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

Abstract

The invention provides an EGR control method and system after a cooling system breaks down, and belongs to the technical field of engine exhaust gas recirculation rate control. According to the method, the cooling system is detected, and after it is detected that at least one part breaks down, the corrected target EGR rate after all the parts break down 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, different target EGR rates can be optimized according to the fault occurrence conditions of different parts of the cooling system, meanwhile, dynamic adjustment and updating are continuously carried out, and knocking occurring after faults occur is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine exhaust gas recirculation rate control, and particularly relates to an EGR control method and system after cooling system 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 engine cooling system related components fail, the target EGR rate before failure is still controlled, which will cause the engine knock performance to deteriorate. 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 cooling system failure.

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

[0005] S100, detecting the cooling system, and determining the corrected target EGR rate after failure of various components after detecting failure of at least one component;

[0006] S200, taking the minimum value of the corrected target EGR rate after failure of all components to obtain the final target EGR rate, limiting the final target EGR rate to not more than the target EGR rate before failure, and performing EGR control according to the final target EGR rate.

[0007] Further, in the step S100, 1) if the water temperature sensor is detected to fail:

[0008] 1.1) if the water temperature sensor detects a too low failure, the corrected target EGR rate is as follows:

[0009]

[0010] wherein is a first speed-load correction coefficient, is a first optimization correction coefficient determined based on a transient condition coefficient, an optimization correction coefficient determined based on the engine speed and the difference ratio of the ignition efficiency, a first target EGR rate self-learning correction coefficient;

[0011] 1.2) If the water temperature sensor is detected as a stuck fault, the corrected target EGR rate is as follows:

[0012]

[0013] wherein a second speed-load correction coefficient, a second optimization correction coefficient determined based on a transient operating condition coefficient, a second target EGR rate self-learning correction coefficient;

[0014] 1.3) If the water temperature sensor is detected as other faults, the corrected target EGR rate .

[0015] Further, 2) if it is detected that the electronic thermostat is faulty: when the electronic thermostat requests heating, is equal to the corrected target EGR rate when the water temperature sensor stuck fault occurs; otherwise, when the electronic thermostat does not request heating, the corrected target EGR rate .

[0016] Further, 3) if it is detected that the electronic water pump is faulty, the corrected target EGR rate .

[0017] Further, 4) if it is detected that the low-speed fan detection is faulty:

[0018] 4.1) When the low-speed fan detects that the speed is too high, i.e., the actual speed of the low-speed fan is higher than the first fan target speed, ;

[0019] 4.2) If the low-speed fan detects that the speed is too low or not rotating, i.e., the actual speed of the low-speed fan is lower than the second fan target speed,

[0020] 4.2.1) When the low-speed fan is not requested to be turned on, the corrected target EGR rate

[0021] ;

[0022] 4.2.2) When the low-speed fan is requested to be turned on, the corrected target EGR rate is as follows:

[0023]

[0024] wherein, is a third speed-load correction coefficient, is a first correction coefficient determined based on the engine water temperature difference, is a third target EGR rate self-learning correction coefficient;

[0025] 4.3) If the low speed fan detects other faults, then the corrected target EGR rate .

[0026] Further, 5) If the high speed fan detects a fault:

[0027] 5.1) If the high speed fan detects that the speed is too high, i.e. the actual speed of the high speed fan is higher than the third fan target speed, ;

[0028] 5.2) If the high speed fan detects that the speed is too low or not rotating, i.e. the actual speed of the high speed fan is lower than the fourth fan target speed,

[0029] 5.2.1) If the high speed fan is not requested to be on, then the corrected target EGR rate

[0030] ;

[0031] 5.2.2) If the high speed fan is requested to be on, then the corrected target EGR rate is as follows:

[0032]

[0033] wherein, is a fourth speed-load correction coefficient, is a second correction coefficient determined based on the engine water temperature difference, is a fourth target EGR rate self-learning correction coefficient;

[0034] 5.3) If the high speed fan detects other faults, then the corrected target EGR rate .

