Aluminum alloy cylinder head with valve seat formed integrally by copper alloy cladding layer and underlying alloy layer

摘要

This internal combustion engine cylinder head includes a main portion made substantially from aluminum alloy and having a valve port which has a circumferential valve seat surface for cooperation with a poppet valve to open and close communication through the valve port. A cladding layer is formed of copper alloy claddingly laid upon this valve seat surface, and an intermediate alloy layer is present between the copper alloy cladding layer and the main cylinder head portion, this intermediate alloy layer being composed essentially of an alloy between the aluminum alloy of the main cylinder head portion and the copper alloy of the cladding layer. Thereby, the anti-wear properties of the valve seat are desirably improved without making the fabrication process unduly troublesome or costly. The proportion of aluminum diffused into the copper alloy cladding layer from the main portion of the cylinder head should preferably be not more than about 15%. The thickness of the intermediate alloy layer should preferably be between about 5 microns and about 300 microns, and the thickness of the copper alloy cladding layer should preferably be at least about 50 microns. If "x" denotes the thickness of the intermediate alloy layer in microns, this thickness value being between about 5 and about 300, and if "y" denotes the thickness of the copper alloy cladding layer in mm, then preferably the relationship y=1.5254x+42.373 should at least approximately hold.