| 摘要 |
An early rise in temperature of a piston and suppression of overheating thereof are made compatible with each other. Provision is made for: a crown with a cavity formed to be recessed from a piston top surface toward a piston lower side; an outer peripheral portion joined to the crown so as to surround at least a piston outer peripheral side of the crown, and having ring grooves formed on its outer periphery for holding piston rings; cooling channels including a gap between the crown and the outer peripheral portion, and being formed at the piston outer peripheral side and at the piston lower side of said cavity so as to make the piston outer peripheral side and the piston lower side in communication with each other; and at least two communication holes to make the cooling channels and a piston outside in communication with each other, and to serve as an inlet port or an outlet port for lubricating oil. |
