Air conditioning system

Abstract

To secure intended performance of an air conditioner when controlling a refrigerant to be supplied to an indoor unit by using a control valve of a valve unit.SOLUTION: An air conditioning system 10 includes: a refrigerant circuit RC 1 that performs a refrigeration cycle; an outdoor unit 40; and a plurality of indoor units 30 connected in parallel with the outdoor unit 40. The air conditioning system includes: refrigerant piping 25 including a liquid pipe 25L and a gas pipe 25G connecting the indoor units 30 with the outdoor unit 40; a shutoff valve unit 51 that is a valve unit 50 provided in the middle of the refrigerant piping 25; and a first motor-operated valve 52 that is a pressure control valve PV provided in the shutoff valve unit 51 and regulating pressure of a refrigerant flowing in the liquid pipe 25L. A distance L1 from the indoor unit 30 to the shutoff valve unit 51 is 20 mm or smaller.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to an air conditioning system.

Background Art

[0002] Patent Document 1 discloses an air conditioning system including an outdoor unit (heat source unit), an indoor unit (usage unit), and a valve unit (refrigerant flow path switching unit). In the air conditioning system, control valves are provided in the outdoor unit, the indoor unit, and the valve unit, respectively. Patent Document 1 further discloses an air conditioning system configured to control the refrigerant supplied to the indoor unit with an electric valve of the outdoor unit or the valve unit, omitting the control valve of the indoor unit (see paragraph 0190).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the air conditioning system, the arrangement of the valve unit varies depending on the installation site, and the distance from the indoor unit to the electric valve of the valve unit also varies depending on the installation site. When controlling the refrigerant supplied to the indoor unit with the electric valve of the valve unit, the distance from the indoor unit to the electric valve affects the performance of the air conditioner. Therefore, when controlling the refrigerant supplied to the indoor unit with the electric valve of the valve unit, depending on the arrangement of the valve unit, it may not be possible to ensure the desired performance for the air conditioner.

[0005] An object of the present disclosure is to ensure the desired performance for the air conditioner when controlling the refrigerant supplied to the indoor unit with the electric valve of the valve unit.

Means for Solving the Problems

[0006] (1) The air conditioning system of the present disclosure is an air conditioning system including a refrigerant circuit that performs a refrigeration cycle, an outdoor unit, and a plurality of indoor units connected in parallel to the outdoor unit, and includes a refrigerant pipe including a liquid side pipe and a gas side pipe that connect the indoor unit and the outdoor unit, a valve unit provided in the middle of the refrigerant pipe, and a pressure control valve provided in the valve unit that adjusts the pressure of the refrigerant flowing through the liquid side pipe, and the distance from the indoor unit to the valve unit is 20 m or less.

[0007] When controlling the refrigerant supplied to the indoor unit with the electric valve of the valve unit, the control characteristics of the electric valve change according to the distance from the indoor unit to the valve unit. According to the air conditioning system of this configuration, by limiting the distance from the indoor unit to the valve unit to 20 m or less, the change in the control characteristics of the electric valve can be suppressed within an allowable range where the desired performance of the air conditioner can be ensured. Thereby, the desired performance of the air conditioner can be ensured.

[0008] (2) In the air conditioning system of the present disclosure, it is preferable that the valve unit is a refrigerant flow path switching unit that individually switches the flow of the refrigerant to the plurality of indoor units, and the pressure control valve is a liquid side electric valve included in the refrigerant flow path switching unit.

[0009] In this case, the liquid side electric valve of the refrigerant flow path switching unit can be used as a pressure control valve that controls the pressure of the refrigerant supplied to the indoor unit. Thereby, it is not necessary to separately provide a pressure control valve, and an increase in the cost of the air conditioning system can be suppressed.

[0010] (3) In the air conditioning system of the present disclosure, it is preferable that the valve unit is a refrigerant flow path switching unit that individually switches the flow of the refrigerant to the plurality of indoor units, and the pressure control valve is connected in series with the liquid side electric valve included in the refrigerant flow path switching unit.

[0011] In this case, a pressure control valve provided in the refrigerant flow path switching unit separately from the liquid-side motor-operated valve of the refrigerant flow path switching unit can control the pressure of the refrigerant supplied to the indoor unit. Thereby, desired performance of the air conditioner can be ensured.

[0012] (4) The air conditioning system of the present disclosure preferably further includes a first control unit that controls the operation of the indoor unit, and the valve unit preferably further includes a second control unit that controls the operation of the valve unit, and the pressure control valve is controlled based on information sent from the first control unit to the second control unit.

[0013] In this case, the pressure control valve can be controlled based on the information about the room detected by the indoor unit.

[0014] (5) The air conditioning system of the present disclosure preferably has the valve unit directly fixed to the casing of the indoor unit.

[0015] In this case, the distance from the indoor unit to the valve unit can be made constant. Thereby, the distance from the indoor unit to the valve unit can surely be made 20 m or less.

[0016] (6) The air conditioning system of the present disclosure preferably has the pressure control valve being a shut-off valve capable of shutting off the flow of the refrigerant in the liquid-side pipe.

[0017] In this case, by using the liquid-side shut-off valve of the shut-off valve unit as the pressure control valve, it is not necessary to separately provide a pressure control valve, and an increase in the cost of the air conditioning system can be suppressed.

Brief Description of the Drawings

[0018]

Fig. 1A

Fig. 1B

Fig. 1C

Fig. 2A

Fig. 2B

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

Mode for Carrying Out the Invention

[0019] (Overview of the air conditioning system) FIG. 1A is a schematic configuration diagram of an air conditioning system according to a first embodiment of the present disclosure. FIG. 1B is a schematic configuration diagram of an air conditioning system according to a second embodiment of the present disclosure. FIG. 1C is a schematic configuration diagram of an air conditioning system according to a third embodiment of the present disclosure. FIGS. 1A, 1B, and 1C show a schematic configuration of the air conditioning system 10 of the present disclosure. In the following description, the air conditioning system 10 according to the first embodiment (see FIG. 1A) is referred to as the first air conditioning system 11, the air conditioning system 10 according to the second embodiment (see FIG. 1B) is referred to as the second air conditioning system 12, and the air conditioning system 10 according to the third embodiment (see FIG. 1C) is referred to as the third air conditioning system 13. In the following description, when simply described as "air conditioning system 10", the common configuration among the first to third air conditioning systems 11 to 13 is described. In the following description, the "first specification" means a specification in which, in an air conditioner having a plurality of indoor units, all the indoor units are switched to either cooling operation or heating operation (so-called cooling / heating switching specification), and the "second specification" means a specification in which, in an air conditioner having a plurality of indoor units, cooling operation or heating operation can be individually selected for each indoor unit (so-called cooling / heating free specification).

[0020] The air conditioning system 10 shown in FIGS. 1A, 1B, and 1C is installed in a building, a factory, etc. to achieve air conditioning of the air-conditioned space. The air conditioning system 10 includes an air conditioner 20 including an indoor unit 30 and an outdoor unit 40. The air conditioner 20 cools and heats the air-conditioned space by performing a vapor compression refrigeration cycle operation.

[0021] The first air conditioning system 11 shown in FIG. 1A includes a first air conditioner 21 which is an air conditioner 20 of the first specification. The first air conditioner 21 includes an indoor unit 30 and an outdoor unit 40. In the following description, the outdoor unit 40 included in the first air conditioner 21 is referred to as the first outdoor unit 41.

[0022] The second air conditioning system 12 shown in FIG. 1B and the third air conditioning system 13 shown in FIG. 1C include an air conditioner 20 of the second specification. In the following description, the air conditioner 20 of the second air conditioning system 12 is referred to as the second air conditioner 22, and the air conditioner 20 of the third air conditioning system 13 is referred to as the third air conditioner 23.

[0023] The second air conditioner 22 includes an indoor unit 30 and an outdoor unit 40. In the following description, the outdoor unit 40 of the second air conditioner 22 is referred to as the second outdoor unit 42. Note that the outdoor unit 40 of the third air conditioner 23 (see FIG. 2B) is also the second outdoor unit 42. In other words, the second air conditioner 22 and the third air conditioner 23 include a common second outdoor unit 42.

