| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that, in generating plasma by radiating microwaves from a center electrode of a spark plug as the plasma and spark ignition are made to react to ignite air-fuel mixture, an action of the plasma on spark discharge is small when a direction of high-frequency electric field due to microwaves is the same as a center-axis direction of the center electrode, that is, a discharge direction of the spark discharge, so that a desired effect is not expected. SOLUTION: The spark plug, provided with a center electrode fitted inside a housing in insulation and a grounding electrode fitted at a lower end of the housing away from the center electrode, is for a spark ignition type internal combustion engine igniting air-fuel mixture with reaction of spark discharge generated between the center electrode and the grounding electrode and plasma generated by electromagnetic waves in a combustion room. The grounding electrode is arranged so as its tip to be positioned away from a center axis line of the center electrode, and that, includes a specific surface generating an electric field direction in a direction crossing that of spark discharge generated between the center electrode and the grounding electrode. COPYRIGHT: (C)2010,JPO&INPIT
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