Heat pump air conditioning system for vehicle

Abstract

A heat pump air conditioning system for a vehicle, wherein the system can efficiently use electric power and a discharge temperature can be set to an optimal level. During dehumidifying-heating operation in which air for air conditioning passes through a fourth heater exchanger after passing through a third heat exchanger, a first blower and a second blower are cooperatively operated by adjusting, according to the voltage supplied to the first blower, the voltage supplied to the second blower. When the discharge temperature of the air for air conditioning flowing from a first heat exchanger is higher than a first predetermined temperature and the rotational speed of a refrigerant compressor is minimum, the cooperative operation between the first blower and the second blower is stopped and the electric power to the second blower is adjusted to lower the discharge temperature to a level lower than a second predetermined temperature.

1 . A heat pump air conditioning system for a vehicle, comprising:
 a refrigerant compressor;   a first heat exchanger, for heat discharge, that performs heat exchange between a refrigerant discharged from the refrigerant compressor and a heat medium;   a second heat exchanger, for heat discharge, that is disposed downstream of the first heat exchanger and performs heat exchange between the refrigerant discharged from the refrigerant compressor and external atmospheric air;   a depressurizing unit that is disposed downstream of the second heat exchanger and decreases a pressure of the refrigerant;   a third heat exchanger, for heat absorption, that is disposed downstream of the depressurizing unit and performs heat exchange between a heat source and the refrigerant;   a fourth heat exchanger, for heat absorption, that is disposed on an upstream side of the first heat exchanger with respect to a flow of the heat medium introduced to the first heat exchanger;   a cooling-heating switching unit for switching between a flow of the refrigerant and the heat medium in cooling operation and a flow of the refrigerant and the heat medium in heating operation;   a first blower for sending the heat medium to the first heat exchanger and the fourth heat exchanger;   a second blower for sending the heat medium from the heat source to the third heat exchanger; and   a control section for controlling the refrigerant compressor, the cooling-heating switching unit, the first blower, and the second blower,   wherein, the control section performs collaborated operation of the second blower in association with the first blower in dehumidification heating operation in which the refrigerant passes through the fourth heat exchanger after the refrigerant passes through the third heat exchanger, and if a discharge temperature of the heat medium from the first heat exchanger is higher than a first predetermined temperature and a rotation speed of the refrigerant compressor is lower than a predetermined rotation speed, the control section releases the collaborated operation between the first blower and the second blower to adjust an electrical power for the second blower and thereby makes the discharge temperature become lower than a second predetermined temperature.   
     
     
         2 . The heat pump air conditioning system according to  claim 1 ,
 wherein, if an external atmospheric temperature is within a first predetermined range in dehumidification cooling operation, the control section switches the dehumidification cooling operation to the dehumidification heating operation to make the refrigerant flow through the third heat exchanger and adjusts the electrical power for the second blower, to thereby control the discharge temperature to be within a second predetermined range.