air conditioning system

Abstract

To provide an air conditioning system that can reduce the amount of leakage of refrigerant gas when the refrigerant gas leaks, and can be operated with high efficiency.SOLUTION: An air conditioning system comprises a plurality of air conditioning units 71A, 71B, and 71C. The air conditioning units 71A, 71B, and 71C include a multiple air conditioning outdoor machines 100A, 100B, and 100C, and a plurality of indoor machines connected to the multiple air conditioning outdoor machines 100A, 100B, and 100C respectively. A refrigerant flows between the multiple air conditioning outdoor machines 100A, 100B, and 100C and the plurality of indoor machines. The multiple air conditioning outdoor machines 100A, 100B, and 100C include inter-outdoor machine heat exchange units 20 for exchanging heat between the refrigerant and a heat medium. The air conditioning system comprises a first pipe 91 and a second pipe 92 connecting the inter-outdoor machine heat exchange units 20 of the plurality of multiple air conditioning outdoor machines 100A, 100B, and 100C, and through which the heat medium flows.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to air conditioning systems. [Background technology]

[0002] Multi-air conditioners are becoming larger due to factors such as the replacement of central systems. As a result, the amount of refrigerant gas filled into one system is also increasing. Since it is rare for all indoor units to require maximum capacity at the same time, it is possible to connect indoor units with a total capacity that exceeds the capacity of the outdoor unit. However, if the total required capacity of the indoor units exceeds the capacity of the outdoor unit, each indoor unit will not be able to perform at 100% of its capacity.

[0003] Systems that enable heat transfer between air conditioning units of different systems are known. For example, in the system described in Patent Document 1, a refrigerant heat exchanger exchanges heat between a refrigerant that has left the outdoor heat exchanger of a first air conditioning unit and then flowed into the refrigerant heat exchanger, and a refrigerant that has left the outdoor heat exchanger of a second air conditioning unit and then flowed into the refrigerant heat exchanger, thereby enabling heat transfer between the systems from the first air conditioning unit to the second air conditioning unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-164423 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the system described in Patent Document 1, the refrigerant used in the first air conditioning unit and the refrigerant used in the second air conditioning unit must be circulated through a refrigerant heat exchanger disposed between the first and second air conditioning units, which increases the amount of refrigerant gas required to be charged, and as a result, the amount of refrigerant gas leaking increases.

[0006] Therefore, an object of the present disclosure is to provide an air conditioning system that can suppress the amount of refrigerant gas leakage in the event of a refrigerant gas leak and that can operate with high efficiency. [Means for solving the problem]

[0007] The air conditioning system of the present disclosure includes a plurality of air conditioning units. Each air conditioning unit includes a multi-air conditioner outdoor unit and a plurality of indoor units each connected to the multi-air conditioner outdoor unit. A refrigerant flows between the multi-air conditioner outdoor unit and the plurality of indoor units. The multi-air conditioner outdoor unit includes an inter-outdoor-unit heat exchange unit that exchanges heat between the refrigerant and a heat medium. The air conditioning system includes first and second pipes that connect the inter-outdoor-unit heat exchange units of the plurality of multi-air conditioner outdoor units and through which the heat medium flows. [Effects of the Invention]

[0008] According to the present disclosure, the heat medium flows through the first and second pipes between the plurality of inter-outdoor heat exchange units that exchange heat between the refrigerant and the heat medium, which makes it possible to suppress the amount of refrigerant gas leakage in the event of a refrigerant gas leak and enables highly efficient operation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of an air conditioning system of Reference Example 1. FIG. [Figure 2] FIG. 10 is a diagram showing the configuration of an air conditioning system of Reference Example 2. [Figure 3] 1 is a diagram showing the configuration of an air conditioning system according to a first embodiment. [Figure 4] 3 is a diagram showing the flow of refrigerant and heat refrigerant in the air conditioning system during cooling, and the states of solenoid valves SV1 to SV10. FIG. [Figure 5] 1A, 1B, and 1C are diagrams showing the states of a three-way electromagnetic valve. [Figure 6] 5 is a flowchart showing a control procedure of the air conditioning system shown in FIG. [Figure 7] 3 is a diagram showing the flow of refrigerant and heat refrigerant in the air conditioning system during heating, and the states of solenoid valves SV1 to SV10. FIG. [Figure 8] FIG. 1 is a diagram showing the flow of refrigerant and heat refrigerant and the states of solenoid valves SV1 to SV10 in an air conditioning system in which some outdoor units of multi-air conditioners operate in cooling mode throughout the year and the remaining outdoor units of multi-air conditioners operate in heating mode. [Figure 9] 10 is a diagram showing the flows of refrigerant and heat refrigerant and the states of solenoid valves SV1 to SV10 in a first modification of the third embodiment. FIG. [Figure 10] 10 is a diagram showing the flows of refrigerant and heat refrigerant and the states of solenoid valves SV1 to SV10 in a second modification of the third embodiment. FIG. [Figure 11] 13 is a flowchart showing a procedure for setting the operation modes of three outdoor units of a multi-air conditioner in a second modification of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. (Reference example 1) FIG. 1 is a diagram showing the configuration of an air conditioning system according to a first reference example.

[0011] Eighteen indoor units IU1 to IU18 are connected to three multi-air conditioner outdoor units 300A, 300B, and 300C.

[0012] If the sum of the required capacities of the indoor units IU1 to IU18 is greater than the sum of the capacities of the multi-air conditioner outdoor units 300A, 300B, and 300C, each indoor unit IUi (i = 1 to 18) cannot perform at 100% of its capacity. If a refrigerant gas leak occurs in room X, all refrigerant gas in the system will leak from room X. As a result, the air in room X will be replaced with refrigerant gas, resulting in an oxygen deficiency. To prevent oxygen deficiency, the value obtained by dividing the amount of refrigerant gas leakage by the volume of the room must be kept below an allowable value. As a result, the minimum volume of the room in which an indoor unit can be installed will increase.

[0013] (Reference example 2) FIG. 2 is a diagram showing the configuration of an air conditioning system according to a second reference example.

[0014] Six indoor units IU1 to IU6 are connected to the multi-air conditioner outdoor unit 200A. Six indoor units IU7 to IU12 are connected to the multi-air conditioner outdoor unit 200B. Six indoor units IU13 to IU18 are connected to the multi-air conditioner outdoor unit 200C.

[0015] If the sum of the required capacities of the indoor units IU1 to IU6 is greater than the capacity of the multi-air conditioner outdoor unit 200A, each indoor unit IUi (i = 1 to 6) will not be able to demonstrate 100% of its capacity. If the sum of the required capacities of the indoor units IU7 to IU12 is greater than the capacity of the multi-air conditioner outdoor unit 200B, each indoor unit IUi (i = 7 to 12) will not be able to demonstrate 100% of its capacity. If the sum of the required capacities of the indoor units IU13 to IU18 is greater than the capacity of the multi-air conditioner outdoor unit 200C, each indoor unit IUi (i = 13 to 18) will not be able to demonstrate 100% of its capacity.

[0016] If a refrigerant gas leak occurs in room X, only the refrigerant gas flowing through the multi-air conditioner outdoor unit 200C leaks from room X. In reference example (2), the amount of refrigerant gas leakage can be reduced compared to reference example (1). As a result, the indoor unit can be installed in a smaller room compared to reference example (1).

[0017] Embodiment 1 FIG. 3 is a diagram showing the configuration of the air conditioning system according to the first embodiment.

[0018] The air conditioning system includes air conditioning units 71A, 71B, and 71C, a first pipe 91, and a second pipe 92.

[0019] Air conditioning unit 71A includes a multi-air conditioner outdoor unit 100A and six indoor units IU1 to IU6 connected to the multi-air conditioner outdoor unit 100A. Air conditioning unit 71B includes a multi-air conditioner outdoor unit 100B and six indoor units IU7 to IU12 connected to the multi-air conditioner outdoor unit 100B. Air conditioning unit 71C includes a multi-air conditioner outdoor unit 100C and six indoor units IU13 to IU18 connected to the multi-air conditioner outdoor unit 100C.

[0020] Each of the multi-air conditioner outdoor units 100A, 100B, and 100C is equipped with an inter-outdoor-unit heat exchange unit 20. The multiple inter-outdoor-unit heat exchange units 20 are connected by a first pipe 91 and a second pipe 92. A heat medium flows through the first pipe 91 and the second pipe 92. In each inter-outdoor-unit heat exchange unit 20, heat is exchanged between the refrigerant and the heat medium. Heat is transferred by the heat medium from a multi-air conditioner outdoor unit whose total required capacity of the multiple indoor units connected to it does not exceed its own capacity to a multi-air conditioner outdoor unit whose required capacity of the multiple indoor units connected to it exceeds its own capacity.

[0021] When the sum of the required capacities of the multiple connected indoor units exceeds the capacity of outdoor unit X of a multi-air conditioner, even if the amount of refrigerant circulated is increased by inverter driving the compressor according to the required capacity of the indoor units, the capacity of the outdoor heat exchanger remains constant, resulting in a shortage of heat exchange capacity. This shortage is supplied via a heat medium from outdoor unit Y of a multi-air conditioner, whose sum of the required capacities of the multiple connected indoor units does not exceed its own capacity. As a result, each indoor unit connected to outdoor unit X of a multi-air conditioner, whose sum of the required capacities of the multiple connected indoor units exceeds its own capacity, can demonstrate capacity closer to 100%, which is greater than when outdoor unit X of a multi-air conditioner is operating alone.

[0022] If a refrigerant gas leak occurs in room X, the refrigerant gas flowing through the multi-air conditioner outdoor unit 100C will leak from room X. In embodiment 1, the amount of refrigerant gas leakage can be reduced compared to reference example (1). As a result, the indoor unit can be installed in a smaller room compared to reference example (1).

[0023] In Patent Document 1, the refrigerant used in the first air conditioning unit must be circulated through a refrigerant heat exchanger disposed between the first and second air conditioning units, and the refrigerant used in the second air conditioning unit must be circulated through the refrigerant heat exchanger. In contrast, in Embodiment 1, the refrigerant only needs to be circulated through each of air conditioning units 71A, 71B, and 71C, so the amount of refrigerant charged can be reduced, and the amount of refrigerant leakage can be reduced if a refrigerant leak occurs.

[0024] (Operation when all outdoor units of multi-air conditioners are in cooling operation) Fig. 4 is a diagram showing the flow of refrigerant and heat refrigerant in the air conditioning system during cooling, and the states of solenoid valves SV1 to SV10. Fig. 4 shows a more detailed configuration of the air conditioning system.

[0025] The air conditioning system includes a plurality of indoor units, multi-air conditioner outdoor units 100A, 100B, and 100C each connected to a corresponding plurality of indoor units, a multi-air conditioner controller 21, a first pipe 91, a second pipe 92, and temperature sensors TH3 and TH4.

[0026] The temperature sensor TH3 detects the temperature of the first pipe 91. The temperature sensor TH4 detects the temperature of the second pipe 92.

[0027] The outdoor unit 100 of a multi-air conditioner includes a compressor 1, a four-way valve 2, a fan 4, a fan motor 6, an outdoor heat exchanger 3, a controller 5, an inter-outdoor unit heat exchange unit 20, a temperature sensor TH1, and a pressure sensor PS1. The inter-outdoor unit heat exchange unit 20 includes a heat exchanger 8, an expansion valve 10, a circulation pump 7, and solenoid valves SV1 to SV10. The solenoid valves SV8 to SV10 are three-way solenoid valves.

[0028] The four-way valve 2 is connected to the compressor 1, the outdoor heat exchanger 3, and the indoor unit. Solenoid valve SV1 is arranged between a first port of heat exchanger 8 and a first branch on the piping between the outdoor heat exchanger 3 and the indoor unit. Expansion valve 10 and solenoid valve SV2 are arranged between the first port of heat exchanger 8 and a second branch on the piping between the outdoor heat exchanger 3 and the indoor unit. Solenoid valve SV3 is arranged between a second port of heat exchanger 8 and the four-way valve 2. Solenoid valve SV4 is arranged between a first piping 91 and a third port of solenoid valve SV8. Solenoid valve SV5 is arranged between a second piping 92 and a third port of solenoid valve SV8. Solenoid valve SV6 is arranged between the second piping 92 and the circulation pump 7. Solenoid valve SV7 is arranged between the first piping 91 and the circulation pump 7. The first port of solenoid valve SV8 is connected to the third port of heat exchanger 8. The second port of solenoid valve SV8 is connected to the circulation pump 7. A first port of the solenoid valve SV9 is connected to a fourth port of the heat exchanger 8. A second port of the solenoid valve SV9 is connected to the circulation pump 7. A first port of the solenoid valve SV10 is connected to the outdoor heat exchanger 3. A second port of the solenoid valve SV10 is connected to the indoor unit.

