Air-conditioning apparatus

Abstract

An air-conditioning apparatus that includes a compressor, a heat-source-side heat exchanger, a plurality of use-side heat exchangers, and a relay unit which switches some of the plurality of use-side heat exchangers to the cooling operation side and which switches some of the plurality of use-side heat exchangers to the heating operation side and that 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, includes a second flow rate control device which adjusts the flow rate of the refrigerant flowing into the compressor, a third flow rate control device which is connected in parallel to the second flow rate control device and which adjusts the flow rate of the refrigerant flowing into the heat-source-side heat exchanger, and a controller which adjusts the second flow rate control device and the third flow rate control device. The controller adjusts the opening degree of the second flow rate control device and the opening degree of the third flow rate control device in accordance with the outside air temperature.

1 . An air-conditioning apparatus including
 a single compressor configured to compress a refrigerant and discharges the compressed refrigerant,   a heat-source-side heat exchanger configured to exchange heat between the refrigerant and an ambient heat source medium,   a plurality of use-side heat exchangers configured to exchange heat between the refrigerant and an ambient use medium, and   a relay unit provided between the heat-source-side heat exchanger and the plurality of use-side heat exchangers, which switches part of the plurality of use-side heat exchangers to the cooling operation side, and which switches part of the plurality of use-side heat exchangers to the 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, the apparatus comprising:   an injection pipe provided between the relay unit and the heat-source-side heat exchanger and configured to allow the refrigerant flowing into the heat-source-side heat exchanger to be supplied to the single compressor;   a first flow rate control device provided at the injection pipe and which adjusts a flow rate of the refrigerant flowing into the single compressor;   a second flow rate control device connected in parallel to the first flow rate control device and configured to adjust a flow rate of the refrigerant flowing into the heat-source-side heat exchanger; and   a controller configured to adjust the first flow rate control device and the second flow rate control device,   wherein the controller   adjusts an opening degree of the first flow rate control device and an opening degree of the second flow rate control device in accordance with an outside air temperature.   
     
     
         2 . The air-conditioning apparatus of  claim 1 ,
 wherein the controller   sets an injection start threshold at which the refrigerant starts to be supplied from the injection pipe,   sets an opening degree reduction threshold at which a flow rate of the refrigerant passing through the second flow rate control device decreases,   increases an opening degree of the first flow rate control device at a predetermined ratio when the outside air temperature is lower than or equal to the injection start threshold, and   reduces an opening degree of the second flow rate control device when the outside air temperature is lower than or equal to the opening degree reduction threshold.   
     
     
         3 . The air-conditioning apparatus of  claim 2 ,
 wherein the relay unit   includes a flow rate control unit which is connected in series to the first flow rate control device and the second flow rate control device and which adjusts a flow rate of the refrigerant flowing in the relay unit, and   adjusts an opening degree of the flow rate control unit in accordance with the outside air temperature.   
     
     
         4 . The air-conditioning apparatus of  claim 3 ,
 wherein the relay unit   sets a first ratio and a first threshold corresponding to the first ratio,   sets a second ratio which is larger than the first ratio and a second threshold which corresponds to the second ratio,   reduces the opening degree of the flow rate control unit at the first ratio when the outside air temperature is lower than or equal to the first threshold, and   reduces the opening degree of the flow rate control unit at the second ratio when the outside air temperature is lower than or equal to the second threshold.   
     
     
         5 . The air-conditioning apparatus of  claim 4 , further comprising:
 a flow rate control valve provided between the relay unit and the heat-source-side heat exchanger, connected in parallel to the second flow rate control device, and configured to adjust the flow rate of the refrigerant, wherein   the controller   adjusts an opening degree of the flow rate control valve in accordance with the outside air temperature.   
     
     
         6 . The air-conditioning apparatus of  claim 5 ,
 wherein the controller   increases an amount of refrigerant supplied from the relay unit and flowing to the compressor by adjusting the opening degree of the first flow rate control device when the outside air temperature is lower than or equal to the injection start threshold, and   reduces an amount of refrigerant supplied from the relay unit and flowing to the heat-source-side heat exchanger by adjusting the opening degree of the second flow rate control device and the opening degree of the flow rate control valve when the outside air temperature is lower than or equal to the opening degree reduction threshold.