[0024] As shown in FIGS. 1A, 1B, and 1C, the first air conditioner 21, the second air conditioner 22, and the third air conditioner 23 include a common indoor unit 30.

[0025] The air conditioner 20 includes a refrigerant pipe 25. The refrigerant pipe 25 of the first air conditioner 21 includes a liquid pipe (liquid side pipe) 25L and a gas pipe (gas side pipe) 25G. The refrigerant pipe 25 of the second air conditioner 22 and the third air conditioner 23 includes a liquid pipe 25L, a high and low pressure gas pipe (gas side pipe) 25G1, and a suction gas pipe (gas side pipe) 25G2.

[0026] The air conditioner 20 (the first air conditioner 21, the second air conditioner 22, and the third air conditioner 23) further includes a valve unit 50. The valve unit 50 of the first air conditioner 21 is a shut-off valve unit 51. The valve unit 50 of the second air conditioner 22 is a refrigerant flow path switching unit 55. The valve unit 50 of the third air conditioner 23 is a shut-off valve unit 51 and a refrigerant flow path switching unit 55.

[0027] (Regarding the first air conditioning system) FIG. 3 is a refrigerant circuit diagram of the air conditioning system according to the first embodiment of the present disclosure. FIG. 4 is a block diagram of the air conditioning system according to the first embodiment of the present disclosure. As shown in FIGS. 1A, 3, and 4, the first air conditioning system 11 includes a first air conditioner 21. The first air conditioner 21 is a multi-type air conditioner in which a plurality of indoor units 30 are connected in parallel to a first outdoor unit 41. In the example shown in FIG. 3, two or more indoor units 30 are connected to one first outdoor unit 41. However, the number of the first outdoor unit 41 and the indoor units 30 is not limited. The first air conditioner 21 can switch between a cooling operation and a heating operation to perform air conditioning of a target space.

[0028] The first air conditioner 21 includes an indoor unit 30, an outdoor unit 40, and a valve unit 50 (shutoff valve unit 51). Since the first air conditioner 21 uses a refrigerant having flammability (for example, R32 having slightly flammability) as the refrigerant, a shutoff valve unit 51 for shutting off the refrigerant supplied to the indoor unit 30 is provided.

[0029] The first air conditioner 21 has a refrigerant circuit RC1. The refrigerant circuit RC1 circulates the refrigerant between the first outdoor unit 41 and the indoor unit 30. The refrigerant circuit RC1 includes a compressor 81, a four-way switching valve 82, an outdoor heat exchanger 83, an outdoor expansion valve 84, a liquid shutoff valve 85, an indoor heat exchanger 31, a gas shutoff valve 86, and refrigerant pipes 25 (liquid pipe 25L and gas pipe 25G) connecting these components.

[0030] (Regarding the indoor unit) The indoor unit 30 includes an indoor heat exchanger 31. The indoor heat exchanger 31 constitutes the refrigerant circuit RC1. The indoor heat exchanger 31 is a cross fin tube type or a microchannel type heat exchanger and is used for heat exchange with indoor air.

[0031] The indoor unit 30 is equipped with an indoor fan 32 and an indoor temperature sensor 33. The indoor fan 32 is configured to take in indoor air into the interior of the indoor unit 30, perform heat exchange between the taken-in air and the indoor heat exchanger 31, and then blow out the air into the room. The indoor fan 32 is equipped with a motor whose operating rotation speed can be adjusted by inverter control. The indoor temperature sensor 33 detects the indoor temperature.

[0032] As described above, the indoor unit 30 of the present disclosure does not have an electric valve (indoor expansion valve) inside the indoor unit 30. In the air conditioning system 10 of the present disclosure, by using an indoor unit 30 that does not have an electric valve (indoor expansion valve) inside, it is possible to use a common indoor unit 30 regardless of the specifications of the outdoor unit 40.

[0033] (Regarding the first outdoor unit) As shown in FIG. 3, the first outdoor unit 41 includes a compressor 81, a four-way switching valve 82, an outdoor heat exchanger 83, an outdoor expansion valve 84, a liquid shut-off valve 85, a gas shut-off valve 86, etc.

[0034] The compressor 81 sucks in low-pressure gaseous refrigerant and discharges high-pressure gaseous refrigerant. The compressor 81 is equipped with a motor whose operating rotation speed can be adjusted by inverter control. The compressor 81 is a variable capacity type (capacity variable type) whose capacity (ability) can be changed when the motor is under inverter control. However, the compressor 81 may be a fixed capacity type.

[0035] The four-way switching valve 82 reverses the flow of the refrigerant in the refrigerant piping and switches and supplies the refrigerant discharged from the compressor 81 to either the outdoor heat exchanger 83 or the indoor heat exchanger 31. Thereby, the first air conditioner 21 can switch between cooling operation and heating operation.

[0036] The outdoor heat exchanger 83 is, for example, a cross fin tube type or microchannel type heat exchanger, and is used to exchange heat between a refrigerant and air as a heat source. The outdoor expansion valve 84 is composed of an electric valve capable of adjusting the flow rate and pressure of the refrigerant. In the first air conditioner 21, the opening degree of the outdoor expansion valve 84 is controlled to adjust the pressure of the refrigerant supplied to the indoor heat exchanger 31.

[0037] The liquid shut-off valve 85 is a manual on-off valve. The gas shut-off valve 86 is also a manual on-off valve. The liquid shut-off valve 85 and the gas shut-off valve 86 shield the flow of the refrigerant in the liquid pipe 25L and the gas pipe 25G by closing, and allow the flow of the refrigerant in the liquid pipe 25L and the gas pipe 25G by opening.

[0038] The first outdoor unit 41 further includes an outdoor fan 87. The outdoor fan 87 includes a motor whose operating rotation speed can be adjusted by inverter control. The outdoor fan 87 is configured to take in outdoor air into the first outdoor unit 41, perform heat exchange between the taken-in air and the outdoor heat exchanger 83, and then blow out the air to the outside of the first outdoor unit 41. Note that the first outdoor unit 41 further includes a plurality of refrigerant pressure sensors, a plurality of refrigerant temperature sensors, and an outside air temperature sensor (not shown).

[0039] (Regarding the shut-off valve unit) As shown in FIGS. 3 and 4, the shut-off valve unit 51 includes a first electric valve 52 and a second electric valve 53. The first electric valve 52 and the second electric valve 53 are electric valves. The first electric valve 52 is provided in the liquid pipe 25L, and the pressure of the liquid refrigerant flowing through the liquid pipe 25L can be adjusted by adjusting the opening degree of the first electric valve 52. The first electric valve 52 can shut off the flow of the liquid refrigerant in the liquid pipe 25L by setting its valve opening degree to fully closed. The second electric valve 53 is provided in the gas pipe 25G, and the flow of the gaseous refrigerant in the gas pipe 25G can be shut off by setting the valve opening degree of the second electric valve 53 to fully closed. In other words, the shut-off valve unit 51 is a valve unit 50 that switches the flow of the refrigerant to the indoor unit 30 between "open" and "closed".

[0040] (Regarding the control unit) The air conditioning system 10 includes a control unit 60 that controls the operation of the air conditioning system 10. The control unit 60 includes an outdoor control unit (first control unit) 61 disposed in the outdoor unit 40 and an indoor control unit (second control unit) 62 disposed in the indoor unit 30.

[0041] The outdoor control unit 61 is a device that controls the operation of the outdoor unit 40, and is configured by, for example, a microcomputer including a processor such as a CPU and memories such as a RAM and a ROM. The outdoor control unit 61 may be realized as hardware using an LSI, an ASIC, an FPGA, or the like. The outdoor control unit 61 exhibits a predetermined function when the processor executes a program installed in the memory. In the following description, the outdoor control unit 61 provided in the first outdoor unit 41 is referred to as the first outdoor control unit 61A. The detection values of the sensors provided in the first outdoor unit 41 are input to the first outdoor control unit 61A. The first outdoor control unit 61A controls the operations of the outdoor expansion valve 84, the compressor 81, the outdoor fan 87, etc. based on the detection values of the sensors and the like.

[0042] The indoor control unit 62 is a device that controls the operation of the indoor unit 30, and is configured by, for example, a microcomputer including a processor such as a CPU and memories such as a RAM and a ROM. The indoor control unit 62 may be realized as hardware using an LSI, an ASIC, an FPGA, or the like. The indoor control unit 62 exhibits a predetermined function when the processor executes a program installed in the memory. The detection values of the sensors provided in the indoor unit 30 are input to the indoor control unit 62. The indoor control unit 62 controls the operation of the indoor unit 30 based on the detection values of the sensors and the like. The indoor control unit 62 has a remote controller 36 connected thereto for the user to perform operations such as starting / stopping the indoor unit 30 and changing the set temperature.

[0043] (Regarding the control unit of the second air conditioning system) The second air conditioning system 12 further includes a shutoff valve control unit 63 provided in the shutoff valve unit 51. In the second air conditioning system 12, the control unit 60 includes a first outdoor control unit 61A, an indoor control unit 62, and a shutoff valve control unit 63. The first outdoor control unit 61A, the indoor control unit 62, and the shutoff valve control unit 63 are communicably connected to each other via a transmission line.

[0044] (Regarding the shutoff valve control unit) The shutoff valve control unit 63 is a device that controls the operation of the shutoff valve unit 51, and is configured by, for example, a microcomputer including a processor such as a CPU and memories such as a RAM and a ROM. The shutoff valve control unit 63 may be realized as hardware using an LSI, an ASIC, an FPGA, or the like. The shutoff valve control unit 63 exhibits a predetermined function when the processor executes a program installed in the memory. The shutoff valve control unit 63 controls the operations of the first electric valve 52 and the second electric valve 53 based on detection values of various sensors (not shown) provided in the indoor unit 30 and the first outdoor unit 41. In the second air conditioning system 12, the shutoff valve control unit 63 may be omitted. In this case, the operations of the first electric valve 52 and the second electric valve 53 are controlled by the first outdoor control unit 61A and / or the indoor control unit 62.

[0045] In the first air conditioning system 11, when a refrigerant sensor (not shown) provided in the indoor unit 30 detects the refrigerant during system operation, the control unit 60 fully closes the first electric valve 52 and the second electric valve 53. Thereby, the supply of the refrigerant to the indoor unit 30 is shut off.

[0046] In the first air conditioning system 11, the first electric valve 52 has a role as a shutoff valve and also has a role as a pressure control valve for controlling the pressure of the refrigerant supplied to the indoor unit 30. In the following description, the control valve for controlling the pressure of the refrigerant supplied from the outdoor unit 40 to the indoor unit 30 is referred to as the pressure control valve PV. In other words, the first electric valve 52 in the first air conditioning system 11 is the pressure control valve PV.

[0047] In the first air conditioning system 11, the first electric valve 52 is used as the pressure control valve PV. Based on the detected values of various sensors (not shown) provided in the indoor unit 30 and the first outdoor unit 41, etc., the shut-off valve control unit 63 adjusts the opening degree of the first electric valve 52 to control the pressure of the refrigerant supplied to the indoor unit 30. In the first air conditioning system 11, by using the first electric valve 52 of the shut-off valve unit 51 (valve unit 50) as the control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30, it is possible to use the indoor unit 30 that does not have an electric valve (indoor expansion valve) inside. Note that in the present embodiment, the case where the control main body of the control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30 is the shut-off valve control unit 63 among the control units 60 is illustrated, but it is not limited thereto, and it may be the first outdoor control unit 61A, the indoor control unit 62, etc.

[0048] In the first air conditioning system 11, the first electric valve 52, which is the pressure control valve PV, may be configured to be controlled based on the information sent from the indoor control unit 62 to the shut-off valve control unit 63. In such a configuration, based on the indoor information detected by the indoor unit 30, the first electric valve 52 (pressure control valve PV) can be controlled.

[0049] When the first air conditioner 21 with the above configuration performs a cooling operation, the four-way switching valve 82 is held in the state shown by the solid line in FIG. 3. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 81 flows into the outdoor heat exchanger 83 through the four-way switching valve 82, and exchanges heat with the outdoor air by the operation of the outdoor fan 87 to condense and liquefy. The liquefied refrigerant passes through the fully open outdoor expansion valve 84 and is decompressed by the first electric valve 52 and then flows into each indoor unit 30. In the indoor unit 30, the refrigerant exchanges heat with the indoor air in the indoor heat exchanger 31 and evaporates. The indoor air cooled by the evaporation of the refrigerant is blown into the room by the indoor fan 32 to cool the room. The refrigerant evaporated in the indoor heat exchanger 31 returns to the first outdoor unit 41 through the gas pipe 25G and is sucked into the compressor 81 through the four-way switching valve 82.

[0050] When the first air conditioner 21 performs a heating operation, the four-way switching valve 82 is held in the state shown by the dashed line in Fig. 3. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 81 passes through the four-way switching valve 82 and flows into the indoor heat exchangers 31 of the indoor units 30. In the indoor heat exchanger 31, the refrigerant exchanges heat with the indoor air and condenses and liquefies. The indoor air heated by the condensation of the refrigerant is blown into the room by the indoor fan 32 to heat the room. The refrigerant liquefied in the indoor heat exchanger 31 returns to the first outdoor unit 41 through the fully opened first electric valve 52 and the liquid pipe 25L, is depressurized to a predetermined low pressure by the outdoor expansion valve 84, and further exchanges heat with the outdoor air in the outdoor heat exchanger 83 and evaporates. The refrigerant evaporated and vaporized in the outdoor heat exchanger 83 is sucked into the compressor 81 through the four-way switching valve 82.

[0051] In the first air conditioning system 11, the first electric valve 52 can block the flow of the refrigerant in the liquid pipe 25L. In other words, in the first air conditioning system 11, the pressure control valve PV is the first electric valve 52 that can block the flow of the refrigerant in the liquid pipe 25L. In this case, by using the first electric valve 52 for refrigerant cutoff as the pressure control valve PV, there is no need to separately provide a control valve (pressure control valve PV) for adjusting the pressure of the refrigerant supplied to the indoor unit 30, and the number of control valves can be suppressed. Thereby, an increase in the cost of the first air conditioning system 11 can be suppressed.

[0052] (Regarding the distance from the indoor unit to the valve unit) When the first motor-operated valve 52 included in the shut-off valve unit 51 is used as the pressure control valve PV, the distance L1 (see FIG. 1A) from the indoor unit 30 to the shut-off valve unit 51 affects the performance of the first air conditioner 21. In other words, the control characteristics of the first motor-operated valve 52 change according to the distance L1 from the indoor unit 30 to the shut-off valve unit 51. If the distance L1 from the indoor unit 30 to the shut-off valve unit 51 is too large, it becomes impossible to ensure the desired performance for the first air conditioner 21. In the first air conditioning system 11, the distance L1 from the indoor unit 30 to the shut-off valve unit 51 is 20 m or less. With this configuration, the change in the control characteristics of the first motor-operated valve 52 can be suppressed within an allowable range where the desired performance of the first air conditioner 21 can be ensured, and thereby, the desired performance can be ensured for the first air conditioner 21.

[0053] (Modification example of the first air conditioning system) FIG. 2A is a schematic configuration diagram of a modification example of the air conditioning system according to the first embodiment of the present disclosure. As shown in FIG. 2A, in the first air conditioner 21, the casing 51a of the shut-off valve unit 51 may be directly attached to the casing 30a of the indoor unit 30. In this case, the distance L1 (see FIG. 1A) from the indoor unit 30 to the shut-off valve unit 51 becomes "0". In the first air conditioning system 11 configured in this way, the distance L1 from the indoor unit 30 to the shut-off valve unit 51 is surely 20 m or less. Thereby, regardless of the construction situation at the site, the desired performance can be surely ensured for the first air conditioner 21.

[0054] (Regarding the second air conditioning system) FIG. 5 is a refrigerant circuit diagram of the air conditioning system according to the second embodiment of the present disclosure. FIG. 6 is a block diagram of the air conditioning system according to the second embodiment of the present disclosure. As shown in FIGS. 1B, 5, and 6, the second air conditioning system 12 includes a second air conditioner 22.

[0055] The second air conditioner 22 includes an indoor unit 30, a second outdoor unit 42, and a valve unit 50. The second air conditioner 22 has a refrigerant circuit RC2. The refrigerant circuit RC2 circulates refrigerant between the second outdoor unit 42 and the indoor unit 30. The refrigerant circuit RC2 includes a heat source side refrigerant circuit RC2A, a utilization side refrigerant circuit RC2B, and an intermediate refrigerant circuit RC2C, which will be described later. For one second outdoor unit 42, two or more indoor units 30 are connected to the second air conditioner 22.

[0056] The valve unit 50 included in the second air conditioner 22 is a refrigerant flow path switching unit 55. For one second outdoor unit 42, two or more indoor units 30 are connected to the second air conditioner 22. Each indoor unit 30 is connected to the second outdoor unit 42 via the refrigerant flow path switching unit 55. The second air conditioner 22 can freely select cooling operation and heating operation for each indoor unit 30 by the refrigerant flow path switching unit 55 to perform air conditioning of the target space.

[0057] (Configuration of the Second Outdoor Unit) As shown in FIG. 5, various devices are arranged in the second outdoor unit 42, and these devices are connected via refrigerant pipes to form the heat source side refrigerant circuit RC2A. The heat source side refrigerant circuit RC2A is connected to the intermediate refrigerant circuit RC2C in the refrigerant flow path switching unit 55 via refrigerant pipes 25 (liquid pipe 25L, high and low pressure gas pipes 25G1, and suction gas pipe 25G2).

[0058] The heat source side refrigerant circuit RC2A includes a liquid side shutoff valve 101, a gas side first shutoff valve 102, a gas side second shutoff valve 103, an accumulator 104, a compressor 105, a first flow path switching valve 106, a second flow path switching valve 107, a third flow path switching valve 108, an outdoor heat exchanger 109, a first outdoor expansion valve 110, and a second outdoor expansion valve 111. The heat source side refrigerant circuit RC2A is formed by connecting these devices via a plurality of refrigerant pipes. In the second outdoor unit 42, an outdoor fan 112 and an outdoor control unit 61 (see FIG. 6) not shown are further arranged.

[0059] The liquid-side shut-off valve 101, the gas-side first shut-off valve 102, and the gas-side second shut-off valve 103 are manual valves that are opened and closed during refrigerant filling, pump-down, etc. One end of the liquid-side shut-off valve 101 is connected to the liquid pipe 25L. The other end of the liquid-side shut-off valve 101 is connected to a refrigerant pipe extending to the first outdoor expansion valve 110 and the second outdoor expansion valve 111. One end of the gas-side first shut-off valve 102 is connected to the high and low pressure gas pipe 25G1. The other end of the gas-side first shut-off valve 102 is connected to a refrigerant pipe extending to the second flow path switching valve 107. One end of the gas-side second shut-off valve 103 is connected to the suction gas pipe 25G2. The other end of the gas-side second shut-off valve 103 is connected to a refrigerant pipe extending to the accumulator 104.

[0060] The accumulator 104 is a container for temporarily storing the low-pressure refrigerant sucked into the compressor 105 and separating the gas refrigerant and the liquid refrigerant.

[0061] The compressor 105 has a hermetic structure incorporating a compressor motor and is, for example, a positive displacement compressor such as a scroll type or a rotary type. The compressor 105 compresses the low-pressure refrigerant sucked from the suction pipe 105b and then discharges it from the discharge pipe 105a. Refrigerant oil is contained inside the compressor 105. This refrigerant oil may circulate in the refrigerant circuit together with the refrigerant. The second outdoor unit 42 of the present embodiment includes one compressor 105, but may include two or more compressors 105 connected in parallel.

[0062] The first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108 are four-way switching valves. The first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108 switch the flow of the refrigerant according to the operating conditions of the third air conditioner 23. A discharge pipe 105a or a branch pipe extending from the discharge pipe 105a is connected to one refrigerant inlet of the first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108. A branch pipe extending from the refrigerant pipe 105c connecting the gas-side second closing valve 103 and the accumulator 104 is connected to one refrigerant inlet of the first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108. The first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108 are configured such that the flow of the refrigerant in one refrigerant flow path is blocked during operation, and in fact, function as three-way valves.

[0063] The outdoor heat exchanger 109 is a cross-fin type or micro-channel type heat exchanger. The outdoor heat exchanger 109 includes a first heat exchange section 109a and a second heat exchange section 109b. The first heat exchange section 109a is provided at the upper part of the outdoor heat exchanger 109, and the second heat exchange section 109b is provided at a lower part than the first heat exchange section 109a.

[0064] The gas-side end of the first heat exchange section 109a is connected to a refrigerant pipe extending to the third flow path switching valve 108. The liquid-side end of the first heat exchange section 109a is connected to a refrigerant pipe extending to the first outdoor expansion valve 110.

[0065] The gas-side end of the second heat exchange section 109b is connected to a refrigerant pipe extending to the first flow path switching valve 106. The liquid-side end of the second heat exchange section 109b is connected to a refrigerant pipe extending to the second outdoor expansion valve 111.

[0066] The refrigerant passing through the first heat exchanger 109a and the second heat exchanger 109b exchanges heat with the air flow generated by the outdoor fan 112. The outdoor fan 112 is, for example, a propeller fan and is driven by an outdoor fan motor (not shown). The outdoor fan 112 generates an air flow that flows into the second outdoor unit 42, passes through the outdoor heat exchanger 109, and flows out of the second outdoor unit 42.

[0067] The first outdoor expansion valve 110 and the second outdoor expansion valve 111 are, for example, motor-operated valves whose opening degrees can be adjusted. One end of the first outdoor expansion valve 110 is connected to a refrigerant pipe extending from the first heat exchanger 109a. The other end of the first outdoor expansion valve 110 is connected to a refrigerant pipe extending to the liquid-side shutoff valve 101.

[0068] One end of the second outdoor expansion valve 111 is connected to a refrigerant pipe extending from the second heat exchanger 109b. The other end of the second outdoor expansion valve 111 is connected to a refrigerant pipe extending to the liquid-side shutoff valve 101. The first outdoor expansion valve 110 and the second outdoor expansion valve 111 have their opening degrees adjusted according to the operating conditions, and decompress the refrigerant passing through them according to their opening degrees.

[0069] The compressor 105, the outdoor fan 112, the first outdoor expansion valve 110, the second outdoor expansion valve 111, the first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108 are operationally controlled by the outdoor control unit 61 (see FIG. 6). In the following description, the outdoor control unit 61 of the second outdoor unit 42 is referred to as the second outdoor control unit 61B.

[0070] (Indoor unit) The second air conditioner 22 has the same indoor unit 30 as the first air conditioner 21. A detailed description of the indoor unit 30 in the second air conditioner 22 is omitted. A user-side refrigerant circuit RC2B is provided in the indoor unit 30. The user-side refrigerant circuit RC2B is configured by connecting the indoor heat exchanger 31 by a liquid pipe 25L and a gas pipe 25G.

[0071] (Refrigerant flow path switching unit) As shown in FIGS. 5 and 6, the second air conditioner 22 has a refrigerant flow path switching unit 55. The refrigerant flow path switching unit 55 is provided between the second outdoor unit 42 and the plurality of indoor units 30. The refrigerant flow path switching unit 55 has a casing 56. The refrigerant flow path switching unit 55 switches the flow of the refrigerant flowing into the second outdoor unit 42 and each indoor unit 30. The refrigerant flow path switching unit 55 is a valve unit 50 that switches the flow of the refrigerant to each indoor unit 30. As shown in FIG. 5, a plurality of header pipes 155, 156, 157, 158 and a plurality of switching units 57 are accommodated in the casing 56.

[0072] (Header pipe) As shown in FIG. 5, the plurality of header pipes 155, 156, 157, 158 include a first header pipe 155, a second header pipe 156, a third header pipe 157, and a fourth header pipe 158. The first header pipe 155 is connected to the liquid pipe 25L. The second header pipe 156 is connected to the high and low pressure gas pipe 25G1. The third header pipe 157 is connected to the suction gas pipe 25G2.