[0029] The temperature sensor TH1 detects the temperature of the piping between the outdoor heat exchanger 3 and the inter-outdoor-unit heat exchange unit 20. The pressure sensor PS1 detects the pressure of the piping between the outdoor heat exchanger 3 and the inter-outdoor-unit heat exchange unit 20.

[0030] The inter-outdoor-unit heat exchange units 20 of each of the multi-air conditioner outdoor units 100A, 100B, 100C are connected by a first pipe 91 and a second pipe 92.

[0031] The states of the solenoid valves SV1 to SV7 are "open" or "closed." When the solenoid valves SV1 to SV7 are "open," refrigerant flows through the solenoid valves SV1 to SV7. When the solenoid valves are "closed," refrigerant does not flow through the two-way solenoid valves.

[0032] The states of the three-way solenoid valves SV8 to SV10 are "direct", "L" or "connected". 5(a), (b), and (c) are diagrams showing the states of the three-way electromagnetic valve.

[0033] As shown in FIG. 5(a), when the three-way solenoid valves SV8 to SV10 are in the "direct" state, the refrigerant flows straight between the first port P1 and the second port P2 of the three-way solenoid valves SV8 to SV10 (direct route).

[0034] As shown in Figure 5(b), when the three-way solenoid valves SV8 to SV10 are in the "L" state, the refrigerant flows through an L-shaped route (bypass route) from the third port P3 of each of the three-way solenoid valves SV8 to SV10 to the first port P1 or the second port P2.

[0035] As shown in Figure 5(c), when the three-way solenoid valves SV8 to SV10 are in the "connected" state, the refrigerant flowing in from the first port P1 or the second port P2 and the refrigerant flowing in from the third port P3 join together and flow out from the first port P1 or the second port P2.

[0036] The multi-air conditioner controller 21 controls each air conditioning unit. Fig. 6 is a flowchart showing the control procedure of the air conditioning system shown in Fig. 4. The processing of steps S101 to S104 is repeated.

[0037] In step S101, the multi-air conditioner controller 21 obtains the capacity CPA of the multi-air conditioner outdoor unit 100A, the sum RQA of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit 100A, the capacity CPB of the multi-air conditioner outdoor unit 100B, the sum RQB of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit 100B, the capacity CPC of the multi-air conditioner outdoor unit 100C, and the sum RQC of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit 100C.

[0038] In step S102, the multi-air conditioner controller 21 sets the operation modes of the multi-air conditioner outdoor units 100A, 100B, and 100C.

[0039] When there is one multi-air conditioner outdoor unit X whose total required capacity of multiple connected indoor units does not exceed its own capacity, and one multi-air conditioner outdoor unit Y whose total required capacity of multiple connected indoor units exceeds its own capacity, the multi-air conditioner controller 21 sets X to a heat supply mode (first mode) and Y to a heat reception mode (second mode).The multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit whose total capacity and required capacity are equal to each other to a self-contained mode (third mode).

[0040] In the example of FIG. 4, the following relationship holds, so the multi-air conditioner outdoor unit 100A is set to the first mode, the multi-air conditioner outdoor unit 100B is set to the third mode, and the multi-air conditioner outdoor unit 100C is set to the second mode.

[0041] CPA>RQA CPB=RQB CPC <RQC In step S103, the multi-air conditioner control device 21 instructs the controller 5 of each multi-air conditioner outdoor unit to select the operation mode of each multi-air conditioner outdoor unit.

[0042] In step S104, the controller 5 of each outdoor unit of a multi-air conditioner controls the internal solenoid valves SV1 to SV10 so that the outdoor unit operates in the instructed operation mode.

[0043] The operation of each outdoor unit of the multi-air conditioner will be explained below. In the multi-air conditioner outdoor unit 100A set to the heat supply mode (first mode), the refrigerant expands after passing through the expansion valve in the indoor unit and evaporates (heats and vaporizes) in the indoor heat exchanger (evaporator) and is sent through a gas pipe. The refrigerant sent from the indoor unit flows into the compressor 1 through the four-way valve 2. The refrigerant discharged from the compressor 1 passes through the four-way valve 2 and is sent to the outdoor heat exchanger 3. In the outdoor heat exchanger 3, the refrigerant is cooled by heat exchange with air that has passed through the outdoor heat exchanger 3 using the fan 4. A portion of the cooled refrigerant (the amount required by the indoor unit) passes through the solenoid valve SV10 and is sent to the indoor unit. The remainder (excess amount) passes through the solenoid valve SV2 and the expansion valve 10 and is sent to the heat exchanger 8. The heat medium sent from the multi-air conditioner outdoor unit 100C through the first pipe 91 passes through the solenoid valve SV7 and is sent to the circulation pump 7. The refrigerant flowing out of the circulation pump 7 passes through the solenoid valve SV9 and is sent to the heat exchanger 8. The refrigerant that has been warmed by exchanging heat with the heat medium in heat exchanger 8 is sent to compressor 1 via solenoid valve SV3 and four-way valve 2. The heat medium that has been cooled by exchanging heat with the refrigerant in heat exchanger 8 is sent to second piping 92 via solenoid valves SV8 and SV5. The amount of refrigerant circulating in air conditioning unit 71A is made variable by driving compressor 1 with an inverter according to the amount required by the indoor unit and the amount supplied to multi-air conditioner outdoor unit 100C that has insufficient capacity.

[0044] In the multi-air conditioner outdoor unit 100C set to the heat receiving mode (second mode), the refrigerant that expands after passing through the expansion valve in the indoor unit evaporates (heated and vaporized) in the indoor heat exchanger (evaporator) and is sent through the gas piping. The refrigerant sent from the indoor unit flows into the compressor 1 through the four-way valve 2. The refrigerant released from the compressor 1 passes through the four-way valve 2 and is sent to the outdoor heat exchanger 3. In the outdoor heat exchanger 3, the refrigerant is cooled by heat exchange with air that has passed through the outdoor heat exchanger 3 using the fan 4. The cooled refrigerant is sent to the heat exchanger 8 through the solenoid valve SV1. The heat medium sent from the multi-air conditioner outdoor unit 100A through the second piping 92 is sent to the circulation pump 7 through the solenoid valve SV6. The refrigerant flowing out of the circulation pump 7 is sent to the heat exchanger 8 through the solenoid valve SV9. The refrigerant that has been cooled by heat exchange with the heat medium in the heat exchanger 8 is sent to the indoor unit through the solenoid valve SV10. The heat medium heated by heat exchange with the refrigerant in heat exchanger 8 passes through solenoid valves SV8 and SV4 and is sent to first pipe 91. The target value for the amount of refrigerant circulating in air conditioning unit 71C is the sum of the required capacities of the indoor units in air conditioning unit 71C. Any shortage is made up for by the amount supplied from multi-air conditioner outdoor unit 100A, which has surplus capacity.

