Engine combustion characteristic parameter prediction method and system, vehicle and medium

Abstract

The invention relates to the technical field of engines, and discloses an engine combustion characteristic parameter prediction method and system, a vehicle and a medium, and the method comprises the steps: determining a reference engine of a target engine; constructing a reference combustion model of the reference engine; simulating the reference combustion model, and outputting the highest temperature and the combustion duration of the corresponding non-combustion area under each rotating speed and torque; a highest temperature matrix of the unburned area is constructed based on the highest temperatures of the unburned area corresponding to the rotating speeds and the torques, and a combustion duration matrix is constructed based on the combustion durations corresponding to the rotating speeds and the torques; and predicting combustion characteristic parameters of the target engine according to the highest temperature matrix of the unburned area and the combustion duration matrix. According to the method, the reference engine with the similar in-cylinder flow level with the new type is screened, the combustion characteristic parameters of the new type are predicted through the combustion model verified through experiments, the prediction precision of the combustion parameters is improved, and the requirement for automatic generation of the combustion characteristic parameters of the new type is met.

Description

Technical Field

[0001] The present invention relates to the field of engine technology, and in particular to a method, system, vehicle and medium for predicting engine combustion characteristic parameters. Background Art

[0002] During the conceptual design phase of an engine, developers need to predict engine performance to guide design. Specifically, accurately predicting engine performance parameters like power, torque, and fuel consumption requires a relatively accurate estimate of the design engine's combustion characteristics. Furthermore, they need to quickly predict the relationship between combustion characteristics and engine design parameters to support large-scale simulation-based design of experiments (DOE).

[0003] Currently, engine combustion characteristics can be predicted using classical combustion models, such as those based on the Weber function, which simplify the complex combustion process into a mathematically fitted expression for the heat release rate. However, the accuracy of these models depends primarily on the accuracy of the combustion characteristic parameters MBF50% (i.e., the Mass Burned Fraction at 50%—the crankshaft angle corresponding to 50% of the fuel burned, or the crankshaft angle at which the cumulative mass fraction burned reaches 50%) and combustion duration (i.e., the crankshaft angle corresponding to the change from 10% to 90% of the fuel burned, or the difference in crankshaft angle corresponding to the cumulative mass fraction burned from 10% to 90%). These two parameters often rely on the experience and experimental knowledge of R&D personnel, making them difficult to quickly predict during the engine design phase, nor is it possible to predict their relationship with design parameters.

[0004] In summary, the existing prediction method of engine combustion characteristic parameters is determined based on subjective experience, which has low prediction accuracy and poor efficiency, and is difficult to meet the needs of automatic generation of combustion characteristic parameters of new models. Summary of the Invention

[0005] In view of this, the present invention provides a method, system, vehicle and medium for predicting engine combustion characteristic parameters to solve the problem raised in the above technical background that the prediction accuracy of existing engine combustion characteristic parameters is low and the effect is poor, making it difficult to effectively obtain the combustion characteristic parameters of new models, thereby seriously affecting the prediction of engine performance.

[0006] In a first aspect, the present invention provides a method for predicting engine combustion characteristic parameters, the method comprising:

[0007] Determine the reference engine of the target engine;

[0008] Construct a reference combustion model of a reference engine;

[0009] Simulate the reference combustion model and output the corresponding maximum temperature of the unburned zone and combustion duration at various speeds and torques;

[0010] A maximum temperature matrix of the unburned zone is constructed based on the maximum temperature of the unburned zone corresponding to each speed and torque, and a combustion duration matrix is ​​constructed based on the combustion duration corresponding to each speed and torque;

[0011] The combustion characteristic parameters of the target engine are predicted based on the unburned zone maximum temperature matrix and the combustion duration matrix.

[0012] The present invention constructs a reference combustion model of the reference engine by screening reference engines with similar in-cylinder flow levels as the target engine, uses its experimentally verified reference combustion model to extract a combustion characteristic matrix, and predicts the combustion characteristic parameters of the target engine based on the combustion characteristic matrix. This not only ensures the prediction accuracy and effect of the combustion characteristic parameters of the new engine model, but also significantly reduces development costs and shortens the prediction cycle, providing reliable data support for engine combustion optimization and performance prediction.

[0013] In an optional embodiment, determining a reference engine for the target engine includes:

[0014] Determine the compression ratio, port tumble ratio and stroke-to-bore ratio of the target engine respectively;

[0015] Based on the compression ratio, port tumble ratio and stroke-to-bore ratio, an engine that meets the preset model difference requirements is selected as a reference engine for the target engine.

[0016] The present invention screens reference engines through three core structural parameters: compression ratio, air tumble ratio, and stroke-to-bore ratio. It can screen reference engines with similar in-cylinder flow levels to the target engine based on precise matching of combustion physics similarities, providing design guidance for the combustion characteristic parameters of subsequent new models.

[0017] In an optional embodiment, constructing a reference combustion model of a reference engine includes:

[0018] Construct a combustion model based on the Weber function;

[0019] Obtain test data of a reference engine, the test data including at least speed, torque, charging efficiency, and fuel consumption rate;

[0020] Import test data into the combustion model for calibration, and obtain the charging efficiency and fuel consumption rate of the combustion model simulation output at various speeds and torques.

[0021] Calculate the efficiency deviation between the charging efficiency of each simulation output and the corresponding charging efficiency in the test data, and the fuel consumption deviation between the fuel consumption rate of each simulation output and the corresponding fuel consumption rate in the test data;

[0022] When any efficiency deviation and fuel consumption deviation meets the preset accuracy requirement, the calibration is stopped and the current combustion model is used as the reference combustion model of the reference engine.

[0023] The present invention constructs a reference combustion model based on the combustion model of the Weber function and the test data of the reference engine. It can take into account the flexibility and physical accuracy of the actual working conditions of the engine, thereby ensuring a high degree of consistency between the model and the actual operation, and laying the foundation for the subsequent prediction of the combustion characteristics of the target engine.

