ENERGIOMVANDLARE FOR OMVANDLING AV ELEKTRISK ENERGI TILL LINJER MEKANISK RORELSE

摘要

An actuator for converting electrical energy into linear mechanical movement comprises a chamber containing an expandable material and a positive temperature coefficient (PTC) of resistance heater located in thermal communication with the chamber. A first piston transmits force from the expandable material to an external load against the force of a first return spring. The first piston moves out of a casing from a retracted position at a first stop to a protracted position at a second stop at which point continued expansion of the expandable material in one embodiment causes a second piston to separate the chamber from the heat source against the bias of a second return spring. As the chamber separates the thermal resistance between the heat source and the chamber greatly increases until equilibrium is obtained between heat input to the expandable medium and pressure exerted by the medium.