Joseph CunninghamHerndon, VA

4388965, Jun 21, 1983

Dec 21, 1979

6/106192

Joseph W. Cunningham - Rockville MD
Lawrence D. Wing - Bowie MD

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

G05D 2300

165 32

An automatic thermal switch to control heat flow includes a first thermally conductive plate 2, a second thermally conductive plate 25 and a thermally conductive switch saddle 1 pivotally mounted to the first plate 2. A flexible heat carrier 27 is connected between the switch saddle 1 and the second plate 25. A phase-change power unit 9, including a piston 13 coupled to the switch saddle 1, is in thermal contact with the first thermally conductive plate 2. A biasing element 21 biases the switch saddle 1 in a predetermined position with respect to the first plate 2. When the phase-change power unit 9 is actuated by an increase in heat transmitted through the first plate 2, the piston 13 extends and causes the switch saddle 1 to pivot thereby varying the thermal conduction between the first and second plates 2 and 25 through the switch saddle 1 and flexible heat carrier 27. The biasing element, switch saddle and piston can be arranged to provide either a normally closed or normally opened thermally conductive path between the first and second plates.