| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug in which even if the thickness of a ring-shape ground electrode chip is made thin, temperature rise of the ring-shape ground electrode chip is suppressed and deterioration of its lifetime is suppressed and high reliability of melting jointing of the ground electrode body and the ring-shape ground electrode chip is secured. SOLUTION: The spark plug 1 includes a center electrode 3 and a ground electrode 5 which generates spark between the center electrode 3, and a ring-shape ground electrode chip 5d consisting of a noble metal is electrically fixed to a tip part 5b of the ground electrode body 5a of the ground electrode 5 in the direction opposed to the center electrode 3. A projection part 5c which projects to the center electrode 3 side is installed at the tip part 5b of the ground electrode body 5a and the ring-shape ground electrode chip 5d is arranged at the outer circumference of the projection part 5c, the projection part 5c and the ring-shape ground electrode chip 5d are electrically jointed by laser welding, and the tip face 5i of the ring-shape ground electrode chip 5d is positioned on the center electrode 3 side than the tip face 5j of the projection part 5c. COPYRIGHT: (C)2010,JPO&INPIT
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