A multi-split air conditioning system

Abstract

This disclosure provides an embodiment of a multi-split air conditioning system, relating to the field of air conditioning technology, for achieving continuous heating in defrost mode. The multi-split air conditioning system includes at least one outdoor unit and multiple indoor units connected in parallel. The outdoor unit includes a compressor, a first commutator assembly, a second commutator assembly, an outdoor heat exchanger, a first throttling valve, and a second throttling valve. The first and third valve ports of the first commutator assembly are connected to the compressor's exhaust port and intake port, respectively, and the second valve port is commutated to one of the first and third valve ports. The first and third valve ports of the second commutator assembly are connected to the compressor's exhaust port and intake port, respectively, and the second port is commutated to one of the first and third ports. The outdoor heat exchanger is connected to the second port. The first throttling valve connects the outdoor heat exchanger to the compressor's intake port. The second throttling valve connects the outdoor heat exchanger to the indoor units. This disclosure is used for temperature regulation.

Description

Technical Field

[0001] This disclosure relates to the field of air conditioning technology, and in particular to a multi-split air conditioning system. Background Technology

[0002] With the development of the economy and society, air conditioning can bring people a better experience, so it is increasingly widely used in various places such as entertainment, home and work.

[0003] After running in heating mode for a period of time, existing multi-split air conditioning systems are prone to frost buildup on the outdoor heat exchanger, leading to a decrease in the system's heating capacity. Current defrosting technologies generally use a reverse circulation method to defrost the outdoor unit, switching the refrigerant circulation path to cooling mode. During defrosting, the refrigerant in the connecting pipes between the indoor and outdoor units and in the indoor heat exchanger becomes cold. This can cause the indoor unit to be unable to heat continuously, reducing the overall heating capacity of the multi-split air conditioning system. Furthermore, when the outdoor unit resumes heating after defrosting, the indoor heat exchanger and the aforementioned connecting pipes need to be reheated, resulting in a slow increase in the indoor unit's outlet air temperature after defrosting, leading to poor thermal comfort for users. Summary of the Invention

[0004] The embodiments of this disclosure provide a multi-split air conditioning system for achieving continuous heating in a multi-split air conditioning system.

[0005] To achieve the above objectives, the embodiments of this disclosure adopt the following technical solutions:

[0006] The embodiments of this disclosure provide a multi-split air conditioning system, the multi-split air conditioning system comprising: at least one outdoor unit and multiple indoor units connected in parallel; in the case where the multi-split air conditioning system includes multiple outdoor units, the multiple outdoor units are connected in parallel; wherein, the outdoor unit includes: a compressor, a first commutation assembly, a second commutation assembly, an outdoor heat exchanger, a first throttle valve and a second throttle valve. The compressor has an intake port and an exhaust port; a first reversing assembly has at least a first valve port, a second valve port, and a third valve port, the first valve port being connected to the exhaust port, the third valve port being connected to the intake port, and the second valve port being reversibly connected to one of the first and third valve ports; the second valve port is connected to the indoor unit; a second reversing assembly has at least a first port, a second port, and a third port, the first port being connected to the exhaust port, the third port being connected to the intake port, and the second port being reversibly connected to one of the first and third ports; a first end of the outdoor heat exchanger is connected to the second port; a first end of the first throttling valve is connected to the second end of the outdoor heat exchanger, and the second end of the first throttling valve is connected to the intake port; a first end of the second throttling valve is connected to the second end of the outdoor heat exchanger, and the second end of the second throttling valve is connected to the indoor unit.

[0007] The multi-split air conditioning system provided in some embodiments of this disclosure includes at least one outdoor unit and multiple indoor units connected in parallel. The outdoor unit includes a first commutator, a second commutator, an outdoor heat exchanger, a first throttle valve, and a second throttle valve. The second valve port of the first commutator is commutatively connected to one of the first and third valve ports. The second port of the second commutator is commutatively connected to one of the first and third ports. The two ends of the first throttle valve are respectively connected to the second end of the outdoor heat exchanger and the air intake port. The two ends of the second throttle valve are respectively connected to the outdoor heat exchanger and the indoor unit. Thus, the multi-split air conditioning system includes... When an outdoor unit is in heating mode and its outdoor heat exchanger meets the defrosting conditions, a portion of the high-temperature refrigerant discharged from the compressor can enter the outdoor heat exchanger through the second reversing assembly to defrost it. Meanwhile, another portion of the high-temperature refrigerant discharged from the compressor can enter the indoor unit's piping through the second valve port of the first reversing assembly. This ensures that the piping inside the indoor unit maintains a high temperature while the outdoor unit is defrosting, allowing the indoor unit to heat up quickly when the outdoor unit finishes defrosting and enters heating mode. This results in a rapid increase in the outlet air temperature during heating, significantly improving the heating comfort of the multi-split air conditioning system. In a multi-split air conditioning system, there are multiple outdoor units in heating mode. When one outdoor unit meets the defrosting conditions (designated as the first outdoor unit), a portion of the high-temperature refrigerant discharged from the compressor of the first outdoor unit enters the outdoor heat exchanger through the second reversing assembly to defrost the outdoor heat exchanger of the first outdoor unit. At the same time, other outdoor units connected in parallel and in heating mode (such as the second outdoor unit) discharge high-temperature refrigerant through the first and second reversing assemblies to enter the outdoor heat exchanger of the first outdoor unit, thereby assisting in the defrosting of the outdoor heat exchanger of the first outdoor unit. This improves the defrosting efficiency of the multi-split air conditioning system. Meanwhile, the second outdoor unit and the corresponding indoor unit maintain the heating mode to ensure that the indoor units output hot air, ensuring uninterrupted and continuous heating of the multi-split air conditioning system. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not a limitation on the actual size of the products involved in the embodiments of this disclosure.

[0009] Figure 1 This is a structural diagram of a multi-split air conditioning system according to some embodiments of the present disclosure;

[0010] Figure 2This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0011] Figure 3 This is a structural diagram of an outdoor unit according to some embodiments of the present disclosure;

[0012] Figure 4 This is a structural diagram of another outdoor unit in some embodiments of this disclosure;

[0013] Figure 5 This is a structural diagram of a compressor according to some embodiments of the present disclosure;

[0014] Figure 6 This is a structural diagram showing one conduction state of the first commutation component in some embodiments of this disclosure;

[0015] Figure 7 This is a structural diagram showing another conduction configuration of the first commutation component in some embodiments of this disclosure;

[0016] Figure 8 This is a structural diagram of another outdoor unit in some embodiments of this disclosure;

[0017] Figure 9 This is a structural diagram of another outdoor unit in some embodiments of this disclosure;

[0018] Figure 10 This is a structural diagram of two outdoor units connected in parallel in some embodiments of this disclosure;

[0019] Figure 11 This is a structural diagram of another two outdoor units connected in parallel, as shown in some embodiments of this disclosure;

[0020] Figure 12 This is a structural diagram of an oil separator according to some embodiments of the present disclosure;

[0021] Figure 13 This is a structural diagram of a gas-liquid separator according to some embodiments of this disclosure;

[0022] Figure 14 This is a structural diagram of an indoor unit according to some embodiments of the present disclosure;

[0023] Figure 15 This is a structural diagram of indoor units connected in parallel according to some embodiments of this disclosure;

[0024] Figure 16 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0025] Figure 17 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0026] Figure 18 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0027] Figure 19 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0028] Figure 20 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure;

[0029] Figure 21 This is a structural diagram of another multi-split air conditioning system in some embodiments of this disclosure. Detailed Implementation

[0030] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0031] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary," or "for example" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "connected" should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; they can refer to mechanical connection or electrical connection; they can refer to direct connection or indirect connection through an intermediate medium; and they can refer to the connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0034] The use of “configured as” in this article implies an open and inclusive language that does not exclude the applicability to or configuration of devices to perform additional tasks or steps.

[0035] Some embodiments of this disclosure provide a multi-split air conditioning system 1000, such as Figure 1 and Figure 2 As shown, the multi-split air conditioning system 1000 can achieve different operating modes, such as cooling mode, heating mode, and defrosting mode.

[0036] In some examples, such as Figure 1 and Figure 2 The aforementioned multi-split air conditioning system 1000 includes at least one outdoor unit 100 and multiple indoor units 200 connected in parallel.

[0037] For example, multiple indoor units 200 are connected to each other. In the case of a multi-split air conditioning system 1000 that includes multiple outdoor units, the multiple outdoor units 100 are connected to each other.

[0038] For example, the aforementioned multiple indoor units 200 can be distributed within the same room.

[0039] In some examples, such as Figure 3 As shown, the outdoor unit 100 includes: a compressor 11, a first reversing assembly 12, a second reversing assembly 13, an outdoor heat exchanger 14, a first throttle valve 16, and a second throttle valve 25.

[0040] For example, such as Figure 5 As shown, the compressor 11 has an intake port 111 and an exhaust port 112.

[0041] Specifically, the suction port 111 of the compressor 11 is used to draw in air. The refrigerant enters the compression chamber of the compressor 11 through the suction port 111 and is compressed by the compressor 11, forming a high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas is then discharged from the compressor 11 through the discharge port 112 and enters the multi-split air conditioning system 1000 to circulate the refrigerant, thereby realizing different working modes of the multi-split air conditioning system 1000.

[0042] For example, the number of compressors 11 can be one or more, for example, one or more compressors 11 connected in parallel to form a compressor unit.

[0043] For example, compressor 11 can be a fixed-speed compressor or a variable-speed compressor.

[0044] The first reversing assembly 12 and the second reversing assembly 13 are connected in parallel between the intake port and the exhaust port of the compressor 11.

[0045] In some examples, the first reversing assembly 12 and the second reversing assembly 13 may both be three-way valves, or they may both be four-way valves.

[0046] For example, the first reversing assembly 12 has at least a first valve port 121, a second valve port 122 and a third valve port 123. The first valve port 121 is connected to the exhaust port, the third valve port 123 is connected to the intake port, and the second valve port 122 is connected to one of the first valve port 121 and the third valve port 123 for reversing.

[0047] For example, the first commutation assembly 12 may also have a fourth valve port 124.

[0048] like Figure 6 As shown, the second valve port 122 of the first reversing assembly 12 can be connected to the first valve port 121.

[0049] like Figure 7 As shown, the second valve port 122 of the first reversing assembly 12 can be connected to the third valve port 123.

[0050] For example, the connection between the first valve port 121 and the exhaust port and the connection between the third valve port 123 and the intake port can be either direct or indirect.

[0051] For example, the conduction status of the first valve port 121, the second valve port 122, the third valve port 123, and the fourth valve port 124 in the first commutation assembly 12 can be controlled according to actual needs. When not powered on, the first valve port 121 and the second valve port 122 of the first commutation assembly 12 are connected, and the third valve port 123 and the fourth valve port 124 are connected. When powered on, the first valve port 121 and the fourth valve port 124 of the first commutation assembly 12 are connected, and the third valve port 123 and the second valve port 122 are connected.

[0052] For example, the second commutation component 13 has at least a first port 131, a second port 132 and a third port 133, the first port 131 being connected to an exhaust port, the third port 133 being connected to an intake port, and the second port 132 being connected to one of the first port 131 and the third port 133 for commutation.

[0053] For example, the connection between the first port 131 and the exhaust port and the connection between the third port 133 and the intake port can be either direct or indirect.

[0054] For example, the outdoor heat exchanger 14 can be a copper tube finned heat exchanger or an all-aluminum microchannel heat exchanger.

[0055] In some examples, the first end of the outdoor heat exchanger 14 is connected to the second port 132 of the second commutation assembly 13.

[0056] Therefore, when the outdoor heat exchanger 14 needs to enter the defrost mode, and the first port 131 and the second port 132 of the second reversing assembly 13 are connected, the high-temperature and high-pressure refrigerant discharged from the compressor 11 can enter the outdoor heat exchanger 14 through the first port 131 and the second port 132 of the second reversing assembly 13 to defrost the outdoor heat exchanger 14. This allows the indoor unit 200 connected to the outdoor unit 100 to maintain a higher temperature after the outdoor unit 100 switches from the heating mode to the defrost mode, thereby improving the heating efficiency of the multi-split air conditioning system 1000.

[0057] For example, such as Figure 3 , Figure 16 and Figure 17 As shown, the first end of the first throttle valve 16 is connected to the second end of the outdoor heat exchanger 14, and the second end of the first throttle valve 16 is connected to the air intake 111. The first end of the second throttle valve 25 is connected to the second end of the outdoor heat exchanger 14, and the second end of the second throttle valve 25 is connected to the indoor unit 200.

[0058] The first throttle valve 16 controls the opening and closing of the passage between the outdoor heat exchanger 14 and the suction port of the compressor 11. The first throttle valve 16 also functions to throttle and reduce the pressure of the refrigerant flowing through it. In other words, the opening degree of the first throttle valve 16 is adjustable. The first throttle valve 16 can have a fully open state (100% opening), a fully closed state (0% opening), and a throttling state (opening degree between 0 and 100%). In the fully closed state, there is no connection between the outdoor heat exchanger and the suction port at both ends of the first throttle valve 16. In the fully open and throttling states, there is connection between the outdoor heat exchanger 14 and the suction port at both ends of the first throttle valve 16, and in the throttling state, the first throttle valve 16 can throttle and reduce the pressure of the refrigerant flowing through it.

