Interface relay for high current equipment

Abstract

Disclosed is a relay for high current equipment, such as, for example, an electric range. The relay provides the interface between the solid state electronics and the high wattage electric heating elements. The relay is comprised of a frame having a non-electrically conductive, flexible substrate, such as a plastic substrate supported at its ends with a shallow V cross section. The substrate has conductive heater elements formed thereon with heater terminals connected to said elements. The plastic substrate has a high coefficient of thermal expansion. A biasing member in contact with the apex of the plastic substrate transmits forces between the substrate and a switch assembly, either creep or snap acting. The upper switch arm preloads or couples a force between the biasing element and the plastic substrate causing a shallow V to be formed in the substrate. When current is applied to the heater terminals and heats the heater element, the substrate expands. This expansion of the plastic substrate is amplified into a larger displacement of the apex of the V due to the geometry of this construction. The motion with amplification of the plastic substrate causes the switch to change from a first state to a second state. When current is removed from the heater elements, the plastic cools and contracts causing the switch to change back to its first state.