An optimization control method of a target EGR rate

Abstract

The application discloses an optimization control method of a target EGR rate, and comprises the following steps: entering EGR closed-loop enabling under the condition that EGR system closed-loop enabling is met; determining a filtering time coefficient of the target EGR rate according to a supercharger response time and a time of exhaust gas flowing from an EGR valve to an EGR exhaust gas merging point, and calculating a change rate of the filtering time coefficient of the target EGR rate; obtaining a filtering time according to the filtering time learning coefficient and the change rate of the filtering time coefficient of the target EGR rate; obtaining a filtered target EGR rate according to the filtering time and the target EGR rate; and controlling the EGR valve according to the filtered target EGR rate. The method provided by the application can optimize the target EGR rate, improve the influence of EGR entering on engine knock deterioration, and improve engine supercharging control stability and emission performance.

Description

Technical Field

[0001] This invention relates to the field of engine control technology, and in particular to an optimized control method for a target EGR rate. Background Technology

[0002] Exhaust gas recirculation (EGR) systems draw exhaust gases from the engine and reintroduce them into the intake system. Studies have shown that EGR systems offer advantages in improving emissions, reducing fuel consumption, and enhancing anti-knock capabilities. In low-pressure EGR systems, the control of the mixing valve is particularly important for improving the EGR rate. Optimizing the target EGR rate and improving control stability and emissions remain areas requiring further research. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an optimized control method for the target EGR rate to address the shortcomings of the prior art. This method can optimize the target EGR rate, improve the impact of EGR on engine knocking when it enters, and improve the stability of engine boost control and emission performance.

[0004] To achieve the above objectives, according to one aspect of the present invention, an optimization control method for a target EGR rate is provided, comprising:

[0005] When the EGR system closed-loop enable condition is met, EGR closed-loop enable is entered. The filter time coefficient of the target EGR rate is determined based on the turbocharger response time and the time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point. The rate of change of the filter time coefficient of the target EGR rate is calculated.

[0006] The filtering time is obtained based on the rate of change of the filtering time learning coefficient and the filtering time coefficient of the target EGR rate;

[0007] The filtered target EGR rate is obtained based on the filtering time and the target EGR rate.

[0008] The EGR valve is controlled according to the filtered target EGR rate;

[0009] The filter time learning coefficient has an initial value, and after operation, it is calculated and updated based on the target boost pressure, actual boost pressure, target air-fuel ratio, actual air-fuel ratio, target EGR rate, actual EGR rate, the updated filtered target EGR rate, the cumulative number of high-intensity knocking events in the engine, and the catalytic converter oxygen storage capacity coefficient.

[0010] In the above scheme, the booster response time τ Boost The time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet; the turbocharger response time τ Boost The method obtained through bench calibration is as follows: at different engine speeds neng And different actual intake air densities rho entering the cylinder Act Under different EGR rates, the average time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet is obtained through multiple sampling.

[0011] In the above scheme, the time τ for the exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point is... EGR The method obtained through bench calibration is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act Under different EGR rates, the average time taken for exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point is obtained through multiple samplings; the EGR exhaust gas confluence point refers to the location where the EGR exhaust gas merges with fresh air.

[0012] In the above scheme, based on the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR Determine the filter time coefficient k for the target EGR rate T The method is as follows:

[0013]

[0014] Where, k T τ is the filter time coefficient for the target EGR rate. Boost τ is the turbocharger response time. EGR The time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point is τ. In this invention, the turbocharger response time τ is used as the reference. Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR Determine the filter time coefficient k for the target EGR rate T The goal is to improve the robustness of EGR rate control by considering both boost response characteristics and EGR response characteristics while optimizing the target EGR rate.

[0015] In the above scheme, the filter time coefficient k for calculating the target EGR rate is... T rate of change dk T The method is as follows:

[0016]

[0017] Where Δt is the sampling time, dk T (z) is the filter time coefficient k of the target EGR rate in the previous sampling period. T rate of change dk T k T (z) represents the filtering time coefficient k of the previous sampling period.T k at the initial time T (z) occurs at the EGR closed-loop enable time, with a default value of 1, and the initial dk T (z) occurs at the EGR closed-loop enable time, and its default value is 0, t c This is a preset time constant. The purpose of calculating the rate of change of the filter time coefficient in this invention is to avoid excessively rapid changes in the rate of change, which would cause large fluctuations in the target EGR rate filter time T, thus affecting the target EGR rate and causing it to change too quickly.

