Nippondenso Co., Ltd.

Ryoji Kondo

Kozo Takamura

Kanji Higuchi

Yasuyuki Sato

Minoru Nagai

A spark plug for internal combustion engines provided with a noble metal tip on the pointed top of a spark plug center electrode. The noble metal tip is welded to the center electrode top end by heating and pressing the portion to be welded. After the welding, the center electrode is shaped to provide the pointed top. The noble metal tip is a platinum alloy consisting of platinum of 85 through 70 in weight percentage and iridium of 15 through 30 in weight percentage.

Spark plug and the method of manufacturing the same

Spark plug and method of manufacturing the same

A spark plug for internal-combustion engines has a spark discharge gap defined between at least two electrodes opposing to each other, and a platinum-containing wear-resistant discharging layer provided on one of the electrodes. The spark plug has a thermal stress relieving layer disposed between the discharging layer and the base metal constituting the one eletrode. The thermal stress relieving layer is made of a platinum base alloy containing nickel, which constitutes the base metal. The discharging layer may be made of a material consisting essentially of 70 to 90 wt % platinum and 30 to 10 wt % iridium. The thermal stress relieving layer may be made of a material consisting essentially of 5 to 95 wt % platinum and 95 to 5 wt % nickel. Another platinum-containing wear-resistant layer may be provided on the other electrode, the wear-resistant layer being made of a material consisting essentially of 5 to 60 wt % nickel and 95 to 40 wt % platinum.

Spark plug for internal-combustion engine

An ignition plug of extended durability which reduces crack formation in noble metal layer on the center electrode and the ground electrode by joining a noblemental layer consisting of 85 to 70% by weight of Pt and 15 to 30% by weight of Ir to the spark discharge portion of the center electrode and also another noble metal layer consisting of 90 to 70% by weight of Pt and 10 to 30% by weight of Ni to the spark discharge portion of the ground electrode.

Growing community of inventors

Okazaki, Japan

Ryoji Kondo