DE2122879B2 - Washing machine safety arrangement - activated by heating without water or by stalling of motor during emptying or spinning - Google Patents

Abstract

The washing machines DC motor is fed through a rectifying circuit from the AC mains, and a temperature sensor mechanically and thermally connected with a heating element which is in series with the motor is arranged to control a thermostat having a contact connected in series with the motor supply circuit and with a circuit in parallel therewith which includes a contact of the washing cycle programmer.

Description

45

The invention relates to a protective circuit device for a by means of a program switch Controlled washing machine with a DC motor fed via a rectifier bridge to the Reversible drive of the laundry drum, one in series with the DC motor switched heating element for the detergent solution, one consisting of a temperature sensor and a thermal switch Thermostats for the detergent solution, a solenoid valve for the water inlet and a pressure switch for Check the lye level.

Such a washing machine is known from DT-OS 24 041. If the engine is heavily loaded will, e.g. B. in the washing process, it has a low rotation speed and has a high power consumption, whereby a large amount of power is converted into heat in the heating element. However, the engine has at low load, e.g. B. when spinning, only a low power consumption, then that is the heating element low current flowing through. The heating element protects the motor and prevents it from being overloaded.

To interrupt the heating process when the predetermined for the washing process is reached Temperature usually a thermostat is used. In the known machines is the Temperature sensor housed in the tub wall. The information received from the thermostat relates to therefore on the temperature of the detergent solution. Excessive heating of the heating element is therefore only transferred after a relatively long time and too late in order to avoid any damage.

It is therefore the object of the invention to provide a protective device to be set up in such a way that they can be operated quickly if the engine power consumption is too high and the heating is at the same time

appeals to.

This object is achieved in a protective device of the type mentioned in that the Thermal switch is connected in series with the heating element and with a parallel circuit, which consists of the Gieichrichterbrücke and at least one program contact Containing engine lockup exists, and that the heating element is thermally connected to the Temperature sensor is coupled.

These measures provide a high level and quickly effective security against heating of the Machine reached without water filling (anti-mosquito protection).

Another advantage of the invention is that the power generated by the power control circuit of the Motor is controlled, is low, as the heating is only switched on when the motor is at a standstill. This makes possible, to use a regulation by phase control, without inadmissible disturbances in the Alternating current network.

Refinements of the invention are given in the subclaims.

The invention is explained in more detail with reference to the drawings.

F i g. 1 shows the essential basic components of the device according to the invention,

F i g. 2 an expanded circuit diagram.

A motor M for driving the drum of a washing machine is fed via a controlled rectifier bridge 10 from the alternating current network. The engine speed is regulated by a control unit 9. The rectifier bridge 10 is connected in series with a thermal switch 8 with two switching contacts 81 and 82 and a heating element 6 to the alternating current network. A circuit connected in parallel to the rectifier bridge 10 contains a program contact 4.

The winding of a solenoid valve 1 to the water inlet and are also connected in series to the alternating current network a pressure switch 2 is connected, which has two contacts 21 and 22. Contact 21 is when the vat is empty and contact 22 is closed when the vat is full.

The thermal switch 8 controlled by a temperature sensor 7 has two contacts 81, 82. So long the temperature remains below a predetermined value, the contact 82 is switched on. Will When the predetermined temperature value is reached when heating up, the thermal switch switches to the contact 81 um.

The device for reversing the direction of rotation of the motor is not shown with the exception of one of her assigned contact 5.

The washing process proceeds as follows: At the beginning (empty tub) the pressure switch 2 contact 21 closed; the solenoid valve 1 is energized and the vat is filled with lye. If the

Lye has reached the predetermined level, the pressure switch 2 switches to the contact 22, whereby the solenoid valve 1 is switched off and filling is ended.

Program contact 3 is now opened and contact 4 is closed. Contacts 3 and 4 become controlled by the same cam of the program switch.

The thermal switch 8 has closed the contact 82, which corresponds to the cold state. When contact 5 opens, motor M is fed via dds heating element b. Because of the series connection of the motor M and the heating element 6, heating is now carried out with reduced power.

If, on the other hand, the motor M is stopped by closing the contact 5, the heating element 6 is fed directly from the mains and the heating takes place at full power.

When the desired temperature is reached, the thermal switch 8 interrupts the motor circuit by switching to the contact 8t. The program switch, which then opens contact 4, is switched on in a manner not shown. After some time, about 2 minutes, the lye has cooled down sufficiently (by about 5 to 7 °) to allow the thermal switch to switch back to contact 82. The motor M is energized again, and the heating element 6 heats again with reduced power. The duration of the washing process is determined by the selected program sequence.

During the spinning process or when emptying, contact 3 is closed; contact 4 is open. The motor M is fed again via the heating element 6. The reduced heating power is therefore not sufficient to cause dangerous heating, especially during de; For the most part, water is present on the bottom of the vat (where the heating element is located).

If the heating process starts with a defective machine without lye (drying out), the heating element will turn off 6 brought to a high temperature quickly. The thermally coupled with the heating element 6 The temperature sensor then causes the thermal switch 8 to switch to contact 81 very quickly will. The wash cycle sets; without damaging the laundry or other elements of the machine (especially the engine). When the laundry is taken out, it turns out that the laundry is still dry and dirty; but furthermore nothing unpleasant happened.

If an item of laundry gets between the drum and the wall of the tub, the motor can blocked. Blocking the motor during the washing process does not have any disadvantages, since there is lye in the vat; the liquor is heated to the predetermined temperature. When the machine goes to emptying or spinning, the circle becomes relatively high Current flows through it, so that the heating element provides sufficient power to the contact arm of the Therno switch 8 to think about contact 18 and stop the engine. After a certain Time, when the temperature has dropped, the contact arm of the thermal switch 8 returns to the contact 82 back, whereupon the motor is re-energized and the heating element is reheated. This change will continued until the end of the cycle.

1 sheet of drawings

Claims (4)

Patent claims: 1. Protection circuit device for a washing machine controlled by means of a program switch with a direct current motor fed via a rectifier bridge to the reversible direction of rotation Drive the laundry drum, a heating element connected in series with the direct current motor for the detergent solution, a temperature sensor and thermal switches existing thermostats for the detergent solution, a solenoid valve for water inlet and a pressure switch to control the suds level, characterized in that that the thermal switch (8) with the heating element (6) and with a parallel connection is connected in series, consisting of the rectifier bridge (10) and at least one Program contact (4, 5) containing engine bypass, and that the heating element (6) μ is thermally coupled to the temperature sensor (7). 2. Apparatus according to claim 1, characterized in that in front of the thermal switch (8) another Program contact (3) is provided for bridging the * s one contact (22) of the pressure switch (2) and that the other contact (21) of the pressure switch is in series with the solenoid valve (1) from the other program contact (3), the thermal switch (8), the motor circuit (10) and the Heating element (6) formed series circuit is connected in parallel. 3. Apparatus according to claim 2, characterized in that the one program contact (4) of the Motor override and the other program contact (3) through the same cam of the program switch controlled so that one program contact is open when the other program contact is closed. 4. Apparatus according to claim 1, characterized in that the one program contact (5) of the motor lock-up is closed while the motor (M) is at a standstill.