GB820682A - Thermally-operated snap-action electric switch - Google Patents

Abstract

820,682. Thermal switches; switches held set and freed mechanically. LANDIS & GYR A.G. July 29, 1957 [July 30, 1956], No. 23983/57. Class 38 (5). A diaphragm 11, operated by a liquid temperature-sensing device 10, carries a rotatable threaded spindle 23 having a travelling nut 24 which supports a setting-lever 12 pivoted on two lugs 17, 18. A leaf-spring 14 connects the free end of lever 12 to a lever 13 pivoted on lugs 15, 16 and carrying an insulating member 27 with a contact 26 normally bridging contacts 28, as shown. When the diaphragm 11 is lifted the lever 13 moves the member 27 with a snapaction against back-stop 29 and opens the circuit between contacts 28. A spring-loaded crank 30 also moves downwards and locks the lever 13 against upward movement when the temperature (and diaphragm 11) falls. The operating temperature is set by adjustment of the nut 24 by rotation of the spindle 23 from outside the case in a manner not described. The switch is reset manually by depression of button 37 which causes a leaf-spring 36 to engage an arm 33 on crank 30, which is thus restored to the position shown. The switch may be manually opened by depression of a button 39 acting on the lever 13 via a leaf-spring 38.