Electric lamp and discharge devices – Spark plugs – Particular electrode structure or spacing
Reexamination Certificate
2007-03-19
2011-12-06
Patel, Nimeshkumar (Department: 2879)
Electric lamp and discharge devices
Spark plugs
Particular electrode structure or spacing
C313S011500, C313S311000
Reexamination Certificate
active
08072125
ABSTRACT:
A spark plug100comprised of a metal shell1, an insulator2, a center electrode3and a ground electrode4. A rear-end face of the ground electrode4is welded to a front-end face of the metal shell1, and a bent portion5located at the intermediated position in the longitudinal direction is bent toward the center of the spark plug100. The ground electrode4assumes a circular-shape with a diameter of 2 mm or less whereby an inflow of an air-fuel mixture is not disturbed even when the air-fuel mixture directly flows into a back face of the ground electrode4. The ground electrode4is comprised of an outer layer4A made of a nickel alloy and an inner layer4B made of pure copper with an excellent thermal conductivity, in which a ratio of a cross-sectional area of the inner layer4B to the entire cross-sectional area of the ground electrode4is 10% or more to 35% or less. Thus, the spark plug100which is excellent in heat sinking ability and can prevent a spring back phenomenon due to a difference in a coefficient of thermal expansion.
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Takafumi et al., Spark Plug for Internal Combustion Engine, Machine translation of JP-05-013146.
Office Action from corresponding Chinese Patent Application No. 2007-10088227.6, issued on Jun. 17, 2010 (with English translation); 22 pages.
Matsutani Wataru
Torii Kazuyoshi
Yoshida Kazumasa
Horikoshi Steven
Kusner & Jaffe
NGK Spark Plug Co. Ltd.
Patel Nimeshkumar
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