Multi-split air conditioning system and its control method

Abstract

This disclosure provides a multi-split air conditioning system and its control method, relating to the field of air conditioning technology, to avoid high-pressure protection alarms and shutdowns of the multi-split air conditioning system after refrigerant recovery. The multi-split air conditioning system includes multiple outdoor units, multiple indoor units, refrigerant gas pipes, refrigerant liquid pipes, gas-side refrigerant shut-off valves, liquid-side refrigerant shut-off valves, a refrigerant concentration sensor, and a controller. The outdoor units include a compressor, a four-way valve, an outdoor unit heat exchanger, and an outdoor unit expansion valve. The controller is used to recover refrigerant to the outdoor units based on the refrigerant concentration in the room where the first indoor unit is located. The multiple outdoor units include at least one first outdoor unit, which includes a one-way valve. The one-way valve, in cooperation with the outdoor unit expansion valve of the first outdoor unit, seals the recovered refrigerant in the outdoor unit heat exchanger of the first outdoor unit. The above-mentioned multi-split air conditioning system is used to regulate air temperature. The above-mentioned control method is used in the multi-split air conditioning system.

Description

Technical Field

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

[0002] Air conditioning systems require refrigerant circulation during operation. In an air conditioning unit, one or more outdoor units and one or more indoor units are connected via piping, forming a refrigerant (e.g., R410a) circuit. Due to environmental regulations, existing refrigerants are being replaced by those with lower global warming potential, such as R32. However, R32 refrigerant has higher flammability than R410a, posing certain risks when used in existing air conditioning systems. In the event of an R32 refrigerant leak, there is a potential for fire or explosion. Summary of the Invention

[0003] The purpose of this disclosure is to provide a multi-split air conditioning system and its control method to avoid the occurrence of high-pressure protection alarm shutdown of the multi-split air conditioning system after refrigerant recovery.

[0004] To achieve the above objectives, the embodiments of this disclosure provide the following technical solutions:

[0005] On one hand, a multi-split air conditioning system is provided. The multi-split air conditioning system includes multiple outdoor units, multiple indoor units, refrigerant gas pipes, refrigerant liquid pipes, a gas-side refrigerant shut-off valve, a liquid-side refrigerant shut-off valve, a refrigerant concentration sensor, and a controller. Each outdoor unit includes a compressor, a four-way valve, an outdoor unit heat exchanger, and an outdoor unit expansion valve. Each of the multiple indoor units includes a first indoor unit. The four-way valve is used to adjust the flow direction of the refrigerant within the multi-split air conditioning system when switching operating modes. The refrigerant gas pipe connects the four-way valve to the first end of the indoor unit. The refrigerant liquid pipe connects the outdoor unit expansion valve to the second end of the indoor unit. The gas-side refrigerant shut-off valve is located between the first end of the indoor unit and the refrigerant gas pipe. The liquid-side refrigerant shut-off valve is located between the second end of the indoor unit and the refrigerant liquid pipe. The refrigerant concentration sensor is located in the first indoor unit and is used to detect the refrigerant concentration in the room where the first indoor unit is located. The controller is coupled to the refrigerant concentration sensor and is used to recover refrigerant to the outdoor unit based on the refrigerant concentration in the room where the first indoor unit is located. The plurality of outdoor units includes at least one first outdoor unit, which includes a one-way valve disposed between the compressor outlet and the four-way valve. This one-way valve, in cooperation with the outdoor unit expansion valve of the first outdoor unit, seals the recovered refrigerant in the outdoor unit heat exchanger of the first outdoor unit.

[0006] The multi-split air conditioning system provided in this disclosure isolates the first indoor unit experiencing refrigerant leakage from the rest of the system by installing a gas-side refrigerant shut-off valve and a liquid-side refrigerant shut-off valve. By installing a one-way valve between the compressor outlet and the four-way valve in at least one first outdoor unit, the outdoor unit expansion valve can be closed when refrigerant from the multi-split air conditioning system is recovered to the outdoor unit's heat exchanger, thereby isolating a portion of the refrigerant in the outdoor unit's heat exchanger. Therefore, it avoids the situation where the refrigerant capacity in the remaining indoor and outdoor units is mismatched with the standard capacity of the multi-split air conditioning system, preventing high-pressure protection alarms and system shutdowns. This allows the remaining indoor and outdoor units to return to normal operation, improving the user experience.

[0007] In some embodiments, the step of recovering refrigerant to the outdoor unit based on the refrigerant concentration in the room where the first indoor unit is located includes: acquiring the refrigerant concentration value detected by the refrigerant concentration sensor, comparing the refrigerant concentration value with a preset concentration value; and if the refrigerant concentration value in the room where the first indoor unit is located is greater than the preset concentration value, closing the liquid-side refrigerant shut-off valve and controlling the compressor of the outdoor unit to work, so as to recover the refrigerant to the outdoor unit.

[0008] In some embodiments, before closing the liquid-side refrigerant shut-off valve when the refrigerant concentration value in the room where the first indoor unit is located is greater than the preset concentration value, the controller is further configured to: determine the operating mode of the multi-split air conditioning system; when the operating mode of the multi-split air conditioning system is non-cooling mode, adjust the operating mode of the multi-split air conditioning system to cooling mode and run it for a seconds, and control the fans of the indoor unit heat exchanger and the outdoor unit heat exchanger to run at the highest speed; where a is a constant.

[0009] In some embodiments, the controller is further configured to: after recovering refrigerant to the outdoor unit, close the gas-side refrigerant shut-off valve between the first indoor unit and the refrigerant gas pipe, and open the liquid-side refrigerant shut-off valve between each indoor unit other than the first indoor unit and the refrigerant liquid pipe; obtain the ratio between the capacity of the first indoor unit and the total capacity of the outdoor unit, and compare the ratio with a preset ratio; if the ratio is greater than or equal to the preset ratio, close the outdoor unit expansion valve of the first outdoor unit.

[0010] In some embodiments, the four-way valve includes: a first port connected to the refrigerant gas pipe, a second port connected to the compressor inlet, a third port connected to one end of the outdoor unit heat exchanger, and a fourth port connected to the compressor outlet. The other end of the outdoor unit heat exchanger is connected to the refrigerant liquid pipe via the outdoor unit expansion valve. The outdoor unit also includes: a suction pressure sensor disposed between the compressor inlet and the second port, and coupled to the controller; the suction pressure sensor is used to detect the suction pressure of the compressor.

[0011] In some embodiments, the outdoor unit further includes: an exhaust temperature sensor and a liquid-side refrigerant temperature sensor. The exhaust temperature sensor is disposed at the exhaust port of the compressor and coupled to the controller; the exhaust temperature sensor is used to detect the exhaust temperature of the compressor. The liquid-side refrigerant temperature sensor is disposed between the expansion valve of the outdoor unit and the refrigerant liquid pipe and coupled to the controller; the liquid-side refrigerant temperature sensor is used to detect the temperature of the refrigerant between the expansion valve of the outdoor unit and the refrigerant liquid pipe. The controller is further configured to: after closing the expansion valve of the first outdoor unit, acquire the exhaust temperature and the subcooling degree of the liquid-side refrigerant shut-off valve of other outdoor units besides the first outdoor unit; if the exhaust temperature of other outdoor units besides the first outdoor unit is greater than a preset exhaust temperature and the holding time is less than a first time, or if the subcooling degree of the liquid-side refrigerant shut-off valve of other outdoor units besides the first outdoor unit is less than or equal to a preset subcooling degree and the holding time is less than the first time, open the compressor of the first outdoor unit and hold it for a second time, adjust the opening value of the expansion valve of the first outdoor unit to a target opening value and hold it for the second time. Wherein, the subcooling degree of the liquid-side refrigerant shut-off valve of any of the outdoor units is the value of the saturation temperature of the outdoor unit under the exhaust pressure minus the temperature of the liquid-side refrigerant shut-off valve.

[0012] In some embodiments, the four-way valve includes: a first port connected to the refrigerant gas pipe, a second port connected to the compressor inlet, a third port connected to one end of the outdoor unit heat exchanger, and a fourth port connected to the compressor outlet. The other end of the outdoor unit heat exchanger is connected to the refrigerant liquid pipe via the outdoor unit expansion valve. The outdoor unit also includes: an exhaust temperature sensor and a liquid-side refrigerant temperature sensor. The exhaust temperature sensor is located at the compressor exhaust port and coupled to the controller; the exhaust temperature sensor is used to detect the compressor exhaust temperature. The liquid-side refrigerant temperature sensor is located between the outdoor unit expansion valve and the refrigerant liquid pipe and coupled to the controller; the liquid-side refrigerant temperature sensor is used to detect the temperature of the refrigerant between the outdoor unit expansion valve and the refrigerant liquid pipe. The first outdoor unit also includes: a refrigerant replenishment device. One end of the refrigerant replenishment device is connected to the fourth port, and the other end is connected to the second port; the refrigerant replenishment device is coupled to the controller. The controller is further configured to: after closing the expansion valve of the first outdoor unit, acquire the exhaust temperature and liquid-side refrigerant shut-off valve subcooling of other outdoor units besides the first outdoor unit; if the exhaust temperature of other outdoor units besides the first outdoor unit is greater than a preset exhaust temperature and the holding time is less than a first time, or if the liquid-side refrigerant shut-off valve subcooling of other outdoor units besides the first outdoor unit is less than or equal to a preset subcooling and the holding time is less than the first time, turn on the compressor of the first outdoor unit and hold it for a third time, and turn on the refrigerant replenishment device and hold it for the third time. Wherein, the liquid-side refrigerant shut-off valve subcooling of any of the outdoor units is the saturation temperature at the exhaust pressure of the outdoor unit minus the liquid-side refrigerant shut-off valve temperature.

[0013] In some embodiments, the refrigerant replenishment device includes: a solenoid valve and a capillary tube connected in series; the solenoid valve is coupled to the controller. The controller is further configured to: open the solenoid valve when it is necessary to open the refrigerant replenishment device.

[0014] On the other hand, this disclosure also provides a control method for a multi-split air conditioning system. The control method includes acquiring a refrigerant concentration value detected by a refrigerant concentration sensor and comparing the refrigerant concentration value with a preset concentration value; if the refrigerant concentration value in the room where the first indoor unit is located is greater than the preset concentration value, closing the liquid-side refrigerant shut-off valve between the multiple indoor units and the refrigerant liquid pipe, and controlling the compressors of the multiple outdoor units to operate to recover refrigerant into the outdoor units; after recovering the refrigerant into the outdoor units, closing the gas-side refrigerant shut-off valve between the first indoor unit and the refrigerant gas pipe, opening the liquid-side refrigerant shut-off valves between the indoor units other than the first indoor unit and the refrigerant liquid pipe; and closing the outdoor unit expansion valve of the first outdoor unit.

[0015] In some embodiments, closing the outdoor unit expansion valve of the first outdoor unit includes: obtaining a ratio between the capacity of the first indoor unit and the total capacity of the outdoor unit, comparing the ratio with a preset ratio; and closing the outdoor unit expansion valve of the first outdoor unit if the ratio is greater than or equal to the preset ratio. After closing the outdoor unit expansion valve of the first outdoor unit, the control method further includes: obtaining the exhaust temperature and liquid-side refrigerant shut-off valve subcooling of other outdoor units besides the first outdoor unit; and adjusting the opening value of the outdoor unit expansion valve of the first outdoor unit to a target opening and maintaining it for a second time, or opening the refrigerant replenishment device and maintaining it for a third time, if the exhaust temperature of other outdoor units besides the first outdoor unit is less than or equal to a preset exhaust temperature and the holding time is less than a first time, or if the liquid-side refrigerant shut-off valve subcooling of other outdoor units besides the first outdoor unit is greater than a preset subcooling and the holding time is less than the first time. Wherein, the liquid-side refrigerant shut-off valve subcooling of any outdoor unit is the value of the saturation temperature under the exhaust pressure of the outdoor unit minus the liquid-side refrigerant shut-off valve temperature.

[0016] The control method for the multi-split air conditioning system described above has the same structure and beneficial technical effects as the multi-split air conditioning system provided in some of the above embodiments, and will not be repeated here. Attached Figure Description

[0017] 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 intended to limit the actual size of the product, the actual process of the method, etc. involved in the embodiments of this disclosure.

[0018] Figure 1 This is a structural diagram of an air conditioning system in related technologies;

[0019] Figure 2a This is a structural diagram of a multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0020] Figure 2b This is a structural diagram of another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0021] Figure 3a This is a refrigerant flow diagram of a multi-split air conditioning system according to some embodiments of the present disclosure;

[0022] Figure 3bThis is a refrigerant flow diagram for another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0023] Figure 3c This is a refrigerant flow diagram for yet another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0024] Figure 4a This is a structural diagram of yet another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0025] Figure 4b This is a refrigerant flow diagram for yet another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0026] Figure 4c This is a refrigerant flow diagram for yet another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0027] Figure 5 This is a structural diagram of yet another multi-split air conditioning system provided according to some embodiments of the present disclosure;

[0028] Figure 6 This is a flowchart of a control method for a multi-split air conditioning system provided according to some embodiments of the present disclosure. Detailed Implementation

[0029] The technical solutions in some 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. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0030] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are 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 embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with this 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.

[0031] Hereinafter, 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0032] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0033] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0034] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0035] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0036] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0037] To facilitate understanding, a brief introduction and explanation of some terms or basic concepts of technology involved in the embodiments of this disclosure will be given first.

[0038] Refrigerant: A substance that easily absorbs heat and turns into a gas, and easily releases heat and turns into a liquid. In air conditioning systems, heat energy is transferred through the evaporation and condensation of the refrigerant to produce a cooling or heating effect.

[0039] Expansion valve: It consists of two parts, a valve body and a coil, and is used for throttling and pressure reduction and for regulating flow.

[0040] Indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioning system acts as a heater in heating mode; when it is used as an evaporator, the air conditioning system acts as a cooler in cooling mode.

[0041] In related technologies, such as Figure 1As shown, a refrigerant concentration sensor 2' is installed on one side of the indoor unit 1'. When the refrigerant concentration sensor 2' detects that the indoor refrigerant concentration exceeds the standard, the air conditioning system enters the cooling operation mode to recover the refrigerant. First, the liquid-side refrigerant shut-off valve 3' is closed, and the compressor 4' recovers the refrigerant to the outdoor unit heat exchanger 5' and gas-liquid separator 6'. After the recovery is completed, the gas-side refrigerant shut-off valve 7' is closed. At this point, the refrigerant recovery in the indoor unit 1' and the refrigerant pipeline is complete.

[0042] However, in multi-split air conditioning systems, because multiple indoor units are connected, even if the refrigerant in one leaking indoor unit is evacuated, the other indoor and outdoor units can still operate normally. In this case, if the evacuated indoor unit contains too much refrigerant, it will cause a mismatch between the refrigerant capacity and the standard capacity of the multi-split air conditioning system. This can easily trigger a high-pressure protection alarm and shutdown, causing even the indoor units that did not leak to malfunction, thus affecting the user experience.

[0043] Based on this, such as Figure 2a As shown, some embodiments of this disclosure provide a multi-split air conditioning system 100. The multi-split air conditioning system 100 includes: multiple outdoor units 1, multiple indoor units 2, refrigerant gas pipes 3, refrigerant liquid pipes 4, gas-side refrigerant shut-off valves 5 and liquid-side refrigerant shut-off valves 6.

[0044] Understandably, there are also pipes between multiple components to allow them to connect with each other.

[0045] For example, in a multi-split air conditioning system 100, the number of outdoor units 1 can be two, three, or four, etc. The number of indoor units 2 can be two, three, or four, etc.

[0046] For example, multiple outdoor units 1 are connected in parallel, and multiple indoor units 2 are connected in parallel. In this way, the operating status of each outdoor unit 1 and each indoor unit 2 can be independent of each other and is not affected by the operating status of other outdoor units 1 or indoor units 2.

[0047] It is understandable that the more outdoor units 1 and indoor units 2 there are, the more refrigerant is contained in the multi-split air conditioning system 100.

[0048] In some examples, such as Figure 2a As shown, outdoor unit 1 includes: compressor 11, four-way valve 12, outdoor unit heat exchanger 13 and outdoor unit expansion valve 14.

[0049] For example, compressor 11 is used to compress gaseous refrigerant in the piping of multi-split air conditioning system 100. Four-way valve 12 is used to adjust the flow direction of refrigerant in multi-split air conditioning system 100 when switching operating modes.

[0050] For example, when the multi-split air conditioning system 100 switches between cooling mode and heating mode, the four-way valve 12 needs to be adjusted accordingly so that the refrigerant in the multi-split air conditioning system 100 flows in different directions in cooling mode and heating mode.

[0051] In some embodiments, such as Figure 2a As shown, the four-way valve 12 includes: a first port 12A connected to the refrigerant gas pipe 3, a second port 12B connected to the inlet of the compressor 11, a third port 12C connected to one end of the outdoor unit heat exchanger 13, and a fourth port 12D connected to the outlet of the compressor 11. The other end of the outdoor unit heat exchanger 13 is connected to the refrigerant liquid pipe 4 through the outdoor unit expansion valve 14.

[0052] By connecting the different ports of the four-way valve 12 to each other, the refrigerant in the multi-split air conditioning system 100 can flow in different directions along the pipeline.

[0053] For example, such as Figure 2a As shown, the indoor unit 2 may include an indoor unit heat exchanger 21 and an indoor unit expansion valve 22.

[0054] In some examples, such as Figure 2a As shown, refrigerant gas pipe 3 connects the four-way valve 12 and the first end 2A of the indoor unit 2. Refrigerant liquid pipe 4 connects the outdoor unit expansion valve 14 and the second end 2B of the indoor unit 2.

[0055] Understandably, the first end 2A of the indoor unit 2 is the end of the indoor unit 2 closest to the indoor unit heat exchanger 21, and the second end 2B of the indoor unit 2 is the end of the indoor unit 2 closest to the indoor unit expansion valve 22.

[0056] Refrigerant gas pipe 3 and refrigerant liquid pipe 4 are the main pipes for refrigerant flow in the multi-split air conditioning system 100. Refrigerant gas pipe 3 is interconnected with each outdoor unit 1 and each indoor unit 2 via pipes, and refrigerant liquid pipe 4 is interconnected with each outdoor unit 1 and each indoor unit 2 via pipes. Therefore, by setting up refrigerant gas pipe 3 and refrigerant liquid pipe 4, refrigerant can circulate among multiple outdoor units 1 and multiple indoor units 2, thereby realizing the cooling or heating function of the multi-split air conditioning system 100.

[0057] In some examples, such as Figure 2a As shown, the gas-side refrigerant shut-off valve 5 is located between the first end 2A of the indoor unit 2 and the refrigerant gas pipe 3, and the liquid-side refrigerant shut-off valve 6 is located between the second end 2B of the indoor unit 2 and the refrigerant liquid pipe 4.

[0058] For example, such as Figure 2a As shown, a gas-side refrigerant shut-off valve 5 can control one indoor unit 2, and a liquid-side refrigerant shut-off valve 6 can control one indoor unit 2.

[0059] Alternatively, a gas-side refrigerant shut-off valve 5 can control multiple indoor units 2, and a liquid-side refrigerant shut-off valve 6 can control multiple indoor units 2. For example, Figure 2b In this design, one gas-side refrigerant shut-off valve 5 can control two indoor units 2, and one liquid-side refrigerant shut-off valve 6 can control two indoor units 2. This disclosure does not limit the scope of the design.

[0060] Correspondingly, when the gas-side refrigerant shut-off valve 5 is open, refrigerant can flow between the first end 2A of the indoor unit 2 and the refrigerant gas pipe 3; when the gas-side refrigerant shut-off valve 5 is closed, refrigerant cannot flow between the first end 2A of the indoor unit 2 and the refrigerant gas pipe 3. When the liquid-side refrigerant shut-off valve 6 is open, refrigerant can flow between the second end 2B of the indoor unit 2 and the refrigerant liquid pipe 4; when the liquid-side refrigerant shut-off valve 6 is closed, refrigerant cannot flow between the second end 2B of the indoor unit 2 and the refrigerant liquid pipe 4. When both the gas-side refrigerant shut-off valve 5 and the liquid-side refrigerant shut-off valve 6 are closed, the indoor unit 2 can be isolated from the rest of the multi-split air conditioning system 100.

[0061] The operating modes of the multi-split air conditioning system 100 include cooling mode and heating mode.

[0062] When the multi-split air conditioning system 100 is in cooling mode, the refrigerant flow direction is as follows: Figure 3a As shown by the middle arrow, in the four-way valve 12 of outdoor unit 1, the first port 12A and the second port 12B are connected, and the third port 12C and the fourth port 12D are connected. The compressor 11 compresses the refrigerant and discharges high-temperature, high-pressure gaseous refrigerant from its outlet. This gaseous refrigerant then passes through the fourth port 12D and the third port 12C of the four-way valve 12 and enters the outdoor unit heat exchanger 13, where it condenses into high-temperature, high-pressure liquid refrigerant. This high-temperature, high-pressure liquid refrigerant then passes through the outdoor unit expansion valve 14 and the indoor unit expansion valve 22, where it is throttled into low-temperature, low-pressure liquid refrigerant. This low-temperature, low-pressure liquid refrigerant evaporates and absorbs heat in the indoor unit heat exchanger 21, evaporating into low-temperature, low-pressure gaseous refrigerant. This low-temperature, low-pressure gaseous refrigerant then returns to the four-way valve 12 of outdoor unit 1 through the refrigerant gas pipe 3. Finally, it returns to the compressor 11, which compresses it into high-temperature, high-pressure gaseous refrigerant. The multi-split air conditioning system 100 continues its refrigeration cycle.

