Air conditioning system

Abstract

The invention discloses an air conditioning system which comprises an outdoor unit which comprises a plurality of outdoor heat exchangers and corresponding outdoor electronic expansion valves; the subcooler comprises a main branch connected with the outdoor heat exchanger; the heat exchange branch exchanges heat with the main branch, and a subcooler electronic expansion valve is arranged on the heat exchange branch; each indoor unit comprises an indoor heat exchanger and an indoor electronic expansion valve; the processing unit is configured to sample the state monitoring parameters according to a preset rule, obtain characteristic variables based on the state monitoring parameters and establish a characteristic variable combination corresponding to the preset rule; and when the characteristic variable combination is in an abnormal state, diagnosing a corresponding electronic expansion valve jamming fault according to the abnormal state of the characteristic variable combination, and when the jamming fault occurs, diagnosing the range of the opening degree of the corresponding electronic expansion valve. According to the method, the multiple state monitoring parameters are integrated through the characteristic variable combination, the overall view corresponding to the complex dynamic refrigeration process is formed, and the diagnosis accuracy of the jamming fault is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration equipment, and in particular to an air conditioning system. BACKGROUND

[0002] In an air conditioning system, an electronic expansion valve is one of the core components, which is used to adjust the flow of refrigerant, thereby controlling the temperature and pressure of the evaporator. The electronic expansion valve jamming (unable to move normally to adjust the opening degree) will affect the normal operation of the refrigeration system, reduce user comfort, and increase energy consumption; under certain working conditions, it will affect the capacity of the indoor unit and the outdoor unit, and even damage the compressor.

[0003] In the prior art, a specific control method is usually used to detect whether each expansion valve is jammed, such as detecting the pressure or temperature change when the opening degree changes, or detecting the current or voltage change. Due to low efficiency and poor feasibility, the same detection process is not suitable for most multi-connected systems, and the accuracy of fault diagnosis is low for electronic expansion valves with different functions.

[0004] The above information disclosed in the background of the application is only used to increase the understanding of the background of the application, and therefore, it can include prior art known to those skilled in the art. SUMMARY

[0005] The present application provides an air conditioning system including an outdoor unit and multiple indoor units, the outdoor unit including multiple outdoor heat exchangers and a subcooler, the outdoor heat exchanger including an outdoor electronic expansion valve, the subcooler including a main branch and a heat exchange branch, the main branch being connected to the outdoor heat exchanger, the heat exchange branch being in heat exchange with the main branch, and the heat exchange branch being provided with a subcooler electronic expansion valve; the indoor unit including an indoor heat exchanger, the indoor heat exchanger being provided with an indoor electronic expansion valve correspondingly; the air conditioning system further including a processing unit configured to sample one or more state monitoring parameters according to a preset rule, obtain a characteristic variable based on the state monitoring parameters, and establish a characteristic variable combination corresponding to the preset rule; when the characteristic variable combination appears in an abnormal state, diagnosing the corresponding electronic expansion valve jamming fault according to the abnormal state of the characteristic variable combination, and the range of the opening degree of the corresponding electronic expansion valve when the jamming fault occurs.

[0006] The above technical solution has the following advantages or beneficial effects: the processing unit realizes the stuck fault diagnosis of the outdoor electronic expansion valve EVO, the indoor electronic expansion valve EVI and the supercooler electronic expansion valve EVB in a data-driven manner. By establishing a characteristic variable combination corresponding to a preset rule, multiple state monitoring parameters are integrated to form an overall view corresponding to a complex dynamic refrigeration system, which can effectively improve the diagnosis accuracy of the stuck fault of the electronic expansion valve. At the same time, when the fault is identified, the range of the opening degree of the corresponding electronic expansion valve when the stuck fault occurs can be identified, thereby providing a theoretical basis for the central air conditioning fault risk assessment and the development of maintenance strategies.

[0007] In some embodiments of the present application, the processing unit is configured to perform the following steps: determining whether there is at least one indoor unit in a temperature control closed state in the air conditioning system; the indoor electronic expansion valve corresponding to the indoor unit in the temperature control closed state is fully closed when working normally; determining whether there is at least one indoor unit in a temperature control open state in the air conditioning system; the indoor electronic expansion valve corresponding to the indoor unit in the temperature control open state is in a throttling opening interval when working normally; if yes, sampling multiple state monitoring parameters of the indoor unit in the temperature control closed state according to a preset first refrigeration mode rule; obtaining a characteristic variable based on the state monitoring parameters, and establishing a first characteristic variable combination corresponding to the preset first refrigeration mode rule; the first characteristic variable combination includes a temperature difference between the return air temperature and the gas pipe temperature of the indoor unit in the temperature control closed state; when the temperature difference between the return air temperature and the gas pipe temperature of the indoor unit in the temperature control closed state shows an upward trend and the upward amount exceeds a preset first indoor side threshold value, it is identified that the first characteristic variable combination is in an abnormal state; according to the abnormal state of the first characteristic variable combination, the stuck fault of the indoor electronic expansion valve in the corresponding indoor unit in the temperature control closed state is diagnosed, and it is identified that the opening degree of the indoor electronic expansion valve in the indoor unit in the temperature control closed state is in the throttling opening interval when the stuck fault occurs.

[0008] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the indoor electronic expansion valve not normally closed in the refrigeration mode by the above method.

[0009] In some embodiments of the present application, the processing unit is configured to perform the following steps: determining whether there is at least one indoor unit in a temperature control on state in the air conditioning system; when operating normally, the indoor electronic expansion valve corresponding to the indoor unit in a temperature control off state is in a throttling opening interval; if so, sampling a plurality of state monitoring parameters of the indoor unit in the temperature control on state according to a preset second refrigeration mode rule; obtaining a characteristic variable based on the state monitoring parameters, establishing a second characteristic variable combination corresponding to the preset second refrigeration mode rule; the second characteristic variable combination includes an indoor heat exchanger superheat and an indoor electronic expansion valve opening adjustment amount; when the indoor heat exchanger superheat shows an upward trend and the upward amount exceeds a preset second indoor side threshold, and the indoor electronic expansion valve opening adjustment amount shows an upward trend and the upward amount exceeds a preset third indoor side threshold, a first abnormal state of the second characteristic variable combination is identified; according to the first abnormal state of the second characteristic variable combination, a stuck fault of the indoor electronic expansion valve in the corresponding indoor unit in the temperature control on state is diagnosed, and it is identified that the opening of the indoor electronic expansion valve in the indoor unit in the temperature control on state is in a micro-opening opening interval when the stuck fault occurs; when the indoor heat exchanger superheat shows a downward trend and the downward amount exceeds a preset fourth indoor side threshold, and the indoor electronic expansion valve opening adjustment amount shows an upward trend and the upward amount exceeds a preset third indoor side threshold, a second abnormal state of the second characteristic variable combination is identified; according to the second abnormal state of the second characteristic variable combination, a stuck fault of the indoor electronic expansion valve in the corresponding indoor unit in the temperature control on state is diagnosed, and it is identified that the indoor electronic expansion valve in the indoor unit in the temperature control on state is fully closed when the stuck fault occurs.

[0010] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the indoor electronic expansion valve in the micro-opening opening interval or the fully closed state in the refrigeration mode by the above method.

[0011] In some embodiments of the present application, the processing unit is configured to perform the following steps: determining whether there is at least one indoor unit in the air conditioning system in a start-up state; sampling a plurality of state monitoring parameters of the indoor unit according to a preset first heating mode rule; obtaining feature variables based on the state monitoring parameters, and establishing a third feature variable combination corresponding to the preset first heating mode rule; the third feature variable combination includes an indoor heat exchanger supercooling degree and an indoor electronic expansion valve opening degree adjustment amount; when the indoor heat exchanger supercooling degree shows an upward trend and the upward amount exceeds a preset fifth indoor side threshold value, and the indoor electronic expansion valve opening degree adjustment amount shows an upward trend and the upward amount exceeds a preset sixth indoor side threshold value, it is identified that the third feature variable combination appears a first abnormal state; according to the first abnormal state of the third feature variable combination, a stuck fault of the indoor electronic expansion valve in the corresponding indoor unit is diagnosed, and it is identified that the opening degree of the indoor electronic expansion valve in the indoor unit in a temperature control open state is in a slightly open opening degree interval when the stuck fault occurs; when the indoor heat exchanger supercooling degree shows a downward trend and the downward amount exceeds a preset seventh indoor side threshold value, and the indoor electronic expansion valve opening degree adjustment amount shows an upward trend and the upward amount exceeds a preset sixth indoor side threshold value, it is identified that the third feature variable combination appears a second abnormal state; according to the second abnormal state of the third feature variable combination, it is identified that the corresponding indoor electronic expansion valve has a stuck fault, and it is identified that the corresponding indoor electronic expansion valve is fully closed when the stuck fault occurs.

[0012] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the indoor electronic expansion valve in a slightly open opening degree or full closure in a heating mode by the above method.