[0059] Similarly, the function of the second throttle valve 25 is similar to that of the first throttle valve 16 described above, and will not be repeated here.

[0060] For example, the first throttle valve 16 and the second throttle valve 25 may be of the same type or different types.

[0061] For example, the first throttle valve 16 can be an electronic expansion valve or an electromagnetic expansion valve.

[0062] The multi-split air conditioning system provided in some embodiments of this disclosure includes at least one outdoor unit and multiple indoor units connected in parallel. The outdoor unit 100 includes a first commutator 12, a second commutator 13, an outdoor heat exchanger 14, a first throttle valve 16, and a second throttle valve 25. The second valve port 122 of the first commutator 12 can be commutated to one of the first valve port 121 and the third valve port 123. The second port 132 of the second commutator 13 can be commutated to one of the first port 131 and the third port 133. The two ends of the first throttle valve 16 are respectively connected to the second end of the outdoor heat exchanger 14 and the air intake. The two ends of the second throttle valve 25 are respectively connected to the outdoor heat exchanger and the indoor unit, thereby encompassing the multi-split air conditioning system. The system includes an outdoor unit 100. When the outdoor heat exchanger 14 in the outdoor unit 100, which is in heating mode, meets the defrosting conditions, a portion of the high-temperature refrigerant discharged by the compressor 11 can enter the outdoor heat exchanger through the second reversing assembly 13 to defrost the outdoor heat exchanger 14. Another portion of the high-temperature refrigerant discharged by the compressor 11 can enter the pipeline of the indoor unit 200 through the second valve port 122 of the first reversing assembly 12. This ensures that the pipeline in the indoor unit 200 is kept at a high temperature when the outdoor unit 100 is defrosting. This ensures that when the outdoor unit 100 finishes defrosting and enters the heating mode, the indoor unit 200 can heat up quickly, resulting in a rapid increase in the outlet air temperature during heating, thereby significantly improving the heating comfort of the multi-split air conditioning system 1000. In a multi-split air conditioning system 1000, there are multiple outdoor units 100 in heating mode. When one outdoor unit 100 meets the defrosting conditions (the outdoor unit that meets the defrosting conditions is designated as the first outdoor unit 100a), a portion of the high-temperature refrigerant discharged by the compressor 11 of the first outdoor unit enters the outdoor heat exchanger 14 through the second reversing assembly 13 to defrost the outdoor heat exchanger 14 of the first outdoor unit. At the same time, other outdoor units connected in parallel and in heating mode (such as the second outdoor unit 100b) discharge high-temperature refrigerant through the first reversing assembly 12 and the second reversing assembly 13 to enter the outdoor heat exchanger 14 of the first outdoor unit 100a, thereby assisting the outdoor heat exchanger of the first outdoor unit 100a in defrosting. This improves the defrosting efficiency of the multi-split air conditioning system. Meanwhile, the second outdoor unit 100b and the corresponding indoor unit 200 maintain the heating mode to ensure that the indoor unit 200 outputs hot air, ensuring uninterrupted and continuous heating of the multi-split air conditioning system.

[0063] In some embodiments, such as Figure 4 , Figure 11 and Figure 18 As shown, in the case where the above-mentioned multi-split air conditioning system includes multiple outdoor units 100, the above-mentioned multi-split air conditioning system also includes: an auxiliary heat exchanger 15 and a third throttle valve 17.

[0064] In some examples, such as Figure 4 and Figure 18 As shown, the first end A of the auxiliary heat exchanger 15 is connected to the second valve port 122, the second end B of the auxiliary heat exchanger 15 is connected to the first end of the third throttle valve 17, the third end C of the auxiliary heat exchanger 15 is connected to the second end of the outdoor heat exchanger 14 through the first throttle valve 16, and the fourth end D of the auxiliary heat exchanger 15 is connected to the air intake. The first end A and the second end B of the auxiliary heat exchanger 15 are connected internally, as are the third end C and the fourth end D. The second end of the third throttle valve 17 is connected to the indoor unit 200.

[0065] For example, the auxiliary heat exchanger 15 described above can be a plate heat exchanger.

[0066] For example, the temperature of the refrigerant flowing through the first end A and the second end B of the auxiliary heat exchanger 15 is different from the temperature of the refrigerant flowing through the third end C and the fourth end D of the auxiliary heat exchanger 15, so that heat exchange can be completed within the auxiliary heat exchanger 15.

[0067] Therefore, the latent heat of the high-temperature refrigerant provided by the outdoor unit 100 in heating mode can be used to exchange heat with the refrigerant entering the auxiliary heat exchanger 15 from the outdoor heat exchanger 14 in the outdoor unit 100 in defrost mode, thereby reducing defrost costs and avoiding the need for additional heating structures, which would otherwise result in higher defrost costs.

[0068] Similarly, the function of the third throttle valve 17 is similar to that of the first throttle valve 16 described above, and will not be repeated here.

[0069] For example, the third throttle valve 17 can be an electronic expansion valve or an electromagnetic expansion valve.

[0070] For example, the second valve port 122 of the first outdoor unit 100a is connected to the second valve port 122 of the second outdoor unit 100b, and the second end of the second throttle valve 25 of the first outdoor unit 100a is connected to the second end of the second throttle valve 25 of the second outdoor unit 100b, so as to realize the parallel connection of the first outdoor unit 100a and the second outdoor unit 100b. It can be understood that when a multi-split air conditioning system includes multiple outdoor units, the parallel connection method of the multiple outdoor units is the same as the parallel connection method of the first outdoor unit and the second outdoor unit described above, and will not be repeated here.

[0071] For ease of description, the following example uses a multi-split air conditioning system that includes two outdoor units 100, namely the first outdoor unit 100a and the second outdoor unit 100b, with the first outdoor unit 100a meeting the defrosting conditions and ready to enter defrosting mode, and the second outdoor unit 100b in heating mode.

