Patent ID: 7735329

Claim:
A control device for the air-conditioning system of a motor vehicle, the air-conditioning system comprising: an evaporator, a compressor with an externally controlled variable displacement located downstream of said evaporator, and an expansion valve located upstream of said evaporator; wherein said control device comprises: (i) a control means for receiving a reference temperature (T REF ) indicating a temperature of air that is desired to reach downstream of the evaporator, and an effective temperature (T MIS ) indicating a temperature of the air present downstream of said evaporator, said control means providing a control signal (S C ) to said compressor cause said effective temperature (T MIS ) to be substantially equal to said reference temperature (T REF ); (ii) observer means for receiving the control signal (S C ), and to supply a temperature disturbance (ΔT EVAP ) indicating an estimate of an oscillatory effect generated by the expansion valve on the temperature of the air downstream of the evaporator when the compressor is driven by the control signal (S C ); and (iii) first adder means for removing from said effective temperature (T MIS ) said temperature disturbance (ΔT EVAP ) to therefore eliminate the oscillatory effect on said effective temperature (T MIS ) of the air downstream of the evaporator.