Fluid machine

摘要

In a compression/expansion unit (30) as a fluid machine, both a compression mechanism (50) and an expansion mechanism (60) are stored in a casing (31). An oil feed passage (90) is formed in a shaft (40) for connecting the compression mechanism (50) to the expansion mechanism (60). A refrigerating machine oil accumulated at the bottom of the casing (31) is sucked into the oil feed passage (90) and fed to the compression mechanism (50) and the expansion mechanism (60). The refrigerating machine oil fed to the expansion mechanism (60) is discharged together with a refrigerant after its expansion from the expansion mechanism (60), and flows in a refrigerant circuit, and thereafter, returns to the compression mechanism (50).