[0035] Further, in 1.1) If the water temperature sensor detects a too low fault,

[0036] a) If the following condition occurs then both are reduced,

[0037] wherein is the first target EGR rate self-learning correction coefficient of the last learning update;

[0038] If the update is not completed within this drive cycle, then , the third target EGR rate self-learning correction coefficient updated last time; otherwise no action;

[0039] if the update is not completed within this driving cycle, then , the fourth target EGR rate self-learning correction coefficient updated last time; otherwise no action;

[0040] b) if occurs, both

[0041] are increased,

[0042] if the update is not completed within this driving cycle, then ; otherwise no action;

[0043] if the update is not completed within this driving cycle, then ; otherwise no action;

[0044] C) in other cases, .

[0045] Further, in 1.2) if the water temperature sensor detects a stuck fault,

[0046] a) if occurs, is decreased,

[0047] wherein are the second target EGR rate self-learning correction coefficients updated last time, respectively;

[0048] if the update is not completed within this driving cycle, then ; otherwise no action;

[0049] if the update is not completed within this driving cycle, then ; otherwise no action;

[0050] b) if occurs, is decreased,

[0051] ; otherwise

[0052] c) if occurs, both are increased, ;

[0053] d) if occurs, is increased,

[0054] ;

[0055] if no update is completed within this drive cycle, ; ; otherwise no action is taken;

[0056] if no update is completed within this drive cycle, ; ; otherwise no action is taken;

[0057] e) otherwise, .

[0058] Further, in 4) if a low speed fan failure is detected,

[0059] a) if occurs, is decreased,

[0060] ;

[0061] b) if occurs, are both decreased,

[0062] ;

[0063] c) if occurs, are both increased, ;

[0064] d) if occurs, is increased,

[0065] ;

[0066] e) otherwise, .

[0067] Further, in 5) if a high speed fan failure is detected,

[0068] a) if occurs, decrease,

[0069] ;

[0070] b) if , then all decrease,

[0071] ;

[0072] c) if , then all increase, ;

[0073] d) if , then increase,

[0074] ;

[0075] e) otherwise, .

[0076] In a second aspect, an embodiment of the present application provides an EGR control system after failure of a cooling system, comprising:

[0077] a determining module configured to detect the cooling system, and determine a corrected target EGR rate after failure of each component after detecting that at least one component fails;

[0078] a control module configured to obtain a final target EGR rate by taking a minimum value of the corrected target EGR rates after failure of all components, limit the final target EGR rate to not exceed a target EGR rate before failure, and perform EGR control according to the final target EGR rate.

[0079] The EGR control method and system after failure of the cooling system provided by the present application can detect the cooling system, determine a corrected target EGR rate after failure of each component after detecting that at least one component fails, obtain a final target EGR rate by taking a minimum value of the corrected target EGR rates after failure of all components, limit the final target EGR rate to not exceed a target EGR rate before failure, and perform EGR control according to the final target EGR rate. Different target EGR rates can be optimized according to different failure conditions of different components of the cooling system, and the target EGR rates are constantly dynamically adjusted and updated, so that the occurrence of knock after failure is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0080] Figure 1 a flowchart of an EGR control method after failure of a cooling system provided by an embodiment of the present application;

[0081] Figure 2 A structural block diagram of an EGR control system after failure of a cooling system is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0082] 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 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 realize 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, for the sake of clarity and conciseness, the description below omits the description of well-known functions and structures.

[0083] In the case of no conflict, each embodiment of the present application and each feature in the embodiments can be combined with each other.

[0084] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0085] The terms used herein are only used to describe specific embodiments, and are not intended to limit the present application. 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 the terms "comprise" and / or "consist of", 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. The terms "connected" or "coupled" and / or similar terms are not limited to a physical or mechanical connection, but can include an electrical connection, whether direct or indirect.

[0086] Unless otherwise defined, 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 a meaning that is consistent with their meaning in the context of the relevant art and the present application, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0087] The present application provides an EGR control method after failure of a cooling system. Figure 1 A flowchart of an EGR control method after failure of a cooling system is provided for an embodiment of the present application, which comprises the following steps:

[0088] S100, detecting the cooling system, determining the corrected target EGR rate after failure of various components after detecting failure of at least one component.

[0089] In one embodiment, the cooling system includes the following components: water temperature sensor, electronic water pump, high and low speed fan, electronic thermostat. Water temperature sensor: reads the highest engine body water temperature, i.e. the coolant temperature at the water outlet. High and low speed fan: in the case that the thermostat-controlled water temperature cannot be met, the fan needs to be turned on to increase the external head-on wind cooling. Electronic thermostat: at low water temperature, the cooling system runs in internal circulation; at high water temperature, the cooling system runs in external circulation. Electronic water pump: traditional mechanical water pump, connected to the engine crankshaft by a belt pulley, engine speed determines water pump speed; electronic water pump can control water pump speed at the same engine speed.

[0090] Assuming that a fault occurs before the target EGR rate before the fault is which can be determined by the prior art CN202011247319.6 "A method and system for calculating a target EGR rate".

[0091] In one embodiment, 1) if a water temperature sensor failure is detected:

[0092] 1.1) If the water temperature sensor detects an excessively low failure, i.e. the water temperature sensor cannot detect the engine cooling water temperature in high working conditions, the corrected target EGR rate is as follows:

[0093]

[0094] wherein is the first speed and load correction coefficient, is the first optimized correction coefficient determined based on the transient condition coefficient, is the optimized correction coefficient determined based on the engine speed and the difference ratio of ignition efficiency, is the first target EGR rate self-learning correction coefficient.

[0095] is the basic correction coefficient determined based on the engine speed n and the load rho (fresh air intake density 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 real knock when the knock sensor fails, the basic correction coefficient determined based on the speed and load is smaller, so the possibility of knock is lower. The purpose of reducing the EGR rate is to reserve space for the engine in the working condition prone to knock, and once real knock occurs in the working condition prone to knock, the EGR rate can be increased to suppress the possibility of knock. The first speed and load correction coefficient is determined by querying the values corresponding to the engine speed n and the load rho in the following table.

[0096] Table 1 Corresponding relationship between first rotational speed load correction coefficient and engine rotational speed and load

[0097]

[0098] Transient condition coefficient is determined by engine rotational speed n and intake air pressure fluctuation rate is determined by engine rotational speed n and intake air pressure fluctuation rate is the difference between the maximum value and the minimum value of the intake air pressure coefficient in the last N sampling periods (a single sampling period is 10 ms) before N is related to engine rotational speed, the lower the rotational speed, the smaller the N value, the greater the rotational speed, the greater the N value, the main reason is that the lower the rotational speed, the more obvious the intake air pressure fluctuation, and the greater the sampling period cannot truly reflect the transient condition. The N value corresponding to different engine rotational speeds n is as follows:

[0099] Table 2 Corresponding relationship between N value and engine rotational speed

[0100] Engine speed n (rpm) 0 1000 1500 2000 2500 3000 4000 6000 N 0 4 6 8 9 10 12 15

[0101] is the throttle outlet intake air pressure, is the throttle outlet intake air pressure of the Nth sampling period, is the first-order low-pass filtered throttle outlet intake air pressure, is the filtered throttle outlet intake air pressure of the Nth sampling period.

[0102]

[0103] wherein, is the filtered throttle outlet intake air pressure of the N-1th sampling period, N = 1, 2, 3, is equal to the throttle outlet intake air pressure at the 0th sampling period ; the sampling period interval is 10 ms in this example. is the throttle outlet intake air pressure coefficient, (the number of cylinders of the engine in this example is 4, the calibration rotational speed of is 1000 rpm, The purpose of such setting is to normalize, without special calibration under different cylinder numbers and rotational speeds, only the calibration of the 4-cylinder engine and the rotational speed of 1000 rpm , so as to reduce the calibration test work), wherein is the number of engine cylinders, is the engine rotational speed, The throttle outlet intake pressure filtering coefficient is taken as 0.02 in the present example. The engine transient state working condition coefficient The engine speed n and the intake pressure fluctuation rate are inquired through the following table The corresponding value is determined, the change rate of the transient state working condition coefficient is limited to not more than ±0.1 / 10 ms in the above table data, and the final transient state working condition coefficient is obtained .

[0104] Table 3 Corresponding relationship between the transient state working condition coefficient, the engine speed and the intake pressure fluctuation rate

[0105]

[0106] The first optimization correction coefficient determined based on the transient state working condition coefficient The transient state working condition coefficient is inquired through the following table The corresponding value is determined, and the purpose of the setting is that, through experiments, it is shown that when the engine working condition jitter is slow, the engine water temperature has less risk of knock, and when the engine working condition jitter is severe, the water temperature has greater risk of knock.

