A control method and system of high-low pressure EGR of a vehicle, a vehicle and a storage medium

Abstract

The application discloses a kind of automobile high-low pressure EGR control method, system, vehicle and storage medium, the method includes, establishing and according to the engine thermodynamic model selects engine simulation operating condition;Formulate high-low pressure EGR control strategy of external characteristic and formulate partial load high-low pressure EGR control strategy, and the external characteristic high-low pressure EGR control strategy and formulate partial load high-low pressure EGR control strategy are input into the engine thermodynamic model to obtain a plurality of first simulation parameters and second simulation parameters, to evaluate whether the external characteristic high-low pressure EGR control strategy and formulate partial load high-low pressure EGR control strategy are qualified according to the plurality of first simulation parameters and plurality of second simulation parameters;By selecting multiple target operating conditions, the entire engine universal characteristic region is covered, so that the reliability and accuracy of the external characteristic high-low pressure EGR control strategy and formulate partial load high-low pressure EGR control strategy increase.

Description

Technical Field

[0001] This invention relates to the field of automotive exhaust gas recirculation technology, and in particular to a control method, system, vehicle, and storage medium for high and low pressure EGR in automobiles. Background Technology

[0002] With further upgrades to emission regulations, future engines will be required to achieve near-zero emissions, making the application of high and low pressure EGR a key technology. EGR is an exhaust gas recirculation technology used in internal combustion engines. Its main function is to reintroduce some of the burned exhaust gas into the engine to participate in the combustion process of the air-fuel mixture again, thereby reducing nitrogen oxide (NOx) emissions in the exhaust gas. Therefore, how to control the high and low pressure EGR system to achieve a balance between power, economy, emissions, and transient response is a critical issue that urgently needs to be addressed.

[0003] Currently, domestic research on the control of high and low pressure EGR systems is relatively shallow and mainly focuses on experimental research, which not only consumes a lot of experimental resources but also lacks positive guidance. For example, some literature only compares the fuel consumption differences under different EGR allocation ratios without considering the impact on other performance parameters. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a control method, system, vehicle, and storage medium for automotive high and low voltage EGR.

[0005] A method for controlling high and low voltage EGR in an automobile according to a first aspect of the present invention, the method comprising,

[0006] An engine thermodynamic model is established to select engine simulation conditions based on the engine thermodynamic model;

[0007] A high- and low-pressure EGR control strategy for external characteristics is formulated, and the high- and low-pressure EGR control strategy for external characteristics is input into the engine thermodynamic model to obtain a variety of first simulation parameters, so as to evaluate the current high- and low-pressure EGR control strategy for external characteristics based on the variety of first simulation parameters;

[0008] A partial load high and low pressure EGR control strategy is formulated, and the partial load high and low pressure EGR control strategy is input into the engine thermodynamic model to obtain a variety of second simulation parameters, so as to evaluate the current partial load high and low pressure EGR control strategy based on the variety of second simulation parameters;

[0009] If the external load high and low voltage EGR control strategy meets the requirements, then a transient response evaluation is performed on the external load high and low voltage EGR control strategy. If the transient response evaluation is qualified, then the external load high and low voltage EGR control strategy is effective.

[0010] The external characteristic high and low pressure EGR control strategy and the partial load high and low pressure EGR control strategy are input into the engine thermodynamic model for verification.

[0011] According to a method for controlling high and low pressure EGR in an automobile, the method first involves inputting parameters into thermodynamic simulation software to establish an engine thermodynamic model. The parameters of the engine thermodynamic model are then adjusted as needed to simulate normal engine thermodynamic operation. After establishing the engine thermodynamic model, an engine simulation condition is selected in the thermodynamic simulation software to simulate the engine's actual operating conditions. A high and low pressure EGR control strategy based on the engine's external characteristics is then formulated and input into the engine thermodynamic model via the thermodynamic simulation software. The engine thermodynamic model processes data according to the high and low pressure EGR control strategy to obtain multiple first simulation parameters. After obtaining these first simulation parameters, the high and low pressure EGR control strategy is evaluated to determine if it meets the requirements. If the evaluation of the high and low pressure EGR control strategy meets the requirements, it indicates that the high and low pressure EGR control strategy meets the requirements. If the external characteristic high and low pressure EGR control strategy fails to meet the evaluation criteria, the external characteristic high and low pressure EGR control strategy is modified and tested again. Simultaneously, a partial load high and low pressure EGR control strategy is formulated and input into the engine thermodynamic model using thermodynamic simulation software. The engine thermodynamic model processes data based on the partial load high and low pressure EGR control strategy to obtain multiple second simulation parameters. After obtaining these parameters, the partial load high and low pressure EGR control strategy is evaluated to determine its suitability. If the partial load high and low pressure EGR control strategy meets the evaluation criteria, it indicates that the partial load high and low pressure EGR control strategy is effective. If the evaluation fails, the partial load high and low pressure EGR control strategy is adjusted and tested again. Finally, the external characteristic high and low pressure EGR control strategy and the partial load high and low pressure EGR control strategy are input into the engine thermodynamic model for verification.

