Title:
SPARK PLUG
Document Type and Number:
WIPO Patent Application WO/2011/118087
Kind Code:
A1
Abstract:
The disclosed sparkplug (1) is provided with a central electrode (5) extending in the direction of an axis line (CL1), an insulator (2) and a main metal fitting (3). The main metal fitting (3) has an annular protrusion (21); the insulator (2) is provided with a step portion (14) which engages with an annular protrusion (13), and a long leg portion (13) extending from the end of the step portion (14). Defining that in the tip position of the main metal fitting (3), the inner diameter of the main metal fitting (3) is A (mm) and the outer diameter of the insulator (2) is B (mm), that 4mm from the tip of the main metal fitting (3) along the axis line (CL1) towards the rear, the inner diameter of the main metal fitting (3) is C (mm) and the outer diameter of the insulator is D (mm), and that more than 4mm along the axis line (CL1) from the end of the main metal fitting (3) on the rear side, the outer diameter of the long leg portion (13) is Y, the following expressions are satisfied: 0.472 ≦ B / A ≦ 0.570, 0.472 ≦ D / C ≦ 0.660, B < Y, and A ≦ 8.7. By this means, the sparkplug achieves excellent resistance to pre-ignition.
Inventors:
KISHIMOTO KAORI (JP)
KAMEDA HIROYUKI (JP)
KAMEDA HIROYUKI (JP)
Application Number:
PCT/JP2010/071433
Publication Date:
September 29, 2011
Filing Date:
December 01, 2010
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
KISHIMOTO KAORI (JP)
KAMEDA HIROYUKI (JP)
KISHIMOTO KAORI (JP)
KAMEDA HIROYUKI (JP)
International Classes:
H01T13/20; F02P13/00; H01T13/16
Foreign References:
| JP2000243535A | 2000-09-08 | |||
| JP2002260817A | 2002-09-13 | |||
| JP2001155839A | 2001-06-08 |
Attorney, Agent or Firm:
KAWAGUCHI MITSUO (JP)
Mitsuo Kawaguchi (JP)
Mitsuo Kawaguchi (JP)
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Claims: