Electrically heatable glow plug and method for manufacturing an electrically heatable glow plug

Abstract

An electrically heatable glow plug and a method of manufacturing an electrically heatable glow plug allow better decoupling between a heating coil and a combustion-chamber-side end of a glow tube. The electrically heatable glow plug for internal combustion engines includes a metallic glow tube, sealed on the combustion-chamber side, into which an electrically conductive heating coil is introduced, the heating coil being connected in an electrically conductive manner to the glow tube in the region of the sealed combustion-chamber-side end of the glow tube. A sealing arrangement is provided which seals the glow tube on the combustion-chamber side and supports the heating coil and only protrudes into the heating coil if the heating coil is connected to the sealing arrangement via an inner side of the heating coil, for which purpose the sealing arrangement is in contact with the inner side of the heating coil essentially over the entire length protruding into the heating coil.

1 . An electrically heatable glow plug for an internal combustion engine, comprising: 
 a metallic glow tube, which is closed on the combustion-chamber side, and into which an electrically conductive heating coil is introduced, the heating coil being connected in an electrically conductive manner to the metallic glow tube in a region of a closed, combustion-chamber-side end of the metallic glow tube; and    a sealing arrangement to seal the glow tube on the combustion-chamber side and to support the heating coil, and being arranged to only protrude into the heating coil if the heating coil is connected to the sealing arrangement via an inner side of the heating coil, for which purpose the sealing arrangement is, in this case, essentially in contact with the inner side of the heating coil over an entire length protruding into the heating coil.    
   
   
       2 . The glow plug of  claim 1 , wherein the heating coil is connected to the sealing arrangement by one of at least one welded point, a continuous welded seam, a screw joint, and a crimping.  
   
   
       3 . The glow plug of  claim 1 , wherein the sealing arrangement is at least one of metallic and of a same material as the glow tube.  
   
   
       4 . The glow plug of  claim 1 , wherein the sealing arrangement is welded to the glow tube.  
   
   
       5 . The glow plug of  claim 1 , wherein the sealing arrangement includes a cap to cover the glow tube on the combustion-chamber side and includes a glow-tube-side elevation to receive the heating coil.  
   
   
       6 . The glow plug of  claim 1 , wherein the sealing arrangement includes a combustion-chamber side pin that protrudes into a combustion-chamber side opening of the glow tube and seals it, and the sealing arrangement includes a glow-tube-side base to receive the heating coil.  
   
   
       7 . The glow plug of  claim 6 , wherein the heating coil rests on the base.  
   
   
       8 . The glow plug of  claim 6 , wherein the base includes a first projection on the glow-tube side, which protrudes into the heating coil and is in contact with the inner side of the heating coil on the combustion-chamber-side end.  
   
   
       9 . The glow plug of  claim 6 , wherein the base itself protrudes into the heating coil and is in contact with the inner side of the heating coil on the combustion-chamber-side end.  
   
   
       10 . The glow plug of  claim 6 , wherein the base includes a second projection on the glow tube side, which encloses the outside of the heating coil on its combustion-chamber-side end.  
   
   
       11 . A method for manufacturing an electrically heatable glow plug for an internal combustion engine, the method comprising: 
 introducing an electrically conductive heating coil into a glow tube, wherein, before introduction of the heating coil into the glow tube, which is initially open on its combustion-chamber-side end, the heating coil is first connected on its combustion-chamber-side end to a sealing arrangement, the sealing arrangement only protruding into the heating coil if the heating coil is attached to the sealing arrangement via an inner side of the heating coil, for which purpose the sealing arrangement is essentially in contact with the inner side of the heating coil over the entire length protruding into the heating coil; and    after introduction of the heating coil, together with the sealing arrangement positioned on the combustion-chamber side, into the glow tube, sealing the glow tube on its combustion-chamber-side end by the sealing arrangement.    
   
   
       12 . The glow plug of  claim 1 , wherein the glow plug is a sheathed-element glow plug.