[0073] (Switching unit) The refrigerant flow path switching unit 55 includes a plurality of switching units 57. Each switching unit 57 forms an intermediate refrigerant circuit RC2C of the refrigerant flow path switching unit 55. One indoor unit 30 is connected to each switching unit 57. However, it is not necessary for all the switching units 57 of the refrigerant flow path switching unit 55 to be connected to the indoor unit 30, and there may be a switching unit 57 to which the indoor unit 30 is not connected in the refrigerant flow path switching unit 55.

[0074] (Regarding the intermediate refrigerant circuit) The plurality of switching units 57 all have the same structure, and the intermediate refrigerant circuit RC2C of each switching unit 57 includes a plurality of valves EV1, EV2, EV3, EV4 and a plurality of refrigerant pipes.

[0075] In the switching unit 57, the plurality of valves EV1, EV2, EV3, EV4 include a first valve EV1, a second valve EV2, a third valve EV3, and a fourth valve EV4. These valves EV1, EV2, EV3, EV4 are constituted by motor-operated valves whose opening degrees are adjustable. The second valve EV2, the third valve EV3, and the fourth valve EV4 are operationally controlled by a flow path switching control unit 64 (see FIG. 6) so as to take any one of a fully closed state, a fully open state, and an opening degree adjustment state. The first valve EV1 is operationally controlled by the flow path switching control unit 64 (see FIG. 6) so as to take any one of a minimum opening degree state, a fully open state, a fully closed state, and an opening degree adjustment state.

[0076] The switching unit 57 includes a first refrigerant pipe P1 that connects the second header pipe 156 and the first valve EV1. A filter F1 is provided in the middle of the first refrigerant pipe P1. The switching unit 57 includes a second refrigerant pipe P2. One end of the second refrigerant pipe P2 is connected to the first valve EV1. The switching unit 57 includes a user-side gas pipe 161. One end of the user-side gas pipe 161 is connected to the gas pipe 25G of the indoor unit 30. The other end of the user-side gas pipe 161 is connected to the second valve EV2. The other end of the second refrigerant pipe P2 is connected to the user-side gas pipe 161. A filter F2 is provided in the user-side gas pipe 161.

[0077] The switching unit 57 includes a third refrigerant pipe P3. One end of the third refrigerant pipe P3 is connected to the second valve EV2. The other end of the third refrigerant pipe P3 is connected to the third header pipe 157. A filter F3 is provided in the middle of the third refrigerant pipe P3.

[0078] The switching unit 57 is provided with a user-side liquid pipe 162. One end of the user-side liquid pipe 162 is connected to the liquid pipe 25L of the indoor unit 30. The other end of the user-side liquid pipe 162 is connected to the subcooling heat exchanger 159. A fourth valve EV4 is provided in the middle of the user-side liquid pipe 162. Inside the subcooling heat exchanger 159, a first heat transfer pipe 159a and a second heat transfer pipe 159b are provided. The subcooling heat exchanger 159 performs heat exchange between the refrigerant flowing through the first heat transfer pipe 159a and the refrigerant flowing through the second heat transfer pipe 159b. The other end of the user-side liquid pipe 162 is connected to one end of the first heat transfer pipe 159a.

[0079] The switching unit 57 is provided with a fourth refrigerant pipe P4. One end of the fourth refrigerant pipe P4 is connected to the other end of the first heat transfer pipe 159a. The other end of the fourth refrigerant pipe P4 is connected to the first header pipe 155.

[0080] The switching unit 57 is provided with a fifth refrigerant pipe P5 branched from the middle of the fourth refrigerant pipe P4. One end of the fifth refrigerant pipe P5 is connected to one end of the third valve EV3. A filter F4 is provided in the middle of the fifth refrigerant pipe P5.

[0081] The switching unit 57 is provided with a sixth refrigerant pipe P6 and a seventh refrigerant pipe P7. One end of the sixth refrigerant pipe P6 is connected to the third valve EV3. The other end of the sixth refrigerant pipe P6 is connected to one end of the second heat transfer pipe 159b of the subcooling heat exchanger 159. One end of the seventh refrigerant pipe P7 is connected to the second heat transfer pipe 159b of the subcooling heat exchanger 159. The other end of the seventh refrigerant pipe P7 is connected to the fourth header pipe 158. The fourth header pipe 158 is connected to the third header pipe 157 via a connecting pipe 163.

[0082] Refrigerant flows into the fourth header pipe 158 from the first header pipe 155 through the fourth refrigerant pipe P4, the fifth refrigerant pipe P5, the third valve EV3, the sixth refrigerant pipe P6, the subcooling heat exchanger 159, and the seventh refrigerant pipe P7. Further, the refrigerant flowing into the fourth header pipe 158 flows into the third header pipe 157 through the connecting pipe 163.

[0083] (Regarding the control unit of the second air conditioning system) The control unit 60 in the second air conditioning system 12 includes a second outdoor control unit 61B, an indoor control unit 62, and a flow path switching control unit 64 of the refrigerant flow path switching unit 55. The second outdoor control unit 61B, the indoor control unit 62, and the flow path switching control unit 64 are communicably connected to each other via a transmission line.

[0084] The second outdoor control unit 61B is a device that controls the operation of the second outdoor unit 42. The detection values of each sensor provided in the second outdoor unit 42 are input to the second outdoor control unit 61B. The second outdoor control unit 61B controls the operations of the compressor 105, the outdoor fan 112, the first outdoor expansion valve 110, the second outdoor expansion valve 111, the first flow path switching valve 106, the second flow path switching valve 107, and the third flow path switching valve 108, etc., based on the detection values of each sensor, etc.

[0085] The flow path switching control unit 64 is a device that controls the operation of the refrigerant flow path switching unit 55, and is constituted by, for example, a microcomputer including a processor such as a CPU, and memories such as a RAM and a ROM. The flow path switching control unit 64 may be realized as hardware using an LSI, an ASIC, an FPGA, etc. The flow path switching control unit 64 exhibits a predetermined function by the processor executing a program installed in the memory. The flow path switching control unit 64 controls the operations of the first valve EV1, the second valve EV2, the third valve EV3, and the fourth valve EV4 based on the detection values of each sensor of the second outdoor unit 42 and the indoor unit 30, etc.

[0086] In the second air conditioning system 12, the fourth valve EV4 is used as the pressure control valve PV. Based on the detection values of various sensors (not shown) included in the indoor unit 30 and the second outdoor unit 42, the flow path switching control unit 64 adjusts the opening degree of the fourth valve EV4 to control the pressure of the refrigerant supplied to the indoor unit 30. In the second air conditioning system 12, by using the fourth valve EV4 of the refrigerant flow path switching unit 55 (valve unit 50) as the control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30, it is possible to use the indoor unit 30 that does not have an electric valve (indoor expansion valve) inside. In the present embodiment, the case where the control main body of the control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30 is the flow path switching control unit 64 in the control unit 60 is illustrated, but it is not limited thereto, and it may be the second outdoor control unit 61B, the indoor control unit 62, or the like.

[0087] In the second air conditioning system 12, the fourth valve EV4, which is the pressure control valve PV, may be configured to be controlled based on the information sent from the indoor control unit 62 to the flow path switching control unit 64. In such a configuration, based on the indoor information detected by the indoor unit 30, the fourth valve EV4 (pressure control valve PV) can be controlled.

[0088] (Regarding the operation of the second air conditioning system) Hereinafter, when all of the operating indoor units 30 perform cooling (hereinafter also referred to as "full cooling operation"), when all of the operating indoor units 30 perform heating (hereinafter also referred to as "full heating operation"), and when some of the operating indoor units 30 perform cooling and others perform heating (hereinafter also referred to as "cooling and heating mixed operation") by the second air conditioning system 12, an explanation will be given.

[0089] (Full cooling operation) In full cooling operation, each valve is adjusted by the control unit 60 as follows. The first valve EV1 of the switching unit 57 is fully closed, the second valve EV2 is fully open, the opening degrees of the third valve EV3 and the fourth valve EV4 are adjusted, and the first and second outdoor expansion valves 110, 111 are fully open. The first flow path switching valve 106 of the second outdoor unit 42 is switched to connect the discharge pipe 105a of the compressor 105 and the gas side end of the second heat exchange part 109b. The second flow path switching valve 107 is switched to connect the discharge pipe 105a and the high and low pressure gas pipe 25G1. The third flow path switching valve 108 is switched to connect the discharge pipe 105a and the gas side end of the first heat exchange part 109a.

