Air conditioning system and control method

Abstract

An air conditioning system according to an embodiment comprises an internal conditioner control unit and an external conditioner control unit. If an operating capacity of an external conditioner is equal to or greater than a first threshold and an operating capacity of an internal conditioner can be increased, the internal conditioner control unit increases the operating capacity of the internal conditioner, and if the operating capacity of the external conditioner is less than a second threshold that is smaller than the first threshold and the operating capacity of the internal conditioner can be reduced, the internal conditioner control unit reduces the operating capacity of the internal conditioner. If the operating capacity of the internal conditioner is equal to or greater than a third threshold and the operating capacity of the external conditioner can be increased, the external conditioner control unit increases the operating capacity of the external conditioner, and if the operating capacity of the internal conditioner is less than a fourth threshold that is smaller than the third threshold and the operating capacity of the external conditioner can be reduced, the external conditioner control unit reduces the operating capacity of the external conditioner.

Description

Technical Field

[0001] The present invention relates to an air conditioning system and a control method. This application claims priority based on Japanese Patent Application No. 2022-192823 filed in Japan on December 1, 2022, and incorporates the content herein by reference.

Background Art

[0002] In the prior art, the interlocking control of the indoor unit and the outdoor unit was for the purpose of reducing power consumption, and was control that compared the coefficient of performance (COP) or compared the power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, devices and instruments capable of measuring the power consumption are required, and the introduction costs thereof increase. Furthermore, when simply comparing the COP, either the indoor unit or the outdoor unit often operates at a high load, or there is a bias in the operation time. As a result, parts of the device that operates at a high load are likely to fail, or the maintenance cycle of the device that operates at a high load may decrease. Thus, in the prior art, there is a problem that the running cost of the air conditioning system increases due to part replacement due to failure and a decrease in the maintenance cycle.

[0005] The problem to be solved by the present invention is to provide an air conditioning system and a control method for suppressing the running cost of the air conditioning system.

Means for Solving the Problems

[0006] The air conditioning system of the embodiment comprises an indoor air handling unit control unit and an outdoor air handling unit control unit. The indoor air handling unit control unit increases the operating capacity of the indoor air handling unit when the operating capacity of the outdoor air handling unit is equal to or greater than a first threshold and the operating capacity of the indoor air handling unit can be increased, and decreases the operating capacity of the indoor air handling unit when the operating capacity of the outdoor air handling unit falls below a second threshold which is smaller than the first threshold and the operating capacity of the indoor air handling unit can be decreased. The outdoor air handling unit control unit increases the operating capacity of the outdoor air handling unit when the operating capacity of the indoor air handling unit is equal to or greater than a third threshold and the operating capacity of the outdoor air handling unit can be increased, and decreases the operating capacity of the outdoor air handling unit when the operating capacity of the indoor air handling unit falls below a fourth threshold which is smaller than the third threshold and the operating capacity of the outdoor air handling unit can be decreased. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing an example configuration of an air conditioning system according to an embodiment. [Figure 2] A flowchart showing a specific example of the processing flow of the air conditioning system in the first embodiment. [Figure 3] A flowchart showing a specific example of the processing flow of the air conditioning system in the second embodiment. [Modes for carrying out the invention]

[0008] The air conditioning system and control method of the embodiment will be described below with reference to the drawings.

[0009] Figure 1 shows an example configuration of an air conditioning system 17 according to an embodiment. The air conditioning system 17 shown in Figure 1 is a system that provides air conditioning for multiple spaces (in Figure 1, two spaces 23 and 24 provided in building 14). The air conditioning system 17 includes a control unit 10, a direct-cooling outdoor unit 12, and a heat source unit 40. Building 14 also includes an air conditioning unit control unit 18, two indoor air conditioning units 21, an exhaust duct 16, two VAVs (Variable Air Volume systems) 20, and two remote controls 22. One indoor air conditioning unit 21, one VAV 20, and one remote control 22 are provided in each of spaces 23 and 24.

