Egr valve operation failure diagnosis method and device

Abstract

The application discloses an EGR valve working failure diagnosis method, which comprises the following contents: determining the condition of EGR valve working failure diagnosis activation, reading and retaining N EGR valve actual opening degrees in the latest time after the diagnosis activation condition is met, respectively determining an EGR valve actual opening degree initial value and a final value, comparing the EGR valve actual opening degree with an EGR valve actual opening degree maximum final value and an EGR valve actual opening degree minimum final value, and judging whether the EGR valve works normally or not. The application also discloses an EGR valve working failure diagnosis device. The application can detect the failure of the EGR valve in the case that the EGR valve has poor response performance, and can be widely applied in the field of engine control.

Description

Technical Field

[0001] This invention relates to the field of engine control, and in particular to a method and apparatus for diagnosing EGR valve malfunction. Background Technology

[0002] Exhaust gas recirculation (EGR) draws exhaust gases from the exhaust system and introduces them into the intake system. Studies have shown that EGR systems offer advantages in improving emissions, reducing fuel consumption, and enhancing anti-knock capabilities. Low-pressure EGR, unlike high-pressure EGR, draws air after the turbocharger, thus avoiding turbocharger efficiency loss. It can operate almost under all operating conditions, resulting in a more significant improvement in fuel efficiency. However, due to its lower pressure differential, a larger diameter valve is required to meet the flow requirements. If the EGR valve malfunctions (including slow or excessive response), the EGR rate response performance will deteriorate, failing to optimally improve fuel consumption and emissions, and may even cause oscillations in engine intake air volume control, leading to abnormal engine combustion and vibration.

[0003] In light of this, some manufacturers have proposed, for example, a technical solution with application number "CN202011247319.6" and invention title "A Method and System for Calculating Target EGR Rate." This solution determines a basic target EGR rate based on engine speed and load; obtains corresponding correction rates based on specific operating conditions; determines an initial target EGR rate based on the basic target EGR rate and each correction rate; determines whether EGR is activated based on EGR activation state conditions; and classifies EGR states based on the determination results to determine the final target EGR rate. However, this solution does not propose a fault detection method for poor response performance of the EGR valve during the EGR rate calculation process.

[0004] In another patent application, numbered CN202110184826.8 and entitled "Method for Determining the Target Opening of the Mixing Valve in an EGR System," it is proposed that when controlling the mixing valve entering the low-pressure EGR, different rates of change of the mixing valve opening should be controlled according to different operating conditions. However, this paper proposes a mixing valve control method but does not propose a fault detection method if the EGR valve has poor response performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and apparatus for diagnosing EGR valve malfunctions, enabling the detection of faults in EGR valves exhibiting poor response performance.

[0006] The present invention provides a method for diagnosing EGR valve malfunction, comprising the following steps: determining the conditions for activating EGR valve malfunction diagnosis; after the conditions for activation are met, reading and retaining N actual opening degrees of the EGR valve within the most recent time period; determining the initial and final values ​​of the actual opening degrees of the EGR valve; comparing the actual opening degrees of the EGR valve with the final values ​​of the maximum and minimum actual opening degrees of the EGR valve to determine whether the EGR valve has malfunctioned.

[0007] In the above technical solution, the specific process is as follows: Determining the activation conditions for EGR valve failure diagnosis: Determine the activation conditions for EGR valve failure diagnosis; EGR valve failure diagnosis is performed only after all activation conditions are met; EGR valve actual opening degree sampling: Read the actual opening degree of the EGR valve from N consecutive samples and arrange them into an array [pct Act1 ,…,pct ActN After each sampling period, the elements in the array are updated, retaining only the N most recent EGR valve actual openings; the initial value of the EGR valve actual opening is determined: the initial value pct of the maximum actual opening of the EGR valve used to determine EGR valve failure is determined. ActMaxLimRaw and the initial value of the actual opening degree of the EGR valve (pct) ActMinLimRaw Determine the final actual opening value of the EGR valve: Determine the final maximum actual opening value (pct) of the EGR valve. ActMaxLim And the actual minimum and final value of the EGR valve opening (pct) ActMinLim EGR valve malfunction judgment: If the actual opening degree of the EGR valve is less than the final value of the minimum actual opening degree or greater than the final value of the maximum actual opening degree, it indicates that the EGR valve has malfunctioned once. The time of the malfunction is used as the sampling period time. If it occurs within the current driving cycle, the current driving cycle time T is... Total The cumulative failure occurrence time within the time limit shall not be less than the failure time T. ErrLim This indicates that the EGR valve has failed.

[0008] In the above technical solution, the specific conditions for determining the activation of the EGR valve failure diagnosis step are as follows: Voltage fault detection: no battery voltage fault; Position sensor fault detection: no position sensor fault in the EGR valve; Motor circuit fault detection: no motor circuit fault in the EGR valve; First operating state detection: the engine is in the first operating state; Coolant temperature sensor fault detection: no engine coolant temperature sensor fault; Catalyst fault detection: no catalytic converter fault; Particulate matter trap fault detection: no particulate matter trap fault; EGR temperature sensor fault detection: no EGR temperature sensor fault; EGR differential pressure sensor fault detection: no EGR differential pressure sensor fault.

[0009] In the above technical solution, the specific process of the EGR valve actual opening degree sampling step is as follows: Determine the number of samples per sampling cycle: Under the combined effect of various engine speeds, fresh air intake density, engine coolant temperature, and ignition angle efficiency, determine the minimum fluctuation period of the EGR valve inlet pressure, and use the number of times the EGR valve inlet pressure signal is collected during the minimum fluctuation period as the sampling number N; Read and update the array elements of the values ​​within the sampling cycle: Read the actual opening degree of the EGR valve sampled N times consecutively, and form it into an array [pct Act1 ,…,pct ActN ]; Update the elements in the array after each sampling period, retaining only the N most recent EGR valve openings; Array extreme value extraction: Extract [pct Act1 ,…,pct ActN The maximum and minimum values ​​in [] represent the actual maximum opening degree (pct) of the EGR valve, respectively. ActMax and the minimum actual opening degree of the EGR valve (pct) ActMin .

[0010] In the above technical solution, the specific process of determining the initial value of the actual opening degree of the EGR valve is as follows: Based on the actual opening degrees of the EGR valve in the N arrays from the previous step, determine the maximum actual opening value pct of the EGR valve. ActMax and the minimum actual opening degree of the EGR valve (pct) ActMin ,pct ActMaxLimRaw =pct ActMax +Δ, pct ActMinLimRaw =pct ActMin -Δ, where Δ is the allowable deviation of the EGR valve opening accuracy.

[0011] In the above technical solution, the principle-based method for determining the final value of the actual opening degree of the EGR valve is as follows:

[0012] pct ActMaxLim (M) = pct ActMaxLim (M-1)+k[pct ActMaxLimRaw (M)-pct ActMaxLim (M-1)],

[0013] pct ActMinLim (M) = pct ActMinLim (M-1)+k[pct ActMinLimRaw (M)-pct ActMinLim (M-1)],

[0014] Where M is a natural number, pct ActMaxLim (M) represents the final maximum actual opening value of the EGR valve used to determine EGR valve malfunction during the Mth sampling period, pct.ActMinLim (M) represents the final value of the minimum actual opening degree of the EGR valve used to determine EGR valve malfunction during the Mth sampling period; pct ActMaxLim (M-1) represents the final value of the actual opening degree of the EGR valve used to determine EGR valve malfunction during the (M-1)th sampling period, pct. ActMinLim (M-1) represents the final value of the minimum actual opening degree of the EGR valve used to determine EGR valve failure during the (M-1)th sampling period; pct ActMaxLimRaw (M) represents the initial value of the actual opening degree of the EGR valve used to determine EGR valve malfunction during the Mth sampling period, pct. ActMinLimRaw (M) is the initial value of the minimum actual opening degree of the EGR valve used to determine the failure of the EGR valve in the Mth sampling period; and the moment when M=0 occurs when all conditions are met in the determination condition step of the EGR valve failure diagnosis activation; k is the filter coefficient.

