Patent ID: 6385979
Filing Date: 2002-05-14
Classification: F04B

Abstract:
A displacement control apparatus for a variable displacement compressor used in a refrigerant circuit of a vehicle air conditioner, wherein the compressor is driven by a drive source of a vehicle, the apparatus comprising:a displacement control mechanism, which controls the displacement of the compressor based on the pressure difference between the pressures at two pressure monitoring points located in the refrigerant circuit, the pressure difference representing the displacement of the compressor; a first device for detecting external information representing the required cooling performance of the refrigerant circuit; a second device for detecting external information representing the load acting on the drive source; and a controller for determining a target value of the pressure difference based on the external information detected by the first device, wherein the displacement control mechanism controls the displacement of the compressor such that the pressure difference seeks the target value, wherein the controller judges whether to set a limit value of the pressure difference based on the external information detected by the second device, wherein, when the limit value is set and a compressor displacement that corresponds to the target value is greater than a compressor displacement that corresponds to the limit value, the controller uses the limit value as the target value of the pressure difference to limit the compressor displacement.