Title:
SPARK PLUG
Document Type and Number:
WIPO Patent Application WO/2021/215051
Kind Code:
A1
Abstract:
The purpose of the present invention is to inhibit a seal material from entering a gap between a flange part and a step part during manufacture of a spark plug, and at the same time, inhibit the occurrence of cracking in an insulator during use of the spark plug. A spark plug is provided with a center electrode having a flange part, an insulator that has a through hole formed therethrough along the axial direction and that holds the center electrode, and a seal material that is packed in the through hole and that fixes the flange part and the insulator to each other, wherein: the insulator has a step part that supports the flange part and in which the through hole is formed so as to have a diameter that progressively decreases towards the front end side, and a small-diameter part that is continuous from the front end side of the step part and in which the through hole is formed so as to have a diameter smaller than that in the step part; the angle θ1 between the step part and a plane perpendicular to the axis and the angle θ2 between a facing surface of the flange part facing the step part and a plane perpendicular to the axis satisfy θ1 – θ2 ≥ 6°; and in a cross-section including the axis, the maximum value D1 of the diameter of the flange part and the diameter D2 of the through hole at the end section of the small-diameter part on the rear end side with respect to the axial direction satisfy 0.15 mm ≤ (D1-D2)/2.
Inventors:
NAKANO SEIJI (JP)
FUJIMURA KENGO (JP)
TAKAENOKI SHOTA (JP)
FUJIMURA KENGO (JP)
TAKAENOKI SHOTA (JP)
Application Number:
PCT/JP2020/047998
Publication Date:
October 28, 2021
Filing Date:
December 22, 2020
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
H01T13/20; H01T13/34
Domestic Patent References:
| WO2012105255A1 | 2012-08-09 | |||
| WO2017169929A1 | 2017-10-05 | |||
| WO2010073609A1 | 2010-07-01 |
Attorney, Agent or Firm:
NOMURA Kazuhiro (JP)
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