GB724628A - Improvements in control switches for electric motors - Google Patents

Abstract

724,628. Temperature-responsive actuating- elements. GENERAL MOTORS CORPORATION. July 22, 1953 [Aug. 5, 1952], No. 20311/53 Class 64 (2). [Also in Group XXXVII] A control switch for an electric motor (see Group XXXVII) comprises a rib 42 of insulating material to which is riveted a U-shaped bi-metallic member 65 with one leg 46, forming the starting member, having its high expansion side facing outwardly from the centre of the base of the switch. The rib 42 also carries an ambient temperature-compensating strip 48 also having its high expansion side facing outwardly, the adjacent movable ends of the strips 46, 48, being connected by a toggle leaf spring 50. The end of the strip 48 is notched while the adjacent end of the strip 46 has an aperture for receiving the notched end of the spring 50 which biases the starting strip to the position shown. A bi-metallic member 57 has one end anchored to terminal 60 and its portion 157 bent at right angles and provided with a U- shaped portion with an arm 63 engaging the strip 46. A localized coating 146 of insulating material is provided on the strip 46. When heated, the strips 46, 57, will deflect toward each other. A ribbon type electric heater 64 is riveted at its lower end to the yoke portion of the member 65 and is connected to the part 157 of the strip 57 at 164. The compensating strip 48 is provided with a stiffening rib 491 which controls its movement under changes in ambient temperature. The lower portion of of the member 65 is provided with a cantilever overload bi-metallic strip 66 which is compensated for ambient temperature by means of strip 76 and toggle spring 78.