[0045] In a multi-air conditioner outdoor unit 100B set to self-contained mode (third mode), refrigerant expands after passing through an expansion valve in the indoor unit, evaporates (heats and vaporizes) in the indoor heat exchanger (evaporator), and is sent through a gas pipe. The refrigerant sent from the indoor unit flows into compressor 1 via four-way valve 2. The refrigerant released from compressor 1 passes through four-way valve 2 and is sent to outdoor heat exchanger 3. In outdoor heat exchanger 3, the refrigerant is cooled by exchanging heat with air that has passed through outdoor heat exchanger 3 using fan 4. The cooled refrigerant is sent to the indoor unit via solenoid valve SV10. The amount of refrigerant circulating in air conditioning unit 71B is variable by driving compressor 1 with an inverter according to the amount of air required by the indoor unit.

[0046] The amount of heat medium circulated can be determined by the amount of heat exchanged between the multi-air conditioner outdoor unit 100A and the multi-air conditioner outdoor unit 100C, based on the temperature of the first pipe 91 detected by temperature sensor TH3, the temperature of the second pipe 92 detected by temperature sensor TH4, and the operating state of the circulation pump 7. The circulation amount of the heat medium is made variable by driving the circulation pumps 7 of each of the multi-air conditioner outdoor units 100A and 100C with an inverter.

[0047] Embodiment 2 In this embodiment, an operation when all the outdoor units of the multi-air conditioner are in heating operation will be described.

[0048] FIG. 7 is a diagram showing the flow of the refrigerant and the heat refrigerant in the air conditioning system during heating, and the states of the solenoid valves SV1 to SV10.

[0049] In the example of FIG. 7, the following relationship holds, so the multi-air conditioner outdoor unit 100A is set to the first mode, the multi-air conditioner outdoor unit 100B is set to the third mode, and the multi-air conditioner outdoor unit 100C is set to the second mode.

[0050] CPA>RQA CPB=RQB CPC <RQC In the multi-air conditioner outdoor unit 100A set to the heat supply mode (first mode), a portion of the refrigerant discharged from the compressor 1 and passing through the four-way valve 2 (the amount required by the indoor unit) is sent to the indoor unit. The remaining refrigerant (excess refrigerant) is sent to the heat exchanger 8 via the solenoid valve SV3. The heat medium sent from the multi-air conditioner outdoor unit 100C through the first piping 91 is sent to the circulation pump 7 via the solenoid valve SV7. The refrigerant flowing out of the circulation pump 7 is sent to the heat exchanger 8 via the solenoid valve SV8. The refrigerant is cooled and condensed in the indoor heat exchanger (condenser) and passes through the expansion valve, then passes through the solenoid valve SV10 and is sent to the outdoor heat exchanger 3. The refrigerant cooled by heat exchange with the heat medium in the heat exchanger 8 is sent to the outdoor heat exchanger 3 via the expansion valve 10 and the solenoid valve SV2. In the outdoor heat exchanger 3, the refrigerant is heated by exchanging heat with the air that has passed through the outdoor heat exchanger 3 using the fan 4. The heated refrigerant passes through four-way valve 2 and flows into compressor 1. The heat medium that has been heated by heat exchange with the refrigerant in heat exchanger 8 passes through solenoid valves SV9 and SV5 and is sent to second piping 92. The amount of refrigerant circulating in air conditioning unit 71A is made variable by driving compressor 1 with an inverter depending on the amount supplied to the indoor unit and the amount supplied to multi-air conditioner outdoor unit 100C with insufficient capacity.

[0051] In the multi-air conditioner outdoor unit 100C set to the heat receiving mode (second mode), the refrigerant discharged from the compressor 1 and passing through the four-way valve 2 is sent to the indoor unit. The refrigerant is cooled and condensed in the indoor heat exchanger (condenser) and passes through the expansion valve, then passes through the solenoid valve SV10 and is sent to the heat exchanger 8. The heat medium sent from the multi-air conditioner outdoor unit 100A through the second piping 92 is sent to the circulation pump 7 via the solenoid valve SV6. The refrigerant flowing out of the circulation pump 7 is sent to the heat exchanger 8 via the solenoid valve SV8. The refrigerant warmed by heat exchange with the heat medium in the heat exchanger 8 is sent to the outdoor heat exchanger 3 via the solenoid valve SV1. In the outdoor heat exchanger 3, the refrigerant is warmed by heat exchange with the air that has passed through the outdoor heat exchanger 3 using the fan 4. The warmed refrigerant flows into the compressor 1 via the four-way valve 2. The heat medium cooled by heat exchange with the refrigerant in heat exchanger 8 passes through solenoid valves SV9 and SV4 and is sent to first pipe 91. The target value for the amount of refrigerant circulating in air conditioning unit 71C is the sum of the amounts required by the indoor units in air conditioning unit 71C. Any shortage is made up for by the amount supplied from multi-air conditioner outdoor unit 100A, which has surplus capacity.

[0052] In a multi-air conditioner outdoor unit 100B set to self-contained mode (third mode), the refrigerant discharged from compressor 1 and passing through four-way valve 2 is sent to the indoor unit. The refrigerant is cooled and condensed in the indoor heat exchanger (condenser) and passes through an expansion valve, then passes through solenoid valve SV10 and is sent to outdoor heat exchanger 3. In outdoor heat exchanger 3, the refrigerant is heated by fan 4 through heat exchange with air that has passed through outdoor heat exchanger 3. The heated refrigerant flows into compressor 1 through four-way valve 2. The amount of refrigerant circulating in air conditioning unit 71B is made variable by driving compressor 1 with an inverter according to the amount of air required by the indoor unit.

[0053] The amount of heat medium circulated can be determined by the amount of heat exchanged between the multi-air conditioner outdoor units 100A and 100C, based on the temperature of the first pipe 91 detected by temperature sensor TH3, the temperature of the second pipe 92 detected by temperature sensor TH4, and the operating state of the circulation pump 7. The circulation amount of the heat medium is made variable by driving the circulation pumps 7 of each of the multi-air conditioner outdoor units 100A and 100C with an inverter.