[0010] The direct-cooling outdoor unit 12 adjusts the temperature of the indoor air in spaces 23 and 24. The remote control 22 is used to start and stop operation, and to set the airflow and temperature. The set information is output to the control unit 10. The control unit 10 controls the operating status of the outdoor air handling unit 31 and the direct-cooling outdoor unit 12 according to the settings set by the remote control 22, the temperature and humidity of the outside and inside air, etc.

[0011] The exhaust duct 16 is connected to exhaust ports (not shown) provided in spaces 23 and 24. The exhaust duct 16 is a duct for exhausting the air from spaces 23 and 24 to the outside via the building 15.

[0012] The building 15 is equipped with a ventilation fan 26, an air handling unit control unit 27, an air handling unit 31, and an air intake 34. The ventilation fan 26 exhausts the air from the exhaust duct 16 mentioned above. The air handling unit control unit 27 controls the air handling unit 31. The air intake 34 draws outside air into the air handling unit 31.

[0013] The air handling unit 31 comprises an air handling unit blower 29, a humidifier 30, and a water coil 32. The air handling unit 31 takes in outside air from an air intake port 34 via an air intake duct 28. The air handling unit 31 adjusts the intake outside air (cooling, heating, dehumidifying, or humidifying). The air handling unit 31 supplies the adjusted outside air from the VAV 20 to spaces 23 and 24 via an air supply duct 25. The air handling unit 31 exhausts the air from spaces 23 and 24 to the outside of the building 13 via an exhaust duct 16 using a ventilation fan 26.

[0014] The water coil 32 is connected to the heat source unit 40. The water coil 32 is a heat exchanger that functions as a cooler for the outside air. The water coil 32 has heat transfer tubes and heat transfer fins. In the water coil 32, heat exchange takes place between the outside air passing around the heat transfer tubes and heat transfer fins and the heat transfer medium passing through the heat transfer tubes. The humidifier 30 humidifies the outside air that has passed through the water coil 32. The air handling unit blower 29 is a blower that takes outside air into the air handling unit 31 and sends it to the supply air duct 25.

[0015] The air handling unit 31 is equipped with various sensors. These sensors include an outside air temperature sensor and an outside air humidity sensor that detect the temperature and humidity of the outside air drawn into the unit. Additionally, the unit is equipped with a sensor that detects the temperature of the supply air sent to the supply air duct 25.

[0016] The air supply duct 25 receives outside air through the air conditioning unit blower 29. The air supply duct 25 is connected to the air conditioning unit 31 and the VAV 20. The air conditioning unit control unit 27 consists of a computing unit, memory device, and various electrical components. The air conditioning unit control unit 27 is electrically connected to the control unit 10 and the remote control 22 via a communication line. The air conditioning unit control unit 27 controls the operating capacity of the air conditioning unit 31 according to settings made by the remote control and the temperature of the intake outside air.

[0017] A direct-cooling outdoor unit 12 typically comprises multiple outdoor units and multiple (two in Figure 1) indoor air handling units 21. The outdoor units are connected to the indoor air handling units 21 via refrigerant connecting pipes 19. Various sensors are provided on the outdoor units and indoor air handling units 21. Sensors provided on the outdoor units include an intake pressure sensor that detects the pressure of the refrigerant drawn into the compressor and a discharge pressure sensor that detects the pressure of the refrigerant discharged from the compressor. Sensors provided on the indoor air handling units 21 include sensors that detect the temperature, humidity, and carbon dioxide concentration of the indoor air drawn into the indoor air handling unit 21.

[0018] The air conditioning control unit 18 is an example of an indoor air conditioning control unit. The air conditioning control unit 18 consists of a computing device, a memory device, various electrical components, etc. The air conditioning control unit 18 is connected to the direct-cooling outdoor unit 12, the indoor air conditioning unit 21 and its sensors, and the remote control 22 via communication lines. The air conditioning control unit 18 controls the operating capacity of the direct-cooling outdoor unit 12 and the indoor air conditioning unit 21 according to settings made by the remote control and the indoor temperature.

