JP5875710B2 - Air conditioner - Google Patents

Description

  The present invention is applied to, for example, a building multi-air conditioner equipped with a refrigerant circuit and a structure capable of efficiently supplying hot and cold produced by a heat source machine, or both hot and cold to a plurality of loads. The present invention relates to an air conditioner used.

Conventionally, in an air conditioner such as a multi air conditioner for buildings, for example, a cooling operation or a heating operation is performed by circulating a refrigerant between an outdoor unit that is a heat source unit arranged outdoors and an indoor unit arranged indoors. It is supposed to be. Specifically, the air-conditioning target space is cooled or heated by air cooled by heat absorbed by the refrigerant or air heated by heat released from the refrigerant. As the refrigerant used in such an air conditioner, for example, an HFC (hydrofluorocarbon) refrigerant is often used. In addition, one using a natural refrigerant such as carbon dioxide (CO ₂ ) has been proposed.

  As such, there is an air conditioner that connects a heat source unit and a plurality of indoor units and supplies a refrigerant from the heat source unit to the plurality of indoor units to enable a cooling / heating operation (for example, Patent Document 1). In the air conditioner described in Patent Literature 1, three-way connection is made to the first connection pipe (6b, 6c, 6d) and the first connection pipe (6) or the second connection pipe (7) in a switchable manner. The first branch portion (10) including the switching valve (8), the second connection pipe (7b, 7c, 7d) on the indoor unit side, and the second connection pipe (7) are connected to the check valve (50b, 50c, 50d, 52b, 52c, 52d), and a second branch portion (11) connected thereto.

  In the air conditioner described in Patent Document 1, switching between the refrigerant flowing into the indoor unit to be heated and the refrigerant flowing in from the indoor unit that is performing the cooling operation is performed by three-way switching of the first branch section (10). This is done with valve (8). Each check valve constituting the second branch portion (11) allows the refrigerant to flow in one direction in accordance with the switching of the refrigerant in the first branch portion (10). Yes. Therefore, when the indoor unit performs a cooling operation, one of the connection ports (first port 8a) of the three-way switching valve (8) is closed and two of the connection ports (second port 8b and third port). The mouth 8c) is an open circuit. When the indoor unit performs a heating operation, one of the connection ports (second port 8b) is closed, and two of the connection ports (first port 8a and third port 8c) are open. .

  And when an indoor unit carries out air_cooling | cooling operation, since a 1st connection piping (6) becomes a low pressure and a 2nd connection piping (7) becomes a high pressure, a refrigerant | coolant of the connection ports of a three-way selector valve (8) One connection port (first port 8a) side connection piping is high pressure, the other connection port (second port 8b) side connection piping is low pressure, and another connection port (third port 8c) side connection The piping is in a low pressure state. Further, during cooling operation, the refrigerant is controlled by the amount of superheat at the outlet of the indoor heat exchanger (5), and the first connection pipe (6b, 6c, 6d) on the indoor unit side is in a low-pressure gas state. Refrigerant is flowing.

  When the indoor unit performs heating operation, the refrigerant has a low pressure in the first connection pipe (6) and a high pressure in the second connection pipe (7). One connection port (first port 8a) side connection piping is high pressure, the other connection port (second port 8b) side connection piping is low pressure, and another connection port (third port 8c) side connection The piping is in a high pressure state. Further, during heating operation, the refrigerant is controlled by the outlet subcooling amount of the indoor heat exchanger (5), and the first connection pipes (6b, 6c, 6d) on the indoor unit side are in a high-temperature and high-pressure gas state. The refrigerant is flowing, and high-temperature and high-pressure liquid refrigerant exists in the indoor heat exchanger (5) and the connection pipe from the indoor heat exchanger (5) to the first flow control device (9).

  Therefore, when switching the operation of the connected indoor unit from the heating operation to the cooling operation, the high-temperature high-pressure gas refrigerant and the high-temperature high-pressure liquid refrigerant that have flowed during the heating pass through the three-way switching valve (8) and are in a low-pressure state. Will flow into the first connection pipe (6). When the operation of the connected indoor unit is switched from the heating operation to the cooling operation, the three-way switching valve (8) generates a refrigerant flow sound due to the balance between the high pressure and the low pressure of the refrigerant passing through the three-way switching valve (8). In particular, the flow noise of the high-temperature high-pressure liquid refrigerant is increased.

  Therefore, there is an air conditioner that uses an electromagnetic valve (electromagnetic on-off valve) instead of the three-way switching valve (8) (see, for example, Patent Document 2). In the air conditioner described in Patent Document 2, the second solenoid valve (8b) is used for heating, the first solenoid valve (8a), and the third solenoid valve (8c) with an orifice function is used for cooling. In use, when switching to the cooling operation, in order to reduce the flow noise of the high-temperature and high-pressure liquid refrigerant, the refrigerant was allowed to flow stepwise through the first and third solenoid valves. Moreover, in the air conditioning apparatus described in Patent Document 2, the refrigerant flow is reduced by reducing the opening diameter of the flow control device, by pulse-controlling the flow control device, or by reducing the opening diameter of the third electromagnetic valve. The sound was reduced.

  There is another air conditioner that uses a solenoid valve (electromagnetic on-off valve) instead of the three-way switching valve (8) so as to be compact (see FIG. 6). In this air conditioner, the second electromagnetic valve b is used for heating, and the first electromagnetic valve a, the third electromagnetic valve c, and the orifice d are used for cooling. That is, in the air conditioner shown in FIG. 6, in order to reduce the flow noise of the high-temperature high-pressure liquid refrigerant when switching to the cooling operation, the orifice d, the third electromagnetic valve c, and the first electromagnetic valve a are stepped. The refrigerant was allowed to flow. In addition, in FIG. 6, the same code | symbol is attached | subjected to what is corresponded to the air conditioning apparatus which concerns on embodiment of this invention.

Japanese Patent No. 4350836 (Embodiment 1, FIG. 1, etc.) Japanese Patent Laid-Open No. 09-0428804 (FIG. 1 etc.)

  According to the air conditioning apparatus described in Patent Document 2 and FIG. 6, since three electromagnetic valves are required for one indoor unit, the number of indoor units × 3 electromagnetic valves is provided at the branching unit. There must be. In order to reduce the refrigerant flow noise, pressure equalization is required, but fine control of the flow rate is not possible by control with a solenoid valve. Therefore, regardless of the pressure state of the refrigerant flowing in from the connection pipe on the indoor unit side, it is necessary to equalize the refrigerant over a certain period of time, and not only can the refrigerant flow noise be sufficiently reduced, but also the startup time of the indoor unit. It was also supposed to be unable to optimize.

  The present invention has been made to solve the above-described problems, and provides an air conditioner that can improve comfort by reducing the startup time of an indoor unit while maintaining quietness. The purpose is to do.

An air conditioner according to the present invention includes a heat source unit having a compressor, a switching valve, and a heat source unit side heat exchanger, and a plurality of indoor units each having an indoor side heat exchanger and a first flow control device. An air conditioner that is connected via a first connection pipe and a second connection pipe, supplies a refrigerant from the heat source unit to the plurality of indoor units, and performs cooling and / or heating operation. A first branch part that switches and connects one of the refrigerant inlets and outlets of each indoor-side heat exchanger of the indoor unit to the first connection pipe or the second connection pipe, and one side is the second connection pipe And a second branch portion connected to the other refrigerant inlet / outlet of the indoor heat exchanger of each of the plurality of indoor units via the first flow rate control device. And the first branch portion includes the first branch portion. A branch flow rate control device provided in each of the pipes branched into a plurality from the connecting pipe side and connected to the indoor heat exchangers, the branch flow rate control devices, and the indoor heat An electromagnetic valve provided in each pipe branched from the pipe connecting the exchanger, and the branch side flow control device is based on the state of the refrigerant flowing into the branch side flow control device The opening degree is controlled , and the state of the refrigerant flowing into the branch side flow control device is determined from the outlet subcool value of the indoor heat exchanger that is performing the heating operation before switching to the cooling operation. The
An air conditioner according to the present invention includes a heat source machine having a compressor, a switching valve, and a heat source machine side heat exchanger, and a plurality of indoor units each having an indoor side heat exchanger and a first flow rate control device. Are connected via a first connection pipe and a second connection pipe, and supply a refrigerant from the heat source unit to the plurality of indoor units to perform cooling and / or heating operation, A first branch section that switches and connects one of the refrigerant inlets and outlets of the indoor heat exchanger of each of the plurality of indoor units to the first connection pipe or the second connection pipe; A second pipe connected to the connection pipe, the other side of which is branched into a plurality and connected to the other refrigerant inlet / outlet of each of the indoor heat exchangers of the plurality of indoor units via the first flow rate controller; A branch part, and the first branch part includes A branch side flow control device provided in each of the pipes branched into a plurality from one connection pipe side and connected to each of the indoor heat exchangers, and each of the branch side flow control devices and each of the chambers. A solenoid valve provided in each pipe branched from the pipe connecting the inner heat exchanger, and the branch-side flow control device is in a state of the refrigerant flowing into the branch-side flow control device And the state of the refrigerant flowing into the branch side flow control device is determined by predicting the inlet / outlet differential pressure of the branch side flow control device .

  According to the air conditioner according to the present invention, the appropriate opening degree of the branch side flow control device can be determined from the state of the refrigerant flowing into the branch side flow control device, and the plurality of solenoid valves are stepped in a certain time step by step. Compared with the case of switching, the refrigerant flow noise can be reduced and the indoor unit start-up time can be shortened, and the comfort can be improved.

It is a whole lineblock diagram centering on a refrigerant system of an air harmony device concerning an embodiment of the invention. The operation state at the time of air-conditioning operation (only air-conditioning operation) of the air harmony device concerning an embodiment of the invention is shown. The operation state at the time of the air-conditioning operation (only heating operation) of the air conditioning apparatus which concerns on embodiment of this invention is shown. The operation state at the time of the air conditioning operation (cooling main operation) of the air conditioner according to the embodiment of the present invention is shown. The operation state at the time of the air conditioning operation (heating main operation) of the air conditioner according to the embodiment of the present invention is shown. It is a circuit block diagram which shows schematically an example of a structure of the relay machine of the conventional air conditioning apparatus. It is a flowchart which shows an example of the process flow of the opening degree control at the time of the refrigerant | coolant sound suppression driving | operation of the 4th flow control apparatus 55 of the air conditioning apparatus which concerns on embodiment of this invention. It is a flowchart which shows an example of the flow of a process of the necessity determination of the refrigerant | coolant sound suppression driving | operation of the air conditioning apparatus which concerns on embodiment of this invention. It is a flowchart which shows an example of the flow of a process of the necessity determination of the refrigerant | coolant sound suppression driving | operation of the air conditioning apparatus which concerns on embodiment of this invention. It is a flowchart which shows an example of the flow of a process of the necessity determination of the refrigerant | coolant sound suppression driving | operation of the air conditioning apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, in the following drawings including FIG. 1, the same reference numerals denote the same or equivalent parts, and this is common throughout the entire specification. Furthermore, the forms of the constituent elements shown in the entire specification are merely examples, and are not limited to these descriptions.

  FIG. 1 is an overall configuration diagram centering on a refrigerant system of an air-conditioning apparatus 100 according to an embodiment of the present invention. 2 to 5 show the operating state of the air conditioner 100 during the cooling and heating operation. 2 is an operation state diagram of only cooling operation, FIG. 3 is an operation state diagram of only heating operation, and FIG. 4 is an operation state diagram of cooling main operation in which the cooling operation capacity of the simultaneous cooling and heating operation is larger than the heating operation capacity. FIG. 5 shows an operation state diagram of the heating main operation in which the heating operation capacity of the simultaneous cooling and heating operation is larger than the cooling operation capacity. In this embodiment, a case where three indoor units are connected to one heat source unit will be described, but the same applies to the case where two or more indoor units are connected.

  As shown in FIG. 1, an air conditioner 100 is configured by connecting a heat source unit A, indoor units B, C, and D (hereinafter simply referred to as indoor units unless otherwise noted) and a relay unit E. Has been. The heat source unit A has a function of supplying hot or cold heat to the indoor unit. As will be described later, the indoor units are connected in parallel to each other and have the same configuration. The indoor unit has a function of executing air conditioning of an air-conditioning target space such as a room by using heat or cold supplied from the heat source unit A. The relay unit E is interposed between the heat source unit A and the indoor unit, and has a function of switching the flow of the refrigerant supplied from the heat source unit A in response to a request from the indoor unit.

  The heat source machine A includes a compressor 1 having a variable capacity, a four-way switching valve 2 that switches the refrigerant flow direction in the heat source machine A, a heat source machine-side heat exchanger 3 that functions as an evaporator or a condenser (heat radiator), and a four-way switching valve. 2, an accumulator 4 connected to the suction side of the compressor 1, a heat source side blower 20 with variable air flow for blowing air to the heat source side heat exchanger 3, and heat source side switching for restricting the refrigerant flow direction A valve 40 is provided. And the heat source machine A is comprised by these. The four-way switching valve 2 corresponds to the “switching valve” of the present invention. In addition, you may comprise a "switching valve" not combining a four-way switching valve but combining a two-way valve, a three-way valve, etc.

  The indoor unit is an indoor heat exchanger 5 that functions as a condenser (radiator) or an evaporator, the amount of superheat on the outlet side of the indoor heat exchanger 5 during cooling, and the indoor heat exchanger 5 during heating. The first flow rate control device 9 controlled by the subcooling amount on the outlet side is provided. And these constitute an indoor unit.

  The relay E includes a first branching unit 10, a second flow rate control device 13, a second branching unit 11, a gas-liquid separator 12, a heat exchange unit (a first heat exchange unit 19, a second heat exchange unit). Part 16) and a third flow rate control device 15 are incorporated. And the repeater E is comprised by these.

The four-way switching valve 2 of the heat source machine A and the relay machine E are connected by a thick first connection pipe 6.
The indoor unit heat exchanger 5 and the relay unit E of the indoor unit are connected to each of the first connection pipes 6b, 6c, and 6d on the indoor unit side corresponding to the first connection pipe 6.
The heat source machine side heat exchanger 3 of the heat source machine A and the relay machine E are connected by a second connection pipe 7 that is narrower than the first connection pipe 6.
The indoor side heat exchanger 5 and the relay unit E of the indoor unit are connected via the first connection pipe 6 and the second connection pipes 7b and 7c on the indoor unit side corresponding to the second connection pipe 7 are connected. , 7d.

The 1st branch part 10 has the function to connect the 1st connection piping 6b, 6c, 6d by the side of an indoor unit, and the 1st connection piping 6 or the 2nd connection piping 7 side so that switching is possible.
The first branch portion 10 includes a fourth flow rate control device (branch side flow rate control device) connected to the first connection piping 6b, 6c, 6d on the indoor unit side and the first connection piping 6. ) 55 and the solenoid valve 31 as a valve device connected to the first connection piping 6b, 6c, 6d on the indoor unit side and the first connection piping 6 side is mounted.

The second branch portion 11 has a function of switching the connection between the second connection pipes 7b, 7c and 7d on the indoor unit side and the second connection pipe 7 according to the flow of the refrigerant.
The second branch portion 11 includes a first check valve 50 (first check valves 50b, 50c, and 50d), which will be described later, and a second check valve 52 (second check valve, which will be described later). 52b, 52c, 52d) are mounted.

The gas-liquid separator 12 is provided in the middle of the second connection pipe 7, the gas phase portion is connected to the electromagnetic valve 31 of the first branch portion 10, and the liquid phase portion is connected to the second branch portion 11. It is connected.
The second flow rate control device 13 is provided between the gas-liquid separation device 12 of the second connection pipe 7 and the second branch portion 11, and is configured by, for example, an electric expansion valve that can be opened and closed. Yes.
Note that the second branch portion 11 and the first connection pipe 6 are connected by a first bypass pipe 14.

The 3rd flow control device 15 is provided in the middle of the 1st bypass piping 14, and is constituted by an electric expansion valve etc. which can be opened and closed, for example.
The second heat exchange unit 16 is provided downstream of the third flow rate control device 15 of the first bypass pipe 14 and between the second connection pipe 7 and a portion downstream of the second flow rate control device 13. In each case, heat exchange is performed.
The first heat exchanging part 19 is provided downstream of the second heat exchanging part 16 of the first bypass pipe 14, and between the part of the second connecting pipe 7 upstream of the second flow rate control device 13. In each case, heat exchange is performed.

The first check valves 50b, 50c, and 50d are provided in the middle of the second connection pipes 7b, 7c, and 7d on the indoor unit side of the second branch portion 11, respectively. Refrigerant flow is allowed only to the second connection pipes 7b, 7c, 7d on the indoor unit side.
The downstream portions of the first check valves 50b, 50c, 50d of the second connection pipes 7b, 7c, 7d on the indoor unit side and the downstream of the second flow rate control device 13 of the second connection pipe 7, and The second bypass pipe 51 is connected to the upstream pipe section of the second heat exchange section 16. And the pipes connected to the second connection pipes 7b, 7c, 7d on the indoor unit side in the second bypass pipe 51 and the pipes connected to the second connection pipe 7 in the second bypass pipe 51 are in the middle. Join.

The second check valves 52 b, 52 c, 52 d are connected to the second connection pipes 7 b, 7 c, 7 d on the indoor unit side in the middle of the second bypass pipe 51. 2 is provided upstream of the portion joining the pipe connected to the connection pipe 7 and permits the refrigerant to flow only from the second connection pipe 7b, 7c, 7d on the indoor unit side to the second connection pipe 7. .
In addition, it reaches the first flow control device 9 from the second connection pipe 7 via the second connection pipes 7b, 7c, 7d on the indoor unit side where the first check valves 50b, 50c, 50d are provided. The flow path constitutes a first refrigerant flow path, and second connection pipes 7b, 7c, 7d and second check valves 52b, 52c, 52d on the indoor unit side are provided from the first flow control device 9. The flow path reaching the second connection pipe 7 via the second bypass pipe 51 constitutes the second refrigerant flow path.

The third check valve 32 is provided in the middle of the pipe connecting the heat source apparatus side heat exchanger 3 and the second connection pipe 7, and only from the heat source apparatus side heat exchanger 3 to the second connection pipe 7. Allow refrigerant flow.
The fourth check valve 33 is provided in the middle of the pipe connecting the four-way switching valve 2 of the heat source apparatus A and the first connection pipe 6, and the refrigerant flows only from the first connection pipe 6 to the four-way switching valve 2. Is acceptable.
The fifth check valve 34 is provided in the middle of the pipe connecting the four-way switching valve 2 and the second connection pipe 7 of the heat source machine A, and the refrigerant flows only from the four-way switching valve 2 to the second connection pipe 7. Is acceptable.
The sixth check valve 35 is provided in the middle of the pipe connecting the heat source apparatus side heat exchanger 3 and the first connection pipe 6, and only from the first connection pipe 6 to the heat source apparatus side heat exchanger 3. Allow refrigerant flow.
The third check valve 32, the fourth check valve 33, the fifth check valve 34, and the sixth check valve 35 constitute a heat source machine side switching valve 40.

The relay machine E is provided with a first pressure detecting means 25, a second pressure detecting means 26, and a third pressure detecting means 56.
The first pressure detection means 25 is provided between the first branch portion 10 of the second connection pipe 7 and the second flow rate control device 13.
The second pressure detection means 26 is provided between the second flow control device 13 and the first flow control device 9.
The third pressure detection means 56 is provided at a connection position between the first connection pipe 6 and the first bypass pipe 14.

The indoor unit is provided with first temperature detection means 53 and second temperature detection means 54.
The 1st temperature detection means 53 is provided in the 1st branch part 10 side of an indoor unit.
The 2nd temperature detection means 54 is provided in the 2nd branch part 11 side of an indoor unit.
That is, the first temperature detection means 53 and the second temperature detection means 54 are provided at both ends of the indoor heat exchanger 5 and connected to the first flow control device 9 side is the second temperature detection. The first temperature detecting means 53 is connected to the means 54 and the other end.

  The heat source machine side heat exchanger 3 includes a first heat source machine side heat exchanger 41 and a second heat source machine side heat exchanger 42, a heat source machine side bypass passage 43, a first electromagnetic on-off valve 44, a second The electromagnetic on-off valve 45, the third electromagnetic on-off valve 46, the fourth electromagnetic on-off valve 47, and the fifth electromagnetic on-off valve 48 are configured. The heat source device side heat exchanger 3 is provided with a heat source device side blower 20 that controls the heat exchange capacity of the heat source device side heat exchanger 3.

The first heat source device side heat exchanger 41 and the second heat source device side heat exchanger 42 have the same heat transfer area and are connected in parallel to each other.
The heat source unit side bypass passage 43 is connected in parallel to the first heat source unit side heat exchanger 41 and the second heat source unit side heat exchanger 42.
The first electromagnetic on-off valve 44 is provided at one end of the first heat source unit side heat exchanger 41 on the side connected to the four-way switching valve 2.
The second electromagnetic opening / closing valve 45 is provided at the other end of the first heat source unit side heat exchanger 41.
The third electromagnetic opening / closing valve 46 is provided at one end of the second heat source unit side heat exchanger 42 on the side connected to the four-way switching valve 2.
The fourth electromagnetic opening / closing valve 47 is provided at the other end of the second heat source unit side heat exchanger 42.
The fifth electromagnetic opening / closing valve 48 is provided in the middle of the heat source unit side bypass path 43.

  The heat source machine A is provided with fourth pressure detection means 18. The fourth pressure detection means 18 is provided in the middle of the pipe connecting the four-way switching valve 2 and the discharge part of the compressor 1.

  The air conditioner 100 has a control device 70. The control device 70 performs overall control of the entire system of the air conditioner 100. Specifically, the control device 70 controls the drive frequency of the compressor 1, the number of rotations of the blower provided in the heat source fan blower 20 and the indoor heat exchanger 5, switching of the four-way switching valve 2, and switching of each solenoid valve. Controls opening and closing, opening of each throttle device, and the like. That is, the control device 70 is based on the detection information from the temperature detection means and pressure detection means described above and instructions from the remote controller (not shown), and the actuators (compressor 1, four-way switching valve 2, solenoid valves (first solenoid valve)). 1 electromagnetic on-off valve 44 to fifth electromagnetic on-off valve 48, solenoid valve 31), each throttle device (first flow control device 9, second flow control device 13, third flow control device 15, fourth Driving components such as the flow rate control device 55).

It is not limited in particular the type of refrigerant to be filled in the air conditioner 100, for example, carbon dioxide (CO ₂₎ and hydrocarbons, natural refrigerant such as helium, HFC410A and HFC407C (HFC of R32 / R125 / R134a Is a non-azeotropic refrigerant mixed in a ratio of 23/25/52 wt%), an alternative refrigerant not containing chlorine such as HFC404A, or a fluorocarbon refrigerant such as R22 or R134a used in existing products May be used.
Although the case where the heat source apparatus side heat exchanger 3 and the indoor side heat exchanger 5 exchange heat between the refrigerant and the air has been described as an example, a heat medium other than the refrigerant and the air, for example, water or brine It is also possible to perform heat exchange with the above.

  Moreover, in this Embodiment, although the case where the one heat source apparatus A is mounted in the air conditioning apparatus 100 is shown as an example, it is not limited to this, Two or more heat source apparatuses A are mounted. It may be. Furthermore, although the case where three indoor units are mounted is shown as an example, the present invention is not limited to this, and four or more indoor units may be mounted. The control device 70 may be mounted on any one of the heat source unit A, the indoor unit, and the relay unit E, or may be mounted on all of them. Further, the control device 70 may be mounted separately from the heat source unit A, the indoor unit, and the relay unit E. When a plurality of control devices 70 are configured, they may be connected so that they can communicate with each other wirelessly or by wire.

Next, the operation of the air conditioning apparatus 100 will be described.
[Cooling operation]
First, the operation state of only the cooling operation will be described with reference to FIG. In FIG. 2, the state which is performing air_conditionaing | cooling operation | movement with all the indoor units B, C, and D is shown as an example.

  As shown in FIG. 2, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 2, and air blown by the heat source machine side blower 20 whose air flow rate is variable in the heat source machine side heat exchanger 3. It is condensed and liquefied by heat exchange. The refrigerant then passes through the third check valve 32, the second connection pipe 7, the gas-liquid separation device 12, and the second flow rate control device 13 in this order, and further to the second branch portion 11 and the indoor unit side. It passes through the second connection pipes 7b, 7c, 7d and flows into the indoor units B, C, D.

  Then, the refrigerant flowing into the indoor units B, C, and D is decompressed to a low pressure by the first flow rate control device 9 that is controlled by the superheat amount at the outlet of each indoor heat exchanger 5. The decompressed refrigerant flows into the indoor heat exchanger 5, exchanges heat with indoor air in the indoor heat exchanger 5, evaporates and gasifies, and cools the room. And the refrigerant | coolant used as this gas state is the 1st connection piping 6b, 6c, 6d by the side of an indoor unit, the 4th flow control apparatus 55 of the 1st branch part 10, the 1st connection piping 6, 4th. The check valve 33, the four-way switching valve 2 of the heat source unit, and the accumulator 4 are sucked into the compressor 1. In this way, the circulation cycle is configured and the cooling operation is performed.