[0054] Embodiment 3 In this embodiment, an operation will be described in which some of the outdoor units of multi-air conditioners perform cooling operation throughout the year, and the remaining outdoor units perform heating operation.

[0055] FIG. 8 is a diagram showing the flow of refrigerant and heat refrigerant and the states of solenoid valves SV1 to SV10 in an air conditioning system in which some outdoor units of multi-air conditioners operate in cooling mode throughout the year and the remaining outdoor units of multi-air conditioners operate in heating mode.

[0056] The multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit X, which operates in cooling mode all year round, to heat supply mode (first mode). The multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit Y, whose total required capacity of the multiple indoor units connected to it exceeds its own capacity, to heat reception mode (second mode). The multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit, whose total capacity and required capacity are equal, to self-contained mode (third mode).

[0057] In a multi-air conditioner outdoor unit Y, where the sum of the required capacities of the multiple connected indoor units exceeds its own capacity, the capacity of the outdoor heat exchanger remains constant even if the refrigerant circulation volume is increased by inverter driving the compressor according to the required capacity of the indoor units, resulting in a shortage of heat exchange capacity. This insufficient heat exchange capacity is made up for by the condensation heat supplied from multi-air conditioner outdoor unit X, which operates in cooling mode year-round. As a result, each indoor unit connected to multi-air conditioner outdoor unit Y can perform at nearly 100% of its capacity, greater than when multi-air conditioner outdoor unit Y is operating alone.

[0058] In the example of Figure 8, the multi-air conditioner outdoor unit 100A operates in cooling mode all year round. The multi-air conditioner outdoor units 100B and 100C operate in heating mode. Furthermore, since the following relationship holds, the multi-air conditioner outdoor unit 100A is set to the first mode, the multi-air conditioner outdoor unit 100C is set to the second mode, and the multi-air conditioner outdoor unit 100B is set to the third mode.

[0059] CPC <RQC CPB=RQB In the multi-air conditioner outdoor unit 100A set to the heat supply mode (first mode), the refrigerant that has expanded after passing through the expansion valve in the indoor unit evaporates (heated and vaporized) in the indoor heat exchanger (evaporator) and is sent through a gas piping. The refrigerant sent from the indoor unit flows into the compressor 1 through the four-way valve 2. The refrigerant released from the compressor 1 passes through the four-way valve 2 and is sent to the outdoor heat exchanger 3. In the outdoor heat exchanger 3, the refrigerant is cooled by heat exchange with air that has passed through the outdoor heat exchanger 3 using the fan 4. The cooled refrigerant is sent to the heat exchanger 8 through the solenoid valve SV1. The heat medium sent from the multi-air conditioner outdoor unit 100C through the first piping 91 is sent to the circulation pump 7 through the solenoid valve SV7. The refrigerant flowing out of the circulation pump 7 is sent to the heat exchanger 8 through the solenoid valve SV9. The refrigerant that has been cooled by heat exchange with the heat medium in the heat exchanger 8 is sent to the indoor unit through the solenoid valve SV10. The heat medium that has been heated by heat exchange with the refrigerant in heat exchanger 8 passes through solenoid valves SV8 and SV5 and is sent to second piping 92. The amount of refrigerant circulating in air conditioning unit 71A is made variable by driving compressor 1 with an inverter according to the amount required by the indoor unit and the amount supplied to multi-air conditioner outdoor unit 100C with insufficient capacity.

[0060] In the multi-air conditioner outdoor unit 100C set to the heat receiving mode (second mode), the refrigerant discharged from the compressor 1 and passing through the four-way valve 2 is sent to the indoor unit. The refrigerant is cooled and condensed in the indoor heat exchanger (condenser) and passes through the expansion valve, then passes through the solenoid valve SV10 and is sent to the heat exchanger 8. The heat medium sent from the multi-air conditioner outdoor unit 100A through the second piping 92 is sent to the circulation pump 7 via the solenoid valve SV6. The refrigerant flowing out of the circulation pump 7 is sent to the heat exchanger 8 via the solenoid valve SV8. The refrigerant warmed by heat exchange with the heat medium in the heat exchanger 8 is sent to the outdoor heat exchanger 3 via the solenoid valve SV1. In the outdoor heat exchanger 3, the refrigerant is warmed by heat exchange with the air that has passed through the outdoor heat exchanger 3 using the fan 4. The warmed refrigerant flows into the compressor 1 via the four-way valve 2. The heat medium cooled by heat exchange with the refrigerant in heat exchanger 8 passes through solenoid valves SV9 and SV4 and is sent to first pipe 91. The target value for the amount of refrigerant circulating in air conditioning unit 71C is the sum of the amounts required by the indoor units in air conditioning unit 71C. Any shortage is made up for by the amount supplied from multi-air conditioner outdoor unit 100A, which has surplus capacity.

[0061] In a multi-air conditioner outdoor unit 100B set to self-contained mode (third mode), the refrigerant discharged from compressor 1 and passing through four-way valve 2 is sent to the indoor unit. The refrigerant is cooled and condensed in the indoor heat exchanger (condenser) and passes through an expansion valve, then passes through solenoid valve SV10 and is sent to outdoor heat exchanger 3. In outdoor heat exchanger 3, the refrigerant is heated by fan 4 through heat exchange with air that has passed through outdoor heat exchanger 3. The heated refrigerant flows into compressor 1 through four-way valve 2. The amount of refrigerant circulating in air conditioning unit 71B is made variable by driving compressor 1 with an inverter according to the amount of air required by the indoor unit.

[0062] The amount of heat medium circulated can be determined by the amount of heat exchanged between multi-air conditioner outdoor units 100A and 100C, based on the temperature of the first pipe 91 detected by temperature sensor TH3, the temperature of the second pipe 92 detected by temperature sensor TH4, and the operating state of the circulation pump 7. The circulation amount of the heat medium is made variable by driving the circulation pumps 7 of both multi-air conditioner outdoor unit 100A and multi-air conditioner outdoor unit 100C with inverters.

[0063] Variation 1 of embodiment 3 FIG. 9 is a diagram showing the flows of the refrigerant and the heat refrigerant and the states of the solenoid valves SV1 to SV10 in the first modification of the third embodiment.

[0064] In the third embodiment, in the multi-air conditioner outdoor unit 100A set to the heat quantity supply mode (first mode), the refrigerant cooled in the outdoor heat exchanger 3 is sent to the heat exchanger 8 via the solenoid valve SV1.

