Patent GB-909745-A (GB)
Title: Control device for washing machines
IPC: D06F34/08
Filed: 1959-07-15
Abstract: 909,745. Washing-machines. BUSCHJAEGER DUBENER METALLWERKE A.G. July 15, 1959 [July 19, 1958], No. 24366/59. Class 138 (2). [Also in Group XXXVII] A control device for washing-machines, such as domestic laundry washing-machines, comprises a thermostat for controlling the heating current circuit and a clockwork or motor-driven time switch for controlling other electrical circuits determining the automatic operational sequences, the thermostat and the time switch being coupled in such a way that, when a preset temperature is reached, the thermostat switches off the heating current and actuates the time switch. In one embodiment (Fig. 1) the time switch comprises a cam-plate 5b driven by a hand-wound clockwork 5 which may be arrested by a brake magnet 6, the armature 6a of which co-operates with the balance 5c or other moving part of the clockwork. This cam plate controls the sliding switch 4 in the circuit of the motor 3 performing the mechanical drive of the machine. The washing time is preset by turning the cam-plate 5b into the appropriate position and thus closing the contacts U, V of the sliding switch 4. However, the motor circuit is not yet closed since it includes a contact 2d which is not made until the desired temperature is reached when the heating circuit 1 is disconnected by the thermostat switch 2. Since the circuit of the brake magnet 6 has simultaneously been broken by the thermostat switch 2, the clockwork 5 is no longer arrested and commences operation. After a predetermined period, the preset cam-plate 5b reaches its zero position and opens the sliding switch 4 thereby terminating the washing operation. In an alternative embodiment the time switch is operated by a synchronous motor, the circuit of which is closed when the heating circuit is disconnected. With the control arrangement of Fig. 5, the mains terminals R.S. are connected not only to the thermostat switch 2b but also in parallel to the time-controlled switch located in the circuit of the motor 3b. Above the cam 5j is a roller 8 supported by levers 8a, the stop 8c of which is pressed by the action of spring 8b against the support 8d. Fig. 7 shows the camplate 5i rotated through an angle in the winding- up direction and although the cam 5j no longer acts as support for the slide 4h, the slide is still in the disconnecting position since it rests against the roller 8 which rests in turn against the preferably serrated cylindrical shoulder 5k of the cam-plate 5i. When the cam-plate turns in the direction of rotation, the roller 8 is pushed back by the friction between it and the shoulder 5k allowing the slide 4h to assume the operating position. Whilst the thermostat of the control of Fig. 1 is designed only as a switching-off thermostat (if it were designed as control thermostat so as to keep the temperature constant during the washing, each short period switching on of the heating current would entail a disadvantageous interruption of the washing process) the modifications shown in Fig. 5, which may also be used where a synchronous motor is employed, make it possible to use a control thermostat.