Patent ID: 6820438
Filing Date: 2004-11-23
Classification: B60H

Abstract:
An air conditioner for a vehicle having an engine for running the vehicle, the air conditioner comprising:a refrigerant cycle including a compressor, driven by at least one of the engine and an electrical motor, for compressing refrigerant, and an evaporator for cooling air to be blown into a passenger compartment of the vehicle by performing a heat exchange between the air and low-pressure low-temperature refrigerant in the refrigerant cycle supplied by operation of the compressor; and an air-conditioning control unit for controlling the compressor, wherein: the air-conditioning control unit includes a target temperature calculating means for calculating a target temperature of the evaporator to be lower as a cooling load in the passenger compartment becomes higher, a control means for controlling the compressor in such a manner that an actual temperature of the evaporator approaches to the target temperature, and a basis temperature setting means for setting a basis temperature that is higher than the target temperature by a predetermined temperature; when the actual temperature of the evaporator is higher than the basis temperature, the air-conditioning control unit outputs an engine drive signal for requiring a drive of the engine, and the compressor is operated by a driving force transmitted from the engine; when the actual temperature of the evaporator is lower than the basis temperature, the air-conditioning control unit prohibits an output of the engine drive signal and outputs a motor drive signal for requiring a drive of the electrical motor to drive the electrical motor, and the compressor is operated by a driving force from the electrical motor; the basis temperature setting means includes a predetermined temperature calculation means for calculating the predetermined temperature in accordance with the target temperature such that the predetermined temperature becomes higher as the target temperature becomes lower; and the basis temperature setting means sets the basis temperature to be not higher than a predetermined comfortable limit temperature.