EGR (Exhaust Gas Recirculation) control method and system after ignition system failure

Abstract

The invention provides an EGR (Exhaust Gas Recirculation) control method and system after an ignition system fails, and belongs to the technical field of engine exhaust gas recirculation rate control. According to the method, the ignition system is detected, and after it is detected that at least one part fails, the corrected target EGR rate after the various parts fail is determined; and the minimum value of the corrected target EGR rate after all the parts break down is obtained, the final target EGR rate is obtained, the final target EGR rate is limited to be not larger than the target EGR rate before the fault, and EGR control is conducted according to the final target EGR rate. According to the method, the possibility of engine knock occurring after the knock sensor breaks down can be effectively improved, and meanwhile the influence on emission, the dynamic property and oil consumption is avoided.

Description

Technical Field

[0001] This invention relates to the field of engine exhaust gas recirculation rate control technology, and in particular to an EGR control method and system after a fuel injection system failure. Background Technology

[0002] Exhaust gas recirculation (EGR) draws exhaust gas from the exhaust system and introduces it into the intake system. Studies have shown that EGR systems have certain advantages in improving emissions, reducing fuel consumption, and improving anti-knock capabilities. Low-pressure EGR, unlike high-pressure EGR, draws gas after the turbine, thus avoiding turbine efficiency loss. It can be used almost under all operating conditions, resulting in a more significant improvement in fuel efficiency. However, due to its low pressure differential, a large-diameter valve is required to meet the flow requirements. Under certain operating conditions, it is also necessary to control the opening of the mixing valve to adjust the pressure at the EGR valve outlet, thereby increasing the pressure difference across the EGR valve and improving the EGR rate.

[0003] The existing technology CN111852719A, "Ignition Angle Control Method, System, and Readable Storage Medium," relates to ignition angle control. However, this patent first determines whether the engine has entered a pre-set drivability-sensitive zone. If so, it further determines whether the jump in the theoretical knock delay ignition angle of the next ignition cylinder relative to the actual knock delay ignition angle of the current ignition cylinder exceeds a preset threshold. If so, it needs to limit the ignition angle jump by shifting the actual knock delay ignition angle of the current ignition cylinder toward the theoretical knock delay ignition angle of the next ignition cylinder by an offset amount. However, this existing technology does not propose how to adjust the EGR rate after an ignition system-related fault occurs.

[0004] The existing technology CN103557107A, "A Method for Correcting Ignition Angle under Enrichment Conditions in a Gasoline Engine," relates to ignition angle control under exhaust temperature protection. This includes the ECU looking up the corresponding ignition angle data at the given engine speed and mixture concentration in the enrichment ignition angle correction logic control table when the gasoline engine enriches the mixture to reduce exhaust temperature. This data is then added to the basic ignition angle to obtain the actual ignition angle output by the ECU to the engine. However, this existing technology does not address how to adjust the EGR rate after an ignition system-related fault occurs. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an EGR control method and system after ignition system failure.

[0006] In a first aspect, embodiments of the present invention provide an EGR control method after an ignition system failure, comprising the following steps:

[0007] S100. Inspect the ignition system. If at least one component fails, determine the corrected target EGR rate after each component fails.

[0008] S200: Take the minimum value of the corrected target EGR rate after all components fail to obtain the final target EGR rate, and limit the final target EGR rate to not exceed the target EGR rate before the failure. Perform EGR control based on the final target EGR rate.

[0009] Furthermore, the ignition system includes components such as an ignition coil and a knock sensor.

[0010] Further, in step S100, 1) if an ignition coil fault is detected: the target EGR rate after forced control correction. .

[0011] Furthermore, 2) If a knock sensor malfunction is detected:

[0012] 2.1) Determine the transient operating coefficients of the engine. ;

[0013] 2.2) Based on transient operating condition coefficients The corrected target EGR rate is obtained by determining the target EGR rate before the failure.

[0014] Furthermore, based on the transient operating condition coefficient The formula for calculating the corrected target EGR rate, obtained from the pre-fault target EGR rate determination, is as follows:

[0015]

[0016] in This is the speed-load correction factor. For engine coolant temperature correction factor, This is the intake air temperature correction factor. This is the ignition efficiency correction factor based on rotational speed. The self-learning correction coefficient for the target EGR rate.

