Patent ID: 8434315

Claim:
A compressor drive torque estimating device to be adapted for a system provided with a refrigeration cycle in which a refrigerant is circulated by a compressor driven by an engine mounted in a vehicle, said compressor drive torque estimating device comprising: heat load detecting means for detecting a heat load of said refrigeration cycle, a storage unit storing a plurality of estimated drive torque characteristics used to control an engine output, establishing correlation between a drive torque change of said compressor and an elapsed time from a time of start of operation of said compressor, wherein the drive torque change varies according to the elapsed time throughout from the time of the start of operation of the compressor, and wherein said plurality of estimated drive torque characteristics are change degrees showing changes in an estimated drive torque for each predetermined time interval, an estimated drive torque characteristic selecting means for selecting said one of the plurality of estimated drive torque characteristics stored in the storage unit based on detected values detected by said heat load detecting means, and an estimated drive torque calculating means for calculating an estimated drive torque of said compressor in a transitory state after the time of the start of operation of said compressor, based on said estimated drive torque characteristic selected by said estimated drive torque characteristic selecting means and the elapsed time, wherein said estimated drive torque is calculated based on a drive torque change obtained from the correlation between said estimated drive torque characteristics and the elapsed time.