THERMAL SWITCH Russian patent published in 1998 - IPC

FIELD: overtemperature sensors such as overheating or fire alarms. SUBSTANCE: switch has heat-conducting case, contact group insulated from case and built up of movable contact in the form of spring-loaded plate and fixed contact, as well as heat-sensing member made of material with transformation induced plasticity that mechanically actuates movable contact; novelty is that heat-sensing member is made of wire made of metal with transformation induced plasticity in the form of section whose both ends are rigidly fixed, its memory being set throughout its entire length to respond to temperatures exceeding shape recovery temperature; at temperatures lower than shape recovery point it is stretched due to spring force of movable contact directed perpendicular to straight line between fastening points of section ends; displacing action on movable contact is wire force set up in recovery of memorized length of section. Wire section may be fixed either directly to spring-loaded overhanging plate of movable contact or to clamp or frame specially introduced for the purpose. EFFECT: simplified design, reduced lag time, facilitated manufacture, improved operating reliability. 3 cl, 3 dwg