[0012] According to some embodiments of the present invention, the establishment of the engine thermodynamic model specifically includes,

[0013] A thermodynamic model framework for the engine was established using thermodynamic software, and the basic modules of the engine were built. The basic modules of the engine include engine cylinders, intake manifolds, exhaust manifolds, valves, intake ports, intercooler, and EGR cooler.

[0014] Injection parameter settings: Input the relationship curves between fuel type, number and diameter of nozzle holes, injection pressure, injection pulse width and fuel injection rate;

[0015] Establish a combustion module and select an engine predictive combustion model;

[0016] Establish an emissions module and activate the NOx emissions component and SOOT emissions component in the predicted combustion model;

[0017] The engine turbocharger map and the lift curves of the engine intake and exhaust valves are obtained and input into the basic module;

[0018] Establish high and low pressure EGR modules for the engine to detect pipeline flow and calculate the engine EGR rate;

[0019] A transient module for torque ramp-up at constant speed is established, and a transient calculation mode is selected to calculate the trend of engine torque change.

[0020] According to some embodiments of the present invention, the external characteristic high and low voltage EGR control strategy includes setting the external characteristic target EGR rate and setting the external characteristic high and low voltage EGR allocation ratio;

[0021] The external characteristic target EGR rate is defined as follows:

[0022] A first target NOx is set based on the emission target, and the first target NOx is achieved by adjusting the external characteristic target EGR rate, thus obtaining the external characteristic target EGR rate;

[0023] The specific allocation ratio of the high and low voltage EGRs for the external characteristics is as follows:

[0024] Keeping the target EGR rate constant, multiple combinations of high and low voltage EGR allocation ratios with different high voltage EGR percentages are set.

[0025] First, a first target NOx is set based on the prescribed emission targets. Then, the external characteristic target EGR rate is adjusted according to the set first target NOx to obtain the external characteristic target EGR rate that satisfies the first target NOx. The external characteristic target EGR rate includes external characteristic high-pressure EGR and external characteristic low-pressure EGR. By setting multiple sets of different external characteristic high-pressure EGR and external characteristic low-pressure EGR ratios, the external characteristic high and low pressure EGR control strategy becomes more comprehensive.

[0026] According to some embodiments of the present invention, the partial load high and low voltage EGR control strategy includes setting a partial load target EGR rate and setting a partial load high and low voltage EGR allocation ratio;

[0027] The target EGR rate for the partial load is set as follows:

[0028] A second target NOx is set based on the emission target, and the second target NOx is achieved by adjusting the partial load target EGR rate to obtain the partial load target EGR rate; and multiple different target operating conditions are set based on the same partial load target EGR rate;

[0029] The allocation ratio of high and low voltage EGRs for the partial load is determined as follows:

[0030] Based on the target EGR rate of the partial load and different target operating conditions, multiple combinations of high and low voltage EGR allocation ratios for the partial load with different high voltage EGR percentages are set.

[0031] First, a second target NOx is formulated based on the prescribed emission target. The partial load target EGR rate is then adjusted according to the formulated second target NOx to obtain the partial load target EGR rate that satisfies the second target NOx. The partial load target EGR rate includes partial load high-pressure EGR and partial load low-pressure EGR. Multiple different target operating conditions are set for the partial load target EGR rate, and under each target operating condition, multiple different proportions of partial load high-pressure EGR and partial load low-pressure EGR are set to make the partial load high and low pressure EGR control strategy more comprehensive and consider more operating conditions.

[0032] According to some embodiments of the present invention, the transient response evaluation specifically includes,

[0033] Select several different speeds under the target operating conditions, calculate the engine torque and the maximum external characteristic torque at the first time, and calculate the ratio of the engine torque to the maximum external characteristic torque;

[0034] If the ratio is greater than or equal to the first threshold, the transient response evaluation is deemed qualified.

[0035] If the ratio is less than the first threshold, the transient response assessment is deemed unqualified, and the second target Nox and the partial load target EGR rate need to be revised.

[0036] According to some embodiments of the present invention, if the current external characteristic high and low pressure EGR control strategy is deemed qualified based on the various first simulation parameters, then the external characteristic dynamics are checked; the check specifically involves...

[0037] The target EGR rate and the high and low pressure EGR distribution ratio of the external characteristics are input into the engine thermodynamic model. The external characteristic torque of the engine is calculated and generated according to the engine thermodynamic model. If the external characteristic torque meets the target, the external characteristic power is verified and passed.

