| 摘要 |
PROBLEM TO BE SOLVED: To prevent growth of a flame kernel from being inhibited by a center electrode or a grounding electrode even when a firing part is narrowed for preventing sideward sparking in a spark plug having a plurality of firing parts. SOLUTION: This spark plug is provided with a plurality of center electrodes 12 and 13 and grounding electrodes 20 and 21; each center electrode is insulated and held by an insulator 11; the insulator is housed in a housing 10; and each grounding electrode is jointed to the housing. Center-side chips 18 and 19 thinner than center electrode body parts 121 and 131 are jointed to tip parts of the respective center electrodes 12 and 13; and ground-side chips 22 and 23 projecting toward the center-side chips 18 and 19 are jointed to the respective grounding electrodes 20 and 21. Thereby, distances from the firing parts G1 and G2 to the center electrodes 12 and 13 and the grounding electrodes 20 and 21 are increased to increase each gap for forming a flame kernel. Thereby, inhibition of the growth of the flame kernel by the center electrodes 12 and 13 and the grounding electrodes 20 and 21 is reduced. COPYRIGHT: (C)2005,JPO&NCIPI
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