[0017] Furthermore, when the conditions for self-learning are met,

[0018] 1) If the exhaust temperature exceeds the first preset temperature T1 for a continuous period of time exceeding t1, ,in The first default preset temperature, Let be the self-learning coefficients for the first row of temperature thresholds, then we have ,in The learned values ​​stored from the previous learning session.

[0019] Furthermore, 2) if the exhaust temperature exceeds the second preset temperature T2 for a continuous period of time exceeding t2, ,in The second default preset temperature. Let be the self-learning coefficient for the second row temperature threshold, then we have .

[0020] Furthermore, 3) if the number of driving cycles CNT1 in which the exhaust temperature does not exceed the third preset temperature T3 continuously exceeds the preset value of the first cycle number, ,in The third default preset temperature. Let T3 be the self-learning coefficient for the third row temperature threshold. Then we have: The driving cycle count CNT1 will be reset to zero and will be incremented again once subsequent conditions are met.

[0021] Furthermore, 4) if the number of driving cycles CNT2 in which the exhaust temperature does not exceed the fourth preset temperature T4 exceeds the second preset cycle number, ,in The fourth default preset temperature. Let T4 be the self-learning coefficient for the fourth preset temperature. Then we have: The driving cycle count CNT2 will be reset to zero and will be incremented again once subsequent conditions are met.

[0022] Furthermore, 5) In other cases, , This is the self-learning coefficient stored since the last self-learning update.

[0023] Furthermore, in condition 1) above, 11) if a torque deviation rate occurs... Less than the torque threshold ,in ,in The default torque threshold is... Requesting arc torque for the engine, , This is the actual firing torque of the engine; therefore, further updates are needed. .

[0024] 12) If the number of times CNT3 satisfies both conditions 1) and 11) above exceeds the preset value, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ,in The margin difference from the last self-learning update is the self-learning coefficient.

[0025] 13) If the number of consecutive times CNT4 exceeds the preset value when condition 1) is met but condition 11) is not met, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ;

[0026] 14) In other cases, .

[0027] Furthermore, in condition 4) above, 41) if All are not less than the torque threshold Then further updates ;

[0028] 42) If both conditions 4) and 41) above are met, and the number of times CNT5 exceeds the preset value, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ;

[0029] 43) If the number of consecutive times CNT6 exceeds the preset value when condition 4) is met but condition 41) is not met, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ;

[0030] 44) In other cases, .

[0031] Further, in step S200, 1) if the following occurs Then , , , All were reduced.

[0032] ; ; ;

[0033] in , , and These are the last learned update values ​​of the self-learning coefficients for the first, second, third, and fourth row temperature thresholds, respectively.

[0034] Further, in step S200, 2) if the following occurs Then , , , All were increased.

[0035] ; ; ; .

[0036] Furthermore, in step S200, 3) in other cases, ; ; ; .

[0037] Secondly, embodiments of the present invention provide an EGR control system for ignition system failure, comprising:

[0038] The determination module is used to detect the ignition system and, after detecting a failure in at least one component, determine the corrected target EGR rate after the failure of each component.

[0039] The control module is used to obtain the final target EGR rate by taking the minimum value of the corrected target EGR rate after all components fail, and to limit the final target EGR rate to not exceed the target EGR rate before the failure, and to perform EGR control based on the final target EGR rate.

[0040] The EGR control method and system provided by this invention after an ignition system failure involves detecting the ignition system and determining the corrected target EGR rate after the failure of at least one component. The final target EGR rate is obtained by minimizing the corrected target EGR rates after all component failures and limiting the final target EGR rate to not exceed the pre-failure target EGR rate. EGR control is then performed based on the final target EGR rate. This effectively reduces the likelihood of engine knocking after a knock sensor failure while avoiding impacts on emissions, power, and fuel consumption. Attached Figure Description

[0041] Figure 1 A flowchart illustrating an EGR control method after an ignition system failure, provided in an embodiment of the present invention;

[0042] Figure 2 This is a structural block diagram of an EGR control system after an ignition system failure, provided as an embodiment of the present invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely 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 invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0044] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.

[0045] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0047] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0048] This invention provides an EGR control method after an ignition system failure. Figure 1 This invention provides a flowchart illustrating an EGR control method after an ignition system failure, comprising the following steps:

[0049] S100. Inspect the ignition system and, after detecting a fault in at least one component, determine the corrected target EGR rate after the fault in each component.

[0050] In one embodiment, the ignition system includes the following components: an ignition coil and a knock sensor. Ignition coil: A typical ignition coil contains two coils, a primary coil and a secondary coil. When the primary coil is powered on, a strong magnetic field is generated around it as the current increases, and the iron core stores magnetic energy. When the switching device disconnects the primary coil circuit, the magnetic field of the primary coil decays rapidly, and a high voltage is induced in the secondary coil. The faster the magnetic field of the primary coil disappears, the larger the current at the moment of disconnection, and the larger the turns ratio of the two coils, the higher the voltage induced in the secondary coil. Knock sensor: An important indicator for determining whether knock has occurred in the engine. Knock is an abnormal combustion phenomenon. After the air-fuel mixture in the cylinder is ignited, the flame propagates from the spark plug outwards. During this propagation, the unburned mixture is compressed by the flame front, resulting in increased pressure and temperature. The excessively high temperature of the remaining unburned mixture may lead to sudden and spontaneous combustion, i.e., knock.

[0051] Assuming the target EGR rate before the failure occurred was... It can be determined through existing technology CN202011247319.6 "A Calculation Method and System for Target EGR Rate".

[0052] In one embodiment, 1) if an ignition coil fault is detected: target EGR rate after forced control correction .

[0053] In one embodiment, 2) if a knock sensor malfunction is detected:

[0054] 2.1) Determine the transient operating coefficients of the engine. ;

[0055] Transient operating coefficient of engine Engine speed n and intake pressure fluctuation rate This value is jointly determined and represents the transient operating conditions of the engine. The larger the value, the more volatile the engine operating conditions. The value is limited to within 0-1. Take the samples from the most recent N sampling periods (each sampling period is 10ms) before... The difference between the maximum and minimum values ​​of N. N is related to engine speed; the lower the speed, the smaller the N value, and the higher the speed, the larger the N value. This is mainly because at lower speeds, intake pressure fluctuations are more pronounced, and a larger sampling period cannot accurately reflect transient operating conditions. The N values ​​corresponding to different engine speeds n are shown in the table below:

[0056] Table 1. Correspondence between N value and engine speed

[0057] Engine speed n (rpm) 0 1000 1500 2000 2500 3000 4000 6000 N 0 4 6 8 9 10 12 15

[0058] This refers to the intake pressure at the throttle outlet. The throttle outlet intake pressure is the value for the Nth sampling period. This represents the throttle outlet intake pressure after a first-order low-pass filter. is the filtered throttle outlet intake pressure in the Nth sampling period.

[0059]

[0060] in, Let N be the filtered throttle outlet intake pressure in the (N-1)th sampling period, where N = 1, 2, 3… Equal to the throttle outlet intake pressure at the 0th sampling period Sampling period interval In this example, it took 10ms. This is the intake pressure coefficient at the throttle outlet. (The engine in this example has 4 cylinders) The calibration speed is 1000 rpm. The purpose of this setting is for normalization; no special calibration is needed for different numbers of cylinders and engine speeds. Only the 4-cylinder engine and the engine at 1000 rpm need to be calibrated. This reduces calibration testing work. The number of engine cylinders. Engine speed, This is the throttle outlet intake pressure filtering coefficient, which is set to 0.02 in this example. The engine's transient operating coefficient. Use the table below to find the engine speed n and intake pressure fluctuation rate. The corresponding value is determined, and the transient operating condition coefficient change rate is limited to no more than 0.1 / 10ms based on the table lookup data above. This yields the final transient operating condition coefficient. .

[0061] Table 2. Correspondence between transient operating condition coefficients and engine speed and intake pressure fluctuation rates

[0062]

[0063] 2.2) Based on transient operating condition coefficients The corrected target EGR rate is obtained by determining the target EGR rate before the failure.

[0064] In one embodiment, based on transient operating condition coefficients The formula for calculating the corrected target EGR rate, obtained from the pre-fault target EGR rate determination, is as follows:

[0065]

[0066] in This is the speed-load correction factor. For engine coolant temperature correction factor, This is the intake air temperature correction factor. This is the ignition efficiency correction factor based on rotational speed. The self-learning correction coefficient for the target EGR rate.

[0067] This is a basic correction factor determined jointly based on engine speed and load rho (intake density of fresh air entering the cylinder). The higher the engine speed and the greater the engine load, the more prone the engine is to knock. To ensure that knocking is prevented from actually occurring when the knock sensor malfunctions, the basic correction factor determined based on engine speed and load should be as small as possible. (Speed ​​and load correction factor) The values ​​corresponding to engine speed n and load rho are determined by looking up the table below.

[0068] Table 3. Correspondence between speed-load correction coefficient and engine speed and load

[0069]

[0070] The purpose of reducing the EGR rate is to allow the engine room to operate under conditions prone to knocking. In situations where knocking is likely, increasing the EGR rate can suppress the possibility of knocking. This requires reducing the engine's basic ignition angle efficiency to avoid the risk of knocking and thus updating the basic ignition angle efficiency. ,in Specifically, the basic ignition angle efficiency (also known as ignition efficiency) of the engine mentioned in the prior art, This margin difference further reduces the risk of knocking, where C1 is the default value. The value is less than 0.2; in this example, it is 0.1. This is the self-learning coefficient for the margin difference C1. Its default value is 0. It can be continuously updated through self-learning and can be saved after the vehicle is powered off.

[0071] Determined by engine coolant temperature, this serves as a correction factor for the target EGR rate after a knock sensor malfunction. Higher engine coolant temperatures increase the likelihood of knocking. (Engine coolant temperature correction factor) The water temperature can be determined by referring to the table below.

[0072] Table 4. Correspondence between engine coolant temperature correction factor and coolant temperature

[0073] Water temperature (°C) 70 80 90 100 110 120 1 1.02 1.05 1.1 1.15 1.3

[0074] Determined by the intake air temperature (temperature in the intake manifold after the throttle valve), it serves as a correction factor for the target EGR rate after a knock sensor malfunction. Higher intake air temperature means higher gas temperature, making knocking more likely. The intake air temperature correction factor... The intake air temperature value can be determined by referring to the table below.

[0075] Table 5. Correspondence between intake air temperature correction factor and intake air temperature

[0076] Inlet air temperature (°C) 50 60 65 70 72 75 1 1.03 1.1 1.15 1.2 1.3

[0077] Speed-intensity ignition efficiency correction factor Based on the difference between engine speed n and ignition efficiency This was jointly determined as a correction factor for the target EGR rate after a knock sensor malfunction. Specifically, the ignition efficiency difference ratio... Due to differences in ignition efficiency and the corrected basic ignition efficiency Confirmed, among which , This represents the engine's actual ignition angle efficiency. Therefore... A smaller EGR rate increases the likelihood of knocking, necessitating a further increase in the EGR rate and the speed-to-ignition efficiency correction factor. The value corresponding to the difference between engine speed and ignition efficiency can be determined by referring to the table below.

[0078] Table 6. Correspondence between the engine speed and ignition efficiency correction coefficient and the difference ratio between engine speed and ignition efficiency.

[0079]

[0080] This is the target EGR rate self-learning correction coefficient after a knock sensor failure. Its default value is 0, and it is continuously updated through self-learning. It can also be saved after the vehicle is powered off.

[0081] Its self-learning can only proceed if all conditions are met, as follows:

[0082] 1. The knock sensor malfunctioned, and no other malfunctions occurred;

[0083] 2. Transient operating condition coefficient Not lower than the preset value; in this example, it is set to 0.5.

[0084] 3. The engine coolant temperature exceeds the preset value; in this example, it is set to 90℃.

[0085] 4. The intake air temperature exceeds the preset value; in this example, it is set to 65℃.

[0086] 5. The ambient temperature exceeds the preset value; in this example, it is set to 40℃.

[0087] 6. Atmospheric pressure exceeds the preset value; in this example, it is set to 80 kPa.

[0088] After all the above conditions are met

[0089] 1) If the exhaust temperature (exhaust manifold temperature) exceeds the first preset temperature T1 for a continuous period exceeding t1 (0.2s in this example), ,in The first default preset temperature is 980℃ in this example. This is the self-learning coefficient for the first row temperature threshold. Its default value is 0. It can be continuously updated through self-learning and is saved after the vehicle is powered off.

[0090] Then there is ,in The learned values ​​stored from the previous learning session.

[0091] Specifically, if the following conditions are met

[0092] 11) If torque deviation rate occurs Less than the torque threshold ,in ,in The default torque threshold is set to 0.3 in this example. Requesting arc torque for the engine, , This represents the actual torque output of the engine's firing circuit. Further updates will follow. Engine knocking may occur. In this case, appropriately increasing the EGR rate can protect against the possibility of engine knocking.

[0093] 12) If the number of times conditions 1) and 11) above are met exceeds the preset value (5 times in this example), then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ,in This is the margin difference value for the previous self-learning update, representing the self-learning coefficient. The number of updates is CNT3, with a default value of 0. It can continuously self-learn and update, and can be saved after the vehicle is powered off. It increments by 1 when conditions 1) and 11) are both met, and is updated at most once in each driving cycle. After the update, the count CNT3 will be reset to zero.

[0094] 13) If the number of consecutive times CNT4 exceeds the preset value (8 times in this example), and condition 1) is met but condition 11) is not met, then the update will be performed. During the update, the self-learning coefficient of the margin difference C1 is... Update and get The consecutive count CNT4 has a default value of 0. It can continuously learn and update itself, and can be saved after the vehicle is powered off. It increments by 1 if condition 1) is met but condition 11) is not met, and updates at most once in each driving cycle. After the update, the consecutive count CNT4 will be reset to zero.

[0095] 14) In other cases, .

[0096] 2) If the exhaust temperature (exhaust manifold temperature) exceeds the second preset temperature T2 for a continuous period of time exceeding t2 (0.1s in this example). ,in The second default preset temperature is 965℃ in this example. This is the self-learning coefficient for the second row temperature threshold. Its default value is 0. It can be continuously updated through self-learning and is saved after the vehicle is powered off.

[0097] Then there is .

[0098] 3) If the number of driving cycles CNT1 in which the exhaust temperature (exhaust manifold temperature) does not exceed the third preset temperature T3 exceeds the preset value of the first cycle number, in this example, it is set to 10. That is, as long as the above judgment conditions are met in each driving cycle, the exhaust temperature (exhaust manifold temperature) does not exceed the third preset temperature T3, and the number of times it is met exceeds the preset value of the first cycle number. ,in The third default preset temperature is 800℃ in this example. The third exhaust temperature threshold T3 is the self-learning coefficient, with a default value of 0. It can be continuously updated through self-learning and is saved after the vehicle is powered off. The driving cycle number CNT1 has a default value of 0 and is updated at most once per driving cycle. If the exhaust temperature (exhaust manifold temperature) does not exceed the third preset temperature T3, the driving cycle number CNT1 is incremented by 1.

[0099] Then there is The driving cycle count CNT1 will be reset to zero and will be incremented again once subsequent conditions are met.

[0100] 4) If the number of driving cycles (CNT2) in which the exhaust manifold temperature does not exceed the fourth preset temperature T4 exceeds the preset value for the second cycle number (6 in this example), then the exhaust manifold temperature will not exceed the fourth preset temperature T4 in every driving cycle. ,in The fourth default preset temperature is 750℃ in this example. The self-learning coefficient for the fourth preset temperature T4 has a default value of 0. It can be continuously updated through self-learning and is saved after the vehicle is powered off. The driving cycle count CNT2 has a default value of 0 and is updated at most once per driving cycle. If the exhaust temperature (exhaust manifold temperature) does not exceed the fourth preset temperature T4, the driving cycle count CNT2 is incremented by 1.

[0101] Then there is The driving cycle count CNT2 will be reset to zero and will be incremented again once subsequent conditions are met.

[0102] Specifically, if the following conditions are met:

[0103] 41) If All are not less than the torque threshold Then further updates There is no possibility of knocking. At this time, the EGR rate should be appropriately reduced to avoid further reduction in exhaust temperature and thus affecting emissions.

[0104] 42) If both conditions 4) and 41) above are met, the number of times CNT5 exceeds the preset value. In this example, it is set to 5 times. During the update, the self-learning coefficient of the margin difference C1 is... Update and get The number of times (CNT5) has a default value of 0. It can continuously learn and update itself, and can be saved after the vehicle is powered off. It increments by 1 when conditions 4) and 41) are both met, and updates at most once per driving cycle. After the update, the count CNT5 will be reset to zero.

[0105] 43) If the number of consecutive times CNT6 exceeds the preset value (8 times in this example), and condition 4) is met but condition 41) is not met, then the update will be performed. During the update, the self-learning coefficient of the margin difference C1 is... Update and get The consecutive count CNT6 has a default value of 0, can be continuously updated through self-learning, and can be saved after the vehicle is powered off. It increments by 1 if condition 4) is met but condition 41) is not met, and updates a maximum of one count per driving cycle. After the update, the consecutive count CNT6 will be reset to zero.

[0106] 44) In other cases, .

[0107] 5) In other cases, , This is the self-learning coefficient stored since the last self-learning update.

[0108] S200. The final target EGR rate is obtained by taking the minimum value of the corrected target EGR rate after all component failures. and the final target EGR rate Limit to not exceeding the target EGR rate before the failure EGR control is performed based on the final target EGR rate.

[0109] In one embodiment, the following condition is updated at most once per driving cycle:

[0110] 1) If it occurs This indicates that a high EGR rate is required to avoid knocking. , , , All were reduced.

[0111] ; ; ;

[0112] in , , and These are the last learned update values ​​of the self-learning coefficients for the first, second, third, and fourth row temperature thresholds, respectively.

[0113] 2) If it occurs This indicates that a lower EGR rate is required, making knocking less likely. Therefore, the reduction of the EGR rate should be slower, fully utilizing the role of EGR in improving fuel economy. , , , All were increased.

[0114] ; ; ; .

[0115] 3) In other cases, ; ; ; .

[0116] In this embodiment of the invention, after the knock sensor fails, the target EGR rate is first determined to be reduced under the basic operating conditions based on speed and load. At the same time, the EGR rate is increased under transient conditions and when the engine operating temperature is high to reduce the possibility of knocking. Meanwhile, the entire dynamic control parameters are self-learned and updated based on the engine torque performance and exhaust temperature performance. This effectively reduces the possibility of engine knocking after the knock sensor fails, while avoiding the impact on emissions, power, and fuel consumption.

[0117] The present invention also provides an EGR control system after an ignition system failure. Figure 2 A structural block diagram of an EGR control system after an ignition system failure is provided in an embodiment of the present invention. The system includes:

[0118] The determination module 11 is used to detect the ignition system and, after detecting that at least one component has failed, determine the corrected target EGR rate after the failure of each component.

[0119] Control module 12 is used to obtain the final target EGR rate by taking the minimum value of the corrected target EGR rate after all component failures. and the final target EGR rate Limit to not exceeding the target EGR rate before the failure EGR control is performed based on the final target EGR rate.

[0120] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A method for EGR control after an ignition system failure, characterized in that, Includes the following steps: S100. Inspect the ignition system. If at least one component fails, determine the corrected target EGR rate after each component fails. S200: Take the minimum value of the corrected target EGR rate after all components fail to obtain the final target EGR rate, and limit the final target EGR rate to not exceed the target EGR rate before the failure. Perform EGR control based on the final target EGR rate.

2. The method according to claim 1, characterized in that, The ignition system includes the following components: ignition coil and knock sensor.

3. The method according to claim 2, characterized in that, In step S100, 1) if an ignition coil malfunction is detected: target EGR rate after forced control correction. .

4. The method according to claim 3, characterized in that, 2) If a knock sensor malfunction is detected: 2.1) Determine the transient operating coefficients of the engine. ; 2.2) Based on transient operating condition coefficients The corrected target EGR rate is obtained by determining the target EGR rate before the failure.

5. The method according to claim 4, characterized in that, Based on transient operating condition coefficient The formula for calculating the corrected target EGR rate, obtained from the pre-fault target EGR rate determination, is as follows: in This is the speed-load correction factor. For engine coolant temperature correction factor, This is the intake air temperature correction factor. This is the ignition efficiency correction factor based on rotational speed. The self-learning correction coefficient for the target EGR rate.

6. The method according to claim 5, characterized in that, When the conditions for self-learning are met 1) If the exhaust temperature exceeds the first preset temperature T1 for a continuous period of time exceeding t1, ,in The first default preset temperature. Let be the self-learning coefficients for the first row of temperature thresholds, then we have ,in The learned values ​​stored from the previous learning session.

7. The method according to claim 6, characterized in that, 2) If the exhaust temperature exceeds the second preset temperature T2 for a continuous period of time exceeding t2, ,in The second default preset temperature. Let be the self-learning coefficient for the second row temperature threshold, then we have .

8. The method according to claim 7, characterized in that, 3) If the number of driving cycles CNT1 in which the exhaust temperature does not exceed the third preset temperature T3 continuously exceeds the first preset cycle number, ,in The third default preset temperature. Let T3 be the self-learning coefficient for the third row temperature threshold. Then we have: The driving cycle count CNT1 will be reset to zero and will be incremented again once subsequent conditions are met.

9. The method according to claim 8, characterized in that, 4) If the number of driving cycles (CNT2) in which the exhaust temperature does not exceed the fourth preset temperature (T4) exceeds the second preset cycle number, ,in The fourth default preset temperature. Let T4 be the self-learning coefficient for the fourth preset temperature. Then we have: The driving cycle count CNT2 will be reset to zero and will be incremented again once subsequent conditions are met.

10. The method according to claim 9, characterized in that, 5) In other cases, , This is the self-learning coefficient stored since the last self-learning update.

11. The method according to claim 10, characterized in that, In condition 1) above, 11) if a torque deviation rate occurs... Less than the torque threshold ,in ,in The default torque threshold is... Requesting arc torque for the engine, , This is the actual firing torque of the engine; therefore, further updates are needed. . 12) If the number of times CNT3 satisfies both conditions 1) and 11) above exceeds the preset value, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ,in The margin difference from the last self-learning update is the self-learning coefficient. 13) If the number of consecutive times CNT4 exceeds the preset value when condition 1) is met but condition 11) is not met, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ; 14) In other cases, .

12. The method according to claim 11, characterized in that, In condition 4) above, 41) if All are not less than the torque threshold Then further updates ; 42) If both conditions 4) and 41) above are met, and the number of times CNT5 exceeds the preset value, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ; 43) If the number of consecutive times CNT6 exceeds the preset value when condition 4) is met but condition 41) is not met, then... During the update, the self-learning coefficient of the margin difference C1 is... Update and get ; 44) In other cases, .

13. The method according to claim 12, characterized in that, In step S200, 1) if the following occurs Then , , , All were reduced. ； ； ； in , , and These are the last learned update values ​​of the self-learning coefficients for the first, second, third, and fourth row temperature thresholds, respectively.

14. The method according to claim 13, characterized in that, In step S200, 2) if the following occurs Then , , , All were increased. ； ； ； 。 15. The method according to claim 14, characterized in that, In step S200, 3) in other cases ; ; ; .

16. An EGR control system for ignition system failure, characterized in that, include: The determination module is used to detect the ignition system and, after detecting a failure in at least one component, determine the corrected target EGR rate after the failure of each component. The control module is used to obtain the final target EGR rate by taking the minimum value of the corrected target EGR rate after all components fail, and to limit the final target EGR rate to not exceed the target EGR rate before the failure, and to perform EGR control based on the final target EGR rate.

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