Multi-split air conditioner

Abstract

The multi-split air conditioner comprises at least one indoor unit and at least two outdoor units, each outdoor unit comprises a compressor, a gas-liquid separator, an outdoor heat exchanger, a four-way valve and a first electronic expansion valve, and the multi-split air conditioner further comprises a pressure detection device used 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 and at least one outdoor unit to be in a shutdown mode, the outdoor unit in the running mode is defined as a running outdoor unit, and the outdoor unit in the shutdown mode is defined as a shutdown outdoor unit; a first electronic expansion valve of the shut-down outdoor unit is in a shut-down state, and air suction pressure corresponding to the shut-down outdoor unit is obtained at a set time interval; and when the change trend of the suction pressure value in a certain time period is a rising trend, judging that the gas-liquid separator has a liquid return phenomenon at the moment. Whether the gas-liquid separator has a liquid return phenomenon or not is judged by detecting the change state of the suction pressure of the compressor, so that timely treatment is facilitated, and liquid return damage of the compressor is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioners, and in particular relates to a multi-split air conditioner. Background Art

[0002] For multi-split air conditioners, there are modular combination units, that is, 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 may have both operating and shut down units. Under normal circumstances, the electronic expansion valve in the shut down unit is closed. Because the gas-liquid pipes of each outdoor unit are connected in parallel, if the electronic expansion valve of the shut down outdoor unit leaks, the operating refrigerant will flow through the leaking electronic expansion valve into the gas-liquid separator of the shut down indoor unit. If not promptly addressed, the gas-liquid separator of the shut down indoor unit will become full of liquid after a certain period of time.

[0004] When the load of the air-conditioning system changes and the outdoor unit that was previously in a stopped state needs to be started, the refrigerant in the gas-liquid separator may enter the compressor through the suction pipe at the suction port, causing damage to the compressor due to liquid backflow.

[0005] In view of this, this application is filed. Summary of the Invention

[0006] In response to the problem of liquid backflow damage to the compressor, this application proposes to detect the changing state of the compressor's suction pressure to determine whether liquid backflow occurs in the gas-liquid separator, so as to prevent the refrigerant in the gas-liquid separator from being sucked into the compressor when it is turned on next time, causing liquid backflow damage to the compressor.

[0007] The present application provides a multi-split air conditioner, which includes:

[0008] an indoor unit group, comprising at least one indoor unit;

[0009] The outdoor unit comprises at least two outdoor units, each of which includes:

[0010] outdoor housing;

[0011] a compressor including an air intake and an air discharge port;

[0012] A gas-liquid separator is provided at the air intake of the compressor for gas-liquid separation;

[0013] An outdoor heat exchanger is provided in the outdoor housing and is used to exchange heat with outdoor wind;

[0014] a four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger;

[0015] a first electronic expansion valve, which is provided between the outdoor heat exchanger and the indoor unit;

[0016] Multi-split air conditioners also include:

[0017] A pressure detection device is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor;

[0018] a controller 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 stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit;

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

[0020] When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve cannot be closed normally.

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

[0022] a subcooler, disposed between the first electronic expansion valve and the indoor unit, wherein a first end of the subcooler is connected to the first electronic expansion valve, and a second end of the subcooler is connected to the indoor unit;

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

[0024] The controller is configured to close the first electronic expansion valve and the second electronic expansion valve of the stopped outdoor unit and obtain the suction pressure corresponding to the stopped outdoor unit at a set time interval;

[0025] When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve and / or the second electronic expansion valve cannot be closed normally.

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

[0027] A coil temperature detection device is provided on the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger;

[0028] An ambient temperature detection device is provided outside the outdoor housing and is used to detect the outdoor ambient temperature;

[0029] a controller configured to: control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, define the outdoor units in the operating mode and the heating mode as operating outdoor units, and define the outdoor units in the stopping mode as stopping outdoor units;

[0030] The first electronic expansion valve of the stopped outdoor unit is in a closed state, and the outdoor coil temperature and the outdoor ambient temperature corresponding to the stopped 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 a preset difference, it is determined that liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve cannot be closed normally.

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

[0033] A coil temperature detection device is provided on the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger;

[0034] An ambient temperature detection device is provided outside the outdoor housing and is used to detect the outdoor ambient temperature;

[0035] a controller configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor units in the operating mode and the heating mode as operating outdoor units, and defining the outdoor units in the stopping mode as stopping outdoor units;

[0036] The controller is configured to obtain the suction pressure, outdoor coil temperature and outdoor ambient temperature corresponding to the stopped outdoor unit at set time intervals, with the first electronic expansion valve and the second electronic expansion valve of the stopped outdoor unit in a closed state;

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

[0038] In some embodiments, the controller is configured to: when it is determined that liquid backflow occurs in the gas-liquid separator of the stopped outdoor unit, start the corresponding stopped outdoor unit after a set time to allow the refrigerant to pass through the corresponding pipeline.

[0039] In this embodiment, the change in the compressor's suction pressure is determined to determine whether liquid backflow has occurred in the gas-liquid separator. This determines whether the compressor should be opened first the next time it is turned on, flushing out congestion in the pipeline and resolving the problem of liquid backflow in the compressor of the idle outdoor unit. This prevents the gas-liquid separator of the idle outdoor unit from being filled with liquid, causing the compressor to fail to start normally or being damaged by liquid backflow.

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

[0041] When it is determined that liquid backflow occurs in the gas-liquid separator of the stopped outdoor unit, the corresponding stopped outdoor unit is turned on after a set time to allow the refrigerant to pass through the corresponding pipeline.