At this time, each solenoid valve 31 is controlled to be closed. Since the first connection pipe 6 is at a low pressure and the second connection pipe 7 is at a high pressure, the refrigerant inevitably flows to the third check valve 32 and the fourth check valve 33.
Further, the opening degree of the fourth flow control device 55 is controlled based on the state of the refrigerant obtained by the detection information from the third pressure detection means 56.

  In this circulation cycle, a part of the refrigerant that has passed through the second flow rate control device 13 enters the first bypass pipe 14. Then, after the pressure is reduced to a low pressure by the third flow control device 15, the refrigerant that has passed through the second flow control device 13 in the second heat exchange unit 16 (the refrigerant before branching to the first bypass pipe 14). Evaporate by exchanging heat with each other. Further, the first heat exchange unit 19 evaporates by exchanging heat with the refrigerant before flowing into the second flow rate control device 13. The evaporated refrigerant enters the first connection pipe 6 and the fourth check valve 33 and is sucked into the compressor 1 through the four-way switching valve 2 of the heat source unit and the accumulator 4.

  On the other hand, in the first heat exchange unit 19 and the second heat exchange unit 16, heat exchange is performed with the refrigerant that enters the first bypass pipe 14 and is decompressed to a low pressure by the third flow control device 15. The cooled and sufficiently subcooled refrigerant flows through the first check valves 50b, 50c, and 50d of the second branch portion 11 into the indoor units B, C, and D that are to be cooled. Here, the capacity of the compressor 1 having a variable capacity and the air flow rate of the heat source unit side fan 20 are adjusted so that the evaporation temperature of the indoor unit and the condensation temperature of the heat source unit side heat exchanger 3 become a predetermined target temperature. In each indoor unit, the target cooling capacity can be obtained. The condensation temperature of the heat source device side heat exchanger 3 is obtained as the saturation temperature of the pressure detected by the fourth pressure detection means 18.

[Heating operation]
Next, the operation state of only the heating operation will be described with reference to FIG. FIG. 3 shows an example in which the heating operation is performed for all of the indoor units B, C, and D.

  As shown in FIG. 3, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 2, the fifth check valve 34, the second connection pipe 7, the gas-liquid separator 12, the first It flows into the indoor units B, C, D through the solenoid valve 31 of the branching section 10 and the first connection pipes 6b, 6c, 6d on the indoor unit side in this order. The refrigerant that has flowed into the indoor units B, C, and D exchanges heat with room air to be condensed and liquefied to heat the room. The refrigerant in this state is controlled by the outlet subcooling amount of each indoor heat exchanger 5 and passes through the first flow rate control device 9.

  The refrigerant that has passed through the first flow control device 9 flows into the second branch portion 11 from the second connection pipes 7b, 7c, 7d on the indoor unit side, and passes through the second check valves 52b, 52c, 52d. Merge after passing. The refrigerant merged at the second branch portion 11 is further guided between the second flow control device 13 and the second heat exchange portion 16 in the middle of the second connection pipe 7, and the third flow control device 15. Pass through. In addition, the refrigerant is decompressed to a low pressure gas-liquid two-phase by the first flow control device 9 or the third flow control device 15 here.

  Then, the refrigerant depressurized to a low pressure flows into the sixth check valve 35 of the heat source unit A and the heat source unit side heat exchanger 3 through the first connection pipe 6, where the air flow rate variable heat source unit side It evaporates by exchanging heat with the air blown by the blower 20. The refrigerant that has been evaporated and turned into a gas state is sucked into the compressor 1 through the four-way switching valve 2 and the accumulator 4. In this way, a circulation cycle is configured and heating operation is performed.

At this time, each solenoid valve 31 is controlled to be opened.
The fourth flow control device 55 is closed.

  In this circulation cycle, since the first connection pipe 6 is low pressure and the second connection pipe 7 is high pressure, the refrigerant inevitably has a fifth check valve 34 and a sixth check valve 35. Circulate to The first check valves 50b, 50c, and 50d are closed because the second connection pipes 7b, 7c, and 7d on the indoor unit side have a higher pressure than the second connection pipe 7. Here, the capacity of the compressor 1 having a variable capacity and the amount of air blown from the heat source side blower 20 are adjusted so that the condensation temperature of the indoor unit and the evaporation temperature of the heat source side heat exchanger 3 become a predetermined target temperature. In each indoor unit, the target heating capacity can be obtained.

[Cooling operation]
Next, the operation state of the cooling main operation will be described with reference to FIG. FIG. 4 shows an example of a cooling main operation when there is a cooling request from the indoor units B and C and a heating request from the indoor unit D.

  As shown in FIG. 4, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 flows into the heat source machine side heat exchanger 3 through the four-way switching valve 2, and is blown by the heat source machine side blower 20 with variable air flow here. Heat-exchanged with the air to be brought into a two-phase high temperature and high pressure state.

  Here, the capacity | capacitance of the compressor 1 with variable capacity | capacitance and the ventilation volume of the heat source side air blower 20 are adjusted so that the evaporation temperature and condensing temperature of an indoor unit may become predetermined target temperature. And the 1st electromagnetic on-off valve 44 of the both ends of the 1st heat source machine side heat exchanger 41 and the 2nd heat source machine side heat exchanger 42, the 2nd electromagnetic on-off valve 45, the 3rd electromagnetic on-off valve 46, The fourth electromagnetic switching valve 47 is opened and closed to adjust the heat transfer area. And the flow rate of the refrigerant | coolant which distribute | circulates the 1st heat source machine side heat exchanger 41 and the 2nd heat source machine side heat exchanger 42 is adjusted by opening and closing the 5th electromagnetic on-off valve 48 of the heat source machine side bypass path 43. By doing in this way, the heat source unit side heat exchanger 3 can obtain an arbitrary amount of heat exchange, and each indoor unit can obtain a target heating capacity or cooling capacity.

