Title:
SPARK PLUG
Document Type and Number:
WIPO Patent Application WO/2018/037824
Kind Code:
A1
Abstract:
The objective of the invention is to suppress radio noise. This spark plug comprises: a cylindrical insulator having a shaft hole extending in the axial direction; a cylindrical metal shell; a metal terminal having a shank portion disposed inside the rear end of the shaft hole and a terminal portion exposed from the shaft hole; a central electrode at least partially disposed inside the leading end of the shaft hole; and a connection part electrically connecting the central electrode to the metal terminal inside the shaft hole. The rear portion of the shank portion rearward of the rear end of the metal shell contains a plurality of recessed portions that are recessed inward in the radial direction. In a cross section including the axis, the depth of each of the recessed portions is 50 μm or deeper, the angle formed by the two slanted surfaces facing each other across the bottom in each of the recessed portions is 150 degrees or narrower, and the axial length of the portion where the plurality of recessed portions are formed is 10 mm or longer. Disposed in at least one of the recessed portions is a layer comprising a ferrite containing at least one among Ni, Zn, Cu, Ba, Ca, Mg, Mn and Y.
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Inventors:
KUROSAWA KAZUHIRO (JP)
TAKAOKA KATSUYA (JP)
TANAKA KUNIHARU (JP)
KURONO HIROKAZU (JP)
UEGAKI HIRONORI (JP)
TAKAOKA KATSUYA (JP)
TANAKA KUNIHARU (JP)
KURONO HIROKAZU (JP)
UEGAKI HIRONORI (JP)
Application Number:
PCT/JP2017/027251
Publication Date:
March 01, 2018
Filing Date:
July 27, 2017
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
H01T13/05; F02P13/00
Foreign References:
| JP2003142224A | 2003-05-16 | |||
| JP2002184552A | 2002-06-28 | |||
| JPS5311246A | 1978-02-01 |
Attorney, Agent or Firm:
AOKI Noboru et al. (JP)
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