Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsKengo Fujimura, Kimihiro Nishizono, Hiroki OTA
Life of this patent
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Abstract
A spark plug enabling suppression of reduction in the strength of an insulator. In the spark plug, a rear end portion of an engagement portion formed on an outer peripheral surface of a tubular insulator extending along an axial line from a front side to a rear side, is engaged with a to-be-engaged portion of a tubular metal shell disposed on the outer peripheral surface of the insulator. The insulator is made from ceramic such as alumina. On at least a part of the outer peripheral surface of the insulator, a projected and recessed portion is formed on the front side relative to the engagement portion so as to helically extend in a circumferential direction of the insulator.
Claims2
A spark plug comprising:
- a tubular insulator having an outer peripheral surface on which an engagement portion is formed, the insulator extending along an axial line from a front side to a rear side;
- and
- a tubular metal shell disposed on the outer peripheral surface of the insulator, and including a to-be-engaged portion engaged with a rear end portion of the engagement portion, wherein,
- on at least a part of the outer peripheral surface of the insulator, a projected and recessed portion is formed on the front side relative to the engagement portion so as to helically extend in a circumferential direction of the insulator.
Dependencies are inferred from the claim text.