| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug which can maintain an airtightness and can control deterioration of an opposability of a central electrode and a grounding electrode. SOLUTION: In the spark plug, a ring-shaped plate packing 27 is provided between a main metal piece 3 which is fixed by caulking and an insulator 2. The plate packing 27 has a hardness three times or more of the main metal piece 3 and is hardly damaged to deform its cross-section by the caulking, and its part is sunk into a sitting face 25a of a stepped part 25 of the main metal piece 3. As a result, the plate packing 27 is stuck airtight to the insulator 2 and the main metal piece 3 to maintain an airtightness inside a combustion chamber. COPYRIGHT: (C)2008,JPO&INPIT
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