Title:
SPARK PLUG
Document Type and Number:
WIPO Patent Application WO/2018/003358
Kind Code:
A1
Abstract:
Provided is a spark plug for which contamination resistance can be ensured with a simple structure. An insulator having a step part formed on the outer circumferential surface thereof has a center electrode disposed in a shaft hole. A tubular main fitting having a step part and a shelf part formed on the inner circumferential surface thereof is disposed radially outward from the insulator. The tip part of the insulator is positioned further toward the tip side of the insulator than is the step part. On the tip part, the arithmetic average roughness in the circumferential direction of the outer circumferential surface is 0.5 µm or less. On at least a portion of the end surface and the outer circumferential surface of the tip part, a recess having a depth of 3-20 µm is provided extending from the tip side to the rear-end side.
Inventors:
ISASA JUMPEI (JP)
NAKANO SEIJI (JP)
KURONO HIROKAZU (JP)
TANAKA KUNIHARU (JP)
YOKOYAMA YUTAKA (JP)
YOSHIDA HARUKI (JP)
KONDO SHUN (JP)
NAKANO SEIJI (JP)
KURONO HIROKAZU (JP)
TANAKA KUNIHARU (JP)
YOKOYAMA YUTAKA (JP)
YOSHIDA HARUKI (JP)
KONDO SHUN (JP)
Application Number:
PCT/JP2017/019447
Publication Date:
January 04, 2018
Filing Date:
May 25, 2017
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
H01T13/20
Foreign References:
| JP2014107084A | 2014-06-09 | |||
| JP2014067658A | 2014-04-17 |
Other References:
See also references of EP 3477801A4
Attorney, Agent or Firm:
AOKI Noboru et al. (JP)
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