Title:
【発明の名称】スパークプラグ
Document Type and Number:
Japanese Patent JP3327941
Kind Code:
B2
Abstract:
In a spark plug, a center electrode is made of a heat-conductor core cladded by a nickel-alloyed metal. A recess is provided on a front end surface of the nickel-alloyed metal. A columnar tip is made of a precious metal, and fitted in the recess in such a manner that a front end of the tip is protracted from the recess. An outer surface of the tip being welded to an inner surface of the recess. A relationship among A, B, C, D, E, F and G is as follows: 0.3 mm & A & 0.8 mm, 1.2A & B & 3A, 0.1 mm & (C-A)/2 & 0.5 mm, D & (C-A)/2, E / B/4, 0 mm & F & 0.5 mm and A/5 & G & A/2, where A: a diameter of the columnar tip, B: a length of the columnar tip, C: a diameter of a front end of the nickel-alloyed metal, D: a length of a front end of the nickel-alloyed metal, E: a length of the front end of the tip which is protacted from the recess, F: a distance between a rear end of the tip and a front end of the heat-conductor core, G: a distance of a welding penetrated from the outer surface of the tip to the inner surface of the recess.
Inventors:
Takafumi Ohshima
Kazuya Iwata
Tsutomu Okayama
Kazuya Iwata
Tsutomu Okayama
Application Number:
JP35092A
Publication Date:
September 24, 2002
Filing Date:
January 06, 1992
Export Citation:
Assignee:
Nippon Special Ceramics Co., Ltd.
International Classes:
H01T13/16; H01T13/20; H01T13/39; (IPC1-7): H01T13/20; H01T13/16; H01T13/39
Domestic Patent References:
| JP3176978A | ||||
| JP554953A | ||||
| JP61171080A |
Attorney, Agent or Firm:
Kenji Ishiguro