Displacement control apparatus and method for variable displacement compressor

摘要

A control valve is located in a variable displacement compressor used in a refrigerant circuit. The control valve operates such that the pressure difference between two pressure monitoring points in the refrigerant circuit seeks a predetermined target value. A controller determines the target value of the pressure difference in accordance with external information that represents the required cooling performance. The target value of the pressure difference is represented by a duty ratio applied to the control valve. When the acceleration pedal is pressed beyond a predetermined level, the controller limits the duty ratio. Therefore, the compressor torque does not hinder quick vehicle acceleration. Also, the cooling performance is not lowered unless it is necessary.