An engine plateau performance self-adaptive calibration method, storage medium and system

Abstract

The application discloses an engine plateau performance self-adaptive calibration method, a storage medium and a system, and relates to the technical field of engines.The method comprises the following steps: engine power performance calibration at a high altitude, engine fuel economy calibration, and engine pollutant emission calibration; based on an engine performance calibration model, an engine plateau performance calibration self-adaptive system is constructed; through a power module, a power attenuation rate of a target altitude is inputted, and target fuel injection quantity and target intake air quantity are acquired; according to an oil consumption and emission module, according to target specific fuel consumption and maximum permissible increase rate of pollutants, minimum fuel injection quantity, intake air quantity, fuel injection advance angle, exhaust gas recirculation rate and power are acquired.The method provides an adaptive calibration method for engine calibration engineers, the system can quickly input target parameters of calibration variables according to product performance tendency, assists engineers in quickly completing product calibration development tests, and can shorten product development time.

Description

Technical Field

[0001] This invention relates to the field of automotive emissions data analysis, specifically to an adaptive calibration method, storage medium, and system for engine high-altitude performance. Background Technology

[0002] As is well known, as altitude increases, atmospheric pressure decreases, engine intake air volume is insufficient, and its power, fuel economy and emission characteristics deteriorate, requiring calibration for the special environment of high altitude.

[0003] Currently, companies use engine benches with altitude simulation or engines in actual altitude environments for calibration. Typically, they conduct targeted calibration based on customers' performance requirements for engines at different altitudes, which is a "one person, one engine" calibration work. This requires calibration engineers to have rich practical calibration experience and a lot of exploration and verification tests. The calibration strategies for different engine models are not the same. Therefore, high-altitude engine performance calibration requires a lot of manpower, material resources and time costs.

[0004] Existing technologies only consider engine performance solutions under single technical features. This invention, from a systems engineering perspective, considers multiple factors and objectives collaboratively, proposing an adaptive calibration method and system for engine high-altitude performance to assist calibration engineers in quickly, efficiently, and cost-effectively completing engine high-altitude performance calibration. The system parameters can be optimized and upgraded based on the accumulation of data to better meet the development needs of real-time engine performance calibration.

[0005] Therefore, there is an urgent need to provide an adaptive calibration method for engine high-altitude performance to assist calibration engineers in completing engine high-altitude performance calibration work quickly, efficiently, and at low cost. Summary of the Invention

[0006] The purpose of this invention is to provide an adaptive calibration method, storage medium, and system for engine high-altitude performance, to assist calibration engineers in quickly, efficiently, and cost-effectively completing engine high-altitude performance calibration.

[0007] The technical solution of this invention is as follows:

[0008] According to a first aspect, the present invention provides an adaptive calibration method for engine high-altitude performance, comprising:

[0009] (1) For prototypes that require high-altitude performance calibration, it is necessary to obtain engine performance data under standard atmospheric pressure and use this as a benchmark for high-altitude calibration.

[0010] (2) Perform dynamic calibration

[0011] Based on an altitude simulation system, the intake and exhaust pressures of the engine at different altitudes are simulated. According to the target power, the fuel injection quantity and intake air quantity are optimized. During the optimization process, it is necessary to control the exhaust temperature to not exceed the maximum permissible exhaust temperature and the turbocharger speed to not exceed the maximum permissible speed. Details are as follows:

[0012]

[0013] In the formula:

[0014] Q FMAX,h Maximum fuel supply at target altitude h, kg / h; P e,0 Power output at flat ground, kW; H represents the power attenuation rate at the target altitude h. U η represents the lower calorific value of the fuel, expressed in kJ / kg; η is the effective thermal efficiency (design thermal efficiency) of the engine; Q A,h Q is the air intake volume at the target altitude h, expressed in kg / h. A,0 The intake air volume for the plains is kg / h; Q F,0 Fuel supply for the plains, kg / h; n Z The turbocharger speed at the target altitude h, in r / min; V Z For compressor volume, m 3 ;ρ A σ is the air density, kg / m³; σ is the compressor's charging efficiency; T 排，h The exhaust temperature at the target altitude h, in °C; T 排,MAX The maximum permissible exhaust temperature of the engine, in °C; n Z,MAX The maximum permissible speed of the turbocharger is expressed in r / min.

[0015] (3) Fuel economy rating

[0016] Calibrling the engine's fuel consumption at high altitudes involves the engine's in-cylinder combustion process. Complete combustion of fuel can improve the engine's fuel utilization rate, that is, increase the engine's fuel economy.

[0017] The parameters involved include fuel injection quantity and fuel injection advance angle.

[0018] This section requires collecting data on engine fuel economy under different injection pressures and injection advance angles to establish a mathematical model. This model will then be used to calibrate fuel economy at high altitudes. The least squares method is used for multivariate nonlinear fitting, and the fitting model is as follows:

[0019]

[0020] In the formula: Q FMIN,h Minimum fuel supply at target altitude h, kg / h; P e,hPower at target altitude h, kW; R, injection advance angle, °CA; η R The thermal efficiency is denoted by R; a0, a1, a2 are fitting coefficients; BSFC MIN,h Minimum specific fuel consumption at altitude h, g / kWh; BSFC 目标,h The target specific fuel consumption is given at an altitude of h, in g / kWh.

