Air conditioner fluorine deficiency detection method, device, system and air conditioner

Abstract

The application discloses a kind of air conditioner fluorine deficiency detection method, device, system and air conditioner, belong to fluorine deficiency detection field.There is fluorine deficiency phenomenon or not by exhaust superheat, real-time pressure ratio and heating capacity attenuation etc. Multidimensional parameters are comprehensively judged, after preliminary judgment fluorine deficiency, further forced execution four-way valve fault judgment process, aims at distinguishing similar symptoms caused by fluorine deficiency fault and four-way valve reversing abnormality, to avoid false report or misreport caused by component confusion, make fault location more accurate and reliable.The application scheme guarantees the timeliness of early warning, and excludes the interference of non-fluorine deficiency factors, greatly reduces the risk of unit false protection or frequent start-stop, lays a solid foundation for subsequent implementation of grading intervention measures, effectively guarantees the safety of air conditioning heating operation, energy efficiency stability, and prolongs the service life of compressor and other key components, improves the user comfort experience in winter heating.

Description

Technical Field

[0001] This application relates to the field of refrigerant deficiency detection technology, and in particular, to a method, apparatus, system, and air conditioner for detecting refrigerant deficiency in air conditioners. Background Technology

[0002] When a heating / cooling air conditioning system is in operation during winter, a refrigerant leak (commonly known as "refrigerant deficiency") not only leads to a significant decrease in heating capacity and energy efficiency ratio, but also causes a chain of malfunctions such as faster-than-normal frosting speed of the outdoor heat exchanger, shortened defrosting cycle, and ice formation on the indoor evaporator. In severe cases, it can cause the compressor to overheat and burn out. Most existing refrigerant deficiency detection technologies are adapted to cooling conditions, and suffer from a series of common industry pain points in heating mode, including detection failure, fault confusion, inability to automatically add refrigerant, and crude protection logic. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, this application provides an air conditioner refrigerant shortage detection method, device, system and air conditioner to solve the problems of detection failure, fault confusion, inability to automatically add refrigerant and crude protection logic in the existing refrigerant shortage detection technology in heating mode.

[0004] The technical solution adopted by this application to solve its technical problem is: Firstly, a method for detecting refrigerant shortage in air conditioners is provided, applicable to the heating mode of air conditioners, including: Obtain a first target parameter, which includes at least one of exhaust superheat, real-time pressure ratio, and heating capacity; Determine whether a fluoride deficiency has occurred based on the first target parameter; When a refrigerant shortage is detected, the four-way valve fault diagnosis procedure is executed to determine whether the four-way valve is faulty. If the four-way valve is determined to be normal, then the air conditioner is found to be low on refrigerant.

[0005] As an optional implementation of this application, it includes: After determining the refrigerant shortage, the second target parameters are obtained, including real-time exhaust superheat, real-time pressure ratio, and commutation response time. The current fluorine deficiency index FI is calculated based on the second target parameter: FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base +δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and α, β, and δ are preset weighting coefficients, the sum of which is 1. The severity of fluoride deficiency is determined based on the fluoride deficiency index, where a higher fluoride deficiency index indicates a more severe fluoride deficiency.

[0006] As an optional implementation of this application, it also includes: After determining the refrigerant shortage, the second target parameters are obtained, including real-time exhaust superheat, real-time pressure ratio, commutation response time, and defrosting frequency correction factor. The current refrigerant shortage index FI is calculated based on the second target parameter: FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base + β·(PR_act - PR_base) / PR_base + γ·k_df + δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and k_df is the defrosting frequency correction factor. , t1 is the standard frosting cycle under normal operating conditions of the air conditioner; t1 is the real-time actual frosting cycle; α, β, γ, and δ are preset weighting coefficients, and the sum of the four is 1. The severity of fluoride deficiency is determined based on the fluoride deficiency index, where a higher fluoride deficiency index indicates a more severe fluoride deficiency.

[0007] As an optional implementation of this application, it also includes: After obtaining the fluoride deficiency index, a target preset range to which the fluoride deficiency index belongs is determined, and each preset range corresponds to a control strategy. The air conditioner is controlled based on the target control strategy corresponding to the target preset range.

[0008] As an optional implementation of this application, determining the target preset range to which the fluoride deficiency index belongs includes: When the fluoride deficiency index is greater than the first threshold, it is determined that it belongs to the first preset range. The control strategy corresponding to the first preset range is: shutdown protection and reporting a fault code. When the fluoride deficiency index is greater than the second threshold and less than or equal to the first threshold, it is determined that it belongs to the second preset interval. The control strategy corresponding to the second preset interval is: frequency limiting protection and automatic fluoride addition. When the fluoride deficiency index is greater than the third threshold and less than or equal to the second threshold, it is determined that it belongs to the third preset interval. The control strategy corresponding to the third preset interval is: pop-up warning and limiting system power. When the fluoride deficiency index is less than or equal to the third threshold, it is determined that it belongs to the fourth preset interval. The control strategy corresponding to the fourth preset interval is to maintain the current operating state unchanged.

[0009] As an optional implementation of this application, the execution of the four-way valve fault judgment process includes: When the compressor stops, the power supply to the four-way valve coil is cut off and the initial pressure on the low-pressure side is obtained; A periodic pulse switching signal is applied to the four-way valve, and the rate of pressure change on the low-pressure side is detected; When the rate of change on the low-pressure side is greater than or equal to a preset rate of change, the four-way valve is determined to be functioning correctly; when the rate of change on the low-pressure side is less than the preset rate of change, the four-way valve is determined to be functioning correctly.

[0010] As an optional implementation of this application, determining whether a fluoride deficiency has occurred based on the first target parameter includes: A fluoride deficiency is determined to occur when any of the following conditions are met: The difference between the real-time exhaust superheat and the reference exhaust superheat is greater than the preset exhaust superheat difference. The difference between the real-time pressure ratio and the reference pressure ratio is greater than the preset pressure ratio difference. The heating capacity has decreased; The reduction in heating capacity is determined when at least two of the following conditions occur: Without reducing the compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature for a continuously preset duration is less than the first preset temperature difference. When the compressor frequency is greater than or equal to the preset compressor frequency, the difference between the indoor air outlet temperature and the indoor return air temperature is always less than the second preset temperature difference, wherein the second preset temperature difference is less than the first preset temperature difference. The difference between the intake superheat and the reference intake superheat is greater than the preset intake superheat difference.

[0011] Secondly, an air conditioner refrigerant shortage detection device is provided, applied in the air conditioner heating mode, including: The target parameter acquisition module is used to acquire a first target parameter, which includes at least one of exhaust superheat, real-time pressure ratio and heating capacity. The fluoride deficiency determination module is used to determine whether a fluoride deficiency has occurred based on the first target parameter. The reversing fault determination module is used to execute the four-way valve fault judgment process when a refrigerant shortage is detected, so as to determine whether the four-way valve is faulty. The air conditioner refrigerant shortage detection module is used to determine that the air conditioner is low on refrigerant when the four-way valve is determined to be functioning correctly.

[0012] Thirdly, an air conditioner refrigerant shortage detection system is provided, including: At least one processor and at least one memory; The memory stores the executable instructions of the processor; The processor is configured to perform any of the above-described air conditioner refrigerant shortage detection methods.

[0013] Fourthly, an air conditioner is provided, including the aforementioned air conditioner refrigerant detection system.

[0014] Beneficial effects: This application provides a method, device, system, and air conditioner for detecting refrigerant shortage. By comprehensively judging the problem using multi-dimensional parameters such as exhaust superheat, real-time pressure ratio, and heating capacity attenuation, it effectively overcomes the shortcomings of traditional single-factor detection methods, which are susceptible to environmental interference and have a high false alarm rate under heating conditions. This significantly improves the sensitivity and accuracy of refrigerant shortage detection. After initial judgment of refrigerant shortage, a four-way valve fault judgment process is further enforced to clearly distinguish between refrigerant shortage faults and similar symptoms caused by abnormal four-way valve reversal, thereby avoiding false alarms or misreports due to component confusion and making fault location more accurate and reliable. This application ensures timely early warning and eliminates interference from non-refrigerant shortage factors, greatly reducing the risk of unit false protection or frequent start-stop, laying a solid foundation for subsequent implementation of graded intervention measures. This effectively ensures the safety and energy efficiency stability of air conditioning heating operation, extends the service life of key components such as the compressor, and improves the user comfort experience during winter heating. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of an air conditioner refrigerant deficiency detection method provided in an embodiment of this application; Figure 2 This is a flowchart of a specific air conditioner refrigerant deficiency detection method provided in an embodiment of this application; Figure 3 This is a flowchart of a four-way valve fault diagnosis method provided in an embodiment of this application; Figure 4 This is a schematic diagram of an air conditioner structure provided in an embodiment of this application; Figure 5 This is a schematic diagram of the three-level correlation mapping model of the heating mode "operating condition-fault-control" provided in the embodiments of this application; Figure 6 This is a flowchart of a heating system refrigerant deficiency detection and grading control provided in an embodiment of this application; Figure 7 This is a schematic diagram illustrating the diagnostic capability of a four-way valve for false commutation, provided in an embodiment of this application. Figure 8 This is a flowchart illustrating the combined judgment of frosting characteristics and fluoride deficiency degree provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of an air conditioner refrigerant shortage detection device provided in an embodiment of this application; Figure 10 This is a schematic diagram of an air conditioner refrigerant shortage detection system provided in an embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: 01-Compressor; 02-Exhaust temperature sensor; 03-Exhaust pressure sensor; 04-Four-way valve; 05-Indoor heat exchanger; 06-Throttling components; 07-Outdoor heat exchanger; 08 - Intake temperature sensor; 09-Inhalation pressure sensor; 10 - First flow valve; 11-Liquid storage tank; 12-Second Flow Valve 13-First ambient temperature sensor; 14 - Second ambient temperature sensor. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Existing fluoride deficiency detection technologies have the following problems: The detection algorithm is only compatible with cooling mode, and its accuracy in detecting heating is extremely low. Existing refrigerant shortage detection solutions are all designed based on cooling operation. For example, CN108131776A relies on the difference between the indoor coil temperature and the room temperature to determine refrigerant shortage, but this logic only applies to cooling mode. In heating mode, the indoor heat exchanger switches from evaporator to condenser, and the pipe temperature and temperature difference change completely, so directly applying the algorithm will result in serious misjudgments. If the air conditioner operates normally in summer but refrigerant leaks in autumn and winter, the system will not be able to identify the refrigerant shortage fault during winter heating operation, and long-term operation in a refrigerant shortage state can easily damage the equipment.

