Control method and apparatus for a flameout prevention exhaust gas recirculation system

Abstract

The application provides a control method and device for an anti-flameout exhaust gas recirculation (EGR) system, belonging to the field of engine control. According to a first corresponding relationship stored through pre-calibration, a post-intercooling theoretical temperature corresponding to an actual ambient temperature determined and obtained is obtained, and the cooling flow of an intercooler is adjusted accordingly, so that the post-intercooling actual temperature of engine intake air after being cooled by the intercooler is close to the post-intercooling theoretical temperature. However, there is still a temperature difference between the post-intercooling theoretical temperature and the post-intercooling actual temperature. According to a second corresponding relationship stored through pre-calibration, an EGR correction coefficient corresponding to the temperature difference and the engine load is determined. The EGR rate is corrected according to the EGR correction coefficient to obtain a target EGR rate, and the EGR valve is controlled according to the target EGR rate, so that engine flameout caused by engine condensate liquid water is avoided, and the stable operation of the engine is ensured.

Description

Technical Field

[0001] The present application relates to the field of engine control, and in particular to a method and device for controlling an anti-stall exhaust gas recirculation system. Background Art

[0002] In order to reduce vehicle fuel consumption and meet higher vehicle emission standards, an EGR (Exhaust Gas Recirculation) system that recirculates exhaust gas to the engine is widely used in vehicles equipped with gasoline engines.

[0003] The EGR system can use molecules with relatively large specific heat capacity such as carbon dioxide and water to increase the specific heat ratio of the mixture in the cylinder, thereby improving the Otto thermal efficiency of the engine. At the same time, carbon dioxide and water can also lower the temperature in the cylinder and reduce the tendency of knock, which can not only improve combustion efficiency but also reduce nitrogen oxide emissions.

[0004] However, in a turbocharged gasoline engine, when EGR operates at high load, the intake manifold pressure increases, and the dew point of water vapor also increases accordingly, which easily condenses into liquid water. When the condensed liquid water exceeds the critical value for stable combustion in the cylinder, the engine combustion becomes unstable and stalls, which in turn leads to excessive emissions. Summary of the Invention

[0005] In view of this, the present application provides an anti-stall exhaust gas recirculation (EGR) system control method, which can avoid engine stall and ensure stable engine operation.

[0006] In one aspect, the present application provides a method for controlling an anti-stall exhaust gas recirculation (EGR) system, the method comprising:

[0007] Get the actual ambient temperature.

[0008] According to a first correspondence between the actual ambient temperature and a pre-stored ambient temperature and a theoretical temperature after intercooling, a theoretical temperature after intercooling corresponding to the actual ambient temperature is determined.

[0009] Adjust the cooling flow of the intercooler according to the theoretical temperature after intercooling.

[0010] The engine load and the actual post-intercooling temperature of the engine intake air after being intercooled by the intercooler are obtained.

[0011] Determine the temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling.

[0012] The engine load and the temperature difference are used as inputs to a pre-stored second correspondence between the engine load, the temperature difference and the EGR correction coefficient to determine the EGR correction coefficient corresponding to the engine load and the temperature difference.

[0013] The target EGR rate is obtained by correcting the theoretical EGR rate according to the EGR correction coefficient.

[0014] The EGR valve is controlled to reach the target EGR rate.

[0015] Optionally, before obtaining the actual ambient temperature, the method further comprises:

[0016] The initial value of the test ambient temperature and the test temperature after intercooling are both set as a first preset temperature threshold.

[0017] The test ambient temperature is increased by a first preset temperature step, and the test temperature after intercooling corresponding to each test ambient temperature is determined, until the test ambient temperature reaches a second preset temperature threshold.

[0018] According to each test ambient temperature and the test temperature after intercooling corresponding to each test ambient temperature, a first correspondence between the ambient temperature and the theoretical temperature after intercooling is obtained, and the first correspondence is stored.

[0019] The test temperature after intercooling corresponding to each test ambient temperature is determined by:

[0020] The initial value of the engine speed is set as a minimum preset engine speed, and the EGR valve is controlled to keep the EGR rate maximum.

[0021] The engine speed is increased by a preset engine speed step, and the test temperature after intercooling corresponding to each engine speed is determined, until the engine speed reaches a maximum preset engine speed.

[0022] The maximum test temperature after intercooling is determined from the test temperature after intercooling corresponding to each engine speed.

[0023] The test temperature after intercooling corresponding to each engine speed is determined by:

[0024] The test temperature after intercooling is increased by a second preset temperature step, until the engine does not misfire, and the test temperature after intercooling at this time is taken as the test temperature after intercooling.

[0025] Optionally, before obtaining the actual ambient temperature, the method further comprises:

[0026] The initial value of the test temperature difference is set as a first preset temperature difference threshold, the engine speed is set as an ideal preset engine speed threshold corresponding to the maximum EGR rate, the engine load is set as a first preset load threshold, and the EGR rate is set as an ideal EGR rate corresponding to the engine load.

[0027] Increase the test temperature difference by a third preset temperature step, and determine an EGR correction coefficient corresponding to each test temperature difference, until the test temperature difference reaches a second preset temperature difference threshold.

[0028] According to each test temperature difference, the EGR correction coefficient corresponding to each test temperature difference, and the engine load corresponding to the EGR correction coefficient, a second correspondence relationship between the engine load, the temperature difference, and the EGR correction coefficient is obtained, and the second correspondence relationship is stored.

[0029] The method further comprises:

[0030] Decrease the engine load by a preset load step, and determine an EGR correction coefficient corresponding to each engine load, until the engine load reaches a preset load threshold.

[0031] The method further comprises:

[0032] Decrease the EGR rate by a preset EGR rate step, until the engine does not appear misfire, and determine the ratio between the test EGR rate and the ideal EGR rate at this time as the EGR correction coefficient.

[0033] Optionally, after the EGR correction coefficient corresponding to the temperature difference is determined, the method further comprises:

[0034] The EGR correction coefficient corresponding to the temperature difference is taken as a first EGR correction coefficient.

