SPARK PLUG, AND PRODUCTION METHOD THEREFOR.

Title:

SPARK PLUG, AND PRODUCTION METHOD THEREFOR.

Document Type and Number:

WIPO Patent Application WO/2014/013722

Kind Code:

A1

Abstract:

The purpose of the present invention is to ensure excellent airtightness, and to more reliably inhibit breakage or the like with respect to an insulation body. A spark plug (1) is provided with: an electrical insulator (2) having a reduced diameter portion (14); and a main metal fitting (3) which has a protruded portion (21) protruding inwardly in the radial direction, and which is provided to the outer periphery of the electrical insulator (2). The protruded portion (21) has a reduced diameter portion (21A) which engages with an engagement portion (14) via an annular sheet packing (22). In a cross section including an axis (CL1), if the acute angle at a corner between a straight line orthogonal to the axis (CL1) and a contour line of the engagement portion (14) is θp(˚), and the acute angle at a corner between a straight line orthogonal to the axis (CL1) and a contour line of the reduced diameter portion (21A) is θs(˚), then θs > θp is satisfied. Furthermore, in said cross section, if the Vickers hardness of the sheet packing (22) at a centre point (CP1) of a first line segment (SL1) is Hvo (Hv), and the Vickers hardness of the sheet packing (22) at a centre point (CP2) of a second line segment (SL2) is Hvi (Hv), then Hvo > Hvi is satisfied.

Inventors:

OZEKI KEIJI (JP)
KOBAYASHI TSUTOMU (JP)
KATO TOMOAKI (JP)
MUKOYAMA NAOYUKI (JP)

Application Number:

PCT/JP2013/004341

Publication Date:

January 23, 2014

Filing Date:

July 16, 2013

Export Citation:

Click for automatic bibliography generation Help

Assignee:

NGK SPARK PLUG CO (JP)

International Classes:

H01T13/36

Domestic Patent References:

WO2010035717A1

2010-04-01

Foreign References:

JP2006092956A	2006-04-06
JPH10289777A	1998-10-27
JP2006236906A	2006-09-07

Other References: