| 摘要 |
PROBLEM TO BE SOLVED: To improve peeling resistance of a precious metal chip by reducing thermal stress or the like generated between the precious metal chip and a ground electrode. SOLUTION: A sparkplug 1 is provided with an insulator 2, a center electrode 5, a main metal fitting 3 and a ground electrode 27, and a spark discharge gap 33 is formed between a precious metal chip 41 jointed to the ground electrode 27 and the center electrode 5. A concave hole part 43 is formed at the ground electrode 27, and more than 70% of its bottom surface of the precious metal chip 41 is jointed to the hole part 43 of the ground electrode 27 through a welding part 35 made of welding itself formed by laser beams or the like being irradiated from its side surface side and the ground electrode 27. A gap 45 of more than 0 mm and 1.0 mm or less is provided along a direction crossing a center axis CL2 of the precious metal chip 41 between at least a part of an inner wall surface 43S of the hole part 43 and the precious metal chip 41. COPYRIGHT: (C)2011,JPO&INPIT
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