Method and device for detecting response performance of engine hybrid valve

Abstract

The application discloses an engine mixed valve response performance detection method, comprising the following steps: arbitrary working condition mixed valve response performance detection: determining the mixed valve response performance detection condition, reserving N target openings, comparing the actual opening with the actual opening maximum final value or the actual opening minimum final value, and judging the mixed valve response performance; steady state working condition mixed valve response performance detection: judging whether the steady state working condition meets the condition, accumulating the first opening time t1 and the second opening time t2 respectively when the steady state working condition meets the condition, comparing t1 and t2 with respective limits respectively, and judging whether the mixed valve is in the steady state working condition response performance fault; as long as any one of the arbitrary working condition and the steady state working condition detection appears a fault, it is indicated that the mixed valve response performance has a fault. The application further discloses an engine mixed valve response performance detection device. The application can detect the fault of the mixed valve response performance according to the change of the mixed valve response performance, and can be widely applied to the engine control field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine control, in particular to an engine hybrid valve response performance detection method and device. BACKGROUND

[0002] Exhaust gas recirculation (EGR) takes exhaust gas from the exhaust system into the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock ability. Low-pressure EGR takes gas after the turbine, so there is no loss of turbine efficiency, and it can be used almost all the time. EGR improves fuel efficiency more significantly, but due to its low pressure difference, a large-diameter valve is needed to meet the flow requirements. In some operating conditions, the opening of the hybrid valve needs to be controlled to adjust the pressure at the outlet of the EGR valve, thereby improving the pressure difference on both sides of the EGR valve and improving the EGR rate. If the response performance of the hybrid valve deteriorates, the response performance of the EGR rate will deteriorate, so that the ability to improve fuel consumption, emissions, etc. cannot be optimized, and even engine combustion may be abnormal and cause engine combustion to shake.

[0003] Therefore, some manufacturers have proposed a technical solution, for example, an application number CN202011247319.6, with the invention name of "a target EGR rate calculation method and system", which determines the basic target EGR rate according to the engine speed and load; obtains the corresponding correction rate according to the special working condition; determines the initial target EGR rate according to the basic target EGR rate and each correction rate; determines whether EGR is activated according to the EGR activation state condition; divides the EGR state according to the judgment result, and determines the final target EGR rate. However, this scheme does not propose a fault detection method if the response performance of the hybrid valve is poor during the EGR rate calculation process.

[0004] In another patent application number CN202110184826.8, with the invention name of "EGR system hybrid valve target opening determination method", it is proposed that when the hybrid valve control enters the low-pressure EGR, different hybrid valve opening change rates are controlled according to different working conditions, and a fault detection method is not proposed if the response performance of the hybrid valve is poor. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the above background art, and to provide an engine hybrid valve response performance detection method and device, which can detect the fault of the hybrid valve according to the change of the response performance of the hybrid valve.

[0006] The application provides an engine hybrid valve response performance detection method, comprising arbitrary working condition hybrid valve response performance detection or / and steady state working condition hybrid valve response performance detection, wherein the arbitrary working condition hybrid valve response performance detection comprises determining hybrid valve response performance detection conditions, reading and retaining N hybrid valve target opening degrees in the latest time, respectively determining hybrid valve actual opening degree initial values and final values, comparing the hybrid valve actual opening degree with the hybrid valve actual opening degree maximum final value or the hybrid valve actual opening degree minimum final value, and judging the hybrid valve response performance; the steady state working condition hybrid valve response performance detection comprises judging whether the steady state working condition meets the conditions, performing hybrid valve response performance detection on the basis of meeting the steady state working condition, and respectively accumulating a first opening degree time t1 from a target EGR rate of 0 to a hybrid valve opening degree starting change and a second opening degree time t2 from the hybrid valve opening degree starting change to a fully open state, comparing t1 and t2 with respective limits, and judging whether the hybrid valve is in a steady state working condition response performance fault; as long as any one of the arbitrary working condition hybrid valve response performance detection and the steady state working condition hybrid valve response performance detection appears a fault, it is indicated that the hybrid valve response performance has a fault, otherwise, no fault occurs.

[0007] In the technical scheme, the specific process of the arbitrary working condition hybrid valve response performance detection step is as follows: the arbitrary working condition hybrid valve response performance detection condition determining step comprises determining the hybrid valve response performance detection conditions, and performing the hybrid valve response performance detection after determining that the detection conditions are met; the hybrid valve target opening degree sampling step comprises reading the hybrid valve target opening degrees in continuous N sampling times, and grouping the hybrid valve target opening degrees into an array [pct Dsrd1 ,…,pct DsrdN ], and updating the elements in the array after each sampling period, and only retaining the N hybrid valve target opening degrees in the latest time; the hybrid valve actual opening degree initial value determining step comprises determining a hybrid valve actual opening degree maximum initial value pct ActMaxRaw and a hybrid valve actual opening degree minimum initial value pct ActMinRaw ; the hybrid valve actual opening degree final value determining step comprises determining a hybrid valve actual opening degree maximum final value pct ActMaxLim and a hybrid valve actual opening degree minimum final value pct ActMinLim ; and the arbitrary working condition hybrid valve response performance judging step comprises: if the hybrid valve actual opening degree is less than the hybrid valve actual opening degree minimum final value or the hybrid valve actual opening degree is greater than the hybrid valve actual opening degree maximum final value, it is indicated that the hybrid valve performance appears a response performance sampling fault once, and the fault occurrence time is taken as a sampling period time; and if the fault occurrence time accumulation value in the T Total time in the driving cycle is not less than a fault time T ErrLim , it is indicated that the hybrid valve response performance has a fault.

[0008] In the technical solution, the specific conditions of the mixed valve response performance detection determining condition step are: voltage fault detection: no battery voltage fault; sensor fault detection: no position sensor fault of the mixed valve; motor circuit fault detection: no motor circuit fault of the mixed valve; first running state detection: the engine is in the first running state; the specific process of the mixed valve target opening sampling step is as follows: reading and forming an array: reading the mixed valve target opening of continuous N sampling times and forming an array [pct Dsrd1 ,…,pct DsrdN ]; element updating: updating the elements in the array after each sampling period, and only keeping the N mixed valve target openings in the recent time.

[0009] In the mixed valve target opening sampling step, the specific process of the sampling number N acquisition method is as follows: first, determining a sampling number basic value according to the engine speed and the actual fresh air intake density; second, determining a first sampling number correction value 1 according to the engine speed and the target EGR rate; third, determining a second sampling number correction value 2 according to the target EGR rate and the target EGR rate change rate; and finally, multiplying the sampling number basic value by the first sampling number correction value 1, then multiplying the result by the second sampling number correction value 2, rounding to an integer to obtain the final N value.

