Electric lamp and discharge devices – Spark plugs – Particular electrode structure or spacing
Reexamination Certificate
2005-03-04
2009-06-23
Roy, Sikha (Department: 2879)
Electric lamp and discharge devices
Spark plugs
Particular electrode structure or spacing
C313S142000, C313S143000, C445S007000, C123S1690EL, C123S1690EB
Reexamination Certificate
active
07550906
ABSTRACT:
A noble-metal chip (30, 90) joined to at least either a center electrode or a ground electrode, the center and ground electrodes forming a spark discharge gap, and having a circumferential edge of its facing end surface (31, 91) removed so as to form an edge-removed portion (32, 92). The edge-removal length is 0.01 mm or more and a ratio of the edge-removal length to a radius of the noble-metal chip is less than 0.3. The noble-metal chip is made of iridium or an alloy that contains iridium man amount of 70% by weight or more, and crystal grains constituting the noble-metal chip (30, 90) extends in the axial direction. Also disclosed is a method for manufacturing the spark plug.
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Matsutani Wataru
Yoshimoto Osamu
Green Tracie Y
NGK Spark Plug Co. Ltd.
Roy Sikha
Sughrue & Mion, PLLC
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