GB879079A - Control apparatus for refrigeration - Google Patents

Abstract

879,079. Thermal switches. RANCO Inc. Dec. 14, 1959, No. 42377/59. Class 38 (5). A control device for a refrigerator comprises manually operable means for temporarily altering one limit of the normal temperature cycle to a predetermined value outside this range irrespective of the adjustment of the normal limits, for defrosting or quick-freeze, whereafter the normal cycle is restored. The embodiment described is arranged for defrosting. A temperature-responsive capsule 12 operates a snap-action switch 15 through a lever 16 pivoted at 17 and loaded by a spring 33 whose tension is adjustable by a knob 38 which controls a cam 37 acting on the lever 36, also pivoted at 17. The defrosting means comprises a lever 40 pivoted at 41 and coupled to a push knob 43 by a rod 42 passing loosely through a bore in the knob 38. The lever 40 is thus movable by knob 43 to bring an arm 44 thereon into engagement with a stop 45 or with a screw 46 on an extension of lever 16. Opposed springs 50 and 53 act on lever 40, the spring 50 being stronger than spring 53, but so attached that its centre-line moves close to the pivot 41 when arm 44 engages stop 45 thereby reducing its effective bias so that lever 40 tends to be maintained in the position to which it has been moved. Thus after knob 43 has been depressed, the arm 16 is acted on by an additional force due to springs 50 and 53, and a higher temperature has to be attained before switch 15 is reclosed, whereafter arm 44 rests against stop 45 and normal cycling ensues. The spring 53 is anchored to the lever 36 such that its tension is varied with adjustment of spring 33 and by suitable choice of springs the defrosting temperature is independent of the setting of knob 38.