GB595626A - Improvements in thermostats - Google Patents

Abstract

595,626. Thermal switches; snap-action switches. GENERAL ELECTRIC CO., Ltd., and EDEN, C. G. Sept. 8, 1943, Nos. 14713 and 21457. [Class 38(v)] In a thermostat, the thermally-operated member 12 acts on a lever 26 hinged at its right hand end to the base and at its left hand end to one end of a rigid member 37 the other end of which is hinged to one end of an extensible member 30 hinged to the base at its other end, the arrangement being such that the members 26 and 30 are in tension and the member 37 in compression and adapted to pass through a deadcentre position. The member 30 in the form shown consists of two corrugated metal strips which hold the member 37 in the position shown so long as the line of them lies above the centre line of member 37. When a thermal member such as an expanding tube causes the rod 12 to rise the member 37 is raised past the line and the spring 30 then snaps the member 37 downwards so that a contact 32 engages a fixed contact 16. To adjust the thermostat for different temperatures the whole switch may be mounted on a platform that is adjustable towards or away from the rod 12 and the rotary knob that does the adjustment may have an extreme " off " position in which the switch is " off whatever the temperature. In a modification, a threepronged non-corrugated sheet steel member takes the place of the corrugated member 30 and the member 37 and an extension of the middle prong 102, Fig. 12, carries a bridging contact 105 adapted to engage and align itself with two fixed contacts 106.