[0035] Obtain the intake manifold temperature.

[0036] According to a third correspondence relationship between the intake manifold temperature and the EGR correction coefficient stored in advance, determine a second EGR correction coefficient corresponding to the intake manifold temperature.

[0037] The minimum value between the first EGR correction coefficient and the second EGR correction coefficient is taken as a final EGR correction coefficient.

[0038] According to the final EGR correction coefficient, correct the theoretical EGR rate to obtain a target EGR rate.

[0039] Control the EGR valve to reach the target EGR rate.

[0040] Optionally, after the EGR correction coefficient corresponding to the temperature difference is determined, the method further comprises:

[0041] The EGR correction coefficient corresponding to the temperature difference is taken as a first EGR correction coefficient.

[0042] Obtain the atmospheric pressure.

[0043] A third EGR correction coefficient corresponding to the atmospheric pressure is determined based on a pre-stored fourth correspondence between the atmospheric pressure and the EGR correction coefficient.

[0044] The product of the first EGR correction coefficient and the third EGR correction coefficient is used as the final EGR correction coefficient.

[0045] The theoretical EGR rate is corrected according to the final EGR correction coefficient to obtain the target EGR rate.

[0046] Control the EGR valve to achieve the target EGR rate.

[0047] On the other hand, the present application also provides an anti-stall exhaust gas recirculation (EGR) system control device, the device comprising:

[0048] The acquisition module is configured to acquire the actual ambient temperature.

[0049] The determination module is configured to determine the post-intercooling theoretical temperature corresponding to the actual ambient temperature according to the actual ambient temperature and a pre-stored first correspondence between the ambient temperature and the post-intercooling theoretical temperature.

[0050] The control module is configured to adjust the cooling flow of the intercooler according to the theoretical temperature after the intercooler.

[0051] The acquisition module is further configured to acquire the engine load and an actual post-intercooling temperature of the engine intake air after being intercooled by the intercooler.

[0052] The determination module is further configured to determine a temperature difference between a theoretical temperature after intercooling and an actual temperature after intercooling.

[0053] The determination module is further configured to take the engine load and the temperature difference as inputs into a pre-stored second correspondence between the engine load, the temperature difference and the EGR correction coefficient, and determine the EGR correction coefficient corresponding to the engine load and the temperature difference.

[0054] The determination module is further configured to correct the theoretical EGR rate according to the EGR correction coefficient to obtain a target EGR rate.

[0055] The control module is further configured to control the EGR valve to achieve a target EGR rate.

[0056] Optionally, the device further comprises:

[0057] The setting module is configured to set the initial values ​​of the test environment temperature and the temperature after cooling during the test as the first preset temperature threshold.

[0058] The determination module is further configured to increase the test environment temperature by a first preset temperature step and determine the post-cooling temperature corresponding to each test environment temperature until the test environment temperature reaches a second preset temperature threshold.

[0059] The determination module is further configured to obtain a first corresponding relationship between the ambient temperature and the theoretical temperature after intercooling according to each test ambient temperature and the test temperature after intercooling corresponding to each test ambient temperature, and store the first corresponding relationship.

[0060] The setting module is further configured to set an initial value of the engine speed to a minimum preset speed, and control the EGR valve to maintain the EGR rate at a maximum.

[0061] The determination module is further configured to increase the engine speed according to a preset speed step and determine a test intercooling intermediate temperature corresponding to each engine speed until the engine speed reaches a maximum preset speed.

[0062] The determination module is further configured to determine a maximum test mid-cold intermediate temperature from the test mid-cold intermediate temperatures corresponding to each engine speed.

[0063] The determination module is further configured to increase the test intercooling temperature by a second preset temperature step until the engine does not misfire, and use the test intercooling temperature at this time as the test intercooling intermediate temperature.

[0064] Optionally, the device further comprises:

[0065] The setting module is configured to set the initial value of the test temperature difference to a first preset temperature difference threshold, set the engine speed to an ideal preset speed threshold corresponding to the maximum EGR rate, set the engine load to a first preset load threshold, and set the EGR rate to an ideal EGR rate corresponding to the engine load.

[0066] The determination module is further configured to increase the test temperature difference by a third preset temperature step and determine an EGR correction coefficient corresponding to each test temperature difference until the test temperature difference reaches a second preset temperature difference threshold.

[0067] The determination module is further configured to obtain a second correspondence between the engine load, the temperature difference, and the EGR correction coefficient based on each test temperature difference, the EGR correction coefficient corresponding to each test temperature difference, and the engine load corresponding to the EGR correction coefficient, and store the second correspondence.

[0068] The determination module is further configured to reduce the engine load by a preset load step size and determine an EGR correction factor corresponding to each engine load until the engine load reaches a preset load threshold.

[0069] The determining module is further configured to decrease the EGR rate by a preset EGR rate step until the engine does not misfire, and determine a ratio between the test EGR rate at this time and the ideal EGR rate as an EGR correction coefficient.

[0070] Alternatively, the determining module is further configured to determine the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient after determining the EGR correction coefficient corresponding to the temperature difference.

[0071] The obtaining module is further configured to obtain an intake manifold temperature.

[0072] The determining module is further configured to determine a second EGR correction coefficient corresponding to the intake manifold temperature according to a third correspondence relationship between the intake manifold temperature and the EGR correction coefficient stored in advance.

[0073] The determining module is further configured to take a minimum value between the first EGR correction coefficient and the second EGR correction coefficient as a final EGR correction coefficient.

[0074] The determining module is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain a target EGR rate.

[0075] The control module is further configured to control the EGR valve to reach the target EGR rate.

[0076] Alternatively, the determining module is further configured to determine the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient after determining the EGR correction coefficient corresponding to the temperature difference.

[0077] The obtaining module is further configured to obtain an atmospheric pressure.

[0078] The determining module is further configured to determine a third EGR correction coefficient corresponding to the atmospheric pressure according to a fourth correspondence relationship between the atmospheric pressure and the EGR correction coefficient stored in advance.

[0079] The determining module is further configured to take a product between the first EGR correction coefficient and the third EGR correction coefficient as a final EGR correction coefficient.

[0080] The determining module is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain a target EGR rate.

[0081] The control module is further configured to control the EGR valve to reach the target EGR rate.

[0082] According to the first corresponding relationship stored in advance, the post-intercooling theoretical temperature corresponding to the actual environment temperature obtained is determined, and the cooling flow of the intercooler is adjusted accordingly, so that the post-intercooling actual temperature of the engine intake air after being cooled in the intercooler is close to the post-intercooling theoretical temperature. However, there is still a temperature difference between the post-intercooling theoretical temperature and the post-intercooling actual temperature. According to the second corresponding relationship stored in advance, the EGR correction coefficient corresponding to the temperature difference and the engine load is determined, the target EGR rate is obtained by correcting the EGR rate according to the EGR correction coefficient, and the EGR valve is controlled according to the target EGR rate, so as to avoid engine stall caused by engine condensate liquid water and ensure smooth operation of the engine. BRIEF DESCRIPTION OF DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0084] Figure 1 The architecture diagram of the anti-stall exhaust gas recirculation EGR system provided by the embodiments of the present application is shown in the figure.

[0085] Figure 2 The flowchart of the anti-stall exhaust gas recirculation EGR system control method provided by the embodiments of the present application is shown in the figure.

[0086] Figure 3 Another flowchart of the anti-stall exhaust gas recirculation EGR system control method provided by the embodiments of the present application is shown in the figure.

[0087] Figure 4 Another flowchart of the anti-stall exhaust gas recirculation EGR system control method provided by the embodiments of the present application is shown in the figure.

[0088] Figure 5 The architecture diagram of the anti-stall exhaust gas recirculation EGR system control device provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0089] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0090] First, the application scenarios related to the embodiments of the present application will be introduced:

[0091] Low-pressure EGR is a key technology for reducing fuel consumption in supercharged gasoline engines and improving the thermal efficiency of the engine. EGR contains a large amount of water vapor, which condenses into liquid water when the temperature drops. When a large amount of liquid water enters the engine cylinder, it will cause abnormal combustion, misfire, and thus worsen emissions. The present invention prevents misfires by controlling the degree of EGR condensation. The core principle is to determine the intercooler temperature through test calibration. The intercooler temperature is achieved by the intercooler low-temperature cooling system. However, the low-temperature cooling system also cools other components of the vehicle, such as the motor and motor controller. At the same time, its physical characteristics cause its response cycle to be long, which leads to low-frequency fluctuations in the difference between the actual intercooler temperature and the required intercooler temperature. To address this fluctuation, the EGR is corrected through test calibration according to the actual intercooler temperature, so as to suppress the combustion misfire problem caused by excessive condensation.

[0092] The embodiment of the present application provides a flameout prevention exhaust gas recirculation EGR system control method for controlling the flameout prevention exhaust gas recirculation EGR system. To better understand the flameout prevention exhaust gas recirculation EGR system control method, the entire system is first described: Figure 1 As shown, the entire anti-stall exhaust gas recirculation (EGR) system is divided into three parts: the engine air path and body, the intake air intercooler low-temperature cooling system, and the ECU control system.

[0093] The engine air circuit and body include: air filter 101, EGR mixing valve 102, supercharger compressor 103, intake water-cooled intercooler 104, throttle 106, intake manifold 108, engine body 109, supercharger turbine 110, three-way catalytic converter 111, EGR cooler 112, and EGR valve 120.

[0094] The intake air intercooler low-temperature cooling system includes: an electronic water pump 114 , a low-temperature radiator 115 , an electronically controlled three-way valve 116 , and a motor MCU 117 .

[0095] The ECU control system includes: an ECU controller 119 , an ambient temperature sensor 100 , an EGR valve pressure difference sensor 113 , a motor MCU temperature sensor 118 , an intake air intercooler temperature sensor 105 , and an intake manifold temperature sensor 107 .

[0096] The anti-stall exhaust gas recirculation EGR system control method provided in the embodiment of the present application can be implemented by the vehicle controller, such as Figure 2 As shown, it includes steps S201, S202, S203, S204, S205, S206, S207 and S208, wherein:

[0097] In step S201 , the actual ambient temperature is obtained.

[0098] In step S202, a post-intercooling theoretical temperature corresponding to the actual ambient temperature is determined according to a first correspondence relationship between the actual ambient temperature and the pre-stored ambient temperature and post-intercooling theoretical temperature.

[0099] In step S203, the cooling flow of the intercooler is adjusted according to the post-intercooling theoretical temperature.

[0100] In step S204, the engine load and the post-intercooling actual temperature of the engine intake air cooled in the intercooler are obtained.

[0101] In step S205, a temperature difference between the post-intercooling theoretical temperature and the post-intercooling actual temperature is determined.

[0102] In step S206, the engine load and the temperature difference are taken as inputs into a second correspondence relationship between the pre-stored engine load, temperature difference and EGR correction coefficient, to determine an EGR correction coefficient corresponding to the engine load and the temperature difference.

[0103] In step S207, the theoretical EGR rate is corrected according to the EGR correction coefficient to obtain a target EGR rate.

[0104] In step S208, the EGR valve is controlled to reach the target EGR rate.

[0105] Before obtaining the actual ambient temperature in step S201, the first correspondence relationship between the ambient temperature and the post-intercooling theoretical temperature can also be pre-calibrated and stored, and the step of calibrating and storing the first correspondence relationship comprises:

[0106] The initial value of the test ambient temperature and the test post-intercooling temperature are both set to a first preset temperature threshold.

[0107] The test ambient temperature is increased by a first preset temperature step, and a test post-intercooling temperature corresponding to each test ambient temperature is determined, until the test ambient temperature reaches a second preset temperature threshold.

[0108] According to each test ambient temperature and the test post-intercooling temperature corresponding to each test ambient temperature, a first correspondence relationship between the ambient temperature and the post-intercooling theoretical temperature is obtained, and the first correspondence relationship is stored.

