| 摘要 |
PROBLEM TO BE SOLVED: To provide a sparking plug for an internal combustion engine which reduces a voltage requirement, which is excellent in durability and low is cost. SOLUTION: A sparking plug 1 for an internal combustion engine comprises a central electrode 2, an insulator 3 which holds the central electrode 2 inside, a housing 4 which holds the insulator 3 inside, and a main grounding electrode 5 which is secured to the tip of the housing 4 and has a spark discharge gap 11 formed between the central electrode 2 and itself. A pocket 13 opened toward the tip side is formed between the housing 4 and the insulator 3. An inward projection 41 which protrudes inward is formed on the inside surface of the housing 4 that faces the pocket 13. The tip of the housing 4 is provided with an auxiliary grounding electrode 6 forming an auxiliary spark discharge gap 12 between the tip of the insulator 3 and itself. COPYRIGHT: (C)2009,JPO&INPIT
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