Patent GB-1019820-A (GB)
Title: Programme control apparatus
IPC: G05B19/44
Filed: 1964-06-18
Abstract: 1,019,820. Dishwashing machines. ROBERTSHAW CONTROLS CO. June 18, 1964 [Aug. 26, 1963], No. 25304/64. Heading A4F. [Also in Division F2] A programme control apparatus for a dishwashing machine comprises a rotatable control member, means for rotating said control member between positions at a selected speed, and pneumatic means including an actuator part controlled by movement of said control member and adapted for over-riding the means for rotating the control member to move the member rapidly to particular positions thereof. The one control member may thus be utilized for controlling a selected one of a number of different programmes. In the apparatus illustrated the control member 21 comprises a flexible sheet 24 secured to a rotary member 25 (Fig. 2, not shown) to define an annular cavity which communicates with the atmosphere through apertures in the member 25. The member 25 carries gear teeth engaging with a pinion on the drive shaft of a timer motor whereby it may be rotated at constant speed relatively to a plate 22 provided with ports. As the sheet 24 rotates pairs of the ports in the plate 22 are interconnected by recesses in the sheet 24 in sequence to initiate the steps of a programme, e.g. the first recess of a row 36A bridges ports 50, 71 to connect a vacuum pump 52 to the vacuum operated actuator of the drain pump motor. The operation of the drain pump motor is terminted when a groove 107 in the sheet 24, vented to the atmosphere, reaches the port 71. The recesses and vented grooves in the sheet 24 are arranged to provide either of two alternative programmes determined by the setting of a selector device 62. The latter comprises a disc 79 rotatable by a selector knob 78 having recesses 82, 83, 84 for selectively interconnecting ports 59, 60, and 65 in a plate 61 (not shown). In the position A of the selector knob 78 the recess 84 interconnects ports 59, 60 whereby one programme is operated, and in the position B the recess 82 interconnects ports 60, 65 whereby the other programme is operated, whilst in the position "CANCEL", the recess 83 interconnects the three ports 59, 60 and 65 to cancel the previously selected programme. A washing operation is commenced by closing an electric switch 89 by pressing a button 102 on a plunger 100 to cause a pivoted blade 93 to actuate the switch plunger 92. The plunger 100 is held in its inner position by the engagement of the blade 93 in a groove 104 therein so that the switch is closed until the end of the washing operation when vacuum is applied through the control member 21 and a conduit 70 to collapse a bellows 68 secured to the blade 93 to disengage the latter from the groove 104. When the switch 89 is closed the timer motor rotates the control member 21 at constant speed for the vacuum operation in sequence of the various actuators; but at selection positions of the member 21 ports 54 and 57 are interconnected by a recess in the sheet 24 to interconnect the vacuum pump 52 and a bellows 45 which is thus collapsed to pull a spring coiled around a one-way clutch on the shaft carrying the control member 21, to rotate the latter rapidly to a further position from where it continues to be rotated by the timer motor.