Anti-flameout exhaust gas recirculation system control method and device

Abstract

The invention provides an anti-flameout exhaust gas recirculation (EGR) system control method and device, and belongs to the field of engine control. According to a pre-calibrated and stored first corresponding relation, an inter-cooled theoretical temperature corresponding to an actual environment temperature is determined and obtained, and the cooling flow of an intercooler is correspondingly adjusted; according to the method, the actual temperature after intercooling of engine inlet air subjected to intercooling through an intercooler is made to be close to the theoretical temperature after intercooling, but a temperature difference value still exists between the theoretical temperature after intercooling and the actual temperature after intercooling, and an EGR correction coefficient corresponding to the temperature difference value and the engine load is further determined according to a pre-calibrated and stored second corresponding relation; and the EGR rate is corrected according to the EGR correction coefficient to obtain the target EGR rate, and the EGR valve is controlled according to the target EGR rate, so that engine flameout caused by condensed liquid water of the engine is avoided, and 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 make vehicle emissions meet higher standards, an EGR (Exhaust Gas Re-circulation) system that allows exhaust gas to flow back 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 knock tendency, which can not only improve combustion efficiency but also reduce nitrogen oxide emissions.

[0004] However, in a supercharged gasoline engine, when EGR is working at high load, the intake manifold pressure increases, and the dew point of water vapor also increases accordingly, which can easily condense liquid water. When the condensed liquid water exceeds the critical value that can be tolerated for stable combustion in the cylinder, the engine combustion becomes unstable and flameout occurs, which will lead 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 stalling and ensure stable engine operation.

[0006] On the one hand, the present application provides an anti-stall exhaust gas recirculation (EGR) system control method, the method comprising:

[0007] Get the actual ambient temperature.

[0008] According to a first corresponding relationship 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 taken as inputs into a pre-stored second correspondence relationship 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 theoretical EGR rate is corrected according to the EGR correction coefficient to obtain the target EGR rate.

[0014] Control the EGR valve to achieve the target EGR rate.

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

[0016] The initial values ​​of the test environment temperature and the temperature after cooling during the test are both set as the first preset temperature threshold.

[0017] The test environment temperature is increased with a first preset temperature step length, and the test post-cooling temperature corresponding to each test environment temperature is determined until the test environment temperature reaches a second preset temperature threshold.

[0018] According to each test environment temperature and the test post-intermediate cooling temperature corresponding to each test environment temperature, a first corresponding relationship between the environment temperature and the post-intermediate cooling theoretical temperature is obtained, and the first corresponding relationship is stored.

[0019] Among them, determining the post-cooling temperature in the test corresponding to each test environment temperature includes:

[0020] 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.

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

[0022] The maximum test intermediate post-cooling temperature is determined from the test intermediate post-cooling temperatures corresponding to each engine speed.

[0023] The determination of the intermediate temperature after cooling in the test corresponding to each engine speed includes:

[0024] The test intercooling temperature is increased with a second preset temperature step length until the engine does not misfire, and the test intercooling temperature at this time is used as the test intercooling intermediate temperature.

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

[0026] 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.

[0027] The test temperature difference is increased with a third preset temperature step length, 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.

[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 corresponding relationship among the engine load, the temperature difference and the EGR correction coefficient is obtained and stored.

[0029] Among them, determining the EGR correction coefficient corresponding to each test temperature difference includes:

[0030] The engine load is reduced in a preset load step size, and an EGR correction factor corresponding to each engine load is determined until the engine load reaches a preset load threshold.

[0031] Wherein, determining the EGR correction factor corresponding to each engine load includes:

[0032] The EGR rate is reduced with 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.

[0033] Optionally, after determining the EGR correction coefficient corresponding to the temperature difference, the method further includes:

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

[0035] Get the intake manifold temperature.

[0036] A second EGR correction coefficient corresponding to the intake manifold temperature is determined according to a pre-stored third correspondence between the intake manifold temperature and the EGR correction coefficient.

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

[0038] The theoretical EGR rate is corrected according to the final EGR correction coefficient to obtain the target EGR rate.

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

[0040] Optionally, after determining the EGR correction coefficient corresponding to the temperature difference, the method further includes:

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

[0042] Get the atmospheric pressure.

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

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

[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 first corresponding relationship between the pre-stored 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 the intercooling and an actual temperature after the 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 also 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 post-intercooling theoretical temperature according to each test ambient temperature and the test post-intercooling temperature corresponding to each test ambient temperature, and store the first corresponding relationship.

