IGNIS K15 (PHILIPS) AWF633/IG P.M. SYSTEM INTERNAL VIEW.

The IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM was first Electronic driven motor washing machine featuring  a control circuit for permanent magnet  (PM SYSTEM) or constant excitation direct current motors, particularly for washing machines, characterized by a circuit for regulating the rotational speed of a DC motor. In the modern actual known circuit, a tachometer dynamo is fixed onto the shaft of said motor, said dynamo generating a signal which is proportional to the motor rotational speed and is fed to an electronic circuit which acts on the motor to regulate its speed when required.

In the case of tachometer dynamos, their cost is relatively high and their installation is often laborious and costly.

The main object of the present invention featured in the IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM is therefore to provide an electric motor control circuit which operates accurately without such costly dynamo.

A further object is to provide an electric motor control circuit which enables the motor to operate substantially at constant power within determined limits of torque and rotational speed for safety reason.

During the motor drive time, motor velocity is proportional to the applied energizing voltage for constant loads. As the load of the motor changes the motor velocity will be controlled as a function of applied energizing voltage by sensing the back emf and comparing the back emf signal with a commanded motor velocity signal. By controlling the motor with the back emf, it is thus possible to have a very precise and constant motor velocity for changing loads by varying the level of applied energizing voltage. An advantage of the present invention is thus to provide velocity regulation of a motor that is reasonably constant for a commanded input signal, even though the motor may inherently have poor speed regulation if constant voltage is applied because of D.C. motor. The amount of power a motor is required to deliver has little effect on motor velocity.
To control motor velocity with the Control Unit of the present invention the behavior of a rotating armature in a field to generate a back emf is utilized. If the armature isn't moving through the field, then there is no back emf and the level of any generated back emf is an immediate indication of the operation of the motor (In example when NO self restart of the drum is mandatory performed when stopped during distribution / spind-drain and or spinning). The Control Unit of the present invention does not rely on a signal provided by an independent generator, but rather utilizes the basic operation of the motor. There is also no reliance on the variation in armature resistance, which as explained, may vary with armature construction. Furthermore the speed of the motor is resulting as indipendent of the Mains supply voltage for the aformementioned features.

 The control circuit constructed as briefly described is mainly composed by a command circuit, a control circuit and a power circuit with diodes and thyristors and this circuit complex composition enables the motor rotational speed to be measured as a function of the voltage taken across the motor terminals with due allowance made for the armature losses arising in the motor. In this manner the regulation of said rotational speed is much highly more accurate under any load condition than that which can be obtained by known electric motor control devices and/or circuits. In addition the circuit described in the present patent prevents the motor absorbing mains power to any extent which could lead to mechanical instability of the washing machine.

 

The machine IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  is illustrated in the figures but typically it can comprise a drum mounted on a shaft in bearings so as to be rotatable on a horizontal axis within a liquid containing cylinder which is suspended by means of cooperating springs and dampers within an outer cabinet. A DC electric drive motor of the series-type is secured to the liquid containing cylinder and is drivingly connected by means of a `V` or multi-V belt-drive system to a pulley wheel secured to the drum shaft outside the liquid cylinder. The system is such that the drum is rotated at a speed below the motor speed and in a fixed relationship of say 1:10 or thereabout. Liquid may be supplied to the cylinder through an electromagnetically actuated inlet valve and removed by an electric motor-driven pump. Liquid in the cylinder may be heated by an electric sheathed wire heating element mounted in a lower wall of the cylinder, the heating element being disposed within the cylinder.

In operation of the washing machine its various functions are sequentially controlled by a program controller comprising a synchronous electric timer motor actuating, via a stepping linkage, a number of cams and hence switches which control the supply of electrical power to the various parts of the machine in sequence so as to cause a particular program of operations to be performed on clothes placed in the drum, and a solid state switching circuit, also controlled by the timer motor for the drive motor of the machine, which controls the speed and acceleration of the drum motor.

This invention relates to clothes-washing and spin-drying machines and relates especially though not exclusively to such machines of the type in which clothes can be washed in a drum by means of a tumbling action effected by rotating the drum about a horizontal or at least inclined axis at a relatively low speed in the presence of washing liquid and can subsequently be dried by a spinning operation achieved by rotating the drum about the same axis at a comparatively high speed.

A problem associated with such washing and spin-drying machines is the prevention of excessive out of balance forces on the drum during high-speed spinning due to clothes accumulating at one point in the drum. With lower spinning speeds the problem can be overcome by incorporating a suspension for the outer container of such a design that out of balance forces are absorbed. However, at higher spinning speeds, which are, in any event, desirable for the successful drying of the clothes, this solution is not practicable and arrangements must be made to ensure that the clothes drum is not excessively out of balance during such high-speed rotation. This may be achieved by making the clothes drum such that it is self-balancing-- but that reduces the possible size and hence the capacity of the drum. Alternatively it can be arranged that whenever the clothes drum is required to rotate at a high spinning speed this operation is preceded by rotation of the drum at a low washing speed in the same direction. This solution is not entirely satisfactory, however, as the speed for washing the clothes must be low enough to cause the clothes to tumble and not cling to the drum wall, i.e., the centrifugal force on the clothes must be less than the gravitational force, and as a result the clothes are not evenly distributed around the drum wall, as is desired, if the drum is to be in a balanced condition for the subsequent high-speed spinning operation.

It is therefore desirable that the drum be rotated at a speed intermediate the tumbling speed and the spinning speed for a short time prior to spinning the drum at high speed in order to ensure that the clothes distribute themselves equally around the internal periphery of the drum in a balanced manner. This has been achieved, for example, by providing a drive motor for the drum capable of energization at three speeds, these speeds being selected by a control arrangement for the machine such that, on termination of a tumbling action provided by rotation of the motor at its lowest speed the spin action provided by the motor rotating at its highest speed is preceded by a short period of rotation at an intermediate speed where the weight of the clothes is just balanced by the centrifugal force on the clothes at this speed, the desired result being that the clothes cease to tumble within the drum and contact the inner peripheral wall of the drum in a balanced manner. The drive motor is then accelerated to its highest (spinning) speed. A problem inherent in this arrangement is that there is no certainty that the clothes will distribute themselves in a balanced manner in the drum during the period of rotation at the intermediate speed, as the comparatively rapid acceleration of the drum from tumbling speed to this intermediate speed tends to fling the clothes abruptly outwards to the wall of the drum in the pattern of distribution which they adopt for the previous tumbling operation (which is very rarely uniform). As a result of this the acceleration to spinning speed results in large out of balance forces on the drum.

In a preferred form of the invention design for a combined washing and spin-drying machine a common DC series electric motor is provided for driving the clothes drum both for washing and for spin drying, and the control means includes a motor speed control circuit having means for generating a series of electric pulses of which the conduction angle or mark to space ratio determines the power supply to the motor, and said control means includes time-dependent means for varying said conduction angle or mark to space ratio in such a way as to produce said different accelerations.

Conveniently a controlled semiconductor rectifier device such as a thyristor is provided in series with the electric motor with respect to input terminals which are arranged to be connected to an alternating current supply, electric pulses being arranged to be applied to the gate of the device in appropriate half-cycles of the alternating current supply to fire the device and cause driving power to be supplied to the motor.

The control means in such a case is conveniently formed with solid state control elements, in particular transistors, so connected and arranged as to control the conduction angle or mark-to-space ratio of the pulses applied to the motor from the semiconductor rectifier device.

The control means preferably also includes feedback means which normally tend to maintain the motor rotating with a selected constant slow speed, said time-dependent means being arranged to override the feedback means when a spin drying operation is initiated.

It will be understood that the invention also includes within its scope control units for controlling the speed of an electric motor driving the clothes drum of a clothes-washing and spin-drying machine or a spin-drying machine in accordance with the invention.

 This invention relates to clothes-washing and spin-drying machines and relates especially though not exclusively to such machines of the type in which clothes can be washed in a drum by means of a tumbling action effected by rotating the drum about a horizontal or at least inclined axis at a relatively low speed in the presence of washing liquid and can subsequently be dried by a spinning operation achieved by rotating the drum about the same axis at a comparatively high speed.

A problem associated with such washing and spin-drying machines is the prevention of excessive out of balance forces on the drum during high-speed spinning due to clothes accumulating at one point in the drum. With lower spinning speeds the problem can be overcome by incorporating a suspension for the outer container of such a design that out of balance forces are absorbed. However, at higher spinning speeds, which are, in any event, desirable for the successful drying of the clothes, this solution is not practicable and arrangements must be made to ensure that the clothes drum is not excessively out of balance during such high-speed rotation. This may be achieved by making the clothes drum such that it is self-balancing-- but that reduces the possible size and hence the capacity of the drum. Alternatively it can be arranged that whenever the clothes drum is required to rotate at a high spinning speed this operation is preceded by rotation of the drum at a low washing speed in the same direction. This solution is not entirely satisfactory, however, as the speed for washing the clothes must be low enough to cause the clothes to tumble and not cling to the drum wall, i.e., the centrifugal force on the clothes must be less than the gravitational force, and as a result the clothes are not evenly distributed around the drum wall, as is desired, if the drum is to be in a balanced condition for the subsequent high-speed spinning operation.

It is therefore desirable that the drum be rotated at a speed intermediate the tumbling speed and the spinning speed for a short time prior to spinning the drum at high speed in order to ensure that the clothes distribute themselves equally around the internal periphery of the drum in a balanced manner. This has been achieved, for example, by providing a drive motor for the drum capable of energization at three speeds, these speeds being selected by a control arrangement for the machine such that, on termination of a tumbling action provided by rotation of the motor at its lowest speed the spin action provided by the motor rotating at its highest speed is preceded by a short period of rotation at an intermediate speed where the weight of the clothes is just balanced by the centrifugal force on the clothes at this speed, the desired result being that the clothes cease to tumble within the drum and contact the inner peripheral wall of the drum in a balanced manner. The drive motor is then accelerated to its highest (spinning) speed. A problem inherent in this arrangement is that there is no certainty that the clothes will distribute themselves in a balanced manner in the drum during the period of rotation at the intermediate speed, as the comparatively rapid acceleration of the drum from tumbling speed to this intermediate speed tends to fling the clothes abruptly outwards to the wall of the drum in the pattern of distribution which they adopt for the previous tumbling operation (which is very rarely uniform). As a result of this the acceleration to spinning speed results in large out of balance forces on the drum.

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM DIRECT-CURRENT MOTOR ENERGIZED BY PERMANENT MAGNETS:

 POLYMOTOR ITALIANA 8219 440 01351 (821944001351)

  DC motor including a tubular stator housing having a pair of curved permanent magnets mounted on the inner surface thereof. A pair of magnetic pole pieces each comprising a segment of a cylinder are concentrically mounted in contact with the inner surface of the magnets. The outer circumference of the pole piece is at least 11/2 times its inner surface thereby concentrating the magnetic flux and reducing the stray flux. 

 1. A direct current motor comprising a tubular stator housing and a rotatable rotor member concentrically arranged within said stator housing, first and second permanent magnets each having the configuration of a hollow tube sector and concentrically mounted with their outer walls engaging the stator housing, first and second magnetic pole pieces each comprising a longitudinal segment of a cylinder having nonradial sidewalls defining the circumferential limits of the segment so that the outer circumferential surface of the segment is at least 11/2 times longer than its inner surface, and means for concentrically mounting said first and second segments with their outer surfaces in contact with the inner surfaces of said first and second magnets, respectively, and with their inner surfaces facing said rotor to define an air gap therewith thereby to concentrate the magnetic flux within a given area.

2. A motor as claimed in claim 1 wherein each of said pole pieces are shaped to provide a pair of flat longitudinally extending surfaces, and said mounting means comprises a pair of longitudinally mounted rods for each pole piece and bearing against said flat surfaces.

Description:

The present invention relates to a direct current commutator motor having a tubular stator and energized by permanent magnets.

Such motors are frequently used in cases of low power consumption, for example in toys, in devices for driving electric contacts of automatic machines, and the like. 

However, if higher powers are to be supplied at larger voltages, such as in domestic apparatus, energization by means of electromagnets is still preferred because the rotor can then be magnetized to saturation. The conventional permanent magnets supply a flux density which is considerably lower than the saturation density of iron. For example, magnets made of a material which is known under the trade name of "Ferroxdure" and has been described in British Pat. Specification 747,724, supplies a flux density of approximately 0.4 Wb/m², whereas the saturation density of iron is approximately equal to 1.5 Wb/m². The same power can then be supplied only if the insufficiently magnetized rotor is provided with a larger number of turns and has larger dimensions, which requires a larger quantity of sheet iron. However, this problem does not play a part in low-power motors so that in this case there is no objection to using permanent magnets.

The invention has for an object to provide direct current commutator motors for higher powers energized by permanent magnets which magnetize the rotor to saturation. In order to obtain the simplest possible construction of the stator, the latter should have a tubular from. These tubes need not be laminated and may be readily cut from long iron tubes.

A motor, in accordance with the invention, is characterized in that the permanent magnets are each in the form of a hollow tube sector, the outer wall of which engages the stator and the inner wall of which engages a corresponding pole piece along a contact surface which is larger, and preferably more than 11/2 times larger, than the surface along which the pole piece adjoins the air gap.

Due to the apparently extraordinarily large dimensions of the stator when compared with those of the rotor, however, large permanent magnets can be used. The emanating flux is indeed proportional to the flux-emanating surface of the magnet. This flux is then concentrated by means of the pole pieces and passed on to the rotor. Thus, the pole pieces serve not only to prevent the occurrence of stray flux but also to provide a strong flux concentration. The diameter of the rotor may then be chosen to be smaller for a given power to be supplied. Although the dimensions of the stator become slightly larger, the cost price of the assembly as a whole is reduced.

The invention will now be described more fully with reference to the accompanying drawing, in which:

FIG. 1 shows a motor for low voltages and powers energized by permanent magnets.

FIG. 2 shows a motor for higher voltages and powers energized by electromagnets.

FIG. 3 shows a motor according to the invention for higher voltages and powers energized by permanent magnets.

FIG. 4 shows one of the permanent magnets used. Each of these FIGS. is a sectional view at right angles to the motor shaft.

The motor of FIG. 1 is used for low powers and has a tubular stator 1, two permanent magnets 2 and 3 supplying the energizing flux and a rotor 4. Such motors are generally supplied with a direct voltage of 6 volts to 12 volts. In domestic apparatus, such as textile-washing machines, dough-kneading machines, pumps and the like, powers are required which exceed 100 watts and for which it is desirable to use direct voltages in excess of 100 volts. For the reasons set out above, the energization is supplied by one or more windings 5 (FIG. 2) wound onto a pole piece 6 and electrically energized in series or in parallel with the armature winding or directly by a fixed direct voltage. In this case the pole piece serves to minimize the reluctance of the magnetic flux circuit and the stray flux.

The motor according to the invention is shown in FIG. 3 and is used at the same voltages and for the same purposes as the motor of FIG. 2. The rotor employed may also the the same. If the rotor 16 should be used together with a stator in the configuration of FIG. 1, this rotor would not be saturated and would not be utilized to its full voltage capacity. Instead of increasing the dimensions of the rotor or the number of turns, according to the invention, the dimension of the stator are increased and the configuration of the stator is altered so that the rotor can nevertheless be magnetized to saturation.