[0109] The test post-intercooling temperature corresponding to each test ambient temperature is determined, comprising:

[0110] The initial value of the engine speed is set to a minimum preset speed, and the EGR rate is controlled to remain maximum.

[0111] The engine speed is increased by a preset speed step, and a test post-intercooling intermediate temperature corresponding to each engine speed is determined until the engine speed reaches a maximum preset speed.

[0112] The maximum test post-intercooling intermediate temperature is determined from the test post-intercooling intermediate temperatures corresponding to each engine speed.

[0113] The determination of the test post-intercooling intermediate temperature corresponding to each engine speed comprises:

[0114] The test post-intercooling temperature is increased by a second preset temperature step until misfire of the engine does not occur, and the test post-intercooling temperature at this time is taken as the test post-intercooling intermediate temperature.

[0115] In some optional embodiments, as shown in Figure 3 The step of pre-calibrating the first correspondence between the ambient temperature and the post-intercooling theoretical temperature can specifically comprise:

[0116] In step S301, the test ambient temperature is set to a first preset temperature threshold, and the test ambient humidity is set to 100%.

[0117] The first preset temperature threshold corresponds to an acceptable minimum ambient temperature.

[0118] In step S302, it is determined whether the test ambient temperature reaches a second preset temperature threshold.

[0119] The second preset temperature threshold corresponds to an acceptable maximum ambient temperature.

[0120] In the case where the determination result of step S302 is no, step S303 is entered, in which an initial value of the engine speed is set to a minimum preset speed.

[0121] In step S304, it is determined whether the engine speed exceeds a maximum speed for EGR operation.

[0122] In the case where the determination result of step S304 is no, step S305 is entered, in which an initial value of the test post-intercooling temperature is set to the first preset temperature threshold, and the EGR valve is controlled to keep the EGR rate maximum.

[0123] In some optional embodiments, in step S305, the post-intercooling temperature is equal to the ambient temperature, and the EGR valve is controlled to keep the EGR rate maximum.

[0124] In step S306, the test post-intercooling temperature is increased by a second preset temperature step, and the engine is controlled to run stably for 20 minutes, and then the throttle opening is kept maximum for 5 seconds.

[0125] In step S307, it is determined whether the engine has stalled, that is, whether the engine has stalled in step S306.

[0126] If the judgment result of step S307 is yes, that is, the engine has stalled in step S306, then return to step S306 again, increase the test mid-cooling temperature by the second preset temperature step again, control the engine to run steadily for 20 minutes, and then keep the throttle opening at the maximum for 5 seconds.

[0127] If the judgment result of step S307 is no, that is, the engine does not stall in step S306, the process proceeds to step S308. In step S308, the test intermediate cooling temperature at this time is used as the test intermediate cooling temperature corresponding to the current speed.

[0128] In step S309 , the intermediate temperature after cooling during the test corresponding to the current rotational speed is compared with the intermediate temperature after cooling during the test corresponding to the previous rotational speed, and the maximum value is obtained.

[0129] In step S310 , the engine speed is increased by a preset speed step.

[0130] After step S310, return to step S304 to determine whether the engine speed exceeds the maximum speed of EGR operation. After determining that the engine speed exceeds the maximum speed of EGR operation, jump out of the loop of step S304-step S310 and enter step S311.

[0131] It is understandable that, by using the loop of step S304 to step S310, the engine speed can be increased according to the preset speed step, and the intermediate temperature after cooling during the test corresponding to each engine speed can be determined until the engine speed reaches the maximum preset speed.

[0132] By using the loop of step S306-step S307 nested in step S304-step S310, the test post-cooling temperature can be increased by the second preset temperature step until the engine does not misfire, and the test post-cooling temperature at this time is used as the test post-cooling intermediate temperature.

[0133] After exiting the loop of step S304 to step S310 and entering step S311, in step S311, the intermediate temperature after intercooling in the test is used as the theoretical temperature after intercooling corresponding to the current test environment temperature.

[0134] It is understandable that, in step S311 , after obtaining the theoretical temperature after intercooling, the theoretical temperature after intercooling and the ambient temperature can be stored in correspondence, thereby obtaining a set of the theoretical temperature after intercooling and the ambient temperature.

[0135] In step S312, the test environment temperature is increased by a first preset temperature step. After step S312, the process returns to step S302 to determine whether the test environment temperature reaches a second preset temperature threshold.

[0136] It is understandable that the loop S302-S312 can increase the test environment temperature by a first preset temperature step and determine the test post-cooling temperature corresponding to each test environment temperature until the test environment temperature reaches a second preset temperature threshold.

[0137] If the judgment result of step S302 is yes, that is, after the test environment temperature reaches the second preset temperature threshold, the loop S302-S312 is jumped out, and finally a first corresponding relationship between the ambient temperature and the theoretical temperature after intercooling is obtained according to each test environment temperature and the test intercooling temperature corresponding to each test environment temperature, and the first corresponding relationship is stored.

[0138] The first correspondence can be shown in Table 1:

[0139] Table 1

[0140] Ambient temperature (℃) -5 10 25 35 45 Theoretical temperature after intercooling (℃) 28 37 45 55 65

[0141] In some optional embodiments, before obtaining the actual ambient temperature in step S201, a second correspondence between the temperature difference and the EGR correction coefficient may be pre-calibrated and stored. The steps of calibrating and storing the second correspondence include:

[0142] The initial value of the test temperature difference is set to the first preset temperature difference threshold, the engine speed is set to the ideal preset speed threshold corresponding to the maximum EGR rate, the engine load is set to the first preset load threshold, and the EGR rate is set to the ideal EGR rate corresponding to the engine load.

[0143] The test temperature difference is increased by a third preset temperature step, and an EGR correction coefficient corresponding to each test temperature difference is determined until the test temperature difference reaches a second preset temperature difference threshold.

[0144] According to each test temperature difference, the EGR correction coefficient corresponding to each test temperature difference, and the engine load corresponding to the EGR correction coefficient, a second corresponding relationship among the engine load, the temperature difference, and the EGR correction coefficient is obtained and stored.