[0038] According to a second aspect of the present invention, an automotive high and low voltage EGR control system includes,

[0039] The first acquisition module is used to acquire engine thermodynamic parameters, including engine cylinder parameters, intake manifold parameters, turbocharger parameters, and fuel injection parameters.

[0040] The model building module is used to build an engine thermodynamic model based on the engine thermodynamic parameters obtained by the first acquisition module.

[0041] The first setting module is used to set and adjust the target EGR rate setting and the high and low pressure EGR allocation ratio of the engine external characteristics, and send the target EGR rate setting and the high and low pressure EGR allocation ratio of the external characteristics to the first processing module.

[0042] The second setting module is used to set and adjust the engine part-load target EGR rate setting and the part-load high and low pressure EGR allocation ratio, apply the part-load target EGR rate to a variety of different target operating conditions, and send the engine part-load target EGR rate setting and the part-load high and low pressure EGR allocation ratio to the second processing module.

[0043] The first processing module performs data processing based on the engine thermodynamic model of the model building module and the external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio sent by the first setting module, obtains the first result parameter, and sends the first result parameter to the first evaluation module.

[0044] The second processing module performs data processing based on the engine thermodynamic model of the model building module and the partial load target EGR rate setting and partial load high and low pressure EGR allocation ratio sent by the second setting module to obtain the second result parameter, and sends the second result parameter to the second evaluation module.

[0045] The first evaluation module is used to receive and evaluate the first result parameter according to a preset comparison table. If the first result parameter is qualified, the corresponding engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio are output. If the first result parameter is not qualified, the feedback is sent to the first setting module to adjust the engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio.

[0046] The second evaluation module receives and evaluates the second result parameter according to a preset comparison table. If the second result parameter is qualified, it outputs the corresponding engine part-load target EGR rate setting and part-load high and low pressure EGR allocation ratio. If the second result parameter is unqualified, it feeds back to the second setting module to adjust the part-load target EGR rate setting and part-load high and low pressure EGR allocation ratio.

[0047] According to a high and low pressure EGR control system for automobiles of the present invention, firstly, engine thermodynamic parameters are input through a first acquisition module, specifically including engine cylinder parameters, intake manifold parameters, turbocharger parameters, fuel injection parameters, etc.; the first acquisition module sends the acquired engine thermodynamic parameters to a model building module, which performs engine thermodynamic modeling based on the engine thermodynamic parameters to establish an engine thermodynamic model; then, a target EGR rate conforming to emission regulations is set through a first setting module, and multiple combinations of different high and low pressure EGR ratios are set according to the target EGR rate, and the target EGR rate and... Combinations of high and low pressure EGR ratios with different external characteristics are sent to the first processing module. The first processing module processes the data based on the engine thermodynamic model of the model building module and the target EGR rate setting and multiple combinations of high and low pressure EGR allocation ratios sent by the first setting module, deriving a first result parameter. The first result parameter is then sent to the first evaluation module. The first evaluation module receives the first result parameter and evaluates it according to a preset lookup table. If the first result parameter is qualified, it outputs the corresponding target EGR rate setting and high and low pressure EGR allocation ratios for the engine external characteristics; otherwise, it outputs the first result parameter. If the parameters are not up to standard, feedback is sent to the first setting module to adjust the engine's external characteristic target EGR rate and the high and low pressure EGR allocation ratio. Simultaneously, the second setting module sets a partial load target EGR rate that complies with emission regulations, and based on this partial load target EGR rate, sets multiple combinations of different partial load high and low pressure EGR ratios. Different target operating conditions are set for the same partial load target EGR rate, forming multiple combinations of partial load target EGR rates and partial load high and low pressure EGR ratios under various target operating conditions. These combinations of partial load target EGR rates and partial load high and low pressure EGR ratios under various target operating conditions are then sent to the second processing module. The second processing module receives and processes the combination of the partial load target EGR rate and the partial load high and low pressure EGR ratio under various different target operating conditions to obtain a second result parameter, and sends the second result parameter to the second evaluation module; the second evaluation module receives the second result parameter and evaluates the second result parameter according to a preset comparison table. If the second result parameter is qualified, it outputs the corresponding engine partial load target EGR rate setting and partial load high and low pressure EGR allocation ratio under the target operating condition. If the second result parameter is not qualified, it feeds back data to the second setting module to adjust the EGR rate setting and the partial load high and low pressure EGR allocation ratio.

[0048] A vehicle according to a third aspect of the present invention includes a processor and a memory for storing processor-executable instructions; wherein the processor is configured to:

[0049] Implement the automotive high and low pressure EGR control method described in the first aspect embodiment.