[0024] In an optional embodiment, before predicting the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix, the engine combustion characteristic parameter prediction method further includes:

[0025] The unburned zone maximum temperature matrix and the combustion duration matrix are respectively corrected based on the preset exhaust gas recirculation rate, and corresponding corrected unburned zone maximum temperature matrix and combustion duration matrix are obtained.

[0026] The present invention introduces a preset exhaust gas recirculation rate to correct the unburned zone maximum temperature matrix and the combustion duration matrix, which can fully consider the influence of the exhaust gas recirculation rate on the combustion process in the prediction of combustion characteristic parameters, and further improve the prediction accuracy of subsequent target engine combustion characteristics.

[0027] In an optional embodiment, the combustion characteristic parameters include MBF50% and combustion duration; and predicting the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix includes:

[0028] determining a combustion duration of a target engine based on a combustion duration matrix;

[0029] A target combustion model of the target engine is constructed, and the MBF50% of the target engine is predicted based on the unburned zone maximum temperature matrix and the target combustion model.

[0030] The present invention determines the combustion duration of the target engine based on the combustion duration matrix of the reference engine, and predicts the MBF50% meter in combination with the target combustion model constructed for the target engine and the maximum temperature matrix of the unburned zone of the reference engine. The combustion characteristic data of the reference engine can be deeply coupled with the personalized model of the target engine. It can not only accurately migrate the combustion duration, improve the prediction efficiency and engineering adaptability, but also enhance the accuracy of the combustion phase, greatly meeting the demand for automatic generation of combustion characteristic parameters of new models.

[0031] In an optional embodiment, determining the combustion duration of the target engine based on the combustion duration matrix includes:

[0032] determining a current design speed and a current design torque of the target engine;

[0033] The combustion duration corresponding to the current design speed and the current design torque is selected from the combustion duration matrix as the combustion duration of the target engine.

[0034] The combustion duration matrix of the present invention stores the combustion characteristic data of the reference engine under different speed and torque conditions, while the design speed and torque of the target engine directly correspond to the actual working scenario; specifically, by accurately matching the design point working conditions of the target engine, combustion duration parameters that are highly consistent with the actual operating conditions of the target engine can be directly obtained, further avoiding the errors caused by extrapolation across working conditions and ensuring the pertinence and accuracy of the prediction.

[0035] In an optional embodiment, predicting MBF50% of a target engine based on the unburned zone maximum temperature matrix and the target combustion model includes:

[0036] The maximum temperature of the unburned zone corresponding to each speed and torque in the maximum temperature matrix of the unburned zone is input into the target combustion model respectively, and the corresponding simulation MBF50% is obtained;

[0037] Determine the predicted maximum unburned zone temperature of the target engine based on each simulated MBF50%, and calculate the temperature error between the predicted maximum unburned zone temperature and the corresponding maximum unburned zone temperature in the maximum unburned zone temperature matrix;

[0038] Based on the temperature error, the control parameters of the target combustion model are corrected. The maximum unburned zone temperature corresponding to each speed and torque in the maximum unburned zone temperature matrix is ​​then input into the target combustion model to obtain the corresponding simulated MBF50%. When the simulated MBF50% meets a preset crankshaft angle threshold or the temperature error is less than a preset temperature difference threshold, the simulated MBF50% is used as the MBF50% of the target engine.

[0039] The present invention generates a simulated MBF50% by inputting the unburned zone maximum temperature matrix into the target combustion model, and reversely calculates the temperature error to correct the model's control parameters. This can dynamically compensate for the differences in combustion characteristics between the target engine and the reference engine, making the model output closer to the actual combustion process, thereby significantly improving the prediction accuracy of MBF50% and greatly ensuring the performance prediction of the engine.

[0040] In a second aspect, the present invention provides an engine combustion characteristic parameter prediction system, the system comprising:

[0041] A reference engine model determination module, used to determine a reference engine for a target engine;

[0042] A combustion model building module, used to build a reference combustion model of a reference engine;

[0043] The combustion model simulation module is used to simulate the reference combustion model and output the maximum temperature of the unburned zone and the combustion duration corresponding to each speed and torque;

[0044] a characteristic matrix construction module for constructing an unburned zone maximum temperature matrix based on the corresponding unburned zone maximum temperatures at each speed and torque, and a combustion duration matrix based on the corresponding combustion duration at each speed and torque;

[0045] The characteristic parameter prediction module is used to predict the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix.

[0046] The engine combustion characteristic parameter prediction system of the present invention screens reference engines with similar in-cylinder flow levels as the target engine and constructs a reference combustion model of the reference engine. It then uses the reference combustion model to extract the combustion characteristic matrix of the unburned zone maximum temperature matrix and the combustion duration matrix, and predicts the combustion characteristic parameters of the target engine based on the combustion characteristic matrix. This can greatly ensure the accuracy and effect of predicting the combustion characteristic parameters of new engine models, while also significantly reducing development costs and shortening the engine combustion characteristic parameter prediction cycle, thereby meeting the demand for automatic generation of combustion characteristic parameters of new engine models.

[0047] In a third aspect, the present invention provides a vehicle, comprising a controller, the controller comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to execute a method for predicting engine combustion characteristic parameters according to the first aspect or any corresponding embodiment thereof.

[0048] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute a method for predicting engine combustion characteristic parameters according to the first aspect or any corresponding embodiment thereof.

[0049] The engine combustion characteristic parameter prediction method and system of the present invention constructs a reference combustion model of the reference engine by screening a reference engine with similar in-cylinder flow levels as the target engine, uses its experimentally verified reference combustion model to extract a combustion characteristic matrix, and predicts the combustion characteristic parameters of the target engine based on the combustion characteristic matrix. This not only ensures the prediction accuracy and effect of the combustion characteristic parameters of the new engine model, but also significantly reduces development costs, thereby shortening the prediction cycle of the engine combustion characteristic parameters, and providing reliable data support for engine combustion optimization and performance prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 is a flow chart of a method for predicting engine combustion characteristic parameters according to an embodiment of the present invention;

[0052] Figure 2 is a flow chart of another method for predicting engine combustion characteristic parameters according to an embodiment of the present invention;

[0053] Figure 3 is a structural block diagram of an engine combustion characteristic parameter prediction system according to an embodiment of the present invention;

[0054] Figure 4 4 is a schematic structural diagram of a vehicle controller according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0056] An embodiment of the present invention provides an embodiment of a method for predicting engine combustion characteristic parameters. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0057] In this embodiment, a method for predicting engine combustion characteristic parameters is provided. Figure 1 FIG. 1 is a flow chart of a method for predicting engine combustion characteristic parameters according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0058] Step S101: Determine a reference engine for the target engine.