[0145] The EGR correction coefficient corresponding to each test temperature difference is determined as follows:

[0146] The engine load is reduced in preset load steps, and an EGR correction factor corresponding to each engine load is determined until the engine load reaches a preset load threshold.

[0147] Determining the EGR correction factor corresponding to each engine load includes:

[0148] The EGR rate is reduced by a preset EGR rate step size until the engine no longer misfires. The ratio between the test EGR rate and the ideal EGR rate at this time is determined as the EGR correction coefficient.

[0149] In some optional embodiments, such as Figure 4 As shown, the step of pre-calibrating and storing the second correspondence between the temperature difference and the EGR correction coefficient may specifically include:

[0150] In step S401 , the test environment humidity is set to 100%, and the engine speed is set to an ideal preset speed threshold corresponding to the maximum EGR rate.

[0151] In step S402, the initial value of the test temperature difference is set to a first preset temperature difference threshold.

[0152] In some optional embodiments, the first preset temperature difference threshold may be an acceptable minimum temperature difference.

[0153] In step S403 , the engine load is set to a first preset load threshold.

[0154] In some optional embodiments, the first preset load threshold may be an acceptable maximum load.

[0155] In step S404 , the EGR rate is set to an ideal EGR rate corresponding to the engine load.

[0156] In step S405, the EGR rate is reduced by a preset EGR rate step size, the engine is stably operated for 20 minutes, and the engine is controlled to operate in a steady state for 20 minutes, and then the throttle opening is kept at the maximum for 5 seconds.

[0157] In step S406, it is determined whether the engine has stalled. In other words, it is determined whether the engine has stalled in step S405.

[0158] If the judgment result of step S406 is yes, that is, the engine has stalled, then return to step S405, reduce the EGR rate by the preset EGR rate step, and the engine runs stably for 20 minutes, and control the engine to run in a steady state for 20 minutes, then keep the throttle opening at the maximum and continue for 5 seconds, and use step S406 again to determine whether the engine has stalled.

[0159] If the judgment result of step S406 is no, that is, the engine has not stalled, then the process proceeds to step S407.

[0160] In step S407 , the ratio between the test EGR rate at this time and the ideal EGR rate is determined as the EGR correction coefficient.

[0161] It can be understood that by using the loop of steps S405-S406 + step S407, the EGR rate can be reduced at a preset EGR rate step size until the engine does not misfire, and the ratio between the test EGR rate and the ideal EGR rate at this time is determined as the EGR correction coefficient and stored.

[0162] In step S408 , the engine load is reduced by a preset load step size.

[0163] In step S409 , it is determined whether the engine load reaches a preset load threshold.

[0164] If the determination result of step S406 is no, that is, the engine load has not been reduced to reach the preset load threshold, the process returns to step S404 .

[0165] By looping through steps S404-S409, the engine load can be reduced in preset load steps and the EGR correction factor corresponding to each engine load can be determined until the engine load reaches a preset load threshold, which can be an acceptable minimum load.

[0166] In step S410, the test temperature difference is increased by a third preset temperature step.

[0167] In step S411, it is determined whether the test temperature difference is greater than a second preset temperature difference threshold.

[0168] If the judgment result of step S411 is no, that is, the test temperature difference is not greater than the second preset temperature difference threshold, then return to step S403.

[0169] By looping through steps S403-S411, the test temperature difference can be increased by a third predetermined temperature step size, and the EGR correction coefficient corresponding to each test temperature difference can be determined until the test temperature difference reaches a second predetermined temperature difference threshold. The second predetermined temperature difference threshold can be a maximum acceptable temperature difference.

[0170] If the result of the step S411 is yes, i.e. the test temperature difference is greater than the second preset temperature difference threshold, the calibration process of the second corresponding relationship is ended. By the cycle of the steps S403-S411, the second corresponding relationship between the engine load, the temperature difference and the EGR correction coefficient can be obtained according to each test temperature difference, the EGR correction coefficient corresponding to each test temperature difference and the engine load corresponding to the EGR correction coefficient, and the second corresponding relationship is stored. It can be understood that the second corresponding relationship is a two-dimensional relationship, taking the temperature difference and the engine load as inputs and the EGR correction coefficient as output.

[0171] It can be understood that the engine load can be represented by the engine charge efficiency. The charge efficiency refers to the ratio of the actual fresh air mass inhaled into the cylinder of the internal combustion engine in each working cycle to the theoretical air mass filling the cylinder working volume under the intake port state. It is an important parameter for evaluating the perfection degree of the actual air exchange process of the internal combustion engine. The higher the charge efficiency is, the more air charge into a certain cylinder volume per cycle, and the power and torque of the internal combustion engine are large, and the power performance is good.

[0172] The second corresponding relationship between the engine load, the temperature difference and the EGR correction coefficient can be shown in Table 2:

[0173] Table 2

[0174]

[0175] In some optional embodiments, the influence of the intake manifold temperature on the engine stall can also be considered. After the step S206, i.e. determining the EGR correction coefficient corresponding to the temperature difference, the method further comprises:

[0176] The EGR correction coefficient corresponding to the temperature difference is taken as the first EGR correction coefficient.

[0177] The intake manifold temperature is obtained.

[0178] According to a third corresponding relationship between the intake manifold temperature and the EGR correction coefficient stored in advance, a second EGR correction coefficient corresponding to the intake manifold temperature is determined.

[0179] The minimum value between the first EGR correction coefficient and the second EGR correction coefficient is taken as the final EGR correction coefficient.

[0180] The theoretical EGR rate is corrected according to the final EGR correction coefficient to obtain a target EGR rate.

[0181] The EGR valve is controlled to reach the target EGR rate.

[0182] In some optional embodiments, the influence of atmospheric pressure on engine stall can also be considered, so as to adapt to plateau environment. After the EGR correction coefficient corresponding to the temperature difference is determined in step S206, the method further includes:

[0183] The EGR correction coefficient corresponding to the temperature difference is taken as the first EGR correction coefficient.

