Egr pressure failure diagnosis method and apparatus

Abstract

An EGR pressure fault diagnosis method and apparatus, relating to the field of engine control, includes performing active diagnosis when a passive diagnosis result corresponding to a target EGR valve pressure signal indicates an EGR pressure fault, thereby obtaining an active diagnosis result. This active diagnosis includes forcibly controlling the target EGR rate or target EGR opening to a preset state and monitoring pressure response characteristics. Based on the active diagnosis result, an EGR pressure fault diagnosis result is determined, and the diagnostic threshold of the passive diagnosis is dynamically adjusted based on the consistency between the passive and active diagnosis results. This application accurately distinguishes between normal fluctuations and fault signals by combining active and passive diagnosis. Active diagnosis forcibly creates specific operating conditions to stimulate hidden fault characteristics, significantly reducing false alarm and false negative rates. Simultaneously, the high-confidence results of active diagnosis are used to calibrate the threshold of passive diagnosis, forming a self-evolving closed-loop diagnosis.

Description

Technical Field

[0001] This application relates to the field of engine control technology, specifically to an EGR pressure fault diagnosis method and device. Background Technology

[0002] Exhaust Gas Recirculation (EGR) systems are key components in modern engines for reducing nitrogen oxide (NOx) emissions. The gas pressure on both sides of the EGR valve (inlet and outlet) serves as a crucial input for EGR rate control, determining the estimation of exhaust gas flow and the accuracy of EGR valve opening control, thus affecting the precision of the target EGR rate. Therefore, it is necessary to regularly check whether the EGR valve gas pressure signal is normal to avoid affecting the control of the target EGR rate and thus preventing EGR from adversely impacting engine performance.

[0003] In related technologies, passive diagnostic methods are usually used to diagnose EGR pressure faults. However, when faced with complex engine operating conditions, it is often difficult to distinguish between normal fluctuations and fault signals. Furthermore, it lacks effective means to trigger hidden faults such as slight drift, making it difficult to optimize both false alarm and false alarm rates simultaneously. In addition, the diagnostic thresholds used in passive diagnostic methods are often fixed constants during calibration, which cannot adapt to sensor aging and system variations, thus easily leading to false alarms or false alarms. Summary of the Invention

[0004] This application provides an EGR pressure fault diagnosis method and apparatus, which can solve the technical problems of false alarms or missed alarms caused by the passive diagnosis method of EGR pressure fault diagnosis using a fixed diagnostic threshold in the prior art.

[0005] In a first aspect, embodiments of this application provide an EGR pressure fault diagnosis method, including: When the passive diagnostic result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, active diagnosis is performed to obtain the active diagnostic result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to be in a preset state and monitoring the pressure response characteristics. Based on the active diagnostic results, the EGR pressure fault diagnosis results are determined, and the diagnostic threshold of the passive diagnosis is dynamically adjusted based on the consistency between the passive diagnostic results and the active diagnostic results.

[0006] In conjunction with the first aspect, in one implementation, dynamically adjusting the diagnostic threshold of the passive diagnosis based on the consistency between the passive diagnostic result and the active diagnostic result includes: If both the passive diagnostic result and the active diagnostic result indicate that there is a fault in the EGR pressure, then the diagnostic threshold for the passive diagnostic is lowered. If the passive diagnosis result indicates a fault in EGR pressure and the active diagnosis result indicates no fault in EGR pressure, then the diagnostic threshold for the passive diagnosis is increased.

[0007] In conjunction with the first aspect, in one embodiment, the target EGR valve pressure signal includes a target EGR valve inlet pressure signal and a target EGR valve outlet pressure signal. After the step of determining the EGR pressure fault diagnosis result based on the active diagnosis result, the method further includes: If the EGR pressure fault diagnosis result corresponding to the target EGR valve inlet pressure signal is that there is a fault in the EGR inlet pressure and the EGR pressure fault diagnosis result corresponding to the target EGR valve outlet pressure signal is that there is a fault in the EGR valve outlet pressure, then the inlet and outlet pressure rationality diagnosis is performed to obtain the rationality diagnosis result. The inlet and outlet pressure rationality diagnosis includes controlling the engine to run in sequence under multiple operating conditions with different EGR rates and monitoring the pressure response characteristics under different operating conditions. The diagnostic threshold for rationality diagnosis of inlet and outlet pressure is dynamically adjusted based on the rationality diagnosis results.

[0008] In conjunction with the first aspect, in one implementation, prior to the step of performing active diagnostics, the method further includes: Determine whether the EGR system meets the preset active diagnostic conditions; If the conditions are met, then proceed with the step of performing active diagnosis. If the first preset duration is not met, the EGR pressure fault diagnosis result is determined to be that there is no fault in the EGR pressure. If the target EGR valve pressure signal is the target EGR valve inlet pressure signal, then the preset active diagnosis conditions include the actual mixing valve opening, the actual EGR valve opening, the EGR valve inlet temperature fluctuation, the GPF outlet pressure fluctuation, and the EGR valve inlet pressure sensor circuit status all meeting the preset inlet active diagnosis requirements and lasting for a duration reaching the third duration threshold. If the target EGR valve pressure signal is the target EGR valve outlet pressure signal, then the preset active diagnostic conditions include a first diagnostic condition and a second diagnostic condition. The first diagnostic condition includes that the actual mixing valve opening, EGR valve inlet pressure fluctuation, EGR valve inlet temperature fluctuation, and EGR valve outlet pressure sensor circuit status all meet the preset first outlet active diagnostic requirements and the duration reaches the fourth duration threshold. The second diagnostic condition includes that the actual EGR valve opening within the target duration meets the preset second outlet active diagnostic requirements. The target duration is the duration during which the target EGR valve opening is fixed at the target EGR valve opening average value. The target EGR valve opening average value is collected under the first diagnostic condition while keeping the target EGR rate constant.

[0009] In conjunction with the first aspect, in one embodiment, when the target EGR valve pressure signal is the target EGR valve inlet pressure signal, the step of performing active diagnosis and obtaining active diagnosis results includes: The current target EGR rate is fixed as the target EGR rate under the first sampling period when the preset active diagnostic conditions are met; Based on the target interval value, the inlet maximum value sequence and inlet minimum value sequence of the current EGR valve inlet pressure signal corresponding to the current target EGR rate are divided into intervals, and the average value of the divided intervals is calculated to obtain the inlet maximum value array and the inlet minimum value array. The target inlet array is obtained by averaging the common elements in the inlet maximum and inlet minimum arrays. The active diagnostic result of the inlet is determined based on the difference between adjacent elements in the target inlet array and the target time difference threshold.

[0010] In conjunction with the first aspect, in one embodiment, the target time difference threshold is determined based on a base time difference threshold, the average target EGR rate under preset stability conditions, the average engine speed filter value under preset stability conditions, the average EGR valve inlet temperature under preset stability conditions, the preset EGR inlet temperature value, the preset engine speed, the preset atmospheric pressure, the current actual atmospheric pressure, the preset atmospheric temperature, the actual atmospheric temperature, and a preset fitting coefficient.

[0011] In conjunction with the first aspect, in one embodiment, when the target EGR valve pressure signal is the target EGR valve outlet pressure signal, the step of performing active diagnosis and obtaining active diagnosis results includes: Based on the target interval value, the current EGR valve outlet pressure signal is divided into intervals for the outlet maximum value sequence and the outlet minimum value sequence, and the average value of the divided intervals is calculated to obtain the outlet maximum value array and the outlet minimum value array. The target export array is obtained by averaging the common elements in the export maximum and export minimum arrays. The active diagnostic result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements.

[0012] In conjunction with the first aspect, in one embodiment, the target difference threshold is determined based on the adjacent elements themselves, the basic difference threshold, the target EGR rate that remains unchanged under the first diagnostic condition, the average value of the target EGR valve opening under the first diagnostic condition, the average value of the engine speed filter value under the preset stability condition, the average value of the EGR valve inlet temperature under the preset stability condition, the preset EGR valve inlet temperature, the preset engine speed, the preset target EGR rate, the actual EGR valve inlet pressure in the interval where the adjacent elements are located, the actual EGR valve inlet pressure filter value in the interval where the adjacent elements are located, and the preset fitting coefficient.

[0013] In conjunction with the first aspect, in one embodiment, the method further includes: When the EGR system is detected to meet the preset stability conditions, it is determined whether the EGR system meets the preset passive diagnostic conditions. If the conditions are met, then perform a passive diagnosis. If the conditions are not met, no diagnosis will be performed; The preset stability conditions include the engine operating state, intake system parameters, combustion state parameters, and sensor state parameters all meeting the preset stability requirements for a duration reaching a first duration threshold. The preset passive diagnostic conditions include the actual mixing valve opening, target EGR rate fluctuation, actual EGR valve opening, EGR valve inlet temperature fluctuation, GPF outlet pressure fluctuation or EGR valve inlet pressure fluctuation, and EGR valve inlet and outlet pressure sensor circuit state all meeting the preset passive diagnostic requirements for a duration reaching a second duration threshold.

[0014] Secondly, embodiments of this application provide an EGR pressure fault diagnosis device, comprising: The fault diagnosis module is used to perform active diagnosis when the passive diagnosis result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, and obtain the active diagnosis result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to be in a preset state and monitoring the pressure response characteristics. Based on the active diagnosis result, the EGR pressure fault diagnosis result is determined. A threshold adjustment module is used to dynamically adjust the diagnostic threshold of passive diagnosis based on the consistency between the passive diagnosis result and the active diagnosis result.

[0015] In conjunction with the second aspect, in one implementation, the threshold adjustment module is specifically used for: If both the passive diagnostic result and the active diagnostic result indicate that there is a fault in the EGR pressure, then the diagnostic threshold for the passive diagnostic is lowered. If the passive diagnosis result indicates a fault in EGR pressure and the active diagnosis result indicates no fault in EGR pressure, then the diagnostic threshold for the passive diagnosis is increased.

[0016] In conjunction with the second aspect, in one embodiment, the target EGR valve pressure signal includes a target EGR valve inlet pressure signal and a target EGR valve outlet pressure signal. The fault diagnosis module is further configured to perform an inlet / outlet pressure rationality diagnosis if the EGR pressure fault diagnosis result corresponding to the target EGR valve inlet pressure signal indicates a fault in the EGR inlet pressure and the EGR pressure fault diagnosis result corresponding to the target EGR valve outlet pressure signal indicates a fault in the EGR valve outlet pressure, thereby obtaining a rationality diagnosis result. The inlet / outlet pressure rationality diagnosis includes controlling the engine to operate sequentially under multiple operating conditions with different EGR rates and monitoring the pressure response characteristics under different operating conditions. The threshold adjustment module is further configured to dynamically adjust the diagnostic threshold for the inlet / outlet pressure rationality diagnosis based on the rationality diagnosis result.

[0017] In conjunction with the second aspect, in one embodiment, the EGR pressure fault diagnosis device further includes a condition verification module, which is used for: Determine whether the EGR system meets the preset active diagnostic conditions; If the conditions are met, then proceed with the step of performing active diagnosis. If the first preset duration is not met, the EGR pressure fault diagnosis result is determined to be that there is no fault in the EGR pressure. If the target EGR valve pressure signal is the target EGR valve inlet pressure signal, then the preset active diagnosis conditions include the actual mixing valve opening, the actual EGR valve opening, the EGR valve inlet temperature fluctuation, the GPF outlet pressure fluctuation, and the EGR valve inlet pressure sensor circuit status all meeting the preset inlet active diagnosis requirements and lasting for a duration reaching the third duration threshold. If the target EGR valve pressure signal is the target EGR valve outlet pressure signal, then the preset active diagnostic conditions include a first diagnostic condition and a second diagnostic condition. The first diagnostic condition includes that the actual mixing valve opening, EGR valve inlet pressure fluctuation, EGR valve inlet temperature fluctuation, and EGR valve outlet pressure sensor circuit status all meet the preset first outlet active diagnostic requirements and the duration reaches the fourth duration threshold. The second diagnostic condition includes that the actual EGR valve opening within the target duration meets the preset second outlet active diagnostic requirements. The target duration is the duration during which the target EGR valve opening is fixed at the target EGR valve opening average value. The target EGR valve opening average value is collected under the first diagnostic condition while keeping the target EGR rate constant.

[0018] In conjunction with the second aspect, in one implementation, when the target EGR valve pressure signal is the target EGR valve inlet pressure signal, the fault diagnosis module is specifically used for: The current target EGR rate is fixed as the target EGR rate under the first sampling period when the preset active diagnostic conditions are met; Based on the target interval value, the inlet maximum value sequence and inlet minimum value sequence of the current EGR valve inlet pressure signal corresponding to the current target EGR rate are divided into intervals, and the average value of the divided intervals is calculated to obtain the inlet maximum value array and the inlet minimum value array. The target inlet array is obtained by averaging the common elements in the inlet maximum and inlet minimum arrays. The active diagnostic result of the inlet is determined based on the difference between adjacent elements in the target inlet array and the target time difference threshold.

