EGR (Exhaust Gas Recirculation) control method and system after system level fault

Abstract

The invention provides an EGR control method and system after a system level fault, and belongs to the technical field of engine exhaust gas recirculation rate control. According to the method, after it is detected that an engine has the system level fault under the non-idling working condition, EGR rate filtering time and EGR rate variable quantity are obtained, and a corrected target EGR rate is determined according to the EGR rate filtering time and the EGR rate variable quantity; and EGR control is conducted according to the corrected target EGR rate. According to the method, the EGR rate control stability, the engine dynamic property, the emission and the engine service life after a complex system-level fault occurs can be improved, and the EGR rate is optimized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine exhaust gas recirculation rate control, and particularly relates to an EGR control method and system after system level failure. BACKGROUND

[0002] Exhaust gas recirculation (EGR) takes exhaust gas from the exhaust system into the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock capacity. Low pressure EGR takes gas after the turbine, so there is no loss of turbine efficiency, and it can use EGR under almost all working conditions, which is more significant for improving fuel efficiency. However, due to the low pressure difference, a large-diameter valve is needed to meet the flow requirements. In some working conditions, the opening of the mixing valve needs to be controlled to adjust the pressure at the outlet of the EGR valve, thereby improving the pressure difference on both sides of the EGR valve and improving the EGR rate. If the system level failure occurs after the idle condition, the engine EGR rate control stability, engine power, emissions and engine life will be deteriorated if the target EGR rate before the failure is still controlled. SUMMARY

[0003] The present application aims to solve at least one of the technical problems existing in the prior art, and provides an EGR control method and system after system level failure.

[0004] In a first aspect, an EGR control method after system level failure is provided, comprising the following steps:

[0005] S100, after detecting that the engine has a system level failure in a non-idle condition, obtaining an EGR rate filtering time and an EGR rate change amount, and determining a corrected target EGR rate according to the EGR rate filtering time and the EGR rate change amount;

[0006] S200, performing EGR control according to the corrected target EGR rate.

[0007] Further, the system level failure is an intake manifold leakage failure or a supercharging system failure.

[0008] Further, the corrected target EGR rate is determined according to the following formula:

[0009]

[0010] wherein, is the corrected target EGR rate in the N+1th sampling period; is the corrected target EGR rate in the Nth sampling period, N=0, 1, 2, 3, 4…; is the sampling period; ​is the EGR rate filtering time; is the EGR rate change.

[0011] Furthermore, the EGR rate filter time The way to obtain is as follows:

[0012] 1) If the engine boost mode is activated, that is, the boost closed loop is enabled, then

[0013]

[0014] in, is the first filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate, is the EGR system correction coefficient, is the intake system correction factor, is the default correction factor.

[0015] Furthermore, the EGR rate filter time The way to obtain is as follows:

[0016] 2) If the engine boost mode is not activated, then

[0017]

[0018] in, It is a second filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate.

[0019] Furthermore, the EGR system correction factor ,in Based on the EGR valve inlet temperature The correction factor, is the correction factor based on the engine cooling water temperature, is a correction factor based on the fan's operating status.

[0020] Furthermore, 1) when the throttle is fully open, ,in is the correction factor based on the intake air temperature at the outlet downstream of the throttle valve.

[0021] Furthermore, 2) when the throttle is not fully open, ,in It refers to the default coefficient of the intake system when the throttle valve is not fully open.

[0022] Furthermore, ,in is the coefficient based on the catalyst light-off state, is a coefficient based on the GPF regeneration state.

[0023] Further, the EGR rate change amount is obtained in the following manner:

[0024]

[0025] wherein, is a first change amount base value based on the EGR rate deviation and the EGR rate deviation change rate, is a second change amount base value based on the EGR rate deviation and the intake and exhaust valve pressure ratio, is a third change amount base value based on the ignition path torque difference and the ignition angle efficiency, is a fourth change amount base value based on the retarded ignition angle and the octane number coefficient, is a self-learning correction coefficient of the EGR rate change amount .