[0184] The atmospheric pressure is obtained.

[0185] According to a fourth correspondence relationship between the atmospheric pressure and the EGR correction coefficient stored in advance, a third EGR correction coefficient corresponding to the atmospheric pressure is determined.

[0186] The product between the first EGR correction coefficient and the third EGR correction coefficient is taken as the final EGR correction coefficient.

[0187] The theoretical EGR rate is corrected according to the final EGR correction coefficient to obtain a target EGR rate.

[0188] The EGR valve is controlled to reach the target EGR rate.

[0189] In some optional embodiments, the influences of the intake manifold temperature and the atmospheric pressure on engine stall can also be considered at the same time, and the product between the minimum value between the first EGR correction coefficient and the second EGR correction coefficient and the third EGR correction coefficient is taken as the final EGR correction coefficient.

[0190] By using the anti-stall EGR system control method provided in the application, the after-intercooling theoretical temperature corresponding to the actual environment temperature obtained is determined according to the first correspondence relationship stored in advance, and the cooling flow of the intercooler is adjusted accordingly, so that the after-intercooling actual temperature of the engine intake air after being cooled in the intercooler approaches the after-intercooling theoretical temperature. However, there is still a temperature difference between the after-intercooling theoretical temperature and the after-intercooling actual temperature. Further, the EGR correction coefficient corresponding to the temperature difference and the engine load is determined according to the second correspondence relationship stored in advance, the EGR rate is corrected according to the EGR correction coefficient to obtain a target EGR rate, and the EGR valve is controlled according to the target EGR rate, so as to avoid engine stall caused by engine condensate liquid water and ensure smooth operation of the engine.

[0191] The application also provides an anti-stall EGR system control device, which can be arranged in a vehicle controller, as shown in FIG. 5. Figure 5 The device includes:

[0192] The obtaining module 501 is configured to obtain an actual environment temperature.

[0193] The determining module 502 is configured to determine the theoretical temperature after intercooling corresponding to the actual ambient temperature according to a first correspondence relationship between the actual ambient temperature and the pre-stored ambient temperature and the theoretical temperature after intercooling.

[0194] The control module 503 is configured to adjust the cooling flow of the intercooler according to the theoretical temperature after intercooling.

[0195] The obtaining module 501 is further configured to obtain the engine load and the actual temperature after intercooling of the engine intake air after intercooling.

[0196] The determining module 502 is further configured to determine the temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling.

[0197] The determining module 502 is further configured to bring the engine load and the temperature difference as inputs into a second correspondence relationship between the pre-stored engine load, the temperature difference and the EGR correction coefficient, and determine the EGR correction coefficient corresponding to the engine load and the temperature difference.

[0198] The determining module 502 is further configured to correct the theoretical EGR rate according to the EGR correction coefficient to obtain the target EGR rate.

[0199] The control module 503 is further configured to control the EGR valve to reach the target EGR rate.

[0200] Optionally, the device further comprises:

[0201] The setting module 504 is configured to set the initial value of the test ambient temperature and the test temperature after intercooling as a first preset temperature threshold.

[0202] The determining module 502 is further configured to increase the test ambient temperature by a first preset temperature step, and determine the test temperature after intercooling corresponding to each test ambient temperature, until the test ambient temperature reaches a second preset temperature threshold.

[0203] The determining module 502 is further configured to obtain the first correspondence relationship between the ambient temperature and the theoretical temperature after intercooling according to each test ambient temperature and the test temperature after intercooling corresponding to each test ambient temperature, and store the first correspondence relationship.

[0204] The setting module 504 is further configured to set the initial value of the engine speed as a minimum preset speed, and control the EGR valve to keep the EGR rate maximum.

[0205] The determining module 502 is further configured to increase the engine speed by a preset speed step, and determine the test temperature after intercooling corresponding to each engine speed, until the engine speed reaches a maximum preset speed.

[0206] The determining module 502 is further configured to determine a maximum test post-intercooling intermediate temperature from the test post-intercooling intermediate temperatures corresponding to each engine speed.

[0207] The determining module 502 is further configured to increase the test post-intercooling temperature by a second preset temperature step until misfire does not occur in the engine, and take the test post-intercooling temperature at this time as the test post-intercooling intermediate temperature.

[0208] The setting module 504 is further configured to set an initial value of the test temperature difference to a first preset temperature difference threshold, set the engine speed to an ideal preset speed threshold corresponding to the maximum EGR rate, set the engine load to a first preset load threshold, and set the EGR rate to an ideal EGR rate corresponding to the engine load.

[0209] The determining module 502 is further configured to increase the test temperature difference by a third preset temperature step, and determine an EGR correction coefficient corresponding to each test temperature difference, until the test temperature difference reaches the second preset temperature difference threshold.

[0210] The determining module 502 is further configured to obtain a second correspondence relationship among the engine load, the temperature difference, and the EGR correction coefficient according to each test temperature difference, the EGR correction coefficient corresponding to each test temperature difference, and the engine load corresponding to the EGR correction coefficient, and store the second correspondence relationship.

[0211] The determining module 502 is further configured to decrease the engine load by a preset load step, and determine an EGR correction coefficient corresponding to each engine load, until the engine load reaches the preset load threshold.

[0212] The determining module 502 is further configured to decrease the EGR rate by a preset EGR rate step until misfire does not occur in the engine, and determine a ratio between the test EGR rate and the ideal EGR rate at this time as the EGR correction coefficient.

[0213] Optionally, the determining module 502 is further configured to, after determining the EGR correction coefficient corresponding to the temperature difference, take the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient.

[0214] The obtaining module 501 is further configured to obtain an intake manifold temperature.

[0215] The determining module 502 is further configured to determine a second EGR correction coefficient corresponding to the intake manifold temperature according to a third correspondence relationship between the intake manifold temperature and the EGR correction coefficient stored in advance.

[0216] The determination module 502 is further configured to use a minimum value between the first EGR correction factor and the second EGR correction factor as the final EGR correction factor.

[0217] The determination module 502 is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain a target EGR rate.

