Air conditioning system and its branch unit shut-off valve opening and closing test method

Abstract

An air conditioning system and its branch unit shut-off valve opening and closing detection method help prevent high-pressure refrigerant discharged from the compressor from accumulating at a certain point in the connecting pipe due to the refrigerant circuit's inability to circulate, thereby causing system failures such as liquid seal and connecting pipe rupture. The air conditioning system of this invention includes an outdoor unit and multiple indoor units. The multiple indoor units are connected to the outdoor unit via gas-side connecting pipes and liquid-side connecting pipes, respectively. The outdoor unit is connected to the gas-side connecting pipes and the liquid-side connecting pipes via liquid-side and gas-side shut-off valves, respectively. The multiple indoor units include: a first indoor unit, which is connected to the liquid-side connecting pipe via a liquid-side branch unit shut-off valve and to the gas-side connecting pipe via a gas-side branch unit shut-off valve; and a second indoor unit, which is not connected to the liquid-side connecting pipe and the gas-side connecting pipe via a branch unit shut-off valve.

Description

Technical Field

[0001] This invention relates to an air conditioning system and a method for detecting the opening and closing of the shut-off valve of its sub-unit. Background Technology

[0002] Currently, many places such as shopping malls and office buildings are equipped with air conditioning systems that include an outdoor unit and multiple indoor units connected to the outdoor unit via connecting pipes. These air conditioning systems generally adopt a structure in which the outdoor unit and each indoor unit are connected to the connecting pipes via shut-off valves.

[0003] However, in the aforementioned air conditioning system, if all shut-off valves are closed, the refrigerant circuit will not be able to circulate. In this case, if the compressor is working, the high-pressure refrigerant discharged by the compressor will accumulate at a certain point in the connecting pipe. Once the pressure of the accumulated refrigerant exceeds the pressure that the connecting pipe can withstand, it will cause system failures such as liquid seal failure and pipe rupture. Summary of the Invention

[0004] This invention addresses the aforementioned problems and aims to provide a method for detecting the opening and closing of an air conditioning system and its unit shut-off valve. This method helps prevent high-pressure refrigerant discharged from the compressor from accumulating in the piping due to the refrigerant circuit's inability to circulate, thus avoiding system malfunctions such as liquid seal failure and piping rupture. Furthermore, this invention also aims to provide a simple method for detecting the opening and closing of the unit shut-off valve.

[0005] To achieve the above objectives, the present invention provides an air conditioning system, including an outdoor unit and multiple indoor units. The multiple indoor units are respectively connected to the outdoor unit via a liquid-side connecting pipe (as a first piping) and a gas-side connecting pipe (as a second piping). The outdoor unit is connected to the liquid-side connecting pipe and the gas-side connecting pipe via liquid-side and gas-side shut-off valves, respectively. The multiple indoor units include: a first indoor unit, which is connected to the liquid-side connecting pipe via a liquid-side branch shut-off valve and to the gas-side connecting pipe via a gas-side branch shut-off valve; and a second indoor unit, which is not connected to the liquid-side connecting pipe and the gas-side connecting pipe via a branch shut-off valve.

[0006] Here, the phrase "the second indoor unit is not connected to the liquid-side connecting pipe and the gas-side connecting pipe via the branch shut-off valve" means that although the second indoor unit is connected to both the liquid-side connecting pipe and the gas-side connecting pipe, there is no shut-off valve between the second indoor unit and the liquid-side connecting pipe and the gas-side connecting pipe to control the flow and cut-off of the refrigerant.

[0007] According to the air conditioning system of the present invention, the multiple indoor units include a second indoor unit. The second indoor unit is not connected to the liquid-side connecting pipe and the gas-side connecting pipe via the branch unit shut-off valve. Therefore, even if the branch unit shut-off valves connecting the first indoor unit to the liquid-side connecting pipe and the gas-side connecting pipe are closed, as long as the outdoor unit shut-off valve is not closed, the refrigerant circuit can form a circulation through the second indoor unit. This helps to prevent the high-pressure refrigerant discharged by the compressor from accumulating at a certain point in the piping due to the inability of the refrigerant circuit to circulate, which could lead to system failures such as liquid seal and piping rupture.

[0008] Furthermore, in the air conditioning system of the present invention, preferably, the first indoor unit and the second indoor unit are also connected to the outdoor unit via a third piping, with the first indoor unit connected to the third piping via a branch shut-off valve on the third piping side. In this case, it is preferable that the second indoor unit is not connected to the third piping via a branch shut-off valve, thereby further helping to avoid the high-pressure refrigerant discharged from the compressor accumulating at a certain point in the piping due to the refrigerant circuit not being able to circulate, which could lead to system failures such as liquid seal and piping rupture.

[0009] Furthermore, in the air conditioning system of the present invention, it is preferable that the first indoor unit is connected to the outdoor unit only through the liquid-side connecting pipe and the gas-side connecting pipe, and the second indoor unit is also connected to the outdoor unit through a third pipe. In this case, it is preferable that the second indoor unit is not connected to the third pipe via the branch shut-off valve, thereby helping to avoid the high-pressure refrigerant discharged from the compressor accumulating at a certain point in the pipe due to the refrigerant circuit not being able to circulate, which could lead to system failures such as liquid seal and pipe rupture.

[0010] Furthermore, in the air conditioning system of the present invention, the branch unit shut-off valve is preferably disposed between the first indoor unit and the outdoor unit by welding or threaded connection.

[0011] According to the air conditioning system of the present invention, the branch unit shut-off valve is installed between the first indoor unit and the outdoor unit by welding or threaded connection. Therefore, it is easy to reliably install the branch unit shut-off valve between the first indoor unit and the outdoor unit to ensure that the refrigerant circuit can operate stably.

[0012] Furthermore, in the air conditioning system of the present invention, preferably the liquid-side connecting pipe includes a liquid-side main pipe and a liquid-side branch pipe branched from the liquid-side main pipe via a liquid-side branching device, the gas-side connecting pipe includes a gas-side main pipe and a gas-side branch pipe branched from the gas-side main pipe via a gas-side branching device, and the indoor unit is connected to the gas-side branch pipe and the liquid-side branch pipe respectively.

[0013] According to the air conditioning system of the present invention, the liquid-side connecting pipe includes a liquid-side main pipe and a liquid-side branch pipe branched from the liquid-side main pipe via a liquid-side branching device, and the gas-side connecting pipe includes a gas-side main pipe and a gas-side branch pipe branched from the gas-side main pipe via a gas-side branching device. The indoor unit is connected to the gas-side branch pipe and the liquid-side branch pipe respectively, so multiple indoor units can be easily connected.

[0014] Furthermore, in the air conditioning system of the present invention, the branch unit shut-off valve is preferably disposed between the branch device and the first indoor unit.

[0015] According to the air conditioning system of the present invention, the branch unit shut-off valve is located between the branch device and the first indoor unit. Therefore, even if it is necessary to close the branch unit shut-off valve in order to move or replace the first indoor unit or add a new indoor unit nearby, other parts of the refrigerant circuit of the air conditioning system are not easily affected. Furthermore, by closing the branch unit shut-off valve corresponding to the refrigerant pipeline of the first indoor unit, it is easy to evacuate the refrigerant pipeline of the first indoor unit, thereby improving the operating efficiency.

[0016] Furthermore, in the air conditioning system of the present invention, the third piping preferably includes a main pipe and a branch pipe branching off from the main pipe via a branching device on the third piping side, and the indoor unit is connected to the branch pipe.

[0017] According to the air conditioning system of the present invention, the third piping includes a main pipe and a branch pipe branching off from the main pipe via a branching device on the third piping side. The indoor unit is connected to the branch pipe, thus enabling convenient connection of a three-pipe indoor unit.

[0018] Furthermore, in the air conditioning system of the present invention, the unit shut-off valve preferably has a refrigerant injection port and a valve core for controlling the opening and closing of the refrigerant passage.

[0019] According to the air conditioning system of the present invention, the branch unit shut-off valve has a refrigerant charging port that is connected to the refrigerant pipeline of the first indoor unit, and has a valve core that controls whether the refrigerant charging port is connected to the outside. Therefore, when it is necessary to move or replace the first indoor unit, after closing the branch unit shut-off valve at the end of the refrigerant pipeline of the first indoor unit, the valve core is switched to the state that the refrigerant charging port is connected to the outside. This allows the refrigerant pipeline of the first indoor unit to be easily evacuated through the refrigerant charging port using an external suction device, which easily improves the work efficiency.

[0020] Furthermore, in the air conditioning system of the present invention, preferably the first indoor unit is connected to the liquid-side connecting pipe via a series of sequentially arranged liquid-side branch unit devices and a liquid-side branch unit shut-off valve, and the first indoor unit is connected to the gas-side connecting pipe via a series of sequentially arranged gas-side branch unit devices and a gas-side branch unit shut-off valve. The branch unit device has a first end, a second end, and a third end. The first end of the branch unit device is connected to the first indoor unit, the second end of the liquid-side branch unit device is connected to the liquid-side branch unit shut-off valve, and the second end of the gas-side branch unit device is connected to the gas-side branch unit shut-off valve.

[0021] According to the air conditioning system of the present invention, a first indoor unit is connected to a liquid-side connecting pipe via a liquid-side branch unit and a liquid-side shut-off valve arranged in sequence. The first indoor unit is also connected to a gas-side connecting pipe via a gas-side branch unit and a gas-side shut-off valve arranged in sequence. The branch unit has a first end, a second end, and a third end. The first end of the branch unit is connected to the first indoor unit, the second end of the liquid-side branch unit is connected to the liquid-side shut-off valve, and the second end of the gas-side branch unit is connected to the gas-side shut-off valve. Therefore, other indoor units can be conveniently connected using the third end of the branch unit.

[0022] Furthermore, in the air conditioning system of the present invention, preferably, the first indoor unit is connected to the liquid-side connecting pipe via a series of sequentially arranged liquid-side branch unit devices and a liquid-side branch unit shut-off valve; the first indoor unit is connected to the gas-side connecting pipe via a series of sequentially arranged gas-side branch unit devices and a gas-side branch unit shut-off valve; the first indoor unit is connected to the third pipe via a series of sequentially arranged third pipe-side branch unit devices and a third pipe-side branch unit shut-off valve; the branch unit device has a first end, a second end, and a third end; the first end of the branch unit device is connected to the first indoor unit; the second end of the liquid-side branch unit device is connected to the liquid-side branch unit shut-off valve; the second end of the gas-side branch unit device is connected to the gas-side branch unit shut-off valve; and the second end of the third pipe-side branch unit device is connected to the third pipe-side branch unit shut-off valve.

[0023] According to the air conditioning system of the present invention, a first indoor unit is connected to a liquid-side connecting pipe via a liquid-side branch unit and a liquid-side shut-off valve arranged in sequence. The first indoor unit is also connected to a gas-side connecting pipe via a gas-side branch unit and a gas-side shut-off valve arranged in sequence. Furthermore, the first indoor unit is connected to a third pipe via a third pipe-side branch unit and a third pipe-side shut-off valve arranged in sequence. Each branch unit has a first end, a second end, and a third end. The first end of the branch unit is connected to the first indoor unit. The second end of the liquid-side branch unit is connected to the liquid-side shut-off valve, the second end of the gas-side branch unit is connected to the gas-side shut-off valve, and the second end of the third pipe-side branch unit is connected to the third pipe-side shut-off valve. Therefore, other three-pipe indoor units can be conveniently connected using the third end of the branch unit.

[0024] Furthermore, in the air conditioning system of the present invention, a foaming element is preferably provided at the branch unit.

[0025] According to the air conditioning system of the present invention, a foaming element is provided at the branch unit, so that the foaming element can be used to insulate the branch unit and prevent condensation.

[0026] Furthermore, in the air conditioning system of the present invention, preferably, the plurality of indoor units include a third indoor unit, which is connected to the third end of the branch unit.

[0027] Furthermore, in the air conditioning system of the present invention, a third indoor unit-side shut-off valve is preferably provided between the third indoor unit and the branch unit device.

[0028] According to the air conditioning system of the present invention, a third indoor unit side shut-off valve is provided between the third indoor unit and the branch unit device. Therefore, by closing the third indoor unit side shut-off valve, the third indoor unit can be easily moved or replaced without being significantly affected by other parts of the refrigerant circuit of the air conditioning system.

[0029] Furthermore, in the air conditioning system of the present invention, the unit shut-off valve is preferably a manually operated valve.

[0030] Furthermore, in the air conditioning system of the present invention, a control unit is preferably included. The first indoor unit includes a test indoor unit, which has an indoor heat exchanger, an air inlet, and a sensor. The control unit performs at least one of a first detection, a second detection, and a third detection when the test indoor unit is in heating operation, and / or performs at least one of a fourth detection, a fifth detection, and a sixth detection when the test indoor unit is in cooling or dehumidification operation. In the first detection, the control unit determines whether the difference between the liquid-side piping temperature and the gas-side piping temperature of the indoor heat exchanger detected by the sensor is below a first preset value. If the difference is below the first preset value, it determines that the unit corresponding to the test indoor unit is cut off. When the difference is greater than a first preset value, the control unit determines that the branch unit shut-off valve corresponding to the indoor unit under test is closed. In the second detection, the control unit determines whether the difference between the temperature of the airflow at the air inlet detected by the sensor and the piping temperature on the gas side of the indoor heat exchanger is below a second preset value. When the difference is below the second preset value, the control unit determines that the branch unit shut-off valve corresponding to the indoor unit under test is open. When the difference is greater than the second preset value, the control unit determines that the branch unit shut-off valve corresponding to the indoor unit under test is closed. In the third detection, the control unit determines whether the difference between the temperature of the airflow at the air inlet detected by the sensor and the piping temperature on the liquid side of the indoor heat exchanger is below a third preset value. The control unit determines whether the difference between the gas-side and liquid-side piping temperatures of the indoor heat exchanger detected by the sensor is above the fourth preset value. If the difference is above the fourth preset value, the control unit determines that the valve corresponding to the indoor unit under test is open; if the difference is less than the fourth preset value, the control unit determines that the valve corresponding to the indoor unit under test is closed. In the fifth detection, the control unit determines whether the difference between the gas-side and liquid-side piping temperatures of the indoor heat exchanger detected by the sensor is above the fourth preset value. The control unit determines whether the temperature difference between the airflow temperature at the inlet and the piping temperature on the air side of the indoor heat exchanger detected by the sensor is greater than or equal to a fifth preset value. If the difference is greater than or equal to the fifth preset value, it determines that the shut-off valve of the indoor unit corresponding to the indoor unit under test is open; if the difference is less than the fifth preset value, it determines that the shut-off valve of the indoor unit corresponding to the indoor unit under test is closed. In the sixth detection, the control unit determines whether the temperature difference between the airflow temperature at the inlet and the piping temperature on the liquid side of the indoor heat exchanger detected by the sensor is greater than or equal to a sixth preset value. If the difference is greater than or equal to the sixth preset value, it determines that the shut-off valve of the indoor unit corresponding to the indoor unit under test is open; if the difference is less than the sixth preset value, it determines that the shut-off valve of the indoor unit under test is closed.It is determined that the shut-off valve of the indoor unit corresponding to the tested indoor unit is closed.

[0031] Furthermore, to achieve the above objectives, the present invention provides a method for detecting the opening and closing of a branch unit shut-off valve in an air conditioning system. The method detects the opening and closing of the branch unit shut-off valve in the air conditioning system. The first indoor unit includes a test indoor unit, which has an indoor heat exchanger and an air inlet. When the test indoor unit is in heating operation, at least one of a first detection, a second detection, and a third detection is performed, and / or, when the test indoor unit is in cooling or dehumidification operation, at least one of a fourth detection, a fifth detection, and a sixth detection is performed. In the first detection, it is determined whether the difference between the liquid-side piping temperature and the gas-side piping temperature of the indoor heat exchanger is below a first preset value. If the difference is below the first preset value... The following steps are performed: First, it is determined that the shut-off valve corresponding to the indoor unit under test is open. Second, it is determined that the shut-off valve corresponding to the indoor unit under test is closed when the difference is greater than a first preset value. In the second detection, it is determined whether the difference between the temperature of the airflow at the air inlet and the piping temperature on the gas side of the indoor heat exchanger is below a second preset value. If the difference is below the second preset value, it is determined that the shut-off valve corresponding to the indoor unit under test is open. If the difference is greater than the second preset value, it is determined that the shut-off valve corresponding to the indoor unit under test is closed. In the third detection, it is determined whether the difference between the temperature of the airflow at the air inlet and the piping temperature on the liquid side of the indoor heat exchanger is... The system performs a judgment based on whether the difference between the gas-side and liquid-side piping temperatures of the indoor heat exchanger is above a third preset value. If the difference is above the third preset value, the system is determined to have the valve corresponding to the indoor unit under test open; if the difference is below the fourth preset value, the valve is determined to be closed. In the fourth detection, the system judges whether the difference between the gas-side and liquid-side piping temperatures of the indoor heat exchanger is above a fourth preset value. If the difference is above the fourth preset value, the system is determined to have the valve corresponding to the indoor unit under test open; if the difference is below the fourth preset value, the valve is determined to be closed. In the fifth detection, the system judges whether the temperature of the airflow at the air inlet is above the fourth preset value. The sixth detection method determines whether the temperature difference between the air-side piping of the indoor heat exchanger is greater than or equal to a fifth preset value. If the difference is greater than or equal to the fifth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is open. If the difference is less than the fifth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is closed.

[0032] It should be noted that in the air conditioning system branch shut-off valve opening and closing detection method of the present invention, if the second detection is performed when the indoor unit under test is in heating operation and the fifth detection is performed when the indoor unit under test is in cooling or dehumidification operation, the detection accuracy can be improved, and therefore it is particularly preferred.

[0033] Furthermore, the air conditioning system branch shut-off valve opening and closing detection method of the present invention preferably includes: an operation mode judgment step, which judges the operation mode of the indoor unit under test; a detection counting step, in which, when the operation mode judgment step determines that the indoor unit under test is in heating operation, any one of the first detection, the second detection, and the third detection is performed, and the number of times the branch shut-off valve corresponding to the indoor unit under test is closed is counted; when the operation mode judgment step determines that the indoor unit under test is in cooling or dehumidification operation, any one of the fourth detection, the fifth detection, and the sixth detection is performed, and the number of times the branch shut-off valve corresponding to the indoor unit under test is closed is counted; and a notification judgment step, which judges whether the count value obtained by the detection counting step is greater than or equal to a preset value; when the count value is greater than or equal to the preset value, a notification indicating that the indoor unit under test has malfunctioned is issued; and when the count value is less than the preset value, the process returns to the operation mode judgment step.