[0063] When the multi-split air conditioning system 100 is in heating mode, the refrigerant flow direction is as follows: Figure 3bAs indicated by the middle arrow, in the four-way valve 12 of outdoor unit 1, the first port 12A and the fourth port 12D are connected, and the third port 12C and the second port 12B are connected. The compressor 11 compresses the refrigerant and discharges high-temperature, high-pressure gaseous refrigerant from its outlet. This high-temperature, high-pressure gaseous refrigerant passes through the fourth port 12D, the first port 12A, and the refrigerant pipe 3 of the four-way valve 12 and enters the indoor unit heat exchanger 21, where it condenses into high-temperature, high-pressure liquid refrigerant. This high-temperature, high-pressure liquid refrigerant passes through the indoor unit expansion valve 22 and the outdoor unit expansion valve 14, where it is throttled into low-temperature, low-pressure liquid refrigerant. This low-temperature, low-pressure liquid refrigerant evaporates and absorbs heat in the outdoor unit heat exchanger 13, evaporating into low-temperature, low-pressure gaseous refrigerant. This low-temperature, low-pressure gaseous refrigerant then returns to the compressor 11 through the third port 12C and the second port 12B of the four-way valve 12, where it is compressed into high-temperature, high-pressure gaseous refrigerant. The multi-split air conditioning system 100 continues its heating cycle.

[0064] The operating mode of the aforementioned multi-split air conditioning system 100 may also include a refrigerant recovery mode. When the multi-split air conditioning system 100 is in refrigerant recovery mode, the liquid-side refrigerant shut-off valve 6 is closed, and the refrigerant flow direction is as follows: Figure 3c As shown by the middle arrow, in the four-way valve 12 of outdoor unit 1, the first port 12A and the second port 12B are connected, and the third port 12C and the fourth port 12D are connected. The compressor 11 operates at high frequency, compressing the refrigerant and discharging high-temperature, high-pressure gaseous refrigerant from its outlet. This gaseous refrigerant then passes through the fourth port 12D and the third port 12C of the four-way valve 12 and enters the outdoor unit heat exchanger 13, where it condenses into high-temperature, high-pressure liquid refrigerant. Because the liquid-side refrigerant shut-off valve 6 is closed, the refrigerant stored in the outdoor unit heat exchanger 13 cannot be discharged.

[0065] In some embodiments of this disclosure, the plurality of outdoor units 1 includes at least one first outdoor unit 1a. Exemplarily, the number of first outdoor units 1a may be one, two, or three, etc.

[0066] For ease of explanation, the following embodiments will use a multi-split air conditioning system 100 including two outdoor units 1 as an example.

[0067] In some embodiments, such as Figure 2a As shown, the plurality of indoor units 2 include a first indoor unit 2a.

[0068] For example, the first indoor unit 2a can be the indoor unit that has experienced refrigerant leakage among a plurality of indoor units 2.

[0069] In some examples, such as Figure 2aAs shown, the multi-split air conditioning system 100 also includes a refrigerant concentration sensor 7 and a controller 8. The refrigerant concentration sensor 7 is installed in the first indoor unit 2a and is used to detect the refrigerant concentration in the room where the indoor unit 2a is located. The controller 8 is coupled to the refrigerant concentration sensor 7 and is used to recover refrigerant to the outdoor unit 1 according to the refrigerant concentration in the room where the first indoor unit 2a is located.

[0070] In some examples, the first outdoor unit 1a includes a one-way valve 15 disposed between the outlet of the compressor 11 and the four-way valve 12, the one-way valve 15 being used to seal the recovered refrigerant in the outdoor unit heat exchanger 13 of the first outdoor unit 1a in cooperation with the outdoor unit expansion valve 14 of the first outdoor unit 1a.

[0071] The one-way valve 15 is open from the outlet of the compressor 11 toward the four-way valve 12. The refrigerant discharged from the outlet of the compressor 11 can only flow in the direction from the outlet of the compressor 11 toward the four-way valve 12, and cannot flow in the opposite direction.

[0072] That is, the one-way valve 15 is located between the outlet of the compressor 11 and the fourth port 12D. The conduction direction of the one-way valve 15 is from the outlet of the compressor 11 to the fourth port 12D of the four-way valve 12.

[0073] By setting a one-way valve 15, in the event that the multi-split air conditioning system 100 detects a refrigerant leak in the first indoor unit 2a, such as... Figure 3c As shown, the multi-split air conditioning system 100 can operate in refrigerant recovery mode, whereby the refrigerant can be stored in the outdoor unit heat exchanger 13. After the refrigerant recovery is completed, as... Figure 4a As shown, the outdoor unit expansion valve 14 of the first outdoor unit 1a can be closed. At this time, due to the presence of the one-way valve 15, the refrigerant stored in the outdoor unit heat exchanger 13 of the first outdoor unit 1a cannot flow to the compressor 11, thus isolating a portion of the refrigerant in the outdoor unit heat exchanger 13 of the first outdoor unit 1a. After isolating the first indoor unit 2a where refrigerant leakage occurs (e.g., Figure 4a In the process of closing the gas-side refrigerant shut-off valve 5 and the liquid-side refrigerant shut-off valve 6 corresponding to the first indoor unit 2a where refrigerant leakage occurs, it can prevent the refrigerant capacity of the remaining indoor and outdoor units from being mismatched with the standard capacity of the multi-split air conditioning system 100, which would cause the high-pressure protection alarm and shutdown of the multi-split air conditioning system 100. This would also allow the remaining indoor unit 2 and outdoor unit 1 to return to normal operation mode, thereby improving the user experience.

[0074] For example, such as Figure 4b As shown, the remaining indoor unit 2 and outdoor unit 1 can resume cooling mode, with the refrigerant circulating within the remaining indoor unit 2 and outdoor unit 1. Figure 4cAs shown, the remaining indoor units 2 and outdoor unit 1 can resume heating mode, and the refrigerant circulates within the remaining indoor units 2 and outdoor unit 1. It should be noted that in this situation, the four-way valve 12 of the first outdoor unit 1a, used for storing the refrigerant, remains in the open position of the refrigerant recovery mode to prevent refrigerant leakage through the four-way valve 12. For ease of description, the above... Figure 4b and Figure 4c The operating mode in this system is called "partial load operation mode".

[0075] Therefore, some embodiments of the multi-split air conditioning system 100 provided in this disclosure, by setting a gas-side refrigerant shut-off valve 5 and a liquid-side refrigerant shut-off valve 6, can isolate the first indoor unit 2a where refrigerant leakage occurs from the rest of the multi-split air conditioning system 100. By setting a one-way valve 15 between the outlet of the compressor 11 and the four-way valve 12 in at least one first outdoor unit 1a, when the refrigerant of the multi-split air conditioning system 100 is recovered to the outdoor unit heat exchanger 13 of the outdoor unit 1, the outdoor unit expansion valve 14 of the first outdoor unit 1a can be closed, thereby isolating a portion of the refrigerant in the outdoor unit heat exchanger 13 of the first outdoor unit 1a. Therefore, it is possible to avoid the situation where the refrigerant capacity in the remaining indoor units 2 and outdoor units 1 is mismatched with the standard capacity of the multi-split air conditioning system 100, causing the high-pressure protection alarm shutdown of the multi-split air conditioning system 100, and thus the remaining indoor units 2 and outdoor units 1 can be restored to normal operating mode, thereby improving the user experience.