[0050] According to a fourth aspect of the present invention, a computer-readable storage medium stores a program for a vehicle high and low voltage EGR control method, which, when executed by a processor, implements a vehicle high and low voltage EGR control method as described in the first aspect embodiment.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart of a method for controlling high and low voltage EGR in automobiles according to an embodiment of the present invention;

[0054] Figure 2 This is a simulation diagram illustrating a high and low voltage EGR control method for automobiles according to an embodiment of the present invention.

[0055] Figure 3 This is an external characteristic torque curve diagram of a high and low voltage EGR control method for automobiles according to an embodiment of the present invention.

[0056] Figure 4 This is a schematic diagram illustrating the target EGR rate of a high and low pressure EGR control method for automobiles according to an embodiment of the present invention.

[0057] Figure 5 This is a schematic diagram of the high-pressure EGR ratio in an embodiment of the high-low pressure EGR control method for automobiles according to the present invention.

[0058] Figure 6 This is a schematic diagram of the specific fuel consumption of a high and low pressure EGR control method for automobiles according to an embodiment of the present invention;

[0059] Figure 7 This is a schematic diagram of nitrogen oxide emissions from a high- and low-pressure EGR control method for automobiles according to an embodiment of the present invention. Detailed Implementation

[0060] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0061] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0063] Example 1

[0064] See Figure 1 As shown, a method for controlling high and low voltage EGR in automobiles includes the following steps:

[0065] Step S100: Establish an engine thermodynamic model to select engine simulation conditions based on the engine thermodynamic model;

[0066] Specifically, establishing an engine thermodynamic model includes the following steps:

[0067] Step S110: Establish the engine thermodynamic model framework in the thermodynamic software and build the engine basic modules;

[0068] Furthermore, the basic engine module includes engine cylinders, intake manifold, exhaust manifold, valves, intake ports, intercooler, and EGR cooler;

[0069] Step S120: Setting injection parameters. In this embodiment, the fuel type is diesel. Input the nozzle orifice diameter and number of orifices; input the injection rate curve of the engine injector, that is, the relationship between injection pressure, injection pulse width and fuel injection rate; the injection rate curve operating points need to be fully covered to ensure the interpolation accuracy of the simulation software. The pressure range is 400-2000 bar, with an interval of 200 bar; the pulse width is 0.2 ms-2 ms, with an interval of 0.1 ms.

[0070] Step S130: Establish a combustion module, select an engine predictive combustion model, and use the same combustion model parameter settings for different engine operating conditions; in this embodiment, the predictive combustion model used is the DIPulse model, and the parameters are set to the system default.

[0071] Step S140: Establish the emission module and activate the NOx emission component and SOOT emission component in the predictive combustion model; wherein the calibration coefficient of NOx is adjusted to 0.8, and the SOOT calibration coefficient adopts the default value of 1;

[0072] Nox represents nitrogen oxide emissions, and SOOT represents soot emissions;

[0073] Step S150: Obtain the engine turbocharger map and input it into the turbocharger of the engine thermodynamic model; the turbocharger pressure end map contains test results of four parameters: speed, pressure ratio, flow rate, and efficiency, with at least 6 sets of data for each speed, and surge line data should also be included in the map; the turbocharger turbine end map contains test results of four parameters: speed, expansion ratio, flow rate, and efficiency, with at least 6 sets of data for each speed.

[0074] Step S160: Input the lift curves of the engine intake valve and exhaust valve respectively; the intake valve and exhaust valve lift curves are each 1 degree apart as a point; input the valve clearance value, which is 0 in this embodiment; fill in the air passage flow coefficients corresponding to the intake and exhaust valves, with the cylinder bore as the reference diameter, and data in sets of 1 mm.

[0075] Step S170: Establish the engine high and low pressure EGR module. Establishing the engine high and low pressure EGR module requires connecting the intake manifold and EGR pipeline, and monitoring the pipeline flow. The engine high and low pressure EGR module will automatically calculate the EGR rate. The target EGR rate is controlled by the speed-torque map. The distribution of high pressure EGR and low pressure EGR is controlled by multiplying the total EGR rate by a coefficient A. It can be seen that 0≤A≤1.

[0076] For details, please refer to Figure 2 As shown, selecting engine simulation conditions includes the following steps:

[0077] Step S180: Select at least 10 operating conditions for external characteristics, one operating condition every 200 rpm; select more than 40 operating conditions for partial load. For speeds above the maximum torque point, an operating condition can be established at 10% load intervals. For the optimal fuel consumption area or thermal management area, the number of operating conditions can be increased as appropriate; for low speed operating conditions, the number of operating conditions can be reduced to 7-8, and the total number of operating conditions should not be less than 50.