[0020] (2) Unable to distinguish between heating refrigerant shortage fault and four-way valve reversing fault. The two main causes of poor air conditioning heating performance are insufficient refrigerant and abnormal switching of the four-way valve. These two types of faults are highly coupled and mutually influential: insufficient refrigerant will lead to insufficient system pressure difference, causing the four-way valve to fail to switch; leakage of gas in the four-way valve and improper switching will also directly lead to a decrease in heating performance.

[0021] Current technologies lack a fault decoupling and identification mechanism, making it impossible to distinguish the root cause of a fault. In practical maintenance, a typical coupling phenomenon exists: the entire four-way valve pipeline overheats, seemingly indicating a reversing fault, but in reality, it's due to insufficient refrigerant causing inadequate reversing pressure. Refilling the refrigerant restores normal operation. Current algorithms cannot accurately differentiate between these two causes, resulting in a very high false alarm rate. In other words, when a refrigerant shortage fault occurs in heating mode, current detection methods can only identify it as a four-way valve reversing fault based on the fault symptoms, failing to distinguish between the two.

[0022] (3) The automatic refrigerant charging interface in heating mode is malfunctioning, and the refrigerant charging operation is cumbersome. Existing patents for automatic refrigerant charging (CN210320757U, CN206176839U, etc.) are all designed based on cooling operation. During heating operation, the air conditioning system switches between high and low pressure circuits. The service port of the conventional coarse shut-off valve needle valve is on the high-pressure side (approximately 1.8±0.2MPa), making direct refrigerant charging impossible. Current technologies typically involve forcibly disconnecting the four-way valve wiring and switching to cooling mode for refrigerant charging. This process is cumbersome and complex, and deviates from actual heating operation conditions. It cannot determine the true refrigerant level based on the heating outlet temperature and overall unit load, making it highly susceptible to overcharging or undercharging.

[0023] (4) No dedicated tiered protection mechanism for heating, and the control logic is crude. Refrigerant shortage faults are gradual and are classified into three levels: minor, moderate, and severe, with vastly different impacts on equipment and user experience.

[0024] Existing patents all use a single protection logic of immediate shutdown after determining refrigerant shortage: in the case of slight refrigerant shortage, the machine is shut down abruptly, directly interrupting the user's winter heating, resulting in a very poor experience; in the case of severe refrigerant shortage, the response is delayed, and the compressor cannot be protected in time, causing irreversible burn-out damage, without a graded and adaptive fine control strategy.

[0025] (5) The interference between normal frosting and abnormal frosting due to fluorine deficiency cannot be separated. Frosting of outdoor heat exchangers under heating conditions is a normal physical phenomenon. However, refrigerant deficiency significantly accelerates the frosting process and shortens the defrosting cycle. Furthermore, the degree of refrigerant deficiency is positively correlated with the degree of abnormal frosting. It is impossible to quantitatively distinguish between normal frosting under operating conditions and abnormal frosting caused by refrigerant deficiency. Fluctuations in frosting and defrosting parameters can severely interfere with the detection and judgment of refrigerant deficiency, leading to a significant increase in the false alarm rate of refrigerant deficiency under heating conditions.

[0026] To address the aforementioned issues, this application provides a method for checking refrigerant shortage in air conditioners during heating mode. The details are as follows: Example 1:

[0027] This application provides a method for detecting refrigerant shortage in an air conditioner, applied in the heating mode. It is understood that in cooling mode or other modes, using existing technology, the refrigerant shortage detection method provided in this application, such as... Figure 1 As shown, it includes: S11: Obtain a first target parameter, the first target parameter including at least one of exhaust superheat, real-time pressure ratio and heating capacity; Wherein, exhaust superheat = real-time exhaust temperature - condensation saturation temperature.

[0028] Pressure ratio = High-pressure side pressure / Low-pressure side pressure. Wherein, the high-pressure side is the outlet of the indoor heat exchanger; the low-pressure side is the compressor suction port or the outlet of the gas-liquid separator (i.e., the position before the low-pressure steam after evaporation in the outdoor heat exchanger enters the compressor).

[0029] Heating capacity can be calculated using the difference between the indoor supply air temperature and the indoor return air temperature.

[0030] S12: Determine whether a fluoride deficiency has occurred based on the first target parameter; The step of determining whether a fluoride deficiency has occurred based on the first target parameter includes: A fluoride deficiency is determined to occur when any of the following conditions are met: The difference between the real-time exhaust superheat and the baseline exhaust superheat is greater than the preset exhaust superheat difference. When refrigerant is insufficient, the refrigerant flow rate entering the evaporator (outdoor unit) is significantly reduced, resulting in a sharp drop in evaporation pressure and temperature, and a sharp increase in compressor suction superheat. At the same time, due to insufficient circulating refrigerant mass flow rate, there is less liquid refrigerant in the condenser (indoor unit), and the proportion of high-temperature superheated gas discharged increases, making the measured exhaust temperature much higher than the saturation temperature at that pressure, thus the exhaust superheat seriously exceeds the normal baseline value.

[0031] The difference between the real-time pressure ratio and the reference pressure ratio is greater than the preset pressure ratio difference. When refrigerant is insufficient, the pressure drop on the low-pressure side (compressor suction port) is particularly significant due to insufficient liquid supply from the evaporator. While the pressure on the high-pressure side also drops, the magnitude is much smaller than that on the low-pressure side, causing the overall pressure ratio to deviate significantly from the normal operating range (usually manifested as an abnormally high pressure ratio). This deviation directly reflects the greater compression power consumption required by the compressor to maintain heating, and is a direct manifestation of the imbalance in the system's cycle driving force.

[0032] Reduced heating capacity. Refrigerant is the carrier of heat; a decrease in its mass directly leads to a simultaneous decrease in the amount of heat absorbed from the outside and released into the room per unit time. Specifically, assuming the compressor frequency remains constant, the temperature difference between the inlet and outlet of the indoor heat exchanger (condenser) narrows, the outlet air temperature decreases, and the system fails to achieve the target heating effect. This criterion, from the final output result, verifies the deterioration of heat exchange capacity caused by insufficient refrigerant.

[0033] In a preferred implementation of this application, the reduction in heating capacity is determined when at least two of the following conditions occur: Without reducing the compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature for a continuously preset duration is less than the first preset temperature difference; the heating capacity is directly reflected in the temperature difference between the indoor unit's outlet and return air. Theoretically, with the compressor frequency (i.e., speed) remaining constant, the refrigerant circulation volume should be constant, and the heating capacity should be relatively stable. If the temperature difference remains consistently lower than the normal baseline, it indicates that the system's heat exchange output has significantly decreased under the same input power, ruling out factors causing a reduction in normal capacity due to frequency reduction control, and directly pointing to insufficient refrigerant leading to a decrease in effective heat exchange capacity.

[0034] When the compressor frequency is greater than or equal to the preset compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature remains less than the second preset temperature difference, which is less than the first preset temperature difference. When the compressor operating frequency reaches a high level, it indicates that the indoor and outdoor temperature difference is large or the user-set temperature is high, and the system is outputting heating at full capacity. In this high-load scenario, if the outlet and return air temperature difference does not even reach the lower second preset temperature difference, it indicates that the system is severely lacking in refrigerant to support the circulation flow required for high-frequency operation. At this time, the degree of heating attenuation is more significant than in normal operating conditions. Sensitive detection can be achieved by setting a smaller threshold separately.

[0035] The difference between the suction superheat and the reference suction superheat is greater than the preset suction superheat difference. Suction superheat = suction temperature - suction pressure corresponding to saturation temperature. Insufficient refrigerant leads to inadequate refrigerant supply to the outdoor evaporator, causing the liquid refrigerant to vaporize completely at the front end of the evaporator tubes. Subsequent tube sections cannot effectively absorb heat, resulting in a sharp increase in suction temperature, and the measured superheat far exceeds the normal reference.

[0036] S13: When a refrigerant shortage is detected, execute the four-way valve fault judgment procedure to determine whether the four-way valve is faulty. As a preferred implementation of the embodiments of this application, such as Figure 3 As shown, the four-way valve fault diagnosis process includes: When the compressor stops, the power supply to the four-way valve coil is cut off and the initial pressure on the low-pressure side is obtained; wherein, the compressor stops immediately. Alternatively, the compressor can stop when the system is running normally (such as stopping when the temperature is reached). The specific setting can be set according to actual needs, and this application embodiment does not limit it. A periodic pulse switching signal is applied to the four-way valve, and the rate of pressure change on the low-pressure side is detected; When the rate of change on the low-pressure side is greater than or equal to a preset rate of change, the four-way valve is determined to be functioning correctly; when the rate of change on the low-pressure side is less than the preset rate of change, the four-way valve is determined to be functioning correctly.

[0037] When the compressor stops, the high and low pressure sides of the system tend to balance. Cutting off the power supply to the four-way valve coil resets the main slide valve to its initial position, and the initial pressure on the low-pressure side is recorded as a reference. Subsequently, a periodic pulse reversing signal is applied, energizing the electromagnetic pilot valve and guiding high-pressure gas through the capillary tube to move the main slide valve. If the four-way valve is mechanically flexible (no fault): the main slide valve quickly completes the reversing under pulse drive, the high and low pressure passages inside the system are redistributed, and high-pressure refrigerant instantaneously enters the originally closed low-pressure side cavity, causing a rapid jump in the low-pressure side pressure (rate of change ≥ preset value). If the four-way valve is mechanically stuck (fault): the main slide valve cannot move due to burrs, deformation, or oil adhesion, the internal flow channel remains unchanged, there is no switching between high and low pressure sides, and the low-pressure side pressure changes slowly or remains basically unchanged due to a small leak (rate of change < preset value). This method, under the safe condition of the compressor being stationary, utilizes the dynamic pressure response rate at the moment of reversing to accurately distinguish between the mechanically stuck and normal state of the four-way valve, effectively eliminating the interference of valve faults on refrigerant shortage detection.

[0038] Based on the same inventive concept, this application may also use any one of the following to determine whether the four-way valve is faulty: response delay time (i.e., the time from when the coil is energized to when the valve core is in place, specifically the time from when the coil is energized to when the low-pressure side pressure reaches an inflection point), static differential pressure holding capability (i.e., after the commutation is completed, the coil is kept de-energized and the drop in low-pressure side pressure is observed within a preset time, which is used to characterize the piston sealing after the valve core is in place), or valve body pipe temperature difference (i.e., the temperature difference between the D pipe connected to the indoor unit and the S pipe connected to the compressor suction pipe, which is used to characterize the degree of internal air leakage).

[0039] S14: If the four-way valve is determined to be not faulty, determine that the air conditioner is low on refrigerant.

[0040] It should be noted that when determining a four-way valve malfunction, there are two scenarios: one is that the air conditioner is not low on refrigerant, meaning the refrigerant shortage is entirely caused by the four-way valve malfunction; the other is that the air conditioner is simultaneously low on refrigerant, meaning the refrigerant shortage is caused by both the four-way valve malfunction and the refrigerant shortage. In this case, the four-way valve malfunction must be resolved first to ensure its normal operation. Then, based on the first target parameter, it should be determined whether a refrigerant shortage still exists. If a refrigerant shortage still exists, it can be directly determined that the air conditioner is low on refrigerant, or it can be determined according to steps S13-S14 of this application.

[0041] The air conditioner refrigerant shortage detection method provided in this application is specifically designed for heating mode. It integrates multiple parameters such as exhaust superheat, real-time pressure ratio, and heating capacity for comprehensive judgment, effectively avoiding single-factor misjudgments. A four-way valve fault troubleshooting process is specifically added, utilizing a periodic pulse reversing signal applied while the compressor is stopped and monitoring the low-pressure side pressure change rate to accurately distinguish between mechanical jamming and normal operation, completely resolving the industry pain point of confusing refrigerant shortage symptoms with reversing valve malfunction characteristics. This method, with its simple and efficient two-level diagnostic architecture, significantly improves the accuracy and reliability of refrigerant shortage detection, providing solid technical support for the accurate identification of refrigerant leaks in heating mode.

[0042] It should be noted that any process or method description in the flowchart or otherwise described herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which the embodiments of this application pertain.

[0043] Furthermore, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] Example 2:

[0045] This application provides a specific method for detecting refrigerant shortage in an air conditioner, applied to the air conditioner's heating mode. It is understood that in cooling mode or other modes, using existing technology, the air conditioner refrigerant shortage detection method provided in this application embodiment, such as... Figure 2 As shown, it includes: S21: Obtain a first target parameter, the first target parameter including at least one of exhaust superheat, real-time pressure ratio and heating capacity; Wherein, exhaust superheat = real-time exhaust temperature - condensation saturation temperature.

[0046] Pressure ratio = High-pressure side pressure / Low-pressure side pressure. Wherein, the high-pressure side is the outlet of the indoor heat exchanger; the low-pressure side is the compressor suction port or the outlet of the gas-liquid separator (i.e., the position before the low-pressure steam after evaporation in the outdoor heat exchanger enters the compressor).

[0047] Heating capacity can be calculated using the difference between the indoor supply air temperature and the indoor return air temperature.

[0048] S22: Determine whether a fluoride deficiency has occurred based on the first target parameter; The step of determining whether a fluoride deficiency has occurred based on the first target parameter includes: A fluoride deficiency is determined to occur when any of the following conditions are met: The difference between the real-time exhaust superheat and the baseline exhaust superheat is greater than the preset exhaust superheat difference. When refrigerant is insufficient, the refrigerant flow rate entering the evaporator (outdoor unit) is significantly reduced, resulting in a sharp drop in evaporation pressure and temperature, and a sharp increase in compressor suction superheat. At the same time, due to insufficient circulating refrigerant mass flow rate, there is less liquid refrigerant in the condenser (indoor unit), and the proportion of high-temperature superheated gas discharged increases, making the measured exhaust temperature much higher than the saturation temperature at that pressure, thus the exhaust superheat seriously exceeds the normal baseline value.

[0049] The difference between the real-time pressure ratio and the reference pressure ratio is greater than the preset pressure ratio difference. When refrigerant is insufficient, the pressure drop on the low-pressure side (compressor suction port) is particularly significant due to insufficient liquid supply from the evaporator. While the pressure on the high-pressure side also drops, the magnitude is much smaller than that on the low-pressure side, causing the overall pressure ratio to deviate significantly from the normal operating range (usually manifested as an abnormally high pressure ratio). This deviation directly reflects the greater compression power consumption required by the compressor to maintain heating, and is a direct manifestation of the imbalance in the system's cycle driving force.

[0050] Reduced heating capacity. Refrigerant is the carrier of heat; a decrease in its mass directly leads to a simultaneous decrease in the amount of heat absorbed from the outside and released into the room per unit time. Specifically, assuming the compressor frequency remains constant, the temperature difference between the inlet and outlet of the indoor heat exchanger (condenser) narrows, the outlet air temperature decreases, and the system fails to achieve the target heating effect. This criterion, from the final output result, verifies the deterioration of heat exchange capacity caused by insufficient refrigerant.

[0051] In a preferred implementation of this application, the reduction in heating capacity is determined when at least two of the following conditions occur: Without reducing the compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature for a continuously preset duration is less than the first preset temperature difference; the heating capacity is directly reflected in the temperature difference between the indoor unit's outlet and return air. Theoretically, with the compressor frequency (i.e., speed) remaining constant, the refrigerant circulation volume should be constant, and the heating capacity should be relatively stable. If the temperature difference remains consistently lower than the normal baseline, it indicates that the system's heat exchange output has significantly decreased under the same input power, ruling out factors causing a reduction in normal capacity due to frequency reduction control, and directly pointing to insufficient refrigerant leading to a decrease in effective heat exchange capacity.

[0052] When the compressor frequency is greater than or equal to the preset compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature remains less than the second preset temperature difference, which is less than the first preset temperature difference. When the compressor operating frequency reaches a high level, it indicates that the indoor and outdoor temperature difference is large or the user-set temperature is high, and the system is outputting heating at full capacity. In this high-load scenario, if the outlet and return air temperature difference does not even reach the lower second preset temperature difference, it indicates that the system is severely lacking in refrigerant to support the circulation flow required for high-frequency operation. At this time, the degree of heating attenuation is more significant than in normal operating conditions. Sensitive detection can be achieved by setting a smaller threshold separately.

[0053] The difference between the suction superheat and the reference suction superheat is greater than the preset suction superheat difference. Suction superheat = suction temperature - suction pressure corresponding to saturation temperature. Insufficient refrigerant leads to inadequate refrigerant supply to the outdoor evaporator, causing the liquid refrigerant to vaporize completely at the front end of the evaporator tubes. Subsequent tube sections cannot effectively absorb heat, resulting in a sharp increase in suction temperature, and the measured superheat far exceeds the normal reference.

[0054] S23: When a refrigerant shortage is detected, execute the four-way valve fault judgment procedure to determine whether the four-way valve is faulty; As a preferred implementation of the embodiments of this application, such as Figure 3 As shown, the four-way valve fault diagnosis process includes: When the compressor stops, the power supply to the four-way valve coil is cut off and the initial pressure on the low-pressure side is obtained; wherein, the compressor stops immediately. Alternatively, the compressor can stop when the system is running normally (such as stopping when the temperature is reached). The specific setting can be set according to actual needs, and this application embodiment does not limit it. A periodic pulse switching signal is applied to the four-way valve, and the rate of pressure change on the low-pressure side is detected; When the rate of change on the low-pressure side is greater than or equal to a preset rate of change, the four-way valve is determined to be functioning correctly; when the rate of change on the low-pressure side is less than the preset rate of change, the four-way valve is determined to be functioning correctly.

[0055] When the compressor stops, the high and low pressure sides of the system tend to balance. Cutting off the power supply to the four-way valve coil resets the main slide valve to its initial position, and the initial pressure on the low-pressure side is recorded as a reference. Subsequently, a periodic pulse reversing signal is applied, energizing the electromagnetic pilot valve and guiding high-pressure gas through the capillary tube to move the main slide valve. If the four-way valve is mechanically flexible (no fault): the main slide valve quickly completes the reversing under pulse drive, the high and low pressure passages inside the system are redistributed, and high-pressure refrigerant instantaneously enters the originally closed low-pressure side cavity, causing a rapid jump in the low-pressure side pressure (rate of change ≥ preset value). If the four-way valve is mechanically stuck (fault): the main slide valve cannot move due to burrs, deformation, or oil adhesion, the internal flow channel remains unchanged, there is no switching between high and low pressure sides, and the low-pressure side pressure changes slowly or remains basically unchanged due to a small leak (rate of change < preset value). This method, under the safe condition of the compressor being stationary, utilizes the dynamic pressure response rate at the moment of reversing to accurately distinguish between the mechanically stuck and normal state of the four-way valve, effectively eliminating the interference of valve faults on refrigerant shortage detection.

[0056] Based on the same inventive concept, this application may also use any one of the following to determine whether the four-way valve is faulty: response delay time (i.e., the time from when the coil is energized to when the valve core is in place, specifically the time from when the coil is energized to when the low-pressure side pressure reaches an inflection point), static differential pressure holding capability (i.e., after the commutation is completed, the coil is kept de-energized and the drop in low-pressure side pressure is observed within a preset time, which is used to characterize the piston sealing after the valve core is in place), or valve body pipe temperature difference (i.e., the temperature difference between the D pipe connected to the indoor unit and the S pipe connected to the compressor suction pipe, which is used to characterize the degree of internal air leakage).

[0057] S24: If it is determined that the four-way valve is not faulty, then the air conditioner is found to be low on refrigerant.

[0058] It should be noted that when determining a four-way valve malfunction, there are two scenarios: one is that the air conditioner is not low on refrigerant, meaning the refrigerant shortage is entirely caused by the four-way valve malfunction; the other is that the air conditioner is simultaneously low on refrigerant, meaning the refrigerant shortage is caused by both the four-way valve malfunction and the refrigerant shortage. In this case, the four-way valve malfunction must be resolved first to ensure its normal operation. Then, based on the first target parameter, it should be determined whether a refrigerant shortage still exists. If a refrigerant shortage still exists, it can be directly determined that the air conditioner is low on refrigerant, or it can be determined according to steps S23-S24 of this application.

[0059] S25: After determining that there is a refrigerant shortage, obtain the second target parameters, which include real-time exhaust superheat, real-time pressure ratio, reversing response time (and defrosting frequency correction factor). S26: Calculate the current fluoride deficiency index FI based on the second target parameter; determine the severity of fluoride deficiency based on the fluoride deficiency index, wherein the larger the fluoride deficiency index, the more severe the fluoride deficiency; In one embodiment, FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base +δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and α, β, and δ are preset weighting coefficients, the sum of which is 1; In another embodiment, FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base + γ·k_df + δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and k_df is the defrosting frequency correction factor. , t1 is the standard frosting cycle under normal operating conditions of the air conditioner; t1 is the real-time actual frosting cycle; α, β, γ, and δ are preset weighting coefficients, and the sum of the four is 1.