[0042] In some embodiments, the controller is configured to: record the operating time of each outdoor unit, and when rotating the units, give priority to starting the outdoor unit with the shortest operating time;

[0043] During the unit rotation process, when a stopped outdoor unit with liquid backflow and a stopped outdoor unit with a short running time appear at the same time, the stopped outdoor unit with liquid backflow will be started first.

[0044] In some embodiments, the controller is configured to: when a stopped outdoor unit that is determined to have liquid backflow is turned on, wait for the unit to be turned off again, and if liquid backflow is still determined to have occurred in the gas-liquid separator after the unit is turned off, continue to turn on the stopped outdoor unit first;

[0045] When the stopped outdoor unit is turned on for a set number of times and is still judged to have liquid backflow after being shut down again, it is determined that the electronic expansion valve of the stopped outdoor unit is damaged and an alarm is issued.

[0046] In some embodiments, the outdoor unit includes at least two compressors, the compressors are connected in parallel, and the compressors can work selectively or in combination;

[0047] When calculating the operating hours of the outdoor unit, the operating hours of all compressors in the outdoor unit are normalized.

[0048] The present application also proposes another multi-split air conditioner, which comprises:

[0049] an indoor unit group, comprising at least one indoor unit;

[0050] The outdoor unit comprises at least two outdoor units, each of which includes:

[0051] Outdoor housing,

[0052] a compressor including an air intake and an air discharge port;

[0053] A gas-liquid separator is provided at the air intake of the compressor for gas-liquid separation;

[0054] An outdoor heat exchanger is provided in the outdoor housing and is used to exchange heat with outdoor wind;

[0055] A four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger;

[0056] Subcooler, located between the outdoor heat exchanger and the indoor unit;

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

[0058] Multi-split air conditioners also include:

[0059] A pressure detection device is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor;

[0060] a controller 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 stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit;

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

[0062] When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that the gas-liquid separator of the stopped outdoor unit has a liquid backflow phenomenon.

[0063] The above embodiment determines whether liquid backflow occurs in the gas-liquid separator by detecting the trend change of the suction pressure value, and determines whether the second electronic expansion valve cannot be closed normally based on whether liquid backflow occurs, thereby preventing the gas-liquid separator from being full of liquid and damaging the compressor.

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

[0065] A coil temperature detection device is provided on the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger;

[0066] An ambient temperature detection device is provided outside the outdoor housing and is used to detect the outdoor ambient temperature;

[0067] a controller configured to: control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor unit in the operating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit;

[0068] The second electronic expansion valve of the stopped outdoor unit is in a closed state, and the outdoor coil temperature and the outdoor ambient temperature corresponding to the stopped 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 liquid backflow occurs in the gas-liquid separator.

[0070] By detecting the difference between the coil temperature of the outdoor heat exchanger and the ambient temperature, it is determined whether liquid backflow occurs in the gas-liquid separator. Based on whether liquid backflow occurs, it is determined whether the second electronic expansion valve cannot be closed normally to prevent the gas-liquid separator from being filled with liquid and damaging the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

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

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

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

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

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

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

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

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

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

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

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

[0084] In the above picture:

[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] Compressor 1; one-way valve 2; high-pressure pressure detection device 3; four-way valve 4; pressure detection device 5;

[0088] Gas-liquid separator 6; first electronic expansion valve 7; outdoor heat exchanger 8; gas side stop valve 9;

[0089] Liquid side stop valve 10; subcooler 11; second electronic expansion valve 12;

[0090] Coil temperature detection device 13; ambient temperature detection device 15; outdoor unit 14; indoor unit 16. DETAILED DESCRIPTION

[0091] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0092] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0093] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections via an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0094] This application proposes a multi-split air conditioner 100, referring to Figure 1The multi-split air conditioner 100 includes 16 groups of indoor units, and the 16 groups of indoor units include at least one indoor unit 16 .

[0095] The indoor unit 16 group includes a plurality of indoor units 16. The plurality of indoor units 16 are connected in parallel.

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

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

[0098] The outdoor unit 14 is installed outdoors. The indoor unit 16 and the outdoor unit 14 are connected by a pipeline for the flow of refrigerant.

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

[0100] The indoor shell is provided with an indoor air inlet, which is used for supplying indoor air to the indoor shell.

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

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

[0103] The indoor unit 16 includes an indoor fan. The indoor fan is installed in an indoor housing. The indoor fan rotates to allow indoor air to enter the indoor housing. The indoor air exchanges heat with the indoor heat exchanger and flows out of the indoor housing.

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

[0105] The outdoor unit 14 includes an outdoor housing that defines the exterior of the outdoor unit 14 and houses internal components of the outdoor unit 14 .

[0106] The outdoor shell is provided with an outdoor air inlet, which is used for allowing outdoor wind to enter the outdoor shell.

[0107] The outdoor shell is provided with an outdoor air outlet, which is used to discharge the wind from the outdoor shell. The outdoor wind enters the outdoor shell 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 in an outdoor housing. The outdoor heat exchanger 8 is used to exchange heat with outdoor air entering the outdoor housing.

[0109] The outdoor unit 14 includes an outdoor fan, which is installed in an outdoor housing. The outdoor fan rotates to allow outdoor air to enter the outdoor housing. The outdoor air exchanges heat with the outdoor heat exchanger 8 and flows out of the outdoor housing.

[0110] Reference Figure 3 、 12 , describing 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 a high-temperature and high-pressure gaseous refrigerant and discharge the compressed gaseous refrigerant.

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

[0113] The compressor 1 includes an exhaust port. Refrigerant enters the compressor 1 from the air intake port and is compressed by the compressor 1 and then discharged from the exhaust port.

[0114] The outdoor unit 14 further includes a gas-liquid separator 6. The gas-liquid separator 6 is installed at the air intake 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. A first port of the four-way valve 4 is connected to the exhaust port of the compressor 1. A second port of the four-way valve 4 is connected to the intake port of the compressor 1. A third port of the four-way valve 4 is connected to the indoor unit 16. A 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 expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant.

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

[0118] The outdoor unit 14 further includes a gas-side stop valve 9 . The gas-side stop valve 9 is provided at the third port of the four-way valve 4 .

[0119] The outdoor unit 14 further includes a liquid-side stop valve 10 , which is provided between the indoor unit 16 and the subcooler 11 .

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

[0121] The multi-split air conditioner 100 uses the refrigerant flow to blow out air conditioned air that is higher than the indoor temperature, lower than the indoor temperature, or the same as the indoor temperature to adjust the temperature and humidity of the indoor environment; or uses the speed of the indoor fan to adjust the air flow rate of the indoor environment.

[0122] The cooling mode and the heating mode of the multi-split air conditioner 100 are described by taking one of the outdoor units 14 as an example.

[0123] During cooling operation of the multi-split air conditioner 100, the refrigerant from compressor 1 is condensed through outdoor heat exchanger 8. The condensed refrigerant then flows through first electronic expansion valve 7 for expansion. The expanded condensate evaporates through the indoor heat exchanger. The evaporated refrigerant then circulates back into compressor 1.

[0124] During heating operation of the multi-split air conditioner 100, the refrigerant from compressor 1 flows through the indoor heat exchanger, where it condenses. The condensed refrigerant then expands by flowing through the first electronic expansion valve 7. The expanded condensed refrigerant evaporates through the outdoor heat exchanger 8. The evaporated refrigerant then circulates back into compressor 1.

[0125] This application primarily addresses the issue of liquid return at the suction port of compressor 1. In cooling mode, due to the high outdoor temperature and refrigerant flow, liquid return to gas-liquid separator 6 generally does not occur. Therefore, the technical solution in this application primarily addresses the component control of outdoor unit 14 when the multi-split air conditioner 100 is operating in heating mode, thereby resolving the issue of liquid return to compressor 1 in outdoor unit 14.

[0126] In some embodiments of the present application, the multi-split air conditioner 100 includes a remote controller, through which a user inputs commands to the controller 21 to select an operating mode of the indoor unit 16 or the outdoor unit 14 .

[0127] In some embodiments, the working modes of the multi-split air conditioner 100 vary according to different models and user needs. In this application, the cooling mode, heating mode and shutdown mode are selected for introduction.

[0128] In the cooling mode, the air flowing into the room by the indoor unit 16 is cold air. The cold air can be defined as airflow with a temperature lower than that of the indoor air.

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

[0130] The shutdown mode means that the multi-split air conditioner 100 does not improve indoor parameters such as temperature, humidity, and air flow rate.

[0131] In some embodiments of the present 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 working state of each component 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 working state of each component inside the outdoor unit 14.

[0134] Wired communication is used between the indoor controller 21 and the outdoor controller 21 .

[0135] In other embodiments, the above 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 the shutdown command, and compare them with the set conditions to determine whether to shut down the outdoor unit 14 and whether liquid backflow occurs, so as to solve the liquid backflow problem of the compressor 1 to a certain extent.

[0137] At the same time, the outdoor controller 21 and the indoor controller 21 can also rotate the units according to the hardware conditions, operating hours, actual working conditions, etc. of each indoor unit 16 and each outdoor unit 14 to achieve efficient coordination between each indoor unit 16 and each outdoor unit 14.

[0138] In some embodiments of the present application, no specific distinction is made between the indoor controller 21 and the outdoor controller 21 , and the indoor controller 21 and the outdoor controller 21 are collectively referred to as the controller 21 .

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

[0140] The structures of the indoor controller 21 and the outdoor controller 21 are substantially the same, and the structure of the indoor controller 21 is described below by taking the indoor controller 21 as an example.

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

[0142] For example, there is at least one disk storage 212. The storage 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 implement communication with related components.

[0144] The communication interface 214 of the indoor controller 21 is used to communicate with the indoor 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 source code form, object code form, executable file or some other form.

[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.

[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 the execution instruction, the processor 213 executes the program to implement Figure 8-9 , the method for detecting the reflux of the gas-liquid separator 6 shown in 11 and Figure 10 The unit rotation control method shown in .

[0149] In some embodiments of the present 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 power-on status and operating status of each air-conditioning unit (ie, each indoor unit 16 and each outdoor unit 14 ).

[0151] The power on / off status includes the power on status and the power off status; the operation status includes the operation parameters in the power on status, the operation parameters memorized in the power off status, and the detection parameters in the power off status.

[0152] The operating parameters memorized in the shutdown state include the shutdown duration, etc. The detection parameters in the shutdown state include the coil temperature Te, suction pressure and ambient temperature Ta in the shutdown state.

[0153] In some embodiments, the plurality of outdoor units 14 are connected via a first branch pipe 23. The plurality of 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 respectively connected to the second branch pipe 24, and the two outdoor units 14 are respectively connected to the first branch pipe 23, and the first branch pipe 23 is connected to the second branch pipe 24.

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

[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, the air-conditioning unit b is selected for rotation.

[0157] The controller 21 can control the operating state of each air-conditioning unit according to the operation rotation time, the power on / off state and the 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 fails, the rotation is not performed.

[0159] In this application, when the load of the indoor unit 16 is small, the demand frequency is low, and at this time, not all outdoor units 14 need to be in operation, and there will be both an operation module and a shutdown module. That is, some outdoor units 14 are set to be in operation and some outdoor units 14 are set to be in shutdown.

[0160] In the present application, an outdoor unit 14 in an operating state is defined as an operating outdoor unit 14 , and an outdoor unit 14 in a stopped state is defined as a stopped outdoor unit 14 .

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

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

[0163] If the load of the air-conditioning system changes or the air-conditioning units meet the rotation conditions at this time, the stopped outdoor unit 14 needs to be started.

[0164] The above rotation conditions may be operating time, failures such as damage to the compressor 1, load increase, and liquid backflow in the stopped outdoor unit 14, etc. The above rotation conditions may be executed according to different set 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 rises to a certain value, the stopped outdoor unit 14 will be restarted. At this time, since the gas-liquid separator 6 of the stopped outdoor unit 14 is full of refrigerant, when the stopped outdoor unit 14 is turned on, the refrigerant will enter the compressor 1 through the suction pipe, and the compressor 1 of the stopped outdoor unit 14 may be damaged due to liquid backflow.

[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 disposed at the suction port of the compressor 1 and is used to detect the suction pressure of the compressor 1.

[0170] By detecting the change state of the suction pressure of the compressor 1, it is determined whether liquid backflow occurs in the gas-liquid separator 6.

[0171] In some embodiments, the multi-split air conditioner 100 further includes a high-pressure detection device 3 , which is disposed between the compressor 1 and the four-way valve 4 , and is used to detect high pressure to prevent excessive line 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 both an operating mode and a heating mode, and at least one outdoor unit 14 to be in a stopping mode. An outdoor unit 14 in both an operating mode and a heating mode is defined as an operating outdoor unit 14, and an outdoor unit 14 in a stopping mode is defined as a stopping outdoor unit 14.

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

[0174] When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that liquid backflow occurs in the gas-liquid separator 6 of the stopped outdoor unit 14 and the first electronic expansion valve 7 cannot be closed normally.

[0175] It can be seen that under normal circumstances, when the idle outdoor unit 14 stops operating, the first electronic expansion valve 7 is closed, no refrigerant flows in the idle outdoor unit 14, and the suction pressure therein remains stable. However, if the first electronic expansion valve 7 leaks, the refrigerant flows along the first leakage loop into the gas-liquid separator 6 of the idle outdoor unit 14, causing the suction pressure of the idle outdoor unit 14 to gradually increase.

[0176] In some embodiments, reference Figure 3 The blue arrow in the middle indicates the circuit, and 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, by detecting the suction pressure of the stopped outdoor unit 14, it is determined whether liquid backflow occurs in the gas-liquid separator 6, and it is inferred whether the first electronic expansion valve 7 is leaking, so that the occurrence of liquid backflow is discovered in time, and damage due to liquid backflow is avoided when the compressor 1 is started again, thereby ensuring stable operation of the air-conditioning system.

[0178] The outdoor unit 14 further includes a subcooler 11. The subcooler 11 is provided on a side of the outdoor heat exchanger 8 close to the indoor unit 16.

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

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

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

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

[0183] The first electronic expansion valve 7 and the second electronic expansion valve 12 being in the closed state means that the first electronic expansion valve 7 and the second electronic expansion valve 12 are set to the closed state. This does not affect the actual state in which the electronic expansion valve cannot be closed normally due to impurities or damage to the electronic expansion valve.

[0184] Reference Figure 8 , explaining the control logic of 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 is turned on or off according to the needs of the air conditioning system (S800).

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

[0187] It should be noted that Ps(n) is the currently 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. A value of x that is too small may cause data processing pressure on the controller 21. Therefore, x is set to be greater than the first parameter. For example, the first parameter is 15S, 20S, or 25S. Consider selecting a suitable specific parameter during specific design.

[0189] Furthermore, if x is too large, changes in suction pressure may not be detected in a timely manner, leading to failure to detect liquid floodback. Therefore, x is set smaller than the second parameter, for example, 25s, 30s, or 35s. Consider a specific parameter during the design process.

[0190] In some embodiments, when the change trend of 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 stopped outdoor unit 14 has a liquid backflow phenomenon (S802).

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

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

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

[0194] It is known that, referring to Figure 4 Under normal circumstances, when the outdoor unit 14 stops working, the first electronic expansion valve 7 and the second electronic expansion valve 12 are both in a closed state, there is no refrigerant flowing in the outdoor unit 14, and the suction pressure thereon is in a stable state. Figure 4 The middle blue line. When the first electronic expansion valve 7 leaks, the refrigerant will flow along the first leakage loop, or when the second electronic expansion valve 12 leaks, the refrigerant will flow along the second leakage loop into the gas-liquid separator 6 of the stopped outdoor unit 14, causing the suction pressure of the stopped outdoor unit 14 to gradually increase. For details, see Figure 4 Middle red line.

[0195] In the above embodiment, by detecting the suction pressure of the stopped outdoor unit 14, it is determined whether liquid backflow occurs in the gas-liquid separator 6, and it is inferred whether the first electronic expansion valve 7 and / or the second electronic expansion valve 12 is leaking, so that the occurrence of liquid backflow is discovered in time, and damage due to liquid backflow is avoided when the compressor 1 is started again, thereby ensuring stable operation of the air-conditioning system.

[0196] In some embodiments, reference Figure 3 The red arrow circuit, the second leakage circuit is the other operating outdoor unit 14, the second electronic expansion valve 12, and the gas-liquid separator 6.

[0197] The multi-split air conditioner 100 further includes a coil temperature detection device 13 . The coil temperature detection device 13 is mounted 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 tube 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 further includes an ambient temperature detection device 15. The ambient temperature detection device 15 is mounted on the plate rib of the outdoor housing 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 inner side of the side cover of the outdoor housing and is fixed to the plate reinforcement with a wire tie.

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

[0204] When the change trend of the suction pressure value within a certain period of time is an upward trend or / and the difference Te-Ta between the outdoor coil temperature Te of the outdoor heat exchanger 8 and the detected outdoor ambient temperature Ta reaches a preset difference m, it is determined that liquid backflow occurs in the gas-liquid separator 6 at this time and the first electronic expansion valve 7 cannot be closed normally.

[0205] It is known that, referring to Figure 5 Under normal circumstances, when the outdoor unit 14 stops working, the first electronic expansion valve 7 on it is in a closed state, no refrigerant flows in the outdoor unit 14, the suction pressure on it is in a stable state, the coil temperature of the outdoor heat exchanger 8 is close to the ambient temperature, and the change trend of the difference between the coil temperature and the outdoor ambient temperature Te-Ta is shown in the figure below. Figure 5 Medium blue line.

[0206] When the first electronic expansion valve 7 leaks, the refrigerant will flow into the gas-liquid separator 6 of the stopped outdoor unit 14 along the first refrigerant circuit. Since the refrigerant flowing into the stopped outdoor unit 14 comes from the running outdoor unit 14 and its temperature is higher than the ambient temperature, the coil temperature of the outdoor heat exchanger 8 of the stopped outdoor unit 14 will gradually become higher than the ambient temperature. As more and more refrigerant flows in, the temperature difference between the coil temperature of the stopped outdoor unit 14 and the ambient temperature will become larger and larger. The change trend of the difference between the coil temperature and the outdoor ambient temperature, Te-Ta, can be seen from the figure below. Figure 5 The red line in the graph.

[0207] In the above embodiment, by detecting the temperature difference between the coil temperature of the stopped outdoor unit 14 and the ambient temperature, it is determined whether backflow occurs in the gas-liquid separator 6 of the stopped outdoor unit 14, thereby facilitating a timely alarm or making a corresponding logical response (for example, starting a unit rotation mechanism), thereby preventing the compressor 1 from being unable to start normally due to liquid backflow.

[0208] In some embodiments, the detection period of the suction pressure, the detection period of the outdoor coil temperature, and the detection period of the outdoor ambient temperature may be consistent, or may be set to be different according to requirements and hardware computing capabilities.

[0209] Reference Figure 9 , explaining the control logic of 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 is turned on or off according to the needs of the air conditioning system (S900).

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

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

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

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

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

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

[0217] In some embodiments, the controller 21 is configured to: when the first electronic expansion valve 7 and the second electronic expansion valve 12 of the stopped outdoor unit 14 are in a closed state, obtain the suction pressure, outdoor coil temperature and outdoor ambient temperature corresponding to the stopped outdoor unit 14 at corresponding set time intervals.

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

[0219] In the above embodiment, whether liquid backflow has occurred in the gas-liquid separator 6 of the stopped outdoor unit 14 can be determined based on both the difference between the coil temperature and the outdoor ambient temperature (Te-Ta) and the change trend of the suction pressure. Alternatively, whether liquid backflow has occurred in the gas-liquid separator 6 can be determined based on one of the parameters. This allows for timely determination of liquid backflow even if the device detecting the parameters of the stopped outdoor unit 14 is damaged or missing.

[0220] In some embodiments, when liquid backflow is detected in the stopped outdoor unit 14 , unit rotation can be performed directly.

[0221] In some embodiments, the operating outdoor unit 14 with the longest working time can be selected for unit rotation to quickly resolve the problem of the stopped outdoor unit 14 with liquid backflow, thereby preventing the compressor 1 from failing to start normally.

[0222] In some embodiments, when liquid backflow is detected in a stopped outdoor unit 14, the controller 21 sends a start signal to start the stopped outdoor unit 14, thereby allowing refrigerant to flow into the pipeline. This allows refrigerant to flow to the first electronic expansion valve 7 and / or the second electronic expansion valve 12 to flush out any foreign matter present therein, thereby resolving the problem of the first electronic expansion valve 7 and / or the second electronic expansion valve 12 being unable to close due to the foreign matter, thereby resolving the problem of liquid backflow in the gas-liquid separator 6.

[0223] In the embodiment of the present application, when liquid backflow is detected in the outdoor unit 14 in the shutdown state, the units can be rotated directly, or all the units can be shut down and then turned on again.

[0224] It can be known that when the outdoor unit 14 is turned on again, the outdoor unit 14 that has liquid backflow and the air conditioning unit with a short operating time are preferentially selected.

[0225] In this application, the outdoor units 14 of the group are arranged in a variety of rotation rules, and different rotation rules have priorities.

[0226] The controller 21 can rotate the outdoor unit 14 according to the operating time of the outdoor unit 14 and whether liquid backflow occurs.

[0227] In some embodiments, the controller 21 is configured to: when it is determined that liquid backflow occurs in the gas-liquid separator 6 of the stopped outdoor unit 14, start the corresponding stopped outdoor unit 14 after a set time to allow the refrigerant to flow through the corresponding pipeline.

[0228] In some embodiments, the operating time of each outdoor unit 14 is recorded. When the units are rotated, the operating time and the shutdown time of each outdoor unit 14 are compared, and the outdoor unit 14 with the shortest operating time is started first.

[0229] In some embodiments, during the unit rotation process, when a stopped outdoor unit 14 with liquid backflow and a stopped outdoor unit 14 with less operating time simultaneously occur, the stopped outdoor unit 14 with liquid backflow is started first.

[0230] In this application, in the unit rotation rule, the priority of opening the outdoor unit 14 that has experienced liquid backflow is higher than the opening of the outdoor unit 14 that has been shut down for a short time. This is to solve the problem of the electronic expansion valve not being able to close normally due to foreign matter as soon as possible.

[0231] By using the unit rotation operation, foreign objects blocking the electronic expansion valve can be flushed away, so that the electronic expansion valve can be completely closed.

[0232] In some embodiments of the present 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 selectively operated or operated in combination.

[0233] When calculating the operating hours of the outdoor unit 14 , the operating hours of the compressor 1 may be used as a reference to normalize the operating hours of all the compressors 1 in the outdoor unit 14 .

[0234] Reference Figure 6 , two outdoor units 14 , each of which includes two compressors 1 , are taken as an example for description.

[0235] The outdoor unit 14 includes an outdoor unit 14A and an outdoor unit 14B, wherein the outdoor unit 14A serves as a master unit and the outdoor unit 14B serves as a slave unit. The outdoor unit 14A and the outdoor unit 14B each have two compressors 1 , which are defined as MC1 and MC2 .

[0236] In some embodiments, for modular combination units, it is necessary to make the running time of the variable frequency compressors 1 in each outdoor unit 14 continue to be uniformed. After each shutdown of the unit, the compressor 1 with the shortest cumulative running time in the modular unit will be started first when it is restarted next time. Figure 6 Taking the two groups of outdoor units 14 as an example, the startup sequence of the outdoor units 14 is specified.

[0237] The cumulative operating time of the four compressors 1 after reset is 100 minutes, 80 minutes, 70 minutes, and 110 minutes. A module operation table is created based on the smaller of the cumulative operating time of compressors 1 MC1 and MC2 in each outdoor unit 14 to facilitate statistical analysis of the operation of the outdoor unit 14. The module operation table header is shown in the table below.

[0238] Module No. B A Time / min 80 70

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

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

[0241] In the present application, the reason why the liquid backflow phenomenon occurs in the outdoor unit 14 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 open electronic expansion valve.

[0242] The reasons for the electronic expansion valve to cause the electronic expansion valve to fail to close properly include impurities in the closed position of the electronic expansion valve, which causes the electronic expansion valve to fail to close normally, and damage to the electronic expansion valve itself. The technical solution for solving the liquid backflow in this application can only be applied to the situation where the electronic expansion valve cannot be closed due to impurities.

[0243] In some embodiments, the controller 21 is configured to, after the stopped outdoor unit 14 is turned on and the liquid backflow phenomenon is determined to have occurred, wait for the shutdown again. If the gas-liquid separator 6 of the stopped outdoor unit 14 is still determined to have liquid backflow phenomenon after the shutdown, the stopped outdoor unit 14 is continued to be turned on first.

[0244] When the stopped outdoor unit 14 is turned on for a set number of times and is still judged to have liquid backflow after being shut down again, it is determined that the electronic expansion valve of the stopped outdoor unit 14 is damaged and an alarm is issued.

[0245] The electronic expansion valves mentioned above include a first electronic expansion valve 7 and a second electronic expansion valve 12. If the electronic expansion valve of the outdoor unit 14 fails, it needs to be repaired by the staff or management personnel through the alarm.

[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 the present application is described by taking the outdoor unit 14A and the outdoor unit 14B as examples, wherein the outdoor unit 14A is in the working state and the outdoor unit 14B is in the stopped state.

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

[0249] In order to prevent the gas-liquid separator 6 of the outdoor unit 14B from being full of liquid, the control unit is shut down and the shutdown code d1-X is reported. The first electronic expansion valve 7 and the second electronic expansion valve 12 of the outdoor unit 14A are reset to zero, that is, the valve opening is closed (S1002).

[0250] Three minutes later, the units are restarted, and the outdoor unit 14B with the abnormal electronic expansion valve is started first. This unit rotation rule takes precedence over the module rotation rule according to the accumulated operating time period in the module during normal operation (S1003).

[0251] After the outdoor unit 14B starts, the first and second electronic expansion valves 7 and 12 are reopened. If the electronic expansion valves are not tightly closed due to impurities, they will return to normal operation after being flushed with refrigerant. If the electronic expansion valves are not tightly closed due to damage, they will be reopened (S1004).

[0252] Later, due to a load change, the outdoor unit 14B stops again, and the electronic expansion valve will again cause the shutdown code d1-X (S1005) due to not closing tightly.

[0253] If this cycle repeats several times, the electronic expansion valve is deemed damaged, and the outdoor unit 14 issues an alarm to shut down, alarm-Y. The outdoor unit 14B cannot be restarted and waits for maintenance personnel to replace the electronic expansion valve (S1006).

[0254] By rotating the units as above, the problem of liquid return damage to compressor 1 caused by leakage of the electronic expansion valve of the shutdown module in the module combination can be solved.

[0255] In some embodiments, when the stopped outdoor unit 14 where liquid backflow occurs includes multiple compressors 1, and one of the compressors 1 has a working time longer than a preset time, other compressors 1 may be prioritized for operation during unit rotation.

[0256] Of course, when the air-conditioning system requires a larger cooling capacity, the compressor 1 whose working time is longer than the preset time can be turned on again to meet the user's needs as soon as possible.

[0257] The air conditioning system in some embodiments of the present application includes two electronic expansion valves. These include a first electronic expansion valve 7, which serves as the expansion valve for the outdoor heat exchanger and provides throttling, and a second electronic expansion valve 12, which bypasses the outdoor unit and provides subcooling.

[0258] The control logics in this application are also applicable to an air-conditioning system without the first electronic expansion valve 7 and an air-conditioning system without the second electronic expansion valve 12 .

[0259] In some embodiments of the present 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 further includes a second electronic expansion valve 12. The second electronic expansion valve 12 is used to control the degree of subcooling of the subcooler 11.

[0261] The multi-split air conditioner 100 includes a pressure detection device 5 installed in the pipeline between the compressor 1 and the four-way valve 4. This device 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-described embodiment and is not further described 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 stopping mode, and define the outdoor unit 14 in the operating mode and the heating mode as an operating outdoor unit 14, and define the outdoor unit 14 in the stopping mode as a stopping outdoor unit 14.

[0263] The first electronic expansion valve 7 of the stopped outdoor unit 14 is in the off state, and the suction pressure corresponding to the stopped outdoor unit 14 is obtained at a set time interval. When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that the gas-liquid separator 6 of the stopped outdoor unit 14 has a liquid backflow phenomenon at this time.

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

[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 at 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 further includes an ambient temperature detection device 15. The ambient temperature detection device 15 is installed outside the outdoor housing and is used to detect the outdoor ambient temperature.

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

[0268] When the difference Te-Ta between the coil temperature of the outdoor heat exchanger 8 and the outdoor ambient temperature reaches a preset difference m, it is determined that liquid backflow occurs in the gas-liquid separator 6 of the stopped outdoor unit 14 .

[0269] Reference Figure 11 , explaining the control logic of 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 is turned on or off according to the needs of the air conditioning system (S1100).

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

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

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

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

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

[0276] In the present application, a multi-split air conditioner 100 is proposed, which includes multiple indoor units 16 and multiple outdoor units 14. When the indoor unit 16 is in a small state, the outdoor unit 14 can partially work. The outdoor unit 14 in the shutdown mode is defined as the shutdown outdoor unit 14, and the outdoor unit 14 in the operation mode is defined as the operation outdoor unit 14. At the same time, in order to better detect the state of the shutdown outdoor unit 14, the outdoor unit 14 also includes 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 shutdown state, the suction pressure corresponding to the shutdown outdoor unit 14 is obtained at a set time interval. When the change trend of the suction pressure value within a certain time period is an upward trend, it is determined that the gas-liquid separator 6 of the shutdown outdoor unit 14 has a liquid backflow phenomenon.

[0277] Alternatively, the outdoor unit 14 is further provided with a coil temperature detection device 13 for detecting the coil temperature and an ambient temperature detection device 15 for detecting the ambient temperature. When the difference Te-Ta between the coil temperature corresponding to the stopped outdoor unit 14 and the ambient temperature obtained at a set time interval reaches a preset difference m, it is determined that liquid backflow occurs in the gas-liquid separator 6 of the stopped outdoor unit 14.

[0278] After determining that liquid backflow occurs in the gas-liquid separator 6, the refrigerant is allowed to enter the pipeline of the outdoor unit 14 where the liquid backflow occurs through unit rotation to continue to preliminarily solve the liquid backflow problem. After multiple solutions, an alarm is issued to completely solve the liquid backflow problem in the gas-liquid separator 6 and avoid damage to the compressor 1 due to the liquid backflow problem.

[0279] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0280] For ease of explanation, the above description has been presented 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. Based on the above teachings, various modifications and variations are possible. The above embodiments have been selected and described to better explain the principles and practical applications, thereby enabling those skilled in the art to better utilize the embodiments and various variations of the embodiments suitable for specific use considerations.

Claims

1. A multi-split air conditioner, characterized in that: Also includes: an indoor unit group, comprising at least one indoor unit; The outdoor unit comprises at least two outdoor units, each of which comprises: outdoor housing; a compressor including an air intake and an air discharge port; A gas-liquid separator, which is provided at the air intake of the compressor and is used for gas-liquid separation; an outdoor heat exchanger, which is disposed in the outdoor housing and is used to exchange heat with outdoor wind; a four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger; a first electronic expansion valve, which is provided between the outdoor heat exchanger and the indoor unit; The multi-split air conditioner also includes: a pressure detection device, which is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor; a controller configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit; The first electronic expansion valve of the stopped outdoor unit is in a closed state, and the suction pressure corresponding to the stopped 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 period of time, it is determined that the gas-liquid separator has a liquid backflow phenomenon.

2. A multi-split air conditioner, characterized in that: include: an indoor unit group, comprising at least one indoor unit; The outdoor unit comprises at least two outdoor units, each of which comprises: outdoor housing; a compressor including an air intake and an air discharge port; A gas-liquid separator, which is provided at the air intake of the compressor and is used for gas-liquid separation; an outdoor heat exchanger, which is disposed in the outdoor housing and is used to exchange heat with outdoor wind; a four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger; a first electronic expansion valve, which is provided between the outdoor heat exchanger and the indoor unit; The multi-split air conditioner also includes: a pressure detection device, which is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor; a controller configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit; When it is determined that liquid backflow occurs in the gas-liquid separator of the stopped outdoor unit, the corresponding stopped outdoor unit is turned on after a set time to allow the refrigerant to pass through the corresponding pipeline.

