Fluid machine for Rankine cycle

A fluid machine comprising:

• an expansion device for generating a driving force by expansion of working fluid, which includes lubricating oil and is heated to become gas-phase condition;
• an electric power generator operated with the expansion device;
• and
• a housing for accommodating the expansion device and the electric power generator,
• wherein the fluid machine further comprises;
• an oil separating portion for separating the lubricating oil contained in the working fluid discharged from the expansion device;
• an oil pooling portion provided in the housing for pooling the lubricating oil separated from the working fluid;
• a heating unit for heating the lubricating oil;
• and
• an oil supply portion for supplying the lubricating oil pooled in the oil pooling portion to sliding portions of the expansion device.

A fluid machine comprising:

• a flat and annular cylinder for forming a cylinder chamber;
• a ring shaped piston accommodated in the cylinder chamber;
• a driving shaft inserted into a center portion of the ring shaped piston and driven by an external driving source;
• and
• bearings for rotatably supporting the driving shaft,
• wherein the ring shaped piston is operated within the cylinder chamber by rotation of the driving shaft, so that working fluid sucked into the cylinder chamber is pressurized and pumped out,
• an oil storing chamber is so formed around the driving shaft as to cover contacting portions of the driving shaft, which are in contact with the ring shaped piston and the bearings, the oil storing chamber being filled with lubricating oil having a higher viscosity than the working fluid, and
• a small space is formed at an axial side surface of the ring shaped piston and at an outer side of the oil storing chamber, the small space being held at a pressure lower than that of the oil storing chamber.

An expansion device comprises:

• a high pressure chamber, into which working fluid heated to a high pressure steam is introduced;
• a driven portion driven by expansion of the working fluid of the high pressure steam from the high pressure chamber;
• a low pressure portion, from which the working fluid, a pressure of which becomes lower as a result of the expansion, flows out of the expansion device;
• and
• a housing for accommodating the above high pressure chamber, the driven portion, and the low pressure portion,
• wherein the expansion device further comprises:
• a communication port formed in the housing for bypassing the driven portion and for directly communicating the high pressure chamber with the low pressure portion;
• and
• a switching device for opening and closing the communication port.