| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug for suppressing noises emitted outside. SOLUTION: A spark plug 1 includes a cylindrical insulating insulator 2 to retain the center electrode 5, and a cylindrical main metal fitting 3 to retain the insulating insulator 2, and forms a spark discharge gap 33 by opposing a ground electrode 27 welded to the tip part of the main metal fitting 3 and the tip part of the center electrode 5. The insulating insulator 2 is integrally fixed to the main metal fitting 3 by caulking the rear end part peripheral edge of the main metal fitting 3 in a state that the insulator is inserted from the rear end side of the main metal fitting 3, and that the step part 14 toward the tip is locked to the step part 21 toward the rear-end. Between the step part 21 toward the rear-end of the main metal fitting 3 and a large diameter part 11 of the insulating insulator 2 in the axial line C1 direction, a space part 36 is formed between the inner peripheral face 3a of the main metal fitting 3 and the outer peripheral face 12a of the tip side trunk part 12 of the insulating insulator 2. A capacitor part 43 in which a dielectric and a conductor are alternately laminated is installed at the space part 36. COPYRIGHT: (C)2009,JPO&INPIT
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