An air-fuel ratio control method, system, device, and medium

Abstract

The application discloses an air-fuel ratio control method, system, device and medium, and relates to the technical field of data processing.The application comprises the following steps: acquiring a front oxygen sensor and a rear oxygen sensor, acquiring two historical monitoring periods, acquiring a front oxygen ion concentration voltage sequence according to the front oxygen sensor, and acquiring a rear oxygen ion concentration voltage sequence according to the rear oxygen sensor; acquiring a front oxygen stability index, judging whether the front oxygen stability index is lower than a first preset threshold value, if lower, acquiring a rear oxygen steady state interval based on the front oxygen stability index, and acquiring a rear oxygen stability index; judging whether the rear oxygen stability index is higher than a second preset threshold value, if higher, collecting a current front oxygen ion concentration voltage value and a current rear oxygen ion concentration voltage value at a current time based on the front oxygen sensor and the rear oxygen sensor, and acquiring a current air-fuel ratio; and acquiring an injection nozzle control compensation ratio according to the current air-fuel ratio and a standard air-fuel ratio.The application has the advantages of stable and reliable control, dynamic self-adaptation and good data processing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data processing, in particular to a method, system, device and medium for air-fuel ratio control. BACKGROUND

[0002] In the field of air-fuel ratio control of internal combustion engines, the existing method relies on the real-time voltage signals of the front oxygen sensor (installed between the exhaust manifold and the three-way catalyst) and the rear oxygen sensor (installed after the three-way catalyst) for closed-loop adjustment of the air-fuel ratio.

[0003] However, the existing air-fuel ratio control method has the following defects: the front oxygen sensor responds quickly, but when the engine operating condition changes suddenly (such as sudden acceleration / deceleration), the exhaust gas flow disturbance causes its voltage signal to fluctuate dramatically, producing high-frequency noise, and the rear oxygen sensor is more stable due to the filtering effect of the three-way catalyst, but its response lag is significant, and the single sampling value of both under dynamic conditions is prone to distortion, which will cause miscompensation of the fuel injection amount if directly used for air-fuel ratio calculation, resulting in over-rich or over-lean mixture. Further, the steady-state reference voltage interval of the rear oxygen sensor is usually fixed based on bench calibration, and in actual operation, due to changes in engine stability, if the fixed interval is continued to be used, it will lead to misjudgment of the rear oxygen signal (such as normal voltage being identified as abnormal), and further trigger the air-fuel ratio correction. Further, the single-cycle data has weak anti-interference ability, and the existing method relies mainly on the sensor data at the current time or a single monitoring period, when an abnormal voltage spike occurs due to occasional electromagnetic interference, exhaust pulsation or sensor transient failure, it may be misjudged as a real air-fuel ratio deviation, which will trigger oscillatory adjustment of the fuel injection pulse width, damaging the combustion stability and increasing emissions. SUMMARY

[0004] In view of the technical problems described in the background, the present application provides a method, system, device and medium for air-fuel ratio control.

[0005] The air-fuel ratio control method comprises: obtaining a front oxygen sensor arranged between an exhaust manifold and a three-way catalyst and a rear oxygen sensor arranged between the three-way catalyst and an exhaust pipe; obtaining a current monitoring period in which a current time point is located; obtaining two historical monitoring periods before the current monitoring period; obtaining a front oxygen ion concentration voltage sequence of the front oxygen sensor in the two historical monitoring periods; obtaining a rear oxygen ion concentration voltage sequence of the rear oxygen sensor in the two historical monitoring periods; obtaining a front oxygen stability index according to the two front oxygen ion concentration voltage sequences; determining whether the front oxygen stability index is lower than a first preset threshold; if so, obtaining a rear oxygen steady state interval based on the front oxygen stability index; obtaining a rear oxygen stability index according to a proportion of the rear oxygen ion concentration voltage sequence in the rear oxygen steady state interval; determining whether the rear oxygen stability index is higher than a second preset threshold; if so, obtaining a current front oxygen ion concentration voltage value and a current rear oxygen ion concentration voltage value of the front oxygen sensor and the rear oxygen sensor at the current time point; obtaining a current air-fuel ratio according to the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value; obtaining a standard air-fuel ratio; and obtaining a fuel nozzle control compensation ratio according to the current air-fuel ratio and the standard air-fuel ratio.

[0006] Optionally, obtaining the rear oxygen steady state interval based on the front oxygen stability index comprises: obtaining an adjustment ratio according to the front oxygen stability index and the first preset threshold; obtaining a standard steady state interval; and obtaining the rear oxygen steady state interval by reducing the standard steady state interval according to the adjustment ratio.

[0007] Optionally, obtaining the current air-fuel ratio according to the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value comprises: obtaining a mapping relationship between the front oxygen ion concentration voltage and the air-fuel ratio; obtaining an initial air-fuel ratio according to the current front oxygen ion concentration voltage value and the mapping relationship; obtaining a correction value according to the current rear oxygen ion concentration voltage value and the standard steady state interval; and obtaining the current air-fuel ratio according to the correction value and the initial air-fuel ratio.

[0008] Optionally, obtaining the fuel nozzle control compensation ratio according to the current air-fuel ratio and the standard air-fuel ratio comprises: determining an adjustment coefficient based on a deviation degree of the current air-fuel ratio and the standard air-fuel ratio, wherein the adjustment coefficient is used to scale a basic fuel injection pulse width; generating a positive adjustment coefficient to increase the fuel injection amount when the current air-fuel ratio is greater than the standard air-fuel ratio; and generating a negative adjustment coefficient to reduce the fuel injection amount when the current air-fuel ratio is less than the standard air-fuel ratio.

[0009] Optionally, obtaining the front oxygen stability index according to the two front oxygen ion concentration voltage sequences is represented as: , ; wherein, is the front oxygen stability index, is a first weight coefficient, is a second weight coefficient. the number of data acquisition nodes in the monitoring period, the pre-oxygen ion concentration voltage value corresponding to the i+1th data acquisition node in the previous historical monitoring period, the pre-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the previous historical monitoring period, the pre-oxygen ion concentration voltage value corresponding to the i+1th data acquisition node in the next historical monitoring period, the pre-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the next historical monitoring period.

[0010] Optionally, the post-oxygen stability index is represented as:

[0011] ; wherein, the post-oxygen stability index, the number of data acquisition nodes in the monitoring period, the ith first intermediate coefficient, the post-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the previous historical monitoring period, the minimum value of the post-oxygen steady state interval, the maximum value of the post-oxygen steady state interval, the ith second intermediate coefficient, the post-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the next historical monitoring period.

[0012] ​​Also provided is an air-fuel ratio control system, comprising: an acquisition module, configured to acquire a front oxygen sensor arranged between an exhaust manifold and a three-way catalyst and a rear oxygen sensor arranged between the three-way catalyst and an exhaust pipe, acquire a current monitoring period in which a current time point is located, acquire two monitoring periods before the current monitoring period as two historical monitoring periods, acquire a front oxygen ion concentration voltage sequence in the two historical monitoring periods according to the front oxygen sensor, and acquire a rear oxygen ion concentration voltage sequence in the two historical monitoring periods according to the rear oxygen sensor; a first data processing module, configured to acquire a front oxygen stability index according to the two front oxygen ion concentration voltage sequences, judge whether the front oxygen stability index is lower than a first preset threshold, if so, acquire a rear oxygen steady state interval based on the front oxygen stability index, and acquire a rear oxygen stability index according to a proportion of the two rear oxygen ion concentration voltage sequences in the rear oxygen steady state interval; a second data processing module, configured to judge whether the rear oxygen stability index is lower than a second preset threshold, if so, acquire a current front oxygen ion concentration voltage value and a current rear oxygen ion concentration voltage value at the current time point based on the front oxygen sensor and the rear oxygen sensor, and acquire a current air-fuel ratio according to the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value; and a control module, configured to acquire a standard air-fuel ratio, acquire a fuel injector control compensation ratio according to the current air-fuel ratio and the standard air-fuel ratio.

[0013] Optionally, the first data processing module is further configured to: acquire an adjustment ratio according to the front oxygen stability index and the first preset threshold; acquire a standard steady state interval, and narrow the standard steady state interval according to the adjustment ratio to form the rear oxygen steady state interval.

[0014] Also provided is an electronic device, comprising: a memory, having a computer program stored thereon; and a processor, configured to execute the computer program in the memory to implement the air-fuel ratio control method.

[0015] Also provided is a non-transitory computer readable storage medium, having a computer program stored thereon, the program being executed by a processor to implement the air-fuel ratio control method.

[0016] The beneficial effects of the present application are embodied in:

[0017] In the whole air-fuel ratio control method, firstly, a double cycle history data verification mechanism is adopted, the dynamic change characteristics of the voltage sequence of the front oxygen sensor in two consecutive monitoring cycles are analyzed, the stability in the dynamic working condition is quantified, the direct dependence on the single sampling value is replaced, and the misjudgment risk caused by the exhaust disturbance noise and the instantaneous electromagnetic interference caused by the sudden acceleration and deceleration is fundamentally avoided; further, the rear oxygen steady state interval adaptive strategy triggered by the front oxygen stability is introduced, the stable state is captured by using the high response characteristics of the front oxygen, the preset standard voltage interval boundary is dynamically compressed according to the historical stability, the fixed interval misjudgment problem caused by the engine state and other problems is solved, the rear oxygen reference judgment is matched with the actual running state in real time, and the dynamic fusion control based on the double stability verification is further carried out. Only when the historical front oxygen signal fluctuation is low and the rear oxygen signal has high convergence in the new interval, the sensor instantaneous value at the current time is allowed to be fused. The initial air-fuel ratio estimated value of the front oxygen voltage is mapped, and the closed-loop compensation algorithm of the rear oxygen voltage super boundary amplitude is superposed, so that the advantages of the front oxygen rapid response are retained, the short-time fluctuation is inhibited through the rear oxygen filtering characteristics, and the air-fuel ratio close to the real combustion state is output. Finally, the precise execution is realized through the nonlinear fuel injection compensation mechanism, the scaling ratio is dynamically generated according to the deviation direction and amplitude of the corrected air-fuel ratio and the theoretical value, the bidirectional adjustment (rich oil injection, lean oil injection) is executed, the fuel injection pulse width oscillation caused by the signal distortion in the traditional method is avoided, and the combustion efficiency and emission level are simultaneously optimized under the complex working conditions such as sudden load change, cold start and plateau low pressure. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0019] Figure 1 It is a part of the air-fuel ratio control method of the present application.

[0020] Figure 2 It is another part of the air-fuel ratio control method of the present application.

[0021] Figure 3 It is a step diagram of the air-fuel ratio control method of the present application.

[0022] Figure 4 It is a part of the step diagram of S2 in the air-fuel ratio control method of the present application.

[0023] Figure 5 It is a part of the step diagram of S3 in the air-fuel ratio control method of the present application.

[0024] Figure 6Fig. 4 is a flowchart illustrating a part of the method for controlling air-fuel ratio according to the present application;

[0025] Figure 7 Fig. 5 is a block diagram of an electronic device according to an embodiment of the present application.

[0026] Reference numerals:

[0027] 700 - electronic device, 701 - processor, 702 - memory, 703 - multimedia component, 704 - I / O interface, 705 - communication component. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0030] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second" and the like are only used to distinguish description, and cannot be understood as indicating or implying relative importance.

[0031] As shown in Figure 1 , Figure 2 and Figure 3 , a method for controlling air-fuel ratio is provided, comprising:

[0032] S1, obtaining a front oxygen sensor arranged between an exhaust manifold and a three-way catalyst and a rear oxygen sensor arranged between the three-way catalyst and an exhaust pipe, obtaining a current monitoring period in which a current time is located, obtaining two historical monitoring periods before the current monitoring period, and obtaining a front oxygen ion concentration voltage sequence in the two historical monitoring periods according to the front oxygen sensor, and obtaining a rear oxygen ion concentration voltage sequence in the two historical monitoring periods according to the rear oxygen sensor;

[0033] S2, obtain a pre-oxygen stability index according to the two pre-oxygen ion concentration voltage sequences, and determine whether the pre-oxygen stability index is lower than a first preset threshold value, if lower, obtain a post-oxygen steady state interval based on the pre-oxygen stability index, and obtain a post-oxygen stability index according to a proportion of the two post-oxygen ion concentration voltage sequences in the post-oxygen steady state interval;

[0034] S3, determine whether the post-oxygen stability index is higher than the first preset threshold value, if higher, collect a current pre-oxygen ion concentration voltage value and a current post-oxygen ion concentration voltage value at the current time based on the pre-oxygen sensor and the post-oxygen sensor, and obtain a current air-fuel ratio according to the current pre-oxygen ion concentration voltage value and the current post-oxygen ion concentration voltage value;

[0035] S4, obtain a standard air-fuel ratio, and obtain an injection nozzle control compensation ratio according to the current air-fuel ratio and the standard air-fuel ratio.

