Dual-Stage Compressor, Control Method Thereof and Air Conditioning Unit

Abstract

The present disclosure relates to a dual-stage compressor, a control method thereof, and an air conditioning unit. The dual-stage compressor includes a low-pressure stage; a high-pressure stage connected in series with the low-pressure stage; and a volume ratio adjustment mechanism arranged at the high-pressure stage and configured to adjust the volume ratio of refrigerant compression at the high-pressure stage. When the final compression pressure of the compressor is lower or greater than the exhaust pressure, the volume ratio adjustment mechanism is operated to increase or reduce the volume ratio of refrigerant compression at the high-pressure stage so that the final compression pressure of the compressor is equal to the exhaust pressure, and overcompression and undercompression are improved to adapt to changes in external conditions, increase the energy efficiency of the compressor, and reduce the noise of the compressor.

1 . A dual-stage compressor, comprising:
 a low-pressure stage;   a high-pressure stage connected in series with the low-pressure stage; and   a volume ratio adjustment mechanism arranged at the high-pressure stage and configured to adjust the volume ratio of refrigerant compression at the high-pressure stage.   
     
     
         2 . The dual-stage compressor according to  claim 1 , wherein the compressor is a screw compressor, and the volume ratio adjustment mechanism comprises a first slide valve adjustment mechanism configured to adjust an output position of an exhaust port at the high-pressure stage. 
     
     
         3 . The dual-stage compressor according to  claim 1 , further comprising a capacity adjustment mechanism arranged at the low-pressure stage and configured to adjust an output capacity of refrigerant compression at the low-pressure stage. 
     
     
         4 . The dual-stage compressor according to  claim 3 , wherein the capacity adjustment mechanism comprises a second slide valve adjustment mechanism configured to adjust the output capacity of a bypass port at the low-pressure stage. 
     
     
         5 . The dual-stage compressor according to  claim 3 , wherein the capacity adjustment mechanism comprises a plunger adjustment mechanism configured to implement capacity adjustment through a suction volume of a designated bypass. 
     
     
         6 . The dual-stage compressor according to  claim 3 , wherein the capacity adjustment mechanism comprises a rotation speed adjustment mechanism configured to control suction volume by changing the rotation speed of a motor so as to implement capacity adjustment. 
     
     
         7 . The dual-stage compressor according to  claim 2 , further comprising a first driving mechanism connected with the first slide valve adjustment mechanism and configured to drive the first slide valve adjustment mechanism to move. 
     
     
         8 . The dual-stage compressor according to  claim 4 , further comprising a second driving mechanism connected with the second slide valve adjustment mechanism and configured to drive the second slide valve adjustment mechanism to move. 
     
     
         9 . A control method of the dual-stage compressor according to  claim 1 , comprising:
 when a final compression pressure of the compressor is lower than an exhaust pressure of the compressor, operating the volume ratio adjustment mechanism to increase the volume ratio of refrigerant compression at the high-pressure stage;   when the final compression pressure of the compressor is greater than the exhaust pressure, operating the volume ratio adjustment mechanism to reduce the volume ratio of refrigerant compression at the high-pressure stage.   
     
     
         10 . An air conditioning unit, comprising the dual-stage compressor according to  claim 1 .