[0034] Furthermore, in the method for detecting the opening and closing of the branch shut-off valve of the air conditioning system of the present invention, it is preferable that the indoor unit to be tested is an indoor unit that has been moved, or an indoor unit that has undergone an expansion operation and a newly added indoor unit corresponding to that indoor unit.

[0035] Furthermore, to achieve the above objectives, the present invention provides a method for detecting the opening and closing of a branch unit shut-off valve in an air conditioning system. The air conditioning system includes an outdoor unit and an indoor unit. The indoor unit is connected to the outdoor unit via a liquid-side connecting pipe (as a first pipe) and a gas-side connecting pipe (as a second pipe). The outdoor unit is connected to the liquid-side connecting pipe and the gas-side connecting pipe via liquid-side and gas-side outdoor unit shut-off valves, respectively. The indoor unit is connected to the liquid-side connecting pipe via a branch unit shut-off valve on the liquid side and to the gas-side connecting pipe via a branch unit shut-off valve on the gas side. The indoor unit has an indoor heat exchanger and an air inlet. When the indoor unit is in heating operation, a first detection, a second detection, and a third detection are performed. At least one of the three detections, and / or at least one of the fourth, fifth, and sixth detections performed when the indoor unit is in cooling or dehumidification operation. In the first detection, it is determined whether the difference between the liquid-side piping temperature and the gas-side piping temperature of the indoor heat exchanger is below a first preset value. If the difference is below the first preset value, it is determined that the unit shut-off valve is open; if the difference is greater than the first preset value, it is determined that the unit shut-off valve is closed. In the second detection, it is determined whether the difference between the airflow temperature at the air inlet and the gas-side piping temperature of the indoor heat exchanger is below a second preset value. If the difference is below the second preset value, it is determined that the unit shut-off valve is closed. The unit shut-off valve is open when the temperature difference is greater than a second preset value, and closed when the temperature difference is greater than a second preset value. In the third detection, it is determined whether the temperature difference between the airflow temperature at the air inlet and the liquid-side piping temperature of the indoor heat exchanger is below a third preset value. If the difference is below the third preset value, the unit shut-off valve is determined to be open; if the difference is greater than the third preset value, the unit shut-off valve is determined to be closed. In the fourth detection, it is determined whether the temperature difference between the gas-side piping temperature and the liquid-side piping temperature of the indoor heat exchanger is above a fourth preset value. If the difference is above the fourth preset value, the unit shut-off valve is determined to be open; if the difference is less than the fourth preset value, the unit shut-off valve is determined to be closed. When the temperature difference between the airflow temperature at the air inlet and the piping temperature on the air side of the indoor heat exchanger is greater than or equal to a fifth preset value, the unit shut-off valve is determined to be open. If the difference is less than the fifth preset value, the unit shut-off valve is determined to be closed. In the sixth detection, the temperature difference between the airflow temperature at the air inlet and the piping temperature on the liquid side of the indoor heat exchanger is determined to be greater than or equal to a sixth preset value. If the difference is greater than the sixth preset value, the unit shut-off valve is determined to be open. If the difference is less than the sixth preset value, the unit shut-off valve is determined to be closed.

[0036] (Invention Effects)

[0037] According to the present invention, the multiple indoor units include a second indoor unit. The second indoor unit is not connected to the liquid-side and gas-side connecting pipes via a branch unit shut-off valve. Therefore, even if all branch unit shut-off valves connecting the first indoor unit to the liquid-side and gas-side connecting pipes are closed, the refrigerant circuit can circulate through the second indoor unit as long as the outdoor unit shut-off valve is not closed. This helps to prevent the high-pressure refrigerant discharged from the compressor from accumulating at a certain point in the piping due to the inability of the refrigerant circuit to circulate, which could lead to system failures such as liquid seal and piping rupture. Furthermore, according to the present invention, at least one of the first, second, and third detections is performed when the indoor unit is in heating operation, and / or at least one of the fourth, fifth, and sixth detections is performed when the indoor unit is in cooling or dehumidification operation. Therefore, the opening and closing of the branch unit shut-off valves can be detected in a simple way, ensuring the normal operation of the system and preventing the corresponding indoor unit from failing to operate due to forgetting to open the corresponding branch unit shut-off valve after closing it when moving, replacing, or adding a new indoor unit nearby. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of an air conditioning system according to an embodiment of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line.

[0039] Figure 2 This is a schematic diagram illustrating the operation of adding air conditioning units to an air conditioning system according to an embodiment of the present invention.

[0040] Figure 3 It is Figure 2 The diagram shows a magnified partial view of the branch device near the branch unit between the first indoor unit and the branch unit shut-off valve, as specified in the regulations.

[0041] Figure 4 This is a flowchart illustrating an example of a method for detecting the opening and closing of a unit shut-off valve in an air conditioning system according to an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram of an air conditioning system according to a modified example of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line.

[0043] Figure 6 This is a schematic diagram illustrating the operation of adding units to an air conditioning system according to a variation of the present invention.

[0044] Figure 7 This is a circuit diagram of an air conditioning system illustrating another variation of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line, and the sensors of the indoor unit are not shown.

[0045] Figure 8This is a schematic diagram illustrating the operation of adding an air conditioning system according to another variation of the present invention, wherein the sensors of the indoor unit are not shown.

[0046] Figure 9 This is a circuit diagram of an air conditioning system used to illustrate another variation of the present invention.

[0047] Figure 10 This is a flowchart illustrating another example of the method for detecting the opening and closing of the unit shut-off valve in an air conditioning system according to an embodiment of the present invention.

[0048] Figure 11 This is a flowchart illustrating yet another example of the method for detecting the opening and closing of the unit shut-off valve in an air conditioning system according to an embodiment of the present invention.

[0049] Figure 12 This is a flowchart illustrating yet another example of the method for detecting the opening and closing of the unit shut-off valve in an air conditioning system according to an embodiment of the present invention.

[0050] (Symbol Explanation)

[0051] 100 outdoor unit

[0052] 110 compressor

[0053] 120 Outdoor Heat Exchanger

[0054] 130 outdoor fan

[0055] 140 Supercooler

[0056] 150 storage tanks

[0057] 160 capillary

[0058] VF1 Four-Way Valve

[0059] VF2 Four-Way Valve

[0060] VC1 First outdoor flow regulating valve

[0061] VC2 Second Outdoor Flow Control Valve

[0062] PO1 discharge pipe

[0063] PO2 piping

[0064] P03 Inhalation Tube

[0065] P04 Piping

[0066] PO5 piping

[0067] PO6 branch pipe

[0068] P07 Piping

[0069] PO8 piping

[0070] 200 indoor units

[0071] 200A First Indoor Unit

[0072] 210A Indoor Heat Exchanger

[0073] 220A Indoor Fan

[0074] 230A Indoor Heat Exchanger

[0075] VC3A Indoor Flow Control Valve

[0076] VC4A Indoor Flow Control Valve

[0077] PI1A refrigerant piping

[0078] PI2A refrigerant piping

[0079] 200B Second Indoor Unit

[0080] 210B Indoor Heat Exchanger

[0081] 220B Indoor Fan

[0082] 230B Indoor Heat Exchanger

[0083] VC3B Indoor Flow Control Valve

[0084] VC4B Indoor Flow Control Valve

[0085] PI1B refrigerant piping

[0086] PI2B refrigerant piping

[0087] VO1 liquid-side outdoor unit shut-off valve

[0088] VO2 gas-side outdoor unit shut-off valve

[0089] VO3 Outdoor unit shut-off valve on the third piping side

[0090] VI1 Liquid-side shut-off valve

[0091] VI2 Gas-side unit shut-off valve

[0092] VI3 Third piping side branch shut-off valve

[0093] VI1C Third Indoor Unit Liquid Side Shut-off Valve

[0094] VI2C Third Indoor Unit Side Air Shut-off Valve

[0095] P1 Liquid-side connection piping

[0096] P2 gas-side connection piping

[0097] P3 Third Piping

[0098] 301 Liquid-side branching device

[0099] 302 Gas-side branching device

[0100] 303 Branching device on the third piping side

[0101] 401 Extension Branch Unit

[0102] 402 Extension Branch Unit

[0103] 403 Extension Branch Unit

[0104] Points K1, K2, and K3 Detailed Implementation

[0105] The air conditioning system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0106] Figure 1 This is a schematic diagram of an air conditioning system according to an embodiment of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line. Figure 2 This is a schematic diagram illustrating the operation of adding air conditioning units according to an embodiment of the present invention. Figure 3 It is Figure 2 The diagram shows a magnified partial view of the area near the branch unit device between the first indoor unit and the branch unit shut-off valve, as specified in the regulations. Figure 4 This is a flowchart illustrating an example of a method for detecting the opening and closing of a unit shut-off valve in an air conditioning system according to an embodiment of the present invention.

[0107] 1) Overall structure of the air conditioning system

[0108] like Figure 1 As shown, the air conditioning system includes an outdoor unit 100 and multiple indoor units 200. The multiple indoor units 200 are connected to the outdoor unit 100 via a liquid-side connecting pipe P1 (as a first piping) and a gas-side connecting pipe P2 (as a second piping). The outdoor unit 100 is connected to the liquid-side connecting pipe P1 and the gas-side connecting pipe P2 via liquid-side and gas-side shut-off valves VO1 and VO2, respectively. Furthermore, as... Figure 1 As shown, the multiple indoor units 200 include: a first indoor unit 200A, which is connected to the liquid-side connecting pipe P1 via the liquid-side branch shut-off valve VI1 and to the gas-side connecting pipe P2 via the gas-side branch shut-off valve VI2; and a second indoor unit 200B, which is not connected to the liquid-side connecting pipe P1 and the gas-side connecting pipe P2 via the branch shut-off valve.

[0109] Although not shown in the diagram, the air conditioning system also includes a control unit that controls the operation of the air conditioning system.

[0110] 2) Structure of the outdoor unit

[0111] like Figure 1 As shown, the outdoor unit 100 includes a compressor 110, a four-way valve VF1, a discharge pipe PO1, a pipe PO2, a suction pipe PO3, and a pipe PO4. The discharge pipe PO1 connects the discharge side of the compressor 110 to the first port a of the four-way valve VF1. The pipe PO2 connects the second port b of the four-way valve VF1 to the liquid-side outdoor unit shut-off valve VO1. The suction pipe PO3 connects the suction side of the compressor 110 to the third port c of the four-way valve VF1. The pipe PO4 connects the fourth port d of the four-way valve VF1 to the gas-side outdoor unit shut-off valve VO2. Furthermore, the four-way valve VF1 can switch between a first state and a second state. In the first state, the four-way valve VF1 connects the first port a to the second port b and connects the third port c to the fourth port d. In the second state, the four-way valve VF1 connects the first port a to the fourth port d and connects the second port b to the third port c.

[0112] In addition, such as Figure 1 As shown, the outdoor unit 100 also includes a pipe PO5, which connects pipe PO2 to the suction pipe P03.

[0113] In addition, such as Figure 1 As shown, the outdoor unit 100 also includes an outdoor heat exchanger 120, an outdoor fan 130, a subcooler 140, a storage tank 150, a first outdoor flow regulating valve VC1, and a second outdoor flow regulating valve VC2. The outdoor heat exchanger 120 is installed on pipe PO2 for heat exchange between the refrigerant and outdoor air. The outdoor fan 130 blows air to the outdoor heat exchanger 120. The subcooler 140 is installed on pipes PO2 and PO5, and is installed on pipe PO2 at a position lower than that of the outdoor heat exchanger 120. At the location of the outdoor unit shut-off valve VO1 on the liquid side, heat exchange occurs between the refrigerant flowing through pipeline PO2 and the refrigerant flowing through pipeline PO5. The storage tank 150 is installed on the suction pipe P03 to temporarily store the refrigerant before it returns to the compressor 110. The first outdoor flow regulating valve VC1 is installed on pipeline PO2 between the outdoor heat exchanger 120 and the subcooler 140. The second outdoor flow regulating valve VC2 is installed on pipeline PO5 between the connection between pipeline PO5 and pipeline PO2 and the subcooler 140.

[0114] 3) Structure of the indoor unit

[0115] like Figure 1As shown, the first indoor unit 200A includes a refrigerant line PI1A, one end of which is connected to the liquid-side unit shut-off valve VI1, and the other end of which is connected to the gas-side unit shut-off valve VI2.

[0116] In addition, such as Figure 1 As shown, the first indoor unit 200A also includes an indoor heat exchanger 210A, an indoor fan 220A, and an indoor flow regulating valve VC3A (e.g., an electronic expansion valve, but not limited to this). The indoor heat exchanger 210A is installed on the refrigerant line PI1A to exchange heat between the refrigerant and the indoor air. The indoor fan 220A blows air to the indoor heat exchanger 210A. The indoor flow regulating valve VC3A is installed between the liquid-side unit shut-off valve VI1 and the indoor heat exchanger 210A.

[0117] In addition, such as Figure 1 As shown, the first indoor unit 200A also includes a first sensor SI1 for detecting the temperature TH1 of the airflow at the air inlet, a second sensor SI2 for detecting the temperature TH2 of the liquid side piping of the indoor heat exchanger, a third sensor SI3 for detecting the temperature TH3 of the gas side piping of the indoor heat exchanger, and a fourth sensor SI4 for detecting the temperature TH4 of the airflow at the air outlet.

[0118] In addition, such as Figure 1 As shown, the second indoor unit 200B, like the first indoor unit 200A, also includes a refrigerant line PI1B. One end of the refrigerant line PI1B (the end shown at point K1 in the figure) is connected to the liquid-side connecting pipe P1 (specifically, the liquid-side branch pipe P12 described below), and the other end of the refrigerant line PI1B (the end shown at point K2 in the figure) is connected to the gas-side connecting pipe P2 (specifically, the gas-side branch pipe P22 described below). Furthermore, like the first indoor unit 200A, the second indoor unit 200B includes an indoor flow regulating valve VC3B (e.g., an electronic expansion valve) and an indoor heat exchanger 210B installed on the refrigerant line PI1B, as well as an indoor fan 220B that supplies air to the indoor heat exchanger 210B.

[0119] In addition, Figure 1 The diagram shows two first indoor units 200A and one second indoor unit 200B (the indoor units shown by dashed lines in the diagram only indicate the location of the designated indoor unit 200X in the first indoor unit 200A after relocation), but this is just one example. The number of first indoor units 200A and second indoor units 200B can be set appropriately as needed.

[0120] 4) Structure of the connecting pipes between the outdoor unit and the indoor unit

[0121] like Figure 1As shown, the liquid-side connecting pipe P1 includes a liquid-side main pipe P11 and liquid-side branch pipes P12 (multiple of which are provided corresponding to each indoor unit) branched from the liquid-side main pipe P11 via a liquid-side branch device 301. The gas-side connecting pipe P2 includes a gas-side main pipe P21 and gas-side branch pipes P22 (multiple of which are provided corresponding to each indoor unit) branched from the gas-side main pipe P21 via a gas-side branch device 302. The indoor unit 200 is connected to the gas-side branch pipe P12 and the liquid-side branch pipe P22 respectively.

[0122] 5) Connection and structure of the branch unit shut-off valve

[0123] The unit shut-off valves VI1 and VI2 are installed, for example, between the first indoor unit 200A and the outdoor unit 100 by welding or threaded connection.

[0124] Here, as Figure 1 As shown, the branch unit shut-off valves VI1 and VI2 are located between the branch devices 301 and 302 and the first indoor unit 200A. Specifically, the liquid-side branch unit shut-off valve VI1 is located between the branch device 301 and the first indoor unit 200A, and the gas-side branch unit shut-off valve VI2 is located between the branch device 302 and the first indoor unit 200A.

[0125] Furthermore, although not illustrated, the unit shut-off valves VI1 and VI2 each have a refrigerant charging port and a valve core for controlling the opening and closing of the refrigerant passage. Specifically, the unit shut-off valves VI1 and VI2 each have a tubular main body, with both ends of the tubular main body used to connect to the refrigerant pipeline PI1 and the liquid-side connecting pipe P1 (or gas-side connecting pipe P2) of the first indoor unit 200A, respectively. A valve core for controlling the opening and closing of the refrigerant passage within the tubular main body and a refrigerant charging port for charging refrigerant are located in the middle of the tubular main body.

[0126] In addition, the branch shut-off valves VI1 and VI2 are, for example, manually operated valves.

[0127] 6) Operation of the air conditioning system

[0128] By switching the four-way valve VF1, the air conditioning system can... Figure 1 Switching between the shown cooling operation mode and the heating operation mode (not shown).

[0129] In refrigeration operation, the refrigerant discharged from the compressor 110 flows sequentially through the four-way valve VF1, the outdoor heat exchanger 120, the first outdoor flow regulating valve VC1, and the subcooler 140. Then, it flows through the liquid-side outdoor unit shut-off valve VO1 into the liquid-side connecting pipe P1 (a portion of the refrigerant flowing through the subcooler 140 flows into the suction pipe PO3 via pipe PO5, for example). It then flows sequentially through the indoor flow regulating valve VC3A (VC3B) of the indoor unit 200 and the indoor heat exchanger 210A (210B), and then into the gas-side connecting pipe P2. Finally, it flows through the gas-side outdoor unit shut-off valve VO2 and the four-way valve VF1 into the suction pipe PO3. Finally, (for example, after merging with the refrigerant flowing into the suction pipe PO3 via pipe PO5) it returns to the compressor 110 via the storage tank 150.

[0130] On the other hand, in heating operation, the refrigerant discharged from the compressor 110 flows through the four-way valve VF1, then through the outdoor unit shut-off valve VO2 on the gas side into the gas-side connecting pipe P2, and then flows through the indoor heat exchanger 210A (210B) and indoor flow regulating valve VC3A (VC3B) of the indoor unit 200 in sequence, and then flows into the liquid-side connecting pipe P1, and then returns to the compressor 110 in sequence through the outdoor unit shut-off valve VO1 on the liquid side, the subcooler 140, the first outdoor flow regulating valve VC1, the outdoor heat exchanger 120, the four-way valve VF1 and the storage tank 150.