[0010] In the technical solution, the specific process of the mixed valve actual opening initial value determining step is as follows: determining the mixed valve target opening maximum value pct DsrdMax and the mixed valve target opening minimum value pct DsrdMin according to the mixed valve target openings in the N arrays of the last step, respectively, pct ActMaxRaw = pct DsrdMax + Δ, and pct ActMinRaw = pct DsrdMin - Δ, wherein Δ is the mixed valve opening accuracy allowable deviation; and the specific process of the mixed valve actual opening final value determining step is as follows: mixed valve opening increase: when the mixed valve target opening pct Dsrd in the current sampling period is not less than the mixed valve target opening pct Dsrd (z) in the last sampling period, that is, pct Dsrd ≥ pct Dsrd (z), it indicates that the mixed valve opening is increasing, and the normal response performance of the mixed valve will be poor, and therefore:

[0011] pct ActMaxLim = pct ActMaxRaw + Δpctrate × Δt,

[0012] pct ActMinLim = pct ActMinRaw - Δpctrate × Δt;

[0013] mixing valve opening reduction: mixing valve target opening pct at current sampling period Dsrd less than mixing valve target opening pct at last sampling period Dsrd (z), i.e. pct Dsrd < pct Dsrd (z), indicating that the mixing valve opening is reducing, the normal response performance of the mixing valve will be better, thus there is:

[0014] pct ActMaxLim = pct ActMaxRaw - Δpctrate × Δt,

[0015] pct ActMinLim = pct ActMinRaw + Δpctrate × Δt,

[0016] wherein Δt is the sampling period; Δpctrate is the sampling period allowable change rate, determined jointly by engine speed n, actual fresh air intake density rho, actual fresh air intake density change rate drho, battery voltage V Battery Basic change rate calculation and judgment: at different engine speeds and actual fresh air intake densities, if the actual fresh air intake density change rate drho is smaller or even negative, the mixing valve action is more difficult, at this time Δpctrate is larger; the mixing valve motor control relies on battery power supply, when the battery voltage is lower, at this time Δpctrate is also larger, thus there is: when the mixing valve target opening is not full opening:

[0017] Δpctrate = Δpctrate Base × f(n, rho) × f(rho, drho) × f(V Battery ), when the mixing valve target opening is full opening:

[0018] Δpctrate = Δpctrate Base × f(n, rho) × f(rho, drho) × f(V Battery ) × k, when the mixing valve target opening is full opening, in order to avoid engine shaking caused by sudden closing of the mixing valve leading to sharp change of air volume, the actual opening allowable response of the mixing valve is relatively slow at full opening, wherein Δpctrate BaseThis is the basic rate of change of the sampling period obtained by benchmarking a faulty mixing valve and a normal mixing valve when the mixing valve is not fully open. This basic rate of change of the sampling period can accurately identify whether the mixing valve has a response performance fault. f(n,rho) is the first correction factor determined by engine speed and actual fresh air intake density, and f(rho,drho) is the second correction factor determined by actual fresh air intake density rho and the actual fresh air intake density change rate drho. f(V Battery (Based on battery voltage V) Battery The third correction factor is determined as follows: the larger the actual fresh air intake density rho is and the smaller the actual fresh air intake density change rate drho is, the more difficult it is for the mixing valve to operate, so the second correction factor is larger; the larger the battery voltage is, the larger the motor operating current is, and the better the response capability is, so the third correction factor is smaller.

[0019] In the above technical solution, the specific process of the steady-state operating condition mixing valve response performance detection step is as follows: steady-state operating condition condition satisfaction judgment: determine whether the steady-state operating condition meets the conditions. If all steady-state operating condition conditions are met, then perform fault detection; steady-state operating condition mixing valve fault detection: perform mixing valve response performance detection on the basis of meeting the steady-state operating condition conditions, and respectively accumulate the first opening time t1 from the target EGR rate of 0 to the start of the mixing valve opening change and the second opening time t2 from the start of the mixing valve opening change to the fully open state. Compare t1 and t2 with their respective limits to determine whether the mixing valve is in a steady-state operating condition response performance fault.

[0020] In the above technical solution, the specific conditions for the steady-state operating condition to meet the condition judgment step are as follows: 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 the engine speed fluctuation entering the mixing valve response performance detection is small; Actual fresh air intake density detection: the actual fresh air intake density is within a certain range, and the actual fresh air intake density fluctuation entering the mixing valve response performance detection is small; Target EGR rate detection: the target EGR rate is greater than a preset value, and the target EGR rate entering the mixing valve response performance detection is stable; Actual EGR rate detection: the actual EGR rate is within a certain range, and the actual EGR rate fluctuation entering the mixing valve response performance detection is small; Actual mixing valve opening detection: the actual opening of the mixing valve is not greater than a preset value, and the actual opening of the mixing valve entering the mixing valve response performance detection is stable; Target EGR rate and actual EGR rate... R-rate difference detection: The difference between the target EGR rate and the actual EGR rate is within a certain range; Engine coolant temperature detection: The engine coolant temperature is within a certain range, and the engine coolant temperature fluctuation during the mixing valve response performance test is small; EGR valve fault detection: No EGR valve fault occurs; Misfire fault and knock detection: No misfire fault or knock occurs; First preset time T0 detection: All 9 conditions above are met for more than the first preset time T0; Second preset time T1 detection: This mixing valve response performance test method has not been executed for more than the second preset time T1; After the above conditions are met, steady-state mixing valve fault detection is performed; The specific process of the steady-state mixing valve fault detection steps is as follows: Cumulative time T2: The sum of engine speed, the sum of actual fresh air intake density, and the sum of target EGR rate within the cumulative time T2; Calculate the average value of each parameter within T2: Calculate the average engine speed n within T2. Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvgTarget EGR rate setting: Set the target EGR rate to 0, i.e., force the EGR system to shut down; Opening time accumulation: Accumulate the first opening time t1 from when the target EGR rate is 0 until the mixing valve opening begins to change, and accumulate the second opening time t2 from when the mixing valve opening begins to change to the fully open state; Comparison of opening time with its limits: Compare t1 with the limits t1_limHi and t1_limLo under the same operating conditions, and simultaneously compare t2 with the limits t2_limHi and t2_limLo under the same operating conditions. If the following conditions are met simultaneously: 1) t1 > t1_limHi; 2) t2 > t2_limHi If the above conditions are not met, then the following conditions are judged again. If the following conditions are met simultaneously: 1) t1 < t1_limLo; 2) t2 < t2_limLo, then the mixing valve response performance is faulty; otherwise, no response performance fault occurs. The time limit values ​​t1_limHi, t1_limLo and t2_limHi, t2_limLo are obtained by testing with two types of mixing valves with deteriorated response performance, namely, those with too fast response and those with too slow response, under fixed engine speed, actual fresh air intake density, and target EGR rate, and by taking multiple samples to read the average value.

