Patent ID: 7624672

Claim:
A piston apparatus comprising: a piston pin that includes a pin-side air inlet and a gas inflow port, gas being caused to flow out through the pin-side air inlet from a pin-side hollow portion provided in the piston pin, the gas being taken in the pin-side hollow portion through the gas inflow port, the piston pin being attached to a piston which performs reciprocating motion in a cylinder; a crankshaft that includes a crank-side air inlet and a gas outflow port, the gas being caused to flow out through the crank-side air inlet from a crank-side hollow portion provided in the crankshaft, the gas in the crank-side hollow portion being fed in the pin-side hollow portion through the gas outflow port; a connecting rod that has a first end portion and a second end portion, the first end portion being joined to an eccentric portion of the crankshaft, the second end portion being joined to the piston pin, the connecting rod feeding the gas in the crank-side hollow portion to the pin-side hollow portion through a gas passage formed in the connecting rod; a first pressure release unit that is provided between the gas outflow port and the crank-side air inlet; and a second pressure release unit that is provided between the gas inflow port and the pin-side air inlet.