Patent ID: 6481215
Filing Date: 2002-11-19
Classification: F02G,F25B

Abstract:
A gas compressor-expander having a space in the rear of a piston within a cylinder for compressing or expanding a gas, and a mechanism chamber provided with a power transmission therein, a partition wall being provided between the piston rear space and the mechanism chamber and having a rod slidably extending therethrough for interconnecting the piston and the power transmission and a seal device surrounding the rod, the gas compressor-expander being characterized in that the seal device comprises:a first seal member having a higher sealing property against a flow from the mechanism chamber toward the piston rear space than against a flow in the opposite direction for preventing lubricating oil in the mechanism chamber from ingressing into the piston rear space, an intermediate chamber provided adjacent the first seal member at a side thereof toward the piston rear space and forming around the rod an annular space having a radial dimension larger than the thickness of a lubricating oil film formed on a surface of the rod, a second seal member disposed adjacent the intermediate chamber at a side thereof toward the piston rear space for preventing working gas in the piston rear space from ingressing into the intermediate chamber, and a communication channel extending between the intermediate chamber and the mechanism chamber to cause the chambers to communicate with each other for sending gas through said channel from the mechanism chamber into the intermediate chamber.