| 摘要 |
A spark plug (1) includes a metallic shell (3) extending along an axis (CL1) and a solid annular gasket (18). The metallic shell 3 has an externally threaded portion (15) and a seat portion (16), and the gasket (18) has an inside diameter smaller than the thread diameter of the externally threaded portion (15) and is provided between the externally threaded portion (15) and the seat portion (16). The forward end surface (18F) of the gasket (18) has an inclined portion (18A) which inclines rearward with respect to the direction of the axis (CL1) from the radially outer side toward the raidally inner side. The thickness of the gasket (18) along the axis (CL1) is 2.0 mm or less; the distance along the axis (CL1) between the outermost circumferential edge and the innermost circumferential edge of inclined portion (18A) is 0.02 mm to 0.12 mm; and the Vickers hardness of the gasket (18) is 60 Hv or more. Thus, when the spark plug is mounted to a combustion apparatus, the position of a forward end portion of the metallic shell (ground electrode) in relation to a combustion chamber can be accurately set. |
