Patent ID: 6520749
Filing Date: 2003-02-18
Classification: F04B

Abstract:
A control valve for controlling the displacement of a variable displacement compressor used in a refrigerant circuit, wherein the compressor includes a crank chamber and a pressure control passage, which is connected to the crank chamber, the displacement of the compressor changes in accordance with the pressure in the crank chamber, and wherein the control valve adjusts the opening size of the pressure control passage, thereby controlling the pressure in the crank chamber, the control valve comprising:a valve housing; a valve body accommodated in the valve housing, wherein the valve body adjusts the opening size of the pressure control passage; a pressure-sensing chamber defined in the valve housing; a pressure-sensing member, which divides the pressure-sensing chamber into a first pressure chamber and a second pressure chamber, the first pressure chamber being exposed to the pressure at a first pressure monitoring point, which is located in the refrigerant circuit, the second pressure chamber being exposed to the pressure at a second pressure monitoring point, which is located in the refrigerant circuit, wherein the pressure at the first pressure monitoring point is higher than the pressure at the second pressure monitoring point, wherein the pressure-sensing member actuates the valve body in accordance with the pressure difference between the pressure chambers, thereby controlling the displacement of the compressor such that fluctuations of the pressure difference between the pressure chambers are cancelled; a first urging member, which urges the pressure-sensing member from one of the pressure chambers toward the other one of the pressure chambers; a second urging member, which urges the pressure-sensing member in the same direction as the first urging member urges the pressure-sensing member; and an actuator, wherein the actuator urges the pressure-sensing member by a force, the magnitude of which corresponds to an external command.