[0019] The control unit 10 controls the entire air conditioning system 17. The control unit 10 consists of a computing device and a memory device.

[0020] The communication lines L1, L2, and L3 are communication lines for the air conditioner control unit 18 and the external unit control unit 27 to communicate with each other. The air conditioner control unit 18 communicates via the direct room outdoor unit 12. Also, the external unit control unit 27 communicates via the heat source unit 40. As forms for the air conditioner control unit 18 and the external unit control unit 27 to communicate, there are a first communication form using the communication line L1 and a second communication form using the communication lines L2 and L3. The first communication form is a form of direct communication without passing through the control unit 10. When communicating in the first communication form, the communication lines L2 and L3 are unnecessary. The second communication form is a form in which the direct room outdoor unit 12 and the control unit 10 are connected by the communication line L2, and the heat source unit 40 and the control unit 10 are connected by the communication line L3. Thus, the second communication form is a form of communication passing through the control unit 10. When communicating in the second communication form, the communication line L1 is unnecessary. Regarding the communication method, it is only necessary that the air conditioner control unit 18 and the external unit control unit 27 can communicate with each other. For example, a general-purpose protocol such as Modbus may be used.

[0021] Based on the above configuration, the first embodiment and the second embodiment will be described. [First Embodiment] In the first embodiment, in the first communication form, the air conditioner control unit 18 and the external unit control unit 27 are made capable of communicating with each other. The air conditioner control unit 18 is configured to be able to acquire the operating capacity of the external unit 31 through communication. The external unit control unit 27 is configured to be able to acquire the operating capacity of the internal unit 21 through communication.

[0022] The air conditioner control unit 18 is preset with a first threshold value T1 for comparison with the operating capacity of the outdoor unit 31 and a second threshold value T2 smaller than the first threshold value T1. The first threshold value T1 and the second threshold value T2 are stored in the storage device of the air conditioner control unit 18. The first threshold value T1 and the second threshold value T2 are set via, for example, the control unit 10. When the operating capacity of the outdoor unit 31 is equal to or greater than the first threshold value T1 and the operating capacity of the indoor unit 21 can be increased, the air conditioner control unit 18 increases the operating capacity of the indoor unit 21. Further, when the operating capacity of the outdoor unit 31 is less than the second threshold value T2 and the operating capacity of the indoor unit 21 can be decreased, the air conditioner control unit 18 decreases the operating capacity of the indoor unit 21. The control for decreasing the operating capacity of the indoor unit 21 includes control for stopping the operation of the indoor unit 21.

[0023] The outdoor unit control unit 27 is preset with a third threshold value T3 for comparison with the operating capacity of the indoor unit 21 and a fourth threshold value T4 smaller than the third threshold value T3. The third threshold value T3 and the fourth threshold value T4 are stored in the storage device of the outdoor unit control unit 27. The third threshold value T3 and the fourth threshold value T4 are set via, for example, the control unit 10. When the operating capacity of the indoor unit 21 is equal to or greater than the third threshold value T3 and the operating capacity of the outdoor unit 31 can be increased, the outdoor unit control unit 27 increases the operating capacity of the outdoor unit 31. Further, when the operating capacity of the indoor unit 21 is less than the fourth threshold value T4 and the operating capacity of the outdoor unit 31 can be decreased, the outdoor unit control unit 27 decreases the operating capacity of the outdoor unit 31. The control for decreasing the operating capacity of the outdoor unit 31 includes control for stopping the operation of the outdoor unit 31.

[0024] FIG. 2 is a flowchart showing the processing flow of the air conditioning system 17 in the first embodiment. The air conditioner control unit 18 determines whether the operating capacity of the outdoor unit 31 is equal to or greater than the threshold value T1 (step S101). When the operating capacity of the outdoor unit 31 is equal to or greater than the threshold value T1 (step S101: YES), and when the operating capacity of the indoor unit 21 can be increased, the air conditioner control unit 18 increases the operating capacity of the indoor unit 21 (step S102) and proceeds to step S105.