The increase of the dimensions of the stator 17 permits of also using larger permanent magnets 7, the flux of which is concentrated through pole pieces 8 and is passed on to the rotor 16. The ratio of the flux density at the air gap to the flux density supplied by the magnet 7 is approximately equal to that of the surface of the inner wall 9 of the magnet 7 to the surface along which the pole piece adjoins the air gap 10 if the flux is not concentrated too far beyond the knee of saturation. The desired dimensions of the permanent magnets, the shape and dimensions of the associated pole pieces and of the stator can thus be found. Ratios of from 1.5:1 up to 3:1 are suitable.

The outer wall 18 of each permanent magnet engages the inner side of the stator 17. The stator may consist of soft iron of soft steel and need not be laminated because the flux variations are small. This also applies to the pole pieces. However, it is sometimes desirable that the pole pieces be made of sheet iron because the passing rotor teeth produce a certain alternating flux. The stator is in the form of a tube. This tube may have a larger length that the magnet. In this case, the same stator reluctance can be obtained with a thinner tube. The tube may be closed at both ends with aluminum discs. The permanent magnets are in the form of hollow tube sectors (FIG. 4) and may be made, for example, of the aforesaid "Ferroxdure," of strontium ferrite or of a suitable alloy. The pole pieces and the magnets may be clamped to the stator, for example, by means of rods 12 secured in the aluminum discs.

As a matter of course, the invention may also be applied to multipolar motors.

A direct current commutator motor having a tubular stator housing, on the inner side of which are arranged curved permanent magnets which are provided with pole pieces, the surface along which the permanent magnets adjoin the pole pieces being larger than the magnetically active surface between the pole pieces and the rotor.
 

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM DRIVING ARRANGEMENT FOR THE DRUM OF A WASHING MACHINE:

 1. In an automatic washing machine including a commutating electric motor for driving the drum of the washing machine at a first comparatively low-washing speed and at a second comparatively high-spin-drying speed, the improvement comprising an automatic speed adjusting circuit for said motor comprising, a pair of input terminals adapted for connection to an AC voltage supply source, a supply circuit for the motor connected to the input terminals and provided with at least two further terminals, an electric heating element arranged to heat the wash water and connected across said two further terminals, a controlled rectifier connected in the supply circuit so as to regulate the motor speed at a given washing speed, and means connecting said two further terminals in the motor supply circuit so that the motor is at least substantially energized through at least a part of the heating element whereby it exhibits a speed characteristic which decreases very sharply with increasing load. 

 1. In an automatic washing machine including a commutating electric motor for driving the drum of the washing machine at a first comparatively low-washing speed and at a second comparatively high-spin-drying speed, the improvement comprising an automatic speed adjusting circuit for said motor comprising, a pair of input terminals adapted for connection to an AC voltage supply source, a supply circuit for the motor connected to the input terminals and provided with at least two further terminals, an electric heating element arranged to heat the wash water and connected across said two further terminals, a controlled rectifier connected in the supply circuit so as to regulate the motor speed at a given washing speed, and means connecting said two further terminals in the motor supply circuit so that the motor is at least substantially energized through at least a part of the heating element whereby it exhibits a speed characteristic which decreases very sharply with increasing load.

2. A washing machine as claimed in claim 1 further comprising a switch by which the further terminals can be directly connected to the input terminals in the cutoff condition of the motor, and means connecting the switch across the series combination of the motor and the controlled rectifier.

3. A washing machine as claimed in claim 2 wherein the supply circuit includes a full wave bridge rectifier, means connecting one of the further terminals to one of the input terminals and another one of the further terminals to one of the input terminals of the bridge rectifier, and means connecting the switch between the two input terminals of the bridge rectifier.

4. A washing machine as claimed in claim 1 further comprising a braking switch by which the motor can be connected across the heating element when the motor supply circuit is interrupted.

5. A washing machine as claimed in claim 1 further comprising means for varying the mechanical load on the motor during a given washing cycle.

6. An automatic speed control circuit for an electric motor subject to a wide variation in load during a normal cycle of operation comprising, a source of supply voltage, said motor having a given speed torque characteristic if connected to said supply voltage such that it exhibits a given speed variation between the expected minimum and maximum values of load, means for varying the load on the motor between said minimum and maximum load values during a normal cycle of operation of the motor, a controlled rectifier connected in series with the motor, means for adjusting the firing angle of said controlled rectifier as a function of motor speed so as to regulate the motor speed at one of said load values, a resistor, and means connecting at least a part of said resistor in series with the motor across said voltage source so that the speed characteristic of the motor is changed to substantially increase said given speed variation between said expected minimum and maximum values of load.

7. A control circuit as claimed in claim 6 for use in an automatic washing machine and further comprising a programming device controlling said load varying means and the wash cycle, means controlled by said programming device for periodically deactivating the motor during a wash cycle, and switching means controlled by the programming device for selectively connecting said resistor directly across the voltage source during the time the motor is deactivated during a wash cycle.

8. A control circuit as claimed in claim 7 wherein said resistor is a heating element located so as to heat the wash water, said circuit further comprising a braking switch for selectively connecting the heating element across the motor in the event that the motor supply circuit is opened.

Description:

This invention relates to an arrangement including a commutating electric motor for driving the drum of a washing machine provided with at least one electric heating element, especially an automatic washing machine having at least one comparatively low-washing speed and also at least one comparatively high-spin-drying speed, which arrangement has a pair of input terminals for connection to a source of supply voltage and a supply circuit for the motor connected to these terminals.

Such arrangements are known and are at present used in most automatic washing machines. At least two widely different speeds (ratios of the order of 1:20 or more are commonly used) are obtained in various manners, for example, by means of two different motors, by means of a kind of gearbox having at least two speeds, by the use of two or more belt or cord drives with different ratios or by a transformer provided with tappings enabling a single motor to be energized with different voltages.

It is an object of the invention to provide a simplified, particularly lightweight and cheap and yet reliable arrangement of the aforementioned kind. The invention is based on the experience that when a self-commutating electric motor is energized through a resistor of sufficient value its load can be increased to an extent such that, it runs regularly at an unexpectedly low speed without exceeding the permissible motor current. In other words, the motor acquires a kind of highly exaggerated series characteristic. The invention is also based on the recognition that just this characteristic is very useful in a washing machine because, during the washing operation, when the tub is full of water which must be kept hot or be heated, the motor is heavily loaded and will consequently run at a low speed and consume much current. As a result, the energy dissipated in a series resistor will be large and may be utilized for heating or keeping the water hot, whereas during the spin-drying operation, when the water has been discharged from the tub, the motor is only lightly loaded and will reach a high speed while consuming little current so that the energy dissipated in a series resistance will be comparatively small and can readily be removed, even without water cooling.

The arrangement in accordance with the invention is characterized in that it is provided, in addition to the aforementioned input terminals, with at least two further terminals for the connection of a heating element of the washing machine. The latter terminals are included in the motor supply circuit so that the motor is at least substantially energized through at least part of this heating element, whereby it exhibits a speed characteristic which very strongly decreases with increasing load.

It should be noted that it is known from the U.S. Pat. No. 1,998,670 to feed an electric motor through a heating element. This patent is however concerned with a fan motor which serves to maintain the air circulation about a heating element of an electric stove in order to provide a better distribution of heated air by forced convection. Consequently, this motor operates with a substantially constant small load and always runs at a normal, comparatively high speed, so that it does not make use of an exaggerated series characteristic and/or of the aforementioned related useful effects occurring in a washing machine.

The invention may be used with any kind of commutating motor: with commutator motors provided with series shunt or compound energization or energization by a permanent magnet fed with smoothed or unsmoothed direct current or with alternating current, or with motors having a rotating permanent magnet, for example, with commutatorless motors provided with an electronic commutator, for example, motors using Hall plates as control elements.

During a washing cycle the load on the motor varies with the amount of washing goods with which the drum of the washing machine is filled and/or with the level of the water in the tub of the machine, whereas the washing effect is an optimum at a given speed of revolution. Therefore the arrangement preferably includes a known control device by which the motor speed is regulated at at least one washing speed. In an arrangement for connection to an alternating voltage supply source, this control device may, for example, include a controlled rectifier by which the motor speed is regulated.

Features and advantages of the invention will appear from the following description of embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram showing the basic elements of a simple embodiment of an arrangement in accordance with the invention,

FIG. 2 shows the speed vs. torque characteristic of the motor of the arrangement shown in FIG. 1 compared with the characteristic of a conventional series-energized commutator motor.

FIG. 3 is a circuit diagram showing the basic elements of an automatic washing machine equipped with a second embodiment of the arrangement in accordance with the invention,

FIG. 4 is a circuit diagram of a third embodiment, and

FIG. 5 is a circuit diagram of a fourth embodiment of the arrangement in accordance with the invention.

In the simplest possible embodiment shown in FIG. 1, the arrangement according to the invention comprises a commutating electric motor 1, for example, a motor with permanent-magnet energization. It further comprises a pair of input terminals 2, 2' for connection to a voltage supply source and a supply circuit 3, 3', 4 for the motor 1 connected to the said terminals. According to the invention the arrangement is provided with two further terminals 5 and 6 for the connection of a heating element 7 of the washing machine. These terminals 5, 6 are included between the parts 3 and 3' of the motor supply circuit 3, 3', 4 so that the motor 1 is energized through the heating element 7.

In a practical embodiment the motor 1 was a motor provided with permanent-magnet energization rated for a DC supply voltage of 220 volts, with a maximum current of 6.4 amperes at a heavy load and designed for driving the drum of a washing machine at a spin-drying speed of 800 revolutions per minute. The heating element 7 had a resistance value of 32 ohms and was proportioned to be likewise connected to a 220 volts supply voltage in the case of water cooling.

Line A of FIG. 2 shows the speed-torque characteristic (speed n as a function of the load torque K) of the motor 1 of the arrangement shown in FIG. 1 when supplied with a direct voltage of 220 volts through the heating element 7 having a resistance value of 32 ohms.

Curve B of FIG. 2 shows, by way of comparison, the characteristic of a conventional series-energized commutator motor supplied directly with a direct voltage of 220 volts.

At a small load, which corresponds to the spin-drying operation, the motor 1 runs at a speed of 800 revolutions per minute and this speed can increase only by a small amount (to about 900 revolutions per minute) at a theoretical zero load torque. Under a heavy load (k=8, which corresponds to a current of 6.4 amperes) this motor runs at a constant speed of only 50 revolutions per minute. The attained speed ratio is thus 16 to 1.

By way of comparison the curve B of FIG. 2 shows that with a conventional series-energized commutator motor directly fed with its rated voltage, the ratio between normal speed at a small load, which corresponds to the spin-drying operation (K=1), and the speed at the maximum permissible load (K=8) is not even 2 to 1.

In a washing machine the characteristic A provides many important advantages:

a. changing from a low-washing speed to a high-spin-drying speed or vice versa can be automatically effected by decreasing or increasing the load by draining or filling the tub with water.

b. The peak starting current of the motor is limited by the resistance of the heating element.

c. Acceleration to the spin-drying speed is very gradual, especially if the motor is started before the tub has been completely drained. Consequently, the mechanical starting shock is heavily damped or even entirely suppressed while the articles to be washed are distributed about the drum in an optimum manner since the speed increases slowly during the draining of the tub.

d. The resistance of the heating element prevents the motor from reaching an excessive spin-drying speed, for example, in the case of an abnormally high-supply voltage, and protects the arrangement in the case of a short circuit of the motor and/or of its supply circuit and/or if the drum locks.

e. The energy dissipated in the heating element is largest during the washing operation when the water in the tub must be heated or kept hot, but during the spin-drying operation it is so small that it can readily be carried away by the air then contained in the tub without inconvenience for the element, the machine and/or the articles being washed.

f. Finally, when the supply circuit of the motor is interrupted, the motor can rapidly be brought to a standstill by short circuiting it through the heating element so that much more costly protection devices can be economized.

The automatic washing machine the basic circuit diagram of which is shown in FIG. 3 includes a second embodiment of the arrangement in accordance with the invention. In this embodiment the motor supply circuit includes a first changeover switch 8, for example, in the form of a relay changeover contact, by means of which the heating element can be directly connected across an alternating-voltage supply 2, 2' to speed up the heating of the water contained in the tub of the machine. This supply circuit includes, in series with the switch 8, a double-pole changeover switch 10, 10', for example, likewise in the form of relay changeover contacts capable of reversing the direction of the current flowing through the motor 1 and hence the direction of rotation of this motor, and a controlled semiconductor rectifier or thyristor 9 by means of which, at at least one washing speed, the motor speed is regulated by simple controlled rectification of the current flowing through the heating element 7 and the motor 1.

Apart from the above-described arrangement the automatic washing machine includes a motor governor 11 by which the thyristor 9 is controlled during the washing operation so that the motor 1 drives the drum of the machine at a substantially constant speed of, say, 50 revolutions per minute. The machine further includes a reversing circuit 12 which controls the switches 8 and 10, 10' so that, during the washing operation the motor 1 alternately and with time intervals rotates in one direction and then in the other direction whereby, during the heating and during the time intervals, the switch 8 can be brought into its lower position so that, if required, a larger electric power is dissipated in the heating element.

The automatic washing machine is provided with a second motor 13 which drives a water pump capable of draining the machine tub. This motor is controlled by a switch 14, for example, a relay contact, which is in turn controlled by a programming device.

The programming device, which also is shown diagrammatically only, comprises a cycle counter 16 by which three electronic switching devices are operated in the correct sequence:

a filling device 17 by which two water supply valves 18 and 19 are opened in a predetermined order and are closed again when the water in the tub reaches a level determined by a detector 20;

a heater 21 by which the thyristor is cut off when the temperature of the water in the tub measured by a transducer 22, for example, a NTC resistor, reaches a predetermined value, for example, 90° C.;

a pump control device 23, which is controlled by a second water level detector 24.

The cycle of operations of the reversing circuit 12 is also controlled by the cycle counter 16.

The automatic washing machine is provided with a switch 25 which is rendered operative by the pump control device 23 and switches off the machine when the water level measured by the second level detector 24 becomes zero during the spin-drying operation. Finally, the system includes a safety switch 26.

The automatic washing machine described can carry out, for example, the following program:

After switching on, the first program cycle (preliminary washing) commences: the tub is first filled with water, with the addition of a washing agent as the case may be, through the first valve 18.

At the instant at which the correct water level is reached, the motor 1 is started through the cycle counter 16 and under the control of the heater 21 and the transducer 22. The operating cycle of the reversing circuit 12 is such that the motor runs alternately in both directions for periods of 12 seconds with time intervals of 3 seconds. The temperature rises slowly because the heating element 7 is directly connected to the input terminals during the short time intervals only, during which it dissipates a power of, say 3 kilowatts, whereas with a running motor its dissipation is restricted to, say, 1 kilowatt. When the temperature of the water reaches a value of, say, 30° C. the motor 13 is switched on through the counter 16 by the switch 14 and under the control of the device 23 and the second level detector 24 which switches it out again as soon as the tub is empty, whereby the motor 1 can be switched out if desired, for example, by 21, 22, but this is not necessary.

The second program cycle (washing) proceeds similarly to the first, with the difference that the tub is now filled through the second valve 19, with washing agent added, and that the cycle of operations of the reversing circuit is changed through cycle counter 16, for example, to running for periods of 3 seconds in alternate directions with time intervals in-between of 12 seconds, and that a different temperature limit of, say, 90° C. can be chosen for this program cycle.

The third program cycle (rinsing) proceeds similarly to the first, with the sole difference that the tub is filled again through the second valve 19, but without the addition of washing agent.

