Patent ID: 8003917

Claim:
A glow plug, comprising: a ceramic heating element arranged as a sheathed-element glow plug situated in a housing and surrounded by a supporting tube, the ceramic heating element being sealed in the supporting tube by a seal with respect to a combustion chamber, and the seal being arranged as a sealing element manufactured from an alloy having an Invar effect; wherein the alloy having the Invar effect is a face-centered cubic FeNi alloy having at least one of the following concentration ranges: (a) Ni from 35.0 to 44.0 wt %, Mn <1.0 wt %, Si <0.50 wt % and C <0.10 wt %, remainder Fe; (b) Ni from 31.0 to 33.0 wt %, Co from 4.0 to 6.0 wt %, Mn <0.50 wt % and Si <0.50 wt %, C <0.10 wt %, remainder Fe; (c) Ni from 28.0 to 30.0 wt %, Co from 17.0 to 18.0 wt %, Mn <0.50 wt %, Si <0.30 wt % and C <0.05 wt %, remainder Fe; and (d) Ni from 41.0 to 43.0 wt %, Co from 6.0 to 7.0 wt %, Mn <1.0 wt %, Si <0.50 Wt % and C <0.10 wt %, remainder Fe.