Multi-connected air conditioner

Abstract

The application discloses a multi-connected air conditioner, comprising at least one indoor unit and at least two outdoor units, wherein the outdoor unit comprises a compressor, a gas-liquid separator, an outdoor heat exchanger, a four-way valve and a first electronic expansion valve; the multi-connected air conditioner further comprises a pressure detection device for detecting the suction pressure of the compressor and a controller; the controller is configured to: control at least one outdoor unit to be in a running mode and a heating mode, control the at least one outdoor unit to be in a shutdown mode, define the outdoor unit in the running mode as a running outdoor unit, and define the outdoor unit in the shutdown mode as a shutdown outdoor unit; the first electronic expansion valve of the shutdown outdoor unit is in a shutdown state, and the suction pressure corresponding to the shutdown outdoor unit is obtained at a set time interval; when the change trend of the suction pressure value is an upward trend within a certain time period, it is determined that the gas-liquid separator has a backflow phenomenon at this time. By detecting the change state of the suction pressure of the compressor, it is determined whether the gas-liquid separator has a backflow phenomenon, so as to be processed in time and prevent the compressor from being damaged due to backflow.

Description

Technical Field

[0001] This invention belongs to the field of air conditioner technology, and particularly relates to a multi-split air conditioner. Background Technology

[0002] For multi-split air conditioners, there are modular combination units, which means that the gas and liquid pipes of multiple outdoor units are connected in parallel to form a whole.

[0003] When the indoor unit load is low and the demand frequency is low, the outdoor unit will simultaneously have both an operating outdoor unit and a shut-down outdoor unit. Under normal circumstances, the electronic expansion valve in the shut-down state is closed. Since the gas and liquid pipes of each outdoor unit are connected in parallel, if the electronic expansion valve of the shut-down outdoor unit leaks, the refrigerant in the operating state will flow through the leaking electronic expansion valve into the gas-liquid separator of the shut-down indoor unit. If not addressed promptly, after a certain period, the gas-liquid separator of the shut-down indoor unit will become full of liquid.

[0004] When the load on the air conditioning system changes and the outdoor unit, which was previously shut down, needs to be started, the refrigerant in the gas-liquid separator may enter the compressor through the suction pipe at the suction port, causing the compressor to be damaged due to liquid return.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] To address the issue of compressor liquid return damage, this application proposes detecting changes in the compressor's suction pressure to determine whether liquid return has occurred in the gas-liquid separator, thus preventing refrigerant from being drawn into the compressor upon the next startup, which could lead to compressor liquid return damage.

[0007] This application embodiment proposes a multi-split air conditioner, which includes:

[0008] An indoor unit, comprising at least one indoor unit;

[0009] An outdoor unit, comprising at least two outdoor units, wherein the outdoor units include:

[0010] Outdoor casing;

[0011] A compressor, which includes an intake port and an exhaust port;

[0012] A gas-liquid separator, located at the suction port of the compressor, is used for gas-liquid separation;

[0013] An outdoor heat exchanger, located inside an outdoor casing, is used to exchange heat with outdoor air.

[0014] The four-way valve has its first port connected to the compressor's discharge port, its second port connected to the compressor's suction port, its third port connected to the indoor unit, and its fourth port connected to the outdoor heat exchanger.

[0015] The first electronic expansion valve is located between the outdoor heat exchanger and the indoor unit;

[0016] Multi-split air conditioners also include:

[0017] A pressure detection device, located in the pipeline between the compressor and the four-way valve, is used to detect the compressor's suction pressure.

[0018] The controller is configured to control at least one outdoor unit to be in an operating mode and in a heating mode, and at least one outdoor unit to be in a shutdown mode, defining the outdoor unit in the operating mode and in the heating mode as the operating outdoor unit, and defining the outdoor unit in the shutdown mode as the shutdown outdoor unit.

[0019] The first electronic expansion valve of the outdoor unit is in the off state, and the corresponding intake pressure of the outdoor unit is obtained at a set time interval.

[0020] If the suction pressure value shows an upward trend over a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve cannot close properly.

[0021] In some embodiments, the outdoor unit further includes:

[0022] A subcooler is located between the first electronic expansion valve and the indoor unit. The first end of the subcooler is connected to the first electronic expansion valve, and the second end of the subcooler is connected to the indoor unit.

[0023] The second electronic expansion valve is used to control the degree of subcooling of the subcooler;

[0024] The controller is configured such that the first and second electronic expansion valves of the outdoor unit are closed when the unit is shut down, and the corresponding intake pressure of the outdoor unit is acquired at set time intervals.

[0025] If the suction pressure value changes upward within a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve and / or the second electronic expansion valve cannot close normally.

[0026] In some embodiments, the multi-split air conditioner further includes:

[0027] A coil temperature detection device is installed on the outdoor heat exchanger to detect the coil temperature of the outdoor heat exchanger.

[0028] An ambient temperature detection device, located on the outside of the outdoor casing, is used to detect the outdoor ambient temperature.

[0029] The controller is configured to: control at least one outdoor unit to be in operating mode and in heating mode, and at least one outdoor unit to be in shutdown mode, defining the outdoor unit in operating mode and in heating mode as the operating outdoor unit, and defining the outdoor unit in shutdown mode as the shutdown outdoor unit.

[0030] The first electronic expansion valve of the outdoor unit is closed when it is shut down. The outdoor coil temperature and outdoor ambient temperature of the outdoor unit are obtained at set time intervals.

[0031] When the difference between the coil temperature of the outdoor heat exchanger and the detected ambient temperature reaches the preset difference value, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve cannot close normally.

[0032] In some embodiments, the multi-split air conditioner further includes:

[0033] A coil temperature detection device is installed on the outdoor heat exchanger to detect the coil temperature of the outdoor heat exchanger.

[0034] An ambient temperature detection device, located on the outside of the outdoor casing, is used to detect the outdoor ambient temperature.

[0035] The controller is configured to control at least one outdoor unit to be in operating mode and heating mode, and at least one outdoor unit to be in shutdown mode, defining the outdoor unit in operating mode and heating mode as the operating outdoor unit, and defining the outdoor unit in shutdown mode as the shutdown outdoor unit.

[0036] The controller is configured such that the first and second electronic expansion valves of the outdoor unit are closed when the unit is shut down, and the suction pressure, outdoor coil temperature and outdoor ambient temperature of the outdoor unit are acquired at set time intervals.

[0037] When the suction pressure value is on an upward trend within a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve and / or the second electronic expansion valve cannot close normally.

[0038] In some embodiments, the controller is configured to: when it is determined that a liquid return phenomenon has occurred in the gas-liquid separator of the shut-down outdoor unit, after a set time, turn on the corresponding shut-down outdoor unit so that the refrigerant can pass through the corresponding pipeline.

[0039] In this embodiment, the change in the compressor's suction pressure is used to determine whether liquid return has occurred in the gas-liquid separator. This allows for a decision on whether the separator should be prioritized for activation upon the next startup to flush out blockages in the pipeline and resolve the liquid return issue in the compressor of the outdoor unit when it is shut down. This prevents the gas-liquid separator of the outdoor unit from becoming full of liquid, which could prevent the compressor from starting normally or cause damage due to liquid return.

[0040] In some embodiments, the controller is configured to:

[0041] When it is determined that the gas-liquid separator of the shut-down outdoor unit has experienced liquid return, the corresponding shut-down outdoor unit will be turned on after a set time to allow the refrigerant to flow through the corresponding pipeline.

[0042] In some embodiments, the controller is configured to record the running time of each outdoor unit and, when rotating units, prioritize turning on the outdoor unit with the shorter running time.

