GB774349A - Control device for refrigeration apparatus - Google Patents

Abstract

774,349. Thermal switches; snap action switches. GENERAL ELECTRIC CO. July 1, 1955 [July 1, 1954], No. 19159/55. Class 38(5) A refrigerator control device in which defrosting is initiated manually and terminated automatically comprises first contacts 2, 5 operated by lever 10 and rod 21 in response to a temperature sensitive bellows 18 to'control a compressor motor 7, and second contacts 35. 35 also in the motor circuit actuated by a manually operated member 54 to open this circuit and initiate defrosting. The contact operating lever 10 is biased upwards to the "contacts-closed" position by a spring 16 and engaged by the end 23 of rod 21 which is connected to the bellows 18 and biased downwards by spring 30. Lever 10 has two positions one at lower temperature when the contacts 2, 5 open and one at a first higher temperature when they close. The first higher temperature is determined by the degree of compression of spring 30 which is adjusted by knob 29 rotating a cam 28 to move a spring supporting plate 25. The contact 36 is carried by a spring blade 37 which forms a snap action toggle mechanism with the spring blade 49 and lever 46 which is pivotally connected to the housing by a leaf spring 48, the lever 46 being provided'with a screw 51. Depression of member 54 tilts the screw causing contacts 35, 36 to open, thus de-energizing the motor and at the same time a third set of contacts 36, 34 are closed to energize a'defrosting heater 42. As the temperature rises the operating rod 21 moves upwards from the position shown in Fig. 3, first closing the contacts 2, 5 at the first higher temperature and then at a second higher temperature the end 23 engages the screw 51 actuating the toggle mechanism thereby opening the heater circuit and closing the motor circuit. The second higher temperature is adjusted by the positioning of the screw 51.