[0060] In other words, this embodiment introduces a defrosting frequency correction factor based on the above embodiment. The core reason for introducing the defrosting frequency correction factor is that, in heating mode, the frosting speed of the outdoor heat exchanger is a "sensitive indicator" reflecting the refrigerant circulation volume of the system, while traditional thermodynamic parameters (exhaust superheat, pressure ratio) have response lag or signal distortion under frosting conditions.

[0061] Specifically, when an air conditioner is heating, the outdoor unit acts as the evaporator. Insufficient refrigerant leads to significantly lower evaporation pressure and temperature, causing a sharp increase in the temperature difference between the outdoor coil surface and the air, thus accelerating condensation and frosting. In other words, the more severe the refrigerant deficiency, the shorter the actual frosting cycle (t1), and the more significant the deviation compared to the normal cycle (tnormal), resulting in a positive increase in k_df. Exhaust superheat and pressure ratio are easily affected by fluctuations in ambient temperature and compressor frequency, causing instantaneous changes; these are considered "rapidly changing" parameters. The change in frosting speed reflects the cumulative damage to the evaporator's heat exchange capacity caused by refrigerant deficiency. Introducing k_df is equivalent to adding a "slowly changing" inertial correction dimension, making the refrigerant deficiency index (FI) smoother and more stable under dynamic operating conditions. Especially in the early stages of refrigerant deficiency, the deviation in exhaust superheat or pressure ratio may not yet reach a significant threshold, but the drop in evaporation temperature is sufficient to shorten the frosting cycle. k_df can capture this early sign, significantly improving detection sensitivity and avoiding missed diagnoses.

[0062] S27: After obtaining the fluoride deficiency index, determine the target preset range to which the fluoride deficiency index belongs, and each preset range corresponds to a control strategy; Determining the target preset range to which the fluoride deficiency index belongs includes: When the refrigerant deficiency index exceeds a first threshold, it is determined to fall within a first preset range. The control strategy corresponding to the first preset range is: shutdown protection and fault code reporting. When the refrigerant deficiency index exceeds the first threshold, it indicates that the system is in a severe refrigerant deficiency state, the highest risk level. At this time, the refrigerant flow into the compressor is extremely scarce, failing to effectively cool the motor windings and remove compression heat, leading to a sharp rise in exhaust temperature. This easily causes the refrigeration oil to carbonize at high temperatures, lose its lubricating properties, and subsequently cause irreversible damage such as compressor seizure or coil burnout. Simultaneously, the system's circulating pressure ratio is severely imbalanced, and heating output is almost ineffective. Continuing to operate is neither meaningful for heating nor does it significantly waste electrical energy. Taking the "shutdown protection and fault code reporting" approach is the last resort hard safety intervention measure, aiming to physically cut off the source of danger, remind users to report repairs in a timely manner by clearly locating the fault code, and at the same time avoid secondary damage caused by repeated start-ups and shutdowns of the system under extreme operating conditions.

[0063] When the refrigerant deficiency index is greater than the second threshold and less than or equal to the first threshold, it is determined to be in the second preset range. The control strategy corresponding to the second preset range is: frequency limiting protection and automatic refrigerant charging. When the refrigerant deficiency index is in the second preset range, it indicates that the system is in a moderately severe refrigerant deficiency state - the refrigerant is obviously insufficient, which leads to an increase in compressor discharge temperature, an increase in pressure ratio, and a deterioration in lubrication conditions. However, the system has not yet entered an extremely dangerous operating condition and still has a certain heating output capacity and operating margin.

[0064] At this point, a strategy of "frequency limiting protection and automatic refrigerant charging" is adopted, with the following logic: Frequency limiting protection is necessary because the compressor frequency directly determines the refrigerant circulation volume and suction specific volume. Reduced frequency operation simultaneously lowers the compressor's discharge temperature and pressure ratio, alleviating mechanical load and thermal stress, and effectively curbing the risk of high-temperature carbonization of the refrigeration oil. Simultaneously, under conditions of insufficient refrigerant supply, reduced frequency raises the evaporation temperature, slowing down the abnormal frosting rate of the outdoor heat exchanger and maintaining the system in a relatively safe "sub-healthy" state for continuous heating, avoiding unnecessary shutdowns that could cause users to completely lose their heating experience. Furthermore, automatic refrigerant charging requires adding liquid refrigerant to the system. If the compressor is operating at high frequency and high load, and the suction pressure is too low, the added refrigerant may not be smoothly drawn into the compression chamber, potentially even causing liquid slugging. After frequency limiting, the system pressure ratio narrows, and the suction superheat decreases, making it easier for the added refrigerant to participate in normal circulation and distribute evenly, ensuring the effectiveness and safety of the refrigerant charging process. Additionally, the second preset interval is a window period for "active intervention and recovery." Compared to the forced shutdown in the first preset range, this approach combines frequency limiting and load reduction with active refrigerant replenishment. This avoids the impact of abrupt shutdown on user operation while allowing the system to return to normal operating conditions through refrigerant replenishment, striking a balance between safety and comfort. If the refrigerant frequency (FI) continues to drop after frequency limiting and refrigerant replenishment, the system can gradually resume high-frequency operation; if the FI continues to climb to the first threshold, it will be upgraded to shutdown protection.

[0065] When the refrigerant deficiency index is greater than the third threshold and less than or equal to the second threshold, it is determined to belong to the third preset interval. The control strategy corresponding to the third preset interval is: pop-up warning and system power limitation. When the refrigerant deficiency index is in the third preset interval, it indicates that the system is in the early warning stage of slight refrigerant deficiency—the refrigerant circulation volume is somewhat lacking, but the degree is still mild. The compressor's exhaust temperature, pressure ratio, and lubrication conditions have not yet reached a dangerous critical state, and the system still basically has effective heating output capacity, with the performance degradation within an acceptable range. Although slight refrigerant deficiency does not pose an immediate safety threat, if left untreated, the leak will continue to worsen, eventually evolving into moderate to severe refrigerant deficiency. Therefore, by pushing a "Refrigerant insufficient, maintenance recommended" pop-up window to the user on the air conditioner display panel or mobile app, the user can be informed of the current operating status and prompted to contact after-sales service to replenish refrigerant at an appropriate time, avoiding more serious damage after the fault worsens. Furthermore, this section does not employ harsh measures such as shutdown or significant frequency limiting. Instead, it only moderately restricts system power (e.g., slightly reducing the upper limit of compressor operating frequency or adjusting the electronic expansion valve opening). The aim is to moderately reduce the system's cyclic load, allowing the discharge temperature, pressure ratio, and suction superheat to drop slightly. This prevents the leakage process from being accelerated by continuous high-frequency operation and also provides more sufficient heat absorption time for the refrigerant in the evaporator, delaying the abnormal frosting trend of the outdoor heat exchanger. Compared to the "frequency limiting + automatic refrigerant charging" in the second section, the power restriction here is more moderate and does not involve active refrigerant replenishment. This is because adding refrigerant is not urgently necessary at this point, and early leak points may not have been eliminated yet. Blindly adding refrigerant would only waste resources and pose environmental risks.

[0066] When the refrigerant deficiency index is less than or equal to the third threshold, it is determined to belong to the fourth preset interval. The control strategy corresponding to the fourth preset interval is to maintain the current operating state. When the refrigerant deficiency index is less than or equal to the third threshold, it indicates that the system is in a normal operating state with sufficient refrigerant or only a very slight deviation—the current exhaust superheat, pressure ratio, heating capacity, and other core parameters are all within the preset normal fluctuation range, the compressor's operating load, exhaust temperature, and lubrication conditions have no abnormal risks, and the system's various performance indicators can meet the user's heating needs, requiring no intervention. Generally, the refrigerant deficiency index (FI) will not fall within the fourth preset interval when a refrigerant deficiency is determined. If it does, it will be recalculated.

[0067] S28: Control the air conditioner based on the target control strategy corresponding to the target preset interval.

[0068] The air conditioner refrigerant shortage detection method provided in this application constructs a full-chain intelligent diagnostic system for heating mode, from "preliminary judgment - valve elimination - index quantification - graded response". First, it integrates multi-dimensional parameters such as exhaust superheat, pressure ratio, and heating capacity to comprehensively determine signs of refrigerant shortage, improving detection sensitivity. Then, it effectively eliminates confusion caused by reversing faults through dynamic pressure response testing of a four-way valve, ensuring accurate location. After determining the refrigerant shortage, it further constructs a refrigerant shortage index model incorporating a defrosting frequency correction factor. It utilizes the "slow-change" cumulative effect of frosting speed to compensate for the response lag of instantaneous thermodynamic parameters, achieving continuous quantitative assessment of the severity of the leak. Finally, it divides the control range into four levels based on the FI value, progressively advancing from mild warning load limiting, active frequency limiting refrigerant charging to emergency shutdown protection. This avoids abrupt shutdowns that affect the heating experience while providing a window for intelligent repair, comprehensively ensuring compressor safety and heating efficiency, and possessing high engineering practical value.

[0069] To more clearly illustrate the solution proposed in this application, a specific implementation method is provided below. like Figure 4 As shown, the air conditioner structure includes: compressor 01, liquid receiver 11, first flow valve 10, second flow valve 12, four-way valve 04, indoor heat exchanger 05, outdoor heat exchanger 07, throttling device 06, first ambient temperature sensor 13, second ambient temperature sensor 14, exhaust pressure sensor 03, exhaust temperature sensor 02, suction pressure sensor 09, and suction temperature sensor 08. For specific installation locations, please refer to [reference needed]. Figure 4 This will not be elaborated upon here.

[0070] This means that a refrigerant charging channel can be achieved without stopping the heating operation by adding a liquid storage tank on the suction side. The existing automatic refrigerant charging device is only suitable for cooling conditions; it cannot be used in heating mode because the refrigerant charging port is on the high-pressure side.

[0071] This application embodiment adds an automatic refrigerant charging device, with a liquid receiver added to the compressor suction side. The refrigerant flow is controlled by a flow valve switch, ensuring that the automatic refrigerant charging device is always connected to the low-pressure side of the compressor suction. During heating operation, the refrigerant charging port pressure remains at a low pressure, eliminating the need for forced switching to cooling mode or disconnection of wiring. Refrigerant can be automatically charged directly under stable heating conditions. Simultaneously, the refrigerant charge is corrected in real-time based on the heating outlet temperature, overall unit load, and operating power, completely resolving the pain points of distorted operating conditions and inaccurate refrigerant charge in traditional technologies. This achieves a hardware and software coordinated automatic refrigerant charging function for uninterrupted heating operation.