[0078] Step S190: Establish a transient model of torque ramp-up at constant speed, select transient calculation mode, and calculate for a total time of 20 seconds. The first 10 seconds are the stable operating conditions of constant speed and low torque target (10 Nm recommended). Starting from the 10th second, the torque target is improved by external characteristics, and the engine air-fuel ratio limit is controlled to 1.05. Calculate the trend of engine torque change.

[0079] Step S200: Formulate the external characteristic high and low pressure EGR control strategy, and input the external characteristic high and low pressure EGR control strategy into the engine thermodynamic model to obtain a variety of first simulation parameters;

[0080] Furthermore, the external characteristic high and low voltage EGR control strategy includes setting the external characteristic target EGR rate and setting the external characteristic high and low voltage EGR allocation ratio;

[0081] Specifically, the external characteristic target EGR rate is set as follows:

[0082] The first target NOx is determined according to the emission target. The first target NOx is achieved by adjusting the external characteristic target EGR rate. The external characteristic target EGR rate is obtained. In this implementation, for the China VI engine, the recommended external characteristic first target NOx is around 6. For areas where the low speed EGR drive capability is insufficient, it can be relaxed to 8-10. According to the first NOx target, the first target NOx result is achieved by adjusting the target EGR rate. As shown in Table (1), it is a table of correspondence between the external characteristic target EGR rate and engine parameters. The external characteristic target EGR rate is obtained by simulation model calculation and iteration. At this time, the NOx result of all operating conditions is lower than the target value, so the external characteristic emission requirements can be met.

[0083] Table (1) Correspondence between target EGR rate and engine parameters for external characteristics

[0084]

[0085] Specifically, the high and low voltage EGR allocation ratio is set as follows:

[0086] Keeping the external characteristic target EGR rate unchanged, the high-pressure EGR ratio coefficient A is adjusted, and the engine fuel consumption and SOOT emission results under different allocation ratios are compared; the normalized fuel consumption and SOOT emission results are calculated with a weighted score based on a 2:1 weight; the coefficient A with the lowest score is the optimal high-pressure EGR ratio; taking 2800rpm as an example, the results of six ratios of 0%, 20%, 40%, 60%, 80%, and 100% are calculated; as shown in Table (2), the simulation results show that the score is the lowest when the high-pressure EGR ratio A = 100%, which is the optimal high-pressure EGR ratio; in order to obtain better results, the simulation interval can be shortened to try to obtain better results, for example, further simulation of 80%, 85%, 90%, 95%, and 100% results for comparison, which will not be elaborated here;

[0087] Table (2) Simulation Results

[0088]

[0089] Similarly, the high-pressure EGR ratio under its operating conditions can be obtained, as shown in Table (3).

[0090] Table (3) Percentage of High-Pressure EGR under Different Operating Conditions

[0091]

[0092] Step S300: Evaluate the current external characteristic high and low voltage EGR control strategy based on multiple first simulation parameters;

[0093] Specifically, the target EGR rate and the high-pressure EGR coefficient A in the high-low pressure EGR distribution ratio of the external characteristics are input into the engine thermodynamic model to calculate the engine's external characteristic power and torque. If the engine's external characteristic power and torque do not reach the target, step S200 is repeated to reduce the target EGR rate until the power target is achieved. In this embodiment, at the 2800rpm, 407N operating point, the turbine inlet exhaust temperature reaches 750℃, exceeding the target value of 735℃, and there is a risk of achieving the torque target. Therefore, it is necessary to reduce the EGR rate to 3%, and the NOx emission target is also changed to 8g / kwh to make the turbine inlet temperature reach 735℃.

[0094] Step S400: Formulate a partial load high and low pressure EGR control strategy, and input the partial load high and low pressure EGR control strategy into the engine thermodynamic model to obtain various second simulation parameters;

[0095] Furthermore, the part-load high and low voltage EGR control strategy includes setting the target EGR rate for part load and setting the EGR allocation ratio for high and low voltage part load.

[0096] Specifically, the target EGR rate for partial load is set as follows:

[0097] A second target NOx is set based on the emission target. The second target NOx is achieved by adjusting the partial load target EGR rate, and the partial load target EGR rate is obtained. In this implementation, for China VI engines, it is recommended that the external characteristic second target NOx be around 6. For areas where the low speed EGR drive capability is insufficient, it can be relaxed to 8-10. Based on the second NOx target, the second target NOx result is achieved by adjusting the partial load target EGR rate. Multiple sets of different target operating conditions are set for the same partial load target EGR rate.

[0098] For transient response evaluation, select three engine speeds (recommended 1000 rpm, 1200 rpm, and 1400 rpm) and calculate the ratio of engine torque to the maximum external torque at 11 seconds. If this ratio is greater than 85%, the transient response is considered acceptable. Otherwise, restart step S400, adjusting the target NOx and EGR rates under partial load until the transient response is acceptable. (See also...) Figure 3 and Figure 4As shown, at a speed of 1000 rpm and a partial load target EGR rate of 20%, the torque in the 11th second is 240.5 Nm, while the external characteristic torque is 285 Nm, with a ratio of 84.3%, which is slightly lower than the requirement of 85%. Therefore, the EGR rate is set to 16%.