[0019] In conjunction with the second aspect, in one embodiment, the target time difference threshold is determined based on a base time difference threshold, the average target EGR rate under preset stability conditions, the average engine speed filter value under preset stability conditions, the average EGR valve inlet temperature under preset stability conditions, the preset EGR inlet temperature value, the preset engine speed, the preset atmospheric pressure, the current actual atmospheric pressure, the preset atmospheric temperature, the actual atmospheric temperature, and a preset fitting coefficient.

[0020] In conjunction with the second aspect, in one implementation, when the target EGR valve pressure signal is the target EGR valve outlet pressure signal, the fault diagnosis module is specifically used for: Based on the target interval value, the current EGR valve outlet pressure signal is divided into intervals for the outlet maximum value sequence and the outlet minimum value sequence, and the average value of the divided intervals is calculated to obtain the outlet maximum value array and the outlet minimum value array. The target export array is obtained by averaging the common elements in the export maximum and export minimum arrays. The active diagnostic result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements.

[0021] In conjunction with the second aspect, in one embodiment, the target difference threshold is determined based on the adjacent elements themselves, the basic difference threshold, the target EGR rate that remains unchanged under the first diagnostic condition, the average value of the target EGR valve opening under the first diagnostic condition, the average value of the engine speed filter value under the preset stability condition, the average value of the EGR valve inlet temperature under the preset stability condition, the preset EGR valve inlet temperature, the preset engine speed, the preset target EGR rate, the actual EGR valve inlet pressure in the interval where the adjacent elements are located, the actual EGR valve inlet pressure filter value in the interval where the adjacent elements are located, and the preset fitting coefficient.

[0022] In conjunction with the second aspect, in one implementation, the condition verification module is further configured to: When the EGR system is detected to meet the preset stability conditions, it is determined whether the EGR system meets the preset passive diagnostic conditions. If the conditions are met, the fault diagnosis module will perform passive diagnosis. If the conditions are not met, the fault diagnosis module will not perform any diagnosis. The preset stability conditions include the engine operating state, intake system parameters, combustion state parameters, and sensor state parameters all meeting the preset stability requirements for a duration reaching a first duration threshold. The preset passive diagnostic conditions include the actual mixing valve opening, target EGR rate fluctuation, actual EGR valve opening, EGR valve inlet temperature fluctuation, GPF outlet pressure fluctuation or EGR valve inlet pressure fluctuation, and EGR valve inlet and outlet pressure sensor circuit state all meeting the preset passive diagnostic requirements for a duration reaching a second duration threshold.

[0023] The beneficial effects of the technical solutions provided in this application include: When a passive diagnostic result corresponding to the target EGR valve pressure signal is detected as indicating an EGR pressure fault, active diagnostics is performed to obtain an active diagnostic result. The active diagnostics include forcibly controlling the target EGR rate or target EGR opening to a preset state and monitoring pressure response characteristics. Based on the active diagnostic result, an EGR pressure fault diagnosis result is determined, and the diagnostic threshold of the passive diagnostics is dynamically adjusted based on the consistency between the passive and active diagnostic results. Therefore, this application accurately distinguishes between normal fluctuations and fault signals by combining active and passive diagnostics. Active diagnostics forcibly creates specific operating conditions to stimulate hidden fault characteristics, thereby significantly reducing false alarm and missed alarm rates. Simultaneously, the high confidence result of active diagnostics is used to calibrate the threshold of passive diagnostics, enabling the system to dynamically optimize the threshold based on diagnostic consistency, thus forming a self-evolving closed-loop diagnostic system to effectively reduce false alarms or missed alarms. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the EGR system structure involved in the embodiments of this application; Figure 2 This is a flowchart illustrating an embodiment of the EGR pressure fault diagnosis method of this application; Figure 3 This is a schematic diagram of the functional modules of an embodiment of the EGR pressure fault diagnosis device of this application.

[0025] In the diagram: 1-Air filter, 2-Mix valve, 3-Compressor, 4-Throttle valve, 5-Engine, 6-Turbine, 7-Catalyst, 8-GPF (Gasoline Particulate Filter), 9-EGR cooler, 10-EGR valve, 11-Temperature sensor, 12-Differential pressure sensor. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0027] First, in this embodiment, the diagnosis of EGR pressure faults will be implemented, wherein the structure of the EGR system is as follows: Figure 1As shown, it includes: an air filter 1; a mixing valve 2 connected to the air filter 1, used to regulate the pressure at the outlet of the EGR valve 10 and increase 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 inlet has a boost temperature and pressure sensor, the throttle valve outlet has an intake air temperature and pressure sensor, and the throttle valve body has a position sensor and an actuator; an engine 5 connected to the throttle valve 4, used to compress fresh air for boosting; a turbine 6 connected to the engine 5, used to control the opening of the exhaust bypass valve; and a catalytic converter connected to the turbine 6. 7; GPF8 connected to catalyst 7, with pressure sensors installed at its inlet and outlet to read the inlet and outlet exhaust gas pressure; EGR cooler 9 installed on another airflow path of mixing valve 2, one end of which is used to receive and cool the exhaust gas output from GPF8 to increase the exhaust gas flow rate, and the other end is connected to EGR valve 10 of mixing valve 2 to control the exhaust gas flow rate entering the cylinder; temperature sensor 11 installed between EGR valve 10 and EGR cooler 9 to detect the exhaust gas temperature entering EGR valve 10; differential pressure sensor 12 connected to EGR valve 10 to detect the pressure at the inlet and outlet of EGR valve 10.

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0029] In a first aspect, embodiments of this application provide an EGR pressure fault diagnosis method.

[0030] In one embodiment, reference is made to Figure 2 , Figure 2 This is a schematic flowchart illustrating an embodiment of the EGR pressure fault diagnosis method of this application. Figure 2 As shown, the EGR pressure fault diagnosis method includes: Step S10: When the passive diagnostic result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, active diagnosis is performed to obtain the active diagnostic result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to a preset state and monitoring the pressure response characteristics.

[0031] As an example, it is understandable that traditional methods typically employ a standalone passive diagnostic approach to diagnose EGR pressure faults. However, when faced with complex engine operating conditions, these methods often struggle to distinguish between normal fluctuations and fault signals, and lack effective means to trigger subtle faults such as slight drift. Consequently, it is difficult to simultaneously optimize both false alarm and false alarm rates. To overcome this problem, this embodiment introduces active diagnostics to eliminate random interference caused by transient engine operating conditions through a controlled variable method. It is understood that the sensor health status obtained by active diagnostics under steady-state conditions can be considered the 'true value'. When passive diagnostics deviates from this 'true value' under transient conditions, it can be determined as transient interference rather than sensor faults. Based on this, this embodiment integrates the control logic of active and passive diagnostics to accurately distinguish between normal fluctuations and fault signals. Furthermore, active diagnostics can be used to forcibly create specific operating conditions to trigger subtle fault characteristics, thereby significantly reducing false alarm and false alarm rates.

[0032] Specifically, after performing passive diagnosis on the target EGR valve pressure signal, if a fault is detected in the EGR pressure, since it is impossible to determine whether the fault is a normal fluctuation or a true fault signal, this embodiment will further perform active diagnosis: by forcibly controlling the target EGR rate or target EGR opening to a preset state, a specific operating condition is created to stimulate hidden fault characteristics, and fault diagnosis is performed based on the pressure response characteristics under the above operating condition. This allows for accurate identification of whether the fault determined by passive diagnosis is a normal fluctuation or a true fault signal, thereby significantly reducing the false alarm rate and missed alarm rate. It should be noted that the passive diagnosis method in this embodiment can be a traditional passive diagnosis method for EGR pressure fault diagnosis, an improved version of a traditional passive diagnosis method, or a completely new passive diagnosis method different from traditional methods; no limitation is made here. In addition, the preset state refers to the state that the target EGR rate is expected to reach or the state that the target EGR opening is expected to reach. The specific state can be determined according to actual needs. For example, if the target EGR rate is expected to remain fixed, then the target EGR rate is controlled to remain fixed; or if the target EGR opening is expected to remain fixed and needs to be maintained for a certain period of time, then the target EGR opening is controlled to remain fixed while maintaining the state for a certain period of time.

[0033] It is worth noting that during passive diagnostics, the engine speed will be checked separately. Engine speed change rate (The method for obtaining this value is the difference between the engine speed in the current sampling period and the engine speed in the previous sampling period, and then dividing the difference by the sampling period.) ), intake density of fresh air entering 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). Filtering is performed for subsequent operating condition determination; the filtering of the above parameters can be achieved using the same first-order low-pass filter formula, i.e., the formula below... It could be engine speed. Engine speed change rate Fresh air intake density entering the cylinder Throttle opening Mixing valve opening EGR valve opening GPF export pressure EGR valve inlet pressure and EGR valve outlet pressure Any one of them:

[0034] In the formula, For the first Each sampling period value, After first-order low-pass filtering value, For the first Filtered after each sampling period value, For the first Filtered after -1 sampling period value, =1,2,3,…, , ; Equal to the 0th sampling period Sampling period 10ms is preferred. The filtering coefficients are obtained using different methods for different parameters, as detailed below: 1) Engine speed Filter coefficients The method for obtaining it is as follows: Its specific value can be determined according to actual needs, and is not limited here. For example, the default value can be used. The preferred value is 0.05.

[0035] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the engine speed is in a stable state (i.e., the speed fluctuation is small); among which, the threshold coefficient and preset time The specific values ​​can be determined according to actual needs, and are not limited here, for example The preferred value is 0.05 and The preferred value is 0.1s.

[0036] 2) Engine speed change rate Filter coefficients The method for obtaining it is as follows: , The specific value can be determined according to actual needs, and is not limited here. For example, the default value can be used. The preferred value is 0.05.

[0037] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the engine speed change rate is in a stable state (i.e., the speed change rate fluctuates little); among which, the threshold coefficient and preset time The specific values ​​can be determined according to actual needs, and are not limited here, for example The preferred value is 0.05 and The preferred value is 0.1s.

[0038] 3) Intake density of fresh air entering the cylinder Filter coefficients The method for obtaining it is as follows: 3.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , The default coefficient for the fresh air intake density entering the cylinder is 1, and its specific value can be determined according to actual needs, for example, preferably 0.02. 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 reduces calibration testing work; 3.2) In other cases: , The default coefficient for the fresh air intake density entering the cylinder is 2. Its specific value can be determined according to actual needs, such as preferably 0.02.

[0039] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the intake air density is in a stable state (i.e., the intake air density fluctuation is small); among which, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.05 and The preferred value is 0.1s.

[0040] 4) Throttle opening Filter coefficients The method for obtaining it is as follows: 4.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , Throttle opening The default coefficient is 1, and its specific value can be determined according to actual needs, such as preferably 0.02; among which, 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 reduces calibration testing work; 4.2) In other cases: , Throttle opening The default coefficient is two, and its specific value can be determined according to actual needs, such as preferably 0.02.

[0041] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the throttle opening is in a stable state (i.e., the throttle fluctuation is small); among which, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The preferred value is 0.1s.

[0042] 5) Mixing valve opening Filter coefficients The method for obtaining it is as follows: 5.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , For the opening degree of the mixing valve The default coefficient is 1, and its specific value can be determined according to actual needs, such as preferably 0.02; among which, 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 reduces calibration testing work; 5.2) In other cases: , For the opening degree of the mixing valve The default coefficient is two, and its specific value can be determined according to actual needs, such as preferably 0.02.

[0043] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the opening of the mixing valve is in a stable state (i.e., the mixing valve fluctuates little); where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The preferred value is 0.1s.

[0044] 6) EGR valve opening Filter coefficients The method for obtaining it is as follows: 6.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , EGR valve opening The default coefficient is 1, and its specific value can be determined according to actual needs, such as preferably 0.02; among which, 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 reduces calibration testing work; 6.2) In other cases: , EGR valve opening The default coefficient is two, and its specific value can be determined according to actual needs, such as preferably 0.02.

[0045] It should be noted that, in The conditions are met continuously for a preset time. After that, it indicates that the EGR valve opening is in a stable state (i.e., the EGR valve fluctuation is small); where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The preferred value is 0.1s.

[0046] 7) GPF export pressure Filter coefficients The method for obtaining it is as follows: 7.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , This is the default coefficient for GPF outlet pressure, and its specific value can be determined according to actual needs, such as preferably 0.2; where, 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 reduces calibration testing work; 7.2) In other cases: , The default coefficient for GPF outlet pressure is 2, and its specific value can be determined according to actual needs, such as preferably 0.2; it is worth noting that, The filter coefficient should be no less than that for engine speed, engine speed change rate, fresh air intake density, throttle opening, and mixing valve opening. These factors are used to verify the EGR inlet pressure, requiring stable operating conditions. Therefore, their filter coefficients need to be relatively small. However, the filter coefficient for the GPF outlet pressure should not be too small; otherwise, excessive smoothing will lead to an overly smoothed EGR valve inlet pressure, potentially causing incorrect assessments of EGR pressure. The purpose of GPF filtering is to prevent excessive fluctuations in EGR inlet pressure caused by exhaust flow disturbances, which could make it impossible to determine if the pressure signal is abnormal.

