Patent ID: 7049734
Filing Date: 2006-05-23
Classification: H01T

Abstract:
1. A spark plug for an internal combustion engine comprising: a ground electrode; a center electrode defining a spark gap between itself and said ground electrode; an insulation porcelain having said center electrode retained therein; a cylindrical metal housing within which said insulation porcelain is disposed, said metal housing defining an annular chamber between an inner wall of said metal housing and an outer wall of said insulation porcelain; a polygonal portion formed on an outer wall of said metal housing around the annular chamber; a powder layer filled within the annular chamber to establish a hermetic seal between said metal housing and said insulation porcelain; and an annular extension formed on said metal housing which extends from an end of said polygonal portion to have an open end opposite an end thereof continuing from said polygonal portion, the open end being crimped inward of said metal housing to retain the powder layer within the annular chamber firmly, the open end having a thickness of 1.0 mm to 1.4 mm.