Electric lamp and discharge devices – Spark plugs – Particular electrode structure or spacing
Reexamination Certificate
2005-03-08
2005-03-08
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Spark plugs
Particular electrode structure or spacing
Reexamination Certificate
active
06864622
ABSTRACT:
The object of the present invention is to provide a spark plug having a discharge portion formed of a noble-metal chip increased in the Ir content while reducing the content of expensive Rh, which can be restrained from generation of unusual wear in the form of eroding the circumferential side surface of the noble-metal chip and exhibits excellent wear resistance.In the present invention, the discharge portion (31) in the center electrode (3) side is formed of a noble-metal chip (31′) comprising an Ir-based alloy and the noble-metal chip (31′) contains 90% by weight or more of Ir as the main component and further contains 0.5% by weight or more of Rh and from 0.5 to 8% by weight of Ni, whereby the noble-metal chip (31′) [discharge portion (31)] can be ensured with good wear resistance, the generation of unusual wear which readily occurs on decreasing the Rh content can be prevented by the addition of Ni and in turn, a spark plug having high performance can be fabricated at a low cost.
REFERENCES:
patent: 9-7733 (1997-01-01), None
patent: 9-219274 (1997-08-01), None
patent: 10-321342 (1998-12-01), None
patent: 11-97151 (1999-04-01), None
patent: 11-97152 (1999-04-01), None
patent: 2001-185323 (2001-07-01), None
Ito Satoko
Matsutani Wataru
Segawa Masayuki
Yoshimoto Osamu
Morgan & Lewis & Bockius, LLP
NGK Spark Plug Co. Ltd.
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