Method for estimating actual EGR rate entering cylinder, electronic device, and vehicle

Abstract

The present invention relates to the technical field of vehicle engine control, and more specifically to a method, electronic device, and vehicle for estimating the actual EGR rate entering a cylinder. By limiting the rate of change of the actual EGR rate and subjecting the limited EGR rate to discrete first-order low-pass filtering, the present invention optimizes the actual EGR rate when the EGR control valve is closed and continuously updates the learning parameters of the actual EGR rate throughout the vehicle's lifecycle. This method effectively improves the accuracy of estimating the actual EGR rate, thereby significantly enhancing the EGR system's effectiveness in improving vehicle engine performance.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle engine control, and in particular to a method for estimating an actual EGR rate entering a cylinder, an electronic device, and a vehicle. Background Art

[0002] Exhaust Gas Recirculation (EGR) extracts exhaust gas from the exhaust and feeds it into the intake system. Research has shown that EGR systems offer advantages in improving emissions, reducing fuel consumption, and improving anti-knock capabilities. The actual EGR rate entering the cylinder is an important basis for the engine to estimate the fresh air flow rate and is also a key parameter for controlling throttle opening. The higher the EGR rate accuracy, the more accurate the fresh air estimation, and the more reasonable the throttle opening control, thereby meeting the engine's demand for fresh air volume and satisfying the vehicle's power and emissions requirements. At the same time, ignition timing is optimized based on the actual EGR rate, thereby improving power and economy. For this reason, the accuracy of the actual EGR rate estimation is extremely important. If the actual EGR rate accuracy is poor, it will not only result in poor engine combustion stability, but also affect power, economy, and emissions.

[0003] The calculation method of the EGR rate in the prior art mainly determines the basic target EGR rate based on the engine speed and load; obtains the corresponding correction rate according to the special working conditions; determines the initial target EGR rate based on the basic target EGR rate and each correction rate; determines whether EGR is activated based on the EGR activation state conditions; divides the EGR state according to the judgment result, and determines the final target EGR rate. The present invention calculates the initial target EGR rate from the throttle opening, manifold pressure difference and minimum ignition angle, can accurately calculate the target EGR rate, and introduces the EGR control activation conditions to perform a secondary correction on the final target EGR rate. However, the prior art is only applicable to the calculation of the target EGR rate, and does not consider the acquisition of the actual EGR rate, and cannot dynamically control the stability of the EGR rate. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a method for estimating the actual EGR rate entering the cylinder is provided, which can effectively improve the estimation accuracy of the actual EGR rate, thereby greatly enhancing the improvement effect of the EGR system on vehicle engine emissions, fuel consumption and anti-knock ability.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for estimating the actual EGR rate entering a cylinder includes the following control strategies:

[0007] S1, limiting the change rate of the initial value of the actual EGR rate entering the cylinder to obtain the EGR rate with limited change rate;

[0008] S2, based on the actual EGR rate filter coefficient, performing a discrete first-order low-pass filter process on the EGR rate with the limited change rate to obtain a filtered actual EGR rate, and using a self-learning update coefficient related to the real-time opening of the EGR control valve to self-learn and update the actual EGR rate filter coefficient;

[0009] S3, read the real-time opening of the EGR control valve. If the continuous time of the real-time opening being 0 exceeds a preset time value, the final actual EGR rate is set to 0. Otherwise, the filtered actual EGR rate is output as the final actual EGR rate.

[0010] Furthermore, the initial value of the actual EGR rate entering the cylinder is: the ratio of the exhaust gas flow entering the cylinder to the sum of the fresh air flow and the exhaust gas flow entering the cylinder.

[0011] Furthermore, the EGR rate r of the limit change rate EGRLim , calculated as follows:

[0012] r EGRLim =r EGRLim (z)+max{min{[r EGRRaw -r EGRLim (z)],r EGRGrandInc},r EGRGrandDec}

[0013] Where r EGRLim (z) is the EGR rate with limited change rate in the previous sampling period, r EGRGrandInc is the maximum increment of EGR rate in a single sampling period, r EGRGrandDec It is the maximum reduction of EGR rate in a single sampling cycle.