[0043] During unit rotation, if both an outdoor unit experiencing liquid return and an outdoor unit with short operating time are simultaneously shut down, the outdoor unit experiencing liquid return should be started first.

[0044] In some embodiments, the controller is configured to: when the outdoor unit that has stopped and is determined to have experienced liquid return is turned on, and after it is turned off again, if the gas-liquid separator is still determined to have experienced liquid return after the shutdown, the outdoor unit that has stopped is turned on first.

[0045] If the outdoor unit is turned on a set number of times after being shut down, and then shut down again, it is still judged that liquid return has occurred. In this case, the electronic expansion valve of the outdoor unit is determined to be damaged, and an alarm is triggered.

[0046] In some embodiments, the outdoor unit includes at least two compressors connected in parallel, and the compressors can operate one or in combination.

[0047] When calculating the operating time of the outdoor unit, the operating time of all compressors in the outdoor unit is uniformized.

[0048] This application also proposes another multi-split air conditioner, which includes:

[0049] An indoor unit, comprising at least one indoor unit;

[0050] An outdoor unit, comprising at least two outdoor units, wherein the outdoor units include:

[0051] Outdoor casing,

[0052] A compressor, which includes an intake port and an exhaust port;

[0053] A gas-liquid separator, located at the suction port of the compressor, is used for gas-liquid separation;

[0054] An outdoor heat exchanger, located inside an outdoor casing, is used to exchange heat with outdoor air.

[0055] The four-way valve has its first port connected to the compressor's exhaust port, its second port connected to the compressor's intake port, its third port connected to the indoor unit, and its fourth port connected to the outdoor heat exchanger.

[0056] The subcooler is located between the outdoor heat exchanger and the indoor unit;

[0057] The second electronic expansion valve is used to control the degree of subcooling of the subcooler;

[0058] Multi-split air conditioners also include:

[0059] A pressure detection device, located in the pipeline between the compressor and the four-way valve, is used to detect the compressor's suction pressure.

[0060] The controller is configured to control at least one outdoor unit to be in an operating mode and in a heating mode, and at least one outdoor unit to be in a shutdown mode, defining the outdoor unit in the operating mode and in the heating mode as the operating outdoor unit, and defining the outdoor unit in the shutdown mode as the shutdown outdoor unit.

[0061] The second electronic expansion valve of the outdoor unit is in the off state, and the corresponding intake pressure of the outdoor unit is obtained at a set time interval.

[0062] If the suction pressure value shows an upward trend over a certain period of time, it is determined that the gas-liquid separator of the outdoor unit that is shut down is experiencing liquid return.

[0063] The above embodiment detects the trend change of the suction pressure value to determine whether liquid return occurs in the gas-liquid separator, and determines whether the second electronic expansion valve cannot close properly based on whether liquid return occurs, so as to prevent the gas-liquid separator from becoming full of liquid and damaging the compressor.

[0064] In some embodiments, the multi-split air conditioner further includes:

[0065] A coil temperature detection device is installed on the outdoor heat exchanger to detect the coil temperature of the outdoor heat exchanger.

[0066] An ambient temperature detection device, located on the outside of the outdoor casing, is used to detect the outdoor ambient temperature.

[0067] The controller is configured to: control at least one outdoor unit to be in operating mode and in heating mode, and at least one outdoor unit to be in shutdown mode, defining the outdoor unit in operating mode as the operating outdoor unit and the outdoor unit in shutdown mode as the shutdown outdoor unit.

[0068] The second electronic expansion valve of the outdoor unit is closed when it is shut down, and the outdoor coil temperature and outdoor ambient temperature of the outdoor unit are obtained at set time intervals.

[0069] When the difference between the coil temperature of the outdoor heat exchanger and the detected ambient temperature reaches a preset difference, it is determined that the gas-liquid separator has experienced liquid return.

[0070] By detecting the difference between the coil temperature of the outdoor heat exchanger and the ambient temperature, it can be determined whether liquid return has occurred in the gas-liquid separator. Based on whether liquid return has occurred, it can be determined whether the second electronic expansion valve is unable to close properly, thus preventing the gas-liquid separator from becoming full of liquid and damaging the compressor. Attached Figure Description

[0071] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0072] Figure 1 This is a structural block diagram of a multi-split air conditioner according to one embodiment of the present invention;

[0073] Figure 2 This is a structural block diagram of a multi-split air conditioner with two outdoor units according to one embodiment of the present invention;

[0074] Figure 3 This is a system block diagram of an air conditioning system according to one embodiment of the present invention;

[0075] Figure 4 This is the trend of air intake pressure variation between a normal outdoor unit and a liquid return outdoor unit in one embodiment of the present invention;

[0076] Figure 5 This is the trend of the difference between the coil temperature and the outdoor ambient temperature of the normal outdoor unit and the liquid return outdoor unit in one embodiment of the present invention.

[0077] Figure 6 This is a structural block diagram of the outdoor unit in this application;

[0078] Figure 7 This is a hardware block diagram of the controller in one embodiment of the present invention;

[0079] Figure 8 This is the control logic for determining whether the gas-liquid separator returns liquid in one embodiment of the present invention;

[0080] Figure 9 This is another control logic for determining whether the gas-liquid separator returns liquid in one embodiment of the present invention;

[0081] Figure 10 This is the unit rotation control logic in one embodiment of the present invention;

[0082] Figure 11 This is another control logic for determining whether the gas-liquid separator returns liquid in one embodiment of the present invention;

[0083] Figure 12 This is a structural block diagram of a multi-split air conditioner according to one embodiment of the present invention;

[0084] In the above image:

[0085] Multi-split air conditioner 100; First branch pipe 23; Second branch pipe 24;

[0086] Controller 21; Bus 211; Memory 212; Processor 213; Communication interface 214.

[0087] 1. Compressor; 2. Check valve; 3. High-pressure detection device; 4. Four-way valve; 5. Pressure detection device;

[0088] 6. Gas-liquid separator; 7. First electronic expansion valve; 8. Outdoor heat exchanger; 9. Gas-side shut-off valve;

[0089] Liquid-side shut-off valve 10; subcooler 11; second electronic expansion valve 12;

[0090] 13. Coil temperature detection device; 15. Ambient temperature detection device; 14. Outdoor unit; 16. Indoor unit. Detailed Implementation

[0091] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0092] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0093] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0094] This application discloses a multi-split air conditioner 100, with reference to... Figure 1The multi-split air conditioner 100 includes 16 indoor units, and each of the 16 indoor units includes at least one indoor unit 16.

[0095] The indoor unit group 16 includes multiple indoor units 16. The multiple indoor units 16 are connected in parallel.

[0096] The multi-split air conditioner 100 includes 14 outdoor units.

[0097] The outdoor unit group 14 includes at least two outdoor units 14. The indoor units 16 are connected in parallel.

[0098] Outdoor unit 14 is installed outdoors. Indoor unit 16 and outdoor unit 14 are connected by pipes for refrigerant flow.

[0099] The indoor unit 16 includes an indoor housing. The indoor housing forms the outer contour of the indoor unit 16 and houses the internal components of the indoor unit 16.

[0100] The interior casing has an interior air inlet. The interior air inlet is used to allow indoor air to enter the interior casing.

[0101] The inner casing has an indoor air outlet. The indoor air outlet is used to exhaust air from the inner casing. Indoor air enters the inner casing through the indoor air inlet and is then blown out from the indoor air outlet.

[0102] The indoor unit 16 includes an indoor heat exchanger. The indoor heat exchanger is installed inside the indoor casing. The indoor heat exchanger is used to exchange heat with indoor air entering the indoor casing.