[0072] like Figure 5 As shown, the three-level correlation mapping model for refrigerant deficiency detection, which includes "operating condition-fault-control", is used. It pioneered a multi-parameter fusion detection model specifically for heating conditions, establishing a precise mapping relationship between parameters, faults, and control, completely replacing traditional refrigeration transplantation algorithms. ① Level 1: Adaptive Parameter Feature Extraction for Operating Conditions The quantitative correlation between refrigerant charge and core parameters under standard heating mode. Core characteristic parameters include: exhaust superheat, return superheat, system pressure ratio, four-way valve reversing pressure difference, and defrosting frequency correction factor. All of these are sensitive parameters specific to heating conditions.

[0073] Exhaust superheat is the core criterion for determining refrigerant shortage, reflecting abnormal heat exchange in the exhaust gas during air conditioning heating operation. The calculation formula is: Exhaust superheat = Compressor exhaust temperature - Condensing saturation temperature.

[0074] Return gas superheat: This item is an auxiliary criterion for determining the reduction in heating capacity. The calculation formula is: Return gas superheat = Compressor suction temperature - Evaporation saturation temperature; System pressure ratio: This item is the core auxiliary criterion for determining refrigerant shortage, reflecting the matching status of high and low pressure operation of the air conditioning system. The calculation formula is: system pressure ratio PR = high pressure side pressure / low pressure side pressure; Four-way valve reversing pressure difference: refers to the real-time pressure difference (ΔP_rev) between the high-pressure side and the low-pressure side of the air conditioning system.

[0075] Calculation formula: ΔP_rev = P_high (high pressure) - P_low (low pressure) Defrosting frequency correction factor: This parameter is only an environmental adaptive correction parameter, used to improve the accuracy of refrigerant shortage detection under complex operating conditions.

[0076] ② Level 2: Accurate identification of dual fault characteristics We constructed a refrigerant deficiency degradation feature vector (linked to increased pressure ratio, soaring exhaust superheat, and reduced heating capacity) and a four-way valve reversing fault feature vector (reversing lag and gas leakage failure without refrigerant influence). Through independent analysis of the two feature vectors, we achieved accurate separation of the two types of coupled faults.

[0077] The specific parameters for the reduction in heating capacity are determined by the following: Indoor air supply temperature rise attenuation: ΔT_air = Indoor air supply temperature - Indoor return air temperature. Under normal heating conditions, ΔT_air ≥ 8℃. If ΔT_air < ​​6℃ for 20 consecutive minutes and the compressor frequency does not decrease, the "Insufficient capacity" flag is triggered.

[0078] Compressor frequency and power mismatch: When the indoor temperature difference remains below the target value, the inverter controller will actively increase the frequency to try to make up for the heat. If the compressor frequency has increased to more than 90% of the rated value, but ΔT_air still remains below 5℃, it means that "the power has increased, but the heat has not been generated".

[0079] Simultaneous increase in intake superheat: In heating mode, the normal intake superheat is 0~3℃. If the intake superheat rises to above 5℃ (indicating insufficient liquid supply at the end of the evaporator), it forms a "double superheat linkage" with the surge in exhaust superheat.

[0080] If two or more of the above three situations occur, it is judged as a linkage of reduced heating capacity.

[0081] For the specific meaning of each parameter in the four-way valve reversing fault characteristic vector, please refer to Table 1: Table 1

[0082] ③ Level 3: Quantitative output control of fluoride deficiency index Construct a quantifiable fluoride deficiency index FI to achieve continuous and accurate determination of the degree of fluoride deficiency: FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base + β·(PR_act - PR_base) / PR_base + γ·k_df + δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm Where: SH_dish_act is the real-time exhaust superheat, PR_act is the real-time pressure ratio, τ_rev_act is the commutation response time, and k_df is the defrosting frequency correction factor. ,in t1: Standard frosting cycle under normal operating conditions of the air conditioner (60min under normal calibration); t1: Real-time actual frosting cycle of the equipment. Through multi-dimensional weighted calculation, the severity level of refrigerant deficiency is accurately quantified, and corresponding control commands are output. α, β, γ, and δ are weighting coefficients: corresponding to the weight ratio of the four diagnostic dimensions, which are determined through extensive operating condition experiments and machine learning optimization. The sum of the four coefficients is always 1, which is used to balance the influence weight of each parameter on the refrigerant deficiency judgment. The normal range of values ​​for the weighting coefficients is detailed in Table 2.

[0083] Table 2

[0084] Decoupling Mechanism of Four-Way Valve False Switching Diagnosis and Refrigerant Leakage To address the challenge of dual-fault coupling in heating mode, a unique shutdown pseudo-commutation diagnostic technology has been developed to achieve independent fault identification, such as... Figure 7 As shown: 1. The compressor is completely stopped, the power supply to the four-way valve coil is cut off, and the initial pressure on the low-pressure side is collected; 2. Apply a periodic pulse reversal signal to the four-way valve to detect the rate of pressure change on the low-pressure side; 3. Compare the four-way valve to the standard reversing reference curve to determine its mechanical health. 4. By combining the baseline of the four-way valve's reversing capability and eliminating mechanical fault interference, the heating capacity reduction caused by pure refrigerant leakage is accurately calculated.

[0085] This mechanism can accurately distinguish between two types of problems: "refrigerant shortage requiring refrigerant addition" and "four-way valve malfunction requiring repair," thus preventing blind refrigerant addition and ineffective repairs.

[0086] Fluorine deficiency classification detection algorithm based on defrosting feature correction, such as Figure 8 As shown: To address the challenge of detecting interference from heating frost, a quantitative correlation model between frost and refrigerant deficiency was established: The frosting rate and defrosting cycle are recorded using an outdoor heat exchanger coil temperature sensor and a defrosting timer. A frosting rate offset R is established, and the specific calculation formula is as follows. (V1 is the actual frosting speed, Vnormal is the normal frosting speed, t1 is the actual frosting period, and tnormal is the normal frosting period.) The normal frosting period is approximately 45-90 minutes. When refrigerant is low, the frosting period may be shortened to 10-15 minutes. For example, if tnormal = 60 minutes and t1 = 15 minutes... This means the current frosting speed is 3 times faster than normal. The transfer function coefficient γ (0.1≤γ≤0.3) between the offset and the degree of refrigerant deficiency is used to weight and correct the refrigerant deficiency index FI. This auxiliary mechanism incorporates the structural characteristics of normal air conditioning operation (defrosting) into the refrigerant deficiency detection system, effectively reducing the risk of misjudgment caused by relying on a single parameter in heating mode.

[0087] A four-tiered early warning and self-healing protection strategy specifically for heating systems. Breaking away from the traditional single shutdown logic, a four-level refined adaptive control system is established based on the Freon deficiency index (FI), balancing user experience and equipment safety. Figure 5 and 6 As shown: 1. Normal state (FI ≤ 0.3): Update the heating health baseline database and establish equipment operating condition files; 2. Slight refrigerant deficiency (0.3 < FI ≤ 0.6): Pop-up warning, slight power limitation, ensure heating supply, no shutdown; 3. Moderate refrigerant deficiency (0.6 < FI ≤ 0.8): Frequency limiting protection, automatic start of heating in-situ refrigerant charging program; 4. Severe refrigerant shortage (FI > 0.8): Emergency shutdown protection, fault code reporting, and retention of operation logs facilitate accurate maintenance.

[0088] The optimal implementation method is described in detail below from five major modules: hardware structure, detection algorithm, fault decoupling, hierarchical control, and automatic refrigerant charging.

[0089] 1. Hardware structure improvement plan The core hardware is an automatic refrigerant charging device, which has low modification costs and high versatility.

[0090] Automatic refrigerant charging device The system is equipped with a miniature built-in refrigerant tank (storing 20%-30% of the rated charge of refrigerant), a pulse-type refrigerant charging solenoid valve, a high-precision flow sensor, and a low-pressure sensor, all of which are electrically connected to the main control board.

[0091] The controller outputs instructions based on the refrigerant level, controlling the solenoid valve to open and close in pulses, and automatically drawing in refrigerant using the compressor's suction negative pressure; the flow sensor monitors the refrigerant charging rate and total amount in real time in a closed loop, accurately controlling the amount of refrigerant added to avoid overcharging or undercharging.

[0092] 2. Dedicated refrigerant shortage detection algorithm for heating system (1) Exhaust superheat deviation detection method During stable heating operation, the standard exhaust superheat SH_dish remains between 3-7℃. Under refrigerant shortage conditions, the exhaust temperature rises sharply, and the superheat is abnormally high.

[0093] Calculation formula: SH_dish = T_discharge - T_cond_sat Parameter description: T_discharge is the real-time exhaust temperature, and T_cond_sat is the condensation saturation temperature; Dynamic threshold correction: The threshold is adaptively adjusted according to the ambient temperature and compressor frequency, and the correction coefficient λ is used to eliminate misjudgment of low temperature and extreme cold conditions; if the parameter exceeds the standard for 10 minutes, a primary warning of refrigerant shortage is triggered.

[0094] (2) System pressure ratio diagnostic method Collect the high-pressure side (indoor heat exchanger outlet) pressure P_high and the low-pressure side pressure P_low in heating mode, and calculate the real-time pressure ratio: PR = P_high / P_low The PR-M (pressure ratio-refrigerant quantity) baseline curve is pre-calibrated under the standard charge quantity. When the real-time pressure ratio exceeds the baseline value by more than 15% and matches an abnormal trend in superheat, a refrigerant shortage fault is determined. The pressure ratio is highly sensitive to changes in refrigerant quantity, enabling accurate diagnosis of minor refrigerant shortages in the early to mid-stages.

[0095] (3) Diagnosis of false reversal fault in four-way valve Perform diagnostic procedures while the air conditioner is in standby or off state: ① Initialize the four-way valve to de-energize and collect the initial pressure on the low-pressure side; ② Output a commutation signal with a period of 200ms and a duty cycle of 50%; ③ Collect the rate of change of pressure on the low-pressure side and compare it with the factory reference curve; ④ If the pressure change rate meets the standard, the four-way valve is mechanically normal, and the heating reduction is entirely attributed to refrigerant deficiency; if the rate does not meet the standard, the four-way valve's switching capability is deteriorated, thus achieving complete decoupling of the two types of faults.