[0025] If the operating capacity of the outdoor air handling unit 31 is not equal to or greater than the threshold T1 (step S101: NO), the air conditioner control unit 18 determines whether the operating capacity of the outdoor air handling unit 31 is less than the threshold T2 (step S 103 If the operating capacity of the outdoor air handling unit 31 is less than the threshold T2 (step S103: YES), and the operating capacity of the indoor air handling unit 21 can be reduced, the air conditioner control unit 18 reduces the operating capacity of the indoor air handling unit 21 (step S104) and proceeds to step S105. If the operating capacity of the outdoor air handling unit 31 is not less than the threshold T2 (step S103: NO), proceeds to step S105.

[0026] The external air handling unit control unit 27 determines whether the operating capacity of the internal air handling unit 21 is equal to or greater than the threshold T3 (step S105). If the operating capacity of the internal air handling unit 21 is equal to or greater than the threshold T3 (step S105: YES), and the operating capacity of the external air handling unit 31 can be increased, the external air handling unit control unit 27 increases the operating capacity of the external air handling unit 31 (step S106) and terminates the process.

[0027] If the operating capacity of the internal air handling unit 21 is not greater than or equal to the threshold T3 (step S105: NO), the external air handling unit control unit 27 determines whether the operating capacity of the internal air handling unit 21 is less than the threshold T4 (step S107). If the operating capacity of the internal air handling unit 21 is less than the threshold T4 (step S107: YES), and the operating capacity of the external air handling unit 31 can be reduced, the external air handling unit control unit 27 reduces the operating capacity of the external air handling unit 31 (step S108) and terminates the process. If the operating capacity of the internal air handling unit 21 is not less than the threshold T4 (step S107: NO), the process terminates.

[0028] The process shown in Figure 2 above may be a loop process that returns to step S101 after the completion of step S106 or step S108, rather than ending at step S106 or step S108. Alternatively, this process may be performed repeatedly and periodically (for example, every minute). This process may also be performed in accordance with the instructions of the operator of the air conditioning system 17.

[0029] The basic processing flow in the first embodiment is as described above. As shown in the flowchart of Figure 2, the purpose of the processing in this embodiment is to suppress the load imbalance on either the external air handling unit 31 or the internal air handling unit 21. If it is possible to suppress the load imbalance on either the external air handling unit 31 or the internal air handling unit 21, additional processing may be added to or modified from the processing shown in the flowchart of Figure 2.

[0030] Specifically, we will explain an example of processing when thresholds T1 and T3 are set to 80% of the operating capacity, and thresholds T2 and T4 are set to 70% of the operating capacity. First, when the operating capacity of the indoor air handling unit 21 becomes 80% or more, and the set dehumidification performance is achieved, the air conditioner control unit 18 increases the airflow of the indoor air handling unit 21, and the outdoor air handling unit control unit 27 increases the operating capacity of the outdoor air handling unit. If the operating capacity of the indoor air handling unit 21 is less than threshold T1 and greater than or equal to threshold T3, the outdoor air handling unit control unit 27 does not perform airflow correction control, but controls it so that the operating capacity with the indoor air handling unit 21 is equalized. If the operating capacity of the outdoor air handling unit 31 becomes less than 70%, the air conditioner control unit 18 gradually reduces the airflow correction and switches to normal control. Normal control here refers to the control of the direct-cooling outdoor unit 12 and the indoor air handling unit 21, which is performed according to settings made by the remote control and the indoor temperature.

[0031] For example, if the operating capacity of the internal air handling unit 21 exceeds 80%, and the operating capacity of the external air handling unit 31 is 100%, the operating capacity of the external air handling unit 31 cannot be increased. However, if the ventilation airflow is satisfactory, the external air handling unit control unit 27 reduces the load on the external air handling unit 31 (by reducing the airflow, changing the set temperature of the heat source unit, or reducing the water flow rate). As a result, the load on the internal air handling unit 21 increases, but the load on the external air handling unit 31 is reduced, thus preventing the load from becoming unevenly distributed between the external air handling unit 31 and the internal air handling unit 21.