[0103] The indoor unit 16 includes an indoor fan. The indoor fan is installed inside the indoor casing. The indoor fan rotates to allow indoor air to enter the indoor casing. After exchanging heat with the indoor heat exchanger, the indoor air flows out of the indoor casing.

[0104] In this application, indoor unit 16 includes, but is not limited to, wall-mounted air conditioners, cabinet air conditioners, and ducted air conditioners.

[0105] The outdoor unit 14 includes an outdoor housing. The outdoor housing forms the outer outline of the outdoor unit 14 and houses the internal components of the outdoor unit 14.

[0106] The outdoor casing has an outdoor air inlet, which is used to allow outdoor air to enter the outdoor casing.

[0107] The outdoor casing has an outdoor air outlet, which is used to exhaust air from the outdoor casing. Outdoor air enters the outdoor casing through the outdoor air inlet and is then blown out from the outdoor air outlet.

[0108] The outdoor unit 14 includes an outdoor heat exchanger 8, which is installed inside the outdoor casing and is used to exchange heat with the outdoor air entering the outdoor casing.

[0109] The outdoor unit 14 includes an outdoor fan, which is installed inside the outdoor casing. The outdoor fan rotates to allow outdoor air to enter the outdoor casing. After exchanging heat with the outdoor heat exchanger 8, the outdoor air flows out of the outdoor casing.

[0110] Reference Figure 3 , 12 This describes the system configuration of the air conditioning system in this application.

[0111] The outdoor unit 14 includes a compressor 1. The compressor 1 can compress the gaseous refrigerant at high temperature and high pressure and discharge the compressed gaseous refrigerant.

[0112] Compressor 1 includes an intake port. Refrigerant flows into compressor 1 from the intake port to be compressed.

[0113] Compressor 1 includes an exhaust port. Refrigerant enters compressor 1 through the suction port, is compressed by compressor 1, and is discharged through the exhaust port.

[0114] The outdoor unit 14 also includes a gas-liquid separator 6. The gas-liquid separator 6 is installed at the suction port of the compressor 1. The gas-liquid separator 6 is used for gas-liquid separation.

[0115] The outdoor unit 14 also includes a four-way valve 4. The first port of the four-way valve 4 is connected to the discharge port of the compressor 1. The second port of the four-way valve 4 is connected to the suction port of the compressor 1. The third port of the four-way valve 4 is connected to the indoor unit 16. The fourth port of the four-way valve 4 is connected to the outdoor heat exchanger 8.

[0116] The outdoor unit 14 also includes a first electronic expansion valve 7. The first electronic expansion valve 7 is disposed between the outdoor heat exchanger 8 and the indoor heat exchanger. The first electronic expansion valve 7 is used for throttling. The first electronic expansion valve 7 causes the high-temperature, high-pressure liquid refrigerant condensed in the condenser to expand into a low-pressure liquid refrigerant.

[0117] The outdoor unit 14 also includes a one-way valve 2. The one-way valve 2 is located at the discharge port of the compressor 1. The one-way valve 2 is installed between the discharge port of the compressor 1 and the first port of the four-way valve 4. It is used to prevent refrigerant in the pipeline from flowing back into the compressor 1.

[0118] The outdoor unit 14 also includes a gas-side shut-off valve 9. The gas-side shut-off valve 9 is located at the third port of the four-way valve 4.

[0119] The outdoor unit 14 also includes a liquid-side shut-off valve 10, which is located between the indoor unit 16 and the subcooler 11.

[0120] The indoor and outdoor heat exchangers 8 function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode. When the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0121] Multi-split air conditioners 100 use refrigerant flow to blow out air that is higher or lower than the indoor temperature, or the same as the indoor temperature, in order to adjust the temperature and humidity of the indoor environment; or they use the speed of the indoor fan to adjust the airflow speed of the indoor environment.

[0122] Taking one of the outdoor units 14 as an example, we will explain the cooling and heating modes of the multi-split air conditioner 100.

[0123] When the multi-split air conditioner 100 is in cooling mode, the refrigerant from compressor 1 is condensed by the outdoor heat exchanger 8. The condensed refrigerant then expands by the first electronic expansion valve 7. The expanded condensate evaporates by the indoor heat exchanger. The evaporated refrigerant then circulates back to compressor 1.

[0124] When the multi-split air conditioner 100 is in heating mode, the refrigerant from compressor 1 flows through the indoor heat exchanger and condenses. The condensed refrigerant then expands by flowing through the first electronic expansion valve 7. The expanded condensate evaporates through the outdoor heat exchanger 8. The evaporated refrigerant then circulates back to compressor 1.

[0125] This application primarily addresses the issue of liquid return at the suction end of compressor 1. In cooling mode, due to the higher outdoor temperature and refrigerant flow, liquid return from the gas-liquid separator 6 is generally not an issue. Therefore, the technical solution in this application mainly focuses on the component control of the outdoor unit 14 when the multi-split air conditioner 100 is in heating mode, in order to solve the liquid return problem of compressor 1 in the outdoor unit 14.

[0126] In some embodiments of this application, the multi-split air conditioner 100 includes a remote control. The user inputs commands to the controller 21 via the remote control to select the operating modes of the indoor unit 16 and the outdoor unit 14.

[0127] In some implementations, the operating modes of the multi-split air conditioner 100 vary depending on the model and user needs. In this application, cooling mode, heating mode and shutdown mode are selected for description.

[0128] In the cooling mode, the air flowing from the indoor unit 16 into the room is cold air. This cold air can be defined as airflow that is lower than the indoor air temperature.

[0129] In heating mode, the air flowing from the indoor unit 16 into the room is hot air. This hot air can be defined as airflow with a temperature higher than the indoor air temperature. The concepts of heating and cooling modes are common knowledge to those skilled in the art.

[0130] In the shutdown mode, the multi-split air conditioner 100 does not improve indoor parameters such as temperature, humidity, and airflow speed.

[0131] In some embodiments of this application, the multi-split air conditioner 100 includes a controller 21. The controller 21 is used to send instructions to the multi-split air conditioner 100 to control the working process of the multi-split air conditioner 100.

[0132] The controller 21 includes an indoor controller 21. The indoor controller 21 is installed in the indoor unit 16. The indoor controller 21 can be used to control the operating status of various components inside the indoor unit 16.

[0133] The controller 21 includes an outdoor controller 21. The outdoor controller 21 is installed in the outdoor unit 14. The outdoor controller 21 can be used to control the operating status of various components inside the outdoor unit 14.

[0134] The indoor controller 21 and the outdoor controller 21 communicate via wired communication.

[0135] In other embodiments, the above-described communication method may also be wireless communication.

[0136] In this application, the outdoor controller 21 is used to read the detection values ​​of the pressure detection device 5, the coil temperature detection device 13 and the ambient temperature detection device 15 at a set time after receiving a shutdown command, and compare them with the set conditions to determine whether to shut down the outdoor unit 14 or whether liquid return has occurred, so as to solve the liquid return problem of the compressor 1 to a certain extent.

[0137] Meanwhile, the outdoor controller 21 and the indoor controller 21 can also rotate the units according to the hardware conditions, running time, and actual working conditions of each indoor unit 16 and each outdoor unit 14, so as to achieve efficient cooperation between each indoor unit 16 and each outdoor unit 14.

[0138] In some embodiments of this application, the indoor controller 21 and the outdoor controller 21 are not specifically distinguished, and are collectively referred to as controller 21.

[0139] The controller 21 is used to coordinate the operation of the entire multi-split air conditioner 100. This includes receiving user commands, operating in various modes such as cooling mode, heating mode, fan mode, and shutdown mode, as well as uploading the operating status of the multi-split air conditioner 100 to the cloud.