[0096] (4) Weighted correction for defrosting frequency Real-time monitoring of outdoor coil temperature and defrosting cycle, calculation of defrosting rate offset ΔT, and weighted correction of the fluorine deficiency index FI by a correction coefficient γ in the range of 0.1-0.3, thereby offsetting parameter interference under normal defrosting conditions and significantly improving the detection stability of low-temperature heating conditions.

[0097] 3. Four-level tiered hierarchical control strategy (1) Normal state (FI≤0.3): Continuously collect operating parameters under all operating conditions, update the heating health baseline database, and establish a dedicated operating condition model for the equipment.

[0098] (2) Slight refrigerant deficiency (0.3 < FI ≤ 0.6): Terminal pop-up window and APP push warning; compressor power limited to 90% of rated power to avoid high load damage to equipment; retain 15 minutes of pre-operation log to ensure heating without stopping the machine.

[0099] (3) Moderate refrigerant shortage (0.6 < FI ≤ 0.8): The compressor frequency is limited to 80% of the rated frequency; when the refrigerant tank has sufficient remaining refrigerant, the heating function is automatically started and refrigerant is added in place; the FI decreasing trend is monitored in real time during the refrigerant adding process until the parameters return to normal.

[0100] (4) Severe refrigerant shortage (FI>0.8): Immediately shut down the machine for protection, lock the compressor to high-frequency operation; display the exclusive fault code E-4F; retain all operating parameters for 3 minutes before and after the fault to provide data support for accurate after-sales maintenance.

[0101] 4. Precise automatic refrigerant charging control in heating mode After the system determines that there is a slight / moderate refrigerant shortage, it will default to starting the heating in-situ refrigerant charging mode. (1) No need to switch operating conditions, refrigerant can be directly added to the low-pressure side through the automatic refrigerant charging device; (2) A pulse-cycle refrigerant charging logic with a 3-second start-up and a 10-second stop-down is adopted to precisely control the amount of refrigerant added; (3) The maximum amount of refrigerant added is limited to 25% of the rated charge of the entire unit; (4) If the refrigerant level reaches the upper limit of 20% but the FI does not return to normal, it is determined that there is a serious leak in the system. Stop adding refrigerant and report the C4 refrigerant addition abnormality fault to prevent invalid addition and safety hazards.

[0102] The solution provided in this application integrates multiple parameters such as exhaust superheat, suction superheat, system pressure ratio, four-way valve reversing pressure difference, and defrosting frequency, combined with adaptive dynamic thresholds for operating conditions. Compared with traditional single-parameter detection, the accuracy is improved by more than 30%, effectively solving the problems of misjudgment and missed judgment in heating conditions. No additional hardware is required; a pseudo-reversing diagnostic mechanism separates four-way valve mechanical faults from refrigerant leakage faults, accurately identifying the root cause of poor heating performance, significantly reducing after-sales repair misjudgment costs and operation and maintenance costs. Automatic refrigerant charging during the heating phase significantly improves accuracy: by adding a liquid storage tank on the suction side, automatic refrigerant charging during heating operation is achieved without switching cooling modes. The refrigerant charging amount is calculated based on actual heating operating parameters, improving charging accuracy by 30%, with extremely simple operation and strong adaptability. Four-level differentiated early warning control ensures heating without interruption for minor refrigerant shortages, and promptly shuts down the machine to protect it from severe refrigerant shortages, balancing the user's winter heating experience with the safety of the compressor equipment. By quantifying the frost interference weight through a defrosting frequency correction factor, the influence of normal heating frost on refrigerant deficiency detection is effectively eliminated, significantly improving the algorithm's accuracy and adapting to low temperature, high humidity, and variable outdoor conditions.

[0103] This application provides an air conditioner refrigerant shortage detection device, applied in the air conditioner's heating mode. It is understood that existing technologies are used in cooling mode or other modes. Figure 9 As shown, the air conditioner refrigerant shortage detection device 90 provided in this embodiment includes: The target parameter acquisition module 91 is used to acquire a first target parameter, which includes at least one of exhaust superheat, real-time pressure ratio and heating capacity. Wherein, exhaust superheat = real-time exhaust temperature - condensation saturation temperature.

[0104] Pressure ratio = High-pressure side pressure / Low-pressure side pressure. Wherein, the high-pressure side is the outlet of the indoor heat exchanger; the low-pressure side is the compressor suction port or the outlet of the gas-liquid separator (i.e., the position before the low-pressure steam after evaporation in the outdoor heat exchanger enters the compressor).

[0105] Heating capacity can be calculated using the difference between the indoor supply air temperature and the indoor return air temperature.

[0106] The fluorine deficiency phenomenon determination module 92 is used to determine whether a fluorine deficiency phenomenon has occurred based on the first target parameter; The step of determining whether a fluoride deficiency has occurred based on the first target parameter includes: A fluoride deficiency is determined to occur when any of the following conditions are met: The difference between the real-time exhaust superheat and the baseline exhaust superheat is greater than the preset exhaust superheat difference. When refrigerant is insufficient, the refrigerant flow rate entering the evaporator (outdoor unit) is significantly reduced, resulting in a sharp drop in evaporation pressure and temperature, and a sharp increase in compressor suction superheat. At the same time, due to insufficient circulating refrigerant mass flow rate, there is less liquid refrigerant in the condenser (indoor unit), and the proportion of high-temperature superheated gas discharged increases, making the measured exhaust temperature much higher than the saturation temperature at that pressure, thus the exhaust superheat seriously exceeds the normal baseline value.

[0107] The difference between the real-time pressure ratio and the reference pressure ratio is greater than the preset pressure ratio difference. When refrigerant is insufficient, the pressure drop on the low-pressure side (compressor suction port) is particularly significant due to insufficient liquid supply from the evaporator. While the pressure on the high-pressure side also drops, the magnitude is much smaller than that on the low-pressure side, causing the overall pressure ratio to deviate significantly from the normal operating range (usually manifested as an abnormally high pressure ratio). This deviation directly reflects the greater compression power consumption required by the compressor to maintain heating, and is a direct manifestation of the imbalance in the system's cycle driving force.

[0108] Reduced heating capacity. Refrigerant is the carrier of heat; a decrease in its mass directly leads to a simultaneous decrease in the amount of heat absorbed from the outside and released into the room per unit time. Specifically, assuming the compressor frequency remains constant, the temperature difference between the inlet and outlet of the indoor heat exchanger (condenser) narrows, the outlet air temperature decreases, and the system fails to achieve the target heating effect. This criterion, from the final output result, verifies the deterioration of heat exchange capacity caused by insufficient refrigerant.

[0109] In a preferred implementation of this application, the reduction in heating capacity is determined when at least two of the following conditions occur: Without reducing the compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature for a continuously preset duration is less than the first preset temperature difference; the heating capacity is directly reflected in the temperature difference between the indoor unit's outlet and return air. Theoretically, with the compressor frequency (i.e., speed) remaining constant, the refrigerant circulation volume should be constant, and the heating capacity should be relatively stable. If the temperature difference remains consistently lower than the normal baseline, it indicates that the system's heat exchange output has significantly decreased under the same input power, ruling out factors causing a reduction in normal capacity due to frequency reduction control, and directly pointing to insufficient refrigerant leading to a decrease in effective heat exchange capacity.

[0110] When the compressor frequency is greater than or equal to the preset compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature remains less than the second preset temperature difference, which is less than the first preset temperature difference. When the compressor operating frequency reaches a high level, it indicates that the indoor and outdoor temperature difference is large or the user-set temperature is high, and the system is outputting heating at full capacity. In this high-load scenario, if the outlet and return air temperature difference does not even reach the lower second preset temperature difference, it indicates that the system is severely lacking in refrigerant to support the circulation flow required for high-frequency operation. At this time, the degree of heating attenuation is more significant than in normal operating conditions. Sensitive detection can be achieved by setting a smaller threshold separately.

[0111] The difference between the suction superheat and the reference suction superheat is greater than the preset suction superheat difference. Suction superheat = suction temperature - suction pressure corresponding to saturation temperature. Insufficient refrigerant leads to inadequate refrigerant supply to the outdoor evaporator, causing the liquid refrigerant to vaporize completely at the front end of the evaporator tubes. Subsequent tube sections cannot effectively absorb heat, resulting in a sharp increase in suction temperature, and the measured superheat far exceeds the normal reference.

[0112] The reversing fault determination module 93 is used to execute the four-way valve fault judgment process when it is determined that a refrigerant shortage has occurred, so as to determine whether the four-way valve is faulty. As a preferred implementation of the embodiments of this application, such as Figure 3 As shown, the four-way valve fault diagnosis process includes: When the compressor stops, the power supply to the four-way valve coil is cut off and the initial pressure on the low-pressure side is obtained; wherein, the compressor stops immediately. Alternatively, the compressor can stop when the system is running normally (such as stopping when the temperature is reached). The specific setting can be set according to actual needs, and this application embodiment does not limit it. A periodic pulse switching signal is applied to the four-way valve, and the rate of pressure change on the low-pressure side is detected; When the rate of change on the low-pressure side is greater than or equal to a preset rate of change, the four-way valve is determined to be functioning correctly; when the rate of change on the low-pressure side is less than the preset rate of change, the four-way valve is determined to be functioning correctly.

[0113] When the compressor stops, the high and low pressure sides of the system tend to balance. Cutting off the power supply to the four-way valve coil resets the main slide valve to its initial position, and the initial pressure on the low-pressure side is recorded as a reference. Subsequently, a periodic pulse reversing signal is applied, energizing the electromagnetic pilot valve and guiding high-pressure gas through the capillary tube to move the main slide valve. If the four-way valve is mechanically flexible (no fault): the main slide valve quickly completes the reversing under pulse drive, the high and low pressure passages inside the system are redistributed, and high-pressure refrigerant instantaneously enters the originally closed low-pressure side cavity, causing a rapid jump in the low-pressure side pressure (rate of change ≥ preset value). If the four-way valve is mechanically stuck (fault): the main slide valve cannot move due to burrs, deformation, or oil adhesion, the internal flow channel remains unchanged, there is no switching between high and low pressure sides, and the low-pressure side pressure changes slowly or remains basically unchanged due to a small leak (rate of change < preset value). This method, under the safe condition of the compressor being stationary, utilizes the dynamic pressure response rate at the moment of reversing to accurately distinguish between the mechanically stuck and normal state of the four-way valve, effectively eliminating the interference of valve faults on refrigerant shortage detection.