3. A multi-split air conditioner, characterized in that: include: an indoor unit group, comprising at least one indoor unit; The outdoor unit comprises at least two outdoor units, each of which comprises: outdoor housing; a compressor including an air intake and an air discharge port; A gas-liquid separator, which is provided at the air intake of the compressor and is used for gas-liquid separation; an outdoor heat exchanger, which is disposed in the outdoor housing and is used to exchange heat with outdoor wind; a four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger; a first electronic expansion valve, which is provided between the outdoor heat exchanger and the indoor unit; The multi-split air conditioner also includes: a pressure detection device, which is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor; a controller configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit; The first electronic expansion valve of the stopped outdoor unit is in a closed state, and the suction pressure corresponding to the stopped 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 period of time, it is determined that liquid backflow occurs in the gas-liquid separator; When it is determined that the stopped outdoor unit has liquid backflow, after a period of time, the units are rotated and the stopped outdoor unit having liquid backflow is started first.

4. The multi-split air conditioner according to any one of claims 1 to 3, characterized in that: The outdoor unit further includes: a subcooler, disposed between the first electronic expansion valve and the indoor unit, wherein a first end of the subcooler is connected to the first electronic expansion valve, and a second end of the subcooler is connected to the indoor unit; a second electronic expansion valve, which is used to control the subcooling degree of the subcooler; The controller is configured to obtain the suction pressure corresponding to the stopped outdoor unit at a set time interval when the first electronic expansion valve and the second electronic expansion valve of the stopped outdoor unit are in a closed state; When the change trend of the suction pressure value is an upward trend within a certain period of time, it is determined that liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve and / or the second electronic expansion valve cannot be closed normally.

5. The multi-split air conditioner according to any one of claims 1 to 3, characterized in that: Also includes: a coil temperature detection device, which is provided on the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger; an ambient temperature detection device, which is provided outside the outdoor housing and is used to detect the outdoor ambient temperature; The controller is configured to: control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, define the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and define the outdoor unit in the stopping mode as a stopping outdoor unit; The first electronic expansion valve of the stopped outdoor unit is in a closed state, and the outdoor coil temperature and the outdoor ambient temperature corresponding to the stopped outdoor unit 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 liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve cannot be closed normally.

6. The multi-split air conditioner according to claim 4, characterized in that: Also includes: a coil temperature detection device, which is provided on the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger; an ambient temperature detection device, which is provided outside the outdoor housing and is used to detect the outdoor ambient temperature; The controller is configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor units in the operating mode and the heating mode as operating outdoor units, and defining the outdoor units in the stopping mode as stopping outdoor units; The controller is configured to obtain the suction pressure, outdoor coil temperature and outdoor ambient temperature corresponding to the stopped outdoor unit at set time intervals when the first electronic expansion valve and the second electronic expansion valve of the stopped outdoor unit are in a closed state; When the suction pressure value is on an upward trend within a certain period of time, it is determined that liquid backflow occurs in the gas-liquid separator and the first electronic expansion valve and / or the second electronic expansion valve cannot be closed normally.

7. The multi-split air conditioner according to claim 2 or 3, characterized in that: The controller is configured to: record the operating time of each outdoor unit, and when rotating the units, give priority to starting the outdoor unit with the shortest operating time; During the unit rotation process, when a stopped outdoor unit with liquid backflow and a stopped outdoor unit with a short running time appear at the same time, the stopped outdoor unit with liquid backflow will be started first.

8. The multi-split air conditioner according to claim 2 or 3, characterized in that: The controller is configured to: when the stopped outdoor unit that is determined to have liquid backflow is turned on, wait for the unit to be turned off again, and if it is still determined that the gas-liquid separator has liquid backflow after the unit is turned off, continue to turn on the stopped outdoor unit first; When the stopped outdoor unit is turned on for a set number of times and is still judged to have liquid backflow after being shut down again, it is determined that the electronic expansion valve of the stopped outdoor unit is damaged and an alarm is issued.

9. The multi-split air conditioner according to claim 7, characterized in that: The outdoor unit includes at least two compressors, which are connected in parallel and can work selectively or in combination; When calculating the operating hours of the outdoor unit, the operating hours of all compressors in the outdoor unit are normalized.

10. A multi-split air conditioner, characterized in that: include: an indoor unit group, comprising at least one indoor unit; The outdoor unit comprises at least two outdoor units, each of which includes: Outdoor housing, a compressor including an air intake and an air discharge port; A gas-liquid separator, which is provided at the air intake of the compressor and is used for gas-liquid separation; an outdoor heat exchanger, which is disposed in the outdoor housing and is used to exchange heat with outdoor wind; a four-way valve, wherein a first port of the four-way valve is connected to the exhaust port of the compressor, a second port of the four-way valve is connected to the intake port of the compressor, a third port of the four-way valve is connected to the indoor unit, and a fourth port of the four-way valve is connected to the outdoor heat exchanger; a subcooler, disposed between the outdoor heat exchanger and the indoor unit; a second electronic expansion valve, which is used to control the subcooling degree of the subcooler; The multi-split air conditioner also includes: a pressure detection device, which is provided in the pipeline between the compressor and the four-way valve, and is used to detect the suction pressure of the compressor; a controller configured to control at least one of the outdoor units to be in an operating mode and a heating mode, and at least one of the outdoor units to be in a stopping mode, defining the outdoor unit in the operating mode and the heating mode as an operating outdoor unit, and defining the outdoor unit in the stopping mode as a stopping outdoor unit; The second electronic expansion valve of the stopped outdoor unit is in a closed state, and the suction pressure corresponding to the stopped 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 period of time, it is determined that liquid backflow occurs in the gas-liquid separator of the stopped outdoor unit.

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