Patent ID: 7628592

Claim:
A fluid machine in which: an expansion mechanism for producing power by the expansion of fluid, a compression mechanism for compressing fluid, and a rotating shaft for transmitting power produced in the expansion mechanism to the compression mechanism are housed in a container-shaped casing; and fluid discharged from the compression mechanism is fed to the outside of the casing by way of an internal space defined in the casing; wherein: lubricating oil is stored on the side of the compression mechanism in the inside of the casing; and the fluid machine comprises: an oil supply passageway which is formed in the rotating shaft and which supplies lubricating oil stored in the inside of the casing to a sliding portion of the expansion mechanism and has a terminating end from which surplus lubricating oil which has not been supplied to the sliding portion of the expansion mechanism is discharged; and an oil return passageway for guiding the surplus lubricating oil towards the compression mechanism from the terminating end of the oil supply passageway.