Title:
【発明の名称】内燃機関用のスパークプラグ
Document Type and Number:
Japanese Patent JP3121309
Kind Code:
B2
Abstract:
A spark plug for an internal combustion engine comprises a noble metallic firing tip (3) laser welded on the opposing surface of either a central electrode (28) or a grounded electrode (29). A fused junction layer (4), formed between the noble metallic firing tip (3) and the base electrode member (2), contains 40 &tilde& 70 wt% noble metallic firing tip component. The noble metallic firing tip (3) has a non-fused portion axially extending by a length "L", where 0.2 mm ≤L≤ 0.7 mm. The fused junction layer (4) axially extends by a length "M", where 0.2 mm ≤M≤ 0.7 mm. And, the relationship B≥ 1.3A is established when "A" represents the diameter of the noble metallic firing tip (3) and "B" represents the diameter of a contact area at the boundary between the fused junction layer and the base electrode member, where 0.3 mm ≤A≤ 0.6 mm.
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Inventors:
Hironori Nagamura
Application Number:
JP5145798A
Publication Date:
December 25, 2000
Filing Date:
February 16, 1998
Export Citation:
Assignee:
株式会社デンソー
International Classes:
H01T13/20; H01T13/39; H01T21/02; (IPC1-7): H01T13/20; H01T13/39
Domestic Patent References:
| JP5159858A | ||||
| JP636856A |
Attorney, Agent or Firm:
Hirohiko Usui