GB695850A - Improvements in and relating to electric refrigerator controls - Google Patents

Abstract

695,850. Thermal switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 20, 1951 [Dec. 28, 1950], No. 29873/51. Class 38 (v) In order that the defrosting temperature of a refrigerator may be independent of the normal operating temperature, the latter is set by a spring 8 acting on an arm 24 pivoted at 25 to a further arm 12 which actuates a switch similar to that of Specification 451,832. The two arms are connected by a spring 27 so that they are normally moved as one by a bellows 2 against the action of spring 8. The arm 12 carries a spring pawl 37 which rotates a ratchet wheel 36 one step clockwise every time the switch opens. The wheel 36 carries a stop 34 which is thus moved into a position where it obstructs the end 35 of arm 24 which is thus blocked to render spring 8 ineffective. Spring 27 is made stronger than spring 8 so that a larger movement of the bellows, and hence a higher "defrosting" temperature, is required to close the switch. In a modification (Figs. 2 and 3, not shown), the contact-carrying arm of the switch has an extension engaging the edge of a disc carried by the ratchet wheel 36. This disc has a cut-away portion which permits a greater opening movement of the contact once in each rotation of the disc, thereby entailing a greater movement of the arm 12. The arm 24 in this arrangement engages a stop on the casing during defrosting. Specification 669,067 also is referred to.