Air-conditioning apparatus

Abstract

An air-conditioning apparatus includes a heat source unit, an indoor unit, a relay unit connected to the heat source unit by a low-pressure pipe and a high-pressure pipe, connected to the indoor unit via a gas branch pipe and a liquid branch pipe, and a controller. The relay unit includes a branch portion at which the gas branch pipe and the low-pressure pipe communicate with each other when the indoor unit performs the cooling operation and the gas branch pipe and the high-pressure pipe communicate with each other when the indoor unit performs the heating operation. The branch portion includes an expansion valve that is connected to the gas branch pipe and the low-pressure pipe. The controller is configured to, when the heat source unit is stopped, control the expansion valve to allow the gas branch pipe and the low-pressure pipe to communicate with each other.

1 . An air-conditioning apparatus comprising:
 a heat source unit including a compressor, a flow switching valve, and a heat-source-side heat exchanger;   an indoor unit including a load-side flow control valve and a load-side heat exchanger and configured to perform a cooling operation or a heating operation;   a relay unit connected to the heat source unit by a low-pressure pipe and a high-pressure pipe, connected to the indoor unit via a gas branch pipe and a liquid branch pipe, and configured to supply refrigerant supplied from the heat source unit to the indoor unit; and   a controller,   wherein the relay unit includes a branch portion at which the gas branch pipe and the low-pressure pipe communicate with each other when the indoor unit performs the cooling operation, and at which the gas branch pipe and the high-pressure pipe communicate with each other when the indoor unit performs the heating operation,   the branch portion includes an expansion valve that is connected to the gas branch pipe and the low-pressure pipe and whose opening degree is adjustable, and   the controller is configured to, when the heat source unit is stopped, control the expansion valve to allow the gas branch pipe and the low-pressure pipe to communicate with each other.   
     
     
         2 . The air-conditioning apparatus of  claim 1 , wherein
 the expansion valve is a three-way electric expansion valve including a first flow passage in which the gas branch pipe and the low-pressure pipe communicate with each other and a second flow passage in which the gas branch pipe and the high-pressure pipe communicate with each other.   
     
     
         3 . The air-conditioning apparatus of  claim 2 , wherein
 the controller is configured to, when the heat source unit is stopped, control the three-way electric expansion valve to open the first flow passage and close the second flow passage.   
     
     
         4 . The air-conditioning apparatus of  claim 3 , wherein
 the controller is configured to, when the heat source unit is operating and the indoor unit is stopped, control the three-way electric expansion valve to close the first flow passage and the second flow passage.   
     
     
         5 . The air-conditioning apparatus of  claim 3 , wherein
 the controller is configured to, when the heat source unit is operating and the indoor unit performs the cooling operation, control the three-way electric expansion valve to open the first flow passage and close the second flow passage.   
     
     
         6 . The air-conditioning apparatus of  claim 3 , wherein
 the controller is configured to, when the heat source unit is operating and the indoor unit performs the heating operation, control the three-way electric expansion valve to open the second flow passage and close the first flow passage.   
     
     
         7 . The air-conditioning apparatus of  claim 1 , wherein
 the expansion valve is an expansion valve for cooling, comprising a two-way electric expansion valve, and   the branch portion further includes an opening-closing valve for heating, connected between the gas branch pipe and the high-pressure pipe.   
     
     
         8 . The air-conditioning apparatus of  claim 7 , wherein
 the controller is configured to, when the heat source unit is stopped, control the expansion valve for cooling to allow the gas branch pipe and the low-pressure pipe to communicate with each other and control the opening-closing valve for heating to close the gas branch pipe and the high-pressure pipe.