Miniature electro-pyrotechnic igniter, and ignition head for the same

Abstract

An electric non-pyrotechnic ignition head ( 100 ) suitable for use in an electro-pyrotechnic igniter ( 1 ), comprising: a housing ( 102 ) defining a front opening ( 106 ); —an electrically insulative, thermally conductive bridge filament support body ( 130 ) that is at least partly disposed in said front opening, and that defines a frontal heating surface ( 132 b ); and a bridge filament ( 120 ) including at least one cross-over portion ( 122 ) that extends over the frontal heating surface ( 132 b ) of the bridge filament support body ( 130 ).

1 . An electric non-pyrotechnic ignition head suitable for use in an electro-pyrotechnic igniter, comprising:
 a housing defining a front opening;   an electrically insulative, thermally conductive bridge filament support body that is at least partly disposed in said front opening, and that defines a frontal heating surface; and   a bridge filament including at least one cross-over portion that extends over the frontal heating surface of the bridge filament support body.   
     
     
         2 . The ignition head according to  claim 1 , further comprising a non-pyrotechnic, electrically insulative, thermally conductive shield film that is applied over the at least one cross-over portion. 
     
     
         3 . The ignition head according to  claim 2 , wherein the shield film has a heat transfer coefficient in the range of 240-24,000 W/m 2 K, and more preferably in the range of 1,250-4,800 W/m 2 K. 
     
     
         4 . The ignition head according to  claim 2 , wherein the shield film is as least partially made of Kapton®. 
     
     
         5 . The ignition head according to  claim 1 , wherein the frontal heating surface defines a plurality of pairs of cross-over terminals, and
 wherein the at least one cross-over portion includes a plurality of cross-over portions, each of said cross-overs portions being uniquely associated with a pair of cross-over terminals, such that a respective cross-over portion extends over the frontal heating surface only in between the cross-over terminals of the pair of cross-over terminals with which it is associated.   
     
     
         6 . The ignition head according to  claim 5 , wherein the cross-over terminals include at least one of: indentations defined by a circumferential edge bounding the frontal heating surface of the bridge filament support body, and through-holes in the bridge filament support body. 
     
     
         7 . The ignition head according to  claim 1 , wherein the bridge filament support body is a plate-like body. 
     
     
         8 . The ignition head according to  claim 7 , wherein the bridge filament support body is at least partially made of a ceramic material. 
     
     
         9 . The ignition head according to  claim 1 , wherein the bridge filament support body has an average thickness in the range of 0.2-2 mm, measured in a direction that is normal with respect to the frontal heating surface. 
     
     
         10 . The ignition head according to  claim 1 , wherein the bridge filament support body is circumferentially dimensioned such that it is fittingly receivable in the front opening of the housing. 
     
     
         11 . The ignition head according to  claim 1 , wherein the housing defines an interior space, wherein the support body extends along or in the front opening and covers the interior space. 
     
     
         12 . The ignition head according to  claim 11 , wherein an inner surface of the filament support body faces the interior space, the inner surface extending opposite ignition head sealing means. 
     
     
         13 . The ignition head according to  claim 11 , wherein lead wires extend through sealing means towards the interior space, wherein the lead wires are connected to proximal ends of the bridge filament, for example at connections located within the interior space. 
     
     
         14 . The ignition head according to  claim 1 , wherein the frontal heating surface has an area in the range of 4-1,000 mm 2 , preferably in the range of 4-160 mm 2 , and more preferably in the range of 9-36 mm 2 . 
     
     
         15 . The ignition head according to  claim 1 , wherein the housing, optionally except for the front opening thereof, is fluidtightly sealed, and
 wherein the bridge filament extends between a first end and a second end, which ends are disposed inside the housing and electrically conductively connected to respective low-electrical-resistance lead wires that extend from the housing via at least one fluidtightly sealed lead wire outlet.   
     
     
         16 . An electro-pyrotechnic igniter, comprising:
 a casing defining an interior reaction chamber and at least one exhaust orifice via which the reaction chamber is fluidly connected to an external environment of the electro-pyrotechnic igniter;   at least one electric non-pyrotechnic ignition head according to  claim 1 , whose housing is integrated with the casing, such that the bridge filament is at least partially disposed within the reaction chamber; and   a pyrotechnic charge that is disposed within the reaction chamber, such that a pyrotechnic composition of the pyrotechnic charge is in contact with the bridge filament of the at least one ignition head via an interposed non-pyrotechnic, electrically insulative, thermally conductive shield film.   
     
     
         17 . The electro-pyrotechnic igniter according to  claim 16 , further comprising:
 a non-reclosing pressure relief device, for instance a burst disc, that closes off the at least one exhaust orifice, and that is configured to open said at least one exhaust orifice once a predetermined pressure has developed within the reaction chamber.   
     
     
         18 . The electro-pyrotechnic igniter according to  claim 16 , wherein said at least one exhaust orifice comprises a plurality of exhaust orifices. 
     
     
         19 . The electro-pyrotechnic igniter according to  claim 16 , wherein said at least one ignition head comprises a plurality of ignition heads. 
     
     
         20 . An ignition system, including:
 a power supply; and   an electro-pyrotechnic igniter according to  claim 16 , whose at least one ignition head is operably connected to the power supply,   
       said system being configured such that an ignition energy to be supplied by the power supply in order to ignite the pyrotechnic charge is in the range of 10-200 Joules, and preferably in the range of 25-100 Joules. 
     
     
         21 . A spacecraft, for instance a satellite, including at least one of an ignition head according to  claim 1 .