[0013] In some embodiments of the present application, the processing unit is configured to perform the following steps: when the outdoor heat exchanger is working, sampling a plurality of state monitoring parameters of the outdoor unit according to a preset third cooling mode rule; obtaining feature variables based on the state monitoring parameters, and establishing a fourth feature variable combination corresponding to the preset third cooling mode rule; the fourth feature variable combination includes a temperature difference between an outdoor heat exchanger liquid pipe temperature and a subcooler inlet temperature; when the corresponding temperature difference between the outdoor heat exchanger liquid pipe temperature and the subcooler inlet temperature shows an upward trend and the upward amount exceeds a preset first outdoor side threshold value, it is identified that the fourth feature variable combination appears an abnormal state; according to the abnormal state of the fourth feature variable combination, a stuck fault of the corresponding outdoor electronic expansion valve is diagnosed, and it is identified that the outdoor electronic expansion valve is in a slightly open opening degree interval or full closure when the stuck fault occurs.

[0014] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the outdoor electronic expansion valve in a slightly open opening degree or full closure in a cooling mode by the above method.

[0015] In some embodiments of the present application, the processing unit is configured to perform the following steps: when the outdoor heat exchanger is working, sampling multiple status monitoring parameters of the outdoor unit according to the preset diagnostic rules of the subcooling heat exchanger electronic expansion valve; obtaining characteristic variables based on the status monitoring parameters, and establishing a fifth characteristic variable combination corresponding to the preset diagnostic rules of the subcooling heat exchanger electronic expansion valve; the fifth characteristic variable combination includes: the superheat of the heat exchange branch, and the temperature difference between the liquid side temperature of the heat exchange branch and the ambient temperature; when the superheat of the heat exchange branch shows a downward trend and the decrease exceeds the preset second outdoor side threshold, and the temperature difference between the liquid side temperature of the heat exchange branch and the ambient temperature shows a downward trend and the decrease exceeds the preset third outdoor side threshold, identifying that the fifth characteristic variable combination is in an abnormal state; based on the abnormal state of the fifth characteristic variable combination, diagnosing the stuck fault of the subcooler electronic expansion valve, and identifying that when the stuck fault occurs, the subcooler electronic expansion valve is in a slightly open opening range or fully closed.

[0016] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the subcooler electronic expansion valve in the slightly open range or fully closed through the above method.

[0017] In some embodiments of the present application, the processing unit is configured to perform the following steps: when the outdoor heat exchanger is working, sampling the status monitoring parameters of the outdoor unit according to the preset second heating mode rules; obtaining characteristic variables based on the status monitoring parameters, and establishing a sixth characteristic variable combination corresponding to the preset second heating mode rules; the sixth characteristic variable combination includes: compressor suction pressure; when the compressor suction pressure shows a downward trend and the decrease exceeds the preset fourth outdoor side threshold, identifying that the sixth characteristic variable combination is in an abnormal state; based on the abnormal state of the sixth characteristic variable combination, diagnosing the corresponding outdoor electronic expansion valve's stuck fault, and identifying that when the stuck fault occurs, the outdoor electronic expansion valve is in a slightly open opening range or fully closed.

[0018] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the outdoor electronic expansion valve in the slightly open range or fully closed in the heating mode through the above method.

[0019] In some embodiments of the present application, the processing unit is configured to perform the following steps: when the outdoor heat exchanger is working, sampling a plurality of state monitoring parameters of the outdoor unit according to a preset third heating mode rule; obtaining a characteristic variable based on the state monitoring parameters; establishing a seventh characteristic variable combination corresponding to the preset third heating mode rule; the seventh characteristic variable combination includes: compressor discharge superheat and outdoor electronic expansion valve opening degree adjustment amount; when the compressor discharge superheat shows a downward trend and the downward amount exceeds a preset fifth outdoor side threshold, and the outdoor electronic expansion valve opening degree adjustment amount shows a downward trend and the downward amount exceeds a preset sixth outdoor side threshold, it is identified that the seventh characteristic variable combination is in an abnormal state; when it is identified that the seventh characteristic variable combination is in an abnormal state, according to the abnormal state of the seventh characteristic variable combination, a stuck fault of the corresponding outdoor electronic expansion valve is diagnosed, and it is identified that the outdoor electronic expansion valve is in a high opening degree interval when the stuck fault occurs.

[0020] The above technical solution has the following advantages or beneficial effects: the processing unit diagnoses the stuck fault of the outdoor electronic expansion valve in the high opening degree interval in the heating mode by the above method.

[0021] In some embodiments of the present application, the processing unit is further configured to perform the following steps: when judging whether the characteristic variable combination is in an abnormal state, classifying the characteristic variable combination according to the influence factors related to the characteristic variable combination, and judging whether the characteristic variable combination is in an abnormal state under the corresponding category.

[0022] The above technical solution has the following advantages or beneficial effects: the processing unit filters out the influence of the influence factors on the characteristic variable combination according to different operating characteristics by the above method, thereby improving the accuracy of the stuck fault diagnosis.

[0023] In some embodiments of the present application, the processing unit is further configured to perform the following steps: sampling a plurality of state monitoring parameters within a set period; obtaining a characteristic variable based on the state monitoring parameters within the set period; and establishing a characteristic variable combination corresponding to the preset rule based on the average value of the characteristic variable within the set period.

[0024] The above technical solution has the following advantages or beneficial effects: the processing unit filters out the influence of transient factors by the above method, thereby improving the accuracy of the stuck fault diagnosis. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 A schematic structural diagram of an air-conditioning system provided by some embodiments of the present invention;

[0027] Figure 2 A schematic diagram of a refrigerant cycle in a cooling mode of an air-conditioning system provided by some embodiments of the present invention;

[0028] Figure 3 A schematic diagram of a refrigerant cycle in a heating mode of an air-conditioning system provided by some embodiments of the present invention;

[0029] Figure 4 A schematic structural diagram of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0030] Figure 5 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0031] Figure 6 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0032] Figure 7 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0033] Figure 8 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0034] Figure 9 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0035] Figure 10 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0036] Figure 11 A flowchart of a processing unit in an air-conditioning system provided by some embodiments of the present invention;

[0037] Figure 12 This is an example of a fault table;

[0038] In the picture:

[0039] 1. Air conditioning system;

[0040] 10. Outdoor unit; 11. Compressor; 12. Outdoor heat exchanger; 13. Switching valve; 14. Subcooler; 15. Main branch; 16. Heat exchange branch;

[0041] 20. Indoor unit; 21. Indoor heat exchanger;

[0042] EVI, indoor electronic expansion valve; EVO, outdoor electronic expansion valve; EVB, subcooler electronic expansion valve;

[0043] 30, processing unit;

[0044] 301, processor; 302, nonvolatile memory; 303, volatile memory; 304, display device; 305, operation device; 306, communication interface; 307, driving device; 308, bus; 309, storage medium; 310, storage medium; DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0046] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0047] The terms "first", "second" are only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0048] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0049] In the present disclosure, unless specifically stated and limited otherwise, a first feature "on" or "under" a second feature can include the first and second features being directly in contact, or can include the first and second features not being directly in contact but being in contact through another feature between them. Also, the first feature "over", "above" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or just means that the first feature is higher in level than the second feature. The first feature "under", "below" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or just means that the first feature is lower in level than the second feature.

[0050] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplicity, the elements and settings of certain examples in the following description will be described with reference to the drawings. These are, of course, merely examples and are not intended to limit the application. Furthermore, the application can be implemented in a variety of environments and applications, and, accordingly, the application is not limited to the specific examples described below. In addition, the application provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize that other processes can be used and / or other materials can be employed.

[0051] A first aspect of the present application provides an air conditioning system that performs a refrigeration cycle of an air conditioner by using a compressor, a condenser, a throttling element, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat an indoor space.

[0052] A low-temperature and low-pressure refrigerant enters the compressor, which compresses the refrigerant gas into a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0053] The throttling element (for example, an electronic expansion valve) expands the high-temperature and high-pressure state liquid phase refrigerant formed in the condenser into a low-pressure liquid phase refrigerant. The evaporator evaporates the refrigerant expanded in the electronic expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a refrigeration effect by exchanging heat with a material to be cooled using the latent heat of evaporation of the refrigerant. Throughout the cycle, the air conditioning system can adjust the temperature of the indoor space.

[0054] The outdoor unit of the air conditioning system refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger, the indoor unit of the air conditioning system includes the indoor heat exchanger, and the electronic expansion valve can be provided in the indoor unit or the outdoor unit.

[0055] The indoor heat exchanger and the outdoor heat exchanger are used as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioning system is used as a heater in a heating mode, and when the indoor heat exchanger is used as an evaporator, the air conditioning system is used as a cooler in a cooling mode.

[0056] From the hardware architecture point of view, referring to the accompanying drawings Figure 1 , the outdoor unit 10 of the air conditioning system 1 provided by some embodiments of the present application is introduced.

[0057] In the outdoor unit 10, the compressor 11 is the core component for driving the refrigerant circulation, compressing the low-pressure gas into high-pressure gas to increase the temperature and pressure, and promoting heat exchange. In the cooling mode, the compressor 11 drives the refrigerant to absorb indoor heat and release it to the outdoor to achieve cooling; in the heating mode, it works reversely to provide warm air.

[0058] The outdoor heat exchanger 12 in the outdoor unit 10 is used for heat exchange with the external environment. In the cooling mode, it acts as a condenser to release the heat absorbed from the indoor to the outdoor air through the refrigerant; in the heating mode, it works reversely as an evaporator to absorb outdoor heat to provide heating. The outdoor heat exchanger 12 is fluidly connected with the outdoor electronic expansion valve EVO, the valve core of which is installed on the refrigerant pipeline and is driven by a stepping motor to accurately adjust the opening degree. The opening degree of the outdoor electronic expansion valve EVO is usually expressed in percentage or stepping motor steps, so as to quantify the opening size of the outdoor electronic expansion valve EVO. The outdoor heat exchanger 12 is provided with an outdoor fan and an air duct system.

[0059] As shown in FIG. Figure 1 , multiple outdoor heat exchangers 12 (two are taken as an example in Figure 1 ) can be arranged in the outdoor unit 10, each of which is connected in parallel to the refrigerant circuit as an independent module, allowing each outdoor heat exchanger 12 to work independently and multiple outdoor heat exchangers 12 to work cooperatively. The multiple outdoor heat exchangers 12 share the same refrigerant inlet and outlet, but each outdoor heat exchanger 12 is fluidly connected with a corresponding outdoor electronic expansion valve EVO. The refrigerant is divided into each outdoor heat exchanger 12 and the corresponding outdoor electronic expansion valve EVO, and then collected to flow out. When multiple outdoor heat exchangers 12 are arranged, each outdoor heat exchanger 12 is provided with a corresponding outdoor fan and air duct system. The corresponding outdoor electronic expansion valve EVO can independently adjust the flow rate to achieve local optimization.

[0060] The outdoor unit 10 is also provided with a switching valve 13 for switching the flow direction of the refrigerant. The switching valve 13 can be a four-way valve. The four-way valve is usually designed in a slider type or a rotary type, and includes four ports, a first port fluidly connected to the discharge side of the compressor 11, a second port fluidly connected to the outdoor heat exchanger 12, a third port fluidly connected to the indoor heat exchanger 21, and a fourth port fluidly connected to the suction side of the compressor 11. Taking the slider type as an example, the slider position is controlled by an electromagnetic coil to switch the flow direction of the refrigerant.

[0061] The air conditioning system 1 also includes an over-cooler 14. The over-cooler 14 is an auxiliary heat exchanger located downstream of the condenser, and cools the liquid refrigerant to below its saturation temperature through an additional cooling process, thereby increasing the energy stored in the refrigerant. The over-cooler 14 includes a main branch 15 fluidly connected to the outdoor heat exchanger 12 and the indoor heat exchanger 21, and a heat exchange branch 16, one end of which is located between the main branch 15 and the indoor heat exchanger 21, and the other end of which is connected to the compressor 11 after heat exchange with the main branch 15. The heat exchange branch 16 is provided with an over-cooler electronic expansion valve EVB; the liquid side of the heat exchange branch 16 before heat exchange with the main branch 15 is defined, and the gas side of the heat exchange branch 16 after heat exchange with the main branch 15 is defined.

[0062] In the over-cooler 14, the high-pressure liquid refrigerant of the main branch 15 exchanges heat with the refrigerant of the heat exchange branch 16. Through the adjustment of the over-cooler electronic expansion valve EVB, the refrigerant in the heat exchange branch 16 is in a lower pressure state, and is partially evaporated to absorb the heat of the refrigerant in the main branch 15, so that the temperature of the refrigerant in the main branch 15 is further reduced to achieve a higher supercooling degree. The over-cooler electronic expansion valve EVB adjusts the opening degree to ensure that the refrigerant in the heat exchange branch 16 exchanges heat in the best state, thereby optimizing the cooling effect of the main branch 15. The low-temperature gaseous refrigerant generated by the evaporation of the heat exchange branch 16 can increase the suction flow of the compressor 11 to achieve the effect of gas supplementation. The over-cooler electronic expansion valve EVB also adjusts the opening degree accurately through the driving of the stepping motor, which will not be described here.

[0063] Referring to Figure 1 The indoor unit 20 is introduced, which adopts an air-refrigerant heat exchange mode to further transfer the heat or cold in the refrigerant cycle to indoor air to adjust the indoor temperature and humidity. The indoor unit 20 includes a refrigerant-air heat exchanger, and an indoor fan drives indoor air to forcibly pass through the refrigerant-air heat exchanger to achieve heat exchange.

[0064] In the present application, the air conditioning system 1 comprises a plurality of indoor heat exchangers 21, each of which is connected in parallel to the refrigerant circuit as an independent module, allowing each indoor heat exchanger 21 to work independently. Each indoor heat exchanger 21 is fluidly connected to a respective indoor electronic expansion valve EVI, so that the refrigeration or heating effect of each room can be dynamically adjusted and controlled according to the specific needs of the air conditioning area where the indoor unit 20 is located, without affecting other areas.

[0065] The outdoor electronic expansion valve EVO, the indoor electronic expansion valve EVI and the supercooler electronic expansion valve EVB can all have a stuck failure, i.e. the valve is fixed at a certain position and cannot respond to the control signal, resulting in the refrigerant flow being unable to be normally adjusted, causing various abnormalities. To solve this problem, in some embodiments of the present application, as shown in Figure 2 The air conditioning system 11 further comprises a processing unit 30.

[0066] Figure 3 A block diagram of the hardware configuration of the processing unit 30 is shown in Figure 3 The processing unit 30 comprises a processor 301. The processor 301 can be a special-purpose processor 301, a central processing unit (CPU), etc. The processing unit 30 further comprises a storage component, which can be a volatile memory 303 and / or a non-volatile memory 302. The processor 301 can access instructions or applications stored in the storage component to implement related functions.

[0067] The processing unit 30 further comprises a display device 304 for displaying various information.

[0068] The processing unit 30 further comprises an operation device 305 for performing various operations.

[0069] The processing unit 30 further comprises a communication interface 306.

[0070] The processing unit 30 further comprises a drive device 307 for controlling hardware interrupts interacting with the storage medium.

[0071] The processing unit 30 further comprises a bus 308.

[0072] The processor 301, the volatile memory 303, the non-volatile memory 302, the display device 304, the operation device 305, the communication interface 306 and the drive device 307 are connected to each other through the bus 308.

[0073] In some embodiments of the present application, the storage medium (such as Figure 3The component 309 shown by reference sign includes a Compact Disc Read-Only Memory (CD-ROM), a floppy disk, an optical magnetic disk, and the like to record information in an optical, electrical, or magnetic manner. The storage medium (such as Figure 3 The component 310 shown by reference sign can also be a semiconductor memory to record information in an electrical manner, such as a Read-Only Memory (ROM), a flash memory, and the like.

[0074] In some embodiments of the present application, the processing unit 30 can be an on-board system based on a Microcontroller Unit (MCU) in the outdoor unit 10.

[0075] In some other embodiments of the present application, the processing unit 30 can be an on-board system based on a microcontroller unit in the indoor unit 20.

[0076] In some other embodiments of the present application, part of the functions of the processing unit 30 can be implemented by an on-board system based on a microcontroller unit in the outdoor unit 10, and another part of the functions can be implemented by an on-board system based on a microcontroller unit in the indoor unit 20.

[0077] In some other embodiments of the present application, part of the functions of the processing unit 30 can be implemented by an edge processing unit 30 (such as a centralized controller or a gateway) and / or a cloud server, and another part of the functions can be implemented by an on-board system based on a microcontroller unit in the outdoor unit 10 and / or the indoor unit 20.

[0078] The processing unit 30 is configured to sample one or more state monitoring parameters according to a preset rule, obtain a characteristic variable based on the state monitoring parameters, and establish a characteristic variable combination corresponding to the preset rule; when any one of the characteristic variable combinations appears in an abnormal state, diagnose a corresponding electronic expansion valve sticking fault and a range of the opening degree of the corresponding electronic expansion valve when the sticking fault occurs according to the abnormal state of the characteristic variable combination.

[0079] Specifically, in the present application, the processing unit 30 realizes the outdoor electronic expansion valve EVO, indoor electronic expansion valve EVI, and subcooler electronic expansion valve EVB sticking fault diagnosis through a data-driven manner, integrates multiple state monitoring parameters by establishing a characteristic variable combination corresponding to a preset rule to form an overall view corresponding to a complex dynamic refrigeration system, which can effectively improve the diagnostic accuracy of the electronic expansion valve sticking fault; and at the same time of identifying the fault, the range of the opening degree of the corresponding electronic expansion valve when the sticking fault occurs can be identified, thereby providing a theoretical basis for the central air conditioning fault risk assessment and the development of maintenance strategies.

[0080] As Figure 5 shown in the drawings, in one embodiment of the present application, the processing unit 30 is configured to perform the following steps:

[0081] Step S101: Determine whether there is at least one indoor unit 20 in the air conditioning system 1 in the temperature control closed state. When working normally, the indoor electronic expansion valve EVI corresponding to the indoor unit 20 in the temperature control closed state is fully closed.

[0082] Step S102: Determine whether there is at least one indoor unit 20 in the air conditioning system 1 in the temperature control open state. When working normally, the indoor electronic expansion valve EVI corresponding to the indoor unit 20 in the temperature control open state is in the throttling opening interval.

[0083] Step S103: If yes, sample the various state monitoring parameters of the indoor unit 20 in the temperature control closed state according to the preset first refrigeration mode rule.

[0084] In some embodiments of the present application, the state monitoring parameters sampled according to the preset first refrigeration mode rule include: return air temperature and air pipe temperature .

[0085] In some embodiments of the present application, the state monitoring parameters sampled according to the preset first refrigeration mode rule include: return air temperature and liquid pipe temperature .

[0086] In some embodiments of the present application, the state monitoring parameters sampled according to the preset first refrigeration mode rule include: return air temperature , air pipe temperature and liquid pipe temperature .

[0087] Wherein, the return air temperature is collected by a temperature sensor arranged at the return air inlet of the indoor unit 20, the air pipe temperature is collected by a temperature sensor arranged on the refrigerant pipeline between the indoor heat exchanger 21 and the compressor 11, and the liquid pipe temperature is collected by a temperature sensor arranged on the refrigerant pipeline between the indoor heat exchanger 21 and the indoor electronic expansion valve EVI.

[0088] Step S104: Obtain feature variables based on the state monitoring parameters, and establish a first feature variable combination corresponding to the preset first refrigeration mode rule.

[0089] In some embodiments of the present application, the first feature variable combination includes return air temperature and air pipe temperature The temperature difference between ;in, .

[0090] In some embodiments of the present application, the first characteristic variable combination includes return air temperature Liquid pipe temperature The temperature difference between ;in, .

[0091] In some embodiments of the present application, the first characteristic variable combination includes return air temperature , tracheal temperature and liquid pipe temperature .

[0092] In some embodiments of the present application, the first characteristic variable combination includes any combination of the above three methods.

[0093] Step S105: When it is identified that the first characteristic variable combination is in an abnormal state, based on the abnormal state of the first characteristic variable combination, a stuck fault of the indoor electronic expansion valve EVI in the corresponding indoor unit 20 that is in the temperature-controlled closed state is diagnosed, and it is identified that when the stuck fault occurs, the opening of the indoor electronic expansion valve EVI in the indoor unit 20 that is in the temperature-controlled closed state is in the throttling range.

[0094] like Figure 2 As shown, in the air conditioning system 1, any indoor unit 20 can operate in either the ThermoON or ThermoOFF state. In the ThermoON state, the indoor unit 20 automatically operates according to the set target temperature. The corresponding opening range of the indoor electronic expansion valve (EVI) is throttled. The indoor electronic expansion valve (EVI) forms a throttling orifice with a variable aperture, causing the refrigerant pressure to drop. At this time, the opening of the indoor electronic expansion valve (EVI) is relatively small, thereby regulating the refrigerant flow rate and pressure drop. When the indoor temperature reaches the set temperature, the indoor unit 20 enters the ThermoOFF state.

[0095] After entering the thermostat off state (Thermo OFF), if the indoor electronic expansion valve EVI works normally, it will be fully closed and no refrigerant will flow through the indoor heat exchanger 21. Return air temperature With tracheal temperature The temperature difference between Smaller.

[0096] After entering the temperature control closed state, the indoor electronic expansion valve EVI is stuck, and when the stuck fault occurs, the opening of the indoor electronic expansion valve EVI is still in the throttling range. At this time, since there is at least one indoor unit 20 in the temperature open state in the air-conditioning system 1, although it enters the temperature control closed state, the refrigerant in the air-conditioning system 1 is still circulating, and the opening of the indoor electronic expansion valve EVI that should have been closed is still in the throttling range, resulting in refrigerant still flowing through the corresponding indoor heat exchanger 21, and the corresponding gas pipe temperature However, when the indoor temperature reaches the set temperature, the indoor unit 20 enters the temperature control closed state, further corresponding to the return air temperature and tracheal temperature The temperature difference between It will show an upward trend.

[0097] Therefore, at the corresponding return air temperature and tracheal temperature The temperature difference between The rising trend is shown and the rising amount exceeds the preset first indoor threshold When , it is identified that the first characteristic variable combination is in an abnormal state.

[0098] Based on the abnormal state occurring in the first characteristic variable combination, it is identified that the indoor electronic expansion valve EVI corresponding to the indoor unit 20 that has entered the temperature-controlled closed state has a stuck fault, and it is identified that when the stuck fault occurs, the indoor electronic expansion valve EVI in the indoor unit 20 that is in the temperature-controlled closed state is in the throttling range, and the corresponding indoor electronic expansion valve EVI is not closed correctly.

[0099] Return air temperature Liquid pipe temperature The temperature difference between , return air temperature , tracheal temperature and liquid pipe temperature The abnormal conditions are not listed here one by one.

[0100] like Figure 6 As shown, in one embodiment of the present application, the processing unit 30 is further configured to perform the following steps:

[0101] Step S201 : determining whether there is at least one indoor unit 20 in the air-conditioning system 1 that is in the thermostat-on state (Thermo ON).

[0102] Step S202: If yes, sample various status monitoring parameters of the indoor unit 20 in the temperature control on state according to the preset second cooling mode rule.

[0103] In some embodiments of the present application, the state monitoring parameters sampled according to the preset second refrigeration mode rule include: the temperature of the gas pipe and the temperature of the liquid pipe .

[0104] Step S203: Obtain feature variables based on the state monitoring parameters, and establish a second feature variable combination corresponding to the preset second refrigeration mode rule.

[0105] In some embodiments of the present application, the second feature variable combination includes the superheat degree of the indoor heat exchanger 21 and the opening degree adjustment amount of the indoor electronic expansion valve EVI .

[0106] In the present application, the superheat degree of the indoor heat exchanger 21 may be equivalent to the difference between the temperature of the gas pipe and the temperature of the liquid pipe , ; the opening degree adjustment amount of the indoor electronic expansion valve EVI is the valve opening degree adjustment amount generated based on a built-in control algorithm (such as a PID algorithm or a fuzzy control algorithm).

[0107] Step S204: When the second feature variable combination is identified to be in a first abnormal state, diagnose the corresponding indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control open state to have a stuck fault according to the first abnormal state of the second feature variable combination, and identify that the opening degree of the indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control open state is in the micro-opening opening degree interval when the stuck fault occurs.

[0108] Step S205: When the second feature variable combination is identified to be in a second abnormal state, diagnose the corresponding indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control open state to have a stuck fault according to the second abnormal state of the second feature variable combination, and identify that the indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control open state is fully closed when the stuck fault occurs.

[0109] Any indoor unit 20 can work in the temperature control open state (Thermo ON), and the built-in control algorithm (PID controller) generates the opening degree adjustment amount of the indoor electronic expansion valve EVI according to the superheat degree at the outlet of the evaporator; when the heat load decreases and the required cooling capacity decreases, the superheat degree decreases, and the opening degree adjustment amount of the indoor electronic expansion valve EVI is generated to close the indoor electronic expansion valve EVI, the superheat degree increases, and the refrigerant in the evaporator decreases; when the heat load increases and the required cooling capacity increases, the superheat degree increases, and the opening degree adjustment amount of the indoor electronic expansion valve EVI The indoor electronic expansion valve EVI is opened, the superheat degree is reduced, the refrigerant in the evaporator is increased, and finally the evaporator outlet superheat degree is maintained in the ideal interval range.

[0110] After entering the temperature control opening state, if the indoor electronic expansion valve EVI has a stuck fault, but at the time of the stuck fault, the indoor electronic expansion valve EVI is still in the micro-opening interval, at this time, the refrigerant flow through the indoor heat exchanger 21 is extremely small. At this time, although the liquid pipe temperature is low, the refrigerant flow through the indoor heat exchanger 21 is extremely small, and the gap between the gas pipe temperature and the return air temperature is also relatively small. Because the indoor heat exchanger 21 as the evaporator is not fully evaporated, the superheat degree will rise significantly; but at this time, the built-in control algorithm will determine that it is a heat load increase or a refrigerant shortage, so as to continue to output a positive indoor electronic expansion valve EVI opening degree adjustment amount , further trying to increase the refrigerant flow and reduce the indoor heat exchanger 21 superheat degree back to the ideal interval.

[0111] Therefore, when the indoor heat exchanger 21 superheat degree presents an upward trend and the upward amount exceeds the preset second indoor side threshold value , and the indoor electronic expansion valve EVI opening degree adjustment amount presents an upward trend and the upward amount exceeds the preset third indoor side threshold value , the first abnormal state of the second feature variable combination is identified.

[0112] According to the first abnormal state of the second feature variable combination, it is diagnosed that the indoor electronic expansion valve EVI corresponding to the indoor unit 20 in the temperature control opening state has a stuck fault, and it is identified that the opening degree of the indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control opening state at the time of the stuck fault is in the micro-opening interval, and the corresponding indoor electronic expansion valve EVI is not normally opened.