[0032] By controlling in this way, it becomes possible to suppress the load from being biased to either the outdoor unit 31 or the indoor unit 21. As a result, it is possible to avoid the parts of the equipment that has become a high-load operation from being prone to failure and the maintenance cycle of the equipment that has become a high-load operation from decreasing, so that the running cost of the air conditioning system can be suppressed.

[0033] [Second Embodiment] In the second embodiment, the air conditioner control unit 18 and the outdoor unit control unit 27 are capable of communicating in the first communication mode or the second communication mode. The air conditioner control unit 18 is configured to be able to acquire the operating capacity of the outdoor unit 31 through communication. The outdoor unit control unit 27 is configured to be able to acquire the operating capacity of the indoor unit 21 through communication.

[0034] A predetermined value A (>0) for comparing the difference between the operating capacity of the outdoor unit 31 and the operating capacity of the indoor unit 21 is preset in the air conditioner control unit 18. The predetermined value A is stored in the storage device of the air conditioner control unit 18. Similarly, the predetermined value A is preset in the outdoor unit control unit 27. The predetermined value A is stored in the storage device of the outdoor unit control unit 27. The predetermined value A is set, for example, via the control unit 10.

[0035] When the difference between the operating capacity X of the outdoor unit 31 and the operating capacity Y of the indoor unit 21 becomes greater than or equal to the predetermined value A (X - Y ≥ A) and the operating capacity of the indoor unit 21 can be increased, the air conditioner control unit 18 increases the operating capacity of the indoor unit 21. Also, when the difference between the operating capacity of the outdoor unit 31 and the operating capacity of the indoor unit 21 becomes less than the predetermined value (X - Y < A) and the operating capacity of the indoor unit 21 can be decreased, the air conditioner control unit 18 decreases the operating capacity of the indoor unit 21. The control for decreasing the operating capacity of the indoor unit 21 includes the control for stopping the operation of the indoor unit 21.

[0036] When the difference between the operation capacity Y of the internal conditioner 21 and the operation capacity X of the external conditioner 31 becomes larger than a predetermined value A (Y−X≧A) and the operation capacity of the external conditioner 31 can be increased, the external conditioner control unit 27 increases the operation capacity of the external conditioner 31. Also, when the difference between the operation capacity of the internal conditioner 21 and the operation capacity of the external conditioner 31 becomes less than the predetermined value (Y−X<A) and the operation capacity of the external conditioner 31 can be decreased, the external conditioner control unit 27 decreases the operation capacity of the external conditioner 31. The control for decreasing the operation capacity of the external conditioner 31 includes control for stopping the operation of the external conditioner 31.

[0037] FIG. 3 is a flowchart showing the processing flow of the air conditioning system 17 in the second embodiment. In the flowchart of FIG. 3, let the difference (X−Y) between the operation capacity X of the external conditioner 31 and the operation capacity Y of the internal conditioner 21 be Z. Let the difference (Y−X) between the operation capacity Y of the internal conditioner 21 and the operation capacity X of the external conditioner 31 be W.

[0038] The air conditioner control unit 18 determines whether or not the difference Z between the operation capacity X of the external conditioner 31 and the operation capacity Y of the internal conditioner 21 is greater than or equal to a predetermined value A (step S201). When the difference Z between the operation capacity X of the external conditioner 31 and the operation capacity Y of the internal conditioner 21 is greater than or equal to the predetermined value A (step S201: YES) and the operation capacity of the internal conditioner 21 can be increased, the air conditioner control unit 18 increases the operation capacity of the internal conditioner 21 (step S202) and proceeds to step S205.

[0039] If the difference Z between the operating capacity X of the outdoor air handling unit 31 and the operating capacity Y of the indoor air handling unit 21 is not greater than or equal to a predetermined value A (step S201: NO), the air conditioner control unit 18 determines whether the difference Z between the operating capacity X of the outdoor air handling unit 31 and the operating capacity Y of the indoor air handling unit 21 has fallen below the predetermined value A (step S203). If the difference Z between the operating capacity X of the outdoor air handling unit 31 and the operating capacity Y of the indoor air handling unit 21 has fallen below the predetermined value A (step S203: YES), and the operating capacity of the indoor air handling unit 21 can be reduced, the air conditioner control unit 18 reduces the operating capacity of the indoor air handling unit 21 (step S204) and proceeds to step S205. If the difference Z between the operating capacity X of the external air handling unit 31 and the operating capacity Y of the internal air handling unit 21 has not fallen below a predetermined value A (step S203: NO), proceed to step S205.