[0059] It should be noted that in this embodiment, the target engine refers to the engine to be designed, also called a new model or target engine; the reference engine is an engine with flow similarity to the target engine, also called a reference model or reference engine.

[0060] In this embodiment, the specific method for determining the reference engine is not limited and can be adjusted based on actual project requirements. For example, based on traditional similarity theory and dimensionless parameters such as Reynolds number and Mach number, reference engines similar to the target engine are selected. This is for illustrative purposes only.

[0061] Step S102: constructing a reference combustion model of a reference engine.

[0062] In this embodiment, the reference combustion model represents a three-dimensional physical and chemical model, which takes into account multiple factors such as the flow field, temperature field, concentration field in the cylinder and their interactions to simulate the combustion process, and can more accurately describe the combustion phenomenon.

[0063] It should be noted that the specific content of the reference combustion model in this embodiment can be found in conventional combustion models in the art, such as the Weibe combustion model (also known as the Weber combustion model, which uses empirical functions such as the Weber function to fit the heat release rate curve, and the combustion parameters involved include combustion start angle, duration, shape factor, etc.), the Semenov auto-ignition model (which uses the Arrhenius reaction rate equation to predict the auto-ignition process of the pre-knock mixture). In addition, the specific construction process (i.e., the modeling process) of the reference combustion model can be carried out using commercial simulation software, such as VL BOOST, GT-Power, or other one-dimensional simulation software that supports parameter setting in the crankshaft angle domain to construct the corresponding model. This is for illustrative purposes only and is not intended to be limiting.

[0064] Step S103 , simulating the reference combustion model, and outputting the corresponding maximum temperature of the unburned zone and the combustion duration at each speed and torque.

[0065] It should be noted that the maximum unburned zone temperature in this embodiment reflects the temperature distribution of the unburned mixture in the cylinder. Specifically, it refers to the maximum temperature reached in the region of the combustion chamber that is not directly ignited by the flame. In practical applications, during engine combustion (such as spark ignition in a gasoline engine or compression ignition in a diesel engine), the flame propagates outward from the ignition center, gradually igniting the mixture. However, due to factors such as the combustion chamber geometry, mixture distribution, airflow motion, or combustion anomalies (such as detonation or misfire), the mixture in some areas may not be fully ignited by the flame, thus forming an "unburned zone." Furthermore, the combustion duration essentially refers to the crankshaft angle range corresponding to 10% to 90% of the cumulative heat release during the combustion process.

[0066] In this embodiment, a reference combustion model is simulated, and the maximum temperature of the unburned zone and the combustion duration corresponding to different speeds and torques can be directly obtained by setting corresponding parameters.

[0067] In step S104 , an unburned zone maximum temperature matrix is ​​constructed based on the corresponding unburned zone maximum temperatures at each speed and torque, and a combustion duration matrix is ​​constructed based on the corresponding combustion durations at each speed and torque.

[0068] It should be noted that in this embodiment, the unburned zone maximum temperature matrix is ​​constructed by the unburned zone maximum temperatures corresponding to multiple different speeds and torques; the combustion duration matrix is ​​constructed by the combustion duration corresponding to multiple different speeds and torques; the specific dimensions of the above two matrices can be adaptively determined according to the actual number of data.

[0069] Step S105 , predicting the combustion characteristic parameters of the target engine according to the unburned zone maximum temperature matrix and the combustion duration matrix.

[0070] It should be noted that the combustion characteristic parameters of this embodiment primarily represent combustion characteristic parameters, such as combustion duration, which require extensive bench testing and operating condition-by-operating condition testing in traditional engine development. These parameters suffer from low parameter prediction accuracy, poor results, long cycle times, and high costs. It should be noted that the specific contents of the combustion characteristic parameters of this embodiment can be adaptively adjusted based on actual needs and are not specifically limited here.

[0071] The engine combustion characteristic parameter prediction method of the embodiment of the present invention constructs a reference combustion model of the reference engine by screening a reference engine with a similar in-cylinder flow level as the target engine, uses its experimentally verified reference combustion model to extract a combustion characteristic matrix, and predicts the combustion characteristic parameters of the target engine based on the combustion characteristic matrix. This not only ensures the prediction accuracy and effect of the combustion characteristic parameters of the new engine model, but also significantly reduces development costs and shortens the prediction cycle, providing reliable data support for engine combustion optimization and performance prediction.

[0072] In this embodiment, a method for predicting engine combustion characteristic parameters is provided. Figure 2 FIG. 1 is a flow chart of another method for predicting engine combustion characteristic parameters according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0073] Step S201: Determine a reference engine for the target engine.

[0074] Specifically, the above step S201 includes:

[0075] Step S2011, respectively determining the compression ratio, port tumble ratio, and stroke-to-bore ratio of the target engine.

