Abnormality diagnosis method for engine system

Abstract

The application provides an abnormality diagnosis method applied to an engine system, and belongs to the technical field of engine control, and the method comprises the following steps: for the detection step in the current driving cycle, the following steps are performed: for each engine operating parameter, a corresponding filter coefficient is used for first-order low-pass filtering to obtain a corresponding filter value; in response to the engine working condition being a passive steady state condition, the EGR valve inlet pressure after secondary filtering is preprocessed to obtain a time difference array; according to the stability of the speed change rate, the periodic stability of the inlet pressure signal is determined by using the number of times that the time difference array is greater than a dynamic threshold; in response to the active pressure fluctuation checking condition being met and the engine working condition being an active steady state condition, the EGR valve inlet pressure is preprocessed to obtain an outlet pressure array; and according to the stability of the speed change rate, the fluctuation stability of the inlet pressure signal is determined by using the number of times that the outlet pressure array is greater than a dynamic threshold.

Description

Technical Field

[0001] This invention relates to the field of engine control technology, and in particular to a method for diagnosing anomalies in engine systems. Background Technology

[0002] Exhaust gas recirculation (EGR) draws exhaust gases from the exhaust system and introduces them into the intake system. Studies have shown that EGR systems have certain advantages in improving emissions, reducing fuel consumption, and improving anti-knock capabilities.

[0003] The gas pressure on both sides (inlet and outlet) of the EGR valve is a crucial input for EGR rate control, determining the accuracy of exhaust gas flow estimation and EGR valve opening control, thus affecting the precision of the EGR rate. Therefore, it is necessary to promptly check whether the EGR valve outlet gas pressure signal is normal to avoid affecting EGR rate control and causing adverse effects on engine performance. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and proposes an anomaly diagnosis method for engine systems.

[0005] In a first aspect, embodiments of the present invention provide a method for anomaly diagnosis applied to an engine system, comprising:

[0006] Filtering steps: For each engine operating parameter, perform a first-order low-pass filter using the corresponding filter coefficient to obtain the corresponding filter value; wherein, the engine operating parameters include at least engine speed parameters and engine-related parameters; the filter coefficient corresponding to each engine-related parameter is determined based on the stability of the engine speed parameters; the engine speed parameters include speed and speed change rate; the engine-related parameters include at least the EGR valve outlet pressure;

[0007] Passive pressure periodic verification steps: In response to determining that the engine operating condition is a passive steady-state condition using engine operating parameters and filter values, the filter values ​​of the EGR valve outlet pressure within the first preset number of sampling periods are preprocessed to obtain a time difference array; the time difference array includes at least the maximum value interval time array and the minimum value interval time array of the EGR valve outlet pressure; based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds the dynamic threshold;

[0008] Active pressure fluctuation verification step: In response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in response to the determination that the outlet pressure signal is stable and the number of stable times of the engine speed change rate meets the requirements in the passive pressure periodic verification step of the third consecutive preset number of driving cycles, the engine operating parameters and filter values ​​are used to determine whether the engine operating condition is an active steady-state condition; in response to the engine operating condition being an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array; based on the stability of the speed change rate, the number of times the outlet pressure array is greater than the dynamic threshold is used to determine the fluctuation stability of the outlet pressure signal.

[0009] According to an embodiment of the present invention, the engine-related parameters include at least one of the following: intake air density into the cylinder, throttle opening, mixing valve opening, EGR valve opening, EGR valve inlet pressure, and EGR valve outlet pressure; the method for calculating the filter coefficients corresponding to the engine-related parameters includes:

[0010] Determine whether the engine speed parameters are in a stable state;

[0011] If the engine speed parameters are stable, the current filter coefficient is calculated based on the preset calibration filter coefficient and the engine speed; the calibration filter coefficient is obtained by bench testing the engine at the preset speed.

[0012] If the engine speed parameters are unstable, the current filter coefficient is calculated based on the preset self-learning coefficient.

[0013] According to an embodiment of the present invention, the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods are preprocessed to obtain a time difference array, and the process further includes...

[0014] Using engine operating parameters and filter values, the engine operating condition is determined, specifically including:

[0015] By using engine operating parameters and the difference between engine operating parameters and corresponding filter values, it can be determined whether the engine meets the signal stability conditions.

[0016] If the time for the engine to meet the signal stabilization condition exceeds the first preset time, it is determined whether the engine meets the first EGR valve gas stabilization condition.

[0017] If the engine meets the gas stability condition of the first EGR valve, the engine operating condition is determined to be a passive steady-state condition.

[0018] According to an embodiment of the present invention, determining whether the engine meets the first EGR valve gas stability condition includes:

[0019] Determine whether the time it takes for the engine to meet the gas stability condition of the first EGR valve exceeds the first time interval;

[0020] If so, the engine is determined to meet the gas stability condition of the first EGR valve;

[0021] If not, the engine is determined not to meet the gas stability conditions of the first EGR valve, and the diagnostic process is terminated.

[0022] The first EGR valve gas stability conditions include:

[0023] Condition 1: The difference between the opening degree of the mixing valve and its filter value is less than the first threshold, which is the product of the minimum value of the opening degree of the mixing valve and its filter value and the first preset threshold coefficient;

[0024] Condition 2: The target EGR rate fluctuates within the first preset range;

[0025] Condition 3: The difference between the EGR valve opening and its filter value is less than the second threshold, which is the product of the minimum value of the EGR valve and its filter value and the second preset threshold coefficient;

[0026] Condition 4: The difference between the EGR valve inlet pressure and its filter value is less than the third threshold, which is the product of the minimum value of the EGR valve inlet pressure and its filter value and the third preset threshold coefficient;

[0027] Condition 5: No EGR valve inlet pressure sensor circuit failure occurred.

[0028] According to an embodiment of the present invention, the first-time acquisition method includes:

[0029] In response to the EGR valve opening being 0, the first time is the sum of the time it takes for the calibrated fresh air to flow from the mixing valve outlet to the booster inlet and the first delay time;

[0030] In response to an EGR valve opening greater than 0, the first time is the sum of the time required for the exhaust gas to flow from the particulate filter outlet to the mixing valve outlet under the current EGR valve opening obtained by calibration and the second delay time.

[0031] The first delay time is obtained by looking up the average value of the engine speed filter value within the first preset time from the first calibration table;

[0032] The second delay time is obtained from the second calibration table by using the average value of the engine speed filter value and the EGR valve opening within the first preset time period.

[0033] According to an embodiment of the present invention, the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods are preprocessed to obtain a time difference array, including:

[0034] Read the maximum and minimum values ​​of the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a first maximum value array and a first minimum value array;

[0035] Remove the first second preset number of elements from the first maximum value array and the first minimum value array, and remove the maximum value and the corresponding minimum value that are 0 to obtain the second maximum value array and the second minimum value array;

[0036] Based on the second maximum value array and the second minimum value array, we obtain the maximum value interval time array and the minimum value interval time array;

[0037] The method for obtaining the second preset quantity includes:

[0038] Based on the filtered value of the rotational speed, the second preset quantity is obtained by looking up the value in the third calibration table; the third calibration table records the mapping relationship between the range of filtered values ​​of the rotational speed and the second preset quantity.

[0039] According to an embodiment of the present invention, the periodic stability of the outlet pressure signal is determined based on the stability of the rotational speed change rate and the number of times the time difference array exceeds a dynamic threshold, including:

[0040] Using the rate of change of rotational speed and its filtered value, determine whether the rate of change of rotational speed is stable within the second preset time period;

[0041] If the speed change rate is unstable within the second preset time, the first number of times when the time difference is less than the first dynamic threshold is counted in the time difference array. When the first number is greater than the first fault count threshold, it is determined that there is a fault in the inlet pressure signal.

[0042] If the speed change rate is stable within the second preset time, the second number of times when the time difference is less than the second dynamic threshold is counted in the statistical time difference array. When the second number is greater than the second fault count threshold, it is determined that there is a fault in the inlet pressure signal.

[0043] The first dynamic threshold and the second dynamic threshold are determined at least based on the target EGR rate, the filtered value of the rotational speed, the EGR valve inlet temperature, the EGR valve inlet pressure, and the self-learning coefficient.

[0044] The first fault counting threshold and the second fault counting threshold are determined at least based on the ratio of the fresh air intake flow rate into the cylinder to the pressure at the outlet and inlet of the mixing valve and the self-learning coefficient.

[0045] According to an embodiment of the present invention, the method for calculating the first fault count threshold and the second fault count includes:

[0046] Obtain the first ratio of the average absolute value of the fresh air intake flow rate entering the cylinder under the condition of signal stability to the preset flow rate;

[0047] Obtain a second ratio between the average value of the mixing valve outlet pressure and the average value of the mixing valve inlet pressure under the condition of signal stability.

[0048] The calculation steps for the first fault counting threshold are as follows: the first base value is obtained by inputting the first ratio into the fourth or fifth calibration table; the second base value is obtained by inputting the second ratio into the sixth or seventh calibration table; the first base value, the second base value, and the first counting self-learning coefficient are multiplied together and rounded to determine the first fault counting threshold.

[0049] The fourth calibration table is used when the EGR valve is closed, and stores the corresponding first basic value indexed by the first ratio; the sixth calibration table is used when the EGR valve is closed, and stores the corresponding second basic value indexed by the second ratio; the fifth calibration table is used when the EGR valve is not closed, and stores the corresponding first basic value indexed by the first ratio; the seventh calibration table is used when the EGR valve is not closed, and stores the corresponding second basic value indexed by the second ratio.

[0050] The calculation steps for the second fault counting threshold are as follows: the third base value is obtained by inputting the first ratio into the eighth or ninth calibration table; the fourth base value is obtained by inputting the second ratio into the tenth or eleventh calibration table; the second fault counting threshold is determined by multiplying the third base value, the fourth base value, and the second counting self-learning coefficient and rounding down.

[0051] The eighth calibration table is used when the EGR valve is closed, and stores the corresponding third basic value indexed by the first ratio; the tenth calibration table is used when the EGR valve is closed, and stores the corresponding fourth basic value indexed by the second ratio; the ninth calibration table is used when the EGR valve is not closed, and stores the corresponding third basic value indexed by the first ratio; the eleventh calibration table is used when the EGR valve is not closed, and stores the corresponding fourth basic value indexed by the second ratio.

[0052] According to an embodiment of the present invention, the method further includes:

[0053] Determine if the active pressure fluctuation check step for the current driving cycle has malfunctioned;

[0054] If a fault occurs, determine whether the engine speed change rate has been unstable in the passive pressure periodic check step of the current driving cycle. If so, reduce the self-learning coefficient of the first dynamic threshold and reduce the first fault self-learning coefficient of EGR valve closure. If not, reduce the self-learning coefficient of the second dynamic threshold and reduce the first count self-learning coefficient of EGR valve not closed.

[0055] If no fault occurs, determine whether the engine speed change rate has been unstable during the passive pressure periodic check step of the current driving cycle. If so, increase the self-learning coefficient of the first dynamic threshold and increase the second fault self-learning coefficient of EGR valve closure. If not, increase the self-learning coefficient of the second dynamic threshold and increase the second count self-learning coefficient of EGR valve not being closed.

[0056] According to an embodiment of the present invention, determining whether the engine operating condition is an active steady-state condition using engine operating parameters and filter values ​​includes:

[0057] By using engine operating parameters and the difference between engine operating parameters and corresponding filter values, it can be determined whether the engine meets the signal stability conditions.

[0058] If the time for the engine to meet the signal stabilization condition exceeds the first preset time, the target EGR rate is unchanged when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the second EGR valve gas stabilization condition.

[0059] In response to the engine meeting the gas stability condition of the second EGR valve, the target EGR valve is controlled so that the target EGR rate remains unchanged when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the EGR valve opening stability condition.

[0060] If the engine meets the EGR valve opening stability condition, the engine operating condition is determined to be an active steady-state condition.

[0061] According to an embodiment of the present invention, determining whether the engine meets the gas stability condition of the second EGR valve includes:

[0062] Determine whether the time it takes for the engine to meet the gas stability condition of the second EGR valve exceeds the third preset time;

[0063] If so, the engine is determined to meet the gas stability conditions of the second EGR valve;

[0064] If not, the engine is determined not to meet the gas stability conditions of the second EGR valve, and the diagnostic process is terminated.

[0065] The gas stability conditions for the second EGR valve include:

[0066] Condition 6: The difference between the opening degree of the mixing valve and its filtered value is less than the first threshold, which is the product of the minimum value of the opening degree of the mixing valve and its filtered value and the first preset threshold coefficient;

[0067] Condition 7: The difference between the EGR valve inlet pressure and its filter value is less than the second threshold, which is the product of the minimum value of the inlet pressure and its filter value and the second preset threshold coefficient;

[0068] Condition 8: The EGR valve inlet temperature fluctuation is within the second preset range;

[0069] Condition 9: No EGR valve inlet pressure sensor circuit failure or EGR valve outlet pressure sensor circuit failure occurred.

[0070] According to an embodiment of the present invention, determining whether the engine meets the EGR valve opening stability condition includes:

[0071] Using the EGR valve opening degree and its filtered value, determine whether the EGR valve opening degree is stable within the fourth preset time period;

[0072] If so, the engine is determined to meet the EGR valve opening stability condition;

[0073] If not, the engine is determined not to meet the EGR valve opening stability condition, and the outlet pressure signal stability check is terminated.

[0074] The method for obtaining the fourth preset time includes: in response to the EGR valve opening being 0, the fourth preset time is the time required for calibrated fresh air to flow from the mixing valve outlet to the turbocharger inlet; in response to the EGR valve opening being greater than 0, the fourth preset time is the time required for calibrated exhaust gas to flow from the gasoline particulate filter outlet to the mixing valve outlet at the current EGR valve opening.

[0075] According to an embodiment of the present invention, the EGR valve outlet pressure within a fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array, including:

[0076] Read the maximum and minimum values ​​of the filtered EGR valve outlet pressure within the fourth preset number of sampling periods to obtain the first maximum value array and the first minimum value array;

[0077] Remove the first second preset number of elements from the first maximum value array and the first minimum value array, and remove the maximum value and the corresponding minimum value that are 0 to obtain the second maximum value array and the second minimum value array;

[0078] Divide the second maximum value array and the second minimum value array according to the fifth preset quantity to obtain the maximum value interval and the minimum value interval of the sixth preset quantity. Calculate the average value of each interval, remove the maximum value average value and the corresponding minimum value average value that are 0, and obtain the final maximum value array and the final minimum value array.

[0079] The mean array is obtained by averaging the corresponding elements of the final maximum value array and the final minimum value array.

[0080] According to an embodiment of the present invention, the stability of the outlet pressure signal fluctuation is determined by the number of times the outlet pressure array exceeds a dynamic threshold, based on the stability of the rotational speed change rate, including:

[0081] Using the rate of change of rotational speed and the filtered value of the rate of change of rotational speed, it is determined whether the rate of change of rotational speed is stable within the fifth preset time period;

[0082] If the speed change rate is unstable within the fifth preset time, the judgment is made based on the mean array in the outlet pressure array. The absolute value of the difference between adjacent elements in the mean array is greater than the third number of the third dynamic threshold. When the third number exceeds the third fault count threshold, the outlet pressure signal is determined to be unstable.