[0018] In the above scheme, based on the filtering time learning coefficient r T and the filter time coefficient k of the target EGR rate T rate of change dk T The method for obtaining the filtering time is as follows:

[0019] T = f(dk) T )×(1+r T );

[0020] Where T is the filtering time; r T The filtering time learning coefficients can be saved after the vehicle is powered off and can be continuously learned and updated during vehicle operation; their default value is 0; f(dk) T ) is the default time for the filtering time T, f(dk) T The value is determined by the filter time coefficient k of the target EGR rate. T rate of change dk T The decision, specifically: when dk T When <-200, f(dk) T ) = 0.15s; when dk T When >200, f(dk) T ) = 0.18s; when -200 ≤ dk T When <-100, f(dk) T ) = 0.12s; when -100 ≤ dk T When <-50, f(dk) T ) = 0.1s; when -50 ≤ dk T When <-10, f(dk) T ) = 0.05s; when -10 ≤ dk T When < 0, f(dk) T ) = 0.01s; when 0 ≤ dk T When <10, f(dk) T ) = 0.05s; when 10 ≤ dk T When <50, f(dk) T ) = 0.12s; when 50 ≤ dk T When <100, f(dk)T ) = 0.16s; when 100 ≤ dk T When <200, f(dk) T = 0.18s.

[0021] In the above scheme, the filter time learning coefficient has an initial value. After operation, it is calculated and updated based on the target boost pressure, actual boost pressure, target air-fuel ratio, actual air-fuel ratio, target EGR rate, actual EGR rate, the updated filtered target EGR rate, the cumulative number of high-intensity knocking events in the engine, and the catalytic converter oxygen storage capacity coefficient. The specific method is as follows: when the time for meeting the filter time learning coefficient judgment condition exceeds a preset time t1, the average value p of the difference between the target boost pressure and the actual boost pressure within time t1 is read. BoostErrAvg The average difference r between the target air-fuel ratio and the actual air-fuel ratio AFRErrAvg The average difference r between the updated filtered target EGR rate and the actual EGR rate EGRErrAvg The average target EGR rate r after filtering EGRDsrdFilterAvg Target EGR rate average r EGRDsrdRawAvg The cumulative number of high-intensity knock events in the engine (Cnt) Knock ; Catalyst oxygen storage capacity coefficient r CatalystOxygen The method for obtaining the target EGR rate is described in patent CN112459910A, entitled "A Method and System for Calculating the Target EGR Rate"; the cumulative number of high-intensity knocking events in the engine, Cnt. Knock For the method of obtaining the octane number, please refer to the patent with publication number CN111878279A, "A method and system for self-learning the octane number of oil products". For the method of reading the oxygen storage capacity of the catalytic converter, please refer to the patent with publication number CN110259553A, "A method, device and electronic equipment for calculating the oxygen storage capacity of a three-way catalytic converter". For the method of reading the maximum oxygen storage capacity of the catalytic converter, please refer to the patent with publication number CN104594986A, "A method for diagnosing engine catalytic converter deterioration".

[0022] Obtain the filtering time learning coefficient r T The specific methods are as follows:

[0023] First scenario: If the average target EGR rate after the update and filtering is r EGRDsrdFilterAvg Greater than the average target EGR rate r EGRDsrdRawAvg If the value exceeds the preset value, it indicates that the EGR rate is decreasing. Therefore, the following conditions—first, second, third, fourth, and fifth—are applied sequentially to determine the filtering time learning coefficient r. T Calculate and update:

[0024] First condition: If the cumulative number of high-intensity knock events is CntKnock ≥CNT1, where CNT1 is a preset value, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value, then r T =r T (z)+0.02, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0025] Second condition: If the cumulative number of high-intensity knock events is Cnt Knock ≥CNT1, where CNT1 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0026] Third condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg |≤0.01, and r CatalystOxygen ≤r C , where r C If r is the preset value, then T =r T (z)-0.03, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0027] Fourth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0028] Fifth condition: In other cases, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0029] The priority of the first, second, third, fourth, and fifth conditions decreases from one to the next. That is, if a previous condition is met, only the update result of that condition will be executed. For example, if the first condition is met, only the update result of the first condition will be executed, and the update results of the subsequent conditions will not be executed.

[0030] Second scenario: If the target EGR rate averages r EGRDsrdRawAvg Greater than the average target EGR rate r after the update and filtering EGRDsrdFilterAvg If the value exceeds the preset value, it indicates that the EGR rate is increasing. Therefore, the following conditions (sixth, seventh, eighth, ninth, and tenth) are applied sequentially to determine the filtering time learning coefficient r. T Calculate and update:

[0031] Sixth condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value, then r T =r T (z)+0.03, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0032] Seventh condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0033] Eighth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg |≤0.01, and r CatalystOxygen ≤r C , where r C If r is the preset value, then T =r T (z)-0.02, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0034] Ninth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0035] Tenth condition: In other cases, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0036] The priority of the sixth, seventh, eighth, ninth, and tenth conditions above decreases, meaning that if a preceding condition is met, only the update result of that preceding condition will be executed; for example, if the sixth condition is met, only the update method for the sixth condition will be executed, and the update methods for the following conditions will not be executed.

[0037] Third case: In other cases where neither the first case nor the second case is satisfied, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value.

[0038] In the above scheme, the filtered target EGR rate r is obtained based on the filtering time and the target EGR rate. EGRDsrdFilter The method is as follows:

[0039]

[0040] Where, r EGRDsrdFilter (N) represents the target EGR rate r after filtering in the Nth sampling period. EGRDsrdFilter r EGRDsrdFilter (N-1) represents the target EGR rate r after filtering in the N-1th sampling period. EGRDsrdFilter Δt is the sampling time, N = 1, 2, 3…, where r EGRDsrdFilter (0) equals 0, which occurs at the moment the vehicle is powered on, r EGRDsrdRaw For the target EGR rate, r EGRDsrdRaw (N) represents the target EGR rate of the Nth sampling period, and T represents the filtering time.

