Accession Number : ADD018099

Title :   Package-Interface Thermal Switch.

Descriptive Note : Patent, Filed 24 May 95, patented 16 Jul 96,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Hyman, Nelson L

Report Date : 16 Jul 1996

Pagination or Media Count : 6

Abstract : The package-interface thermal switch (PITS) is an active temperature control device for modulating the flow of thermal energy from satellite equipment, such as electronic modules or batteries, to the satellite mounting deck which serves as a heat sink. PITS comprises a mounting bolt made of a shaped memory alloy (SMA) actuating bolt and a non-metallic rod with a helical spring surrounding it forming a mounting bolt for a satellite equipment package. At least four mounting bolts are used for installing the equipment package and are preloaded to a predetermined stress representing the desired thermal conductance between the heat sink and the package. The SMA actuating bolt is in thermal contact with the component or package and expands or contracts as the result of changing package temperature and the helical 'return' spring forces against the SMA actuating bolt portion of the PITS, increasing ('hot-on' condition) or decreasing ('cold-off' condition) the pressure of the package against the mounting deck. As the PITS changes its total length, the thermal conductance between the two objects is increased or decreased. Thus thermal conductance changes as a direct function of package temperature, resulting in active temperature control. The simple design of the PITS reduces the cost and weight of the thermal control subsystem in satellites and its high reliability eliminates the requirement for thermal design verification testing.

Descriptors :   *PATENTS, *THERMAL SWITCHES, TEST AND EVALUATION, THERMAL PROPERTIES, FUNCTIONS, TEMPERATURE, CONTROL SYSTEMS, VERIFICATION, SHAPE, HELICAL SPRINGS, ALLOYS, NONMETALS, COSTS, MEMORY DEVICES, THERMAL CONDUCTIVITY, ARTIFICIAL SATELLITES, PRESSURE, MODULES(ELECTRONICS), MOUNTS, TEMPERATURE CONTROL, RODS, ACTUATION, HEAT SINKS, THERMAL RADIATION, BOLTS, HIGH RELIABILITY

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE