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

Abstract

The invention provides an EGR control method and system after a fan fault, and belongs to the technical field of engine exhaust gas recirculation rate control. According to the method, the fan is detected, and after it is detected that at least one fault happens to the fan, corrected target EGR rates of various faults are determined; and taking a minimum value of the corrected target EGR rate of each fault to obtain a final target EGR rate, limiting the final target EGR rate to be not greater than the target EGR rate before the fault, and performing EGR control according to the final target EGR rate. According to the method, different target EGR rates can be optimized according to the fan fault occurrence condition, meanwhile, dynamic adjustment and updating are continuously carried out, and knocking occurrence after the fault occurs is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine exhaust gas recirculation rate control, and in particular to an EGR control method and system after a fan failure. Background Art

[0002] Exhaust Gas Recirculation (EGR) takes exhaust gas from the exhaust and enters the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock capabilities. Compared with high-pressure EGR, low-pressure EGR takes air after the turbine, so there is no loss of turbine efficiency, and it can use EGR under almost all operating conditions, which is more significant in improving fuel efficiency. However, due to its low pressure difference, a large-diameter valve is required to meet the flow requirements. Under some 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 on both sides of the EGR valve and improving the EGR rate. If the fan fails, still controlling it according to the target EGR rate before the failure will cause the engine's knock performance to deteriorate. Summary of the Invention

[0003] 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 a fan failure.

[0004] In a first aspect, an embodiment of the present invention provides an EGR control method after a fan failure, comprising the following steps:

[0005] S100, testing the fan, and upon detecting at least one fault of the fan, determining a corrected target EGR rate for each fault;

[0006] S200 , taking the minimum value of the corrected target EGR rates for various faults to obtain a final target EGR rate, limiting the final target EGR rate to not exceed the pre-fault target EGR rate, and performing EGR control based on the final target EGR rate.

[0007] Furthermore, in step S100, if a low-speed fan failure is detected:

[0008] 1.1) When the low-speed fan detects that the speed is too high, that is, the actual speed of the low-speed fan is higher than the first fan target speed, .

[0009] Furthermore, in step S100, if a low-speed fan failure is detected:

[0010] 1.2) If the low-speed fan detects that the speed is too low or not running, that is, the actual speed of the low-speed fan is lower than the target speed of the second fan,

[0011] 1.2.1) When the low speed fan is not requested to start, the corrected target EGR rate ;

[0012] 1.2.2) When the low speed fan is requested to be turned on, the corrected target EGR rate as follows:

[0013]

[0014] in, is the first speed load correction coefficient, is the first optimization correction coefficient determined based on the transient operating condition coefficient, is the first correction coefficient determined based on the engine water temperature difference, is the optimization correction coefficient determined based on the difference ratio between engine speed and ignition efficiency, It is the first target EGR rate self-learning correction coefficient.

[0015] Furthermore, in step S100, if a low-speed fan failure is detected:

[0016] 1.3) If the low speed fan detects other faults, the target EGR rate will be corrected. .

[0017] Furthermore, if a high-speed fan failure is detected:

[0018] 2.1) When the high-speed fan detects that the speed is too high, that is, the actual speed of the high-speed fan is higher than the target speed of the third fan, .

[0019] Furthermore, if a high-speed fan failure is detected:

[0020] 2.2) If the high-speed fan detects that the speed is too low or not rotating, that is, the actual speed of the high-speed fan is lower than the fourth fan target speed,

[0021] 2.2.1) When the high-speed fan is not requested to start, the corrected target EGR rate ;

[0022] 2.2.2) When the high-speed fan is requested to be turned on, the corrected target EGR rate as follows:

[0023]

[0024] in, is the second speed load correction coefficient, is the second correction coefficient determined based on the engine water temperature difference, It is the second target EGR rate self-learning correction coefficient.

[0025] Furthermore, if a high-speed fan failure is detected:

[0026] 2.3) If the high-speed fan detects other faults, the target EGR rate will be corrected. .

[0027] Further, if a low speed fan fault is detected,

[0028] a) If , then To reduce, ,in The first target EGR rate self-learning correction coefficient updated in the last learning;

[0029] b) If , then All are reduced, ;

[0030] c) If , then All increased, ;

[0031] d) If , then To increase, ;

[0032] e) In other cases, .

[0033] Further, if a high-speed fan failure is detected,

[0034] a) If , then To reduce, ;

[0035] b) If , then All are reduced, ;

[0036] c) If , then All increased, ;

[0037] d) If , then To increase, ;

[0038] e) In other cases, .

[0039] Further, if a low speed fan fault is detected, in case a), 1) if a low speed fan fault occurs and ,and If the value is not greater than -0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low-speed fan failure occurs Not greater than -0.2, and appears , and a high-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , , The second target EGR rate self-learning correction coefficient updated in the last learning; 3) In other cases, it remains unchanged.

[0040] Further, if a low speed fan fault is detected, in case c), 1) if a low speed fan fault occurs and ,and If the value is greater than 0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low speed fan failure occurs and , and appears Greater than 0.2, and a high-speed fan failure occurs during this driving cycle, and Not less than 0.2, then further , ;3) In other cases, remain unchanged.

[0041] Furthermore, if a low-speed fan fault is detected, in case e), if CNT1 exceeds the preset value continuously, the initial value of CNT1 is 0, and it is increased by 1 after each driving cycle of the vehicle, and can be saved after the vehicle is powered off. At the same time, the vehicle mileage S1 exceeds the preset value, the initial value of S1 is 0, and it is continuously updated according to the vehicle mileage, and can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT1 and S1; 2) If <0, then , and clear CNT1 and S1; 3) Others remain unchanged.

[0042] Further, if a high-speed fan failure is detected, in case a), 1) if a high-speed fan failure occurs and ,and If the value is not greater than -0.1 and no low-speed fan failure occurs during this driving cycle, then: ;2) If a high-speed fan failure occurs Not greater than -0.1, and appears , and a low-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , ;3) In other cases, remain unchanged.

[0043] Further, if a high-speed fan failure is detected, in case c), 1) if a high-speed fan failure occurs and ,and If the value is greater than 0.2 and no low-speed fan failure occurs during this driving cycle, then: ; 2) If the water high-speed fan fails and , and appears Greater than 0.2, and a low-speed fan failure occurs during this driving cycle, and If it is greater than 0.2, then further , ;3) In other cases, remain unchanged.

[0044] Furthermore, if CNT2 exceeds the preset value continuously, the initial value of CNT2 is 0, and it is increased by 1 after each driving cycle of the vehicle, and can be saved after the vehicle is powered off. At the same time, the vehicle mileage S2 exceeds the preset value, the initial value of S2 is 0, and it is continuously updated according to the vehicle mileage, and can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT2 and S2; 2) If <0, then , and clear CNT2 and S2; 3) Others remain unchanged.

[0045] In a second aspect, an embodiment of the present invention provides an EGR control system after a fan failure, comprising:

[0046] a determination module, configured to detect the fan and, upon detecting at least one fault of the fan, determine a corrected target EGR rate for each fault;

[0047] The control module is used to obtain the minimum value of the corrected target EGR rate of various faults to obtain the final target EGR rate, limit the final target EGR rate to not exceed the target EGR rate before the fault, and perform EGR control according to the final target EGR rate.

[0048] The post-fan fault EGR control method and system provided by the present invention are configured to detect the fan, and after detecting at least one fan fault, the corrected target EGR rate for various faults is determined; the minimum value of the corrected target EGR rate for various faults is taken to obtain the final target EGR rate, and the final target EGR rate is limited to not exceed the target EGR rate before the fault, and EGR control is performed according to the final target EGR rate; different target EGR rates can be optimized according to the occurrence of the fan fault, and are continuously and dynamically adjusted and updated, thereby effectively improving the occurrence of knock after the fault occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic flow chart of an EGR control method after a fan failure provided by an embodiment of the present invention;

[0050] Figure 2 This is a structural block diagram of an EGR control system after a fan failure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] 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 facilitate understanding. These details should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0052] In the absence of conflict, the various embodiments of the present invention and the various features therein may be combined with each other.

[0053] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0054] The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a" and "the" are also intended to include the plural forms, 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 features, wholes, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof is not excluded. Similar words such as "connected" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0055] 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 also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined as such herein.

[0056] The present invention provides an EGR control method after a fan failure. Figure 1 A flow chart of a method for controlling EGR after a fan failure is provided in an embodiment of the present invention. The method includes the following steps:

[0057] S100 : Detecting the fan, and after detecting at least one fault of the fan, determining a corrected target EGR rate for various faults.

[0058] High and low speed fan: When the thermostat cannot control the water temperature, the fan needs to be turned on to increase the cooling of the external wind. Assuming that before the fault occurs, the target EGR rate before the fault is , which can be determined by the existing technology CN202011247319.6 "A method and system for calculating the target EGR rate".

[0059] In one embodiment, if a low speed fan fault is detected:

[0060] 1.1) When the low-speed fan detects that the speed is too high, that is, the actual speed of the low-speed fan is higher than the first fan target speed (determined according to the actual component characteristics of the low-speed fan), ;

[0061] 1.2) If the low-speed fan detects that its speed is too low or not rotating, that is, the actual speed of the low-speed fan is lower than the second fan target speed (determined according to the actual component characteristics of the low-speed fan),

[0062] 1.2.1) When the low speed fan is not requested to start, the corrected target EGR rate ;

[0063] 1.2.2) When the low speed fan is requested to be turned on, the corrected target EGR rate as follows:

[0064]

[0065] in, is the first speed load correction coefficient, is the first optimization correction coefficient determined based on the transient operating condition coefficient, is the first correction coefficient determined based on the engine water temperature difference, is the optimization correction coefficient determined based on the difference ratio between engine speed and ignition efficiency, It is the first target EGR rate self-learning correction coefficient.

[0066] It is a basic correction coefficient determined based on the engine speed n and load rho (the density of fresh air intake into the cylinder). The higher the engine speed and the greater the engine load, the more likely the engine is to knock. In order to ensure that the engine can avoid actual knock when the knock sensor fails, the smaller the basic correction coefficient determined based on the speed and load, the lower the possibility of knock. The purpose of reducing the EGR rate is to reserve space for the engine in conditions prone to knock. Once knock actually occurs when it is prone to knock, the EGR rate can be increased to suppress the possibility of knock. The first speed load correction coefficient Determine the corresponding values ​​of engine speed n and load rho by looking up the table below.

[0067] Table 1 Correspondence between the first speed load correction coefficient and engine speed and load

[0068]

[0069] Transient operating coefficient The engine speed n and the intake pressure fluctuation rate It is jointly determined and represents the changes in the transient operating conditions of the engine. The larger the value, the more volatile the engine operating conditions. Its value is limited to 0-1. Take the data before the last N sampling periods (single sampling period is 10ms) The difference between the maximum and minimum values ​​of N. N is related to the engine speed. The lower the speed, the smaller the N value, and the higher the speed, the larger the N value. The main reason is that the lower the speed, the more obvious the intake pressure fluctuations. The larger the sampling cycle, the less likely it is to truly reflect the transient operating conditions. The N values ​​corresponding to different engine speeds n are as follows:

[0070] Table 2 Corresponding relationship between N value and engine speed

[0071]

[0072] is the throttle outlet intake pressure, is the throttle outlet intake pressure of the Nth sampling period, is the throttle outlet intake pressure after first-order low-pass filtering, is the filtered throttle outlet intake pressure of the Nth sampling period.

[0073]

[0074] in, is the filtered throttle outlet intake pressure of the N-1th sampling period, N=1,2,3…, Equal to the throttle outlet intake pressure at the 0th sampling cycle ; Sampling period interval In this example, it is 10ms. is the throttle outlet intake pressure coefficient, (The number of engine cylinders in this example is 4, The calibration speed is 1000rpm. The purpose of this setting is to normalize the process. Under different cylinder numbers and speeds, no special calibration is required. Only the 4-cylinder engine and the speed of 1000rpm need to be calibrated. , thereby reducing calibration testing work), where is the number of engine cylinders, is the engine speed, The filter coefficient of the intake pressure at the throttle outlet is 0.02 in this example. Use the following table to query the engine speed n and intake pressure fluctuation rate The corresponding value is determined. In the above table data, the transient operating coefficient change rate is limited to no more than ±0.1 / 10ms, and the final transient operating coefficient is obtained. .