The next few (for example, three) program cycles (rinsing) proceed similarly to the third but without heating during the intervals and without the use of the temperature limit, the step controlled by elements 21, 22 being skipped.

The last program cycle (spin-drying) consists in that the motor governor 11 switches to the spin-drying speed before the tub is fully drained by the motor 13. In this process the reversing circuit 12 is rendered inoperative by the cycle counter 16 and a power of only about 150 watts is dissipated in the heating element 7.

When the supply of water to the tub from the drum and from the washing goods ceases, the machine is switched off by the switch 25 and all its components return to their respective rest positions, in which they remain until the machine is started again. If the machine is inadvertently opened during operation, the door or cover automatically switches the safety switch 26 from the operative position shown to the other position in which it interrupts the lead 4 of the supply circuit and short circuits the motor 1 through the heating element 7, the switch 8 and the reversing switch 10, 10' so that the motor is vigorously braked by this circuit and is brought to a standstill within a very short time (of the order of 3 seconds) even from the highest spin-drying speed.

It should be noted that the motor can also be stopped by cutting off the thyristor 9, in which case no electric power is supplied to the heating element 7 during the intervals. It will have attracted notice that the described automatic washing machine does not include any of the otherwise commonly used time-measuring devices. The cycle counter 16 is simply switched from one cycle to the next under the control of the transducers 20, 22 and 24, and the time-measuring device is replaced by an accurate temperature transducer 22. This provides equally satisfactory or even better washing results than with the use of a more expensive time-measuring device.

FIG. 4 shows a third embodiment of the arrangement in accordance with the invention. This embodiment mainly differs from that shown in FIG. 3 by the inclusion of a full-wave rectifying bridge circuit 30 between the input terminals 2, 2' and the motor supply circuit 3, 3', 4 provided with the further terminals 5 and 6, between which the heating element 7 is shown. Furthermore, the changeover switch 8 of FIG. 3 is replaced by a short-circuiting switch 8', and a flywheel diode 31 is connected across the motor 1 and the reversing switch 10, 10'.

By the use of the supply rectifier 30 the power supplied to the motor and to the heating element 7 through the thyristor during each half cycle of the AC supply voltage is about doubled so that the motor 1 can produce a higher torque, even with increased dissipation in the heating element 7.

The flywheel diode 31 ensures that the thyristor 9 is extinguished between successive half cycles of the AC supply voltage and of the rectified voltage across the output terminals of the full-wave rectifier 30. It may also contribute somewhat to the improvement of the control properties and of the form factor of the arrangement, at least at certain speeds. An embodiment of the motor governor similar to the motor governor 11 of FIG. 3 is shown in detail in FIG. 4. The motor 1 is switched off by means of a switch 32, by which the control electrode of the thyristor 9 can be directly connected to its cathode so that the thyristor can no longer be fired. If electric energy is to be dissipated in the heating element 7 with the motor stationary, the switch 8' can be switched on.

The control electrode of the thyristor is also connected to its anode through a resistor 33 of, say, 4.7 kΩin series with three Zener diodes 34 having an overall Zener voltage of, say 225 volts and with a diode 35 connected in the forward direction. A control circuit is connected to the junction point of the diode 35 and the Zener diodes 34. This comprises a second diode 36 connected in the forward direction and two further Zener diodes 37 each having a Zener voltage of 7.5 volts. A control switch 38 is connected to the negative lead 4 of the motor supply circuit. This switch has four positions. In its first position a it connects the end of the control circuit 36, 37 remote from the diode 35 to the lead 4. The firing of the thyristor 9 through the circuit 33, 34, 35 is then delayed by the control circuit 36, 37, so that the motor 1 runs at a controlled normal washing speed of 50 revolutions per minute stabilized by the counteraction of its back E.M.F. in the cathode circuit of the thyristor 9.

In its second position b the switch 38 connects the junction point of the two Zener diodes 37 to the lead 4 so that the firing of the thyristor 9 is even more delayed by the circuit 36, 37. The back E.M.F. of the motor 1 is compared now to the forward voltage across only one of the Zener diodes 37. Accordingly the motor 1 runs at a stabilized, particularly low-washing speed of only 25 revolutions per minute.

In its third position c the switch 38 connects the cathode of the diode 36 to the lead 4 through a resistor 39 of, say, 4.7 kΩ, the Zener diode being short circuited by a switch 40 which is coupled to the switch 38. The back E.M.F. of the motor 1 is then compared to the voltage drop across the resistor 39. If this back E.M.F. is equal to zero (for example at starting), the thyristor 9 becomes conductive as soon as its anode voltage exceeds the sum of the voltage drop across the resistor 33, the threshold voltage of the diode 35 and the threshold voltage of the path between its control electrode and its cathode. The resistor 39 is chosen such that the motor 1 is accelerated to a reduced spin-drying speed of 350 revolutions per minute and continues running at this stabilized speed.

In the positions a and b of a practical embodiment of the arrangement the variations of the motor speed due to load variations (between K=1 and K=8 in FIG. 2) and to variations of the AC supply voltage of ± 10 percent were between -4 and +6 percent, and the speed variations due to variations of the ambient temperature between 26° and 61° C. were between -0.6 percent and +2.1 percent.

In its fourth position d the control switch 38 is open and renders the control circuit 36, 37 inoperative while the Zener diodes 34 are short circuited by the switch 40. The thyristor 9 begins to conduct as soon as its anode voltage minus the back E.M.F. of the motor 1 exceeds the sum of the threshold voltages of the diode 35 and of the control electrode-cathode path of the thyristor. The motor 1 is supplied with substantially complete half cycles of the AC supply voltage and is accelerated at an even higher rate than in the third position of the control switch 38. It reaches a spin-drying speed of 725 revolutions per minute and continues running at this speed.

FIG. 5 is a circuit diagram of a fourth embodiment. In this embodiment the rectifying bridge 30 of FIG. 4 is replaced by a rectifying bridge 30' the output terminals of which are directly connected to the input terminals of the reversing switch 10, 10'. The bridge input terminals are connected to the input terminal 2' of the device through the lead 4 of the motor supply circuit and to the further terminal 6 through the lead 3' of the same supply circuit, respectively. In addition, the switch 8' of FIG. 4 is replaced by a changeover switch 8" connected between the input terminals of the rectifier bridge 30'. This provides the advantage that the rectifier 30' need not supply the high-heating power to the heating element 7 when this element is connected to the full supply voltage through the switch 8". Consequently, the heating element 7 is always fed with alternating current.

The arrangement includes a third further terminal 6' to which a tapping of the heating element 7 is to be connected and which can alternatively be connected to the further terminal 5 in the absence of such a tapping. The motor governor 11 of FIG. 3 or 33-40 of FIG. 4 is here replaced by a two-position governor provided with a switch 11' by which either part or the whole of the heating element 7 can be short circuited when the rectifier 30' is not short circuited. This switch can, for example, be a normally open contact of a relay energized by an adjustable portion of the back E.M.F. of the motor 1 or of the voltage delivered by a tachogenerator (NOT IN PM SYSTEM) .

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  METHOD OF SWITCHING A DIRECT-CURRENT MOTOR OF A WASHING MACHINE:

  A circuit arrangement for a direct-current motor for a washing machine, which motor is equipped with permanent magnets for starting the spinning operation from a predetermined direction of rotation of the oscillatory washing movement for the washing operation, irrespective of any manual operation of the timer. The operation of the timer and of the voltage change-over device of the motor are effected independently of one another by means of one or two motors. The arrangement may be used in washing machines equipped with direct-current motors which permit of starting the spinning operation either with the tub filled or with the tub empty.

1. A washing machine comprising, a direct-current motor for driving a drum of the washing machine at a low washing speed in two directions of rotation and at a high spin-drying speed in one direction of rotation, a timer for controlling the sequence and the time duration of the various washing machine operations, a reversing switch which includes first switching means for selectively controlling the electric supply for the motor so as to provide switching to the low washing speed and two directions of rotation and for switching to the high spinning speed, said timer controlling second switching means which control the motor electric supply and the energization of the reversing switch and which short-circuit said first switching means having the same functions but appertaining to the reversing switch, means driven by the timer for initially rendering said second switching means inoperative when switching the machine from a low speed wash cycle to a high speed spin cycle, whereupon the part of said first switching means appertaining to the reversing switch are rendered inoperative at an instant determined by the

2. A washing machine as claimed in claim 1, characterized in that the timer and the reversing switch are independently driven by appropriate means.

3. A washing machine as claimed in claim 2, characterized in that the timer and the reversing switch are driven by at least one alternating current

4. A washing machine control system comprising, a reversible DC motor for driving the washing machine drum at a low reversible wash speed and at a high spin-drying speed in one predetermined direction of rotation, reversing switch means that includes first, second and third switching means coupled to the motor terminals, to the motor electric supply, and to a control winding for controlling the reversing switch means, respectively, said first switching means controlling the direction of motor rotation, said second switching means controlling the motor speed and said third switching means controlling said control winding, a timer for controlling the sequence of washer operations and the time duration thereof and including fourth and fifth switching means connected in parallel with said second and third switching means, respectively, said timer being operative to open said fourth and fifth switching means prior to the start of a spin-drying cycle so that said second and third switching means assume control of the motor speed and the reversing switch, respectively, said second and third switching means then being operated in a predetermined relation to the operation of said first switching means to a condition to provide said predetermined direction of motor rotation whereby said second switching means adjusts the electric supply to provide said high spin-drying speed and said third switching

5. A control system as claimed in claim 4 further comprising a pair of input terminals connected to a source of AC supply voltage, rectifier means coupling said AC supply terminals to the motor via said first switching means to provide a reversible DC voltage to the motor, and means connecting said parallel connected third and fifth switching means in

6. A control system as claimed in claim 5 wherein said timer is arranged to close said fourth and fifth switching means during a wash cycle thereby to operate the motor alternately in both directions of rotation and at said low washing speed.

Description:

This invention relates to a device for switching a direct-current motor intended for driving a drum of a washing machine at a low washing speed in two directions of rotation and at a high spin-drying speed in one direction of rotation. In this device use is made of a timer which determines the sequence and the durations of the various operations, while a reversing switch is provided which includes switching means for the electric supply of the motor, both for switching to the low washing speed in two directions of rotation and for switching to the high spin-drying speed.

In known washing machines the oscillatory rotation movement of the wash-drum is obtained by reversing the direction of rotation of the motor of the machine. It is also known for a washing machine to be driven by a change-pole alternating-current motor in which, by changing over the poles, two speeds are obtainable, the washing speed and the spin-drying speed, the latter being considerably higher than the former. The reversal of the direction of rotation of the motor at the washing speed is achieved by means of a reversing switch included in the control unit of the machine. In automatic or semi-automatic washing machines this control unit ensures the sequence and the duration of the operations to be performed according to a selected program, such as washing, heating, rinsing and spin-drying. In such a cycle, switching from washing to spin-drying is to be effected when the reversing switch is out of the circuit. Frequently this will give rise to locking of the drum because the reversing switch is rendered inoperative before the change-over to the spin-drying speed has been effected.

The commonly used control units comprise a timer which determines the sequence and the duration of the operations and a reversing switch. The timer and the reversing switch are mechanically coupled together and are driven by a single motor. This embodiment permits a saving both in the space occupied and in material used.

In the so-called "thermostatic" machines, the timer is stopped during the heating period, i.e. during the time in which the wash-water has not yet reached the desired temperature. However, during this time, the wash-water must continue to be agitated and hence the wash drum has to perform its oscillatory movement. Consequently, during the stationary period of the program, another driving device is required to rotate the cams which control the reversing contacts until the desired water temperature has been reached. In the timers available so far, either a device which disengages the program part or a two-speed motor is used. The part of the timer which controls the reversal of the movement generally comprises a limited number of switches since the reversal of the direction of rotation in alternating current motors requires only single-pole commutation.

In washing machines equipped with direct-current motors, the motor can be made to run not only in two directions but also at different speeds by merely controlling the electric supply. Although this a highly interesting property, realization gives rise to great switching and safety problems. This problem may be explained with reference to FIGS. 1 and 2 of the accompanying diagrammatic drawings.

The invention will now be described in greater detail with reference to the accompanying drawing, in which:

FIG. 1 schematically shows a double pole switching arrangement for a DC motor,

FIG. 2 schematically shows a modified form of the arrangement of FIG. 1,

FIG. 3 shows a preferred form of the invention, and

FIG. 4 illustrates the cyclical operation of the various switches of the arrangement of FIG. 3.

Double-pole switching of a direct-current motor is shown schematically in FIG. 1. In order to reverse the direction of rotation of the motor, the polarity of the voltage at the motor terminals is reversed by closing either the switches 1 and 3 or 2 and 4.

For example, to bring the wash drum from the washing speed (say 50 rev/min) to the spin-drying speed (from 200 to 600 rev/min.) it is sufficient to change the supply current at the motor terminals and to render the reversing arrangement inoperative. If the timer is equipped with a single motor, the reversing switches will rotate continuously. Hence the reversing arrangement must be rendered inoperative, resulting in a circuit diagram as shown in FIG. 2. In this circuit arrangement the program part comprises two switches 15 and 16 which are present to enable the supply circuit, including the reversing switches, to be interrupted, and two switches 17 and 18 which must be closed to feed the motor so as to obtain the required spin-drying speed and the proper direction of rotation, which must be maintained during the entire spin-drying period. The switches 15, 16, 17 and 18 are controlled by the timer. However, they may lead to an uncontrolled speed when the timer button is manually operated, and they also may cause the wrong polarity to be switched into circuit when the polarity has not yet been reversed. The broken lines of FIG. 2 show the paths which the current takes when the switches are too quickly operated.

Before the spinning period begins the switches 15 and 16 are closed and the motor is fed through switches 12 and 14. The negative polarity then occurs at 14 and the positive polarity at 12, which is also the case at one of the contacts of the switches 17 and 18. When the latter switches are closed, a double short-circuit occurs, namely in the circuit including the elements 17, 15 and 14 (the switch 17 closes, the switch 15 has not yet been opened and the switch 14 is in the closed position) and also in the circuit including the elements 12, 16 and 18 (the switch 18 closes, the switch 16 has not yet been opened and the switch 12 is in the closed position).

Since the electric supply for the direct-current motor is taken from the alternating-current lines through a rectifier bridge comprising semiconductor elements, the latter will act as fuses and the supply arrangement of the motor will be badly damaged.

The problem of changing the speed and reversing the direction of rotation of a direct-current motor by means of a timer in which the functions "sequence and duration" and "reversal" are combined would appear to be insoluble when very fast operation of the reversing switches by manual turning of the times button is possible.

It is an object of the present invention to avoid this disadvantage and to make the switching of the sequence and duration independent of the reversal. The invention is characterized in that in switching from the washing speed to the spinning speed, initially switching means, which appertain to the timer and control the motor supply and the drive of the reversing switch, and which short-circuit switching means having the same functions but appertaining to the reversing switch, are rendered inoperative by means driven by the timer, whereupon the said switching means appertaining to the reversing switch are rendered inoperative at an instant which is determined by the reversal of the direction of movement of the wash-drum. The arrangement according to the invention ensures that the spinning operation is started under predetermined conditions, and that the direct current is switched by means of a reliable device operating with a high degree of safety, irrespective of any manual operations.