[0047] 8) EGR valve inlet pressure Filter coefficients The method for obtaining it is as follows: 8.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , This is the default coefficient for the EGR valve inlet pressure; its specific value can be determined according to actual needs, for example, a preferred value is 0.2. 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 reduces calibration testing work; 8.2) In other cases: , The default coefficient for the EGR valve inlet pressure is two; its specific value can be determined according to actual needs, for example, a preferred value is 0.2. It is worth noting that... The filter coefficient should not be less than the 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 conditions for checking EGR pressure. These conditions require stable operating conditions, so it is necessary to ensure that they are in a stable state. Therefore, their filter coefficients are relatively small. However, the filter coefficient of the EGR valve inlet pressure should not be too small, otherwise it is easy to make an incorrect assessment of whether the EGR pressure is normal.

[0048] 9) EGR valve outlet pressure Filter coefficients The method for obtaining it is as follows: 9.1) If both the engine speed and the rate of change of engine speed are in a steady state, then: , This is the default coefficient for the EGR valve outlet pressure; its specific value can be determined according to actual needs, for example, a preferred value is 0.2. 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 reduces calibration testing work; 9.2) In other cases: , The default coefficient for the EGR valve outlet pressure is two, and its specific value can be determined according to actual needs, such as preferably 0.2. It is worth noting that... The filtering coefficient should not be less than the filtering coefficients 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 conditions for checking EGR pressure. These conditions require stable operating conditions, so it is necessary to ensure that they are in a stable state. Therefore, their filtering coefficients are relatively small. However, the filtering coefficient of the EGR valve outlet pressure should not be too small, otherwise it is easy to make an incorrect assessment of whether the EGR pressure is normal.

[0049] Based on this, when the original signal of the EGR valve pressure is acquired, the original signal can be filtered by the above filtering coefficients to obtain the target EGR valve pressure signal; then passive diagnosis is performed based on the target EGR valve pressure signal.

[0050] Furthermore, in one embodiment, the method further includes: When the EGR system is detected to meet the preset stability conditions, it is determined whether the EGR system meets the preset passive diagnostic conditions. If the conditions are met, then perform a passive diagnosis. If the conditions are not met, no diagnosis will be performed; The preset stability conditions include the engine operating state, intake system parameters, combustion state parameters, and sensor state parameters all meeting the preset stability requirements for a duration reaching a first duration threshold. The preset passive diagnostic conditions include the actual mixing valve opening, target EGR rate fluctuation, actual EGR valve opening, EGR valve inlet temperature fluctuation, GPF outlet pressure fluctuation or EGR valve inlet pressure fluctuation, and EGR valve inlet and outlet pressure sensor circuit state all meeting the preset passive diagnostic requirements for a duration reaching a second duration threshold.

[0051] As an example, in this embodiment, the EGR valve inlet pressure check of the EGR system can preferably be performed under the following steady-state conditions (i.e., the preset stability requirements include the following): (1) The engine is running; (2) The engine speed is within a certain range. In this embodiment, it is preferably between 600 rpm and 5900 rpm, and the engine speed enters a stable state after entering the EGR system pressure check (the specific identification method of this stable state is detailed in the aforementioned embodiment, and will not be repeated here). (3) The fresh air intake density entering the cylinder is within a certain range. In this embodiment, it is preferably between 200 mgpl and 3000 mgpl, and the intake density after entering the EGR system pressure check enters a stable state (the specific identification method of this stable state is detailed in the aforementioned embodiment, and will not be repeated here). (4) Throttle opening The system enters a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). (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). (6) The target air-fuel ratio fluctuation (i.e. the difference between the target air-fuel ratios of two adjacent sampling periods) is within a certain range, and in this embodiment, ±0.1 is preferably selected; (7) The fluctuation of the difference between the target air-fuel ratio and the actual air-fuel ratio (i.e., the difference between the target air-fuel ratio and the actual air-fuel ratio in two adjacent sampling periods) is within a certain range. In this embodiment, ±0.1 is preferred. (8) The actual air-fuel ratio fluctuation (i.e. the difference between the actual air-fuel ratios of two adjacent sampling periods) is within a certain range, and in this embodiment, ±0.1 is preferably selected; (9) The engine coolant temperature is within a certain range (preferably 0℃ to 100℃ in this embodiment), and the engine coolant temperature fluctuation after entering the EGR system pressure check (i.e. the difference between engine coolant temperatures in two adjacent sampling cycles) is small. In this embodiment, ±2℃ is preferred. (10) The intake temperature is within a certain range (preferably 30°C to 80°C in this embodiment), and the intake temperature fluctuation after entering the EGR system pressure check (i.e., the difference between the intake temperatures of two adjacent sampling cycles) is small. In this embodiment, ±1.5°C is preferred. (11) The ignition angle efficiency fluctuation (i.e. the difference in ignition angle efficiency between two adjacent sampling periods) is small, and in this embodiment, ±0.1 is preferred; (12) No detonation or pre-ignition occurred; (13) The engine did not experience fuel cut-off; (14) Both the oxygen sensor before and after the catalyst have been activated by heating. (15) The atmospheric pressure fluctuation (i.e. the difference in atmospheric pressure between two adjacent sampling periods) is small. In this embodiment, ±0.5 kPa is preferred. (16) No fire malfunction occurred; (17) No EGR system pressure signal fault was detected during this vehicle driving cycle.

[0052] It should be understood that, after all the above conditions are met, the following stability condition must also be met before the EGR system pressure signal can be checked: the duration of all the above conditions being met exceeds the first duration threshold, thus confirming that the EGR system meets the stability condition; wherein, the specific value of the first duration threshold t0 can be determined according to actual needs, for example, in this embodiment, it can be preferably taken as 5s.

[0053] After the EGR system meets the preset stability conditions, it is necessary to further determine whether the EGR system meets the preset passive diagnostic conditions. These preset passive diagnostic conditions include inlet pressure passive diagnostic conditions and outlet pressure passive diagnostic conditions, and both the inlet pressure passive diagnostic conditions and the outlet pressure passive diagnostic conditions include the following: 1) Actual mixing valve opening Fully open, meaning the mixing valve is at its maximum opening. 2) Target EGR rate The fluctuation (i.e., the difference between the target EGR rates of two adjacent sampling periods) is within a certain range, and in this embodiment, it is preferably ±0.02; 3) The actual EGR valve opening is in a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 4) The EGR valve inlet temperature fluctuation (i.e., the difference between the EGR valve inlet temperature in two adjacent sampling periods) is small. In this embodiment, ±3℃ is preferred. 5) No EGR valve inlet pressure sensor circuit failure occurred (such as any circuit failure including open circuit or short circuit); In addition, the preset passive diagnostic requirements in the inlet pressure passive diagnostic conditions also include 6) controlling the GPF outlet pressure fluctuation to be small, that is, satisfying: The conditions are met continuously for a preset time. After that, it indicates that the GPF outlet pressure is in a stable state; where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The preferred value is 0.05s; The preset passive diagnostic requirements in the outlet pressure passive diagnostic conditions also include 6) controlling the EGR valve inlet pressure fluctuation to be small, that is, satisfying: The conditions are met continuously for a preset time. After that, it indicates that the EGR valve inlet pressure is in a stable state; where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The optimal value is 0.05s.

[0054] It should be understood that if all the above conditions are met and the duration exceeds the second duration threshold t1, the preset passive diagnostic conditions are considered met. The specific value of the second duration threshold t1 can be determined according to actual needs; for example, in this embodiment, 5 seconds is preferred. It should be noted that if EGR pressure fault diagnosis requires separate inlet and outlet diagnoses, the EGR system is judged to meet the corresponding passive diagnostic conditions based on the inlet pressure passive diagnostic conditions and the outlet pressure passive diagnostic conditions. If neither is met, no diagnosis is performed. If the inlet pressure passive diagnostic conditions are met, inlet pressure passive diagnosis is performed; if the outlet pressure passive diagnostic conditions are met, outlet pressure passive diagnosis is performed.

[0055] It is worth noting that if, during the passive diagnostic condition assessment, the EGR valve opening becomes unstable, the control time t1 in the next assessment will be increased by a preset value relative to the previous passive diagnostic condition assessment time (the specific value can be determined according to actual needs, such as preferably 0.05s). If the current passive diagnostic process records that the previous passive diagnostic condition assessment did not show the EGR valve opening becoming unstable, then t1 will be restored to its initial value in the next passive diagnostic condition assessment. The purpose of this dynamic adjustment of t1 is to avoid misjudgments caused by EGR valve opening fluctuations in the pressure fluctuation verification.

[0056] The EGR system pressure fluctuation can only be checked after all stability and passive diagnostic conditions are met. If the stability or passive diagnostic conditions are not met, or if the stability or passive diagnostic conditions are not met during the process of checking the EGR system pressure fluctuation, the check of the EGR system pressure fluctuation will be stopped and characterized as a fault not detected.

[0057] In this embodiment, before performing passive diagnostics on the inlet and outlet, it is preferable to filter the EGR valve inlet pressure and EGR valve outlet pressure (the original sensor pressure values ​​read) using three different filtering coefficients. The filtering algorithm is the same as above, i.e.:

[0058] Among them, the three filter coefficients corresponding to the inlet pressure They are respectively , and Furthermore, different filter coefficients result in different filtered inlet pressures. , and Similarly, the filter coefficient for the outlet pressure... They are respectively , and And different filter coefficients result in different filtered outlet pressures. , and .

[0059] Specifically, the filter coefficient for inlet pressure In other words, , and Constant values ​​can be taken separately. , and ,and , and The specific value can be determined according to actual needs or obtained through bench calibration, for example... , and The optimal values ​​can be 0.2, 0.1, and 0.05, respectively; similarly, the filter coefficient for the outlet pressure... In other words, , and Constant values ​​can be taken separately. , and ,and , and The specific value can be determined according to actual needs or obtained through bench calibration, for example... , and The optimal values ​​are 0.15, 0.08, and 0.05, respectively.

[0060] Based on this, the following passive diagnostic method can be preferred for checking inlet pressure fluctuations: Filtered inlet pressure , and After calculating the pressure difference between adjacent sampling periods (i.e., the inlet pressure in the current sampling period minus the inlet pressure in the previous sampling period), a correlation is formed with... The corresponding difference sequence [ , …],and The corresponding difference sequence [ , …]and with The corresponding difference sequence [ , …]; Based on this, if any of the following conditions occur, it indicates that a passive diagnostic fault has occurred in the EGR valve inlet pressure: First scenario: [This occurs] >0、 <0 and <0, and Not less than the first entry passive diagnosis threshold , i=1,2,3..., where, It should be noted that, This is the learning coefficient for the first entry pressure. Its default value can be preferably 0. It can continuously learn and update itself, and the updated value will be saved immediately. The learning values ​​for all operating conditions will be updated each time.

[0061] The second scenario: <0、 >0 and >0, and Not less than the first entry passive diagnosis threshold ; The third scenario: [This occurs] >0、 >0 and <0, and Not less than the passive diagnostic threshold of the second entry point ,in, It should be noted that, This is the learning coefficient for the second entry pressure. Its default value can be preferably 0. It can continuously learn and update, and the updated value will be saved immediately. The learning values ​​for all operating conditions will be updated each time.

[0062] The fourth scenario: occurs <0、 <0 and >0, and Not less than the passive diagnostic threshold of the second entry point ; in, The average target EGR rate under stability conditions. This represents the average value of the filtered engine speed under stability conditions. The default engine speed is 1000 rpm, which is preferred in this embodiment; the default input speed is... and It can be obtained by benchmarking and fitting data from faulty pressure sensors and non-faulty pressure sensors; for example, both can be preferably set to 0.23.

[0063] It is understandable that if any one of the above four conditions is met, the passive diagnosis result is that there is a fault in the EGR inlet pressure; if none of the four conditions are met, the passive diagnosis result is that there is no fault in the EGR inlet pressure.

[0064] Similarly, for verifying fluctuations in export pressure, the following passive diagnostic methods can be preferred: The filtered outlet pressure , and Calculate the pressure difference between adjacent sampling periods to form a correlation between the pressure difference and the pressure difference between the two periods. The corresponding difference sequence [ , …],and The corresponding difference sequence [ , …]and with The corresponding difference sequence [ , …]; Based on this, if any of the following conditions occur, it indicates that a passive diagnostic fault has occurred in the EGR valve outlet pressure: First scenario: [This occurs] >0、 <0 and <0, and Not less than the passive diagnostic threshold of the first exit ,in, It should be noted that, This is the learning coefficient for the first export pressure. Its default value can be preferably 0. It can continuously learn and update itself, and the updated value will be saved immediately. The learning values ​​for all operating conditions will be updated each time.

[0065] The second scenario: <0、 >0 and >0, and Not less than the passive diagnostic threshold of the first exit ; The third scenario: [This occurs] >0、 >0 and <0, and Not less than the passive diagnostic threshold of the second exit ,in, It should be noted that, This is the learning coefficient for the second outlet pressure. Its default value can be preferably 0. It can continuously learn and update itself, and the updated value is saved immediately. The learning values ​​for all operating conditions will be updated each time.