[0090] When the compressor 105 is driven, the high-pressure gas refrigerant compressed by the compressor 105 flows into the outdoor heat exchanger 109 through the discharge pipe 105a, the first flow path switching valve 106, the third flow path switching valve 108, etc. and condenses. The refrigerant condensed in the outdoor heat exchanger 109 passes through the first and second outdoor expansion valves 110, 111, the liquid side closing valve 101, etc. and flows into the liquid pipe 25L.

[0091] The refrigerant flowing into the liquid pipe 25L flows through the first header pipe 155 of the refrigerant flow path switching unit 55 and into the fourth refrigerant pipe P4 of each switching unit 57. The refrigerant flowing into the fourth refrigerant pipe P4 flows into the first heat transfer pipe 159a of the subcooling heat exchanger 159, and is further depressurized by the fourth valve EV4 on the utilization side liquid pipe 162 and flows into the indoor unit 30.

[0092] The refrigerant flowing into the fourth refrigerant pipe P4 also branches and flows into the fifth refrigerant pipe P5, is depressurized according to the opening degree of the third valve EV3, and flows into the second heat transfer pipe 159b of the subcooling heat exchanger 159. In this subcooling heat exchanger 159, heat exchange occurs between the refrigerant flowing through the first heat transfer pipe 159a and the refrigerant flowing through the second heat transfer pipe 159b, and the refrigerant flowing through the first heat transfer pipe 159a is subcooled and flows into the indoor unit 30.

[0093] The refrigerant flowing through the second heat transfer tube 159b of the subcooling heat exchanger 159 flows from the seventh refrigerant pipe P7 into the fourth header pipe 158 and then into the third header pipe 157 via the connecting pipe 163. The refrigerant flowing into the indoor unit 30 evaporates in the indoor heat exchanger 31.

[0094] In the indoor unit 30, the refrigerant evaporated in the indoor heat exchanger 31 flows from the gas pipe 25G into the utilization-side gas pipe 161, mainly passes through the second valve EV2, and then flows into the third header pipe 157. The refrigerant flowing into the third header pipe 157 flows into the accumulator 104 via the suction gas pipe 25G2 and the gas-side second shut-off valve 103 and is sucked into the compressor 105.

[0095] (Regarding full heating operation) In full heating operation, each valve is adjusted as follows by the control unit 60. The first valve EV1 of the switching unit 57 is fully opened, the second valve EV2 is fully closed, the third valve EV3 is fully closed, the fourth valve EV4 is fully opened, and the first and second outdoor expansion valves 110, 111 are adjusted in opening degree. The first flow path switching valve 106 of the second outdoor unit 42 is switched to connect the refrigerant pipe 105c and the gas-side end of the second heat exchange section 109b. The second flow path switching valve 107 is switched to connect the discharge pipe 105a and the high-low pressure gas pipe 25G1. The third flow path switching valve 108 is switched to connect the refrigerant pipe 105c and the gas-side end of the first heat exchange section 109a.

[0096] When the compressor 105 is driven, the high-pressure gas refrigerant compressed by the compressor 105 flows into the high-low pressure gas pipe 25G1 via the discharge pipe 105a and the second flow path switching valve 107, etc. The refrigerant flowing into the high-low pressure gas pipe 25G1 passes through the second header pipe 156 of the refrigerant flow path switching unit 55 and the first refrigerant pipe P1 of the switching unit 57, passes through the first valve EV1, and flows into the gas pipe 25G of the indoor unit 30 from the utilization-side gas pipe 161.

[0097] The refrigerant flowing into the gas pipe 25G flows into the indoor heat exchanger 31 of the indoor unit 30 and condenses. The condensed refrigerant flows through the liquid pipe 25L, passes through the fourth valve EV4, and flows into the utilization-side liquid pipe 162 of the switching unit 57. The refrigerant flowing into the utilization-side liquid pipe 162 flows into the first header pipe 155 via the subcooling heat exchanger 159 and the fourth refrigerant pipe P4.

[0098] The refrigerant flowing into the first header pipe 155 flows through the liquid pipe 25L and into the second outdoor unit 42, where it is depressurized by the first and second outdoor expansion valves 110 and 111. The depressurized refrigerant evaporates when passing through the outdoor heat exchanger 109, flows through the first flow path switching valve 106, the third flow path switching valve 108, etc., and flows into the accumulator 104, where it is sucked into the compressor 105.

[0099] (Heating and cooling mixed operation) In the heating and cooling mixed operation, each valve is adjusted as follows by the control unit 60. Among the operating indoor units 30, in the switching unit 57 (hereinafter also referred to as the "cooling-side switching unit 57") corresponding to the indoor unit 30 performing the cooling operation (hereinafter also referred to as the "cooling-side indoor unit 30"), the first valve EV1 is set to the minimum opening degree, the second valve EV2 is set to the fully open state, and the third valve EV3 and the fourth valve EV4 are adjusted in terms of the opening degree. The first flow path switching valve 106 of the second outdoor unit 42 is switched so as to connect the refrigerant pipe 105c and the gas-side end of the second heat exchange section 109b. The second flow path switching valve 107 is switched so as to connect the discharge pipe 105a and the high and low pressure gas pipe 25G1. The third flow path switching valve 108 is switched so as to connect the discharge pipe 105a and the gas-side end of the first heat exchange section 109a.

[0100] Among the operating indoor units 30, in the switching unit 57 (hereinafter also referred to as the "heating-side switching unit 57") corresponding to the indoor unit 30 performing the heating operation (hereinafter also referred to as the "heating-side indoor unit 30"), the first valve EV1 is set to the fully open state, the second valve EV2 is set to the fully closed state, the third valve EV3 is set to the fully closed state, and the fourth valve EV4 is set to the fully open state.

[0101] When the compressor 105 is driven, a part of the high-pressure gas refrigerant compressed by the compressor 105 flows into the high and low pressure gas pipe 25G1 through the discharge pipe 105a and the second flow path switching valve 107. Another part of the high-pressure gas refrigerant compressed by the compressor 105 is condensed in the first heat exchange section 109a through the discharge pipe 105a and the third flow path switching valve 108, and a part of it flows into the liquid pipe 25L through the first outdoor expansion valve 110, and the rest flows into the second outdoor expansion valve 111. The refrigerant condensed in the first heat exchange section 109a evaporates in the second heat exchange section 109b through the second outdoor expansion valve 111 and is sucked into the compressor 105 through the first flow path switching valve 106.

[0102] The refrigerant flowing into the high and low pressure gas pipe 25G1 flows into the second header pipe 156 of the refrigerant flow path switching unit 55, flows through the first refrigerant pipe P1, the first valve EV1, and the utilization side gas pipe 161 of the heating side switching unit 57, and flows into the gas pipe 25G.

[0103] The refrigerant flowing into the gas pipe 25G condenses in the indoor heat exchanger 31 of the heating side indoor unit 30. The condensed refrigerant flows into the utilization side liquid pipe 162 of the heating side switching unit 57 through the fourth valve EV4 which is fully opened from the liquid pipe 25L, flows through the subcooling heat exchanger 159 and the fourth refrigerant pipe P4, and flows into the first header pipe 155.

[0104] The refrigerant flowing into the liquid pipe 25L from the second outdoor unit 42 also flows into the first header pipe 155. The refrigerant flowing into the first header pipe 155 passes through the fourth refrigerant pipe P4, the subcooling heat exchanger 159, and the utilization side liquid pipe 162 of the cooling side switching unit 57, is depressurized by the fourth valve EV4 with the opening adjusted, and then flows into the cooling side indoor unit 30 through the liquid pipe 25L. At this time, the refrigerant passing through the subcooling heat exchanger 159 branches from the fourth refrigerant pipe P4, flows through the fifth refrigerant pipe P5, and is subcooled by the refrigerant depressurized by the third valve EV3.

