Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus 100 according to the present invention includes: a refrigerant circuit 160 including a compressor 101, a condenser ( 102 or 106 ), a first throttling device ( 103 or 105 ), a gas-liquid separator 104, a second throttling device ( 105 or 103), and an evaporator ( 106 or 102 ); an injection passage 170 through which a gas phase refrigerant separated out in the gas-liquid separator 104 is supplied to the compressor 101 during a compression process; a detector 130 for detecting a temperature or a pressure of a refrigerant present on a downstream side of the first throttling device and on an upstream side of the second throttling device in the refrigerant circuit 160 or present in the injection passage 170; and a controller 108 for decreasing an opening degree of the first throttling device when the controller 108 recognizes, by the detector 130, that a pressure of the refrigerant flowing into the gas-liquid separator 104 exceeds a specified pressure lower than a saturation vapor pressure, in a starting operation, a defrosting operation or a stopping operation.

1 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit including a compressor for compressing a refrigerant, a condenser for condensing the refrigerant compressed in the compressor, a first throttling device for expanding the refrigerant condensed in the condenser, a gas-liquid separator for separating the refrigerant expanded in the first throttling device into a gas phase refrigerant and a liquid phase refrigerant, a second throttling device for expanding the liquid phase refrigerant separated out in the gas-liquid separator, and an evaporator for evaporating the refrigerant expanded in the second throttling device, the refrigerant circuit being a refrigerant circuit through which the refrigerant that does not reach a supercritical state after being compressed in the compressor circulates;   an injection passage through which the gas phase refrigerant separated out in the gas-liquid separator is supplied to the compressor during a compression process;   a detector for detecting a temperature or a pressure of the refrigerant present on a downstream side of the first throttling device and on an upstream side of the second throttling device in the refrigerant circuit or present in the injection passage; and   a controller for decreasing an opening degree of the first throttling device when the controller recognizes, by the detector, that a pressure of the refrigerant flowing into the gas-liquid separator exceeds a specified pressure lower than a saturation vapor pressure, in a starting operation, a defrosting operation or a stopping operation.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , wherein the controller decreases the opening degree of the first throttling device and increases an opening degree of the second throttling device when the controller recognizes, by the detector, that the pressure of the refrigerant flowing into the gas-liquid separator exceeds the specified pressure in the starting operation, the defrosting operation or the stopping operation. 
     
     
         3 . The refrigeration cycle apparatus according to  claim 1 , wherein the detector is a temperature sensor, and in the starting operation, the defrosting operation or the stopping operation, the controller compares a temperature Ti detected by the temperature sensor to a threshold value Ti 1 , and determines that the pressure of the refrigerant flowing into the gas-liquid separator exceeds the specified pressure if a relationship of Ti>Ti 1  holds. 
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , wherein at least in the starting operation, the controller decreases the opening degree of the first throttling device, or decreases the opening degree of the first throttling device and increases an opening degree of the second throttling device when the controller recognizes, by the detector, that the pressure of the refrigerant flowing into the gas-liquid separator exceeds the specified pressure. 
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein the controller ends the starting operation after a specified period of time has elapsed since start of the operation. 
     
     
         6 . The refrigeration cycle apparatus according to  claim 4 , further comprising a condenser temperature sensor for detecting a temperature of the refrigerant flowing through the condenser,
 wherein the controller compares a rate of change with time, ΔTc, calculated from the temperature detected by the condenser temperature sensor to a threshold value ΔTc 1 , and ends the starting operation if a relationship of ΔTc>ΔTc 1  holds.   
     
     
         7 . The refrigeration cycle apparatus according to  claim 4 , further comprising an evaporator temperature sensor for detecting a temperature of the refrigerant flowing through the evaporator,
 wherein the controller compares a rate of change with time, ΔTe, calculated from the temperature detected by the evaporator temperature sensor to a threshold value ΔTe 1 , and ends the starting operation if a relationship of ΔTe>ΔTe 1  holds.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 1 , further comprising a switching device capable of switching between a heating operation and a cooling operation.