SPARK PLUG - NGK SPARK PLUG CO

Title:

SPARK PLUG

Document Type and Number:

WIPO Patent Application WO/2015/063987

Kind Code:

A1

Abstract:

Provided is a spark plug that can suppress breaking of an insulator. The spark plug comprises the following: an insulator having a through hole extending in the axial direction; a rod-shaped central electrode provided inserted into the through hole and extending in the axial direction; a main body fitting disposed at the outer circumference of the insulator; and a ground electrode that is electrically conductive with the main body fitting and that forms a gap with the central electrode. The front end portion of the insulator has a front end surface, an outer circumferential surface that extends from the front end surface towards a back end in the axial direction, and a curved surface section that is formed between the front end surface and the outer circumferential surface. In a cross section that includes an axial line, the front end of the inner circumferential surface of the main body fitting faces in a direction perpendicular to the curved surface section and the axial line, and the radius of curvature of the curved surface section is 0.2mm-0.8mm.

Inventors:

MITSUDA SHINYA (JP)
YAMADA YUICHI (JP)

Application Number:

PCT/JP2014/004262

Publication Date:

May 07, 2015

Filing Date:

August 20, 2014

Export Citation:

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Assignee:

NGK SPARK PLUG CO (JP)

International Classes:

H01T13/20

Foreign References:

JP2002260816A	2002-09-13
JP2007080833A	2007-03-29
JP2001307857A	2001-11-02
JPH08298177A	1996-11-12
JPH0927379A	1997-01-28
JPH09266056A	1997-10-07
JPH1041047A	1998-02-13

Other References: