By-pass device in variable displacement compressor

Abstract

A by-pass device in a variable displacement compressor has a by-pass passage, a valve body and a deformable separator. The by-pass passage interconnects a discharge pressure region with a crank chamber for releasing refrigerant from the discharge pressure region to the crank chamber. The valve body is arranged in the by-pass passage for opening and closing the by-pass passage. The deformable separator separates a back pressure region from the by-pass passage without sliding. The valve body is urged from a side of an opened position where the valve body is spaced from a valve seat toward a side of a closed position where the valve body contacts with the valve seat by pressure applied from the back pressure region to the separator. The valve body is moved from the closed position to the opened position by deforming the deformable separator.

What is claimed is:  
     
         1 . A by-pass device in a variable displacement compressor which adjusts pressure in a crank chamber in such a manner that refrigerant in a discharge pressure region is introduced into the crank chamber through a supply passage and the refrigerant in the crank chamber is released to a suction pressure region through a bleed passage, displacement of the compressor being controlled by adjusting the pressure in the crank chamber, the by-pass device comprising: 
 a by-pass passage interconnecting the discharge pressure region with the crank chamber for releasing the refrigerant from the discharge pressure region to the crank chamber;    a valve body arranged in the by-pass passage for opening and closing the by-pass passage; and    a deformable separator separating a back pressure region from the by-pass passage without sliding, wherein the valve body is urged from a side of an opened position toward a side of a closed position, the valve body being spaced from a valve seat at the opened position, the valve body contacting with the valve seat by pressure applied from the back pressure region to the separator, the valve body being moved from the closed position to the opened position by deforming the separator.    
     
     
         2 . The by-pass device according to  claim 1 , wherein the deformable separator is set to be broken when pressure differential between the discharge pressure region and the back pressure region increases to an abnormal level.  
     
     
         3 . The by-pass device according to  claim 1 , wherein the back pressure region is a part of atmospheric region.  
     
     
         4 . The by-pass device according to  claim 1 , further comprising: 
 an urging means for elastically urging the deformable separator from the side of the back pressure region so as to urge the valve body from the side of the opened position toward the side of the closed position; and    an urging force adjustor for adjusting urging force of the urging means.    
     
     
         5 . The by-pass device according to  claim 4 , wherein the urging means is a spring, the urging force adjustor is a screw member which serves as a spring seat for the spring, a position where the screw member is screwed being changed to vary spring force of the spring.  
     
     
         6 . The by-pass device according to  claim 1 , wherein the deformable separator is a diaphragm.  
     
     
         7 . The by-pass device according to  claim 6 , wherein the diaphragm includes a convex portion as the valve body for opening and closing a valve hole.  
     
     
         8 . The by-pass device according to  claim 6 , wherein the valve body forms a ball shape, the valve body being connected to the diaphragm.  
     
     
         9 . The by-pass device according to  claim 1 , wherein the deformable separator is a bellows.  
     
     
         10 . The by-pass device according to  claim 1 , wherein the pressure in the discharge pressure region is applied to a central portion of the valve body, the pressure in the crank chamber being applied to a peripheral portion of the valve body.  
     
     
         11 . The by-pass device according to  claim 1 , wherein the deformable separator elastically deforms to move the valve body from the closed position to the opened position.