SURFACE TEMPERATURE-RESPONSIVE SWITCH USING SMART MATERIAL ACTUATORS

Malfunction or failure of mechanical, electrical, and electro-mechanical equipment, for example, equipment used in manufacturing operations, is often preceded by an increase in the operating temperature of at least some portion of the equipment. A temperature-sensitive, active material-containing actuator is pre-selected to operate at a pre-determined temperature indicative of impending equipment failure and placed in thermal contact with the equipment. If the equipment achieves the pre-selected temperature the actuator signals this by closing an externally-powered circuit to enable or provide a suitable alarm signal. Additionally, the actuator may close a second circuit connected to a machine controller to alert the machine controller to take some pre-programmed action. Selected actuators are based on shape memory alloys (SMA) adapted to operate over a temperature range sufficient to encompass the expected range of pre-determined temperatures.