[0015] In the above technical solution, the specific process for determining the final value of the actual opening of the EGR valve is as follows: EGR valve opening increase: the target opening of the EGR valve in the current sampling period is pct. Dsrd Not less than the target opening of the EGR valve in the previous sampling period (pct) Dsrd (z) is when pct Dsrd ≥pct Dsrd (z) indicates that the EGR valve opening is increasing, which will worsen the normal response performance of the EGR valve. Therefore, we have: pct ActMaxLim =pct ActMaxLimRaw +Δpctrate×ΔT,pct ActMinLim =pct ActMinLimRaw -Δpctrate×ΔT; EGR valve opening reduction: the target EGR valve opening pct in the current sampling period. Dsrd The EGR valve target opening (pct) is less than that of the previous sampling period. Dsrd (z) is when pct Dsrd <pct Dsrd (z) indicates that as the EGR valve opening increases or decreases, the normal response performance of the EGR valve will improve. Therefore:

[0016] pct ActMaxLim =pct ActMaxLimRaw -Δpctrate×ΔT,

[0017] pct ActMinLim =pct ActMinLimRaw+Δpctrate×ΔT; where ΔT is the sampling period, which is the time it takes for the engine to rotate 720° / Cnt, and Δpctrate is the allowable rate of change of the sampling period, which is determined by the engine speed n, the actual fresh air intake density rho, and the booster actuator opening pct. BoostAct The ratio r of the current actual oxygen storage capacity of the catalyst to its maximum oxygen storage capacity. CatOxy The pressure difference p between the inlet and outlet of the particulate matter collector GPFDiff Particulate matter collector temperature T GPF Battery voltage V Battery The determination is made jointly; the basic rate of change of the sampling period is calculated and judged as follows: Under different engine speeds and actual fresh air intake densities, if the opening of the boost actuator is larger, the boost capacity is stronger, the energy of the exhaust gas after boosting is weaker, and the EGR valve is more difficult to operate, at which point Δpctrate is larger; similarly, the ratio r of the catalytic converter storage capacity to the maximum oxygen storage capacity. CatOxy The smaller the value, the more oxygen the catalytic converter stores, resulting in weaker exhaust gas energy after the catalytic converter, making it more difficult for the EGR valve to operate, and thus a larger Δpctrate. Similarly, a larger GPF pressure differential and higher GPF temperature result in stronger GPF carbon removal capabilities, weakening exhaust gas energy after the GPF, making it more difficult for the EGR valve to operate, and thus a larger Δpctrate. Since the EGR valve actuator motor relies on battery power, the lower the battery voltage, the larger the Δpctrate. Therefore:

[0018] Δpctrate=Δpctrate Base ×f(n,rho)×f(n,pct BoostAct )×f(n,r CatOxy )×f(n,p GPFDiff )×f(p GPFDiff ,T GPF )×f(V Battery )×(1+r Adapt ), where Δpctrate Base The basic rate of change of the sampling period, obtained by benchmarking EGR valves with and without performance failures and mixed normal operating valves, can accurately identify whether an EGR valve has experienced performance failure. The parameters used in this identification process are as follows: f(n,rho) is the first correction factor determined by engine speed and actual fresh air intake density, and f(n,pct) is... BoostAct (pct represents engine speed and booster actuator opening) BoostAct The determined second correction factor; f(n,r) CatOxy The value r represents the ratio of engine speed to the current actual oxygen storage capacity of the catalyst and its maximum oxygen storage capacity. CatOxy The determined third correction factor; f(n,p)GPFDiff ) represents the engine speed and the pressure difference between the GPF inlet and outlet, p. GPFDiff The determined fourth correction factor; f(p) GPFDiff ,T GPF ) represents the pressure difference p between the GPF inlet and outlet. GPFDiff and GPF temperature T GPF The determined fifth correction factor; f(V) Battery ) represents the battery voltage V Battery The determined sixth correction factor, r Adapt This is the self-learning update correction factor. If it has never been updated successfully through self-learning or has never been updated through self-learning before, its initial value is 0. After successful self-learning, the updated self-learning update correction factor r is used. Adapt The larger the opening of the booster actuator, the stronger the boosting capacity, but the weaker the energy of the boosted exhaust gas, making it more difficult for the EGR valve to operate, and thus the larger Δpctrate; the ratio r of the catalytic converter's storage capacity to its maximum oxygen storage capacity. CatOxy The smaller the value, the more oxygen the catalytic converter stores, resulting in weaker exhaust gas energy after the catalytic converter, making it more difficult for the EGR valve to operate, and thus a larger Δpctrate. Similarly, a larger GPF pressure difference results in stronger GPF carbon removal capabilities, weakened exhaust gas energy after the GPF, and more difficult EGR valve operation, again leading to a larger Δpctrate. Furthermore, a larger GPF pressure difference and higher GPF temperature also result in stronger GPF carbon removal capabilities, weakened exhaust gas energy after the GPF, and more difficult EGR valve operation, again leading to a larger Δpctrate. Additionally, a higher battery voltage and motor operating current result in better response capability, thus a smaller Δpctrate.

[0019] In the above technical solution, in the step of determining the final value of the actual opening degree of the EGR valve, the self-learning update correction factor r in the sub-step of calculating and judging the basic rate of change of the sampling period Adapt The learning content is as follows:

[0020] Steady-state operating condition judgment: First, determine whether the EGR valve is operating under steady-state conditions. When all conditions are met for steady-state operating condition judgment, the self-learning update correction factor r is performed. Adapt Increment the number of times the condition is met by 1; Self-learning update correction factor learning method: When the number of times the condition is met exceeds a preset number, determine whether the difference between the target EGR rate and the actual EGR rate exceeds a third preset value, whether the fluctuation range of the actual EGR rate is within a fourth preset value, and whether the EGR valve malfunction has occurred. Adjust the self-learning update correction factor r accordingly. Adapt Increase the first preset value, decrease the second preset value, decrease the third preset value, or decrease the fourth preset value; if the steady-state condition judgment is not met, the correction factor r is updated through self-learning. Adapt Remain unchanged.

