Patent ID: 6447258
Filing Date: 2002-09-10
Classification: F04B,Y10T

Abstract:
A control valve used in a variable displacement compressor, wherein the compressor draws refrigerant from an external refrigerant circuit, compresses the refrigerant and then discharges the compressed refrigerant to the external refrigerant circuit, wherein a zone that is exposed to suction pressure is connected to a crank chamber by a bleeding passage, and a zone that is exposed to discharge pressure is connected to the crank chamber by a supply passage, thereby adjusting the pressure in the crank chamber, wherein the displacement of the compressor is varied based on the pressure in the crank chamber, the control valve comprising:a valve housing; a valve chamber defined in the valve housing, the valve chamber forming a part of the supply passage or the bleeding passage; a valve body accommodated in the valve chamber, wherein the valve body is moved in the valve chamber to adjust the degree of opening of the supply passage or the bleeding passage; a first limiting member, wherein, when contacting the valve body, the first limiting member limits the movement of the valve body; a first urging member for urging the valve body toward the first limiting member; a pressure-sensitive chamber defined in the valve housing; a pressure-sensitive member movably arranged in the pressure-sensitive chamber, wherein the pressure-sensitive member divides the pressure-sensitive chamber into a first pressure chamber and a second pressure chamber, wherein the pressure-sensitive member is moved based on the pressures in the first and second pressure chambers, and wherein the pressure-sensitive member selectively separates from and engages with the valve body; first and second pressure monitoring points located in the external refrigerant circuit, the pressure difference between the two pressure monitoring points representing the compressor displacement, wherein the first pressure monitoring point is located in a higher pressure zone and the second pressure monitoring point is located in a lower pressure zone, wherein the first pressure chamber is exposed to the pressure at the first pressure monitoring point and the second pressure chamber is exposed to the pressure at the second pressure monitoring point, wherein, when the pressure-sensitive member is moved based on the pressure difference between the first and second pressure chambers, the movement of the pressure-sensitive member affects the position of the valve body such that the compressor displacement is changed to reduce fluctuations in the pressure difference between the first and second pressure chambers; a second limiting member, wherein, when contacting the pressure-sensitive member, the second limiting member limits the movement of the pressure-sensitive member; a second urging member for urging the pressure-sensitive member toward the second limiting member; and a control member, wherein the control member urges the valve body against the forces of the first and second urging members such that the valve body contacts the pressure-sensitive member, wherein the force applied to the valve body is externally controlled so that a set pressure difference, which is a reference value for determining the position of the valve body by the pressure-sensitive member, is changed.