[0076] In some embodiments, the above-mentioned method of recovering refrigerant to outdoor unit 1 based on the refrigerant concentration in the room where the first indoor unit 2a is located includes: acquiring the refrigerant concentration value detected by the refrigerant concentration sensor 7, comparing the refrigerant concentration value with a preset concentration value; and if the refrigerant concentration value in the room where the first indoor unit 2a is located is greater than the preset concentration value, closing the liquid-side refrigerant shut-off valve 6 and controlling the compressor 11 of outdoor unit 1 to work so as to recover refrigerant to outdoor unit 1.

[0077] If no refrigerant leak occurs in indoor unit 2, the refrigerant concentration in the room where indoor unit 2 is located will be close to 0. Therefore, if the controller 8 detects that the refrigerant concentration in the room where the first indoor unit 2a is located is greater than a preset concentration value, it can determine that a refrigerant leak has occurred in the room where the first indoor unit 2a is located. By setting up a refrigerant concentration sensor 7, the controller 8 can obtain the refrigerant concentration in the room where indoor unit 2 is located, thereby determining the location of the indoor unit 2 where the refrigerant leak has occurred.

[0078] Understandably, at this time, the operating mode of the multi-split air conditioning system 100 is adjusted to refrigerant recovery mode, and the refrigerant is recovered to the outdoor unit 1.

[0079] For example, while the controller 8 adjusts the operating mode of the multi-split air conditioning system 100 to refrigerant recovery mode, it can also make the fan of the indoor unit heat exchanger 21 and the fan of the outdoor unit heat exchanger 13 run at the highest speed, which can speed up the refrigerant recovery.

[0080] In some embodiments, when the refrigerant concentration in the room where the first indoor unit 2a is located is greater than a preset concentration value, before closing the liquid-side refrigerant shut-off valve 6, the controller 8 is further configured to: determine the operating mode of the multi-split air conditioning system 100; if the operating mode of the multi-split air conditioning system 100 is non-cooling mode, adjust the operating mode of the multi-split air conditioning system 100 to cooling mode and run it for 'a' seconds, and control the fans of the indoor unit heat exchanger 21 and the outdoor unit heat exchanger 13 to run at their highest speeds. Wherein, 'a' is a constant.

[0081] For example, 30≤a≤90, where a can be 30, 65, or 90, etc.

[0082] By setting the above, the refrigerant pressure inside the indoor unit 2 can be reduced as quickly as possible, thereby reducing the refrigerant leakage rate.

[0083] In some embodiments, the controller 8 is further configured to: after recovering refrigerant into the outdoor unit 1, close the gas-side refrigerant shut-off valve 5 between the first indoor unit 2a and the refrigerant gas pipe 3, and open the liquid-side refrigerant shut-off valve 6 between each indoor unit 2 other than the first indoor unit 2a and the refrigerant liquid pipe 4; obtain the ratio between the capacity of the first indoor unit 2a and the total capacity of the outdoor unit 1, and compare the ratio with a preset ratio; if the ratio is greater than or equal to the preset ratio, close the outdoor unit expansion valve 14 of the first outdoor unit 1a.

[0084] By opening the liquid-side refrigerant shut-off valve 6 between the indoor units 2 (excluding the first indoor unit 2a) and the refrigerant liquid pipe 4, the remaining indoor units 2 (excluding the first indoor unit 2a) can be reconnected to the refrigerant gas pipe 3 and the refrigerant liquid pipe 4, ensuring that the subsequent indoor units 2 can operate normally.

[0085] For example, the preset ratio is d%, where d is a constant, 30≤d≤50, for example d can be 30, 40 or 50, etc.

[0086] As those skilled in the art will understand, when the ratio between the capacity of the first indoor unit 2a and the total capacity of the outdoor unit 1 is greater than or equal to a preset ratio, recovering the refrigerant from the first indoor unit 2a will cause excessive pressure within the multi-split air conditioning system 100, triggering an alarm and affecting the normal operation of the remaining outdoor units 1 and indoor units 2 in the multi-split air conditioning system 100. When the ratio between the capacity of the first indoor unit 2a and the total capacity of the outdoor unit 1 is less than the preset ratio, recovering the refrigerant from the first indoor unit 2a is unlikely to significantly affect the pressure within the multi-split air conditioning system 100, and therefore is unlikely to affect the normal operation of the remaining outdoor units 1 and indoor units 2 in the multi-split air conditioning system 100.

[0087] When the ratio between the capacity of the first indoor unit 2a and the total capacity of the outdoor unit 1 is greater than a preset ratio, the controller 8 of this disclosure closes the outdoor unit expansion valve 14 of the first outdoor unit 1a. Under the combined action of the one-way valve 15, a portion of the refrigerant can be isolated in the first outdoor unit 1a. Therefore, this portion of the refrigerant can be prevented from affecting the pressure of the other outdoor units 1 and indoor units 2 in the multi-split air conditioning system 100, thereby preventing the other outdoor units 1 and indoor units 2 in the multi-split air conditioning system 100 from having excessive pressure.

[0088] In some examples, the controller 8 is also used to: after the refrigerant is recovered to the outdoor unit 1, close the gas-side refrigerant shut-off valve 5 between the first indoor unit 2a and the refrigerant pipe 3, and at the same time turn off the fan of the indoor unit heat exchanger 21 of the first indoor unit 2a.

[0089] Understandably, at this point, the first indoor unit 2a no longer has the function of cooling or heating.

[0090] In some embodiments, the outdoor unit 1 further includes a suction pressure sensor 16, which is disposed between the inlet and the second interface 12B of the compressor 11 and coupled to the controller 8. The suction pressure sensor 16 is used to detect the suction pressure of the compressor 11.

[0091] It is understandable that, such as Figure 3c As shown, when the multi-split air conditioning system 100 is operating in cooling mode, the indoor unit 2 is directly connected to the compressor 11 via the refrigerant pipe 3. Therefore, the suction pressure of the compressor 11 detected by the suction pressure sensor 16 is approximately equal to the refrigerant pressure inside the indoor unit 2. The higher the refrigerant content inside the indoor unit 2, the greater the refrigerant pressure inside the indoor unit 2.

[0092] In some examples, during the process of the multi-split air conditioning system 100 recovering refrigerant to the outdoor unit 1, the controller 8 is also configured to: acquire a first suction pressure value of the suction pressure sensor 16, compare the first suction pressure value with a first preset suction pressure value; and determine that the refrigerant in the first indoor unit 2a has been recovered to the outdoor unit 1 if the first suction pressure value is less than or equal to the first preset suction pressure value.

[0093] For example, the first preset inhalation pressure value can be c MPa. Where c is a constant, c≤0.1, for example, the value of c can be 0.01, 0.05 or 0.1, etc.

[0094] By setting the suction pressure sensor 16, the controller 8 can monitor in real time whether the refrigerant in the indoor unit 2 has been recovered to the outdoor unit 1, making the refrigerant recovery control of the multi-split air conditioning system 100 more precise.

[0095] In some examples, controller 8 is also configured to cause the first indoor unit 2a to issue a warning signal after determining that refrigerant recovery in the first indoor unit 2a is complete.

[0096] For example, the warning signals mentioned above can be sound or optical signals.