[0072] refer to Figure 18When the outdoor heat exchanger 14 of the first outdoor unit 100a needs to enter defrost mode, and the first port 131 and the second port 132 of the second reversing assembly 13 are connected, the high-temperature and high-pressure refrigerant discharged from the compressor 11 can enter the outdoor heat exchanger 14 through the first port 131 and the second port 132 of the second reversing assembly 13 to defrost the outdoor heat exchanger 14. After defrosting the outdoor heat exchanger 14, the refrigerant enters the auxiliary heat exchanger 15 through the first throttle valve 16 to absorb heat, and then enters the compressor 11 to complete the defrosting of the outdoor heat exchanger 14. Meanwhile, a portion of the high-temperature refrigerant discharged from the compressor of the second outdoor unit 100b, which is connected in parallel with the first outdoor unit 100a, enters the auxiliary heat exchanger 15 through the second valve port 122 of the first reversing assembly 12 of the second outdoor unit 100b and the second valve port 122 of the first outdoor unit 100a, thereby exchanging heat with the refrigerant discharged from the outdoor heat exchanger 14 of the first outdoor unit 100a, thus assisting the first outdoor unit 100a in defrosting. Another portion of the refrigerant discharged from the compressor 11 of the second outdoor unit 100b enters the indoor unit 200 via the first reversing assembly 12, allowing the indoor heat exchanger 26 to exchange heat with the room air. This causes the indoor unit to blow out hot air, ensuring that the multi-split air conditioning system can still produce hot air in the indoor units even when some outdoor units are defrosting, providing continuous heating and improving user comfort. Furthermore, when the first outdoor unit 100a finishes defrosting and switches to heating mode, the indoor unit's piping maintains a higher temperature, ensuring that the indoor unit always produces hot air and avoiding the experience of low air temperature at the initial switching stage.

[0073] For ease of description, the outdoor unit in heating mode in this article refers to the outdoor unit that operates in conjunction with the corresponding indoor unit to achieve indoor heating when the entire multi-split air conditioning system is in heating mode. Similarly, the indoor unit in heating mode refers to the indoor unit that operates in conjunction with the corresponding outdoor unit to achieve indoor heating when the entire multi-split air conditioning system is in heating mode.

[0074] In some embodiments, such as Figures 16-18 As shown, the multi-split air conditioning system 1000 also includes multiple connecting pipes 30. The multiple connecting pipes connect multiple outdoor units 100 and multiple indoor units 200.

[0075] Of course, the connection pipe 30 can also be used to connect multiple outdoor units 100, or to connect multiple indoor units 200, or to connect indoor units 200 with outdoor units 100.

[0076] For example, the connection pipe 30 is used to transfer refrigerant between each outdoor unit 100 or between each indoor unit 200 or between an indoor unit 200 and an outdoor unit 100.

[0077] For example, the connecting pipe 30 can also connect the passage between the outdoor heat exchanger 14 and the first commutation assembly 12, or the passage between the outdoor heat exchanger 14 and the second commutation assembly 13.

[0078] In some examples, such as Figures 8-11 As shown, the outdoor unit 100 also includes: a first shut-off valve 18, a second shut-off valve 19, and an outdoor fan 20 located on one side of the outdoor heat exchanger 14.

[0079] For example, the first end of the first shut-off valve 18 is connected to the second valve port 122 of the first reversing assembly 12; the second end of the first shut-off valve 18 is connected to the indoor unit 200. In the case where the multi-split air conditioning system 1000 includes multiple outdoor units 100 connected in parallel, the second end of the first shut-off valve 18 of the first outdoor unit 100a is also connected to the second end of the first shut-off valve 18 of the second outdoor unit 100b.

[0080] The first end of the second shut-off valve 19 is connected to the second end of the second throttle valve 25; the second end of the second shut-off valve 19 is connected to the indoor unit 200. In the case of a multi-split air conditioning system including multiple outdoor units 100 connected in parallel, the second end of the second shut-off valve 19 of the first outdoor unit 100a is also connected to the second end of the second shut-off valve 19 of the second outdoor unit 100b.

[0081] It is understandable that when the multi-split air conditioning system is in operation, whether in heating mode, cooling mode or defrosting mode, the first shut-off valve 18 and the second shut-off valve 19 are both open, so that the refrigerant of the parallel first outdoor unit 100a and the second outdoor unit 100b can flow to each other, and the refrigerant between the outdoor unit 100 and the indoor unit 200 can flow to each other.

[0082] For example, the outdoor fan 20 can be an axial fan, which can make outdoor air enter the outdoor heat exchanger 14 quickly when the outdoor fan 20 rotates, thereby improving the heat exchange efficiency of the outdoor heat exchanger 14.

[0083] In some embodiments, such as Figures 8-11 As shown, the outdoor unit 100 also includes: a one-way valve 21, an oil separator 22, a capillary tube 23, a gas-liquid separator 24, and a third throttle valve 17.

[0084] Of course, such as Figures 8-11 As shown, the outdoor unit 100 may also include a one-way valve 21 and a capillary tube 23.

[0085] Figure 12 This is a structural diagram of an oil separator 22. Figure 13 This is a structural diagram of a gas-liquid separator 24.

[0086] For example, refer to Figures 8-13The first end of the one-way valve 21 is connected to the exhaust port of the compressor 11; the first end 221 of the oil separator 22 is connected to the second end of the one-way valve 21, and the second end 222 of the oil separator 22 is connected to the first valve port 121 of the first reversing assembly 12 and the first valve port 121 of the second reversing assembly 13, so that the exhaust port of the compressor is connected to the first valve port of the first reversing assembly and the first valve port of the second reversing assembly; the first end of the capillary tube 23 is connected to the third end 223 of the oil separator 22.

[0087] The first end 241 of the gas-liquid separator 24 is connected to the suction port of the compressor 11. The second end 242 of the gas-liquid separator 24 is connected to the second end of the capillary tube 23, the third valve port 123 of the first reversing assembly 12, and the third port 133 of the second reversing assembly 13. The second end 242 of the gas-liquid separator 24 is connected to the suction port of the compressor 11, so that the suction port of the compressor 11 is connected to the third valve port 123 of the first reversing assembly 12 and the third port 133 of the second reversing assembly 13. The first end of the third throttle valve 17 is connected to the second end of the outdoor heat exchanger 14, and the second end of the third throttle valve 17 is connected to the second shut-off valve 19.

[0088] For example, the one-way valve 21 is directed from the exhaust port of the compressor 11 towards the oil separator 22. This prevents the refrigerant discharged from the compressor 11 from flowing back, thus avoiding affecting the cooling or heating efficiency of the multi-split air conditioning system 1000.

[0089] For example, the first shut-off valve 18 can control the flow of refrigerant in the connecting pipe 30.

[0090] The oil separator 22 and capillary tube 23 are provided so that the oil in the compressor 11 can be separated in the oil separator 22 and then flow out through the capillary tube 23 and return to the compressor 11. This can ensure the reliability of the oil level in the compressor 11 and also prevent the oil from entering the refrigerant circulation pipeline, thereby improving the working efficiency of the multi-split air conditioning system 1000.

[0091] The gas-liquid separator 24 is provided so that the refrigerant is separated in the gas-liquid separator 24 before entering the compressor 11, so that only the gas phase refrigerant enters the compressor 11, thereby ensuring the reliability of the compressor 11 and preventing the liquid phase refrigerant from entering the compressor 11 and causing liquid compression.