[0099] Specifically, the high- and low-voltage EGR allocation ratio for partial load is set as follows:

[0100] See Figure 5 As shown, the high and low pressure EGR ratio coefficient A is the partial load EGR ratio coefficient. Keeping the target EGR rate constant, the high pressure EGR ratio coefficient A is adjusted, and the engine fuel consumption and SOOT emissions under different ratios are compared. Normalized fuel consumption and SOOT emissions results are weighted and scored according to a 2:1 weighting. The coefficient A with the lowest score is the optimal high pressure EGR ratio. Taking 2800 rpm as an example, six ratios were calculated: 0%, 20%, 40%, 60%, 80%, and 100%. To obtain better results, the simulation interval can be shortened to try and achieve even better results. For example, further simulations at 80%, 85%, 90%, 95%, and 100% can be compared, but this will not be elaborated further here.

[0101] Step S500: Evaluate the current external characteristic high and low voltage EGR control strategy based on various second simulation parameters;

[0102] Specifically, the target EGR rate and the high-pressure EGR coefficient B in the high-low pressure EGR distribution ratio of the partial load are input into the engine thermodynamic model to calculate the engine external characteristic torque; if the engine external characteristic torque does not reach the target, step S400 is restarted until the power target is achieved and the engine external characteristic torque reaches the target.

[0103] Step S600: Input the external characteristic high and low pressure EGR control strategy and the partial load high and low pressure EGR control strategy into the engine thermodynamic model for verification;

[0104] Specifically, the target EGR rate for external characteristics and the high-low pressure EGR allocation ratio coefficients for external characteristics, as well as the target EGR rate for partial load and the high-low pressure EGR allocation ratio coefficients for partial load, are input into the engine thermodynamic model to calculate the fuel consumption and emissions results of the engine's universal characteristics, and to evaluate the rationality of the results; see reference. Figure 6 and Figure 7As shown, the high-efficiency range of ≤210g / kWh is very wide, spanning 1300rpm-2500rpm in speed range and 170Nm-450Nm in torque range. For small Euro VI diesel engines of the same displacement, the speed range of ≤210g / kWh is generally 1400rpm-2400rpm, and the torque range is 200Nm-400Nm. Therefore, it is evident that the above method can significantly improve the engine's optimal fuel consumption range. The BSNOx results show that most of the engine's BSNOx emissions are 4-6g / kWh, meeting the original emission requirements of a heavy-duty Euro VI engine. Therefore, the current design target EGR rate and high-pressure EGR proportional coefficient are reasonable.

[0105] Example 2

[0106] A high and low voltage EGR control system for automobiles includes,

[0107] The first acquisition module is used to acquire engine thermodynamic parameters, including engine cylinder parameters, intake manifold parameters, turbocharger parameters, and fuel injection parameters.

[0108] The model building module is used to build an engine thermodynamic model based on the engine thermodynamic parameters obtained by the first acquisition module.

[0109] The first setting module is used to set and adjust the target EGR rate setting and the high and low pressure EGR allocation ratio of the engine external characteristics, and send the target EGR rate setting and the high and low pressure EGR allocation ratio of the external characteristics to the first processing module.

[0110] The second setting module is used to set and adjust the engine part load target EGR rate setting and the part load high and low pressure EGR allocation ratio, apply the part load target EGR rate to a variety of different target operating conditions, and send the engine part load target EGR rate setting and the part load high and low pressure EGR allocation ratio to the second processing module.

[0111] The first processing module processes data based on the engine thermodynamic model from the model building module and the target EGR rate and high / low pressure EGR allocation ratio sent by the first setting module to obtain the first result parameters, and sends the first result parameters to the first evaluation module.

[0112] The second processing module performs data processing based on the engine thermodynamic model of the model building module and the partial load target EGR rate setting and partial load high and low pressure EGR allocation ratio sent by the second setting module to obtain the second result parameters, and sends the second result parameters to the second evaluation module.

[0113] The first evaluation module is used to receive and evaluate the first result parameters according to the preset comparison table. If the first result parameters are qualified, the corresponding engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio are output. If the first result parameters are not qualified, the feedback is sent to the first setting module to adjust the engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio.

[0114] The second evaluation module receives and evaluates the second result parameters according to a preset comparison table. If the second result parameters are qualified, it outputs the corresponding engine part-load target EGR rate setting and part-load high and low pressure EGR allocation ratio. If the second result parameters are not qualified, it feeds back to the second setting module to adjust the part-load target EGR rate setting and part-load high and low pressure EGR allocation ratio.

