Spark plug for internal combustion engine and manufacturing method thereof

摘要

A spark plug comprising: a center electrode extending along an axis; an insulator provided about the outer peripheral surface of the center electrode; a metal shell provided about the outer peripheral surface of the insulator; a noble metal tip provided at the leading end portion of the center electrode; one end of the ground electrode fixed at the leading end of the metal shell, and the other end of the ground electrode forming a gap with the leading end of the noble metal tip; a stopper preventing the noble metal tip from moving relative to the central electrode; a molten portion formed by irradiating laser or electron beam; and a closed space formed between the basal portion of the noble metal tip and the center electrode. The molten portion welds the center electrode and a part of the basal portion of the noble metal tip.