[0113] After entering the temperature control opening state, if the indoor electronic expansion valve EVI has a stuck fault, but at the time of the stuck fault, the indoor electronic expansion valve EVI is still in the full-closed state, at this time, no refrigerant will flow through the indoor heat exchanger 21. Because the indoor electronic expansion valve EVI is fully closed, the refrigerant cannot flow, and the compressor 11 is still working, therefore, the liquid pipe temperature will rise. In the indoor heat exchanger 21, the evaporation process is completely stopped, and the indoor heat exchanger 21 will be gradually exhausted, and there is no overheat state, and the indoor heat exchanger 21 superheat degree The indoor heat exchanger 21 will be significantly reduced until close to 0. When the fault just occurs, there may be some refrigerant remaining in the indoor heat exchanger 21, similar to the fault in the micro-opening interval, the built-in control algorithm will determine that it is a refrigerant shortage, and thus continue to output a positive indoor electronic expansion valve EVI opening degree adjustment amount , trying to increase the refrigerant flow.

[0114] Therefore, when the indoor heat exchanger 21 superheat presents a downward trend and the downward amount exceeds the preset fourth indoor side threshold , and the indoor electronic expansion valve EVI opening degree adjustment amount presents an upward trend and the upward amount exceeds the preset third indoor side threshold , it is identified that the second state monitoring parameter enters the second abnormal state.

[0115] According to the second abnormal state of the second feature variable combination, it is identified that the indoor electronic expansion valve EVI corresponding to the indoor unit 20 in the temperature control opening state has a jamming fault, and it is identified that the indoor electronic expansion valve EVI in the indoor unit 20 in the temperature control opening state is fully closed when the jamming fault occurs.

[0116] In some embodiments of the present application, the processing unit 30 is configured to classify the feature variable combination according to the influence factor related to the feature variable combination when judging whether the feature variable combination enters an abnormal state, and judge whether the feature variable combination enters an abnormal state under the corresponding category.

[0117] In this embodiment, on the one hand, since the indoor fan speed affects the flow speed of air on the surface of the indoor heat exchanger 21, thereby directly affecting the heat exchange efficiency, the superheat and the speed are related to each other. On the other hand, the liquid pipe temperature is the temperature of the refrigerant before entering the indoor heat exchanger 21, and the return air temperature can be considered as the ambient temperature of the indoor heat exchanger 21, and the temperature difference between the two is the heat exchange temperature difference, which reflects the heat load and heat transfer capacity of the indoor heat exchanger 21, since the heat exchange temperature difference directly affects the efficiency of the evaporation process, thereby also being related to the superheat. Therefore, the related influence factors include the speed gear of the indoor fan and / or the heat exchange temperature difference.

[0118] In order to filter out the interference of the indoor fan speed and the heat exchange temperature difference on the electronic expansion valve jamming fault identification, in the present application, when judging whether the second feature variable combination enters the first abnormal state or the second abnormal state, the second feature variable combination is classified according to the preset interval of the speed gear of the indoor fan and / or the heat exchange temperature difference, and whether the second feature variable combination enters the first abnormal state or the second abnormal state is judged under the corresponding category.

[0119] For example, the wind speed gears of the indoor fan can be classified into low speed, medium speed and high speed; the heat exchange temperature difference can be classified into small temperature difference, medium temperature difference and large temperature difference. Based on the classification results, corresponding normal operation data is called from a pre-stored database. The normal operation data is a benchmark value obtained based on historical tests or simulations, for example, a typical range of the superheat degree and the indoor electronic expansion valve EVI opening degree adjustment amount under the same specific wind speed gear and temperature difference category as the current system state. Further comparison is made on the current system state to determine whether the second feature variable combination appears the first abnormal state or the second abnormal state.

[0120] In an embodiment of the present application, the processing unit 30 is further configured to perform the following steps:

[0121] Step S301: Determine whether there is at least one indoor unit 20 in the air conditioning system 1 in the switch ON state.

[0122] Step S302: Sample a plurality of state monitoring parameters of the indoor unit 20 according to the preset first heating mode rule.

[0123] In some embodiments of the present application, the state monitoring parameters sampled according to the preset first heating mode rule include the liquid pipe temperature , the compressor 11 discharge pressure , and the condensing temperature obtained based on the compressor 11 discharge pressure .

[0124] Step S303: Obtain feature variables based on the state monitoring parameters, and establish a third feature variable combination corresponding to the preset first heating mode rule.

[0125] In some embodiments of the present application, the third feature variable combination includes the supercooling degree of the indoor heat exchanger 21 and the indoor electronic expansion valve EVI opening degree adjustment amount .

[0126] In the present application, the supercooling degree of the indoor heat exchanger 21 is the difference between the condensing temperature and the liquid pipe temperature , ; the indoor electronic expansion valve EVI opening degree adjustment amount is the valve opening degree adjustment amount generated based on a built-in control algorithm (for example, a PID algorithm or a fuzzy control algorithm).

[0127] Step S304: When it is identified that the third characteristic variable combination has a first abnormal state, a stuck fault of the indoor electronic expansion valve EVI in the corresponding indoor unit 20 is diagnosed based on the first abnormal state of the third characteristic variable combination, and it is identified that when the stuck fault occurs, the opening degree of the indoor electronic expansion valve EVI in the indoor unit 20 in the temperature-controlled open state is in a slightly open opening range.

[0128] Step S305: When it is identified that the third characteristic variable combination has a second abnormal state, the stuck fault of the indoor electronic expansion valve EVI in the corresponding indoor unit 20 is diagnosed based on the second abnormal state of the third characteristic variable combination, and it is identified that when the stuck fault occurs, the indoor electronic expansion valve EVI in the indoor unit 20 that is in the temperature control open state is fully closed.

[0129] like Figure 3 As shown, in the heating mode, the refrigerant flows in the opposite direction. The gaseous refrigerant enters the indoor heat exchanger 21 from the gas pipe, passes through the indoor heat exchanger 21, and then enters the liquid pipe through the indoor electronic expansion valve EVI. After converging, it flows into the outdoor heat exchanger 12. In this process, the indoor electronic expansion valve EVI does not throttle and remains in a high opening range. In order to avoid the accumulation of refrigerant in the indoor heat exchanger 21 during shutdown, which reduces the circulation amount of refrigerant in the air-conditioning system 1, the indoor electronic expansion valve EVI also needs to maintain a certain opening when the system is shut down. Therefore, in the heating mode, if the stuck fault of the indoor electronic expansion valve EVI occurs in the high opening range, it does not affect the normal use of the air-conditioning system 1. In this application, it will not be diagnosed.

[0130] In the heating mode, when there is no fault, the indoor electronic expansion valve EVI controls the refrigerant flow by adjusting the opening degree, and its opening degree also determines the subcooling degree of the indoor heat exchanger 21.

[0131] If the indoor electronic expansion valve EVI is stuck, the indoor electronic expansion valve EVI is in a slightly open range. Since the refrigerant stays in the indoor heat exchanger 21 for a long time, the temperature is further reduced and the degree of subcooling is reduced. However, at this time, the built-in control algorithm will continue to output a positive indoor electronic expansion valve EVI opening adjustment amount. , further attempts were made to increase the refrigerant flow rate by increasing the opening of the indoor electronic expansion valve EVI, thereby reducing the supercooling degree.

[0132] Therefore, the subcooling degree of the indoor heat exchanger 21 is The temperature shows an upward trend and the increase exceeds the preset fifth indoor threshold. At the same time, the indoor electronic expansion valve EVI opening adjustment amount The temperature shows an upward trend and the increase exceeds the preset sixth indoor threshold. When , it is identified that the third characteristic variable combination has a first abnormal state.

[0133] According to the first abnormal state occurring in the third characteristic variable combination, it is diagnosed that the indoor electronic expansion valve EVI corresponding to the indoor unit 20 has a stuck fault, and it is identified that when the stuck fault occurs, the opening range of the indoor electronic expansion valve EVI is a slightly open opening range.

[0134] If the indoor electronic expansion valve EVI is stuck, the indoor electronic expansion valve EVI is fully closed, and the corresponding indoor heat exchanger 21 accumulates refrigerant for a long time, and eventually the gas pipe and liquid pipe connected to the indoor heat exchanger 21 are filled with liquid refrigerant, and the gas pipe temperature Decreases, and the subcooling degree of the indoor heat exchanger 21 During this process, the built-in control algorithm will continue to output a positive indoor electronic expansion valve EVI opening adjustment amount. , try to increase the refrigerant flow rate.

[0135] Therefore, the subcooling degree of the indoor heat exchanger 21 is The temperature shows a downward trend and the amount of decrease exceeds the preset seventh indoor threshold. At the same time, the indoor electronic expansion valve EVI opening adjustment amount The temperature shows an upward trend and the increase exceeds the preset sixth indoor threshold. When , it is identified that the third characteristic variable combination has a second abnormal state.

[0136] According to the occurrence of the second abnormal state in the third characteristic variable combination, it is identified that the corresponding indoor electronic expansion valve EVI has a stuck fault, and it is identified that when the stuck fault occurs, the corresponding indoor electronic expansion valve EVI is fully closed.

