| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug for an internal combustion engine with improved combustibility.SOLUTION: A spark plug includes: a cylindrical housing 2; a cylindrical insulator 3 held at the inner side of the housing 2; a center electrode 4 held at the inner side of the insulator 3; a ground electrode 5 which forms a spark discharge gap 11 with the center electrode 4; and a plug cover 6 which is fixed to a tip part of the housing 2 and forms a sub combustion chamber 12, in which the spark discharge gap 11 is disposed, with the housing 2. The plug cover 6 has a through hole 61 which connects the exterior of the plug cover 6 with the sub combustion chamber 12. The ground electrode 5 is formed protruding from an inner surface 62 of the plug cover 6 to the sub combustion chamber 12 side. |
