Patent ID: 6932352

Claim:
A gasket embedding an ion sensor used for sealing a cylinder head to a cylinder block of an engine which is situated under pressure between the cylinder head and the cylinder block of the engine, said gasket comprising: a metal sheet provided with an opening corresponding to a cylinder bore of the engine, a lug projecting outside from the periphery of said metal sheet, and a bead structure annularly formed around said opening; and an insulation seal layer for coating at least a part of the upper surface and the lower surface of said metal sheet around said bead structure; wherein: an ionic current detection electrode is provided at said opening of said metal sheet, said ionic current detection electrode projecting into a combustion chamber of the engine from the edge of said opening in a manner that it comes out from said insulation seal layer; said lug functionates as an ionic current introduction electrode the opening edge of said metal sheet projects into said cylinder bore of said engine so as to constitute an ionic current detection electrode in a manner that said opening edge is barely exposed from said insulation seal layer; and said lug constitutes an ionic current introduction electrode.