Normally closed pressure responsive switch with improved compact

Abstract

A compact, low cost, pressure responsive electrical switch of improved reliability has simple and easily assembled contacts movable on a base between open and closed circuit positions. A dished metal disc is operably connected with a diaphragm to move with snap action between original and inverted dished configurations for moving the contacts sharply between such circuit positions when selected pressures are applied to the diaphragm. The contacts are biased to open the circuit; a first, convex side of the disc engages and holds the contacts firmly in closed circuit position against the noted bias when the disc is in its original dished configuration; a selected diameter portion of that first side of the metal disc engages an annular ridge on the base; and a motion transfer member is located between the diaphragm and the opposite side of the disc, the member having an annular ridge of relatively larger diameter than the ridge on the base engaging a correspondingly larger diameter portion on the opposite side of the disc near the disc periphery. The member moves in response to application of a selected pressure to the diaphragm to press the disc against the annular base ridge to snap the disc to its inverted configuration and to withdraw the originally convex disc side away from the contacts for permitting the contacts to follow the disc movement to fully and reliably open the device circuit.