[0021] In the above technical solution, the self-learning update correction factor r Adapt The learning content includes the following process for judging steady-state operating conditions: To determine whether the EGR valve is operating in a steady-state condition, fault detection can only be performed when the following conditions are met: Second operating state detection: the engine is in the second operating state; Engine speed fluctuation detection: the engine speed is within a certain range and enters the correction factor r. Adapt The engine speed fluctuations after learning are smaller; Actual fresh air intake density detection: The actual fresh air intake density is within a certain range and enters the correction factor r. Adapt The actual fresh air intake density fluctuates less after learning; Target EGR rate detection: The target EGR rate is greater than the first preset value, and it enters the self-learning update correction factor r. Adapt The target EGR rate stabilizes after learning; target EGR valve opening fluctuation detection: target EGR valve opening fluctuation range; difference between target opening and actual opening of the mixing valve detection: the difference between the target opening and actual opening of the mixing valve does not exceed the second preset value; engine coolant temperature detection: engine coolant temperature is within a certain range, and the engine coolant temperature fluctuation for entering the mixing valve response performance detection is small; EGR valve failure diagnosis condition detection: all conditions for EGR valve failure diagnosis are met; unupdated vehicle mileage detection: self-learning update correction factor r Adapt The vehicle mileage that has not been updated exceeds the preset mileage; if any of the above conditions are not met, the EGR valve failure detection will not be performed; if all the above conditions are met, the following condition will be checked again: the detection time for all the above conditions exceeds the preset time T0; after the above conditions are met, the self-learning update correction factor r will be performed. Adapt The number of times the condition is met is incremented by 1, and the cumulative increment within each vehicle driving cycle will not exceed 1. The self-learning update correction factor r is then used. Adapt After the update, the number of times the condition is met immediately returns to 0, and the accumulation resumes only after the condition is met again; the self-learning update correction factor r Adapt The specific arrangement of the self-learning update correction factor learning strategy in the learning content is as follows: Increase the first preset amount: If the number of times the condition is met exceeds the preset number, the following conditions must be met: the difference between the target EGR rate and the actual EGR rate does not exceed the third preset value; and the fluctuation range of the actual EGR rate is within the fourth preset value; and no EGR valve failure has occurred, then the self-learning update correction factor r AdaptIncrease the first preset value. This is for cases where EGR rate control accuracy is high and the actual EGR rate is stable, indicating good EGR valve performance. Therefore, increase the threshold for EGR valve failure to avoid false alarms. Subtract the second preset value: If the number of times the condition is met exceeds a preset number, all of the following conditions must be met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; the actual EGR rate fluctuation range is within the fourth preset value; and no EGR valve failure has occurred; and simultaneously, one of the following two conditions must be met: pct Act The minimum value during the period when the condition is met and pct ActMinLim The difference is less than the fifth preset value, or, pct ActMaxLim With pct Act If the difference between the maximum values ​​during the period when the conditions are met is less than the sixth preset value, then the self-learning update correction factor r before the update will be adjusted. Adapt Subtracting the second preset value indicates that the EGR rate control accuracy is not high, but the actual EGR rate is stable, and the EGR valve is at critical failure. This indicates poor EGR valve performance, so the threshold for EGR valve failure should be reduced to report the fault as early as possible. Subtracting the third preset value: If the number of times this condition is met exceeds a preset number, all of the following conditions must be met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; the fluctuation range of the actual EGR rate is not within the fourth preset value; and no EGR valve failure has occurred; and simultaneously, one of the following two conditions must be met: pct Act The minimum value during the period when the condition is met and pct ActMinLim The difference is less than the fifth preset value, or, pct ActMaxLim With pct Act If the difference between the maximum values ​​during the period when the conditions are met is less than the sixth preset value, then the self-learning update correction factor r before the update will be adjusted. Adapt Immediately subtract the third preset value. This situation occurs when the EGR rate control accuracy is low, the actual EGR rate is unstable, and the EGR valve experiences critical failure. In this case, the EGR valve's performance is very poor, so the threshold for EGR valve failure is further reduced to report the fault earlier. Subtract the fourth preset value: If the number of times the condition is met exceeds a preset number, and the following conditions are met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; the actual EGR rate fluctuation range is not within the fourth preset value; and an EGR valve failure occurs, then the self-learning update correction factor r will be adjusted accordingly. Adap Immediately subtract the fourth preset value from t. This situation indicates that the EGR rate control accuracy is not high, the actual EGR rate is unstable, and the EGR valve has failed. In this case, the EGR valve's performance is extremely poor. Therefore, the threshold for EGR valve failure is reduced to a wider range to report the fault earliest. The second preset value is not greater than the third preset value, and the third preset value is not greater than the fourth preset value. In all cases except steady-state operation, the self-learning update correction factor r is used. Adap t remains unchanged.

[0022] The present invention also provides an EGR valve malfunction diagnosis device, which has a computer program capable of executing an EGR valve malfunction diagnosis method.

[0023] The present invention provides a method and apparatus for diagnosing EGR valve malfunction, which has the following advantages: it can reasonably identify the impact of the EGR valve's operating characteristics on the exhaust system, thereby making early judgments on EGR valve malfunction; and it can self-learn and update the EGR valve's performance judgment threshold based on the EGR system's performance, thereby making more reasonable judgments on EGR malfunction. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the low-voltage EGR system architecture of the present invention;

[0025] Figure 2 This is a schematic diagram illustrating the overall concept of the EGR valve failure diagnosis method of the present invention;

[0026] Figure 3 This is a schematic diagram of the specific process of the EGR valve failure diagnosis method of the present invention;

[0027] Figure 4 This is a flowchart illustrating the sampling step of the actual opening degree of the EGR valve in the EGR valve failure diagnosis method of the present invention.

[0028] Figure 5 This is a flowchart illustrating the method for determining the number of samples N in the EGR valve actual opening degree sampling step of the EGR valve failure diagnosis method of the present invention.

[0029] Figure 6 This is a schematic diagram of the specific process for determining the final value of the actual opening degree of the EGR valve in the EGR valve failure diagnosis method of the present invention.

[0030] Figure 7 This invention's EGR valve failure diagnosis method includes a self-learning update correction factor r for the sub-step of calculating and judging the basic rate of change of the sampling period, which is part of the step of determining the final value of the actual opening of the EGR valve. Adapt A schematic diagram illustrating the overall process of learning methods;

[0031] Figure 8 This invention's EGR valve failure diagnosis method includes a self-learning update correction factor r for the sub-step of calculating and judging the basic rate of change of the sampling period, which is part of the step of determining the final value of the actual opening of the EGR valve. Adapt A schematic diagram illustrating the conditions for judging steady-state operating conditions in learning methods;

[0032] Figure 9This invention's EGR valve failure diagnosis method includes a self-learning update correction factor r for the sub-step of calculating and judging the basic rate of change of the sampling period, which is part of the step of determining the final value of the actual opening of the EGR valve. Adapt A flowchart illustrating the self-learning update correction factor learning strategy in learning methods;

[0033] Figure 10 This is a schematic diagram of the EGR valve failure diagnosis device of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0035] Low-voltage EGR system architecture such as Figure 1 As shown, the low-pressure EGR system includes: air filter, turbocharger compressor, throttle valve, engine, turbocharger turbine, catalytic converter, particulate filter, EGR cooler, EGR valve, EGR temperature sensor, EGR differential pressure sensor, flow meter and linear oxygen sensor, mixing valve, etc.

[0036] The turbocharger compressor compresses fresh air for boost; the turbocharger turbine controls the turbine's efficiency by adjusting the opening of the turbocharger's exhaust bypass valve, thus achieving different boost capacities. Compared to the non-low-pressure EGR system, the low-pressure EGR system adds the following components: EGR cooler, EGR temperature sensor, EGR valve, EGR differential pressure sensor, mixing valve, flow meter, and oxygen sensor. The flow meter, installed between the air filter and the mixing valve, detects the flow rate of fresh air entering the engine. The mixing valve regulates the pressure at the EGR valve outlet, increasing the pressure differential across the EGR valve and improving the EGR rate. The mixing valve consists of a position sensor, an actuator motor, and a valve plate. The position sensor reads the position of the valve plate, i.e., the opening degree of the mixing valve. The actuator motor controls the valve plate's movement, ensuring that the actual opening degree of the mixing valve follows the target opening degree. The oxygen sensor, installed between the compressor and the throttle valve, near the throttle valve, is used to detect the flow rate of the air-fuel mixture entering the cylinder. The EGR cooler is used to cool the exhaust gas, facilitating increased exhaust gas flow and reduced exhaust gas temperature. The EGR valve acts as a throttling device, controlling the flow rate of exhaust gas entering the cylinder. The EGR temperature sensor detects the temperature of the exhaust gas entering the EGR valve. The EGR differential pressure sensor detects the inlet and outlet pressure signals of the EGR valve and can detect the pressure difference of the exhaust gas between the two sides of the EGR valve.

[0037] See Figure 2 The principle of the EGR valve failure diagnosis method of the present invention includes the following aspects:

[0038] Determine the conditions for activating the EGR valve failure diagnosis. Once the diagnosis activation conditions are met, read and retain the N actual opening degrees of the EGR valve in the most recent time period, and determine the initial and final values ​​of the actual opening degree of the EGR valve respectively.

[0039] The self-learning update correction factor r of the EGR valve under various operating states is updated based on the EGR valve's operating status. Adapt ;

[0040] The actual opening degree of the EGR valve is compared with the final value of the maximum actual opening degree of the EGR valve and the final value of the minimum actual opening degree of the EGR valve to determine whether the EGR valve has failed to operate.