[0040] The external air handling unit control unit 27 determines whether the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 is greater than or equal to a predetermined value A (step S205). If the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 is greater than or equal to a predetermined value A (step S205: YES), and the operating capacity of the external air handling unit 31 can be increased, the external air handling unit control unit 27 increases the operating capacity of the external air handling unit 31 (step S206) and terminates the process.

[0041] If the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 is not greater than or equal to a predetermined value A (step S205: NO), the external air handling unit control unit 27 determines whether the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 has fallen below the predetermined value A from a state in which it was greater than or equal to a predetermined value A (step S207). If the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 has fallen below the predetermined value A from a state in which it was greater than or equal to a predetermined value A (step S207: YES), and the operating capacity of the external air handling unit 31 can be reduced, the external air handling unit control unit 27 reduces the operating capacity of the external air handling unit 31 (step S208) and terminates the process. If the difference W between the operating capacity Y of the internal air handling unit 21 and the operating capacity X of the external air handling unit 31 has not fallen below the predetermined value A from a state in which it was greater than or equal to a predetermined value A (step S207: NO), the process terminates.

[0042] The process shown in Figure 3 above may be performed periodically (for example, every minute) or in accordance with the instructions of the operator of the air conditioning system 17.

[0043] The basic processing flow in the second embodiment is as described above. As shown in the flowchart of Figure 3, the purpose of the processing in this embodiment is to prevent the load from being unevenly distributed to either the external air handling unit 31 or the internal air handling unit 21. If it is possible to prevent the load from being unevenly distributed to either the external air handling unit 31 or the internal air handling unit 21, additional processing may be added to or modified from the processing shown in the flowchart of Figure 3.

[0044] Let's explain a specific example of processing when the predetermined value A is set to 20%. When the difference W between the operating capacity Y of the indoor air handling unit 21 and the operating capacity X of the outdoor air handling unit 31 is 20% or more, it is assumed that this is the operating capacity at which the dehumidification performance of the outdoor air handling unit 31 can be obtained. In this case, the outdoor air handling unit control unit 27 increases the operating capacity of the outdoor air handling unit 31 by increasing the airflow or decreasing the discharge temperature. This equalizes the load, thus preventing the load from being unevenly distributed between the outdoor air handling unit 31 and the indoor air handling unit 21. When the difference W between the operating capacity Y of the indoor air handling unit 21 and the operating capacity X of the outdoor air handling unit 31 falls below 20% from a state of 20% or more, the air conditioner control unit 18 stops the operation of the indoor air handling unit 21, and the outdoor air handling unit control unit 27 performs normal control of only the outdoor air handling unit 31. Normal control here refers to control by the outdoor air handling unit control unit 27, which is performed according to settings made via the remote control or the temperature of the intake outside air. By stopping the equipment with the highest load among the external air handling unit 31 and the internal air handling unit 21 in this way, the operating time of the equipment with the highest load is reduced.

[0045] This makes it possible to prevent the load from being unevenly distributed to either the outdoor air handling unit 31 or the indoor air handling unit 21. This prevents equipment under heavy load from being prone to failure and reduces the maintenance cycle of such equipment, thereby lowering the running costs of the air conditioning system.

