| 摘要 |
PROBLEM TO BE SOLVED: To avoid inhibition of growth of flame at smoking of a spark plug for an internal-combustion engine. SOLUTION: The spark plug (1) is provided with a center electrode (12) protruding in one direction at the tip, a grounding electrode (13) opposed to the center electrode with an interval at a tip side, and an insulator (14), with a jutted part (14a) at least partially covering an outer periphery face at a root side of the center electrode and protruding, in a direction along that one direction at a site separated with an interval from the center electrode. As creeping discharge takes place at smoking between the center electrode and the grounding electrode via the jutted part, it can prevent the flame generated from being robbed of its heat by surrounding members, inhibited from growing, or going out. COPYRIGHT: (C)2009,JPO&INPIT
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