Temperature safety switch

In a temperature responsive safety switch including an insulating housing provided with a recess, a thermally conductive heat transfer plate mounted on the housing, a pair of electrically conductive contact elements mounted in the housing and defining an electric current path extending through the housing, one of the contact elements being a spring element which is internally stressed to tend to separate from the other contact element, a body of meltable material mounted on the heat transfer plate, and a force-transmitting plunger displaceably mounted in the housing and having one end in engagement with the body of meltable material and its other end in engagement with the spring element to maintain the contact elements in contact with one another when the body of meltable material has not melted, the improvement comprising:

• a hollow cylindrical sleeve member in which said body of meltable material is enclosed and which is oriented with its longitudinal axis extending in the displacement direction of said plunger, said sleeve member and plunger being so positioned and dimensioned relative to one another that the end of said plunger remote from said contact spring extends into said sleeve member with play in the direction perpendicular to the longitudinal axis of said sleeve member, said sleeve member being mounted in said recess in said housing, and said housing recess being dimensioned to present a space around said sleeve member sufficient to receive the entire mass of said body when the material melts and is forced out of said sleeve member by displacement of said plunger.