[0131] 7) Relocation of indoor units of air conditioning systems

[0132] In air conditioning systems, it is sometimes necessary to relocate the indoor unit, for example, such as... Figure 1 As shown, the designated indoor unit 200X in the first indoor unit 200A is moved from the position shown by the solid line to the position shown by the dashed line.

[0133] The following is an explanation of the relocation procedure for the indoor unit 200X.

[0134] When relocating a specified indoor unit 200X, thorough preparations should be made before proceeding with the actual relocation.

[0135] As preparation, the following tasks should be performed in sequence:

[0136] (1) Prepare a hanger for the new location of the indoor unit 200X (i.e., the location after relocation).

[0137] (2) Prepare piping, wiring and drainage pipes according to the specified moving distance of the indoor unit 200X.

[0138] (3) After bundling the piping and wiring together, insert them from the original position to the new position.

[0139] (4) Prepare the consumables and materials needed for the relocation.

[0140] As part of the formal relocation, the following procedures shall be performed in sequence:

[0141] (1) Close the liquid-side shut-off valve of the indoor unit to enable the specified indoor unit 200X to operate in cooling mode and recover the refrigerant in the specified indoor unit 200X.

[0142] (2) After running for several minutes, close the gas-side unit shut-off valve to stop the indoor unit from operating at 200X as specified.

[0143] (3) Residual refrigerant in the refrigerant piping of the specified indoor unit 200X is recovered via a bimanifold gauge (pressure gauge) connection (both gas and liquid sides are recovered simultaneously).

[0144] (4) Power off (If the power supply to each indoor unit is independent, only the power supply to the specified indoor unit 200X to be moved can be cut off)

[0145] (5) Dismantle external wiring, conduit, and drain pipes.

[0146] (6) Remove the drain plug to drain the condensate, and remove the specified indoor unit 200X.

[0147] (7) Relocation

[0148] (8) Connect the external wiring

[0149] (9) Powering on (When all indoor units of the air conditioning system share a common power supply, enable the other indoor units to operate normally; when the power supplies of each indoor unit are independent, enable the air conditioning system to identify the specified indoor unit 200X)

[0150] (10) Connect the drain pipe, connect the piping and perform vacuuming (to check for leaks in the piping).

[0151] (11) Determine if refrigerant needs to be added; if so, add refrigerant; then disconnect the hose and tighten the valve cap of the unit's shut-off valve.

[0152] (12) Open the gas-side shut-off valve and the liquid-side shut-off valve.

[0153] (13) Perform thermal insulation treatment on the piping connection parts.

[0154] 8) Adding indoor units to the air conditioning system

[0155] In air conditioning systems, it is sometimes necessary to add indoor units, for example, such as... Figure 2 and Figure 3 As shown, a third indoor unit 200C is added to the refrigerant piping of the designated indoor unit 200X in the first indoor unit 200A.

[0156] The following describes the process of adding a third indoor unit, 200C.

[0157] When adding a third indoor unit (200C), preparations should be made before proceeding with the actual addition.

[0158] As preparation, the following tasks should be performed in sequence:

[0159] (1) Prepare the location of the third indoor unit 200C using a hanging rod.

[0160] (2) Prepare piping, wiring and drainage pipes according to the installation distance of the third indoor unit 200C.

[0161] (3) After bundling the piping and wiring together, insert it from the designated indoor unit 200X position to the third indoor unit 200C position.

[0162] (4) Prepare the consumable materials needed for the expansion.

[0163] As part of the formal addition of the aircraft, the following procedures shall be carried out in sequence:

[0164] (1) Hoisting the third indoor unit 200C

[0165] (2) Run the connecting pipes and wiring, for example, inside the ceiling, from the location of the third indoor unit 200C to the designated location of the indoor unit 200X (specifically...). Figure 2 (near the branch unit 401, 402)

[0166] (3) Install the branch unit devices 401 and 402 of the third indoor unit 200C, the branch pipe with the branch unit shut-off valve (specifically the liquid-side branch unit shut-off valve VI1C on the third indoor unit side and the gas-side branch unit shut-off valve VI2C on the third indoor unit side), connect the wiring, and ensure that the above-mentioned branch unit shut-off valves are open (of course, branch pipes without branch unit shut-off valves can also be used here).

[0167] (4) Connect the drain pipe of the third indoor unit 200C

[0168] (5) Install air intake panels, air outlet grilles, etc.

[0169] (6) Close the liquid-side shut-off valve of the indoor unit to allow the specified indoor unit 200X to operate in cooling mode and recover the refrigerant in the specified indoor unit 200X.

[0170] (7) After running for several minutes, close the gas-side unit shut-off valve to stop the indoor unit from operating at the specified 200X.

[0171] (8) Recover residual refrigerant in the refrigerant piping of the specified indoor unit 200X by connecting a bimanifold gauge (pressure gauge) (simultaneous gas and liquid side recovery).

[0172] (9) Power off (If the power supply to each indoor unit is independent, only the power supply to the designated indoor unit 200X can be cut off), connect the power cord, signal cord, and remote control cord of the third indoor unit 200C to the designated indoor unit 200X.

[0173] (10) Powering on (when all indoor units of the air conditioning system share a common power supply, so that the other indoor units can operate normally)

[0174] (11) Disconnect the piping of the specified indoor unit 200X.

[0175] (12) Connect the specified indoor unit 200X and the third indoor unit 200C to the branch unit devices 401 and 402 respectively. (Specifically, connect the first ends 401a and 402a of the branch unit devices to the specified indoor unit 200X, connect the second end 401b of the liquid-side branch unit device 401 to the liquid-side branch unit shut-off valve VI1, connect the second end 402b of the gas-side branch unit device 402 to the gas-side branch unit shut-off valve VI2, and connect the third ends 401c and 402c of the branch unit devices to the third indoor unit 200C via the liquid-side branch unit shut-off valve VI1C and the gas-side branch unit shut-off valve VI2C of the third indoor unit. Of course, the liquid-side branch unit shut-off valve VI1C and the gas-side branch unit shut-off valve VI2C of the third indoor unit can be omitted here, and the third ends 401c and 402c of the branch unit devices can be directly connected to the third indoor unit 200C.)

[0176] (13) Vacuuming (to check for leaks in the piping)

[0177] (14) Determine if refrigerant needs to be added; if so, add refrigerant; then disconnect the hose and tighten the valve cap of the unit's shut-off valve.

[0178] (15) Open the gas-side shut-off valve and the liquid-side shut-off valve.

[0179] (16) Perform thermal insulation treatment on the piping connection parts.

[0180] 9) Method for detecting the opening and closing of the branch unit's shut-off valve

[0181] As mentioned above, in air conditioning systems, it is sometimes necessary to relocate the first indoor unit and add a third indoor unit. In this case, if the corresponding unit shut-off valve is not opened after the relocation or addition work, the relocated first indoor unit, the added first indoor unit, and / or the third indoor unit will not be able to operate normally.

[0182] To ensure the normal operation of the first indoor unit after relocation, and the first and third indoor units after expansion, in this embodiment, after the relocation and expansion operations, by... Figure 4The method for detecting the opening and closing of the unit shut-off valve is shown for testing the opening and closing of the unit shut-off valve of the first indoor unit after relocation, the first indoor unit after addition, and the third indoor unit.

[0183] Below, will Figure 1 and Figure 2 The following explanation uses the indoor unit 200X as an example, as specified in the regulations.

[0184] Suppose that after a preset operating time for the indoor unit 200X (e.g., 5 minutes, but not limited to this), the remote control sends a command to the air conditioning system controller to start the opening and closing detection of the indoor unit 200X's shut-off valve.

[0185] In this case, in step ST101, the operating mode of the specified indoor unit 200X after relocation or addition is determined.

[0186] In step ST101, if it is determined that the specified indoor unit 200X is in heating operation, the process proceeds to step ST102. In step ST102, the second and third sensors are used to detect the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 of the indoor heat exchanger of the specified indoor unit 200X, respectively, and it is determined whether the difference between the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 is below a first preset value (e.g., -3℃, but not limited to this). In step ST102, if it is determined that the difference between the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 is below the first preset value, the process proceeds to step ST103, where it is determined that the unit shut-off valve of the specified indoor unit 200X is open and operating normally. On the other hand, if it is determined that the difference between the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 is greater than the first preset value, the process proceeds to step ST105.

[0187] On the other hand, in step ST101, if it is determined that the specified indoor unit 200X is in cooling or dehumidifying operation, the process proceeds to step ST104. In step ST104, the second and third sensors are used to detect the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 of the indoor heat exchanger of the specified indoor unit 200X, respectively, and it is determined whether the difference between the gas-side piping temperature TH3 and the liquid-side piping temperature TH2 (TH3-TH2) is greater than or equal to a fourth preset value (e.g., 3°C, but not limited to this). In step ST104, if it is determined that the difference between the gas-side piping temperature TH3 and the liquid-side piping temperature TH2 is greater than or equal to the fourth preset value, the process proceeds to step ST103, where it is determined that the unit shut-off valve of the specified indoor unit 200X is open and the operation is normal. On the other hand, if it is determined that the difference between the gas-side piping temperature TH3 and the liquid-side piping temperature TH2 is greater than the first preset value, the process proceeds to step ST105.

