Multi-connected air conditioning system

Abstract

This application discloses a multi-split air conditioning system, relating to the field of air conditioning technology. The multi-split air conditioning system includes a compressor, an outdoor heat exchanger, a first reversing valve, an indoor heat exchanger, and a second reversing valve. The first reversing valve is connected to the compressor outlet, the compressor inlet, and the outdoor heat exchanger. Multiple indoor heat exchangers are configured, each independently. Each indoor heat exchanger is connected to a first main circuit and a second main circuit, the first main circuit being connected to the outdoor heat exchanger. The second main circuit is connected to a first branch circuit and a second branch circuit. The other end of the first branch circuit is connected to the compressor inlet. The second reversing valve is connected to the compressor outlet, the compressor inlet, and the other end of the second branch circuit. A first shut-off valve is provided on the first branch circuit. A second shut-off valve is provided on the second branch circuit. In this application, the refrigerant can circulate independently in each indoor heat exchanger without interfering with each other, thus enabling the multi-split air conditioning system to simultaneously cool and heat.

Description

Technical Field

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

[0002] Multi-split air conditioning systems connect multiple indoor units to a single outdoor unit, using refrigerant circulation for heat exchange to achieve independent temperature control for multiple indoor spaces. However, their operation is limited by the refrigerant flow path, preventing the system from simultaneously meeting the cooling and heating needs of some indoor units. Utility Model Content

[0003] To address the shortcomings of related technologies, this application provides a multi-split air conditioning system. By setting two reversing valves to adjust the flow direction of refrigerant through the indoor and outdoor heat exchangers, and by setting multiple flow paths for refrigerant to enter and exit the indoor heat exchangers, the refrigerant can circulate independently in each indoor heat exchanger without interfering with each other, thereby enabling the multi-split air conditioning system to simultaneously cool and heat.

[0004] This application provides a multi-split air conditioning system, including:

[0005] compressor;

[0006] Outdoor heat exchanger;

[0007] The first reversing valve is connected to the compressor outlet, the compressor inlet, and the outdoor heat exchanger; in the first state, the first reversing valve connects the outdoor heat exchanger to the compressor outlet; in the second state, the first reversing valve connects the compressor inlet to the outdoor heat exchanger.

[0008] The indoor heat exchangers are configured in multiple ways, and the multiple indoor heat exchangers are set independently of each other; each indoor heat exchanger is connected to a first main line and a second main line, and the first main line is connected to an outdoor heat exchanger.

[0009] The first branch road connects to the second main road at one end and to the compressor inlet at the other end.

[0010] The second branch road connects at one end to the second main road;

[0011] The second reversing valve is connected to the compressor outlet, the compressor inlet, and the end of the second branch away from the second main branch. In the first state, the second reversing valve connects the second branch to the compressor outlet; in the second state, the second reversing valve connects the second branch to the compressor inlet.

[0012] The first shut-off valve is located on the first branch and is used to control the opening and closing of the first branch;

[0013] The second shut-off valve is located on the second branch and is used to control the opening and closing of the second branch.

[0014] When the indoor heat exchanger is a condenser, the first shut-off valve is closed and the second shut-off valve is open. The refrigerant flows into the indoor heat exchanger from the second branch and then flows to the outdoor heat exchanger through the first main branch.

[0015] When the indoor heat exchanger is an evaporator, at least one of the first and second shut-off valves is open. The refrigerant flows into the indoor heat exchanger through the first main line, then flows back to the compressor through the first branch line from the second main line, and / or flows back to the compressor through the second branch line and the second reversing valve from the second main line.

[0016] In this technical solution, multiple independent indoor heat exchangers are set up, along with a first main line, a second main line, a first branch line, a second branch line, a first reversing valve, and a second reversing valve connecting each component. These, combined with the control of the first and second branch lines by the first and second shut-off valves, allow for different refrigerant flow control when the indoor heat exchanger functions as a condenser or evaporator. Specifically, when the indoor heat exchanger functions as a condenser (heating mode), the first branch line is closed and the second branch line is open. High-temperature refrigerant flows from the second branch line into the indoor heat exchanger, releases heat, and then flows through the first main line to the outdoor heat exchanger. When the indoor heat exchanger functions as an evaporator (cooling mode), the first branch line is open and the second branch line is closed. The refrigerant absorbs heat through the first main line and then returns directly to the compressor through the first branch line. This avoids refrigerant flow conflicts caused by different operating modes of the indoor units, enabling the multi-split air conditioning system to flexibly meet the cooling or heating needs of different indoor environments. Furthermore, each indoor heat exchanger operates independently, improving system flexibility and energy efficiency. The system can adjust its operating status according to actual usage, reducing energy consumption.

[0017] In some embodiments of this application, when at least one indoor heat exchanger in the operating indoor unit is a condenser, the second reversing valve is in a first state; when all indoor heat exchangers in the operating indoor unit are evaporators, the second reversing valve is in a second state.

[0018] In the technical solution, the state of the second reversing valve is related to the working state of the indoor heat exchanger. When an indoor heat exchanger is working as a condenser, the second reversing valve is in the first state. When all the indoor heat exchangers in the operating indoor units are evaporators, the second reversing valve is in the second state, ensuring that the refrigerant flows smoothly through the evaporator and back to the compressor; ensuring that the refrigerant can flow through the second branch to the indoor heat exchanger that is acting as a condenser, thus ensuring the stability and reliability of the multi-split air conditioning system.

[0019] In some embodiments of this application, the multi-split air conditioning system includes a single heating mode. In the single heating mode, the outdoor heat exchanger is an evaporator and the indoor heat exchanger is a condenser. A first shut-off valve is closed and a second shut-off valve is open. A first reversing valve is used to connect the outdoor heat exchanger to the compressor inlet. A second reversing valve is used to connect the second branch to the compressor outlet.

[0020] In the technical solution, the refrigerant is circulated in one direction by the coordinated control of the reversing valve and the shut-off valve, so that all indoor units can heat at the same time, avoiding the problem of heat distribution contradictions when heating in traditional systems; clear flow direction control can maintain system pressure balance and prevent component damage caused by refrigerant flow conflicts. At the same time, when the outdoor heat exchanger acts as an evaporator, the compressor power ensures the continuous phase change of the refrigerant, improving heating efficiency.

[0021] In some embodiments of this application, the multi-split air conditioning system includes a single cooling mode, in which the outdoor heat exchanger is a condenser and the indoor heat exchanger is an evaporator; at least one of the first shut-off valve and the second shut-off valve is open, and the first reversing valve is used to connect the compressor outlet with the outdoor heat exchanger.

[0022] When the second shut-off valve is open, the second directional valve is used to connect the second branch to the compressor outlet.

[0023] In this technical solution, the outdoor heat exchanger is switched to act as a condenser and the indoor heat exchanger to act as an evaporator by a reversing valve. This ensures that the heat release and absorption processes are unidirectional during cooling, avoiding the decrease in cooling efficiency caused by the chaotic refrigerant flow in traditional systems. The selective opening of the first and second shut-off valves can adjust the refrigerant flow according to the number of indoor units in operation. At the same time, the state of the second reversing valve, in coordination with the shut-off valve, ensures that the refrigerant return path is unobstructed, maintains stable low-pressure side pressure in the system, and improves cooling reliability.

[0024] In some embodiments of this application, the multi-split air conditioning system includes a first mixing mode. In the first mixing mode, the outdoor heat exchanger is an evaporator, and at least one indoor heat exchanger is a condenser. A first reversing valve is used to connect the outdoor heat exchanger to the compressor inlet; a second reversing valve is used to connect the second branch to the compressor outlet; a first shut-off valve corresponding to the indoor heat exchanger that acts as an evaporator is open, and a second shut-off valve is closed; a first shut-off valve corresponding to the indoor heat exchanger that acts as a condenser is closed, and a second shut-off valve is open.

[0025] In the technical solution, under the first mixing mode, one path of high-temperature, high-pressure refrigerant flows through the second reversing valve and the second branch into the indoor heat exchanger (which acts as a condenser) to release heat, then flows through the first main path into the outdoor heat exchanger to absorb heat, and returns to the compressor. The other path of refrigerant flows through the first main path into the indoor heat exchanger (which acts as an evaporator) to absorb heat, and returns to the compressor through the second main path and the first branch. By independently controlling the refrigerant flow of each indoor unit, some rooms can be heated while others are cooled, meeting the differentiated needs of different areas. The heat release by the indoor unit (as a condenser) and the heat absorption by the indoor unit (as an evaporator) occur simultaneously. The outdoor heat exchanger, acting as an evaporator, absorbs the heat emitted by the indoor condenser, reducing energy loss and achieving a rational distribution and utilization of heat within the system.

[0026] In some embodiments of this application, the multi-split air conditioning system includes a second mixing mode, in which the outdoor heat exchanger is a condenser, at least one indoor heat exchanger is a condenser, and at least one indoor heat exchanger is an evaporator; a first reversing valve is used to connect the compressor outlet to the outdoor heat exchanger; and a second reversing valve is used to connect the second branch to the compressor outlet.

[0027] The first shut-off valve for the indoor heat exchanger that acts as an evaporator is open, and the second shut-off valve is closed; the first shut-off valve for the indoor heat exchanger that acts as a condenser is closed, and the second shut-off valve is open.

[0028] In this technical solution, the refrigerant discharged from the compressor is split between an outdoor heat exchanger (condensing and releasing heat) and an indoor heat exchanger (releasing heat), which acts as a condenser. The two refrigerant streams converge in the first main path and flow into the indoor heat exchanger (acting as an evaporator) to absorb heat. The refrigerant then returns to the compressor via the second main path and the first branch path. The outdoor heat exchanger acts as a condenser to centrally discharge heat, while some indoor units act as condensers to assist in heat release, and others act as evaporators to absorb heat. This achieves a hybrid operation of "partial cooling + partial heating," adapting to the temperature and humidity control needs in complex scenarios. Precise control of the reversing valve and shut-off valve prevents refrigerant flow conflicts between different indoor units. Simultaneously, the outdoor condenser handles heat dissipation uniformly, preventing system pressure imbalance and improving stability during multi-mode operation.

[0029] In some embodiments of this application, a water tank is also included, and a water tank heat exchanger is provided inside the water tank. One interface of the water tank heat exchanger is connected to a third main circuit, and the other end of the third main circuit is connected to the outlet of the compressor. Another interface of the water tank heat exchanger is connected to a fourth main circuit, and the other end of the fourth main circuit is connected to the first main circuit.

[0030] In this technical solution, a water tank is installed, and a water tank heat exchanger is installed inside the water tank. The water tank heat exchanger is connected to the system via a third and fourth main circuit, so that the refrigerant heats the water in the water tank through the water tank heat exchanger, thereby meeting the user's demand for domestic hot water. This allows the multi-split air conditioning system to not only regulate indoor temperature but also provide hot water, improving the overall utilization rate and practicality of the system, achieving multiple uses in one unit, and bringing more convenience and energy-saving benefits to users.

[0031] In some embodiments of this application, a third reversing valve is also included, which is connected to the compressor outlet, the compressor inlet and the third main line, and is used to switch the flow direction of refrigerant through the water tank heat exchanger.

[0032] In the technical solution, a third reversing valve is installed to regulate the flow direction of the refrigerant through the water tank heat exchanger. This allows the water tank heat exchanger to be used as a condenser to heat the water in the tank, or as an evaporator to defrost the outdoor heat exchanger. When heating the water in the tank is required, the third reversing valve controls the refrigerant to flow through the water tank heat exchanger in a specific direction to achieve heating. When defrosting the outdoor heat exchanger, the refrigerant flow direction is changed, and the water tank heat exchanger is used to assist in defrosting. This allows the water tank heat exchanger to meet the different operating requirements of the multi-split air conditioning system.

[0033] In some embodiments of this application, the third directional valve includes a first state and a second state. When the third directional valve is in the first state, it is used to connect the third main circuit with the outlet of the compressor. When the third directional valve is in the second state, it is used to connect the inlet of the compressor with the third main circuit.

[0034] When the water tank heat exchanger is a condenser, the third reversing valve is in the first state; when the water tank heat exchanger is an evaporator, the third reversing valve is in the second state.

[0035] In the technical solution, when the water tank heat exchanger heats the water in the water tank, the third reversing valve is in the first state, ensuring that the refrigerant heats the water through a suitable path; when the water tank heat exchanger is used to defrost the outdoor heat exchanger, the third reversing valve is in the second state, guiding the refrigerant to circulate along the path required for defrosting, so that the water tank heat exchanger can operate efficiently in different functional processes, improving the realization effect and operating efficiency of each function of the system, and ensuring the stable and reliable operation of the system.

[0036] In addition, this application also provides a multi-split air conditioning system, including:

[0037] Outdoor unit, which includes:

[0038] compressor;

[0039] Outdoor heat exchanger;

[0040] The first reversing valve is connected to the compressor outlet, the compressor inlet, and the outdoor heat exchanger;

[0041] There are multiple indoor units, each independently configured; each indoor unit includes:

[0042] The indoor heat exchanger is connected to a first main line and a second main line, and the first main line is connected to the outdoor heat exchanger.

[0043] Multi-split air conditioning systems also include:

[0044] The first branch road connects to the second main road at one end and to the compressor inlet at the other end.

[0045] The second branch road connects at one end to the second main road;

[0046] The second reversing valve is connected to the compressor outlet, the compressor inlet, and the end of the second branch away from the second main branch;

[0047] When the indoor heat exchanger is a condenser, the first branch is cut off and the second branch is connected. The refrigerant flows into the indoor heat exchanger from the second branch and then flows to the outdoor heat exchanger through the first main branch.

[0048] When the indoor heat exchanger is an evaporator, at least one of the first branch and the second branch is connected. After the refrigerant flows into the indoor heat exchanger through the first main branch, it flows back to the compressor through the second main branch and / or flows back to the compressor through the second branch and the second reversing valve.

[0049] In this technical solution, each indoor unit's indoor heat exchanger is connected to the outdoor heat exchanger via a main circuit, and is equipped with independent first and second branches. Combined with the switching of the second reversing valve, the refrigerant flow can be independently controlled. When the indoor heat exchanger is a condenser (indoor unit heating), the second branch allows high-temperature, high-pressure refrigerant to enter the indoor unit to release heat, and then returns to the outdoor unit via the main circuit. When the indoor heat exchanger is an evaporator (indoor unit cooling), the first branch allows low-temperature, low-pressure refrigerant to enter the indoor unit to absorb heat, and then directly returns to the compressor via the first branch. This allows each indoor unit to operate independently, facilitating flexible use by users according to actual needs and ensuring the stability and reliability of the multi-connected air conditioning system.

[0050] In the above embodiments, a multi-split air conditioning system adjusts the flow direction of refrigerant when it flows through the outdoor heat exchanger by setting a first reversing valve, and adjusts the flow direction of refrigerant when it flows through the indoor heat exchanger by setting a second reversing valve. A first branch and a second branch are connected to the indoor heat exchanger so that the refrigerant has multiple flow paths to enter and exit the indoor heat exchanger. This allows the refrigerant to circulate independently in each indoor heat exchanger without interfering with each other, thereby enabling the multi-split air conditioning system to cool and heat simultaneously. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the structure of one embodiment of the multi-split air conditioning system in this application;

[0052] Figure 2 This is a schematic diagram of the refrigerant flow path in a single heating mode of a multi-split air conditioning system in one embodiment of the multi-split air conditioning system in this application;

[0053] Figure 3 This is a schematic diagram of the refrigerant flow path in a single cooling mode of a multi-split air conditioning system in one embodiment of the multi-split air conditioning system in this application;

[0054] Figure 4 This is a schematic diagram of the refrigerant flow path in the first mixing mode of a multi-split air conditioning system in one embodiment of the multi-split air conditioning system in this application;

[0055] Figure 5 This is a schematic diagram of the refrigerant flow path in the second mixing mode of a multi-split air conditioning system in one embodiment of the multi-split air conditioning system in this application;

[0056] Figure 6 This is a schematic diagram of the refrigerant flow path when the multi-split air conditioning system in a single heating mode defrosts using a water tank heat exchanger, according to one embodiment of the multi-split air conditioning system in this application.

[0057] Figure 7 This is a schematic diagram of the refrigerant flow path when the multi-split air conditioning system in a single heating mode defrosts using an indoor heat exchanger in one embodiment of the multi-split air conditioning system in this application.

[0058] Figure 8 This is a schematic diagram of the refrigerant flow path during defrosting using the indoor heat exchanger in the refrigeration indoor unit in a first hybrid mode of a multi-split air conditioning system in this application.

[0059] Figure 9 This is a schematic diagram of the refrigerant flow path during defrosting using the water tank heat exchanger and the indoor heat exchanger in the cooling indoor unit in a first mixing mode of the multi-split air conditioning system in this application.

[0060] Figure 10 This is a schematic diagram of the refrigerant flow path during defrosting using all indoor heat exchangers in a first mixing mode of a multi-split air conditioning system in one embodiment of the present application.

[0061] In the diagram, 100 is the outdoor unit; 200 is the indoor unit; and 300 is the water tank.

[0062] 110. Compressor; 120. Outdoor heat exchanger; 130. Outdoor fan; 140. First reversing valve; 150. Second reversing valve; 160. Third reversing valve; 170. Outdoor expansion valve;

[0063] 210. Indoor heat exchanger; 220. Indoor expansion valve; 230. First shut-off valve; 240. Second shut-off valve;

[0064] 211. First indoor heat exchanger; 212. Second indoor heat exchanger; 213. Third indoor heat exchanger;

[0065] 221. First indoor expansion valve; 222. Second indoor expansion valve; 223. Third indoor expansion valve;

[0066] 201. First main road; 202. Second main road; 203. First side road; 204. Second side road;

[0067] 310. Water tank heat exchanger; 320. Water tank expansion valve;

[0068] 301, Third Main Road; 302, Fourth Main Road. Detailed Implementation

[0069] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0070] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0071] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0072] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0073] In related technologies, multi-split air conditioning systems typically employ single refrigerant pipeline flow direction control. In traditional multi-split systems, the outdoor unit 100 is connected to the indoor unit 200 via a single liquid supply pipe and a single return pipe. The refrigerant circulates in the system in a single direction (during cooling, it flows from the outdoor unit 100 to the indoor unit 200 for evaporation and heat absorption; during heating, a four-way valve switches the flow direction, causing the refrigerant to condense and release heat in the indoor unit 200). At any given time, the refrigerant's flow direction and state (liquid or gaseous) are uniform, making it impossible for different indoor units 200 to simultaneously exhibit opposite heat absorption and release processes. If some indoor units 200 require cooling (evaporation and heat absorption) and others require heating (condensation and heat release), the refrigerant flow directions will conflict, leading to an imbalance in heat distribution (a contradiction between cooling heat dissipation and heating heat absorption), potentially damaging system components due to pressure imbalances and other issues.

[0074] Based on this, this application provides a multi-split air conditioning system, which adjusts the flow direction of refrigerant through the indoor heat exchanger 210 by setting a reversing valve, and connects the indoor heat exchanger 210 to multiple flow paths for refrigerant to enter and exit, so that the refrigerant can circulate independently in each indoor heat exchanger 210, achieving non-interference between different indoor units 200, thereby enabling the multi-split air conditioning system to cool and heat simultaneously.

[0075] The multi-split air conditioning system provided in this application can have various implementation forms. Figure 1 This is a specific implementation of the multi-split air conditioning system of this application.

[0076] like Figures 1-10 As shown, a multi-split air conditioning system includes an indoor unit 200, which is located indoors. Multiple indoor units 200 are typically configured, each independently located in a different room, allowing the multi-split air conditioning system to cool or heat multiple rooms.

[0077] like Figures 1-10 As shown, the indoor unit 200 includes an indoor heat exchanger 210, which is used for heat exchange with indoor air. A refrigerant for heat exchange with the air flows inside the indoor heat exchanger 210. When the indoor unit 200 is cooling, the indoor heat exchanger 210 operates as an evaporator; when the indoor unit 200 is heating, the indoor heat exchanger 210 operates as a condenser.

[0078] One interface of the indoor heat exchanger 210 is connected to the first main line 201, and the other interface of the indoor heat exchanger 210 is connected to the second main line 202. When the indoor heat exchanger 210 is an evaporator, the refrigerant flows into the indoor heat exchanger 210 from the first main line 201 and flows out of the indoor heat exchanger 210 from the second main line 202. When the indoor heat exchanger 210 is a condenser, the refrigerant flows into the indoor heat exchanger 210 from the second main line 202 and flows out of the indoor heat exchanger 210 from the first main line 201.

[0079] like Figures 1-10 As shown, the multi-split air conditioning system includes an outdoor unit 100, which is located outdoors. The outdoor unit 100 and the indoor unit 200 cooperate with each other to realize the circulation of refrigerant between the outdoor unit 100 and the indoor unit 200, so that the indoor unit 200 can cool or heat the indoor environment.

[0080] Outdoor unit 100 is usually set as one unit. One outdoor unit 100 works in conjunction with multiple indoor units 200. The refrigerant is distributed among the multiple indoor units 200 so that the multiple indoor units 200 can cool or heat different rooms.

[0081] like Figures 1-10 As shown, the outdoor unit 100 includes an outdoor heat exchanger 120, which is used for heat exchange with outdoor air; refrigerant for heat exchange with air flows inside the outdoor heat exchanger 120. One interface of the outdoor heat exchanger 120 is connected to the first main line 201. When the outdoor heat exchanger 120 is an evaporator, refrigerant flows into the outdoor heat exchanger 120 from the first main line 201; when the outdoor heat exchanger 120 is a condenser, refrigerant flows out of the outdoor heat exchanger 120 from the first main line 201.

[0082] When the indoor unit 200 is cooling, the outdoor heat exchanger 120 works as a condenser; when the indoor unit 200 is heating, the outdoor heat exchanger 120 works as an evaporator.

[0083] When a multi-split air conditioning system is in operation, if the outdoor heat exchanger 120 is a condenser, then at least one indoor heat exchanger 210 is an evaporator; if the outdoor heat exchanger 120 is an evaporator, then at least one indoor heat exchanger 210 is a condenser, so as to ensure that the refrigerant can switch between the gas phase and the liquid phase.

