GB388326A - Improvements in or relating to thermally operated electrical switches - Google Patents

Abstract

388,326. Thermal switches. PAYNE, M., 50, Hook Road, Surbiton, Surrey, and BRITISH THERMOSTAT CO., Ltd., Windmill Road, Sunbury, Middlesex. Sept. 2, 1931, No. 24139/32. Divided on 385,668. [Class 38 (v).] In a thermally-operated electric switch, the movements of an expansive fluid in a bellowscontaining chamber 5 are transmitted to a two-armed lever 18, having a pin-and-slot connection with a mercury switch 17, by means of a tubular member 9 acted on by an adjustable spring control to vary the temperature at which the switch operates, one arm of the lever passing through the member 9 to engage between pegs 20, 20a fixed thereon. The control spring 8 bears against a sliding non- rotatable support 11 screwed on a spindle 14, the hand-wheel 15 of which has openings 25 for a locking-pin 34. A scale (not shown) on the support 11 is visible through a removable cover (not shown) on the casing 1 enclosing the apparatus. To promote quick movement of the switch and to vary the minimum temperature change required to move it, a spring 37 mounted on a telescopic rod 38 acts between the lever 18 and the end of a rotatable rod 41 having a pin 43 bearing against a fixed cam surface 44, an indicator 46 being provided for adjusting and locking the rod 41. The chamber 5, control spring 8, and tubular member 9 are carried by a rigid frame 2 removably mounted in the lower portion of the casing 1, the upper portion of which is divided by a rib 28 into the switch-containing compartment and into a compartment b housing terminals 29 and the current-carrying wires. When used in connection with refrigerating apparatus the chamber 5 is connected to a sealed vessel 4a in the refrigerator chamber containing expansible fluid.