公开(公告)号：US20190326733A1

公开(公告)日：2019-10-24

申请号：US16472275

申请日：2017-09-05

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Kengo Fujimura ,  Kimihiro Nishizono ,  Hiroki OTA

IPC: H01T13/20 ,  H01T13/02

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.