[0076] It should be noted that the compression ratio of the engine in this embodiment is the ratio of the total cylinder volume (i.e., the volume when the piston is at the bottom dead center) to the combustion chamber volume (i.e., the volume when the piston is at the top dead center). It reflects the degree of mixture compression. The higher the compression ratio, the higher the temperature and pressure at the end of compression, which is conducive to improving thermal efficiency. The compression ratio can be directly calculated through engine design parameters or determined using a compression ratio tester. The tumble ratio in the airway refers to the airflow movement around the horizontal axis of the cylinder formed during the intake process. The tumble ratio is defined as the ratio of the tumble angular velocity to the crankshaft angular velocity. It can be measured experimentally (e.g., using a steady flow test bench to simulate the intake process and measure the airflow velocity distribution at the airway outlet). , and then calculate the tumble ratio) or perform numerical simulation to obtain the flow field distribution and then process and calculate the tumble ratio; the stroke-to-diameter ratio is the ratio of the piston stroke (expressed as S) to the cylinder diameter (expressed as D), which affects the average piston speed (for example, a long-stroke engine has a higher piston speed and greater friction loss at the same speed), or affects the shape of the combustion chamber (for example, a short-stroke engine has a flatter combustion chamber, which can suppress knock but may cause insufficient scavenging). The piston stroke (i.e., the distance between the top dead center and the bottom dead center) and the cylinder inner diameter can be measured with a caliper or micrometer to calculate the ratio or directly determine it by referring to the engine technical manual; the above examples are for illustration only and are not intended to be limiting.

[0077] Step S2012 , selecting an engine that meets preset engine model difference requirements based on compression ratio, port tumble ratio, and stroke-to-bore ratio as a reference engine for the target engine.

[0078] In this embodiment, the preset model difference requirement is the design requirement of the target engine for parameters characterizing the in-cylinder flow level, such as compression ratio, air tumble ratio and stroke-to-bore ratio. The specific values ​​are adaptively adjusted according to actual needs. For example, the preset model difference requirement is that the difference in air tumble ratio between the reference engine and the target engine is less than 10%.

[0079] In the embodiment of the present invention, the three core structural parameters of compression ratio, air tumble ratio and stroke-to-bore ratio are used to screen reference engines. Based on the precise matching of combustion physics similarities, reference engines with similar in-cylinder flow levels as the target engine can be screened, providing design guidance for the combustion characteristic parameters of subsequent new models.

[0080] Step S202: construct a reference combustion model of a reference engine.

[0081] Specifically, the above step S202 includes:

[0082] Step S2021: construct a combustion model based on the Weber function.

[0083] In this embodiment, the relevant contents of the combustion model are referred to above and will not be repeated here.

[0084] Step S2022: Acquire test data of a reference engine, where the test data at least includes speed, torque, charging efficiency, and fuel consumption rate.

[0085] In this embodiment, the specific method for obtaining the test data is not limited in detail herein and can be determined by referring to conventional data acquisition methods in the art, such as the volumetric efficiency (VE), which is the ratio of the actual air mass entering the cylinder to the theoretical maximum intake volume, reflecting the efficiency of the intake system (i.e., the higher the VE, the stronger the cylinder's "breathing" ability, which can burn more fuel and increase power. For example, the VE of a high-performance gasoline engine can reach over 95%). The data can be directly measured using a Coriolis mass flowmeter; or indirectly calculated and determined by the cylinder pressure method by reverse propulsion air volume; the fuel consumption rate, also known as fuel consumption or brake specific fuel consumption (BSFC), represents the fuel consumption per unit effective power and reflects the fuel economy of the engine (i.e., the lower the BSFC, the higher the energy conversion efficiency). The data can be determined specifically through a steady-state test method, which is provided for illustrative purposes only.

[0086] In step S2023 , the test data are sequentially imported into the combustion model for calibration, and the charging efficiency and fuel consumption rate output by the combustion model simulation at each speed and torque are correspondingly obtained.

[0087] In step S2024 , the efficiency deviation between the charging efficiency outputted by each simulation and the corresponding charging efficiency in the test data, and the fuel consumption deviation between the fuel consumption rate outputted by each simulation and the corresponding fuel consumption rate in the test data are calculated respectively.

[0088] Step S2025: When any of the efficiency deviation and the fuel consumption deviation meets the preset accuracy requirement, the calibration is stopped, and the current combustion model is used as the reference combustion model of the reference engine.

[0089] In this embodiment, the specific content of the preset accuracy requirement can be adaptively adjusted according to actual needs. For example, the preset accuracy requirement is that the error accuracy is within 5%, which is only for illustrative purposes.

[0090] In the embodiment of the present invention, a reference combustion model is constructed based on the combustion model of the Weber function and the test data of the reference engine, which can take into account the flexibility and physical accuracy of the actual working conditions of the engine, thereby ensuring a high degree of consistency between the model and the actual operation, and laying the foundation for the subsequent prediction of the combustion characteristics of the target engine.

[0091] Step S203: Simulate the reference combustion model and output the corresponding maximum temperature of the unburned zone and the combustion duration at each speed and torque. Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0092] In step S204 , an unburned zone maximum temperature matrix is ​​constructed based on the corresponding unburned zone maximum temperatures at each speed and torque, and a combustion duration matrix is ​​constructed based on the corresponding combustion durations at each speed and torque.

[0093] In practical applications, exhaust gas recirculation (EGR) systems are used during engine operation to reduce nitrogen oxide emissions, improve combustion characteristics, and thus ensure engine performance and power output. Since the introduction of exhaust gas recirculation (EGR) reduces engine knock tendency (i.e., lowers combustion temperature and prolongs combustion duration), in this embodiment, EGR correction is performed on the obtained unburned zone maximum temperature matrix and combustion duration matrix to ensure the accuracy of these two types of combustion characteristic matrices.

[0094] In this embodiment, the unburned zone maximum temperature matrix and the combustion duration matrix are respectively corrected based on the preset exhaust gas recirculation rate, and corresponding corrected unburned zone maximum temperature matrix and combustion duration matrix are obtained.

[0095] It should be noted that the preset exhaust gas recirculation rate (EGR rate) in this embodiment is determined based on actual needs, such as by statistical regression of a large amount of experimental data. This is provided for illustrative purposes only. Specifically, by incorporating the preset exhaust gas recirculation rate into the unburned zone maximum temperature matrix and the combustion duration matrix, the impact of the exhaust gas recirculation rate on the combustion process can be fully considered in the prediction of combustion characteristic parameters, further improving the accuracy of subsequent predictions of the target engine's combustion characteristics.