Thereafter, the two-phase high-temperature and high-pressure refrigerant passes through the third check valve 32 and the second connection pipe 7 and is sent to the gas-liquid separator 12 of the relay E, where the gas-state refrigerant and the liquid-state refrigerant are sent. And separated.
Then, the gaseous refrigerant separated by the gas-liquid separator 12 flows into the indoor unit D to be heated through the electromagnetic valve 31 of the first branch portion 10 and the first connection pipe 6d on the indoor unit side in this order. Then, the indoor heat exchanger 5 exchanges heat with room air to condense and heat the room. Furthermore, the refrigerant that has flowed out of the indoor heat exchanger 5 passes through the first flow rate control device 9 controlled by the outlet subcooling amount of the indoor heat exchanger 5 of the indoor unit D, and is slightly depressurized to be the second branch. Flows into the section 11. This refrigerant flows through the second bypass pipe 51 including the second check valve 52d into the downstream portion of the second flow control device 13 of the second connection pipe 7.

  On the other hand, the liquid refrigerant separated by the gas-liquid separator 12 passes through the second flow rate controller 13 controlled by the detected pressure of the first pressure detector 25 and the detected pressure of the second pressure detector 26. The refrigerant passes through the indoor unit D to be heated. Thereafter, it flows into the second heat exchange unit 16 and is cooled by the second heat exchange unit 16.

  Then, a part of the refrigerant cooled by the second heat exchange unit 16 passes through the first check valves 50b and 50c and the second connection pipes 7b and 7c on the indoor unit side to be cooled. Enter B and C. The refrigerant that has flowed into the indoor units B and C enters the first flow control device 9 controlled by the superheat amount at the outlet of the indoor heat exchanger 5 of each of the indoor units B and C, and is then depressurized. It enters into the heat exchanger 5 and exchanges heat to evaporate into a gas state to cool the room. Thereafter, it flows into the first connection pipe 6 via the fourth flow rate control device 55.

  On the other hand, the remainder of the refrigerant cooled by the second heat exchange unit 16 is controlled so that the pressure difference between the detected pressure of the first pressure detecting means 25 and the detected pressure of the second pressure detecting means 26 falls within a predetermined range. The third flow control device 15 is passed through. Then, after heat-exchanging and evaporating in the 2nd heat exchange part 16 and the 1st heat exchange part 19, it flows into the thick 1st connection piping 6, and merges with the refrigerant | coolant which passed indoor unit B, C. The refrigerant merged in the first connection pipe 6 is sucked into the compressor 1 through the fourth check valve 33, the four-way switching valve 2, and the accumulator 4 of the heat source machine A. In this way, the circulation cycle is configured and the cooling main operation is performed.

At this time, the solenoid valve 31 connected to the indoor units B and C is controlled to be closed, and the solenoid valve 31 connected to the indoor unit D is controlled to be opened.
Further, the fourth flow rate control device 55 connected to the indoor units B and C is opened, and the fourth flow rate control device 55 connected to the indoor unit D is closed.

In addition, since the first connection pipe 6 is low pressure and the second connection pipe 7 is high pressure, the refrigerant inevitably flows into the third check valve 32 and the fourth check valve 33.
Furthermore, since the second connecting pipes 7b and 7c on the indoor unit side are lower in pressure than the second connecting pipe 7, the second check valves 52b and 52c are closed.
Moreover, since the pressure of the second connection pipe 7d on the indoor unit side is higher than that of the second connection pipe 7, the first check valve 50d is closed.
By the first check valve 50 and the second check valve 52, the cooling request is made in a state where the refrigerant that has passed through the indoor unit D that requires heating does not pass through the second heat exchanging unit 16 and does not have sufficient subcooling. Is prevented from flowing into the indoor units B and C.

[Heating-based operation]
Next, the operation state of the heating main operation will be described with reference to FIG. FIG. 5 shows an example of a heating main operation when there is a heating request from the indoor units B and C and a cooling request from the indoor unit D.

  The high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is sent to the relay machine E through the four-way switching valve 2, the fifth check valve 34, and the second connection pipe 7, as shown in FIG. It passes through the liquid separator 12. The refrigerant that has passed through the gas-liquid separator 12 passes through the electromagnetic valve 31 of the first branching section 10 and the first connection pipes 6b and 6c on the indoor unit side, and then flows into the indoor units B and C to be heated. Then, heat is exchanged with room air in the indoor heat exchanger 5 to be condensed and heated to heat the room. The condensed and liquefied refrigerant is controlled by the outlet subcooling amount of each indoor side heat exchanger 5 of the indoor units C and D, passes through the first flow control device 9, is slightly decompressed, and flows into the second branch portion 11. To do.

  The refrigerant that has flowed into the second branch section 11 joins the second connection pipe 7 through the second bypass pipe including the second check valves 52b and 52c, and is cooled by the second heat exchange section 16. Is done. A part of the refrigerant cooled by the second heat exchange unit 16 passes through the first check valve 50d and the second connection pipe 7d on the indoor unit side and enters the indoor unit D to be cooled. The refrigerant that has entered the indoor unit D enters the first flow rate control device 9 controlled by the outlet superheat amount of the indoor side heat exchanger 5 and is depressurized, and then enters the indoor side heat exchanger 5 and heats it. It exchanges and evaporates, becomes a gas state, cools the room, and flows into the first connection pipe 6 via the fourth flow rate control device 55.

  On the other hand, the remainder of the refrigerant cooled by the second heat exchange unit 16 is set so that the pressure difference between the detection pressure of the first pressure detection unit 25 and the detection pressure of the second pressure detection unit 26 falls within a predetermined range. It passes through a third flow control device 15 to be controlled. The refrigerant that has passed through the third flow control device 15 is evaporated by exchanging heat with the refrigerant that has come out of the heating indoor unit in the second heat exchange unit 16. Thereafter, the refrigerant merges with the refrigerant that has passed through the indoor unit D to be cooled, and passes through the thick first connection pipe 6 to the sixth check valve 35 of the heat source unit A and the heat source unit side heat exchanger 3. Inflow. The refrigerant that has flowed into the heat source apparatus side heat exchanger 3 exchanges heat with the air blown by the heat source apparatus side blower 20 whose air flow rate is variable, and evaporates into a gas state.