[0066] The fourth scenario: occurs <0、 <0 and >0, and Not less than the passive diagnostic threshold of the second exit ; in, The average target EGR rate under stability conditions. This represents the average inlet pressure of the EGR valve under stability conditions. This represents the average value of the filtered engine speed under stability conditions. The default EGR valve inlet pressure is 101 kPa, which is preferably selected in this embodiment. The default engine speed is 1000 rpm, which can be preferably selected in this embodiment; and Average inlet pressure of EGR valve under stability conditions With the default EGR valve inlet pressure ratio Determined, i.e., different sizes Corresponding , They are all different, among which and The specific value can be obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors; in addition, the default value for the outlet... and This can be obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors; ideally, both can be set to 0.2. It is worth noting that when checking for fluctuations in outlet pressure, the following should be considered... The reason is that fluctuations in the EGR valve inlet pressure greatly affect fluctuations in the outlet pressure, so corrections are needed accordingly.

[0067] It is understandable that if any one of the above four conditions is met, the passive diagnosis result is that there is a fault in the EGR outlet pressure; if none of the four conditions are met, the passive diagnosis result is that there is no fault in the EGR outlet pressure.

[0068] Furthermore, in one embodiment, prior to the step of performing active diagnosis, the method further includes: Determine whether the EGR system meets the preset active diagnostic conditions; If the conditions are met, then proceed with the step of performing active diagnosis. If the first preset duration is not met, the EGR pressure fault diagnosis result is determined to be that there is no fault in the EGR pressure. If the target EGR valve pressure signal is the target EGR valve inlet pressure signal, then the preset active diagnosis conditions include the actual mixing valve opening, the actual EGR valve opening, the EGR valve inlet temperature fluctuation, the GPF outlet pressure fluctuation, and the EGR valve inlet pressure sensor circuit status all meeting the preset inlet active diagnosis requirements and lasting for a duration reaching the third duration threshold. If the target EGR valve pressure signal is the target EGR valve outlet pressure signal, then the preset active diagnostic conditions include a first diagnostic condition and a second diagnostic condition. The first diagnostic condition includes that the actual mixing valve opening, EGR valve inlet pressure fluctuation, EGR valve inlet temperature fluctuation, and EGR valve outlet pressure sensor circuit status all meet the preset first outlet active diagnostic requirements and the duration reaches the fourth duration threshold. The second diagnostic condition includes that the actual EGR valve opening within the target duration meets the preset second outlet active diagnostic requirements. The target duration is the duration during which the target EGR valve opening is fixed at the target EGR valve opening average value. The target EGR valve opening average value is collected under the first diagnostic condition while keeping the target EGR rate constant.

[0069] As an example, in this embodiment, the preset active diagnostic conditions include inlet pressure active diagnostic conditions and outlet pressure active diagnostic conditions; wherein, the preset inlet active diagnostic requirements in the inlet pressure active diagnostic conditions include: 1) The aforementioned stability conditions are met (i.e., all 17 conditions are met and the duration reaches t0). 2) Actual mixing valve opening The system enters a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 3) The actual EGR valve opening is in a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 4) The EGR valve inlet temperature fluctuation (i.e., the difference between the EGR valve inlet temperature in two adjacent sampling periods) is small. In this embodiment, ±3℃ is preferred. 5) The GPF outlet pressure fluctuation is small, i.e., it meets the following condition: The conditions are met continuously for a preset time. After that, it indicates that the GPF outlet pressure is in a stable state; where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The optimal value is 0.05s.

[0070] 6) No EGR valve inlet pressure sensor circuit failure occurred (such as any circuit failure including open circuit or short circuit); It should be understood that if all the above conditions are met simultaneously and the duration exceeds the third duration threshold T1, then the inlet pressure active diagnosis condition is considered met. Here, T1 = t2 + t3. For t2, if the EGR valve is closed, then t2 represents the time it takes for exhaust gas to flow from the GPF outlet to the EGR valve inlet. Its specific value can be obtained through bench calibration. For example, during bench calibration, the engine speed and the fresh air intake density into the cylinder can be fixed, and the EGR valve closed. Then, by adjusting various data sampling methods, the exhaust gas flow from the GPF... The average time it takes for the exhaust gas to flow from the GPF outlet to the EGR valve inlet is taken as t2. If the EGR valve is not closed, then t2 represents the time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet. The specific value can also be obtained from bench calibration: for example, when performing bench calibration, the engine speed and the fresh air intake density entering the cylinder can be fixed, and different EGR valve openings can be fixed. Then, the average time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet can be obtained by adjusting various data sampling, and the average time is taken as t2.

[0071] It should be noted that when setting T1, t2 is considered to ensure that the EGR inlet pressure is not affected by GPF and mixing valves, thus preventing erroneous interference and ensuring the EGR valve inlet pressure operates under stable conditions, thereby avoiding incorrect inlet pressure judgments. t3 is considered to ensure sufficient samples to calculate the average EGR inlet pressure; otherwise, the accuracy of pressure fluctuation signal verification will be inaccurate. Specifically, for t3, if the EGR valve is closed, N1 × As t3, sampling period The specific value can be determined according to actual needs, such as preferably 10ms; N1 represents the delay number one, which can be determined by the average value of the engine speed filter value in the stability condition. That is, the larger the average value of the engine speed filter value, the larger N1 needs to be set in order to ensure stable operating conditions and the accuracy of pressure signal verification. See Table 1 for details.

[0072] Table 1 Delay Count Mapping Table

[0073] N1 is determined by looking up the average value of the engine speed filter value in the stability conditions in Table 1 above. The lookup method for N1 is to take the larger value in the lookup results but not exceeding the maximum and minimum values ​​in the lookup table: (1) If the average value of the engine speed filter value in the stability conditions is greater than 1000 rpm but less than 1400 rpm, then N1 is 260; (2) If the average value of the engine speed filter value in the stability conditions is not greater than 600 rpm, then N1 is 200; (3) If the average value of the engine speed filter value in the stability conditions is greater than 5700 rpm, then N1 is 350. It should be noted that Table 1 above is only a presentation of an embodiment, and the specific values ​​in Table 1 can be adaptively adjusted according to actual needs.

[0074] If the EGR valve is not closed, then N2× As t3; N2 represents the second delay. N2 is determined by the average value of the engine speed filter value and the average value of the EGR valve opening in the stability conditions. That is, the larger the average value of the engine speed filter value and the larger the average value of the EGR valve opening, the larger N2 needs to be set in order to ensure stable operating conditions and the accuracy of pressure signal verification. See Table 2 for details.

[0075] Table 2 Delay Count Mapping Table

[0076] It should be noted that the lookup method for N2 is similar to that for N1, and will not be repeated here for the sake of brevity. Furthermore, Table 2 above is merely an example; the specific values ​​in Table 2 can be adjusted according to actual needs.

[0077] Therefore, active diagnosis of EGR inlet pressure can only be performed after all inlet pressure active diagnosis conditions are met. If the stability condition or the inlet pressure active diagnosis condition is not met and the first preset duration is continuously maintained (the specific value is determined according to actual needs, such as setting it to the duration of the current power-on to power-off driving cycle), or if the stability condition or the inlet pressure active diagnosis condition is not met during the EGR inlet pressure active diagnosis check, then the active diagnosis of EGR inlet pressure will be stopped and characterized as a fault not detected.

[0078] Furthermore, the proactive export pressure diagnosis conditions include a first diagnosis condition and a second diagnosis condition; among which, the preset first proactive export diagnosis requirements in the first diagnosis condition include: 1) The aforementioned stability conditions are met (i.e., all 17 conditions are met and the duration reaches t0). 2) Actual mixing valve opening The system enters a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 3) The EGR valve inlet pressure fluctuation is small, i.e., it meets the following condition: The conditions are met continuously for a preset time. After that, it indicates that the EGR valve inlet pressure is in a stable state; where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The optimal value is 0.05s.

[0079] 4) The actual EGR valve opening is in a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 5) The EGR valve inlet temperature fluctuation (i.e., the difference between the EGR valve inlet temperatures of two adjacent sampling periods) is small, and in this embodiment, ±3℃ is preferred; 6) No EGR valve inlet pressure sensor circuit failure occurred (such as any circuit failure including open circuit or short circuit); It should be understood that if all the above conditions are met and the duration exceeds the fourth duration threshold T2, then the first diagnostic condition is considered to be met; the specific value of T2 can be determined according to actual needs, for example, in this embodiment, 0.5s is preferred.

[0080] It is worth noting that after the first diagnostic condition is met, the target EGR rate of the active control is kept constant so that the second diagnostic condition is checked under the condition of a constant target EGR rate. Therefore, for the second diagnostic condition, it is necessary to read the average value of the target EGR valve opening within t4 hours after the first diagnostic condition is met. The specific value of t4 can be determined according to actual needs, such as by selecting the optimal value. , The specific value can also be determined according to actual needs, such as taking 0.2s. The average engine speed after filtering during the stability process is set, and the current target EGR valve opening is forcibly fixed at [value]. The target duration t5 remains unchanged and is maintained. Based on this, the second diagnostic condition includes that the actual EGR valve opening within the duration t5 meets the preset second outlet active diagnostic requirement, and the preset second outlet active diagnostic requirement is that the actual EGR valve opening is in a stable state (the specific identification method of this stable state is detailed in the aforementioned embodiment and will not be repeated here). In other words, if the actual EGR valve opening is in a stable state within the duration t5, it is determined that the second diagnostic condition is met, and if the EGR valve opening is not in a stable state within the duration t5, the outlet pressure active diagnostic is terminated.

[0081] The acquisition of t5 can preferably be achieved through the following methods: (1) If the EGR valve is closed, t5 represents the time it takes for fresh air to flow from the outlet of the mixing valve to the inlet of the turbocharger. Its specific value can be obtained through bench calibration: When performing bench calibration, the engine speed and the intake density of fresh air entering the cylinder can be fixed, and the EGR valve can be closed. Then, the average time of fresh air flowing from the outlet of the mixing valve to the inlet of the turbocharger can be obtained by debugging various data sampling, and the average time is taken as t5.

[0082] (2) If the EGR valve is not closed, then t5 represents the time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet. Its specific value can be obtained through bench calibration: When performing bench calibration, the engine speed and the fresh air intake density entering the cylinder can be fixed, and different EGR valve openings can be fixed. Then, the average time of the exhaust gas flowing from the GPF outlet to the mixing valve outlet can be obtained by debugging various data sampling, and this average time is taken as t5.

[0083] It should be noted that active diagnosis of EGR outlet pressure stability can only be performed after all active diagnostic conditions for outlet pressure are met simultaneously. If any of the stability condition, the first diagnostic condition, or the second diagnostic condition is not met, or if any of the stability condition, the first diagnostic condition, or the second diagnostic condition suddenly becomes unmet during the active diagnostic verification of EGR outlet pressure, the active diagnostic verification of EGR outlet pressure will be stopped, and the fault will be indicated as not being detected.

[0084] Further, in one embodiment, when the target EGR valve pressure signal is the target EGR valve inlet pressure signal, the step of performing active diagnosis and obtaining active diagnosis results includes: The current target EGR rate is fixed as the target EGR rate under the first sampling period when the preset active diagnostic conditions are met; Based on the target interval value, the inlet maximum value sequence and inlet minimum value sequence of the current EGR valve inlet pressure signal corresponding to the current target EGR rate are divided into intervals, and the average value of the divided intervals is calculated to obtain the inlet maximum value array and the inlet minimum value array. The target inlet array is obtained by averaging the common elements in the inlet maximum and inlet minimum arrays. The active diagnostic result of the inlet is determined based on the difference between adjacent elements in the target inlet array and the target time difference threshold.

[0085] The target time difference threshold is determined based on the base time difference threshold, the average target EGR rate under preset stability conditions, the average engine speed filter value under preset stability conditions, the average EGR valve inlet temperature under preset stability conditions, the preset EGR inlet temperature value, the preset engine speed, the preset atmospheric pressure, the current actual atmospheric pressure, the preset atmospheric temperature, the actual atmospheric temperature, and the preset fitting coefficient.

[0086] As an example, in this embodiment, for inlet pressure diagnosis, when the EGR system meets the inlet pressure active diagnosis conditions, the target EGR rate at the first sampling period at the time of the inlet pressure active diagnosis condition is read, and the current target EGR rate is actively and strongly controlled. The target EGR rate for the first sampling period is set and kept constant. Then, the raw signal of the EGR valve inlet pressure under this operating condition is acquired and subjected to first and second filtering in sequence. The first filtering removes high-frequency noise, and the second filtering further smooths the signal, thus achieving secondary purification of the pressure signal. This cascaded filtering method can effectively improve the purity of the signal and significantly reduce the interference of noise on the diagnostic logic.

