Long life spark plug having minimum noble metal amount

An economical spark plug for an internal combustion engine which has a long service life and by which a reduction in the discharge voltage and the use of the minimum amount of a noble metal can be achieved. The spark plug has an insulator, a center electrode supported by the insulator, and an earth...

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Bibliographic Details
Main Authors KATOH; AKIO, KANAO; KEIJI
Format Patent
LanguageEnglish
Published 23.11.1999
Edition6
Subjects
BASIC ELECTRIC ELEMENTS
CORONA DEVICES
ELECTRICITY
GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
OVERVOLTAGE ARRESTERS USING SPARK GAPS
SPARK GAPS
SPARKING PLUGS
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Summary:An economical spark plug for an internal combustion engine which has a long service life and by which a reduction in the discharge voltage and the use of the minimum amount of a noble metal can be achieved. The spark plug has an insulator, a center electrode supported by the insulator, and an earth electrode facing to the center electrode. A narrowed portion is arranged on a tip of an electrode material of at least one of the center electrode and the earth electrode. The narrowed portion includes a projection formed by extending the electrode material and a noble metal chip firmly connected to a terminal end of the projection. The electrode material is a nickel-base heat-resisting alloy. The noble metal chip is made of a Pt-Ir alloy essentially consisting of 90-100% by weight Pt and 0-10% by weight Ir. A diameter D of the narrowed portion is in a range of 0.6-1.2 mm. A thickness t of the noble metal chip is in a range of 0.16-0.8 mm. A length L of the narrowed portion including the thickness t of the noble metal chip is in a range of 0.8-1.5 mm.
Bibliography:Application Number: US19930068700