British Pat. specification No. 244,026 describes a washing machine including a control arrangement for reversing the direction of rotation of the motor independently of the program arrangement which determines the duration of the various stages of the washing cycle and also the supply of water and the washing ingredients. Each of these arrangements includes a drum provided with segments which is driven by a motor and travels past carbon brushes which control the various operations. The safety of the circuits upon reversal of the direction of rotation of the motor is ensured by switching into circuit electric starting resistances by means of the drum switch which determines the reversal of the movement. The reason for separating the operation of the timer and of the reversing switch is to permit the wash drum to be stopped with its door registering with the door of the machine. No provision is made for a spin-drying operation and hence for variation of the motor supply voltage.

In an embodiment of the present invention, the washing machine includes a direct-current motor equipped with permanent magnets. The motor is fed from the alternating current supply through a known supply arrangement providing current rectified by semiconductor elements. The automatic coordination arrangements which are used for performing the reversing and timer functions and which usually are controlled by a single alternating-current motor are separated so as to be independent of one another, the reversing arrangement and the timer arrangement each being operated by a separate motor. The use of alternating-current motors for these automatic coordination devices provides the advantages of simple design and at the same time of a particularly constant speed, e.g., by using a synchronous motor.

The method and the arrangement according to the invention will now be described more fully with reference to a circuit diagram shown, by way of example, in FIG. 3. The switches represented by two parallel lines form part of the reversing arrangement and those represented by a single line form part of the timer. The reversing switches 21 and 23 relate to a first direction of rotation during the washing operation and to the preferential direction of rotation during spin-drying, and the switches 22 and 24 relate to the second direction of rotation during the washing operation.

Furthermore, it is assumed that spinning is started while the tub still is filled with water.

It is desirable to have a preferential direction of rotation for the spinning in view of certain constructional details of the machines, one such detail being that the location of the draining system of the machine permits it to be emptied faster when the drum rotates in a predetermined direction.

Starting of the spinning in a preferential sense is a known problem, the solution of which will be different for different electrical arrangements used.

The reversing switch 25 controls the AC supply of a motor M. When this switch 25 is closed, the characteristics of the current supplied to the motor correspond to the washing speed. When the switch 25 is open, these characteristics correspond to the spinning speed. The switch is opened in an accurately determined condition of the reversing arrangement (for example, when the switches 21 and 23 are closed).

In order to maintain a given direction of rotation during spinning, the motor of the reversing arrangement is stopped by opening the switch 26. The switch 27, which controls the pump for draining the tub, is closed when the motor of the reversing arrangement is stopped. This switch 27 may alternatively be operated by the timer part when spinning is started with the tub empty.

The switches 25', 26' and 27' are the timer switches which provide for normal operation when spinning is not required.

The machine operates as follows:

Washing: the switches 25, 26 and 27 are short-circuited by switches 25', 26' and 27' which are controlled by the timer with the reversing arrangement rotating; the direct-current motor operates in a predetermined rhythm in two directions of rotation.

Spinning: the start of a spin cycle is effected in two stages. First the timer orders the timer switches 25', 26' and 27' to be opened. The switch 26 of the reversing motor remains closed, and the voltage corresponding to the washing speed continues to be applied to the direct-current motor, while the reversing motor continues to rotate.

At a given instant of the reversing cycle (when the switches 21 and 23 are closed) the switch 25 is opened (see FIG. 4) so that the spinning operation may start and then the switch 26 is opened so that the reversing motor is stopped. Opening the switch 25 ensures the start of the spinning operation. As soon as the reversing motor stops (in response to the open condition of switch 26), all of the reversing switch contacts remain in the positions shown in FIG. 4 with switches 25 and 26 open, switch 27 closed, switches 21 and 23 closed and switches 22 and 24 opened. The spin cycle continues until the timer orders a new set of conditions by operating the timer switches 25', 26', and 27'.

FIG. 4 shows the reversing cycle and the positions of the various switches of the reversing arrangement during this cycle, i.e., the program of the reversing switch and the condition of its various contacts, open or closed, brought about by the reversing switch cam discs during their rotation. The opening and closing of these contacts have no effect as long as the corresponding timer contacts such as 25' and 26' remain closed.

Contacts 25' and 26' open only if the timer orders a spin cycle and then the reversing switch alone takes over briefly to insure that the spin cycle will begin only if contacts 21 and 23 are closed and 25 is open. Switch 26 then opens shortly thereafter to stop the reversing switch motor whereupon the various reversing switch contacts are held in position until the timer takes over control of the remaining operations in the washer program cycle via the timer switches such as 25', 26' etc..

The reversing arrangement is of conventional design: a shaft which is integral with a motor (1 rev/min) carries cams the protuberances of which operate either directly or through levers upon a contact element. The protuberances which effect the closure of the switches 21 and 22 are arranged at diametrically opposed points on the same cam, a second cam carrying the protuberances which operate the switches 23 and 24. The protuberances which operate the switches 21 and 23 are rigidly disposed opposite one another. The contact period, i.e., the time of rotation in the same direction is 12 seconds and is followed by a stationary period of 3 seconds. The cams which ensure switching on of washing and spinning operations (switch 25) and stopping of the reversing motor (switch 26) ensure a permanent contact during the entire time of rotation except for a short interval during which the switch 25 is open to enable the application of the spinning voltage while, only fractions of a second later, the switch 26 is opened, which enables the reversing arrangement to be stopped. The recesses of these cams are rigidly arranged in the center positions of these protuberances for the switches 21 and 23 which provide the preferential direction of rotation. The interval between the instants at which the switches 25 and 26 are opened enable the reversing motor to be stopped as soon as the spinning speed has been switched on.

The cam which carries the protuberance for operating the switch 27 is located opposite the recess of the cam operating the switch 25 and ensures the starting of the draining pump and also the starting of the spinning operation.

The switch 27' is provided only if it is desired to drain the tub on termination of a washing operation without subsequent spin-drying or if draining of the tub is to commence before spinning is started.

The advantages of this method of starting from the washing speed to the spinning speed are many.

The starting of the spin-drying operation is tied only to the reversing arrangement. Manual operation of the timer does not influence the manner of switching of the spinning operation (since the operation of the reversing arrangement is separate from that of the timer).

In this manner the problem of switching for reversal is simplified as far as possible since the system uses a smaller number of contacts than the circuit arrangement of FIG. 2, and moreover, complete safety is obtained, preventing a short-circuit.

In a conventional reversing arrangement it would not be possible to obtain intervals of precise duration as short as one second, for the diameter of the cams is comparatively small (about 15 mm). In the reversing arrangement according to the invention, however, this diameter is about 60 mm, while the motor speed is 1 rev/min, so that a second corresponds to about 3 mm of the circumference. Thus, if short-duration intervals are desired, a cam having a diameter of this order may be notched with a sufficient degree of accuracy.

In another embodiment of a washing machine operating in the aforedescribed manner, the timer and the reversing arrangement are independently driven by a single motor by means of a known appropriate gearing which may be mechanical, electromagnetic, electronic or hydraulic.

Such a switching method may be used in washing machines equipped with a direct-current motor which may be switched to spinning speed either when the tub is filled or when it is empty.

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  Device for controlling the spin-drying speed in a washing machine:

 Device for controlling the spin-drying speed in a washing machine having a d.c. motor. During spin-drying, the motor speed is limited by a resistor in a control circuit. During acceleration of the motor to spin-drying speed, the speed is limited to a minimum spin-drying speed by a water level sensing switch contact connected to the resistor. 

 1. In a washing machine of the type comprising a tub, a drum mounted for rotation within the tub, a d.c. motor for driving the drum at least at a low washing and a high spin-drying speed, a water level control device, switching means for changing from washing speed to spin-drying speed while the tub is filled with water, means for setting a maximum spin-drying speed, a motor supply control device, and electric speed regulator means responsive to the setting means for controlling said motor supply control device, an improved spin-drying control device comprising a switch contact responsive to the level of water in the tub, and wherein said setting means comprises a variable resistor, said speed regulator being responsive to the setting of a circuit comprising said switch contact connected to said variable resistor.

2. A device as claimed in claim 1 wherein said switch contact is connected in parallel with said resistor, the contact being closed when the tub is full of water, and the speed regulator response is such that minimum resistance of the variable resistor corresponds to minimum spin-drying speed.

Description:

The invention relates to a device for controlling the spin-drying speed in a washing-machine which comprises a motor for driving the drum, which motor can operate at two different speeds: a low washing speed and a high spin-drying speed; switching means which enable the passage from the washing speed to the spin-drying speed while the tub is filled with water, a water level control device, a variable resistor by means of which the maximum spin-drying speed can be determined via a motor supply control device which is controlled by a speed regulator.

From French Patent Specification No. 2,044,540, to which U.S. application Ser. No. 34,727, filed May 5, 1970, assigned to the assignee of this application, and now abandoned, corresponds, a washing-machine is known in which a distributing speed is obtained without the use of the additional speed changing device of a conventional motor which, in addition to windings for the low and high speeds, comprises a winding for each of the other speeds. In a machine according to that patent the motor torque is predetermined in such a way that when the electrical parameters which correspond both to the spin-drying speed and to a limited torque are applied to the motor, the motor speeds up and attains a speed which cannot increase as long as the total mass consisting of the drum, the load of laundry and the water contained in the tub is driven by the motor. The torque developed by the motor is counter-balanced by the reactive torque as a result of said total mass. Subsequently, while the tub still contains water, the drum speed will increase to a given value for which the motor torque equals the reactive torque produced by the braking effect of the water as a result of the friction of water between the walls of the drum and the tub. If the water level in the tub is maintained, said speed will remain constant. By the partial or complete drainage of the water, thus reducing the counter-torque, a new level or the spin-drying speed can be attained. The electrical characteristics are substantially those of the motor and its power supply device, while the mechanical characteristics include the dimensions of the tub and the drum, the interior and exterior profiles of the drum, and the distance from the wall of the tub to that of the drum. The interior profile of the drum will influence the laundry movement and thus the length of time that the drum speed is kept constant for evenly distributing the laundry along the drum wall.

When said first period of constant speed is passed, the acceleration of the drum will have to be substantial so as to pass through the critical speed range as rapidly as possible. In the critical speed range, which varies per machine, the slightest unbalance of the load causes vibrations whose amplitude may increase in time and which may cause damage both to the housing and to the equipment attached thereto. Once said range is passed, though the rotation of the drum is accompanied by vibrations, they will be of sufficiently low amplitude not to present any problems. Moreover, beyond said range of critical speed the drum speed stabilizes and remains constant as long as the water level in the tub remains constant. In the example of the aforementioned French patent, said level is utilized for balancing, which is effected by the addition of unbalance-compensation masses, generally by filling compartments in the drum with water. The laundry distribution speed level, which occurs at approx. 50 rpm, is maintained comparatively briefly and its duration cannot be controlled in a simple manner because it is produced by a torque which varies in time, and which is owing to the unstable equilibrium obtained between the driving torque of the motor at spin-drying speed and the reactive torque as a result of the rotation of the total mass contained in the tub. In a washing-machine which employs that feature, the speed level is unlikely to be sufficiently large to ensure the optimum distribution of the mass of laundry, which in itself is not a major drawback because a subsequent balancing phase is provided. The main advantage is that the distribution speed level is obtained without special means, simply through suitable control of the driving torque of the motor at washing speed and mechanical features such as the dimensions of the drum, of the tub, and the water volume.

The invention evolves from the previously cited Specification but its object is to obtain a speed level which is maintained at a speed lower than the critical speed range as long as desired. The balancing speed of 100 rpm to which the level of the previous Specification automatically adjusts itself necessitates a special construction which is conceivable when a machine is concerned with a high spin-drying speed (600 rpm) which must have a particularly good stability. Especially the water tightness of the tub must be very good, in order to withstand the overpressures which may be produced whilst the drum rotates at 100 rpm with 12 liters of water in the tub.

The device according to the invention allows the speed level to be controlled, requiring only a minimum number of additional elements. The device consists of a single low-priced element: a contact which is controlled by the water level, passing from the spin-drying speed with filled tub to the spin-drying speed being effected automatically as the water is drained from the tub.

The spin-drying speed control device in a washing-machine of the type which comprises a drive motor for the drum, which motor can operate at two different speeds: a low washing speed and a high spin drying speed, switching means which enable the passage from the washing speed to the spin-drying speed while the tub is filled with water, a water level control device, a variable resistor by means of which the maximum spin-drying speed can be determined via a motor supply control device which is controlled by a speed regulator, is provided by a speed regulator for a d.c. machine drive motor, the device including a variable resistor which determines the selected maximum spin-drying speed, said variable resistor being short-circuited by a delayed contact.

In different embodiments:

said delayed contact which short-circuits the variable resistor is provided in the water-level control device.

said delayed contact is a contact of a device which controls the water level in the tub.

said delayed contact is constituted by a second water-level control device.

said delayed contact is a timer contact.

The following descriptions and drawing are given by way of example in order that the invention be more fully understood.

The sole FIGURE of the drawing is a simplified electrical diagram of an embodiment of the invention.

The diagram shows a permanent-magnet d.c. motor 1. Said motor can be energized via a bridge rectifier 2 which comprises two diodes and two thyristors. The motor speed is regulated and controlled by a speed regulator 3, which device controls the motor supply via the control electrodes of the thyristors. A contact 4 which belongs to the timer is connected in parallel with the contact of the water-level control device 5 (pressostat) in the closed position, i.e. tub filled with water. A variable resistor 6 is included in series in the motor supply control circuit and limits the control current to such a value that the motor can attain the fixed spin-drying speed. The device for reversing the direction of rotation of the motor is represented by the contacts 7, 8, 9, 10, which by the alternate closure of 7, 8 and 9, 10 change the polarity at the motor terminals. The contact 12 which is included in the motor supply circuit at the spin-drying speed belongs to the reversing device and dictates the direction of rotation of the drum during spin-drying.

The device according to the invention is in particularly destined for a washing machine which comprises a motor 1 with a commutator which is supplied via a resistor 13, which resistor is used for heating the suds. The value of said resistor is selected so that the motor load may be as high as required without the permissible motor current being exceeded and such that the motor can rotate at a uniform speed, which speed decreases as the load increases. The motor will then have a high current consumption and the substantial power which is dissipated in the series resistor is used for heating the water.

In an embodiment of the device for driving the drum of a washing-machine, the permanent magnet d.c. motor 1 is supplied from the electric a.c. mains by a diode rectifier bridge 2 via a control device which in the diagram is represented by two thyristors. The application or interruption of the d.c. supply is effected via the control electrodes of the thyristor by means of a voltage which is produced by the motor speed regulator 3. Said regulator comprises a reference voltage generator, whose voltage is compared with the back e.m.f. developed by the motor when it operates as a generator during the time intervals in which it is not supplied by the rectified voltage. The motor speed is limited by including a resistor 6 in the circuit of the control electrodes of the thyristors. Generally, a variable resistor is used which may or may not be accessible for the user and by means of which the spin-drying speed can be adjusted to the desired value.

By means of the variable resistor 6 the spin-drying speed can be adjusted between two limits, a limit below and a limit above approximately 600 rpm. To obtain the maximum spin-drying speed, the resistance 6 must be very high, while for the minimum speed it must be zero. The spin-drying speed is fixed during starting of the machine at the same time as the other washing parameters and does not necessarily correspond to the lowest possible spin-drying speed. In one embodiment the minimum speed is fixed at 100 rpm. This is advantageous when the motor torque can be limited to the electrical characteristics which correspond to said minimum spin-drying speed in such a way that the motor torque and the reactive torque, owing to inter alia the mass of water in the filled tub, are balanced around said speed. This is rendered possible by short-circuiting the resistor 6 by a contact 14. The speed of the drum in the filled tub will then be limited to that which corresponds to a spin-drying speed, i.e. the lowest permissible spin-drying speed of the machine.

