SPARK PLUG FOR INTERNAL COMBUSTION ENGINE AND METHOD FOR MANUFACTURING SAME

摘要

The spark plug has a configuration satisfying the relationships of B>=0.7A and 0.3 mm@A@0.6 mm, where B is an axial thickness along the central axis line Q of the weld portion formed between the base material electrode and the noble-metal chip, and A is an axial distance along the central axis line Q between the intersection points P3 and X. The intersection point P3 is a point at which a phantom axis line radially distant from the central axis line Q by D/2 (D being a diameter of the noble-metal chip) intersects with the boundary line between the weld portion and the noble-metal chip. The intersection point X is a point at which an extension of the contour line of the base material electrode in the vicinity of the weld portion intersects with a boundary line between the weld portion and the base material electrode.