  Here, the capacity of the compressor 1 and the heat source machine side blower whose capacity is variable so that the evaporation temperature of the indoor unit D requiring cooling and the condensation temperature of the indoor units B and C requiring heating become predetermined target temperatures. 20 air flow rate is adjusted. And the 1st electromagnetic on-off valve 44 of the both ends of the 1st heat source machine side heat exchanger 41 and the 2nd heat source machine side heat exchanger 42, the 2nd electromagnetic on-off valve 45, the 3rd electromagnetic on-off valve 46, The fourth electromagnetic switching valve 47 is opened and closed to adjust the heat transfer area. And the flow rate of the refrigerant | coolant which distribute | circulates the 1st heat source machine side heat exchanger 41 and the 2nd heat source machine side heat exchanger 42 is adjusted by opening and closing the 5th electromagnetic on-off valve 48 of the heat source machine side bypass path 43. By doing in this way, the heat source unit side heat exchanger 3 can obtain an arbitrary amount of heat exchange, and each indoor unit can obtain a target heating capacity or cooling capacity. The refrigerant is sucked into the compressor 1 through the four-way switching valve 2 and the accumulator 4 of the heat source machine A. In this way, the circulation cycle is configured and the heating main operation is performed.

  At this time, the solenoid valve 31 connected to the indoor units B and C is controlled to open, and the solenoid valve 31 connected to the indoor unit D is controlled to close. Further, the fourth flow rate control device 55 connected to the indoor units B and C is closed, and the fourth flow rate control device 55 connected to the indoor unit D is opened.

The refrigerant inevitably flows to the fifth check valve 34 and the sixth check valve 35 because the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure. At this time, the second flow rate control device 13 is closed.
Furthermore, since the second connecting pipes 7b and 7c on the indoor unit side have higher pressure than the second connecting pipe 7, the first check valves 50b and 50c are closed.
Moreover, since the pressure of the second connection pipe 7d on the indoor unit side is lower than that of the second connection pipe 7, the second check valve 52d is closed.
The first check valve 50 and the second check valve 52 allow the refrigerant that has passed through the heating indoor units B and C not to pass through the second heat exchange unit 16 to be sufficiently subcooled, so that the cooling indoor unit D is prevented from flowing into D.

[Opening Control of Fourth Flow Control Device 55]
The opening degree of the fourth flow control device 55 is controlled based on the state of the refrigerant obtained from the detection information from the third pressure detection means 56. That is, the control device 70 determines the state of the refrigerant flowing into the fourth flow control device 55 from the pressure information detected by the third pressure detection means 56, and based on the determination result, the fourth flow control device 55. The degree of opening is properly maintained.
In addition, although the case where the state of the refrigerant flowing into the fourth flow control device 55 is determined based on the detection information in the third pressure detection unit 56 is shown as an example, the present invention is not limited to this and will be described below. As described above, information from other detection means may be used.

For example, the fourth flow control device 55 is predicted by predicting the differential pressure value at the inlet / outlet of the fourth flow control device 55 based on the information from the third pressure detection device 56 and the first temperature detection device 53. You may make it judge the state of the refrigerant | coolant which flows in into (FIG. 8).
Further, the state of the refrigerant flowing into the fourth flow control device 55 may be determined from the outlet subcool value of the indoor heat exchanger 5 performing the heating operation before switching to the cooling operation (see FIG. 9). ).
Furthermore, the state of the refrigerant flowing into the fourth flow control device 55 may be determined by predicting the refrigerant state of the indoor unit that is stopped from the elapsed time from the heating stop (see FIG. 10). .
Furthermore, the state of the refrigerant flowing into the fourth flow control device 55 may be determined by combining these.

  FIG. 7 is a flowchart illustrating an example of a flow of opening degree control processing during the refrigerant noise suppression operation of the fourth flow control device 55. 8 to 10 are flowcharts illustrating an example of a processing flow for determining whether or not the refrigerant noise suppression operation is necessary. Based on FIGS. 7-10, the refrigerant | coolant sound suppression driving | operation of the 4th flow control apparatus 55 is demonstrated. 7 to 10 is the control device 70.

First, based on FIG. 7, the flow of processing during the refrigerant sound characteristic operation will be described.
When starting the refrigerant noise suppression operation (step S101), the control device 70 controls the opening of the fourth flow rate control device 55 to be slightly opened (step S102). Then, the control device 70 determines whether or not the refrigerant sound suppression operation is necessary (step S103). Whether or not the refrigerant noise suppression operation is necessary is determined according to flowcharts shown in FIGS.

  If it is determined that the refrigerant noise suppression operation is necessary (step S103; YES), the control device 70 increases the opening of the fourth flow control device 55 (step S104). Next, the control device 70 determines whether or not the opening of the fourth flow control device 55 is the maximum (Max opening) (step S105). On the other hand, when determining that the refrigerant sound suppression operation is unnecessary (step S103; NO), the control device 70 ends the refrigerant noise suppression operation (step S106).

  If it is determined that the opening degree of the fourth flow control device 55 is the maximum (step S105; YES), the control device 70 ends the refrigerant sound suppression operation (step S106). On the other hand, when determining that the opening degree of the fourth flow control device 55 is not the maximum (step S105; NO), the control device 70 reconfirms whether or not the refrigerant noise suppression operation is necessary (step S103).

Next, an example of the processing flow for determining whether or not the refrigerant noise suppression operation is necessary will be described with reference to FIG. In FIG. 8, the necessity of the refrigerant noise suppression operation is determined based on the differential pressure across the fourth flow control device 55.
When the control device 70 determines whether or not the refrigerant sound suppression operation is necessary (reconfirmation) (step S103, step S101a in FIG. 7), the front-rear differential pressure ΔPa of the fourth flow control device 55 is determined in advance. It is determined whether or not ΔP0 or more (step S102a). If ΔPa is equal to or greater than ΔP0 (step S102a; YES), the control device 70 determines that the refrigerant noise suppression operation is necessary (step S104a). On the other hand, if ΔPa is smaller than ΔP0 (step S102a; NO), the refrigerant noise suppression operation is terminated and the normal operation is resumed (step S103a).

  Note that the third pressure detector 56 may be used for the low pressure side pressure of the fourth flow control device 55. As for the pressure on the high pressure side of the fourth flow control device 55, the saturation temperature on the indoor unit side can be estimated from the first temperature detection means 53.

Next, an example of the processing flow for determining whether or not the refrigerant noise suppression operation is necessary will be described with reference to FIG. In FIG. 9, it is determined whether or not the refrigerant noise suppression operation is necessary based on the subcool of the indoor unit during the heating operation.
When the control device 70 determines whether or not the refrigerant sound suppression operation is necessary (reconfirmation) (steps S103 and S101b in FIG. 7), is the subcool SCa of the indoor unit during the heating operation equal to or greater than a predetermined target subcool SC0? It is determined whether or not (step S102b). If SCa is greater than or equal to SC0 (step S102b; YES), control device 70 determines that the refrigerant noise suppression operation is necessary (step S104b). On the other hand, if SCa is smaller than SC0 (step S102b; NO), the refrigerant noise suppression operation is terminated and the normal operation is resumed (step S103b).