[0036] In the embodiment, it should be noted that in S1, as an initial data collection stage, the core target is to establish a historical reference of sensor data. Specifically, first, the ion concentration voltage signals in the exhaust gas are obtained in real time through the pre-oxygen sensor physically installed between the exhaust manifold and the three-way catalyst, and the post-oxygen sensor between the three-way catalyst and the exhaust pipe. At the same time, the running time is divided into fixed monitoring periods (for example, data collection windows defined based on engine speed or time interval), and based on the monitoring period at the current time, the previous two consecutive periods are traced back and extracted as historical references. In each monitoring period, the data obtained from the pre-oxygen sensor is arranged as a pre-oxygen ion concentration voltage sequence, which represents the dynamic change trajectory of the sensor voltage value in the corresponding time period; similarly, the data obtained from the post-oxygen sensor forms a post-oxygen ion concentration voltage sequence, which together with the pre-oxygen ion concentration voltage sequence forms the key input source. This step solves the distortion problem of single sampling in existing methods, because it emphasizes multi-period sequences rather than instantaneous points, and can exclude transient interference such as exhaust pulsation in advance, providing a continuous data background for subsequent stability evaluation.

[0037] Further, when the engine enters a new monitoring window (such as a 100ms period), the control immediately links to retrieve the stored records of the previous two historical periods: assuming that the pre-oxygen voltage sequence of the previous period contains the ordered change of voltage values from the beginning to the end, and the post-oxygen sequence of the next period records the smooth response trend under deceleration conditions. Similarly, the pre-oxygen sequence exhibits a continuous value chain that rises or falls in the historical data, while the post-oxygen sequence exhibits a stable trend line with a lag, both of which are stored in time point order. Through these sequences, the common patterns of the sensors in dynamic events (such as noise characteristics during historical acceleration or deceleration) can be analyzed, laying a foundation for the stability index calculation of step S2, and avoiding misjudgment caused by directly relying on distorted sampling.

[0038] In S2, the stability of the pre-oxygen sensor is quantified by historical data, and the reference judgment interval of the post-oxygen sensor is dynamically corrected accordingly. First, the fluctuation of the pre-oxygen voltage sequence in the two historical monitoring periods is analyzed, and the stability is evaluated by calculating the cumulative value of the change amplitude of the consecutive voltage values in the sequence (such as the smoothness of the voltage curve in the monitoring period). If the stability index is higher than a certain threshold (i.e. the fluctuation is low), it means that the exhaust gas flow in the historical stage is stable and there is no sudden change in the working condition, so it is determined that the current time has the conditions to perform the subsequent operation. Subsequently, based on the deviation of the pre-oxygen stability index from the threshold, an adjustment ratio is generated - the more stable the historical data (the higher the index), the larger the adjustment ratio, and then the pre-set post-oxygen standard steady-state interval is compressed by a larger range (for example, the range of the compressed boundary is tightened in proportion), forming a new adaptive reduced post-oxygen steady-state interval. This step essentially uses the high responsiveness of the pre-oxygen signal to capture stability and avoid false judgments caused by fixed intervals.

[0039] Further, it is necessary to verify whether the post-oxygen signal in the historical period meets the expectations of the new steady-state interval. In specific operations, all data points of the two historical post-oxygen voltage sequences are traversed, and the proportion of them falling within the adaptive interval is counted: if most of the data points are within the interval (such as the gentle voltage group after sudden deceleration under the action of the three-way catalyst), it indicates that the post-oxygen signal is stable and meets the standard due to the influence of the catalyst filter; if a large number of data points deviate from the interval (such as abnormal fluctuations when the catalyst is not ignited during the cold start stage), it indicates that the post-oxygen signal itself has distortion risk. This proportion value is converted into a post-oxygen stability index, which serves as the basis for whether to use the current real-time signal for air-fuel ratio correction in the future. For example, when the vehicle smoothly transitions from high-speed cruising, the interval contraction triggered by the minimal fluctuation of the pre-oxygen historical sequence and the high proportion of the post-oxygen sequence falling within the new interval ensure the reliability of the next stage of control.

[0040] In S3, after the double stability verification, the sensor instantaneous value at the current time is fused and calculated to dynamically correct the initial air-fuel ratio estimate. When it is determined that the pre-oxygen historical data is stable (the pre-oxygen stability index is lower than the first preset threshold in S2) and the proportion of the post-oxygen historical data within the adaptive interval meets the standard (the post-oxygen stability index is higher than the second preset threshold), it means that the current working condition is in a reliable stable state. At this time, the real-time voltage value of the pre-oxygen sensor at the current time is synchronously collected - its fast response characteristic is used to capture the instantaneous exhaust state, and it is converted into an initial air-fuel ratio estimate through a pre-set voltage-air-fuel ratio mapping table. At the same time, the voltage value of the current post-oxygen sensor is read, which is lagged but affected by the three-way catalyst filter and can better reflect the overall trend of the mixture. The key of this step is: only when the historical data proves that there is no sudden disturbance, the instantaneous signal which is easily affected by noise is allowed to be used, avoiding false triggering of control caused by distorted sampling.

[0041] Further, the post-oxygen signal is introduced to dynamically correct the initial estimate to improve accuracy. In specific operation, the current post-oxygen voltage value is compared with the adaptive adjustment steady-state interval boundary - if the voltage exceeds the upper limit of the interval, it is determined that the actual concentration of the mixture is richer than the pre-oxygen instantaneous value feedback (such as the post-oxygen voltage remains high due to the hysteresis of the catalyst after sudden acceleration), and the initial air-fuel ratio needs to be adjusted according to the preset rule. If it is lower than the lower limit, it is adjusted to be rich. The correction strength is determined by the amplitude of the boundary: slight deviation triggers small range correction, and serious deviation triggers strong compensation. For example, when the vehicle smoothly transitions from idle to uniform speed, the pre-oxygen instantaneous value indicates that the air-fuel ratio is normal, but the post-oxygen voltage is slightly higher than the upper limit of the new interval due to hysteresis. Accordingly, the initial estimate is adjusted, and the small deviation that may be ignored by the pre-oxygen signal is compensated for, and the air-fuel ratio output is closer to the real combustion state.

