Patent ID: 7121190

Claim:
A gas compression refrigerating system comprising: a fluid machine for performing a pump mode operation for compressing working fluid and a motor mode operation for generating mechanical energy by converting fluid pressure into kinetic energy; and a fluid passage change-over device operatively connected to the fluid machine for selectively allowing the working fluid to and/or from the fluid machine through the fluid passage change-over device, depending on operational modes at the fluid machine, wherein the fluid machine comprises: multiple working chambers, each having a piston movable in a reciprocal manner so that the volume of the working chamber can be increased and/or decreased by the reciprocal movement of the piston, the multiple working chambers being composed of a first working chamber and a second working chamber; a first and a second pump mode passages for allowing the working fluid from an inlet side to an output side of the fluid machine through the first and second working chambers to perform the pump mode operations at the respective working chambers, when the working fluid of low pressure is supplied to the inlet side and the pistons of the first and second working chambers are driven to move in the reciprocal manner; a high pressure chamber and a low pressure chamber to be respectively communicated with the second working chamber; and a valve mechanism selectively forming a motor mode passage connecting the high pressure chamber and the low pressure chamber at least through the second working chamber, wherein the fluid passage change-over device and the valve mechanism change-over the fluid passage for the second working chamber from the second pump mode passage to the motor mode passage, so that the second working chamber performs the motor mode operation when the super heated working fluid of high pressure is introduced into the second working chamber, and the valve mechanism prevents the working fluid from flowing in the reversed direction in the motor mode operation.