[0083] If the speed change rate is stable within the fifth preset time, the judgment is made based on the maximum value array and minimum value array in the outlet pressure array. The number of times the absolute value of the difference between adjacent elements in the maximum value array is greater than the fourth dynamic threshold, the number of times the absolute value of the difference between adjacent elements in the minimum value array is greater than the fifth dynamic threshold, and the number of times the absolute value of the difference between the corresponding elements of the maximum and minimum value arrays is greater than the sixth dynamic threshold are counted. When the fourth, fifth, or sixth count exceeds the fourth fault count threshold, the outlet pressure signal is determined to be unstable.

[0084] Among them, the third dynamic threshold, the fourth dynamic threshold, the fifth dynamic threshold and the sixth dynamic threshold are determined at least based on the target EGR rate, the filtered value of the rotational speed, the target EGR valve opening, the EGR valve inlet temperature, the EGR valve inlet pressure and the filtered value of the EGR valve inlet pressure.

[0085] The third and fourth fault count thresholds are determined at least based on the ratio of the fresh air intake flow rate into the cylinder to the pressure at the outlet and inlet of the mixing valve.

[0086] According to an embodiment of the present invention, the method for calculating the third dynamic threshold, the fourth dynamic threshold, the fifth dynamic threshold, and the sixth dynamic threshold includes:

[0087] The third dynamic threshold is obtained based on the first preset default threshold, the minimum absolute value of the difference between adjacent elements of the mean array, the first correction factor, and the second correction factor.

[0088] The fourth dynamic threshold is obtained based on the second preset default threshold, the minimum absolute value of the difference between adjacent elements of the maximum value array, the third correction factor, and the fourth correction factor.

[0089] The fifth dynamic threshold is obtained based on the second preset default threshold, the minimum value of the absolute value of the difference between adjacent elements of the minimum value array, the third correction factor, and the fourth correction factor;

[0090] The sixth dynamic threshold is obtained based on the second preset default threshold, the minimum value of the absolute value of the difference between the corresponding elements of the maximum and minimum value arrays, the third correction factor, and the fourth correction factor.

[0091] The first correction factor is calculated using a first preset value, a target EGR rate, and a calibration value; the second correction factor is calculated using a second preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure; the third correction factor is calculated using a third preset value, a target EGR rate, and a calibration value; and the fourth correction factor is calculated using a fourth preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure.

[0092] The calibration values ​​are obtained by querying the preset twelfth calibration table; the twelfth calibration table stores the corresponding calibration values, indexed by the filtered value of the rotational speed and the target EGR valve opening.

[0093] According to an embodiment of the present invention, the method for calculating the third fault count threshold and the fourth fault count includes:

[0094] Obtain the third ratio of the average absolute value of the fresh air intake flow rate entering the cylinder under stable signal conditions to the preset flow rate;

[0095] Obtain the fourth ratio of the average value of the mixing valve outlet pressure to the average value of the mixing valve inlet pressure under the condition of signal stability.

[0096] The calculation steps for the third fault count threshold are as follows: the fifth base value is obtained by inputting the third ratio into the thirteenth or fourteenth calibration table; the sixth base value is obtained by inputting the third ratio into the fifteenth or sixteenth calibration table; the fifth base value and the sixth base value are multiplied together and rounded to determine the third fault count threshold.

[0097] The thirteenth calibration table is used when the EGR valve is closed, and stores the corresponding third basic value indexed by the third ratio; the fifteenth calibration table is used when the EGR valve is closed, and stores the corresponding fourth basic value indexed by the fourth ratio; the fourteenth calibration table is used when the EGR valve is not closed, and stores the corresponding third basic value indexed by the third ratio; the sixteenth calibration table is used when the EGR valve is not closed, and stores the corresponding fourth basic value indexed by the fourth ratio.

[0098] The calculation steps for the second fault count threshold are as follows: the seventh base value is obtained by inputting the third ratio into the seventeenth or eighteenth calibration table; the eighth base value is obtained by inputting the fourth ratio into the nineteenth or twentieth calibration table; the third base value and the fourth base value are multiplied together and rounded to determine the second fault count threshold.

[0099] The seventeenth calibration table is used when the EGR valve is closed, and stores the corresponding seventh basic value indexed by the third ratio; the nineteenth calibration table is used when the EGR valve is closed, and stores the corresponding eighth basic value indexed by the fourth ratio; the eighteenth calibration table is used when the EGR valve is not closed, and stores the corresponding seventh basic value indexed by the third ratio; the twentieth calibration table is used when the EGR valve is not closed, and stores the corresponding eighth basic value indexed by the fourth ratio.

[0100] According to an embodiment of the present invention, the number of stable cycles of the engine speed change rate meets the requirements, including:

[0101] The number of driving cycles that enter the diagnosis of engine speed change rate not being in a stable state is not less than the fifth preset value, and the number of driving cycles that enter the diagnosis of engine speed change rate being in a stable state is 0.

[0102] The number of driving cycles that enter the diagnosis of engine speed change rate being in a stable state is not less than the sixth preset value, and the number of driving cycles that enter the diagnosis of engine speed change rate not being in a stable state is 0.

[0103] The number of driving cycles diagnosed when the engine speed change rate is in a stable state and the number of driving cycles diagnosed when the engine speed change rate is not in a stable state are both not 0, but the sum of the number of driving cycles diagnosed when the engine speed change rate is in a stable state and the number of driving cycles diagnosed when the engine speed change rate is not in a stable state is not less than the seventh preset value.

[0104] A second aspect of the present invention provides an anomaly diagnosis system for an engine system, which can be used to implement the above-described anomaly diagnosis method for an engine system, comprising:

[0105] The filtering module is used to perform first-order low-pass filtering on each engine operating parameter using the corresponding filtering coefficients to obtain the corresponding filtered value. The engine operating parameters include at least engine speed parameters and engine-related parameters. The filtering coefficients for each engine-related parameter are determined based on the stability of the engine speed parameters. The engine speed parameters include engine speed and rate of change of engine speed. The engine-related parameters include at least the EGR valve outlet pressure.

[0106] The passive pressure periodic verification module is used to respond to the engine operating condition being determined to be a passive steady-state condition by using engine operating parameters and filter values. It then preprocesses the filter values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a time difference array. The time difference array includes at least a maximum value interval time array and a minimum value interval time array of the EGR valve outlet pressure. Based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds the dynamic threshold.

[0107] The active pressure fluctuation verification module is used to determine whether the engine operating condition is an active steady-state condition in response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in the passive pressure periodic verification step of the third consecutive preset number of driving cycles, the outlet pressure signal is stable and the number of stable times of the engine speed change rate meets the requirements. In response to the engine operating condition being an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array. Based on the stability of the speed change rate, the stability of the outlet pressure signal fluctuation is determined by the number of times the outlet pressure array is greater than the dynamic threshold.

[0108] A third aspect of the present invention provides an electronic device comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors perform the above-described anomaly diagnosis method applied to an engine system.

[0109] A fourth aspect of the present invention also provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the above-described anomaly diagnosis method applied to an engine system.

[0110] The present invention provides an abnormal diagnosis method for engine systems. Through a detection process including a filtering step, a passive pressure periodic check step, and an active pressure fluctuation check step, the passive diagnosis step does not actively adjust engine parameters to avoid affecting the performance of the EGR system. The active diagnosis step is triggered only under highly stable operating conditions after the passive diagnosis has failed to detect the fault multiple times, and actively adjusts the engine parameters. This solves the technical problem that a single diagnosis mode may interfere with the normal control of the engine or have insufficient detection efficiency. It achieves efficient and accurate detection of periodic abnormal signals of EGR valve outlet pressure while minimizing interference with engine performance. Attached Figure Description

[0111] Figure 1 This is a schematic diagram of the engine system involved in the technical solution disclosed herein;

[0112] Figure 2 This is a flowchart illustrating an anomaly diagnosis method for an engine system provided in an embodiment of the present invention.

[0113] Figure 3 A flowchart of another anomaly diagnosis method applied to an engine system provided in this disclosure embodiment;

[0114] Figure 4 A structural block diagram of an anomaly diagnosis system for an engine system provided in an embodiment of the present invention;

[0115] Figure 5 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0116] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0117] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.

[0118] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0119] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0120] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0121] In the technical solution of this invention, the collection, storage, use, processing, transmission, provision, and disclosure of user personal information all comply with relevant laws and regulations and do not violate public order and good morals. The use of user data in this technical solution follows relevant national laws and regulations (e.g., the "Information Security Technology - Personal Information Security Specification"). For example: appropriate measures are taken for personal information access control; restrictions are imposed on the display of personal information; the purpose of using personal information does not exceed the scope of direct or reasonable association; and explicit identity targeting is eliminated when using personal information to avoid precisely locating a specific individual.

[0122] Figure 1 This is a schematic diagram of the engine system involved in the technical solution disclosed herein. Figure 1 As shown, an engine system generally includes an air filter 1; a mixing valve 2 connected to the air filter, configured to regulate the pressure at the outlet of the EGR valve 10, increasing the pressure difference across the EGR valve 10, with two airflow passages extending from the mixing valve 2; a compressor 3 connected to one of the airflow passages of the mixing valve 2; a throttle valve 4 connected to the compressor 3, wherein the throttle valve 4 has a boost temperature and pressure sensor at its inlet and an intake air temperature and pressure sensor at its outlet, and the throttle valve 4 body has a position sensor and an actuator; an engine 5 connected to the throttle valve 4, configured to compress fresh air for boosting; and a turbine 6 connected to the engine 5, configured to control the opening of the exhaust bypass valve. The following components are connected to the turbine 6: a catalyst 7; a particulate filter 8; an EGR cooler 9 installed on another airflow path of the mixing valve 2, configured to receive and cool the exhaust gas output from the particulate filter 8 to increase the exhaust gas flow rate; an EGR valve 10 connected at one end to the EGR cooler 9 and at the other end to the mixing valve 2, configured to control the exhaust gas flow rate entering the cylinder; a temperature sensor 11 installed between the EGR valve 10 and the EGR cooler 9, configured to detect the exhaust gas temperature entering the EGR valve 10; and a differential pressure sensor 12 connected to the EGR valve 10, configured to detect the pressure at the inlet and outlet of the EGR valve 10.

[0123] The gas pressure on both sides (inlet and outlet) of the EGR valve is a crucial input for EGR rate control, determining the accuracy of exhaust gas flow estimation and EGR valve opening control, thus affecting the precision of the EGR rate. Therefore, it is necessary to promptly check whether the EGR valve outlet gas pressure signal is normal to avoid affecting EGR rate control and causing adverse effects on engine performance.

[0124] This invention provides an anomaly diagnosis method for engine systems that improves the accuracy of verification. Figure 2 This is a flowchart illustrating an anomaly diagnosis method for an engine system provided by an embodiment of the present invention, as shown below. Figure 2As shown, this embodiment of the invention provides an anomaly diagnosis method applied to an engine system, including:

[0125] S1. For each engine operating parameter, a first-order low-pass filter is performed using the corresponding filter coefficient to obtain the corresponding filter value. The engine operating parameters include at least engine speed parameters and engine-related parameters. The filter coefficient for each engine-related parameter is determined based on the stability of the engine speed parameters. The engine speed parameters include engine speed and rate of change of engine speed. The engine-related parameters include at least the EGR valve outlet pressure.

[0126] The filter coefficients are dynamically adjusted according to the stability of the speed parameters, realizing adaptive optimization of filtering: when the speed is stable, the calibrated filter coefficients are normalized according to the speed to improve the accuracy of signal filtering; when the speed is unstable, the preset default coefficients are used to effectively filter out high-frequency noise in the parameter signal and retain the true signal change trend.

[0127] S2~S3, Passive Pressure Periodic Verification Steps: In response to determining that the engine operating condition is a passive steady-state condition using engine operating parameters and filter values, the filter values ​​of the EGR valve outlet pressure within the first preset number of sampling periods are preprocessed to obtain a time difference array; the time difference array includes at least the maximum value interval time array and the minimum value interval time array of the EGR valve outlet pressure; based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds the dynamic threshold; the pressure signal is observed using the time window generated during the natural operation of the engine without changing any control commands or interfering with engine performance or emissions.

[0128] By using steady-state operating conditions as a prerequisite for pressure signal verification, the normal fluctuations in pressure signals caused by dynamic changes in engine operating conditions (such as sudden changes in engine speed, sudden changes in throttle opening, and EGR valve switching status) are eliminated. This solves the problem of misjudgment of faults caused by failure to distinguish operating conditions, and greatly improves the accuracy and reliability of pressure signal verification.

[0129] S4~S6, Active Pressure Fluctuation Verification Steps: In response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in response to the determination that the outlet pressure signal is stable and the number of stable engine speed change rate steps meets the requirements in the passive pressure periodic verification steps of the third consecutive preset number of driving cycles, the engine operating parameters and filter values ​​are used to determine whether the engine operating condition is an active steady-state condition. If the engine operating condition is an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array. Based on the stability of the speed change rate, the number of times the outlet pressure array exceeds the dynamic threshold is used to determine the fluctuation stability of the outlet pressure signal. The target EGR rate is controlled to artificially eliminate sources of uncertainty, ensuring that changes in the pressure signal fully reflect its own state.

[0130] It should be noted that in both the passive pressure periodic verification step and the active pressure fluctuation verification step, a secondary filter can be performed before preprocessing. The secondary filter method is the same as that in the passive pressure periodic verification step.

[0131] In this embodiment, Step 1: If no fault is found during active diagnosis in the current driving cycle, passive diagnosis will not be entered in the next driving cycle; instead, active diagnosis will be entered directly, i.e., proceed to Step 3. Step 2: If a fault is found during active diagnosis in the current driving cycle, diagnosis will be stopped until the fault is resolved. Step 3: If active diagnosis is entered: Step 3.1: If a fault is found, diagnosis will be stopped until the fault is resolved, and passive diagnosis threshold update method one will be entered. Simultaneously, after the fault is resolved, passive diagnosis will be performed again, and a new judgment will be made based on the fault diagnosis result and the stable number of times the engine speed change rate has been determined. Step 3.2: If no fault is found, passive diagnosis threshold update method two will be entered, and passive diagnosis will be performed again in the next driving cycle, and a new judgment will be made based on the fault diagnosis result and the above three conditions.

[0132] Through the embodiments of this invention, the main focus is on verifying the normality of the EGR valve outlet pressure signal. Based on the EGR valve outlet pressure characteristics, and considering whether different EGR valves are closed or not, as well as engine speed fluctuations, EGR inlet pressure fault checks are made separately, thereby improving the accuracy of pressure fault verification and promptly preventing impacts on EGR rate control precision. If no fault is found through passive diagnosis, the EGR rate is actively adjusted for active diagnosis. Similarly, the differences in the maximum and minimum values ​​across different cycles are checked to determine if an outlet pressure stability fault has occurred, promptly preventing impacts on EGR rate control precision. Passive diagnosis does not interfere with normal engine control; active diagnosis improves fault detection efficiency and minimizes interference with normal engine performance control. Furthermore, during the diagnosis process, the passive diagnosis threshold is learned and updated based on the results of active diagnosis, improving diagnostic accuracy and speed.

[0133] Based on the above embodiments, the engine-related parameters include at least one of the following: intake air density into the cylinder, throttle opening, mixing valve opening, EGR valve opening, EGR valve inlet pressure, and EGR valve outlet pressure; the calculation method for the filter coefficients corresponding to the engine-related parameters includes:

[0134] The system determines whether the engine speed parameters are stable. If the engine speed parameters are stable, the current filter coefficient is calculated based on the preset calibration filter coefficient and the engine speed. The calibration filter coefficient is obtained through bench testing of an engine at a preset speed. If the engine speed parameters are unstable, the current filter coefficient is calculated based on the preset self-learning coefficient.