[0137] The capacity ratio of active indoor units 20 in air conditioning system 1 changes the system's equilibrium point, affecting the condenser pressure and temperature distribution, which indirectly leads to changes in subcooling. The indoor fan speed is also correlated with subcooling. The temperature difference between the condensing temperature and the return air temperature indirectly affects the system load and refrigerant demand, and is thus also correlated with subcooling. Factors associated with the third characteristic variable combination include the capacity ratio of active indoor units 20, the indoor fan speed, and / or the temperature difference between the condensing temperature and the return air temperature, or the HP of the active indoor units 20, the indoor fan speed, and / or the temperature difference between the condensing temperature and the return air temperature.

[0138] To filter out the interference of the temperature difference between the capacity ratio of the operating indoor unit 20, the indoor fan speed, the condensing temperature and the return air temperature on the electronic expansion valve stuck fault recognition, in the present application, when judging whether the third characteristic variable combination appears the first abnormal state or the second abnormal state, the third characteristic variable combination is classified according to the preset interval of the operating indoor unit 20 capacity ratio (the number of HP of the indoor unit 20 in the operating state), the indoor fan speed, and / or the condensing temperature and the return air temperature, and under the corresponding category, whether the third characteristic variable combination appears the first abnormal state or the second abnormal state is judged.

[0139] For example, the operating indoor unit 20 capacity ratio can be divided into low, medium and high; the speed gear of the indoor fan can be divided into low speed, medium speed and high speed; the heat exchange temperature difference can be divided into small temperature difference, medium temperature difference and large temperature difference. Based on the classification result, the corresponding normal operation data is called from the pre-stored database, the normal operation data is the benchmark value obtained based on historical test or simulation, for example, the typical range of supercooling degree and indoor electronic expansion valve EVI opening degree adjustment amount under a specific operating indoor unit 20 capacity ratio, speed gear and temperature difference category, and further comparison of the current system state is made to judge whether the third characteristic variable combination appears the first abnormal state or the second abnormal state.

[0140] In the cooling mode, when there is an indoor unit 20 running, the outdoor electronic expansion valve EVO is in the high opening degree interval, its main function is to guide the flow of refrigerant, and does not perform throttling adjustment. Even if a stuck fault occurs, such a fault will not affect the normal operation of the system. In the present application, the stuck fault in this case is not diagnosed.

[0141] In an embodiment of the present application, the processing unit 30 is configured to perform the following steps:

[0142] Step S401: When the outdoor heat exchanger 12 is working, a plurality of state monitoring parameters of the outdoor unit 10 are sampled according to the preset third cooling mode rule.

[0143] In some embodiments of the present application, the state monitoring parameters sampled according to the preset third cooling mode rule include: the supercooler 14 inlet temperature and the outdoor heat exchanger 12 liquid pipe temperature .

[0144] The supercooler 14 inlet temperature is collected by a temperature sensor arranged on the main branch 15 of the supercooler 14 close to the outdoor heat exchanger 12; and the outdoor heat exchanger 12 liquid pipe temperature The temperature is collected by a temperature sensor located at the capillary tube of the lowest temperature branch behind the liquid pipe manifold of the outdoor heat exchanger 12. The liquid pipe manifold is used to evenly distribute the refrigerant into the heat exchanger, ensuring that the refrigerant is evenly distributed when entering the exchange area.

[0145] Step S402: Acquire characteristic variables based on the state monitoring parameters, and establish a fourth characteristic variable combination corresponding to a preset third cooling mode rule.

[0146] In some embodiments of the present application, the fourth characteristic variable combination includes: the liquid pipe temperature of the outdoor heat exchanger 12 and the inlet temperature of the subcooler 14 The temperature difference between .

[0147] Step S403: When it is identified that the fourth characteristic variable combination is in an abnormal state, the corresponding outdoor electronic expansion valve EVO is diagnosed to be stuck based on the abnormal state of the fourth characteristic variable combination, and it is identified that when the stuck fault occurs, the outdoor electronic expansion valve EVO is in a slightly open range or fully closed.

[0148] If the outdoor electronic expansion valve EVO is stuck and is in the slightly open range when the stuck fault occurs, the outdoor electronic expansion valve EVO will continue to over-throttle, resulting in a decrease in refrigerant flow and an increase in pressure drop; the inlet temperature of the subcooler 14 The temperature of the outdoor heat exchanger 12 liquid pipe is lower than the normal value. and the inlet temperature of the subcooler 14 The temperature difference between Will rise.

[0149] If the outdoor electronic expansion valve EVO is stuck and fully closed, the compressor 11 that continues to run will pump the high-temperature refrigerant into the outdoor heat exchanger 12. However, since the outdoor electronic expansion valve EVO is stuck, the heat cannot be released, and the liquid pipe temperature of the outdoor heat exchanger 12 is high. Will rise, the outdoor heat exchanger 12 liquid pipe temperature and the inlet temperature of the subcooler 14 The temperature difference between Will rise.

[0150] Therefore, at the corresponding outdoor heat exchanger 12 liquid pipe temperature and the inlet temperature of the subcooler 14 The temperature difference between The rising trend is shown and the rising amount exceeds the preset first outdoor threshold When , it is identified that the fourth characteristic variable combination is in an abnormal state.

[0151] Liquid temperature of outdoor heat exchanger 12 Temperature difference between sub-cooler 14 inlet temperature Compressor 11 operating frequency, ambient temperature and outdoor fan wind speed. The impact factor related to the fourth characteristic variable combination is the compressor 11 operating frequency, ambient temperature and outdoor fan wind speed. In order to filter out the interference of the compressor 11 operating frequency, ambient temperature and outdoor fan wind speed on the outdoor electronic expansion valve EVO stuck fault identification fault, in the present application, when judging whether the fourth characteristic variable combination is in an abnormal state, the fourth characteristic variable combination is classified according to the compressor 11 operating frequency, ambient temperature

[0152] The sub-cooler electronic expansion valve EVB is located on the heat exchange branch 16, and is used to accurately control the refrigerant flow and realize heat exchange between the main branch 15 and the heat exchange branch 16. Compared with the main branch 15, the heat exchange branch 16 handles smaller refrigerant flow, so a smaller aperture electronic expansion valve is usually selected to adapt to the low flow range and provide more accurate adjustment. The stuck fault of the sub-cooler electronic expansion valve EVB occurs in the high opening interval, which does not affect the normal use of the air conditioning system 1, and in the present application, the fault in this case is not diagnosed.

[0153] In an embodiment of the present application, the processing unit 30 is configured to perform the following steps:

[0154] Step S301: When the outdoor heat exchanger 12 is working, a plurality of state monitoring parameters of the outdoor unit 10 are sampled according to the preset sub-cooler heat exchanger electronic expansion valve diagnosis rule.

[0155] In some embodiments of the present application, the state monitoring parameters sampled according to the preset sub-cooler heat exchanger electronic expansion valve diagnosis rule include: the gas side temperature of the heat exchange branch 16, the liquid side temperature of the heat exchange branch 16 and the ambient temperature

[0156] Among them, the gas side temperature of the heat exchange branch 16 is collected by the temperature sensor arranged on the gas side of the heat exchange branch 16; the liquid side temperature of the heat exchange branch 16 is collected by the temperature sensor arranged on the liquid side of the heat exchange branch 16; and the ambient temperature is collected by the temperature sensor arranged outside the outdoor heat exchanger 12.

[0157] ​Step S302: Acquire characteristic variables based on the state monitoring parameters, and establish a fifth characteristic variable combination corresponding to a preset diagnostic rule for the electronic expansion valve of the subcooling heat exchanger.

[0158] In some embodiments of the present application, the fifth characteristic variable combination includes: the superheat degree of the heat exchange branch 16 , and the liquid side temperature of heat exchange branch 16 and ambient temperature The temperature difference between .

[0159] Superheat of heat exchange branch 16 satisfy , which represents the superheat of the refrigerant in the heat exchange branch 16.

[0160] Liquid side temperature of heat exchange branch 16 and ambient temperature The temperature difference between satisfy .

[0161] Step S303: When it is identified that the fifth characteristic variable combination is in an abnormal state, a stuck fault of the subcooler electronic expansion valve EVB is diagnosed based on the abnormal state of the fifth characteristic variable combination, and it is identified that when the stuck fault occurs, the subcooler electronic expansion valve EVB is in a slightly open range or fully closed.

[0162] If the subcooler electronic expansion valve EVB is stuck, and is in the slightly open range or fully closed when the stuck fault occurs, the flow of refrigerant into the heat exchange branch 16 is restricted, which will slow down the flow of refrigerant in the heat exchange branch 16, resulting in insufficient heat exchange process and abnormal temperature distribution, which is further reflected in the decrease of heat exchange efficiency and the superheat degree of the heat exchange branch 16. At the same time, due to the micro-opening range or fully closed stuck fault of the subcooler electronic expansion valve EVB, the refrigerant flow rate will be reduced, causing the pressure at the inlet of the heat exchange branch 16 to drop, and the liquid side temperature of the heat exchange branch 16 will be low. At this time, the ambient temperature is relatively stable. Therefore, the liquid side temperature of the heat exchange branch 16 and ambient temperature The temperature difference between Will decrease.

[0163] Therefore, the superheat degree in heat exchange branch 16 is The number of drops is greater than the preset second outdoor threshold. , and the liquid side temperature of heat exchange branch 16 and ambient temperature The temperature difference between The number of drops is greater than the preset threshold outside the third room. When the fifth characteristic variable combination is identified to be in an abnormal state.

