Cutler-Hammer, Inc.

Eric L Long

A trigger switch for portable tools that provides safety disconnect under contact-weld conditions. The switch is a manual close, return spring open, double-snap type wherein the actuator acts on a double-inclined surface of a cam to snap the switch contacts closed or open as the actuator passes the center high point of the cam in one direction or the other. The safety disconnect feature provides in series with the switch contacts a connector biased to flip open that is normally held closed by actuator reactance force on the cam in combination with tripping means therefor. This tripping means includes coacting means between the cam and a contact carrier on which the cam is normally spring-restrained from shifting in the switch opening movement direction of the actuator. If the contacts weld, switch opening movement of the actuator under force of the stored energy of its return spring, and without requiring any additional external force, forcibly shifts the cam to a point allowing it to trip down in the contact carrier and release the connector allowing it to flip open and interrupt the connection permanently.

Safety disconnect electric switch

An electrically conductive annular elastic contactor is trapped in a cavity in a housing defined by a bottom wall and left and right side walls. A movable operator cammingly engages the contactor, compressively deforming it until an overcenter position is passed, after which the contactor snaps against the opposite side wall to make and/or break contact with stationary contacts mounted on at least one of the walls.The contactor acts both as the movable contact for engaging stationary contacts and as snap action biasing means for effecting switching operations. Due to the resilient deformation of the contactor, there is afforded a torsional shearing of contact welds.

Switch using resilient annular contactor

An electric snap-action switch is disclosed having a movable contactor with oppositely inclined camming surfaces meeting at an apex on the top thereof. The contactor is centrally biased upwardly from below and cammed downwardly from above by a laterally movable operator traversing the inclined camming surfaces such that the contactor snaps laterally against vertical stationary contacts as the apex is crossed by the operator. The invention includes fulcrum means effective to stop the downward movement of the contactor before the operator crosses the apex whereby a moment arm is formed from a fulcrum to the point of operator-contactor engagement such that further movement of the operator towards the apex effectuates a torque on the contactor to pivot the contactor about the fulcrum to positively break any welds or other frictional attachments between the contacts without relying on the stored energy of the carrier biasing means, thereby affording a switch having little possibility of failure in an 'on' position. The inclined camming surfaces of the contactor may be formed with compound slopes to assure constant operator pressure prior to trip point as the contactor pivots and increases the angle of inclination of the camming surface traversed by the operator. Specific embodiments of a double-pole single-throw trigger switch and a double-pole double-throw toggle lever switch are disclosed.

Growing community of inventors

Mequon, WI, United States of America

Eric L Long