[0065] In this modified example, in the outdoor heat exchanger 3, a portion of the cooled refrigerant is sent to the outdoor unit via solenoid valve SV10, and the remainder of the cooled refrigerant is sent to the heat exchanger 8 via solenoid valve SV1.

[0066] Variation 2 of Embodiment 3 FIG. 10 is a diagram showing the flows of the refrigerant and the heat refrigerant and the states of the solenoid valves SV1 to SV10 in the second modification of the third embodiment.

[0067] FIG. 11 is a flowchart showing the procedure for setting the operation modes of three outdoor units of a multi-air conditioner in the second modification of the third embodiment.

[0068] In step S200, the multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit X, which performs cooling operation all year round, to a heat supply mode (first mode).

[0069] In step S201, if there is a multi-air conditioner outdoor unit Y whose total required capacity of multiple connected indoor units exceeds its own capacity, the process proceeds to step S202, and if there is no multi-air conditioner outdoor unit Y whose total required capacity of multiple connected indoor units exceeds its own capacity, the process proceeds to step S206.

[0070] In step S202, the multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit Y to a heat quantity receiving mode (second mode).

[0071] In step S203, if the difference between the amount of condensation heat of multi-air conditioner outdoor unit X and the amount of heat supplied to multi-air conditioner outdoor unit Y is equal to or greater than a predetermined threshold TR1, the process proceeds to step S204. If the difference between the amount of condensation heat of multi-air conditioner outdoor unit X and the amount of heat supplied to multi-air conditioner outdoor unit Y is less than the predetermined threshold TR1, the process proceeds to step S205.

[0072] In step S204, the multi-air conditioner controller 21 sets the outdoor units of the multi-air conditioners whose capacities and the sum of the required capacities are equal to each other to a heat quantity receiving mode (second mode).

[0073] In step S205, the multi-air conditioner controller 21 sets the outdoor units of the multi-air conditioners whose capacities and the sum of the required capacities are equal to each other to the self-contained mode (third mode).

[0074] In step S206, if the condensation heat quantity of the multi-air conditioner outdoor unit X is equal to or greater than a predetermined threshold value TR2, the process proceeds to step S207, and if the condensation heat quantity of the multi-air conditioner outdoor unit X is less than the predetermined threshold value TR2, the process proceeds to step S208.

[0075] In step S207, the multi-air conditioner controller 21 sets the two multi-air conditioner outdoor units whose capacities and the sum of their required capacities are equal to each other to a heat quantity receiving mode (second mode).

[0076] In step S208, the multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit with the smaller low-pressure detected by the pressure sensor PS1, out of the two multi-air conditioner outdoor units whose capacity and required capacity sums are equal, to the heat receiving mode (second mode).

[0077] In step S209, the multi-air conditioner controller 21 sets the multi-air conditioner outdoor unit with the higher low-pressure detected by the pressure sensor PS1, out of the two multi-air conditioner outdoor units whose capacity and required capacity sums are equal, to self-contained mode (third mode).

[0078] This allows the temperature of the refrigerant returning to the outdoor unit of the multi-air conditioner operating in heating mode to be increased, thereby reducing frost buildup on the outdoor heat exchanger 3. As a result, the number of defrosting operations can be reduced. In addition, the low-pressure can be increased, which increases the amount of refrigerant circulating. As a result, energy savings can be achieved.

[0079] In the example of Fig. 10, the multi-air conditioner outdoor unit 100A performs cooling operation all year round, so the multi-air conditioner outdoor unit 100A is set to the first mode. Furthermore, although the following relationship holds, the multi-air conditioner outdoor units 100B and 100C are set to the second mode in step S207.

[0080] CPC=RQC CPB=RQB The operation of the multi-air conditioner outdoor unit 100A set to the heat quantity supply mode (first mode) is similar to the operation of the multi-air conditioner outdoor unit 100A in FIG.

[0081] The operation of the multi-air conditioner outdoor units 100B and 100C set to the heat quantity receiving mode (second mode) is similar to the operation of the multi-air conditioner outdoor unit 100C in FIG.

[0082] [Note] The above-described embodiment is a specific example of the following additional notes.

[0083] (Appendix 1) An air conditioning system, A plurality of air conditioning units are provided, each of the air conditioning units including a multi-air conditioner outdoor unit and a plurality of indoor units each connected to the multi-air conditioner outdoor unit, and a refrigerant flows between the multi-air conditioner outdoor unit and the plurality of indoor units; The multi-air conditioner outdoor unit includes an inter-outdoor unit heat exchange unit that exchanges heat between the refrigerant and the heat medium, The air conditioning system includes: The air conditioning system comprises first and second pipes that connect the inter-outdoor-unit heat exchange units of a plurality of the multi-air-conditioner outdoor units and through which the heat medium flows.

[0084] (Appendix 2) Excess heat is sent from the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a first mode to the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a second mode through the heat medium; the capacity of the multi-air conditioner outdoor unit set to the first mode is greater than the sum of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the first mode, An air conditioning system as described in Appendix 1, wherein the capacity of the multi-air conditioner outdoor unit set to the second mode is smaller than the sum of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the second mode.

[0085] (Appendix 3) The air conditioning system according to claim 2, wherein the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to the third mode does not exchange heat with the inter-outdoor-unit heat exchange units of the other multi-air-conditioner outdoor units through the heat medium.

[0086] (Appendix 4) The outdoor unit heat exchange unit is a first heat exchanger through which the refrigerant and the heat medium flow and exchange heat; a circulation pump for circulating the heat medium; 4. The air conditioning system according to any one of claims 1 to 3, further comprising: a plurality of switches for controlling the paths through which the refrigerant and the heat medium flow.

[0087] (Appendix 5) The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, When all of the multi-air conditioner outdoor units and all of the indoor units included in the air conditioning system are operating in cooling mode, By the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode, a portion of the refrigerant flowing out from the second heat exchanger is sent to the indoor unit and the remainder of the refrigerant is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping is sent to the circulation pump, the heat medium flowing out from the circulation pump is sent to the first heat exchanger, the refrigerant flowing out from the first heat exchanger is sent to the compressor via the four-way valve, and the heat medium flowing out from the first heat exchanger is sent to the second piping, The air conditioning system according to any one of appendixes 1 to 4, wherein the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the second mode cause the refrigerant flowing out of the second heat exchanger to be sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the first mode through the second piping to be sent to the circulation pump, the heat medium flowing out of the circulation pump to be sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger to be sent to the indoor unit, and the heat medium flowing out of the first heat exchanger to be sent to the first piping.