[0046] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0047] 10...Control unit, 12...Direct-type outdoor unit, 14, 15...Building, 16...Exhaust duct, 17...Air conditioning system, 18...Air conditioner control unit, 19...Refrigerant connecting pipe, 21...Indoor air handling unit, 22...Remote control, 23, 24...Space, 25...Intake duct, 26...Ventilation fan, 27...Outdoor air handling unit control unit, 28...Intake duct, 29...Outdoor air handling unit blower, 30...Humidifier, 31...Outdoor air handling unit, 32...Water coil, 34...Intake port, 40...Heat source unit, L1, L2, L3...Communication lines

Claims

1. An air conditioning system including an indoor air handling unit and an outdoor air handling unit, An internal air handling unit control unit increases the operating capacity of the internal air handling unit when the operating capacity of the external air handling unit is equal to or greater than a first threshold and the operating capacity of the internal air handling unit can be increased, and decreases the operating capacity of the internal air handling unit when the operating capacity of the external air handling unit is less than a second threshold which is smaller than the first threshold and the operating capacity of the internal air handling unit can be decreased, When the operating capacity of the internal air handling unit becomes equal to or greater than the third threshold and the operating capacity of the external air handling unit can be increased, the external air handling unit control unit increases the operating capacity of the external air handling unit. When the operating capacity of the internal air handling unit becomes less than the fourth threshold, which is smaller than the third threshold, and the operating capacity of the external air handling unit can be decreased, the external air handling unit control unit decreases the operating capacity of the external air handling unit. Equipped with an air conditioning system.

2. An air conditioning system including an indoor air handling unit and an outdoor air handling unit, An internal air handling unit control unit increases the operating capacity of the internal air handling unit if the difference between the operating capacity of the external air handling unit and the operating capacity of the internal air handling unit becomes greater than or equal to a predetermined value and the operating capacity of the internal air handling unit can be increased, and decreases the operating capacity of the internal air handling unit if the difference between the operating capacity of the external air handling unit and the operating capacity of the internal air handling unit becomes less than the predetermined value and the operating capacity of the internal air handling unit can be decreased, An external air handling unit control unit increases the operating capacity of the external air handling unit if the difference between the operating capacity of the internal air handling unit and the operating capacity of the external air handling unit becomes greater than or equal to a predetermined value and the operating capacity of the external air handling unit can be increased, and decreases the operating capacity of the external air handling unit if the difference between the operating capacity of the internal air handling unit and the operating capacity of the external air handling unit becomes less than the predetermined value and the operating capacity of the external air handling unit can be decreased, Equipped with an air conditioning system.

3. A control method for an air conditioning system including an indoor air handling unit and an outdoor air handling unit, If the operating capacity of the external air handling unit becomes equal to or greater than a first threshold and the operating capacity of the internal air handling unit can be increased, the operating capacity of the internal air handling unit is increased. If the operating capacity of the external air handling unit becomes less than a second threshold, which is smaller than the first threshold, and the operating capacity of the internal air handling unit can be decreased, the operating capacity of the internal air handling unit is decreased. A control method which increases the operating capacity of the external air handling unit when the operating capacity of the internal air handling unit is equal to or greater than a third threshold and the operating capacity of the external air handling unit can be increased, and decreases the operating capacity of the external air handling unit when the operating capacity of the internal air handling unit is less than a fourth threshold which is less than the third threshold and the operating capacity of the external air handling unit can be decreased.

4. A control method for an air conditioning system including an indoor air handling unit and an outdoor air handling unit, If the difference between the operating capacity of the external air handling unit and the operating capacity of the internal air handling unit becomes greater than or equal to a predetermined value, and the operating capacity of the internal air handling unit can be increased, the operating capacity of the internal air handling unit is increased. If the difference between the operating capacity of the external air handling unit and the operating capacity of the internal air handling unit becomes less than the predetermined value, and the operating capacity of the internal air handling unit can be decreased, the operating capacity of the internal air handling unit is decreased. A control method that increases the operating capacity of the external air handling unit if the difference between the operating capacity of the internal air handling unit and the operating capacity of the external air handling unit becomes greater than or equal to a predetermined value and the operating capacity of the external air handling unit can be increased, and decreases the operating capacity of the external air handling unit if the difference between the operating capacity of the internal air handling unit and the operating capacity of the external air handling unit becomes less than the predetermined value and the operating capacity of the external air handling unit can be decreased.

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