Air-conditioning apparatus

Abstract

An air-conditioning apparatus includes a heat-source-unit-side heat exchanger, a plurality of use-side heat exchangers, and a relay unit provided between the heat-source-unit-side heat exchanger and the plurality of use-side heat exchangers. The relay unit is configured to switch part of the plurality of use-side heat exchangers to a cooling operation side to switch part of the plurality of use-side heat exchangers to a heating operation side, and simultaneously performs a cooling and heating simultaneous operation by switching each of the plurality of use-side heat exchangers to the cooling operation side or the heating operation side in accordance with a control instruction.

1 . An air-conditioning apparatus comprising:
 a heat-source-unit-side heat exchanger;   a plurality of use-side heat exchangers; and   a relay unit provided between the heat-source-unit-side heat exchanger and the plurality of use-side heat exchangers, configured to switch part of the plurality of use-side heat exchangers to a cooling operation side, and switch part of the plurality of use-side heat exchangers to a heating operation side,   wherein the air-conditioning apparatus performs a cooling and heating simultaneous operation by switching each of the plurality of use-side heat exchangers to the cooling operation side or the heating operation side in accordance with a control instruction,   wherein the relay unit includes
 a flow rate control unit configured to adjust a flow rate of a refrigerant to be distributed to the heat-source-unit-side heat exchanger and a use-side heat exchanger that is performing the cooling operation among the plurality of use-side heat exchangers, and 
 a controller configured to adjust the flow rate control unit, and 
   wherein the controller
 obtains, based on a downstream-side temperature on a downstream side of the flow rate control unit and a liquid pipe temperature of the use-side heat exchanger that is performing the cooling operation among the plurality of use-side heat exchangers, a target control temperature of the downstream-side temperature, and 
 controls the liquid pipe temperature by adjusting the flow rate control unit in accordance with the target control temperature. 
   
     
     
         2 . The air-conditioning apparatus of  claim 1 ,
 wherein the controller   obtains a reference temperature difference between the downstream-side temperature and the liquid pipe temperature serving as a reference before a flow rate of the refrigerant flowing in the relay unit varies,   obtains a current temperature difference between the downstream-side temperature and the liquid pipe temperature when the flow rate of the refrigerant flowing in the relay unit varies,   obtains a correction amount of the downstream-side temperature, based on the reference temperature difference and the current temperature difference,   obtains the target control temperature, based on the downstream-side temperature and the correction amount, and   controls the liquid pipe temperature, based on the target control temperature.   
     
     
         3 . The air-conditioning apparatus of  claim 2 ,
 wherein the controller   decreases the target control temperature when the flow rate of the refrigerant flowing in the relay unit increases, and   increases the target control temperature when the flow rate of the refrigerant flowing in the relay unit decreases.   
     
     
         4 . The air-conditioning apparatus of  claim 3 , further comprising:
 a compressor configured to compress a refrigerant and discharge the compressed refrigerant;   an injection pipe provided between the relay unit and the heat-source-unit-side heat exchanger and allowing the refrigerant that is to flow into the heat-source-unit-side heat exchanger to be supplied to the compressor;   a compressor flow rate control device provided at the injection pipe and configured to adjust a flow rate of the refrigerant that is to flow into the compressor; and   a heat-source-unit-side heat exchanger flow rate control device connected in parallel to the compressor flow rate control device and configured to adjust a flow rate of the refrigerant to be distributed to the heat-source-unit-side heat exchanger,   wherein the flow rate control device, the compressor flow rate control device, and the heat-source-unit-side heat exchanger flow rate control device are connected in series to one another.   
     
     
         5 . The air-conditioning apparatus of  claim 4 ,
 wherein the controller   adjusts an opening degree of the flow rate control unit to control the flow rate of the refrigerant to be supplied to the compressor flow rate control device and the heat-source-unit-side heat exchanger flow rate control device.