[0088] (Appendix 6) The air conditioning system of Appendix 5, wherein the refrigerant flowing out of the second heat exchanger is sent to the indoor unit by the plurality of switches of the inter-outdoor unit heat exchange unit of the multi-air conditioner outdoor unit set to the third mode, and the heat medium sent from the multi-air conditioner outdoor unit set to the second mode through the first piping is not sent to the circulation pump.

[0089] (Appendix 7) The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, When all of the multi-air conditioner outdoor units and all of the indoor units included in the air conditioning system are in heating operation, By the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode, the refrigerant from the indoor unit flows into the second heat exchanger, a portion of the refrigerant that flows out of the compressor and passes through the four-way valve is sent to the indoor unit, the remainder of the refrigerant is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping is sent to the circulation pump, the heat medium flowing out of the circulation pump is sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger is sent to the second heat exchanger, and the heat medium flowing out of the first heat exchanger is sent to the second piping, The air conditioning system according to any one of appendixes 1 to 4, wherein the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the second mode cause the refrigerant flowing out of the compressor and passing through the four-way valve to be sent to the indoor unit, the refrigerant from the indoor unit to be sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping to the circulation pump, the heat medium flowing out of the circulation pump to the first heat exchanger, the refrigerant flowing out of the first heat exchanger to flow into the second heat exchanger, and the heat medium flowing out of the first heat exchanger to be sent to the first piping.

[0090] (Appendix 8) The air conditioning system of claim 7, wherein the refrigerant from the indoor unit is sent to the second heat exchanger by the plurality of switches of the inter-outdoor unit heat exchange unit of the multi-air conditioner outdoor unit set to the third mode, and the heat medium sent from the multi-air conditioner outdoor unit set to the second mode through the first piping is not sent to the circulation pump.

[0091] (Appendix 9) Excess heat is sent from the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a first mode to the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a second mode through the heat medium; 2. The air conditioning system according to claim 1, wherein the outdoor unit of the multi-air conditioner set to the first mode performs cooling operation year-round, and the other outdoor units of the multi-air conditioner perform heating operation.

[0092] (Appendix 10) The outdoor unit heat exchange unit is a first heat exchanger through which the refrigerant and the heat medium flow and exchange heat; a circulation pump for circulating the heat medium; and a plurality of switches for controlling the flow paths of the refrigerant and the heat medium.

[0093] (Appendix 11) The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, The air conditioning system of claim 10, wherein the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode cause the refrigerant flowing out of the second heat exchanger to be sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping to be sent to the circulation pump, the heat medium flowing out of the circulation pump to be sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger to be sent to the indoor unit, and the heat medium flowing out of the first heat exchanger to be sent to the second piping.

[0094] (Appendix 12) An air conditioning system as described in any one of Appendices 9 to 11, wherein the capacity of the multi-air conditioner outdoor unit set to the second mode is smaller than the sum of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the second mode.

[0095] (Appendix 13) An air conditioning system as described in any one of Appendices 9 to 11, wherein the capacity of the multi-air conditioner outdoor unit set to the second mode is equal to the requirements of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the second mode.

[0096] (Appendix 14) the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the third mode among the plurality of multi-air-conditioner outdoor units does not exchange heat quantity with the inter-outdoor-unit heat exchange units of the other multi-air-conditioner outdoor units through the heat medium, the capacity of the multi-air conditioner outdoor unit set to the second mode is equal to the demands of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the second mode, the capacity of the multi-air conditioner outdoor unit set to the third mode is equal to the demands of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the third mode, An air conditioning system as described in any one of Appendices 9 to 11, wherein the pressure in the piping between the second heat exchanger and the inter-outdoor unit heat exchange unit in the multi-air conditioner outdoor unit set to the second mode is lower than the pressure in the piping between the second heat exchanger and the inter-outdoor unit heat exchange unit in the multi-air conditioner outdoor unit set to the third mode.

[0097] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0098] 1 compressor, 2 four-way valve, 3 outdoor heat exchanger, 4 fan, 5 controller, 6 fan motor, 7 circulation pump, 8 heat exchanger, 10 expansion valve, 20 heat exchange unit between outdoor units, 21 multi-air conditioner controller, 71A, 71B, 71C air conditioning unit, 91 first piping, 92 second piping, 100A, 100B, 100C, 200A, 200B, 200C, 300A, 300B, 300C multi-air conditioner outdoor units, IU1 to IU18 indoor units, P1 first port, P2 second port, P3 third port, SV1 to SV10 solenoid valves, TH1, TH3, TH4 temperature sensors, PS1 pressure sensor.

Claims

1. An air conditioning system, comprising: A plurality of air conditioning units are provided, each of the air conditioning units including a multi-air conditioner outdoor unit and a plurality of indoor units each connected to the multi-air conditioner outdoor unit, and a refrigerant flows between the multi-air conditioner outdoor unit and the plurality of indoor units; The multi-air conditioner outdoor unit includes an inter-outdoor unit heat exchange unit that exchanges heat between the refrigerant and the heat medium, The air conditioning system includes: a first pipe and a second pipe that connect the inter-outdoor-unit heat exchange units of a plurality of the multi-air-conditioner outdoor units and through which the heat medium flows; an amount of excess heat is sent from the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a first mode to the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a second mode through the heat medium; the capacity of the multi-air conditioner outdoor unit set to the first mode is greater than the sum of the required capacities of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the first mode, the capacity of the multi-air conditioner outdoor unit set to the second mode is smaller than the sum of the required capacities of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the second mode, the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to the third mode does not exchange heat with the inter-outdoor-unit heat exchange units of the other multi-air-conditioner outdoor units through the heat medium, The outdoor unit heat exchange unit is a first heat exchanger through which the refrigerant and the heat medium flow and exchange heat; a circulation pump for circulating the heat medium; a plurality of switches for controlling the paths through which the refrigerant and the heat medium flow, The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, When all of the multi-air conditioner outdoor units and all of the indoor units included in the air conditioning system are operating in cooling mode, By the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode, a portion of the refrigerant flowing out from the second heat exchanger is sent to the indoor unit and the remainder of the refrigerant is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping is sent to the circulation pump, the heat medium flowing out from the circulation pump is sent to the first heat exchanger, the refrigerant flowing out from the first heat exchanger is sent to the compressor via the four-way valve, and the heat medium flowing out from the first heat exchanger is sent to the second piping, an air conditioning system in which, by the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the second mode, the refrigerant flowing out of the second heat exchanger is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the first mode through the second piping is sent to the circulation pump, the heat medium flowing out of the circulation pump is sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger is sent to the indoor unit, and the heat medium flowing out of the first heat exchanger is sent to the first piping.