[0041] In the above scheme, the condition for determining the learning coefficients during the filtering time is:

[0042] (1) Engine speed fluctuation does not exceed the preset value;

[0043] (2) The actual intake air density fluctuation does not exceed the preset value;

[0044] (3) EGR system closed-loop enable;

[0045] (4) The difference between the target boost pressure and the system's maximum boost pressure and minimum boost pressure exceeds the preset value;

[0046] (5) The difference between the system's maximum boost pressure and the target boost pressure exceeds the preset value;

[0047] (6) The engine coolant temperature does not exceed the preset value;

[0048] (7) The engine intake air temperature does not exceed the preset value.

[0049] In the above scheme, the closed-loop enable condition of the EGR system is:

[0050] (1) No related faults were found in any of the components of the EGR system;

[0051] (2) No fuel cut-off request was received or the fuel cut-off recovery time exceeded the preset time;

[0052] (3) The updated filtered target EGR rate is not less than the minimum EGR rate; wherein the method for obtaining the minimum EGR rate is described in the patent "Method, Apparatus, Device and Storage Medium for Adjusting Minimum EGR Rate" with publication number CN115585070A.

[0053] (4) The engine speed is within the preset speed range;

[0054] (5) The intake air temperature is within the preset range;

[0055] (6) The engine coolant temperature is within the preset range;

[0056] (7) The atmospheric temperature is within the preset range;

[0057] (8) When the atmospheric pressure exceeds 66 kPa, the EGR closed-loop enable condition is allowed; when the atmospheric temperature is below 64 kPa, the EGR closed-loop enable condition needs to be exited.

[0058] In the above scheme, the intake air temperature within the preset range specifically includes: if the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state requires ensuring that the intake air temperature is not lower than the minimum intake air temperature of 10°C; if the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires ensuring that the intake air temperature is lower than the minimum intake air temperature of 7°C; if the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state requires ensuring that the intake air temperature does not exceed the maximum intake air temperature of 60°C; if the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires ensuring that the intake air temperature exceeds the maximum intake air temperature of 65°C.

[0059] In the above scheme, the engine coolant temperature within the preset range specifically includes: if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the coolant temperature is not lower than the minimum coolant temperature of 60℃; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the coolant temperature is lower than the minimum coolant temperature of 55℃; if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the coolant temperature does not exceed the maximum coolant temperature of 115℃; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the coolant temperature exceeds the maximum coolant temperature of 120℃.

[0060] In the above scheme, the atmospheric temperature within the preset range specifically includes: if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the temperature is not lower than the minimum atmospheric temperature by 5°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the temperature is lower than the minimum atmospheric temperature by 3°C; if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the temperature does not exceed the maximum atmospheric temperature by 55°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the temperature exceeds the maximum atmospheric temperature by 60°C.

[0061] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0062] This invention provides an optimized control method for a target EGR rate. This method optimizes the target EGR rate, improves the impact of EGR on engine knocking and boosting stability, and also improves the impact on emissions degradation. Attached Figure Description

[0063] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0064] Figure 1 This is a schematic diagram of the system structure with EGR in an embodiment of the present invention.

[0065] Figure 2 This is a flowchart illustrating the optimization control method for the target EGR rate in an embodiment of the present invention.

[0066] Figure Labels

[0067] 1-Air filter; 2-Mix valve; 3-Compressor; 4-Throttle valve; 5-Engine; 6-Turbine; 7-Catalyst; 8-Particulate matter filter; 9-EGR cooler; 10-EGR valve; 11-Temperature sensor; 12-Differential pressure sensor. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be 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 illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0069] It should be understood that the sequence number of each step in the embodiment does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0070] Example 1

[0071] The system architecture with EGR on which this invention is based is as follows: Figure 1 As shown, it includes: an air filter 1; a mixing valve 2 connected to the air filter, used to regulate the pressure at the outlet of the EGR valve 10, increasing the pressure difference across the EGR valve 10, with two airflow passages extending from the mixing valve 2; a compressor 3 connected to one of the airflow passages of the mixing valve 2; a throttle valve 4 connected to the compressor 3; an engine 5 connected to the throttle valve 4, used to compress fresh air for boosting; a turbine 6 connected to the engine 5, used to control the opening of the exhaust bypass valve; a catalytic converter 7 connected to the turbine 6; and a particulate filter 8 connected to the catalytic converter 7; and an installation... An EGR cooler 9 on another airflow path of the mixing valve 2 is used to receive and cool the exhaust gas output from the particulate filter 8, thereby increasing the exhaust gas flow rate; one end is connected to the EGR cooler 9 and the other end is connected to the EGR valve 10 of the mixing valve 2, which is used to control the exhaust gas flow rate entering the cylinder; a temperature sensor 11 installed between the EGR valve 10 and the EGR cooler 9 is used to detect the exhaust gas temperature entering the EGR valve 10; a differential pressure sensor 12 connected to the EGR valve 10 is used to detect the pressure at the inlet and outlet of the EGR valve 10.

