Air conditioner for vehicle

Abstract

In a refrigerant cycle device for a vehicle air conditioner, a refrigerant flow switching device is configured to switch one of a cooling mode, a first heating mode and a second heating mode. In the first heating mode, refrigerant discharged from a compressor flows through a radiator, a heating decompression device and an exterior heat exchanger in this order, and the refrigerant flowing out of the exterior heat exchanger is introduced to a refrigerant suction side of the compressor while bypassing an evaporator. In contrast, in the second heating mode, the refrigerant discharged from the compressor flows into the radiator, and the refrigerant flowing out of the radiator is introduced to the refrigerant suction side of the compressor while bypassing both the exterior heat exchanger and the evaporator, so that the refrigerant radiates heat at the radiator.

1 . An air conditioner for a vehicle, comprising:
 a compressor configured to compress and discharge refrigerant;   an exterior heat exchanger configured to perform heat exchange between the refrigerant and air outside of a vehicle compartment;   an evaporator, arranged in an air conditioning case, to perform a heat exchange between low-pressure and low-temperature refrigerant and air to be blown into the vehicle compartment;   a radiator disposed to cool a high-pressure and high-temperature refrigerant by performing a heat exchange between the high-pressure and high-temperature refrigerant and air having passed through the evaporator;   a refrigerant flow switching device configured to switch one of refrigerant cycles of a cooling mode, a first heating mode and a second heating mode;   a first decompression device configured to decompress refrigerant at least in the refrigerant cycle of the cooling mode; and   a second decompression device configured to decompress refrigerant at least in the refrigerant cycle of the first heating mode, wherein   the refrigerant cycle of the cooling mode is configured such that the refrigerant discharged from the compressor flows through the exterior heat exchanger, the first decompression device, the evaporator and a refrigerant suction side of the compressor in this order, so that the refrigerant absorbs heat at the evaporator and radiates heat at the exterior heat exchanger,   the refrigerant cycle of the first heating mode is configured such that the refrigerant discharged from the compressor flows through the radiator, the second decompression device and the exterior heat exchanger in this order, and the refrigerant flowing out of the exterior heat exchanger is introduced to the refrigerant suction side of the compressor while bypassing the evaporator, so that the refrigerant absorbs heat at the exterior heat exchanger and radiates heat at the radiator,   the refrigerant cycle of the second heating mode is configured such that the refrigerant discharged from the compressor flows into the radiator, and the refrigerant flowing out of the radiator is introduced to the refrigerant suction side of the compressor while bypassing both the exterior heat exchanger and the evaporator, so that the refrigerant radiates heat at the radiator, and   the refrigerant flow switching device switches the refrigerant cycle from the first heating mode to the second heating mode, when a physical amount having a relation with a heating capacity of the first heating mode becomes a value at which the heating capacity is low in the first heating mode.   
     
     
         2 . The air conditioner according to  claim 1 , further comprising
 an air heater disposed in the air conditioning case at a downstream air side of the evaporator to heat air by using a heat source different from the refrigerant cycle, wherein the radiator is disposed in the air conditioning case at a downstream air side of the air heater, to heat air after passing through the air heater by performing heat exchange with refrigerant.   
     
     
         3 . The air conditioner according to  claim 1 , wherein
 the refrigerant cycle of the second heating mode is configured such that the refrigerant discharged from the compressor flows into the radiator, and the refrigerant flowing out of the radiator is introduced to the refrigerant suction side of the compressor after being decompressed by the second decompression device.   
     
     
         4 . The air conditioner according to  claim 1 , further comprising
 a third decompression device configured to decompress the refrigerant discharged from the compressor, before flowing into the radiator in the second heating mode.   
     
     
         5 . The air conditioner according to  claim 1 , further comprising
 an outside air temperature sensor disposed to detect an outside air temperature as the physical amount, wherein the refrigerant flow switching device is configured to switch the refrigerant cycle from the first heating mode to the second heating mode when the outside air temperature detected by the outside air temperature sensor is lower than a predetermined temperature.   
     
     
         6 . The air conditioner according to  claim 1 , further comprising
 a pressure detection device disposed to detect a refrigerant pressure at the refrigerant suction side of the compressor, as the physical amount,   wherein the refrigerant flow switching device is configured to switch the refrigerant cycle from the first heating mode to the second heating mode, when the refrigerant pressure detected by the pressure detection device is lower than a predetermined pressure.   
     
     
         7 . The air conditioner according to  claim 1 , further comprising
 a temperature detection device disposed to detect a refrigerant temperature at a refrigerant discharge side of the compressor, as the physical amount,   wherein the refrigerant flow switching device is configured to switch the refrigerant cycle from the first heating mode to the second heating mode, when the refrigerant temperature detected by the temperature detection device is higher than a predetermined temperature in the first heating mode.   
     
     
         8 . The air conditioner according to  claim 1 , wherein
 the radiator includes
 a first radiator part disposed in the air conditionig case at a downstream air side of the evaporator, to heat air after passing through the evaporator by using a liquid fluid flowing therein, and 
 a second radiator part disposed to radiate heat from high-pressure and high-temperature refrigerant to the liquid fluid by performing heat exchange between high-pressure and high-temperature refrigerant and the liquid fluid. 
   
     
     
         9 . The air conditioner according to  claim 8 , further comprising
 a liquid heater configured to heat the liquid fluid flowing to the first radiator part.