[0075] Table 3 Corresponding relationship between transient operating coefficient and engine speed and intake pressure fluctuation rate

[0076]

[0077] The first optimization correction coefficient determined based on the transient operating condition coefficient Check the transient operating coefficient in the table below The corresponding value is determined. The purpose of this setting is to show through experiments that when the engine operating condition shakes slowly, the engine water temperature has a smaller risk of knocking. When the engine operating condition shakes more violently, the water temperature has a greater risk of knocking.

[0078] Table 4 Correspondence between the optimized correction coefficient determined based on the transient operating condition coefficient and the transient operating condition coefficient

[0079]

[0080] Based on the engine water temperature difference The correction coefficient is determined. When the water temperature difference is greater, The larger the value, the less likely detonation will occur. is the target engine water temperature, In particular, if the water temperature sensor fails, The first correction coefficient determined based on the engine water temperature difference is determined by looking up the value corresponding to the engine water temperature difference in the following table.

[0081] Table 5 Correspondence between the first correction coefficient determined based on the engine water temperature difference and the engine water temperature difference

[0082]

[0083] Ignition efficiency difference ratio Differences in ignition efficiency and basic ignition efficiency Sure, It is the basic ignition angle efficiency of the engine mentioned in the prior art (also called ignition efficiency), , is the actual ignition angle efficiency of the engine. The smaller the value, the more likely detonation will occur. If the engine water temperature sensor temperature is too low, detonation will occur more easily. It is necessary to further increase the EGR rate. The optimization correction coefficient is determined based on the difference between the engine speed and the ignition efficiency. Determine the value corresponding to the engine speed and ignition efficiency difference ratio by looking up the table below.

[0084] Table 6 Correspondence between the optimized correction coefficient determined based on the engine speed and ignition efficiency difference ratio and the engine speed and ignition efficiency difference ratio

[0085]

[0086] It is the target EGR rate self-learning correction coefficient after a low-speed fan failure occurs. Its default value is 0 and it can be continuously updated through self-learning.

[0087] 1.3) If the low speed fan detects other faults, the target EGR rate will be corrected. .

[0088] In one embodiment, if a high-speed fan failure is detected:

[0089] 2.1) When the high-speed fan detects that the speed is too high, that is, the actual speed of the high-speed fan is higher than the target speed of the third fan (determined according to the actual component characteristics of the high-speed fan), ;

[0090] 2.2) If the high-speed fan detects that the speed is too low or not rotating, that is, the actual speed of the high-speed fan is lower than the fourth fan target speed (determined according to the actual component characteristics of the high-speed fan),

[0091] 2.2.1) When the high-speed fan is not requested to start, the corrected target EGR rate ;

[0092] 2.2.2) When the high-speed fan is requested to be turned on, the corrected target EGR rate as follows:

[0093]

[0094] in, is the second speed load correction coefficient, is the second correction coefficient determined based on the engine water temperature difference, It is the second target EGR rate self-learning correction coefficient.

[0095] , For the same engine speed n and the same engine intake density, it is not greater than The basic correction coefficient is mainly due to the fact that the high-speed fan request is turned on at this time. The water temperature is higher than when the low-speed fan is turned on. At this time, the risk of knock is greater. Reducing the EGR rate first makes it possible to increase the EGR rate in subsequent operating conditions to suppress knock. C1 is the first adjustment coefficient that is greater than 0 and not greater than 1. In this example, C1 is 0.8.

[0096] Based on the engine water temperature difference The correction coefficient is determined. When the water temperature difference is greater, The larger the value, the less likely it is to cause detonation. Not less than In particular, if the water temperature sensor fails, The second correction coefficient determined based on the engine water temperature difference is determined by looking up the value corresponding to the engine water temperature difference in the following table.

[0097] Table 7 Correspondence between the second correction coefficient determined based on the engine water temperature difference and the engine water temperature difference

[0098]

[0099] It is the target EGR rate self-learning correction coefficient after a high-speed fan failure occurs. Its default value is 0 and it can be continuously updated through self-learning. Adjusted learning rate ratio Be quick, as the risk of detonation is greater at this time.

[0100] 2.3) If the high-speed fan detects other faults, the target EGR rate will be corrected. .

[0101] S200, taking the minimum value of the corrected target EGR rate for various faults to obtain the final target EGR rate The final target EGR rate is limited to not exceed the target EGR rate before the fault, and EGR control is performed according to the final target EGR rate.

[0102] In one embodiment, if a low speed fan fault is detected,

[0103] a) If , indicating that the EGR rate requirement is high. To avoid the occurrence of knock, To reduce, ,in The first target EGR rate self-learning correction coefficient updated in the last learning.

[0104] In particular, if the learning value is adjusted too large, it is necessary to further increase the learning step and pre-control the EGR rate adjustment for high-speed fan failure in advance to improve the risk of knock: 1) If a low-speed fan failure occurs and ,and If the value is not greater than -0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low-speed fan failure occurs Not greater than -0.2, and appears , and a high-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , , The second target EGR rate self-learning correction coefficient updated in the last learning; 3) In other cases, it remains unchanged.

[0105] b) If , indicating that the EGR rate requirement is high. To avoid the occurrence of knock, All are reduced, .

[0106] c) If , indicating that the EGR rate requirement is low and knock is not likely to occur, so the reduction of the EGR rate should be slowed down to make full use of the role of EGR in improving fuel consumption. All increased, .

[0107] In particular, if the learning value is not adjusted much, it is necessary to further adjust the learning pace and pre-control the EGR rate adjustment of the high-speed fan failure in advance to improve the advantages of the EGR rate: 1) If the low-speed fan failure occurs and ,and If the value is greater than 0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low speed fan failure occurs and , and appears Greater than 0.2, and a high-speed fan failure occurs during this driving cycle, and Not less than 0.2, then further , ;3) In other cases, remain unchanged.

[0108] d) If , indicating that the EGR rate requirement is low and knock is not likely to occur, so the reduction of the EGR rate should be slowed down to make full use of the role of EGR in improving fuel consumption. To increase, .

[0109] e) In other cases, .

[0110] In particular, since there has been no need to adjust the EGR rate for a long time to adjust the working advantage of the EGR rate and improve the risk of knock, it is necessary to gradually transition the learning value to restore the advantage of the EGR rate: if CNT1 exceeds the preset value continuously (5000 times in this example), the initial value of CNT1 is 0, and it is increased by 1 after each driving cycle of the vehicle, and it can be saved after the vehicle is powered off. At the same time, the vehicle mileage S1 exceeds the preset value (5 kilometers in this example), the initial value of S1 is 0, and it is continuously updated according to the vehicle mileage, and it can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT1 and S1; 2) If <0, then , and clear CNT1 and S1; 3) Others remain unchanged.

[0111] The above steps are performed at most once per driving cycle.

[0112] In one embodiment, if a high-speed fan failure is detected,

[0113] a) If , indicating that the EGR rate requirement is high. To avoid the occurrence of knock, To reduce, .

[0114] In particular, if the learning value is adjusted too large, it is necessary to further increase the learning step and pre-control the EGR rate adjustment of the low-speed fan in advance to improve the risk of knock: 1) If a high-speed fan failure occurs and ,and If the value is not greater than -0.1 and no low-speed fan failure occurs during this driving cycle, then: ;2) If a high-speed fan failure occurs Not greater than -0.1, and appears , and a low-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , ;3) In other cases, remain unchanged.

[0115] b) If , indicating that the EGR rate requirement is high. To avoid the occurrence of knock, All are reduced, .

[0116] c) If , indicating that the EGR rate requirement is low and knock is not likely to occur, so the reduction of the EGR rate should be slowed down to make full use of the role of EGR in improving fuel consumption. All increased, .

[0117] In particular, if the learning value is not adjusted much, it is necessary to further adjust the learning pace and pre-control the EGR rate adjustment for low-speed fan failure in advance to improve the advantages of EGR rate: 1) If a high-speed fan failure occurs and ,and If the value is greater than 0.2 and no low-speed fan failure occurs during this driving cycle, then: ; 2) If the water high-speed fan fails and , and appears Greater than 0.2, and a low-speed fan failure occurs during this driving cycle, and If it is greater than 0.2, then further , ;3) In other cases, remain unchanged.

[0118] d) If , indicating that the EGR rate requirement is low and knock is not likely to occur, so the reduction of the EGR rate should be slowed down to make full use of the role of EGR in improving fuel consumption. To increase, .

[0119] e) In other cases, .

[0120] In particular, since there has been no need to adjust the EGR rate for a long time to adjust the working advantage of the EGR rate and improve the risk of knock, it is necessary to gradually transition the learning value to restore the advantage of the EGR rate: if CNT2 exceeds the preset value continuously (5000 times in this example), the initial value of CNT2 is 0, and it is increased by 1 after each driving cycle of the vehicle, and it can be saved after the vehicle is powered off. At the same time, the vehicle mileage S2 exceeds the preset value (5 kilometers in this example), the initial value of S2 is 0, and it is continuously updated according to the vehicle mileage, and it can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT2 and S2; 2) If <0, then , and clear CNT2 and S2; 3) Others remain unchanged.

[0121] The above steps are performed at most once per driving cycle.

[0122] The embodiment of the present invention can optimize different target EGR rates according to the occurrence of fan failure, and dynamically adjust and update them continuously, thereby effectively improving the occurrence of knock after the failure occurs.

[0123] The present invention also provides an EGR control system after a fan failure. Figure 2 A structural block diagram of an EGR control system after a fan failure is provided in an embodiment of the present invention. The system includes:

[0124] A determination module 11 is configured to detect the fan and, upon detecting at least one fault of the fan, determine a corrected target EGR rate for each fault;

[0125] The control module 12 is used to obtain the minimum value of the corrected target EGR rate of various faults to obtain the final target EGR rate. The final target EGR rate is limited to not exceed the target EGR rate before the fault, and EGR control is performed according to the final target EGR rate.

[0126] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly indicated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art 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 controlling EGR after a fan failure, characterized in that: The following steps are involved: S100, testing the fan, and upon detecting at least one fault of the fan, determining a corrected target EGR rate for each fault; S200 , taking the minimum value of the corrected target EGR rates for various faults to obtain a final target EGR rate, limiting the final target EGR rate to not exceed the pre-fault target EGR rate, and performing EGR control based on the final target EGR rate.

2. The method according to claim 1, characterized in that In step S100, if it is detected that the low-speed fan fails: 1.1) When the low-speed fan detects that the speed is too high, that is, the actual speed of the low-speed fan is higher than the first fan target speed, .

3. The method according to claim 2, characterized in that In step S100, if it is detected that the low-speed fan fails: 1.2) If the low-speed fan detects that the speed is too low or not running, that is, the actual speed of the low-speed fan is lower than the target speed of the second fan, 1. 2.1) When the low speed fan is not requested to start, the corrected target EGR rate ; 1.2.2) When the low speed fan is requested to be turned on, the corrected target EGR rate as follows: in, is the first speed load correction coefficient, is the first optimization correction coefficient determined based on the transient operating condition coefficient, is the first correction coefficient determined based on the engine water temperature difference, is the optimization correction coefficient determined based on the difference ratio between engine speed and ignition efficiency, It is the first target EGR rate self-learning correction coefficient.

4. The method according to claim 3, characterized in that In step S100, if it is detected that the low-speed fan fails: 1.3) If the low speed fan detects other faults, the target EGR rate will be corrected. .

5. The method according to claim 4, characterized in that If a high-speed fan failure is detected: 2.1) When the high-speed fan detects that the speed is too high, that is, the actual speed of the high-speed fan is higher than the target speed of the third fan, .

6. The method according to claim 5, characterized in that If a high-speed fan failure is detected: 2.2) If the high-speed fan detects that the speed is too low or not rotating, that is, the actual speed of the high-speed fan is lower than the fourth fan target speed, 2.2.1) When the high-speed fan is not requested to start, the corrected target EGR rate ; 2.2.2) When the high-speed fan is requested to be turned on, the corrected target EGR rate as follows: in, is the second speed load correction coefficient, is the second correction coefficient determined based on the engine water temperature difference, It is the second target EGR rate self-learning correction coefficient.

7. The method according to claim 6, characterized in that If a high-speed fan failure is detected: 2.3) If the high-speed fan detects other faults, the target EGR rate will be corrected. .

8. The method according to claim 7, characterized in that If a low speed fan fault is detected, a) If , then To reduce, ,in The first target EGR rate self-learning correction coefficient updated in the last learning; b) If , then All are reduced, ; c) If , then All increased, ; d) If , then To increase, ; e) In other cases, .

9. The method according to claim 8, characterized in that If a high-speed fan failure is detected, a) If , then To reduce, ; b) If , then All are reduced, ; c) If , then All increased, ; d) If , then To increase, ; e) In other cases, .

10. The method according to claim 8, characterized in that If a low speed fan fault is detected, in case a), 1) if a low speed fan fault occurs and ,and If the value is not greater than -0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low-speed fan failure occurs Not greater than -0.2, and appears , and a high-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , , The second target EGR rate self-learning correction coefficient updated in the last learning; 3) In other cases, it remains unchanged.

11. The method according to claim 8, characterized in that If a low speed fan fault is detected, in case c), 1) if a low speed fan fault occurs and ,and If the value is greater than 0.2 and no high-speed fan failure occurs during this driving cycle, then: ;2) If a low speed fan failure occurs and , and appears Greater than 0.2, and a high-speed fan failure occurs during this driving cycle, and Not less than 0.2, then further , ;3) In other cases, remain unchanged.

12. The method according to claim 8, characterized in that If a low-speed fan fault is detected, in case e), if CNT1 exceeds the preset value continuously, the initial value of CNT1 is 0, and it is increased by 1 after each driving cycle of the vehicle, and can be saved after the vehicle is powered off. At the same time, the vehicle mileage S1 exceeds the preset value, the initial value of S1 is 0, and it is continuously updated according to the vehicle mileage, and can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT1 and S1; 2) If <0, then , and clear CNT1 and S1; 3) Others remain unchanged.

13. The method according to claim 9, characterized in that If a high-speed fan failure is detected, in case a), 1) if a high-speed fan failure occurs and ,and If the value is not greater than -0.1 and no low-speed fan failure occurs during this driving cycle, then: ;2) If a high-speed fan failure occurs Not greater than -0.1, and appears , and a low-speed fan failure occurs during this driving cycle, and Less than -0.2, then further , ;3) In other cases, remain unchanged.

14. The method according to claim 9, characterized in that If a high-speed fan failure is detected, in case c), 1) if a high-speed fan failure occurs and ,and If the value is greater than 0.2 and no low-speed fan failure occurs during this driving cycle, then: ; 2) If the water high-speed fan fails and , and appears Greater than 0.2, and a low-speed fan failure occurs during this driving cycle, and If it is greater than 0.2, then further , ;3) In other cases, remain unchanged.

15. The method according to claim 9, characterized in that If CNT2 exceeds the preset value continuously, the initial value of CNT2 is 0, and it is increased by 1 after each driving cycle of the vehicle, and can be saved after the vehicle is powered off. At the same time, the vehicle mileage S2 exceeds the preset value, the initial value of S2 is 0, and it is continuously updated according to the vehicle mileage, and can be saved after the vehicle is powered off, then 1) If ≥0, then , and clear CNT2 and S2; 2) If <0, then , and clear CNT2 and S2; 3) Others remain unchanged.

16. A fan failure EGR control system, characterized in that: include: a determination module, configured to detect the fan and, upon detecting at least one fault of the fan, determine a corrected target EGR rate for various faults; The control module is used to obtain the minimum value of the corrected target EGR rate of various faults to obtain the final target EGR rate, limit the final target EGR rate to not exceed the target EGR rate before the fault, and perform EGR control according to the final target EGR rate.

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