GB434064A - Improvements in or relating to circuit controlling devices, particularly applicable to electric refrigerators - Google Patents

Abstract

434,064. Thermal switches; automatic circuit-breakers, IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London. (Assignees of Kuhn, C. W. ; 12th Street, St. Paul Avenue, Milwaukee, Wisconsin, U.S.A.) Nov. 16, 1934, No. 33026. Convention date, Jan. 29. [Class 38 (v)] A circuit-controlling device for an electrically operated refrigerator, comprises fixed contacts 8 adapted to co-operate with a movable bridging contact 10 on an arm 12 pivoted on a fixed bracket 11 and connected by a tension spring 14 to a second arm 13 pivoted at an adjacent point on the bracket 11. A knob 6 is connected by a slide 32 to the arm 13 so that by moving the knob 6 axially the circuit can be opened or closed with a dead-centre snap-action. The switch is also operated automatically by means of a temperature sensitive bellows 70 operating against an adjustable spring 73 to turn a lever 72 about a pivot 79. The lower end of lever 72 carries a point 194 which bears on a spring 88 the other end of which bears on the end 93 of a lever 90 pivoted at 89. From the open position shown, if the bellows expand, the point 94 moves to the right across the point 89 thus moving the point 93 rapidly to the left to withdraw a plate 96 from engagement with contact 10 which then closes under the action of spring 14. On contraction of the bellows the reverse action takes place to open the circuit. The circuit is also opened on overload by a member 46, Fig. 7, biassed to the left by a spring 56 and having a latch 57 which engages a toothed wheel 53 normally held stationary by fusible metal surrounded by a heating coil 48, Fig. 2, connected on the driving circuit. On overload the metal fuses to release the latch 57 and the member 46 moves to the left, Fig. 7, due to spring 56 to engage spring 14 and open the circuit even if the knob 6 is held in the on position as shown in Fig. 7. The device is reset by pulling out knob 6 and pushing it in, the plate 46 being arranged so as to tilt on passing a fixed projection 54 which disengages it from the knob 6 before the circuit is remade. This ensures that the device cannot be reset until the fusible metal has set.