[0096] Step S205 , predicting the combustion characteristic parameters of the target engine according to the unburned zone maximum temperature matrix and the combustion duration matrix.

[0097] In this embodiment, the combustion characteristic parameters include MBF50% and combustion duration. It should be noted that MBF50% in this embodiment is a quantitative indicator of combustion phasing (i.e., MBF50% corresponds to the point in the combustion process when 50% of the fuel is completely burned and is a key indicator for evaluating combustion efficiency and heat release rate). Its ideal position is generally approximately 10-15°CA after top dead center, when in-cylinder pressure and temperature reach peak values ​​and thermal efficiency is highest. If MBF50% is advanced or delayed, it may lead to knock or incomplete combustion. Combustion duration is a core indicator of combustion speed, representing the crankshaft angle difference corresponding to the cumulative mass fraction of fuel burned from 10% to 90% (also known as ΔCA90, in °CA). A smaller ΔCA90 indicates a faster combustion speed and higher thermal efficiency (for example, pre-chamber jet ignition can reduce ΔCA90 by 30%). However, an excessively fast combustion speed, such as ΔCA90 < 20°CA, may induce knock, while an excessively slow combustion speed, such as ΔCA90 > 40°CA, may increase afterburning.

[0098] Specifically, the above step S205 includes:

[0099] Step S2051: Determine the combustion duration of the target engine based on the combustion duration matrix.

[0100] Specifically, the above step S2051 includes:

[0101] Step A1: Determine the current design speed and current design torque of the target engine.

[0102] In this embodiment, the current design speed and the current design torque can be determined according to actual design requirements of the target engine.

[0103] Step A2: Filtering the combustion duration corresponding to the current design speed and the current design torque from the combustion duration matrix as the combustion duration of the target engine.

[0104] The combustion duration matrix in the embodiment of the present invention stores the combustion characteristic data of the reference engine under different speed and torque conditions, while the design speed and torque of the target engine directly correspond to the actual working scenario; specifically, by accurately matching the design point conditions of the target engine, combustion duration parameters that are highly consistent with the actual operating conditions of the target engine can be directly obtained, further avoiding the errors caused by extrapolation across operating conditions and ensuring the targeted and accurate prediction.

[0105] Step S2052: construct a target combustion model of the target engine, and predict MBF50% of the target engine based on the unburned zone maximum temperature matrix and the target combustion model.

[0106] Specifically, the above step S2052 predicts the MBF50% of the target engine based on the unburned zone maximum temperature matrix and the target combustion model, including:

[0107] Step B1: input the maximum temperature of the unburned zone corresponding to each speed and torque in the maximum temperature matrix of the unburned zone into the target combustion model to obtain the corresponding simulated MBF50%.

[0108] In this embodiment, different rotation speeds and torques can be set directly through the simulation software, and the corresponding simulated MBF50% can be output.

[0109] Step B2: determining the predicted maximum unburned zone temperature of the target engine based on each simulated MBF50%, and calculating the temperature error between the predicted maximum unburned zone temperature and the corresponding maximum unburned zone temperature in the maximum unburned zone temperature matrix.

[0110] In step B3, the control parameters of the target combustion model are corrected based on the temperature error. The target combustion model is then fed with the maximum unburned zone temperature corresponding to each speed and torque in the maximum unburned zone temperature matrix, thereby obtaining the simulated MBF50%. This simulated MBF50% is used as the target engine's MBF50% when the simulated MBF50% meets a preset crankshaft angle threshold or the temperature error is less than a preset temperature difference threshold.

[0111] In this embodiment, specific values ​​of the preset crankshaft angle threshold and the preset temperature difference threshold are adaptively set according to actual needs and are not limited in detail here.

[0112] In the embodiment of the present invention, by inputting the unburned zone maximum temperature matrix into the target combustion model to generate a simulated MBF50%, and reversely calculating the temperature error to correct the model's control parameters, the differences in combustion characteristics between the target engine and the reference engine can be dynamically compensated, making the model output closer to the actual combustion process, thereby significantly improving the prediction accuracy of MBF50%, and greatly ensuring the performance prediction of the engine.

[0113] In the embodiment of the present invention, the combustion duration of the target engine is determined based on the combustion duration matrix of the reference engine, and the MBF50% meter is predicted in combination with the target combustion model constructed for the target engine and the maximum temperature matrix of the unburned zone of the reference engine. The combustion characteristic data of the reference engine can be deeply coupled with the personalized model of the target engine, which not only can accurately migrate the combustion duration, improve the prediction efficiency and engineering adaptability, but also enhance the accuracy of the combustion phase, greatly meeting the requirements for automatic generation of combustion characteristic parameters of new models.

[0114] In this embodiment, the target engine (i.e., the prediction engine) is a 1.5L engine, that is, the prediction method of the above embodiment is used to predict the combustion characteristics of the 1.5L prediction engine. Accordingly, a combustion prediction method based on reference model transfer is proposed. Specifically, by establishing a flow similarity criterion between the reference engine and the prediction engine, extracting the combustion temperature field characteristics of the reference engine, and combining PID control (Proportional Integral Derivative) to achieve automatic matching of combustion phases, the efficiency and accuracy of the prediction of combustion characteristics of new models are significantly improved. In addition, this prediction method can also be used to predict the power, torque, and fuel consumption of the engine in the design stage; and can adapt to changes in engine control parameters and operating boundaries, such as compression ratio, VVT (Variable Valve Timiing), EGR, water temperature, intake temperature, etc. The specific prediction process includes the following steps:

[0115] 1. Select a reference model for the predicted model.

[0116] In this embodiment, the difference in intake duct tumble intensity between the reference model and the predicted model is within 2, and the difference in stroke-to-diameter ratio S / D between the reference model and the predicted model is within 0.2.

[0117] 2. Use commercial software (such as GT-POWER) to establish a thermodynamic simulation model of the reference engine, which specifically includes the ventilation process, in-cylinder heat exchange process and combustion process. The Weibe combustion model is selected as the combustion model.

