| 摘要 |
PROBLEM TO BE SOLVED: To assure an anti-contamination property and further restrain channeling or the like, about a spark plug carrying out semi-creepage discharge all the time. SOLUTION: The spark plug 100 is provided with a main body fitting 1, an insulation body 2, a center electrode 3, and grounding electrodes 4A, 4B. A tip end side 3a of the center electrode 3 is nearly on the same plane as a tip end side 2a of the insulation body 2, and tip end sides 41a, 41b of the grounding electrodes 4A, 4B are extended in parallel with an axis line direction. A creeping discharge path along the tip end side 2a of the insulation body 2 is included at a part of a sparkling discharge path between a tip of each grounding electrode 4A, 4B and the center electrode 3. Edge parts EA, EB between the tip end sides 41a, 41b and inner side faces 42a, 42b of the grounding electrodes 4A, 4B are further toward the tip edge side than a virtual flat face M1 containing the tip end side 2a of the insulation body 2, and also, they are placed further toward a tip end side than the tip end side 3a of the center electrode 3 and placed further outward than a tip-end outer periphery G1 of the insulation body 2. Anglesθof the edge parts EA, EB are obtuse angles. COPYRIGHT: (C)2008,JPO&INPIT
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