Aisin Seiki Kabushiki Kaisha

Tomohiro Sawada

Yasuhiro Kawabata

Soichi Hara

Shuji Inoue

Yuji Kato

Hiromi Niimi

The method of making a piston unit for an internal combustion engine incorporates the steps of pinching a melting core in a mold cavity of a piston mold wherein the melting core includes an inner ring that forms a ring shaped passage within a piston body, an outer ring and a plurality of coupling portions connected with between the inner ring and the outer ring. The method further includes pouring molten metallic alloy into the cavity and solidifying therein, removing the outer ring of the melting core, filling the space left by removal of the outer ring with reinforced material, and then melting the inner ring and the coupling portions of the melting core.

Method of making a piston unit for an internal combustion engine

Piston unit used in an internal combustion engine, which allows no interfacial crack between a piston and a wear-proof ring as well as allowing to provide T6 treatment to aluminum base alloy used for the piston. The piston unit has a piston formed of aluminum base alloy, and a wear-proof ring that has been fused with a first ring groove of the piston. The wear-proof ring is formed of copper-zinc alloy with its thermal expansion coefficient ranging from 19.5.times.10.sup.-6 m/m to 22.0.times.10.sup.-6 m/m. The copper zinc alloy may contain 63 wt. % of copper, 30 wt. % of zinc, 15 wt. % of aluminum, and 4% of titanium, or it may contain 70 wt. % of copper and 30% of zinc only.

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Aichi-pref., Japan

Tomohiro Sawada