[0042] In S4, the corrected air-fuel ratio estimate is converted into an accurate fuel injection amount compensation instruction to realize the execution layer adjustment in the closed-loop control. Specifically, first, the deviation direction and amplitude of the current air-fuel ratio and the theoretical standard air-fuel ratio are compared (for example: current value 14.76 vs. standard value 14.70), and an adjustment coefficient is dynamically generated based on the deviation degree - the coefficient is not a fixed proportion, but according to different data ranges, different scaling ratios are mapped: small proportion compensation is used for slight deviation to avoid excessive adjustment; strong compensation is used for significant deviation to accelerate convergence. This step scales the basic fuel injection pulse width by quantifying the deviation, rather than directly replacing the original control, to ensure smooth transition of the adjustment process to the vicinity of the theoretical air-fuel ratio.

[0043] Further, the fuel injection amount needs to be bidirectionally corrected according to the demand of the mixture concentration. When the current air-fuel ratio is greater than the standard value (the mixture is too lean), a positive adjustment coefficient is generated to increase the fuel injection pulse width in proportion to supplement the fuel supply; on the contrary, when the current air-fuel ratio is less than the standard value (the mixture is too rich), a negative adjustment coefficient is generated to reduce the fuel injection pulse width. For example, when the vehicle cruising state suddenly encounters an uphill load, the air-fuel ratio output by S3 is higher than the standard value due to the increase in intake air volume, which will automatically increase the fuel injection amount to a reasonable range, avoiding acceleration weakness and preventing emission deterioration, and finally realizing the coordinated optimization of combustion stability and emission control.

[0044] In summary, in the whole air-fuel ratio control method, first, a double-cycle historical data verification mechanism is adopted, the dynamic change characteristics of the voltage sequence of the front oxygen sensor in two consecutive monitoring cycles are analyzed, the stability in the dynamic working condition is quantified, the direct dependence on the single sampling value is replaced, and the misjudgment risk caused by the exhaust disturbance noise and the instantaneous electromagnetic interference caused by the sudden acceleration and deceleration is fundamentally avoided; further, a rear oxygen steady state interval adaptive strategy triggered by the front oxygen stability is introduced, the stable state is captured by using the high response characteristic of the front oxygen, the preset standard voltage interval boundary is dynamically compressed according to the historical stability, the fixed interval misjudgment problem caused by the engine state and other problems is solved, the rear oxygen reference judgment is matched with the actual running state in real time, and the dynamic fusion control based on the double stability verification is further carried out. Only when the historical front oxygen signal fluctuation is low and the rear oxygen signal has high convergence in the new interval, the sensor instantaneous value at the current moment is allowed to be fused. The initial air-fuel ratio estimated value of the front oxygen voltage mapping is superimposed with the closed-loop compensation algorithm of the rear oxygen voltage super-boundary amplitude, the advantages of the front oxygen fast response are retained, the short-time fluctuation is inhibited through the rear oxygen filtering characteristic, and the air-fuel ratio closer to the real combustion state is output. Finally, through the nonlinear fuel injection compensation mechanism, accurate execution is realized, the deviation direction and amplitude of the corrected air-fuel ratio and the theoretical value are used to dynamically generate a scaling ratio to perform bidirectional adjustment (increasing fuel for too lean and decreasing fuel for too rich), the fuel injection pulse width oscillation caused by signal distortion in the traditional method is avoided, and the combustion efficiency and emission level are simultaneously optimized under complex working conditions such as sudden load change, cold start and high altitude low pressure.

[0045] As shown in Figure 1 and Figure 4 in an embodiment, the rear oxygen steady state interval based on the front oxygen stability index in S2 includes:

[0046] S21, obtaining an adjustment ratio according to the front oxygen stability index and a first preset threshold;

[0047] S22, obtaining a standard steady state interval, and reducing the standard steady state interval according to the adjustment ratio to form a rear oxygen steady state interval.

[0048] In the embodiment, it should be noted that in S21, the core is to convert the quantization result of the front oxygen stability index into an intensity parameter of interval adjustment. In specific operation, the adjustment ratio is dynamically determined according to the difference between the front oxygen stability index and the first preset threshold: the lower the fluctuation of the front oxygen historical sequence (i.e., the index is closer to the highest stability level), the greater the absolute value of the difference, and the greater the value of the corresponding adjustment ratio. This design reflects a key logic: when the historical data proves that the exhaust state is highly stable, the rear oxygen reference interval can be more boldly shrunk to improve the judgment sensitivity. For example, if the engine returns to stable cruising after sudden acceleration, the front oxygen sequence continuously shows slight fluctuation (the difference is significant), and the adjustment ratio close to the upper limit is generated, providing strong driving for subsequent interval compression.

[0049] Further, the adjustment ratio is calculated according to the difference between the previous oxygen stability index and the first preset threshold, and the specific formula is: adjustment ratio K = min((first preset threshold - previous oxygen stability index) / first preset threshold, maximum adjustment ratio upper limit). The maximum adjustment ratio upper limit is usually set to 0.8 to prevent excessive narrowing of the interval.

[0050] For example, set the first preset threshold to 0.7 (representing a stable benchmark): case 1, if the previous oxygen stability index is 0.6 (lower than the threshold 0.7), the absolute value of the difference is 0.1, the adjustment ratio K = min(0.1 / 0.7, 0.8) ≈ min(0.1429, 0.8) = 0.1429, which indicates that the stability is good and the adjustment ratio is small; case 2: if the previous oxygen stability index is 0.2 (much lower than the threshold 0.7), the absolute value of the difference is 0.5, the adjustment ratio K = min(0.5 / 0.7, 0.8) ≈ min(0.7143, 0.8) = 0.7143, which represents excellent stability and a larger adjustment ratio, resulting in more significant interval compression.

[0051] In S22, the post-oxygen steady-state interval is generated by using the adjustment ratio to direct the contraction of the standard steady-state interval, forming a dynamic benchmark range that adapts to the actual working condition. First, a preset standard steady-state interval (such as a wide voltage band calibrated on a test bench) is called, and then the interval boundaries are reduced according to the adjustment ratio: the larger the ratio, the greater the synchronous inward contraction of the upper and lower limits of the interval, but a contraction upper limit is set to prevent excessive narrowing that would result in loss of fault tolerance. For example, in a high-altitude low-pressure environment, the engine is running stably for a long time, and the previous oxygen stability index is extremely high, triggering a large contraction. The new post-oxygen steady-state interval only retains the core part of the standard interval (such as eliminating the edge fluctuation band), and at this time, if the post-oxygen voltage is relatively high overall compared to the calibration value, this contraction mechanism can automatically match the voltage offset and avoid misjudging the actual normal rich mixture signal as abnormal.

[0052] Further, the standard steady-state interval is symmetrically reduced based on the adjustment ratio, and the formula is: post-oxygen steady-state interval = [original minimum value + (adjustment ratio x interval half-width), original maximum value - (adjustment ratio x interval half-width)], where interval half-width = (original maximum value - original minimum value) / 2.

[0053] For example, set the standard steady-state interval to [650mV, 750mV] (half-width 50mV): case 1, adjust the proportion K=0.1429, new minimum value=650+(0.1429x50)≈650+7.145=657.145mV, new maximum value=750-(0.1429x50)≈750-7.145=742.855mV, new interval [657mV, 743mV]; case 2: adjust the proportion K=0.7143, new minimum value=650+(0.7143x50)≈650+35.715=685.715mV, new maximum value=750-(0.7143x50)≈750-35.715=714.285mV, new interval [686mV, 714mV], which reflects a significant contraction of the interval under high stability, improving the sensitivity of the judgment.

[0054] As shown in Figure 5 In one embodiment, obtaining the current air-fuel ratio according to the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value in S3 includes:

[0055] S31, obtaining a mapping relationship between the front oxygen ion concentration voltage and the air-fuel ratio;

[0056] S32, obtaining an initial air-fuel ratio according to the current front oxygen ion concentration voltage value and the mapping relationship;

[0057] S33, obtaining a correction value according to the current rear oxygen ion concentration voltage value and the standard steady-state interval, and obtaining the current air-fuel ratio according to the correction value and the initial air-fuel ratio.

[0058] In the present embodiment, it should be noted that in S31, a physical correlation between the front oxygen voltage signal and the air-fuel ratio is established. The mapping relationship between the front oxygen ion concentration voltage and the air-fuel ratio is a physical quantity conversion database established through engine bench calibration experiments, and its establishment process does not depend on mathematical models or algorithms, but is based on standardized experimental procedures and physical measurement data. The specific steps are as follows: maintain the engine at a fixed operating point (e.g., 2000 rpm, 50% load), adjust the fuel injection amount step by step through the fuel supply system, and continuously transition the exhaust air-fuel ratio from lean mixture (air-fuel ratio > 1) to rich mixture (air-fuel ratio < 1), covering the full working range of the sensor; then, after adjusting the fuel injection amount each time, wait for the system to stabilize, and measure the true air-fuel ratio with an air-fuel ratio analyzer, and simultaneously read the front oxygen sensor output voltage, repeat the above operation, and obtain multiple sets of corresponding data points; finally, arrange the effective data pairs in ascending order of voltage value, and generate a discrete mapping table, and store it. Specifically, for example, the typical data is as follows:

[0059]

[0060] Further, first, a stored voltage-air-fuel ratio discrete mapping table is called, which is generated based on engine bench calibration experiments and accurately records the correspondence between the voltage value of the front oxygen sensor output and the theoretical air-fuel ratio under different exhaust oxygen concentrations. The mapping is essentially a nonlinear curve: the low voltage area corresponds to lean mixture (high air-fuel ratio), and the high voltage area corresponds to rich mixture (low air-fuel ratio). For example, when the oxygen content in the exhaust gas suddenly increases (such as the opening of the throttle), the front oxygen voltage will quickly drop to the low value interval, and at this time the mapping table can immediately convert the voltage change to the air-fuel ratio offset amplitude.

[0061] In S32, the transient state is captured using the fast response characteristics of the front oxygen real-time voltage. The front oxygen voltage value collected at the current time is input into the mapping table, and the initial air-fuel ratio estimate is output by interpolation calculation. For example, when the exhaust gas flow recovers smoothly after sudden deceleration, the front oxygen voltage falls from the fluctuating high point to the medium level, and the mapping table outputs a medium air-fuel ratio value. This step fully utilizes the response speed advantage of the front oxygen to provide a baseline reference for subsequent correction, but attention should be paid to its limitation of being easily disturbed by transient noise.

[0062] For example, based on the front oxygen real-time voltage, the initial estimate is output by table lookup: the exhaust gas is stable, and the current front oxygen ion concentration voltage value falls to 600 mV; the lookup table result is 600 mV→air-fuel ratio 14.3 (directly matching the calibration point).

[0063] If it is an interpolation scenario: if the voltage is 650 mV (between 600-750 mV), the linear interpolation calculation is as follows: air-fuel ratio difference=14.3-13.8=0.5; voltage difference=750-600=150 mV; air-fuel ratio change per unit voltage=0.5 / 150≈0.0033 / mV; 650 mV offset=(650-600)×0.0033≈0.165; initial air-fuel ratio=14.3-0.165=14.135.

[0064] In S33, the initial estimate is compensated by introducing the lagging but stable signal of the rear oxygen. Three steps are performed. First, boundary comparison, compare the current rear oxygen voltage value with the adaptive steady state interval generated in S2. Second, correction direction determination, if the rear oxygen voltage exceeds the upper limit of the interval (indicating that the exhaust gas after the catalyst is too rich), the initial lean air-fuel ratio needs to be adjusted downward; if it is lower than the lower limit (indicating that it is too lean), it needs to be adjusted upward. Finally, the correction strength calculation: according to the absolute amplitude of the boundary exceeding, the compensation amount is graded according to the preset rules - the more the exceeding limit, the larger the correction coefficient, and the correction strength and the boundary deviation show a non-linear increasing relationship. For example, in the plateau low-pressure environment, the front oxygen voltage indicates that the air-fuel ratio is normal (the initial estimate is reasonable), but the rear oxygen continuously outputs a high voltage due to the low atmospheric oxygen content; when its value exceeds the upper limit of the adaptive interval, the initial estimate is significantly adjusted according to the exceeding limit, compensating for the trend of continuous rich mixture that the front oxygen has not perceived, and finally outputting an air-fuel ratio that matches the actual working condition.

[0065] Further, for example, first, the boundary comparison and correction direction, the rear oxygen adaptive steady state interval (S22 generation): [650mV, 750mV], the current rear oxygen voltage 780mV, then the over-limit 30mV (780-750=30), determine: over-limit indicates that the mixture is too rich, and needs to be adjusted (downward correction of the initial air-fuel ratio). Then, the correction strength calculation is performed, and the correction amount (air-fuel ratio) is changed by 0.03 for each over-limit 10mV, and the total amount of over-limit is 30mV, and the correction amount is (30 / 10) x (0.03)=0.09. Finally, the initial air-fuel ratio (S32 output) is 14.85, the correction amount is 0.09, and the current air-fuel ratio is 14.85-0.09=14.76 (according to the determination result, the initial air-fuel ratio is corrected downward).

[0066] In summary, the entire correction mechanism is complementary through the dual sensors: avoiding the fast response of the front oxygen but easy to be distorted, providing transient reference; the rear oxygen is lagged but filtered by the catalyst, correcting the system deviation. The final output value overcomes the noise of sudden working conditions and high environmental interference, and compresses the air-fuel ratio control error from ±0.5 of the traditional method to within ±0.1.

[0067] As shown in FIG. 4, in one embodiment, the S4 includes: Figure 6

[0068] S41, determining an adjustment coefficient based on the deviation degree of the current air-fuel ratio and the standard air-fuel ratio, wherein the adjustment coefficient is used to scale the basic injection pulse width;

[0069] S42, generating a positive adjustment coefficient to increase the injection amount when the current air-fuel ratio is greater than the standard air-fuel ratio;

[0070] S43, generating a negative adjustment coefficient to reduce the injection amount when the current air-fuel ratio is less than the standard air-fuel ratio.

[0071] In this embodiment, it should be noted that in S41, the compensation strength is dynamically scaled according to the air-fuel ratio deviation amplitude. First, calculate the absolute deviation amount of the current air-fuel ratio and the standard value (such as |14.76-14.70|=0.06), and determine the adjustment coefficient based on the preset nonlinear response curve: when the deviation is less than the critical value (such as 0.05), a low gain coefficient is used to avoid over-regulation, and a high gain coefficient is used after the deviation exceeds the critical value to accelerate convergence. This design is essentially a fuzzy control rule - conservative regulation to maintain stability when the deviation is small, and aggressive compensation to quickly correct the deviation when the deviation is large. For example, when the mixture is instantaneously too rich (deviation 0.1) during cold start, a high gain coefficient (such as 0.8) is enabled, and only a small gain (such as 0.1) is triggered for a stable micro-fluctuation (deviation 0.02).

[0072] ​In S42, the fuel addition strategy for the lean mixture state is implemented. When the current air-fuel ratio is greater than the standard value (e.g., 15.2>14.70), a positive adjustment coefficient (positive value) is generated, and the base injection pulse width is proportionally expanded: new pulse width=base pulse width x (1+adjustment coefficient). For example, when sudden acceleration occurs during cruising, the intake air surges, and the current air-fuel ratio jumps to 15.1, the injection pulse width is expanded to 160% of the base value with an adjustment coefficient of 0.6, quickly filling the fuel gap and preventing combustion interruption. This process is synchronized with the exhaust gas temperature monitoring to avoid excessive addition and cause the exhaust temperature to exceed the limit.

[0073] In S43, the fuel reduction mechanism for the rich mixture state is implemented. When the current air-fuel ratio is less than the standard value (e.g., 13.8<14.70), a negative adjustment coefficient (negative value) is generated, and the injection pulse width is compressed: new pulse width=base pulse width x (1-|adjustment coefficient|). For example, when the mixture is too rich (air-fuel ratio 13.9) after resuming fuel supply after deceleration fuel cut, the pulse width is reduced to 50% of the base value with an adjustment coefficient of 0.5. Key protection design: when the adjusted pulse width approaches the minimum injection threshold, the reduction amount is frozen to maintain the minimum fuel supply, preventing injector flameout.

[0074] In one embodiment, the pre-oxygen stability index is obtained according to two pre-oxygen ion concentration voltage sequences in S2, represented as:

[0075] ; wherein,

[0076] is the pre-oxygen stability index, is the first weight coefficient, is the second weight coefficient, is the number of data acquisition nodes in the monitoring period, is the pre-oxygen ion concentration voltage value corresponding to the i+1th data acquisition node in the previous historical monitoring period, is the pre-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the previous historical monitoring period, is the pre-oxygen ion concentration voltage value corresponding to the i+1th data acquisition node in the next historical monitoring period, is the pre-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the next historical monitoring period.

[0077] In this embodiment, it should be noted that, and ​All are the difference of the adjacent node voltage, not the absolute value, allowing the result to be positive (upward trend) or negative (downward trend). Thus, the stability index is larger when the vehicle is accelerating or decelerating rapidly; for rapid acceleration, the exhaust oxygen concentration drops sharply, and the front oxygen voltage continuously rises in one direction (the difference sequence is all positive), the cumulative sum is a large positive value, and finally the absolute value is taken to eliminate the sign, so the stability index is larger; for rapid deceleration, the oxygen concentration increases sharply, and the voltage continuously decreases in one direction (the difference sequence is all negative), the cumulative sum is a large negative value, and finally the absolute value is taken to eliminate the sign, so the stability index is larger. Under normal and stable working conditions, the voltage fluctuates bidirectionally around the mean value with a small amplitude (e.g., +10 mV followed by 8 mV), and the positive and negative differences partially offset, so the cumulative sum tends to zero (low fluctuation), and finally the absolute value is taken to eliminate the sign, so the stability index is smaller. If the absolute value is used, both one-way mutation and two-way noise will output a high positive value, and it is impossible to distinguish between real working condition mutation and transient disturbance. The present design separates one-way drift (working condition mutation) from oscillatory noise through direction sensitivity.

[0078] Further, a double-period weighted fusion mechanism; the difference sums of two historical monitoring periods are respectively assigned weights and , and , and then summed. If the previous period is rapidly accelerating and the subsequent period is stable, set , , which can increase the weight of the subsequent period, thereby weakening the contribution of the unstable previous period and improving the contribution of the stable subsequent period. That is, the recent subsequent period generally reflects the current state, and generally > (e.g. ), so that the system pays more attention to the latest trend and avoids early fluctuations.

[0079] In one embodiment, the rear oxygen stability index S2 is obtained according to the proportion of the two rear oxygen ion concentration voltage sequences in the rear oxygen stable interval, and is expressed as:

[0080] ;

[0081] ;

[0082] ; wherein,

[0083] is the rear oxygen stability index, is the number of data acquisition nodes in the monitoring period, is the i-th first intermediate coefficient, is the rear oxygen ion concentration voltage value corresponding to the i-th data acquisition node in the previous historical monitoring period, is the minimum value of the rear oxygen stable interval, is a maximum value of the post-oxygen steady-state interval, is the ith second intermediate coefficient, is the post-oxygen ion concentration voltage value corresponding to the ith data acquisition node in the next historical monitoring period.

[0084] In one embodiment, it should be noted that, and Both embody the 0 / 1 binary quantization mechanism (core anti-interference design); for each data point, the attribution determination is made, and the value is taken as 1 if it is located in the interval; and the value is taken as 0 if it is outside the interval. Thus, electromagnetic interference, occasional spikes caused by exhaust pulsation (such as a single-point voltage rising to 800 mV during cold start) and real over-limit voltage values will be directly judged as 0 and will not participate in the proportion calculation. Further, when the catalyst is at low temperature, the post-oxygen voltage continuously oscillates at low frequency (such as [650, 690, 620, 710] mV). Assuming that the new interval is [680, 720], then 690 mV takes 1, 620 mV takes 0, and 710 mV takes 1; the effective data proportion is 50%, which accurately reflects the “unstable state” rather than misjudging as a fault.

[0085] Further, it also embodies double-cycle global fusion. The number of effective points in the previous cycle is counted, The number of effective points in the next cycle is counted, and the sum of the two is divided by the total number of points 2n. If 40% of the data in the previous cycle is out of the interval due to deceleration disturbance ( ), and 90% of the data in the next cycle is in the interval ( ), then: However, the disturbance in the previous cycle is not excessively punished, and the improvement in the next cycle is not ignored.

[0086] Further, it also embodies output normalization and threshold decision. represents that all data points in the two cycles are located in the adaptive interval (highly stable); represents that all data deviates from the interval (severe instability). Assuming that the second preset threshold is 0.9, then it is determined that the post-oxygen signal proportion meets the standard, and the current real-time signal is used to correct the air-fuel ratio; then the control is skipped to prevent the filter of the catalyst from being invalid, causing distortion of the correction.

[0087] Also provided is an air-fuel ratio control system, which comprises:

[0088] The acquisition module is configured to acquire a front oxygen sensor arranged between an exhaust manifold and a three-way catalyst and a rear oxygen sensor arranged between the three-way catalyst and an exhaust pipe, acquire a current monitoring period in which a current time point is located, acquire two historical monitoring periods before the current monitoring period, acquire a front oxygen ion concentration voltage sequence in the two historical monitoring periods respectively according to the front oxygen sensor, and acquire a rear oxygen ion concentration voltage sequence in the two historical monitoring periods respectively according to the rear oxygen sensor.

[0089] The first data processing module is configured to acquire a front oxygen stability index according to the two front oxygen ion concentration voltage sequences, determine whether the front oxygen stability index is lower than a first preset threshold, acquire a rear oxygen steady state interval based on the front oxygen stability index if the front oxygen stability index is lower than the first preset threshold, and acquire a rear oxygen stability index according to a proportion of the rear oxygen ion concentration voltage sequences in the rear oxygen steady state interval.

[0090] The second data processing module is configured to determine whether the rear oxygen stability index is lower than a second preset threshold, acquire a current front oxygen ion concentration voltage value and a current rear oxygen ion concentration voltage value at the current time point based on the front oxygen sensor and the rear oxygen sensor if the rear oxygen stability index is lower than the second preset threshold, and acquire a current air-fuel ratio according to the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value.

[0091] The control module is configured to acquire a standard air-fuel ratio, and acquire a fuel injection nozzle control compensation ratio according to the current air-fuel ratio and the standard air-fuel ratio.

[0092] In an embodiment, the first data processing module is further configured to acquire an adjustment ratio according to the front oxygen stability index and the first preset threshold, acquire a standard steady state interval, and narrow the standard steady state interval to form the rear oxygen steady state interval according to the adjustment ratio.

[0093] In the embodiment, it should be noted that, as to the above-mentioned air-fuel ratio control system, the specific manner of performing operations has been described in detail in the embodiments of the air-fuel ratio control method, and will not be described in detail here.

[0094] Figure 7 is a block diagram of an electronic device according to an exemplary embodiment of an air-fuel ratio control method. As shown in Figure 7 the electronic device 700 can include a processor 701 and a memory 702. The electronic device 700 can further include one or more of a multimedia component 703, an I / O interface 704 (input / output interface), and a communication component 705.

[0095] The processor 701 is configured to control overall operations of the electronic device 700 to complete all or part of the steps of the air-fuel ratio control method described above. The memory 702 is configured to store various types of data to support operations of the electronic device 700, which can include, for example, instructions for any application or method operating on the electronic device 700, and application-related data, such as contact data, transmitted and received messages, pictures, audio, video, and the like. The memory 702 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as a static random access memory (SRAM), an electrically erasable programmable read-only memory (EEPROM), an erasable programmable read-only memory (EPROM), a programmable read-only memory (PROM), a read-only memory (ROM), a magnetic storage, a flash memory, a magnetic disk, or an optical disk. The multimedia component 703 can include a screen and an audio component. The screen can be, for example, a touch screen, and the audio component is configured to output and / or input audio signals. For example, the audio component can include a microphone configured to receive external audio signals. The received audio signals can be further stored in the memory 702 or transmitted through the communication component 705. The audio component further includes at least one speaker configured to output audio signals. The I / O interface 704 provides an interface between the processor 701 and other interface modules, which can be a keyboard, a mouse, a button, and the like. The buttons can be virtual buttons or physical buttons. The communication component 705 is configured to perform wired or wireless communication between the electronic device 700 and other devices. The wireless communication, such as Wi-Fi, Bluetooth, near field communication (NFC), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, and the like, or a combination of one or more of them, is not limited herein. Therefore, the communication component 705 can include, for example, a Wi-Fi module, a Bluetooth module, an NFC module, and the like.

[0096] In an exemplary embodiment, the electronic device 700 can be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, micro-controllers, microprocessors, or other electronic elements for performing the air-fuel ratio control method described above.

[0097] In another exemplary embodiment, a computer-readable storage medium including program instructions that, when executed by a processor, implement the steps of the air-fuel ratio control method described above is also provided. For example, the computer-readable storage medium can be the memory 702 described above including program instructions that are executable by the processor 701 of the electronic device 700 to complete the air-fuel ratio control method described above.

[0098] In another exemplary embodiment, a computer program product containing a computer program executable by a programmable device, the computer program having code portions for performing the air-fuel ratio control method described above when executed by the programmable device is also provided.

[0099] The preferred embodiments of the present disclosure are described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above-described embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0100] In addition, it should be noted that each of the specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0101] Furthermore, any combination of the various different embodiments of the present disclosure can also be made, as long as it does not deviate from the idea of the present disclosure, it should also be considered as disclosed by the present disclosure.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalent replacements; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. An air-fuel ratio control method, characterized in that, include: The system acquires the front oxygen sensor located between the exhaust manifold and the three-way catalytic converter and the rear oxygen sensor located between the three-way catalytic converter and the exhaust gas pipeline. It acquires the current monitoring cycle at the current moment, acquires the two monitoring cycles before the current monitoring cycle and uses them as two historical monitoring cycles. It also acquires the front oxygen ion concentration voltage sequence in the two historical monitoring cycles based on the front oxygen sensor and the rear oxygen ion concentration voltage sequence in the two historical monitoring cycles based on the rear oxygen sensor. The pre-oxygen stability index is obtained based on two pre-oxygen ion concentration voltage sequences, and it is determined whether the pre-oxygen stability index is lower than a first preset threshold. If it is lower, the post-oxygen steady-state interval is obtained based on the pre-oxygen stability index, and the post-oxygen stability index is obtained based on the proportion of the two post-oxygen ion concentration voltage sequences that are in the post-oxygen steady-state interval. Determine whether the post-oxygen stability index is higher than the second preset threshold. If it is higher, collect the current pre-oxygen ion concentration voltage value and the current post-oxygen ion concentration voltage value at the current moment based on the pre-oxygen sensor and the post-oxygen sensor, and obtain the current air-fuel ratio based on the current pre-oxygen ion concentration voltage value and the current post-oxygen ion concentration voltage value. Obtain the standard air-fuel ratio, and then determine the injector control compensation ratio based on the current air-fuel ratio and the standard air-fuel ratio.

2. The air-fuel ratio control method according to claim 1, characterized in that, The method for obtaining the post-oxygen steady-state range based on the pre-oxygen stability index includes: The adjustment ratio is obtained based on the pre-oxygen stability index and the first preset threshold. Obtain the standard steady-state range, and reduce the standard steady-state range according to the adjustment ratio to form the post-oxygen steady-state range.

3. The air-fuel ratio control method according to claim 2, characterized in that, The process of obtaining the current air-fuel ratio based on the current front oxygen ion concentration voltage value and the current rear oxygen ion concentration voltage value includes: Obtain the mapping relationship between pre-oxygen ion concentration voltage and air-fuel ratio; The initial air-fuel ratio is obtained based on the current pre-oxygen ion concentration voltage value and mapping relationship; The correction value is obtained based on the current post-oxygen ion concentration voltage value and the standard steady-state range, and the current air-fuel ratio is obtained based on the correction value and the initial air-fuel ratio.

4. The air-fuel ratio control method according to claim 1, characterized in that, The process of obtaining the injector control compensation ratio based on the current air-fuel ratio and the standard air-fuel ratio includes: An adjustment coefficient is determined based on the degree of deviation between the current air-fuel ratio and the standard air-fuel ratio, wherein the adjustment coefficient is used to scale the base injection pulse width proportionally. When the current air-fuel ratio is greater than the standard air-fuel ratio, a positive adjustment coefficient is generated to increase the fuel injection quantity; When the current air-fuel ratio is less than the standard air-fuel ratio, a negative adjustment coefficient is generated to reduce the amount of fuel injected.

5. The air-fuel ratio control method according to claim 1, characterized in that, The pre-oxygen stability index obtained based on two pre-oxygen ion concentration-voltage sequences is expressed as follows: , ;in, It serves as an indicator of pre-oxygen stability. As the first weighting coefficient, This is the second weighting coefficient. The number of data collection nodes for the monitoring period. This represents the preceding oxygen ion concentration voltage value corresponding to the (i+1)th data acquisition node in the previous historical monitoring cycle. This represents the preceding oxygen ion concentration voltage value corresponding to the i-th data acquisition node in the previous historical monitoring cycle. This represents the preceding oxygen ion concentration voltage value corresponding to the (i+1)th data acquisition node in the next historical monitoring cycle. This represents the preceding oxygen ion concentration voltage value corresponding to the i-th data acquisition node in the next historical monitoring cycle.

6. The air-fuel ratio control method according to claim 1, characterized in that, The post-oxygen stability index, obtained based on the proportion of post-oxygen ion concentration-voltage sequences within the post-oxygen steady-state range, is expressed as follows: ； ； ;in, As an indicator of post-oxygen stability, The number of data collection nodes for the monitoring period. For the i-th first intermediate coefficient, This represents the post-oxygen ion concentration voltage value corresponding to the i-th data acquisition node in the previous historical monitoring cycle. This is the minimum value in the post-oxygen steady-state range. This represents the maximum value in the post-oxygen steady-state range. For the i-th second intermediate coefficient, This represents the post-oxygen ion concentration voltage value corresponding to the i-th data acquisition node in the next historical monitoring cycle.

7. An air-fuel ratio control system, characterized in that, The system includes: The acquisition module is used to acquire the front oxygen sensor located between the exhaust manifold and the three-way catalytic converter and the rear oxygen sensor located between the three-way catalytic converter and the exhaust gas pipeline, acquire the current monitoring cycle at the current moment, acquire the two monitoring cycles before the current monitoring cycle as two historical monitoring cycles, and acquire the front oxygen ion concentration voltage sequence in the two historical monitoring cycles according to the front oxygen sensor, and acquire the rear oxygen ion concentration voltage sequence in the two historical monitoring cycles according to the rear oxygen sensor. The first data processing module is used to obtain the pre-oxygen stability index based on two pre-oxygen ion concentration voltage sequences, and determine whether the pre-oxygen stability index is lower than a first preset threshold. If it is lower, the module obtains the post-oxygen steady-state interval based on the pre-oxygen stability index, and obtains the post-oxygen stability index based on the proportion of the two post-oxygen ion concentration voltage sequences that are within the post-oxygen steady-state interval. The second data processing module is used to determine whether the post-oxygen stability index is lower than the second preset threshold. If it is lower, it collects the current pre-oxygen ion concentration voltage value and the current post-oxygen ion concentration voltage value at the current moment based on the pre-oxygen sensor and the post-oxygen sensor, and obtains the current air-fuel ratio based on the current pre-oxygen ion concentration voltage value and the current post-oxygen ion concentration voltage value. The control module is used to obtain the standard air-fuel ratio and to obtain the injector control compensation ratio based on the current air-fuel ratio and the standard air-fuel ratio.

8. The air-fuel ratio control system according to claim 7, characterized in that, The first data processing module is also used for: The adjustment ratio is obtained based on the pre-oxygen stability index and the first preset threshold. Obtain the standard steady-state range, and reduce the standard steady-state range according to the adjustment ratio to form the post-oxygen steady-state range.

9. An electronic device, characterized in that, include: A memory on which computer programs are stored; A processor for executing the computer program in the memory to implement the air-fuel ratio control method according to any one of claims 1 to 6.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the air-fuel ratio control method according to any one of claims 1 to 6.

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