[0140] The indoor controller 21 and the outdoor controller 21 have roughly the same structure. The structure of the indoor controller 21 will be explained using the indoor controller 21 as an example.

[0141] The indoor controller 21 includes a memory 212. The memory 212 may include high-speed random access memory (RAM) or non-volatile memory (NVM).

[0142] For example, at least one disk storage device 212. Storage device 212 is used to store programs.

[0143] Reference Figure 7 The indoor controller 21 includes a communication interface 214. The communication interface 214 is used to communicate with related components.

[0144] The communication interface 214 of the indoor controller 21 is used to communicate with the indoor unit expansion valve and the outdoor controller 21. The communication interface 214 of the outdoor controller 21 is used to communicate with the pressure detection device 5, the coil temperature detection device 13, the ambient temperature detection device 15, and the indoor controller 21.

[0145] The indoor controller 21 includes a processor 213. The processor 213 is used to execute executable modules stored in the memory 212, such as computer programs. The code of the computer program can be in the form of source code, object code, executable file, or some of these forms.

[0146] The indoor controller 21 includes a bus 211. The bus 211 is used to connect the communication interface 214 and the processor 213. The bus 211 can be an ISA bus 211, a PCI bus 211, or an EISA bus 211, etc.

[0147] The outdoor controller 21 of the outdoor unit 14 and the indoor controller 21 of each indoor unit 16 each include at least one software function module that can be stored in the memory 212 in the form of software or firmware.

[0148] In this application, after receiving an execution instruction, the processor 213 executes the program to implement... Figure 8-9 The detection method for the reflux of the gas-liquid separator 6 shown in Figure 11 and Figure 10 The unit rotation control method shown is illustrated.

[0149] In some embodiments of this application, the controller 21 is used to control at least the compressor 1, the indoor fan, the outdoor fan, the first electronic expansion valve 7, and the second electronic expansion valve 12.

[0150] The controller 21 can obtain the start-up status and operating status of each air conditioning unit (i.e., each indoor unit 16 and each outdoor unit 14).

[0151] The power-on / off status includes the power-on state and the power-off state; the operating status includes the operating parameters in the power-on state, the operating parameters stored in the power-off state, and the detection parameters in the power-off state.

[0152] The operating parameters stored in the power-off state include power-off duration. The detection parameters in the power-off state include coil temperature Te, suction pressure, and ambient temperature Ta.

[0153] In some embodiments, multiple outdoor units 14 are connected via a first branch pipe 23. Multiple indoor units 16 are connected via a second branch pipe 24. The first branch pipe 23 and the second branch pipe 24 are connected.

[0154] Reference Figure 2 Taking two outdoor units 14 and two indoor units 16 as an example, the two indoor units 16 are connected to the second branch pipe 24 respectively, and the two outdoor units 14 are connected to the first branch pipe 23 respectively. The first branch pipe 23 and the second branch pipe 24 are connected.

[0155] The controller 21 can manage multiple air conditioning units and configure the rotation time and the rotation relationship between the air conditioning units in order to rotate the operation of each air conditioning unit.

[0156] The rotation relationship refers to the relationship between the current air conditioning unit a and the air conditioning unit b to be rotated. That is, when the current air conditioning unit a needs to be rotated, air conditioning unit b is selected for rotation.

[0157] The controller 21 can control the operating status of each air conditioning unit according to the operation rotation time, on / off status and rotation relationship.

[0158] In some embodiments, the controller 21 performs rotation not only based on the calculated rotation time, but also based on the operating status of each air conditioning unit. For example, when an air conditioning unit malfunctions, rotation is not performed.

[0159] In this application, when the load on the indoor unit 16 is low, the frequency of demand is low. At this time, it is not necessary for all outdoor units 14 to work; both the operation module and the shutdown module will exist simultaneously. That is, some outdoor units 14 are set to be in the operation state, while some outdoor units 14 are in the shutdown state.

[0160] In this application, an outdoor unit 14 in operation is defined as an operating outdoor unit 14, and an outdoor unit 14 in shutdown is defined as a shutdown outdoor unit 14.

[0161] In some embodiments, an outdoor unit 14 that is in operation and in heating mode is defined as an operating outdoor unit 14.

[0162] Under normal operating conditions of all components of the multi-split air conditioner 100, the electronic expansion valve of the outdoor unit 14 (when shut down) is closed. However, because the gas-liquid pipes between the modules are connected in parallel, if the electronic expansion valve of the outdoor unit 14 (when shut down) fails to close properly and refrigerant leaks, the refrigerant in the operating outdoor unit 14 will flow through the leaking electronic expansion valve into the gas-liquid separator 6 of the outdoor unit 14 (when shut down). If not addressed promptly, the gas-liquid separator 6 will become saturated with liquid.

[0163] If the load on the air conditioning system changes or the air conditioning units reach the rotation conditions, the outdoor unit 14 that was shut down needs to be started.

[0164] The above-mentioned rotation conditions can be such as running time, compressor 1 damage or other faults, increased load, and liquid return from the outdoor unit 14 when it is shut down. The above-mentioned rotation conditions can be executed according to different priorities.

[0165] In some embodiments, when the load increases and the frequency of the existing compressor 1 cannot meet the requirements, the frequency will be increased. When the frequency increases to a certain value, the outdoor unit 14 will be restarted. At this time, since the gas-liquid separator 6 of the outdoor unit 14 is full of refrigerant, when the outdoor unit 14 is turned on, the refrigerant will enter the compressor 1 through the suction pipe. The compressor 1 of the outdoor unit 14 may be damaged due to liquid return.

[0166] The multi-split air conditioner 100 includes a pressure detection device 5. The pressure detection device 5 is installed on the pipeline between the compressor 1 and the four-way valve 4. It is used to detect the suction pressure of the compressor 1.

[0167] In some embodiments, the pressure detection device 5 is installed on the pipeline between the compressor 1 and the gas-liquid separator 6.

[0168] In some embodiments, the pressure detection device 5 is installed on the pipeline between the gas-liquid separator 6 and the second port of the four-way valve 4.

[0169] In some embodiments, the pressure detection device 5 is configured as a pressure sensor. The pressure sensor is located at the suction port of the compressor 1 and is used to detect the suction pressure of the compressor 1.

[0170] By detecting changes in the suction pressure of compressor 1, it can be determined whether liquid return has occurred in gas-liquid separator 6.

[0171] In some embodiments, the multi-split air conditioner 100 also includes a high-pressure detection device 3. It is located between the compressor 1 and the four-way valve 4. It is used to detect high pressure to prevent excessively high pipeline pressure from affecting the normal operation of the air conditioner.

[0172] In some embodiments, the controller 21 is configured to control at least one outdoor unit 14 to be in an operating mode and a heating mode, and at least one outdoor unit 14 to be in a shutdown mode. An outdoor unit 14 in the operating mode and heating mode is defined as an operating outdoor unit 14, and an outdoor unit 14 in the shutdown mode is defined as a shut-down outdoor unit 14.

[0173] At this time, the first electronic expansion valve 7 of the outdoor unit 14 is in the off state, and the suction pressure corresponding to the compressor 1 of the outdoor unit 14 is obtained at a set time interval.

[0174] When the suction pressure value changes upward within a certain time period, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down is experiencing liquid return, and the first electronic expansion valve 7 cannot close normally.

[0175] It is known that under normal circumstances, when the outdoor unit 14 stops working, its first electronic expansion valve 7 is closed, there is no refrigerant flowing inside the outdoor unit 14, and its suction pressure is stable. When the first electronic expansion valve 7 leaks, the refrigerant will flow along the first leakage circuit into the gas-liquid separator 6 of the outdoor unit 14, and the suction pressure of the outdoor unit 14 will gradually increase.

[0176] In some embodiments, refer to Figure 3 The blue arrow in the middle indicates the circuit. The first leakage circuit is the other operating outdoor unit 14, the first electronic expansion valve 7, the outdoor heat exchanger 8, the four-way valve 4, and the gas-liquid separator 6.

[0177] In the above embodiment, the suction pressure of the shut-down outdoor unit 14 is detected to determine whether liquid return occurs in the gas-liquid separator 6, and to infer whether the first electronic expansion valve 7 is leaking, so as to detect the liquid return phenomenon in time, avoid damage to the compressor 1 due to liquid return when it is restarted, and ensure the stable operation of the air conditioning system.

[0178] The outdoor unit 14 also includes a subcooler 11. The subcooler 11 is located on the side of the outdoor heat exchanger 8 near the indoor unit 16.

[0179] In some embodiments, the subcooler 11 is disposed between the first electronic expansion valve 7 and the indoor unit group 16. The first end of the subcooler 11 is connected to the first electronic expansion valve 7, and the second end of the subcooler 11 is connected to the indoor heat exchanger of the indoor unit group 16.

[0180] The outdoor unit 14 also includes a second electronic expansion valve 12 for controlling the subcooling of the subcooler 11.

[0181] In some embodiments, the controller 21 is configured such that both the first electronic expansion valve 7 and the second electronic expansion valve 12 of the outdoor unit 14 are closed, and the suction pressure of the compressor 1 of the outdoor unit 14 is acquired at set time intervals.

[0182] When the suction pressure value is on an upward trend within a certain time period, it is determined that the gas-liquid separator 6 is experiencing liquid return, and the first electronic expansion valve 7 and / or the second electronic expansion valve 12 cannot close normally.

[0183] The phrase "the first electronic expansion valve 7 and the second electronic expansion valve 12 are in the closed state" refers to the fact that the first electronic expansion valve 7 and the second electronic expansion valve 12 are set to be in the closed state. This does not affect the actual state where the electronic expansion valves cannot close properly due to impurities or damage.

[0184] Reference Figure 8 This explains the control logic for whether the gas-liquid separator 6 returns liquid in this application.

[0185] In some embodiments, when the multi-split air conditioner 100 is operating, the indoor unit 16 continues to turn on and off according to user needs. The outdoor unit 14 turns on or off according to the needs of the air conditioning system (S800).

[0186] In some embodiments, the suction pressure Ps of the outdoor unit 14 that is shut down is detected, and it is determined whether the trend of the suction pressure value is an upward trend within a certain period of time, that is, Ps(n) > Ps(n-1) for a certain period of time (S801).

[0187] It should be noted that Ps(n) is the current detected Ps value, and Ps(n-1) is the Ps value detected x seconds ago.

[0188] In some embodiments, x can be set to be greater than the first parameter. If the value of x is too small, it may cause data processing pressure on the controller 21. Therefore, x is made to be greater than the first parameter, for example, the first parameter is 15S, 20S, or 25S. In specific design, consider choosing a suitable specific parameter.

[0189] Furthermore, if x is too large, it may prevent the timely detection of changes in inspiratory pressure, thus hindering the timely detection of liquid return. Therefore, x should be less than the second parameter, which is 25S, 30S, or 35S. A suitable specific parameter should be considered in the actual design.

[0190] In some embodiments, when the trend of the change in the suction pressure value within a certain period of time is an upward trend, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has experienced liquid return (S802).

[0191] In some embodiments, when the trend of the inhalation pressure value over a certain period of time is an upward trend, it is determined that the first electronic expansion valve 7 cannot close normally (S803).

[0192] In some embodiments, when the trend of the inhalation pressure value over a certain period of time is an upward trend, it is determined that the second electronic expansion valve 12 cannot close normally (S804).

[0193] In some implementations, some of the operations described above for determining whether the gas-liquid separator 6 is returning liquid may be optionally combined, and / or the order of some operations may be optionally changed.

[0194] It is known that, by reference Figure 4 Under normal circumstances, when the outdoor unit 14 stops working, both the first electronic expansion valve 7 and the second electronic expansion valve 12 are closed, there is no refrigerant flow inside the outdoor unit 14, and its suction pressure is stable. (Refer to...) Figure 4 The blue line indicates that when the first electronic expansion valve 7 leaks, the refrigerant will flow along the first leakage circuit, or when the second electronic expansion valve 12 leaks, the refrigerant will flow along the second leakage circuit into the gas-liquid separator 6 of the off outdoor unit 14, causing the suction pressure of the off outdoor unit 14 to gradually increase. (See the attached diagram for details.) Figure 4 The red line in the middle of the graph.

[0195] In the above embodiment, the suction pressure of the outdoor unit 14 that is shut down is detected to determine whether liquid return occurs in the gas-liquid separator 6, and to infer whether the first electronic expansion valve 7 or / and the second electronic expansion valve 12 is leaking, so as to detect the liquid return phenomenon in time, avoid damage due to liquid return when the compressor 1 is restarted, and ensure the stable operation of the air conditioning system.

[0196] In some embodiments, refer to Figure 3 The red arrow indicates the circuit; the second leakage circuit includes other operating outdoor units 14, the second electronic expansion valve 12, and the gas-liquid separator 6.

[0197] The multi-split air conditioner 100 also includes a coil temperature detection device. The coil temperature detection device 13 is installed on the outdoor heat exchanger 8 and is used to detect the coil temperature of the outdoor heat exchanger 8.

[0198] In some embodiments, the coil temperature detection device 13 is installed on the liquid-side capillary of the outdoor heat exchanger 8.

[0199] In some embodiments, the coil temperature detection device 13 is configured as a temperature sensor for detecting the coil temperature of the outdoor heat exchanger 8.

[0200] The multi-split air conditioner 100 also includes an ambient temperature detection device 15. The ambient temperature detection device 15 is installed on the ribs of the outdoor casing and is used to detect the outdoor ambient temperature.

[0201] In some embodiments, the ambient temperature detection device 15 is configured as a temperature sensor. The temperature sensor is connected to the controller 21. The temperature sensor detects the outdoor ambient temperature and sends the outdoor ambient temperature to the controller 21.

[0202] In some embodiments, the wiring of the temperature sensor passes through the inside of the side cover of the outdoor housing and is secured to the reinforcing rib with wire ties.

[0203] In some embodiments, the controller 21 is configured to acquire the suction pressure, outdoor coil temperature and outdoor ambient temperature of the outdoor unit 14 at corresponding set time intervals when the first electronic expansion valve 7 of the outdoor unit 14 is in the closed state.

[0204] When the trend of the suction pressure value changes upward within a certain period of time or / and the difference between the outdoor coil temperature Te of the outdoor heat exchanger 8 and the detected outdoor ambient temperature Ta reaches the preset difference m, it is determined that the gas-liquid separator 6 has a liquid return phenomenon, and the first electronic expansion valve 7 cannot close normally.

[0205] It is known that, by reference Figure 5 Under normal circumstances, when the outdoor unit 14 stops working, its first electronic expansion valve 7 is closed, there is no refrigerant flow inside the outdoor unit 14, its suction pressure is stable, and the coil temperature of the outdoor heat exchanger 8 is close to the ambient temperature. The trend of the difference between the coil temperature and the outdoor ambient temperature, Te-Ta, is referenced. Figure 5 The blue line in the middle.