[0092] In some embodiments, such as Figures 14-18 As shown, the indoor unit 200 includes: an indoor heat exchanger 26, a fourth throttle valve 27, and an indoor fan 28.

[0093] For example, the first end of the indoor heat exchanger 26 is connected to the first shut-off valve 18; the first end of the fourth throttle valve 27 is connected to the second end of the indoor heat exchanger 26, and the second end of the fourth throttle valve 27 is connected to the second shut-off valve 19.

[0094] For example, an indoor fan 28 is disposed on one side of an indoor unit 200.

[0095] For example, the indoor heat exchanger 26 can be a copper tube finned heat exchanger or an all-aluminum microchannel heat exchanger.

[0096] The function of the fourth throttle valve 27 is similar to that of the first throttle valve 16 mentioned above, except that the pipes at both ends are different, which will not be described in detail here.

[0097] For example, the indoor fan 28 can be a centrifugal fan, a flow fan, or a vortex fan. The rotation of the indoor fan 28 causes indoor air to flow through the indoor heat exchanger 26, thereby improving the working efficiency of the multi-split air conditioning system 1000.

[0098] The following describes embodiments of this disclosure. Figure 14 The working process of the provided multi-split air conditioning system 1000 is described.

[0099] like Figure 14 As shown, when the multi-split air conditioning system 1000 is in heating mode, the first valve port 121 and the second valve port 122 of the first reversing assembly 12 of the outdoor unit 100 are open, the second port 132 and the third port 133 of the second reversing assembly 13 are open, the third throttle valve 17 is in a throttling state, the first throttle valve 16 is fully closed, the fourth throttle valve 27 is in a throttling state, and the first shut-off valve 18 and the second shut-off valve 19 are open. At this time, the indoor fan 28 rotates, the outdoor fan 20 rotates, and the high-temperature refrigerant discharged by the compressor 11 flows sequentially through the first port 131 and the second port 132 of the first reversing assembly 12, the first shut-off valve 18, the indoor heat exchanger 26, the fourth throttle valve 27, the second shut-off valve 19, the third throttle valve 17, the outdoor heat exchanger 14, the second port 132 and the third port 133 of the second reversing assembly 13, and the gas-liquid separator 24 before returning to the compressor 11, completing the heating cycle. It is understandable that the operation of the other outdoor units 100 and indoor units 200 is the same as the above process, and will not be repeated here.

[0100] like Figure 15 and Figure 16As shown, when the multi-split air conditioning system 1000 is in cooling mode, taking one outdoor unit 100 and one indoor unit 200 as an example, the second valve port 122 and the third valve port 123 of the first reversing assembly 12 are open, the first port 131 and the second port 132 of the second reversing assembly 13 are open, the third throttle valve 17 is fully open, the first throttle valve 16 is fully closed, the fourth throttle valve 27 is in a throttling state, and the first shut-off valve 18 and the second shut-off valve 19 are open. At this time, the indoor fan 28 rotates, the outdoor fan 20 rotates, and the high-temperature refrigerant discharged by the compressor 11 flows sequentially through the first port 131 and the second port 132 of the second reversing assembly 13, the outdoor heat exchanger 14, the third throttle valve 17, the second shut-off valve 19, the fourth throttle valve 27, the indoor heat exchanger 26, the first shut-off valve 18, the second valve port 122 and the third valve port 123 of the first reversing assembly 12, and the gas-liquid separator 24 before returning to the compressor 11, completing the refrigeration cycle. It is understandable that the operation of the other outdoor units 100 and indoor units 200 is the same as the above process, and will not be repeated here.

[0101] In some embodiments, such as Figure 19 As shown, the multi-split air conditioning system 1000 also includes: controller 29.

[0102] For example, controller 29 is used to receive user commands and issue corresponding commands to multi-split air conditioning system 1000, causing multi-split air conditioning system 1000 to execute different operating modes. Controller 29 can also monitor the operating status of multiple outdoor units 100 in multi-split air conditioning system 1000 and control the outdoor units 100 to enter the corresponding operating modes.

[0103] For example, in winter, when the outdoor temperature is low, the multi-split air conditioning system 1000 runs in heating mode for a long time, and the outdoor unit 100 is prone to frost, which leads to a decrease in its heating effect. The controller 29 monitors the frost situation of multiple outdoor units 100 in heating mode, and then controls the corresponding outdoor unit 100 to enter defrost mode.

[0104] It is understood that the operation process of an outdoor unit in the multi-split air conditioning system provided in any of the above embodiments is different, and will be described separately below.

[0105] In some examples, such as Figure 16 or Figure 19In the heating mode of the multi-split air conditioning system shown, the first valve port 121 and the second valve port 122 of the first reversing assembly 12 are connected, the second port 132 and the third port 133 of the second reversing assembly 13 are connected, the first throttle valve 16 is closed, the second throttle valve 25 is open, and the high-temperature refrigerant discharged from the compressor 11 enters the compressor 11 sequentially through the one-way valve 21, the oil separator 22, the first reversing assembly 12, the first shut-off valve 18, the indoor heat exchanger 26, the fourth throttle valve 27, the second shut-off valve 19, the second throttle valve 25, the outdoor heat exchanger 14, the second reversing assembly 13, and the gas-liquid separator 24.

[0106] It is important to note that Figure 19 The dashed arrows in the diagram indicate the refrigerant flow direction in the defrost mode of a multi-split air conditioning system.

[0107] exist Figure 16 or Figure 19 In the cooling mode of the multi-split air conditioning system shown, the second and third valve ports of the first reversing assembly 12 are connected, the first and second ports of the second reversing assembly 13 are connected, the first throttle valve 16 is closed, the second throttle valve 25 is open, and the high-temperature refrigerant discharged from the compressor 11 passes through the check valve, oil separator, second reversing assembly 13, outdoor heat exchanger 14, second shut-off valve 19, fourth throttle valve 27, indoor heat exchanger 26, first shut-off valve 18, first reversing assembly 12, and gas-liquid separator 24 before entering the compressor 11.

[0108] like Figure 16 or Figure 19 As shown, in the defrost mode, the controller 29 is configured to, when the multi-split air conditioning system includes an outdoor unit in heating mode and the outdoor unit meets the defrost conditions, set the outdoor unit as the first outdoor unit 100a, open the first throttle valve 16 of the first outdoor unit 100a, close the second throttle valve 25, keep the first valve port and the second valve port of the first reversing assembly 12 connected, and connect the first port and the second port of the second reversing assembly 13, so that a portion of the refrigerant discharged by the compressor 11 enters the outdoor heat exchanger 14 through the first reversing assembly 12 for defrosting;

[0109] When the first outdoor unit 100a meets the defrosting end conditions, control the first outdoor unit 100a to enter the heating mode.

