| 摘要 |
Provided is a spark plug capable of achieving both of air tightness and high gasket detachment resistance. The spark plug (1) includes a metal shell (3) and a solid annular gasket (18). The metal shell (3) has a mounting male thread portion (15) and a radially outwardly protruding seat portion (16). The gasket (18) is disposed between the male thread portion (15) and the seat portion (16). The gasket (18) has a recessed portion (41) formed with a depth in the direction of an axis (CL1) such that the recessed portion (41) has an opening at a surface of the gasket (18) located opposite to the seat portion (16). The gasket (18) includes an inner peripheral front end surface region (351) formed such that a distance from a reference plane (VS), which passes through a rear end of the recessed portion (41) and extends perpendicular to a center line (CL2) of the gasket (18), to the inner peripheral front end surface region (351) decreases toward an inner periphery of the gasket (18) and an outer peripheral front end surface region (352) formed radially outside the inner peripheral front end surface region (351). The opening of the recessed portion (14) is located radially inside an innermost periphery of the outer peripheral front end surface region (352). |