As the variable resistor 6 should only be switched out when the tub is filled with water, the contact 14 should be controlled by the water level in order to ensure that the selected spin-drying speed can be obtained when the tub is emptied.

The drainage of the tub is determined by the timer which controls the draining pump circuit.

In one embodiment the contact 14 is a second contact of the water level control device 5 (pressostat), the contacts 5 and 14 being mechanically coupled. The elements which form the device which limits the spin-drying speed with filled tub is therefore essentially a second contact 14 of the pressostat, thus providing at least one closed contact for the position with filled tub. A buffer resistor in the electronic device in series with the variable resistor limits the lowest spin-drying speed with filled tub, to a speed below the critical speed range, which range varies in accordance with the type of machine for which the supply and control device is destined.

The operation of the device is as follows: it is assumed that the washing cycle is completed, and the timer and reversing device have started the spin-drying cycle in the preferred direction by contact 12 of the reversing device being opened. The motor is energized via contact 4 of the timer and 5 of the water-level control device. The contact 14 which is coupled to the contact 5 of the pressostat is closed, for the tub is filled. In this case, the voltage which is produced by the regulator 3 is applied to the control electrodes of the thyristors and limits the speed to a value below the critical speed range. Said speed is limited to 120 rpm, which speed is below the critical speed range of the type of machine equipped with the device.

After acceleration to spin-drying speed and drainage of the tub (controlled by the timer) contact 14 opens, the variable resistor 6 being no longer short-circuited, the speed increases to the spin-drying speed which is selected and determined by the value of the resistor 6.

The contacts 5 and 14 may be mechanically coupled, but the contact 14 may also be incorporated in the pressostat which comprises the contact 5. The contact 14 may alternatively be constituted by the contact in "position filled tub" of a second pressostat.

Thus, the speed-limiting device, simply by the operation of the pressostat which is equipped with a second contact in position filled tub or of a second pressostat, permits a gradual acceleration to spin-drying speed with filled tub. Said gradual accelerataion is effected from a minimum speed to spin-drying with empty tub.

The advantages of such a device are, inter alia, a level before spin-drying at a speed which is as slow as desired, and so permits secondary effects on the watertight tub owing to turbulence of the water to be reduced, thus allowing the use of construction materials which are lighter and which render it easier to make the tub watertight.

The contact 14 may alternatively be controlled by the timer, during starting of the draining pump or after a certain time.

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  Switching control for a reversing motor of a washing machine:

 A device for switching a d.c. motor of a washing machine. The drive means of the reversing device is connected in series with a pressostat. This circuit is connected in parallel with the terminals of the pump contact; a terminal of the pressostat contact and a terminal of the actuation contact of the supply module of the d.c. motor are connected. The motor of the reversing device is connected in series with the pump motor through which it is energized. 1. 

A device for switching a drum drive motor of a washing machine, comprising a pump motor having a first line connection and a switch connection; a drum drive motor; an electronic supply module having a first line connection and a switch connection, and output connections; timer contacts, including a pump motor contact having a second line and a motor connection, and a spin cycle contact having a second line and a module connection; a reversing switch assembly; means for connecting said drum drive motor to said electronic supply module output connections via said reversing switch assembly; means for driving the reversing switch assembly having first and second input connections; a delay contact having second line and motor connections; and means for connecting said first line connections together and said second line connections together and for connecting first and second line connections to a source of electric power; wherein said pump motor contact motor connection, pump motor switch connection and first input connection are connected together, and said delay contact motor connection, spin cycle contact module connection, electronic module switch connection and second input connection are connected together, whereby said delay contact and drive means for the reversing switch form a series circuit in parallel with the pump motor contact, and said delay contact and spin cycle contact are in parallel for supplying power to said electronic control module.

2. A device as claimed in claim 1 wherein said delay contact is a contact of a device which senses water level.

Description:

The invention relates to a method of and a device for switching a d.c. motor to a high spin-drying speed. The motor drives the drum of a washing-machine in an alternating fashion at a low washing speed and continuously in a specific direction at a high spin-drying speed. A timer assembly controls the sequence and the duration of the washing operations and a reversing switch assembly which switches the electric supply unit of the drive motor of the drum at washing speed in an alternating fashion and at spin drying speed. Devices for switching on the motor of the draining pump, for switching the supply of the drive motor of the drum and for controlling the drive of the reversing switch assembly are associated with the timer assembly and can short-circuit devices which have the same functions but which are associated with the reversing switch assembly thus rendering these inoperative by means which are driven by the timer assembly. In the same way as similar devices which are associated with the reversing assembly can short circuit the said devices belonging to the timer assembly at a given instant determined by the reversal of the rotating direction at washing speed.
From French Pat. No. 2,058,524 a method is known of switching a d.c. motor to spin-drying speed by means of four contacts of a d.c. motor, which motor is powered from the a.c. mains via an electronic module, and drives the drum of a washing machine. Said method employs either a timer with one motor and electromechanical blocking of the reversing cams, or a timer with two motors: one for the programming section and one for the reversing section.
French Pat. No. 1,455,935 describes a device by means of which the reversing motor can be stopped and consequently the spin-drying contacts can be actuated at a precise instant of the reversing cycle and held in the actuated position. This is achieved by connecting the reversing switch motor in series with the spin-drying motor, which combination is connected in parallel with the washing motor. The contact which is connected to a branch of one of the phases of the supply mains, which branch is disposed between the reversing switch motor and the spin-drying motor, is locked to the energizing contact of the washing motor and functions oppositely.
The methods and devices described in the two patent specifications thus permit the spin-drying cycle to be started at a precise instant of the reversing cycle when the desired contacts of the reversing means are closed. The reversing means then stops in this position during the entire spin-drying cycle, thus ensuring a safe operation. Moreover, it is impossible to damage the machine assembly and the electronic module by an incorrect operation. As a matter of fact, the machine would become highly unstable when by operating the timer spin-drying is allowed while the preferred direction of rotation of the drum is not correct. The sudden reversal of the polarity of the motor and its power supply might lead to the immediate breakdown of the electronic components of the power supply unit. As the reversing means itself controls the acceleration to spin-drying, irrespective of the setting of the timer, this yields a greater mechanical and electrical safety.
However, there is still a risk if the reversing means is activated too soon after completion of the spin-drying cycle. One of the characteristics of a permanent-magnet motor is that it also constitutes a generator, that is it can produce a voltage which is proportional to the rotor speed. Thus, during the entire deceleration period after completion of spin-drying a voltage appears at the terminals of the brushes which decreases gradually. For example, in said French Pat. No. 2,058,524 the voltage at the motor terminals is of the order of 200 Volts. Immediately after the electronic module is switched off, the motor keeps rotating as a result of its inertia and that of the loaded drum. This period of deceleration may last several tens of seconds. Throughout said period the voltage at the terminals decreases gradually from 200 V to 0 V. If it is assumed that the reversing means when started again rapidly changes over the two opposite contacts, the supply voltages and the motor voltages are suddenly reversed. This results in a short circuit which is the more violent because the voltage is high.
The invention is based on the previously described devices and its object is to avoid short-circuits that would occur if the reversing switch means were started again while the drum had not yet stopped. Moreover, it has the advantage of greater simplicity because it employs existing elements of the washing-machine.
According to the invention, the switching method is characterized in that the control of the reversing switch assembly is applied in series with the pump motor drive.
According to the invention, a device for switching a d.c. motor of a washing machine to spin-drying speed, comprises a timer assembly and a reversing switch assembly whose drive means are independent, make or break contacts for the pump motor, for the electronic supply module, for the drive motor of the drum and for the drive of the reversing switch assembly, the circuits constituted by a contact of the pump motor which is controlled by the timer in series with said pump motor and by an energizing contact of the electronic d,c. supply module of the drive motor of the drum in series with said power supply being supplied in parallel from the a.c. mains, wherein a circuit formed by a delayed contact in series with the drive means of the reversing switch assembly is connected in parallel with the terminals of the contacts of the pump motor, the terminal of the delayed contact which also forms a terminal of the drive means of the reversing switch assembly and the terminal of the energizing contact of the electronic module, which terminals are not permanently connected to a phase of the a.c. mains, being interconnected.
The delayed contact is constituted by the device which senses the water level in the tub of the machine.
In order that the invention be understood more fully reference is made to the following descriptions and Figures which are given by way of example.
FIG. 1 is a schematic diagram of a device for stopping the reversing means in a specific position in accordance with the prior art.
FIG. 2 is a schematic diagram of a device according to the invention.
FIG. 1 represents the device which controls the rotating direction of a permanent-magnet d.c. motor described in Franch Pat. No. 2,058,524, the reversing device being stopped during acceleration to spin-drying speed by selection of the contacts of the reversing switch means for a preferred direction of rotation.

The drive motor 1 of the drum is d.c. motor powered by an electronic module 2 which consists of a semi-conductor rectifier bridge and a reversing switch assembly of contacts 3, 4, 5, 6.
To reverse the running direction, the polarity at the motor terminals is reversed by closing the contacts 3 and 5 or 4 and 6 respectively in the desired rhythm. To increase the speed of the drum from the washing speed (approx. 50 rpm) to the spin-drying speed (100 to 600 rpm) the supply current at the terminals of the drive motor is varied and the reversing switch means is put out of action, which necessitates the use of independent drives for the timer and for the reversing switch means. Acceleration to spin-drying speed in a preferred direction is achieved by the following combination of contacts (the contacts represented by two dashes are associated with the reversing means and those represented by a single dash with the timer): the reversing contact 7 controls the power supply 2 of the motor 1, when 7 is closed the current which is supplied to the motor corresponding to the low washing speed; when it is open said current corresponds to the spin-drying speed. The contact is open at a specific position of the reversing cycle (for example when 3 and 5 are closed). In order to ensure a specific rotating direction during spin-drying, the motor 10 of the reversing switch means is stopped by opening contact 8. Reversing contact 9 which energizes the pump for draining the tub 11, is closed when the motor 10 of the reversing means has stopped. Contacts 7' 8', 9' are timer contacts which ensure normal operation if no spin-drying is required. Contact 12 is the timer contact which controls the draining cycle.
The operation of the device is as follows: during washing, contacts 7, 8, 9 are short-circuited by contacts 7', 8', 9' which are controlled by the timer; while the reversing means rotates, the d.c. motor rotates in accordance with a specific rhythm and in the two directions of rotation.
During spin-drying, acceleration is effected in two steps. First of all, the timer contacts 7', 8', 9' open. Contact 8 of the motor of the reversing means remains closed, the d.c. motor is still supplied with the "washing" voltage, the motor of the reversing means keep rotating.
Subsequently, at a given instant of the reversing cycle (when 3 and 5 are closed) the motor of the reversing means stops because 8 is open and spin-drying commences because 7 is open.
From the above description of the operation it appears that if at the end of the spin-drying cycle the machine is immediately re-started, the motor of the reversing means will be re-energized and rapidly switches the two contacts opposite 3 and 5, that is 4 and 6, and the supply voltages and the motor voltage are suddenly reversed. This causes a short-circuit which becomes the more severe as the voltage supplied by the motor is higher.
The invention provides a method and a device which assure absolute safety when spin-drying is discontinued and which permit the previously described circuits to be simplified.
In FIG. 2 elements which are equivalent to those of the previous embodiment have the same reference numerals and functions.
The operation of the various elements is as follows:
During the washing-cycle, contacts 12 and 13 of the timer are open and a delay means 14 closes the circuit a certain time after the machine is started. The motor 1 is energized by the electronic module 2, whose one of terminals is connected directly to one phase of the mains, and the other terminal to the second phase of the mains through contact 14; contacts 7 and 7' are open, thus allowing the motor to be energized with a voltage corresponding to the washing speed. The motor of the reversing means 10 is energized through contact 14 which is closed and the pump motor 11. As the impedance of the motor of the reversing means is high relative to the impedance of the pump motor, the pump motor cannot start. The motor 1 alternately rotates in either direction at the washing speed.
When the timer advances to the spin-drying cycle, contact 12 which is controlled by the timer closes, pump motor 11 is started, contact 7 closes when contacts 3 and 5 which define the preferred direction of rotation are closed and, spin cycle contact 13 also closes and short-circuits contact 14 which opens after a relatively short time. At the same instant the motor of the reversing means 10 is stopped and maintains the position of contacts 3 and 5 for the duration of the spin-drying cycle.
When the spin-drying cycle is discontinued because the electronic module 2 is switched off, contacts 12 and 13 of the timer open, motor 10 of the reversing means remain stopped and pump motor 11 are stopped. The motor 10 of the reversing means then cannot be started until after the delay contact 14 has closed the circuit. This allows motor 1 to come to a complete standstill before commencing with a new cycle of the revolutions.
In an embodiment of the washing-machine in which switching to spin-drying should take place with filled tub, the delay means is constituted by the pressostat contact.
Apart from the advantages of assuring change-over to spin-drying in a specific direction of rotation, independently of any change in timer setting, the pump motor 11 is switched on by a contact at a previously determined instant and without any other means short-circuits the motor 10 of the reversing means. Consequently, it is not necessary to use one or two additional contacts as described in French Pat. No. 2,058,524. The pump contact 12 alone performs the functions of controlling the pump and blocking the reversing means.
A device embodying the method according to the invention employs the arrangement of the elements as shown in FIG. 2 and in said device the function of the delayed contact 14 is performed by the pressostat (in the case of a machine which changes over to spin-drying with filled tub), contact 12 of the timer being an existing contact because this serves for starting the pump motor.
Thus, connected in parallel with the mains terminals are the circuit formed by contact 12 of the pump motor in series with the pump motor 11 and the circuit formed by the spin cycle energizing contact 13 of the electronic module 2 and the electronic module. Parallel connected with contact 12 is the circuit with the delayed contact 14 (pressostat) in series with the motor 10 of the reversing means (or any other means which permits or prevents the reversing section of the timer from being driven. The delayed contact 14 and the motor of the reversing means 10 are consequently connected in series with the motor 11 of the draining pump. The terminals of contacts 13 and 14, which are not permanently connected to the phase of the mains, are connected.
This arrangement, compared with the arrangement described with reference to FIG. 1 allows four contacts (two reversing contacts and two timer contacts) to be dispensed with, which apart from providing operational safety results in a simplification of the timer-reversing device and consequently a substantially reduced cost price.
 

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  Device for preventing unbalance in washing machines during spindrying:

 A device for avoiding unbalance during acceleration to spindrying. A water level sensor has an additional contact through which a control voltage which is derived from a motor speed regulator is fed, and interrupts the motor supply if the drum speed decreases below a predetermined value. Spindrying cannot commence until after the tub is filled and an operating sequence at washing speed has taken place. 

 1. A device for preventing excessive imbalance in a clothes washing machine, comprising a drum driving motor, means for supplying voltage to the motor, regulating means sensitive to rotational speed of said motor for providing an output electrical control signal in response to said speed being below a predetermined speed, means for controlling voltage supplied by said supply means in response to an electrical control signal input, a water level switch contact for sensing a tub empty condition, an operating function controller contact for selecting a spin drying function, and means connecting said water level sensing contact and said operating function contact between the regulating means output and said voltage controlling means input such that voltage supplied to said motor will be controlled in response to said speed sensitive signal only when said spin drying function is selected and a tub empty condition is sensed.

