GB1462473A - Static electric relay comprising a pyrotechnic composition - Google Patents

Abstract

1462473 Thermal switches FRANCE ARMED FORCES MINISTER OF 19 March 1974 [19 March 1973 25 Feb 1973] 12197/74 Addition to 1378328 Heading H1N An electric relay comprises spaced electrodes 3a, 3b insulated from each other and having confronting parallel faces with pyrotechnic material 4 between the faces and input means 10, 11 to initiate a pyrotechnic reaction of material 4 to produce between the faces a metallic conductive body to connect electrodes 3a, 3b physically and electrically. Input means 10, 11 is an electric filament connected to terminals 9a, 9b, and a second pyrotechnic material. The pyrotechnic material 4 may comprise a mixture of an oxide of a metal of the group tin, lead, copper and silver, and a reducing metalloid of the group boron and silicon. The mixture may contain methylsilicone oil. The mixture is insulating but upon reduction, the metal liberated fills and effects a weld between the electrodes 3a, 3b. Electrodes 3a, 3b may be coated with a layer of combustible insulating varnish or a layer of tin. In a second embodiment, Figs. 3, 4 (not shown) concentric cylindrical electrodes with a central core (21) are attached to heavy current threaded stud terminals and the input means (25, 26) fits into an orifice (23) in the side of the insulating casing. In a third embodiment, Figs. 5-7 (not shown) four pairs of concentric cylindrical electrodes (37a, 37b) are arranged in insulation with four pairs of plug-in wafer terminals (33a) at one axial end of the electrodes and four pairs of plug-in wafer terminals (32a) for the input means at the other axial end. In the three embodiments in Figs. 8-11, only Fig. 8 shown, in addition to the pyrotechnic material 112 between the cylindrical electrodes 109, 110, there is an air-gap 113 between the electrodes to increase the insulation and break-down voltage. Material 112 is retained by an enclosure 111 which may be of paper, or of tin which melts and helps bridge electrodes 109, 110. The input means is a filament 107 between terminals 105 igniting a second pyrotechnic material 116. The embodiment in Figs. 9, 10 (not shown) is similar to that in Figs. 5-7 except for the air gap and the central electrode being a solid rod 125. The embodiment in Fig. 11 (not shown) is similar to that in Figs. 3, 4 apart from air gaps between electrodes (147, 148) and between central core (150) and electrode (147). In the embodiments in Figs. 9-11, the pyrotechnic material is retained by paper or tin enclosing walls. Also in Figs. 8-11 there is a space (117 in Fig. 8) for the gases produced by the ignition of the input means.