[0107] Table 4 Corresponding relationship between the optimization correction coefficient determined based on the transient state working condition coefficient and the transient state working condition coefficient

[0108] #timg# 0 0.1 0.3 0.5 0.6 0.7 0.8 0.9 1 #timg# 1 1 1.01 1.04 1.1 1.12 1.15 1.25 1.4

[0109] Ignition efficiency difference ratio Determined by the ignition efficiency difference And the basic ignition efficiency , The engine basic ignition angle efficiency mentioned in the prior art (which can also be referred to as ignition efficiency), , The engine actual ignition angle efficiency. Therefore The smaller the ignition efficiency difference ratio is, the more likely it is to occur knock, if the engine water temperature sensor temperature is too low at this time, the more likely it is to occur knock, and the EGR rate needs to be further increased. The optimization correction coefficient determined based on the engine speed and the ignition efficiency difference ratio The engine speed and the ignition efficiency difference ratio corresponding value are inquired through the following table.

[0110] Table 5 Corresponding relationship between the optimization correction coefficient determined based on the engine speed and the ignition efficiency difference ratio and the engine speed and the ignition efficiency difference ratio

[0111]

[0112] The target EGR rate self-learning correction coefficient after the water temperature too low fault occurs, which has a default value of 0, can be continuously self-learned and updated, and can be saved after the vehicle is powered off.

[0113] 1.2) If the water temperature sensor is detected to be stuck, that is, the water temperature signal read by the water temperature sensor changes much more slowly than the actual situation, the corrected target EGR rate is as follows:

[0114]

[0115] wherein is a second speed-load correction coefficient, is a second optimization correction coefficient determined based on a transient operating condition coefficient, is a second target EGR rate self-learning correction coefficient.

[0116] wherein C1 is a first adjustment coefficient greater than 0 and not greater than 1, and in the present example, C1 is 0.95.

[0117] wherein C2 is a second adjustment coefficient greater than 0 and not greater than 1, and in the present example, C2 is 0.4. C2 is not greater than C1 because the water temperature is stuck and cannot identify the situation of water temperature transient change.

[0118] The target EGR rate self-learning correction coefficient after the water temperature sensor stuck fault occurs, which has a default value of 0, can be continuously self-learned and updated, and can be saved after the vehicle is powered off. Since the water temperature signal is stuck or changes slowly at this time, but the real water temperature can still be represented in part of the steady operating condition, the learning process is more specific and accurate than .

[0119] 1.3) If the water temperature sensor is detected to be stuck, the corrected target EGR rate .

[0120] In one embodiment, 2) if it is detected that the electronic thermostat has failed: when the electronic thermostat requests heating, is equal to the corrected target EGR rate when the water temperature sensor stuck fault occurs; otherwise, when the electronic thermostat does not request heating, the corrected target EGR rate .

[0121] In one embodiment, 3) if it is detected that the electronic water pump has failed, the corrected target EGR rate .

[0122] In one embodiment, 4) if it is detected that the low-speed fan detection has failed:

[0123] 4.1) When the low speed fan detects that the rotation speed is too high, i.e. the actual rotation 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), ;

[0124] 4.2) If the low speed fan detects that the rotation speed is too low or not rotating, i.e. the actual rotation 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),

[0125] 4.2.1) When the low speed fan is not requested to start, the corrected target EGR rate ;

[0126] 4.2.2) When the low speed fan is requested to start, the corrected target EGR rate is as follows:

[0127]

[0128] wherein, is a third rotation speed load correction coefficient, is a first correction coefficient determined based on the engine water temperature difference, is a third target EGR rate self-learning correction coefficient.

[0129] , is a basic correction coefficient no greater than under the same engine rotation speed n and the same engine intake density, mainly considering that the low speed fan is requested to start at this time and the engine water temperature is too high, at this time the risk of knock is higher, and reducing the EGR rate first makes it possible to improve the EGR rate for subsequent working conditions to suppress knock, C3 is a third adjustment coefficient greater than 0 and no greater than 1, and in the present example, C3 is 0.9.

[0130] is a correction coefficient determined based on the engine water temperature difference , the greater the water temperature difference is, the greater is to avoid the occurrence of knock. Wherein is the target engine water temperature, is the actual engine water temperature. In particular, if any fault occurs to the water temperature sensor at this time, is 0. The first correction coefficient determined based on the engine water temperature difference is determined by querying the value corresponding to the engine water temperature difference through the following table.