[0110] For example, the high-temperature refrigerant discharged from the compressor 11 of the first outdoor unit 100a enters the outdoor heat exchanger 14 through the first and second ports of the second reversing assembly 13 to defrost the outdoor heat exchanger 14. Then, the refrigerant flowing out of the outdoor heat exchanger 14 returns to the compressor 11 through the first throttle valve 16 and the gas-liquid separator 24. Because the second throttle valve 25 is closed, the refrigerant flowing out of the outdoor heat exchanger 14 cannot enter the indoor unit 200, thus preventing the indoor unit 200 from blowing out cold air and lowering the indoor temperature. Furthermore, the high-temperature refrigerant discharged from the compressor 11 can also enter the indoor unit 200 through the first and second valve ports of the first reversing assembly 12, thereby maintaining the high-temperature state of the indoor unit 200's piping. This allows the indoor unit 200 to blow out hot air in a shorter time when the first outdoor unit 100a resumes heating.

[0111] Understandably, the above defrosting process can be called bypass defrosting. Figure 16 or Figure 19 The multi-split air conditioning system shown can also be defrosted using reverse defrosting.

[0112] Figure 16 or Figure 19 The reverse defrosting method of the multi-split air conditioning system shown is the same as the cooling mode described above, and will not be repeated here.

[0113] In other examples, such as Figure 17 or Figure 20 The multi-split air conditioning system shown has heating and cooling modes similar to the previous example. Figure 16 or Figure 19 The heating and cooling modes of multi-split air conditioning systems operate in the same way, so they will not be described in detail here.

[0114] The following is about... Figure 17 or Figure 20 The defrosting modes of the multi-split air conditioning system shown are introduced below.

[0115] For example, the controller is configured to, in a multi-split air conditioning system including multiple outdoor units in heating mode, wherein the multiple outdoor units include at least one first outdoor unit 100a and one second outdoor unit 100b, and when the first outdoor unit 100a meets the defrosting conditions, open the first throttle valve 16 of the first outdoor unit 100a, keep the second throttle valve 25 of the first outdoor unit 100a open, keep the first valve port and the second valve port of the first reversing assembly 12 of the first outdoor unit 100a connected, and connect the first port and the second port of the second reversing assembly 13 of the first outdoor unit 100a, so that the refrigerant discharged by the compressor 11 of the first outdoor unit 100a enters the outdoor heat exchanger 14 through the second reversing assembly 13 for defrosting; and keep the second outdoor unit 100b in heating mode.

[0116] When the first outdoor unit 100a meets the defrosting end conditions, control the first outdoor unit 100a to enter the heating mode.

[0117] For example, the high-temperature refrigerant discharged from the compressor 11 of the first outdoor unit 100a enters the outdoor heat exchanger 14 through the first and second ports of the second reversing assembly 13 for defrosting. A portion of the refrigerant flowing out of the outdoor heat exchanger 14 returns to the compressor 11 through the first throttle valve 16. Another portion of the refrigerant flowing out of the outdoor heat exchanger 14 enters the second outdoor unit 100b through the second throttle valve 25, the second shut-off valve 19, and the second shut-off valve 19 of the second outdoor unit 100b. This portion of refrigerant combines with the refrigerant flowing out of the indoor unit 200 and then enters the outdoor heat exchanger 14 of the second outdoor unit 100b. After flowing out of the outdoor heat exchanger 14, it enters the compressor 11 through the second reversing assembly 13 of the second outdoor unit 100b.

[0118] At this time, the refrigerant discharged from the compressor 11 of the second outdoor unit 100b flows into the indoor unit 200 through the first valve port and the second valve port of the first reversing assembly 12 to achieve heating in the indoor unit 200. The refrigerant flowing out from the second valve port of the first reversing assembly 12 of the second outdoor unit 100b also enters the outdoor heat exchanger 14 of the first outdoor unit 100a through the first shut-off valve 18 of the second outdoor unit 100b, the first shut-off valve 18 of the first outdoor unit 100a, the first reversing assembly 12 of the first outdoor unit 100a, and the second reversing assembly 13 of the first outdoor unit 100a, thereby assisting the first outdoor unit 100a in defrosting.

[0119] By adopting the above configuration, the indoor unit 200 can maintain continuous and uninterrupted heating while the first outdoor unit 100a is defrosting, thereby improving user comfort. Furthermore, the second outdoor unit 100b, which is connected in parallel with the first outdoor unit 100a, can assist in defrosting, improving the defrosting effect and shortening the defrosting time.

[0120] In some other examples, such as Figure 18 or Figure 21 The multi-split air conditioning system shown has heating and cooling modes similar to the previous example. Figure 16 or Figure 19 The heating and cooling modes of the Zhongzhong multi-split air conditioning system operate similarly. When heating or cooling, both the first throttle valve 16 and the third throttle valve 17 are closed, and the conduction status of the first reversing assembly 12 and the second reversing assembly 13 is the same as in the example above, so it will not be repeated here.

[0121] For example, controller 29 is configured to, in a multi-split air conditioning system including multiple outdoor units in heating mode, wherein the multiple outdoor units include at least a first outdoor unit 100a and a second outdoor unit 100b connected in parallel, and when the first outdoor unit 100a meets the defrosting conditions, open the first throttle valve 16 and the third throttle valve 17 of the first outdoor unit 100a, close the second throttle valve 25 of the first outdoor unit 100a, keep the first valve port 121 and the second valve port 122 of the first reversing assembly 12 of the first outdoor unit 100a connected, and connect the first port 131 and the second port 132 of the second reversing assembly 13 of the first outdoor unit 100a, so that the refrigerant discharged by the compressor 11 of the first outdoor unit 100a enters the outdoor heat exchanger 14 through the second reversing assembly 13 for defrosting; and keep the second outdoor unit 100b in heating mode.

[0122] When the first outdoor unit 100a meets the defrosting end conditions, control the first outdoor unit 100a to enter the heating mode.

[0123] For example, such as Figure 18 or Figure 21 As shown, the refrigerant discharged from the first outdoor unit 100a passes sequentially through the second reversing assembly 13, outdoor heat exchanger 14, first throttle valve 16, auxiliary heat exchanger 15, and gas-liquid separator 24 of the first outdoor unit 100a and returns to the compressor 11. The refrigerant discharged from the first outdoor unit 100a can also pass sequentially through the first valve port 121, second valve port 122, auxiliary heat exchanger 15, third throttle valve 17, and second shut-off valve 19 of the first reversing assembly 12 of the first outdoor unit 100a, and then merges with the refrigerant from the indoor unit 200. After passing through the second shut-off valve 19 and second throttle valve 25 of the second outdoor unit 100b, it enters the outdoor heat exchanger 14 of the second outdoor unit 100b, and then returns to the compressor 11 of the second outdoor unit 100b through the second reversing assembly 13.

