Displacement control valve for variable displacement compressor

Abstract

A displacement control valve for a variable displacement compressor includes a valve hole partially forming a supply passage or a bleed passage of the compressor and a valve body having a cross-sectional area changed portion that is movable into and out of the valve hole. The cross-sectional area changed portion has a minimum cross-sectional area portion and a maximum cross-sectional area portion. The cross-sectional area changed portion is shaped so that the cross-sectional area of the cross-sectional area changed portion increases from the minimum cross-sectional area portion to the maximum cross-sectional area portion. The minimum cross-sectional area portion initially enters into the valve hole when the cross-sectional area changed portion is moved into the valve hole. The maximum cross-sectional area portion is movable into the valve hole. The valve hole is closed when the maximum cross-sectional area portion is positioned in the valve hole.

1 . A displacement control valve used for a variable displacement compressor that adjusts a pressure in a pressure control chamber by introducing a refrigerant in a discharge pressure region into the pressure control chamber through a supply passage and releasing the refrigerant in the pressure control chamber to a suction pressure region through a bleed passage, thereby controlling displacement of the compressor, the displacement control valve comprising: 
 a valve hole partially forming the supply passage or the bleed passage; and    a valve body having a cross-sectional area changed portion that is movable into and out of the valve hole, wherein the cross-sectional area changed portion has a minimum cross-sectional area portion and a maximum cross-sectional area portion, wherein the cross-sectional area changed portion is shaped so that a cross-sectional area of the cross-sectional area changed portion increases from the minimum cross-sectional area portion to the maximum cross-sectional area portion, wherein the minimum cross-sectional area portion initially enters into the valve hole when the cross-sectional area changed portion is moved into the valve hole, wherein the maximum cross-sectional area portion is movable into the valve hole, and wherein the valve hole is closed when the maximum cross-sectional area portion is positioned in the valve hole.    
   
   
       2 . The displacement control valve according to  claim 1 , wherein the cross-sectional area changed portion has a conical peripheral surface.  
   
   
       3 . The displacement control valve according to  claim 1 , wherein a minute clearance is formed between the maximum cross-sectional area portion and a circumferential wall surface of the valve hole when the maximum cross-sectional area portion is positioned in the valve hole for allowing the refrigerant to flow therethrough slightly.  
   
   
       4 . The displacement control valve according to  claim 1 , wherein the valve hole is a part of the supply passage, and wherein the displacement control valve is adapted to open the valve hole when the compressor is at its minimum displacement.  
   
   
       5 . The displacement control valve according to  claim 1 , wherein the valve hole is a part of the bleed passage, and wherein the displacement control valve is adapted to close the valve hole when the compressor is at its minimum displacement.  
   
   
       6 . The displacement control valve according to  claim 1 , wherein the cross-sectional area changed portion is tapered toward the valve hole.  
   
   
       7 . The displacement control valve according to  claim 1 , further comprising a pressure sensing means operable to sense a pressure of a first point in the discharge pressure region and a pressure of a second point in the discharge pressure region and to regulate a position of the valve body based on pressure difference between the first and second points.  
   
   
       8 . The displacement control valve according to  claim 7 , wherein the pressure sensing means includes a first pressure sensing chamber, a second pressure sensing chamber and a displacement body that divides the first and second pressure sensing chambers, wherein the valve body is connected to the displacement body, wherein the pressure of the first point is introduced into the first pressure sensing chamber, and wherein the pressure of the second point is introduced into the second pressure sensing chamber.  
   
   
       9 . The displacement control valve according to  claim 8 , wherein the displacement body is a bellows.  
   
   
       10 . The displacement control valve according to  claim 1 , further comprising a rod connected to the valve body, wherein the displacement control valve is formed so that the rod receives the pressure in the discharge pressure region and the pressure in the pressure control chamber, and wherein a load resulting from the pressure in the discharge pressure region and a load resulting from the pressure in the pressure control chamber act against each other through the rod.  
   
   
       11 . The displacement control valve according to  claim 1 , further comprising a rod connected to the valve body, wherein the displacement control valve is formed so that the rod receives the pressure in the discharge pressure region and the pressure in the suction pressure region, and wherein a load resulting from the pressure in the discharge pressure region and a load resulting from the pressure in the suction pressure region act against each other through the rod.  
   
   
       12 . The displacement control valve according to  claim 1 , further comprising a solenoid for generating an electromagnetic force acting on the valve body.