2. A device as claimed in claim 1, wherein said voltage supplying means is blocked by said electrical control signal.

3. A device as claimed in claim 1, wherein said contacts are in electrical series connection, the water level switch being closed in response to a tub empty condition, said regulating means output signal is additionally responsive to comparison of motor speed with a spindrying speed, and said voltage supply is blocked by an electrical control signal input corresponding to said motor speed being below said predetermined speed.

Description:

The invention relates to a device for preventing an unbalance in washing machines during spindrying, which becomes operative after a voluntary or involuntary interruption of the operation of the machine, or after a decrease of the spindrying speed of the drum below a predetermined level, by providing for a sequence of alternating rotations of the drum at the low washing speed before the acceleration to the high spindrying speed.
During an interruption of the operation of a washing machine, owing to for example, a power failure or a voluntary stop during the spindrying cycle, the load which was distributed by the preceding washing cycle with alternating rotations comes off the drum wall and collects at the bottom of the drum. This may also happen if the drum speed decreases below a certain level. The laundry is then more or less dry and its mass may vary within rather wide limits. Accelerating again to the spindrying speed may have serious consequences because of unbalance which gives rise to substantial displacements of the tub-motor assembly, which will then hit the walls of the machine. The effects of the unbalance are especially marked in light weight machines having a low balancing mass and in which acceleration to spindrying is effected with a filled tub. In that case, the critical speed is always passed when the tub is still filled with water, i.e. when the mass of the tub-motor assembly is still substantial, and as rapidly as possible in order that vibrations of a high amplitude cannot build up.

From French Pat. Specification 1,530,872 a control device for the drive motor of the drum of a washing machine is known which, when a spindrying cycle is controlled independently of the washing cycle or after voluntary or involuntary stoppage of the machine, causes said motor to start with a cycle of alternating rotations at washing speed so as to tumble and distribute the load. Said device moreover comprises a delay means constituted by a pressostat switch sensitive to water level in the tub and a bimetal which is heated by a timer-controlled circuit, which prevents starting of the spindrying cycle while the tub is still filled with water. This known embodiment is an approach towards the solution of the problem of the unbalance during acceleration to spindrying after a stop. However, switching to alternating rotation at washing speed cannot always lead to a satisfactory distribution, especially when the laundry has hardly dried; i.e., at the very beginning of the spindrying cycle. This is also the case when the user employs the machine for spindrying only.
In a device according to the invention, a contact of a water level control device is connected in series in a branch of the circuit of a motor regulating device, which controls the electrical current to the motor, said contact being closed when the tub is empty.
In another embodiment said contact is in series with a second contact associated with the timer, which operates simultaneously with a timer contact associated with the spin-drying made.
The following descriptions and drawing are given by way of example in order that the invention be more fully understood.

The single FIGURE of the drawing is a circuit diagram of a device according to the invention.
French Pat. Specification 1,530,872 describes a device which can be employed in a machine in which spindrying can apparently commence whilst the tub is empty. Moreover, devices are provided for changing over from the washing speed to the spindrying speed when the washing speed reaches 80 to 85% of its rated speed. The drum then accelerates to high speed. This operation is effected each time that the power supply is restored after stopping. It is to be noted that the distribution of the laundry is effected while the tub is empty, the pressostat allowing acceleration to spindrying only while the tub is empty.
According to the invention a laundry distribution cycle, known per se from the French Pat. Specification No. 2,044,540, "Spindrying with filled tub", is performed in the presence of water, so as to obtain an optimum distribution. This is effected each time that the machine is stopped voluntarily or owing to a power failure, or when the spindrying speed has dropped below a previously determined value. The distribution cycle is obtained by filling the tub with water to a sufficient level, followed by a cycle of alternating rotations at washing speed for a given time, after which the timer causes the motor to accelerate to spindrying speed, while the tub is still filled with water, and simultaneously the pump is energized to reduce the water level and allow acceleration to the selected spindrying speed.
The use of a d.c. motor for driving the drum in series with the heating resistance allows a balance to be obtained between the maximum permissible speed and the moment of resistance. Acceleration to spindrying with filled tub presents no problems with such a d.c. motor, because by an appropriate selection of the heating resistance which is connected in series with the motor the speed is automatically limited to a value equal to the maximum speed which is permissible without overflowing. The permanent-magnet d.c. motor 1 used in the embodiment shown in the drawing is energized from the a.c. mains via a bridge with diodes and thyristors 2. The direct voltage supplied by said bridge is controlled by a regulating device 3 of any type well-known in the art which compares the back-e.m.f. of the motor, during the periods when said motor is not energized and behaves as a generator, with a specific reference voltage for the washing speed and the spindrying speed. Such a regulator is shown, for example, in U.S. Pat. No. 3,640,098. Said comparison results in a voltage which is applied to the control electrodes of the thyristors and thus influences the motor supply. The voltage thus supplied to the motor passes via contacts which are disposed on cams which are fixed on a shaft which is driven by a motor (not shown) forming the reversing device and enabling the alternating rotation of the motor by changing the polarity of the supply voltage at the motor terminals.
The device according to the invention comprises two elements, of which one is external and the other is included in the power supply. This is shown by the diagram. By the closure of the contact 4 the pressostat of the machine energizes the motor 1 and the heating resistance 6 in series when filling is completed. A second pressostat contact 5 ensures that the rectifying bridge 2 which supplies the motor can be controlled when it is closed, i.e. when the tub is empty. The closure of the contact 5 enables the control voltage from the regulating device 3 to be applied to the control electrodes of the thyristors.
The contact 5 may be incorporated in the pressostat 4 as shown in the present embodiment or may form an assembly which is separate from the pressostat and which in a similar way as the pressostat responds to the water level in the tub. It is simpler to couple said contact mechanically to the pressostat contact.
The contacts 7 and 8 are associated with the timer and are closed during spindrying.
The operation of the device is as follows:
During acceleration to spindrying, while the tub is filled with water, the contact 4 energizes the motor 1 via the rectifying bridge 2. Acceleration takes place. During this time, the rectifying bridge 2 which forms the power supply operates normally because the tub-empty contact 5 is open and does not control the control electrodes of the thyristors.
After the tub is emptied and when the speed is sufficient (above 80 rpm for the drum) contact 4 opens and contact 7 of the timer ensures the continuation of the motor supply. At the same time the contact 5 closes. The control voltage from the regulator 3 is then fed via the contact 8 to a device for controlling the supply voltage of the motor which maintains the spindrying speed.
If owing to some cause the motor speed, and thus the speed of the drum, drops below a predetermined value, the contacts 5 and 8 remaining closed, the control voltage from 3 interrupts the power supply in the present example by turning off the thyristors. The motor stops and thus the risk of instability owing to the occurrence of an unbalance as a result of a change in distribution of the load is eliminated.
The power supply control device which is controlled by the voltage from the regulating device 3 is not rendered operative during the acceleration phase, for in that case the power supply would be permanently cut off because the motor speed is below the predetermined threshold (100 rpm for the drum).
As the pressostat which comprises 4 provides a delay, it initially allows the acceleration of the motor and the clearance of the threshold. In a second phase, when the tub is empty, contact 5 allows the power supply to be blocked if the speed becomes lower than said threshold.
Thus, the device employs a power supply which comprises a blocking threshold, a pressostat which controls the closure of a contact 5, when the tub is empty in series with a contact 8 which is associated with the timer and which is closed during spindrying.
The combination of said elements thus prevents restarting in the spindrying mode if the voltage at the motor terminals has been cut off.
Thus, the stability of the machine is ensured when:
the user stops the machine during spindrying and starts it again after a certain time during which the laundry can collect at the bottom of the drum.
the supply voltage of the machine has been cut off.
If an intermittent defect of electrical contacts occurs in the control elements of the machine.
the user performs a forbidden operation by setting the timer knob to the spindrying cycle whilst the tub is empty and the complete starting process with water cannot be performed.

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  Method of and device for controlling a d.c. washing machine motor, CONTROL UNIT TYPE C-03H/220 function description :

 A method of controlling the operation of a d.c. motor of a washing machine by energizing or de-energizing a reference voltage generator. The back-e.m.f. of the motor is compared with the reference voltage. The a.c. supply of the generator is controlled by contacts of detectors for the operating conditions of the machine, such as temperature of the suds or of electronic components, unbalance, opening of the door etc. 

 1. A method of controlling a d.c. motor of a washing machine in dependence on motor speed and at least one other parameter, by energizing a motor from a controlled rectifying bridge circuit supplied from an alternating current source; supplying a control signal to said bridge circuit from an electronic speed regulator; generating a motor stop signal in a comparator by comparing a back-e.m.f. signal from the motor with a reference voltage from a reference voltage generator; and applying a motor de-energize signal to said regulator in response to a low speed condition and in response to a given other condition; wherein said step of applying a de-energizing signal in response to a given other condition comprises detecting said given other condition and controlling a switch contact responsive to said given condition, and supplying alternating current power to said reference voltage generator from said alternating current source through said switch contact.

2. A method as claimed in claim 1, wherein upon occurrence of said given condition, said switch contact is closed so as to apply alternating current power to said reference voltage generator, and said motor de-energizing signal is applied to said regulator when motor speed is below a given speed while power is applied to said reference voltage generator.

3. A method as claimed in claim 2, wherein said other condition relates to water level in a tub of the machine, and said switch contact is closed when said tub is empty.

4. A method as claimed in claim 2, wherein said reference voltage generator includes a plurality of input alternating current power connections; and a respective plurality of switch contacts are responsive to a plurality of other conditions, each input alternating current connection providing power to generate a unique reference voltage level.

5. A method as claimed in claim 4, wherein one switch contact is closed in response to detection of low water temperature.

6. A method as claimed in claim 5, wherein a second switch contact, associated with generation of a reference voltage corresponding to a higher motor speed than that associated with the low water temperature detection, is closed in response to a tub empty condition sensed by a tub water level detector.

Description:

BACKGROUND OF THE INVENTION
The invention relates to a method of controlling a d.c. motor (POLYMOTOR ITALIANA [PHILIPS] 8219 440 01351) of a washing machine in dependence on a parameter which is not exclusively related to motor speed. In such a method the motor is energized from an alternating current supply through a rectifier bridge which comprises two diodes and two thyristors, the thyristors being controlled by a signal which is supplied by an electronic speed regulator. During at least one specific operating cycle of the machine the timer switches on a control device, which supplies a motor de-energize signal to the regulator for stopping the motor when the motor speed drops below a certain value, the control device being actuated by a motor stop signal supplied from a comparator which continually receives both the back-e.m.f. voltage of the motor and a rectified reference voltage from a reference voltage generator.
Such a device for controlling the operation of the motor is particularly useful in a machine which accelerates after a laundry distribution cycle. Such a method of starting up is employed if the weight of the machine is to be reduced or if the spindrying speed is to be increased. It is then necessary to take special care that the mass of laundry is distributed as uniformly as possible along the walls of the drum so as to avoid unbalance. When the mains supply of the machine is interrupted, the motor may either stop because the failure lasts some time, or may slow down when the failure is very brief. In the first case the laundry drops again onto the bottom of the drum; and during speeding up the unbalance will become more severe, depending on the wetness of the laundry. In the second case the loss of speed of the drum may be such that the result will be the same as if it had stopped.

Control of the motor by the control device in the event of a voltage failure is based on the comparison of two voltages: a negative voltage produced by the back-e.m.f. of the motor when the motor has reached its normal operating condition for the relevant cycle and a full-wave rectified reference voltage which is derived from the supply circuit of the regulator and an antihunting device. The reference voltage is adjusted to a value lower than that of the BEMF voltage which corresponds to the drum speed at which the laundry no longer remains at the periphery of the drum.

SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of controlling a d.c. motor (POLYMOTOR ITALIANA [PHILIPS] 8219 440 01351) of a washing machine in dependence on a parameter which is not exclusively related to the motor speed and to achieve this by switching a reference voltage generator on or off. The various detectors for parameters such as the motor temperature or the temperature of electronic components, the temperature of the suds, opening of the door, the water level, tub displacement etc. have at least one make or break contact in series with the a.c. supply circuit of the reference voltage generator.
The method according to the invention of controlling a d.c. motor of a washing machine is characterized in that the control device is activated by modifying the supply voltage of a reference voltage generator, said modification being controlled by at least one contact of at least one detector for a variation of an operating parameter of the machine.
The method is further characterized in that the reference voltage generator is energized when the tub is empty.
The device embodying said method is characterized in that a reference voltage generator comprises at least one switched a.c. input which corresponds to at least one predetermined reference voltage at the output.

In various embodiments:
at least one make or break contact for the a.c. supply of the reference voltage generator belongs to at least one detector for an operating parameter of the machine,
at least one make contact of the a.c. supply of the reference voltage generator is the tub-empty contact of a detector for the water level in the tub of the machine,
at least one make or break contact of the power supply of the reference voltage generator is a contact of a detector for the amplitude of tub movements,
at least one make or break contact of the power of the reference voltage generator is a contact of thermal senser which controls the temperature of the washing water,
at least one make or break contact of the power supply of the reference voltage generator is a safety contact for the door of the washing machine,
at least one make or break contact of the power supply of the reference voltage generator is a contact of a thermal senser which is disposed on an element of the washing machine whose heating resistance is connected in series with the motor supply, which element is subject to overheating as a result of a malfunction.
The following descriptions and drawings are given by way of example in order that the invention may be more fully understood.

BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram of a prior-art device.
FIG. 2 is a block diagram of a control system according to the invention.
FIG. 3 is an electronic circuit diagram of the reference voltage generator, comparator and control unit of FIG. 2.
FIG. 4 is a block diagram of a device for controlling a motor of a washing machine in dependence on several parameters.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

FIG. 1 represents a d.c. motor control system in accordance with a device described in U.S. Pat. No. 3,939,673 issued Feb. 24, 1976 to the instant applicant. The sole object of said method is to avoid the unbalance which occurs in washing machines during spin-drying after a voluntary or involuntary interruption of the operation of the machine or after the spindrying speed has dropped below a predetermined value, said method consisting of refilling of the tub with water and acceleration to washing speed before acceleration to spindrying speed with the tub still filled with water.
A permanent-magnet d.c. motor (POLYMOTOR ITALIANA [PHILIPS] 8219 440 01351) 4 is energized from the a.c. mains 1, 2 through a rectifier bridge 5 which comprises two diodes and two thyristors. The rectifier bridge 5 is connected in series with an immersion heater 3. The thyristors of the bridge 5 are controlled by a regulator 6 which compares the voltage produced by the back-e.m.f. (BEMF) of the motor when said motor is not energized, with reference voltages for the washing and spindrying speeds. The input of the reference voltages to the regulator 6 is represented by the line 13 and that of the BEMF voltage by the line 14. In order to require that a re-starting cycle proceed only with filled tub so as to avoid unbalance if an interruption of the power supply of the machine, has occurred, a control device 7 constituted by, for example, a transistor, receives its actuating, or motor stop, signal from a comparator 8. The comparator 8 via the lines 13 and 14 respectively receives a d.c. reference voltage and the voltage produced by the back-e.m.f. of the motor. When the value of the BEMF voltage of the motor becomes lower than that of the reference voltage, the control device via the regulator 6 causes the thyristors of the power supply 5 to be cut off and hence the motor is stopped. In order to allow the motor to speed up to spindrying and to avoid power supply blocking control before the motor has reached a speed which suffices to avoid blocking of the power supply, the output of the control device is connected to the regulator through the contacts 9 and 10. The contact 9 is mechanically coupled to the contact 11 of the pressostat which is only closed when the tub is empty; the contact 10 is a timer contact which is closed for the spindrying cycle. The contact 12 which belongs to the timer is closed during spindrying and enables the motor to be supplied, ensuring that power supply is continued when the contact 11 of the pressostat opens after drainage.
Thus, such a device allows two parameters to be controlled: the motor speed and refilling of the tub with water. The other parameters such as the temperature of the suds, the temperature of the electronic components or of the motor, or the amplitude of the vibrations of the tub can only be controlled by means of detectors whose contacts control the main power supply of the machine. The same applies to a door opening safety device which also steps the machine when the door is opened during operation. It is not possible to achieve the previously outlined goals by connecting said contacts in series with the output of the control device, for the control signal is very weak; therefore, the method according to the invention enables the motor to be blocked by means of these different parameters which no longer act on the weak signal supplied by the control device but rather act on the supply of the reference voltage which is an input to the comparator.