[0118] In this embodiment, the process of establishing the thermodynamic simulation model can refer to the commercial software help documentation.

[0119] 3. Based on the universal characteristic test data of the reference model (including speed, torque, combustion phase, charging efficiency, effective fuel consumption rate, etc.), the model is calibrated so that the error between the simulation output and the measured performance is less than 3%.

[0120] In this embodiment, the model parameters are calibrated based on the test data of the reference model so that the error between the simulation output and the measured performance is less than 3%.

[0121] 4. Extract the calculated values ​​of the maximum unburned zone temperature of the cycle at each speed and torque of the calibrated reference engine thermodynamic simulation model to construct the reference engine unburned zone maximum temperature matrix Tmax (including the maximum unburned zone temperature corresponding to different speeds and torques).

[0122] In this embodiment, considering that the introduction of EGR can reduce the tendency of engine knock, the empirical formula for EGR rate correction is obtained based on the statistical regression formula of a large amount of experimental data as follows:

[0123] Tmax_egr=Tmax+1.5×EGR_Rate×100(1)

[0124] Among them, Tmax_egr is the highest temperature in the unburned area after correction; EGR_Rate is the preset exhaust gas recirculation rate, and its specific value can be adaptively set according to actual requirements.

[0125] 5. Extract the measured combustion duration data of the reference engine's universal characteristic test at different speeds and torques to construct the combustion duration matrix Burndur (including the combustion durations corresponding to different speeds and torques).

[0126] In this embodiment, also considering that the introduction of EGR will reduce the engine combustion rate, the empirical formula for correcting the combustion duration by the EGR rate is obtained according to the statistical regression formula of a large amount of experimental data as follows:

[0127] Burndur_egr = Burndur + 0.4 × EGR_Rate × 100(2)

[0128] Among them, Burndur_egr is the combustion duration after correction.

[0129] 6. Establish a prediction engine model and integrate a combustion prediction module.

[0130] In this embodiment, the combustion prediction module includes a PID controller. Among them, the control period of the PID controller is 0.1° crankshaft angle. With the Tmax_egr of each speed load as the target, the output of MBF50% per cycle is adjusted. It should be noted that the PID controller adopts negative feedback control, that is, when the highest temperature in the unburned area > Tmax_egr, the output of MBF50% is increased; if the highest temperature in the unburned area < Tmax_egr, the output of MBF50% is decreased until MBF50% = 6°CA (i.e., the preset crankshaft angle threshold) or the absolute value of the temperature error in the unburned area < 1K (i.e., the preset temperature difference threshold), the control ends and the current output of MBF50% is used as the combustion characteristic parameter of the prediction engine.

[0131] 7. Change the design parameters (such as compression ratio, cam profile, etc.) or control parameters (such as VVT phase, EGR rate, etc.), and output the combustion characteristic parameters under the corresponding working conditions in real time.

[0132] In a specific embodiment, the specific steps for establishing the model and obtaining the parameters of the reference engine include:

[0133] 1. Select a certain 1.5L engine as the reference engine, and its parameters are compared with those of the prediction engine as shown in the following table. <​​​​​​2. Use the software GT-POWER to establish a thermodynamic model of the reference model.

[0137] In this embodiment, the thermodynamic model includes detailed geometric features of the intake and exhaust systems, uses the WoschniGT heat transfer model for in-cylinder heat exchange, and uses the detailed wall temperature solver model EngCylTWallSoln for in-cylinder wall temperature. The combustion model uses the Weibe combustion model EngCylCombSIWiebe. Test data from a reference engine in the speed range of 1500-3000 rpm and torque range of 20 Nm-120 Nm is then imported to appropriately adjust the in-cylinder heat transfer coefficient and calibrate the model. This ensures that the deviation accuracy of the reference engine's thermodynamic model for charging efficiency (VE) and specific fuel consumption (BSFC) is within 3%. The relevant parameters involved in the model calibration process are shown in the following table.

[0138] Table 2

[0139]

[0140]

[0141] 3. Extract the unburned zone maximum temperature matrix Tmax and the combustion duration matrix Burndur of the reference model as the input of the reference model. The specific contents of the unburned zone maximum temperature matrix Tmax and the combustion duration matrix Burndur are shown in the following table respectively.

[0142] Table 3

[0143]

[0144] Table 4

[0145]

[0146] In one embodiment, the steps of establishing a prediction model and predicting combustion phase include:

[0147] 1. Establish a thermodynamic model of the predicted model based on the design parameters. The modeling method is the same as that of the reference model. Note that the model of the predicted model includes the EGR pipeline.

[0148] 2. Establish a combustion phase prediction module.

[0149] In this embodiment, the combustion duration of the predicted engine is determined according to the corresponding data in the combustion duration matrix Burndur of the reference engine, and is corrected according to the target EGR rate.

[0150] In this implementation, the MBF50% prediction for the engine model is achieved by establishing a PID controller with Tmax_egr as the target. Tmax_egr uses the simulation results of the reference engine model (i.e., the unburned zone maximum temperature matrix Tmax) as input and is modified based on the target EGR rate. Note that in this feedback control process, MBF50% is the control variable; the P term of the PID controller is set to -0.1, and the I term is set to -0.5, for illustrative purposes only.

[0151] In this embodiment, the prediction model is run to obtain the MBF50% prediction results as shown in the following table.

[0152] Table 5

[0153]

[0154] It should be noted that the prediction results in the table above show that the difference between the simulated and measured MBF50% is within 2°CA, which accurately predicts the combustion phasing of the new model.

[0155] In one embodiment, the effect of design parameter changes on performance is predicted. Specifically, the compression ratio (CR) in the predicted engine thermodynamic model is changed from 14 to 13. The corresponding model simulation prediction results for MBF50% are shown in the following table.

