Air conditioner for vehicle

Abstract

An air-conditioner for a vehicle includes a vapor-compression refrigeration cycle, a determination unit and a controller. The refrigeration cycle includes a compressor, an inside condenser, an outside heat exchanger, and an inside evaporator. The refrigeration cycle is capable of operating an outside-air heat-absorption heating operation in which refrigerant absorbs heat at the outside heat exchanger and radiates heat at the inside condenser, and an inside-air heat-absorption heating operation in which refrigerant absorbs heat at the inside evaporator and radiates heat at the inside condenser. The determination unit determines whether or not the outside heat exchanger freezes. The controller changes over the outside-air heat-absorption heating operation to the inside-air heat-absorption heating operation when the determination unit determines that the outside heat exchanger freezes. According to the air-conditioner, a heating operation can be maintained without increasing drive power for the compressor even when the outside heat exchanger freezes.

1 . An air-conditioner for a vehicle, comprising:
 a vapor-compression refrigeration cycle that includes a compressor for compressing refrigerant, an inside condenser for exchanging heat between refrigerant compressed by the compressor and air to be supplied to a passenger compartment to heat the air, an outside heat exchanger for exchanging heat between refrigerant and air outside a passenger compartment, and an inside evaporator for exchanging heat between refrigerant and air to be supplied to a passenger compartment to cool the air, and is capable of operating an outside-air heat-absorption heating operation in which refrigerant absorbs heat at the outside heat exchanger and refrigerant radiates heat at the inside condenser, and an inside-air heat-absorption heating operation in which refrigerant absorbs heat at the inside evaporator and refrigerant radiates heat at the inside condenser;   a determination unit for determining whether or not the outside heat exchanger is frozen; and   a controller that changes over the outside-air heat-absorption heating operation to the inside-air heat-absorption heating operation when the determination unit determines that the outside heat exchanger is frozen.   
     
     
         2 . The air-conditioner for a vehicle according to  claim 1 , wherein
 the refrigeration cycle further includes a pressure regulator for regulating pressure of refrigerant to be supplied to the outside heat exchanger, a first bypass path bypassing the outside heat exchanger, a first flowpath changeover unit for changing over a refrigerant flow to the outside heat exchanger or to the first bypass path, a pressure reducer for reducing pressure of refrigerant to be supplied to the inside evaporator, a second bypass path bypassing the inside evaporator, and a second flowpath changeover unit for changing over a refrigerant flow to the inside evaporator or to the second bypass path,   in the outside-air heat-absorption heating operation, set is a refrigerant path in which refrigerant compressed by the compressor flows sequentially through the inside condenser, the pressure regulator, the outside heat exchanger and the second bypass path, and then returns to the compressor, wherein the pressure regulator decompresses refrigerant, and,   in the inside-air heat-absorption heating operation, set is a refrigerant path in which refrigerant compressed by the compressor flows sequentially through the inside condenser, the first bypass path, the pressure reducer and the inside evaporator, and then returns to the compressor, wherein the pressure reducer decompresses refrigerant.   
     
     
         3 . The air-conditioner for a vehicle according to  claim 2 , wherein
 the refrigeration cycle is capable of further operating a re-heat cooling operation in which refrigerant absorbs heat at the inside evaporator and refrigerant radiates heat at both of the inside condenser and the outside heat exchanger, and,   in the re-heat cooling operation, set is a refrigerant path in which refrigerant compressed by the compressor flows sequentially through the inside condenser, the pressure regulator, the outside heat exchanger, the pressure reducer and the inside evaporator, and then returns to the compressor, wherein the pressure regulator doesn't decompress refrigerant.   
     
     
         4 . The air-conditioner for a vehicle according to  claim 1 , further comprising
 an outside-heat-exchanger passing-through air temperature detector for detecting temperature of air after passing through the outside heat exchanger, and a refrigerant temperature detector for detecting temperature of refrigerant at an outlet of the outside heat exchanger, wherein   the determination unit determines whether or not the outside heat exchanger is frozen based on deference between the temperature of air detected by the outside-heat-exchanger passing-through air temperature detector and the temperature of refrigerant detected by the refrigerant temperature detector.   
     
     
         5 . The air-conditioner for a vehicle according to  claim 1 , wherein,
 in the inside-air heat-absorption heating operation, air inside a passenger-compartment is supplied to the inside evaporator, and then supplied to the inside condenser.   
     
     
         6 . The air-conditioner for a vehicle according to  claim 1 , further comprising
 a heater for heating air to be supplied to a passenger compartment,   a foot-outlet temperature detector for detecting temperature of air blowing out from a foot outlet port, and   a defroster/vent-outlet temperature detector for detecting temperature of air blowing out from a defroster outlet port and a vent outlet port, wherein   the controller controls a heating amount of the heater based on the temperatures of air detected by the foot-outlet temperature detector and the defroster/vent-outlet temperature detector.   
     
     
         7 . The air-conditioner for a vehicle according to  claim 1 , further comprising
 an inlet-air temperature and humidity detector for detecting temperature and humidity of air to be supplied to the inside evaporator, and   an outside-air temperature detector for detecting temperature of outside air, wherein   the controller calculates dew-point temperature in a passenger compartment based on detection results of the inlet-air temperature and humidity detector and the outside-air temperature detector, and controls a humidifying amount of the inside evaporator based on the calculated dew-point temperature.   
     
     
         8 . The air-conditioner for a vehicle according to  claim 1 , wherein
 the outside heat exchanger includes a plurality of tubes, a pair of tanks disposed on both ends of the plurality of tubes, a reservoir tank for accumulating refrigerant, and a plurality of partitions, each of the tanks being provided with at least one of the plurality of partitions, and   a partition positioned most downstream along a refrigerant flow path within the outside heat exchanger among the plurality of partitions is configured to be capable of guiding introduction of refrigerant into the reservoir tank and to flow refrigerant with low flow resistance.