FIG. 2 shows a block diagram of a device embodying the method according to the invention. In this diagram the devices and elements which resemble those in the known arrangement have been given the same reference numerals. The permanent magnet d.c. motor 4 is supplied from the a.c. mains 1, 2 through a rectifier bridge 5 which comprises two diodes and two thyristors. The rectifier bridge 5 is connected in series with the immersion heater 3. The thyristors of the bridge 5 are controlled by a regulator 6 which compares the voltage produced by the BEMF of the motor with reference voltages for the washing and spindrying speeds. The input of the reference voltages to the regulator 6 is represented by the line 13 and that of the BEMF voltage by the line 14. The control device 7, which in a known embodiment is constituted by a transistor, receives a voltage at its base which is supplied by the comparator 8. The comparator 8 receives the BEMF voltage from the motor over the line 14, and compares that voltage with a rectified reference voltage supplied by the reference voltage generator 15. The reference voltage generator 15 is supplied with alternating current from the terminal 17 through the detectors 16 for detecting operating parameters of the machine other than the speed of rotation of the motor and, finally, through a contact 10 which belongs to the timer rectified-voltage generator to be switched on or off.

FIG. 3 shows a circuit diagram of the control unit of the electronic regulator. The devices of the block diagram in FIG. 2 are delimited by dash lines and have the same reference numerals. Thus, the control device 7 is constituted by a transistor whose collector is connected through a resistor 19 to provide a motor-de-energize signal to a control electrode of the tetrode thyristor (not shown) of the regulator 6, the emitter receiving the supply voltage from the motor.
The base of the transistor 18 is supplied with a voltage which is the sum of the voltages across the resistors 20 and 23, which come from the +terminal of the motor supply, and the voltage which is the result of the comparison of the BEMF voltage of the motor (line 14 and resistor 21) with a reference voltage obtained from the generator 15 through the resistor 22. Capacitors 24 and 25 are polarized capacitors and the diode 26 is a protection diode.
The reference voltage generator 15 is shown with two inputs 27 and 28. Each of these inputs includes a diode 29 which rectifies the alternating voltage applied to its terminals through the contacts of the detector switches 16. Each branch of the voltage generator constituted by the elements 29,31 and 30, 32 supplies a different reference voltage. Thus the branch 27,29,31 supplies a rectified voltage which is equivalent to the BEMF voltage of the motor at a speed which at least equals 70 r.p.m., while the branch 28,30,32 supplies a voltage equivalent to the BEMF voltage of the motor at some given speed lower than 50 r.p.m.
These inputs of different value of the reference voltage generator are applied by the contacts of the detectors 16 depending on whether the motor speed during washing (50 r.p.m.) or during sprindrying is to be controlled.

The operation of the devices 7,8 and 15 of FIG. 3 is as follows:
The circuit will be considered which is constituted by the terminal 17, the contact 33, the terminals 27, the diode 29 and the resistor 31 (the capacitor which is shown but which has no reference numeral is a timing-base capacitor and is irrelevant for the description of the operation). When the terminal 27 is not energized, the base of the transistor 18 receives a negative voltage produced by the BEMF of the motor. As a result, the transistor remains cut off permanently and the control of the thyristors which are connected to the collector through the resistor 19 is not influenced: the power supply functions normally.
After speeding up to spindrying, the application of an alternating voltage to the terminal 27 has no effect, for the motor voltage which is supplied over line 14 and resistor 21 is more negative than the opposing voltage which is positive because rectification by the diode 29, and the transistor 18 remains cut off.
If the mains voltage at the terminal 27 is interrupted for a time which is sufficiently long for the BEMF to assume a low value (simply by the motor slowing down), there will be an instant at which the positive voltage supplied through circuit 29,31 and 22 becomes more significant, and a motor stop signal is applied to the base of transistor 18: the transistor 18 then conducts. Thus, it blocks the operation of the thyristors and consequently the motor supply.
If the machine is to be re-started, it suffices to interrupt the circuit which supplies the terminal 27, for example by re-filling the tub, and the cycle is then repeated. The afore-described operation corresponds to a voltage failure protection and ensures that the motor cannot speed up again to spindrying speed without a prior laundry distribution cycle, which may be qualified as internal control of the motor supply.
The devices provided enable external control of the power supply by means of the contacts of a detector for variations of an operating parameter of the machine. Typical parameters are for example the water level, the temperature of the suds, the displacement of the tub, opening of the door, blocking of the drum or motor.

The dash line 10 (FIG. 3) between the detector elements 16 and the rectified-voltage generator 15 corresponds to contact 10 in FIG. 2 and belongs to the timer.
Control of the operation of the motor in dependence on the water level in the tub may be obtained, when the contact 33 is assumed to belong to a water level sensor or pressostat. If the thyristors of the motor supply should not be blocked as soon as the machine speeds up to spindrying, it is necessary that the motor has reached a certain speed (which has been fixed at approx. 600 r.p.m., or 80 r.p.m. for the drum of the machine), so as to ensure that the BEMF of the motor, which comes from 21 and 23, exceeds the reference voltage. To accomplish this, terminal 27 is not energized during said acceleration phase. For this purpose, the following switching process is realised: the terminal 27 is energized through the contact 10 which belongs to the timer and which is closed during spindrying only. The high-level pressostat of the machine has two contacts, of which one contact 33 corresponds to an empty tub and a second contact, not shown, corresponds to a filled tub. The contact 33 is connected in series with the contact 10 of the timer.
During acceleration to spindrying, the pressostat is in the filled-tub position, i.e., contact 33 is open. The machine speeds up normally. After some tens of seconds, while the tub is gradually filled, the pressostat returns to the empty position, and contact 33 is then closed. Through contact 33 and contact 10 of the timer the alternating voltage is applied to input terminal 27 of the reference voltage generator. Two cases are to be considered:
the speed of the drum is higher than 80 r.p.m.; in this case the voltage failure has no effect, and the machine continues to speed up to spindrying speed,
the speed of the drum is lower than 80 r.p.m.; in this case the machine is blocked and it is impossible to start the machine except if 33 is open, i.e. when the tub is full. If starting in the spindrying mode is attempted with an empty tub, whilst contact 33 is closed, the system is blocked at once and the machine cannot start.
Control as a function of the temperature of the suds is applied when the laundry should not be stirred during special cycles. For example, for woollens, the washing movement should be minimal. The reference voltage generator will be energized at 28 through the timer contact 10 (FIG. 3) and through a contact 34 which in this case belongs to the thermostat. Said thermostat contact opens when the required temperature is attained, the motor supply thus being blocked until the temperature is reached. Once the washing water has the desired temperature, contact 34 of the thermostat opens, the alternating voltage at terminal 28 cuts out and the motor is immediately started for the next operations at washing speed.
In a similar way, the motor can be controlled in dependence on the displacement of the tub. It is known that instabilities owing to an incorrect distribution of the lead of laundry in the drum occur at specific speeds, which are called critical speeds. In order to avoid damage to the machines, it is necessary to stop the machine very rapidly when the amplitude of displacements of the washing unit are excessive. For this a contact, represented by contact 33 in FIG. 3, is disposed at a specific location in the path of the washing unit during substantial displacements, which will result in automatic stoppage in dangerous cases. As the contact 33 is a self-releasing contact (i.e. it returns immediately to its original position, which is "contact open"), it is evident that when the washing unit actuates the contact 33, a short pulse is applied via contact 10 of the timer to the rectified-voltage generator and subsequently to the motor supply, the motor being stopped immediately. The conventional methods of acceleration to spindrying can then function normally.
Control of the motor supply when the door is opened is achieved in the same way as in the previous case, by disposing a circuit breaker 33 or 34 on the door of the machine. In accordance with the washing cycle of the machine, the machine is stopped through contact 33, if the machine is in the spindrying mode, and through contact 34 during the washing mode.
It is equally possible to ensure that the power supply circuit of the motor is protected when the drum is blocked. It is known from French Patent Specification No. 2,009,665 or British Patent Specification No. 1,354,367 that the circuit of the permanent-magnet motor is protected both by the limitation of the current owing to the series resistance and, as known from U.S. Pat. No. 3,638,090, by a thermal protection device consisting of a temperature detector which is disposed underneath the heating element and which interrupts the power supply when the temperature exceeds a preset threshold. The same result can be obtained by including the contacts of the temperature detector in the power supply circuit of the reference voltage generator at 33 or 34 or in the two branches (FIG. 3). For example, if the detector is disposed close to the heating element, or in the interior of the motor or on the heat sinks of power elements of the motor supply, the motor supply will be blocked electronically when the temperature becomes too high, as soon as the contact of the detector is closed.

The method and the device according to the invention, moreover enable protection of the machine in the event that the rotor of the motor is blocked. The operating principle has been described hereinbefore of pressostat control which allows acceleration to spindrying only when the tub is filled with water. If the motor or the drum is blocked, the motor is energized after the acceleration cycle. After a certain quantity of water has been drained, contact 33 of the pressostat will close. At this very instant, the blocking command occurs, to block the power supply and to de-energize the motor. FIG. 3 shows that if the back-e.m.f. is zero, transistor 18 is conducting and the circuit 18-19 through the tetrode transistor of the device 6 (FIG. 2) supplies a voltage for blocking the thyristors. Thus, when the motor is blocked full protection of the motor, of the electronic circuitry and of the series resistor 3 (FIG. 2) is provided, as long as the fault lasts, and any damage to these elements of the machine is avoided.
FIG. 4 is a simplified diagram of an embodiment of a control system for the rotation of the motor of a washing machine in dependence on a plurality of operating parameters.
The input terminal 27 of the reference voltage generator 15 carries a rectified voltage equal to that produced by the back-e.m.f. of the motor at a drum speed of 70 r.p.m. The input terminal 28 carries a rectified voltage which corresponds to a drum speed lower than 50 r.p.m.

The machine is started with filled tub and closed door, the pressostat 35 being in position 352 for the filled tub and the door safety device 36 being in position 362 for the door closed; the power supply 5 of the motor is then connected directly to the mains terminal 1 and, through the motor resistance 3, to the mains terminal 2. The washing water is heated by closing contact 37 of the timer. When the water has not yet attained the desired temperature, the thermostat 38 remains in the cold position 381 and energizes the reference voltage generator 15; since the motor has not yet begun the alternating washing movement, its speed is lower than 50 rpm, thus causing the rectifier bridge 5 to be cut off. The timer motor 39 which is also connected in series with the thermostat 38 is not energized, and does not start until the thermostat is in latter position 382; in this position terminal 28 is no longer energized, the back-e.m.f. of the motor is then higher than the reference voltage and the normal power supply for the washing speed is then applied to the motor terminals.
When door protection contact 362 opens, the power supply of the rectifier bridge is interrupted, which bridge constitutes the power supply 5 of the motor, so that the motor is stopped. When the door is closed, the rectifier 5 is again energized by the closed contact 362. However, contact 361 closes again and applies a voltage to 27 which blocks the power supply. Starting takes place after filling, upon closure of contact 352 of the pressostat.

Protection against a blocked rotor is effected by the disappearance of the back-e.m.f. of the motor. The reference voltage generator 15, which is always energized via the terminal 27, will therefore always have a voltage which is higher than the back-e.m.f. of the motor, so that the power supply will be cut off when the tub is empty and the motor is not rotating.
During spindrying the timer contact 40 as well as the door protection contact 361 are closed. Since this type of machine is started when the tub is filled with water, a contact 41 allows the motor to speed up to spin-drying. After a very short time, the pressostat 35 changes over to the empty-position 351 and allows the terminal 27 of the rectified voltage generator 15 to be energized.
The safety contact 42 for instability of the tub of the machine, upon actuation, supplies a pulse which blocks the power supply. Starting will take place after filling upon closure of contact 352 of the pressostat.

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  WASHING AND SPIN-DRYING MACHINE:
 

  An automatic washing machine including a source of
electric energy and a two-position safety switch. The en-
ergizing winding of the water supply valve and the wind-
ing of the drain pump motor are connected in series with
one position of the safety switch across the energy source.
A heating element and the drum motor winding are con-
nected in parallel. This parallel combination is connected
in series with the second position_of the safety switch
across the energy source. The motor winding for the pro-
gramming device is connected between the junction of
the valve winding and the drain pump winding and the
junction of the second position of the safety switch with
the parallel combination of the heating element and the
drum -motor winding.

The present invention relates to an automatic washing
machine and, more particularly, to an improved program-
ming device therefor. An electric washing and spin-drying
machine generally comprises an electric circuit arrange-
ment which feeds a programming device, a motor for
driving the drain pump and at least one motor for driv-
ing the washing and spin-drying drum, a heating element
and an electromagnetically actuated water supply valve
for determining the water levels in the tub.

It is known that a machine for washing and spin-drying
comprises one or twomotors each having one or more
speeds for the washing and spin-drying operations, a
motor-driven pump and at least one heating element. Au-
tomatic operation is made possible by the addition of an
electromagnetically actuated water supply valve and a
safety device which controls the water levels required for
washing or rinsing. These various membersare controlled
by, and in turn control, a programming device equipped
with a separate motor. In the known washing and spin-
drying machines, the design of the circuits which include
the various electrical elements is such that the program-
ming device must have a plurality of make-and-break
switches, one in the circuit of each of the said. elements.

The inventionobviates this disadvantage and has for its
object to provide a simplified programming device by the
use of a suitable design of the safety devices and of the cir-
cuits which include the members which in cooperation per-
form the washing and spin-drying operations. For this pur-
pose the invention is characterized in that the circuit ar-
rangement comprises two parallel branches, one of which
comprises the series combination of a safety switch in the
position “filling,” the winding of the water supply valve
and the winding of the drain-pump motor. The other
branch comprises the series combination of the safety
switch in the position “end of filling” and the parallel com-
bination of the heating element and the windings of the
motor or motors for driving the drum. The winding of
the motor of the programming device is connected at one
end to the junction of the windings of the water supply
valve and of the draining-pump motor and at the other
end to the junction of the safety switch in the position
“end of filling” position and of the parallel combination
of the heating element and the driving motor.
An advantageous embodiment of a washing machine in
accordance with the invention is characterized in that
the impedances of the windings of the water-supply valve
and the motor of the programming device are large com-
pared with the impedances of the winding of the drain-
pump motor and of the parallel combination comprising
the heating element and the windings of the driving motor
or motors.

A further feature of the washing machine in accordance
with the invention is that the safety switch in the position
“filling” and the winding of the water-supply valve are
short-circuited through a contact of the programming de-
vice.