[0060] 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 keep 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 after-intermediate temperature from the test mid-cold after-intermediate temperatures corresponding to each engine speed.

[0063] The determination module is further configured to increase the test intercooling temperature at a second preset temperature step size 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 also configured to obtain a second corresponding relationship 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 corresponding relationship.

[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 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 the ratio between the test EGR rate and the ideal EGR rate at this time as the EGR correction coefficient.

[0070] Optionally, the determination module is further configured to use the EGR correction coefficient corresponding to the temperature difference as the first EGR correction coefficient after determining the EGR correction coefficient corresponding to the temperature difference.

[0071] The acquisition module is further configured to acquire an intake manifold temperature.

[0072] The determination module is further configured to determine a second EGR correction coefficient corresponding to the intake manifold temperature according to a pre-stored third correspondence between the intake manifold temperature and the EGR correction coefficient.

[0073] The determination module 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.

[0074] The determination 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 also configured to control the EGR valve to achieve a target EGR rate.

[0076] Optionally, 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 the first EGR correction coefficient.

[0077] The acquisition module is further configured to acquire atmospheric pressure.

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

[0079] The determination module 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.

[0080] The determination 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 also configured to control the EGR valve to achieve a target EGR rate.

[0082] By adopting the anti-stall exhaust gas recirculation (EGR) system control method provided by the present application, the theoretical temperature after intercooling corresponding to the actual ambient temperature obtained is determined according to a first corresponding relationship that is pre-calibrated and stored, and the cooling flow of the intercooler is adjusted accordingly, so that the actual temperature after intercooling of the engine intake air after intercooling by the intercooler is close to the theoretical temperature after intercooling, but there will still be a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling, and further according to a second corresponding 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 stalling due to condensed liquid water in the engine and ensuring smooth operation of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0084] Figure 1 An architectural diagram of an anti-stall exhaust gas recirculation (EGR) system provided in an embodiment of the present application;

[0085] Figure 2 A flow chart of an anti-stall exhaust gas recirculation (EGR) system control method provided in an embodiment of the present application;

[0086] Figure 3 Another flow chart of the anti-stall exhaust gas recirculation (EGR) system control method provided in an embodiment of the present application;

[0087] Figure 4 Another flow chart of the anti-stall exhaust gas recirculation (EGR) system control method provided in an embodiment of the present application;

[0088] Figure 5 This is an architectural diagram of the anti-stall exhaust gas recirculation (EGR) system control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0089] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0090] First, the application scenarios involved in the embodiments of the present application are 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. When the temperature drops, the water vapor will condense into liquid water. When a large amount of liquid water enters the engine cylinder, it will cause abnormal combustion, misfire, and then worsen emissions. The present invention prevents misfires by controlling the degree of EGR condensation water. The core principle is to determine the intercooler temperature through test calibration. The intercooler temperature is achieved by the intercooler low-temperature cooling system, but the low-temperature cooling system also needs to cool other parts of the vehicle, such as the motor and motor controller. At the same time, its physical characteristics cause its response cycle to be longer, which leads to the difference between the actual intercooler temperature and the required intercooler temperature. The difference has low-frequency volatility. In view of this volatility, the EGR is corrected by test calibration according to the actual intercooler temperature to suppress the combustion misfire problem caused by excessive condensed water.

[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 gas circuit and body, the intake intercooler low-temperature cooling system, and the ECU control system.

[0093] The engine air circuit and body include: an air filter 101, an EGR mixing valve 102, a supercharger compressor 103, an intake water-cooled intercooler 104, a throttle valve 106, an intake manifold 108, an engine body 109, a supercharger turbine 110, a three-way catalytic converter 111, an EGR cooler 112, and an EGR valve 114.

[0094] The intake 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 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 a 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, the post-intercooling theoretical temperature corresponding to the actual ambient temperature is determined according to the actual ambient temperature and a first corresponding relationship between the pre-stored ambient temperature and the post-intercooling theoretical temperature.

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

[0100] In step S204, the engine load and the actual temperature after intercooling of the engine intake air after being intercooled by the intercooler are obtained.

[0101] In step S205 , a temperature difference between a theoretical temperature after intercooling and an actual temperature after intercooling is determined.

[0102] In step S206, the engine load and the temperature difference are taken as input into a pre-stored second correspondence relationship 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.