[0188] In step ST105, the counter counts the number of times the branch shut-off valve of the indoor unit 200X is closed, and then the process proceeds to step ST106.

[0189] In step ST106, it is determined whether the number of times the branch shut-off valve of the indoor unit 200X has been closed is more than a preset number.

[0190] In step ST106, if it is determined that the number of times the branch shut-off valve of the specified indoor unit 200X has closed is greater than a preset number, then the process proceeds to step ST107, where the remote control displays a fault code indicating that the branch shut-off valve of the specified indoor unit 200X is not open (for example, the remote control corresponding to the specified indoor unit 200X displays the fault code, or the central remote control displays the identification number of the specified indoor unit 200X and the fault code indicating that the branch shut-off valve is not open). On the other hand, if it is determined in step ST106 that the number of times the branch shut-off valve of the specified indoor unit 200X has closed is less than a preset number, then the process proceeds to step ST108, waits for a preset time (for example, 3 minutes, but not limited to this), and then returns to step ST101.

[0191] Here, step ST101 is equivalent to the operation mode determination step of the present invention, steps ST102, ST104, and ST105 are equivalent to the detection and counting steps of the present invention, and steps ST106 and ST107 are equivalent to the notification determination steps of the present invention.

[0192] In addition, it should be noted that when performing the branch unit shut-off valve opening and closing test, first determine whether the outdoor unit shut-off valve is open (this is existing technology and will not be elaborated on in detail). Only after ensuring that the outdoor unit shut-off valve is open should the branch unit shut-off valve opening and closing test be performed.

[0193] Furthermore, when adding a third indoor unit (200C), after the addition operation, the same method can be used as described above. Figure 4 The same method is used to test the opening and closing of the branch unit's shut-off valve (e.g., ...). Figure 2 As shown, the third indoor unit 200C also has a first sensor to detect the temperature TH1 of the airflow at the air inlet, a second sensor to detect the temperature TH2 of the liquid side piping of the indoor heat exchanger, a third sensor to detect the temperature TH3 of the gas side piping of the indoor heat exchanger, and a fourth sensor to detect the temperature TH4 of the airflow at the air outlet. Of course, after the addition of a unit, the opening and closing of the branch unit shut-off valve can be detected only on the newly added third indoor unit 200C or the specified indoor unit 200X.

[0194] (Main technical effects of this embodiment)

[0195] According to the air conditioning system of this embodiment, the multiple indoor units 200 include a second indoor unit 200B. The second indoor unit 200B is not connected to the liquid-side connecting pipe P1 and the gas-side connecting pipe P2 via the branch unit shut-off valve. Therefore, even if the branch unit shut-off valves VI1 and VI2 connected to the first indoor unit 200A and the liquid-side connecting pipe P1 and the gas-side connecting pipe P2 are closed, as long as the outdoor unit shut-off valves VO1 and VO2 are not closed, the refrigerant circuit can form a circulation through the second indoor unit 200B. This helps to prevent the high-pressure refrigerant discharged by the compressor 110 from accumulating at a certain point in the piping due to the inability of the refrigerant circuit to circulate, which could lead to system failures such as liquid seal and piping rupture.

[0196] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above embodiments.

[0197] For example, in the above embodiment, multiple indoor units 200 are connected to the outdoor unit 100 only through the liquid-side connecting pipe P1 (as the first piping) and the gas-side connecting pipe P2 (as the second piping), but this is not limited to this; alternative methods may be used. Figure 5 , Figure 6 The structure shown can also be adopted as follows: Figure 7 , Figure 8 The structure shown. Here, Figure 5 This is a schematic diagram of an air conditioning system according to a modified example of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line. Figure 6 This is a schematic diagram illustrating the operation of adding units to an air conditioning system according to a variation of the present invention, and, in Figure 5 and Figure 6 In the text, the same symbols are used to mark the parts that are the same as or corresponding to those in Embodiment 1. Similarly, Figure 7 This is a schematic circuit diagram of an air conditioning system illustrating another variation of the present invention, wherein a first indoor unit that has been moved is represented by a dashed line. Figure 8 This is a schematic diagram illustrating the operation of adding a unit to an air conditioning system according to another variation of the present invention, and, in Figure 7 and Figure 8 In the text, the same symbols are used to mark the parts that are the same as or corresponding to those in Implementation 1.

[0198] Specifically, in Figure 5 and Figure 6In the structure shown, the first indoor unit 200A is connected to the outdoor unit 100 only through the liquid-side connecting pipe P1 and the gas-side connecting pipe P2, while the second indoor unit 200B is connected to the outdoor unit 100 through the liquid-side connecting pipe P1, the gas-side connecting pipe P2, and the third pipe P3; and the outdoor unit 100 is connected to the liquid-side connecting pipe P1, the gas-side connecting pipe P2, and the third pipe P3 via the liquid-side outdoor unit shut-off valve VO1, the gas-side outdoor unit shut-off valve VO2, and the third pipe-side outdoor unit shut-off valve VO3, respectively. More specifically, as Figure 5 As shown, the outdoor unit 100, based on the outdoor unit 100 in the air conditioning system of Embodiment 1, further includes a branch pipe PO6 branching from the discharge pipe PO1, a four-way valve VF2, piping PO7, and piping PO8. The branch pipe PO6 includes piping PO6-1 and piping PO6-2. One end of piping PO6-1 is connected to the discharge pipe PO1, and the other end of piping PO6-1 is connected to the third port c1 of the four-way valve VF2. One end of piping PO6-2 is connected to the fourth port d1 of the four-way valve VF2, and the other end of piping PO6-2 is connected to the outdoor unit shut-off valve VO3 on the third piping side. One end of piping PO7 is connected to the fourth port d1 of the four-way valve VF2. The first port a1 of the four-way valve VF2 is connected, the other end of the piping PO7 is connected to the suction pipe PO3, one end of the piping PO8 is connected to the second port b1 of the four-way valve VF2, and the other end of the piping PO8 is connected to the piping PO7. A capillary tube 160 is installed on the piping PO8. Furthermore, the four-way valve VF2 can switch between a first state and a second state. In the first state, the four-way valve VF2 connects the first port a1 to the second port b1 and connects the third port c1 to the fourth port d1. In the second state, the four-way valve VF2 connects the first port a1 to the fourth port d1 and connects the second port b1 to the third port c1. And, as... Figure 5 As shown, the first indoor unit 200A is the same as the first indoor unit 200A in the air conditioning system of Embodiment 1. The second indoor unit 200B, based on the second indoor unit 200B in the air conditioning system of Embodiment 1, further includes a refrigerant pipe PI2B, an indoor flow regulating valve VC4B installed on the refrigerant pipe PI2B, and an indoor heat exchanger 230B. One end of the refrigerant pipe PI2B is connected to the refrigerant pipe PI1B, and the other end of the refrigerant pipe PI2B is connected to the third piping P3 (specifically, at point K3, it connects to the branch pipe P32). The indoor fan 220B blows air to the indoor heat exchanger 230B. In the airflow path formed by the indoor fan 220B, the indoor heat exchanger 230B is located downstream of the indoor heat exchanger 210B. Furthermore, as... Figure 5As shown, the connecting pipe between the outdoor unit and the indoor unit in the air conditioning system of Embodiment 1 further includes a third piping P3. The third piping P3 includes a main pipe P31 and a branch pipe P32 branching off from the main pipe P31 via a branch device 303 on the third piping side. The second indoor unit 200B (specifically, the refrigerant piping PI2B) is connected to the branch pipe P32. Figure 5 In the structure shown, the relocation of the first indoor unit can be performed in the same way as the relocation of the first indoor unit 200A of the air conditioning system in Embodiment 1, and the addition of the third indoor unit of the air conditioning system can be performed in the same way as the addition of the third indoor unit 200C of the air conditioning system in Embodiment 1. Furthermore, the same branch shut-off valve opening and closing detection method as the branch shut-off valve opening and closing detection method of the air conditioning system in Embodiment 1 can be used.

[0199] In addition, Figure 7 and Figure 8 In the structure shown, the first indoor unit 200A and the second indoor unit 200B are connected to the outdoor unit 100 via liquid-side connecting pipe P1, gas-side connecting pipe P2, and third pipe P3, respectively; and the outdoor unit 100 is connected to the liquid-side connecting pipe P1, gas-side connecting pipe P2, and third pipe P3 via liquid-side outdoor unit shut-off valve VO1, gas-side outdoor unit shut-off valve VO2, and third pipe-side outdoor unit shut-off valve VO3, respectively. More specifically, as... Figure 7 As shown, the structure of outdoor unit 100 is similar to... Figure 5 The outdoor unit 100 shown has the same structure. Furthermore, as... Figure 7 As shown, the first indoor unit 200A, based on the first indoor unit 200A in the air conditioning system of Embodiment 1, further includes a refrigerant pipe PI2A, an indoor flow regulating valve VC4A installed on the refrigerant pipe PI2A, and an indoor heat exchanger 230A. One end of the refrigerant pipe PI2A is connected to the refrigerant pipe PI1A, and the other end is connected to the third piping P3 (specifically, branch pipe P32). The indoor fan 220A blows air to the indoor heat exchanger 230A. In the airflow path formed by the indoor fan 220A, the indoor heat exchanger 230A is located downstream of the indoor heat exchanger 210A. Furthermore, the second indoor unit 200B and... Figure 5 The structure of the second indoor unit 200B shown is the same. Furthermore, as... Figure 7As shown, the connecting pipe between the outdoor unit and the indoor unit in the air conditioning system of Embodiment 1 further includes a third piping P3. The third piping P3 includes a main pipe P31 and a branch pipe P32 branching off from the main pipe P31 via a branch device 303 on the third piping side. The first indoor unit 200A (specifically, refrigerant piping PI2A) and the second indoor unit 200B (specifically, refrigerant piping PI2B) are connected to the branch pipe P32. Figure 7 In the structure shown, the relocation of the first indoor unit can be performed in a similar manner to the relocation of the first indoor unit 200A of the air conditioning system in Embodiment 1, and the addition of the third indoor unit of the air conditioning system can be performed in a similar manner to the addition of the third indoor unit 200C of the air conditioning system in Embodiment 1. Furthermore, the same branch shut-off valve opening and closing detection method as the branch shut-off valve opening and closing detection method of the air conditioning system in Embodiment 1 can be used.