[0084] like Figures 1-10 As shown, the outdoor unit 100 includes an outdoor fan 130, which is located near the outdoor heat exchanger 120 to accelerate the heat exchange efficiency between the air and the outdoor heat exchanger 120.

[0085] like Figures 1-10As shown, the outdoor unit 100 includes a compressor 110, which is used to compress refrigerant gas in a low temperature and low pressure state into refrigerant gas in a high temperature and high pressure state. The compressor 110 provides power for the circulation of refrigerant in the pipeline.

[0086] like Figures 1-10 As shown, the outdoor unit 100 includes a first reversing valve 140, which is used to regulate the flow direction and flow path of the refrigerant when it flows through the outdoor heat exchanger 120. The first port of the first reversing valve 140 is connected to the outlet of the compressor 110, the second port of the first reversing valve 140 is connected to the outdoor heat exchanger 120, and the third port of the first reversing valve 140 is connected to the inlet of the compressor 110.

[0087] The first reversing valve 140 includes a first state. When the first reversing valve 140 is in the first state, the first reversing valve 140 is used to connect the outdoor heat exchanger 120 and the outlet of the compressor 110. The first port of the first reversing valve 140 is connected to the second port of the first reversing valve 140, and the third port of the first reversing valve 140 is cut off.

[0088] When the outdoor heat exchanger 120 is a condenser, the first reversing valve 140 is in the first state. After the refrigerant is discharged from the outlet of the compressor 110, it flows into the outdoor heat exchanger 120 through the first reversing valve 140 to release heat.

[0089] The first reversing valve 140 includes a second state. When the first reversing valve 140 is in the second state, the first reversing valve 140 is used to connect the inlet of the compressor 110 with the outdoor heat exchanger 120. The first port of the first reversing valve 140 is cut off, and the second port of the first reversing valve 140 is connected to the third port of the first reversing valve 140.

[0090] When the outdoor heat exchanger 120 is an evaporator, the first reversing valve 140 is in the second state, and the refrigerant flows out of the outdoor heat exchanger 120 and then flows back to the compressor 110 through the first reversing valve 140.

[0091] In some embodiments, the first directional valve 140 can be a three-way valve or a four-way valve. When the first directional valve 140 is a four-way valve, one port does not participate in the operation and is always shut off.

[0092] like Figures 1-10 As shown, the multi-split air conditioning system includes a first branch 203, one end of which is connected to the second main branch 202, and the other end of which is connected to the inlet of the compressor 110.

[0093] like Figures 1-10As shown, the multi-split air conditioning system includes a second branch 204, one end of which is connected to the second main branch 202; the second branch 204 and the first branch 203 are set independently of each other.

[0094] It should be noted that each indoor heat exchanger 210 is connected to a first main line 201 and a second main line 202, and the first main line 201 and the second main line 202 of different indoor heat exchangers 210 are set independently; correspondingly, the second branch line 204 of each indoor heat exchanger 210 is connected to a first branch line 203 and a second branch line 204, and the first branch line 203 and the second branch line 204 of different indoor heat exchangers 210 are set independently.

[0095] like Figures 1-10 As shown, the outdoor unit 100 includes a second reversing valve 150. The first port of the second reversing valve 150 is connected to the outlet of the compressor 110, the second port of the second reversing valve 150 is connected to the second branch 204, and the third port of the second reversing valve 150 is connected to the inlet of the compressor 110.

[0096] The second reversing valve 150 includes a first state. When the second reversing valve 150 is in the first state, the second reversing valve 150 is used to connect the second branch 204 with the outlet of the compressor 110. The first port of the second reversing valve 150 is connected to the second port of the second reversing valve 150, and the third port of the second reversing valve 150 is cut off.

[0097] When at least one indoor heat exchanger 210 is a condenser, the second reversing valve 150 is in the first state. Refrigerant flows from the first main line 201 into the indoor heat exchanger 210, which operates as an evaporator, and then flows back to the compressor 110 via the second main line 202 and the first branch line 203; refrigerant flows from the second main line 202 into the indoor heat exchanger 210, which operates as a condenser, and then flows into the outdoor heat exchanger 120 via the first main line 201.

[0098] In this embodiment, for ease of description, the indoor heat exchanger 210 operating as an evaporator is referred to as the indoor evaporator, and the indoor heat exchanger 210 operating as a condenser is referred to as the indoor condenser. It should be noted that "indoor evaporator" can be considered an abbreviation for "indoor heat exchanger 210 operating as an evaporator," and "indoor condenser" can be considered an abbreviation for "indoor heat exchanger 210 operating as a condenser."

[0099] The second reversing valve 150 includes a second state. When the second reversing valve 150 is in the second state, the second reversing valve 150 is used to connect the second branch 204 with the inlet of the compressor 110. The first port of the second reversing valve 150 is cut off, and the second port of the second reversing valve 150 is connected to the third port of the second reversing valve 150.

[0100] When all indoor heat exchangers 210 in the indoor unit 200 of the multi-split air conditioning system are evaporators, it can also be considered that when all indoor heat exchangers 210 in the multi-split air conditioning system are working as evaporators, the second reversing valve 150 is in the second state. The refrigerant flows into the indoor heat exchanger 210 from the first main line 201 and then flows directly into the compressor 110 from the second main line 202 through the first branch line 203, or flows into the compressor 110 through the second branch line 204 and the second reversing valve 150.

[0101] like Figures 1-10 As shown, a first shut-off valve 230 is provided on the first branch 203. The first shut-off valve 230 is used to control the opening and closing of the first branch 203. When the first shut-off valve 230 is closed, the first branch 203 is cut off. When the first shut-off valve 230 is open, the first branch 203 is opened.

[0102] like Figures 1-10 As shown, a second shut-off valve 240 is provided on the second branch 204. The second shut-off valve 240 is used to control the opening and closing of the second branch 204. When the second shut-off valve 240 is closed, the second branch 204 is cut off. When the second shut-off valve 240 is open, the second branch 204 is opened.

[0103] When the indoor heat exchanger 210 is a condenser, the first shut-off valve 230 is closed and the second shut-off valve 240 is open, that is, the first branch 203 is cut off and the second branch 204 is connected. The refrigerant flows into the indoor heat exchanger 210 from the second branch 204 and then flows to the outdoor heat exchanger 120 through the first main line 201. When the indoor heat exchanger 210 is an evaporator, at least one of the first shut-off valve 230 and the second shut-off valve 240 is open, that is, at least one of the first branch 203 and the second branch 204 is connected. The refrigerant flows into the indoor heat exchanger 210 through the first main line 201 and then flows back to the compressor 110 from the second main line 202 through the first branch 203, and / or flows back to the compressor 110 from the second main line 202 through the second branch 204 and the second reversing valve 150.

[0104] In some embodiments, the second directional valve 150 can be a three-way valve or a four-way valve. When the first directional valve 140 is a four-way valve, one port does not participate in the operation and is always shut off.

[0105] like Figures 1-10 As shown, an outdoor expansion valve 170 is provided on the first main line 201. The outdoor expansion valve 170 is used to reduce the pressure of the refrigerant flowing through the outdoor heat exchanger 120 when the outdoor heat exchanger 120 is used as an evaporator, so that the refrigerant becomes a low temperature and low pressure state so as to absorb heat in the outdoor evaporator.