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

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

[0105] Before obtaining the ambient temperature in step S201, a first corresponding relationship between the ambient temperature and the theoretical temperature after intercooling may be pre-calibrated and stored. The steps of calibrating and storing the first corresponding relationship include:

[0106] The initial values ​​of the test environment temperature and the temperature after cooling during the test are both set as the first preset temperature threshold.

[0107] The test environment temperature is increased with a first preset temperature step length, and the test post-cooling temperature corresponding to each test environment temperature is determined until the test environment temperature reaches a second preset temperature threshold.

[0108] According to each test environment temperature and the test post-intermediate cooling temperature corresponding to each test environment temperature, a first corresponding relationship between the environment temperature and the post-intermediate cooling theoretical temperature is obtained, and the first corresponding relationship is stored.

[0109] Among them, determining the post-cooling temperature in the test corresponding to each test environment temperature includes:

[0110] 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.

[0111] The engine speed is increased according to the preset speed step, and the intermediate temperature after the test cooling corresponding to each engine speed is determined until the engine speed reaches the maximum preset speed.

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

[0113] The determination of the intermediate temperature after cooling in the test corresponding to each engine speed includes:

[0114] The test intercooling temperature is increased with a second preset temperature step length until the engine does not misfire, and the test intercooling temperature at this time is used as the test intercooling intermediate temperature.

[0115] In some optional embodiments, such as Figure 3 As shown, the step of pre-calibrating the first corresponding relationship between the ambient temperature and the theoretical temperature after intercooling may specifically include:

[0116] In step S301, the test environment temperature is set to a first preset temperature threshold, and the test environment 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 environment temperature reaches a second preset temperature threshold.

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

[0120] When the judgment result of step S302 is no, the process proceeds to step S303, in which the initial value of the engine speed is set to the minimum preset speed.

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

[0122] When the judgment result of step S304 is no, the process proceeds to step S305. In step S305, the initial value of the post-cooling temperature in the test is set as the first preset temperature threshold, and the EGR valve is controlled to keep the EGR rate at the maximum.

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

[0124] In step S306, the post-cooling temperature in the test is increased by a second preset temperature step, and the engine is controlled to run in a steady state for 20 minutes, and then the throttle opening is kept at the 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, increase the post-cooling temperature in the test 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 is not stalled in step S306, the process proceeds to step S308, in which 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 in the test corresponding to the current rotation speed is compared with the intermediate temperature after cooling in the test corresponding to the previous rotation speed, and the maximum value is taken.

[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 cycle of step S304-step S310, the engine speed can be increased according to the preset speed step, and the intermediate temperature after cooling in 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 jumping out of the loop of step S304 - 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 correspondingly, so as to obtain 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 cycle S302-S312 can 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.

[0137] When 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 the first corresponding relationship between the environment 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 corresponding relationship 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 ambient temperature in step S201, a second corresponding relationship between the temperature difference and the EGR correction coefficient may be pre-calibrated and stored. The steps of calibrating and storing the second corresponding relationship 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 with a third preset temperature step length, 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] Among them, determining the EGR correction coefficient corresponding to each test temperature difference includes:

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

[0147] Wherein, determining the EGR correction factor corresponding to each engine load includes:

[0148] The EGR rate is reduced with 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.

[0149] In some optional embodiments, such as Figure 4 As shown, the step of pre-calibrating and storing the second corresponding relationship 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 maintained at the maximum for 5 seconds.

[0157] In step S406, it is determined whether the engine is stalled. In other words, it is determined whether the engine is 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, the engine runs stably for 20 minutes, and controls the engine to run steadily 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 is 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 utilizing the loop of steps S405-S406 + step S407, it is possible to reduce the EGR rate by 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.

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

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

[0165] By using the cycle of steps S404-S409, it is possible to reduce the engine load in a preset load step and determine the EGR correction factor corresponding to each engine load until the engine load reaches a preset load threshold, which may 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 using the cycle of steps S403-S411, it is possible to increase the test temperature difference by the third preset temperature step and determine the EGR correction coefficient corresponding to each test temperature difference until the test temperature difference reaches the second preset temperature difference threshold. The second preset temperature difference threshold may be the maximum acceptable temperature difference.

[0170] If the judgment result of step S411 is yes, that is, the test temperature difference is greater than the second preset temperature difference threshold, the calibration process of the second correspondence relationship is terminated. By using the loop of steps S403-S411, it is possible to obtain the second correspondence relationship between 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. It can be understood that the second correspondence relationship is a two-dimensional relationship, with the temperature difference and the engine load as input and the EGR correction coefficient as output.