[0105] The refrigerant flowing into the indoor unit 30 on the cooling side evaporates in the indoor heat exchanger 31 to cool the interior of the room. The evaporated refrigerant flows through the gas pipe 25G, enters the utilization-side gas pipe 161 of the cooling-side switching unit 57, flows through the second valve EV2, enters the third refrigerant pipe P3 and the third header pipe 157, flows through the suction gas pipe 25G2, enters the accumulator 104, and is sucked into the compressor 105.

[0106] (Regarding the distance from the indoor unit to the valve unit) When the fourth valve EV4 of the refrigerant flow path switching unit 55 is used as the pressure control valve PV, the distance L2 (see FIG. 1B) from the indoor unit 30 to the refrigerant flow path switching unit 55 affects the performance of the second air conditioner 22. In other words, the control characteristics of the second air conditioner 22 change according to the distance L2 from the indoor unit 30 to the refrigerant flow path switching unit 55. If the distance L2 from the indoor unit 30 to the refrigerant flow path switching unit 55 is too large, it becomes impossible to ensure the desired performance for the second air conditioner 22. In the second air conditioning system 12, the distance L2 from the indoor unit 30 to the refrigerant flow path switching unit 55 is 20 m or less. Thereby, the desired performance can be ensured for the second air conditioner 22.

[0107] (Modification example of the second air conditioning system) FIG. 2B is a schematic configuration diagram of a modification example of the air conditioning system according to the second embodiment of the present disclosure. As shown in FIG. 2B, in the second air conditioner 22, the refrigerant flow path switching unit 55 may be directly attached to the indoor unit 30. Specifically, the casing 57a of the switching unit 57 may be directly attached to the casing 30a of the indoor unit 30. In this case, the distance L2 (see FIG. 1B) from the indoor unit 30 to the refrigerant flow path switching unit 55 becomes "0". In the second air conditioning system 12 configured in this way, the distance L2 from the indoor unit 30 to the refrigerant flow path switching unit 55 is surely 20 m or less. Regardless of the construction situation at the site, thereby, the desired performance can surely be ensured for the second air conditioner 22.

[0108] (Regarding the third air conditioning system) FIG. 7 is a refrigerant circuit diagram of the air conditioning system according to the third embodiment of the present disclosure. FIG. 8 is a block diagram of the air conditioning system according to the third embodiment of the present disclosure. As shown in FIGS. 1C, 7, and 8, the third air conditioning system 13 includes a third air conditioner 23. The third air conditioner 23 includes an indoor unit 30, a second outdoor unit 42, and a plurality of valve units 50 (a shut-off valve unit 51 and a refrigerant flow path switching unit 55). Since the third air conditioner 23 uses a refrigerant having flammability (for example, R32 having slight flammability) as the refrigerant, a shut-off valve unit 51 for shutting off the refrigerant supplied to the indoor unit 30 is provided. The third air conditioner 23 is different from the second air conditioner 22 in that it includes the shut-off valve unit 51. In other words, the third air conditioner 23 is common to the second air conditioner 22 in terms of the configuration other than the shut-off valve unit 51. In the third air conditioner 23 shown in FIGS. 7 and 8, the parts having the same configuration as those of the second air conditioner 22 are denoted by the same reference numerals, and the description of the common parts is omitted unless otherwise particularly described.

[0109] (Regarding the control unit of the third air conditioning system) In the third air conditioning system 13, the control unit 60 includes a second outdoor control unit 61B, an indoor control unit 62, a shut-off valve control unit 63, and a flow path switching control unit 64. The second outdoor control unit 61B, the indoor control unit 62, the shut-off valve control unit 63, and the flow path switching control unit 64 are communicably connected to each other via a transmission line.

[0110] When a refrigerant sensor (not shown) provided in the indoor unit 30 detects the refrigerant during the system operation in the third air conditioning system 13, the first electric valve 52 and the second electric valve 53 are closed to shut off the supply of the refrigerant to the indoor unit 30.

[0111] In the third air conditioning system 13, the fourth valve EV4 is used as a pressure control valve PV. In the present embodiment, the flow path switching control unit 64 adjusts the opening degree of the fourth valve EV4 based on the detection values of the respective sensors (not shown) of the indoor unit 30 and the first outdoor unit 41 to control the pressure of the refrigerant supplied to the indoor unit 30.

[0112] In the second air conditioning system 12, the first motor-operated valve 52 may be used as the pressure control valve PV. In this case, the shutoff valve control unit 63 adjusts the opening degree of the first motor-operated valve 52 based on the detection values of various sensors (not shown) included in the indoor unit 30 and the first outdoor unit 41, and controls the pressure of the refrigerant supplied to the indoor unit 30. In the fourth air conditioning system 14, by using the fourth valve EV4 of the refrigerant flow path switching unit 55 or the first motor-operated valve 52 of the shutoff valve unit 51 as the control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30, it is possible to use the indoor unit 30 that does not have a motor-operated valve (indoor expansion valve) inside.

[0113] (Regarding the distance from the indoor unit to the valve unit) In the third air conditioning system 13, either the first motor-operated valve 52 of the shutoff valve unit 51 or the fourth valve EV4 of the refrigerant flow path switching unit 55 can be used as the pressure control valve PV. When the third air conditioning system 13 uses the first motor-operated valve 52 as the pressure control valve PV, the distance L1 (see FIG. 1C) from the indoor unit 30 to the shutoff valve unit 51 is 20 m or less. When the fourth valve EV4 is used as the pressure control valve PV, the distance L2 (see FIG. 1C) from the indoor unit 30 to the refrigerant flow path switching unit 55 is 20 m or less. Thereby, the desired performance can be ensured for the third air conditioner 23.

[0114] (Regarding the fourth air conditioning system) FIG. 9 is a refrigerant circuit diagram of an air conditioning system according to a fourth embodiment of the present disclosure. FIG. 10 is a block diagram of the air conditioning system according to the fourth embodiment of the present disclosure. As shown in FIGS. 9 and 10, the fourth air conditioning system 14 includes a fourth air conditioner 24. The fourth air conditioner 24 includes an indoor unit 30, a second outdoor unit 42, and a plurality of refrigerant flow path switching units 58. The refrigerant flow path switching unit 58 includes a switching unit 59 having a fifth valve EV5. The refrigerant flow path switching unit 58 is different from the above-described refrigerant flow path switching unit 55 in that it includes the fifth valve EV5. In other words, the fourth air conditioner 24 is common to the second air conditioner 22 in terms of the configuration other than the refrigerant flow path switching unit 58. In the fourth air conditioner 24 shown in FIGS. 9 and 10, the same reference numerals are given to the portions having the same configuration as the second air conditioner 22, and the description of the common portions is omitted unless otherwise specified.

[0115] In the fourth air conditioning system 14, the valve unit 50 is a refrigerant flow path switching unit 55 that individually switches the flow of refrigerant to the plurality of indoor units 30. In the utilization-side liquid pipe 162, a fifth valve that is a pressure control valve PV is connected in series with a fourth valve EV4 that is a liquid-side electric valve of the refrigerant flow path switching unit 55.

[0116] (Regarding the control unit of the fourth air conditioning system) In the fourth air conditioning system 14, the control unit 60 includes a second outdoor control unit 61B, an indoor control unit 62, and a flow path switching control unit 64. The second outdoor control unit 61B, the indoor control unit 62, and the flow path switching control unit 64 are communicably connected to each other via a transmission line. In the fourth air conditioning system 14, a fifth valve EV5 provided in the refrigerant flow path switching unit 55 separately from the fourth valve EV4 is used as a pressure control valve PV.

[0117] The flow path switching control unit 64 adjusts the opening degree of the fifth valve EV5 based on the detection values of various sensors (not shown) provided in the indoor unit 30 and the second outdoor unit 42, and controls the pressure of the refrigerant supplied to the indoor unit 30. In the fourth air conditioning system 14, by using the fifth valve EV5 of the refrigerant flow path switching unit 55 (valve unit 50) as a control valve for adjusting the pressure of the refrigerant supplied to the indoor unit 30, it becomes possible to use the indoor unit 30 that does not have an electric valve (indoor expansion valve) inside.

