Patent GB-1174212-A (GB)
Title: Electronic control system for dishwashing and other washing apparatus
IPC: D06F34/08
Filed: 1968-03-12
Abstract: 1,174,212. Dishwashing machines. WHIRLPOOL CORP. 12 March, 1968 [20 April, 1967], No. 11982/68. Heading A4F. [Also in Divisions D1, G3 and H3] An electronic system for controlling dish washing or other washing apparatus, and including solid state devices, comprises a timing circuit which emits an output signal a selected one of a plurality of delay periods after receipt of an input signal, a ring counter stopped by the timing circuit to control liquid admission, draining, and recirculating devices associated with a washing chamber, a switching circuit having a plurality of switching stages actuated by the counter in sequence, each actuation being at the end of a washing or rinsing cycle, and means responsive to signals from the counter and from the switching circuit for selecting the desired delay periods for the timing circuit. The closing of a starting switch 10 energizes, via an OR gate 14, a power unit 12 to activate an inverter 16 to energize a water pump motor 18. The power unit 12 also energizes a water inlet valve 32 via OR AND gates 30, 20 in a ring counter 82. A signal also passes via the AND gate 20 to OR and AND gates 38, 36 to produce an output signal from a timer 40 after a delay period of 2 minutes, the period of the first rinse. The initial energization of the power unit 12 sends a pulse via a selector switch 47, and OR and AND gates 52, 50, to actuate a RINSE 1 indicator 54, e.g. a lamp, in a switching circuit 84. At the expiration of the 2 minute delay the timer 40 activates the inverter 16 to produce a negative pulse which de-energizes the AND gate 20 and shuts the water valve 32. On cessation of the negative pulse a waveform generator 56 produces a pulse to actuate via OR and AND gates 58, 22 a heating unit 60, and activate the timer 40 via an AND gate 64 to produce an output pulse after a 3 minute delay. This. causes a waveform generator 74 to activate OR and AND gates 76, 24 to open a drain valve 78 and deenergize the heater 60. These operations of filling, circulating water, and draining are repeated in subsequent washing, rinsing and drying stages similarly controlled by the circuitry illustrated in the drawings. The selection of the periods of the various rinsing, washing, and drying stages is effected by signals applied to AND gates of the timer 40 from the counter section 82 and from inverters 70, 72 receiving signals at appropriate times from the switching circuit 84. Figure 2 illustrates the electronic circuitry in which the timer 40 comprises a capacitor 290 which is chargeable through a potentiometer 292 and various alternative paths including diodes 290, 308, 310 and respective series resistors 296, 312, 314 to cause after selected time delays activation of a unijunction transistor 298 and thereby activation of NPN transistor 154. Silicon controlled rectifiers 158, 160, 162 in the ring counter 82 are responsive to the conduction and non-conduction of the transistor 142, and the ring counter 82 controls Triacs 264, 274, 306, 316 in series with the water pump motor 18, the water inlet valve solenoid 32, the heating coil 60, and the drain valve solenoid 78. The switching section 84 comprises silicon controlled rectifiers 194, 196, 198, etc., in series with RINSE 1, WASH 1, WASH 2, etc., indicators, and controlled by NPN transistors 150, 156.