[0171] It is understandable that the engine load can be represented by the engine charging efficiency. The charging efficiency refers to the ratio of the mass of fresh air actually sucked into the engine cylinder in each working cycle of the internal combustion engine to the theoretical mass of air that fills the cylinder working volume in the intake port state. It is an important parameter for evaluating the degree of perfection of the actual ventilation process of the internal combustion engine. The higher the charging efficiency, the more air is charged into a certain cylinder volume per cycle, the greater the power and torque of the internal combustion engine, and the better the dynamic performance.

[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 flameout may also be considered. In step S206, after determining the EGR correction coefficient corresponding to the temperature difference, the method further includes:

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

[0177] Get the intake manifold temperature.

[0178] A second EGR correction coefficient corresponding to the intake manifold temperature is determined according to a pre-stored third correspondence between the intake manifold temperature and the EGR correction coefficient.

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

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

[0181] Control the EGR valve to achieve the target EGR rate.

[0182] In some optional embodiments, the effect of atmospheric pressure on engine flameout may also be considered to adapt to the plateau environment. In step S206, after determining the EGR correction coefficient corresponding to the temperature difference, the method further includes:

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

[0184] Get the atmospheric pressure.

[0185] A third EGR correction coefficient corresponding to the atmospheric pressure is determined according to a pre-stored fourth correspondence relationship between the atmospheric pressure and the EGR correction coefficient.

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

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

[0188] Control the EGR valve to achieve the target EGR rate.

[0189] In some optional embodiments, the effects of intake manifold temperature and atmospheric pressure on engine flameout may also be considered simultaneously, and the product of the minimum value between the first EGR correction coefficient and the second EGR correction coefficient and the third EGR correction coefficient is used as the final EGR correction coefficient.

[0190] By adopting the anti-stall exhaust gas recirculation (EGR) system control method provided by the present application, the theoretical temperature after intercooling corresponding to the actual ambient temperature obtained is determined according to a first corresponding relationship that is pre-calibrated and stored, and the cooling flow of the intercooler is adjusted accordingly, so that the actual temperature after intercooling of the engine intake air after intercooling by the intercooler is close to the theoretical temperature after intercooling, but there will still be a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling, and further according to a second corresponding 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 stalling due to condensed liquid water in the engine and ensuring smooth operation of the engine.

[0191] The embodiment of the present application also provides an anti-stall exhaust gas recirculation EGR system control device, which can be set in a vehicle controller, such as Figure 5 As shown, the device comprises:

[0192] The acquisition module 501 is configured to acquire the actual ambient temperature.

[0193] The determination module 502 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 relationship between the ambient temperature and the post-intercooling theoretical temperature.

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

[0195] The acquisition module 501 is further configured to acquire the engine load and the actual post-intercooling temperature of the engine intake air after being intercooled by the intercooler.

[0196] The determination module 502 is further configured to determine a temperature difference between the post-intercooling theoretical temperature and the post-intercooling actual temperature.

[0197] The determination module 502 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.

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

[0199] The control module 503 is also configured to control the EGR valve to achieve a target EGR rate.

[0200] Optionally, the device further comprises:

[0201] The setting module 504 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.

[0202] The determination module 502 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.

[0203] The determination module 502 is further configured to obtain a first corresponding relationship between the ambient temperature and the post-intercooling theoretical temperature according to each test ambient temperature and the test post-intercooling temperature corresponding to each test ambient temperature, and store the first corresponding relationship.

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

[0205] The determination module 502 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.

[0206] The determination module 502 is further configured to determine a maximum test mid-cold after-intermediate temperature from the test mid-cold after-intermediate temperatures corresponding to each engine speed.

[0207] The determination module 502 is further configured to increase the test intercooling temperature at a second preset temperature step size until the engine does not misfire, and use the test intercooling temperature at this time as the test intercooling intermediate temperature.

[0208] The setting module 504 is also 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.

[0209] The determination 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 a second preset temperature difference threshold.

[0210] The determination module 502 is further configured to obtain a second corresponding relationship between 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 corresponding relationship.

[0211] The determination module 502 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.

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

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

[0214] The acquisition module 501 is further configured to acquire the intake manifold temperature.

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

[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 also 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 factor corresponding to the atmospheric pressure according to a pre-stored fourth correspondence relationship between the atmospheric pressure and the EGR correction factor.