[0087] Obtain the EGR inlet pressure after secondary filtering (i.e., the current EGR valve inlet pressure signal), and read the EGR inlet pressure after secondary filtering within the time T after the rejection time t2 (the specific value can be determined according to actual needs). The maximum and minimum values ​​are recorded as the entry maximum sequence [pmax0, pmax1, ...] and the entry minimum sequence [pmin0, pmin1, ...], respectively; where pmax0 is the first sampling period within time T after the removal time t2 (sampling period interval). The maximum value of the EGR inlet pressure read, pmax1 is the second sampling period within time T after the rejection time t2 (sampling period interval). The maximum value of the EGR inlet pressure read, and so on; pmin0 is the first sampling period within time T after the rejection time t2 (sampling period interval). The minimum value of the EGR inlet pressure read, pmin1 is the second sampling period within time T after the rejection time t2 (sampling period interval). The minimum value of the EGR inlet pressure is read, and so on.

[0088] Then, the ingress maximum and minimum sequences are divided into intervals using target interval values. These target interval values ​​can be specific values ​​obtained through experimental calibration, or they can be obtained using the aforementioned N1 and N2. Round down to obtain the target interval value M1, which is a positive integer. Specifically, with M1 as the interval, continuously record the average value of the maximum value to form the entry maximum value array [p1maxAvg0, p1maxAvg1, …]; at the same time, with M1 as the interval, continuously record the average value of the minimum value to form the entry minimum value array [p1minAvg0, p1minAvg1, …].

[0089] Averaging the maximum and minimum values ​​of the above entry maximum and minimum value arrays along the same dimension (i.e., the same elements in the two arrays) again yields the target entry array [p1Avg0, p1Avg1,…], where p1Avg0 = (p1maxAvg0 + p1minAvg0) / 2, and similarly, p1Avg1 = (p1maxAvg1 + p1minAvg1) / 2, and so on. Then, the time difference between consecutive average values ​​in the target entry array is calculated, i.e., the difference between adjacent elements in the target entry array is calculated, such as subtracting p1Avg0 from p1Avg1 to obtain the average time difference. Subtracting p1Avg1 from p1Avg2 gives the average time difference. And so on, forming an entry time difference array [ , [, …]; Then, the active diagnosis result for the ingress is determined based on the ingress time difference array and the target time difference threshold. It should be noted that the target time difference threshold… It can be determined based on actual needs, or it can be based on a baseline time difference threshold. The average target EGR rate under preset stability conditions The average value of the engine speed filter under preset stability conditions Average inlet temperature of EGR valve under preset stability conditions Preset EGR inlet temperature value Preset engine speed Preset atmospheric pressure Current actual atmospheric pressure Preset atmospheric temperature Actual atmospheric temperature And the preset fitting coefficients are determined, that is:

[0090] in, As the default EGR valve inlet temperature, 550°C is preferably selected in this embodiment; As the default engine speed, 1000 rpm can be preferably selected in this embodiment; As the default atmospheric pressure, standard atmospheric pressure is used in this embodiment; The value is 101 kPa; As the default atmospheric temperature, 20°C is preferably selected in this embodiment.

[0091] This can be obtained through testing on an engine bench. During bench testing, when the engine speed change is not in a stable state, both the stability condition and the active inlet pressure diagnosis condition must be met simultaneously. Furthermore, tests are conducted at different engine speeds and with different intake air densities under various external engine characteristics. The inlet time difference arrays under conditions of no pressure sensor failure and pressure sensor failure are used to construct statistical data S1 and S2, respectively. Assuming they both follow a normal distribution, then... After setting, ensure that the pressure sensor is not faulty and that the data when a pressure sensor fault occurs meets the three-standard-deviation principle:

[0092] in, and The average time difference between when the pressure sensor is not faulty and when a pressure sensor fault occurs, obtained from a large number of data samples (i.e., data samples at engine universal characteristic operating points corresponding to different engine speeds and different fresh air intake densities entering the cylinder, each no less than 5000). The average value; and The average time difference between when the pressure sensor is not faulty and when a pressure sensor fault occurs, obtained from a large number of data samples (i.e., data samples at engine universal characteristic operating points corresponding to different engine speeds and different fresh air intake densities entering the cylinder, each no less than 5000). The standard deviation of [the value]. Based on this, the standard deviation can be obtained through the above bench calibration. .

[0093] further, and All are preset fitting coefficients, which can be adjusted in different ways. The following data is obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors, and the preferred values ​​for both are 0.052 and 0.04, respectively. Furthermore, correction coefficients... Based on , , and Determined, i.e., different sizes , , and Corresponding They are all different; similarly, Based on , , and Determined, i.e., different sizes , , and Corresponding They are all different; among them, and All coefficients are obtained based on calibration under different atmospheric pressures and temperatures. The main calibration method is as follows: determined based on faulty and non-faulty pressure sensors, i.e., statistical data from faulty and non-faulty pressure sensors are collected from the actual vehicle, and the correction coefficient is determined using the three-standard-deviation principle. and .

[0094] For determining the active diagnosis result of the ingress based on the ingress time difference array and the target time difference threshold, specifically: if the ingress time difference array [ , The consecutive occurrence of values ​​not less than the target time difference threshold in [, …] If the number of times reaches the threshold number CNT1, it indicates that the EGR valve inlet pressure active diagnosis fault has occurred, that is, the EGR valve inlet pressure fault has actually occurred, and the result of active diagnosis is that there is a fault in the EGR inlet pressure; otherwise, it indicates that the pressure signal fault has not occurred.

[0095] It is worth noting that in this embodiment, the threshold number CNT1 can be dynamically adjusted based on whether the EGR valve is closed; if the EGR valve is closed, the absolute value of the average fresh air intake flow rate entering the cylinder under stability conditions is used. Compared to the default preset fresh air intake flow rate (It is preferable to select a ratio of 10g / s) To determine the threshold number CNT1, i.e., CNT1 = V1, as shown in Table 3: Table 3 Threshold Count Mapping Table

[0096] As shown in Table 3, the larger the absolute value of the average fresh air intake flow rate, the greater the potential flow disturbance in the exhaust system. Therefore, V1 should be larger to avoid the impact of flow disturbance. It should be noted that the lookup method for V1 is similar to that for N1, and will not be repeated here for the sake of simplicity. Furthermore, Table 3 is only a presentation of an example, and the specific values ​​in Table 3 can be adaptively adjusted according to actual needs.

[0097] If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder under stability conditions. Compared to the default fresh air intake flow rate ratio The threshold number CNT1 is determined, i.e., CNT1 = V2, as shown in Table 4: Table 4 Threshold Count Mapping Table

[0098] Similarly, the larger the absolute value of the average fresh air intake flow rate, the greater the flow disturbance of the exhaust system may be, and therefore V2 should be larger to avoid the impact caused by the flow disturbance. It should be noted that V2 is not less than V1. In addition, Table 4 above is only a presentation of an example, and the specific values ​​in Table 4 can be adaptively adjusted according to actual needs.

[0099] It should be noted that if the stability condition is not met when the EGR valve switches between the closed and open states, the pressure signal verification will be terminated.

[0100] Further, in one embodiment, when the target EGR valve pressure signal is the target EGR valve outlet pressure signal, the step of performing active diagnosis and obtaining active diagnosis results includes: Based on the target interval value, the current EGR valve outlet pressure signal is divided into intervals for the outlet maximum value sequence and the outlet minimum value sequence, and the average value of the divided intervals is calculated to obtain the outlet maximum value array and the outlet minimum value array. The target export array is obtained by averaging the common elements in the export maximum and export minimum arrays. The active diagnostic result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements.

[0101] The target difference threshold is determined based on the adjacent elements themselves, the basic difference threshold, the target EGR rate that remains unchanged under the first diagnostic condition, the average value of the target EGR valve opening under the first diagnostic condition, the average value of the engine speed filter value under the preset stability condition, the average value of the EGR valve inlet temperature under the preset stability condition, the preset EGR valve inlet temperature, the preset engine speed, the preset target EGR rate, the actual EGR valve inlet pressure in the interval where the adjacent elements are located, the actual EGR valve inlet pressure filter value in the interval where the adjacent elements are located, and the preset fitting coefficient.

[0102] As an example, in this embodiment, for outlet pressure diagnosis, when the EGR system meets the second diagnostic condition in the active outlet pressure diagnosis conditions, that is, the current target EGR valve opening under the second diagnostic condition is forcibly fixed to the average value of the target EGR valve opening over a time period t4. The raw signal of the EGR valve outlet pressure under this operating condition is acquired and filtered once; then the filtered EGR outlet pressure is read. The maximum and minimum values ​​of the current EGR valve outlet pressure signal are recorded as the outlet maximum sequence [pmax0, pmax1, …] and the outlet minimum sequence [pmin0, pmin1, …], respectively. Here, pmax0 represents the first sampling period (sampling period interval) after all stability and second diagnostic conditions are met. The maximum value of the EGR outlet pressure read, pmax1 is the second sampling period after all stability conditions and the second diagnostic conditions are met (sampling period interval). The maximum value of the EGR outlet pressure read, and so on; pmin0 is the first sampling period (sampling period interval) after all stability conditions and the second diagnostic conditions are met. The minimum value of the EGR outlet pressure read, pmin1 is the second sampling period after all stability conditions and the second diagnostic conditions are met (sampling period interval). The minimum value of the EGR outlet pressure read, and so on.

[0103] In this embodiment, the maximum and minimum values ​​of the first M2 sampling periods are preferably removed to avoid signal instability in the early stages of stable testing conditions, which could affect the accuracy of the pressure signal test. The value of M2 can be obtained from Table 5 based on the average value of the engine speed filter value when the stability condition is met. Table 5 M2 Value Mapping Table

[0104] Based on this, M2 is determined by referring to Table 5 above according to the average value of the engine speed filter value in the stability conditions; where M2 is finally taken as the larger value in the table lookup results, but does not exceed the maximum and minimum values ​​in the table: (1) If the average value of the engine speed filter value in the stability conditions is greater than 1000 rpm but less than 1400 rpm, then M2 is 5; (2) If the average value of the engine speed filter value in the stability conditions is not greater than 600 rpm, then M2 is 2; (3) If the average value of the engine speed filter value in the stability conditions is greater than 5700 rpm, then M2 is 12. It should be noted that Table 5 above is only a presentation of the embodiment, and the specific values ​​in Table 5 can be adaptively adjusted according to actual needs.

[0105] After removing the maxima and minima from the first M2 sampling periods of the export maxima and minima sequences respectively, the two sequences are divided into intervals according to M1 (M1=50 in this embodiment is preferred). The average of the maxima and minima in each M1 interval of the two sequences is calculated to form the export maxima array [pmaxAvg0, pmaxAvg1, …] and the export minima array [pminAvg0, pminAvg1, …]. In particular, if any element pmaxAvgQ (Q=0,1,2,3…) in the export maxima array or any element pminAvgR (R=0,1,2,3…) in the export minima array is equal to 0, the maxima and minima corresponding to element Q, as well as the maxima and minima corresponding to element R, are removed to form a new array. The stability of the export pressure signal is then checked on the new array.

[0106] Then, the maximum and minimum values ​​at the same position in the exit maximum array [pmaxAvg0, pmaxAvg1, …] and the exit minimum array [pminAvg0, pmaxAvg1, …] are averaged again to form the target exit array [pAvg0, pAvg1, …], i.e., pAvg0 = (pmaxAvg0 + pminAvg0) / 2, and similarly, pAvg1 = (pmaxAvg1 + pmaxAvg1) / 2, and so on. Next, the active diagnosis result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements. It should be noted that the target time difference threshold… It can be determined based on actual needs, or it can be determined by the adjacent elements themselves or the basic difference threshold. The target EGR rate that remains unchanged under the first diagnostic condition Average value of target EGR valve opening under the first diagnostic condition The average value of the engine speed filter under preset stability conditions Average inlet temperature of EGR valve under preset stability conditions Preset EGR valve inlet temperature Preset engine speed Preset target EGR rate Actual EGR valve inlet pressure in the interval where adjacent elements are located The actual EGR valve inlet pressure filter value of the interval where adjacent elements are located And the preset fitting coefficients are determined, that is:

[0107] in, As a default threshold, a value of 0.1 is preferred. As the default EGR valve inlet temperature, 550°C is preferably selected in this embodiment; As the default engine speed, 1000 rpm can be preferably selected in this embodiment; The target EGR rate under the first diagnostic condition is the strong control target. This represents the average target EGR valve opening value over time t4 under the second diagnostic condition. This represents the average filtered value of engine speed under stability conditions. This represents the average inlet temperature of the EGR valve under stable conditions. As the default target EGR rate, this embodiment can preferably be 10%; The actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i (i=0,1,2,3...) in the target outlet array; The filtered value of the actual EGR valve inlet pressure within the M1 sampling interval corresponding to element i in the target outlet array; For the M1 sampling interval corresponding to element i in the target exit array Maximum value.

[0108] further, and All are preset fitting coefficients, which can be adjusted in different ways. Engine speed And under the EGR valve opening, based on the fitting data from the faulty pressure sensor and the non-faulty pressure sensor, the optimal values ​​for both are 0.03 and 0.045, respectively; in addition, the correction coefficient... Based on , , and Determined, i.e., different sizes , , and Corresponding They are all different, among which, The specific value can be determined based on the faulty pressure sensor and the non-faulty pressure sensor. That is, by benchmarking the faulty pressure sensor and the non-faulty pressure sensor, the correction coefficient is determined using the aforementioned three-standard-deviation principle. .

