Ngk Spark Plug Company, Limited

Kazumi Kawamura

Akira Suzuki

Takahiro Suzuki

Yoshihiro Matsubara

Shigeyasu Yamada

Kazuya Iwata

Masahiro Ishikawa

Shinichi Hiramatsu

Shuji Nakamura

A method of making a spark plug having a noble metal chip joined to an electrode main body of a ground electrode by interposing therebetween an intermediate member. The method comprises the steps of prior to joining the noble metal chip to the electrode main body, joining the intermediate member and the noble metal chip together, placing a noble metal chip and intermediate member assembly on the electrode main body in a way as to allow the intermediate member to contact the electrode main body, and welding the electrode main body and the intermediate member together while restricting relative movement of the electrode main body and the intermediate member without applying an urging force to a joint between the intermediate member and the noble metal chip.

Method of making a spark plug

In a spark plug for a gas engine including a ground electrode (4) whose front end is to be placed in a combustion chamber of a gas engine which is driven by gaseous fuel, a metallic shell (3) enclosing a center electrode (5) which has a noble metal tip (18) superior in spark-erosion resistance at a firing portion in which a spark discharge occurs against the ground electrode (4). A resistor (10) is provided within the spark plug or a spark plug cap so as to be included in a spark plug voltage circuit which applies a high voltage to the center electrode. It is preferable that the noble metal tip (18) has a diameter in a range of 0.5.about.1.5 mm, and that the resistor has an electrical resistance greater than or equal to 50 k.OMEGA..

Spark plug including a ground electrode, a center electrode, and a

A spark plug for an internal combustion engine with both sides of a surface, on a center electrode side, of an outer electrode and/or both side portions, on the top surface of the center electrode, form wedge-shaped projections. At least one surface having the wedge-shaped projection has no plane surface but is arcuate.

Spark plug for internal combustion engine

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Mie, Japan

Kazumi Kawamura