DRIVING TORQUE-CALCULATING DEVICE FOR VARIABLE DISPLACEMENT COMPRESSOR, AND AIR CONDITIONING SYSTEM FOR VEHICLE

[Summary] [Purpose] To provide a variable displacement compressor driving torque calculation device easily adaptable to vehicle designs, and thus, highly versatile, and an automotive air-conditioning system equipped with this device. [Solution] The driving torque calculation device comprises a radiator-inlet refrigerant pressure sensor (46) for detecting pressure of the refrigerant at an inlet of a radiator (24), a radiator-outlet refrigerant pressure sensor (48) for detecting pressure of the refrigerant at an outlet of the radiator (24), a rotational speed detection means for detecting rotational speed of the variable displacement compressor (100), a suction pressure detection means for detecting suction pressure with which the variable displacement compressor (100) sucks the refrigerant, and a calculation means for calculating driving torque on the variable displacement compressor (100) on the basis of the pressures of the refrigerant at the inlet and the outlet of the radiator (24), the rotational speed of the variable displacement compressor (100) and the suction pressure.