[0131] Table 6 Corresponding relationship between the first correction coefficient determined based on the engine water temperature difference and the engine water temperature difference

[0132] #timg# (°C) -2 0 2 4 6 8 12 18 20 #timg# 1 1.05 1.08 1.1 1.12 1.15 1.2 1.3 1.45

[0133] The target EGR rate self-learning correction coefficient after the low-speed fan failure occurs, and the default value is 0, which can be continuously self-learned and updated. The adjustment learning speed ratio is faster, and the risk of knock is greater.

[0134] 4.3) If the low-speed fan detects other failures, the modified target EGR rate .

[0135] In one embodiment, 5) if it is detected that the high-speed fan fails:

[0136] 5.1) When the high-speed fan detects that the rotation speed is too high, that is, the actual rotation speed of the high-speed fan is higher than the third fan target speed (determined according to the actual part characteristics of the high-speed fan), ;

[0137] 5.2) If the high-speed fan detects that the rotation speed is too low or not rotating, that is, the actual rotation speed of the high-speed fan is lower than the fourth fan target speed (determined according to the actual part characteristics of the high-speed fan),

[0138] 5.2.1) When the high-speed fan is not requested to start, the modified target EGR rate ;

[0139] 5.2.2) When the high-speed fan is requested to start, the modified target EGR rate is as follows:

[0140]

[0141] wherein, is the fourth rotation speed load correction coefficient, is the second correction coefficient determined based on the engine water temperature difference, is the fourth target EGR rate self-learning correction coefficient.

[0142] , is the basic correction coefficient not greater than under the same engine speed n and the same engine intake density, mainly considering that the high-speed fan is requested to start at this time, the water temperature is higher than when the low-speed fan starts, the risk of knock is greater, and reducing the EGR rate first makes it possible to improve the EGR rate for subsequent working conditions to suppress knock, C4 is the fourth adjustment coefficient greater than 0 and not greater than 1, and in this example, C4 is 0.8.

[0143] is the correction coefficient determined based on the engine water temperature difference , the greater the water temperature difference, the greater to avoid the occurrence of knock, is not less than . In particular, if any fault occurs in the water temperature sensor at this time is 0. The second correction coefficient determined based on the engine water temperature difference is determined by referring to the value corresponding to the engine water temperature difference in the following table.

[0144] Table 7 Correspondence between the second correction coefficient determined based on the engine water temperature difference and the engine water temperature difference

[0145] #timg# (°C) -2 0 2 4 6 8 12 18 20 #timg# 1 1.05 1.1 1.15 1.18 1.22 1.23 1.4 1.56

[0146] is the target EGR rate self-learning correction coefficient after the high-speed fan fault occurs, and its default value is 0, which can be continuously self-learned and updated. The adjustment learning speed is faster than , and the risk of knock is greater at this time.

[0147] 5.3) If the high-speed fan detects other faults, the modified target EGR rate .

[0148] S200, the minimum value of the modified target EGR rate after all component faults is obtained 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.

[0149] In one embodiment, in 1.1) if the water temperature sensor detects a too low fault,

[0150] a) If occurs, it indicates that the EGR rate requirement is high, and the occurrence of knock is avoided, then are all reduced, wherein is the first target EGR rate self-learning correction coefficient updated last time.

[0151] In particular, if the update of is not completed within this driving cycle, then , is the third target EGR rate self-learning correction coefficient updated last time; otherwise no action.

[0152] In particular, if the update of is not completed within this driving cycle, then , is the fourth target EGR rate self-learning correction coefficient updated last time; otherwise no action.

[0153] b) If , it is indicated that the EGR rate requirement is low and knocking is not likely to occur, so the lowering of the EGR rate is to be slowed down and the effect of EGR on improving fuel consumption is to be fully utilized, so the are both increased, .

[0154] In particular, if the update is not completed within this drive cycle, , then ; otherwise , no action is taken.

[0155] In particular, if the update is not completed within this drive cycle, , then ; otherwise , no action is taken.

[0156] c) in other cases, .

