| 摘要 |
PURPOSE:To secure a flow of hot water so as to prevent generation of casting failure when a cut-shaped piston is cast from a light alloy, by forming a chamber on the inner edge of a pin boss at both ends in such a manner that it is gouged out a little in its vertical direction and greatly at both ends. CONSTITUTION:A piston 1 is casted using a light alloy and is provided with a pin boss 2 which protrudes integrally at its opposite inner sides. The pin boss 2 has a lower hole 3 provided at one part and has also a chamber 4 integrally formed at its inner edge when it is casted. The chamfer 4 is formed by gouging out the inner edge of the pin boss a little in its vertical direction and greatly at both ends. The lower hole 3 portion is further formed as a precise pin hole 5 via a drill-cutting process, and a piston pin to which the small end of a connecting rod is axially attached is inserted into the hole to connect the piston 1 and the connecting rod. A pin hole 6 is offset as indicated by the amount 0 of offset at the drill-cutting process. |