[0021] The above technical solution also includes fault judgment and self-learning update steps, which are briefly described as follows: When no mixing valve response performance fault is detected, t1 and t2 under the same operating condition are arrayed according to the cumulative time order. If the order number is greater than the preset value, and both arrays show no decreasing or increasing trend, when both arrays show no decreasing trend, the last number of the array divided by the first number is greater than the preset value, or when both arrays show no increasing trend, the last number of the array divided by the first number is less than the preset value. Then, the fault time of the mixing valve response performance detection under any operating condition is updated, and the t1 and t2 arrays under the same operating condition that meet the steady-state operating condition are cleared. They are then combined again after the steady-state condition is met again.

[0022] In the above technical solution, the detailed process of the fault judgment and self-learning update step is as follows: Trend of opening time array change: If no mixing valve response performance fault is detected, the first opening time t1 and the second opening time t2 under the same operating condition are arranged in the order of cumulative time to form time arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M]. If M is greater than a preset value, and any two of the following conditions are met: the arrays [t1_1,t1_2,…t1_M] and [t1_2_M] are... If the arrays [t1_1, t1_2, ..., t2_M] all show a trend of not decreasing; t1_M divided by t1_1 is greater than the preset value; t2_M divided by t2_1 is greater than the preset value; or, if the arrays [t1_1, t1_2, ..., t1_M] and [t2_1, t2_2, ..., t2_M] both show a trend of not increasing; t1_M divided by t1_1 is less than the preset value; t2_M divided by t2_1 is less than the preset value; if any of the above conditions are met, then the following action is performed: Update the fault time under any operating condition: update the fault time T of the mixing valve response performance detection under any operating condition. ErrLim To update, follow these steps:

[0023]

[0024] T ErrLimOld This is the fault time after the last update; Steady-state operating condition opening time array clearing: Clear the corresponding t1 and t2 arrays under the same operating condition that meet the steady-state operating condition, and reassemble them after they are met again.

[0025] The present invention also provides an engine mixing valve response performance testing device, which has a computer program capable of executing an engine mixing valve response performance testing method.

[0026] The engine mixing valve response performance detection method and device of the present invention have the following beneficial effects: the response performance of the mixing valve is determined based on the actual opening degree and response time of the mixing valve, which enables the mixing valve performance to be judged as early as possible, and effectively updates the mixing valve failure time to improve the detection rate, effectively avoiding engine vibration and other problems caused by mixing valve response failure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the low-voltage EGR system architecture of the present invention;

[0028] Figure 2 This is an overall flowchart of the method for detecting the response performance of a hybrid valve according to the present invention;

[0029] Figure 3 This is a schematic diagram of the process for testing the response performance of a hybrid valve under any operating condition in the hybrid valve response performance testing method of the present invention;

[0030] Figure 4 This is a flowchart of the method for obtaining the number of samplings N in the target opening degree sampling step of the hybrid valve in the hybrid valve response performance testing method under any working condition of the present invention.

[0031] Figure 5 This is a flowchart of the steps for determining the final value of the actual opening degree of the mixing valve in the mixing valve response performance testing method under any working condition in the present invention.

[0032] Figure 6 This is a schematic diagram of the steady-state operating condition hybrid valve response performance testing process in the hybrid valve response performance testing method of the present invention;

[0033] Figure 7 This is a flowchart illustrating the steady-state condition satisfaction judgment step in the steady-state operating condition of the hybrid valve response performance detection method of the present invention.

[0034] Figure 8 This is a flowchart illustrating the steady-state operating condition hybrid valve fault detection steps in the hybrid valve response performance testing method of the present invention.

[0035] Figure 9 This is a flowchart illustrating the fault diagnosis and self-learning update steps in the hybrid valve response performance detection method of the present invention.

[0036] Figure 10 This is a schematic diagram of the engine mixing valve response performance testing device of the present invention. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] 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, making the actual opening degree of the mixing valve follow the target opening degree. The oxygen sensor, installed between the compressor and the throttle valve, close to 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 has a throttling function, controlling the flow rate of exhaust gas entering the cylinder. The EGR temperature sensor is used to detect the temperature of the exhaust gas entering the EGR valve. The EGR differential pressure sensor is used to detect the pressure difference of the exhaust gas on both sides of the EGR valve.

[0040] The mixing valve is in its default state of being fully open, meaning it has its maximum opening. When there is a need to reduce the EGR valve outlet pressure, this is achieved by controlling the mixing valve opening to decrease. The specific method for calculating the target opening of the mixing valve can be found in patent CN202110184826.8, "Method for Determining the Target Opening of the Mixing Valve in an EGR System." This patent determines the target opening of the mixing valve; if the actual opening cannot respond quickly and accurately, and cannot follow the target opening, it indicates a malfunction in the mixing valve's response performance. In response to this malfunction, a functional degradation process is implemented to protect the engine.

[0041] See Figure 2 The present invention provides a method for detecting the response performance of an engine mixing valve, comprising detection of the mixing valve response performance under arbitrary operating conditions and / or steady-state operating conditions, and fault diagnosis and self-learning update steps, wherein...

[0042] Response performance testing of mixing valve under arbitrary operating conditions: Determine the response performance testing conditions of the mixing valve, read and retain N target openings of the mixing valve in the most recent time, determine the initial and final values ​​of the actual opening of the mixing valve respectively, compare the actual opening of the mixing valve with the final value of the maximum or minimum value of the actual opening of the mixing valve, and judge the response performance of the mixing valve.

[0043] Steady-state operating condition mixing valve response performance test: Determine if the steady-state operating condition is met. On the basis of meeting the steady-state operating condition, perform the mixing valve response performance test and accumulate the first opening time t1 from the target EGR rate of 0 to the start of the mixing valve opening change and the second opening time t2 from the start of the mixing valve opening change to the fully open state. Compare t1 and t2 with their respective limits to determine whether the mixing valve is in a steady-state operating condition response performance failure.

