Refrigerant cycle system with expansion energy recovery

A refrigerant cycle system comprising:

• a compressor for compressing refrigerant;
• a radiator for cooling refrigerant discharged from said compressor, said radiator having therein a pressure higher than the critical pressure of refrigerant;
• an expansion-energy recovering unit for decompressing and expanding refrigerant discharged from said radiator in a refrigerant expansion, and for converting expansion energy during the refrigerant expansion to mechanical energy to supply the mechanical energy to said compressor, said expansion-energy recovering unit being integrated with said compressor such that said expansion-energy recovering unit and said compressor are rotated with the same rotation speed;
• an evaporator for evaporating refrigerant decompressed in said expansion-energy recovering unit, to which refrigerant from said radiator is introduced through a refrigerant passage;
• a throttle unit for adjusting an opening area of said refrigerant passage, disposed in said refrigerant passage;
• a pressure detection unit for detecting a pressure of high-pressure side refrigerant discharged from said compressor, said pressure detection unit being disposed at an upstream side of said throttle unit in a refrigerant flow direction;
• a temperature detection unit for detecting the temperature of the high-pressure side refrigerant;
• and
• a control unit which controls an opening degree of said throttle unit to control the pressure of high-pressure side refrigerant based on the temperature of the high-pressure side refrigerant detected by the temperature detection unit.

A refrigerant cycle system comprising:

• a compressor for compressing refrigerant;
• a radiator for cooling refrigerant discharged from said compressor, said radiator having therein a pressure higher than the critical pressure of refrigerant;
• an expansion-energy recovering unit for decompressing and expanding refrigerant discharged from said radiator, and for recovering expansion energy during a refrigerant expansion, said expansion-energy recovering unit being disposed to supply the recovered expansion energy to said compressor;
• an evaporator for evaporating refrigerant decompressed in said expansion-energy recovering unit;
• a control unit for controlling a driving force for driving said compressor;
• a pressure detection unit for detecting the pressure of high-pressure side refrigerant;
• a temperature detection unit for detecting the temperature of the high-pressure side refrigerant;
• and
• a control valve disposed at an upstream side of said expansion-energy recovering unit in a refrigerant flow direction to control the pressure of the high-pressure side refrigerant based on the temperature of the high-pressure side refrigerant detected by the temperature detection unit.