[0218] The control module 503 is further configured to control the EGR valve to achieve a target EGR rate.

[0219] Optionally, after determining the EGR correction coefficient corresponding to the temperature difference, the determination module 502 is further configured to use the EGR correction coefficient corresponding to the temperature difference as the first EGR correction coefficient.

[0220] The acquisition module 501 is further configured to acquire atmospheric pressure.

[0221] The determination module 502 is further configured to determine a third EGR correction coefficient corresponding to the atmospheric pressure according to a pre-stored fourth correspondence between the atmospheric pressure and the EGR correction coefficient.

[0222] The determination module 502 is further configured to use a product of the first EGR correction factor and the third EGR correction factor as a final EGR correction factor.

[0223] The determination module 502 is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain a target EGR rate.

[0224] The control module 503 is further configured to control the EGR valve to achieve a target EGR rate.

[0225] The anti-stall exhaust gas recirculation (EGR) system control device provided by the present application is used to determine the theoretical temperature after intercooling corresponding to the actual ambient temperature obtained based on a first correspondence relationship that is pre-calibrated and stored, and adjust the cooling flow of the intercooler accordingly, so that the actual temperature after intercooling of the engine intake air after intercooling through the intercooler is close to the theoretical temperature after intercooling. However, there will still be a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling. Further, based on a second correspondence relationship that is pre-calibrated and stored, an EGR correction coefficient corresponding to the temperature difference and the engine load is determined, the EGR rate is corrected according to the EGR correction coefficient to obtain a target EGR rate, and the EGR valve is controlled according to the target EGR rate, thereby avoiding engine stall due to condensed liquid water in the engine and ensuring smooth operation of the engine.

[0226] In this application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0227] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the application being indicated by the following claims.

[0228] It is to be understood that the application is not limited to the precise construction herein disclosed and shown in the drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should only be limited by the claims appended hereto.

[0229] The above merely is for the convenience of the people in the art to understand the technical solutions of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flameout prevention exhaust gas recirculation (EGR) system control method, characterized in that: The method comprises: Get the actual ambient temperature; Determining the post-intercooling theoretical temperature corresponding to the actual ambient temperature according to a first correspondence between the actual ambient temperature and a pre-stored first correspondence between the ambient temperature and the post-intercooling theoretical temperature; adjusting the cooling flow of the intercooler according to the theoretical temperature after intercooling, so that the actual temperature of the engine intake air after intercooling through the intercooler approaches the theoretical temperature after intercooling; Obtaining engine load and actual temperature after intercooling; determining a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling; Substituting the engine load and the temperature difference as input into a pre-stored second correspondence relationship between the engine load, the temperature difference, and the EGR correction coefficient, and determining the EGR correction coefficient corresponding to the engine load and the temperature difference; Correcting the theoretical EGR rate according to the EGR correction coefficient to obtain a target EGR rate; The EGR valve is controlled to achieve the target EGR rate.

2. The flameout prevention exhaust gas recirculation (EGR) system control method according to claim 1, characterized in that: Before obtaining the actual ambient temperature, the method further includes: Setting the initial values ​​of the test environment temperature and the temperature after cooling during the test as the first preset temperature threshold; Increasing the test environment temperature by a first preset temperature step, and determining a post-cooling temperature corresponding to each test environment temperature, until the test environment temperature reaches a second preset temperature threshold; According to each of the test environment temperatures and the test post-intercooling temperature corresponding to each of the test environment temperatures, the first corresponding relationship between the environment temperature and the post-intercooling theoretical temperature is obtained, and the first corresponding relationship is stored. The step of determining the post-cooling temperature corresponding to each of the test environment temperatures includes: The initial value of the engine speed is set to the minimum preset speed, and the EGR valve is controlled to keep the EGR rate at the maximum; Increasing the engine speed according to a preset speed step size, and determining a post-cooling intermediate temperature corresponding to each engine speed until the engine speed reaches a maximum preset speed; determining the maximum test intercooled intermediate temperature from the test intercooled intermediate temperatures corresponding to each of the engine speeds; The determining of the intermediate temperature after cooling in the test corresponding to each engine speed includes: The test post-cooling temperature is increased with a second preset temperature step length until the engine does not misfire, and the test post-cooling temperature at this time is used as the test post-cooling intermediate temperature.

3. The flameout prevention exhaust gas recirculation (EGR) system control method according to claim 1, characterized in that: Before obtaining the actual ambient temperature, the method further includes: Setting the initial value of the test temperature difference to a first preset temperature difference threshold, setting the engine speed to an ideal preset speed threshold corresponding to the maximum EGR rate, setting the engine load to a first preset load threshold, and setting the EGR rate to an ideal EGR rate corresponding to the engine load; Increasing the test temperature difference by a third preset temperature step, and determining the EGR correction coefficient corresponding to each test temperature difference, until the test temperature difference reaches a second preset temperature difference threshold; obtaining a second correspondence between the engine load, the temperature difference, and the EGR correction coefficient based on each of the test temperature differences, the EGR correction coefficient corresponding to each of the test temperature differences, and the engine load corresponding to the EGR correction coefficient, and storing the second correspondence; Wherein, determining the EGR correction coefficient corresponding to each of the test temperature differences includes: reducing the engine load in a preset load step size and determining the EGR correction coefficient corresponding to each engine load until the engine load reaches a preset load threshold, Wherein, determining the EGR correction coefficient corresponding to each engine load includes: The EGR rate is reduced by a preset EGR rate step size until the engine does not misfire, and the ratio between the test EGR rate at this time and the ideal EGR rate is determined as the EGR correction coefficient.

4. The flameout prevention exhaust gas recirculation (EGR) system control method according to claim 1, characterized in that: After determining the EGR correction coefficient corresponding to the temperature difference, the method further includes: using the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient; Get the intake manifold temperature; determining a second EGR correction coefficient corresponding to the intake manifold temperature based on a pre-stored third correspondence between the intake manifold temperature and the EGR correction coefficient; taking the minimum value between the first EGR correction coefficient and the second EGR correction coefficient as the final EGR correction coefficient; Correcting the theoretical EGR rate according to the final EGR correction coefficient to obtain the target EGR rate; The EGR valve is controlled to achieve the target EGR rate.