[0124] While the first outdoor unit 100a is defrosting, the second outdoor unit 100b is in heating mode. The high-temperature refrigerant discharged from the compressor 11 in the second outdoor unit 100b is discharged through the first valve port 121 and the second valve port 122 of the first reversing assembly 12, and then enters two circulation loops respectively. In the first circulation loop, a portion of the refrigerant passes through the first shut-off valve 18 and the connecting pipe 30 of the second outdoor unit 100b in sequence, then enters the indoor heat exchanger 26, the fourth throttle valve 27, the second shut-off valve 19, the second throttle valve 25 of the second outdoor unit 100b, the outdoor heat exchanger 14, the second reversing assembly 13, and the gas-liquid separator 24, before returning to the compressor 11. The second circulation loop is as follows: another portion of the refrigerant flows sequentially through the first shut-off valve 18 and connecting pipe 30 of the second outdoor unit 100b into the first shut-off valve 18 of the first outdoor unit 100a, through the auxiliary heat exchanger 15 of the first outdoor unit 100a, through the second throttle valve 25, the second shut-off valve 19, and connecting pipe 30, and then out of the first outdoor unit 100a. The second circulation loop is used for heating and assisting in defrosting the first outdoor unit 100a.

[0125] While the first outdoor unit is defrosting, the indoor unit can maintain continuous and uninterrupted heating, improving user comfort. Furthermore, a second outdoor unit connected in parallel with the first outdoor unit can assist in defrosting, improving the defrosting effect and shortening the defrosting time.

[0126] For example, when the second outdoor unit 100b meets the defrosting conditions, the process of the second outdoor unit 100b switching from the heating mode to the defrosting mode is the same as the process of the first outdoor unit 100a switching from the heating mode to the defrosting mode in the example above, and will not be described again here.

[0127] For example, when multiple outdoor units 100 meet the defrosting conditions, the multiple outdoor units 100 take turns entering the defrosting mode and defrost in sequence until all outdoor units 100 that need defrosting have completed defrosting.

[0128] In some embodiments, the defrosting termination conditions include: the temperature of the refrigerant discharged from the second end of the outdoor heat exchanger 14 of the first outdoor unit 100a is greater than or equal to a preset temperature and lasts for a first preset time; and / or, the suction pressure of the compressor 11 of the first outdoor unit 100a is greater than or equal to a first preset pressure and lasts for a second preset time; and / or, the duration of the defrosting operation of the first outdoor unit 100a is greater than or equal to a third preset time.

[0129] For example, the conditions for the defrosting to end can be at least one of the three conditions mentioned above.

[0130] For example, the preset temperature can be greater than or equal to 6°C. For instance, the preset temperature can be 7°C, and the first preset time can be 5 seconds.

[0131] For example, such as Figure 21 As shown, the first outdoor unit 100a also includes a temperature sensor 31. The temperature sensor 31 is used to detect the temperature of the refrigerant discharged from the outdoor heat exchanger 14.

[0132] For example, if the temperature of the refrigerant discharged from the outdoor heat exchanger 14 of the first outdoor unit 100a is greater than or equal to 7°C, and the duration of this temperature is greater than or equal to 5 seconds, it can be determined that the defrosting of the first outdoor unit 100a is over, and it can re-enter the heating mode.

[0133] For example, the first preset pressure can be 0.8 MPa and the second preset time can be 20 seconds.

[0134] For example, if the suction pressure of the compressor 11 of the first outdoor unit 100a is greater than or equal to 0.8 MPa and the duration is greater than or equal to 20 seconds, it can be determined that the defrosting of the first outdoor unit 100a is over and it can re-enter the heating mode.

[0135] For example, the aforementioned third preset time can be 600s. For instance, if the defrosting operation of the first outdoor unit 100a lasts for more than or equal to 600s, it can be determined that the defrosting of the first outdoor unit 100a has ended, and it can re-enter the heating mode.

[0136] By adopting the above setting method, the multi-split air conditioning system 1000 can determine the defrosting status of the outdoor unit 100, improve its heating efficiency, and avoid reducing user comfort due to prolonged defrosting.

[0137] In some embodiments, the controller 29 is further configured to, when the first outdoor unit 100a is performing a defrosting operation, control the outdoor fan 20 of the first outdoor unit 100a to not work, and control the speed of the outdoor fan 20 of the second outdoor unit 100b to be greater than or equal to a preset speed.

[0138] For example, the preset rotational speed can be 500 r / s.

[0139] For example, when the first outdoor unit 100a is defrosting, the controller 29 controls the speed of the outdoor fan 20 of the first outdoor unit 100a to 0 r / s, and controls the speed of the outdoor fan 20 of the second outdoor unit 100b to be greater than or equal to 500 r / s.

[0140] By adopting the above configuration, the defrosting efficiency of the first outdoor unit 100a can be improved and its defrosting time can be shortened, thereby improving the heating efficiency of the multi-split air conditioning system 1000.

[0141] In some embodiments, the controller 29 is further configured to control the indoor fan 28 of the indoor unit 200 to rotate when the exhaust pressure of the compressor 11 of the second outdoor unit 100b is greater than or equal to a second preset pressure.

[0142] For example, the second preset pressure is 2.3 MPa.

[0143] For example, when the discharge pressure of the compressor 11 of the second outdoor unit 100b is greater than or equal to 2.3 MPa, the controller 29 controls the indoor fan 28 of the indoor unit 200 to rotate.

[0144] By adopting the above configuration, the refrigerant discharged by the compressor 11 of the second outdoor unit 100b can enter the first outdoor unit 100a through the first shut-off valve 18 of the second outdoor unit 100b and the first shut-off valve 18 of the first outdoor unit 100a, thereby improving the defrosting efficiency of the first outdoor unit 100a by utilizing the refrigerant provided by the second outdoor unit 100b.