[0118] [Operation and Effect of Embodiment] (1) The air conditioning system 10 of the present disclosure is an air conditioning system including refrigerant circuits RC1 and RC2 that perform a refrigeration cycle, an outdoor unit 40, and a plurality of indoor units 30 connected in parallel to the outdoor unit 40. The air conditioning system 10 includes a refrigerant pipe 25 including a liquid pipe 25L and a gas pipe 25G that connect the indoor unit 30 and the outdoor unit 40, a valve unit 50 provided in the middle of the refrigerant pipe 25, and a pressure control valve PV (first electric valve 52 or fourth valve EV4) provided in the valve unit 50 for adjusting the pressure of the refrigerant flowing through the liquid pipe 25L, and the distance from the indoor unit 30 to the valve unit 50 is 20 m or less.

[0119] When the refrigerant supplied to the indoor unit 30 is controlled by the electric valve (first electric valve 52 or fourth valve EV4) of the valve unit 50, the control characteristics of the electric valve (first electric valve 52 or fourth valve EV4) change according to the distance from the indoor unit 30 to the valve unit 50. According to the air conditioning system 10 of this configuration, by limiting the distances L1 and L2 from the indoor unit 30 to the valve unit 50 to 20 m or less, the change in the control characteristics of the electric valve (first electric valve 52 or fourth valve EV4) can be suppressed within an allowable range in which the desired performance of the air conditioner 20 can be ensured. Thereby, the desired performance can be ensured for the air conditioner 20.

[0120] (2) In the second air conditioning system 12 and the third air conditioning system 13 of the present disclosure, the valve unit 50 is a refrigerant flow path switching unit 55 that individually switches the flow of the refrigerant to a plurality of indoor units 30, and the pressure control valve PV is the fourth valve EV4 that is a liquid-side electric valve included in the refrigerant flow path switching unit 55.

[0121] In this case, the fourth valve EV4 of the refrigerant flow path switching unit 55 can be used as a pressure control valve PV that controls the pressure of the refrigerant supplied to the indoor unit 30. Thereby, it is not necessary to separately provide the pressure control valve PV, and an increase in the cost of the air conditioning system 10 can be suppressed.

[0122] (3) In the fourth air conditioning system 14 of the present disclosure, the valve unit 50 is a refrigerant flow path switching unit 55 that individually switches the flow of the refrigerant to the plurality of indoor units 30, and the fifth valve EV5, which is a pressure control valve PV, is connected in series with the fourth valve EV4, which is a liquid side motor-operated valve of the refrigerant flow path switching unit 55.

[0123] In this case, the fifth valve EV5 provided in the refrigerant flow path switching unit 55 separately from the fourth valve EV4, which is the liquid side motor-operated valve of the refrigerant flow path switching unit 55, can control the pressure of the refrigerant supplied to the indoor unit 30.

[0124] (4) In the air conditioning system 10 of the present disclosure, the indoor unit 30 further includes an indoor control unit 62 that controls the operation of the indoor unit 30, and the valve unit 50 further includes a control unit (shut-off valve control unit 63 or flow path switching control unit 64) that controls the operation of the valve unit 50, and the pressure control valve PV (first motor-operated valve 52 or fourth valve EV4) is controlled based on information sent from the indoor control unit 62 to the control unit (shut-off valve control unit 63 or flow path switching control unit 64).

[0125] In this case, the pressure control valve PV (first motor-operated valve 52 or fourth valve EV4) can be controlled based on the indoor information detected by the indoor unit 30.

[0126] (5) In the air conditioning system 10 of the present disclosure, the valve unit 50 (casing 51a, 57a) is directly fixed to the casing 30a of the indoor unit 30.

[0127] In this case, the distance from the indoor unit 30 to the valve unit 50 can be made constant. As a result, the distances L1 and L2 from the indoor unit 30 to the valve unit 50 can surely be made 20 m or less.

[0128] (6) In the first air conditioning system 11 of the present disclosure, the pressure control valve PV is a shut-off valve (the first electric valve 52 or the fourth valve EV4) that can shut off the flow of the refrigerant in the liquid pipe 25L.

[0129] In this case, by using the shut-off valve (the first electric valve 52 or the fourth valve EV4) as the pressure control valve PV, it is not necessary to separately provide the pressure control valve PV, and an increase in the cost of the first air conditioning system 11 can be suppressed.

[0130] Note that the present disclosure is not limited to the above examples, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0131] 10: Air conditioning system 11: First air conditioning system 12: Second air conditioning system 13: Third air conditioning system 14: Fourth air conditioning system 25L: Liquid pipe (liquid side pipe) 25G: Gas pipe (gas side pipe) 25G1: High and low pressure gas pipe (gas side pipe) 25G2: Suction gas pipe (gas side pipe) 30: Indoor unit 30a: Casing 40: Outdoor unit 50: Valve unit 51: Shut-off valve unit 51a: Casing 52: First electric valve (second control valve) 55: Refrigerant flow path switching unit 57a: Casing 60: Control unit 63: Shut-off valve control unit (second control unit) 64: Flow path switching control unit (second control unit) 62: Indoor control unit (first control unit) 84: Outdoor expansion valve (first control valve) 110: First outdoor expansion valve (first control valve) 111: Second outdoor expansion valve (first control valve) EV4: Fourth valve (second control valve) EV5: Fifth valve (second control valve) PV: Pressure control valve RC1: Refrigerant circuit RC2: Refrigerant circuit

Claims

1. An air conditioning system (10) including a refrigerant circuit (RC1, RC2) performing a refrigeration cycle, an outdoor unit (40), and a plurality of indoor units (30) connected in parallel to the outdoor unit (40), a refrigerant pipe (25) including a liquid side pipe (25L) and gas side pipes (25G, 25G1, 25G2) connecting the indoor unit (30) and the outdoor unit (40), a valve unit (50) provided in the middle of the refrigerant pipe (25), a pressure control valve (PV) provided in the valve unit (50) for adjusting the pressure of the refrigerant flowing through the liquid side pipe (25L), wherein the valve unit (50) is a refrigerant flow path switching unit (55) for individually switching the flow of the refrigerant to the plurality of indoor units (30), the pressure control valve (PV) is a liquid side electric valve (EV4) of the refrigerant flow path switching unit (55), and the distance (L1, L2) from the indoor unit (30) to the valve unit (50) is 20 m or less. The air conditioning system (10).

2. An air conditioning system (10) including a refrigerant circuit (RC1, RC2) performing a refrigeration cycle, an outdoor unit (40), and a plurality of indoor units (30) connected in parallel to the outdoor unit (40), a refrigerant pipe (25) including a liquid side pipe (25L) and gas side pipes (25G, 25G1, 25G2) connecting the indoor unit (30) and the outdoor unit (40), a valve unit (50) provided in the middle of the refrigerant pipe (25), a pressure control valve (EV5) provided in the valve unit (50) for adjusting the pressure of the refrigerant flowing through the liquid side pipe (25L), the distance (L1, L2) from the indoor unit (30) to the valve unit (50) is 20 m or less, the valve unit (50) is a refrigerant flow path switching unit (55) for individually switching the flow of the refrigerant to the plurality of indoor units (30), and the pressure control valve (EV5) is connected in series with a liquid side electric valve (EV4) of the refrigerant flow path switching unit (55). The air conditioning system (14).

3. The indoor unit (30) further includes a first control unit (62) for controlling the operation of the indoor unit (30), and the valve unit (50) further includes a second control unit (63, 64) for controlling the operation of the valve unit (50). The air conditioning system (10) according to claim 1, wherein the pressure control valve (PV) is controlled based on information sent from the first control unit (62) to the second control units (63, 64).

4. The indoor unit (30) further includes a first control unit (62) that controls the operation of the indoor unit (30), and the valve unit (50) further includes second control units (63, 64) that control the operation of the valve unit (50), The air conditioning system (10) according to claim 2, wherein the pressure control valve (EV5) is controlled based on information sent from the first control unit (62) to the second control units (63, 64).

5. The air conditioning system (10) according to claims 1 to 4, wherein the valve unit (50) is directly fixed to the casing (30a) of the indoor unit (30).

6. The air conditioning system (10) according to claim 1 or claim 3, wherein the pressure control valve (PV) is a shut-off valve (52, EV4) capable of shutting off the flow of the refrigerant in the liquid side pipe (25L).

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