[0026] Further, the self-learning correction coefficient is obtained in the following manner:

[0027] According to the supercharging performance, three kinds of supercharging performance are classified:

[0028] 1) Supercharging performance one: the absolute value of the supercharging pressure difference is greater than a preset value 5 kPa for a continuous time T1, is the difference between the target supercharging pressure and the actual supercharging pressure;

[0029] 2) Supercharging performance two: the absolute value of the supercharging pressure difference is greater than a preset value 3 kPa for a continuous time T2;

[0030] 3) Supercharging performance three: other cases, supercharging performance is good;

[0031] According to the engine ignition path torque performance, three kinds of supercharging performance are classified:

[0032] 1) Ignition path torque performance one: the difference between the engine requested ignition path torque and the engine actual ignition path torque is greater than a preset value 10 Nm for a continuous time T3;

[0033] 2) Ignition path torque performance two: the difference between the engine requested ignition path torque and the engine actual ignition path torque is greater than a preset value 8 Nm for a continuous time T4;

[0034] 3) Ignition path torque performance three: other cases, ignition path torque performance is good;

[0035] If the following occurs at the time of failure:

[0036] 1) If supercharging performance one and ignition path torque performance three occur, then , is the last time learning update learning value;

[0037] 2) If the supercharging performance one and the fire path torque performance two appear, then ;

[0038] 3) If the supercharging performance one and the fire path torque performance one appear, then .

[0039] Further, 4) if the supercharging performance two and the fire path torque performance three appear, then ;

[0040] 5) If the supercharging performance two and the fire path torque performance two appear, then ;

[0041] 6) If the supercharging performance two and the fire path torque performance one appear, then .

[0042] Further, 7) if the supercharging performance three and the fire path torque performance three appear, then ;

[0043] 8) If the supercharging performance three and the fire path torque performance two appear, then ;

[0044] 9) If the supercharging performance three and the fire path torque performance one appear, then .

[0045] Further, 10) in other cases, .

[0046] In a second aspect, an embodiment of the present application provides an EGR control system after system-level failure, comprising:

[0047] A determination module is configured to, after detecting that the engine occurs system-level failure in a non-idling working condition, acquire an EGR rate filtering time and an EGR rate change amount, and determine a corrected target EGR rate according to the EGR rate filtering time and the EGR rate change amount;

[0048] A control module is configured to perform EGR control according to the corrected target EGR rate.

[0049] The system level fault post-EGR control method and system provided by the application, after detecting that the engine occurs a system level fault under a non-idling working condition, the EGR rate filtering time and the EGR rate change amount are acquired, the corrected target EGR rate is determined according to the EGR rate filtering time and the EGR rate change amount, and the EGR control is performed according to the corrected target EGR rate, so that the EGR rate control stability, the engine power, the emission and the engine life after the complex system level fault occurs are optimized. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A schematic diagram of the structure of a turbocharged engine including exhaust gas recirculation;

[0051] Figure 2 A flowchart of a system level fault post-EGR control method provided by an embodiment of the application;

[0052] Figure 3 A block diagram of a system level fault post-EGR control system provided by an embodiment of the application.

[0053] The reference signs, 1, air filter; 2, mixing valve; 3, compressor; 4, throttle valve; 5, engine; 6, turbine; 7, catalytic converter; 8, particulate trap; 9, EGR cooler; 10, EGR valve; 11, temperature sensor; 12, differential pressure sensor. DETAILED DESCRIPTION

[0054] In order for those skilled in the art to better understand the technical solutions of the present application, the exemplary embodiments of the present application are described below in conjunction with the accompanying drawings, which include various details of the embodiments of the present application to help understanding, and should be considered only as exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Also, in order to be clear and concise, the description in the following description omits the description of well-known functions and structures.

[0055] In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0056] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Coupled" or "connected" or similar terms are not restricted to physical or mechanical connections or relationships.

[0058] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0059] Figure 1 For the structure diagram of turbocharged engine including exhaust gas recirculation, including: air filter 1; connecting air filter 1's mixing valve 2, for adjusting the pressure of EGR valve 10 outlet, increasing the pressure difference between the two ends of EGR valve 10, two gas flow paths extend from mixing valve 2; connecting one of the gas flow paths of mixing valve 2's compressor 3; connecting compressor 3's throttle valve 4, wherein the inlet of throttle valve 4 has a boost temperature sensor, a boost pressure sensor, the outlet of throttle valve 4 has an intake temperature sensor, an intake pressure sensor, the body of throttle valve has a position sensor and an actuator (not shown in the figure); connecting throttle valve 4's engine 5, for compressing fresh air to boost pressure; connecting engine 5's turbine 6, for controlling the opening degree of exhaust gas bypass valve; connecting turbine 6's catalytic converter 7; connecting catalytic converter 7's particulate matter trap 8. EGR cooler 9 is installed on the other gas flow path of mixing valve 2, for receiving the exhaust gas output by particulate matter trap 8 and cooling, increasing the exhaust gas flow; EGR valve 10 is connected at one end of EGR cooler 9 and connected at the other end of mixing valve 2, for controlling the exhaust gas flow into the cylinder; temperature sensor 11 is installed between EGR valve 10 and EGR cooler 9, for detecting the temperature of exhaust gas entering EGR valve 10; differential pressure sensor 12 is connected to EGR valve 10, for detecting the pressure at the inlet and outlet of EGR valve 10.

[0060] The present application provides a system-level post-fault EGR control method. Figure 2 A system-level post-fault EGR control method is provided for the embodiment of the present application, and the flowchart of the method comprises the following steps:

[0061] S100、detecting that the engine occurs a system level fault in a non-idle operating condition, obtaining an EGR rate filtering time and an EGR rate change amount, and determining a corrected target EGR rate according to the EGR rate filtering time and the EGR rate change amount.

[0062] The present application proposes an EGR control method after a system level fault, mainly to solve the engine fault, but not the engine component level fault, that is, not the fault of a certain component or components, but the fault of the system level related, such as the intake manifold leakage fault mentioned in the patent CN202310578963.9 "intake manifold leakage detection and post-processing method, device, equipment and storage medium", or the supercharging system fault mentioned in CN202311285223.2 "supercharging system capacity fault detection method".

[0063] Once the above fault occurs, if the engine is in an idle operating condition, the patent CN202211528641.5 "target EGR rate control method in idle operating condition" is still maintained for control.

[0064] Suppose the target EGR rate before the fault is which can be determined by the prior art CN202011247319.6 "a method and system for calculating target EGR rate".

[0065] In one embodiment, the corrected target EGR rate is determined by the following formula:

[0066]

[0067] Wherein, is the corrected target EGR rate in the N+1th sampling period; is the corrected target EGR rate in the Nth sampling period, N=0,1,2,3,4…; is the sampling period, which is 10ms in this example; is the EGR rate filtering time; is the EGR rate change amount.

[0068] In particular, The moment of occurrence, 1) if the last sampling period is that the engine is in an idle operating condition, the occurrence moment is the first operating condition when the engine enters from idle to non-idle, at this time the target EGR rate = the target EGR rate in the sampling period corresponding to the last moment of idle; 2) if it is not the first case, but the fault occurs before the engine starts, at this time the target EGR rate = = 0; 3) if the engine start-up after the malfunction occurs is not the above two cases, the target EGR rate = is the original target EGR rate at the current corresponding time .

[0069] In one embodiment, the EGR rate filtering time is obtained as follows:

[0070] 1) if the engine supercharging condition is activated, i.e., the supercharging closed loop is enabled, then

[0071]

[0072] 2) if the engine supercharging condition is not activated, then

[0073]

[0074] wherein, is a first filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate, is a second filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate, is an EGR system correction coefficient, is an intake system correction coefficient, is a default correction coefficient.

[0075] The EGR system correction coefficient wherein, is a correction coefficient based on the EGR valve inlet temperature , when the EGR inlet temperature is too low or too high, the EGR rate control stability is easily deteriorated, therefore is larger. The correction coefficient based on the EGR valve inlet temperature is determined by querying the EGR valve inlet temperature corresponding value through the following table.

[0076] Table 1 Corresponding relationship between the correction coefficient based on the EGR valve inlet temperature and the EGR valve inlet temperature

[0077] #timg# (°C) -30 -25 -20 -10 0 65 70 75 80 #timg# 1.25 1.2 1.1 1.05 1 1 1.1 1.2 1.3

[0078] wherein, is a correction coefficient based on the engine cooling water temperature, when the cooling water temperature is very high, it is easy to cause the influence of knock, based on this, at this time is smaller, and the risk of reducing the EGR rate to improve knock is rapidly improved. The correction coefficient based on the engine cooling water temperature is determined by querying the engine cooling water temperature corresponding value through the following table.

[0079] Table 2: Correspondence between correction coefficient based on engine cooling water temperature and engine cooling water temperature

[0080] #timg# (°C) 25 40 65 80 90 100 110 115 120 #timg# 1 0.99 0.98 0.96 0.95 0.9 0.8 0.72 0.6

[0081] wherein is a correction coefficient based on fan deployment state wherein is 0 representing fan not on, is 1 representing low speed fan on, is 2 representing high speed fan on. Note that the cooling fan of the whole vehicle only has these three states. The faster the fan is on, the more the engine cooling water temperature needs to be reduced to improve the engine life, and thus the shorter the filter time of the EGR rate. The correction coefficient based on fan deployment state is determined by looking up the fan deployment state corresponding value in the following table.

[0082] Table 3: Correspondence between correction coefficient based on fan deployment state and fan deployment state

[0083] #timg# 0 1 2 #timg# 1 0.95 0.8

[0084] Intake system correction coefficient

[0085] 1) When the throttle is fully open (the difference between the throttle inlet and outlet pressures is not more than ±0.01 kPa), wherein is a correction coefficient based on throttle downstream outlet intake temperature, when the throttle downstream outlet intake temperature is very high and is easy to cause the influence of knock, based on this, the smaller at this time, the faster the improvement of the EGR rate reduces the risk of knock. The correction coefficient based on throttle downstream outlet intake temperature is determined by looking up the throttle downstream outlet intake temperature corresponding value in the following table.

[0086] Table 4: Correspondence between correction coefficient based on throttle downstream outlet intake temperature and throttle downstream outlet intake temperature

[0087] #timg# (°C) 20 30 35 40 50 55 60 65 70 #timg# 1.1 1.06 1.04 1.02 1 0.95 0.92 0.85 0.78

[0088] 2) When the throttle is not fully open, wherein means that when the throttle is not fully open, the stability of the throttle to the control of the intake mixture is high, at this time, the delay control of the EGR rate can be reduced, this example takes 0.8.

[0089] Default correction coefficient​ Based on the catalyst light-off state The coefficient of , based on GPF regeneration status The coefficient of Joint decision, If the catalyst is in the light-off state, then is 1, otherwise it is 0. If the GPF is in active regeneration state, then =1, otherwise 0. Based on the catalyst light-off state The coefficient of Check the catalytic converter ignition status through the table below The corresponding value is determined based on the GPF regeneration status The coefficient of Check the GPF regeneration status through the following table The corresponding value is determined.

[0090] Table 5 Correspondence between the coefficient based on the catalyst ignition state and the catalyst ignition state

[0091] #timg# 0 1 #timg# 1 0.8

[0092] Table 6 Correspondence between coefficients based on GPF regeneration status and GPF regeneration status

[0093] #timg# 0 1 #timg# 1 0.72

[0094] and The EGR rate deviations in the previous M sampling cycles (the target EGR rate in the previous sampling cycle) Compared with the actual EGR rate in the previous sampling period The minimum value of the difference Deviation from EGR rate Rate of change The experimental test data shows that taking M as 3, that is, considering the EGR rate control accuracy (EGR rate deviation and its change rate) of the first 3 times as the control object can optimize the improvement of EGR rate control accuracy. The larger M is, the slower the system control and the worse the control accuracy; the smaller M is, the worse the control robustness. or The larger the absolute value, the and The smaller it is, the shorter the filter time of EGR rate control is when the deviation or deviation change rate is larger, so as to improve the deviation as soon as possible; the longer the filter time of EGR rate control is when the deviation or deviation change rate is smaller, so as to improve the control robustness. The optimal data value is obtained based on the test time calibration to meet the EGR rate control requirements. The EGR rate control requirements can be determined by the OEM. and below, not less than , considering that the supercharging control accuracy is to be given priority in the supercharging control activation state, the EGR system is regulated more slowly than when the supercharging control is not activated, and the greater the filtering time is.

[0095] In one embodiment, the EGR rate change amount is obtained as follows:

[0096]

[0097] wherein, is a first change amount base value based on the EGR rate deviation and the EGR rate deviation change rate, is a second change amount base value based on the EGR rate deviation and the mixed valve inlet and outlet pressure ratio, is a third change amount base value based on the firing path torque difference and the ignition angle efficiency, is a fourth change amount base value based on the retarded ignition angle and the octane value coefficient, is a self-learning correction coefficient of the EGR rate change amount .

[0098] The first change amount base value based on the EGR rate deviation and the EGR rate deviation change rate is determined based on and , and in or is greater, the is greater, and the target EGR rate is reduced to reduce the EGR rate deviation and improve the control robustness. The second change amount base value based on the EGR rate deviation and the mixed valve inlet and outlet pressure ratio is determined by and the ratio of the mixed valve outlet pressure to the inlet pressure , and in is greater, and is smaller, the likelihood of reducing the EGR rate deviation by regulating the mixed valve is greater at this time, and the EGR rate deviation is also greater at this time, so the EGR rate change can be increased to quickly remind the performance advantage of the EGR, and is smaller.

[0099] The third change amount base value based on the firing path torque difference and the ignition angle efficiency is determined based on the difference between the engine requested firing path torque and the engine actual firing path torque and the engine actual ignition angle efficiency . In is greater, and is smaller, the The smaller, the more the engine power is improved by the advantage of EGR.

[0100] The fourth change amount of the base value of the ignition delay angle and the octane number coefficient is determined based on the ignition delay angle after engine knock and the octane number coefficient of the fuel together, the greater or the smaller, in order to protect the engine, the greater, the engine life is improved by the advantage of EGR.

[0101] The above calibration is based on the engine power and engine life protection and EGR system control accuracy requirements after the failure occurs.

[0102] The self-learning correction coefficient of the EGR rate change amount , the default value is 0, which can be continuously self-learned and updated, and can be saved after the vehicle is powered off.

[0103] The self-learning correction coefficient The self-learning method is as follows:

[0104] According to the performance of the supercharging performance, three kinds of supercharging performance are divided:

[0105] 1) Supercharging performance one: the absolute value of the supercharging pressure difference appears greater than the preset value 5kPa within the continuous time T1 (0.5s in this example), is the difference between the target supercharging pressure and the actual supercharging pressure;

[0106] 2) Supercharging performance two: the absolute value of the supercharging pressure difference appears greater than the preset value 3kPa within the continuous time T2 (0.8s in this example);

[0107] 3) Supercharging performance three: other cases, the supercharging performance is good.

[0108] According to the engine fire road torque performance, three kinds of supercharging performance are divided:

[0109] 1) Fire road torque performance one: the difference between the engine request fire road torque and the actual engine fire road torque appears greater than the preset value 10Nm within the continuous time T3 (0.1s in this example);

[0110] 2) Fire road torque performance two: the difference between the engine request fire road torque and the actual engine fire road torque appears greater than the preset value 8Nm within the continuous time T4 (0.2s in this example);

[0111] 3) Fire path torque performance three: other cases, fire path torque performance is good.

[0112] If the following occurs at the time of failure:

[0113] 1) If boost performance one and fire path torque performance three occur, then , is the last learning update learning value;

[0114] 2) If boost performance one and fire path torque performance two occur, then ;

[0115] 3) If boost performance one and fire path torque performance one occur, then ;

[0116] 4) If boost performance two and fire path torque performance three occur, then ;

[0117] 5) If boost performance two and fire path torque performance two occur, then ;

[0118] 6) If boost performance two and fire path torque performance one occur, then ;

[0119] 7) If boost performance three and fire path torque performance three occur, then ;

[0120] 8) If boost performance three and fire path torque performance two occur, then ;

[0121] 9) If boost performance three and fire path torque performance one occur, then ;

[0122] 10) Other cases, .

[0123] S200, EGR control is performed according to the corrected target EGR rate.

[0124] The embodiment of the application can improve the EGR rate control stability, engine power, emission, and engine life optimization after the occurrence of complex system level failure.

[0125] The application also provides an EGR control system after system level failure. Figure 3 A structural block diagram of an EGR control system after system level failure is provided for the embodiment of the application, and the system comprises:

[0126] The determining module 11 is configured to, after detecting that the system-level fault occurs in the non-idling working condition of the engine, acquire an EGR rate filtering time and an EGR rate change amount, and determine a corrected target EGR rate according to the EGR rate filtering time and the EGR rate change amount.

[0127] The control module 12 is configured to perform EGR control according to the corrected target EGR rate.

[0128] Example embodiments have been disclosed herein and, although the specific terms are employed, they are used in a generic sense only and should not be construed to be limited to the specific embodiments described herein. In some instances, those skilled in the art will appreciate that features, aspects and / or elements described herein with respect to one particular embodiment can be used singularly, in combination with other embodiments, or in combination with other aspects described herein, unless expressly stated otherwise. Therefore, those skilled in the art will recognize that the spirit and scope of the present application are spelled out fully by the following claims.

Claims

1. A system-level post-fault EGR control method, characterized in that: The following steps are involved: S100, after detecting a system-level fault in the engine under a non-idle operating condition, obtaining an EGR rate filter time and an EGR rate change, and determining a corrected target EGR rate based on the EGR rate filter time and the EGR rate change; S200: Perform EGR control according to the corrected target EGR rate.

2. The method according to claim 1, characterized in that The system-level fault is an intake manifold leakage fault or a boost system fault.

3. The method according to claim 2, characterized in that Corrected target EGR rate The formula for determining is as follows: in, is the corrected target EGR rate in the N+1th sampling period; is the corrected target EGR rate in the Nth sampling period, N=0,1,2,3,4…; is the sampling period; is the EGR rate filtering time; is the EGR rate change.

4. The method according to claim 3, characterized in that EGR rate filter time The way to obtain is as follows: 1) If the engine boost mode is activated, that is, the boost closed loop is enabled, then in, is the first filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate, is the EGR system correction coefficient, is the intake system correction factor, is the default correction factor.

5. The method according to claim 4, characterized in that EGR rate filter time The way to obtain is as follows: 2) If the engine boost mode is not activated, then in, It is a second filtering time base value based on the EGR rate deviation and the EGR rate deviation change rate.

6. The method according to claim 5, characterized in that EGR system correction factor ,in Based on the EGR valve inlet temperature The correction factor, is the correction factor based on the engine cooling water temperature, is a correction factor based on the fan's operating status.

7. The method according to claim 6, characterized in that 1) When the throttle is fully open, ,in is the correction factor based on the intake air temperature at the downstream outlet of the throttle valve.

8. The method according to claim 7, characterized in that 2) When the throttle is not fully open, ,in It refers to the default coefficient of the intake system when the throttle valve is not fully open.

9. The method according to claim 8, characterized in that ,in is the coefficient based on the catalyst light-off state, is a coefficient based on the GPF regeneration state.

10. The method according to claim 9, characterized in that EGR rate change The way to obtain is as follows: in, is a first variation base value based on the EGR rate deviation and the EGR rate deviation variation rate, is the second variation base value based on the EGR rate deviation and the mixing valve inlet and outlet pressure ratio, is the third variation base value based on the fire-circuit torque difference and the ignition angle efficiency, is a fourth variation base value based on the retarded ignition angle and the octane number coefficient, EGR rate change The self-learning correction coefficient.

11. The method according to claim 10, characterized in that Self-learning correction coefficient The self-learning method is as follows: According to the boost performance, there are three types of boost performance: 1) Boost performance 1: Absolute value of boost pressure difference The value is greater than the preset value 5kPa for the continuous time T1. The difference between the target boost pressure and the actual boost pressure; 2) Boost performance 2: Absolute value of boost pressure difference The pressure is greater than the preset value of 3kPa for a continuous period of time T2; 3) Boosting performance three: In other cases, boosting performance is good; According to the engine fire circuit torque performance, three types of boost performance are divided: 1) Fire-circuit torque performance 1: The difference between the engine's requested fire-circuit torque and the engine's actual fire-circuit torque The pressure is greater than the preset value of 10Nm for a continuous period of time T3; 2) Fire-circuit torque performance 2: The difference between the engine's requested fire-circuit torque and the engine's actual fire-circuit torque The force is greater than the preset value of 8Nm for a continuous period of time T4; 3) Fire circuit torque performance three: In other cases, the fire circuit torque performance is good; If the following appears when a fault occurs: 1) If the boost performance is 1 and the fire torque performance is 3, then , The learning value updated for the last learning; 2) If the boost performance is 1 and the fire torque performance is 2, then ; 3) If the boost performance is 1 and the fire torque performance is 1, then .

12. The method according to claim 11, characterized in that 4) If the boost performance is 2 and the fire torque performance is 3, then ; 5) If the boost performance is 2 and the fire torque performance is 2, then ; 6) If the boost performance is 2 and the fire torque performance is 1, then .

13. The method according to claim 12, characterized in that 7) If the boost performance is 3 and the fire torque performance is 3, then ; 8) If the boost performance is 3 and the fire torque performance is 2, then ; 9) If the boost performance is 3 and the fire torque performance is 1, then .

14. The method according to claim 13, characterized in that 10) In other cases, .

15. A system-level post-fault EGR control system, characterized in that: include: A determination module is used to detect a system-level fault of the engine under non-idle conditions, obtain an EGR rate filtering time and an EGR rate variation, and determine a corrected target EGR rate based on the EGR rate filtering time and the EGR rate variation; The control module is configured to perform EGR control according to the corrected target EGR rate.

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