[0200] Furthermore, in the above embodiments, such as Figure 9 As shown, two outdoor units can also be connected in parallel. Similarly, in Figures 5 to 8 In the structure shown, two outdoor units can also be connected in parallel.

[0201] In addition, in the above embodiment, the outdoor unit 100 includes a four-way valve VF1, a pipeline PO5, a subcooler 140, and a second outdoor flow regulating valve VC2, etc., but these components may be omitted depending on the situation.

[0202] Furthermore, in the above embodiments, the branch devices 301, 302, 303 and the extension branch devices 401, 402, 403 may be composed of T-type connectors having a first end, a second end, and a third end, or they may be composed of Y-type connectors or other multi-way connectors (such as T-type connectors) having multiple ends.

[0203] Furthermore, in the above embodiment, the newly added third indoor unit 200C is connected to the branch unit devices 401, 402, and 403 (specifically the third end) via a shut-off valve, but it is not limited to this. The newly added third indoor unit 200C may also be connected to the branch unit devices 401, 402, and 403 without using a shut-off valve.

[0204] Furthermore, in the above embodiments, branch devices 301 and 302 are used to connect the main pipe and the branch pipe, but it is not limited to this; the branch pipe can also be directly welded to the main pipe.

[0205] Furthermore, in the above embodiments, such as Figure 4As shown, in step ST102, it is determined whether the difference between the liquid-side piping temperature TH2 and the gas-side piping temperature TH3 is below a first preset value. If the difference is below the first preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is open; if the difference is greater than the first preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is closed, but it is not limited to this. Specifically, as shown... Figure 10 As shown, in step ST102, it is also possible to determine whether the difference between the airflow temperature TH1 at the air inlet and the piping temperature TH3 on the air side of the indoor heat exchanger is below a second preset value (e.g., -3℃, but not limited to this). If the difference is below the second preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is open; if the difference is greater than the second preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is closed. Or, as... Figure 11 As shown, in step ST102, it is also possible to determine whether the difference between the airflow temperature TH1 at the air inlet and the liquid-side piping temperature TH2 of the indoor heat exchanger is below a third preset value (e.g., -3℃, but not limited to this). If the difference is below the third preset value, it is determined that the shut-off valve of the indoor unit corresponding to the tested unit is open; if the difference is greater than the third preset value, it is determined that the shut-off valve of the indoor unit corresponding to the tested unit is closed. Or, as... Figure 12 As shown, in step ST102, it is also possible to determine whether the difference between the air temperature TH1 of the air inlet and the air temperature TH4 of the air outlet is below the seventh preset value (e.g., -3℃, but not limited to this). When the difference is below the seventh preset value, it is determined that the branch shut-off valve corresponding to the indoor unit under test is open, and when the difference is greater than the seventh preset value, it is determined that the branch shut-off valve corresponding to the indoor unit under test is closed.

[0206] Furthermore, in the above embodiments, such as Figure 4 As shown, in step ST104, it is determined whether the difference (TH3-TH2) between the gas-side piping temperature TH3 and the liquid-side piping temperature TH2 is greater than or equal to a fourth preset value. If the difference is greater than or equal to the fourth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is open; if the difference is less than the fourth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is closed, but this is not limited to this. Specifically, as shown... Figure 10 As shown, in step ST104, it is also possible to determine whether the difference between the airflow temperature TH1 at the air inlet and the piping temperature TH3 on the air side of the indoor heat exchanger is greater than or equal to a fifth preset value (e.g., 3°C, but not limited to this). If the difference is greater than or equal to the fifth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is open; if the difference is less than the fifth preset value, it is determined that the shut-off valve of the unit corresponding to the indoor unit under test is closed. Or, as... Figure 11As shown, in step ST104, it is also possible to determine whether the difference between the airflow temperature TH1 at the air inlet and the piping temperature TH2 on the liquid side of the indoor heat exchanger is above a sixth preset value (e.g., 3°C, but not limited to this). If the difference is above the sixth preset value, it is determined that the shut-off valve of the indoor unit corresponding to the tested unit is open; if the difference is less than the sixth preset value, it is determined that the shut-off valve of the indoor unit corresponding to the tested unit is closed. Or, as... Figure 12 As shown, in step ST104, it is also possible to determine whether the difference between the air temperature TH1 of the air inlet and the air temperature TH4 of the air outlet is above the eighth preset value (e.g., 3°C, but not limited to this). When the difference is above the eighth preset value, it is determined that the branch shut-off valve corresponding to the indoor unit under test is open, and when the difference is less than the eighth preset value, it is determined that the branch shut-off valve corresponding to the indoor unit under test is closed.

[0207] Furthermore, in the above embodiment, in step ST104, the operation status of the drain pump of the indoor unit under test can be used to determine whether the branch unit shut-off valve is open. Specifically, if the drain pump of the first indoor unit is started, it is determined that the branch unit shut-off valve corresponding to the indoor unit under test is open and operating normally. If the drain pump of the first indoor unit is stopped, the process proceeds to step ST105.

[0208] Furthermore, in the above embodiments, in an air conditioning system including a second indoor unit 200B connected to the liquid-side communication pipe P1 and the gas-side communication pipe P2 without via the branch unit shut-off valve, according to Figure 4 The method for detecting the opening and closing of the branch unit's shut-off valve, as shown, detects whether the branch unit's shut-off valve is open or closed, but... Figure 4 The illustrated method for detecting the opening and closing of the unit shut-off valve can also be applied to air conditioning systems that only include indoor units connected via the unit shut-off valve to the liquid-side connecting pipe P1 and the gas-side connecting pipe P2. Similarly, Figures 10 to 12 The method for detecting the opening and closing of the unit shut-off valve shown can also be applied to air conditioning systems that only include indoor units connected via the unit shut-off valve to the liquid-side connecting pipe P1 and the gas-side connecting pipe P2.

[0209] Furthermore, in the above embodiment, one end of pipe PO5 is connected to the portion of pipe PO2 located between the subcooler 140 and the outdoor unit shut-off valve VO1, but it is not limited to this. Alternatively, one end of pipe PO5 can be connected to the portion of pipe PO2 located between the subcooler 140 and the first outdoor flow regulating valve VC1.

[0210] In addition, Figures 5 to 8 In the embodiment shown, a capillary tube 160 is connected to the second port b1 of the four-way valve VF2, but it is not limited to this. The capillary tube 160 can be omitted and the second port b1 can be set to the cut-off state. A three-way valve or the like can also be used to replace the four-way valve VF2.

[0211] It should be understood that within the scope of this invention, various embodiments can be freely combined, or parts of various embodiments can be appropriately modified or omitted.

Claims

1. An air conditioning system comprising an outdoor unit and a plurality of indoor units, the plurality of indoor units being connected to the outdoor unit through a liquid-side communication pipe as a first pipe and a gas-side communication pipe as a second pipe, respectively, the outdoor unit being connected to the liquid-side communication pipe and the gas-side communication pipe through outdoor unit shut-off valves on the liquid side and the gas side, respectively, characterized in that the plurality of indoor units comprise: a first indoor unit connected to the liquid-side communication pipe through a subunit shut-off valve on the liquid side and connected to the gas-side communication pipe through a subunit shut-off valve on the gas side; and a second indoor unit not connected to the liquid-side communication pipe and the gas-side communication pipe through subunit shut-off valves.

2. The air conditioning system according to claim 1, characterized in that the first indoor unit and the second indoor unit are further connected to the outdoor unit through a third pipe, respectively, and the first indoor unit is connected to the third pipe through a subunit shut-off valve on the third pipe side.

3. The air conditioning system according to claim 1, characterized in that the first indoor unit is connected to the outdoor unit through only the liquid-side communication pipe and the gas-side communication pipe, and the second indoor unit is further connected to the outdoor unit through a third pipe.

4. The air conditioning system according to any one of claims 1 to 3, characterized in that the subunit shut-off valve is provided between the first indoor unit and the outdoor unit by welding or screwing.

5. The air conditioning system according to any one of claims 1 to 3, characterized in that the liquid-side communication pipe comprises a liquid-side main pipe and a liquid-side branch pipe branched from the liquid-side main pipe through a branch device on the liquid side, the gas-side communication pipe comprises a gas-side main pipe and a gas-side branch pipe branched from the gas-side main pipe through a branch device on the gas side, and the indoor units are connected to the gas-side branch pipe and the liquid-side branch pipe, respectively.