[0115] According to an embodiment of an automotive high and low pressure EGR control system, firstly, engine thermodynamic parameters are input through a first acquisition module, specifically including engine cylinder parameters, intake manifold parameters, turbocharger parameters, and fuel injection parameters. The first acquisition module sends the acquired engine thermodynamic parameters to a model building module, which performs engine thermodynamic modeling based on these parameters. Then, a target EGR rate conforming to emission regulations is set through a first setting module, and multiple combinations of different high and low pressure EGR ratios are set based on this target EGR rate. The data, along with combinations of high and low pressure EGR ratios for different external characteristics, is sent to the first processing module. The first processing module processes the data based on the engine thermodynamic model from the model building module and the target EGR rate and multiple combinations of high and low pressure EGR allocation ratios sent from the first setting module, deriving first result parameters. These first result parameters are then sent to the first evaluation module. The first evaluation module receives the first result parameters and evaluates them according to a preset comparison table. If the first result parameters are acceptable, it outputs the corresponding target EGR rate and high and low pressure EGR allocation ratios for the engine's external characteristics; otherwise, it outputs the parameters that are not acceptable. If the value is correct, the first setting module will adjust the engine's external characteristic target EGR rate and the high / low pressure EGR allocation ratio. Simultaneously, the second setting module will set a partial load target EGR rate that complies with emission regulations, and based on this partial load target EGR rate, set multiple combinations of different high / low pressure EGR ratios for each partial load. Different target operating conditions will be set for the same partial load target EGR rate, forming multiple combinations of partial load target EGR rates and high / low pressure EGR ratios under various target operating conditions. These combinations of partial load target EGR rates and high / low pressure EGR ratios under various target operating conditions will then be sent to the second setting module. The second processing module receives and processes combinations of partial load target EGR rates and partial load high and low pressure EGR ratios under various target operating conditions to obtain second result parameters, which are then sent to the second evaluation module. The second evaluation module receives the second result parameters and evaluates them according to a preset comparison table. If the second result parameters are qualified, it outputs the corresponding engine partial load target EGR rate setting and partial load high and low pressure EGR allocation ratio under the target operating conditions. If the second result parameters are not qualified, it feeds back data to the second setting module to adjust the EGR rate setting and partial load high and low pressure EGR allocation ratio.

[0116] Example 3

[0117] A vehicle includes a processor and a memory for storing processor-executable instructions; wherein the processor is configured as follows:

[0118] Implementing the high and low voltage EGR control method for automobiles in Example 1

[0119] Example 4

[0120] A computer-readable storage medium stores a program for a vehicle high and low voltage EGR control method, which, when executed by a processor, implements a vehicle high and low voltage EGR control method as described in Example 1.

[0121] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0122] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0123] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0124] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for controlling high and low voltage EGR in automobiles, characterized in that, The method includes, An engine thermodynamic model is established to select engine simulation conditions based on the engine thermodynamic model; A high- and low-pressure EGR control strategy for external characteristics is formulated, and the high- and low-pressure EGR control strategy for external characteristics is input into the engine thermodynamic model to obtain a variety of first simulation parameters, so as to evaluate the current high- and low-pressure EGR control strategy for external characteristics based on the variety of first simulation parameters; The external characteristic high and low voltage EGR control strategy includes setting the external characteristic target EGR rate and setting the external characteristic high and low voltage EGR allocation ratio; The external characteristic target EGR rate is defined as follows: A first target NOx is set based on the emission target, and the first target NOx is achieved by adjusting the external characteristic target EGR rate, thus obtaining the external characteristic target EGR rate; The specific allocation ratio of the high and low voltage EGRs for the external characteristics is as follows: Keeping the target EGR rate constant, multiple combinations of high and low voltage EGR allocation ratios with different high voltage EGR percentages are set. A partial load high and low pressure EGR control strategy is formulated, and the partial load high and low pressure EGR control strategy is input into the engine thermodynamic model to obtain a variety of second simulation parameters, so as to evaluate the current partial load high and low pressure EGR control strategy based on the variety of second simulation parameters; The partial load high and low voltage EGR control strategy includes setting the target EGR rate for partial load and setting the EGR allocation ratio for partial load high and low voltage. The target EGR rate for the partial load is set as follows: A second target NOx is set based on the emission target, and the second target NOx is achieved by adjusting the partial load target EGR rate to obtain the partial load target EGR rate; and multiple different target operating conditions are set based on the same partial load target EGR rate; The allocation ratio of high and low voltage EGRs for the partial load is determined as follows: Based on the target EGR rate of the partial load and different target operating conditions, multiple combinations of high and low voltage EGR allocation ratios for the partial load with different high voltage EGR percentages are set. If the partial load high and low voltage EGR control strategy meets the requirements, then a transient response evaluation is performed on the partial load high and low voltage EGR control strategy. If the transient response evaluation is qualified, then the partial load high and low voltage EGR control strategy is effective. The transient response evaluation specifically includes, Select several different speeds under the target operating conditions, calculate the engine torque and the maximum external characteristic torque at the first time, and calculate the ratio of the engine torque to the maximum external characteristic torque; If the ratio is greater than or equal to the first threshold, the transient response evaluation is deemed qualified. If the ratio is less than the first threshold, the transient response assessment is deemed unqualified, and the second target Nox and the partial load target EGR rate need to be revised. The external characteristic high and low pressure EGR control strategy and the partial load high and low pressure EGR control strategy are input into the engine thermodynamic model for verification.