[0041] See Figure 3 The method for diagnosing EGR valve malfunctions according to the present invention is as follows:

[0042] The first step is to determine the activation conditions for EGR valve malfunction diagnosis: The activation conditions for EGR valve malfunction diagnosis must be met. EGR valve malfunction diagnosis can only be performed if all of the following conditions are satisfied; otherwise, performance testing will result in misjudgment if the conditions are not met. The conditions for EGR valve malfunction diagnosis are:

[0043] 1) Voltage fault detection: No battery voltage fault was found;

[0044] 2) Position sensor fault detection: The EGR valve has no position sensor fault;

[0045] 3) Motor circuit fault detection: The EGR valve has no motor circuit faults (such as open circuit, short circuit, etc.);

[0046] 4) First operating state detection: The engine is in the first operating state;

[0047] 5) Coolant temperature sensor fault detection: The engine coolant temperature sensor has no faults;

[0048] 6) Catalyst fault detection: No catalyst fault;

[0049] 7) Particulate matter filter fault detection: No GPF (particulate matter filter related fault);

[0050] 8) EGR temperature sensor fault detection: The EGR temperature sensor is fault-free;

[0051] 9) EGR differential pressure sensor fault detection: The EGR differential pressure sensor is fault-free.

[0052] Step 2, see Figure 4 EGR valve actual opening degree sampling:

[0053] Determine the number of samples per sampling period: After all the above conditions are met, read the actual opening of the EGR valve for N consecutive samples. Each sampling period is the average engine rotation angle during the exhaust stroke of each cylinder, i.e., 720° / Cnt, where Cnt is the number of engine cylinders. For a 4-cylinder engine, the period is 720° / 4 = 180°. The purpose of this design is that exhaust gas is discharged during each exhaust process, causing fluctuations in the EGR valve inlet pressure, thus affecting the periodic airflow impact of the EGR valve and causing EGR valve fluctuations. Experimental studies have found that engine speed, load (intake density of fresh air into the cylinder), engine coolant temperature (referred to as water temperature), and ignition timing efficiency all affect the degree of EGR valve inlet pressure fluctuation to varying degrees, thus affecting EGR valve fluctuations. See also... Figure 5 The sampling number N is determined as follows: Under different engine speeds, loads, water temperatures, and ignition angle efficiencies, the minimum fluctuation period of the EGR valve inlet pressure (the sampling period of the EGR valve inlet pressure is also 720° / Cnt) is determined, and the number of times the EGR valve inlet pressure signal with the minimum fluctuation period is collected is taken as the sampling number N. In this example, the sampling number N is determined as follows: N = max[f(n,rho), f(n,T)]. Coolant ), f(n,r SprkEff )],

[0054] First, there is a linear positive correlation between different engine speeds and loads, as shown in Table 1 below:

[0055] Table 1

[0056]

[0057]

[0058] Secondly, when the water temperature is low, the engine combustion temperature is low, the heat release rate of the combustion flame is low, the exhaust flow impact is weak, and the EGR valve inlet pressure fluctuation is low. Based on this, the calibration results are as follows, as shown in Table 2 below:

[0059] Table 2

[0060]

[0061] Secondly, the lower ignition angle efficiency results in more combustion work and greater exhaust energy, which significantly affects the EGR valve inlet pressure fluctuation, as detailed in Table 3 below:

[0062] Table 3

[0063]

[0064] NA: represents no unit.

[0065] Read the values ​​within the sampling period to form an array element and update: Based on the above, the number of sampling times N for the actual opening degree of the EGR valve can be determined and formed into an array [pct Act1 ,…,pct ActN ], where pct Act1 The actual opening degree of the EGR valve in the current sampling period, pct ActN This represents the actual opening degree of the EGR valve for the first N-1 sampling periods. The elements in the array are updated after each sampling period, retaining only the latest N actual EGR valve opening degrees.

[0066] Array extreme value extraction: [pct Act1 ,…,pct ActN The maximum and minimum values ​​in [] represent the actual maximum opening degree (pct) of the EGR valve, respectively. ActMax and the minimum actual opening degree of the EGR valve (pct) ActMin .

[0067] The third step is to determine the initial value of the actual opening degree of the EGR valve: determine the initial value (pct) of the maximum actual opening degree of the EGR valve used to determine whether the EGR valve has failed. ActMaxLimRaw and the initial value of the actual opening degree of the EGR valve (pct) ActMinLimRaw The method for determining this is as follows: Based on the actual opening degree of the EGR valve in the N arrays from the previous step, read the maximum actual opening degree (pct) of the EGR valve. ActMax and the minimum actual opening degree of the EGR valve (pct) ActMin To confirm. pct ActMaxLimRaw =pct ActMax +Δ, pct ActMinLimRaw =pct ActMin -Δ, where Δ is the allowable deviation of the EGR valve opening accuracy (i.e., the maximum allowable deviation between the target opening of the EGR valve and the actual opening of the EGR valve is 1% in this example; to avoid incorrect detection of response performance, Δ is taken as 2% in this example).

[0068] Step 4: Determine the final actual opening value of the EGR valve: Determine the final maximum actual opening value (pct) of the EGR valve used to determine EGR valve failure. ActMaxLim And the actual minimum and final value of the EGR valve opening (pct) ActMinLim The principle behind its determination method is as follows:

[0069] pct ActMaxLim (M) = pct ActMaxLim (M-1)+k[pct ActMaxLimRaw (M)-pct ActMaxLim (M-1)],

[0070] pct ActMinLim (M) = pct ActMinLim(M-1)+k[pct ActMinLimRaw (M)-pct ActMinLim (M-1)],

[0071] Where M is a natural number, and in one or more embodiments, M = 1, 2, 3, ...; pct ActMaxLim (M) and pct ActMinLim (M) represents the final maximum and minimum actual opening values ​​of the EGR valve, used to determine EGR valve malfunction during the Mth sampling period; pct ActMaxLim (M-1) and pct ActMinLim (M-1) represents the final maximum and minimum actual opening values ​​(pct) of the EGR valve, used to determine EGR valve malfunction during the (M-1)th sampling period. ActMinLim ;pct ActMaxLimRaw (M) and pct ActMinLimRaw (M) represents the initial maximum and minimum actual opening values ​​of the EGR valve, respectively, used to determine EGR valve malfunction during the Mth sampling period. Specifically, M = 0 occurs when all conditions in the first step of activating EGR valve malfunction diagnosis are met. k is the filtering coefficient, and the method for determining the filtering coefficient k will be described in detail below. The purpose of filtering the actual opening of the EGR valve used to determine EGR valve malfunction is to filter the exhaust gas after engine combustion, which enters the EGR valve after passing through the turbocharger, catalytic converter, and GPF (Gas Particulate Filter). If the exhaust gas flow direction is the same as the EGR valve's operation, it will improve the EGR valve's responsiveness; however, if the exhaust gas flow direction is opposite to the EGR valve's operation, it will worsen the EGR valve's responsiveness.

[0072] See Figure 6 Based on the aforementioned principle, the specific process for determining the final value of the actual opening degree of the EGR valve is as follows:

[0073] 1) Increased EGR valve opening: The target opening of the EGR valve (pct) in the current sampling period. Dsrd Not less than the target opening of the EGR valve in the previous sampling period (pct) Dsrd (z) When (the method for determining the target opening of the EGR valve can be found in patent CN202211297028.7 "A Control Method for the Target Opening of an EGR Valve"), i.e., pct Dsrd ≥pct Dsrd (z) indicates that the EGR valve opening is increasing. Since the airflow direction is opposite to the EGR valve's operating direction, the normal response performance of the EGR valve will deteriorate. Therefore:

[0074] pct ActMaxLim =pct ActMaxLimRaw+Δpctrate×ΔT,

[0075] pct ActMinLim =pct ActMinLimRaw -Δpctrate×ΔT,

[0076] 2) EGR valve opening decreases: the target opening of the EGR valve (pct) in the current sampling period. Dsrd The EGR valve target opening (pct) is less than that of the previous sampling period. Dsrd (z) is when pct Dsrd <pct Dsrd (z) indicates that the EGR valve opening is decreasing. Since the airflow direction is the same as the EGR valve's operating direction, the normal response performance of the EGR valve will improve. Therefore:

[0077] pct ActMaxLim =pct ActMaxLimRaw -Δpctrate×ΔT,

[0078] pct ActMinLim =pct ActMinLimRaw +Δpctrate×ΔT,

[0079] Wherein, ΔT is the sampling period, which is the time it takes for the engine to rotate 720° / Cnt, and has a linear relationship with the engine speed; Δpctrate is the allowable rate of change of the sampling period, which is determined by the engine speed n, the actual fresh air intake density rho, and the turbocharger (turbine) opening pct. BoostAct (Acquired by the position sensor at the turbine) The ratio r of the current actual oxygen storage capacity of the catalyst to the maximum oxygen storage capacity (maximum oxygen storage capacity refers to the maximum oxygen storage capacity of the catalyst). CatOxy The pressure difference between the inlet and outlet of the GPF (particulate filter) (obtained or estimated by sensors) p GPFDiff GPF temperature (obtained or estimated by a sensor) T GPF Battery voltage V Battery Let's decide together.

[0080] 3) Calculation and judgment of the basic rate of change of the sampling period: Under different engine speeds and actual fresh air intake densities, if the opening of the boost actuator is larger and the boost capacity is stronger, the energy of the exhaust gas after boosting is weaker, and the EGR valve will be more difficult to operate. At this time, Δpctrate is larger; similarly, the ratio r of the catalytic converter storage capacity to the maximum oxygen storage capacity... CatOxyThe smaller the value, the more oxygen the catalytic converter stores, resulting in weaker exhaust gas energy after the catalytic converter, making it more difficult for the EGR valve to operate, and thus a larger Δpctrate. Similarly, a larger GPF pressure differential and higher GPF temperature result in stronger GPF carbon removal capabilities, weakening exhaust gas energy after the GPF, making it more difficult for the EGR valve to operate, and thus a larger Δpctrate. Since the EGR valve actuator motor relies on battery power, the lower the battery voltage, the larger the Δpctrate. Therefore:

[0081] Δpctrate=Δpctrate Base ×f(n,rho)×f(n,pct BoostAct )×f(n,r CatOxy )×f(n,p GPFDiff )×f(p GPFDiff ,T GPF )×f(V Battery )×(1+r Adapt ),

[0082] Where Δpctrate Base The engine speed is 1000 rpm, the actual fresh air intake density (rho) is 300 mg / L, and the turbocharger actuator (turbine) opening is pct. BoostAct The ratio r of the current actual oxygen storage capacity of the catalyst to its maximum oxygen storage capacity is 0%. CatOxy The pressure difference between the GPF inlet and outlet is 0.5 p. GPFDiff 30 kPa, GPF temperature T GPF 410℃, battery voltage V Battery The sampling period is 12V. The basic rate of change of the sampling period is obtained by comparing a failed EGR valve with a mixed-function valve. This basic rate of change of the sampling period can accurately identify whether an EGR valve has experienced a performance failure. In this example, Δpctrate Base Take 12.5% / s. During the identification of the basic rate of change of the sampling period, the following parameters are used: f(n,rho) is the first correction factor determined by engine speed and actual fresh air intake density, f(n,pct) BoostAct The engine speed and turbocharger actuator (turbine) opening are measured in pct values. BoostAct The determined second correction factor; f(n,r) CatOxy The value r represents the ratio of engine speed to the current actual oxygen storage capacity of the catalyst and its maximum oxygen storage capacity. CatOxy The determined third correction factor; f(n,p) GPFDiff ) represents the engine speed and the pressure difference between the GPF inlet and outlet, p. GPFDiff The determined fourth correction factor; f(p) GPFDiff ,T GPF ) represents the pressure difference p between the GPF inlet and outlet.GPFDiff and GPF temperature T GPF The determined fifth correction factor; f(V) Battery ) represents the battery voltage V Battery The determined sixth correction factor. Adapt This is the self-learning update correction factor, which will be explained in detail later. If it has never been successfully updated through self-learning or has never been updated through self-learning (i.e., the initial value), the initial value is 0. After successful self-learning, the updated self-learning update correction factor r will be used. Adapt The self-learning update correction factor r Adapt This information can be saved after the vehicle is powered off. See Tables 4-9 below for details on selecting various parameters:

[0083] In the process of identifying the basic rate of change of the sampling period, the first correction factor is determined by the engine speed and the actual fresh air intake density. The specific functional relationship is shown in Table 4 below:

[0084] Table 4

[0085]

[0086] In the selection of the second correction factor, the larger the opening of the booster actuator, the stronger the boosting capacity, and the weaker the energy of the boosted exhaust gas. This makes it more difficult for the EGR valve to operate, resulting in a larger Δpctrate. See Table 5 below for details:

[0087] Table 5

[0088]

[0089] In the selection of the third correction factor, the ratio r of catalyst storage capacity to maximum oxygen storage capacity is considered. CatOxy The smaller the value, the more oxygen the catalytic converter stores, resulting in weaker exhaust gas energy after the catalytic converter. This makes it more difficult for the EGR valve to operate, and in this case, the larger the Δpctrate is. See Table 6 below for details:

[0090] Table 6

[0091]

[0092] In the selection of the fourth correction factor, the larger the GPF pressure difference, the stronger the GPF carbon removal ability. The energy of the exhaust gas after the GPF is weakened, making it more difficult for the EGR valve to operate. In this case, the larger Δpctrate is. See Table 7 below for details:

[0093] Table 7

[0094]

[0095]

[0096] In the selection of the fifth correction factor, the greater the GPF pressure difference and the higher the GPF temperature, the stronger the GPF carbon removal ability. The energy of the exhaust gas after the GPF is weakened, making it more difficult for the EGR valve to operate. In this case, the Δpctrate is larger. See Table 8 below for details:

[0097] Table 8

[0098]

[0099] In selecting the sixth correction factor, a larger battery voltage and a larger motor operating current result in better response capability, thus requiring a smaller correction factor. See Table 9 below for details:

[0100] Table 9

[0101]

[0102] Step 5, EGR valve malfunction judgment: When judging the malfunction of the EGR valve, if the actual opening degree of the EGR valve is less than the final value of the minimum actual opening degree of the EGR valve, i.e., pct Act <pct ActMinLim Or, the actual opening degree of the EGR valve is greater than the final value of the maximum actual opening degree of the EGR valve, i.e., pct Act >pct ActMaxLim This indicates that the EGR valve has experienced a malfunction sampling fault once, with a fault sampling time of 10ms. If this occurs within the current driving cycle, T... Total The accumulated fault time within the time frame (3000ms in this example) shall not be less than the fault time T. ErrLim (In this example, 2500ms) indicates that the EGR valve has failed; otherwise, no EGR valve failure has occurred within this driving cycle. Generally, a sampling failure does not necessarily mean the final failure has occurred; it simply means that the failure has occurred once. A failure is considered to have occurred only if the duration of the failure within a certain timeframe is relatively long. That is, T... Total If a sampling failure occurs (the opening degree is calculated every 10ms), the number of sampling failures multiplied by 10ms will be used as the failure time T. ErrLim .

[0103] It should be noted that the downtime T ErrLim It will continuously update and learn, and will save power-off data, with an initial value of 100ms.

[0104] See Figure 7 The following section will elaborate on the self-learning update correction factor r in the sub-step of calculating and judging the basic rate of change of the sampling period in the step of determining the final value of the actual opening of the EGR valve. Adapt The learning method, and its specific process are as follows:

[0105] See Figure 8 Steady-state operating condition judgment: self-learning update correction factor r Adapt The learning process needs to be performed under steady-state conditions. First, it is determined whether the EGR valve is operating under steady-state conditions. When the following conditions are met, the self-learning update correction factor r is performed. Adapt Fault detection can only proceed after the number of attempts is incremented by 1.

[0106] 1) Second operating state detection: The engine is in the second operating state;

[0107] 2) Engine speed fluctuation detection: The engine speed is within a certain range, in this example between 600 rpm and 5900 rpm, and is included in the correction factor r. Adap The engine speed fluctuation after t learning is small; in this embodiment, ±15 rpm is taken.

[0108] 3) Actual fresh air intake density detection: The actual fresh air intake density is within a certain range. In this embodiment, it is taken as between 300 mg / pl and 3000 mg / pl, and includes the correction factor r. Adapt The actual fresh air intake density fluctuation after learning is small; in this embodiment, it is taken as ±12 mgpl.

[0109] 4) Target EGR rate detection: If the target EGR rate is greater than the first preset value (in this embodiment, the first preset value is 0.05; if the target EGR rate is too small, the EGR system control will be unstable, resulting in large fluctuations in the target opening of the EGR valve, making it impossible to accurately detect the response performance of the mixing valve), and the self-learning update correction factor r is entered. Adapt The target EGR rate is stable after learning, meaning that the fluctuation range of the target EGR rate in this embodiment does not exceed ±1%.

[0110] 5) Target EGR valve opening fluctuation detection: The target EGR valve opening fluctuation range, in this embodiment, shall not exceed ±0.5%;

[0111] 6) Detection of the difference between the target opening degree and the actual opening degree of the mixing valve: The difference between the target opening degree and the actual opening degree of the mixing valve shall not exceed the second preset value (in this embodiment, the second preset value is ±0.5%).

[0112] 7) Engine coolant temperature detection: The engine coolant temperature is within a certain range (0℃ to 100℃ in this embodiment), and the engine coolant temperature fluctuation is small when entering the mixing valve response performance detection. In this embodiment, ±2℃ is taken.

[0113] 8) EGR valve failure diagnosis condition test: All conditions for EGR valve failure diagnosis are met;

[0114] 9) Vehicle mileage not updated: Self-learning update correction factor r AdaptThe corresponding vehicle mileage has not been updated (in the self-learning update correction factor r). Adapt After the update, the vehicle mileage is reset to zero and starts accumulating again. The mileage exceeds the preset mileage (10km in this example).

[0115] If any of the above conditions are not met, the EGR valve malfunction detection will not be performed. If all the above conditions are met, the following condition will be evaluated again:

[0116] 10) After all the above conditions are met, the detection time exceeds the preset time T0, which is 3 seconds in this embodiment.

[0117] Once the above conditions are met, the self-learning update correction factor r will be performed. Adapt The number of times the condition is met (referred to as the number of times the condition is met) is incremented by 1, and the cumulative number of times within each vehicle driving cycle will not exceed 1. The self-learning update correction factor r is then used. Adapt After the update, the number of times the condition is met will immediately return to 0, and the count will be accumulated again once the condition is met again.

[0118] See Figure 9 The self-learning update correction factor learning strategy is as follows: When the number of times the condition is met exceeds a preset number, it is determined whether the difference between the target EGR rate and the actual EGR rate exceeds a third preset value, whether the fluctuation range of the actual EGR rate is within a fourth preset value, and whether the EGR valve malfunction has occurred. The self-learning update correction factor r is adjusted accordingly. Adapt Increase the first preset value, decrease the second preset value, decrease the third preset value, or decrease the fourth preset value; if the steady-state condition judgment is not met, the correction factor r is updated through self-learning. Adapt The arrangements remain unchanged, as follows:

[0119] 1) Increase the first preset amount: If the number of times the condition is met exceeds the preset number (1000 in this embodiment), the following conditions are met: the difference between the target EGR rate and the actual EGR rate does not exceed the third preset value (±1% in this embodiment); and the fluctuation range of the actual EGR rate is within the fourth preset value (±1% in this embodiment); and no EGR valve malfunction occurs.

[0120] Then the self-learning update correction factor r Adapt Immediately and definitely increase the first preset amount (r before the upcoming update). Adapt In addition to the first preset amount (0.005 in this embodiment), this situation indicates that the EGR rate control accuracy is high and the actual EGR rate is stable, resulting in good EGR valve performance. Therefore, the threshold for EGR valve failure can be increased to avoid false alarms.

[0121] 2) Subtract the second preset amount: If the number of times the condition is met exceeds the preset number (1000 in this embodiment), the following conditions are met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value (±1% in this embodiment); and the fluctuation range of the actual EGR rate is within the fourth preset value (±1% in this embodiment); and no EGR valve failure occurs; and one of the following two conditions is met (pct Act The minimum value during the period when the condition is met and pct ActMinLim The difference is less than the fifth preset value, or, pct ActMaxLim With pct Act The difference between the maximum values ​​during the period when the conditions are met is less than the sixth preset value (2% in this embodiment).

[0122] Then the self-learning update correction factor r Adapt Immediately subtract a certain amount of the second preset value (r before the update). Adapt Subtract the second preset amount (0.002 in this embodiment). In this case, the EGR rate control accuracy is not high, but the actual EGR rate is stable, and the EGR valve is at critical failure. Therefore, the EGR valve's working performance is poor, and it is necessary to reduce the threshold for EGR valve failure to report the fault as early as possible.

[0123] 3) Subtract the third preset amount: If the number of times the condition is met exceeds the preset number (1000 in this embodiment), the following conditions are met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value (±1% in this embodiment); and the fluctuation range of the actual EGR rate is not within the fourth preset value (±1% in this embodiment); and no EGR valve failure has occurred; and one of the following two conditions is met (pct Act The minimum value during the period when the condition is met and pct ActMinLim The difference is less than the fifth preset value, or, pct ActMaxLim With pct Act The difference between the maximum values ​​during the period when the conditions are met is less than the sixth preset value (2% in this embodiment).

[0124] Then the self-learning update correction factor r Adapt Immediately subtract a certain amount of the third preset (r before the update) Adapt Subtract the third preset amount (0.005 in this embodiment). This situation occurs when the EGR rate control accuracy is not high, the actual EGR rate is unstable, and the EGR valve experiences critical failure. In this case, the EGR valve's performance is very poor, so it is necessary to further reduce the threshold for EGR valve failure to report the fault earlier.

[0125] 4) Subtract the fourth preset value: If the number of times the condition is met exceeds the preset number (1000 in this embodiment), the following conditions are met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value (±1% in this embodiment); and the fluctuation range of the actual EGR rate is not within the fourth preset value (±1% in this embodiment); and an EGR valve malfunction occurs.

[0126] Then the self-learning update correction factor r Adapt Immediately subtract a certain amount of the fourth preset (r before the upcoming update) Adapt Subtract the fourth preset amount (0.01 in this embodiment). In this case, the EGR rate control accuracy is not high, the actual EGR rate is unstable, and the EGR valve fails. The EGR valve's performance is extremely poor, so the threshold for EGR valve failure needs to be reduced to a wider range to report the fault as early as possible.

[0127] The second preset value is not greater than the third preset value, and the third preset value is not greater than the fourth preset value, that is, the second preset value ≤ the third preset value ≤ the fourth preset value.

[0128] In cases other than steady-state conditions, the self-learning update correction factor r Adapt Remain unchanged.

[0129] The above completes the description of the EGR valve failure diagnosis method.

[0130] See Figure 10 The EGR valve failure diagnosis device of the present invention includes the following parts:

[0131] The module for determining the activation conditions for EGR valve malfunction diagnosis: determines the conditions for activating EGR valve malfunction diagnosis. EGR valve malfunction diagnosis will only be performed after all activation conditions are met.

[0132] EGR valve actual opening sampling module: Reads the actual opening of the EGR valve from N consecutive samples and arranges them into an array [pct Act1 ,…,pct ActN The array is updated after each sampling period ends, retaining only the N most recent EGR valve openings.

[0133] Module for determining the initial value of the actual opening of the EGR valve: Determines the initial value (pct) of the maximum actual opening of the EGR valve used to determine EGR valve malfunction. ActMaxLimRaw and the initial value of the actual opening degree of the EGR valve (pct) ActMinLimRaw ;

[0134] Module for determining the final actual opening value of the EGR valve: Determines the final maximum actual opening value (pct) of the EGR valve. ActMaxLim And the actual minimum and final value of the EGR valve opening (pct)ActMinLim ;

[0135] EGR valve failure detection module: If the actual opening degree of the EGR valve is less than the final value of the minimum actual opening degree or greater than the final value of the maximum actual opening degree, it indicates that the EGR valve has failed once. The time of failure is used as the sampling period. If it occurs within the current driving cycle, the current driving cycle time T... Total The cumulative failure occurrence time within the time limit shall not be less than the failure time T. ErrLim This indicates that the EGR valve has failed.

[0136] The key technical points and technical principles of this invention are as follows:

[0137] 1. Diagnosis of EGR valve malfunction;

[0138] 2. Failure diagnosis threshold learning factor update method.

[0139] Definitions of abbreviations and key terms:

[0140] EGR (Exhaust Gas Recirculation): Exhaust gas recirculation;

[0141] GPF (Gasoline Particulate Filter): Gasoline engine particulate filter.

[0142] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0143] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A method for diagnosing EGR valve malfunction, characterized in that: Includes the following: The conditions for activating the EGR valve failure diagnosis are determined. Once the activation conditions are met, the actual opening degrees of the EGR valve within the most recent time period are read and retained. The initial and final values ​​of the actual opening degrees of the EGR valve are determined respectively. The actual opening degrees of the EGR valve are compared with the final values ​​of the maximum and minimum actual opening degrees of the EGR valve to determine whether the EGR valve has failed. The specific process is as follows: Determining the activation conditions for EGR valve failure diagnosis: Determine the conditions for activation of EGR valve failure diagnosis. EGR valve failure diagnosis will only be performed after all activation conditions are met. EGR valve actual opening sampling: Read the actual opening of the EGR valve from N consecutive samples and arrange them into an array. ,…, The array is updated after each sampling period ends, retaining only the N most recent EGR valve openings. Determine the initial value of the actual opening degree of the EGR valve: Determine the initial value of the maximum actual opening degree of the EGR valve used to determine EGR valve failure. and the initial value of the actual minimum opening of the EGR valve ; Determine the final actual opening value of the EGR valve: Determine the final maximum actual opening value of the EGR valve. and the final value of the actual minimum opening of the EGR valve ; EGR valve malfunction detection: If the actual opening degree of the EGR valve is less than the final value of the minimum actual opening degree, or the actual opening degree of the EGR valve is greater than the final value of the maximum actual opening degree, it indicates that the EGR valve has malfunctioned once. The time of the malfunction is used as the sampling period time. If it occurs within the current driving cycle, the current driving cycle time is considered as follows. The cumulative failure occurrence time within the time limit shall not be less than the failure time. This indicates that the EGR valve has failed.

2. The EGR valve failure diagnosis method according to claim 1, characterized in that: The specific conditions for determining the activation of the EGR valve failure diagnosis step are as follows: Voltage fault detection: No battery voltage fault; Position sensor fault detection: EGR valve has no position sensor fault; Motor circuit fault detection: No motor circuit fault in EGR valve; First operating status detection: The engine is in the first operating state; Coolant temperature sensor fault detection: The engine coolant temperature sensor is not faulty; Catalyst fault detection: No catalyst fault; Particulate matter trap fault detection: The particulate matter trap is not faulty; EGR temperature sensor fault detection: The EGR temperature sensor is not faulty; EGR differential pressure sensor fault detection: The EGR differential pressure sensor is not faulty.

3. The EGR valve failure diagnosis method according to claim 2, characterized in that: The specific process for sampling the actual opening degree of the EGR valve is as follows: Determine the number of samplings for each sampling period: Under the combined effects of various engine speeds, fresh air intake density entering the cylinder, engine coolant temperature, and ignition angle efficiency, determine the minimum fluctuation period of the EGR valve inlet pressure, and use the number of times the EGR valve inlet pressure signal with the minimum fluctuation period is collected as the number of samplings N. Read the values ​​within the sampling period to form an array element and update: Read the actual opening degree of the EGR valve from N consecutive samples and form it into an array [ ,…, After each sampling period, the elements in the array are updated, and only the N most recent EGR valve openings are retained. Array extreme value extraction: Extract [ ,…, The maximum and minimum values ​​in [] represent the actual maximum opening degree of the EGR valve, respectively. and the minimum actual opening of the EGR valve .

4. The EGR valve failure diagnosis method according to claim 3, characterized in that: The specific process for determining the initial value of the actual opening degree of the EGR valve is as follows: Based on the actual opening degree of the EGR valve in the N arrays from the previous step, determine the maximum actual opening value of the EGR valve. and the minimum actual opening of the EGR valve , , ,in, This refers to the allowable deviation in the opening accuracy of the EGR valve.

5. The EGR valve failure diagnosis method according to claim 4, characterized in that: The principle-based method for determining the final value of the actual opening degree of the EGR valve is as follows: ， ， in, For natural numbers, This is the final value of the actual opening degree of the EGR valve in the Mth sampling period, used to determine the failure of the EGR valve. This is the final value of the minimum actual opening degree of the EGR valve used to determine the failure of the EGR valve during the Mth sampling period; This is the final value of the actual opening degree of the EGR valve, used to determine the failure of the EGR valve during the (M-1)th sampling period. This is the final value of the minimum actual opening degree of the EGR valve used to determine the failure of the EGR valve during the M-1th sampling period; This is the initial value of the actual opening degree of the EGR valve in the Mth sampling period, used to determine the failure of the EGR valve. is the initial value of the minimum actual opening degree of the EGR valve used to determine the failure of the EGR valve in the Mth sampling period; and the moment when M=0 occurs when all conditions are met in the determination condition step of the EGR valve failure diagnosis activation; k is the filter coefficient.

6. The EGR valve failure diagnosis method according to claim 5, characterized in that: The specific process for determining the final actual opening value of the EGR valve is as follows: EGR valve opening increased: Target opening of the EGR valve in the current sampling period. Not less than the target opening of the EGR valve in the previous sampling period At that time, that is This indicates that as the EGR valve opening increases, the normal response performance of the EGR valve will deteriorate. Therefore: ， ； EGR valve opening decreases: the target opening of the EGR valve in the current sampling period. The EGR valve target opening is less than that of the previous sampling period. At that time, that is This indicates that as the EGR valve opening increases or decreases, the normal response performance of the EGR valve will improve. Therefore: ， ； in, The sampling period is the time it takes for the engine to rotate 720° / Cnt. The allowable rate of change for the sampling period is determined by the engine speed n and the actual fresh air intake density. , Intensifier actuator opening The ratio of the current actual oxygen storage capacity to the maximum oxygen storage capacity of the catalyst. Pressure difference between the inlet and outlet of the particulate matter collector Particulate matter collector temperature Battery voltage Let's decide together; Calculation and judgment of the basic rate of change of the sampling period: Under different engine speeds and actual fresh air intake densities, if the opening of the booster actuator is larger and the boosting capacity is stronger, the energy of the boosted exhaust gas will be weaker, and the EGR valve will have more difficulty operating. The larger the value; similarly, the ratio of catalyst storage capacity to maximum oxygen storage capacity. The smaller the value, the more oxygen the catalytic converter stores, resulting in reduced exhaust gas energy after the catalytic converter, making it more difficult for the EGR valve to operate. The larger the temperature of the GPF, the greater the pressure difference and the higher the temperature of the GPF, the stronger the carbon removal ability of the GPF. However, the energy of the exhaust gas after the GPF is weakened, making it more difficult for the EGR valve to operate. The larger the value; the EGR valve actuator motor control relies on battery power, and the lower the battery voltage, the more... Similarly, the larger it is, the more we have: ， in, The basic rate of change of the sampling period, obtained by comparing EGR valves with malfunctioning and mixed-function valves, can accurately identify whether an EGR valve has experienced malfunction. The parameters used in this identification process are as follows: The first correction factor is determined based on engine speed and actual fresh air intake density. For engine speed and booster actuator opening The determined second correction factor; The ratio of engine speed and the current actual oxygen storage capacity of the catalyst to its maximum oxygen storage capacity. A determined third correction factor; For engine speed and GPF inlet and outlet pressure difference The determined fourth correction factor; The pressure difference between the GPF inlet and outlet and GPF temperature The determined fifth correction factor; Battery voltage The determined sixth correction factor, This is the self-learning update correction factor. If it has never been updated successfully through self-learning or has never been updated through self-learning before, its initial value is 0. After successful self-learning, the updated self-learning update correction factor will be used. , The larger the opening of the booster actuator, the stronger the boosting capacity. However, the weaker the energy of the boosted exhaust gas, the more difficult it is for the EGR valve to operate. The larger; The ratio of catalyst storage capacity to maximum oxygen storage capacity The smaller the value, the more oxygen the catalytic converter stores, resulting in reduced exhaust gas energy after the catalytic converter, making it more difficult for the EGR valve to operate. The larger; The greater the pressure difference between the GPF and the exhaust gas, the stronger the carbon removal ability of the GPF. However, the reduced exhaust gas energy after the GPF makes it more difficult for the EGR valve to operate. The larger; The greater the pressure difference and the higher the GPF temperature, the stronger the GPF's carbon removal ability. However, the reduced exhaust gas energy after the GPF makes it more difficult for the EGR valve to operate. The larger; A higher battery voltage results in a higher motor operating current and better response capability. The smaller.

7. The EGR valve failure diagnosis method according to claim 6, characterized in that: In the step of determining the final actual opening value of the EGR valve, the self-learning update correction factor in the sub-step of calculating and judging the basic rate of change of the sampling period The learning content is as follows: Steady-state operating condition judgment: First, determine whether the EGR valve is operating under steady-state conditions. When all conditions are met for steady-state operating condition judgment, the correction factor is updated through self-learning. Increment the number of times the condition is met by 1; Self-learning update correction factor learning method: When the number of times the condition is met exceeds a preset number, it is determined whether the difference between the target EGR rate and the actual EGR rate exceeds a third preset value, whether the fluctuation range of the actual EGR rate is within a fourth preset value, and whether the EGR valve malfunction has occurred. The self-learning update correction factor is then adjusted accordingly. Increase the first preset amount, subtract the second preset amount, subtract the third preset amount, or subtract the fourth preset amount; If the steady-state condition judgment is not met, the self-learning update correction factor is activated. Remain unchanged.

8. The EGR valve failure diagnosis method according to claim 7, characterized in that: The self-learning update correction factor The specific process for determining steady-state operating conditions in the learning content is as follows: To determine whether the EGR valve is operating under steady-state conditions, fault detection can only be performed when all of the following conditions are met: Second operating status detection: The engine is in the second operating status; Engine speed fluctuation detection: The engine speed is within a certain range and enters the correction factor. The engine speed fluctuations were smaller after the learning process; Actual fresh air intake density detection: The actual fresh air intake density is within a certain range and includes the correction factor. The actual fresh air intake density fluctuations after the learning process were small. Target EGR rate detection: If the target EGR rate is greater than the first preset value, the self-learning update correction factor is initiated. The target EGR rate stabilizes after learning; Target EGR valve opening fluctuation detection: Target EGR valve opening fluctuation range; Detection of the difference between the target opening degree and the actual opening degree of the mixing valve: The difference between the target opening degree and the actual opening degree of the mixing valve shall not exceed the second preset value; Engine coolant temperature detection: The engine coolant temperature is within a certain range, and the engine coolant temperature fluctuation is small when entering the mixing valve response performance detection. EGR valve failure diagnosis condition test: All conditions for EGR valve failure diagnosis are met; Vehicle mileage detection not updated: self-learning update correction factor The corresponding vehicle mileage has not been updated and exceeds the preset mileage; If any of the above conditions are not met, the EGR valve failure detection will not be performed; if all of the above conditions are met, the following condition will be evaluated again: The detection time for all of the above conditions exceeds the preset time T0; Once the above conditions are met, the correction factor will be updated automatically through learning. The number of times the condition is met is incremented by 1, and the cumulative increment within each vehicle driving cycle will not exceed 1. The correction factor is then updated through self-learning. After the update, the number of times the condition is met will immediately return to 0, and the count will be repeated only after the condition is met again. The self-learning update correction factor The specific arrangement of the self-learning update correction factor learning strategy in the learning content is as follows: Increase the first preset amount: If the number of times the condition is met exceeds the preset number, the following conditions must be met: the difference between the target EGR rate and the actual EGR rate does not exceed the third preset value; the fluctuation range of the actual EGR rate is within the fourth preset value; and no EGR valve failure has occurred. Then the self-learning update correction factor Increase the first preset value. In this case, the EGR rate control accuracy is high and the actual EGR rate is stable, so the EGR valve works well. In this case, increase the threshold for EGR valve failure to avoid false alarms. Subtract the second preset amount: If the number of times the condition is met exceeds the preset number, all of the following conditions must be met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; and the fluctuation range of the actual EGR rate is within the fourth preset value; and no EGR valve failure has occurred; and one of the following two conditions must also be met: The minimum value during the period when the condition is met The difference is less than the fifth preset value, or, and The difference between the maximum values ​​during the period when the condition is met is less than the sixth preset value. Then the self-learning update correction factor before the update will be used. Subtracting the second preset amount, in this case, the EGR rate control accuracy is not high, but the actual EGR rate is stable, and the EGR valve is at critical failure, then the EGR valve performance is poor. Therefore, reduce the threshold for EGR valve failure and report the fault as early as possible. Subtract the third preset amount: If the number of times the condition is met exceeds the preset number, all of the following conditions must be met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; and the fluctuation range of the actual EGR rate is not within the fourth preset value; and no EGR valve failure has occurred; and one of the following two conditions must also be met: The minimum value during the period when the condition is met The difference is less than the fifth preset value, or, and The difference between the maximum values ​​during the period when the condition is met is less than the sixth preset value. Then the self-learning update correction factor before the update will be used. Immediately reduce the third preset amount. In this case, the EGR rate control accuracy is not high, the actual EGR rate is unstable, and the EGR valve is at critical failure. The EGR valve's working performance is very poor. Therefore, further reduce the threshold for EGR valve failure to report the fault earlier. Subtract the fourth preset amount: If the number of times the target EGR rate is satisfied exceeds the preset number of times, the following conditions must be met: the difference between the target EGR rate and the actual EGR rate exceeds the third preset value; Furthermore, the actual EGR rate fluctuation range is not within the fourth preset value; and the EGR valve malfunctions. Then the self-learning update correction factor before the update will be used. Immediately subtract the fourth preset amount. In this case, the EGR rate control accuracy is not high, the actual EGR rate is unstable, and the EGR valve fails. The EGR valve's performance is extremely poor. Therefore, the threshold for EGR valve failure is reduced to a wider range to report the fault as early as possible. The second preset amount is not greater than the third preset amount, and the third preset amount is not greater than the fourth preset amount; In cases other than steady-state conditions, self-learning updates the correction factor. Remain unchanged.

9. An EGR valve failure diagnosis device, comprising a computer program, characterized in that: The computer program is capable of performing the EGR valve malfunction diagnosis method as described in any one of claims 1 to 8.

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