[0135] First, for the engine speed n and the rate of change of engine speed dn (which is obtained by dividing the difference between the engine speed n in the current sampling period and the engine speed in the previous sampling period by the sampling period), we can calculate the engine speed n and the rate of change of engine speed dn. ), Fresh air intake density into the cylinder Throttle opening Mixing valve opening EGR valve opening GPF export pressure EGR valve inlet gas pressure (referred to as EGR valve inlet pressure) And the EGR valve outlet gas pressure (referred to as EGR valve outlet pressure). The filtering process uses the same formula, where X can be the engine speed. Engine speed change rate Fresh air intake density entering the cylinder and throttle opening Mixing valve opening EGR valve opening GPF export pressure EGR valve inlet pressure and EGR valve outlet pressure Any one of them.

[0136]

[0137] in, Let X be the value of the Nth sampling period. The value of X after first-order low-pass filtering. The filtered X value is the value of the Nth sampling period. The filtered X value is the value after filtering in the (N-1)th sampling period, where N = 1, 2, 3, ... Equal to the 0th sampling period Sampling period In this example, it took 10ms. The filter coefficients are obtained as follows:

[0138] (1) Filtering coefficients for engine speed n The method for obtaining it is as follows: Default coefficient Take 0.05.

[0139] Furthermore, in The conditions are met continuously for a preset time. This indicates that the engine speed is in a stable state (with minimal speed fluctuations). The threshold coefficient is also included. In this example, we use 0.05. This example takes 0.1s.

[0140] (2) Filtering coefficient of engine speed change rate dn The method for obtaining it is as follows:

[0141] Default coefficient Take 0.05. The filter coefficients are learned correction coefficients, with an initial value of 0, which are continuously learned and updated, and can be saved after the vehicle is powered off.

[0142] Optionally, Adaptive online learning based on model reference. The ECU has a built-in reference model to predict the ideal characteristics of the filtered signal for the rate of change of engine speed (dn) under steady-state operating conditions. During actual operation, the system continuously compares the deviation between the filtered actual signal and the model's prediction. If a persistent and significant deviation is detected, the system will adjust online and slowly. This changes the actual effective filter coefficients. This allows the filtering effect to converge towards the ideal state. (Learned) The value will be saved for use on the next power-on, thus enabling long-term parameter adaptation and experience accumulation.

[0143] Optionally, This method, based on statistical characteristics, involves operating condition calibration and offline mapping. It is primarily performed during engine bench or vehicle calibration. Raw signal data of the filter (dn) is collected under numerous different typical steady-state operating conditions (e.g., different speeds and load combinations). By analyzing the statistical characteristics of the signal (e.g., standard deviation) and conducting repeated tests, a filter that optimizes the filtering effect is calibrated for each operating condition. Then, the corresponding value for each operating condition point is derived. Value. During actual vehicle operation, the ECU retrieves the corresponding value from a table based on real-time operating conditions. value.

[0144] Furthermore, in The conditions are met continuously for a preset time. This indicates that the engine speed change rate is in a stable state (the speed change rate fluctuates little). The threshold coefficient is also included. In this example, we use 0.05. This example takes 0.1s.

[0145] (3) Intake density of fresh air entering the cylinder Filter coefficients The method for obtaining it is as follows:

[0146] (3.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0147] This example The calibration speed is 1000 rpm. The purpose of this setting is for normalization; at different engine speeds, no special calibration is needed, only calibration of the 4-cylinder engine and the engine at 1000 rpm. This eliminates the need for individual bench calibration tests at every RPM, significantly reducing the workload and time cost of engine calibration, thereby reducing calibration testing work. The default coefficient for the fresh air intake density entering the cylinder is 1; in this example, it is set to 0.02.

[0148] (3.2) In other cases, , The default coefficient for the fresh air intake density entering the cylinder is two; in this example, it is set to 0.02.

[0149] (4) Throttle opening Filter coefficients The method for obtaining it is as follows:

[0150] (4.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0151] This example The calibration speed is 1000 rpm. The purpose of this setting, as mentioned above, is for normalization processing. Throttle opening The default coefficient is 1; in this example, it is set to 0.02.

[0152] (4.2) In other cases, , Throttle opening The default coefficient is two; in this example, it is set to 0.02.

[0153] (5) Mixing valve opening Filter coefficients The method for obtaining it is as follows:

[0154] (5.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0155] This example The calibration speed is 1000 rpm. The purpose of this setting, as mentioned above, is for normalization processing. For the opening degree of the mixing valve The default coefficient is 1; in this example, it is set to 0.02.

[0156] (5.2) In other cases, , For the opening degree of the mixing valve The default coefficient is two; in this example, it is set to 0.02.

[0157] (6) EGR valve opening Filter coefficients The method for obtaining it is as follows:

[0158] (6.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0159] This example The calibration speed is 1000 rpm. The purpose of this setting, as mentioned above, is for normalization processing. EGR valve opening The default coefficient is 1; in this example, it is set to 0.02.

[0160] (6.2) In other cases, , EGR valve opening The default coefficient is two; in this example, it is set to 0.02.

[0161] (7) EGR valve inlet pressure Filter coefficients The method for obtaining it is as follows:

[0162] (7.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0163] This example The calibration speed is 1000 rpm. The purpose of this setting, as mentioned above, is for normalization processing. The default coefficient for the EGR valve inlet pressure is 1; in this example, it is set to 0.2.

[0164] (7.2) Other situations, The default inlet pressure coefficient for the EGR valve is two. Take 0.2. The filtering coefficient should not be less than the filtering coefficient of engine speed, engine speed change rate, fresh air intake density entering the cylinder, throttle opening, and mixing valve opening. This is because engine speed, engine speed change rate, fresh air intake density entering the cylinder, throttle opening, and mixing valve opening are used as conditions for checking EGR pressure. These conditions require stable operating conditions, so it is necessary to ensure that the EGR pressure is in a stable state. Therefore, the filtering coefficient should be relatively small. However, the filtering coefficient of the EGR valve inlet pressure should not be too small, otherwise it may lead to an incorrect evaluation of whether the EGR pressure is normal.

[0165] (8) EGR valve outlet pressure Filter coefficients The method for obtaining it is as follows:

[0166] (8.1) If both the engine speed and the rate of change of engine speed are in a steady state, then:

[0167] This example The calibration speed is 1000 rpm. The purpose of this setting, as mentioned above, is for normalization processing. The default coefficient for the EGR valve outlet pressure is 1; in this example, it is set to 0.2.

[0168] (8.2) Other situations, The default inlet pressure coefficient for the EGR valve is two. Take 0.2. The filtering coefficient should not be less than the engine speed, the rate of change of engine speed, the intake density of fresh air entering the cylinder, the throttle opening, and the mixing valve opening, for the same reasons as above.

[0169] It should be noted that the method for obtaining the calibration filter coefficient through bench testing is as follows: Under a preset reference operating condition (such as engine speed stable at 1000 rpm, specific load), the original signal of the target parameter (such as intake air density) is collected. By analyzing the noise characteristics and dynamic response requirements of the signal, the filter coefficient in the first-order low-pass filter formula is repeatedly adjusted and tested until the filtered signal can achieve the best balance between effectively filtering out high-frequency noise and not excessively delaying the real change. The filter coefficient finally determined at this time is the calibration filter coefficient under the reference speed.

[0170] Through the embodiments of the present invention, the calculation method for dynamically switching the filter coefficient based on the stable state of the engine speed parameters enables the filtering process to adapt to different engine operating states:

[0171] When the engine speed is stable, the calibrated filter coefficients obtained from bench tests are used for normalization calculations. This fully utilizes the precise data from bench tests to ensure that the filter coefficients achieve an optimal balance between signal smoothness and response delay at different engine speeds, effectively filtering out high-frequency noise and preserving true parameter changes. When the engine speed is unstable, self-learning coefficients are used to calculate the filter coefficients. These self-learning coefficients continuously optimize based on the actual engine operating conditions, avoiding the problem of poor filtering performance under dynamic conditions with fixed coefficients, while also ensuring the basic effectiveness of the filter.

[0172] Based on the above embodiments, the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods are preprocessed to obtain a time difference array. Before this, the engine operating condition is determined using engine operating parameters and the filtered values. Specifically, this includes: determining whether the engine meets the signal stability condition using the engine operating parameters and the difference between the engine operating parameters and the corresponding filtered values; determining whether the engine meets the first EGR valve gas stability condition if the time for the engine to meet the signal stability condition exceeds a first preset time; and determining whether the engine meets the first EGR valve gas stability condition if the engine meets the first EGR valve gas stability condition.

[0173] The signal stability conditions specifically include:

[0174] (1) The engine is running.

[0175] (2) The engine speed is within a certain range, in this example it is between 600rpm and 5900rpm, and the engine speed enters a stable state after entering the EGR system pressure check.

[0176] (3) The intake density of fresh air entering the cylinder is within a certain range. In this example, it is between 200 mgpl and 3000 mgpl, and the intake density after the pressure check of the EGR system enters a stable state.

[0177] Specifically, in The conditions are met continuously for a preset time. This indicates that the intake air density is in a stable state (with minimal fluctuations). The threshold coefficient is also included. In this example, we use 0.05. This example takes 0.1s.

[0178] (4) Throttle opening It has entered a stable state.

[0179] Specifically, in The conditions are met continuously for a preset time. This indicates that the throttle opening is in a stable state (throttle fluctuation is small). The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.1s.

[0180] (5) The boost control closed loop state remains unchanged. That is, if the boost control closed loop state has been entered, the boost control closed loop state must be maintained; if the closed loop state has not been entered, the boost control closed loop state should not be entered.

[0181] (6) Target air-fuel ratio fluctuation, that is, the difference between the target air-fuel ratios of two adjacent sampling periods, is within a certain range, and in this example it is taken as ±0.1.

[0182] (7) The difference between the target air-fuel ratio and the actual air-fuel ratio fluctuates, that is, the difference between the target air-fuel ratio and the actual air-fuel ratio in two adjacent sampling periods. Within a certain range, this example takes ±0.1.

[0183] (8) The actual air-fuel ratio fluctuation, that is, the difference between the actual air-fuel ratios of two adjacent sampling periods, is within a certain range. In this example, it is taken as ±0.1.

[0184] (9) The engine coolant temperature is within a certain range (0℃ to 100℃ in this example), and the engine coolant temperature fluctuation after entering the EGR system pressure check is small, that is, the difference between the engine coolant temperatures of two adjacent sampling periods is small. In this example, ±2℃ is taken.

[0185] (10) The intake temperature is within a certain range (30℃ to 80℃ in this example), and the intake temperature fluctuation after entering the EGR system pressure check is small, that is, the difference between the intake temperatures of two adjacent sampling cycles is small. In this example, it is ±1.5℃.

[0186] (11) Ignition angle efficiency fluctuation, that is, the difference between the ignition angle efficiency of two adjacent sampling periods is small. In this example, it is ±0.1.

[0187] (12) No detonation occurred and no premature combustion occurred.

[0188] (13) The engine did not experience fuel cut-off.

[0189] (14) Both the oxygen sensor before the catalyst and the oxygen sensor after the catalyst have been activated by heating.

[0190] (15) Atmospheric pressure fluctuation, that is, the difference in atmospheric pressure between two adjacent sampling periods is small. In this example, it is ±0.5 kPa.

[0191] (16) No fire malfunction occurred.

[0192] (17) No EGR system pressure signal fault was detected during this vehicle driving cycle.

[0193] In the process, water temperature, air-fuel ratio, ignition efficiency, and knock ensure stable combustion; intake air temperature, throttle opening, and boost control mode ensure stable intake; activation of front and rear oxygen sensors, absence of misfires, and absence of related circuit faults ensure effective monitoring; stable atmospheric pressure and absence of historical faults within the driving cycle eliminate the influence of sudden environmental changes and residual faults; and engine speed and load are within reasonable ranges to ensure operation within the normal range. Only after all the above conditions are met, and the following signal stability condition is also met, can the EGR system pressure signal check be performed: all the above conditions exceed a preset time t0 (5 seconds in this example).

[0194] It should be noted that the 17 conditions can be divided into three categories and monitored in parallel using three subtasks:

[0195] Group A provides a quick check of Boolean data or data that changes rapidly, including engine operating status, speed / load range, sensor circuit status, knock / misfire warning, and fuel cut-off warning.

[0196] Group B, Medium-Speed ​​Checks: Simulated quantities with relatively slow changes, such as water temperature, intake air temperature, air-fuel ratio fluctuations, and atmospheric pressure fluctuations. For small fluctuations, the judgment requires calculating the difference, which can reduce the execution frequency.

[0197] Group C, slow check, or event-driven: oxygen sensor heating activation (usually completed some time after power-on, can be considered a one-time event), no historical faults within the driving cycle (can be considered a flag).

[0198] Through the embodiments of the present invention, it is first determined whether the engine meets a wide range of signal stability conditions and continues for a first preset time, and then it is further determined whether the first EGR valve gas stability condition is met. The steady-state operating condition is determined in detail at different levels, and the efficiency of condition judgment is improved. This prevents misjudgment that may easily occur when pressure diagnosis is performed when the engine is in transient operation or when related systems are unstable, and improves the accuracy of diagnosis.

[0199] After all 17 conditions are met and the signal stability condition is satisfied, passive diagnostics are performed first. No parameters are adjusted to avoid interfering with the EGR system's control and affecting EGR performance. If multiple passive diagnostics fail, active diagnostics are performed. That is, passive diagnostics needs to re-evaluate whether the engine meets the first EGR valve gas stability condition, including:

[0200] Determine whether the time it takes for the engine to meet the first EGR valve gas stability condition exceeds a first time; if yes, determine that the engine meets the first EGR valve gas stability condition; if no, determine that the engine does not meet the first EGR valve gas stability condition and exit the diagnostic process.

[0201] The first EGR valve gas stability conditions include:

[0202] Condition 1: The difference between the opening degree of the mixing valve and its filtered value is less than a first threshold. The first threshold is the product of the minimum value of the opening degree of the mixing valve and its filtered value and a first preset threshold coefficient, indicating that the opening degree of the mixing valve has entered a stable state. The conditions are met continuously for a preset time. This indicates that the mixing valve opening is in a stable state (the mixing valve fluctuates little). The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.1s.

[0203] Condition 2: The target EGR rate fluctuation (the difference between the target EGR rates of two adjacent sampling periods) is within a certain range, which is ±0.02 in this example.

[0204] Condition 3: The difference between the EGR valve opening and its filtered value is less than a second threshold, where the second threshold is the product of the minimum value of the EGR valve and its filtered value and a second preset threshold coefficient; that is, the EGR valve opening is in a stable state. The conditions are met continuously for a preset time. This indicates that the EGR valve opening is in a stable state (the EGR valve fluctuation is small). The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.1s.

[0205] Condition 4: The difference between the EGR valve inlet pressure and its filtered value is less than the third threshold, which is the product of the minimum value of the EGR valve inlet pressure and its filtered value and a third preset threshold coefficient; that is, it satisfies:

[0206] exist The conditions are met continuously for a preset time. This indicates that the EGR valve inlet pressure is in a stable state. The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.05s.

[0207] Condition 5: No EGR valve inlet pressure sensor circuit failure (including any circuit failure such as open circuit or short circuit) has occurred.

[0208] In this embodiment, the mixing valve opening, EGR valve opening, and target EGR rate ensure the stability of the system's control over the exhaust gas flow; the EGR valve inlet pressure ensures the stability of the pressure source. All of the above conditions exceeding a preset time t1 are referred to as the first EGR valve gas stability condition, i.e., the passive diagnostic condition is met.