[0097] With the above settings, the user can be notified that the indoor unit 2 has malfunctioned, so as to accurately identify the malfunctioning indoor unit 2 and carry out repairs.

[0098] In some embodiments, such as Figure 2a As shown, the outdoor unit 1 also includes an exhaust temperature sensor 17 and a liquid-side refrigerant temperature sensor 18. The exhaust temperature sensor 17 is located at the exhaust port of the compressor 11 and is coupled to the controller 8. The exhaust temperature sensor 17 is used to detect the exhaust temperature of the compressor 11. The liquid-side refrigerant temperature sensor 18 is located between the outdoor unit expansion valve 14 and the refrigerant liquid line 4, and is coupled to the controller 8. The liquid-side refrigerant temperature sensor 18 is used to detect the temperature of the refrigerant between the outdoor unit expansion valve 14 and the refrigerant liquid line 4.

[0099] With the above settings, the controller 8 can obtain the discharge temperature of the compressor 11 and the temperature of the refrigerant between the outdoor unit expansion valve 14 and the refrigerant liquid pipe 4.

[0100] In the following embodiment, two outdoor units 1, including a first outdoor unit 1a and a second outdoor unit 1b, are used as an example for illustration. The first outdoor unit 1a is an outdoor unit used to store refrigerant, and the second outdoor unit 1b is an outdoor unit that maintains normal operation after the multi-split air conditioning system is switched to a partial load operation mode.

[0101] In some examples, the controller 8 is also used to: after closing the outdoor unit expansion valve 14 of the first outdoor unit 1a, acquire the exhaust temperature Td2 and the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve of another outdoor unit 1 (e.g., the second outdoor unit 1b) besides the first outdoor unit 1a; if the exhaust temperature Td2 of the other outdoor unit 1 besides the first outdoor unit 1a is greater than the preset exhaust temperature g and the holding time is less than the first time, or if the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve of the other outdoor unit 1 besides the first outdoor unit 1a is less than or equal to the preset subcooling degree f and the holding time is less than the first time, turn on the compressor 11 of the first outdoor unit 1a and hold it for a second time, adjust the opening value of the outdoor unit expansion valve 14 of the first outdoor unit 1a to the target opening value and hold it for a second time. Wherein, the subcooling degree of the liquid-side refrigerant shut-off valve of any outdoor unit 1 is the value of the saturation temperature at the exhaust pressure of that outdoor unit minus the temperature of the liquid-side refrigerant shut-off valve.

[0102] In some examples, such as Figure 2a As shown, the outdoor unit 1 may also include an exhaust pressure sensor 19, which is disposed between the exhaust port of the compressor 11 and the four-way valve 12 and coupled to the controller 8. The exhaust pressure sensor 19 is used to detect the pressure of the refrigerant discharged from the exhaust port of the compressor 11.

[0103] Those skilled in the art will understand that there is a one-to-one correspondence between the saturation temperature of any outdoor unit 1 under exhaust pressure and the pressure value detected by the exhaust pressure sensor 19. After detecting the pressure value detected by the exhaust pressure sensor 19, the saturation temperature of the outdoor unit 1 under exhaust pressure can be obtained, thereby obtaining the subcooling degree of the liquid-side refrigerant shut-off valve of any outdoor unit 1.

[0104] For example, the preset exhaust temperature g is a constant, 90≤g≤110, for example, the value of g can be 90, 100 or 110, etc.

[0105] The first time mentioned above can be e minutes, where e is a constant, 10≤e≤20. For example, the value of e can be 10, 15 or 20, etc.

[0106] The aforementioned preset subcooling degree f is a parameter related to the outdoor ambient temperature Ta1, the capacity ratio j of the indoor unit 2 operating in partial load mode, and the outdoor unit 1. f = m - j + n * (Ta1 - q), where m, n, and k are constants: 5 ≤ m ≤ 15, 0.1 ≤ n ≤ 0.5, and 10 ≤ q ≤ 30. For example, the value of m can be 5, 10, or 15, the value of n can be 0.1, 0.3, or 0.5, and the value of q can be 10, 20, or 30. Correspondingly, the multi-split air conditioning system 100 also includes an outdoor temperature sensor coupled to the controller 8 for detecting the outdoor ambient temperature.

[0107] The target opening can be h%, where h is a constant, 2 ≤ h ≤ 4. For example, the value of h can be 2, 3, or 4. The second time can be i seconds, where i is a constant, 5 ≤ i ≤ 20. For example, the value of i can be 5, 12, or 20.

[0108] For example, after the compressor 11 of the first outdoor unit 1a is turned on, the speed of the compressor 11 can be controlled at a lower speed by the controller 8, for example, the speed of the compressor 11 can be controlled at one-quarter of its maximum speed.

[0109] After closing the outdoor unit expansion valve 14 of the first outdoor unit 1a, the multi-split air conditioning system 100, except for the first indoor unit 2a and the first outdoor unit 1a, is adjusted to a partial load operation mode. Because the first outdoor unit 1a stores some refrigerant, the indoor unit 2 and outdoor unit 1 operating in the partial load mode may experience refrigerant shortage. The controller 8 of the multi-split air conditioning system 100 of this disclosure can release the refrigerant stored in the first outdoor unit 1a through the outdoor unit expansion valve 14 to the refrigerant liquid pipe 4 to replenish the indoor unit 2 and outdoor unit 1 operating in the partial load mode, thereby restoring the refrigerant content in the indoor unit 2 and outdoor unit 1 operating in the partial load mode to normal.

[0110] In other examples, such as Figure 5 As shown, outdoor unit 1 includes a first outdoor unit 1a and a second outdoor unit 1b. The values ​​of h and i mentioned above can be determined by the subcooling difference ΔTsc and the exhaust pressure difference ΔP. Where ΔTsc = f - Tsc, then the subcooling difference ΔTsc1 of the first outdoor unit 1a = f - Tsc1, and the subcooling difference ΔTsc2 of the second outdoor unit 1b = f - Tsc2; ΔP is the exhaust pressure value of the second outdoor unit 1b minus the exhaust pressure value of the first outdoor unit 1a. Therefore, h = xΔTsc2 + y(ΔTsc2 - ΔTsc1), and i = z × ΔP + k. Where x is a constant, 0.5≤x≤2, for example, the value of x can be 0.5, 1.2 or 2, etc.; y is a constant, 0.1≤y≤1, for example, the value of y can be 0.1, 0.5 or 1, etc.; z is a constant, 10≤z≤20, for example, the value of z can be 10, 15 or 20, etc.; k is a constant, 3≤k≤10, for example, the value of k can be 3, 7 or 10, etc.

[0111] Alternatively, the method of replenishing refrigerant can also refer to the following embodiments.

[0112] In other embodiments, such as Figure 5 As shown, the first outdoor unit 1a also includes a refrigerant replenishment device 110. One end of the refrigerant replenishment device 110 is connected to the fourth interface 12D, and the other end is connected to the second interface 12B. The refrigerant replenishment device 110 is also coupled to the controller 8.

[0113] The controller 8 is also used to: after closing the outdoor unit expansion valve 14 of the first outdoor unit 1a, obtain the exhaust temperature Td2 and the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve of the other outdoor unit 1 (e.g., the second outdoor unit 1b) besides the first outdoor unit 1a; and to open the refrigerant replenishment device 110 and maintain it for a third time if the exhaust temperature Td2 of the other outdoor unit 1 (e.g., the second outdoor unit 1b) besides the first outdoor unit 1a is greater than the preset exhaust temperature g and the holding time is less than the first time, or if the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve of the other outdoor unit 1 besides the first outdoor unit 1a is less than or equal to the preset subcooling degree f and the holding time is less than the first time.

