GB544530A - Improvements in or relating to temperature control apparatus for mechanical refrigerators - Google Patents

Abstract

544,530. Automatic control systems; thermal switches. SHEPHERD, G. R. (Westinghouse Electric International Co.). March 14, 1941, No. 3500. [Class 38 (iv)) [Also in Group XXXVII] Temperature. Refrigerating apparatus, comprising an evaporator and motor driven compressor with a thermostatic switch 22 in heat exchange relation with the evaporator for opening and closing the circuit of the motor 15 has an electrical heater 30 in heat exchange relation with the thermostatic element and a single manually actuated member 67 controlling the circuits of motor and heater whereby the motor may be completely de-energized or continuously operated or the motor may be operated cyclically in response to one or more selected mean evaporator temperatures according to the setting of the member. The temperatures are varied by varying a resistance 64 in the heater circuit. A modified circuit compensating for external temperature conditions subjects the heater to thermostat control jointly within the motor. The thermostatic element is preferably a crinkled bi-metal snap disc 25 and operates a contact 35 against spring tension adjustable by a member 46 to determine response temperature a second adjustment 45 determining temperature range. The parts are hermetically sealed in a chamber 26. The heating element 30 may be inside or outside the chamber. Heat insulation 23 is arranged between the evaporator 18 and the thermostatic element.