| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a spark plug for an internal combustion engine capable of preventing the degradation of exfoliation resistance or the like caused by residual stress due to bending of a grounding electrode, and to provide a method of manufacturing the spark plug. Ž<P>SOLUTION: When a thickness of a thick part 271 of the grounding electrode 27 is to be A(mm), a distance between a base end of an inner peripheral surface and a chip surface 27s of the grounding electrode 27 in a horizontal direction is to be B(mm), a relation: B/A≤2.5 is satisfied. A precious metal chip 32 is protruded from the chip surface 27s of the grounding electrode 27 to form a gap with a chip of a center electrode 5. The grounding electrode 27 includes the thick part 271 fitted at a base end side, a thin part 272 fitted at a chip side and a step part 273 fitted at an inner peripheral surface side between the thick part 271 and the thin part 272. The precious metal chip 32 is welded on a flat surface 27f which is to be an inner peripheral surface of the thin part 272 so that a part of itself is embedded. A joining site of the precious metal chip 32 can be placed at a site with comparatively small residual stress due to bending. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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