[0044] Fault diagnosis and self-learning update: When no fault in the response performance of the mixing valve is detected, t1 and t2 under the same operating condition are arrayed according to the cumulative time order. If the order number is greater than the preset value and both arrays show no decreasing or increasing trend, when both arrays show no decreasing trend, the last number divided by the first number of the array is greater than the preset value, or when both arrays show no increasing trend, the last number divided by the first number of the array is less than the preset value. Then, the fault time of the mixing valve response performance detection under any operating condition is updated, and the t1 and t2 arrays under the same operating condition that meet the steady-state operating condition are cleared. They are combined again after the steady-state condition is met again.

[0045] See Figure 3 The specific process of the arbitrary operating condition mixing valve response performance testing step is as follows:

[0046] The first step is to determine the conditions for testing the response performance of the mixing valve under arbitrary operating conditions: The following conditions must all be met before testing the response performance of the mixing valve can be performed; otherwise, incorrect judgments will occur if the conditions are not met. The conditions for testing the response performance of the mixing valve are:

[0047] 1) Voltage fault detection: No battery voltage fault was found;

[0048] 2) Sensor fault detection: No position sensor detected in the mixing valve;

[0049] 3) Motor circuit fault detection: No motor circuit faults (such as open circuit, short circuit, etc.) are found in the mixing valve;

[0050] 4) First operating state detection: The engine is in the first operating state.

[0051] The second step is to sample the target opening of the mixing valve: After the above conditions are met simultaneously, the target opening of the mixing valve is read N times consecutively (in this embodiment, the sampling period is 10ms, that is, the target opening of the mixing valve is read once every 10ms. The method for obtaining the target opening of the mixing valve can be found in patent CN202110184826.8 "Method for Determining the Target Opening of the Mixing Valve in an EGR System"), and these samples are arranged into an array [pct Dsrd1 ,…,pct DsrdNThe array is updated after each sampling period, retaining only the N target openings of the mixing valves from the most recent time. The method for obtaining N depends on engine speed, actual fresh air intake density (the real-time fresh air density entering the cylinder), target EGR rate, and the rate of change of the target EGR rate. Engine speed, actual fresh air intake density, and target EGR rate represent basic information about engine operating conditions. Under different engine speeds, actual fresh air intake densities, and target EGR rates, a larger rate of change in the target EGR rate may indicate a larger change in the target opening of the mixing valve. A larger change in the target opening of the mixing valve requires collecting more sampled target openings for response performance testing to more accurately and promptly determine whether the mixing valve has experienced a response performance failure. Based on this, a method for obtaining the number of samples N was designed.

[0052] See Figure 4 First, the basic value for the number of sampling times is determined by the engine speed and the actual fresh air intake density, as shown in Table 1 below:

[0053] Table 1

[0054]

[0055] Secondly, the correction value 1 for the first sampling number is determined by the engine speed and the target EGR rate, as shown in Table 2 below:

[0056] Table 2

[0057]

[0058]

[0059] Next, the second sampling correction value 2 is determined by the target EGR rate and the rate of change of the target EGR rate. The larger the rate of change, the more samplings are needed to accurately determine whether a performance failure has occurred. See Table 3 below for details:

[0060] Table 3

[0061]

[0062] The base value of the number of samples is first multiplied by the first sample count correction value of 1, then multiplied by the second sample count correction value of 2, and then rounded to obtain the final integer value of N. The above calibration approach for the N value is to minimize the N value as much as possible while ensuring the accuracy of performance detection in identifying whether a performance failure has occurred, so as to report whether a performance failure has occurred as quickly as possible.

[0063] The third step is to determine the initial value of the actual opening of the mixing valve: determine the initial value of the maximum actual opening of the mixing valve, pct. ActMaxRaw The minimum actual opening value and initial value of the mixing valve (pct) ActMinRawThe method for determining this is as follows: Based on the target opening of the mixing valve in the N arrays from the previous step, determine the maximum target opening value pct of the mixing valve. DsrdMax Minimum target opening value of mixing valve (pct) DsrdMin pct ActMaxRaw =pct DsrdMax +Δ, pct ActMinRaw =pct DsrdMin -Δ, where Δ is the allowable deviation of the opening accuracy of the mixing valve (i.e., the maximum allowable deviation between the target opening of the mixing valve and the actual opening of the mixing valve is 1% in this embodiment, and to avoid incorrect detection of response performance, Δ is taken as 3% in this embodiment).

[0064] See Figure 5 The fourth step is to determine the final actual opening value of the mixing valve: determine the final maximum actual opening value of the mixing valve, pct. ActMaxLim The minimum and final values ​​of the actual opening of the mixing valve (pct) ActMinLim The method for determining it is as follows:

[0065] 1) Increased mixing valve opening: The target opening of the mixing valve (pct) in the current sampling period. Dsrd Not less than the target opening of the mixing valve in the previous sampling period (pct) Dsrd (z) is when pct Dsrd ≥pct Dsrd (z) indicates that the mixing valve opening is increasing. Since the airflow direction is opposite to the mixing valve's operating direction, the normal response performance of the mixing valve will deteriorate. Therefore:

[0066] pct ActMaxLim =pct ActMaxRaw +Δpctrate×Δt

[0067] pct ActMinLim =pct ActMinRaw -Δpctrate×Δt

[0068] 2) Mixing valve opening decreases: the target opening of the mixing valve (pct) in the current sampling period. Dsrd The target opening of the mixing valve is less than the previous sampling period's target opening (pct). Dsrd (z) is when pct Dsrd <pct Dsrd (z) indicates that the mixing valve opening is decreasing. Since the airflow direction is the same as the mixing valve's operating direction, the normal response performance of the mixing valve will improve. Therefore:

[0069] pct ActMaxLim =pct ActMaxRaw -Δpctrate×Δt

[0070] pctActMinLim =pct ActMinRaw +Δpctrate×Δt

[0071] Where Δt is the sampling period, which is 10ms in this embodiment; 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, the actual fresh air intake density change rate drho, and the battery voltage V. Battery Let's decide together.

[0072] 3) Calculation and Judgment of the Basic Change Rate of the Sampling Period: Under different engine speeds and actual fresh air intake densities, if the change rate of the actual fresh air intake density (drho) is smaller or even negative, the mixing valve will have more difficulty operating, and Δpctrate will be larger. Since the mixing valve motor control relies on battery power, the lower the battery voltage, the larger Δpctrate will be. Therefore:

[0073] When the target opening of the mixing valve is not fully open:

[0074] Δpctrate=Δpctrate Base ×f(n,rho)×f(rho,drho)×f(V Battery ),

[0075] When the target opening of the mixing valve is fully open:

[0076] Δpctrate=Δpctrate Base ×f(n,rho)×f(rho,drho)×f(V Battery )×k

[0077] When the target opening of the mixing valve is fully open, in order to avoid sudden changes in air volume and engine vibration caused by the sudden closure of the mixing valve, the actual opening of the mixing valve is allowed to respond relatively slowly when fully open. In this embodiment, k is taken as 1.08.

[0078] Where Δpctrate Base With the mixing valve not fully open, the engine speed is 1000 rpm, the actual fresh air intake density rho is 300 mg / L, the actual fresh air intake density change rate drho is 0 mg / L, and the battery voltage V... Battery The sampling period is 12V. The basic rate of change of the sampling period is obtained by comparing the response performance of a faulty mixing valve with that of a normal mixing valve. This basic rate of change of the sampling period can accurately identify whether the mixing valve has a response performance failure. In this embodiment, Δpctrate BaseTake 30% / s. f(n,rho) is the first correction factor determined by engine speed and actual fresh air intake density (see Table 4 below for details), and f(rho,drho) is the second correction factor determined by actual fresh air intake density rho and actual fresh air intake density change rate drho; f(V Battery (Based on battery voltage V) Battery The determined third correction factor is detailed in Tables 4-6 below:

[0079] Table 4

[0080]

[0081] The higher the actual fresh air intake density rho and the lower the actual fresh air intake density change rate drho, the more difficult it is for the mixing valve to operate. Therefore, the second correction factor should have a larger value, as shown in Table 5 below:

[0082] Table 5

[0083]

[0084] A higher battery voltage results in a higher motor operating current and better response capability, thus a smaller third correction factor. See Table 6 below for details.

[0085] Table 6

[0086]

[0087] Step 5, Performance evaluation of the mixing valve under arbitrary operating conditions: Perform a performance evaluation of the mixing valve's response. If the actual opening degree (pct) of the mixing valve is found to be abnormal... Act <pct ActMinLim Or the actual opening degree (pct) of the mixing valve Act >pct ActMaxLim This indicates that the mixing valve experienced a response performance sampling failure once, with the failure occurring within a 10ms sampling period. If this occurs within the current driving cycle, T... Total The accumulated fault time within the time frame (150ms in this example) shall not be less than the fault time T. ErrLim This indicates a failure in the mixing valve's response performance. Generally, a sampling failure does not necessarily mean the final failure has occurred; it merely represents one instance of a failure. A relatively long period of failure within a given timeframe is required for a final failure to be considered to have occurred. In other words, 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 .

[0088] It is important to note the downtime T. ErrLimIt will continuously update and learn, and will save power-off data, with an initial value of 100ms.

[0089] The scenario described above allows for testing the response performance of the mixing valve under any operating condition. In contrast, another method for testing the response performance of the mixing valve judges its behavior based on changes in the EGR rate under steady-state conditions, and updates the failure time T of the testing method under any operating condition based on these changes and parameters. ErrLim .

[0090] Compared to testing under arbitrary operating conditions, the second type of testing is performed under steady-state conditions. Arbitrary operating conditions do not require steady-state conditions and can be performed at any time. However, steady-state operating conditions require certain conditions to be met before diagnosis can be performed.

[0091] See Figure 6 The specific process of the steady-state operating condition mixing valve response performance testing steps is as follows:

[0092] See Figure 7 Steady-state operating condition condition judgment: First, determine whether the operating condition is steady-state. Fault detection can only be performed when all of the following conditions are met:

[0093] 1. Second operating state detection: The engine is in the second operating state;

[0094] 2. Engine speed fluctuation detection: The engine speed is within a certain range, which in this embodiment is between 600 rpm and 5900 rpm, and the engine speed fluctuation for entering the mixing valve response performance detection is small, which in this embodiment is ±15 rpm;

[0095] 3. Actual fresh air intake density detection: The actual fresh air intake density is within a certain range. In this embodiment, it is taken to be between 300 mgpl and 3000 mgpl. The actual fresh air intake density fluctuates little when entering the mixing valve response performance test. In this embodiment, it is taken to be ±12 mgpl.

[0096] 4. Target EGR rate detection: The target EGR rate is greater than the preset value (in this embodiment, the 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 opening of the mixing valve, making it impossible to accurately detect the response performance of the mixing valve), and the target EGR rate entering the mixing valve response performance detection is stable, that is, the fluctuation range of the target EGR rate in this embodiment does not exceed ±1%.

[0097] 5. Actual EGR rate detection: The actual EGR rate is within a certain range, and the fluctuation of the actual EGR rate entering the mixing valve response performance detection is small. In this embodiment, it is taken as ±1%.

[0098] 6. Actual opening degree detection of the mixing valve: The actual opening degree of the mixing valve is not greater than the preset value (in this embodiment, the preset value is 65%, and the opening degree of the mixing valve is not fully open. It is used to detect the response time of the mixing valve action when the mixing valve response performance is tested later, so as to determine whether the response performance of the mixing valve has failed). The actual opening degree of the mixing valve entering the mixing valve response performance test is stable, that is, the fluctuation range of the actual opening degree of the mixing valve in this embodiment does not exceed ±1%.

[0099] 7. Detection of the difference between the target EGR rate and the actual EGR rate: The difference between the target EGR rate and the actual EGR rate is within a certain range, which is ±1% in this embodiment;

[0100] 8. 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.

[0101] 9. EGR valve fault detection: No EGR valve-related faults were found;

[0102] 10. Fire fault and knock detection: No fire fault or knock was detected.

[0103] If any of the above conditions are not met, the mixing valve response performance test will not be performed. If all the above conditions are met, the following condition will be evaluated again:

[0104] 11. First preset time T0 detection: If all 9 conditions above are met for more than the first preset time T0, this embodiment takes 3 seconds.

[0105] 12. Second preset time T1 detection: This method of detecting the response performance of the mixing valve has not been executed for more than the preset time T1 (60h in this embodiment. Since EGR will be prohibited during the execution of the mixing valve response performance detection, which will cause emissions and fuel consumption to deteriorate, the execution should not be too frequent).

[0106] Once the above two conditions are met, a steady-state mixing valve fault detection will be performed.

[0107] See Figure 8 The specific process of the steady-state mixing valve fault detection step is as follows:

[0108] 1. Accumulated Time T2: The total engine speed, the total actual fresh air intake density, and the total target EGR rate within a certain time period T2 (T2 is 3s in this embodiment). After time T2 is satisfied, the next stage begins.

[0109] 2. Calculate the average value of each parameter within time T2: Calculate the average engine speed n within time T2. Avg The average actual fresh air intake density rho AvgTarget EGR rate average r DsrdEGRAvg .

[0110] 3. Target EGR Rate Setting: Set the target EGR rate to 0, which forces the EGR system to shut down. From this step onwards, conditions 4, 5, and 6 in the steady-state condition judgment for the mixing valve response performance test will no longer apply. Other conditions will still be judged. If any condition is not met, the mixing valve response performance test will be terminated.

[0111] 4. Accumulation of opening time: Accumulate the time t1 from when the target EGR rate is 0 to when the opening of the mixing valve begins to change, and accumulate the time t2 from when the opening of the mixing valve begins to change to when it is fully open.

[0112] 5. Comparison of opening time with its limit: Compare t1 with the same operating conditions (average engine speed n) Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvg The limits t1_limHi and t1_limLo are compared under the same conditions (where all are the same), and t2 is compared with the limits t1_limHi and t1_limLo under the same operating conditions (where the average engine speed n is the same). Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvg Compare the limits t2_limHi and t2_limLo under the condition that they are all the same. If the following conditions are met simultaneously:

[0113] 1) t1 > t1_limHi;

[0114] 2) t2>t2_limHi;

[0115] This indicates a malfunction in the mixing valve's response performance. If the above conditions are not met, then the following conditions are checked again. If all of the following conditions are met:

[0116] 1) t1 < t1_limLo;

[0117] 2) t2 < t2_limLo;

[0118] This indicates a malfunction in the mixing valve's response performance; otherwise, no malfunction has occurred.

[0119] In this embodiment, the time limits t1_limHi, t1_limLo and t2_limHi, t2_limLo are obtained by testing with two types of mixed valves exhibiting deteriorated response performance (too fast response and too slow response) under fixed engine speed, actual fresh air intake density, and target EGR rate (response performance testing is the performance of the mixing valve response after the target EGR is abruptly reduced to 0). Multiple samplings (more than 5000 times in this embodiment) are performed to obtain the average value. In this embodiment, with an engine speed of 1000 rpm, an actual fresh air intake density of 300 mgpl, and a target EGR rate of 0.1, t1_limHi is set to 0.6 s, t2_limHi to 1.2 s, t1_limLo to 0.1 s, and t2_limLo to 0.2 s.

[0120] See Figure 9 The detailed process of the fault diagnosis and self-learning update steps is as follows:

[0121] 1. Trend of opening time array change: If no mixing valve response performance fault is detected (the following actions will no longer be performed after a mixing valve response performance fault is detected), the engine speed average n under the same operating conditions will be... Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvg If the first opening time t1 and the second time t2 are the same (meaning the working conditions are the same), they are arranged in the order of cumulative time to form time arrays [t1_1, t1_2, ..., t1_M] and [t2_1, t2_2, ..., t2_M]. If M is greater than a preset value, in this embodiment it is taken as 50, and any two of the following conditions are met:

[0122] 1) Both arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M] show a trend of not decreasing; t1_M divided by t1_1 is greater than the preset value, which is 1.2 in this embodiment; t2_M divided by t2_1 is greater than the preset value, which is 1.2 in this embodiment.

[0123] 2) Alternatively, both arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M] show a trend of not increasing; t1_M divided by t1_1 is less than a preset value, which is 0.9 in this embodiment; t2_M divided by t2_1 is less than a preset value, which is 0.9 in this embodiment;

[0124] If any of the above conditions are met, the following action will be performed:

[0125] 2. Arbitrary operating condition fault time update: Update the fault time T of the mixing valve response performance test under any operating condition. ErrLimTo update, follow these steps:

[0126]

[0127] T ErrLimOld This is the downtime since the last update;

[0128] 3. Clear the steady-state operating condition opening time array: Clear the same operating conditions that meet the steady-state operating condition (average engine speed n). Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvg If all conditions are the same (meaning the working conditions are the same), the t1 and t2 arrays corresponding to the working conditions are cleared, and then combined again after the conditions are met again.

[0129] It should be noted that if either the arbitrary operating condition mixing valve response performance testing method or the steady-state operating condition mixing valve response performance testing method detects a fault, it indicates that the mixing valve response performance has failed; otherwise, no fault has occurred. Once a fault is detected, testing will cease until the fault is cleared by the diagnostic instrument.

[0130] The above completes the description of the engine mixing valve response performance testing method.

[0131] See Figure 10 The engine mixing valve response performance testing device of the present invention includes an arbitrary operating condition mixing valve response performance testing module and / or a steady-state operating condition mixing valve response performance testing module, and a fault judgment and self-learning update module, wherein,

[0132] Arbitrary operating condition mixing valve response performance detection module: Determine the mixing valve response performance detection conditions, read and retain N target openings of the mixing valve in the most recent time, determine the initial and final values ​​of the actual opening of the mixing valve respectively, compare the actual opening of the mixing valve with the final value of the maximum or minimum value of the actual opening of the mixing valve, and judge the response performance of the mixing valve.

[0133] Steady-state operating condition mixing valve response performance detection module: Determines whether the steady-state operating condition is met. Based on the condition being met, the module performs mixing valve response performance detection and accumulates the first opening time t1 from the target EGR rate of 0 to the start of the mixing valve opening change and the second opening time t2 from the start of the mixing valve opening change to the fully open state. The module compares t1 and t2 with their respective limits to determine whether the mixing valve is in a steady-state operating condition response performance failure.

[0134] Fault Judgment and Self-Learning Update Module: When no fault in the response performance of the mixing valve is detected, t1 and t2 under the same operating condition are arrayed according to the cumulative time order. If the order number is greater than the preset value and both arrays show no decreasing or increasing trend, when both arrays show no decreasing trend, the last number divided by the first number of the array is greater than the preset value, or when both arrays show no increasing trend, the last number divided by the first number of the array is less than the preset value. Then, the fault time of the mixing valve response performance detection under any operating condition is updated, and the t1 and t2 arrays under the same operating condition that meet the steady-state operating condition are cleared. They are then combined again after the steady-state condition is met again.

[0135] The key technical points and technical principles of this invention are as follows:

[0136] 1. Method for judging the actual opening response of a mixing valve;

[0137] 2. Method for judging the response time of mixing valve under steady-state conditions.

[0138] 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.

[0139] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A method for detecting the response performance of an engine mixing valve, characterized in that: This includes performance testing of mixed valve response under arbitrary operating conditions and / or steady-state operating conditions, wherein... Response performance testing of mixing valve under arbitrary operating conditions: Determine the response performance testing conditions of the mixing valve, read and retain N target openings of the mixing valve in the most recent time, determine the initial and final values ​​of the actual opening of the mixing valve respectively, compare the actual opening of the mixing valve with the final value of the maximum or minimum value of the actual opening of the mixing valve, and judge the response performance of the mixing valve. Steady-state operating condition mixing valve response performance test: Determine if the steady-state operating condition is met. On the basis of meeting the steady-state operating condition, perform the mixing valve response performance test and accumulate the first opening time t1 from the target EGR rate of 0 to the start of the mixing valve opening change and the second opening time t2 from the start of the mixing valve opening change to the fully open state. Compare t1 and t2 with their respective limits to determine whether the mixing valve is in a steady-state operating condition response performance failure. If a fault occurs in either the arbitrary operating condition mixing valve response performance test or the steady-state operating condition mixing valve response performance test, it indicates that the mixing valve response performance has failed; otherwise, no fault has occurred.

2. The method for detecting the response performance of an engine mixing valve according to claim 1, characterized in that: The specific process for testing the response performance of the mixing valve under arbitrary operating conditions is as follows: Determining the conditions for testing the response performance of a mixing valve under any operating condition: Determine the conditions for testing the response performance of the mixing valve, and only conduct the testing after all testing conditions are met; Mixed valve target opening sampling: Read the mixed valve target opening from N consecutive samples and arrange them into an array [pct Dsrd1 ,…,pct DsrdN The array is updated after each sampling period, retaining only the N target openings of the mixing valves in the most recent time. Determine the initial value of the actual opening of the mixing valve: Determine the initial value of the maximum actual opening of the mixing valve, pct. ActMaxRaw The minimum actual opening value and initial value of the mixing valve (pct) ActMinRaw ; Determine the final actual opening value of the mixing valve: Determine the final maximum actual opening value (pct) of the mixing valve. ActMaxLim The minimum and final values ​​of the actual opening of the mixing valve (pct) ActMinLim ; Performance evaluation of the mixing valve under any operating condition: If the actual opening of the mixing valve is less than the final value of the minimum actual opening or greater than the final value of the maximum actual opening, it indicates that the mixing valve has experienced a performance sampling fault. The time of the fault occurrence is taken as the sampling period. If within the current driving cycle, T... Total The cumulative value of fault occurrence time within a given time period shall not be less than the fault time T. ErrLim This indicates a malfunction in the mixing valve's response performance.

3. The method for detecting the response performance of an engine mixing valve according to claim 2, characterized in that: The specific conditions for determining the response performance of the mixing valve are as follows: Voltage fault detection: No battery voltage fault; Sensor fault detection: No position sensor detected in the mixing valve; Motor circuit fault detection: No motor circuit fault in the mixing valve; First operating status detection: The engine is in the first operating state; The specific process of sampling the target opening degree of the mixing valve is as follows: Read values ​​and assemble them into an array: Read the target opening of the mixing valve from N consecutive samples and assemble them into an array [pct Dsrd1 ,…,pct DsrdN ]; Element update: After each sampling period, update the elements in the array, retaining only the N target openings of the mixing valves in the most recent time.

4. The method for detecting the response performance of an engine mixing valve according to claim 3, characterized in that: The specific process for obtaining the number of samplings N in the target opening degree sampling step of the mixing valve is as follows: First, the basic value for the number of sampling times is determined by the engine speed and the actual fresh air intake density. Secondly, the correction value for the first sampling number is determined by the engine speed and the target EGR rate; Next, the second sampling number correction value 2 is determined by the target EGR rate and the rate of change of the target EGR rate; Finally, the basic value of the number of samples is multiplied by the first sample number correction value 1, then by the second sample number correction value 2, and then rounded to obtain the final integer value of N.

5. The method for detecting the response performance of an engine mixing valve according to claim 4, characterized in that: The specific process for determining the initial value of the actual opening degree of the mixing valve is as follows: Based on the target opening of the mixing valve in the N arrays from the previous step, determine the maximum target opening value pct of the mixing valve. DsrdMax Minimum target opening value of mixing valve (pct) DsrdMin ,pct ActMaxRaw =pct DsrdMax +Δ, pct ActMinRaw =pct DsrdMin -Δ, where Δ is the allowable deviation of the opening accuracy of the mixing valve; The specific process for determining the final value of the actual opening degree of the mixing valve is as follows: Increase the opening degree of the mixing valve: the target opening degree of the mixing valve in the current sampling period (pct). Dsrd Not less than the target opening of the mixing valve in the previous sampling period (pct) Dsrd (z) is when pct Dsrd ≥pct Dsrd (z) indicates that as the opening of the mixing valve increases, the normal response performance of the mixing valve will deteriorate. Therefore: pct ActMaxLim =pct ActMaxRaw +Δpctrate×Δt, pct ActMinLim =pct ActMinRaw -Δpctrate×Δt; Mixing valve opening decrease: the target opening of the mixing valve (pct) in the current sampling period. Dsrd The target opening of the mixing valve is less than the previous sampling period's target opening (pct). Dsrd (z) is when pct Dsrd <pct Dsrd (z) indicates that the opening of the mixing valve is decreasing, which will improve the normal response performance of the mixing valve. Therefore: pct ActMaxLim =pct ActMaxRaw -Δpctrate×Δt, pct ActMinLim =pct ActMinRaw +Δpctrate×Δt, Where Δt is the sampling period; 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, the actual fresh air intake density change rate drho, and the battery voltage V. Battery 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 rate of change of the actual fresh air intake density (drho) is smaller or even negative, the mixing valve will have more difficulty operating, and Δpctrate will be larger. Since the mixing valve motor control relies on battery power, the lower the battery voltage, the larger Δpctrate will be. Therefore: When the target opening of the mixing valve is not fully open: Δpctrate=Δpctrate Base ×f(n,rho)×f(rho,drho)×f(V Battery ), When the target opening of the mixing valve is fully open: Δpctrate=Δpctrate Base ×f(n,rho)×f(rho,drho)×f(V Battery )×k When the target opening of the mixing valve is fully open, to avoid sudden changes in air volume and engine vibration caused by abrupt closure of the mixing valve, the actual opening of the mixing valve is allowed to respond relatively slowly when fully open. Where, Δpctrate Base This is the basic rate of change of the sampling period obtained by benchmarking a faulty mixing valve and a normal mixing valve when the mixing valve is not fully open. This basic rate of change of the sampling period can accurately identify whether the mixing valve has a response performance fault. f(n,rho) is the first correction factor determined by engine speed and actual fresh air intake density, and f(rho,drho) is the second correction factor determined by actual fresh air intake density rho and the actual fresh air intake density change rate drho. f(V Battery (Based on battery voltage V) Battery A determined third correction factor; The larger the actual fresh air intake density rho is, and the smaller the actual fresh air intake density change rate drho is, the more difficult it is for the mixing valve to operate, and therefore the larger the second correction factor is. A higher battery voltage and a higher motor operating current result in better response capability, thus a smaller third correction factor.

6. The method for detecting the response performance of an engine mixing valve according to claim 5, characterized in that: The specific process for testing the steady-state operating condition mixing valve response performance is as follows: Steady-state operating condition satisfaction judgment: Determine if the steady-state operating condition meets the conditions. If all steady-state operating condition conditions are met, then perform fault detection. Steady-state operating condition mixing valve fault detection: On the basis of meeting the steady-state operating conditions, the response performance of the mixing valve is tested, and the first opening time t1 from the target EGR rate of 0 to the start of the change in the opening of the mixing valve and the second opening time t2 from the start of the change in the opening of the mixing valve to the fully open state are accumulated respectively. t1 and t2 are compared with their respective limits to determine whether the mixing valve is in a steady-state operating condition response performance fault.

7. The method for detecting the response performance of an engine mixing valve according to claim 1, characterized in that: The specific conditions for the steady-state operating condition to satisfy the condition judgment step are as follows: 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 the engine speed fluctuation is small when entering the mixing valve response performance detection. Actual fresh air intake density test: The actual fresh air intake density is within a certain range, and the fluctuation of the actual fresh air intake density in the mixing valve response performance test is small; Target EGR rate detection: The target EGR rate is greater than the preset value, and the target EGR rate for entering the mixing valve response performance detection is stable; Actual EGR rate detection: The actual EGR rate is within a certain range, and the fluctuation of the actual EGR rate entering the mixing valve response performance detection is small; Actual opening degree detection of mixing valve: The actual opening degree of the mixing valve is not greater than the preset value, and the actual opening degree of the mixing valve entering the mixing valve response performance detection is stable; Target EGR rate vs. actual EGR rate difference detection: The difference between the target EGR rate and the actual EGR rate is within a certain range; 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 fault detection: No EGR valve fault was detected; Fire fault and detonation detection: No fire fault or detonation was detected; First preset time T0 detection: All 9 conditions above are met for more than the first preset time T0; Second preset time T1 detection: This method for detecting the response performance of the mixing valve has not been executed for more than the second preset time T1; After the above conditions are met, perform steady-state mixing valve fault detection. The specific process for detecting faults in the mixing valve under steady-state operating conditions is as follows: Cumulative time T2: The total engine speed, the total actual fresh air intake density, and the total target EGR rate within the cumulative time T2; Calculate the average value of each parameter within time T2: Calculate the average engine speed n within time T2. Avg The average actual fresh air intake density rho Avg Target EGR rate average r DsrdEGRAvg ; Target EGR rate setting: Set the target EGR rate to 0, which forces the EGR system to shut down; Accumulated opening time: Accumulate the first opening time t1 from the target EGR rate of 0 to the start of the change in the opening of the mixing valve, and accumulate the second opening time t2 from the start of the change in the opening of the mixing valve to the fully open state; Comparison of opening time with its limits: Compare t1 with the limits t1_limHi and t1_limLo under the same operating conditions, and simultaneously compare t2 with the limits t2_limHi and t2_limLo under the same operating conditions. If the following conditions are met simultaneously: 1) t1 > t1_limHi; 2) t2>t2_limHi; This indicates a malfunction in the mixing valve's response performance. If the above conditions are not met, then the following conditions are checked again. If all of the following conditions are met: 1) t1 < t1_limLo; 2) t2 < t2_limLo; This indicates a malfunction in the mixing valve's response performance; otherwise, no malfunction has occurred. The time limits t1_limHi, t1_limLo and t2_limHi, t2_limLo are obtained by testing a mixed valve with two types of degraded response performance, namely, one with too fast response and one with too slow response, under fixed engine speed, actual fresh air intake density and target EGR rate, and by taking multiple samples to read the average value.

8. The method for detecting the response performance of an engine mixing valve according to claim 7, characterized in that: It also includes fault diagnosis and self-learning update steps, briefly described below: When no mixing valve response performance fault is detected, t1 and t2 under the same operating condition are arrayed according to the cumulative time order. If the order number is greater than the preset value and both arrays show no decreasing or increasing trend, when both arrays show no decreasing trend, the last number of the array divided by the first number is greater than the preset value, or when both arrays show no increasing trend, the last number of the array divided by the first number is less than the preset value. Then, the fault time of the mixing valve response performance detection under any operating condition is updated, and the t1 and t2 arrays under the same operating condition that meet the steady-state operating condition are cleared. They are then combined again after the steady-state condition is met again.

9. The method for detecting the response performance of an engine mixing valve according to claim 8, characterized in that: The detailed process of the fault diagnosis and self-learning update steps is as follows: Trend of opening time array change: If, without detecting any mixing valve response performance failure, the first opening time t1 and the second opening time t2 under the same operating conditions are arranged in the order of cumulative time from first to last to form time arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M], if M is greater than a preset value and any two of the following conditions are met: The arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M] both show a trend of not decreasing; t1_M divided by t1_1 is greater than the preset value; t2_M divided by t2_1 is greater than the preset value; or, The arrays [t1_1,t1_2,…t1_M] and [t2_1,t2_2,…t2_M] both show a trend of not increasing; t1_M divided by t1_1 is less than the preset value; t2_M divided by t2_1 is less than the preset value; If any of the above conditions are met, the following action will be performed: Arbitrary operating condition failure time update: Update the failure time T of the mixing valve response performance test under arbitrary operating conditions. ErrLim To update, follow these steps: T ErrLimOld This is the downtime since the last update; Steady-state operating condition opening time array clearing: Clear the corresponding t1 and t2 arrays for the same operating condition that meet the steady-state operating condition, and recombine them after the steady-state operating condition is met again.

10. An engine mixing valve response performance testing device, comprising a computer program, characterized in that: The computer program is capable of executing the engine mixing valve response performance testing method as described in any one of claims 1 to 9.

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