[0114] For example, the third time mentioned above can be the same as the second time mentioned above.

[0115] With the above settings, as Figure 5 As shown, the refrigerant stored in the outdoor heat exchanger 13 of the first outdoor unit 1a can be released to the refrigerant gas pipe 3 through the refrigerant replenishment device 110 and the four-way valve 12 to replenish the indoor unit 2 and outdoor unit 1 operating in partial load mode, thereby restoring the refrigerant content in the multi-split air conditioning system 100 to normal.

[0116] For example, the controller 8 is also configured to: open the refrigerant replenishment device 110 when the difference between the discharge pressure and the suction pressure of the compressor 11 is greater than a preset pressure difference, or when the compressor 11 stops operating.

[0117] By setting the above, the difference between the inlet pressure and the outlet pressure of the compressor 11 can be reduced, which can prevent the compressor 11 from being damaged by the excessive difference or from having difficulty starting the compressor 11.

[0118] In some embodiments, such as Figure 5 As shown, the refrigerant replenishment device 110 includes a solenoid valve 110a and a capillary tube 110b connected in series. The solenoid valve 110a is coupled to a controller 8. The controller 8 is also used to open the solenoid valve 110a when it is necessary to open the refrigerant replenishment device 110.

[0119] For example, the capillary tube 110b has a small diameter, which can reduce the flow rate of the refrigerant, thereby enabling precise control of the refrigerant flowing through the refrigerant replenishment device 110 by switching the solenoid valve 110a on and off.

[0120] In some examples, such as Figure 2a and Figure 5 As shown, the multi-split air conditioning system 100 also includes a gas-liquid separator 9. The main function of the gas-liquid separator 9 is to protect the compressor 11 when refrigerant liquid returns. The gas-liquid separator 9 can also temporarily store excess refrigerant liquid.

[0121] On the other hand, such as Figure 6 As shown, some embodiments of this disclosure also provide a control method for a multi-split air conditioning system, the control method including steps S100 to S400.

[0122] S100: Obtain the refrigerant concentration value detected by the refrigerant concentration sensor 7, and compare the refrigerant concentration value with the preset concentration value.

[0123] S200: If the refrigerant concentration value in the room where the first indoor unit 2a is located is greater than the preset concentration value, close the liquid-side refrigerant shut-off valve 6 between the indoor unit 2 and the refrigerant liquid pipe 4, and control the compressor 11 of the multiple outdoor units 1 to work so as to recover the refrigerant into the outdoor unit 1.

[0124] By following the steps above, the location of the leaking indoor unit 2 can be determined, and the refrigerant can be recovered into the outdoor unit 1.

[0125] S300. After recovering the refrigerant into the outdoor unit 1, close the gas-side refrigerant shut-off valve 5 between the first indoor unit 2a and the refrigerant gas pipe 3, and open the liquid-side refrigerant shut-off valve 6 between each indoor unit 2 (excluding the first indoor unit 2a) and the refrigerant liquid pipe 4.

[0126] After the refrigerant has been recovered through the above steps, the first indoor unit 2a and the remaining equipment can be isolated.

[0127] S400, Close the outdoor unit expansion valve 14 of the first outdoor unit 1a.

[0128] By following the above steps, the refrigerant can be prevented from affecting the pressure of the remaining outdoor unit 1 and indoor unit 2 in the multi-split air conditioning system 100, thereby preventing the situation where the pressure of the remaining outdoor unit 1 and indoor unit 2 in the multi-split air conditioning system 100 is too high.

[0129] In some embodiments, the outdoor unit expansion valve 14 that shuts off the first outdoor unit 1a includes: S410 to S420.

[0130] S410. Obtain the ratio between the capacity of the first indoor unit 2a and the total capacity of the outdoor unit 1, and compare the ratio with a preset ratio.

[0131] S420. If the above ratio is greater than or equal to the preset ratio, close the outdoor unit expansion valve 14 of the first outdoor unit 1a.

[0132] Through the above steps, after recovering the refrigerant in the first indoor unit 2a and isolating the first indoor unit 2a, the refrigerant capacity in the first indoor unit 2a can be detected, and the outdoor unit expansion valve 14 of the first outdoor unit 1a can be controlled accordingly based on the detection results.

[0133] In some embodiments, after closing the outdoor unit expansion valve 14 of the first outdoor unit 1a, the above control method further includes steps S500 to S600.

[0134] S500: Obtain the exhaust temperature Td2 of other outdoor units 1 (e.g., second outdoor unit 1b) besides the first outdoor unit 1a and the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve.

[0135] S600, if the exhaust temperature Td2 of the outdoor unit 1 other than the first outdoor unit 1a is less than or equal to the preset exhaust temperature g and the holding time is less than the first time, or if the subcooling degree Tsc2 of the liquid-side refrigerant shut-off valve of the outdoor unit 1 other than the first outdoor unit 1a (e.g., the second outdoor unit 1b) is greater than the preset subcooling degree f and the holding time is less than the first time, the opening value of the outdoor unit expansion valve 14 of the first outdoor unit 1a is adjusted to the target opening and held for a second time, or the refrigerant replenishment device 110 is opened and held for a third time.

[0136] Through the above steps, the refrigerant content in the outdoor units 1 and indoor units 2 other than the first outdoor unit 1a and the first indoor unit 2a can be detected. If the refrigerant content is low, the refrigerant can be replenished through the outdoor unit expansion valve 14 of the first outdoor unit 1a or the refrigerant replenishment device 110, thereby restoring the refrigerant content in the outdoor units 1 and indoor units 2 other than the first outdoor unit 1a and the first indoor unit 2a to normal.

[0137] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology 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.

Claims

1. A multi-split air conditioning system, characterized in that, The multi-split air conditioning system includes: Multiple outdoor units, each outdoor unit including: a compressor, a four-way valve, an outdoor unit heat exchanger, and an outdoor unit expansion valve; Multiple indoor units, including the first indoor unit; A refrigerant pipe connecting the four-way valve and the first end of the indoor unit; A refrigerant pipe connecting the expansion valve of the outdoor unit and the second end of the indoor unit; A gas-side refrigerant shut-off valve is installed between the first end of the indoor unit and the refrigerant pipe. A liquid-side refrigerant shut-off valve is installed between the second end of the indoor unit and the refrigerant liquid pipe; A refrigerant concentration sensor, installed in the first indoor unit, is used to detect the refrigerant concentration in the room where the first indoor unit is located; and, The controller, coupled to the refrigerant concentration sensor, is used to recover refrigerant to the outdoor unit based on the refrigerant concentration in the room where the first indoor unit is located; The plurality of outdoor units include at least one first outdoor unit, the first outdoor unit including: a one-way valve disposed between the outlet of the compressor and the four-way valve, the one-way valve being used to seal the recovered refrigerant in the outdoor heat exchanger of the first outdoor unit in cooperation with the outdoor unit expansion valve of the first outdoor unit; An exhaust temperature sensor is disposed at the exhaust port of the compressor and coupled to the controller; the exhaust temperature sensor is used to detect the exhaust temperature of the compressor; and, A liquid-side refrigerant temperature sensor is installed between the outdoor unit expansion valve and the refrigerant liquid pipe, and is coupled to the controller; the liquid-side refrigerant temperature sensor is used to detect the temperature of the refrigerant between the outdoor unit expansion valve and the refrigerant liquid pipe. The controller is used for: After closing the expansion valve of the first outdoor unit, obtain the exhaust temperature of the other outdoor units besides the first outdoor unit and the subcooling degree of the liquid-side refrigerant shut-off valve. If the exhaust temperature of other outdoor units (excluding the first outdoor unit) is greater than the preset exhaust temperature and the holding time is less than the first time, or if the subcooling degree of the liquid-side refrigerant shut-off valve of other outdoor units (excluding the first outdoor unit) is less than or equal to the preset subcooling degree and the holding time is less than the first time, the compressor of the first outdoor unit is turned on and held for a second time, and the opening value of the outdoor unit expansion valve of the first outdoor unit is adjusted to the target opening value and held for the second time. Wherein, the subcooling degree of the liquid-side refrigerant shut-off valve of any of the outdoor units is the value of the saturation temperature of the outdoor unit under the exhaust pressure minus the temperature of the liquid-side refrigerant shut-off valve.