[0206] When the first electronic expansion valve 7 leaks, refrigerant flows along the first refrigerant circuit into the gas-liquid separator 6 of the off outdoor unit 14. Since the refrigerant flowing into the off outdoor unit 14 originates from the operating outdoor unit 14, its temperature is higher than the ambient temperature. Therefore, the coil temperature of the outdoor heat exchanger 8 of the off outdoor unit 14 will gradually exceed the ambient temperature. As more and more refrigerant flows in, the temperature difference between the coil temperature and the ambient temperature of the off outdoor unit 14 will increase. The trend of the Te-Ta value (temperature difference between the coil temperature and the outdoor ambient temperature) is shown in the figure. Figure 5 The red line in the graph.

[0207] In the above embodiment, by detecting the temperature difference between the coil temperature of the shut-down outdoor unit 14 and the ambient temperature, it is determined whether a backflow phenomenon has occurred in the gas-liquid separator 6 of the shut-down outdoor unit 14, which facilitates timely alarm or corresponding logical response (exemplarily, activating the unit rotation mechanism). This prevents the compressor 1 from failing to start normally due to liquid backflow.

[0208] In some embodiments, the detection cycle of intake pressure, the detection cycle of outdoor coil temperature, and the detection cycle of outdoor ambient temperature can be the same, or they can be set differently according to requirements and the computing power of the hardware.

[0209] Reference Figure 9 This explains the control logic for whether the gas-liquid separator 6 returns liquid in this application.

[0210] In some embodiments, when the multi-split air conditioner 100 is operating, the indoor unit 16 continues to turn on and off according to user needs. The outdoor unit 14 turns on or off according to the needs of the air conditioning system (S900).

[0211] In some embodiments, the suction pressure of the shut-down outdoor unit 14 is detected, and it is determined whether the trend of the suction pressure value over a certain period of time is an upward trend (S901).

[0212] In some embodiments, the coil temperature of the shut-down outdoor unit 14 and the outdoor ambient temperature are detected, and it is determined whether the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches the preset difference m (step S905).

[0213] In some embodiments, when the trend of the suction pressure value within a certain period of time is an upward trend or the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches a preset difference m, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has a liquid return phenomenon (S902).

[0214] In some embodiments, when the trend of the intake pressure value changes upward within a certain period of time or the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches a preset difference m, it is determined that the first electronic expansion valve 7 cannot close normally (S903).

[0215] In some embodiments, when the trend of the change in the suction pressure value over a certain period of time is an upward trend or the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches a preset difference m, it is determined that the second electronic expansion valve 12 cannot close normally (S904).

[0216] In some implementations, some of the operations described above for determining whether the gas-liquid separator 6 is returning liquid may be optionally combined, and / or the order of some operations may be optionally changed.

[0217] In some embodiments, the controller 21 is configured to acquire the suction pressure, outdoor coil temperature and outdoor ambient temperature of the outdoor unit 14 at a set time interval when the first electronic expansion valve 7 and the second electronic expansion valve 12 of the outdoor unit 14 is closed.

[0218] When the suction pressure is on an upward trend within a certain period of time or / and the difference between the outdoor coil temperature of the outdoor heat exchanger 8 and the detected outdoor ambient temperature Te-Ta reaches the preset difference m, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has a liquid return phenomenon, and the first electronic expansion valve 7 and / or the second electronic expansion valve 12 cannot close normally.

[0219] In the above embodiments, whether liquid return has occurred in the gas-liquid separator 6 of the outdoor unit 14 when it is shut down can be determined by combining the difference between the coil temperature and the outdoor ambient temperature (Te-Ta) and the trend of the suction pressure. Alternatively, one of the parameters can be used to determine whether liquid return has occurred in the gas-liquid separator 6. This allows for timely judgment of liquid return even if some detection devices of the outdoor unit 14 when it is shut down are damaged or missing, based on another parameter.

[0220] In some embodiments, when liquid return is detected in the shut-down outdoor unit 14, the unit can be directly rotated.

[0221] In some embodiments, the outdoor unit 14 with the longest operating time can be selected for unit rotation in order to resolve the problem of the shut-down outdoor unit 14 experiencing liquid return as soon as possible and prevent the compressor 1 from failing to start normally.

[0222] In some embodiments, when a liquid return phenomenon is detected in the shut-down outdoor unit 14, the controller 21 sends a start-up signal to start the shut-down outdoor unit 14, allowing refrigerant to flow into the pipeline. This enables refrigerant flow at the location of the first electronic expansion valve 7 and / or the second electronic expansion valve 12 to flush out foreign objects present at that location, resolving the situation where the first electronic expansion valve 7 and / or the second electronic expansion valve 12 cannot close due to foreign objects, thereby solving the liquid return problem of the gas-liquid separator 6.

[0223] In this embodiment of the application, when a liquid return phenomenon is detected in the outdoor unit 14 which is in the off state, the units can be rotated directly, or all units can be shut down and then turned on again.

[0224] It is known that when the system is turned on again, the outdoor unit 14 that has experienced liquid return and the air conditioning unit with the shortest operating time will be selected first.

[0225] In this application, the outdoor unit 14 of the unit has multiple rotation rules. Different rotation rules have different priorities.

[0226] The controller 21 can rotate the outdoor unit 14 based on the outdoor unit 14's operating time and whether liquid return occurs.

[0227] In some embodiments, the controller 21 is configured to: when it is determined that the gas-liquid separator 6 of the shut-down outdoor unit 14 has experienced liquid return, after a set time, turn on the corresponding shut-down outdoor unit 14 so that the refrigerant flows through the corresponding pipeline.

[0228] In some embodiments, the running time of each outdoor unit 14 is recorded. When the units are rotated, the running time and downtime of each outdoor unit 14 are compared, and the outdoor unit 14 with the shorter running time is turned on first.

[0229] In some embodiments, during unit rotation, when both the outdoor unit 14 experiencing liquid return and the outdoor unit 14 with less operating time are simultaneously shut down, the outdoor unit 14 experiencing liquid return is turned on first.

[0230] In this application, the rotation rules prioritize the opening of outdoor units 14 that have experienced liquid return over those that have been shut down for a shorter period of time. This is to resolve the issue of electronic expansion valves failing to close properly due to foreign objects as quickly as possible.

[0231] By rotating the units, foreign objects blocking the electronic expansion valve can be flushed away, allowing the electronic expansion valve to close completely.

[0232] In some embodiments of this application, the outdoor unit 14 includes at least two compressors 1. Different compressors 1 of the same outdoor unit 14 are connected in parallel. The compressors 1 can be selected to operate individually or in combination.

[0233] When calculating the working time of outdoor unit 14, the working time of compressor 1 can be used as a reference to uniformize the working time of all compressors 1 in outdoor unit 14.

[0234] Reference Figure 6 The following explanation will be based on two outdoor units 14, each of which includes two compressors 1.

[0235] The outdoor unit 14 includes outdoor unit 14A and outdoor unit 14B, with outdoor unit 14A serving as the main unit and outdoor unit 14B serving as the slave unit. Both outdoor unit 14A and outdoor unit 14B have two compressors 1, which are defined as MC1 and MC2.

[0236] In some embodiments, for modular combined units, it is necessary to further homogenize the operating time of the variable frequency compressors 1 installed in each of the 14 outdoor units. After each unit shutdown, upon restarting, the compressor 1 with the shortest cumulative operating time within the modular unit will be started first. Figure 6 Taking two sets of outdoor units 14 as an example, the startup sequence of outdoor unit 14 is specified.

[0237] After the four compressors 1 are reset, their cumulative operating times are 100 min, 80 min, 70 min, and 110 min. Based on the smaller value of the cumulative operating time of compressors MC1 and MC2 in each outdoor unit 14, a module operation table is created to facilitate the statistical analysis of the operation of outdoor unit 14. See the table below for the module operation table header.

