Hughes Aircraft Company

Jerry J Herrin

Howard H Rogers

A relay (30) has one or both current carrying relay contacts (12, 14) made of a soft, deformable, readily fusible metal, preferably indium, lead, cadmium, bismuth, or tin. When the relay (30) closes, the contacts (12, 14) deform or fuse together, ensuring good electrical conductance and eliminating chatter and accidental opening. The relay (30) is particularly useful in a bypass circuit (54) for a spacecraft battery system (50).

One-time-close relay useful in spacecraft power systems

A cell bypass circuit is disclosed which includes a diode 32 connected electrically in parallel with a cell 20 of a battery 12. A thermal switch 34 is mounted in thermal contact with a diode 32. A relay 38 including a coil 36 and a contact 40 is provided. The coil 36 is connected to the thermal switch 34 so as to be activated by the activation thereof. The contact 40 of the relay 38 is connected in parallel with the cell 20 so that the activation of the diode 32 causes thermal energy to radiate therefrom activating the thermal switch 34. The activation of the thermal switch 34 causes the activation of the relay 38 which in turn places an electrical short across the defective cell 20 via the contacts 40 thereof.

Cell bypass circuit

The present invention generally provides a thermally-activated, shorting-diode switch whose composite diode structure possesses a non-operationally-alterable junction path, and whose diode shorting is effectuated by temperature-sensitive companion elements. The diode structure includes a semiconductor diode element to which associated first and second lead substructures are both unalterably connected. When activated by the increased temperatures experienced by the diode structure upon conduction, the shorting elements establish a direct, diode-bypass connection between the lead substructures. In a first more-specific embodiment, the shorting mechanism encompasses a solder preform which melts and flows over the diode structure when conduction-interval temperatures are generated. A second more-specific embodiment alternatively employs a temperature-responsive deformation mechanism which upon activation deflects a cantilevered segment of the first lead into diode-bridging contact with a companion segment of the second lead.

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Santa Ana, CA, United States of America

Jerry J Herrin