[0157] In one embodiment, in 1.2) if the water temperature sensor is detected as stuck fault,

[0158] a) if , it is indicated that the EGR rate requirement is high and knocking is likely to occur, so the lowering of the EGR rate is to be accelerated, is decreased, , where are the second target EGR rate self-learning correction coefficients of the last learning update, respectively.

[0159] In particular, if the update is not completed within this drive cycle, , then ; otherwise , no action is taken.

[0160] In particular, if the update is not completed within this drive cycle, , then ; otherwise , no action is taken.

[0161] b) if , it is indicated that the EGR rate requirement is high and knocking is likely to occur, so the lowering of the EGR rate is to be accelerated, is decreased, .

[0162] c) if , it is indicated that the EGR rate requirement is low and knocking is not likely to occur, so the lowering of the EGR rate is to be slowed down and the effect of EGR on improving fuel consumption is to be fully utilized, so the are both increased, .

[0163] d) if , it is explained that the EGR rate requirement is high, and knocking is likely to occur, so the EGR rate will be reduced, increased, .

[0164] In particular, if the update is not completed within this drive cycle, , the ; otherwise does not act.

[0165] In particular, if the update is not completed within this drive cycle, , the ; otherwise does not act.

[0166] e) in other cases, .

[0167] In one embodiment, in 4) if a low-speed fan failure is detected,

[0168] a) if , it is explained that the EGR rate requirement is high, and knocking is likely to occur, so the EGR rate will be reduced, increased, .

[0169] b) if , it is explained that the EGR rate requirement is high, and knocking is likely to occur, so the EGR rate will be reduced, increased, .

[0170] c) if , it is explained that the EGR rate requirement is low, and knocking is not likely to occur, so the EGR rate will be reduced, increased, .

[0171] d) if , it is explained that the EGR rate requirement is low, and knocking is not likely to occur, so the EGR rate will be reduced, increased, .

[0172] e) in other cases, .

[0173] The above is executed at most once per drive cycle.

[0174] In particular, if or is updated synchronously with the update of , then the above EGR rate is not updated in this driving cycle .

[0175] In one embodiment, in 5) if the high-speed fan failure is detected,

[0176] a) If , it means that the EGR rate requirement is high, and the occurrence of knock is avoided, then is reduced, .

[0177] b) If , it means that the EGR rate requirement is high, and the occurrence of knock is avoided, then are all reduced, .

[0178] c) If , it means that the EGR rate requirement is low, and the occurrence of knock is not easy, then the reduction of the EGR rate is slowed down, and the effect of EGR on improving fuel consumption is fully utilized, then are all increased, .

[0179] d) If , it means that the EGR rate requirement is low, and the occurrence of knock is not easy, then the reduction of the EGR rate is slowed down, and the effect of EGR on improving fuel consumption is fully utilized, then is increased, .

[0180] e) In other cases, .

[0181] The above is executed at most once in each driving cycle.

[0182] In particular, if or is updated synchronously in the update process , then the above EGR rate is not updated in this driving cycle .

[0183] The embodiment of the application can optimize different target EGR rates according to the fault occurrence of different parts of the cooling system, and constantly dynamically adjust and update, thereby effectively improving the occurrence of knock after the fault occurs.

[0184] The application also provides an EGR control system after a cooling system fault. Figure 2 A structural block diagram of an EGR control system after a cooling system fault is provided for the embodiment of the application, and the system comprises:

[0185] The determining module 11 is configured to determine the modified target EGR rate of each component after failure when the cooling system is detected to have at least one failed component.

[0186] The control module 12 is configured to take the minimum value of the modified target EGR rates of all the components after failure to obtain a final target EGR rate , limit the final target EGR rate to not exceed the target EGR rate before failure, and perform EGR control according to the final target EGR rate.

[0187] 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 of ordinary skill in the art will appreciate that a feature, characteristic or element described in connection with a particular embodiment can be used in conjunction with other embodiments unless otherwise explicitly stated. It will also be appreciated by those of ordinary skill in the art that various changes in form and details can be made without departing from the scope of the present disclosure as set forth in the following claims.