[0156] Table 6

[0157]

[0158]

[0159] It should be noted that the prediction results in the table above show that in the low-load range, MBF50% remains unchanged; in the high-load range, MBF50% advances by 1-3°CA. This is consistent with the trend that knock tendency decreases and combustion phase advances after compression ratio reduction. Therefore, the prediction method of this embodiment can be used for qualitative analysis of the impact of design changes on combustion characteristics during the conceptual design phase. Specifically, the above examples demonstrate that this prediction method can relatively accurately predict MBF50% and engine performance, and is suitable for performance analysis of design parameter changes, possessing significant engineering application value.

[0160] In summary, the engine combustion characteristic parameter prediction method of the embodiment of the present invention, by screening a reference engine with a similar in-cylinder flow level as the new model, uses its experimentally verified combustion model to predict the combustion characteristic parameters of the new model, which not only improves the prediction accuracy of the combustion parameters, but also meets the demand for automatic generation of the combustion characteristic parameters of the new model.

[0161] This embodiment also provides an engine combustion characteristic parameter prediction system, which is used to implement the above-mentioned embodiments and preferred embodiments. Details already described will not be repeated here. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the systems described in the following embodiments are preferably implemented using software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0162] The present invention provides an engine combustion characteristic parameter prediction system, such as Figure 3 As shown, the system includes:

[0163] The reference engine type determination module 301 is used to determine a reference engine for the target engine.

[0164] The combustion model building module 302 is used to build a reference combustion model of a reference engine.

[0165] The combustion model simulation module 303 is used to simulate the reference combustion model and output the corresponding maximum temperature of the unburned zone and the combustion duration at each speed and torque.

[0166] The characteristic matrix construction module 304 is used to construct an unburned zone maximum temperature matrix based on the corresponding unburned zone maximum temperature at each speed and torque, and to construct a combustion duration matrix based on the corresponding combustion duration at each speed and torque.

[0167] The characteristic parameter prediction module 305 is used to predict the combustion characteristic parameters of the target engine according to the unburned zone maximum temperature matrix and the combustion duration matrix.

[0168] In some optional embodiments, the reference model determination module 301 includes: a first model determination submodule and a second model determination submodule; wherein the first model determination submodule is used to respectively determine the compression ratio, airway tumble ratio and stroke-to-bore ratio of the target engine; the second model determination submodule is used to screen an engine that meets the preset model difference requirements based on the compression ratio, airway tumble ratio and stroke-to-bore ratio as a reference engine for the target engine.

[0169] In some optional embodiments, the combustion model construction module 302 includes: a first model construction submodule, a second model construction submodule, a third model construction submodule, a fourth model construction submodule and a fifth model construction submodule; wherein the first model construction submodule is used to construct a combustion model based on the Weber function; the second model construction submodule is used to obtain test data of a reference engine, the test data including at least speed, torque, charging efficiency and fuel consumption rate; the third model construction submodule is used to sequentially import the test data into the combustion model for calibration, and accordingly obtain the charging efficiency and fuel consumption rate of the combustion model simulation output at each speed and torque; the fourth model construction submodule is used to respectively calculate the efficiency deviation between the charging efficiency of each simulation output and the corresponding charging efficiency in the test data, and the fuel consumption deviation between the fuel consumption rate of each simulation output and the corresponding fuel consumption rate in the test data; the fifth model construction submodule is used to stop calibration when any efficiency deviation and fuel consumption deviation meet the preset accuracy requirements, and use the current combustion model as the reference combustion model of the reference engine.

[0170] In some optional embodiments, the system also includes: a characteristic matrix correction module, which is used to correct the unburned zone maximum temperature matrix and the combustion duration matrix based on a preset exhaust gas recirculation rate, and obtain corresponding corrected unburned zone maximum temperature matrix and combustion duration matrix.

[0171] In some optional embodiments, the characteristic parameter prediction module 305 includes: a first parameter prediction submodule and a second parameter prediction submodule; wherein, the first parameter prediction submodule is used to determine the combustion duration of the target engine based on the combustion duration matrix; the second parameter prediction submodule is used to construct a target combustion model of the target engine, and predict the MBF50% of the target engine based on the unburned zone maximum temperature matrix and the target combustion model.

[0172] In some optional embodiments, the first parameter prediction submodule includes: a parameter determination unit and a parameter screening unit; wherein the parameter determination unit is used to determine the current design speed and the current design torque of the target engine; the parameter screening unit is used to screen the combustion duration corresponding to the current design speed and the current design torque from the combustion duration matrix as the combustion duration of the target engine.

[0173] In some optional embodiments, the second parameter prediction submodule includes: a parameter input unit, a parameter calculation unit and a parameter control unit; wherein the parameter input unit is used to input the unburned zone maximum temperature corresponding to each speed and torque in the unburned zone maximum temperature matrix into the target combustion model respectively, and obtain the corresponding simulated MBF50%; the parameter calculation unit is used to determine the predicted unburned zone maximum temperature of the target engine based on each simulated MBF50%, and respectively calculate the temperature error between the predicted unburned zone maximum temperature and the corresponding unburned zone maximum temperature in the unburned zone maximum temperature matrix; the parameter control unit is used to correct the control parameters of the target combustion model based on the temperature error, and return to the step of inputting the unburned zone maximum temperature corresponding to each speed and torque in the unburned zone maximum temperature matrix into the target combustion model respectively, and obtain the corresponding simulated MBF50%, until the simulated MBF50% meets the preset crankshaft angle threshold or the temperature error is less than the preset temperature difference threshold, and the simulated MBF50% is used as the MBF50% of the target engine.

[0174] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0175] The engine combustion characteristic parameter prediction system in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0176] The engine combustion characteristic parameter prediction system of an embodiment of the present invention screens a reference engine with a similar in-cylinder flow level to the target engine, constructs a reference combustion model of the reference engine, and then uses the reference combustion model to extract the combustion characteristic matrix of the unburned zone maximum temperature matrix and the combustion duration matrix, and predicts the combustion characteristic parameters of the target engine based on the combustion characteristic matrix. This can greatly ensure the accuracy and effect of the prediction of the combustion characteristic parameters of the new engine model, while also significantly reducing development costs, thereby shortening the engine combustion characteristic parameter prediction cycle, and meeting the demand for automatic generation of combustion characteristic parameters of the new engine model.