5. The flameout prevention exhaust gas recirculation (EGR) system control method according to claim 1, characterized in that: After determining the EGR correction coefficient corresponding to the temperature difference, the method further includes: using the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient; Get atmospheric pressure; determining a third EGR correction coefficient corresponding to the atmospheric pressure according to a pre-stored fourth correspondence between the atmospheric pressure and the EGR correction coefficient; multiplying the first EGR correction coefficient and the third EGR correction coefficient as a final EGR correction coefficient; Correcting the theoretical EGR rate according to the final EGR correction coefficient to obtain the target EGR rate; The EGR valve is controlled to achieve the target EGR rate. 6.An anti-stall exhaust gas recirculation EGR system control device, characterized in that: The device comprises: An acquisition module is configured to acquire actual ambient temperature; a determining module configured to determine the post-intercooling theoretical temperature corresponding to the actual ambient temperature based on the actual ambient temperature and a pre-stored first correspondence between the ambient temperature and the post-intercooling theoretical temperature; a control module configured to adjust a cooling flow rate of the intercooler according to the post-intercooling theoretical temperature so that the actual post-intercooling temperature of the engine intake air after intercooling by the intercooler approaches the post-intercooling theoretical temperature; The acquisition module is further configured to acquire the engine load and the actual temperature after the intercooler; The determination module is further configured to determine a temperature difference between the post-intercooling theoretical temperature and the post-intercooling actual temperature; The determination module is further configured to take the engine load and the temperature difference as inputs into a pre-stored second correspondence relationship between the engine load, the temperature difference, and the EGR correction coefficient, and determine the EGR correction coefficient corresponding to the engine load and the temperature difference; The determination module is further configured to correct the theoretical EGR rate according to the EGR correction coefficient to obtain a target EGR rate; The control module is further configured to control the EGR valve to achieve the target EGR rate.

7. The flameout prevention exhaust gas recirculation (EGR) system control device according to claim 6, characterized in that: The device further comprises: A setting module is configured to set the initial values ​​of the test environment temperature and the temperature after cooling during the test to a first preset temperature threshold; The determining module is further configured to increase the test environment temperature by a first preset temperature step and determine a post-cooling temperature corresponding to each test environment temperature until the test environment temperature reaches a second preset temperature threshold; The determining module is further configured to obtain the first corresponding relationship between the ambient temperature and the theoretical temperature after intercooling according to each of the test ambient temperatures and the test temperature after intercooling corresponding to each of the test ambient temperatures, and store the first corresponding relationship. The setting module is further configured to set the initial value of the engine speed to a minimum preset speed, and control the EGR valve to maintain the EGR rate at a maximum; The determining module is further configured to increase the engine speed according to a preset speed step size and determine a post-cooling intermediate temperature corresponding to each engine speed until the engine speed reaches a maximum preset speed; The determining module is further configured to determine a maximum test intercooled intermediate temperature from the test intercooled intermediate temperatures corresponding to each of the engine speeds. The determination module is further configured to increase the test post-cooling temperature by a second preset temperature step size until the engine does not misfire, and use the test post-cooling temperature at this time as the test post-cooling intermediate temperature.

8. The flameout prevention exhaust gas recirculation (EGR) system control device according to claim 6, characterized in that: The device further comprises: a setting module configured to set an initial value of the test temperature difference to a first preset temperature difference threshold, set the engine speed to an ideal preset speed threshold corresponding to the maximum EGR rate, set the engine load to a first preset load threshold, and set the EGR rate to an ideal EGR rate corresponding to the engine load; The determination module is further configured to increase the test temperature difference by a third preset temperature step and determine the EGR correction coefficient corresponding to each test temperature difference until the test temperature difference reaches a second preset temperature difference threshold; The determination module is further configured to obtain a second correspondence between the engine load, the temperature difference, and the EGR correction coefficient based on each of the test temperature differences, the EGR correction coefficient corresponding to each of the test temperature differences, and the engine load corresponding to the EGR correction coefficient, and store the second correspondence. The determination module is further configured to reduce the engine load by a preset load step size and determine the EGR correction factor corresponding to each engine load until the engine load reaches a preset load threshold. The determination module is further configured to reduce the EGR rate by a preset EGR rate step size until the engine does not misfire, and determine a ratio between the test EGR rate at this time and the ideal EGR rate as the EGR correction coefficient.

9. The flameout prevention exhaust gas recirculation (EGR) system control device according to claim 6, characterized in that: The determination module is further configured to, after determining the EGR correction coefficient corresponding to the temperature difference, use the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient; The acquisition module is further configured to acquire the intake manifold temperature; The determination module is further configured to determine a second EGR correction coefficient corresponding to the intake manifold temperature based on a pre-stored third correspondence between the intake manifold temperature and the EGR correction coefficient; The determination module is further configured to use a minimum value between the first EGR correction factor and the second EGR correction factor as a final EGR correction factor; The determination module is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain the target EGR rate; The control module is further configured to control the EGR valve to achieve the target EGR rate.

10. The flameout prevention exhaust gas recirculation (EGR) system control device according to claim 6, characterized in that: After determining the EGR correction coefficient corresponding to the temperature difference, the determination module is further configured to use the EGR correction coefficient corresponding to the temperature difference as a first EGR correction coefficient; The acquisition module is further configured to acquire atmospheric pressure; The determination module is further configured to determine a third EGR correction coefficient corresponding to the atmospheric pressure based on a pre-stored fourth correspondence between the atmospheric pressure and the EGR correction coefficient; The determination module is further configured to use the product of the first EGR correction factor and the third EGR correction factor as a final EGR correction factor; The determination module is further configured to correct the theoretical EGR rate according to the final EGR correction coefficient to obtain the target EGR rate; The control module is further configured to control the EGR valve to achieve the target EGR rate.

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