2. 2. The air conditioning system of claim 1, wherein the plurality of switches of the inter-outdoor unit heat exchange unit of the multi-air conditioner outdoor unit set to the third mode cause the refrigerant flowing out of the second heat exchanger to be sent to the indoor unit, and the heat medium sent from the multi-air conditioner outdoor unit set to the second mode through the first piping is not sent to the circulation pump.

3. An air conditioning system, A plurality of air conditioning units are provided, each of the air conditioning units including a multi-air conditioner outdoor unit and a plurality of indoor units each connected to the multi-air conditioner outdoor unit, and a refrigerant flows between the multi-air conditioner outdoor unit and the plurality of indoor units; The multi-air conditioner outdoor unit includes an inter-outdoor unit heat exchange unit that exchanges heat between the refrigerant and the heat medium, The air conditioning system includes: a first pipe and a second pipe that connect the inter-outdoor-unit heat exchange units of a plurality of the multi-air-conditioner outdoor units and through which the heat medium flows; an amount of excess heat is sent from the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a first mode to the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a second mode through the heat medium; the capacity of the multi-air conditioner outdoor unit set to the first mode is greater than the sum of the required capacities of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the first mode, the capacity of the multi-air conditioner outdoor unit set to the second mode is smaller than the sum of the required capacities of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the second mode, the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to the third mode does not exchange heat with the inter-outdoor-unit heat exchange units of the other multi-air-conditioner outdoor units through the heat medium, The outdoor unit heat exchange unit is a first heat exchanger through which the refrigerant and the heat medium flow and exchange heat; a circulation pump for circulating the heat medium; a plurality of switches for controlling the paths through which the refrigerant and the heat medium flow, The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, When all of the multi-air conditioner outdoor units and all of the indoor units included in the air conditioning system are in heating operation, By the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode, the refrigerant from the indoor unit flows into the second heat exchanger, a portion of the refrigerant that flows out of the compressor and passes through the four-way valve is sent to the indoor unit, and the remainder of the refrigerant is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping is sent to the circulation pump, the heat medium flowing out of the circulation pump is sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger is sent to the second heat exchanger, and the heat medium flowing out of the first heat exchanger is sent to the second piping, an air conditioning system in which, by the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the second mode, the refrigerant flowing out of the compressor and passing through the four-way valve is sent to the indoor unit, the refrigerant from the indoor unit is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the first mode through the first piping is sent to the circulation pump, the heat medium flowing out of the circulation pump is sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger flows into the second heat exchanger, and the heat medium flowing out of the first heat exchanger is sent to the first piping.

4. 4. The air conditioning system of claim 3, wherein the plurality of switches of the inter-outdoor unit heat exchange unit of the multi-air conditioner outdoor unit set to the third mode cause the refrigerant from the indoor unit to be sent to the second heat exchanger, and the heat medium sent from the multi-air conditioner outdoor unit set to the second mode through the first piping is not sent to the circulation pump.

5. An air conditioning system, A plurality of air conditioning units are provided, each of the air conditioning units including a multi-air conditioner outdoor unit and a plurality of indoor units each connected to the multi-air conditioner outdoor unit, and a refrigerant flows between the multi-air conditioner outdoor unit and the plurality of indoor units; The multi-air conditioner outdoor unit includes an inter-outdoor unit heat exchange unit that exchanges heat between the refrigerant and the heat medium, The air conditioning system includes: a first pipe and a second pipe that connect the inter-outdoor-unit heat exchange units of a plurality of the multi-air-conditioner outdoor units and through which the heat medium flows; an amount of excess heat is sent from the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a first mode to the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to a second mode through the heat medium; The outdoor unit of the multi-air conditioner set to the first mode performs cooling operation throughout the year, and the other outdoor units of the multi-air conditioner perform heating operation, The outdoor unit heat exchange unit is a first heat exchanger through which the refrigerant and the heat medium flow and exchange heat; a circulation pump for circulating the heat medium; a plurality of switches for controlling the flow paths of the refrigerant and the heat medium; The outdoor unit of the multi-air conditioner includes a compressor, a four-way valve, and a second heat exchanger that exchanges heat with air, an air conditioning system in which, by the plurality of switches of the inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the first mode, the refrigerant flowing out of the second heat exchanger is sent to the first heat exchanger, the heat medium sent from the multi-air-conditioner outdoor unit set to the second mode through the first piping is sent to the circulation pump, the heat medium flowing out of the circulation pump is sent to the first heat exchanger, the refrigerant flowing out of the first heat exchanger is sent to the indoor unit, and the heat medium flowing out of the first heat exchanger is sent to the second piping.

6. The air conditioning system according to claim 5, wherein the capacity of the multi-air conditioner outdoor unit set to the second mode is smaller than the sum of the required capacities of the multiple indoor units connected to the multi-air conditioner outdoor unit set to the second mode.

7. The inter-outdoor-unit heat exchange unit of the multi-air-conditioner outdoor unit set to the third mode among the plurality of multi-air-conditioner outdoor units does not exchange heat with the inter-outdoor-unit heat exchange units of other multi-air-conditioner outdoor units through the heat medium, 6. The air conditioning system according to claim 5, wherein the capacity of the multi-air conditioner outdoor unit set to the third mode is equal to the demands of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the third mode.

8. the inter-outdoor-unit heat exchange unit of one of the plurality of multi-air-conditioner outdoor units that is set to the third mode does not exchange heat with the inter-outdoor-unit heat exchange units of the other multi-air-conditioner outdoor units through the heat medium, the capacity of the multi-air conditioner outdoor unit set to the second mode is equal to the demands of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the second mode, the capacity of the multi-air conditioner outdoor unit set to the third mode is equal to the demands of the plurality of indoor units connected to the multi-air conditioner outdoor unit set to the third mode, 6. The air conditioning system of claim 5, wherein the pressure in the piping between the second heat exchanger and the inter-outdoor-unit heat exchange unit in the multi-air-conditioner outdoor unit set to the second mode is lower than the pressure in the piping between the second heat exchanger and the inter-outdoor-unit heat exchange unit in the multi-air-conditioner outdoor unit set to the third mode.

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