Claims

1. A cooling system failure EGR control method, characterized in that: The following steps are involved: S100, inspecting the cooling system, and upon detecting that at least one component has failed, determining a corrected target EGR rate for each component that has failed; S200 , taking the minimum value of the corrected target EGR rates after all components fail to obtain a final target EGR rate, limiting the final target EGR rate to not exceed the pre-failure 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, 1) if it is detected that the water temperature sensor is faulty: 1.1) If the water temperature sensor detects a low fault, the target EGR rate is corrected. 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 optimization correction coefficient determined based on the difference ratio between engine speed and ignition efficiency, is the first target EGR rate self-learning correction coefficient; 1.2) If the water temperature sensor is detected as stuck, the target EGR rate is corrected. as follows: in is the second speed load correction coefficient, is the second optimization correction coefficient determined based on the transient operating condition coefficient, is the second target EGR rate self-learning correction coefficient; 1.3) If the water temperature sensor detects other faults, the target EGR rate after correction .

3. The method according to claim 2, characterized in that 2) If a malfunction of the electronic thermostat is detected: When the electronic thermostat requests heating, Equal to the corrected target EGR rate when the water temperature sensor is stuck; otherwise, when the electronic thermostat does not request heating, the corrected target EGR rate .

4. The method according to claim 3, characterized in that 3) If the electronic water pump is detected to be faulty, the target EGR rate is corrected. .

5. The method according to claim 4, characterized in that 4) If a low-speed fan fault is detected: 4.1) 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, .

6. The method according to claim 5, characterized in that 4) If a low-speed fan fault is detected: 4.2) 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, 4.2.1) When the low speed fan is not requested to start, the corrected target EGR rate ； 4.2.2) When the low speed fan is requested to be turned on, the corrected target EGR rate as follows: in, is the third speed load correction coefficient, is the first correction coefficient determined based on the engine water temperature difference, It is the third target EGR rate self-learning correction coefficient.

7. The method according to claim 6, characterized in that 4) If a low-speed fan fault is detected: 4.3) If the low speed fan detects other faults, the target EGR rate will be corrected. .

8. The method according to claim 7, characterized in that 5) If a high-speed fan failure is detected: 5.1) 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, .

9. The method according to claim 8, characterized in that 5) If a high-speed fan failure is detected: 5.2) 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, 5.2.1) When the high-speed fan is not requested to start, the corrected target EGR rate ； 5.2.2) When the high speed fan is requested to be turned on, the corrected target EGR rate as follows: in, is the fourth speed load correction coefficient, is the second correction coefficient determined based on the engine water temperature difference, It is the fourth target EGR rate self-learning correction coefficient.

10. The method according to claim 9, characterized in that 5) If a high-speed fan failure is detected: 5.3) If the high-speed fan detects other faults, the target EGR rate will be corrected. .

11. The method according to claim 10, characterized in that In 1.1) If the water temperature sensor detects a low fault, a) If , then All are reduced, ,in The first target EGR rate self-learning correction coefficient updated in the last learning; If this driving cycle If the update is not completed, , The third target EGR rate self-learning correction coefficient updated in the last learning; otherwise No action; If this driving cycle If the update is not completed, , The fourth target EGR rate self-learning correction coefficient updated in the last learning; otherwise No action; b) If , then All increased, ； If this driving cycle If the update is not completed, ;otherwise No action; If this driving cycle If the update is not completed, ;otherwise No action; C) In other cases, .

12. The method according to claim 11, characterized in that In 1.2) If the water temperature sensor is detected as stuck, a) If , then To reduce, ,in They are the second target EGR rate self-learning correction coefficients updated in the last learning; If this driving cycle If the update is not completed, ;otherwise No action; If this driving cycle If the update is not completed, ;otherwise No action; b) If , then To reduce, ； c) If , then All increased, ; d) If , then To increase, ； If this driving cycle If the update is not completed, ;otherwise No action; If this driving cycle If the update is not completed, ;otherwise No action; e) In other cases, .

13. The method according to claim 12, characterized in that In 4) if a low speed fan fault 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, .

14. The method according to claim 13, characterized in that In 5) 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, .

15. An EGR control system after a cooling system failure, characterized in that: include: a determination module for detecting the cooling system and, upon detecting a failure of at least one component, determining a corrected target EGR rate after the failure of various components; The control module is used to obtain a minimum value of the corrected target EGR rate after all components fail to function to obtain a final target EGR rate, and to limit the final target EGR rate to not exceed the target EGR rate before the failure, and to perform EGR control according to the final target EGR rate.

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