[0109] Specifically, if the target export array contains If the number of occurrences of (element i=0,1,2,3…) exceeds the threshold CNT2, it indicates that the EGR outlet pressure active diagnosis fault has occurred, that is, the EGR outlet pressure fault has actually occurred, and the result of active diagnosis is that there is a fault in the EGR outlet pressure; otherwise, it indicates that the pressure signal fault has not occurred.

[0110] It is worth noting that in this embodiment, the threshold number CNT2 can be dynamically adjusted based on whether the EGR valve is closed; if the EGR valve is closed, the threshold number CNT2 is adjusted based on the absolute value of the average fresh air intake flow rate into the cylinder under stability conditions. Compared to the default preset fresh air intake flow rate (It is preferable to select a ratio of 10g / s) Definite and the average outlet pressure of the mixing valve under stability conditions. Average inlet pressure of the mixing valve ratio Definite The threshold number CNT2 is jointly determined, i.e., CNT2 = V3, where V3 is the number of times the threshold is reached. The result is obtained by rounding to the nearest integer. It should be understood that the larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system, and the larger its threshold coefficient CNT2, to avoid the impact of flow disturbance. Among these, The specific value can be obtained by looking up Table 6.

[0111] Table 6 Threshold Count Mapping Table

[0112] It should be noted that Table 6 above is only a presentation of an example, and the specific values ​​in Table 6 can be adaptively adjusted according to actual needs.

[0113] Understandably, the higher the mixing valve pressure ratio, the worse the mixing valve's throttling effect, and the greater the potential for gas flow disturbances. This can easily cause disturbances in the EGR valve outlet pressure, leading to reduced signal verification accuracy. To avoid such problems, the threshold number CNT2 needs to be increased. The specific value can be obtained by looking up Table 7.

[0114] Table 7 Threshold Count Mapping Table

[0115] It should be noted that Table 7 above is only a presentation of an example, and the specific values ​​in Table 7 can be adapted to meet actual needs.

[0116] If the EGR valve is not closed, the absolute value of the average fresh air intake flow rate into the cylinder under stability conditions. Compared to the default preset fresh air intake flow rate (It is preferable to select a ratio of 10g / s) Definite and the average outlet pressure of the mixing valve under stability conditions. Average inlet pressure of the mixing valve ratio Definite The threshold number CNT2 is jointly determined, i.e., CNT2 = V4, where V4 is the number of times the threshold is reached. The result is obtained by rounding to the nearest integer. It should be noted that V4 is not less than V3. It should be understood that the larger the absolute value of the intake airflow, the greater the potential flow disturbance in the exhaust system, and therefore the larger the threshold coefficient CNT2, to avoid the impact of flow disturbance. The specific value can be obtained by looking up Table 8.

[0117] Table 8 Threshold Count Mapping Table

[0118] It should be noted that Table 8 above is only a presentation of an example, and the specific values ​​in Table 8 can be adaptively adjusted according to actual needs.

[0119] Understandably, the higher the mixing valve pressure ratio, the worse the mixing valve's throttling effect, and the greater the potential for gas flow disturbances. This can easily cause disturbances in the EGR valve outlet pressure, leading to reduced signal verification accuracy. To avoid such problems, the threshold number CNT2 needs to be increased. The specific value can be obtained by looking up Table 9.

[0120] Table 9 Threshold Count Mapping Table

[0121] It should be noted that Table 9 above is only a presentation of an example, and the specific values ​​in Table 9 can be adaptively adjusted according to actual needs.

[0122] Furthermore, if the stability condition is not met when the EGR valve switches between closed and open states, the pressure signal verification will be terminated.

[0123] Step S20: Determine the EGR pressure fault diagnosis result based on the active diagnosis result, and dynamically adjust the diagnosis threshold of the passive diagnosis based on the consistency between the passive diagnosis result and the active diagnosis result.

[0124] As an example, in this embodiment, for inlet pressure diagnosis, if the active diagnosis result indicates a fault in the EGR inlet pressure, then the presence of an EGR inlet pressure fault is taken as the EGR pressure fault diagnosis result; conversely, if the active diagnosis result indicates no fault in the EGR inlet pressure, then the absence of an EGR inlet pressure fault is taken as the EGR pressure fault diagnosis result. Similarly, for outlet pressure diagnosis, if the active diagnosis result indicates a fault in the EGR outlet pressure, then the presence of an EGR outlet pressure fault is taken as the EGR pressure fault diagnosis result; conversely, if the active diagnosis result indicates no fault in the EGR outlet pressure, then the absence of an EGR outlet pressure fault is taken as the EGR pressure fault diagnosis result.

[0125] Understandably, since the confidence level of active diagnostic results is higher than that of passive diagnostic results, if the passive diagnostic results are consistent with the active diagnostic results, it means that there are no misjudgments or omissions in the passive diagnostic process, but its diagnostic speed needs to be improved. Conversely, if the passive diagnostic results are inconsistent with the active diagnostic results, it means that there are misjudgments or omissions in the passive diagnostic process, and its diagnostic accuracy needs to be improved. Therefore, this embodiment can dynamically adjust the diagnostic threshold of passive diagnostics by maintaining consistency between the passive and active diagnostic results, thereby improving the speed or accuracy of fault diagnosis in passive diagnostics.

[0126] Furthermore, in one embodiment, dynamically adjusting the diagnostic threshold of the passive diagnosis based on the consistency between the passive diagnostic result and the active diagnostic result includes: If both the passive diagnostic result and the active diagnostic result indicate that there is a fault in the EGR pressure, then the diagnostic threshold for the passive diagnostic is lowered. If the passive diagnosis result indicates a fault in EGR pressure and the active diagnosis result indicates no fault in EGR pressure, then the diagnostic threshold for the passive diagnosis is increased.

[0127] In this exemplary embodiment, if both the passive and active diagnostic results indicate an EGR pressure fault (i.e., the passive and active diagnostic results are consistent), the passive diagnostic threshold can be directly lowered to improve the fault detection speed. Conversely, if the passive diagnostic result indicates an EGR pressure fault but the active diagnostic result indicates no EGR pressure fault (i.e., the passive and active diagnostic results are inconsistent), the passive diagnostic threshold can be directly raised to improve the accuracy of fault detection. Alternatively, it can be further determined whether active diagnostics has been initiated N times consecutively (in this embodiment, N is preferably 3, where the N value is updated at most once per driving cycle and can be saved after the vehicle is powered off) without reporting an EGR pressure fault. Only then should the passive diagnostic threshold be raised and the N value reset to zero. It should be noted that the specific increase and decrease in the diagnostic threshold can be determined according to actual needs or obtained through bench testing calibration, and are not limited here.

[0128] Specifically, once the threshold for passive diagnosis of reduced inlet pressure is reached, the following updates will be made: 1) If the fault occurs in either the first or second scenario described in the aforementioned entry fault judgment, then , This represents the current first entry pressure learning coefficient; 2) If the fault occurs in the third or fourth scenario described in the aforementioned entry fault judgment, then , This represents the current second entry pressure learning coefficient.

[0129] Once the threshold for increasing inlet pressure passive diagnosis is reached, update: 1) If the fault occurs in either the first or second scenario described in the aforementioned entry fault judgment, then ; 2) If the fault occurs in the third or fourth scenario described in the aforementioned entry fault judgment, then .

[0130] Once the threshold for passive diagnosis to reduce export pressure is reached, update: 1) If the fault occurs in either the first or second scenario described in the aforementioned exit fault assessment, then , This represents the current learning coefficient for the first export pressure. 2) If the fault occurs under the third or fourth scenario described in the aforementioned exit fault assessment, then , This represents the current learning coefficient for the second export pressure.

[0131] Once the threshold for passively diagnosing export pressure is reached, update: 1) If the fault occurs in either the first or second scenario described in the aforementioned exit fault assessment, then ; 2) If the fault occurs under the third or fourth scenario described in the aforementioned exit fault assessment, then .

[0132] Further, in one embodiment, the target EGR valve pressure signal includes a target EGR valve inlet pressure signal and a target EGR valve outlet pressure signal. After the step of determining the EGR pressure fault diagnosis result based on the active diagnosis result, the method further includes: If the EGR pressure fault diagnosis result corresponding to the target EGR valve inlet pressure signal is that there is a fault in the EGR inlet pressure and the EGR pressure fault diagnosis result corresponding to the target EGR valve outlet pressure signal is that there is a fault in the EGR valve outlet pressure, then the inlet and outlet pressure rationality diagnosis is performed to obtain the rationality diagnosis result. The inlet and outlet pressure rationality diagnosis includes controlling the engine to run in sequence under multiple operating conditions with different EGR rates and monitoring the pressure response characteristics under different operating conditions. The diagnostic threshold for rationality diagnosis of inlet and outlet pressure is dynamically adjusted based on the rationality diagnosis results.

[0133] As an example, in this embodiment, if both inlet pressure and outlet pressure faults are confirmed—that is, the result of the active inlet pressure diagnosis is a fault in the EGR inlet pressure and the result of the active outlet pressure diagnosis is a fault in the EGR valve outlet pressure—then it can be determined whether to perform inlet and outlet pressure rationality diagnosis by judging whether the EGR system meets the inlet and outlet pressure rationality diagnosis conditions. The inlet and outlet pressure rationality diagnosis conditions include: 1) Target EGR rate The fluctuation (i.e., the difference between the target EGR rates of two adjacent sampling periods) is within a certain range, and in this embodiment, it is preferably ±0.02; 2) Target EGR rate The target EGR rate should not exceed a preset value (preferably 0.1 in this embodiment), meaning the target EGR rate should not be too high.

[0134] 3) The mixing valve is fully open; 4) The EGR valve opening is in a stable state (the specific identification method for this stable state is detailed in the aforementioned embodiments and will not be repeated here). 5) The EGR valve inlet temperature fluctuation (i.e., the difference between the EGR valve inlet temperatures of two adjacent sampling periods) is small, and in this embodiment, ±3℃ is preferred; 6) The GPF outlet pressure fluctuation is small, i.e., it satisfies: The conditions are met continuously for a preset time. After that, it indicates that the GPF outlet pressure is in a stable state; where, the threshold coefficient and preset time The specific value can be determined according to actual needs, for example... The preferred value is 0.01 and The optimal value is 0.05s.

[0135] 7) No EGR valve inlet and outlet pressure sensor circuit faults occurred (such as any circuit faults including open circuits and short circuits).

[0136] It should be understood that if all the above conditions are met and the duration exceeds the fifth duration threshold T5, then the conditions for reasonableness diagnosis of entrance and exit pressure are considered met, and a reasonableness diagnosis of entrance and exit pressure is performed.

[0137] It should be noted that the fifth time threshold T5 is the time it takes for the exhaust gas to flow from the GPF outlet to the mixing valve outlet. Specifically, it can be calculated by multiplying the average time of the exhaust gas flow from the GPF outlet to the mixing valve outlet by N3 × 10 ... The products of these factors are summed, and the sum is used as the fifth duration threshold T5. The sampling period is... The specific value can be determined according to actual needs, such as preferably 10ms; N3 represents the delay number three, which can be 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. By debugging various data sampling, the average time of exhaust gas flowing from the GPF outlet to the mixing valve outlet is obtained, and the average time is added to N3 × As T5; 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 in the above stability conditions will be used to replace the fixed engine speed, fresh air intake density entering the cylinder, and average value of the EGR valve opening on the test bench to obtain the actual T5. It should be noted that N3 is determined by the average value of the engine speed filter value and the average value of the EGR valve opening in the stability conditions. That is, the larger the average value of the engine speed filter value and the larger the average value of the EGR valve opening, the larger N3 needs to be set in order to ensure stable operating conditions and the accuracy of pressure signal verification. See Table 10 for details.

[0138] Table 10 Three-way mapping table for delay counts

[0139] It should be noted that N3 is determined by looking up the table in Table 10 above based on the average value of the engine speed filter value and the average value of the EGR valve opening in the stability conditions. The table lookup method for N3 is similar to that for N1, and will not be repeated here for the sake of simplicity. In addition, Table 10 above is only a presentation of an embodiment, and the specific values ​​in Table 10 can be adaptively adjusted according to actual needs.

[0140] Furthermore, it is preferable that the EGR pressure verification can only proceed after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met. If the stability conditions or inlet / outlet pressure rationality diagnostic conditions are not met, or if the stability conditions or inlet / outlet pressure rationality diagnostic conditions are not met during the EGR inlet / outlet pressure rationality verification process, the EGR pressure verification should be stopped, indicating that the fault has not been detected.

[0141] Based on this, the EGR inlet pressure after secondary filtering is obtained, which meets the conditions for reasonable inlet and outlet pressure diagnosis. And read the EGR inlet pressure after secondary filtering. The maximum and minimum values ​​are recorded as the inlet maximum sequence [pmax00, pmax01, …] and the inlet minimum sequence [pmin00, pmin01, …], respectively; where pmax00 is the first sampling period (sampling period interval) after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met. The maximum value of the EGR inlet pressure read, pmax01 is the second sampling period after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met (sampling period interval). The maximum value of the EGR inlet pressure is read, and so on; pmin00 is the first sampling period (sampling period interval) after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met. The minimum value of the EGR inlet pressure read, pmin01 is the second sampling period after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met (sampling period interval). The minimum value of the EGR inlet pressure is read, and so on.

[0142] Obtain the filtered EGR outlet pressure that meets the conditions for reasonable inlet and outlet pressure diagnosis. The maximum and minimum values ​​are recorded as the outlet maximum sequence [pmax10, pmax11, …] and the outlet minimum sequence [pmin10, pmin11, …], respectively, where pmax10 is the first sampling period after all stability conditions and inlet / outlet pressure rationality diagnosis conditions (sampling period interval). The maximum value of the EGR outlet pressure read, pmax11 is the second sampling period after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met (sampling period interval). The maximum value of the EGR outlet pressure read is used, and so on; pmin10 is the first sampling period (sampling period interval) after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met. The minimum value of the EGR outlet pressure read, pmin11 is the second sampling period after all stability conditions and inlet / outlet pressure rationality diagnostic conditions are met (sampling period interval). The minimum value of the EGR outlet pressure read, and so on.

[0143] In this embodiment, the maximum and minimum values ​​of the first M3 sampling periods are preferably removed to avoid signal instability in the early stages of stable inspection conditions, which could affect the accuracy of the pressure signal inspection. The value of M3 can be obtained from Table 11 based on the average value of the engine speed filter value when the stability condition is met. Table 11 M3 Value Mapping Table

[0144] Based on this, M3 is determined by looking up the average value of the engine speed filter value in the stability condition in Table 11 above; the method for obtaining M3 by looking up the table is similar to that of N1, and will not be repeated here for the sake of simplicity; it should be noted that Table 11 above is only a presentation of an embodiment, and the specific values ​​in Table 11 can be adaptively adjusted according to actual needs.

[0145] After removing the maximum and minimum values ​​from the first M3 sampling periods, the time difference array between adjacent maximum values ​​of the EGR valve inlet pressure is read. Time difference array between and adjacent minimum values The first element in the array and To remove the time difference between adjacent extreme values ​​of the EGR valve inlet pressure obtained from the first sample after the first M3 sampling periods; similarly, after removing the maximum and minimum values ​​from the first M3 sampling periods, the time difference array between adjacent maximum values ​​of the EGR valve outlet pressure is read. Time difference array between and adjacent minimum values The first element in the array and To eliminate the time difference between adjacent extreme values ​​of the EGR valve outlet pressure obtained from the first sampling after the previous M3 sampling cycles.

[0146] Based on this, calculate and The difference between the identical elements in the middle, i.e. To obtain the difference between the time difference of the inlet pressure maximum and the time difference of the outlet pressure maximum. Simultaneously, calculation and The difference between the identical elements in the middle, i.e. To obtain the difference between the time difference between the minimum inlet pressure and the time difference between the minimum outlet pressure. , where i = 0, 1, 2, ...

[0147] Then, the target EGR rate is controlled to decrease from the current value to the target minimum EGR rate (it should be noted that the target minimum EGR rate can be determined by the prior art with publication number CN115585070B and patent name "Method, Device, Equipment and Storage Medium for Adjusting Minimum EGR Rate", which will not be elaborated here) and fixed. At this time, when performing steady-state operation condition verification, in addition to meeting (1) all the aforementioned stability conditions and inlet / outlet pressure rationality diagnosis conditions (except for changes in the target EGR rate), it is also necessary to meet (2): The deviation between the average engine speed under the current stable condition and the average engine speed under the previous stable condition does not exceed the first deviation value (e.g., 2%, then the difference between the average engine speed under the current stable condition and the average engine speed under the previous stable condition divided by the average engine speed under the previous stable condition does not exceed ±2%). Simultaneously, the deviation between the average intake air density of the fresh air entering the cylinder under the current stable condition and the average intake air density of the fresh air entering the cylinder under the previous stable condition does not exceed the second deviation value (e.g., 1%, then the difference between the average intake air density of the fresh air entering the cylinder under the current stable condition and the average intake air density of the fresh air entering the cylinder under the previous stable condition divided by the average intake air density of the fresh air entering the cylinder under the previous stable condition does not exceed ±1%). Based on this, it avoids situations where excessive changes in operating conditions prevent comparison of EGR performance differences under significantly different operating conditions, thus hindering the determination of whether a pressure fault has occurred.

[0148] It should be noted that the EGR inlet and outlet pressure rationality check can only be carried out when both conditions (1) and (2) above are met at the same time; if the stability condition and the inlet and outlet pressure rationality diagnosis condition are not met, or if the stability condition and the inlet and outlet pressure rationality diagnosis condition (except for changes in the target EGR rate) are not met during the EGR inlet and outlet pressure rationality check, the EGR inlet and outlet pressure rationality check will be stopped and characterized as a fault not detected.

[0149] Similarly, following the above method, the difference between the time difference of the maximum inlet pressure and the time difference of the maximum outlet pressure under the above operating conditions is obtained. And the difference between the time difference of the minimum inlet pressure and the time difference of the minimum outlet pressure. .

[0150] Next, the target EGR rate is controlled to decrease from the minimum target EGR rate to 0 and remain fixed. At this time, when performing steady-state condition verification, in addition to meeting all the aforementioned stability conditions and inlet / outlet pressure rationality diagnosis conditions (except for changes in the target EGR rate), it is also necessary to meet (4): The deviation between the average engine speed under the current stable condition and the average engine speed under the previous stable condition does not exceed the first deviation value (e.g., 2%, then the difference between the average engine speed under the current stable condition and the average engine speed under the previous stable condition divided by the average engine speed under the previous stable condition does not exceed ±2%). Simultaneously, the deviation between the average intake air density of the fresh air entering the cylinder under the current stable condition and the average intake air density of the fresh air entering the cylinder under the previous stable condition does not exceed the second deviation value (e.g., 1%, then the difference between the average intake air density of the fresh air entering the cylinder under the current stable condition and the average intake air density of the fresh air entering the cylinder under the previous stable condition divided by the average intake air density of the fresh air entering the cylinder under the previous stable condition does not exceed ±1%). Based on this, it avoids situations where excessive changes in operating conditions prevent comparison of EGR performance differences under significantly different operating conditions, thus hindering the determination of whether a pressure fault has occurred.

[0151] It should be noted that the EGR inlet and outlet pressure rationality check can only be carried out when both conditions (3) and (4) above are met at the same time; if the stability condition and the inlet and outlet pressure rationality diagnosis condition are not met, or if the stability condition and the inlet and outlet pressure rationality diagnosis condition (except for changes in the target EGR rate) are not met during the EGR inlet and outlet pressure rationality check, the EGR inlet and outlet pressure rationality check will be stopped and characterized as a fault not detected.

[0152] Similarly, the difference between the time difference of the maximum inlet pressure and the time difference of the maximum outlet pressure under the above operating conditions is obtained. And the difference between the time difference of the minimum inlet pressure and the time difference of the minimum outlet pressure. .

[0153] Based on this, a judgment is made on the rationality of the inlet and outlet pressure: 11) If it occurs or If the number of occurrences exceeds the preset value A (the specific value can be determined according to actual needs, such as 50 in this embodiment), it indicates that the EGR inlet and outlet pressures may have a fault (i.e., a suspected fault exists).

[0154] It should be noted that, This represents the first diagnostic threshold for determining the reasonableness of inlet and outlet pressure. This represents the average value of the engine speed filter under stability conditions. The default engine speed is 1000 rpm, which can be preferably selected in this embodiment; This represents the average inlet temperature of the EGR valve under stable conditions. Let be a constant value for the exhaust gas. The average actual EGR valve opening under the condition of reasonable inlet and outlet pressure diagnosis; The preset base difference ratio value can be set to different values. The following data was obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors. Based on , , , and Determined, i.e., different sizes , , , and Corresponding They are all different, among which, The specific value can be different The following data was obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors. This is the first threshold self-learning coefficient, whose default value can preferably be 0, and it can be continuously self-learned and updated. The updated value is saved immediately after each update. Only update the corresponding working condition each time (i.e.) , and The learning value under the same conditions.

[0155] 12) If it occurs or If the number of occurrences exceeds the preset value B (the specific value can be determined according to actual needs, such as 50 in this embodiment), it indicates that the EGR inlet and outlet pressures may have a second fault (i.e., a suspected fault exists).

[0156] It should be noted that, This represents the second diagnostic threshold for assessing the reasonableness of inlet and outlet pressure. Similarly, it is a preset base difference ratio value, which can be different The following data was obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors. Based on , , , and Determined, i.e., different sizes , , , and Corresponding They are all different, among which, The specific value can be different The following data was obtained by benchmarking and fitting data from faulty and non-faulty pressure sensors. This is the self-learning coefficient for the second threshold. Its default value can preferably be 0, and it can be continuously updated through self-learning. The updated value is saved immediately after each update. Only update the corresponding working condition each time (i.e.) , and The learning value under the same conditions.

[0157] 13) If it occurs or If the number of times exceeds the preset value C (the specific value can be determined according to actual needs, such as 20 in this embodiment), it indicates that the EGR inlet and outlet pressure may have a third fault.

[0158] It is worth noting that if both possible fault one and possible fault three occur simultaneously, or both possible fault two and possible fault three occur simultaneously, it indicates that an EGR inlet and outlet pressure rationality fault has occurred, that is, the rationality diagnosis result is that there is a rationality fault in the inlet and outlet pressure; otherwise, it indicates that no rationality fault has been detected.

[0159] Based on this, if the rationality diagnosis result indicates a rationality fault in the inlet / outlet pressure, then the rationality diagnosis threshold adjustment one is initiated to accelerate the judgment of rationality faults in the inlet / outlet pressure. If the rationality diagnosis of inlet / outlet pressure is initiated G times consecutively (preferably 5 times in this embodiment, where the G value is updated at most once in each driving cycle and can be saved after the vehicle is powered off), but no rationality fault is reported, then the rationality diagnosis threshold adjustment two is initiated to improve the accuracy of rationality pressure diagnosis, and the G value is reset to zero. It should be noted that the specific increase and decrease in the diagnostic threshold for rationality diagnosis of inlet / outlet pressure can be determined according to actual needs, or it can be obtained through bench testing calibration, and is not limited here.

[0160] Specifically, once the rationality diagnosis threshold adjustment is reached, the following will be updated: 1) If the fault occurs as described in scenario 11 of the aforementioned fault assessment regarding the reasonableness of inlet and outlet pressures, then , This represents the current first threshold self-learning coefficient; 2) If the fault occurs as described in scenario 12 of the aforementioned fault assessment regarding the reasonableness of inlet and outlet pressure, then , This represents the current second threshold self-learning coefficient.

[0161] Once the rationality diagnosis threshold adjustment reaches level two, the following will be updated: 1) If the fault occurs as described in scenario 11 of the aforementioned fault assessment regarding the reasonableness of inlet and outlet pressures, then ; 2) If the fault occurs as described in scenario 12 of the aforementioned fault assessment regarding the reasonableness of inlet and outlet pressure, then .

[0162] In summary, in this embodiment, passive diagnosis does not interfere with the normal control of the engine. After a fault is detected, it will actively perform a second diagnosis to improve the accuracy of fault detection. At the same time, the diagnostic threshold of passive diagnosis is dynamically adjusted according to the consistency between the passive diagnosis results and the active diagnosis results to improve the speed or accuracy of fault diagnosis in passive diagnosis. In addition, when inlet pressure faults and outlet pressure faults occur, it is determined whether an inlet / outlet pressure rationality fault has occurred. If so, the threshold is updated to avoid misjudgment of inlet / outlet pressure rationality faults due to inlet / outlet pressure faults and outlet pressure faults.

[0163] Secondly, embodiments of this application also provide an EGR pressure fault diagnosis device.

[0164] In one embodiment, reference is made to Figure 3 , Figure 3 This is a functional module diagram of an embodiment of the EGR pressure fault diagnosis device of this application. Figure 3 As shown, the EGR pressure fault diagnosis device includes: The fault diagnosis module is used to perform active diagnosis when the passive diagnosis result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, and obtain the active diagnosis result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to be in a preset state and monitoring the pressure response characteristics. Based on the active diagnosis result, the EGR pressure fault diagnosis result is determined. A threshold adjustment module is used to dynamically adjust the diagnostic threshold of passive diagnosis based on the consistency between the passive diagnosis result and the active diagnosis result.

[0165] Furthermore, in one embodiment, the threshold adjustment module is specifically used for: If both the passive diagnostic result and the active diagnostic result indicate that there is a fault in the EGR pressure, then the diagnostic threshold for the passive diagnostic is lowered. If the passive diagnosis result indicates a fault in EGR pressure and the active diagnosis result indicates no fault in EGR pressure, then the diagnostic threshold for the passive diagnosis is increased.

[0166] Further, in one embodiment, the target EGR valve pressure signal includes a target EGR valve inlet pressure signal and a target EGR valve outlet pressure signal. The fault diagnosis module is further configured to perform an inlet / outlet pressure rationality diagnosis if the EGR pressure fault diagnosis result corresponding to the target EGR valve inlet pressure signal indicates a fault in the EGR inlet pressure and the EGR pressure fault diagnosis result corresponding to the target EGR valve outlet pressure signal indicates a fault in the EGR valve outlet pressure, thereby obtaining a rationality diagnosis result. The inlet / outlet pressure rationality diagnosis includes controlling the engine to operate sequentially under multiple operating conditions with different EGR rates and monitoring the pressure response characteristics under different operating conditions. The threshold adjustment module is further configured to dynamically adjust the diagnostic threshold for the inlet / outlet pressure rationality diagnosis based on the rationality diagnosis result.

[0167] Furthermore, in one embodiment, the EGR pressure fault diagnosis device further includes a condition verification module, which is used for: Determine whether the EGR system meets the preset active diagnostic conditions; If the conditions are met, then proceed with the step of performing active diagnosis. If the first preset duration is not met, the EGR pressure fault diagnosis result is determined to be that there is no fault in the EGR pressure. If the target EGR valve pressure signal is the target EGR valve inlet pressure signal, then the preset active diagnosis conditions include the actual mixing valve opening, the actual EGR valve opening, the EGR valve inlet temperature fluctuation, the GPF outlet pressure fluctuation, and the EGR valve inlet pressure sensor circuit status all meeting the preset inlet active diagnosis requirements and lasting for a duration reaching the third duration threshold. If the target EGR valve pressure signal is the target EGR valve outlet pressure signal, then the preset active diagnostic conditions include a first diagnostic condition and a second diagnostic condition. The first diagnostic condition includes that the actual mixing valve opening, EGR valve inlet pressure fluctuation, EGR valve inlet temperature fluctuation, and EGR valve outlet pressure sensor circuit status all meet the preset first outlet active diagnostic requirements and the duration reaches the fourth duration threshold. The second diagnostic condition includes that the actual EGR valve opening within the target duration meets the preset second outlet active diagnostic requirements. The target duration is the duration during which the target EGR valve opening is fixed at the target EGR valve opening average value. The target EGR valve opening average value is collected under the first diagnostic condition while keeping the target EGR rate constant.

[0168] Furthermore, in one embodiment, when the target EGR valve pressure signal is the target EGR valve inlet pressure signal, the fault diagnosis module is specifically used for: The current target EGR rate is fixed as the target EGR rate under the first sampling period when the preset active diagnostic conditions are met; Based on the target interval value, the inlet maximum value sequence and inlet minimum value sequence of the current EGR valve inlet pressure signal corresponding to the current target EGR rate are divided into intervals, and the average value of the divided intervals is calculated to obtain the inlet maximum value array and the inlet minimum value array. The target inlet array is obtained by averaging the common elements in the inlet maximum and inlet minimum arrays. The active diagnostic result of the inlet is determined based on the difference between adjacent elements in the target inlet array and the target time difference threshold.

[0169] Furthermore, in one embodiment, the target time difference threshold is determined based on the base time difference threshold, the average target EGR rate under preset stability conditions, the average engine speed filter value under preset stability conditions, the average EGR valve inlet temperature under preset stability conditions, the preset EGR inlet temperature value, the preset engine speed, the preset atmospheric pressure, the current actual atmospheric pressure, the preset atmospheric temperature, the actual atmospheric temperature, and the preset fitting coefficient.

[0170] Furthermore, in one embodiment, when the target EGR valve pressure signal is the target EGR valve outlet pressure signal, the fault diagnosis module is specifically used for: Based on the target interval value, the current EGR valve outlet pressure signal is divided into intervals for the outlet maximum value sequence and the outlet minimum value sequence, and the average value of the divided intervals is calculated to obtain the outlet maximum value array and the outlet minimum value array. The target export array is obtained by averaging the common elements in the export maximum and export minimum arrays. The active diagnostic result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements.

[0171] Further, in one embodiment, the target difference threshold is determined based on the adjacent elements themselves, the basic difference threshold, the target EGR rate that remains unchanged under the first diagnostic condition, the average value of the target EGR valve opening under the first diagnostic condition, the average value of the engine speed filter value under the preset stability condition, the average value of the EGR valve inlet temperature under the preset stability condition, the preset EGR valve inlet temperature, the preset engine speed, the preset target EGR rate, the actual EGR valve inlet pressure in the interval where the adjacent elements are located, the actual EGR valve inlet pressure filter value in the interval where the adjacent elements are located, and the preset fitting coefficient.

[0172] Furthermore, in one embodiment, the condition verification module is also used for: When the EGR system is detected to meet the preset stability conditions, it is determined whether the EGR system meets the preset passive diagnostic conditions. If the conditions are met, the fault diagnosis module will perform passive diagnosis. If the conditions are not met, the fault diagnosis module will not perform any diagnosis. The preset stability conditions include the engine operating state, intake system parameters, combustion state parameters, and sensor state parameters all meeting the preset stability requirements for a duration reaching a first duration threshold. The preset passive diagnostic conditions include the actual mixing valve opening, target EGR rate fluctuation, actual EGR valve opening, EGR valve inlet temperature fluctuation, GPF outlet pressure fluctuation or EGR valve inlet pressure fluctuation, and EGR valve inlet and outlet pressure sensor circuit state all meeting the preset passive diagnostic requirements for a duration reaching a second duration threshold.

[0173] The functions of each module in the above-mentioned EGR pressure fault diagnosis device correspond to the steps in the above-mentioned EGR pressure fault diagnosis method embodiment, and their functions and implementation processes will not be described in detail here.

[0174] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0175] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0176] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0177] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0178] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0179] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0180] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for diagnosing EGR pressure faults, characterized in that, include: When the passive diagnostic result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, active diagnosis is performed to obtain the active diagnostic result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to be in a preset state and monitoring the pressure response characteristics. Based on the active diagnostic results, the EGR pressure fault diagnosis results are determined, and the diagnostic threshold of the passive diagnosis is dynamically adjusted based on the consistency between the passive diagnostic results and the active diagnostic results.

2. The EGR pressure fault diagnosis method as described in claim 1, characterized in that, The method of dynamically adjusting the diagnostic threshold for passive diagnosis based on the consistency between the passive diagnostic results and the active diagnostic results includes: If both the passive diagnostic result and the active diagnostic result indicate that there is a fault in the EGR pressure, then the diagnostic threshold for the passive diagnostic is lowered. If the passive diagnosis result indicates a fault in EGR pressure and the active diagnosis result indicates no fault in EGR pressure, then the diagnostic threshold for the passive diagnosis is increased.

3. The EGR pressure fault diagnosis method as described in claim 1, characterized in that, The target EGR valve pressure signal includes the target EGR valve inlet pressure signal and the target EGR valve outlet pressure signal. After the step of determining the EGR pressure fault diagnosis result based on the active diagnosis result, the method further includes: If the EGR pressure fault diagnosis result corresponding to the target EGR valve inlet pressure signal is that there is a fault in the EGR inlet pressure and the EGR pressure fault diagnosis result corresponding to the target EGR valve outlet pressure signal is that there is a fault in the EGR valve outlet pressure, then the inlet and outlet pressure rationality diagnosis is performed to obtain the rationality diagnosis result. The inlet and outlet pressure rationality diagnosis includes controlling the engine to run in sequence under multiple operating conditions with different EGR rates and monitoring the pressure response characteristics under different operating conditions. The diagnostic threshold for rationality diagnosis of inlet and outlet pressure is dynamically adjusted based on the rationality diagnosis results.

4. The EGR pressure fault diagnosis method as described in claim 1, characterized in that, Prior to the step of performing active diagnostics, the following is also included: Determine whether the EGR system meets the preset active diagnostic conditions; If the conditions are met, then proceed with the step of performing active diagnosis. If the first preset duration is not met, the EGR pressure fault diagnosis result is determined to be that there is no fault in the EGR pressure. If the target EGR valve pressure signal is the target EGR valve inlet pressure signal, then the preset active diagnosis conditions include the actual mixing valve opening, the actual EGR valve opening, the EGR valve inlet temperature fluctuation, the GPF outlet pressure fluctuation, and the EGR valve inlet pressure sensor circuit status all meeting the preset inlet active diagnosis requirements and lasting for a duration reaching the third duration threshold. If the target EGR valve pressure signal is the target EGR valve outlet pressure signal, then the preset active diagnostic conditions include a first diagnostic condition and a second diagnostic condition. The first diagnostic condition includes that the actual mixing valve opening, EGR valve inlet pressure fluctuation, EGR valve inlet temperature fluctuation, and EGR valve outlet pressure sensor circuit status all meet the preset first outlet active diagnostic requirements and the duration reaches the fourth duration threshold. The second diagnostic condition includes that the actual EGR valve opening within the target duration meets the preset second outlet active diagnostic requirements. The target duration is the duration during which the target EGR valve opening is fixed at the target EGR valve opening average value. The target EGR valve opening average value is collected under the first diagnostic condition while keeping the target EGR rate constant.

5. The EGR pressure fault diagnosis method as described in claim 4, characterized in that, When the target EGR valve pressure signal is the target EGR valve inlet pressure signal, the active diagnosis is performed to obtain the active diagnosis result, including: The current target EGR rate is fixed as the target EGR rate under the first sampling period when the preset active diagnostic conditions are met; Based on the target interval value, the inlet maximum value sequence and inlet minimum value sequence of the current EGR valve inlet pressure signal corresponding to the current target EGR rate are divided into intervals, and the average value of the divided intervals is calculated to obtain the inlet maximum value array and the inlet minimum value array. The target inlet array is obtained by averaging the common elements in the inlet maximum and inlet minimum arrays. The active diagnostic result of the inlet is determined based on the difference between adjacent elements in the target inlet array and the target time difference threshold.

6. The EGR pressure fault diagnosis method as described in claim 5, characterized in that, The target time difference threshold is determined based on the base time difference threshold, the average target EGR rate under preset stability conditions, the average engine speed filter value under preset stability conditions, the average EGR valve inlet temperature under preset stability conditions, the preset EGR inlet temperature value, the preset engine speed, the preset atmospheric pressure, the current actual atmospheric pressure, the preset atmospheric temperature, the actual atmospheric temperature, and the preset fitting coefficient.

7. The EGR pressure fault diagnosis method as described in claim 4, characterized in that, When the target EGR valve pressure signal is the target EGR valve outlet pressure signal, the active diagnosis is performed to obtain the active diagnosis result, including: Based on the target interval value, the current EGR valve outlet pressure signal is divided into intervals for the outlet maximum value sequence and the outlet minimum value sequence, and the average value of the divided intervals is calculated to obtain the outlet maximum value array and the outlet minimum value array. The target export array is obtained by averaging the common elements in the export maximum and export minimum arrays. The active diagnostic result is determined based on the difference between adjacent elements in the target exit array and the target difference threshold corresponding to the adjacent elements.

8. The EGR pressure fault diagnosis method as described in claim 7, characterized in that, The target difference threshold is determined based on the adjacent elements themselves, the basic difference threshold, the target EGR rate that remains unchanged under the first diagnostic condition, the average value of the target EGR valve opening under the first diagnostic condition, the average value of the engine speed filter value under the preset stability condition, the average value of the EGR valve inlet temperature under the preset stability condition, the preset EGR valve inlet temperature, the preset engine speed, the preset target EGR rate, the actual EGR valve inlet pressure in the interval where the adjacent elements are located, the actual EGR valve inlet pressure filter value in the interval where the adjacent elements are located, and the preset fitting coefficient.

9. The EGR pressure fault diagnosis method as described in claim 1, characterized in that, The method further includes: When the EGR system is detected to meet the preset stability conditions, it is determined whether the EGR system meets the preset passive diagnostic conditions. If the conditions are met, then perform a passive diagnosis. If the conditions are not met, no diagnosis will be performed; The preset stability conditions include the engine operating state, intake system parameters, combustion state parameters, and sensor state parameters all meeting the preset stability requirements for a duration reaching a first duration threshold. The preset passive diagnostic conditions include the actual mixing valve opening, target EGR rate fluctuation, actual EGR valve opening, EGR valve inlet temperature fluctuation, GPF outlet pressure fluctuation or EGR valve inlet pressure fluctuation, and EGR valve inlet and outlet pressure sensor circuit state all meeting the preset passive diagnostic requirements for a duration reaching a second duration threshold.

10. An EGR pressure fault diagnosis device, characterized in that, include: The fault diagnosis module is used to perform active diagnosis when the passive diagnosis result corresponding to the target EGR valve pressure signal is detected as a fault in the EGR pressure, and obtain the active diagnosis result. The active diagnosis includes forcibly controlling the target EGR rate or the target EGR opening to be in a preset state and monitoring the pressure response characteristics. Based on the active diagnosis result, the EGR pressure fault diagnosis result is determined. A threshold adjustment module is used to dynamically adjust the diagnostic threshold of passive diagnosis based on the consistency between the passive diagnosis result and the active diagnosis result.

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