Control valve system

Abstract

A control valve system of a variable displacement swash plate type compressor for use in a heating and cooling air conditioner, which includes a throttling valve provided in a refrigerating circuit, a constant differential pressure valve arranged to open when a differential pressure between upstream and downstream pressures of the throttling valve reaches a predetermined value, thereby introducing compressor discharge gas to a crank chamber, external information detecting device for detecting external information such as cooling load or vehicle running state, and controller for determining an opening of the throttling valve based on the external information, and which is capable of performing a stable feedback control of the discharge capacity in a range from a small discharge capacity to a large discharge capacity, and suppressing the decrease in compressor efficiency at large discharge capacity.

What is claimed is:  
     
         1 . A control valve system of a variable displacement swash plate type compressor for use in a heating and cooling air conditioner, comprising: 
 a throttling valve provided in a refrigerating circuit;    a constant differential pressure valve arranged to open when a differential pressure between upstream and downstream pressures of the throttling valve reaches a predetermined value, thereby introducing compressor discharge gas to a crank chamber;    external information detecting means for detecting external information such as cooling load or vehicle running state; and    control means for determining an opening of the throttling valve based on the external information.    
     
     
         2 . The control valve system according to  claim 1 , wherein said throttling valve is an electromagnetic valve and integrally mounted to said constant differential pressure valve.  
     
     
         3 . The control valve system according to  claim 1  or  2 , wherein said constant differential pressure valve is arranged to introduce the compressor discharge gas on the upstream side of said throttling valve into the crank chamber.  
     
     
         4 . The control valve system according to  claim 3 , further comprising a cutoff valve disposed on the downstream side of said throttling valve.  
     
     
         5 . The control valve system according to  claim 3  or  4 , wherein a discharge gas inflow chamber is formed on the upstream side of said throttling valve, the compressor discharge gas in said discharge gas inflow chamber is introduced into the crank chamber, and said discharge gas inflow chamber has an inlet thereof directed tangential to a wall surface of the discharge gas inflow chamber.  
     
     
         6 . The control valve system according to  claim 5 , wherein said discharge gas inflow chamber is formed with a plurality of inlets that are circumferentially spaced from one another.  
     
     
         7 . The control valve system according to  claim 1  or  2 , wherein said throttling valve has a pressure receiving portion that presses said throttling valve in a direction to be opened when it receives a downstream side pressure.  
     
     
         8 . The control valve system according to  claim 7 , wherein the pressure receiving portion has the same area as that of a downstream-side pressure receiving surface of said throttling valve.