[0106] like Figures 1-10As shown, an indoor expansion valve 220 is provided on the first main line 201. The indoor expansion valve 220 is used to reduce the pressure of the refrigerant flowing through the indoor heat exchanger 210 when the indoor heat exchanger 210 is used as an evaporator, so that the refrigerant becomes a low temperature and low pressure state so as to absorb heat in the indoor evaporator.

[0107] like Figure 2 As shown, the multi-split air conditioning system includes a single heating mode. In the single heating mode, the outdoor heat exchanger 120 is an evaporator, and the indoor heat exchanger 210 is a condenser. The first reversing valve 140 is in the second state, the second reversing valve 150 is in the first state, the first shut-off valve 230 is closed, and the second shut-off valve 240 is open. After being discharged from the compressor 110, the refrigerant flows through the second reversing valve 150, through the second branch 204 and the second main line 202 into the indoor heat exchanger 210 to release heat, then flows through the first main line 201 into the outdoor heat exchanger 120 to absorb heat, and finally flows back to the compressor 110 through the first reversing valve 140.

[0108] like Figure 3 As shown, the multi-split air conditioning system includes a single cooling mode. In the single cooling mode, the outdoor heat exchanger 120 is a condenser, and all indoor heat exchangers 210 involved in the operation are evaporators. At least one of the first shut-off valve 230 and the second shut-off valve 240 is open. The first reversing valve 140 is in a first state, and the second reversing valve 150 is in a second state. After being discharged from the compressor 110, the refrigerant flows into the outdoor heat exchanger 120 through the first reversing valve 140 to release heat, and then flows into the indoor heat exchanger 210 through the first main line 201 to absorb heat. Finally, it flows back to the compressor 110 through the second main line 202 and the first branch line 203, or through the second branch line 204 and the second reversing valve 150, or a portion of the refrigerant flows back to the compressor 110 through the second main line 202 and the second branch line 204, and a portion of the refrigerant flows back to the compressor 110 through the second main line 202 and the first branch line 203.

[0109] It should be noted that in a multi-split air conditioning system, in either a single heating mode or a single cooling mode, all indoor units 200 can operate, or only some indoor units 200 can operate. However, all indoor units 200 that are operating will either be cooling or heating.

[0110] like Figure 4As shown, the multi-split air conditioning system includes a first mixing mode. In the first mixing mode, the outdoor heat exchanger 120 is an evaporator, and at least one indoor heat exchanger 210 is a condenser. That is, some indoor units 200 are cooling and some are heating, with the outdoor heat exchanger acting as the evaporator. The first reversing valve 140 is in the second state, the second reversing valve 150 is in the first state, the first shut-off valve 230 on the first branch 203 connected to the indoor condenser is closed, and the second shut-off valve 240 on the second branch 204 connected to the indoor condenser is open. The first branch connected to the indoor evaporator... The first shut-off valve 230 on 203 is opened, and the second shut-off valve 240 on the second branch 204 connected to the indoor evaporator is closed. After being discharged from the compressor 110, the refrigerant flows through the second reversing valve 150, through the second branch 204 and the second main line 202 into the indoor condenser to release heat, and then flows out of the indoor condenser through the first main line 201. After the refrigerant flows out of the indoor condenser, it splits into two paths. One path flows through the first main line 201 into the outdoor heat exchanger 120, and then flows back to the compressor 110 through the first reversing valve 140. The other path flows into the indoor evaporator, and then flows back to the compressor 110 through the second main line 202 and the first branch 203.

[0111] like Figure 5 As shown, the multi-split air conditioning system includes a second mixing mode. In the second mixing mode, the outdoor heat exchanger 120 is a condenser, at least one indoor heat exchanger 210 is a condenser, and at least one indoor heat exchanger 210 is an evaporator. That is, some indoor units 200 are cooling and some indoor units 200 are heating. The first reversing valve 140 is in the first state, the second reversing valve 150 is in the first state, the first shut-off valve 230 on the first branch 203 connected to the indoor condenser is closed, and the second shut-off valve 240 on the second branch 204 connected to the indoor condenser is open; the indoor evaporator... The first shut-off valve 230 on the first branch 203 connected to the evaporator is opened, and the second shut-off valve 240 on the second branch 204 connected to the indoor evaporator is closed. After the refrigerant is discharged from the compressor 110, it is divided into two paths. One path flows through the first reversing valve 140 into the outdoor heat exchanger 120 and then into the first main path 201. The other path flows through the second reversing valve 150 from the second branch 204 into the indoor condenser and then into the first main path 201. The refrigerant flowing into the first main path 201 flows into the indoor evaporator to absorb heat, and then flows back to the compressor 110 through the second main path 202 and the first branch 203.

[0112] like Figures 1-10 As shown, the multi-split air conditioning system includes a water tank 300 for storing water; a water tank heat exchanger 310 is provided inside the water tank 300 for heating the water in the water tank 300 so that the multi-split air conditioning system can provide domestic hot water to users.

[0113] like Figures 1-10 As shown, the water tank heat exchanger 310 is connected to a third main line 301, which is connected to the outlet of the compressor 110.

[0114] like Figures 1-10 As shown, the water tank heat exchanger 310 is connected to a fourth main circuit 302, which is connected to the first main circuit 201.

[0115] like Figures 1-10 As shown, a water tank expansion valve 320 is installed on the fourth main circuit 302. The water tank expansion valve 320 is used to reduce the pressure of the refrigerant flowing through the water tank heat exchanger 310 when the water tank heat exchanger 310 is used as an evaporator, so that the refrigerant becomes a low-temperature, low-pressure state to absorb heat in the outdoor evaporator. The water tank expansion valve 320 can also control the on / off state of the fourth main circuit 302. When the water tank expansion valve 320 is closed, the fourth main circuit 302 is cut off; when the water tank expansion valve 320 is open, the fourth main circuit 302 is opened.

[0116] like Figures 1-10 As shown, the multi-split air conditioning system includes a third reversing valve 160. The first port of the third reversing valve 160 is connected to the outlet of the compressor 110, the second port of the third reversing valve 160 is connected to the third main line 301, and the third port of the third reversing valve 160 is connected to the inlet of the compressor 110.

[0117] The third directional valve 160 includes a first state. When the third directional valve 160 is in the first state, the first port of the third directional valve 160 is connected to the second port of the third directional valve 160, and the third port of the third directional valve 160 is cut off. The third directional valve 160 is used to connect the third main line 301 with the outlet of the compressor 110.

[0118] When the water tank heat exchanger 310 is a condenser, the third reversing valve 160 is in the first state. After the refrigerant is discharged from the compressor 110, it flows into the water tank heat exchanger 310 through the third reversing valve 160 to release heat, and then flows into the evaporator through the fourth main line 302 and the first main line 201.

[0119] The third directional valve 160 includes a second state. When the third directional valve 160 is in the second state, the first port of the third directional valve 160 is cut off, and the second port of the third directional valve 160 is connected to the third port of the third directional valve 160. The directional valve is used to connect the inlet of the compressor 110 with the third main line 301.

[0120] When the water tank heat exchanger 310 is an evaporator, the third reversing valve 160 is in the second state. The refrigerant flows into the water tank heat exchanger 310 through the fourth main line 302, absorbs heat, flows out of the water tank heat exchanger 310 through the third main line 301, and flows back to the compressor 110 after passing through the third reversing valve 160.

[0121] It should be noted that the water tank heat exchanger 310 is usually used as a condenser to heat the water in the water tank 300. When the water tank heat exchanger 310 is used in conjunction with the outdoor heat exchanger 120 for defrosting, the water tank heat exchanger 310 acts as an evaporator.