[0145] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0146] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions within the technical scope disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims. In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A multi-split air conditioning system, characterized in that, The multi-split air conditioning system includes: at least one outdoor unit and multiple indoor units connected in parallel; in the case where the multi-split air conditioning system includes multiple outdoor units, the multiple outdoor units are connected in parallel. The outdoor unit includes a compressor having an air intake and an exhaust port; The first reversing assembly has at least a first valve port, a second valve port and a third valve port, wherein the first valve port is connected to the exhaust port, the third valve port is connected to the intake port, and the second valve port is connected to one of the first valve port and the third valve port for reversing. The second commutation component has at least a first port, a second port and a third port, the first port being connected to the exhaust port, the third port being connected to the intake port, and the second port being connected to one of the first port and the third port for commutation. An outdoor heat exchanger, wherein a first end of the outdoor heat exchanger is connected to a second port; A first throttle valve, the first end of which is connected to the second end of the outdoor heat exchanger, and the second end of which is connected to the air intake; The second throttle valve has a first end connected to the second end of the outdoor heat exchanger and a second end connected to the indoor unit. An auxiliary heat exchanger is provided, wherein the second valve port of the first reversing assembly is connected to the first end of the auxiliary heat exchanger and the indoor unit, the second end of the auxiliary heat exchanger is connected to its first end, and the second end of the auxiliary heat exchanger is connected to the indoor unit.

2. The multi-split air conditioning system according to claim 1, wherein, In the case where the multi-split air conditioning system includes multiple outdoor units, the multiple outdoor units include at least a first outdoor unit and a second outdoor unit, and the outdoor units further include: a third throttle valve; The second end of the auxiliary heat exchanger is connected to the first end of the third throttling valve, and the second end of the third throttling valve is connected to the indoor unit; The third end of the auxiliary heat exchanger is connected to the second end of the outdoor heat exchanger through the first throttling valve, and the fourth end of the auxiliary heat exchanger is connected to the air intake. The third end of the auxiliary heat exchanger is connected to its fourth end. The refrigerant flowing through the first and second ends of the auxiliary heat exchanger can exchange heat with the refrigerant flowing through the third and fourth ends of the auxiliary heat exchanger. The second valve port of the first outdoor unit is also connected to the second valve port of the second outdoor unit; the second end of the second throttle valve of the first outdoor unit is also connected to the second end of the second throttle valve of the second outdoor unit.

3. The multi-split air conditioning system according to claim 1 or 2, characterized in that, The multi-split air conditioning system further includes: multiple connecting pipes; the multiple connecting pipes connect the multiple outdoor units to the multiple indoor units; The outdoor unit also includes: a first shut-off valve, a second shut-off valve, and an outdoor fan located on one side of the outdoor heat exchanger; The first end of the first shut-off valve is connected to the second valve port of the first reversing assembly; the second end of the first shut-off valve is connected to the indoor unit. The first end of the second shut-off valve is connected to the second end of the second throttle valve; the second end of the second shut-off valve is connected to the indoor unit.

4. The multi-split air conditioning system according to claim 3, wherein, The outdoor unit also includes: An oil separator, wherein a first end of the oil separator is connected to the exhaust port of the compressor, and a second end of the oil separator is connected to the first valve port of the first reversing assembly and the first valve port of the second reversing assembly, so that the exhaust port of the compressor is connected to the first valve port of the first reversing assembly and the first valve port of the second reversing assembly; A gas-liquid separator; the first end of the gas-liquid separator is connected to the suction port of the compressor, and the second end of the gas-liquid separator is connected to the third valve port of the first reversing assembly and the third port of the second reversing assembly, respectively, so that the suction port of the compressor is connected to the third valve port of the first reversing assembly and the third port of the second reversing assembly.

5. The multi-split air conditioning system according to claim 4, wherein, The indoor unit includes: An indoor heat exchanger, wherein a first end of the indoor heat exchanger is connected to a second end of the first shut-off valve; The fourth throttle valve has its first end connected to the second end of the indoor heat exchanger, and its second end connected to the second end of the second shut-off valve. An indoor fan is located on one side of the indoor unit. 6.The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system also includes: a controller; The controller is configured to, When the multi-split air conditioning system includes an outdoor unit in heating mode and the outdoor unit meets the defrosting conditions, the outdoor unit is designated as the first outdoor unit. The first throttle valve of the first outdoor unit is opened, the second throttle valve is closed, the first valve port and the second valve port of the first reversing assembly are kept in contact, and the first port and the second port of the second reversing assembly are connected, so that a portion of the refrigerant discharged by the compressor enters the outdoor heat exchanger through the first reversing assembly for defrosting. When the first outdoor unit meets the defrosting end conditions, control the first outdoor unit to enter the heating mode. 7.The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system also includes: a controller; The controller is configured to, The multi-split air conditioning system includes multiple outdoor units in heating mode. Each outdoor unit includes at least one first outdoor unit and one second outdoor unit. When the first outdoor unit meets the defrosting conditions, the first throttle valve of the first outdoor unit is opened, and the second throttle valve of the first outdoor unit remains open. The first and second valve ports of the first reversing assembly of the first outdoor unit are kept connected, and the first and second ports of the second reversing assembly of the first outdoor unit are connected. This allows the refrigerant discharged from the compressor of the first outdoor unit to enter the outdoor heat exchanger via the second reversing assembly for defrosting; the second outdoor unit is maintained in heating mode. When the first outdoor unit meets the defrosting end conditions, control the first outdoor unit to enter the heating mode. 8.The multi-split air conditioning system according to claim 2, characterized in that, The multi-split air conditioning system also includes: a controller; The multi-split air conditioning system includes multiple outdoor units in heating mode. These outdoor units include at least one first outdoor unit and one second outdoor unit connected in parallel. When the first outdoor unit meets the defrosting conditions, the first and third throttle valves of the first outdoor unit are opened, and the second throttle valve of the first outdoor unit is closed. The first and second valve ports of the first reversing assembly of the first outdoor unit are kept connected, and the first and second ports of the second reversing assembly of the first outdoor unit are connected, allowing the refrigerant discharged from the compressor of the first outdoor unit to enter the outdoor heat exchanger for defrosting via the second reversing assembly; thus, the second outdoor unit is maintained in heating mode. When the first outdoor unit meets the defrosting end conditions, control the first outdoor unit to enter the heating mode.

9. The multi-split air conditioning system according to any one of claims 6 to 8, characterized in that, The defrosting termination condition includes: the temperature of the refrigerant discharged from the second end of the outdoor heat exchanger of the first outdoor unit is greater than or equal to a preset temperature, and this condition is maintained for a first preset time. And / or, the suction pressure of the compressor of the first outdoor unit is greater than or equal to a first preset pressure, and lasts for a second preset time; And / or, the defrosting operation duration of the first outdoor unit is greater than or equal to a third preset time. 10.The multi-split air conditioning system according to claim 7 or 8, characterized in that, The controller is further configured to, when the first outdoor unit is performing a defrosting operation, control the outdoor fan of the first outdoor unit to not work, and control the speed of the outdoor fan of the second outdoor unit to be greater than or equal to a preset speed; or, the controller is further configured to, when the exhaust pressure of the compressor of the second outdoor unit is greater than or equal to a second preset pressure, control the indoor fan of the indoor unit to rotate.

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