[0177] An embodiment of the present invention further provides a vehicle including a controller. The controller in this embodiment is a vehicle controller, configured to power on / off, and wake up its connected sub-controllers and network nodes, and to collect real-time output current from each power supply interface. Other controllers with the aforementioned functions are also applicable.

[0178] Figure 4 is a schematic diagram of the structure of the controller provided in an optional embodiment of the present invention, such as Figure 4 As shown, the controller includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. The various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the controller, including instructions stored in or on the memory to display graphical information of a GUI on an external input / output system (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple controllers can be connected, and each controller provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 4 A processor 10 is taken as an example.

[0179] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0180] The memory 20 stores instructions that can be executed by at least one processor 10, so as to enable at least one processor 10 to execute the method shown in the above embodiment.

[0181] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created according to the use of the controller, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the controller via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0182] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0183] The controller further includes a communication interface 30 for the main control chip to communicate with other devices or a communication network.

[0184] A computer-readable storage medium is also provided in an embodiment of the present invention. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor main control chip or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0185] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for predicting engine combustion characteristic parameters, characterized in that: The method comprises: Determine the reference engine of the target engine; constructing a reference combustion model of the reference engine; Simulating the reference combustion model and outputting the corresponding maximum temperature of the unburned zone and the combustion duration at each speed and torque; A maximum temperature matrix of the unburned zone is constructed based on the maximum temperature of the unburned zone corresponding to each speed and torque, and a combustion duration matrix is ​​constructed based on the combustion duration corresponding to each speed and torque; The combustion characteristic parameters of the target engine are predicted based on the unburned zone maximum temperature matrix and the combustion duration matrix.

2. The method for predicting engine combustion characteristic parameters according to claim 1, characterized in that: The step of determining a reference engine for the target engine includes: Determine the compression ratio, port tumble ratio and stroke-to-bore ratio of the target engine respectively; An engine that meets preset engine model difference requirements is selected based on the compression ratio, the port tumble ratio, and the stroke-to-bore ratio as a reference engine for the target engine.

3. The method for predicting engine combustion characteristic parameters according to claim 1, characterized in that: The constructing of the reference combustion model of the reference engine comprises: Construct a combustion model based on the Weber function; Acquiring test data of the reference engine, the test data including at least speed, torque, charging efficiency, and fuel consumption rate; sequentially importing the test data into the combustion model for calibration, and correspondingly obtaining the charging efficiency and fuel consumption rate output by the combustion model simulation at various speeds and torques; respectively calculating the efficiency deviation between each of the charging efficiencies output by the simulation and the corresponding charging efficiencies in the test data, and the fuel consumption deviation between each of the fuel consumption rates output by the simulation and the corresponding fuel consumption rates in the test data; When any of the efficiency deviation and the fuel consumption deviation meets the preset accuracy requirement, the calibration is stopped, and the current combustion model is used as the reference combustion model of the reference engine.

4. The method for predicting engine combustion characteristic parameters according to claim 1, characterized in that: Before predicting the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix, the method further includes: The unburned zone maximum temperature matrix and the combustion duration matrix are respectively corrected based on a preset exhaust gas recirculation rate, and corresponding corrected unburned zone maximum temperature matrix and combustion duration matrix are obtained.

5. The method for predicting engine combustion characteristic parameters according to any one of claims 1 to 4, characterized in that: The combustion characteristic parameters include MBF50% and combustion duration; and the prediction of the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix includes: determining a combustion duration of the target engine based on a combustion duration matrix; A target combustion model of the target engine is constructed, and MBF50% of the target engine is predicted based on the unburned zone maximum temperature matrix and the target combustion model.

6. The method for predicting engine combustion characteristic parameters according to claim 5, characterized in that: The determining the combustion duration of the target engine based on the combustion duration matrix includes: Determining a current design speed and a current design torque of the target engine; The combustion duration corresponding to the current design speed and the current design torque is selected from the combustion duration matrix as the combustion duration of the target engine.

7. The method for predicting engine combustion characteristic parameters according to claim 6, characterized in that: The method of predicting MBF50% of the target engine based on the unburned zone maximum temperature matrix and the target combustion model includes: Inputting the maximum temperature of the unburned zone corresponding to each speed and torque in the maximum temperature matrix of the unburned zone into the target combustion model respectively to obtain the corresponding simulated MBF50%; determining a predicted maximum unburned zone temperature of the target engine based on each of the simulated MBF50%, and calculating temperature errors between the predicted maximum unburned zone temperature and the corresponding maximum unburned zone temperature in the maximum unburned zone temperature matrix; The control parameters of the target combustion model are corrected based on the temperature error, and the process returns to the step of inputting the unburned zone maximum temperature corresponding to each speed and torque in the unburned zone maximum temperature matrix into the target combustion model to obtain a corresponding simulated MBF50%. When the simulated MBF50% satisfies a preset crankshaft angle threshold or the temperature error is less than a preset temperature difference threshold, the simulated MBF50% is used as the MBF50% of the target engine.

8. An engine combustion characteristic parameter prediction system, characterized in that: The system comprises: A reference engine model determination module, used to determine a reference engine for a target engine; a combustion model building module, configured to build a reference combustion model of the reference engine; a combustion model simulation module, configured to simulate the reference combustion model and output the corresponding maximum temperature of the unburned zone and the combustion duration at various speeds and torques; a characteristic matrix construction module for constructing an unburned zone maximum temperature matrix based on the corresponding unburned zone maximum temperatures at each speed and torque, and a combustion duration matrix based on the corresponding combustion duration at each speed and torque; The characteristic parameter prediction module is used to predict the combustion characteristic parameters of the target engine based on the unburned zone maximum temperature matrix and the combustion duration matrix.

9. A vehicle, characterized in that: The vehicle includes a controller, which includes: a memory and a processor, the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the engine combustion characteristic parameter prediction method according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the engine combustion characteristic parameter prediction method according to any one of claims 1 to 7.

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