GB1315089A - Oven control system including single dial control - Google Patents

Abstract

1315089 Thermal switches; cam-operated switches WESTINGHOXJSE ELECTRIC CORP 15 Nov 1971 [31 Dec 1970] 52880/71 Heading H1N [Also in Division H2] Means for adjusting the operating temperature of a snap-action thermostat for an oven with cooking and heat-cleaning, comprises a manually rotatable structure 30, 16 with a larger range of angular adjustment for cooking than for heat-cleaning, means 26 movable to adjust the operating temperature, and means 31, 32 for translating the angular adjustment of the rotatable structure into movement of the operating temperature adjusting means 26, which movement, for a given angular adjustment of the rotatable structure, is larger in the heat cleaning range than in the cooking range. As shown, pressure wafer 27 connected by capillary tube 28 to an oven temperature sensitive bulb (not shown) bears against spring arm 20 bearing against the casing at its lower end 21 and against shaft 26 to snap over spring 23 and move bridging contact 18 to open contacts 8c, 2b (and also contacts 9c, 1b, Fig. 3 (not shown), to open the circuit to the heating elements. Spring 23 is adjusted by screw 25. Rotation of shaft 30 coupled to a temperature indicating dial, Fig. 11 (not shown), rotates cup-shaped member 16 which rotates cam follower 31 having two arms 37a, 38a, the end of arm 38a being bent to engage the cam surface on the end of fixed cam 32 so that as cam follower 31 is rotated it moves axially under the pressure of spring arm 20 to move shaft 26 adjustably fixed to cam follower 31, to adjust the temperature operating point at which spring arm 20 snaps over. The gradient of the cam surface on the end of cam 32 is greater, Fig. 10 (not shown), in the heat cleaning range than in the cooking range so that for a given angular movement of shaft 30 the axial movement of cam follower 31 and shaft 26 is greater during the heat-cleaning range than during the cooking range. The final heat-cleaning temperature can be adjusted by turning setscrew 45 in cam 32 against which cam follower 31 bears at the end of its travel. The contacts 8c, 9c are connected to movable contact blades 8, 9, Fig. 1, in the upper compartment 12 which are moved by cam surfaces on the outer periphery of member 16 to co-operate with fixed contacts 4b, 6b, 7b to vary the circuit connections to the heating elements in the oven as shaft 30 is rotated. A circuit diagram, Fig. 12 (not shown), is given for the connections to the various heating elements.