Title:
SPARK PLUG
Document Type and Number:
WIPO Patent Application WO/2014/013723
Kind Code:
A1
Abstract:
The objective of the present invention is to achieve both the airtightness and voltage resistance of a spark plug. The spark plug comprises: an insulating body formed as a tube-like body having a shaft hole, the insulating body including a reduced-diameter external surface as an outer peripheral surface, the outer diameter of which decreases from the rear end toward the front end; a body metal formed as a tube-like body having a through-hole into which the insulating body is inserted, the body metal including a screw section having a thread for attachment on the outer peripheral surface and a reduced-diameter inner surface as an inner peripheral surface, the inner diameter of which decreases from the rear end toward the front end; and an annular packing. The reduced-diameter external surface of the insulating body and the reduced-diameter inner surface of the body metal are sealed with the packing interposed therebetween. The nominal diameter of the screw section is 10 mm or less, and in at least one cross-section including the axial line, when (the difference between the effective diameter and the inner diameter at the rear end of the diameter-reduced inner surface of the screw section)/2 is defined as length A (mm) and (the difference between the inner diameter at the rear end of the reduced-diameter inner surface and the inner diameter at the front end of the reduced-diameter inner surface)/2 is defined as length B (mm), (A/B) ≥ 3.1, B ≥ 0.25, and (A + B) ≤ 2.0 are satisfied.
Inventors:
NISHIDA MASAHIRO (JP)
KATO TOMOAKI (JP)
OZEKI KEIJI (JP)
MUKOYAMA NAOYUKI (JP)
KOBAYASHI TSUTOMU (JP)
KATO TOMOAKI (JP)
OZEKI KEIJI (JP)
MUKOYAMA NAOYUKI (JP)
KOBAYASHI TSUTOMU (JP)
Application Number:
PCT/JP2013/004344
Publication Date:
January 23, 2014
Filing Date:
July 16, 2013
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
H01T13/36
Domestic Patent References:
| WO2011125306A1 | 2011-10-13 |
Foreign References:
| JP2009176525A | 2009-08-06 | |||
| JP3502936B2 | 2004-03-02 | |||
| JP4548818B2 | 2010-09-22 | |||
| JP4268771B2 | 2009-05-27 | |||
| JP4267855B2 | 2009-05-27 | |||
| JP2006066385A | 2006-03-09 | |||
| JP2009176525A | 2009-08-06 |
Other References:
See also references of EP 2876752A4
Attorney, Agent or Firm:
AOKI, Noboru et al. (JP)
Aoki 昇 (JP)
Aoki 昇 (JP)
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