[0122] In some embodiments, the third directional valve 160 can be a three-way valve or a four-way valve. When the first directional valve 140 is a four-way valve, one port does not participate in the operation and is always shut off.

[0123] The following section uses a multi-split air conditioning system, consisting of three indoor units 200 and a water tank 300, as an example to detail the refrigerant flow of the multi-split air conditioning system under different operating modes when the water tank 300 provides hot water.

[0124] For ease of description, the three indoor units 200 are referred to as the first indoor unit 200, the second indoor unit 200, and the third indoor unit 200; the indoor heat exchangers 210 of the first indoor unit 200, the second indoor unit 200, and the third indoor unit 200 are referred to as the first indoor heat exchanger 211, the second indoor heat exchanger 212, and the third indoor heat exchanger 213; the indoor expansion valve 220 corresponding to the first indoor heat exchanger 211 is the first indoor expansion valve 221, the indoor expansion valve 220 corresponding to the second indoor heat exchanger 212 is the second indoor expansion valve 222, and the indoor expansion valve 220 corresponding to the third indoor heat exchanger 213 is the third indoor expansion valve 223.

[0125] like Figure 2 As shown, all indoor units 200 are in heating mode, i.e., the outdoor heat exchanger 120 is an evaporator, and the first indoor heat exchanger 211, the second indoor heat exchanger 212 and the third indoor heat exchanger 213 are all condensers. The first reversing valve 140 is in the second state, the second reversing valve 150 is in the first state, the third reversing valve 160 is in the first state, the first shut-off valve 230 is closed and the second shut-off valve 240 is open.

[0126] After being discharged from the compressor 110, the refrigerant is split into two paths. One path flows through the third reversing valve 160 into the water tank heat exchanger 310, where it condenses and releases heat to heat the water in the water tank 300, and then flows into the first main path 201. The other path flows through the second reversing valve 150 from the second branch path 204 through the second main path 202 into the indoor heat exchanger 210 to release heat and heat the room, and then flows into the first main path 201. The refrigerant flowing into the first main path 201 continues to flow in the first main path 201, passes through the outdoor expansion valve 170 for throttling, and then flows into the outdoor heat exchanger 120 to absorb heat. In the outdoor heat exchanger 120, it evaporates and absorbs heat to form a low-pressure gaseous refrigerant, which then flows back to the compressor 110 through the first reversing valve 140.

[0127] like Figure 3As shown, all indoor units 200 are used for cooling, that is, all indoor heat exchangers 210 are evaporators and outdoor heat exchangers 120 are condensers. At this time, the first reversing valve 140 is in the first state, the second reversing valve 150 is in the second state, the third reversing valve 160 is in the first state, and at least one of the first shut-off valve 230 and the second shut-off valve 240 is open.

[0128] After being discharged from the compressor 110, the refrigerant is split into two streams. One stream flows through the third reversing valve 160 into the water tank heat exchanger 310, where it condenses and releases heat to heat the water in the water tank 300, and then flows into the first main stream 201. The other stream flows through the first reversing valve 140 into the outdoor heat exchanger 120, where it releases heat before flowing into the first main stream 201. The refrigerant flowing into the first main stream 201 passes through the outdoor expansion valve 170 and then through the first indoor expansion valve 221, the second indoor expansion valve 222, and the third indoor expansion valve 223, before flowing into the first indoor heat exchanger 211, the second indoor heat exchanger 212, and the third indoor heat exchanger 213, where it evaporates and absorbs heat to cool the room, forming a low-pressure gaseous refrigerant. Then, a portion of the refrigerant flows back to the compressor 110 through the second main stream 202 from the second branch 204 via the second reversing valve 150, and another portion flows back to the compressor 110 through the second main stream 202 from the first branch 203.

[0129] like Figure 4 As shown, the outdoor heat exchanger 120 is an evaporator, the first indoor heat exchanger 211 and the second indoor heat exchanger 212 are condensers, and the third indoor heat exchanger 213 is an evaporator. The first reversing valve 140 is in the second state, the second reversing valve 150 is in the first state, and the third reversing valve 160 is in the first state. The first shut-off valve 230 on the first branch 203 connecting the first indoor heat exchanger 211 and the second indoor heat exchanger 212 is closed, and the second shut-off valve 240 on the second branch 204 connecting the first indoor heat exchanger 211 and the second indoor heat exchanger 212 is open. The first shut-off valve 230 on the first branch 203 connecting the third indoor heat exchanger 213 is open, and the second shut-off valve 240 on the second branch 204 connecting the third indoor heat exchanger 213 is closed.

[0130] After being discharged from compressor 110, the refrigerant is split into two paths. One path flows through the third reversing valve 160 into the water tank heat exchanger 310, where it condenses and releases heat to heat the water in water tank 300, and then flows into the first main path 201. The other path flows through the second reversing valve 150, through the second branch path 204 corresponding to the first indoor heat exchanger 211 and the second indoor heat exchanger 212, and the second main path 202, where it releases heat. Then, the refrigerant flows from the first main path 201... The refrigerant flowing into the first main line 201 from the first indoor heat exchanger 211 and the second indoor heat exchanger 212 is split into two streams. One stream flows through the first main line 201 into the outdoor heat exchanger 120, and then flows back to the compressor 110 through the first reversing valve 140. The other stream flows into the third indoor heat exchanger 213 to evaporate and absorb heat, cooling the room. After forming a low-pressure gaseous refrigerant, it flows back to the compressor 110 through the second main line 202 and the first branch line 203.

[0131] like Figure 5 As shown, the outdoor heat exchanger 120 is a condenser, the first indoor heat exchanger 211 is a condenser, and the second indoor heat exchanger 212 and the third indoor heat exchanger 213 are evaporators. The first reversing valve 140, the second reversing valve 150, and the third reversing valve 160 are all in the first state. The first shut-off valve 230 on the first branch 203 connected to the first indoor heat exchanger 211 is closed, and the second shut-off valve 240 on the second branch 204 connected to the first indoor heat exchanger 211 is open. The first shut-off valve 230 on the first branch 203 connected to the second indoor heat exchanger 212 and the third indoor heat exchanger 213 is open. The second shut-off valve 240 on the second branch 204 connecting the heat exchanger 212 and the third indoor heat exchanger 213 is closed; the refrigerant discharged from the compressor 110 is divided into three paths: the first path flows into the outdoor heat exchanger 120 through the first reversing valve 140 and then into the first main path 201; the second path flows into the indoor condenser through the second branch 204 through the second reversing valve 150 and then into the first main path 201; the third path flows into the water tank heat exchanger 310 through the third reversing valve 160 and then into the first main path 201; the refrigerant flowing into the first main path 201 flows into the indoor evaporator to absorb heat, and then flows back to the compressor 110 through the second main path 202 and the first branch 203.

[0132] It should be noted that, in this embodiment, there are three indoor units 200. When the multi-split air conditioning system is running in the first hybrid mode, two indoor units 200 are used for heating. Therefore, in this embodiment, the first hybrid mode is mainly for heating. When the multi-split air conditioning system is running in the second hybrid mode, two indoor units 200 are used for cooling. Therefore, in this embodiment, the second hybrid mode is mainly for cooling.

[0133] When the outdoor heat exchanger 120 is working as an evaporator, the surface of the outdoor heat exchanger 120 is prone to frost formation. In this application, the outdoor heat exchanger 120 is made to work as a condenser, and the water tank heat exchanger 310 and / or the indoor heat exchanger 210 are made to work as evaporators in conjunction with the outdoor heat exchanger 120, so that the refrigerant can defrost the outdoor heat exchanger 120.