A further feature is that the winding of the motor intended
for the spin-drying operation is connected in series
with the safety switch in the position “filling” and a make and break switch.

The invention will now be described more fully with
reference of the accompanying drawing, the single figure
of which shows the circuit diagram of a programming de-
vice in accordance with the invention. During a wash-cycle
this programming device performs the following opera-
tions: regulation of the Water level; rotation of the drum
alternately in either direction in a rhythm which is deter-
mined by a change-over switch which forms part of the
programming device; and rapid rotation for spin-drying.

The cycle comprises the usual operations of a wash-pro-
gramme, i.e. pre-washing with heating for a predeter-
mined period of time, washing with heating for a pre-
determined period of time, rinsing and, as the case may
be, drying by spinning.

Because in a wash-cycle both the washing quality and
the protection of the various machine parts must be taken
into account, the following measures are taken.

During the filling operation the programming device is
inoperative and the machine is not started until the water
has reached the correct level. Filling takes place only
when the pump is capable of normal operation, but can-
not take place when the pump is disconnected or its wind-
ings are switched off.
The heating element cannot be switched on before the
tub has been filled to the desired level. The reciprocating
movement of the drum can only .be effected when the tub
is filled, however, it continues during the draining operation
 until the water-level safety valve is actuated. Spindrying
 can only take place when the tub is empty of water.
To prevent. a complete cycle from being performed
during the failure of an essential member, the machinestops:
in the absence of water at the beginning of, or during,a cycle;
 when the heater is switched off or disconnected; and when the pump is switched off or
 disconnected.

This is ensured by a suitable design of the circuit of
the motor of the programming device and by the action of
the cams of this device on the switches of the various members.

A discussion of the operation will explain how a wash
cycle is effected.

The machine is energized from the supply line through
a main switch having contacts 1 and 2. In the oIf—position
of the switch the entire machine is insulated from the
electric supply. Starting is effected by turning the knob
of the programming device to the first position so that
the contacts 1 and 2 (or a single contact if there is a
main switch at another point) are closed.

During the filling operation, a safety switch G is in the
position shown by a solid line, so that a water-supply
Valve (not shown) is operative. A high-impedance Winding
E of the valve now is connected in series with a low-
impedance winding of a pump C. As a result of the volt-
age divider effect the voltage across the pump winding
is very small so that the motor F of the programming
device, in parallel therewith, is not driven. The voltage
across the heater element D, in series with motor winding
F, is so low that it can be considered to be negligible.

When the correct water level is reached, the safety
switch G passes from the -position shown by the solid line
to the position shown by the broken line. The heating
element D and a washing motor A now are energized, the
latter through one of the positions of a change-over
switch H. The motor of the programming device F is now
energized through the windings of the pump C so that it
can run. The machine then performs the wash-cycle, the
drum being rotated alternately in either direction. In order
to begin the draining operation, a contact 3 of the pro-
gramming device is closed. The motor of the programming
device F is stopped because it is short-circuited through
the switch 3 and the switch G. When the water drops to
a given level, the switch G changes position, i.e., passes
from the position shown by the broken line to the posi-
tion shown by the solid line, thereby removing the short
circuit from winding F. The motor of the programming
device now is energized through the switch 3, the heating
element D and the windings of the washing motor A.
Since the switch 3 is closed, the winding E is short cir-
cuited. When the heating element is switched off, the
motor of the programming device will stop as soon as
the change-over switch H of the washing motor A passes
from one position to the other. The pump C alone re-
mains operative and the machine stops.

On termination of the draining operation, i.e., when
the tub is empty, the contact 4 is closed to start the spin-
drying cycle. The spin motor B then is energized through
contact 4 and the safety switch G, which is in the posi-
tion shown by the solid line.

The cycle is terminated by opening the contacts 1 and
2 after the last spin-drying operation.

What is claimed is:

1. An automatic electric washing machine comprising,
an electric circuit arrangement for energizing the motor
of a programming device, a motor for driving the drain
pump, at least one motor for driving the drum, a heating
element and the winding of an electromagnetically actu-
ated water level supply valve, and a safety switch having
first and second positions corresponding to a Water filling
condition and an end of filling condition, respectively, the
circuit arrangement comprising two parallel branches
coupled to a source of electric energy, one branch com-
prising the series combination of the safety switch in the
first position, the winding of the water supply valve and
the winding of the pump motor, the other branch com-
prising the series combination of the safety switch in the
second position and the parallel combination of the heat-
ing element and the windings of the drum motor, means
connecting one end of the motor winding of the pro-
gramming device to the junction of the windings of the
water supply valve and of the pump motor and the other
end to the junction of the safety switch in the second
position and the parallel combination of the heating ele-
ment and the drum motor winding.

2. A washing machine as claimed in claim 1 wherein
the impedances of the windings of the water-supply valve
and of the motor of the programming device are large
relative to the impedances of the winding of the pump
motor and of the parallel combination comprising the
heating element and the windings of the drum motor.

3. A washing machine as claimed in claim 1 wherein
the programming device includes a switching contact
connected in shunt with the series combination of the
safety switch in the first position and the winding of the
water-supply valve.

4. A washing machine as claimed in claim 1 further
comprising a make-and-break switch and a winding for
driving the drum motor at high speed during the spin-dry
cycle, and means connecting said high speed motor wind-
ing in series with the safety switch in the first position
and the make-and-break switch.

5. An automatic washing machine comprising a water
level safety switch adapted to switch between first and
second positions as a function of the water level in the
machine, a source of electric energy, an electromagnet
winding for controlling the water supply valve, a winding
for the drain pump motor, means serially connecting the
safety switch in the first position, the electromagnet wind-
ing and the pump motor winding across said energy
source, a heater element and a winding for driving the
drum motor connected in parallel, means connecting
the safety switch in the second position in series with the
parallel combination of the heater element and the drum
-motor winding across said energy source, a winding for
the motor of the machine programming device, means
connecting one end of the programming motor winding
to the junction of the electromagnet winding and the
pump motor winding, and means connecting the other end
of the programming motor winding to the junction of the
safety switch in the second position with said parallel
combination.

6. A washing machine as claimed in claim 5 wherein
the impedance of the electromagnet winding and the im-
pedance of the programming motor winding are each sub-
stantially greater than the impedance of the pump motor
winding.

7. A washing machine as claimed in claim 6 wherein
said programming device includes a switch contact con-
nected in shunt with the electromagnet winding via the
first position of the safety switch and in series with the
pump motor winding across said energy source.

8. A washing machine as claimed in claim 7 further
comprising a winding for driving the drum motor at high
speed to produce a spin-drying cycle, a switch, and means
connecting said high speed winding, said switch, and the
safety switch in the first position in series circuit across
said energy source.

 

IGNIS K15 (PHILIPS) AWF633/IG  P.M. SYSTEM  PUSHBUTTON SWITCH:


Pushbutton switch which has a single housing both for
the mechanical operation of the pushbuttons and also for
carrying the electrical contacts and slides.

The invention relates to pushbutton switches of the kind
having a housing for the mechanical operation of the
pushbuttons and one or more carriers for electrical con-
tacts.Existing pushbutton switches of this kind have two
separate housings, one for mechanical operation, that is
to say for the control of pushbutton slides, for mechani-
cal locking and so forth, and the other as an added con-
tact housing to carry the electrical contacts. This makes
them rather expensive and bulky, large numbers of com-
ponents, particularly stamped-out parts, having to be used.
In some cases, too, the pushbutton slides and catch slides
are assembled in two parts, so that assembly is also com-
plicated, especially as, in this known kind of pushbutton
switch, the button-slide levers are at right angles to the
plane of the catch slides.

An object of the invention is to eliminate these draw-
backs and to provide a pushbutton switch of the kind de-
scribed, which is of simple design, less expensive and
occupies less space than known pushbutton switches.

According to the present invention there is provided a
pushbutton switch of the kind having a housing for the
mechanical operation of the pushbuttons and one or more
carriers for electrical contacts, wherein the housing com-
prises two plates of insulating material, which serve to
control the pushbutton slides and to carry the electrical
contacts.

In this way, only a single housing is required, to meet
both the mechanical and the electrical requirements of
the pushbutton switch. The pushbutton switch conform-
ing to the invention thus makes it possible to dispense
with many of the parts used hitherto.

Another feature of the invention is that the carrier for
the electrical contacts consists of at least one baseplate
containing slots into which the contacts can be inserted.
Among other advantages, this facilitates assembly, since
the insertion of the contacts is extremely easy and can be
carried out quickly. Two such contact plates should pref-
erably be provided, through which the contacts are in-
serted.

In that case, according to a further advantageous fea-
ture of the invention, pushbutton slides can be fitted with
tags and springs, resulting in springy contacts that are
easy to fit and remove. Moreover, one of the two base-
plates may well serve as a stop for the pushbutton slide.
This makes it unnecessary to fit a separate stop, so that
in this respect, too, the pushbutton switch is simpler, and
fewer possible components are used which simplifies their
assembly.

Another feature of the invention provides for the catch
slides to be carried in slots in the housing frame.

A particularly advantageous feature of the invention
is that both the plates of insulating material already
mentioned are gripped in a frame forming three sides of
the housing, the fixing plate being flanged on to this
frame. Because the frame is U-shaped, the other fixing
plate does not require any shaping, which naturally represents further simplification in manufacture. The front fixing plate may be riveted or welded to the other, curved,
plate. With a frame of flanged design, it is also possible
to use screws for assembly.

The invention will be further described by way of ex-
ample with reference to the accompanying diagrammatic
drawings, in which:

FIGURE 1 is a plan of pushbutton switch according
to the invention, with the top plate removed;

FIGURE 2 is a vertical section taken along the line
A—B in FIGURE 1, with a top plate;

FIGURE 3 is an underneath plan view of the push-
button switch illustrated in FIGURES 1 and 2;

FIGURE 4 is a similar view to FIGURE 3, but with
a baseplate fitted; and

FIGURE 5 is a front View of the pushbutton switch.

Referring to the drawings in detail FIGURES 1 and 2
show two plates of insulating material, 1 and 2, which
serve to carry a number of pushbutton slides 5. As can be
seen, the pushbutton slides 5 are fitted to slide at their
front ends in the plate 1 and at their rear ends in the plate
2. The plate 2 is bent to form a U and is provided with
a flange to which the plate 1 is riveted. The contacts are
merely represented diagrammatically in position; in fact,
as will be described hereinafter, they are inserted (see
FIGURE 2) in slots in the baseplate 6.

FIGURE 2 also shows a top plate 11, having slots
through which the contacts 8 are likewise inserted. As
can be seen from FIGURES 1 and 2, each pushbutton
slide 5 is fitted with tags 9 and springs 10. The baseplate
6 is formed with a front extension which extends beyond
the plate of insulating material 1, to act as a stop for the
pushbutton slide 5 provided with a nose-like projection,
14, which engages the extension when the pushbutton
slide 5 is pushed in.

A return spring, 12, is fitted in the pushbutton slide 5,
which restores the pushbutton slide 5 to its inoperative
position as illustrated in FIGURE 2.

FIGURE 3 shows, two catch slides 3 and 4 which are
mounted in the plate of insulating material 2. Two of the
pushbutton slides 5 mounted on the catch slide 3 have a
stop to ensure that operation is not possible until two
other pushbutton slides 5 have been pressed. The other
catch slide 4, has no cam projection at one button, to
ensure that when this button is pressed the adjacent one
does not spring out. The travel is the same for all the
buttons. Contacts may be provided as desired, i.e. break,
make, or change-over contacts. The depth of the push-
button slide according to the invention is equivalent to the
width of the two catch slides 3 and 4. The height is deter-
mined by the width required to accommodate the button
slides and catch slides combined, because these work in
parallel planes and not, as in known pushbutton slides,
at right angles to each other, which saves a considerable
amount of space.

The contacts 8 are all made up as units and can be
plugged in, as already stated. Thus, all that is needed is
a single movement to set up the contact studs in different
positions. The contacts 8 can be stamped out very eco-
nomically. The pushbutton slides 5 themselves are made
in one piece, preferably by press or injection moulding.

When the pushbutton switch is used for washing ma-
chines, it is sutficient, apart from the Off-button, i.e. the
larger button 5 (see FIGURE 3), to provide four selector
buttons suitable for all programmes. The “Off” button
should preferably be coloured red, and when operated it
releases all the buttons and remains in the “Oif” position,
in which the head of the button is aligned with all the
other buttons. The mode of operation of the rest of the
buttons will be apparent from ‘FIGURE 3.

FIGURE 4 shows, in particular, the baseplate 6 con-
taining slots 7 for the contacts 8, while FIGURE 5 serves,
more particularly, to show the dimensions of the front
plate 1 of insulating material, and the holes 15 for rivet-
ing the plate '1 to the plate of insulating material 2 as
hereinbefore, described. FIGURE 3 also makes clear how
the pushbuttons 5 areguided by the front plate 1. In
addition, the plates 6 and 11 (see also FIGURE 2) are
held directly by the plates of insulating material 1 and 2,
resulting in the simplification of the switch construction
already mentioned.

The manufacture and assembly of the switch is par-
ticularly simple, in that the contacts 8 are inserted into
the parallel slots 7 in the baseplate 6 and the pushbutton
slides 5, fitted with their tags 9 and springs 10, are placed
in position. Then the top plate 11 is fitted in position over
the «contacts 8, likewise ‘by their corresponding slots, and
the shoulders of the contacts 8 are bent over or set at an
angle to secure the plates 6 and 11 to each other. This
bending or setting of the contacts 8 is necessary only in
respect of two or three contacts 8 located in the middle
of the plates. A U-shaped member which is also known as
the “chassis” is then pushed into position and the front
plate 1 is riveted or welded to it. The compression springs
12 are then inserted into the recesses provided for them.
To prevent these springs from dropping out, a safety plate
16 (see FIGURE 2) is provided. Finally, the catchslides )
3 and 4 are inserted; these can .readily be replaced sub-
sequently by others. The stop by which the travel of the
pushbutton slides 5 is limited, is located in the recess for
the return springs 12, and also prevents the pushbuttons
5 from jumping out of the front plate 1.

What ‘I claim is:

1. A pushbutton switch comprising a substantially U-
shaped first member of insulating material, said member
comprising a bottom portion, integral side portions and
flange portions extending outwardly from the ends of said
side portions, a second member of insulating material
secured to said first memberpand closing off the top thereof,
 said bottom portion of said first member and said sec-
ond member respectively being provided with aligned
slots, a plurality of pushbutton slides carried in said slots
in said members, third and fourth members spaced from
one another, carried by said first and second members
and having said slides positioned therebetween, a plurality
of contacts carried by said third and fourth members
said pushbuttons slides carrying spring biased tags, means
whereby said tags engage said contacts, and at least one
catch slide being operatively engaged with at least some
of said pushbutton slides and ‘being carried and slidingly
engaged by said first member.

2. The pushbutton switch of claim 1 wherein said at
least one catch slide extends transversely to said push-
button slides and being slidably carried by said side por-
tions of said first member.

3. The pushbutton switch of claim 1 wherein said first
and second members are secured together by riveting.

4. The pushbutton slide of claim 1 wherein said first
and second members are secured together by welding.

5. The pushbutton switch of claim 1 wherein said third
and fourth members are provided with aligned slots
through which said contacts extend and wherein at least
some of said contacts are bent ‘beyond the outer faces of
said members in order to secure said members together.