2. The automotive high and low voltage EGR control method according to claim 1, characterized in that, The establishment of the engine thermodynamic model specifically involves... A thermodynamic model framework for the engine was established using thermodynamic software, and the basic modules of the engine were built. Injection parameter settings: Input the relationship curves between fuel type, number and diameter of nozzle holes, injection pressure, injection pulse width and fuel injection rate; Establish a combustion module and select an engine predictive combustion model; Establish an emissions module and activate the NOx emissions component and SOOT emissions component in the predicted combustion model; The engine turbocharger map and the lift curves of the engine intake and exhaust valves are obtained and input into the basic module; Establish high and low pressure EGR modules for the engine to detect pipeline flow and calculate the engine EGR rate; A transient module for torque ramp-up at constant speed is established, and a transient calculation mode is selected to calculate the trend of engine torque change.

3. The automotive high and low pressure EGR control method according to claim 2, characterized in that, The engine basic module includes engine cylinders, intake manifold, exhaust manifold, valves, intake ports, intercooler, and EGR cooler.

4. The automotive high and low pressure EGR control method according to claim 1, characterized in that, If the current external characteristic high and low pressure EGR control strategy is deemed qualified based on the aforementioned multiple first simulation parameters, then the external characteristic dynamics are verified; specifically, the verification involves... The target EGR rate and the high-low pressure EGR distribution ratio of the external characteristics are input into the engine thermodynamic model, and the engine external characteristic torque is calculated based on the engine thermodynamic model; if the external characteristic torque meets the target, the external characteristic power is verified and passes the verification.

5. A high and low voltage EGR control system for automobiles, used to implement the high and low voltage EGR control method for automobiles according to any one of claims 1-4, characterized in that, The system includes, The first acquisition module is used to acquire engine thermodynamic parameters, including engine cylinder parameters, intake manifold parameters, turbocharger parameters, and fuel injection parameters. The model building module is used to build an engine thermodynamic model based on the engine thermodynamic parameters obtained by the first acquisition module. The first setting module is used to set and adjust the target EGR rate setting and the high and low pressure EGR allocation ratio of the engine external characteristics, and send the target EGR rate setting and the high and low pressure EGR allocation ratio of the external characteristics to the first processing module. The second setting module is used to set and adjust the engine part-load target EGR rate setting and the part-load high and low pressure EGR allocation ratio, apply the part-load target EGR rate to a variety of different target operating conditions, and send the engine part-load target EGR rate setting and the part-load high and low pressure EGR allocation ratio to the second processing module. The first processing module performs data processing based on the engine thermodynamic model of the model building module and the external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio sent by the first setting module, obtains the first result parameter, and sends the first result parameter to the first evaluation module. The second processing module performs data processing based on the engine thermodynamic model of the model building module and the partial load target EGR rate setting and partial load high and low pressure EGR allocation ratio sent by the second setting module to obtain the second result parameter, and sends the second result parameter to the second evaluation module. The first evaluation module is used to receive and evaluate the first result parameter according to a preset comparison table. If the first result parameter is qualified, it outputs the corresponding engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio. If the first result parameter is not qualified, it feeds back to the first setting module to adjust the engine external characteristic target EGR rate setting and external characteristic high and low pressure EGR allocation ratio. The second evaluation module is used to receive and evaluate the second result parameter according to a preset comparison table. If the second result parameter is qualified, the corresponding engine part load target EGR rate setting and part load high and low pressure EGR allocation ratio are output. If the second result parameter is not qualified, it is fed back to the second setting module to adjust the target EGR rate setting for the partial load and the high and low voltage EGR allocation ratio for the partial load.

6. A vehicle, comprising a processor, characterized in that, A memory for storing processor-executable instructions; wherein the processor is configured as follows: Implement the high and low pressure EGR control method for automobiles as described in any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The storage medium stores a program for a vehicle high and low voltage EGR control method, which, when executed by a processor, implements a vehicle high and low voltage EGR control method as described in any one of claims 1-4.

Images