Sheathed Element Glow Plug Having a Combustion Chamber Pressure Sensor

Abstract

A sheathed element glow plug includes an integrated combustion chamber pressure sensor for a self-igniting internal combustion engine for measuring combustion chamber pressures, in particular for combustion chamber signal-based engine control. The sheathed element glow plug has a heating element and a glow plug housing, as well as a glow plug axis. The glow plug housing has a receptacle area for receiving the heating element, a housing body, and at least one flexibility area situated between the housing body and the receptacle area. At least one force measuring element is installed in the glow plug housing.

1 - 11 . (canceled) 
   
   
       12 . A sheathed element glow plug for a self-igniting internal combustion engine, comprising:
 a heating device;   a glow plug housing; and   a glow plug axis;   wherein the glow plug housing includes a receptacle area configured to receive the heating device, a housing body and at least one flexibility area arranged between the housing body and the receptacle area, at least one force measuring device arranged in the glow plug housing.   
   
   
       13 . The sheathed element glow plug according to  claim 12 , further comprising at least one force transmission device configured to transmit a combustion chamber pressure to the at least one force measuring device. 
   
   
       14 . The sheathed element glow plug according to  claim 12 , wherein the at least one flexibility area includes at least one area in which the glow plug housing has a lower rigidity parallel to the glow plug axis than in an area of the housing body. 
   
   
       15 . The sheathed element glow plug according to  claim 12 , wherein the at least one flexibility area includes at least one of: (a) an undulation; (b) a bellows having at least one fold turned to one of (i) an inside and (ii) an outside of the glow plug housing; (c) an area having a small wall thickness of the glow plug housing; (d) an elastic device; and (e) an device having a low modulus of elasticity. 
   
   
       16 . The sheathed element glow plug according to  claim 12 , wherein the at least one force measuring device is accommodated in the housing body. 
   
   
       17 . The sheathed element glow plug according to  claim 12 , wherein the at least one force transmission device includes at least one of: (a) a pressure rod; (b) a substantially cylindrical pressure rod; (c) a pressure sleeve; and (d) a substantially cylindrical sleeve-shaped pressure sleeve. 
   
   
       18 . The sheathed element glow plug according to  claim 13 , wherein one end of the at least one force transmission device is supported by the at least one force measuring device and the other end is supported by at least one of: (a) the heating device; (b) the at least one flexibility area; and (c) an area of the glow plug housing arranged between the at least one flexibility area and the at least one heating device. 
   
   
       19 . The sheathed element glow plug according to  claim 13 , wherein one end of the at least one force transmission device is supported by the at least one force measuring device and the other end is supported by an area of the glow plug housing arranged between the at least one flexibility area and the at least one heating device, the sheathed element glow plug further comprising at least one supporting device configured to support the at least one force transmission device on the glow plug housing. 
   
   
       20 . The sheathed element glow plug according to  claim 12 , further comprising at least one external thread configured to connect the sheathed element glow plug to a cylinder head of the internal combustion engine, the at least one external thread being a component of the housing body. 
   
   
       21 . The sheathed element glow plug according to  claim 12 , wherein the at least one force measuring device is one of (a) annular- and (b) disk-shaped. 
   
   
       22 . The sheathed element glow plug according to  claim 13 , wherein the at least one force measuring device is arranged in the glow plug housing such that a tensile pre-stress is applied to at least part of the glow plug housing, and a compression pre-stress is applied to the at least one force transmission device. 
   
   
       23 . The sheathed element glow plug according to  claim 22 , wherein the at least one force measuring device is one of (a) screwed in and (b) caulked to the glow plug housing.