[0014] Furthermore, the actual EGR rate after filtering r EGRFilter , calculated as follows:

[0015] r EGRFilter (N) = K EGR ×[r EGRLim (N)-r EGRFilter (N-1)]+r EGRFilter (N-1)

[0016] Where r EGRLim (N) is the EGR rate with limited change rate in the Nth sampling period, r EGRFilter (N) is the actual EGR rate after filtering in the Nth sampling period, r EGRFilter (N-1) is the actual EGR rate after filtering in the N-1th sampling period, N≥2; k EGR is the actual EGR rate filter coefficient, and k EGR =k EGRFilterBase×(1+r EGRFilterAdapt ), k EGRFilterBase Actual EGR rate filter coefficient reference value, r EGRFilterAdapt It is the self-learning update coefficient of the actual EGR rate filter coefficient.

[0017] Furthermore, the preset time t0 is the time required for the exhaust gas to flow from the EGR control valve into the cylinder. The method for determining the preset time t0 includes:

[0018] On the engine test bench, the engine speed and the fresh air intake density entering the cylinder are fixed. The time required for the exhaust gas to flow from the EGR control valve into the cylinder is measured under multiple groups of different EGR control valve openings. The average time value is calculated and used as the preset time t0 under the current speed and fresh air intake density entering the cylinder. Base ;

[0019] Measurements are performed under different engine speeds and different fresh air intake densities entering the cylinder to obtain the preset time t0 under different working conditions.

[0020] Furthermore, the self-learning update coefficient r of the actual EGR rate filter coefficient EGRFilterAdapt The update methods include:

[0021] If the difference between the continuous time t when the EGR control valve opening is 0 minus the preset time t0 under the current working condition is not less than the preset value A, and the actual r after current filtering is EGRFilter Not greater than the preset threshold C;

[0022] Then the cumulative counter CNT1 of the excessive EGR rate when the EGR control valve is closed is increased by 1, and its initial value is 0;

[0023] If the difference between the preset time t0 under the current working condition and the continuous time t when the EGR control valve opening is 0 is not less than the preset value B, and the actual r after current filtering is EGRFilter Not less than the preset threshold D;

[0024] Then the accumulative counter CNT2 indicating that the EGR rate is too small when the EGR control valve is closed is incremented by 1, and its initial value is 0;

[0025] When reading CNT1>200 and CNT2<5, then r EGRFilterAdapt =r EGRFilterAdapt (z) + 0.02, and clear CNT1 and CNT2 to 0;

[0026] When reading CNT2>200 and CNT1<5, then r EGRFilterAdapt =r EGRFilterAdapt (z) -0.02, and clear CNT1 and CNT2 to 0;

[0027] In other cases, r EGRFilterAdapt =r EGRFilterAdapt (z);

[0028] Among them, r EGRFilterAdapt (z) is the self-learning update coefficient r of the actual EGR rate filter coefficient after the last update EGRFilterAdapt .

[0029] Furthermore, the self-learning update coefficient r of the actual EGR rate filter coefficient EGRFilterAdapt The update conditions are:

[0030] The engine speed fluctuation does not exceed a preset range, and the target fresh air intake density entering the cylinder does not fluctuate within a preset range.

[0031] Compared with the prior art, the present invention has the following main advantages:

[0032] The present invention proposes a method for estimating the actual EGR rate entering the cylinder. By limiting the actual EGR rate change rate and performing a discrete first-order low-pass filter processing on the EGR rate with limited change rate, the actual EGR rate is optimized when the EGR control valve is closed, and the learning parameters of the actual EGR rate are continuously updated during the vehicle life cycle, the estimation accuracy of the actual EGR rate can be effectively improved, thereby significantly enhancing the improvement effect of the EGR system on the vehicle engine performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an overall flow chart of the actual EGR rate estimation method in Example 1 of the present invention;

[0034] Figure 2 Schematic diagram of the EGR system in Example 1 of the present invention;

[0035] Figure 3 Schematic diagram of the steps of the estimation method in the second embodiment of the present invention.

[0036] In the figure: 1. EGR control valve inlet temperature sensor; 2. EGR control valve; 3. EGR cooler; 4. EGR cooler outlet temperature sensor; 5. Air line control valve. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0038] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0039] In the present invention, unless otherwise expressly specified or limited, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise expressly specified or limited.

[0040] Example 1. This embodiment provides a method for estimating the actual EGR rate entering the cylinder. By limiting the rate of change and using a filtering algorithm, the actual EGR rate is optimized when the EGR valve is closed, and the learning parameters of the actual EGR rate are continuously updated during the life cycle of the vehicle. This can effectively improve the estimation accuracy of the actual EGR rate, thereby significantly improving the improvement effect of the EGR system on the vehicle engine performance (engine emissions, fuel consumption, and anti-knock capability, etc.).

