Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsKeiji Ozeki, Tsutomu Kobayashi
Life of this patent
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Abstract
A spark plug includes a tubular metal shell that includes a metal-shell step portion extending in an inner circumferential direction, an insulator that is inserted in the metal shell, that includes a facing portion that faces the metal-shell step portion with an annular packing interposed therebetween, a center electrode that extends in the axial direction, that has a flange portion extending in an outer circumferential direction, and a seal body seals the insulator and the center electrode. In a section that contains the axial line and that is along the axial line, a distance L along the axial line from a rear end of the facing portion of the insulator to a rear end of a portion at which the flange portion is in contact with the insulator satisfies L≤1.1 (mm).
Claims5
A spark plug, comprising:
- a tubular metal shell that includes a metal-shell step portion extending in an inner circumferential direction and that has a tubular hole extending in an axial direction;
- an insulator that is inserted in the metal shell, that has an axial hole extending in the axial direction, and that includes a facing portion that faces the metal-shell step portion with an annular packing interposed therebetween;
- a center electrode that extends in the axial direction, that has a flange portion extending in an outer circumferential direction, and that is inserted in the axial hole such that at least a part of the center electrode protrudes further toward a front-end side of the spark plug than the insulator;
- and
- a seal body that is disposed in the axial hole and that seals the insulator and the center electrode,
- wherein in a section that contains an axial line of the spark plug and that is along the axial line, a distance L along the axial line from a rear end of the facing portion of the insulator to a rear end of a portion at which the flange portion is in contact with the insulator satisfies
- L≤1.1 (mm).
Dependencies are inferred from the claim text.