[0238] Time / min 80 70

[0239] In some embodiments, based on the cumulative operating time of each compressor 1, the MC1 of the outdoor unit 14B is preferentially used for operation.

[0240] In some embodiments, one of the outdoor units 14 can be randomly selected to operate based on the combined operating time of the compressors 1 of the two outdoor units 14.

[0241] In this application, the reason for the liquid return phenomenon in the outdoor unit 14 which is in the shutdown state may be that the electronic expansion valve is not closed tightly, causing the refrigerant of other outdoor units 14 to flow into the gas-liquid separator 6 through the unclosed electronic expansion valve.

[0242] Causes of problems with electronic expansion valves include impurities at the valve's closing position preventing normal closure, and damage to the valve itself. The technical solution for resolving liquid return in this application only addresses situations where impurities prevent the electronic expansion valve from closing.

[0243] In some embodiments, the controller 21 is configured to, after determining that the outdoor unit 14 that has experienced liquid return has been turned on, wait for it to be turned off again, and if it is still determined that the gas-liquid separator 6 of the outdoor unit 14 has experienced liquid return after being turned off, continue to turn on the outdoor unit 14 first.

[0244] If the outdoor unit 14 is turned on a set number of times and is still judged to have liquid return after being turned off again, the electronic expansion valve of the outdoor unit 14 is determined to be damaged and an alarm is triggered.

[0245] The aforementioned electronic expansion valves include a first electronic expansion valve 7 and a second electronic expansion valve 12. An alarm will sound if staff or managers detect a malfunction in the electronic expansion valve of the outdoor unit 14, requiring repair.

[0246] In some embodiments, other electronic expansion valves may also be used to cause the gas-liquid separator 6.

[0247] Reference Figure 10 The unit rotation control method in this application is illustrated using outdoor units 14A and 14B as examples. Outdoor unit 14A is in the operating state, while outdoor unit 14B is in the stopped state.

[0248] When liquid return is detected in the gas-liquid separator 6 of outdoor unit 14B (S1001);

[0249] To prevent the gas-liquid separator 6 of outdoor unit 14B from becoming full of liquid, the unit is controlled to stop and a stop code d1-X is reported. The first electronic expansion valve 7 and the second electronic expansion valve 12 of outdoor unit 14A are reset to zero, that is, the valve opening is closed (S1002).

[0250] Three minutes later, the unit restarted, with outdoor unit 14B, whose electronic expansion valve malfunctioned, being started first. The rotation rule for this unit takes precedence over the normal module rotation rule based on the cumulative operating time within the module (S1003).

[0251] After outdoor unit 14B starts, the first electronic expansion valve 7 and the second electronic expansion valve 12 reopen. If the electronic expansion valve is stuck due to impurities, the unit will return to normal after being flushed with refrigerant; if the electronic expansion valve is damaged and cannot close properly, the electronic expansion valve will reopen (S1004).

[0252] Later, due to load changes, the outdoor unit 14B stopped again, and the electronic expansion valve would again cause the shutdown code d1-X (S1005) because it could not close properly.

[0253] If this cycle repeats multiple times, the electronic expansion valve is deemed damaged, and outdoor unit 14 will issue an alarm to stop (alarm-Y). Outdoor unit 14B will not be able to restart and will need to wait for maintenance personnel to replace the electronic expansion valve (S1006).

[0254] By rotating the units as described above, the problem of compressor 1 being damaged by liquid return caused by leakage of the electronic expansion valve of the shutdown module in the modular combination can be resolved.

[0255] In some embodiments, the outdoor unit 14 that shuts down due to liquid return includes multiple compressors 1. One compressor 1 operates for a duration longer than a preset time. During unit rotation, other compressors 1 can be prioritized for operation.

[0256] Of course, when the air conditioning system requires a larger cooling capacity, compressor 1, which operates for a longer period than the preset time, can be turned on again to meet the user's needs as quickly as possible.

[0257] The air conditioning system in some embodiments of this application has two electronic expansion valves. These include: a first electronic expansion valve 7, which is the expansion valve corresponding to the outdoor heat exchanger and functions as a throttling valve; and a second electronic expansion valve 12, which is the outdoor unit bypass electronic expansion valve and functions as a subcooling valve.

[0258] The control logic in this application is also applicable to air conditioning systems without the first electronic expansion valve 7 and air conditioning systems without the second electronic expansion valve 12.

[0259] In some embodiments of this application, the multi-split air conditioner 100 includes a subcooler 11. The subcooler 11 is disposed between the outdoor heat exchanger 8 and the indoor unit 16.

[0260] The multi-split air conditioner 100 also includes a second electronic expansion valve 12. The second electronic expansion valve 12 is used to control the subcooling degree of the subcooler 11.

[0261] The multi-split air conditioner 100 includes a pressure detection device 5, which is installed in the pipeline between the compressor 1 and the four-way valve 4. It is used to detect the suction pressure of the compressor 1. The configuration of the pressure detection device 5 in this embodiment is the same as in the above embodiments, and will not be repeated here.

[0262] In some embodiments, the controller 21 is configured to control at least one outdoor unit 14 to be in an operating mode and in a heating mode, and at least one outdoor unit 14 to be in a shutdown mode, defining the outdoor unit 14 in the operating mode and in the heating mode as the operating outdoor unit 14, and defining the outdoor unit 14 in the shutdown mode as the shutdown outdoor unit 14.

[0263] When the first electronic expansion valve 7 of the outdoor unit 14 is in the off state, the suction pressure corresponding to the outdoor unit 14 is obtained at a set time interval. When the suction pressure value changes upward within a certain period of time, it is determined that the gas-liquid separator 6 of the outdoor unit 14 is experiencing liquid return.

[0264] In some embodiments, when liquid return occurs in the gas-liquid separator 6, it is determined that the second electronic expansion valve 12 may fail to close properly, resulting in liquid return.

[0265] In some embodiments, the multi-split air conditioner 100 further includes a coil temperature detection device 13. The coil temperature detection device 13 is installed on the outdoor heat exchanger 8 and is used to detect the coil temperature of the outdoor heat exchanger 8.

[0266] The multi-split air conditioner 100 also includes an ambient temperature detection device 15. The ambient temperature detection device 15 is installed on the outside of the outdoor casing and is used to detect the outdoor ambient temperature.

[0267] In some embodiments, the controller 21 is configured such that the second electronic expansion valve 12 of the outdoor unit 14 is closed, and the coil temperature and outdoor ambient temperature corresponding to the outdoor unit 14 are acquired at set time intervals.

[0268] When the difference between the coil temperature of the outdoor heat exchanger 8 and the outdoor ambient temperature Te-Ta reaches the preset difference m, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has experienced liquid return.

[0269] Reference Figure 11 This explains the control logic for whether the gas-liquid separator 6 returns liquid in this application.

[0270] In some embodiments, when the multi-split air conditioner 100 is operating, the indoor unit 16 continues to turn on and off according to user needs. The outdoor unit 14 turns on or off according to the needs of the air conditioning system (S1100).

[0271] In some embodiments, the suction pressure of the shut-down outdoor unit 14 is detected, and it is determined whether the trend of the suction pressure value over a certain period of time is an upward trend (S1101).

[0272] In some embodiments, the coil temperature of the shut-down outdoor unit 14 and the outdoor ambient temperature are detected, and it is determined whether the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches the preset difference m (step S1103).

[0273] In some embodiments, when the trend of the suction pressure value within a certain period of time is an upward trend or the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches a preset difference m, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has a liquid return phenomenon (S1102).