[0041] like Figure 1 As shown, the main strategies include the following:

[0042] S1, limiting the change rate of the initial value of the actual EGR rate entering the cylinder to obtain the EGR rate with limited change rate;

[0043] S2, based on the actual EGR rate filter coefficient, performing a discrete first-order low-pass filter process on the EGR rate with the limited change rate to obtain a filtered actual EGR rate, and using a self-learning update coefficient related to the real-time opening of the EGR control valve to self-learn and update the actual EGR rate filter coefficient;

[0044] S3, read the real-time opening of the EGR control valve. If the continuous time of the real-time opening being 0 exceeds a preset time value, the final actual EGR rate is set to 0. Otherwise, the filtered actual EGR rate is output as the final actual EGR rate.

[0045] like Figure 2 As shown, the EGR system mainly consists of an EGR control valve inlet temperature sensor 1, an EGR control valve 2 (with a position sensor), an EGR cooler 3, an EGR cooler outlet temperature sensor 4, and an air line control valve 5.

[0046] The EGR control valve inlet temperature sensor 1 is used to detect the exhaust gas temperature entering the EGR control valve 2;

[0047] EGR control valve 2 (with position sensor), used to control the valve opening and read the actual opening, used to calculate and control the EGR rate;

[0048] EGR cooler 3, used to cool the exhaust gas temperature;

[0049] EGR cooler outlet temperature sensor 4, used to read the temperature of exhaust gas entering the intake system;

[0050] Air line control valve 5, used to open and close the air line and control the density of fresh air intake into the cylinder;

[0051] The EGR air is taken in at the front side of the supercharger turbine, that is, the exhaust gas generated by engine combustion has not yet driven the turbine to boost and reduce the exhaust gas capacity. Because the exhaust gas pressure is relatively high, it is called high-pressure EGR; the mixing point where the EGR exhaust gas enters the intake system is after the throttle valve, just before entering the cylinder.

[0052] Furthermore, the method for determining the exhaust gas flow rate entering the cylinder includes:

[0053] 1) Obtaining the exhaust gas pressure at the outlet of the EGR control valve based on the mixing point position, and dividing the exhaust gas pressure at the outlet of the EGR control valve by the exhaust manifold pressure at the EGR intake point to obtain the gas pressure ratio between the outlet and the intake of the EGR control valve; the mixing point represents the mixing position of the EGR gas and the fresh air;

[0054] 2) Based on the gas pressure ratio between the outlet and inlet of the EGR control valve and the gas temperature of the EGR control valve, the exhaust gas flow rate of the EGR control valve is estimated using the compressible gas equation based on the ideal nozzle;

[0055] 3) The exhaust gas flow rate entering the cylinder is obtained based on the exhaust gas flow rate of the EGR control valve.

[0056] Furthermore, the method for determining the fresh air flow entering the cylinder includes:

[0057] 1) Obtain the fresh air flow entering the cylinder before fitting;

[0058] 2) determining whether all the accuracy conditions of the estimated fitting parameters are met, and if so, continuing to perform the subsequent steps; if not, determining that the estimated fresh air flow rate entering the cylinder is equal to the fresh air flow rate entering the cylinder before fitting;

[0059] The accuracy conditions of the fitting parameter estimation are specifically: the engine speed exceeds the preset speed; all cylinders are not cut off from fuel; the EGR control valve is in the closed state or the pressure ratio before and after the throttle valve is less than the preset pressure ratio;

[0060] 3) Calculate fitting parameters;

[0061] 4) Calculate the estimated fresh air flow entering the cylinder based on the fitting parameters.

[0062] Furthermore, the ratio of the exhaust gas flow rate divided by the sum of the exhaust gas flow rate and the fresh air flow rate is the actual initial value of the EGR rate entering the cylinder, r EGRRaw .

[0063] Example 2: This example provides a method for estimating the actual EGR rate entering a cylinder, which mainly includes the following steps:

[0064] The first step is to calculate the initial value of the actual EGR rate entering the cylinder r EGRRaw The actual EGR rate is controlled to limit the sudden change. EGRRaw The more theoretical formula is used to calculate the actual EGR rate. The fluctuation of the actual EGR rate is unlikely to be large. In order to avoid the large deviation of the EGR rate estimation, the change rate of the EGR rate is limited, and the EGR rate with limited change rate r is obtained. EGRLim ;

[0065] r EGRLim =r EGRLim (z)+max{min{[r EGRRaw -r EGRLim (z)],r EGRGrandInc},r EGRGrandDec}

[0066] Among them, r EGRLim (z) is the EGR rate with limited change rate in the previous sampling period (the sampling period in this example is 10ms), r EGRGrandInc is the maximum increment of EGR rate in a single sampling period, r EGRGrandInc =r EGRGrandIncBase ×(1+r EGRGrandIncAdapt )(The maximum incremental reference value r in this example EGRGrandIncBase Take 0.3 / s, r EGRGrandIncAdapt is the maximum incremental self-learning update coefficient, which is saved after the vehicle is powered off and its default value is 0), r EGRGrandDec is the maximum reduction of EGR rate in a single sampling period, r EGRGrandDec =r EGRGrandDecBase ×(1+r EGRGrandDecAdapt )(The maximum reduction benchmark value in this example is r EGRGrandDecBase Take -0.4 / s, r EGRGrandDecAdapt It is the maximum decrement self-learning update coefficient, which is saved after the vehicle is powered off and its default value is 0).

[0067] The second step is to limit the EGR rate r EGRLimA discrete first-order low-pass filter is performed to further limit the fluctuation of the EGR rate and avoid poor EGR closed-loop control accuracy (if the actual EGR rate estimate fluctuates greatly, it will weaken the closed-loop control stability) to obtain the actual EGR rate after filtering r EGRFilter

[0068] r EGRFilter (N) = K EGR ×[r EGRLim (N)-r EGRFilter (N-1)]+r EGRFilter (N-1)

[0069] Among them, r EGRLim (N) is the actual EGR rate r with the limited change rate in the Nth sampling period EGRLim , r EGRFilter is the actual EGR rate after discrete first-order low-pass filtering, r EGRFilter (N) is the actual EGR rate after filtering in the Nth sampling period, r EGRFilter (N-1) is the actual EGR rate after filtering in the N-1th sampling period, N = 1, 2, 3..., r EGRFilter (0) is equal to the actual EGR rate r at the 0th sampling period EGRLim (0), the 0th sampling period occurs when the vehicle is just powered on; the sampling period interval Δt in this example is 10ms. K EGR is the coefficient: (This example k EGR The calibration speed is 1000rpm. The purpose of this setting is to normalize the process. At different speeds, no special calibration is required. Only the k value at 1000 rpm needs to be calibrated. EGR , thereby reducing the calibration test work. Different engine speeds will cause fluctuations in exhaust pressure, thereby affecting the fluctuation of EGR exhaust gas), where n is the engine speed, k EGR is the actual EGR rate filter coefficient, k EGR =k EGRFilterBase ×(1+r EGRFilterAdapt ), actual EGR rate filter coefficient reference value k EGRFilterBase In this example, 0.06 is used. EGRFilterAdapt It is the self-learning update coefficient of the actual EGR rate filter coefficient, which is saved after the vehicle is powered off. Its default value is 0.

[0070] The third step is to read the actual opening of the EGR valve at that time.

[0071] 1) If the continuous time t (starting from the time when the actual opening of the EGR valve is 0) that the actual opening of the EGR valve is 0 exceeds the preset time t0, the actual EGR rate entering the cylinder is set to 0, that is, rEGRFinal =0

[0072] 2) Otherwise, r EGRFinal =r EGRFilter

[0073] The preset time t0 refers to the time required for exhaust gas to flow from the EGR valve into the cylinder. The method for determining t0 is to adjust the EGR exhaust gas volume on the engine test bench by fixing the engine speed and the fresh air intake density entering the cylinder to test the time it takes for EGR exhaust gas to flow from the EGR valve into the cylinder. The average time is collected through multiple groups of tests and used as the preset time t0 under the current speed and fresh air intake density. Base The test was conducted under different engine speeds and different fresh air intake densities entering the cylinder to obtain the preset time t0 under different working conditions.

[0074] The fourth step is to determine and output the final actual EGR rate.

[0075] Furthermore, the self-learning update coefficient r EGRFilterAdapt The methods for obtaining include:

[0076] Actual EGR rate filter coefficient self-learning update coefficient r EGRFilterAdapt Updates will be made when the following conditions are met:

[0077] 1) The engine speed fluctuation does not exceed a preset range, in this example ±15 rpm;

[0078] 2) The target fresh air intake density of the engine entering the cylinder does not fluctuate within a preset range, which in this example is ±20 mgpl;

[0079] If the first case occurs:

[0080] a) The difference between the continuous time t during which the actual EGR valve opening is 0 (starting from the time when the actual EGR valve opening is 0) and the preset time t0 read in real time is not less than the preset value A, which is 0.03s in this example.

[0081] and b) the filtered EGR rate r read in real time EGRFilter ≥0.01;

[0082] The cumulative counter CNT1 of the excessive EGR rate when the EGR valve is closed is incremented by 1, and its default value is 0. CNT1 is updated only once when the condition is met this time, and it is determined whether to update CNT1 when the condition is not met again.

[0083] If the second situation occurs:

[0084] a) The difference between the preset time t0 read in real time and the continuous time t during which the actual EGR valve opening is 0 (the time starts from when the actual EGR valve opening is 0) is not less than the preset value B, which is 0.03s in this example.

[0085] and b) the filtered EGR rate r read in real time EGRFilter The difference from 0 does not exceed the preset value, which is 0.005 in this example.

[0086] The cumulative counter CNT2 of the EGR rate being too small when the EGR valve is closed is incremented by 1, and its default value is 0. CNT2 is updated only once when the condition is met this time, and it is determined whether to update CNT2 again when the condition is not met again.

[0087] If CNT1 is greater than 200 but CNT2 is less than 5, then:

[0088] r EGRFilterAdapt =r EGRFilterAdapt (z) + 0.02, and clear CNT1 and CNT2 to 0;

[0089] If CNT2 is greater than 200 but CNT1 is less than 5, then:

[0090] r EGRFilterAdapt =r EGRFilterAdapt (z) -0.02, and clear CNT1 and CNT2 to 0;

[0091] In other cases, r EGRFilterAdapt =r EGRFilterAdapt (z)

[0092] Among them, r EGRFilterAdapt (z) is the actual EGR rate filter coefficient self-learning update coefficient after the last update. If it has never been updated, then r EGRFilterAdapt (z) is the default value of the actual EGR rate filter coefficient self-learning update coefficient after the last update.

[0093] Furthermore, the target EGR rate r EGRDsrd Fluctuation, the method for judging the fluctuation is

[0094] r EGRDsrdFilter (N) = K EGRDsrd ×[r EGRDsrd (N)-r EGRDsrdFilter (N-1)]+r EGRDsrdFilter (N-1)

[0095] Among them, r EGRDsrd (N) is the target EGR rate of the Nth sampling period, r EGRDsrdFilter is the target EGR rate after discrete first-order low-pass filtering, r EGRDsrdFilter(N) is the filtered target EGR rate of the Nth sampling period, r EGRDsrdFilter (N-1) is the filtered target EGR rate of the N-1th sampling period, N = 1, 2, 3..., r EGRDsrdFilter (0) is equal to the target EGR rate r at the 0th sampling cycle EGRDsrd (0), the 0th sampling period occurs when the vehicle is just powered on; the sampling period interval Δt in this example is 10ms. K EGRDsrd is the target EGR rate filter coefficient: (This example k EGRDsrd The calibration speed is 1000rpm. The purpose of this setting is to normalize the process. At different speeds, no special calibration is required. Only the k value at 1000 rpm needs to be calibrated. EGRDsrd , thereby reducing the calibration test work. Different engine speeds will cause fluctuations in exhaust pressure, thereby affecting the fluctuation of EGR exhaust gas), where n is the engine speed, k EGRDsrd In this example, 0.06 is used.

[0096] r EGRDsrdFilter (N) = K EGRDsrd ×[r EGRDsrd (N)-r EGRDsrdFilter (N-1)]+r EGRDsrdFilter (N-1)

[0097] In|r EGRDsrdFilter (N)-r EGRDsrd (N)≥min[r EGRDsrdFilter (N), r EGRDsrd (N)]×r EGRDsrdLim The condition is continuously met for a period of time up to T EGRDsrd The target EGR rate is in a fluctuating state. EGRDsrdLim In this example, we take 0.05, T EGRDsrd In this example, the time is 3s.

[0098] Furthermore, if the following conditions are met at the same time:

[0099] 1) The target EGR rate is fluctuating;

[0100] 2) The target EGR rate is greater than 0;

[0101] Then read the time T EGRDsrd Average value of short-term fuel correction value r ST (The definition of short-term fuel correction can be found in patent CN202111202932.0 "An engine short-term fuel correction control method and control system");

[0102] a) If r ST>1.15 (if the short-term fuel correction is too large, it means the injection amount is too small and fuel compensation is needed, which indirectly means that the fresh air amount is estimated too little, which means that the actual EGR rate is estimated too much), and the actual EGR valve opening is not 0, then the EGR rate change rate accumulation counter CNT3 is incremented by 1. Its default value is 0. CNT3 is updated only once when the condition is met. It will be determined whether to update CNT3 again after the condition is no longer met.

[0103] b) If 1.1 < r ST If the short-term fuel correction is less than 1.15 (a large short-term fuel correction indicates a small amount of fuel injection and the need for fuel compensation, which indirectly indicates that the estimated fresh air volume is small, which means that the actual EGR rate estimate is large), and the actual EGR valve opening is not 0, then the EGR rate change rate is large. The cumulative counter CNT4 is incremented by 1, and its default value is 0. CNT4 is updated only once when the condition is met. If the condition is no longer met and is met again, it is determined whether to update CNT4.

[0104] c) If r ST <0.85 (if the short-term fuel correction is too small, it means that the injection amount is too high and needs to be reduced, which indirectly means that the fresh air amount is overestimated, and the actual EGR rate is underestimated), and the actual EGR valve opening is not 0, then the EGR rate change rate accumulation counter CNT5 is incremented by 1. Its default value is 0. CNT5 is updated only once when the condition is met. It will be determined whether to update CNT5 again after the condition is no longer met.

[0105] d) If 0.85 < r ST ≤0.9, (a small short-term fuel correction indicates a large amount of fuel injection and needs to be reduced, indirectly indicating a large amount of fresh air is estimated, which means the actual EGR rate is estimated to be small), and the actual EGR valve opening is not 0, then the EGR rate change rate is small, and the cumulative counter CNT6 is incremented by 1, with a default value of 0;

[0106] The CNT6 is updated only once when the condition is met. When the condition is no longer met and is met again, it is determined whether to update the CNT6.

[0107] e) If 0.9<r ST <1, (the short-term fuel correction is too small, which means that the injection amount is too much and needs to be reduced, which indirectly means that the estimated fresh air amount is too much, which means that the actual EGR rate is too small), the actual EGR valve opening is not 0;

[0108] e.1)r EGRDsrdFilter (N)-r EGRDsrd (N) at time T EGRDsrd Average value within If it is greater than 0 (indicating that the target EGR rate is decreasing), the EGR rate filter coefficient is appropriately increased. The self-learning update coefficient cumulative counter CNT7 is incremented by 1, and its default value is 0. CNT7 is updated only once when the current condition is met. When the condition is no longer met and is met again, it is determined whether to update CNT7.

[0109] e.2)r EGRDsrdFilter (N)-r EGRDsrd (N) at time T EGRDsrd Average value within If it is less than 0 (indicating that the target EGR rate is increasing), the EGR rate filter coefficient is appropriately small. The self-learning update coefficient cumulative counter CNT8 is increased by 1, and its default value is 0. CNT8 is only updated once when the condition is met this time. When the condition is not met and is met again, it is determined whether to update CNT8.

[0110] f) If 1<r ST <1.1, (a large short-term fuel correction indicates that the injection amount is small and needs to be increased, which indirectly indicates that the estimated fresh air amount is small, which means that the actual EGR rate is estimated to be large), the actual EGR valve opening is not 0;

[0111] f.1)r EGRDsrdFilter (N)-r EGRDsrd (N) at time T EGRDsrd Average value within If it is greater than 0 (indicating that the target EGR rate is decreasing), the EGR rate filter coefficient is appropriately small, and the self-learning update coefficient cumulative counter CNT9 is increased by 1. Its default value is 0. CNT9 is only updated once when the current condition is met. When the condition is not met and is met again, it is determined whether to update CNT9;

[0112] f.2)r EGRDsrdFilter (N)-r EGRDsrd (N) at time T EGRDsrd Average value within If it is less than 0 (indicating that the target EGR rate is increasing), the EGR rate filter coefficient is appropriately increased. The self-learning update coefficient accumulation counter CNT10 is increased by 1, and its default value is 0. CNT10 is updated only once when the condition is met this time. When the condition is no longer met and is met again, it is determined whether to update CNT10.

[0113] Furthermore, if the reading shows that CNT3 is greater than 200, CNT5 is less than 5, and CNT6 is less than 5, then:

[0114] r EGRGrandIncAdapt =r EGRGrandIncAdapt (z)-0.01, r EGRGrandDecAdapt =r EGRGrandDecAdapt(z) -0.01 and clear CNT3, CNT4, CNT5, and CNT6 to 0

[0115] If the value of CNT4 is greater than 200, CNT5 is less than 5, and CNT6 is less than 5, then:

[0116] r EGRGrandIncAdapt =r EGRGrandIncAdapt (z)-0.005, r EGRGrandDecAdapt =r EGRGrandDecAdapt (z) -0.005 and clear CNT3, CNT4, CNT5, and CNT6 to 0

[0117] If the value of CNT5 is greater than 200, CNT3 is less than 5, and CNT4 is less than 5, then:

[0118] r EGRGrandIncAdapt =r EGRGrandIncAdapt (z)+0.01, r EGRGrandDecAdapt =r EGRGrandDecAdapt (z) + 0.01 and clear CNT3, CNT4, CNT5, and CNT6 to 0

[0119] If the value of CNT6 is greater than 200, CNT3 is less than 5, and CNT4 is less than 5, then:

[0120] r EGRGrandIncAdapt =r EGRGrandIncAdapt (z)+0.005, r EGRGrandDecAdapt =r EGRGrandDecAdapt (z) + 0.005 and clear CNT3, CNT4, CNT5, and CNT6 to 0

[0121] In other cases, r EGRGrandIncAdapt =r EGRGrandIncAdapt (z), r EGRGrandDecAdapt =r EGRGrandDecAdapt (z)

[0122] Among them, r EGRGrandIncAdapt (z), r EGRGrandDecAdapt (z) are the actual EGR rate change coefficient self-learning update coefficients after the last update. If it has never been updated, then r EGRGrandIncAdapt (z), r EGRGrandDecAdapt (z) is the default value.

[0123] The above priorities decrease gradually and are judged at most once per driving cycle.

[0124] Further, r EGRFilterAdapt Will be updated in the following cases

[0125] The first one is if both

[0126] 1) CNT7 is greater than 200, or CNT10 is greater than 200;

[0127] 2) CNT8 is less than 5;

[0128] 3) CNT9 is less than 5;

[0129] Then r EGRFilterAdapt =r EGRFilterAdapt (z) -0.01, and CNT7, CNT8, CNT9, and CNT10 are cleared to 0.

[0130] The second type, if both

[0131] 1) CNT8 is greater than 200, or CNT9 is greater than 200;

[0132] 2) CNT7 is less than 5;

[0133] 3) CNT10 is less than 5;

[0134] Then r EGRFilterAdapt =r EGRFilterAdapt (z) + 0.01, and clear CNT7, CNT8, CNT9, and CNT10 to 0.

[0135] In other cases, r EGRFilterAdapt =r EGRFilterAdapt (z).

[0136] Furthermore, the vehicle engine control system performs closed-loop control based on the actual EGR rate obtained in this application, so that the actual EGR rate approaches the target EGR rate, thereby achieving precise control of the EGR rate and significantly improving engine performance.

[0137] Embodiment 3: Based on the same inventive concept, this embodiment also provides a vehicle electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the actual EGR rate estimation method as described above is implemented.

[0138] Embodiment 4: Based on the same inventive concept, this embodiment further provides a manual-automatic vehicle, which is provided with the vehicle electronic equipment as described above.

[0139] Furthermore, all parts of this application that are not described in detail are the same as the existing technology or are implemented using the existing technology.

[0140] In summary:

[0141] The present invention proposes a method for estimating the actual EGR rate entering the cylinder. By limiting the actual EGR rate change rate and performing a discrete first-order low-pass filter processing on the EGR rate with limited change rate, and optimizing the actual EGR rate when the EGR control valve is closed, and continuously updating the learning parameters of the actual EGR rate during the vehicle life cycle, the estimation accuracy of the actual EGR rate can be effectively improved, thereby significantly enhancing the improvement effect of the EGR system on vehicle engine emissions, fuel consumption and anti-knock capability.

[0142] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0143] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0144] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0145] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0146] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for estimating the actual EGR rate entering a cylinder, characterized in that: include: Limiting the change rate of the initial value of the actual EGR rate entering the cylinder to obtain an EGR rate with a limited change rate; Based on the actual EGR rate filter coefficient, a discrete first-order low-pass filter is performed on the EGR rate with a limited change rate to obtain a filtered actual EGR rate, and a self-learning update coefficient related to the real-time opening of the EGR control valve is used to self-learn and update the actual EGR rate filter coefficient; The real-time opening of the EGR control valve is read. If the continuous time of the real-time opening being 0 exceeds a preset time value, the final actual EGR rate is set to 0; otherwise, the filtered actual EGR rate is output as the final actual EGR rate.

2. The method for estimating the actual EGR rate entering the cylinder according to claim 1, characterized in that: The initial value of the actual EGR rate entering the cylinder is: the ratio of the exhaust gas flow entering the cylinder to the sum of the fresh air flow and the exhaust gas flow entering the cylinder.

3. The method for estimating the actual EGR rate entering the cylinder according to claim 1, characterized in that: The EGR rate with the limited change rate is determined by: Calculate the actual initial value of EGR rate entering the cylinder r EGRRaw The EGR rate r that limits the change rate in the previous sampling cycle EGRLim The difference of (z) is recorded as difference one; Compare the difference value with the maximum EGR rate increment r in a single sampling cycle EGRGrandInc , take the minimum value of the two and record it as the minimum value one; Compare the minimum value with the maximum EGR rate reduction r in a single sampling cycle EGRGrandDec , take the maximum value of the two and record it as the maximum value one; According to the EGR rate r of the limit change rate in the previous sampling period EGRLim (z) and the maximum value, calculate the EGR rate r that limits the change rate EGRLim .

4. The method for estimating the actual EGR rate entering the cylinder according to claim 1, characterized in that: The actual EGR rate after filtering r EGRFilter , the determination methods include: Calculate the EGR rate r that limits the change rate in the Nth sampling period EGRLim (N) and the actual EGR rate r after filtering in the N-1 sampling period EGRFilter The difference of (N-1) is recorded as difference two; According to the difference 2 and the actual EGR rate filter coefficient k EGR And the actual EGR rate r after filtering in the N-1th sampling period EGRFilter (N-1), calculate the actual EGR rate r after filtering in the Nth sampling period EGRFilter (N); Among them, the actual EGR rate filter coefficient k EGR Based on the actual EGR rate filter coefficient reference value k EGRFilterBase And the self-learning update coefficient r of the actual EGR rate filter coefficient EGRFilterAdapt Calculated.

5. The method for estimating the actual EGR rate entering the cylinder according to claim 1, characterized in that: The preset time t0 is the time required for the exhaust gas to flow from the EGR control valve into the cylinder. The method for determining the preset time t0 includes: On the engine test bench, the engine speed and the fresh air intake density entering the cylinder are fixed. The time required for the exhaust gas to flow from the EGR control valve into the cylinder is measured under multiple groups of different EGR control valve openings. The average time value is calculated and used as the preset time t0 under the current speed and fresh air intake density entering the cylinder. Base ; Measurements are performed under different engine speeds and different fresh air intake densities entering the cylinder to obtain the preset time t0 under different working conditions.

6. The method for estimating the actual EGR rate entering the cylinder according to claim 4, characterized in that: The self-learning update coefficient r of the actual EGR rate filter coefficient EGRFilterAdapt The update methods include: If the difference between the continuous time t when the EGR control valve opening is 0 minus the preset time t0 under the current working condition is not less than the preset value A, and the actual r after current filtering is EGRFilter Not greater than the preset threshold C; Then the cumulative counter CNT1 of the excessive EGR rate when the EGR control valve is closed is increased by 1, and its initial value is 0; If the difference between the preset time t0 under the current working condition and the continuous time t when the EGR control valve opening is 0 is not less than the preset value B, and the actual r after current filtering is EGRFilter Not less than the preset threshold D; Then the accumulative counter CNT2 indicating that the EGR rate is too small when the EGR control valve is closed is incremented by 1, and its initial value is 0; When reading CNT1>200 and CNT2<5, the preset correction value is added based on the self-learning update coefficient of the actual EGR rate filter coefficient after the last update, and CNT1 and CNT2 are cleared to 0; When CNT2>200 and CNT1<5 is read, the preset correction value is subtracted from the self-learning update coefficient of the actual EGR rate filter coefficient after the last update, and CNT1 and CNT2 are cleared to 0; In other cases, the self-learning update coefficient of the actual EGR rate filter coefficient after the last update is kept unchanged.

7. The method for estimating the actual EGR rate entering the cylinder according to claim 6, characterized in that: The self-learning update coefficient r of the actual EGR rate filter coefficient EGRFilterAdapt The update conditions are: The engine speed fluctuation does not exceed a preset range, and the target fresh air intake density entering the cylinder does not fluctuate within a preset range.

8. A vehicle electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the actual EGR rate estimation method according to any one of claims 1 to 7 is implemented.

9. A non-transitory readable storage medium having a program stored thereon, characterized in that: When the program is executed by a vehicle electronic device, the actual EGR rate estimation method according to any one of claims 1 to 7 is implemented.

10. A manual-automatic vehicle, characterized in that: The vehicle electronic device comprising the vehicle electronic device according to claim 8.

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