6. The air conditioning system according to claim 5, characterized in that the subunit shut-off valve is provided between the branch device and the first indoor unit.

7. The air conditioning system according to claim 2 or 3, characterized in that the third pipe comprises a main pipe and a branch pipe branched from the main pipe through a branch device on the third pipe side, and the indoor units are connected to the branch pipe.

8. The air conditioning system according to any one of claims 1 to 3, characterized in that the subunit shut-off valve has a refrigerant suction and injection port and has a valve core that controls the on-off of a refrigerant passage.

9. The air conditioning system according to claim 1, characterized in that the first indoor unit is connected to the liquid-side communication pipe through a subunit branch device on the liquid side and the subunit shut-off valve on the liquid side in this order, the first indoor unit is connected to the gas-side communication pipe through a subunit branch device on the gas side and the subunit shut-off valve on the gas side in this order, the subunit branch device has a first end portion, a second end portion, and a third end portion, the first end portion of the subunit branch device is connected to the first indoor unit, and the second end portion of the subunit branch device on the liquid side is connected to the subunit shut-off valve on the liquid side and the second end portion of the subunit branch device on the gas side is connected to the subunit shut-off valve on the gas side. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. The air conditioning system according to claim 2, wherein the first indoor unit is connected to the liquid-side communication pipe via the branch device of the liquid side, the branch valve of the liquid side, and the liquid-side communication pipe arranged in this order, the first indoor unit is connected to the gas-side communication pipe via the branch device of the gas side, the branch valve of the gas side, and the gas-side communication pipe arranged in this order, the first indoor unit is connected to the third pipe via the branch device of the third pipe side, the branch valve of the third pipe side, and the third pipe arranged in this order, the branch device has a first end portion, a second end portion, and a third end portion, the first end portion of the branch device of the liquid side is connected to the first indoor unit, the second end portion of the branch device of the liquid side is connected to the branch valve of the liquid side, the second end portion of the branch device of the gas side is connected to the branch valve of the gas side, and the second end portion of the branch device of the third pipe side is connected to the branch valve of the third pipe side.

11. The air conditioning system according to claim 9 or 10, wherein a foaming member is provided at the branch device.

12. The air conditioning system according to claim 9 or 10, wherein the plurality of indoor units include a third indoor unit, and the third indoor unit is connected to the third end portion of the branch device.

13. The air conditioning system according to claim 12, wherein a branch valve of the third indoor unit side is provided between the third indoor unit and the branch device.

14. The air conditioning system according to claim 1, wherein the branch valves are manually opened and closed.

15. The air conditioning system according to claim 1, comprising a control portion, the first indoor unit includes a to-be-tested indoor unit having an indoor heat exchanger, an air inlet, and a sensor, the control portion performs at least one of a first detection, a second detection, and a third detection when the to-be-tested indoor unit is in a heating operation, and / or performs at least one of a fourth detection, a fifth detection, and a sixth detection when the to-be-tested indoor unit is in a cooling or dehumidifying operation, in the first detection, the control portion judges whether a difference (TH2-TH3) between a pipe temperature (TH2) of the liquid side of the indoor heat exchanger and a pipe temperature (TH3) of the gas side of the indoor heat exchanger detected by the sensor is equal to or less than a first predetermined value, and judges that the branch valve corresponding to the to-be-tested indoor unit is open when the difference is equal to or less than the first predetermined value, and judges that the branch valve corresponding to the to-be-tested indoor unit is closed when the difference is greater than the first predetermined value, in the second detection, the control portion judges whether a difference (TH1-TH3) between a temperature (TH1) of an air flow of the air inlet and the pipe temperature (TH3) of the gas side of the indoor heat exchanger detected by the sensor is equal to or less than a second predetermined value, and judges that the branch valve corresponding to the to-be-tested indoor unit is open when the difference is equal to or less than the second predetermined value, and judges that the branch valve corresponding to the to-be-tested indoor unit is closed when the difference is greater than the second predetermined value. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In the third detection, the control section determines whether a difference (TH1-TH2) between the temperature (TH1) of the airflow of the air inlet obtained by the sensor detection and the pipe temperature (TH2) of the liquid side of the indoor heat exchanger is equal to or less than a third predetermined value, and determines that the branch stop valve corresponding to the indoor unit to be detected is open when the difference is equal to or less than the third predetermined value, and determines that the branch stop valve is closed when the difference is greater than the third predetermined value, In the fourth detection, the control section determines whether a difference (TH3-TH2) between the pipe temperature (TH3) of the gas side of the indoor heat exchanger obtained by the sensor detection and the pipe temperature (TH2) of the liquid side of the indoor heat exchanger is equal to or greater than a fourth predetermined value, and determines that the branch stop valve corresponding to the indoor unit to be detected is open when the difference is equal to or greater than the fourth predetermined value, and determines that the branch stop valve is closed when the difference is less than the fourth predetermined value, In the fifth detection, the control section determines whether a difference (TH1-TH3) between the temperature (TH1) of the airflow of the air inlet obtained by the sensor detection and the pipe temperature (TH3) of the gas side of the indoor heat exchanger is equal to or greater than a fifth predetermined value, and determines that the branch stop valve corresponding to the indoor unit to be detected is open when the difference is equal to or greater than the fifth predetermined value, and determines that the branch stop valve is closed when the difference is less than the fifth predetermined value, In the sixth detection, the control section determines whether a difference (TH1-TH2) between the temperature (TH1) of the airflow of the air inlet obtained by the sensor detection and the pipe temperature (TH2) of the liquid side of the indoor heat exchanger is equal to or greater than a sixth predetermined value, and determines that the branch stop valve corresponding to the indoor unit to be detected is open when the difference is equal to or greater than the sixth predetermined value, and determines that the branch stop valve is closed when the difference is less than the sixth predetermined value.

16. A branch stop valve opening / closing detection method of an air conditioning system, which detects the opening / closing of the branch stop valve of the air conditioning system according to any one of claims 1 to 14, characterized in that the first indoor unit includes an indoor unit to be detected, which has an indoor heat exchanger and an air inlet, at least one of the first detection, the second detection, and the third detection is executed when the indoor unit to be detected is in a heating operation, and / or at least one of the fourth detection, the fifth detection, and the sixth detection is executed when the indoor unit to be detected is in a cooling or dehumidifying operation, in the first detection, a difference (TH2-TH3) between the pipe temperature (TH2) of the liquid side of the indoor heat exchanger and the pipe temperature (TH3) of the gas side is determined to be equal to or less than a first predetermined value, and it is determined that the branch stop valve corresponding to the indoor unit to be detected is open when the difference is equal to or less than the first predetermined value, and it is determined that the branch stop valve is closed when the difference is greater than the first predetermined value, In the second detection, it is judged whether the difference (TH1-TH3) between the temperature (TH1) of the air flow of the air inlet and the pipe temperature (TH3) of the air side of the indoor heat exchanger is below a second preset value, and when the difference is below the second preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is open, and when the difference is greater than the second preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is closed, In the third detection, it is judged whether the difference (TH1-TH2) between the temperature (TH1) of the air flow of the air inlet and the pipe temperature (TH2) of the liquid side of the indoor heat exchanger is below a third preset value, and when the difference is below the third preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is open, and when the difference is greater than the third preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is closed, In the fourth detection, it is judged whether the difference (TH3-TH2) between the pipe temperature (TH3) of the air side of the indoor heat exchanger and the pipe temperature (TH2) of the liquid side is above a fourth preset value, and when the difference is above the fourth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is open, and when the difference is less than the fourth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is closed, In the fifth detection, it is judged whether the difference (TH1-TH3) between the temperature (TH1) of the air flow of the air inlet and the pipe temperature (TH3) of the air side of the indoor heat exchanger is above a fifth preset value, and when the difference is above the fifth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is open, and when the difference is less than the fifth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is closed, In the sixth detection, it is judged whether the difference (TH1-TH2) between the temperature (TH1) of the air flow of the air inlet and the pipe temperature (TH2) of the liquid side of the indoor heat exchanger is above a sixth preset value, and when the difference is above the sixth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is open, and when the difference is less than the sixth preset value, it is judged that the branch stop valve corresponding to the indoor unit to be detected is closed.

17. The method of claim 16, wherein the method further comprises: determining whether the sub-cut off valve is open or closed based on the comparison result. Comprise: Operation mode judging step, judging the operation mode of the indoor unit to be detected; Detection counting step, when the operation mode judging step judges that the indoor unit to be detected is in heating operation, any one of the first detection, the second detection and the third detection is executed, and the number of times that the branch stop valve corresponding to the indoor unit to be detected is judged to be closed is counted, when the operation mode judging step judges that the indoor unit to be detected is in cooling or dehumidifying operation, any one of the fourth detection, the fifth detection and the sixth detection is executed, and the number of times that the branch stop valve corresponding to the indoor unit to be detected is judged to be closed is counted; And The notification judging step judges whether the count value obtained by the detection counting step is greater than or equal to a preset value, and when the count value is judged to be greater than or equal to the preset value, a notification indicating that the indoor unit to be tested has a failure is performed, and when the count value is judged to be less than the preset value, the operation mode judging step is returned to.

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