[0114] Based on the same inventive concept, this application may also use any one of the following to determine whether the four-way valve is faulty: response delay time (i.e., the time from when the coil is energized to when the valve core is in place, specifically the time from when the coil is energized to when the low-pressure side pressure reaches an inflection point), static differential pressure holding capability (i.e., after the commutation is completed, the coil is kept de-energized and the drop in low-pressure side pressure is observed within a preset time, which is used to characterize the piston sealing after the valve core is in place), or valve body pipe temperature difference (i.e., the temperature difference between the D pipe connected to the indoor unit and the S pipe connected to the compressor suction pipe, which is used to characterize the degree of internal air leakage).

[0115] The air conditioner refrigerant shortage detection module 94 is used to determine that the air conditioner is low on refrigerant when the four-way valve is determined to be not faulty.

[0116] It should be noted that when determining a four-way valve malfunction, there are two scenarios: one is that the air conditioner is not low on refrigerant, meaning the refrigerant shortage is entirely caused by the four-way valve malfunction; the other is that the air conditioner is simultaneously low on refrigerant, meaning the refrigerant shortage is caused by both the four-way valve malfunction and the refrigerant shortage. In this case, the four-way valve malfunction must be resolved first to ensure its normal operation. Then, based on the first target parameter, it should be determined whether a refrigerant shortage still exists. If a refrigerant shortage still exists, it can be directly determined that the air conditioner is low on refrigerant, or the determination can be made according to the solution described in this application.

[0117] The second target parameter acquisition module is used to acquire second target parameters after determining that there is a refrigerant shortage. The second target parameters include real-time exhaust superheat, real-time pressure ratio, reversing response time (and defrosting frequency correction factor). The fluoride deficiency index calculation module is used to calculate the current fluoride deficiency index FI based on the second target parameter; and to determine the severity of fluoride deficiency based on the fluoride deficiency index, wherein the larger the fluoride deficiency index, the more severe the fluoride deficiency. In one embodiment, FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base +δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and α, β, and δ are preset weighting coefficients, the sum of which is 1; In another embodiment, FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base + γ·k_df + δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and k_df is the defrosting frequency correction factor. , t1 is the standard frosting cycle under normal operating conditions of the air conditioner; t1 is the real-time actual frosting cycle; α, β, γ, and δ are preset weighting coefficients, and the sum of the four is 1.

[0118] In other words, this embodiment introduces a defrosting frequency correction factor based on the above embodiment. The core reason for introducing the defrosting frequency correction factor is that, in heating mode, the frosting speed of the outdoor heat exchanger is a "sensitive indicator" reflecting the refrigerant circulation volume of the system, while traditional thermodynamic parameters (exhaust superheat, pressure ratio) have response lag or signal distortion under frosting conditions.

[0119] Specifically, when an air conditioner is heating, the outdoor unit acts as the evaporator. Insufficient refrigerant leads to significantly lower evaporation pressure and temperature, causing a sharp increase in the temperature difference between the outdoor coil surface and the air, thus accelerating condensation and frosting. In other words, the more severe the refrigerant deficiency, the shorter the actual frosting cycle (t1), and the more significant the deviation compared to the normal cycle (tnormal), resulting in a positive increase in k_df. Exhaust superheat and pressure ratio are easily affected by fluctuations in ambient temperature and compressor frequency, causing instantaneous changes; these are considered "rapidly changing" parameters. The change in frosting speed reflects the cumulative damage to the evaporator's heat exchange capacity caused by refrigerant deficiency. Introducing k_df is equivalent to adding a "slowly changing" inertial correction dimension, making the refrigerant deficiency index (FI) smoother and more stable under dynamic operating conditions. Especially in the early stages of refrigerant deficiency, the deviation in exhaust superheat or pressure ratio may not yet reach a significant threshold, but the drop in evaporation temperature is sufficient to shorten the frosting cycle. k_df can capture this early sign, significantly improving detection sensitivity and avoiding missed diagnoses.

[0120] The preset interval determination module is used to determine the target preset interval to which the fluoride deficiency index belongs after obtaining the fluoride deficiency index, and each preset interval corresponds to a control strategy. Determining the target preset range to which the fluoride deficiency index belongs includes: When the refrigerant deficiency index exceeds a first threshold, it is determined to fall within a first preset range. The control strategy corresponding to the first preset range is: shutdown protection and fault code reporting. When the refrigerant deficiency index exceeds the first threshold, it indicates that the system is in a severe refrigerant deficiency state, the highest risk level. At this time, the refrigerant flow into the compressor is extremely scarce, failing to effectively cool the motor windings and remove compression heat, leading to a sharp rise in exhaust temperature. This easily causes the refrigeration oil to carbonize at high temperatures, lose its lubricating properties, and subsequently cause irreversible damage such as compressor seizure or coil burnout. Simultaneously, the system's circulating pressure ratio is severely imbalanced, and heating output is almost ineffective. Continuing to operate is neither meaningful for heating nor does it significantly waste electrical energy. Taking the "shutdown protection and fault code reporting" approach is the last resort hard safety intervention measure, aiming to physically cut off the source of danger, remind users to report repairs in a timely manner by clearly locating the fault code, and at the same time avoid secondary damage caused by repeated start-ups and shutdowns of the system under extreme operating conditions.

[0121] When the refrigerant deficiency index is greater than the second threshold and less than or equal to the first threshold, it is determined to be in the second preset range. The control strategy corresponding to the second preset range is: frequency limiting protection and automatic refrigerant charging. When the refrigerant deficiency index is in the second preset range, it indicates that the system is in a moderately severe refrigerant deficiency state - the refrigerant is obviously insufficient, which leads to an increase in compressor discharge temperature, an increase in pressure ratio, and a deterioration in lubrication conditions. However, the system has not yet entered an extremely dangerous operating condition and still has a certain heating output capacity and operating margin.

[0122] At this point, a strategy of "frequency limiting protection and automatic refrigerant charging" is adopted, with the following logic: Frequency limiting protection is necessary because the compressor frequency directly determines the refrigerant circulation volume and suction specific volume. Reduced frequency operation simultaneously lowers the compressor's discharge temperature and pressure ratio, alleviating mechanical load and thermal stress, and effectively curbing the risk of high-temperature carbonization of the refrigeration oil. Simultaneously, under conditions of insufficient refrigerant supply, reduced frequency raises the evaporation temperature, slowing down the abnormal frosting rate of the outdoor heat exchanger and maintaining the system in a relatively safe "sub-healthy" state for continuous heating, avoiding unnecessary shutdowns that could cause users to completely lose their heating experience. Furthermore, automatic refrigerant charging requires adding liquid refrigerant to the system. If the compressor is operating at high frequency and high load, and the suction pressure is too low, the added refrigerant may not be smoothly drawn into the compression chamber, potentially even causing liquid slugging. After frequency limiting, the system pressure ratio narrows, and the suction superheat decreases, making it easier for the added refrigerant to participate in normal circulation and distribute evenly, ensuring the effectiveness and safety of the refrigerant charging process. Additionally, the second preset interval is a window period for "active intervention and recovery." Compared to the forced shutdown in the first preset range, this approach combines frequency limiting and load reduction with active refrigerant replenishment. This avoids the impact of abrupt shutdown on user operation while allowing the system to return to normal operating conditions through refrigerant replenishment, striking a balance between safety and comfort. If the refrigerant frequency (FI) continues to drop after frequency limiting and refrigerant replenishment, the system can gradually resume high-frequency operation; if the FI continues to climb to the first threshold, it will be upgraded to shutdown protection.

[0123] When the refrigerant deficiency index is greater than the third threshold and less than or equal to the second threshold, it is determined to belong to the third preset interval. The control strategy corresponding to the third preset interval is: pop-up warning and system power limitation. When the refrigerant deficiency index is in the third preset interval, it indicates that the system is in the early warning stage of slight refrigerant deficiency—the refrigerant circulation volume is somewhat lacking, but the degree is still mild. The compressor's exhaust temperature, pressure ratio, and lubrication conditions have not yet reached a dangerous critical state, and the system still basically has effective heating output capacity, with the performance degradation within an acceptable range. Although slight refrigerant deficiency does not pose an immediate safety threat, if left untreated, the leak will continue to worsen, eventually evolving into moderate to severe refrigerant deficiency. Therefore, by pushing a "Refrigerant insufficient, maintenance recommended" pop-up window to the user on the air conditioner display panel or mobile app, the user can be informed of the current operating status and prompted to contact after-sales service to replenish refrigerant at an appropriate time, avoiding more serious damage after the fault worsens. Furthermore, this section does not employ harsh measures such as shutdown or significant frequency limiting. Instead, it only moderately restricts system power (e.g., slightly reducing the upper limit of compressor operating frequency or adjusting the electronic expansion valve opening). The aim is to moderately reduce the system's cyclic load, allowing the discharge temperature, pressure ratio, and suction superheat to drop slightly. This prevents the leakage process from being accelerated by continuous high-frequency operation and also provides more sufficient heat absorption time for the refrigerant in the evaporator, delaying the abnormal frosting trend of the outdoor heat exchanger. Compared to the "frequency limiting + automatic refrigerant charging" in the second section, the power restriction here is more moderate and does not involve active refrigerant replenishment. This is because adding refrigerant is not urgently necessary at this point, and early leak points may not have been eliminated yet. Blindly adding refrigerant would only waste resources and pose environmental risks.

[0124] When the refrigerant deficiency index is less than or equal to the third threshold, it is determined to belong to the fourth preset interval. The control strategy corresponding to the fourth preset interval is to maintain the current operating state. When the refrigerant deficiency index is less than or equal to the third threshold, it indicates that the system is in a normal operating state with sufficient refrigerant or only a very slight deviation—the current exhaust superheat, pressure ratio, heating capacity, and other core parameters are all within the preset normal fluctuation range, the compressor's operating load, exhaust temperature, and lubrication conditions have no abnormal risks, and the system's various performance indicators can meet the user's heating needs, requiring no intervention. Generally, the refrigerant deficiency index (FI) will not fall within the fourth preset interval when a refrigerant deficiency is determined. If it does, it will be recalculated.

[0125] An air conditioning control module is used to control the air conditioner based on a target control strategy corresponding to the target preset range.