[0072] This application provides an optimized control method for a target EGR rate according to one aspect of the present invention, see reference. Figure 2 ,include:

[0073] S1, under the condition that the EGR system closed-loop enable condition is met, enter the EGR closed-loop enable, determine the filter time coefficient of the target EGR rate based on the turbocharger response time and the time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas junction, and calculate the rate of change of the filter time coefficient of the target EGR rate.

[0074] Specifically, in this embodiment, the closed-loop enable condition for the EGR system is:

[0075] (1) No related faults were found in any of the components of the EGR system;

[0076] (2) No fuel cut-off request occurs or the fuel cut-off recovery time exceeds the preset time. In this embodiment, the preset time is 0.3s.

[0077] (3) The updated filtered target EGR rate is not less than the minimum EGR rate;

[0078] (4) The engine speed is within the preset speed range. In this embodiment, the preset speed range is 750rpm~5500rpm.

[0079] (5) The intake air temperature is within the preset range; if the current state is that the EGR closed loop is not enabled, then enter the EGR closed loop state, and ensure that the intake air temperature is not lower than the minimum intake air temperature by 10°C; if the current state is that the EGR closed loop is enabled, then exit the EGR system closed loop enabled state, and ensure that the intake air temperature is lower than the minimum intake air temperature by 7°C; if the current state is that the EGR closed loop is not enabled, then enter the EGR closed loop state, and ensure that the intake air temperature does not exceed the maximum intake air temperature by 60°C; if the current state is that the EGR closed loop is enabled, then exit the EGR system closed loop enabled state, and ensure that the intake air temperature exceeds the maximum intake air temperature by 65°C.

[0080] (6) The engine coolant temperature is within the preset range; if the current state is EGR closed loop not enabled, then enter the EGR closed loop state, and ensure that the coolant temperature is not lower than the minimum coolant temperature of 60℃; if the current state is EGR closed loop enabled, then exit the EGR system closed loop enabled state, and ensure that the coolant temperature is lower than the minimum coolant temperature of 55℃; if the current state is EGR closed loop not enabled, then enter the EGR closed loop state, and ensure that the coolant temperature does not exceed the maximum coolant temperature of 115℃; if the current state is EGR closed loop enabled, then exit the EGR system closed loop enabled state, and ensure that the coolant temperature exceeds the maximum coolant temperature of 120℃.

[0081] (7) The atmospheric temperature is within the preset range; if the current state is that the EGR closed loop is not enabled, then enter the EGR closed loop state, and it is necessary to ensure that the temperature is not lower than the minimum atmospheric temperature by 5℃; if the current state is that the EGR closed loop is enabled, then exit the EGR system closed loop enabled state, and it is necessary to ensure that the temperature is lower than the minimum atmospheric temperature by 3℃; if the current state is that the EGR closed loop is not enabled, then enter the EGR closed loop state, and it is necessary to ensure that the temperature does not exceed the maximum atmospheric temperature by 55℃; if the current state is that the EGR closed loop is enabled, then exit the EGR system closed loop enabled state, and it is necessary to ensure that the temperature exceeds the maximum atmospheric temperature by 60℃.

[0082] (8) When the atmospheric pressure exceeds 66 kPa, the EGR closed-loop enable condition is allowed; when the atmospheric temperature is below 64 kPa, the EGR closed-loop enable condition needs to be exited.

[0083] If all of the above conditions are met, the EGR system will be enabled in closed loop.

[0084] In this embodiment, the booster response time τ Boost The time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet; turbocharger response time τ. Boost The method obtained through bench calibration is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act Under different EGR rates, the average time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet is obtained through multiple sampling.

[0085] In this embodiment, the time τ for the exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point is... EGR The method obtained through bench calibration is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act The average time taken for exhaust gas to travel from the EGR valve to the EGR exhaust gas confluence point was obtained through multiple samplings under different EGR rates. The EGR exhaust gas confluence point is the location where the EGR exhaust gas merges with fresh air; for details, see [link to documentation]. Figure 1 In this embodiment, the EGR exhaust gas convergence point refers to the location where the EGR exhaust gas and fresh air converge at the outlet of mixing valve 2.

[0086] Specifically, in this embodiment, based on the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR Determine the filter time coefficient k for the target EGR rate T The method is as follows:

[0087]

[0088] Where, k T τ is the filter time coefficient for the target EGR rate. Boost τ is the turbocharger response time. EGR This is the time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas junction point.

[0089] Furthermore, in this embodiment, the filtering time coefficient k is based on the target EGR rate. T Calculate the filter time coefficient k for the target EGR rate T rate of change dk T The method is as follows:

[0090]

[0091] Where Δt is the sampling time, and in this embodiment Δt is 10ms, dk T (z) is the filter time coefficient k of the target EGR rate in the previous sampling period. T rate of change dk T k T (z) represents the filtering time coefficient k of the previous sampling period. T k at the initial time T (z) occurs at the EGR closed-loop enable time, with a default value of 1, and the initial dk T (z) occurs at the EGR closed-loop enable time, and its default value is 0, t c In this embodiment, t is a preset time constant. c Take 0.03s.

[0092] S2, the filtering time is obtained based on the rate of change of the filtering time coefficient and the target EGR rate.

[0093] Specifically, in this embodiment, based on the filtering time learning coefficient r T The filter time coefficient k of the target EGR rate T rate of change dk T The method for obtaining the filtering time is as follows:

[0094] T = f(dk) T )×(1+r T );

[0095] Where T is the filtering time; r T The filtering time learning coefficients can be saved after the vehicle is powered off and can be continuously learned and updated during vehicle operation; their default value is 0; f(dk) T ) represents the default time for filtering time T, f(dk) T The value is determined by the filter time coefficient k of the target EGR rate. T rate of change dkT The decision is made in the table below:

[0096]

[0097] Specifically: when dk T When <-200, f(dk) T ) = 0.15s; when dk T When >200, f(dk) T ) = 0.18s; when -200 ≤ dk T When <-100, f(dk) T ) = 0.12s; when -100 ≤ dk T When <-50, f(dk) T ) = 0.1s; when -50 ≤ dk T When <-10, f(dk) T ) = 0.05s; when -10 ≤ dk T When < 0, f(dk) T ) = 0.01s; when 0 ≤ dk T When <10, f(dk) T ) = 0.05s; when 10 ≤ dk T When <50, f(dk) T ) = 0.12s; when 50 ≤ dk T When <100, f(dk) T ) = 0.16s; when 100 ≤ dk T When <200, f(dk) T = 0.18s.

[0098] Specifically, in this embodiment, the condition for determining the learning coefficients during the filtering time is:

[0099] (1) The engine speed fluctuation does not exceed the preset value, which is ±15 rpm in this embodiment;

[0100] (2) The actual intake density fluctuation does not exceed the preset value, which is ±20 mgpl in this embodiment;

[0101] (3) EGR system closed-loop enable;

[0102] (4) The difference between the target boost pressure and the system's maximum boost pressure and minimum boost pressure exceeds a preset value, which is 10 kPa in this embodiment;

[0103] (5) The difference between the maximum boost pressure of the system and the target boost pressure exceeds the preset value, which is 10 kPa in this embodiment;

[0104] (6) The engine coolant temperature does not exceed the preset value, which is 100℃ in this embodiment;

[0105] (7) The engine intake air temperature does not exceed the preset value, which is 65°C in this embodiment.

[0106] It is understood that in this embodiment, the filter time learning coefficient has an initial value of 0. After running, the specific method for calculating and updating the target boost pressure, actual boost pressure, target air-fuel ratio, actual air-fuel ratio, target EGR rate, actual EGR rate, updated filtered target EGR rate, cumulative number of high-intensity knocking events in the engine, and catalyst oxygen storage capacity coefficient is as follows: when the time for meeting the filter time learning coefficient judgment condition exceeds a preset time t1, the average value p of the difference between the target boost pressure and the actual boost pressure within time t1 is read. BoostErrAvg The average difference r between the target air-fuel ratio and the actual air-fuel ratio AFRErrAvg The average difference r between the updated filtered target EGR rate and the actual EGR rate EGRErrAvg The average target EGR rate r after filtering EGRDsrdFilterAvg Target EGR rate average r EGRDsrdRawAvg The cumulative number of high-intensity knock events in the engine (Cnt) Knock ; Catalyst oxygen storage capacity coefficient r CatalystOxygen The method for obtaining the target EGR rate is described in patent publication CN112459910A, entitled "A Method and System for Calculating the Target EGR Rate"; the method for obtaining the actual EGR rate is existing technology; and the cumulative number of high-intensity knock events (Cnt) of the engine is mentioned. Knock For the method of obtaining the octane number, please refer to the patent with publication number CN111878279A, "A method and system for self-learning the octane number of oil products". For the method of reading the oxygen storage capacity of the catalytic converter, please refer to the patent with publication number CN110259553A, "A method, device and electronic equipment for calculating the oxygen storage capacity of a three-way catalytic converter". For the method of reading the maximum oxygen storage capacity of the catalytic converter, please refer to the patent with publication number CN104594986A, "A method for diagnosing engine catalytic converter deterioration".

[0107] Obtain the learning coefficients r during the filtering time T The specific methods are as follows:

[0108] First scenario: If the average target EGR rate after the update and filtering is r EGRDsrdFilterAvg Greater than the average target EGR rate r EGRDsrdRawAvg If the value exceeds the preset value (0.05 in this embodiment), it indicates that the EGR rate is decreasing. Therefore, the following conditions are applied sequentially: first, second, third, fourth, and fifth, to determine the filtering time learning coefficient r. T Calculate and update:

[0109] First condition: If the cumulative number of high-intensity knock events is CntKnock ≥CNT1, where CNT1 is a preset value. In this embodiment, CNT1 is 5, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value. In this embodiment, p1 is taken as 4 kPa, then r T =r T (z)+0.02, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0110] Second condition: If the cumulative number of high-intensity knock events is Cnt Knock ≥CNT1, where CNT1 is a preset value. In this embodiment, CNT1 is 5, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0111] Third condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg |≤p2, where p2 is a preset value, and in this embodiment p2 is 2kPa, and |r EGRErrAvg |≤0.01, and r CatalystOxygen ≤r C , where r C As a preset value, r in this embodiment C If we take 0.2, then r T =r T (z)-0.03, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0112] Fourth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg |≤p2, where p2 is a preset value, and in this embodiment p2 is 2kPa, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0113] Fifth condition: In other cases, r T =rT (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0114] In particular, it should be noted that the priority of the first, second, third, fourth, and fifth conditions above decreases, that is, if a previous condition is met, only the update result of the previous condition is executed; for example, if the first condition is met, only the update result of the first condition is executed, and the update results of the subsequent conditions are not executed.

[0115] Second scenario: If the target EGR rate averages r EGRDsrdRawAvg Greater than the average target EGR rate r after filtering EGRDsrdFilterAvg If the value exceeds the preset value (0.05 in this embodiment), it indicates that the EGR rate is increasing. Therefore, the following conditions (sixth, seventh, eighth, ninth, and tenth) are applied sequentially to determine the filtering time learning coefficient r. T Calculate and update:

[0116] Sixth condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value. In this embodiment, CNT1 is 5, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value. In this embodiment, p1 is taken as 4 kPa, then r T =r T (z)+0.03, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0117] Seventh condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value. In this embodiment, CNT1 is 5, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0118] Eighth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg |≤p2, where p2 is a preset value, and in this embodiment p2 is 2kPa, and |r EGRErrAvg |≤0.01, and rCatalystOxygen ≤r C , where r C As a preset value, r in this embodiment C If we take 0.2, then r T =r T (z)-0.02, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0119] Ninth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg |≤p2, where p2 is a preset value, and in this embodiment p2 is 2kPa, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0120] Tenth condition: In other cases, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value;

[0121] In particular, it should be noted that the priority of the sixth, seventh, eighth, ninth, and tenth conditions above decreases, that is, if the preceding conditions are met, only the update results of the preceding conditions are executed; for example, if the sixth condition is met, only the update results of the sixth condition are executed, and the update results of the following conditions are not executed.

[0122] Third case: In other cases where neither the first nor the second case is satisfied, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value.

[0123] S3, obtain the filtered target EGR rate based on the filtering time and the target EGR rate.

[0124] Specifically, in this embodiment, the filtered target EGR rate r is obtained based on the filtering time and the target EGR rate. EGRDsrdFilter The method is as follows:

[0125]

[0126] Where, rEGRDsrdFilter (N) represents the target EGR rate r after filtering in the Nth sampling period. EGRDsrdFilter r EGRDsrdFilter (N-1) represents the target EGR rate r after filtering in the N-1th sampling period. EGRDsrdFilter Δt is the sampling time, which is 10ms in this embodiment, and N = 1, 2, 3..., where r EGRDsrdFilter (0) equals 0, which occurs at the moment the vehicle is powered on, r EGRDsrdRaw For the target EGR rate, r EGRDsrdRaw (N) represents the target EGR rate of the Nth sampling period, and T represents the filtering time.

[0127] S4 controls the EGR valve based on the filtered target EGR rate.

[0128] Specifically, in this embodiment, after obtaining the filtered target EGR rate, the EGR valve is actively controlled to make the actual EGR pressure follow the target EGR pressure.

[0129] In summary, the target EGR rate optimization control method provided by this invention can optimize the target EGR rate, improve the impact of EGR entry on engine knocking, and improve engine boost control stability and emission performance.

[0130] It should be noted that, depending on the implementation needs, the various steps described in this application can be broken down into more steps, or two or more steps or parts of the steps can be combined into new steps to achieve the purpose of this invention.

[0131] Those skilled in the art will readily understand 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 within the scope of protection of the present invention.

Claims

1. An optimization control method for a target EGR rate, characterized in that, include: When the EGR system closed-loop enable conditions are met, EGR closed-loop enable is entered. The filter time coefficient of the target EGR rate is determined based on the turbocharger response time and the time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas junction. The rate of change of the filter time coefficient of the target EGR rate is calculated based on the filter time coefficient of the target EGR rate. The filtering time is obtained based on the rate of change of the filtering time learning coefficient and the filtering time coefficient of the target EGR rate; The filtered target EGR rate is obtained based on the filtering time and the target EGR rate. The EGR valve is controlled according to the filtered target EGR rate; The filter time learning coefficient has an initial value, and after operation, it is calculated and updated based on the target boost pressure, actual boost pressure, target air-fuel ratio, actual air-fuel ratio, target EGR rate, actual EGR rate, the updated filtered target EGR rate, the cumulative number of high-intensity knocking events in the engine, and the catalytic converter oxygen storage capacity coefficient. The booster response time τ Boost This is the time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet.

2. The method for optimizing and controlling a target EGR rate according to claim 1, characterized in that, The booster response time τ Boost The method obtained through bench calibration is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act Under different EGR rates, the average time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet is obtained through multiple sampling.

3. The method for optimizing and controlling a target EGR rate according to claim 2, characterized in that, The time τ for the exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point EGR The method obtained through bench calibration is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act Under different EGR rates, the average time taken for exhaust gas to flow from the EGR valve to the EGR exhaust gas confluence point is obtained through multiple samplings; the EGR exhaust gas confluence point refers to the location where the EGR exhaust gas merges with fresh air.

4. The method for optimizing and controlling a target EGR rate according to claim 3, characterized in that, Based on the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction point EGR Determine the filter time coefficient k for the target EGR rate T The method is as follows: Where, k T τ is the filter time coefficient for the target EGR rate. Boost τ is the turbocharger response time. EGR This is the time it takes for the exhaust gas to flow from the EGR valve to the EGR exhaust gas junction point.

5. The method for optimizing and controlling a target EGR rate according to claim 4, characterized in that, Calculate the filter time coefficient k of the target EGR rate T rate of change dk T The method is as follows: Where Δt is the sampling time, dk T (z) is the filter time coefficient k of the target EGR rate in the previous sampling period. T rate of change dk T k T (z) represents the filtering time coefficient k of the previous sampling period. T k at the initial time T (z) occurs at the EGR closed-loop enable time, with a default value of 1, and the initial dk T (z) occurs at the EGR closed-loop enable time, and its default value is 0, t c This is the preset time constant.

6. The method for optimizing and controlling a target EGR rate according to claim 5, characterized in that, Based on the learning coefficient r of the filtering time T and the filter time coefficient k of the target EGR rate T rate of change dk T The method for obtaining the filtering time is as follows: T=f(dk T )×(1+r T ); Where T is the filtering time; r T The filtering time learning coefficients can be saved after the vehicle is powered off and can be continuously learned and updated during vehicle operation; their default value is 0; f(dk) T ) is the default time for the filtering time T, f(dk) T The value is determined by the filter time coefficient k of the target EGR rate. T rate of change dk T The decision, specifically: when dk T When <-200, f(dk) T ) = 0.15s; when dk T When >200, f(dk) T ) = 0.18s; when -200 ≤ dk T When <-100, f(dk) T ) = 0.12s; when -100 ≤ dk T When <-50, f(dk) T ) = 0.1s; when -50 ≤ dk T When <-10, f(dk) T ) = 0.05s; when -10 ≤ dk T When < 0, f(dk) T ) = 0.01s; when 0 ≤ dk T When <10, f(dk) T ) = 0.05s; when 10 ≤ dk T When <50, f(dk) T ) = 0.12s; when 50 ≤ dk T When <100, f(dk) T ) = 0.16s; when 100 ≤ dk T When <200, f(dk) T = 0.18s.

7. The method for optimizing and controlling a target EGR rate according to claim 6, characterized in that, The filter time learning coefficient has an initial value. After operation, it is calculated and updated based on the target boost pressure, actual boost pressure, target air-fuel ratio, actual air-fuel ratio, target EGR rate, actual EGR rate, the updated filtered target EGR rate, the cumulative number of high-intensity knocking events in the engine, and the catalytic converter oxygen storage capacity coefficient. The specific method is as follows: when the time for meeting the filter time learning coefficient judgment condition exceeds a preset time t1, the average difference p between the target boost pressure and the actual boost pressure within time t1 is read. BoostErrAvg The average difference r between the target air-fuel ratio and the actual air-fuel ratio AFRErrAvg The average difference r between the updated filtered target EGR rate and the actual EGR rate EGRErrAvg The average target EGR rate r after filtering EGRDsrdFilterAvg Target EGR rate average r EGRDsrdRawAvg The cumulative number of high-intensity knock events in the engine (Cnt) Knock ; Catalyst oxygen storage capacity coefficient r CatalystOxygen ; Obtain the filtering time learning coefficient r T The method is specifically shown in the following three cases: First scenario: If the average target EGR rate after the update and filtering is r EGRDsrdFilterAvg Greater than the average target EGR rate r EGRDsrdRawAvg If the value exceeds the preset value, it indicates that the EGR rate is decreasing. Therefore, the following conditions—first, second, third, fourth, and fifth—are applied sequentially to determine the filtering time learning coefficient r. T Calculate and update: First condition: If the cumulative number of high-intensity knock events is Cnt Knock ≥CNT1, where CNT1 is a preset value, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value, then r T =r T (z)+0.02, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Second condition: If the cumulative number of high-intensity knock events is Cnt Knock ≥CNT1, where CNT1 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Third condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg |≤0.01, and r CatalystOxygen ≤r C , where r C If it is a preset value, then r T =r T (z)-0.03, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Fourth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Fifth condition: In other cases, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; The priority of the first, second, third, fourth, and fifth conditions above decreases, meaning that if a previous condition is met, only the previous update result will be executed. Second scenario: If the target EGR rate is averaged r EGRDsrdRawAvg Greater than the average target EGR rate r after the update and filtering EGRDsrdFilterAvg If the value exceeds the preset value, it indicates that the EGR rate is increasing. Therefore, the following conditions (sixth, seventh, eighth, ninth, and tenth) are applied sequentially to determine the filtering time learning coefficient r. T Calculate and update: Sixth condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value, and |p BoostErrAvg |≥p1, and|r EGRErrAvg |≤0.01, where p1 is a preset value, then r T =r T (z)+0.03, and Cnt Knock Reset to zero and start counting again, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Seventh condition: If the cumulative number of high-intensity knock events (Cnt) occurs... Knock ≥CNT1, where CNT1 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)+0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Eighth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg |≤0.01, and r CatalystOxygen ≤r C , where r C If r is the default value, then T =r T (z)-0.02, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Ninth condition: If |r AFRErrAvg |≤0.01, and |p BoostErrAvg | ≤ p2, where p2 is a preset value, and |r EGRErrAvg If |≤0.01, then r T =r T (z)-0.01, where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; Tenth condition: In other cases, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value; The priority of the sixth, seventh, eighth, ninth, and tenth conditions above decreases, meaning that if a previous condition is met, only the previous update result will be executed. Third case: In other cases where neither the first case nor the second case is satisfied, r T =r T (z), where r T (z) represents the learning coefficient r of the filter time stored in the last learning update. T Learning value.

8. The method for optimizing and controlling a target EGR rate according to claim 7, characterized in that, The filtered target EGR rate r is obtained based on the filtering time and the target EGR rate. EGRDsrdFilter The method is as follows: Where, r EGRDsrdFilter (N) represents the target EGR rate r after filtering in the Nth sampling period. EGRDsrdFilter r EGRDsrdFilter (N-1) represents the target EGR rate r after filtering in the N-1th sampling period. EGRDsrdFilter Δt is the sampling time, N = 1, 2, 3…, where r EGRDsrdFilter (0) equals 0, which occurs at the moment the vehicle is powered on, r EGRDsrdRaw Let r be the target EGR rate. EGRDsrdRaw (N) represents the target EGR rate of the Nth sampling period, and T represents the filtering time.

9. The method for optimizing and controlling a target EGR rate according to claim 7, characterized in that, The criteria for determining the filtering time learning coefficients are as follows: (1) Engine speed fluctuation does not exceed the preset value; (2) The actual intake air density fluctuation does not exceed the preset value; (3) EGR system closed-loop enable; (4) The difference between the target boost pressure and the system's maximum boost pressure and minimum boost pressure exceeds the preset value; (5) The difference between the system's maximum boost pressure and the target boost pressure exceeds the preset value; (6) The engine coolant temperature does not exceed the preset value; (7) The engine intake air temperature does not exceed the preset value.

10. The optimization control method for a target EGR rate according to claim 1, characterized in that, The closed-loop enable condition for the EGR system is: (1) No related faults were found in any of the components of the EGR system; (2) No fuel cut-off request was received or the fuel cut-off recovery time exceeded the preset time; (3) The updated filtered target EGR rate is not less than the minimum EGR rate; (4) The engine speed is within the preset speed range; (5) The intake air temperature is within the preset range; (6) The engine coolant temperature is within the preset range; (7) The atmospheric temperature is within the preset range; (8) When the atmospheric pressure exceeds 66 kPa, the EGR closed-loop enable condition is allowed; when the atmospheric temperature is below 64 kPa, the EGR closed-loop enable condition needs to be exited.

11. The optimization control method for a target EGR rate according to claim 10, characterized in that, The intake air temperature within the preset range specifically includes: if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the intake air temperature is not lower than the minimum intake air temperature by 10°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the intake air temperature is lower than the minimum intake air temperature by 7°C; if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the intake air temperature does not exceed the maximum intake air temperature by 60°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the intake air temperature exceeds the maximum intake air temperature by 65°C.

12. The method for optimizing and controlling a target EGR rate according to claim 10, characterized in that, The engine coolant temperature within the preset range specifically includes: if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the coolant temperature is not lower than the minimum coolant temperature of 60℃; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the coolant temperature is lower than the minimum coolant temperature of 55℃; if the current state is EGR closed-loop not enabled, then entering the EGR closed-loop state requires ensuring that the coolant temperature does not exceed the maximum coolant temperature of 115℃; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the coolant temperature exceeds the maximum coolant temperature of 120℃.

13. The optimization control method for a target EGR rate according to claim 10, characterized in that, The atmospheric temperature within the preset range specifically includes: if the current state is EGR closed-loop disabled, then entering the EGR closed-loop state requires ensuring that the temperature is not lower than the minimum atmospheric temperature by 5°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the temperature is lower than the minimum atmospheric temperature by 3°C; if the current state is EGR closed-loop disabled, then entering the EGR closed-loop state requires ensuring that the temperature does not exceed the maximum atmospheric temperature by 55°C; if the current state is EGR closed-loop enabled, then exiting the EGR system closed-loop enabled state requires ensuring that the temperature exceeds the maximum atmospheric temperature by 60°C.

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