Refrigeration cycle device

Abstract

A refrigeration cycle device includes a third refrigerant passage connecting a utilization heat exchanger to a first expansion valve, a fourth refrigerant passage connecting the first expansion valve to a receiver, a fifth refrigerant passage connecting the receiver to a second expansion valve, a sixth refrigerant passage connecting the second expansion valve to an air heat exchanger, a hot-gas bypass passage connecting a discharge passage to the sixth refrigerant passage, a hot-gas bypass valve, an internal heat exchanger to exchange heat between the liquid refrigerant inside the receiver and the refrigerant passing through the suction passage, a liquid bypass passage including an inlet portion connected to the fourth refrigerant passage, the fifth refrigerant passage, or a lower portion of the receiver, and an outlet portion connected to the suction passage upstream of the internal heat exchanger, and a liquid bypass valve.

1 . A refrigeration cycle device comprising:
 a compressor to compress refrigerant;   a suction passage connecting to a suction port of the compressor;   a discharge passage connecting to a discharge port of the compressor;   an air heat exchanger to exchange heat between the refrigerant and air;   a utilization heat exchanger to exchange heat between the refrigerant and a heat medium;   a first refrigerant passage connecting the utilization heat exchanger to the discharge passage;   a second refrigerant passage connecting the air heat exchanger to the suction passage;   a receiver to store therein liquid refrigerant that is the refrigerant in liquid phase;   a first expansion valve;   a second expansion valve;   a third refrigerant passage connecting the utilization heat exchanger to the first expansion valve;   a fourth refrigerant passage connecting the first expansion valve to the receiver;   a fifth refrigerant passage connecting the receiver to the second expansion valve;   a sixth refrigerant passage connecting the second expansion valve to the air heat exchanger;   a hot-gas bypass passage connecting the discharge passage to the sixth refrigerant passage;   a hot-gas bypass valve provided on the hot-gas bypass passage;   an internal heat exchanger to exchange heat between the liquid refrigerant inside the receiver and the refrigerant passing through the suction passage, or between the refrigerant passing through the fourth refrigerant passage and the refrigerant passing through the suction passage;   a liquid bypass passage including an inlet portion connected to the fourth refrigerant passage, the fifth refrigerant passage, or a lower portion of the receiver, and an outlet portion connected to the suction passage upstream of the internal heat exchanger; and   a liquid bypass valve provided on the liquid bypass passage.   
     
     
         2 . The refrigeration cycle device according to  claim 1 , further comprising
 controlling circuitry to execute a heating operation that causes the refrigerant discharged from the compressor to flow into the utilization heat exchanger, and a hot-gas defrost operation that melts frost adhering to the air heat exchanger,   wherein at a time of the heating operation, the controlling circuitry is configured to cause the refrigerant discharged from the compressor to flow into the utilization heat exchanger by closing the hot-gas bypass valve and the liquid bypass valve,   at a time of the hot-gas defrost operation, the controlling circuitry is configured to cause the refrigerant discharged from the compressor to pass through the hot-gas bypass passage and flow into the air heat exchanger by opening the hot-gas bypass valve and closing the second expansion valve, and   at the time of the hot-gas defrost operation, the controlling circuitry is configured to cause the liquid refrigerant to flow into the suction passage from the liquid bypass passage by opening the liquid bypass valve continuously or intermittently.   
     
     
         3 . The refrigeration cycle device according to  claim 2 , further comprising
 a detector to detect a suction superheat degree that is a superheat degree of the refrigerant to be sucked by the compressor,   wherein at the time of the hot-gas defrost operation, the controlling circuitry is configured to control an operation of the liquid bypass valve so that the suction superheat degree becomes close to a target.   
     
     
         4 . The refrigeration cycle device according to  claim 2 , further comprising
 a detector to detect a discharge superheat degree that is a superheat degree of the refrigerant discharged from the compressor,   wherein at the time of the hot-gas defrost operation, the controlling circuitry is configured to control an operation of the liquid bypass valve so that the discharge superheat degree becomes close to a target.   
     
     
         5 . The refrigeration cycle device according to  claim 2 ,
 wherein the refrigeration cycle device is configured to be able to execute the hot-gas defrost operation without stopping a flow of the heat medium in the utilization heat exchanger.   
     
     
         6 . The refrigeration cycle device according to  claim 2 , further comprising:
 a refrigerant circuit switching valve to switch between a forward cycle circuit in which the refrigerant discharged from the compressor flows into the utilization heat exchanger through the first refrigerant passage, and a reverse cycle circuit in which the refrigerant discharged from the compressor flows into the air heat exchanger through the second refrigerant passage; and   a temperature sensor to detect a temperature of the heat medium,   wherein when melting frost adhering to the air heat exchanger, the controlling circuitry is configured to execute the hot-gas defrost operation when the temperature of the heat medium is lower as compared with a reference, and is configured to execute a reverse cycle defrost operation that circulates the refrigerant into the reverse cycle circuit when the temperature of the heat medium is higher as compared with the reference.   
     
     
         7 . The refrigeration cycle device according to  claim 2 ,
 wherein at the time of the hot-gas defrost operation, the controlling circuitry is configured to cause the liquid refrigerant inside the utilization heat exchanger to flow into the fourth refrigerant passage by opening the first expansion valve continuously or intermittently.   
     
     
         8 . The refrigeration cycle device according to  claim 2 ,
 wherein at the time of the hot-gas defrost operation, the controlling circuitry is configured to control an operation of the liquid bypass valve so that the refrigerant of superheated gas flows out from the air heat exchanger.   
     
     
         9 . The refrigeration cycle device according to  claim 1 , wherein the refrigerant is flammable refrigerant. 
     
     
         10 . The refrigeration cycle device according to  claim 1 , wherein an accumulator is not provided on the suction passage. 
     
     
         11 . The refrigeration cycle device according to  claim 1 , further comprising
 a bypass heating heat exchanger to heat the liquid refrigerant passing through the liquid bypass passage by the heat medium,   wherein the liquid bypass passage includes a first passage connecting the inlet portion to the bypass heating heat exchanger, and a second passage connecting the bypass heating heat exchanger to the outlet portion.   
     
     
         12 . The refrigeration cycle device according to  claim 11 , comprising
 a liquid bypass expansion valve that is the liquid bypass valve configured by an expansion valve capable of adjusting a flow rate,   wherein the liquid bypass expansion valve is positioned on the second passage.   
     
     
         13 . The refrigeration cycle device according to  claim 12 , further comprising
 a liquid bypass solenoid valve positioned on the first passage,   wherein the liquid bypass solenoid valve is configured to decompress the liquid refrigerant passing through the first passage.