2. The multi-split air conditioning system according to claim 1, characterized in that, The step of recovering refrigerant to the outdoor unit based on the refrigerant concentration in the room where the first indoor unit is located includes: Obtain the refrigerant concentration value detected by the refrigerant concentration sensor, and compare the refrigerant concentration value with a preset concentration value; If the refrigerant concentration in the room where the first indoor unit is located is greater than the preset concentration value, the liquid-side refrigerant shut-off valve is closed, and the compressor of the outdoor unit is controlled to work to recover the refrigerant into the outdoor unit.

3. The multi-split air conditioning system according to claim 2, characterized in that, If the refrigerant concentration in the room where the first indoor unit is located is greater than the preset concentration value, before closing the liquid-side refrigerant shut-off valve, the controller is further configured to: Determine the operating mode of the multi-split air conditioning system; When the multi-split air conditioning system is in non-cooling mode, the operating mode of the multi-split air conditioning system is adjusted to cooling mode and run for a seconds, and the fans of the indoor unit heat exchanger and the outdoor unit heat exchanger are controlled to run at the highest speed. Where a is a constant.

4. The multi-split air conditioning system according to claim 2, characterized in that, The controller is also used for: After the refrigerant is recovered into the outdoor unit, the gas-side refrigerant shut-off valve between the first indoor unit and the refrigerant gas pipe is closed, and the liquid-side refrigerant shut-off valve between each indoor unit other than the first indoor unit and the refrigerant liquid pipe is opened. Obtain the ratio between the capacity of the first indoor unit and the total capacity of the outdoor unit, and compare the ratio with a preset ratio; If the ratio is greater than or equal to the preset ratio, the outdoor unit expansion valve of the first outdoor unit is closed.

5. The multi-split air conditioning system according to claim 4, characterized in that, The four-way valve includes: a first port connected to the refrigerant gas pipe, a second port connected to the inlet of the compressor, a third port connected to one end of the outdoor unit heat exchanger, and a fourth port connected to the outlet of the compressor. The other end of the outdoor unit heat exchanger is connected to the refrigerant liquid pipe through the outdoor unit expansion valve. The outdoor unit also includes: a suction pressure sensor, which is disposed between the inlet of the compressor and the second interface and coupled to the controller; The suction pressure sensor is used to detect the suction pressure of the compressor.

6. The multi-split air conditioning system according to claim 4, characterized in that, The four-way valve includes: a first port connected to the refrigerant gas pipe, a second port connected to the inlet of the compressor, a third port connected to one end of the outdoor unit heat exchanger, and a fourth port connected to the outlet of the compressor. The other end of the outdoor unit heat exchanger is connected to the refrigerant liquid pipe through the outdoor unit expansion valve. The outdoor unit also includes: The first outdoor unit further includes a refrigerant replenishment device, one end of which is connected to the fourth interface and the other end of which is connected to the second interface, and the refrigerant replenishment device is coupled to the controller; The controller is also used for: If the exhaust temperature of outdoor units other than the first outdoor unit is greater than the preset exhaust temperature and the holding time is less than the first time, or if the subcooling degree of the liquid-side refrigerant shut-off valve of outdoor units other than the first outdoor unit is less than or equal to the preset subcooling degree and the holding time is less than the first time, the refrigerant replenishment device is opened and held for a third time.

7. The multi-split air conditioning system according to claim 6, characterized in that, The refrigerant replenishment device includes: a solenoid valve and a capillary tube connected in series; the solenoid valve is coupled to the controller; The controller is also used for: If it is necessary to open the refrigerant replenishment device, open the solenoid valve.

8. A control method for a multi-split air conditioning system, characterized in that, The control method includes: Obtain the refrigerant concentration value detected by the refrigerant concentration sensor, and compare the refrigerant concentration value with a preset concentration value; If the refrigerant concentration value in the room where the first indoor unit is located is greater than the preset concentration value, the liquid-side refrigerant shut-off valve between the multiple indoor units and the refrigerant liquid pipe is closed, and the compressors of the multiple outdoor units are controlled to work to recover the refrigerant into the outdoor units. After the refrigerant is recovered into the outdoor unit, the gas-side refrigerant shut-off valve between the first indoor unit and the refrigerant gas pipe is closed, and the liquid-side refrigerant shut-off valve between each indoor unit other than the first indoor unit and the refrigerant liquid pipe is opened. Close the outdoor unit expansion valve of the first outdoor unit; Obtain the exhaust temperature and liquid-side refrigerant shut-off valve subcooling of the outdoor units other than the first outdoor unit; If the exhaust temperature of other outdoor units (excluding the first outdoor unit) is greater than the preset exhaust temperature and the holding time is less than the first time, or if the subcooling degree of the liquid-side refrigerant shut-off valve of other outdoor units (excluding the first outdoor unit) is less than or equal to the preset subcooling degree and the holding time is less than the first time, the compressor of the first outdoor unit is turned on and held for a second time, and the opening value of the outdoor unit expansion valve of the first outdoor unit is adjusted to the target opening value and held for the second time. Wherein, the subcooling degree of the liquid-side refrigerant shut-off valve of any of the outdoor units is the value of the saturation temperature of the outdoor unit under the exhaust pressure minus the temperature of the liquid-side refrigerant shut-off valve.

9. The control method for a multi-split air conditioning system according to claim 8, characterized in that, The step of closing the outdoor unit expansion valve of the first outdoor unit includes: Obtain the ratio between the capacity of the first indoor unit and the total capacity of the outdoor unit, and compare the ratio with a preset ratio; If the ratio is greater than or equal to the preset ratio, the outdoor unit expansion valve of the first outdoor unit is closed. After closing the outdoor unit expansion valve of the first outdoor unit, the control method further includes: Obtain the exhaust temperature and liquid-side refrigerant shut-off valve subcooling of the outdoor units other than the first outdoor unit; If the exhaust temperature of outdoor units other than the first outdoor unit is less than or equal to the preset exhaust temperature and the holding time is less than the first time, or if the subcooling degree of the liquid-side refrigerant shut-off valve of outdoor units other than the first outdoor unit is greater than the preset subcooling degree and the holding time is less than the first time, the refrigerant replenishment device is opened and held for a third time.

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