[0209] Through embodiments of this disclosure, the stability of gas flow and control, which is directly related to the EGR valve outlet pressure, is precisely diagnosed.

[0210] Based on the above embodiments, the method for obtaining the first time t1 includes:

[0211] When the EGR valve opening is 0, the first time is the sum of the time required for fresh air to flow from the mixing valve outlet to the turbocharger inlet, as determined by calibration, and the first delay time. When the EGR valve opening is greater than 0, the first time is the sum of the time required for exhaust gas to flow from the particulate filter outlet to the mixing valve outlet at the current EGR valve opening, as determined by calibration, and the second delay time. The first delay time is obtained from the first calibration table by using the average value of the engine speed filter value within the first preset time. The second delay time is obtained from the second calibration table by using the average value of the engine speed filter value within the first preset time and the EGR valve opening.

[0212] In this embodiment, t1 is obtained as follows:

[0213] (1) If the EGR valve is closed, then t1 is the time it takes for exhaust gas to flow from the GPF outlet to the EGR valve inlet. It is obtained based on bench calibration. Bench calibration can fix the engine speed and the intake density of fresh air entering the cylinder, and close the EGR valve. By debugging various data sampling, the average time of fresh air flowing from the mixing valve outlet to the turbocharger inlet is obtained. The average time is then added to the first delay time N1× As t1. Where the sampling time is... In this example, 10ms is used, and N1 is the delay count. After calibration, the average value of the engine speed filter value and the average value of the fresh air intake density entering the cylinder under the above signal stabilization conditions are used to replace the fixed engine speed and fresh air intake density entering the cylinder during bench calibration to obtain t1. The specific calibration method for t1 is as follows: On the engine bench, pressure sensors are installed at the GPF outlet, mixing valve outlet, and EGR valve inlet. A time synchronization acquisition device is prepared. The engine speed and load (intake density) are fixed at a certain operating point. With the EGR valve closed, the time it takes for the pressure pulse to travel from the GPF outlet to the EGR valve inlet is captured through high-speed data acquisition. This is repeated multiple times, and the statistical average is taken. With the EGR valve open, similarly, with a fixed EGR valve opening, a pulse is injected or the rapid action of the EGR valve itself is used to measure the time it takes for the pulse to travel from the GPF outlet to the mixing valve outlet, obtaining the time at that (speed, load, EGR opening). The experiment is repeated at multiple engine speed, load, and EGR opening points to form a calibration table.

[0214] N1 is determined by the average value of the engine speed filter value under signal stabilization conditions. The larger the average value of the engine speed filter value, the higher N1 needs to be to ensure the accuracy of pressure signal verification and maintain stable operating conditions. This provides additional stabilization buffer time. The time average value obtained from bench calibration reflects the theoretical flow time of exhaust gas under specific fixed operating conditions. However, in actual operation, even if many signal stabilization conditions are met, the system may still experience minor airflow disturbances or pressure fluctuations. Therefore, a variable delay is proactively added to allow potential transient disturbances to subside.

[0215] Table 1 schematically illustrates the lookup table for N1. The first row represents the average value of the engine speed filter under stable signal conditions. The calibration method for N1 is as follows: On a test bench, the engine is operated at a specific operating point (speed, EGR opening) and all steady-state conditions are satisfied. Starting from the instant the conditions are met, the EGR inlet pressure signal is recorded at intervals of Δt. The time series of the pressure signal is analyzed to determine the time required from the start of recording until the signal statistical characteristics (such as standard deviation) fall into and remain within a very small interval. N1 is calculated, and by iterating through different speed and EGR opening operating points, the calibration tables for N1, N2, etc., can be filled in.

[0216] Table 1

[0217]

[0218] The larger value is selected after looking up the table, but it does not exceed the maximum and minimum values ​​in the table. That is, if the average value of the engine speed filter value under the signal stability condition is greater than 1000 rpm but less than 1400 rpm, then N1 is 8; if the average value of the engine speed filter value under the signal stability condition is not greater than 600 rpm, then N1 is 2; if the average value of the engine speed filter value under the signal stability condition is greater than 5700 rpm, then N1 is 20.

[0219] (2) If the EGR valve is not closed, then t1 is the time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet. It is obtained based on bench calibration. Bench calibration can fix the engine speed and the intake air density of the cylinder, as well as fix different EGR valve openings. By debugging various data sampling, the average time for the exhaust gas to flow from the GPF outlet to the mixing valve outlet is obtained. The average time is then added to the second delay time N2× As t1, N2 represents the second delay. In subsequent applications, the average value of the engine speed filter value, the average value of the fresh air intake density entering the cylinder, and the average value of the EGR valve opening, as well as the average value of the engine speed filter value and the fresh air intake density entering the cylinder, are used to replace the fixed engine speed and fresh air intake density calibrated on the test bench to obtain t1. N2 is determined by the average value of the engine speed filter value and the average value of the EGR valve opening in the signal stabilization conditions. The larger the average value of the engine speed filter value, the larger N2 needs to be set to ensure the accuracy of pressure signal verification in order to ensure stable operating conditions.

[0220] Table 2 schematically illustrates the lookup table for N2. The lookup method for N2 is the same as that for N1. The lookup method for N2 is as follows: First, before entering passive diagnosis and judging the gas stability condition of the first EGR valve, the average value of the engine speed filter value and the average value of the EGR valve opening during the period when the signal stability condition is continuously met are obtained as input parameters; then, using these two average values ​​as indexes, the two-dimensional calibration mapping table shown in Table 2 is looked up. When looking up the table, the larger value must be taken, but it must not exceed the maximum and minimum values ​​in the lookup table. For the average speed, if it is lower than the lowest speed (600 rpm) at the top of the table, it is looked up at 600 rpm; if it is higher than the highest speed (4500 rpm), it is looked up at 4500 rpm; if it is between two speed nodes, the column corresponding to the larger node is taken. Similarly, for the average EGR valve opening, if it is lower than the minimum opening (0%) in the table, it is looked up at 0%; if it is higher than the maximum opening (100%), it is looked up at 100%; if it is between two opening nodes, the row corresponding to the larger node is taken. Finally, the value located by the processed speed column and opening row is the required N2.

[0221] Table 2

[0222]

[0223] Through the embodiments of the present invention, different flow paths are used to calibrate the exhaust gas flow time depending on whether the EGR valve is closed, and a variable delay time related to engine speed and EGR valve opening is added on this basis, taking into account the differences in the physical path of exhaust gas transmission and providing an additional buffer for system stability.

[0224] Passive EGR stress verification can only be performed after all signal stability and passive diagnostic conditions are met. If the signal stability or passive diagnostic conditions are not met, or if the signal stability or passive diagnostic conditions are not met during the passive EGR stress verification process, the passive EGR stress verification will be stopped, indicating that the fault was not detected.

[0225] Based on the above embodiments, the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods are preprocessed to obtain a time difference array, including: reading the maximum and minimum values ​​of the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a first maximum value array and a first minimum value array; removing the first second preset number of elements from the first maximum value array and the first minimum value array, removing the maximum value and the corresponding minimum value that are 0, to obtain a second maximum value array and a second minimum value array; and obtaining a maximum value interval time array and a minimum value interval time array based on the second maximum value array and the second minimum value array.

[0226] The method for obtaining the second preset quantity includes:

[0227] Based on the filtered value of the rotational speed, the second preset quantity is obtained by looking up the value in the third calibration table; the third calibration table records the mapping relationship between the range of filtered values ​​of the rotational speed and the second preset quantity.

[0228] In this embodiment, the EGR outlet pressure after secondary filtering is read. The maximum and minimum values ​​are recorded as [pmax0, pmax1, ...] and [pmin0, pmin1, ...], respectively, where pmax0 is the first sampling period after all stability and diagnostic conditions are met (sampling period interval). The maximum value of the EGR outlet pressure read, pmax1 is the second sampling period after all stability and diagnostic conditions are met (sampling period interval). The maximum value of the EGR outlet pressure read is used, and so on. Where pmin0 is the first sampling period (sampling period interval) after all stability and diagnostic conditions are met. The minimum value of the EGR outlet pressure read, pmin1 is the second sampling period after all stability and diagnostic conditions are met (sampling period interval). The minimum value of the EGR outlet pressure read, and so on.

[0229] First, the maximum and minimum values ​​from the first M sampling periods need to be removed to avoid signal instability in the early stages of stable testing conditions, which could affect the accuracy of the pressure signal test. Table 3 schematically shows the lookup table for M. The first row represents the average value of the engine speed filter value under stable signal conditions. The method for obtaining M is to take the larger value after looking up the table, but not exceeding the maximum and minimum values ​​in the table. That is, if the average value of the engine speed filter value in the minimum value is greater than 1000 rpm but less than 1400 rpm, then M is 5; if the average value of the engine speed filter value in the minimum value is not greater than 600 rpm, then M is 2; if the average value of the engine speed filter value in the minimum value is greater than 5700 rpm, then M is 12.

[0230] Table 3

[0231]

[0232] After removing the maximum and minimum values ​​from M sampling periods, read the time difference array between adjacent maximum values. Time difference array between the minimum and adjacent minimum values The first element in the array and This is to remove the adjacent time difference obtained from the first sample after M samplings.

[0233] Through the embodiments of this disclosure, before calculating the time difference array, the values ​​of the M initial sampling periods determined according to the rotational speed are removed. At high rotational speeds, the airflow inertia is large, and the time required for stabilization is slightly longer. Therefore, the higher the rotational speed, the larger M is. This removes the initial data that the system may not be fully stable when the diagnostic conditions are just met, thus improving the data quality.

[0234] Based on the above embodiments, the periodic stability of the outlet pressure signal is determined by using the number of times the time difference array exceeds a dynamic threshold, according to the stability of the rotational speed change rate. This includes: using the rotational speed change rate and its filtered value to determine whether the rotational speed change rate is stable within a second preset time period; if the rotational speed change rate is unstable within the second preset time period, the first number of times the time difference array is less than the first dynamic threshold is counted, and if the first count is greater than the first fault count threshold, the inlet pressure signal is determined to have a fault; if the rotational speed change rate is stable within the second preset time period, the second number of times the time difference array is less than the second dynamic threshold is counted, and if the second count is greater than the second fault count threshold, the inlet pressure signal is determined to have a fault; wherein, the first dynamic threshold and the second dynamic threshold are determined at least based on the target EGR rate, the filtered value of the rotational speed, the EGR valve inlet temperature, the EGR valve inlet pressure, and the self-learning coefficient; the first fault count threshold and the second fault count threshold are determined at least based on the ratio of the fresh air intake flow rate entering the cylinder to the pressure at the outlet and inlet of the mixing valve and the self-learning coefficient.

[0235] In this embodiment, the specific components include:

[0236] (1) If the rate of change of engine speed is not in a steady state. If the time difference array or The number of times the value is less than the threshold is greater than the number of times CNT1 is counted.

[0237] threshold If the signal is positive, it indicates that a pressure signal fault has occurred; otherwise, it indicates that a fault has not occurred.

[0238] in The average target EGR rate under stable signal conditions. This represents the average value of the filtered engine speed under stable signal conditions. This represents the average inlet temperature of the EGR valve under stable signal conditions. This represents the average value of the EGR valve inlet pressure filter under stability conditions. The default EGR valve inlet pressure is set to 250 kPa in this example. The default EGR valve inlet temperature is 550℃ in this example. The default speed is 100 rpm in this example. , , The values ​​were taken as 8.4 (ms), 1.5 (ms), and 15 (ms) respectively, at different... The following data is obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors.

[0239] Learning coefficient 1 This is a learning value used for passively diagnosing when the engine speed change rate is not in an stable state. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , , The learning value under the same conditions.

[0240] (2) If the rate of change of engine speed is in a steady state. If the time difference array or The number of times the value is less than the threshold is greater than CNT2.

[0241] threshold If the signal is positive, it indicates that a pressure signal fault has occurred; otherwise, it indicates that a fault has not occurred.

[0242] in , , Each not greater than , , The values ​​are 8.2 (ms), 1.1 (ms), and 15 (ms), in different... The following data is obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors.

[0243] Learning coefficient 2 This is a learning value used for passively diagnosing the engine speed change rate in a stable state. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , The learning value under the same conditions.

[0244] Through embodiments of the present invention, different dynamic thresholds and fault counting thresholds are used to determine faults based on whether the engine speed change rate is stable, thus solving the problem of varying tolerances to pressure fluctuations at different dynamic stages of the engine. When dn is unstable, the intake and exhaust flow rates change rapidly, resulting in significant fluctuations in the EGR valve outlet pressure. When dn is stable, the engine background fluctuations are small. Therefore, setting different thresholds improves diagnostic accuracy.

[0245] Based on the above embodiments, the calculation method for the first fault count threshold and the second fault count includes:

[0246] The calculation steps for the first fault count threshold are as follows: First, obtain the absolute value of the average fresh air intake flow rate into the cylinder under stable signal conditions, and a first ratio to the preset flow rate; second, obtain the average value of the mixing valve outlet pressure to the average value of the mixing valve inlet pressure under stable signal conditions; third, calculate the first fault count threshold by inputting the first ratio into the fourth or fifth calibration table to obtain the first base value; fourth, obtain the second base value by inputting the second ratio into the sixth or seventh calibration table; fifth, obtain the first base value by multiplying the first base value, the second base value, and the first self-learning coefficient, and rounding down to determine the first fault count threshold. The fourth calibration table stores the corresponding first base value using the first ratio as an index when the EGR valve is closed; the sixth calibration table stores the corresponding second base value using the second ratio as an index when the EGR valve is closed; the fifth calibration table stores the corresponding first base value using the first ratio as an index when the EGR valve is not closed; and the seventh calibration table stores the corresponding second base value using the second ratio as an index when the EGR valve is not closed.

[0247] The calculation steps for the second fault counting threshold are as follows: A third base value is obtained by inputting the first ratio into the eighth or ninth calibration table; a fourth base value is obtained by inputting the second ratio into the tenth or eleventh calibration table; the third base value, the fourth base value, and the second counting self-learning coefficient are multiplied and rounded to determine the second fault counting threshold. Specifically, the eighth calibration table stores the corresponding third base value using the first ratio as an index when the EGR valve is closed; the tenth calibration table stores the corresponding fourth base value using the second ratio as an index when the EGR valve is closed; the ninth calibration table stores the corresponding third base value using the first ratio as an index when the EGR valve is not closed; and the eleventh calibration table stores the corresponding fourth base value using the second ratio as an index when the EGR valve is not closed.

[0248] The first fault count threshold, CNT1, is obtained as follows:

[0249] (1) If the EGR valve is closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (This example uses a ratio of 10 g / s) And the correction factor determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. The decision is made jointly, whereby the average outlet pressure of the mixing valve under signal stability conditions represents the outlet pressure of the mixing valve obtained when checking whether the signal stability conditions are met. Once the signal stability conditions are verified, the average outlet pressure of the mixing valve during the verification process is calculated and stored, i.e., CNT1 = V1. The values ​​are rounded to the nearest integer. The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system. Therefore, the larger the threshold coefficient CNT1 = V1, the more likely the flow disturbance will have to cause problems. The calibration tables are shown in Tables 4 and 5.

[0250] Table 4

[0251]

[0252] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0253] Table 5

[0254]

[0255] V1 learning coefficient 1 This is the CNT1 learning value for passively diagnosing when the engine speed change rate is not in an stable state and the EGR valve is closed. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , , , , The learning value under the same conditions.

[0256] (2) If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (In this example, 10 g / s is used) The correction factor is determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It is jointly determined that CNT1=V2 is The result is obtained by rounding to the nearest integer, CNT1 = V2 (V2 is not less than V1). The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system; therefore, the larger the threshold coefficient 2 should be to avoid the impact of flow disturbance. The calibration tables are shown in Tables 6 and 7.

[0257] Table 6

[0258]

[0259] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0260] Table 7

[0261]

[0262] V2 learning coefficient This is the CNT1 learning value for passively diagnosing when the engine speed change rate is not in an stable state and the EGR valve is not closed. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , , , , The learning value under the same conditions.

[0263] If the stability condition is not met when the EGR valve switches between closed and open states, then the pressure signal verification will be terminated.

[0264] The second fault count threshold CNT2 is obtained as follows:

[0265] (1) If the EGR valve is closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (This example uses a ratio of 10 g / s) And the correction factor determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It is jointly determined that CNT2 = V3 (V3 is not greater than V1). The result is obtained by rounding to the nearest integer (V3 is not greater than V1). The larger the absolute value of the intake air flow, the greater the flow disturbance in the exhaust system may be. Therefore, the threshold coefficient CNT2 = V3 should be larger to avoid the influence caused by flow disturbance. The calibration tables are shown in Tables 5 and 6.

[0266] Table 8

[0267]

[0268] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0269] Table 9

[0270]

[0271] V3 Learning Factor This is the V3 learning value for passively diagnosing when the engine speed change rate is in a stable state and the EGR valve is closed. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , , , , The learning value under the same conditions.

[0272] (2) If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (In this example, 10 g / s is used) The correction factor is determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It is jointly determined that CNT2=V4 is The values ​​are rounded to the nearest integer, resulting in CNT2 = V4 (V4 is not greater than V2), to avoid the impact of flow disturbances. The larger the absolute value of the intake flow rate, the greater the potential flow disturbance in the exhaust system, and thus the larger the threshold coefficient 2, to avoid the impact of flow disturbances. The calibration tables are shown in Tables 7 and 8.

[0273] Table 10

[0274]

[0275] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0276] Table 11

[0277]

[0278] If the stability condition is not met when the EGR valve switches between closed and open states, then the pressure signal verification will be terminated.

[0279] V4 learning factor This is the V4 learning value for passively diagnosing when the engine speed change rate is in a stable state and the EGR valve is not closed. Its default value is 0, and it can be continuously self-learned and updated. After the update, it will be saved immediately. Only update the corresponding working condition each time (i.e.) , , , , , The learning value under the same conditions.

[0280] Through the embodiments of this disclosure, the fault counting threshold can simultaneously respond to gas flow disturbances caused by changes in engine intake airflow and the throttling effect of the mixing valve. The higher the intake airflow and the higher the mixing valve pressure ratio, the higher the threshold will be. This effectively avoids the problem of normal pressure signal fluctuations caused by exhaust system flow disturbances and poor mixing valve throttling effect being misjudged as faults, and achieves dynamic adaptive optimization of the fault counting threshold. At the same time, dedicated calibration tables are configured for the two states of EGR valve closed and open, so that the threshold calculation can accurately match the gas flow characteristics of the EGR system under different operating conditions. When the EGR valve is not closed, the threshold is not less than that in the closed state, which is close to the actual operating condition where the pressure signal fluctuates more during exhaust gas recirculation.

[0281] Based on the above embodiments, the number of stable cycles of the engine speed change rate meets the requirements, including:

[0282] (1) Number of driving cycles in which the engine speed change rate is not in a stable state for diagnosis The number of driving cycles that are not less than the fifth preset value (3 in this example) and enter the diagnostic process for a stable engine speed change rate is not less than the fifth preset value. It is 0.

[0283] Or, (2) the number of driving cycles in which the engine speed change rate is in a stable state for diagnosis. The number of driving cycles required for diagnosis is not less than the sixth preset value (2 in this example) and the engine speed change rate is not in a stable state. =0;

[0284] Or, (3) the number of driving cycles for diagnosing when the engine speed change rate is in a stable state. The number of driving cycles used to diagnose when the engine speed change rate is not in a stable state. The number of driving cycles for diagnosis is not zero, but the rate of change of engine speed is in a stable state. Number of driving cycles for diagnosing engine speed change rate not being in a stable state The sum is not less than the seventh preset value (3 in this example).

[0285] It should be noted that if at least one of the above three situations occurs, active diagnosis will be initiated in this driving cycle, and... and All values ​​are set to 0. If, during a single driving cycle, the engine speed change rate repeatedly enters a stable state diagnostic, then... Add only 1; if during a single driving cycle, multiple diagnostics are initiated regarding the engine speed rate of change not being stable, then... Add only 1; if during a single driving cycle, the system enters both the steady-state engine speed change rate diagnosis and the unstable engine speed change rate diagnosis, then... and Add 1 to each.

[0286] Through embodiments of the present invention, different operating conditions are distinguished, and different trigger thresholds are set to limit the fault-free conditions for the first entry into active diagnosis into passive diagnosis. The requirement for the engine speed change rate to be in an unstable state is greater than that for the engine speed change rate to be in a stable state. If the two are mixed and more unstable, a higher number of attempts are required.

[0287] Based on the above embodiments, the method further includes:

[0288] Determine if the active pressure fluctuation check step for the current driving cycle has malfunctioned;

[0289] If a fault occurs, determine whether the engine speed change rate has been unstable in the passive pressure periodic check step of the current driving cycle. If so, reduce the self-learning coefficient of the first dynamic threshold and reduce the first fault self-learning coefficient of EGR valve closure. If not, reduce the self-learning coefficient of the second dynamic threshold and reduce the first count self-learning coefficient of EGR valve not closed.

[0290] If no fault occurs, determine whether the engine speed change rate has been unstable during the passive pressure periodic check step of the current driving cycle. If so, increase the self-learning coefficient of the first dynamic threshold and increase the second fault self-learning coefficient of EGR valve closure. If not, increase the self-learning coefficient of the second dynamic threshold and increase the second count self-learning coefficient of EGR valve not being closed.

[0291] The update method for passive diagnostic threshold update method one is as follows:

[0292] During the most recent passive diagnostic process prior to active diagnostics, if the engine speed change rate becomes unstable during the passive diagnostic process, then the corresponding operating condition (i.e., ...) will be updated. , , Learning values ​​under the same conditions Furthermore, if the EGR valve is closed, then update. If the EGR valve is not closed, update. .

[0293] If the engine speed change rate enters a stable state during the passive diagnostic process, then update the corresponding operating condition (i.e., , , Learning values ​​under the same conditions Furthermore, if the EGR valve is closed, then update. If the EGR valve is not closed, update. .

[0294] Once the update is complete, the situation of the most recent passive diagnosis will be assessed again in the next active diagnosis, and an update will be performed according to the specific circumstances.

[0295] and , , , , This is the learning value corresponding to the last learning update, with a default value of 0.

[0296] The update method for the passive diagnostic threshold update method two is as follows:

[0297] During the most recent passive diagnostic process prior to active diagnostics, if the engine speed change rate becomes unstable during the passive diagnostic process, then the corresponding operating condition (i.e., ...) will be updated. , , Learning values ​​under the same conditions Furthermore, if the EGR valve is closed, then update. If the EGR valve is not closed, update. .

[0298] If the engine speed change rate enters a stable state during the passive diagnostic process, then update the corresponding operating condition (i.e., , , Learning values ​​under the same conditions Furthermore, if the EGR valve is closed, then update. If the EGR valve is not closed, update. .

[0299] Once the update is complete, the situation of the most recent passive diagnosis will be assessed again in the next active diagnosis, and an update will be performed according to the specific circumstances.

[0300] It should be noted that upper and lower limits (e.g., ±0.3) should be set for the learning coefficients. Optionally, a slow decay mechanism can also be considered. For example, at regular intervals or after a certain number of driving cycles, all learning coefficients are multiplied by a factor slightly less than 1 (e.g., 0.995), causing them to slowly regress to 0. This prevents the learning values ​​from becoming fixed due to long-term operation under certain special conditions and maintains the system's adaptability to new operating conditions.

[0301] In the embodiments of this disclosure, if active diagnosis detects a fault but passive diagnosis fails to do so, it indicates that the threshold for passive diagnosis is set too loosely, leading to missed detections. Therefore, the corresponding learning coefficient is lowered. If active diagnosis fails to detect a fault, it indicates that the threshold for passive diagnosis may have a risk of false alarms. Therefore, the learning coefficient is increased. By updating the self-learning coefficient on which the dynamic threshold of passive diagnosis depends based on the results of active diagnosis and the stability of the rotational speed change rate during the corresponding passive diagnosis phase, the diagnostic parameters are optimized.

[0302] Based on the above embodiments, the engine operating parameters and filter values ​​are used to determine whether the engine operating condition is an active steady-state condition, including:

[0303] Using engine operating parameters and the difference between engine operating parameters and corresponding filter values, it is determined whether the engine meets the signal stability condition. If the time for the engine to meet the signal stability condition exceeds a first preset time, the target EGR rate is controlled to remain unchanged at the target EGR rate when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the second EGR valve gas stability condition. If the engine meets the second EGR valve gas stability condition, the target EGR valve is controlled to remain unchanged at the target EGR rate when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the EGR valve opening stability condition. If the engine meets the EGR valve opening stability condition, the engine operating condition is determined to be an active steady-state operating condition.

[0304] Specifically, determining whether the engine meets the gas stability conditions of the second EGR valve includes:

[0305] Determine whether the time it takes for the engine to meet the second EGR valve gas stability condition exceeds the third preset time; if yes, determine that the engine meets the second EGR valve gas stability condition; if no, determine that the engine does not meet the second EGR valve gas stability condition and exit the diagnostic process.

[0306] The gas stability conditions for the second EGR valve include:

[0307] Condition 6: The difference between the opening degree of the mixing valve and its filtered value is less than the first threshold, which is the product of the minimum value of the opening degree of the mixing valve and its filtered value and the first preset threshold coefficient;

[0308] Condition 7: The difference between the EGR valve inlet pressure and its filter value is less than the second threshold, which is the product of the minimum value of the inlet pressure and its filter value and the second preset threshold coefficient;

[0309] Condition 8: The EGR valve inlet temperature fluctuation is within the second preset range;

[0310] Condition 9: No EGR valve inlet pressure sensor circuit failure or EGR valve outlet pressure sensor circuit failure occurred.

[0311] Specifically, determining whether the engine meets the EGR valve opening stability condition includes: using the EGR valve opening and its filtered value to determine whether the EGR valve opening is stable within a fourth preset time period; if yes, the engine is determined to meet the EGR valve opening stability condition; if no, the engine is determined not to meet the EGR valve opening stability condition, and the outlet pressure signal stability check is exited.

[0312] The method for obtaining the fourth preset time includes: in response to the EGR valve opening being 0, the fourth preset time is the time required for calibrated fresh air to flow from the mixing valve outlet to the turbocharger inlet; in response to the EGR valve opening being greater than 0, the fourth preset time is the time required for calibrated exhaust gas to flow from the gasoline particulate filter outlet to the mixing valve outlet at the current EGR valve opening.

[0313] The gas stabilization conditions for the second EGR valve specifically include:

[0314] (1) Mixing valve opening Reaching a stable state:

[0315] exist The conditions are met continuously for a preset time. This indicates that the mixing valve opening is in a stable state (the mixing valve fluctuates little). The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.1s.

[0316] (2) Read the target EGR rate at the first sampling period when entering the diagnostic condition, and actively control the target EGR rate. Fixed and unchanging.

[0317] (3) The inlet pressure fluctuation of the EGR valve is small. That is, it satisfies:

[0318] exist The conditions are met continuously for a preset time. This indicates that the EGR valve inlet pressure is in a stable state. The threshold coefficient is also mentioned. In this example, the value is 0.01. This example takes 0.05s.

[0319] (4) The EGR valve inlet temperature fluctuates, that is, the difference between the EGR valve inlet temperature in two adjacent sampling periods is small. In this example, it is ±3℃.

[0320] (5) No EGR valve inlet pressure sensor circuit failure occurred, including any circuit failure such as open circuit or short circuit.

[0321] (6) No EGR valve outlet pressure sensor circuit failure occurred, including any circuit failure such as open circuit or short circuit.

[0322] After all the above EGR valve gas stability conditions have been met for more than t2 (0.5s in this example), the EGR valve opening stability condition is checked. The EGR valve opening stability conditions specifically include:

[0323] The EGR valve opening stability conditions specifically include:

[0324] After all the gas stability conditions of the EGR valve are met, the average value of the target EGR valve opening over time t3 is read. t3 time take Where C1 is 0.2s, This represents the average engine speed after filtering during the minimum process. The target EGR valve opening is forcibly fixed at [value]. The process is kept constant and maintained at t4. If the EGR valve opening is not stable within t4 (the determination of whether the EGR valve opening is stable is as described above), the diagnosis is terminated. If the EGR valve opening is stable within t4, the EGR valve opening stability condition is met.

[0325] The t4 value precisely covers the gas flow delay time, ensuring sufficient time for obtaining reliable signal data to verify the opening stability, avoiding misjudgments due to insufficient time, while also preventing excessive time from increasing the computational load on the engine control system. The t4 value is obtained as follows:

[0326] (1) If the EGR valve is closed, then t4 is the time it takes for fresh air to flow from the outlet of the mixing valve to the inlet of the turbocharger. It is obtained by bench calibration. Bench calibration can fix the engine speed and the intake density of fresh air entering the cylinder, and close the EGR valve. The average time it takes for fresh air to flow from the outlet of the mixing valve to the inlet of the turbocharger is obtained by debugging various data sampling.

[0327] (2) If the EGR valve is not closed, then t4 is the time it takes for the exhaust gas to flow from the GPF particulate filter outlet to the mixing valve outlet. It is obtained by bench calibration. Bench calibration can fix the engine speed and the fresh air intake density entering the cylinder, as well as fix different EGR valve openings. The average time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet is obtained by debugging various data sampling.

[0328] Through embodiments of this invention, a three-tiered judgment system—signal stability condition, EGR valve gas stability condition, and EGR valve opening stability condition—focuses on the core operating parameters of the EGR system. It gradually narrows the judgment from overall engine operating condition stability to the local operating state stability of the EGR valve, ensuring the rigor of the active steady-state condition determination. This ensures that the final determined steady-state condition truly reflects the stable operating state of the EGR system after parameter control. The signal stability condition covers 17 core parameters, including engine speed, intake air density, valve opening, air-fuel ratio, temperature, pressure, and fault status. Comprehensive verification is performed from multiple dimensions, including engine operating status, parameter range, parameter fluctuations, and fault diagnosis, ensuring the engine is in a stable operating state. In the second and third levels of condition determination, the target EGR rate and target EGR valve opening are actively and strictly controlled to remain constant, eliminating normal fluctuations in the outlet pressure signal caused by the EGR system actively changing the valve opening to adjust the EGR rate. Existing technologies do not strictly control the EGR rate and valve opening, leading to pressure signal fluctuations during the system's active adjustment process being included in the verification scope, which can easily cause misjudgments.

[0329] The EGR outlet pressure stability check can only be performed after all signal stability conditions, EGR valve gas stability conditions, and EGR valve opening stability conditions are simultaneously met. If any of the signal stability conditions, EGR valve gas stability conditions, or EGR valve opening stability conditions are not met, or if any of these conditions suddenly become unmet during the EGR outlet pressure stability check, the active EGR outlet pressure check will be stopped, and this will be indicated as a fault not being detected.

[0330] Based on the above embodiments, the EGR valve outlet pressure within a fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array, including:

[0331] Read the maximum and minimum values ​​of the filtered EGR valve outlet pressure within the fourth preset number of sampling periods to obtain the first maximum value array and the first minimum value array; remove the first second preset number of elements from the first maximum value array and the first minimum value array, and remove the maximum value and the corresponding minimum value that are 0 to obtain the second maximum value array and the second minimum value array; divide the second maximum value array and the second minimum value array according to the fifth preset number to obtain the sixth preset number of maximum value intervals and the sixth preset number of minimum value intervals, calculate the average value of each interval, remove the average value of the maximum value and the corresponding average value of the minimum value that are 0 to obtain the final maximum value array and the final minimum value array; calculate the average value of the corresponding elements of the final maximum value array and the final minimum value array to obtain the mean value array.

[0332] In this embodiment, similar to passive diagnostics, the filtered EGR outlet pressure is read within the sampling period. The maximum and minimum values ​​are calculated, and the maximum and minimum values ​​of the previous M sampling periods are removed.

[0333] After removing the maximum and minimum values ​​from M sampling periods, the average of the maximum and minimum values ​​in M1 is calculated according to the interval division M1 (50 in this example), forming a maximum value array [pmaxAvg0, pmaxAvg1,…] and a minimum value array [pminAvg0, pmaxAvg1,…]. In particular, if any element pmaxAvgQ (Q=0,1,2,3…) in the maximum value array or any original pmaxAvgR (R=0,1,2,3…) in the maximum value array is equal to 0, then the maximum and minimum values ​​corresponding to element Q, as well as the maximum and minimum values ​​corresponding to element R, are removed, and a new array is formed. The stability of the outlet pressure signal is checked on the new array.

[0334] Through embodiments of the present invention, by removing the first M initial unstable elements and invalid elements with values ​​of 0, the interference of abnormal data on the array is eliminated, ensuring the validity and reliability of the array data. Dividing the array into intervals according to M1 and calculating the interval average effectively smooths out random small fluctuations in the pressure signal. After smoothing, the array data can be more focused on significant fluctuations caused by faults. Simultaneously, three types of outlet pressure arrays—maximum value array, minimum value array, and mean value array—are constructed to reflect the upper limit fluctuation, lower limit fluctuation, and average level fluctuation of the pressure signal, respectively.

[0335] Based on the above embodiments, the stability of the outlet pressure signal fluctuation is determined by using the number of times the outlet pressure array exceeds the dynamic threshold, according to the stability of the rotational speed change rate. This includes: using the rotational speed change rate and its filtered value to determine whether the rotational speed change rate is stable within a fifth preset time period; if the rotational speed change rate is unstable within the fifth preset time period, a determination is made based on the mean array in the outlet pressure array, counting the third number of times the absolute value of the difference between adjacent elements in the mean array exceeds the third dynamic threshold, and determining that the outlet pressure signal is unstable when the third number exceeds the third fault count threshold; if the rotational speed change rate is stable within the fifth preset time period, a determination is made based on the maximum and minimum value arrays in the outlet pressure array, counting the absolute value of the difference between adjacent elements in the maximum value array. The outlet pressure signal is determined to be unstable when the fourth number of times the difference between adjacent elements in the minimum value array exceeds the fourth dynamic threshold, the fifth number of times the absolute value of the difference between the corresponding elements in the maximum and minimum value arrays exceeds the sixth dynamic threshold, and the sixth number of times the absolute value of the difference between the corresponding elements in the maximum and minimum value arrays exceeds the sixth dynamic threshold. The third, fourth, fifth, and sixth dynamic thresholds are determined at least based on the filtered values ​​of the target EGR rate, engine speed, target EGR valve opening, EGR valve inlet temperature, EGR valve inlet pressure, and the filtered value of the EGR valve inlet pressure. The third and fourth fault count thresholds are determined at least based on the ratio of the fresh air intake flow rate into the cylinder to the pressure ratio at the outlet and inlet of the mixing valve.

[0336] Based on the above embodiments, the calculation methods for the third dynamic threshold, the fourth dynamic threshold, the fifth dynamic threshold, and the sixth dynamic threshold include:

[0337] A third dynamic threshold is obtained based on the first preset default threshold, the minimum absolute value of the difference between adjacent elements in the mean array, the first correction factor, and the second correction factor; a fourth dynamic threshold is obtained based on the second preset default threshold, the minimum absolute value of the difference between adjacent elements in the maximum array, the third correction factor, and the fourth correction factor; a fifth dynamic threshold is obtained based on the second preset default threshold, the minimum absolute value of the difference between adjacent elements in the minimum array, the third correction factor, and the fourth correction factor; and a sixth dynamic threshold is obtained based on the second preset default threshold, the minimum absolute value of the difference between corresponding elements in the maximum and minimum arrays, the third correction factor, and the fourth correction factor.

[0338] The first correction factor is calculated using a first preset value, a target EGR rate, and a calibration value; the second correction factor is calculated using a second preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure; the third correction factor is calculated using a third preset value, a target EGR rate, and a calibration value; and the fourth correction factor is calculated using a fourth preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure.

[0339] The calibration values ​​are obtained by querying the preset twelfth calibration table; the twelfth calibration table stores the corresponding calibration values, indexed by the filtered value of the rotational speed and the target EGR valve opening.

[0340] (1) If the rate of change of engine speed is not in a stable state. Take the maximum value and minimum value of each element position of the maximum value array [pmaxAvg0,pmaxAvg1,...] and the minimum value array [pminAvg0,pmaxAvg1,...] and average them again to form [pAvg0,pAvg1,...].

[0341] The element i = 0, 1, 2, 3… If the above formula is satisfied more than a preset number of times - CNT3, it indicates that a fault has been detected in the stability check of the outlet pressure signal; otherwise, it indicates that no fault has occurred.

[0342]

[0343] The default threshold is set to 0.1 in this example. The target EGR rate is the gas stability condition for the EGR valve. The target EGR valve opening is the average value over time t3, which is the EGR valve opening stability condition. This represents the average value of the filtered engine speed under stable signal conditions. This represents the average inlet temperature of the EGR valve under stable signal conditions. The default EGR valve inlet temperature is 550℃ in this example. The default speed is 1000 rpm in this example. The actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i; The filtered value of the actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i.

[0344] It is the first correction factor.

[0345] This is the second correction factor.

[0346] For element i, within the M1 sampling interval Maximum value.

[0347] , The values ​​were 0.03 and 0.045 respectively, in different... Rotation speed The EGR valve opening is obtained based on the fitting data from both faulty and non-faulty pressure sensors. (Preset)

[0348] Where the correction coefficient and , Based on the results determined by faulty and non-faulty pressure sensors, and benchmarked against both faulty and non-faulty pressure sensors, the three-standard-deviation principle is used to determine the... , and correction factor one ,in , The values ​​are 0.03 and 0.045 respectively.

[0349] (2) If the engine speed change rate is in a steady state, the maximum value array [pmaxAvg0, pmaxAvg1, ...] and the minimum value array [pminAvg0, pmaxAvg1, ...] satisfy the following:

[0350] The number of times i=0,1,2,3… exceeds the preset number of times CNT4.

[0351] or, The number of times i=0,1,2,3… exceeds the preset number of times CNT4.

[0352] or, The number of times i=0,1,2,3… exceeds the preset number of times CNT4.

[0353]

[0354] The default threshold is set to 0.1 in this example. The target EGR rate is the gas stability condition for the EGR valve. The average value of the target EGR valve opening over time t1 is given by the EGR valve opening stability condition. This represents the average value of the filtered engine speed under stable signal conditions. This represents the average inlet temperature of the EGR valve under stable signal conditions. The default EGR valve inlet temperature is 550℃ in this example. The default speed is 1000 rpm in this example. The actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i; The filtered value of the actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i;

[0355] For element i, within the M1 sampling interval Maximum value.

[0356] Where the correction coefficient is two and , Based on the results determined by faulty and non-faulty pressure sensors, and benchmarked against both faulty and non-faulty pressure sensors, the three-standard-deviation principle is used to determine the... , and correction factor, where , The values ​​are 0.025 and 0.042 respectively.

[0357] Through embodiments of this invention, differentiated pressure signal stability diagnosis is performed for two states: stable and unstable speed change rate. When the speed change rate is unstable, a single-dimensional judgment using a mean array is employed, closely reflecting the characteristics of average pressure signal fluctuations under slight dynamic engine operating conditions. When the speed change rate is stable, a multi-dimensional judgment using maximum and minimum value arrays is employed, accurately capturing abnormal fluctuations in pressure signal extreme values ​​under strictly steady-state operating conditions. This achieves high adaptability for pressure signal diagnosis under different engine operating conditions, enabling more sensitive and accurate identification of small and continuous abnormal fluctuations in the pressure signal. The dynamic threshold is adapted to the actual operating conditions of the engine and EGR system, avoiding judgment deviations caused by thresholds. Furthermore, the calibration value is obtained by querying a calibration table indexed by the speed filter value and the target EGR valve opening, allowing the correction factor value to better reflect the system operating characteristics under different speeds and different EGR valve openings.

[0358] Based on the above embodiments, the calculation methods for the third fault count threshold and the fourth fault count include:

[0359] Obtain the third ratio of the average absolute value of the fresh air intake flow rate entering the cylinder under the condition of signal stability to the preset flow rate; obtain the fourth ratio of the average value of the mixing valve outlet pressure to the average value of the mixing valve inlet pressure under the condition of signal stability.

[0360] The calculation steps for the third fault count threshold are as follows: the fifth base value is obtained by inputting the third ratio into the thirteenth or fourteenth calibration table; the sixth base value is obtained by inputting the third ratio into the fifteenth or sixteenth calibration table; the fifth base value and the sixth base value are multiplied together and rounded to determine the third fault count threshold.

[0361] The thirteenth calibration table is used when the EGR valve is closed, and stores the corresponding third basic value indexed by the third ratio; the fifteenth calibration table is used when the EGR valve is closed, and stores the corresponding fourth basic value indexed by the fourth ratio; the fourteenth calibration table is used when the EGR valve is not closed, and stores the corresponding third basic value indexed by the third ratio; the sixteenth calibration table is used when the EGR valve is not closed, and stores the corresponding fourth basic value indexed by the fourth ratio.

[0362] The calculation steps for the second fault count threshold are as follows: the seventh base value is obtained by inputting the third ratio into the seventeenth or eighteenth calibration table; the eighth base value is obtained by inputting the fourth ratio into the nineteenth or twentieth calibration table; the third base value and the fourth base value are multiplied together and rounded to determine the second fault count threshold.

[0363] The seventeenth calibration table is used when the EGR valve is closed, and stores the corresponding seventh basic value indexed by the third ratio; the nineteenth calibration table is used when the EGR valve is closed, and stores the corresponding eighth basic value indexed by the fourth ratio; the eighteenth calibration table is used when the EGR valve is not closed, and stores the corresponding seventh basic value indexed by the third ratio; the twentieth calibration table is used when the EGR valve is not closed, and stores the corresponding eighth basic value indexed by the fourth ratio.

[0364] The third fault count threshold CNT3 is obtained as follows:

[0365] (1) If the EGR valve is closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (This example uses a ratio of 10 g / s) And the correction factor determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. The decision is made jointly, whereby the average outlet pressure of the mixing valve under signal stability conditions represents the outlet pressure of the mixing valve obtained when checking whether the signal stability conditions are met. Once the signal stability conditions are verified, the average outlet pressure of the mixing valve during the verification process is calculated and stored, i.e., CNT3 = V5. The values ​​are rounded to the nearest integer. The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system. Therefore, the larger the threshold coefficient CNT3=V5, the better to avoid the impact of flow disturbance. The calibration tables are shown in Tables 12 and 13.

[0366] Table 12

[0367]

[0368] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0369] Table 13

[0370]

[0371] (2) If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (In this example, 10 g / s is used) The correction factor is determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It was jointly decided that CNT3=V6. After rounding to the nearest integer, CNT3 = V6 (V6 is not less than V5). The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system, and its threshold coefficient is two. The larger the value, the less likely it is to cause the impact of traffic disturbances. The calibration tables are shown in Tables 14 and 15.

[0372] Table 14

[0373]

[0374] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0375] Table 15

[0376]

[0377] If the stability condition is not met when the EGR valve switches between closed and open states, then the pressure signal verification will be terminated.

[0378] The fourth fault counting threshold CNT4 is obtained as follows:

[0379] (1) If the EGR valve is closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (This example uses a ratio of 10 g / s) And the correction factor determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It is jointly determined that CNT4 = V7 (V7 is not greater than V5). The values ​​are rounded to the nearest integer. The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system, and the larger the threshold coefficient CNT4=V7, thus avoiding the impact of flow disturbance. The calibration tables are shown in Tables 16 and 17.

[0380] Table 16

[0381]

[0382] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0383] Table 17

[0384]

[0385] (2) If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder is based on the signal stability condition. With default traffic (In this example, 10 g / s is used) The correction factor is determined by the ratio of the average outlet pressure of the mixing valve to the average inlet pressure of the mixing valve under stable signal conditions. It was jointly decided that CNT4=V8 is The result is obtained by rounding to the nearest integer, CNT4 = V8 (V8 is not less than V7). The larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system; therefore, a larger threshold coefficient is needed to avoid the impact of flow disturbance. The calibration tables are shown in Tables 18 and 19.

[0386] Table 18

[0387]

[0388] The higher the pressure ratio of the mixing valve, the worse the throttling effect of the mixing valve, and the greater the gas flow disturbance may be. This can easily cause disturbances in the EGR valve outlet pressure, leading to a decrease in the accuracy of signal verification. To avoid such problems, it is necessary to increase the threshold number of times.

[0389] Table 19

[0390]

[0391] If the signal stability condition is not met when the EGR valve switches between closed and open states, then the pressure signal verification will be terminated.

[0392] Through the embodiments of this disclosure, the fault counting threshold can simultaneously respond to gas flow disturbances caused by changes in engine intake airflow and the throttling effect of the mixing valve. The higher the intake airflow and the higher the mixing valve pressure ratio, the higher the threshold will be. This effectively avoids the problem of normal pressure signal fluctuations caused by exhaust system flow disturbances and poor mixing valve throttling effect being misjudged as faults, and achieves dynamic adaptive optimization of the fault counting threshold. At the same time, dedicated calibration tables are configured for the two states of EGR valve closed and open, so that the threshold calculation can accurately match the gas flow characteristics of the EGR system under different operating conditions. When the EGR valve is not closed, the threshold is not less than that in the closed state, which is close to the actual operating condition where the pressure signal fluctuates more during exhaust gas recirculation.

[0393] It should be noted that the calibration system of this method is performed in a controlled engine bench environment, which establishes benchmarks for various filter coefficients, time parameters, and basic thresholds, specifically including:

[0394] For the filter coefficient, a normalized calibration strategy is adopted. Instead of conducting massive independent tests across the entire speed range, a reference speed (e.g., 1000 rpm) is selected. At this point, adjustments are made to determine the calibrated filter coefficient that achieves the optimal filtering effect for various parameters (such as intake air density and throttle opening). In practical applications, when the engine speed is stable, the current filter coefficient is automatically calculated from the engine speed and the calibrated filter coefficient, realizing the scaling of the coefficient with engine speed and reducing the workload of full-condition calibration.

[0395] For time parameters, such as the flow time required for exhaust gas to flow from the outlet of the particulate filter (GPF) to the inlet of the EGR valve or the outlet of the mixing valve, the actual measurement is carried out on the test bench by acquiring pressure pulse signals with high precision under different speed, load, and EGR valve opening combinations, and a three-dimensional lookup table is formed.

[0396] The dynamic threshold system for fault diagnosis is calibrated in two steps: First, initial threshold calibration is performed on a test bench. Data samples are collected at numerous engine operating points under two conditions: normal operation of the pressure sensor and simulated faults (such as the injection of periodic interference signals). By running a diagnostic algorithm, two sets of characteristic values ​​representing the periodicity of the signal are obtained. Subsequently, using the three-standard-deviation principle, a threshold is found that ensures the separation between normal and fault data distributions meets requirements, thereby ensuring that the threshold can distinguish between normal and fault states with a very high probability. Second, real-vehicle environmental correction is performed. For different atmospheric pressure and temperature conditions, the above data collection is repeated, and environmental correction factors (such as f1, f2) are determined through analysis. Finally, the dynamic threshold used for the real vehicle is calculated by multiplying the initial threshold by a series of formulas including the target EGR rate, engine speed, temperature, and environmental correction factors, giving the threshold full-condition adaptive capability.

[0397] To ensure the stability of the diagnostic system under different disturbance conditions, a fault-tolerant parameter calibration system was designed. The fresh air intake flow rate into the cylinder was used as a characterization of the disturbance intensity. Bench tests were conducted to determine the optimal number of fault counts (e.g., CNT1, CNT2, V1-V8) under different flow rate ratios, and a lookup table was created. Furthermore, a self-learning mechanism was introduced.

[0398] Through the embodiments of this invention, a complete standard system is adopted to jointly solve the problems of traditional diagnostic methods in terms of engineering implementation, scientific reliability, and long-term adaptability. By calibrating for different working conditions, the technical problem of the diagnostic system's decision threshold relying on experience is solved, and adaptive updates of each parameter for different working conditions are achieved.

[0399] Figure 3 A flowchart of another anomaly diagnosis method applied to an engine system provided in this disclosure embodiment is shown below. Figure 3 As shown, a diagnostic strategy for detecting periodic faults in the outlet pressure sensor of an EGR (Exhaust Gas Recirculation) system is described. It employs a strategy of first passively monitoring and screening, followed by active verification and confirmation, achieving reliable and high-accuracy fault detection while minimizing intervention in normal engine control. The system uses a single driving cycle as the execution unit and learns from historical diagnostic results.

[0400] The signal preparation and global operating condition steady-state determination phase begins with the system performing a first-order low-pass filter on a series of key operating parameters, including engine speed, rate of change of speed, and EGR valve inlet pressure. Next, it determines whether the engine meets the stability conditions for pressure verification signals, including coolant temperature, air-fuel ratio, and the status of various sensors. Further checks are then performed on operating conditions directly related to the EGR exhaust gas flow path, including the stability of the EGR valve opening, mixing valve opening, and upstream GPF (particulate filter) outlet pressure. Only when both of these conditions are consistently met for a preset time are the diagnostic phase allowed to proceed.

[0401] Once the steady-state conditions are met, the process enters the passive pressure periodic check phase, which is a preliminary screening without changing any engine control parameters. The EGR valve outlet pressure signal undergoes secondary filtering, and its pressure waveform peaks and troughs are continuously captured in real time. By calculating the time interval between adjacent peaks or troughs, a time difference array reflecting the periodic characteristics of the pressure signal is constructed. A relatively lenient threshold is used under transient conditions with large speed variations; a stricter threshold is used under steady-state conditions with stable speeds, ensuring high identification accuracy of passive diagnosis under different engine dynamic backgrounds. If a fault is directly identified at this stage, the process terminates and an alarm is triggered; if no fault is found and the triggering conditions are met, active diagnosis is performed. The system first controls the current target EGR rate to create a test environment with a constant exhaust gas flow input. Then, after confirming that the active steady-state conditions are met again, the system collects pressure data for a period of time, but the analysis object changes from the passive diagnosis time interval to the average fluctuation of the pressure level. Faults are captured by calculating the pressure average, maximum, and minimum value sequences. If active diagnosis confirms no fault, the next cycle directly enters the active diagnosis mode.

[0402] In a real ECU, a sophisticated state machine is needed for management. An example of a state machine design is as follows:

[0403] Define the following states:

[0404] INIT: Initializes and clears historical data and counters; MONITOR_STEADY_CONDITIONS: Monitors 17 signal stability conditions. If not met, it waits / loops; if met for more than t0, it proceeds to the next state.

[0405] PASSIVE_EGR_STEADY_CHECK: Monitors the gas stability condition of the first EGR valve. Simultaneously starts / continues passive diagnostic data acquisition (maximum value recording). If the condition is not met, it reverts to MONITOR state. If the condition is continuously met for more than t1, passive diagnostic calculation is triggered.

[0406] PASSIVE_DIAGNOSIS_EVAL: Executes a passive diagnostic algorithm (calculates the time difference array, compares it with a threshold, and counts the number of faults). Based on the result: If a fault is detected, enters the FAULT_CONFIRMED state and reports a fault code. If no fault is detected, updates the driving cycle counter CNT_SpdStability or CNT_NoSpdStability. Then checks if the active diagnostic trigger conditions are met. If met, enters the PREPARE_ACTIVE_DIAG state, saves the current target EGR rate, and locks it. If not met, returns to the MONITOR_STEADY_CONDITIONS state and begins the next round of monitoring.

[0407] PREPARE_ACTIVE_DIAG: After locking the EGR rate, monitor the signal stability condition and the gas stability condition of the second EGR valve again. If the condition is continuously met for more than t2+t3, then proceed to active diagnostic calculation.

[0408] ACTIVE_DIAGNOSIS_EVAL: Executes the active diagnostic algorithm, calculating the mean, maximum, and minimum value arrays. Based on the results: If a fault is determined, enters FAULT_CONFIRMED and calls UpdatePassiveThresholdLearning(true, ...). If no fault is determined, calls UpdatePassiveThresholdLearning(false, ...). If no fault is found in this active diagnostic, the next driving cycle directly jumps to the PREPARE_ACTIVE_DIAG state (i.e., skips passive diagnostics and directly performs active monitoring).

[0409] FAULT_CONFIRMED: Fault confirmation state. Freeze frame data is stored, and the fault indicator light is illuminated. In this state, the main diagnostic process is paused. The system will not reset to the INIT state until the fault codes are cleared using a diagnostic tool.

[0410] It should be noted that in any steady-state monitoring or diagnostic execution state, if the corresponding steady-state condition is violated, the state machine should immediately exit the current diagnostic and return to the MONITOR_STEADY_CONDITIONS state. Simultaneously, ongoing timers (such as t1 timer) should be cleared or paused, and data segments that have been collected but not yet diagnosed should be discarded. At the end of the driving cycle, necessary learning coefficients and counters should be saved. At the start of a new driving cycle, it begins in the INIT state but reads the saved learning coefficients. Basic signal rationality checks should be performed before filtering and diagnostics. If the EGR valve outlet pressure signal itself exceeds the physically possible range (e.g., negative pressure, over-range), the relevant fault should be reported directly without entering the current periodic diagnostic process.

[0411] Figure 4 A structural block diagram of an abnormality diagnosis system for an engine system provided in an embodiment of the present invention is shown below. Figure 4 As shown, a second aspect of the present invention provides an anomaly diagnosis system for an engine system, which can be used to implement the above-described anomaly diagnosis method for an engine system, including:

[0412] The filtering module is used to perform first-order low-pass filtering on each engine operating parameter using the corresponding filtering coefficients to obtain the corresponding filtered value. The engine operating parameters include at least engine speed parameters and engine-related parameters. The filtering coefficients for each engine-related parameter are determined based on the stability of the engine speed parameters. The engine speed parameters include engine speed and rate of change of engine speed. The engine-related parameters include at least the EGR valve outlet pressure.

[0413] The passive pressure periodic verification module is used to respond to the engine operating condition being determined to be a passive steady-state condition by using engine operating parameters and filter values. It then preprocesses the filter values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a time difference array. The time difference array includes at least a maximum value interval time array and a minimum value interval time array of the EGR valve outlet pressure. Based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds the dynamic threshold.

[0414] The active pressure fluctuation verification module is used to determine whether the engine operating condition is an active steady-state condition in response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in the passive pressure periodic verification step of the third consecutive preset number of driving cycles, the outlet pressure signal is stable and the number of stable times of the engine speed change rate meets the requirements. In response to the engine operating condition being an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array. Based on the stability of the speed change rate, the stability of the outlet pressure signal fluctuation is determined by the number of times the outlet pressure array is greater than the dynamic threshold.

[0415] Based on the same inventive concept, embodiments of the present invention also provide an electronic device. Figure 5 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. Figure 5 As shown, an embodiment of the present invention provides an electronic device including: one or more processors 101, a memory 102, and one or more I / O interfaces 103. The memory 102 stores one or more programs, which, when executed by the one or more processors, cause the one or more processors to implement any of the abnormal diagnosis methods applied to an engine system as described in the above embodiments; the one or more I / O interfaces 103 are connected between the processor and the memory, configured to enable information interaction between the processor and the memory.

[0416] The processor 101 is a device with data processing capabilities, including but not limited to a central processing unit (CPU); the memory 102 is a device with data storage capabilities, including but not limited to random access memory (RAM, more specifically SDRAM, DDR, etc.), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and flash memory (FLASH); the I / O interface (read / write interface) 103 is connected between the processor 101 and the memory 102, and can realize information interaction between the processor 101 and the memory 102, including but not limited to a data bus (Bus).

[0417] In some embodiments, the processor 101, memory 102, and I / O interface 103 are interconnected via bus 104, and thus connected to other components of the computing device.

[0418] In some embodiments, the one or more processors 101 include a field-programmable gate array.

[0419] This invention also provides a computer-readable medium. The computer-readable medium stores a computer program, which, when executed by a processor, implements the steps of any of the anomaly diagnosis methods applied to an engine system as described in the above embodiments. The computer-readable storage medium may be volatile or non-volatile.

[0420] This invention also provides a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code. When the computer-readable code is run in the processor of an electronic device, the processor in the electronic device executes the above-described anomaly diagnosis method applied to an engine system.

[0421] Those skilled in the art will understand that all or some of the steps, systems, and apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software can be distributed on a computer-readable storage medium, which may include computer storage media (or non-transitory media) and communication media (or transient media).

[0422] As is known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable program instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), static random access memory (SRAM), flash memory or other memory technologies, portable compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, it is known to those skilled in the art that communication media typically contain computer-readable program instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0423] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0424] The computer program instructions used to perform the operations of this invention may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the computer-readable program instructions. This electronic circuitry can execute the computer-readable program instructions to implement various aspects of the invention.

[0425] The computer program product described herein can be implemented specifically through hardware, software, or a combination thereof. In one alternative embodiment, the computer program product is specifically embodied in a computer storage medium; in another alternative embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0426] Various aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0427] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0428] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0429] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction, which contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0430] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A method for diagnosing anomalies in an engine system, characterized in that, The detection steps in the current driving cycle include: Filtering steps: For each engine operating parameter, a first-order low-pass filter is performed using the corresponding filter coefficient to obtain the corresponding filter value; wherein, the engine operating parameters include at least engine speed parameters and engine-related parameters; the filter coefficient corresponding to each engine-related parameter is determined based on the stability of the engine speed parameters; the engine speed parameters include engine speed and rate of change of engine speed; the engine-related parameters include at least the EGR valve outlet pressure; Passive pressure periodic verification step: In response to determining that the engine operating condition is a passive steady-state condition using the engine operating parameters and the filtered value, the filtered value of the EGR valve outlet pressure within a first preset number of sampling periods is preprocessed to obtain a time difference array; the time difference array includes at least a maximum value interval time array and a minimum value interval time array of the EGR valve outlet pressure; based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds the dynamic threshold; Active pressure fluctuation verification step: In response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in response to the determination that the outlet pressure signal is stable and the number of stable times of the engine speed change rate meets the requirements in the passive pressure periodic verification step of the third consecutive preset number of driving cycles, the engine operating parameters and the filter value are used to determine whether the engine operating condition is an active steady-state condition; in response to the engine operating condition being an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array; based on the stability of the speed change rate, the number of times the outlet pressure array is greater than the dynamic threshold is used to determine the fluctuation stability of the outlet pressure signal.

2. The method according to claim 1, wherein, The engine-related parameters include at least one of the following: intake air density into the cylinder, throttle opening, mixing valve opening, EGR valve opening, EGR valve inlet pressure, and EGR valve outlet pressure; the calculation method for the filter coefficients corresponding to the engine-related parameters includes: Determine whether the engine speed parameters are in a stable state; If the engine speed parameters are stable, the current filter coefficient is calculated based on the preset calibration filter coefficient and the engine speed; the calibration filter coefficient is obtained by bench testing an engine at the preset speed. If the engine speed parameters are unstable, the current filter coefficient is calculated based on the preset self-learning coefficient.

3. The method according to claim 1, wherein, The process involves preprocessing the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a time difference array, which previously included... Using the engine operating parameters and the filter value, the engine operating condition is determined, specifically including: By using engine operating parameters and the difference between engine operating parameters and corresponding filter values, it can be determined whether the engine meets the signal stability conditions. If the time for the engine to meet the signal stabilization condition exceeds the first preset time, it is determined whether the engine meets the first EGR valve gas stabilization condition. If the engine meets the gas stability condition of the first EGR valve, the engine operating condition is determined to be a passive steady-state condition.

4. The method according to claim 3, wherein, Determining whether the engine meets the first EGR valve gas stability condition includes: Determine whether the time it takes for the engine to meet the gas stability condition of the first EGR valve exceeds the first time interval; If so, the engine is determined to meet the gas stability condition of the first EGR valve; If not, the engine is determined not to meet the gas stability conditions of the first EGR valve, and the diagnostic process is terminated. The gas stability conditions for the first EGR valve include: Condition 1: The difference between the opening degree of the mixing valve and its filter value is less than a first threshold, where the first threshold is the product of the minimum value of the opening degree of the mixing valve and its filter value and a first preset threshold coefficient; Condition 2: The target EGR rate fluctuates within the first preset range; Condition 3: The difference between the EGR valve opening and its filter value is less than the second threshold, which is the product of the minimum value of the EGR valve and its filter value and the second preset threshold coefficient; Condition 4: The difference between the EGR valve inlet pressure and its filtered value is less than the third threshold, which is the product of the minimum value of the EGR valve inlet pressure and its filtered value and the third preset threshold coefficient; Condition 5: No EGR valve inlet pressure sensor circuit failure occurred.

5. The method according to claim 4, wherein, The methods for obtaining the first time include: In response to the EGR valve opening being 0, the first time is the sum of the calibrated time for fresh air to flow from the mixing valve outlet to the booster inlet and the first delay time; In response to an EGR valve opening greater than 0, the first time is the sum of the time required for the exhaust gas to flow from the particulate filter outlet to the mixing valve outlet under the calibrated current EGR valve opening and the second delay time. The first delay time is obtained by looking up the average value of the engine speed filter value within the first preset time from the first calibration table; The second delay time is obtained from the second calibration table by using the average value of the engine speed filter value and the EGR valve opening within the first preset time period.

6. The method according to claim 1, wherein, The filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods are preprocessed to obtain a time difference array, including: Read the maximum and minimum values ​​of the filtered values ​​of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a first maximum value array and a first minimum value array; Remove the first second preset number of elements from the first maximum value array and the first minimum value array, and remove the maximum value and the corresponding minimum value that are 0 to obtain the second maximum value array and the second minimum value array; Based on the second maximum value array and the second minimum value array, we obtain the maximum value interval time array and the minimum value interval time array; The method for obtaining the second preset quantity includes: Based on the filtered value of the rotational speed, the second preset quantity is obtained by querying the third calibration table; the third calibration table records the mapping relationship between the range of filtered values ​​of the rotational speed and the second preset quantity.

7. The method according to claim 1, wherein, The step of determining the periodic stability of the outlet pressure signal based on the stability of the rotational speed change rate, using the number of times the time difference array exceeds a dynamic threshold, includes: Using the rate of change of rotational speed and its filtered value, determine whether the rate of change of rotational speed is stable within the second preset time period; If the rotational speed change rate is unstable within the second preset time period, the first number of times when the time difference is less than the first dynamic threshold is counted in the time difference array. When the first count is greater than the first fault count threshold, it is determined that the inlet pressure signal has a fault. If the rotational speed change rate is stable within a second preset time, then count the second number of times the time difference is less than the second dynamic threshold in the time difference array. When the second number is greater than the second fault count threshold, it is determined that the inlet pressure signal has a fault. The first dynamic threshold and the second dynamic threshold are determined at least based on the target EGR rate, the filtered value of the rotational speed, the EGR valve inlet temperature, the EGR valve inlet pressure, and the self-learning coefficient. The first fault counting threshold and the second fault counting threshold are determined at least based on the ratio of the fresh air intake flow rate into the cylinder to the pressure at the outlet and inlet of the mixing valve and the self-learning coefficient.

8. The method according to claim 7, wherein, The calculation methods for the first fault count threshold and the second fault count include: Obtain the first ratio of the average absolute value of the fresh air intake flow rate entering the cylinder under the condition of signal stability to the preset flow rate; Obtain a second ratio between the average value of the mixing valve outlet pressure and the average value of the mixing valve inlet pressure under the condition of signal stability. The calculation steps for the first fault counting threshold are as follows: by inputting the first ratio into the fourth or fifth calibration table, a first base value is obtained; by inputting the second ratio into the sixth or seventh calibration table, a second base value is obtained; the first base value, the second base value, and the first counting self-learning coefficient are multiplied together and rounded to determine the first fault counting threshold. Specifically, the fourth calibration table stores the corresponding first basic value using the first ratio as an index when the EGR valve is closed; the sixth calibration table stores the corresponding second basic value using the second ratio as an index when the EGR valve is closed; the fifth calibration table stores the corresponding first basic value using the first ratio as an index when the EGR valve is not closed; and the seventh calibration table stores the corresponding second basic value using the second ratio as an index when the EGR valve is not closed. The calculation steps for the second fault counting threshold are as follows: by inputting the first ratio into the eighth or ninth calibration table, a third base value is obtained; by inputting the second ratio into the tenth or eleventh calibration table, a fourth base value is obtained; the third base value, the fourth base value, and the second counting self-learning coefficient are multiplied together and rounded to determine the second fault counting threshold. Specifically, the eighth calibration table is used when the EGR valve is closed, and stores the corresponding third basic value indexed by the first ratio; the tenth calibration table is used when the EGR valve is closed, and stores the corresponding fourth basic value indexed by the second ratio; the ninth calibration table is used when the EGR valve is not closed, and stores the corresponding third basic value indexed by the first ratio; and the eleventh calibration table is used when the EGR valve is not closed, and stores the corresponding fourth basic value indexed by the second ratio.

9. The method according to claim 8, wherein, The method further includes: Determine if the active pressure fluctuation check step for the current driving cycle has malfunctioned; If a fault occurs, determine whether the engine speed change rate has been unstable in the passive pressure periodic check step of the current driving cycle. If so, reduce the self-learning coefficient of the first dynamic threshold and reduce the first fault self-learning coefficient of EGR valve closure. If not, reduce the self-learning coefficient of the second dynamic threshold and reduce the first count self-learning coefficient of EGR valve not closed. If no fault occurs, determine whether the engine speed change rate has been unstable during the passive pressure periodic check step of the current driving cycle. If so, increase the self-learning coefficient of the first dynamic threshold and increase the second fault self-learning coefficient of EGR valve closure. If not, increase the self-learning coefficient of the second dynamic threshold and increase the second count self-learning coefficient of EGR valve not being closed.

10. The method according to claim 1, wherein, Using the engine operating parameters and the filter value, determine whether the engine operating condition is an active steady-state condition, including: By using engine operating parameters and the difference between engine operating parameters and corresponding filter values, it can be determined whether the engine meets the signal stability conditions. If the time for the engine to meet the signal stabilization condition exceeds the first preset time, the target EGR rate is unchanged when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the second EGR valve gas stabilization condition. In response to the engine meeting the gas stability condition of the second EGR valve, the target EGR valve is controlled so that the target EGR rate remains unchanged when entering the active pressure fluctuation verification step, and it is determined whether the engine meets the EGR valve opening stability condition. If the engine meets the EGR valve opening stability condition, the engine operating condition is determined to be an active steady-state condition.

11. The method according to claim 10, wherein, Determine whether the engine meets the gas stability conditions of the second EGR valve, including: Determine whether the time it takes for the engine to meet the gas stability condition of the second EGR valve exceeds the third preset time; If so, the engine is determined to meet the gas stability conditions of the second EGR valve; If not, the engine is determined not to meet the gas stability conditions of the second EGR valve, and the diagnostic process is terminated. The gas stabilization conditions for the second EGR valve include: Condition 6: The difference between the opening degree of the mixing valve and its filter value is less than a first threshold, where the first threshold is the product of the minimum value of the opening degree of the mixing valve and its filter value and a first preset threshold coefficient; Condition 7: The difference between the EGR valve inlet pressure and its filter value is less than the second threshold, which is the product of the minimum value of the inlet pressure and its filter value and the second preset threshold coefficient; Condition 8: The EGR valve inlet temperature fluctuation is within the second preset range; Condition 9: No EGR valve inlet pressure sensor circuit failure or EGR valve outlet pressure sensor circuit failure occurred.

12. The method according to claim 10, wherein, Determining whether the engine meets the EGR valve opening stability conditions includes: Using the EGR valve opening degree and its filtered value, determine whether the EGR valve opening degree is stable within the fourth preset time period; If so, the engine is determined to meet the EGR valve opening stability condition; If not, the engine is determined not to meet the EGR valve opening stability condition, and the outlet pressure signal stability check is terminated. The method for obtaining the fourth preset time includes: in response to the EGR valve opening being 0, the fourth preset time is the time required for calibrated fresh air to flow from the mixing valve outlet to the turbocharger inlet; in response to the EGR valve opening being greater than 0, the fourth preset time is the time required for calibrated exhaust gas to flow from the gasoline particulate filter outlet to the mixing valve outlet at the current EGR valve opening.

13. The method according to claim 11, wherein, The preprocessing of the EGR valve outlet pressure within a fourth preset number of sampling periods yields an outlet pressure array, including: Read the maximum and minimum values ​​of the filtered EGR valve outlet pressure within the fourth preset number of sampling periods to obtain the first maximum value array and the first minimum value array; Remove the first second preset number of elements from the first maximum value array and the first minimum value array, and remove the maximum value and the corresponding minimum value that are 0 to obtain the second maximum value array and the second minimum value array; Divide the second maximum value array and the second minimum value array according to the fifth preset quantity to obtain the maximum value interval and the minimum value interval of the sixth preset quantity. Calculate the average value of each interval, remove the maximum value average value and the corresponding minimum value average value that are 0, and obtain the final maximum value array and the final minimum value array. The mean array is obtained by averaging the corresponding elements of the final maximum value array and the final minimum value array.

14. The method according to claim 1, wherein, The step of determining the stability of the outlet pressure signal fluctuation based on the stability of the rotational speed change rate, using the number of times the outlet pressure array exceeds a dynamic threshold, includes: Using the rate of change of rotational speed and the filtered value of the rate of change of rotational speed, it is determined whether the rate of change of rotational speed is stable within the fifth preset time period; If the rotational speed change rate is unstable within the fifth preset time period, a judgment is made based on the mean array in the outlet pressure array. The absolute value of the difference between adjacent elements in the mean array is counted to be greater than the third number of the third dynamic threshold. When the third number exceeds the third fault count threshold, the outlet pressure signal is determined to be unstable. If the rotational speed change rate is stable within the fifth preset time period, then a judgment is made based on the maximum value array and minimum value array in the outlet pressure array. The number of times the absolute value of the difference between adjacent elements in the maximum value array is greater than the fourth dynamic threshold, the number of times the absolute value of the difference between adjacent elements in the minimum value array is greater than the fifth dynamic threshold, and the number of times the absolute value of the difference between the corresponding elements of the maximum and minimum value arrays is greater than the sixth dynamic threshold are counted. When the fourth, fifth, or sixth count exceeds the fourth fault count threshold, the outlet pressure signal is determined to be unstable. The third dynamic threshold, the fourth dynamic threshold, the fifth dynamic threshold, and the sixth dynamic threshold are determined at least based on the target EGR rate, the filtered value of the rotational speed, the target EGR valve opening, the EGR valve inlet temperature, the EGR valve inlet pressure, and the filtered value of the EGR valve inlet pressure. The third fault counting threshold and the fourth fault counting threshold are determined at least based on the ratio of the fresh air intake flow rate into the cylinder to the pressure at the outlet and inlet of the mixing valve.

15. The method according to claim 14, wherein, The calculation methods for the third dynamic threshold, the fourth dynamic threshold, the fifth dynamic threshold, and the sixth dynamic threshold include: The third dynamic threshold is obtained based on the first preset default threshold, the minimum absolute value of the difference between adjacent elements of the mean array, the first correction factor, and the second correction factor. The fourth dynamic threshold is obtained based on the second preset default threshold, the minimum absolute value of the difference between adjacent elements in the maximum value array, the third correction factor, and the fourth correction factor; The fifth dynamic threshold is obtained based on the second preset default threshold, the minimum value of the absolute value of the difference between adjacent elements of the minimum value array, the third correction factor, and the fourth correction factor; The sixth dynamic threshold is obtained based on the second preset default threshold, the minimum value of the absolute value of the difference between the corresponding elements of the maximum and minimum value arrays, the third correction factor, and the fourth correction factor; The first correction factor is calculated using a first preset value, a target EGR rate, and a calibration value; the second correction factor is calculated using a second preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure; the third correction factor is calculated using a third preset value, a target EGR rate, and a calibration value; and the fourth correction factor is calculated using a fourth preset value, an EGR valve inlet temperature, an EGR valve inlet pressure, and a filtered value of the EGR valve inlet pressure. The calibration value is obtained by querying a preset twelfth calibration table; the twelfth calibration table stores the corresponding calibration values, indexed by the filtered value of the rotational speed and the target EGR valve opening.

16. The method of claim 14, wherein, The calculation methods for the third fault count threshold and the fourth fault count include: Obtain the third ratio of the average absolute value of the fresh air intake flow rate entering the cylinder under stable signal conditions to the preset flow rate; Obtain the fourth ratio of the average value of the mixing valve outlet pressure to the average value of the mixing valve inlet pressure under the condition of signal stability. The calculation steps for the third fault counting threshold are as follows: by inputting the third ratio into the thirteenth or fourteenth calibration table, a fifth basic value is obtained; by inputting the third ratio into the fifteenth or sixteenth calibration table, a sixth basic value is obtained; the fifth basic value and the sixth basic value are multiplied together and rounded to determine the third fault counting threshold. Specifically, the thirteenth calibration table is used when the EGR valve is closed, and stores the corresponding third basic value indexed by the third ratio; the fifteenth calibration table is used when the EGR valve is closed, and stores the corresponding fourth basic value indexed by the fourth ratio; the fourteenth calibration table is used when the EGR valve is not closed, and stores the corresponding third basic value indexed by the third ratio; the sixteenth calibration table is used when the EGR valve is not closed, and stores the corresponding fourth basic value indexed by the fourth ratio. The calculation steps for the second fault count threshold are as follows: by inputting the third ratio into the seventeenth or eighteenth calibration table, a seventh basic value is obtained; by inputting the fourth ratio into the nineteenth or twentieth calibration table, an eighth basic value is obtained; the third basic value and the fourth basic value are multiplied together and rounded to determine the second fault count threshold. Specifically, the seventeenth calibration table is used when the EGR valve is closed, and stores the corresponding seventh basic value indexed by the third ratio; the nineteenth calibration table is used when the EGR valve is closed, and stores the corresponding eighth basic value indexed by the fourth ratio; the eighteenth calibration table is used when the EGR valve is not closed, and stores the corresponding seventh basic value indexed by the third ratio; and the twentieth calibration table is used when the EGR valve is not closed, and stores the corresponding eighth basic value indexed by the fourth ratio.

17. The method according to claim 1, wherein, The stability number of the engine speed change rate meets the requirements, including: The number of driving cycles that enter the diagnosis of engine speed change rate not being in a stable state is not less than the fifth preset value, and the number of driving cycles that enter the diagnosis of engine speed change rate being in a stable state is 0. The number of driving cycles that enter the diagnosis of engine speed change rate being in a stable state is not less than the sixth preset value, and the number of driving cycles that enter the diagnosis of engine speed change rate not being in a stable state is 0. The number of driving cycles diagnosed when the engine speed change rate is in a stable state and the number of driving cycles diagnosed when the engine speed change rate is not in a stable state are both not 0, but the sum of the number of driving cycles diagnosed when the engine speed change rate is in a stable state and the number of driving cycles diagnosed when the engine speed change rate is not in a stable state is not less than the seventh preset value.

18. An anomaly diagnosis system applied to an engine system, characterized in that, Capable of implementing the method of claim 1, comprising: A filtering module is used to perform first-order low-pass filtering on each engine operating parameter using corresponding filtering coefficients to obtain the corresponding filtered value. The engine operating parameters include at least engine speed parameters and engine-related parameters. The filtering coefficient for each engine-related parameter is determined based on the stability of the engine speed parameters. The engine speed parameters include engine speed and rate of change of engine speed. The engine-related parameters include at least the EGR valve outlet pressure. The passive pressure periodic verification module is used to, in response to determining that the engine operating condition is a passive steady-state condition using the engine operating parameters and the filtered value, preprocess the filtered value of the EGR valve outlet pressure within a first preset number of sampling periods to obtain a time difference array; the time difference array includes at least a maximum value interval time array and a minimum value interval time array of the EGR valve outlet pressure; based on the stability of the speed change rate, the periodic stability of the outlet pressure signal is determined by the number of times the time difference array exceeds a dynamic threshold; The active pressure fluctuation verification module is used to determine whether the engine operating condition is an active steady-state condition in response to the determination that the outlet pressure signal is stable in the active pressure fluctuation verification step of the previous driving cycle, or in the passive pressure periodic verification step of the third consecutive preset number of driving cycles, the outlet pressure signal is stable and the number of stable times of the engine speed change rate meets the requirements. In response to the engine operating condition being an active steady-state condition, the EGR valve outlet pressure within the fourth preset number of sampling periods is preprocessed to obtain an outlet pressure array. Based on the stability of the speed change rate, the stability of the outlet pressure signal fluctuation is determined by the number of times the outlet pressure array is greater than the dynamic threshold.

19. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in claim 1.

20. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in claim 1.

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