Glow plug with permanent displacement resistant probe tip joint

Abstract

A glow plug has a heater probe that can be axially misaligned relative to a central axis of an outer metal shell and of a center electrode and thereafter return automatically to its axially aligned configuration with the central axis. The outer shell has a through bore extending along the central axis. The center electrode is received in the though bore and extends along the central axis. The heater probe is attached in electrical communication with the center electrode in the through bore and extends along the central axis axially outwardly from a distal end of the shell. An annular flex joint provides the sole source of attachment of the outer shell to the heater probe via one end of the flex joint being attached to the outer shell adjacent the distal end and another end of the flex joint being attached to the heater probe.

1 . A glow plug, comprising:
 a metal outer shell having a through bore extending along a central axis between a proximal end and a distal end;   a center electrode received in said though bore and extending along said central axis;   a heater probe attached in electrical communication with said center electrode in said through bore and extending along said central axis axially outwardly from said distal end of said shell; and   an annular flex joint providing the sole source of attachment of said outer shell to said heater probe, said flex joint having one end attached to said outer shell adjacent said distal end and another end attached to the said heater probe, said flex joint having an annular leg extending radially between said outer shell and said heater probe.   
     
     
         2 . The glow plug of  claim 1  wherein said leg has at least one portion extending substantially parallel to said central axis in radially spaced relation with said shell and said heater probe. 
     
     
         3 . The glow plug of  claim 2  wherein said leg has at least a pair of portions extending substantially parallel to one another between said shell and said heater probe. 
     
     
         4 . The glow plug of  claim 3  wherein said leg is generally Z-shaped. 
     
     
         5 . The glow plug of  claim 4  wherein a first portion of said Z-shaped leg is fixed to said shell, a second portion of said Z-shaped leg is fixed to said heater probe, and a third portion extend between said first portion and said second portion with a radial clearance formed between said first, second and third portions. 
     
     
         6 . The glow plug of  claim 5  wherein a portion of said first portion is detached in radially spaced relation from said shell. 
     
     
         7 . The glow plug of  claim 6  wherein a portion of said second portion is detached in radially spaced relation from said heater probe. 
     
     
         8 . The glow plug of  claim 5  wherein said first portion is entirely attached to said shell. 
     
     
         9 . The glow plug of  claim 8  wherein said second portion is entirely to said heater probe. 
     
     
         10 . The glow plug of  claim 5  wherein said first, second and third portions are spaced radially from one another. 
     
     
         11 . The glow plug of  claim 1  wherein said distal end of said shell has a chamfered nose extending toward an outer surface of said shell and said one end of said flex joint being everted over said chamfered nose in bonded relation thereto. 
     
     
         12 . The glow plug of  claim 1  wherein said annular leg transitions to a cylindrical portion extending axially outwardly from said distal end of said shell. 
     
     
         13 . The glow plug of  claim 1  wherein said cylindrical portion is entirely fixed to said heater probe. 
     
     
         14 . The glow plug of  claim 1  wherein said cylindrical portion has a portion spaced radially from said heater probe and a portion fixed to said heater probe.