Control method and control device for air conditioning system, and air conditioning system

Abstract

This application provides a control method and control device for an air conditioning system, and an air conditioning system using the control method or including the control device. When switched to heating mode, a hot gas valve and a liquid injection valve are opened, and a main heat valve is closed. A condenser is excluded from refrigerant circulation. The refrigerant is heated by a motor of a compressor and exchanges heat with the outside via an evaporator to raise indoor ambient temperature. Part of the refrigerant returns to the compressor, while the rest enters a liquid reservoir via the liquid injection valve to reduce refrigerant flow rate and improve energy utilization. When operating for a specified time or when the indoor ambient temperature reaches a specified heating temperature, the liquid injection valve is closed to retain sufficient refrigerant in the heating circulation and avoid continuous decrease in heating performance.

What is claimed is: 
     
         1 . A control method for an air conditioning system, the air conditioning system including: a compressor, a main heat valve, a condenser, a liquid reservoir, an expansion valve, and an evaporator which are connected in sequence to form a refrigerant circulation loop; a hot gas valve having one end connected to an outlet of the compressor and the other end connected to an inlet of the evaporator; and a liquid injection valve having one end connected to an outlet of the evaporator and the other end connected to the liquid reservoir, the control method comprising:
 an air conditioning system setting mode determination step comprising determining whether the air conditioning system is set to a specified mode;   a hot gas valve opening step comprising opening the hot gas valve;   a main heat valve closing step comprising closing the main heat valve according to a determination result of the air conditioning system setting mode determination step;   a liquid injection valve opening step comprising opening the liquid injection valve;   a compressor starting step comprising starting the compressor to operate in the specified mode; and   a liquid injection valve closing step comprising closing the liquid injection valve when a specified closing condition is satisfied.   
     
     
         2 . The control method for an air conditioning system according to  claim 1 , wherein
 the specified mode is a heating mode.   
     
     
         3 . The control method for an air conditioning system according to  claim 2 , wherein
 the specified closing condition is that a specified time N passes after the compressor starting step is executed.   
     
     
         4 . The control method for an air conditioning system according to  claim 2 , wherein
 the specified closing condition is that a specified heating temperature is reached after the compressor starting step is executed.   
     
     
         5 . The control method for an air conditioning system according to  claim 3 , the control method further comprising:
 a standby operation step comprising stopping the operation of the compressor, keeping the main heat valve and the liquid injection valve closed, and keeping the hot gas valve opened if a heating temperature set in the heating mode is reached.   
     
     
         6 . The control method for an air conditioning system according to  claim 5 , the control method further comprising:
 a compressor restarting step comprising restarting the compressor to exit a standby operation mode if a temperature is lower than the heating temperature set in the heating mode.   
     
     
         7 . The control method for an air conditioning system according to  claim 6 , wherein
 the air conditioning system further includes a compressor suction pressure regulating valve disposed between an inlet of the compressor and the outlet of the evaporator.   
     
     
         8 . A control device for an air conditioning system, the control device comprising:
 an air conditioning system setting mode determination module configured to determine whether the air conditioning system is set to a specified mode;   a hot gas valve opening instruction generation module configured to generate and issue an instruction to open a hot gas valve;   a main heat valve closing instruction generation module configured to issue an instruction to close a main heat valve according to a determination result of the air conditioning system setting mode determination module;   a liquid injection valve opening instruction generation module configured to generate and issue an instruction to open a liquid injection valve;   a compressor starting module configured to start a compressor to operate in the specified mode; and   a liquid injection valve closing instruction generation module configured to generate and issue an instruction to close the liquid injection valve when a specified closing condition is satisfied.   
     
     
         9 . An air conditioning system comprising:
 a memory; and   the control device according to claim  8 .