| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug that is enhanced in durability.SOLUTION: A center electrode of a spark plug has a shaft portion, a chip portion joined to the tip portion of the shaft portion, and a joint portion for joining the shaft portion and the chip portion. A small-diameter portion is defined as a part having the smallest inner diameter out of a portion where the chip portion formed of an insulator is accommodated. Here, the distance between an inner edge as an edge at the tip side in the axial line direction of the inner peripheral surface of the small-diameter portion and the surface of the center electrode is set to 0.3 mm or more, or the subtraction of a first distance from a second distance is equal to zero mm or more. |
