Patent ID: 8522545

Claim:
A heat-driven engine comprising (a) a thermally conductive path into said engine, from a heat source; (b) a working medium of a thermostrictive material, having a first temperature of transformation, positioned adjacent to said thermally conductive path; (c) a heat pump of phase change material positioned adjacent to said working medium; (d) an actuator controlled to apply stimulus to said heat pump, causing a phase change and an associated release of thermal energy, to drive said working medium above its low-to-high temperature of transformation and controlled to alternatingly remove said stimulus from said heat pump, causing said phase change to reverse, and an associated intake of thermal energy, to drive said working medium below its high-to-low temperature of transformation; and (e) heat flow through said thermally conductive path maintains said working medium at a temperature range that permits said heat pump to so drive said working medium temperature.