Air-conditioning apparatus

Abstract

To provide an air-conditioning apparatus that can prevent the formation of frost on indoor-side heat exchangers functioning as an evaporator even when the outside air temperature is low, and can use unmodified normal indoor units even when a portion of the indoor units is used in a place that has a large sensible heat load. An air-conditioning apparatus capable of simultaneous heating and cooling operation includes a heat source unit, a plurality of indoor units, and a relay unit that connects the heat source unit to the indoor units. A flow control unit that controls a flow amount of a refrigerant that flows through the indoor units that are in cooling operation is provided to a piping on the downstream side of a merging section of a piping through which flows the refrigerant that flows out from the indoor units that are in cooling operation.

1 . An air-conditioning apparatus, comprising:
 a heat source unit having a compressor, a four-way switching valve, and a heat source unit-side heat exchanger that is connected to the four-way switching valve;   a plurality of indoor units each having an indoor-side heat exchanger and a first flow control device connected to one end of the indoor-side heat exchanger; and   a relay unit that connects the heat source unit to the indoor units,   the air-conditioning apparatus being capable of simultaneous heating and cooling operation in which each of the indoor units selectively performs a cooling operation or a heating operation, wherein   the relay unit is connected to the heat source unit by a first connecting piping through which a refrigerant that flows out to the heat source unit flows and a second connecting piping through which the refrigerant that flows in from the heat source unit flows, and   the relay unit comprises   a first branching unit that switchably connects the other end of each indoor-side heat exchanger to the first connecting piping or the second connecting piping,   a second branching unit that switchably connects each first flow control device to the first connecting piping or the second connecting piping, and   a flow control unit provided to the first connecting piping that controls a flow amount of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator.   
     
     
         2 . The air-conditioning apparatus of  claim 1 , wherein
 the flow control unit comprises an openable and closable valve device and a capillary tube connected in parallel to the valve device, and   a flow amount of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator is controlled by the opening and closing of the valve device.   
     
     
         3 . The air-conditioning apparatus of  claim 1 , wherein
 the flow control unit includes a second flow control device whose opening degree can be changed, and   a flow amount of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator is controlled by controlling the opening degree of the second flow control device.   
     
     
         4 . The air-conditioning apparatus of  claim 1 , wherein when the heat source unit-side heat exchanger functions as an evaporator, the indoor-side heat exchangers functioning as an evaporator, the flow control unit, and the heat source unit are serially connected. 
     
     
         5 . The air-conditioning apparatus of  claim 1 , wherein the flow control unit adjusts a flow amount of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator based on an evaporation temperature of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator. 
     
     
         6 . The air-conditioning apparatus of  claim 1 , wherein a temperature detection device that detects the temperature of the refrigerant is provided to the first connecting piping between the first branching unit and the flow control unit, and
 a flow amount of the refrigerant that flows through the indoor-side heat exchangers functioning as an evaporator is controlled based on a temperature detected by the temperature detection device.