[0134] In this application, when the outdoor heat exchanger 120 operates as an evaporator, the multi-split air conditioning system is in a single heating mode or a first mixed mode.

[0135] The following section uses the above-mentioned multi-split air conditioning system, which includes three indoor units 200 and one water tank 300, as an example to introduce the defrosting methods of the multi-split air conditioning system in single heating mode or first mixing mode.

[0136] In single heating mode, the multi-split air conditioning system can use the cooperation of the water tank heat exchanger 310 and the outdoor heat exchanger 120 to defrost, so as to avoid lowering the indoor ambient temperature when the indoor heat exchanger 210 is working as an evaporator.

[0137] Specifically, such as Figure 6 As shown, the first shut-off valve 230 and the second shut-off valve 240 are closed, the first reversing valve 140 is in the first state, and the third reversing valve 160 is in the second state. After the refrigerant is discharged from the compressor 110, it enters the outdoor heat exchanger 120 through the first reversing valve 140, condenses and releases heat to defrost the outdoor heat exchanger 120, forming liquid refrigerant that flows back and then flows into the third main line 301 through the first main line 201. After passing through the water tank expansion valve 320, it enters the water tank heat exchanger 310, where it evaporates and absorbs heat to cool the water in the water tank 300, forming low-pressure gaseous refrigerant that flows back and then flows back to the compressor 110 through the third reversing valve 160.

[0138] When a user has a hot water demand, if the water tank heat exchanger 310 is used as an evaporator in conjunction with the outdoor heat exchanger 120 for defrosting, the water temperature in the water tank 300 will decrease and will not meet the user's hot water demand. In this case, the indoor heat exchanger 210 is used in conjunction with the outdoor heat exchanger 120 for defrosting.

[0139] Specifically, such as Figure 7As shown, the first reversing valve 140 is in the first state and the second reversing valve 150 is in the second state. After being discharged from the compressor 110, the refrigerant flows through the first reversing valve 140 into the outdoor heat exchanger 120 to release heat, and then flows through the first main line 201 into the indoor heat exchanger 210 to absorb heat. Finally, it flows back to the compressor 110 through the second main line 202 and the first branch line 203, or through the second branch line 204 and the second reversing valve 150. Alternatively, some refrigerant flows back to the compressor 110 through the second main line 202 and the second branch line 204, and some refrigerant flows back to the compressor 110 through the second main line 202 and the first branch line 203.

[0140] It should be noted that at this time, the multi-split air conditioning system is actually in single cooling mode.

[0141] In some embodiments of this application, under a single heating mode, the defrosting control logic of the outdoor unit 100 is as follows: Every two minutes, the system collects the water temperature TDHW(n) in the water tank 300. First, it determines whether TDHW(n) is greater than 50°C. If so, it indicates that the water tank 300 has enough stored heat to meet domestic hot water needs and also for defrosting. Therefore, defrosting of the water tank 300 is performed at this time. If not, it determines whether the water temperature in the water tank 300 is within the range of 30 to 50°C and whether the difference between the previous water temperature TDHW(n) and the current water temperature TDHW(n) is greater than 5°C. If so, it indicates that the water tank 300 has enough stored heat. If there is a lot of stored heat but the demand for domestic hot water is high, the heat stored in water tank 300 cannot be consumed, and indoor unit 200 should be used for defrosting. However, if the water temperature in water tank 300 is between 30 and 50°C, but the difference between the previous water temperature TDHW(n) and the current water temperature TDHW(n) is less than 5°C, it means that there is a lot of stored heat in water tank 300 and the demand for domestic hot water is not high, so water tank 300 can be used for defrosting. If the water temperature TDHW(n) in water tank 300 is less than 30°C, it means that there is insufficient stored heat in water tank 300, and the heat stored in water tank 300 cannot be consumed, so indoor unit 200 should be used for defrosting.

[0142] When the multi-split air conditioning system is running in the first mixed mode, since the third indoor heat exchanger 213 is an evaporator, it is used in conjunction with the outdoor heat exchanger 120 for defrosting.

[0143] like Figure 8As shown, the water tank expansion valve 320 is closed, the first reversing valve 140 is in the first state, and the second reversing valve 150 is in the second state. After being discharged from the compressor 110, the refrigerant flows through the first reversing valve 140 into the outdoor heat exchanger 120 to release heat, and then flows through the first main line 201 into the indoor heat exchanger 210 to absorb heat. Finally, it flows back to the compressor 110 through the second main line 202 and the first branch line 203, or through the second branch line 204 and the second reversing valve 150. Alternatively, some refrigerant flows back to the compressor 110 through the second main line 202 and the second branch line 204, and some refrigerant flows back to the compressor 110 through the second main line 202 and the first branch line 203.

[0144] If the capacity of the indoor cooling unit 200 cannot meet the defrosting requirements and the user has no domestic hot water needs, the water tank 300 and the third indoor heat exchanger 213 are used in conjunction with the outdoor heat exchanger 120 to allow the refrigerant to defrost the outdoor heat exchanger 120.

[0145] Specifically, such as Figure 9 As shown, the first shut-off valve 230 is open, the second shut-off valve 240 is closed, the first reversing valve 140 is in the first state, and the third reversing valve 160 is in the second state. After the refrigerant is discharged from the compressor 110, it enters the outdoor heat exchanger 120 through the first reversing valve 140 to release heat, and then flows into the first main line 201 and is split into two lines in the first main line 201. One line flows into the water tank heat exchanger 310, and then flows back to the compressor 110 through the third main line 301 and the third reversing valve 160; the other line flows into the third indoor heat exchanger 213 and flows back to the compressor 110 through the first main line 201 and the first branch line 203.

[0146] When a user has a hot water demand, if the water tank heat exchanger 310 is used as an evaporator in conjunction with the outdoor heat exchanger 120 for defrosting, the water temperature in the water tank 300 will decrease and will not meet the user's hot water demand. However, using only the indoor cooling unit 200 cannot meet the defrosting requirements of the outdoor heat exchanger 120. In this case, all indoor heat exchangers 210 are used in conjunction with the outdoor heat exchanger 120 for defrosting.

[0147] like Figure 10As shown, the water tank expansion valve 320 is closed, the first reversing valve 140 is in the first state, and the second reversing valve 150 is in the second state. After being discharged from the compressor 110, the refrigerant flows through the first reversing valve 140 into the outdoor heat exchanger 120 to release heat, and then flows through the first main line 201 into the indoor heat exchanger 210 to absorb heat. Finally, it flows back to the compressor 110 through the second main line 202 and the first branch line 203, or through the second branch line 204 and the second reversing valve 150. Alternatively, some refrigerant flows back to the compressor 110 through the second main line 202 and the second branch line 204, and some refrigerant flows back to the compressor 110 through the second main line 202 and the first branch line 203.

[0148] It should be noted that at this time, the multi-split air conditioning system is actually in single cooling mode.

