Spark plug

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 surfa...

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Bibliographic Details
Main Authors ITO SATOKO, MATSUTANI WATARU, YOSHIMOTO OSAMU, SEGAWA MASAYUKI
Format Patent
LanguageEnglish
Published 08.03.2005
Edition7
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: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.
Bibliography:Application Number: US20020297201