[0126] The air conditioner refrigerant shortage detection device provided in this application addresses the challenge of refrigerant leakage detection in heating mode by proposing an integrated solution that combines multi-parameter fusion judgment, four-way valve fault diagnosis, refrigerant shortage index quantification, and graded intelligent response. By introducing multi-dimensional features such as exhaust superheat, real-time pressure ratio, and heating capacity attenuation as joint criteria, it effectively avoids misjudgments and failures in traditional single-parameter detection under heating conditions. The addition of a four-way valve fault judgment process resolves the issue of feature confusion between refrigerant shortage and reversing faults, significantly improving diagnostic accuracy. Furthermore, a refrigerant shortage index model is constructed, encompassing exhaust superheat deviation, pressure ratio deviation, reversing response time, and defrosting frequency correction factors, enabling precise quantification of the severity of refrigerant shortage. Based on this, multi-level control strategies are implemented, ranging from minor warnings and frequency limiting protection to graded shutdown reporting responses. This avoids abrupt shutdowns that impact user experience and provides a decision-making basis for intelligent refrigerant charging and adaptive operation, comprehensively improving the operational reliability, energy efficiency, and compressor lifespan guarantee level of the air conditioner in heating mode.

[0127] Based on the same inventive concept, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the air conditioner refrigerant shortage detection method provided in any of the above embodiments.

[0128] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0129] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0130] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0131] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0132] The computer-readable storage medium provided in this application embodiment stores a computer program, which, when executed by a processor, implements the steps of the air conditioner refrigerant shortage detection method provided in any of the above embodiments. Addressing the challenge of refrigerant leakage detection in heating mode, an integrated solution is proposed, encompassing multi-parameter fusion judgment, four-way valve fault troubleshooting, refrigerant shortage index quantification, and graded intelligent response. By introducing multi-dimensional features such as exhaust superheat, real-time pressure ratio, and heating capacity attenuation as joint criteria, the misjudgment and failure of traditional single-parameter detection under heating conditions are effectively avoided. The addition of a four-way valve fault judgment process resolves the issue of feature confusion between refrigerant shortage and reversing faults, significantly improving diagnostic accuracy. Furthermore, a refrigerant shortage index model is constructed, encompassing exhaust superheat deviation, pressure ratio deviation, reversing response time, and defrosting frequency correction factors, achieving precise quantification of the severity of refrigerant shortage. Based on this, multi-level control strategies are implemented, ranging from minor warnings and frequency limiting protection to graded shutdown reporting responses. This avoids abrupt shutdowns that impact user experience and provides a decision-making basis for intelligent refrigerant charging and adaptive operation, comprehensively improving the operational reliability, energy efficiency, and compressor lifespan guarantee level of the air conditioner in heating mode.

[0133] Based on the same inventive concept, such as Figure 10 As shown, this application also provides an air conditioner refrigerant shortage detection system 100, comprising: At least one processor 101 and at least one memory 102; The memory stores the executable instructions of the processor; The processor is configured to execute the air conditioner refrigerant shortage detection method provided in the above embodiments.

[0134] The air conditioner refrigerant shortage detection system provided in this application stores the processor's executable instructions in a memory. When these instructions are executed, the processor, through the collaborative logic of multi-physical quantity coupling criteria and four-way valve status self-check, completely solves the inherent problem of confusion between refrigerant shortage and reversing faults in traditional solutions. Furthermore, it constructs a dynamic refrigerant shortage index model that includes defrosting frequency correction, enabling continuous quantitative assessment of the leakage degree and formulating differentiated intelligent response strategies—from mild warnings and frequency limiting compensation to shutdown protection—avoiding harsh interventions that affect user experience while providing a basis for accurate refrigerant charging. Simultaneously, it optimizes the four-way valve dynamic detection process and heating attenuation criteria, giving the entire system adaptive diagnostic capabilities. This significantly improves the safety, energy efficiency ratio, and compressor durability during winter heating operation, providing reliable technical support for fault prediction and health management of intelligent air conditioners.

[0135] Based on the same inventive concept, this application provides an air conditioner including the air conditioner refrigerant detection system provided in the above embodiments.

[0136] The air conditioner provided in this application embodiment, by incorporating the refrigerant shortage detection system provided in the above embodiment, can comprehensively determine the problem by integrating multi-dimensional parameters such as exhaust superheat, real-time pressure ratio, and heating capacity, effectively improving detection sensitivity and accuracy. It also adds a four-way valve fault troubleshooting process, completely avoiding the confusion between commutation abnormalities and refrigerant shortage symptoms. Furthermore, it constructs a refrigerant shortage index model including commutation response time and defrosting frequency correction factors to quantify the severity, and provides a graded control strategy (early warning, frequency limiting, shutdown) for intelligent response. Simultaneously, it optimizes the four-way valve dynamic detection and heating capacity attenuation criteria, comprehensively ensuring compressor safety, improving heating efficiency and user comfort, and possessing high reliability and practical application value.

[0137] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0138] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means at least two.

[0139] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for detecting refrigerant deficiency in air conditioners, characterized in that, Applied to air conditioning heating modes, including: Obtain a first target parameter, which includes at least one of exhaust superheat, real-time pressure ratio, and heating capacity; Determine whether a fluoride deficiency has occurred based on the first target parameter; When a refrigerant shortage is detected, the four-way valve fault diagnosis procedure is executed to determine whether the four-way valve is faulty. If the four-way valve is determined to be normal, then the air conditioner is found to be low on refrigerant.

2. The method according to claim 1, characterized in that, Also includes: After determining the refrigerant shortage, the second target parameters are obtained, including real-time exhaust superheat, real-time pressure ratio, and reversing response time. The current fluorine deficiency index FI is calculated based on the second target parameter: FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base +β·(PR_act - PR_base) / PR_base +δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and α, β, and δ are preset weighting coefficients, the sum of which is 1. The severity of fluoride deficiency is determined based on the fluoride deficiency index, where a higher fluoride deficiency index indicates a more severe fluoride deficiency.

3. The method according to claim 1, characterized in that, Also includes: After determining the refrigerant shortage, the second target parameters are obtained, including real-time exhaust superheat, real-time pressure ratio, commutation response time, and defrosting frequency correction factor. The current refrigerant deficiency index FI is calculated based on the second target parameter: FI = α·(SH_dish_act - SH_dish_base) / SH_dish_base + β·(PR_act - PR_base) / PR_base + γ·k_df + δ·(τ_rev_act - τ_rev_norm) / τ_rev_norm; where SH_dish_act is the real-time exhaust superheat, SH_dish_base is the preset baseline exhaust superheat, PR_act is the real-time pressure ratio, PR_base is the preset baseline pressure ratio, τ_rev_act is the four-way valve switching response time, τ_rev_norm is the preset normal four-way valve switching time, and k_df is the defrosting frequency correction factor. , t1 is the standard frosting cycle under normal operating conditions of the air conditioner; t1 is the real-time actual frosting cycle; α, β, γ, and δ are preset weighting coefficients, and the sum of the four is 1. The severity of fluoride deficiency is determined based on the fluoride deficiency index, where a higher fluoride deficiency index indicates a more severe fluoride deficiency.

4. The method according to claim 2 or 3, characterized in that, Also includes: After obtaining the fluoride deficiency index, a target preset range to which the fluoride deficiency index belongs is determined, and each preset range corresponds to a control strategy. The air conditioner is controlled based on the target control strategy corresponding to the target preset range.

5. The method according to claim 4, characterized in that: Determining the target preset range to which the fluoride deficiency index belongs includes: When the fluoride deficiency index is greater than the first threshold, it is determined that it belongs to the first preset range. The control strategy corresponding to the first preset range is: shutdown protection and reporting a fault code. When the fluoride deficiency index is greater than the second threshold and less than or equal to the first threshold, it is determined that it belongs to the second preset interval. The control strategy corresponding to the second preset interval is: frequency limiting protection and automatic fluoride addition. When the fluoride deficiency index is greater than the third threshold and less than or equal to the second threshold, it is determined that it belongs to the third preset interval. The control strategy corresponding to the third preset interval is: pop-up warning and limiting system power. When the fluoride deficiency index is less than or equal to the third threshold, it is determined that it belongs to the fourth preset interval. The control strategy corresponding to the fourth preset interval is to maintain the current operating state unchanged.

6. The method according to claim 1, characterized in that: The four-way valve fault diagnosis process includes: When the compressor stops, the power supply to the four-way valve coil is cut off and the initial pressure on the low-pressure side is obtained; A periodic pulse switching signal is applied to the four-way valve, and the rate of pressure change on the low-pressure side is detected; When the rate of change on the low-pressure side is greater than or equal to a preset rate of change, the four-way valve is determined to be functioning correctly; when the rate of change on the low-pressure side is less than the preset rate of change, the four-way valve is determined to be functioning correctly.

7. The method according to claim 1, characterized in that: The step of determining whether a fluoride deficiency has occurred based on the first target parameter includes: A fluoride deficiency is determined to occur when any of the following conditions are met: The difference between the real-time exhaust superheat and the reference exhaust superheat is greater than the preset exhaust superheat difference. The difference between the real-time pressure ratio and the reference pressure ratio is greater than the preset pressure ratio difference. The heating capacity has decreased; The reduction in heating capacity is determined when at least two of the following conditions occur: Without reducing the compressor frequency, the difference between the indoor outlet air temperature and the indoor return air temperature for a continuously preset duration is less than the first preset temperature difference. When the compressor frequency is greater than or equal to the preset compressor frequency, the difference between the indoor air outlet temperature and the indoor return air temperature is always less than the second preset temperature difference, wherein the second preset temperature difference is less than the first preset temperature difference. The difference between the intake superheat and the reference intake superheat is greater than the preset intake superheat difference.

8. An air conditioner refrigerant shortage detection device, characterized in that, Applied to air conditioning heating modes, including: The target parameter acquisition module is used to acquire a first target parameter, which includes at least one of exhaust superheat, real-time pressure ratio and heating capacity. The fluoride deficiency determination module is used to determine whether a fluoride deficiency has occurred based on the first target parameter. The reversing fault determination module is used to execute the four-way valve fault judgment process when a refrigerant shortage is detected, so as to determine whether the four-way valve is faulty. The air conditioner refrigerant shortage detection module is used to determine that the air conditioner is low on refrigerant when the four-way valve is determined to be functioning correctly.

9. An air conditioner refrigerant shortage detection system, characterized in that, include: At least one processor and at least one memory; The memory stores the executable instructions of the processor; The processor is configured to perform the method according to any one of claims 1-7.

10. An air conditioner, characterized in that, Includes the air conditioner refrigerant shortage detection system as described in claim 9.

Images