GB788645A - Improvements in or relating to temperature responsive devices - Google Patents

Abstract

788,645. Temperature-responsive actuating-elements. ROBERTSHAW-FULTON CONTROLS CO. May 2, 1956 [Aug. 5, 1955], No. 13562/56. Class 64(2) A temperature-responsive apparatus comprises an expansible and contractible member 10 having a part 18 arranged for movement upon expansion or contraction of the member, a temperature sensitive bulb 14, and a tube 12 connecting the bulb and the member in a closed system filled with fluid, the bulb having at least one portion formed of materials having different co-efficients of thermal expansion so that its volume is unaffected when all of its wall has undergone a temperature change. The bulb may be formed from a sheet of bimetallic material with the high expansion side forming the exterior surface and have a recess 26 filled with a flexible insulating substance 32. Upon an increase in temperature, the chamber 23 within the bulb contracts due to flexing of the legs 30, 30 of the uninsulated portion so that fluid is injected into the member 10 to provide an instant response in anticipattion of the fluid expansion, the legs 30, 30 being restored to their original positions after the increased temperature has reached and expanded the portion 26. A fall in temperature produces a temporary increase in the volume of the chamber 23. The substance 32 may be removed to provide a chamber of constant volume for all temperatures. The element 10 may consist of a pair of corrugated discs connected to a support by a threaded stud 16 and arranged to operate a valve or switch. The bulb 14 is welded or soldered to the tube 12 and has an end 22 which is flattened or crimped after the system has been charged with fluid under pressure.