| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston for an internal combustion engine capable of avoiding nonconformity of a pin hole inner peripheral end part such as a crack by applying conical machining, realizing efficient cooling of the piston by drilling a cooling channel and not causing lowering of structural strength. SOLUTION: This piston for the internal combustion engine to reciprocate in a cylinder of the internal combustion engine is furnished with a pin 3 to axially support a connecting rod free to oscillate, a pin hole 4 provided on a pin boss 6 of the piston to support the pin 3 and the cooling channel 7 drilled in a ring on the inside of the piston to circulate a coolant to cool the piston. The conical machining 13 is applied on a part of an inner peripheral surface 4a of the pin hole 4, and a relative clearance 14 is formed at least on one of an outer periphery of the pin 3 and an inner periphery of the pin hole 4 on a part adjacent to the cooling channel 7 on a boundary surface of the pin 3 and the pin hole 4.
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