GB503021A - Improvements in or relating to snap-action electric switches - Google Patents

Abstract

503,021. Snap-action switches. COFFEEN, J. M. Sept. 28, 1937, No. 26242. Convention date, Dec. 12, 1936. [Class 38 (v)] In a snap-action switch a peripherally held diaphragm exerts a continuous reaction in ono direction to open the contacts, and is moved by an actuator which engages it at a position intermediate between its centre and periphery, snap action occurring in both directions. The two insulating cup-shaped parts 11 and 14 are bolted together to form a body 10 and to grip the dished diaphragm 38 around its periphery. A stud 50, riveted to the centre of the diaphragm 38 carries a plate 51 which, when the diaphragm 38 is curved upwards to its fullest extent, makes contact with a U-shaped plate 23 held in position by a screw 30, and a terminal 25 secured to the wall of the body. The diaphragm 38 is snapped downwards past the position of maximum opposing force by an actuating member 32 comprising a stud 33, and an inverted cup-shaped member 36 which engages the diaphragm midway between its centre and periphery, a sensitive action being thereby obtained. Contact is thus broken between the terminal 25 and a terminal 46 in contact with the diaphragm 38, and established between the latter and an annular disc 21 fixed to the terminal 16. The body members may be sealed together by cement 61 in channel 60 and the hermetically sealed contact chamber 12 thereby formed below the diaphragm, may be filled with an inert gas. The Specification also describes a modification in which the diaphragm operates a bell-crank lever which forms the common contact arm of a two-way switch with resilient stationary contacts.