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1. (WO2017170276) SPARK PLUG FOR INTERNAL COMBUSTION ENGINE

Pub. No.:    WO/2017/170276    International Application No.:    PCT/JP2017/012163
Publication Date: Fri Oct 06 01:59:59 CEST 2017 International Filing Date: Sat Mar 25 00:59:59 CET 2017
IPC: H01T 13/32
Applicants: DENSO CORPORATION
株式会社デンソー
Inventors: OHNO Ryuichi
大野 龍一
AKIYOSHI Ryohei
秋吉 亮平
Title: SPARK PLUG FOR INTERNAL COMBUSTION ENGINE
Abstract:
A spark plug (1) for an internal combustion engine comprises a cylindrical housing (2), a cylindrical insulator (3), a center electrode (4), and a ground electrode (5). The ground electrode (5) is provided with an erect section (51) and an inclined section (52). The erect section (51) is an erect area on the proximal end side of a proximal end section (21) of the housing (2). The inclined section (52) is an area that curves from the proximal end of the erect section (51) toward the center electrode (4) and extends at an incline toward the proximal end side. The inclined section (52) comprises a ground end surface (521), a facing surface (522), and a corner section curved surface (523). The corner section curved surface (523) is a surface that smoothly connects the ground end surface (521) and the facing surface (522). The corner section curved surface (523) has a curved shape. The radius of curvature R of the corner section curved surface (523) satisfies the expression 0.3 mm ≤ R ≤ 0.7 mm. The angle of inclination θ of the inclined section (52) with respect to a plug axis direction (Z) satisfies the expression 30° ≤ θ ≤ 60°.