Patent ID: 11862943

Abstract:
Spark plug has center electrode having leg portion extending in an axis direction, brim portion located at rear end side with respect to the leg portion and protruding outwards in a radial direction with respect to the leg portion and connecting portion connecting the leg portion and the brim portion; insulator having penetration hole and supporting the center electrode; and seal member filling the penetration hole and fixing the brim portion and the insulator. The center electrode satisfies “(D1-D2)/D1≤0.06”, where a maximum value of a radius of the brim portion is D1, and a minimum value of the radius of the brim portion is D2, also satisfies “L2/L1≤0.30”, where a size of the center electrode along the axis direction is L1, and a size along the axis direction from boundary between the connecting portion and the leg portion to a center of gravity of the center electrode is L2.