[0274] In some embodiments, when the trend of the change in the suction pressure value over a certain period of time is an upward trend or the difference between the coil temperature and the outdoor ambient temperature Te-Ta reaches a preset difference m, it is determined that the second electronic expansion valve 12 cannot close normally (S1104).

[0275] In some implementations, some of the operations described above for determining whether the gas-liquid separator 6 is returning liquid may be optionally combined, and / or the order of some operations may be optionally changed.

[0276] This application proposes a multi-split air conditioner 100, which includes multiple indoor units 16 and multiple outdoor units 14. When the pressure of the indoor units 16 is low, the outdoor units 14 can partially operate. The outdoor units 14 in the shutdown mode are defined as shutdown outdoor units 14, and the outdoor units 14 in the operation mode are defined as operation outdoor units 14. In order to better detect the status of the shutdown outdoor units 14, the outdoor units 14 also include a pressure detection device 5 for detecting the suction pressure of the compressor 1. When the first electronic expansion valve 7 of the shutdown outdoor unit 14 is in the off state, the suction pressure corresponding to the shutdown outdoor unit 14 is acquired at a set time interval. When the suction pressure value changes upward within a certain period of time, it is determined that the gas-liquid separator 6 of the shutdown outdoor unit 14 has experienced liquid return.

[0277] Alternatively, the outdoor unit 14 may also be equipped with a coil temperature detection device 13 for detecting coil temperature and an ambient temperature detection device 15 for detecting ambient temperature. When the difference Te-Ta between the coil temperature and the ambient temperature of the outdoor unit 14 that is shut down reaches a preset difference m at a set time interval, it is determined that the gas-liquid separator 6 of the outdoor unit 14 that is shut down has experienced liquid return.

[0278] After determining that liquid return has occurred in the gas-liquid separator 6, the unit rotates to introduce refrigerant into the pipes of the outdoor unit 14 where liquid return has occurred to further address the liquid return issue. After multiple attempts to resolve the issue, an alarm is triggered to completely resolve the liquid return problem in the gas-liquid separator 6 and prevent damage to the compressor 1 caused by the liquid return problem.

[0279] 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.

[0280] 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 embodiments and various different variations of the embodiments suitable for specific application considerations.

Claims

1. A multi-split air conditioner, characterized in that, Also includes: An indoor unit, comprising at least one indoor unit; An outdoor unit comprising at least two outdoor units, wherein the outdoor units include: Outdoor casing; A compressor, which includes an intake port and an exhaust port; A gas-liquid separator is located at the suction port of the compressor and is used for gas-liquid separation; An outdoor heat exchanger, which is located inside the outdoor casing, is used to exchange heat with outdoor air; A four-way valve, wherein the first port of the four-way valve is connected to the exhaust port of the compressor, the second port of the four-way valve is connected to the intake port of the compressor, the third port of the four-way valve is connected to the indoor unit, and the fourth port of the four-way valve is connected to the outdoor heat exchanger; A first electronic expansion valve is disposed between the outdoor heat exchanger and the indoor unit; The multi-split air conditioner also includes: A pressure detection device, located in the pipeline between the compressor and the four-way valve, is used to detect the suction pressure of the compressor; The controller is configured to control at least one of the outdoor units to be in an operating mode and in a heating mode, and at least one of the outdoor units to be in a shutdown mode, defining the outdoor unit in the operating mode and in the heating mode as an operating outdoor unit, and defining the outdoor unit in the shutdown mode as a shutdown outdoor unit. The first electronic expansion valve of the outdoor unit that is shut down is in the off state, and the suction pressure corresponding to the outdoor unit that is shut down is obtained at a set time interval. If the trend of the change in the suction pressure value is upward within a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return. When it is determined that the shut-down outdoor unit has experienced liquid return, after a period of time, the units are rotated and the shut-down outdoor unit experiencing liquid return is turned on first. The unit rotation operation is used to flush away foreign objects blocking the electronic expansion valve, so that the electronic expansion valve can be closed normally.

2. The multi-split air conditioner according to claim 1, characterized in that, The outdoor unit also includes: A subcooler is disposed between the first electronic expansion valve and the indoor unit, with a first end of the subcooler connected to the first electronic expansion valve and a second end of the subcooler connected to the indoor unit; The second electronic expansion valve is used to control the degree of subcooling of the subcooler; The controller is configured such that the first electronic expansion valve and the second electronic expansion valve of the outdoor unit that is shut down are in a closed state, and the corresponding intake pressure of the outdoor unit that is shut down is acquired at a set time interval. If the suction pressure value changes upward within a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve and / or the second electronic expansion valve cannot close normally.

3. The multi-split air conditioner according to claim 1, characterized in that, Also includes: A coil temperature detection device is installed in the outdoor heat exchanger to detect the coil temperature of the outdoor heat exchanger. An ambient temperature detection device is installed outside the outdoor housing to detect the outdoor ambient temperature; The controller is configured to: control at least one outdoor unit to be in operating mode and in heating mode, and at least one outdoor unit to be in shutdown mode, defining the outdoor unit in operating mode and in heating mode as the operating outdoor unit, and defining the outdoor unit in shutdown mode as the shutdown outdoor unit. The first electronic expansion valve of the outdoor unit that is shut down is in a closed state, and the outdoor coil temperature and outdoor ambient temperature corresponding to the outdoor unit that is shut down are obtained at set time intervals. When the difference between the coil temperature of the outdoor heat exchanger and the detected ambient temperature reaches a preset difference, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve cannot close normally.

4. The multi-split air conditioner according to claim 2, characterized in that, Also includes: A coil temperature detection device is installed in the outdoor heat exchanger to detect the coil temperature of the outdoor heat exchanger. An ambient temperature detection device is installed outside the outdoor housing to detect the outdoor ambient temperature; The controller is configured to control at least one outdoor unit to be in an operating mode and a heating mode, and at least one outdoor unit to be in a shutdown mode, defining the outdoor unit in the operating mode and the heating mode as the operating outdoor unit, and defining the outdoor unit in the shutdown mode as the shutdown outdoor unit. The controller is configured such that the first electronic expansion valve and the second electronic expansion valve of the outdoor unit that is shut down are in a closed state, and the suction pressure, outdoor coil temperature and outdoor ambient temperature of the outdoor unit that is shut down are acquired at set time intervals. If the suction pressure value is on an upward trend within a certain period of time, it is determined that the gas-liquid separator is experiencing liquid return, and the first electronic expansion valve and / or the second electronic expansion valve cannot close normally.

5. The multi-split air conditioner according to claim 1, characterized in that, The controller is configured to record the running time of each outdoor unit and, when rotating units, prioritize turning on the outdoor unit with the shorter running time. During unit rotation, if both an outdoor unit experiencing liquid return and an outdoor unit with short operating time are simultaneously shut down, the outdoor unit experiencing liquid return should be started first.

6. The multi-split air conditioner according to claim 1, characterized in that, The controller is configured to: when the outdoor unit that has been shut down due to liquid return is turned on, and after it is turned off again, if the gas-liquid separator is still found to have liquid return after the shutdown, the outdoor unit that has been shut down will be turned on first. If the outdoor unit is turned on a set number of times after being shut down, and then shut down again, it is still judged that liquid return has occurred. In this case, the electronic expansion valve of the outdoor unit is determined to be damaged, and an alarm is triggered.

7. The multi-split air conditioner according to claim 5, characterized in that, The outdoor unit includes at least two compressors connected in parallel, and the compressors can operate individually or in combination. When calculating the operating time of the outdoor unit, the operating time of all compressors in the outdoor unit is uniformized.

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