Patent GB-1130357-A (GB)
Title: A timing system for washing machines
Inventor: ACHERMANN ALBERT
IPC: D06F34/06
Filed: 1965-09-14
Abstract: 1,130,357. Automatic washing machines. LANDIS & GYR G.m.b.H. 14 Sept., 1965, No. 39165/65. Heading D1A. In a washing machine control, a timer advances through a series of positions to control a series of operations and comprises a variable resistance adjustable according to the position of the timer and connected in the control circuit of a relay circuit together with a resistance 30 varied by temperature or some other condition, the relay circuit controlling a heater 1 for adjusting the temperature or means for adjusting the other condition. The timer comprises contacts controlling windings 5-8 which control a heater 1, spinning motor 2, outlet pump motor 3 and a washing motor 4. A motor 10 actuates a change-over switch 9 to reverse the washing motor periodically and at intervals, e.g. one minute, closes a pulse switch 11 to advance motor 12 step by step. Motor 12 advances cam shaft 14 step by step, its cams acting on contacts 15-20 controlling windings 5-8 and contacts 26-28 connected in a circuit including resistance 30 which has a negative temperature coefficient. The timer also includes start key 21 and selector keys I-III each associated with a predetermined programme. The system is energized through a door switch 23 and contact 19' alternately closes the circuit of an inlet valve 25 and the circuit of coil 5. Switches 26-28 allow connection of the control circuit to selected tappings of a voltage divider comprising resistances connected to a d.c. source 31, the connection to the positive terminal of source 31 being through resistance 38 and including a change-over switch 50 controlled by cam shaft 14 so that resistance 30 and level switch 51 are alternatively connected in the circuit. The control circuit comprises an electronic Schmitt trigger comprising transistors 32, 33 energized by d.c. source 31, a low ohmic resistance W being connected in parallel to the emitter collector stretch of transistor 32 which is conducting when the trigger is in its rest position. The relay winding 34' in the collector circuit of transistor 32 operates a rest contact 35' in the circuit of the advancing motor 12 of the timer. One complete rotation of shaft 14 comprises 45 steps. When the switches 22, 23 of the door and soap chamber have been closed, one of the keys I-III is actuated and remains actuated. Actuation of key 21 advances the cam shaft to its start position and contact 15 holds the circuit to maintain motor 10 continuously energized to advance shaft 14 step by step, each step being terminated by contacts 13 controlled by shaft 14. If switch 51 is opened or resistance 30 is high, i.e. the water has not reached the required level or temperature respectively, relay 34' is energized, contact 35' is opened and stepping on of the cam shaft 14 is prevented. In an alternative arrangement, Fig. 2 (not shown), the voltage divider arrangement comprises an insulating disc (40) with printed conductors on both faces. Switches 16, 18, 20 Fig. I permit the jumping of positions of shaft 14 when closed by the appropriate cam on shaft 14.