  The saturation temperature of the indoor unit during the heating operation can be estimated from the first pressure detection means 25. Further, the subcool value (SC value) can be calculated from the saturation temperature estimated from the second temperature detection means 54 and the first pressure detection means 25.

Next, an example of the processing flow for determining whether or not the refrigerant noise suppression operation is necessary will be described with reference to FIG. In FIG. 10, it is determined whether or not the refrigerant noise suppression operation is necessary based on the elapsed time since the heating operation was stopped.
If it becomes necessity judgment (reconfirmation) of the refrigerant | coolant sound suppression operation (step S103, step S101c of FIG. 7), the control apparatus 70 will be the target elapsed time T0 in which the elapsed time Ta after stopping heating operation is predetermined. It is determined whether or not the above is true (step S102c). If Ta is equal to or greater than T0 (step S102c; YES), the control device 70 determines that the refrigerant noise suppression operation is necessary (step S104c). On the other hand, if Ta is smaller than T0 (step S102c; NO), the refrigerant sound suppression operation is terminated and the normal operation is resumed (step S103c).

  Although the necessity determination of the refrigerant noise suppression operation has been described separately according to the flowcharts shown in FIGS. 8 to 10, the necessity determination of the refrigerant noise suppression operation may be executed by appropriately combining these.

  As described above, according to the air conditioner 100, the opening degree of the fourth flow control device 55 can be maintained in an appropriate state, and therefore, the refrigerant flow noise generated when switching from the heating operation to the cooling operation is generated by the plurality of solenoid valves. Compared with what comprises a 1st branch part, it can reduce significantly. Moreover, according to the air conditioning apparatus 100, it is not necessary to equalize the refrigerant regardless of the amount of the high-temperature high-pressure liquid refrigerant flowing from the first connection pipe 6 on the indoor unit side, and the start-up time of the indoor unit is shortened. It becomes possible. Therefore, according to the air conditioning apparatus 100, comfort can be significantly improved.

DESCRIPTION OF SYMBOLS 1 Compressor, 2 way switching valve, 3 Heat source machine side heat exchanger, 4 Accumulator, 5 Indoor side heat exchanger, 6 1st connection piping, 6b 1st connection piping, 6d 1st connection piping, 7 1st 2 connection piping, 7b 2nd connection piping, 7d 2nd connection piping, 9 1st flow control device, 10 1st branch part, 11 2nd branch part, 12 Gas-liquid separation device, 13 2nd 14 1st bypass piping, 15 3rd flow control device, 16 2nd heat exchange part, 18 4th pressure detection means, 19 1st heat exchange part, 20 heat source machine side blower, 25 First pressure detection means, 26 Second pressure detection means, 31 Solenoid valve, 32 Third check valve, 33 Fourth check valve, 34 Fifth check valve, 35 Sixth check valve Valve, 40 heat source machine side switching valve, 41 first heat source machine side heat exchanger, 42 second heat source machine side heat exchanger, 43 heat source Side bypass path, 44 first electromagnetic on-off valve, 45 second electromagnetic on-off valve, 46 third electromagnetic on-off valve, 47 fourth electromagnetic on-off valve, 48 fifth electromagnetic on-off valve, 50 first check valve Valve, 50b first check valve, 50c first check valve, 50d first check valve, 51 second bypass pipe, 52 second check valve, 52b second check valve, 52d Second check valve, 53 First temperature detection means, 54 Second temperature detection means, 55 Fourth flow rate control device, 56 Third pressure detection means, 70 Control device, 100 Air conditioner, A Heat source Machine, B indoor machine, C indoor machine, D indoor machine, E relay machine.

Claims (2)

A heat source unit having a compressor, a switching valve and a heat source unit side heat exchanger, and a plurality of indoor units each having an indoor side heat exchanger and a first flow rate control device are connected to the first connecting pipe and the second An air conditioner that is connected via a connection pipe and supplies a refrigerant from the heat source unit to the plurality of indoor units to perform cooling and / or heating operation,
A first branching section that switches and connects one of the refrigerant inlets and outlets of the indoor heat exchanger of each of the plurality of indoor units to the first connection pipe or the second connection pipe;
One side is connected to the second connection pipe, the other side is branched into a plurality, and the other of the refrigerant inlets and outlets of the indoor heat exchangers of the plurality of indoor units is connected to the other through the first flow rate control device. A connected second branch,
In the first branch portion,
A branch side flow control device provided in each of the pipes branched into a plurality from the first connection pipe side and connected to the respective indoor heat exchangers;
An electromagnetic valve provided in each pipe branched from a pipe connecting each branch-side flow rate control device and each indoor heat exchanger;
The branch side flow rate control device is:
The opening degree is controlled based on the state of the refrigerant flowing into the branch side flow control device ,
The state of the refrigerant flowing into the branch side flow rate control device is:
An air conditioner that is determined from an outlet subcool value of the indoor heat exchanger that performs a heating operation before switching to a cooling operation . A heat source unit having a compressor, a switching valve and a heat source unit side heat exchanger, and a plurality of indoor units each having an indoor side heat exchanger and a first flow rate control device are connected to the first connecting pipe and the second An air conditioner that is connected via a connection pipe and supplies a refrigerant from the heat source unit to the plurality of indoor units to perform cooling and / or heating operation,
A first branching section that switches and connects one of the refrigerant inlets and outlets of the indoor heat exchanger of each of the plurality of indoor units to the first connection pipe or the second connection pipe;
One side is connected to the second connection pipe, the other side is branched into a plurality, and the other of the refrigerant inlets and outlets of the indoor heat exchangers of the plurality of indoor units is connected to the other through the first flow rate control device. A connected second branch,
In the first branch portion,
A branch side flow control device provided in each of the pipes branched into a plurality from the first connection pipe side and connected to the respective indoor heat exchangers;
An electromagnetic valve provided in each pipe branched from a pipe connecting each branch-side flow rate control device and each indoor heat exchanger;
The branch side flow rate control device is:
The opening degree is controlled based on the state of the refrigerant flowing into the branch side flow control device ,
The state of the refrigerant flowing into the branch side flow rate control device is:
An air conditioner that is determined by predicting an inlet / outlet differential pressure of the branch side flow rate control device.

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