[0164] The superheat degree of the heat exchange branch 16 The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature The temperature difference between the liquid side temperature of the heat exchange branch 16 and the ambient temperature

[0165] In the heating mode, when there is an indoor unit 20 running, the opening degree of the outdoor electronic expansion valve EVO is in the throttling interval. If the stuck fault occurs in the throttling opening interval, it will not affect the normal operation of the air conditioning system 1. In the present application, the stuck fault in this case is not diagnosed.

[0166] In an embodiment of the present application, the processing unit 30 is configured to perform the following steps:

[0167] Step S601: When the outdoor heat exchanger 12 is working, the state monitoring parameters of the outdoor unit 10 are sampled according to the preset second heating mode rule.

[0168] In some embodiments of the present application, the state monitoring parameters sampled according to the preset second heating mode rule include: the suction pressure of the compressor 11 , the discharge temperature of the compressor 11 , the discharge temperature of the compressor 11 .

[0169] Step S602: Obtain the characteristic variables based on the state monitoring parameters, and establish the sixth characteristic variable combination corresponding to the preset second heating mode rule.

[0170] In some embodiments of the present application, the sixth characteristic variable combination includes: the suction pressure of the compressor 11 .

[0171] Step S603: When the sixth feature variable combination is identified to be in an abnormal state, a corresponding outdoor electronic expansion valve EVO stuck fault is diagnosed according to the abnormal state of the sixth feature variable combination, and it is identified that the outdoor electronic expansion valve EVO is in a micro-opening opening interval or full-closed when the stuck fault occurs.

[0172] If the outdoor electronic expansion valve EVO has a stuck fault, and is in a micro-opening opening interval when the stuck fault occurs, the outdoor electronic expansion valve EVO only allows a small amount of refrigerant to pass through, and the flow is much lower than the demand of the air conditioning system 1. The evaporation efficiency is reduced due to insufficient supply of refrigerant in the evaporator, and the pressure cannot be maintained at a normal level. The suction pressure of the compressor 11 drops significantly.

[0173] If the outdoor electronic expansion valve EVO has a stuck fault, and is full-closed when the stuck fault occurs, the refrigerant cannot enter the outdoor heat exchanger 12, the amount of refrigerant in the evaporator is sharply reduced, and the evaporation process cannot be carried out. The compressor 11 continues to operate, but there is not enough low-pressure steam on the suction side, causing the suction pressure of the compressor 11 to drop rapidly.

[0174] Therefore, when the suction pressure of the compressor 11 presents a downward trend and the amount of decrease exceeds the preset fourth outdoor side threshold , it is identified that the sixth feature variable combination is in an abnormal state.

[0175] The suction pressure of the compressor 11 is related to the operating frequency of the compressor 11, the ambient temperature and the outdoor fan speed. The influence factors related to the sixth feature variable combination are the operating frequency of the compressor 11, the ambient temperature and the outdoor fan speed. In order to filter out the interference of the operating frequency of the compressor 11, the ambient temperature and the outdoor fan speed on the stuck fault identification of the outdoor electronic expansion valve EVO, in the present application, when judging whether the sixth feature variable combination is in an abnormal state, the sixth feature variable combination is classified according to the operating frequency of the compressor 11, the ambient temperature and the outdoor fan speed, and whether the sixth feature variable combination is in an abnormal state is judged in the corresponding category.

[0176] In an embodiment of the present application, the processing unit 30 is configured to perform the following steps:

[0177] Step S701: When the outdoor heat exchanger 12 is working, a plurality of state monitoring parameters of the outdoor unit 10 are sampled according to a preset third heating mode rule.

[0178] In some embodiments of the present application, the state monitoring parameters sampled according to the preset third heating mode rule include: the compressor 11 discharge pressure , the compressor 11 discharge temperature .

[0179] Step S702: Obtain feature variables based on the state monitoring parameters, and establish a seventh feature variable combination corresponding to the preset third heating mode rule.

[0180] In some embodiments of the present application, the seventh feature variable combination includes: the compressor 11 discharge superheat and the outdoor electronic expansion valve EVO opening degree adjustment amount ; wherein the compressor 11 discharge superheat satisfies , wherein is the condensing temperature corresponding to the compressor 11 discharge pressure.

[0181] Step S703: When the seventh feature variable combination is identified to be in an abnormal state, the corresponding outdoor electronic expansion valve EVO stuck fault is diagnosed according to the abnormal state of the seventh feature variable combination, and it is identified that the outdoor electronic expansion valve EVO is in a high opening degree interval when the stuck fault occurs.

[0182] When the outdoor electronic expansion valve EVO is stuck in the high opening degree interval, the refrigerant flow is too large, resulting in insufficient evaporation of the refrigerant in the outdoor electronic expansion valve EVO. Normally, the outdoor electronic expansion valve EVO is in the throttling working interval to ensure that the refrigerant is completely vaporized in the outdoor heat exchanger 12; but when the flow is too large, part of the refrigerant may flow to the compressor 11 inlet without being evaporated. The suction and discharge conditions of the compressor 11 are affected, further causing the compressor 11 discharge superheat to decrease. The built-in control algorithm (such as a PID controller) judges that the flow is too large when the compressor 11 discharge superheat decreases, and generates the outdoor electronic expansion valve EVO opening degree adjustment amount to reduce the opening degree.

[0183] Therefore, when the compressor 11 discharge superheat presents a downward trend and the decrease amount exceeds a preset fifth outdoor side threshold value , and the outdoor electronic expansion valve EVO opening degree adjustment amount presents a downward trend and the decrease amount exceeds a preset sixth outdoor side threshold value , it is identified that the seventh feature variable combination is in an abnormal state.

[0184] The compressor 11 discharge superheat is related to the compressor 11 operating frequency, the ambient temperature The sixth characteristic variable combination is related to the compressor 11 operating frequency, the ambient temperature and the outdoor fan speed The sixth characteristic variable combination is related to the compressor 11 operating frequency, the ambient temperature and the outdoor fan speed The sixth characteristic variable combination is related to the compressor 11 operating frequency, the ambient temperature and the outdoor fan speed The sixth characteristic variable combination is related to the compressor 11 operating frequency, the ambient temperature and the outdoor fan speed

[0185] In some embodiments of the present application, the processing unit 30 is further configured to perform the following steps: sampling a plurality of state monitoring parameters within a set period according to a preset rule; obtaining a characteristic variable based on the state monitoring parameters within the set period; and establishing a characteristic variable combination corresponding to the preset rule based on the average value of the characteristic variable within the set period.

[0186] Since the data fluctuation of the air conditioning system 1 during the start-up and stop phases is large and not referenceable, the data during the start-up and stop phases is removed when sampling a plurality of state monitoring parameters. Subsequently, a characteristic variable is obtained based on the state monitoring parameters within a set period according to a preset rule; a characteristic variable combination corresponding to the preset rule is established based on the average value of the characteristic variable within the set period; when judging whether the characteristic variable combination is abnormal, the characteristic variable combination is classified according to the influence factor related to the characteristic variable combination; and whether the characteristic variable combination is in an abnormal state is judged under the corresponding category.

[0187] The first indoor-side threshold value , the second indoor-side threshold value , the third indoor-side threshold value , the fourth indoor-side threshold value , the fifth indoor-side threshold value , the sixth indoor-side threshold value , the seventh indoor-side threshold value , the first outdoor-side threshold value , the second outdoor-side threshold value , the third outdoor-side threshold value , the fourth outdoor-side threshold value , the fifth outdoor-side threshold value , and the sixth outdoor-side threshold value may all be fixed values determined and stored based on the category for ready calling.

[0188] The processing unit 30 can also store a fault table as shown in the figure, realizing data-driven fault diagnosis of the electronic expansion valve of the multi-split air conditioning system 1.

[0189] In the present application, the high opening interval is the state that the electronic expansion valve approaches or reaches the maximum opening state, and the high flow control is used to optimize the refrigerant flow, for example, higher than 80%; the throttling opening interval is the state that the electronic expansion valve is partially opened, and is used for flow and pressure drop regulation, for example, 20% to 80%; the micro opening interval is the state that the valve is slightly opened, for example, 1%-10%; and the full closing refers to the completely closed state.

[0190] In the description of the above-mentioned embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0191] The above merely describes specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. Air conditioning system, including: The outdoor unit includes: Multiple outdoor heat exchangers, each of which is equipped with an outdoor electronic expansion valve; A subcooler comprising: a main branch connected to the outdoor heat exchanger; A heat exchange branch, which exchanges heat with the main branch, and a subcooler electronic expansion valve is provided on the heat exchange branch; Multiple indoor units, the indoor units comprising: An indoor heat exchanger is provided with an indoor electronic expansion valve; It is characterized by further comprising: A processing unit is configured to sample one or more state monitoring parameters according to preset rules, obtain characteristic variables based on the state monitoring parameters, and establish a characteristic variable combination corresponding to the preset rules; when an abnormal state occurs in the characteristic variable combination, diagnose the corresponding electronic expansion valve stuck fault based on the abnormal state of the characteristic variable combination, and the range of the opening of the corresponding electronic expansion valve when the stuck fault occurs.

2. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: Determine whether there is at least one indoor unit in the temperature control off state in the air conditioning system; during normal operation, the indoor electronic expansion valve corresponding to the indoor unit in the temperature control off state is fully closed; Determine whether there is at least one indoor unit in the temperature control on state in the air conditioning system; during normal operation, the indoor electronic expansion valve corresponding to the indoor unit in the temperature control on state is in the throttling opening range; If so, sampling various status monitoring parameters of the indoor unit in the temperature control off state according to the preset first cooling mode rule; Acquire characteristic variables based on the state monitoring parameters, and establish a first characteristic variable combination corresponding to a preset first cooling mode rule; The first characteristic variable combination includes: the temperature difference between the return air temperature and the gas pipe temperature of the indoor unit in the temperature control off state; When the temperature difference between the return air temperature and the gas pipe temperature of the indoor unit in the temperature control closed state shows an upward trend and the increase exceeds a preset first indoor side threshold, identifying that the first characteristic variable combination is in an abnormal state; Based on the abnormal state of the first characteristic variable combination, a stuck fault of the indoor electronic expansion valve in the corresponding indoor unit that is in the temperature-controlled closed state is diagnosed, and it is identified that when the stuck fault occurs, the opening of the indoor electronic expansion valve in the indoor unit that is in the temperature-controlled closed state is in the throttling opening range.

3. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: Determine whether there is at least one indoor unit in the air-conditioning system that is in the temperature control on state; during normal operation, the indoor electronic expansion valve corresponding to the indoor unit in the temperature control off state is in the throttling opening range; If so, sampling various status monitoring parameters of the indoor unit in the temperature control on state according to the preset second cooling mode rule; Acquire characteristic variables based on the state monitoring parameters, and establish a second characteristic variable combination corresponding to a preset second cooling mode rule; The second characteristic variable combination includes: indoor heat exchanger superheat and indoor electronic expansion valve opening adjustment amount; When the superheat of the indoor heat exchanger shows an upward trend and the increase exceeds a preset second indoor threshold, and the opening adjustment amount of the indoor electronic expansion valve shows an upward trend and the increase exceeds a preset third indoor threshold, it is recognized that the second characteristic variable combination is in a first abnormal state; Based on the first abnormal state of the second characteristic variable combination, a stuck fault of the indoor electronic expansion valve in the corresponding indoor unit in the temperature-controlled on state is diagnosed, and the opening degree of the indoor electronic expansion valve in the temperature-controlled on state is identified as being in a slightly open range when the stuck fault occurs. When the superheat of the indoor heat exchanger shows a downward trend and the amount of decrease exceeds a preset fourth indoor threshold, and the opening adjustment amount of the indoor electronic expansion valve shows an upward trend and the amount of increase exceeds a preset third indoor threshold, it is identified that the second characteristic variable combination is in a second abnormal state; Based on the second abnormal state of the second characteristic variable combination, the corresponding stuck fault of the indoor electronic expansion valve in the indoor unit that is in the temperature control open state is diagnosed, and it is identified that the indoor electronic expansion valve in the indoor unit that is in the temperature control open state is fully closed when the stuck fault occurs.

4. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: Determine whether there is at least one indoor unit in the air-conditioning system that is in a powered-on state; sampling various status monitoring parameters of the indoor unit according to a preset first heating mode rule; Acquire characteristic variables based on the state monitoring parameters, and establish a third characteristic variable combination corresponding to the preset first heating mode rule; The third characteristic variable combination includes the indoor heat exchanger subcooling degree and the indoor electronic expansion valve opening adjustment amount; When the subcooling degree of the indoor heat exchanger shows an upward trend and the increase exceeds the preset fifth indoor threshold, and the opening adjustment amount of the indoor electronic expansion valve shows an upward trend and the increase exceeds the preset sixth indoor threshold, it is identified that the third characteristic variable combination has a first abnormal state; diagnosing a stuck fault of an indoor electronic expansion valve in a corresponding indoor unit based on a first abnormal state of the third characteristic variable combination, and identifying that when the stuck fault occurs, the opening degree of the indoor electronic expansion valve in the indoor unit in the temperature control open state is in a slightly open range; When the subcooling degree of the indoor heat exchanger shows a downward trend and the amount of decrease exceeds the preset seventh indoor threshold, and at the same time, the opening adjustment amount of the indoor electronic expansion valve shows an upward trend and the amount of increase exceeds the preset sixth indoor threshold, it is identified that the third characteristic variable combination has a second abnormal state; According to the occurrence of the second abnormal state in the third characteristic variable combination, it is identified that the corresponding indoor electronic expansion valve has a stuck fault, and it is identified that when the stuck fault occurs, the corresponding indoor electronic expansion valve is fully closed.

5. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: When the outdoor heat exchanger is working, various status monitoring parameters of the outdoor unit are sampled according to the preset third cooling mode rules; Acquiring characteristic variables based on the state monitoring parameters, and establishing a fourth characteristic variable combination corresponding to a preset third cooling mode rule; The fourth characteristic variable combination includes: the temperature difference between the outdoor heat exchanger liquid pipe temperature and the subcooler inlet temperature; When the temperature difference between the corresponding outdoor heat exchanger liquid pipe temperature and the subcooler inlet temperature shows an upward trend and the increase exceeds a preset first outdoor side threshold, it is identified that the fourth characteristic variable combination is in an abnormal state; According to the abnormal state of the fourth characteristic variable combination, a stuck fault of the corresponding outdoor electronic expansion valve is diagnosed, and it is identified that when the stuck fault occurs, the outdoor electronic expansion valve is in a slightly open range or fully closed.

6. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: When the outdoor heat exchanger is working, various status monitoring parameters of the outdoor unit are sampled according to the preset diagnostic rules of the subcooling heat exchanger electronic expansion valve; Acquiring characteristic variables based on the state monitoring parameters, and establishing a fifth characteristic variable combination corresponding to a preset diagnostic rule for the subcooling heat exchanger electronic expansion valve; The fifth characteristic variable combination includes: the superheat of the heat exchange branch, and the temperature difference between the liquid side temperature of the heat exchange branch and the ambient temperature; When the superheat of the heat exchange branch shows a downward trend and the amount of decrease exceeds a preset second outdoor threshold, and the temperature difference between the liquid side temperature of the heat exchange branch and the ambient temperature shows a downward trend and the amount of decrease exceeds a preset third outdoor threshold, it is identified that the fifth characteristic variable combination is in an abnormal state; Based on the abnormal state of the fifth characteristic variable combination, a stuck fault of the subcooler electronic expansion valve is diagnosed, and it is identified that when the stuck fault occurs, the subcooler electronic expansion valve is in a slightly open range or fully closed.

7. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: When the outdoor heat exchanger is working, the state monitoring parameters of the outdoor unit are sampled according to the preset second heating mode rules; Acquire characteristic variables based on the state monitoring parameters, and establish a sixth characteristic variable combination corresponding to a preset second heating mode rule; The sixth characteristic variable combination includes: compressor suction pressure; When the compressor suction pressure shows a downward trend and the amount of decrease exceeds a preset threshold value outside the fourth chamber, it is identified that the sixth characteristic variable combination is in an abnormal state; According to the abnormal state of the sixth characteristic variable combination, a stuck fault of the corresponding outdoor electronic expansion valve is diagnosed, and it is identified that when the stuck fault occurs, the outdoor electronic expansion valve is in a slightly open range or fully closed.

8. The air conditioning system according to claim 1, characterized in that The processing unit is configured to perform the following steps: When the outdoor heat exchanger is working, various status monitoring parameters of the outdoor unit are sampled according to the preset third heating mode rules; Acquiring characteristic variables based on the state monitoring parameters, and establishing a seventh characteristic variable combination corresponding to a preset third heating mode rule; The seventh characteristic variable combination includes: compressor exhaust superheat and outdoor electronic expansion valve opening adjustment amount; When the compressor exhaust superheat shows a downward trend and the amount of decrease exceeds a preset fifth outdoor threshold, and the outdoor electronic expansion valve opening adjustment amount shows a downward trend and the amount of decrease exceeds a preset sixth outdoor threshold, it is identified that the seventh characteristic variable combination is in an abnormal state; When it is identified that the seventh characteristic variable combination is in an abnormal state, a stuck fault of the corresponding outdoor electronic expansion valve is diagnosed based on the abnormal state of the seventh characteristic variable combination, and it is identified that when the stuck fault occurs, the outdoor electronic expansion valve is in a high opening range.

9. The air conditioning system according to any one of claims 3 to 8, characterized in that: The processing unit is further configured to perform the following steps: When judging whether the characteristic variable combination is in an abnormal state, the characteristic variable combination is classified according to the influencing factors related to the characteristic variable combination, and under the corresponding category, Determine whether the feature variable combination is abnormal.

10. The air conditioning system according to claim 9, characterized in that The processing unit is further configured to perform the following steps: A plurality of state monitoring parameters are sampled within a set period; characteristic variables are obtained based on the state monitoring parameters within the set period; and a characteristic variable combination corresponding to a preset rule is established based on an average value of the characteristic variables within the set period.

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