Patent ID: 6412294
Filing Date: 2002-07-02
Classification: F04B

Abstract:
A controller for a variable displacement compressor, wherein the compressor is used for air conditioning a compartment and includes a suction pressure zone, a discharge pressure zone, and a control chamber, which is connected to the suction pressure zone and to the discharge pressure zone, and wherein the pressure in the control chamber is adjusted for controlling the displacement of the compressor, the controller comprising:a refrigerant circuit connected to the compressor, wherein two pressure monitoring points are located in the refrigerant circuit; a control valve for controlling the pressure in the control chamber, wherein the control valve operates based on the actual pressure difference between the pressure monitoring points such that a target value of the pressure difference between the pressure monitoring points, which is externally determined, is maintained; a detection circuit, wherein the detection circuit-includes a temperature sensor for monitoring a temperature that represents the temperature of the compartment, wherein the detection circuit produces a first detection signal when the sensed temperature exceeds a threshold value and a second detection signal when the sensed temperature falls below the threshold value; and a pressure difference changer, wherein, the pressure difference changer gradually increases the target value of the pressure difference when the first signal is received from the detection circuit and gradually decreases the target value of the pressure difference when the second signal is received from the detection circuit.