[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 also configured to control the EGR valve to achieve a target EGR rate.

[0225] By adopting the anti-stall exhaust gas recirculation (EGR) system control device provided by the present application, the theoretical temperature after intercooling corresponding to the actual ambient temperature is determined according to a first corresponding relationship that is pre-calibrated and stored, and the cooling flow of the intercooler is adjusted accordingly, so that the actual temperature after intercooling of the engine intake air after intercooling by the intercooler is close to the theoretical temperature after intercooling, but there will still be a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling, and further according to a second corresponding 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 stalling due to condensed liquid water in the engine and ensuring smooth operation of the engine.

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

[0227] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only.

[0228] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

[0229] The above is only to facilitate those skilled in the art to understand the technical solution of this application and is not intended to limit this application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this 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 corresponding relationship between the actual ambient temperature and a pre-stored ambient temperature and the post-intercooling theoretical temperature; adjusting the cooling flow of the intercooler according to the theoretical temperature after intercooling; Acquiring an engine load and an actual temperature of the engine intake air after being intercooled by the intercooler; Determining a temperature difference between the theoretical temperature after intercooling and the actual temperature after intercooling; Taking the engine load and the temperature difference as input into a pre-stored second correspondence relationship among 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 ambient temperature, the method further includes: The initial values ​​of the test environment temperature and the temperature after cooling during the test are both set as the first preset temperature threshold value; Increasing the test environment temperature with a first preset temperature step length, and determining a post-cooling temperature corresponding to each of the test environment temperatures, 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. Wherein, the determining of the post-cooling temperature in the test corresponding to each of the test environment temperatures comprises: 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 length, 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 intercooling intermediate temperature from the test intercooling intermediate temperatures corresponding to each of the engine speeds, Wherein, the determining of the intermediate temperature after cooling in the test corresponding to each engine speed comprises: 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 of the test temperature differences, until the test temperature difference reaches a second preset temperature difference threshold; According to each of the test temperature differences, the EGR correction coefficients respectively corresponding to each of the test temperature differences, and the engine load corresponding to the EGR correction coefficient, the second corresponding relationship among the engine load, the temperature difference, and the EGR correction coefficient is obtained, and the second corresponding relationship is stored. Wherein, the determining of the EGR correction coefficient corresponding to each of the test temperature differences comprises: reducing the engine load in a preset load step and determining the EGR correction factor corresponding to each engine load until the engine load reaches a preset load threshold, Wherein, determining the EGR correction coefficient corresponding to each of the engine loads comprises: The EGR rate is reduced with 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.

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 according to a pre-stored third correspondence relationship 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 the atmospheric pressure; determining a third EGR correction coefficient corresponding to the atmospheric pressure according to a pre-stored fourth correspondence relationship between the atmospheric pressure and the EGR correction coefficient; taking the product of 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-flameout exhaust gas recirculation (EGR) system control device, characterized in that: The device comprises: An acquisition module is configured to acquire actual ambient temperature; a determination module 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 relationship 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 intercooling post-theoretical temperature; The acquisition module is further configured to acquire the engine load and the actual temperature after intercooling of the engine intake air after intercooling by 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 also includes: A setting module is configured to set the initial values ​​of the test environment temperature and the temperature after cooling in the test as a first preset temperature threshold; The determination module is further configured to increase the test environment temperature by a first preset temperature step, and determine the post-cooling temperature in the test corresponding to each of the test environment temperatures, until the test environment temperature reaches a second preset temperature threshold; The determination module is further configured to obtain the first corresponding relationship between the ambient temperature and the post-intercooling theoretical temperature according to each of the test ambient temperatures and the test post-intercooling temperature 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 keep the EGR rate at a maximum; The determination module is further configured to increase the engine speed according to a preset speed step and determine a post-cooling intermediate temperature corresponding to each engine speed until the engine speed reaches a maximum preset speed; The determination module is further configured to determine a maximum test intermediate post-cooling temperature from the test intermediate post-cooling temperatures corresponding to each of the engine speeds. The determination module is further configured to increase the test post-cooling temperature at 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 also includes: A setting module is 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 of the test temperature differences until the test temperature difference reaches a second preset temperature difference threshold; The determination module is further configured to obtain the second corresponding relationship between the engine load, the temperature difference and the EGR correction coefficient according to 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 corresponding relationship. The determination module is further configured to reduce the engine load by a preset load step 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 according to 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 according to a pre-stored fourth correspondence relationship 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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