[0149] In some embodiments of this application, in the first hybrid mode, the defrosting control logic of the outdoor unit 100 is as follows: Every two minutes, the system collects the water temperature TDHW(n) in the water tank 300. First, it determines whether the capacity of the cooling indoor unit 200 is greater than or equal to the capacity required for defrosting. If so, the cooling indoor unit 200 is used directly for defrosting. Then, it determines whether TDHW(n) is greater than 50°C. If so, it means that the heat stored in the water tank 300 is sufficient to meet the domestic hot water demand and can also be used for defrosting. Therefore, defrosting of the water tank 300 and the cooling indoor unit 200 is performed at this time. If not, it determines whether the water in the water tank 300 is within the range of 30 to 50°C and whether the previous water temperature TDHW(n) is different from the current water temperature TDHW(n). If the difference between the water temperature TDHW(n) and the current water temperature TDHW(n) is greater than 5℃, it indicates that the water tank 300 stores a lot of heat but the demand for domestic hot water is high. In this case, the heat in the water tank 300 cannot be consumed, and all indoor units 200 should be defrosted. However, if the water temperature in the water tank 300 is in the range of 30 to 50℃, but the difference between the previous water temperature TDHW(n) and the current water temperature TDHW(n) is less than 5℃, it indicates that the water tank 300 stores a lot of heat and the demand for domestic hot water is not high. In this case, the water tank 300 and the cooling indoor units 200 can be defrosted. If the water temperature TDHW(n) in the water tank 300 is less than 30℃, it indicates that the heat stored in the water tank 300 is insufficient. In this case, the heat in the water tank 300 cannot be consumed, and all indoor units 200 should be defrosted.

[0150] It should be noted that the working principles of the indoor expansion valve 220, the outdoor expansion valve 170, and the water tank expansion valve 320, as well as their mechanisms of action on the refrigerant, the location of the refrigerant in the gas phase and the location of the refrigerant in the liquid phase during the circulation process, and the high-pressure and low-pressure states of the refrigerant in which pipelines, are common knowledge in the field and will not be elaborated upon in this application.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0152] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A multi-split air conditioning system, characterized in that, include: compressor; Outdoor heat exchanger; A first reversing valve is connected to the outlet of the compressor, the inlet of the compressor, and the outdoor heat exchanger; in a first state, the first reversing valve connects the outdoor heat exchanger to the outlet of the compressor; in a second state, the first reversing valve connects the inlet of the compressor to the outdoor heat exchanger. The room heat exchanger is configured in multiple ways, and the multiple room heat exchangers are configured independently of each other; each room heat exchanger is connected to a first main line and a second main line, and the first main line is connected to the outdoor heat exchanger. The first branch, one end of which is connected to the second main branch, and the other end of which is connected to the inlet of the compressor; The second branch road, one end of which is connected to the second main road; The second reversing valve is connected to the outlet of the compressor, the inlet of the compressor, and the end of the second branch away from the second main branch; in the first state, the second reversing valve connects the second branch to the outlet of the compressor; in the second state, the second reversing valve connects the second branch to the inlet of the compressor. A first shut-off valve is provided on the first branch and is used to control the opening and closing of the first branch; The second shut-off valve is located on the second branch and is used to control the opening and closing of the second branch; When the indoor heat exchanger is a condenser, the first shut-off valve is closed and the second shut-off valve is open. The refrigerant flows into the indoor heat exchanger from the second branch and then flows to the outdoor heat exchanger through the first main branch. When the indoor heat exchanger is an evaporator, at least one of the first shut-off valve and the second shut-off valve is open. The refrigerant flows into the indoor heat exchanger through the first main line, then flows back to the compressor through the first branch line from the second main line, and / or flows back to the compressor through the second branch line and the second reversing valve from the second main line.

2. The multi-split air conditioning system according to claim 1, characterized in that, When at least one of the indoor heat exchangers in the operating indoor unit is a condenser, the second reversing valve is in the first state; when all the indoor heat exchangers in the operating indoor unit are evaporators, the second reversing valve is in the second state.

3. The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system includes a single heating mode. In the single heating mode, the outdoor heat exchanger is an evaporator and the indoor heat exchanger is a condenser. The first shut-off valve is closed and the second shut-off valve is open. The first reversing valve is used to connect the outdoor heat exchanger to the inlet of the compressor. The second reversing valve is used to connect the second branch to the outlet of the compressor.

4. The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system includes a single cooling mode, in which the outdoor heat exchanger is a condenser and the indoor heat exchanger is an evaporator. At least one of the first shut-off valve and the second shut-off valve is open, and the first reversing valve is used to connect the outlet of the compressor with the outdoor heat exchanger; When the second shut-off valve is open, the second reversing valve is used to connect the second branch to the outlet of the compressor.

5. The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system includes a first mixing mode, in which the outdoor heat exchanger is an evaporator, at least one indoor heat exchanger is a condenser, and at least one indoor heat exchanger is an evaporator; the first reversing valve is used to connect the outdoor heat exchanger to the inlet of the compressor; the second reversing valve is used to connect the second branch to the outlet of the compressor; The first shut-off valve is open and the second shut-off valve is closed for the indoor heat exchanger that serves as an evaporator; the first shut-off valve is closed and the second shut-off valve is open for the indoor heat exchanger that serves as a condenser.

6. The multi-split air conditioning system according to claim 1, characterized in that, The multi-split air conditioning system includes a second mixing mode, in which the outdoor heat exchanger is a condenser, at least one indoor heat exchanger is a condenser, and at least one indoor heat exchanger is an evaporator; the first reversing valve is used to connect the outlet of the compressor to the outdoor heat exchanger; the second reversing valve is used to connect the second branch to the outlet of the compressor; The first shut-off valve is open and the second shut-off valve is closed for the indoor heat exchanger that serves as an evaporator; the first shut-off valve is closed and the second shut-off valve is open for the indoor heat exchanger that serves as a condenser.

7. The multi-split air conditioning system according to claim 1, characterized in that, It also includes a water tank, which contains a water tank heat exchanger. One interface of the water tank heat exchanger is connected to a third main circuit, and the other end of the third main circuit is connected to the outlet of the compressor. The other interface of the water tank heat exchanger is connected to a fourth main circuit, and the other end of the fourth main circuit is connected to the first main circuit.

8. The multi-split air conditioning system according to claim 7, characterized in that, It also includes a third reversing valve, which is connected to the outlet of the compressor, the inlet of the compressor and the third main line. The third reversing valve is used to switch the flow direction of refrigerant through the water tank heat exchanger.

9. The multi-split air conditioning system according to claim 8, characterized in that, The third reversing valve includes a first state and a second state. When the third reversing valve is in the first state, it is used to connect the third main circuit with the outlet of the compressor. When the third reversing valve is in the second state, it is used to connect the inlet of the compressor with the third main circuit. When the water tank heat exchanger is a condenser, the third reversing valve is in the first state; when the water tank heat exchanger is an evaporator, the third reversing valve is in the second state.

10. A multi-split air conditioning system, comprising: Outdoor unit, which includes: compressor; Outdoor heat exchanger; A first reversing valve is connected to the outlet of the compressor, the inlet of the compressor, and the outdoor heat exchanger; Multiple indoor units are configured, and the multiple indoor units are independently configured; each indoor unit includes: An indoor heat exchanger is connected to a first main line and a second main line, the first main line being connected to the outdoor heat exchanger. The multi-split air conditioning system is characterized in that it further includes: The first branch, one end of which is connected to the second main branch, and the other end of which is connected to the inlet of the compressor; The second branch road, one end of which is connected to the second main road; The second reversing valve is connected to the outlet of the compressor, the inlet of the compressor, and the end of the second branch away from the second main branch; When the indoor heat exchanger is a condenser, the first branch is cut off and the second branch is connected. The refrigerant flows into the indoor heat exchanger from the second branch and then flows to the outdoor heat exchanger through the first main branch. When the indoor heat exchanger is an evaporator, at least one of the first branch and the second branch is connected. After the refrigerant flows into the indoor heat exchanger through the first main branch, it flows back to the compressor through the second main branch and / or flows back to the compressor through the second main branch and the second reversing valve.

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