[0021] (4) Emissions calibration

[0022] Heavy-duty vehicles in high-altitude environments primarily exhibit excessive NOx and soot emissions. Understanding the trade-off between these two emissions is a key focus and challenge in calibrating diesel engines for heavy-duty vehicles. NOx is rapidly generated in high-temperature, oxygen-rich environments, while soot is rapidly generated in oxygen-deficient environments. NOx emissions are mainly related to the engine's injection advance angle and exhaust gas recirculation (EGR) rate, while soot emissions are primarily related to the injection advance angle and EGR rate. Therefore, it is necessary to pre-fit relevant mathematical models before conducting performance calibration of engines operating at high altitudes.

[0023]

[0024] In the formula:

[0025] E NOx NOx emission concentration, ppm; E soot For carbon soot emission concentration, mg / m3; f EGR The engine's EGR rate is represented by b0, b1, b2, b3, and b4, which are fitting coefficients. c0, c1, and c2 are also fitting coefficients. r represents the air-fuel ratio. NOx,h NOx emission concentration at target altitude h, in ppm; E soot,h E represents the carbon soot emission concentration at the target altitude h, in mg / m3. soot,h E represents the carbon soot emission concentration at the target altitude h, in mg / m3. NOx,0 NOx emission concentration in plains, ppm; E soot,0 The carbon soot emission concentration in the plains is expressed in mg / m3. The pollutant increase rate at the target altitude h; This represents the maximum permissible rate of increase for pollutants.

[0026] According to a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being executable by a processor to implement the steps of the engine high-altitude performance adaptive calibration method described in the present invention.

[0027] According to a third aspect, the present invention provides an adaptive system for calibrating engine high-altitude performance, comprising:

[0028] Power module, based on the power attenuation rate at the target altitude T MAX With n MAX Calculate the permissible fuel injection quantity Q FMAX,h With intake air volume Q A,h :

[0029]

[0030] The fuel consumption and emissions module is based on the target altitude P. e,h BSFC 目标 Calculate the minimum fuel injection quantity Q FMIN,h With the optimal ignition angle R:

[0031]

[0032] according to Mathematical model, calculate fEGR; according to Mathematical model, calculate P.

[0033]

[0034] In summary, the calibration parameter Q for engine performance in high-altitude environments can be obtained. FMIN,h Q A,h , R, f EGR .

[0035] Furthermore, the system's computational logic can be upgraded as needed, such as by adding cyclic calculations and infinite approximation principles, to further optimize engine performance.

[0036] The beneficial effects of this invention include:

[0037] This invention addresses the problem of deteriorating performance of traditional diesel engines at high altitudes by proposing an adaptive calibration method for engines at high altitudes. First, plain data of the engine model to be calibrated is obtained. Model development is then carried out using the plain data to obtain benchmark models for power, economy, and emissions. Next, based on the target performance of the engine at the altitude to be calibrated, the injection and intake parameters of the engine at each altitude are calibrated for the target performance. The model can further shorten product development time, and the synergy of the models enables refined calibration of engine performance. Attached Figure Description

[0038] Figure 1 : Flowchart of the adaptive calibration method of the present invention. Detailed Implementation

[0039] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0040] Example 1

[0041] For prototypes that require high-altitude performance calibration, it is necessary to obtain engine performance data under standard atmospheric pressure and use this as a benchmark for high-altitude calibration.

[0042] Performance Calibration: At high altitudes, engine performance is a primary concern for car owners; therefore, engine performance optimization for high altitudes was the first step. Based on an altitude simulation system, intake and exhaust pressures were simulated at different altitudes. According to the target power, fuel injection and intake air volume were optimized. During the optimization process, exhaust temperature and turbocharger speed were controlled to ensure they did not exceed the maximum permissible exhaust temperature and speed. Details are as follows:

[0043]

[0044] In the formula:

[0045] Q F,h Fuel supply at target altitude h, kg / h; P e,0 Power output at flat ground, kW; η is the power attenuation rate at the target altitude h; HU is the lower calorific value of the fuel, kJ / kg; η is the effective thermal efficiency of the engine (design thermal efficiency); Q A,h Q is the air intake volume at the target altitude h, expressed in kg / h. A,0 The intake air volume for the plains is kg / h; Q F,0 Fuel supply for the plains, kg / h; n Z The turbocharger speed at the target altitude h, in r / min; V Z For compressor volume, L; ρ A σ is the air density, kg / m³; σ is the compressor's charging efficiency; T 排，h The exhaust temperature at the target altitude h, in °C; T 排,max The maximum permissible exhaust temperature of the engine, in °C; n Z,max The maximum permissible speed of the turbocharger is expressed in r / min.

[0046] Fuel economy calibration: This mainly targets the fuel consumption of the engine at high altitudes. It involves the in-cylinder combustion process of the engine. Complete combustion of fuel can improve the fuel utilization rate of the engine, that is, increase the fuel economy of the engine.

[0047] The parameters involved include fuel injection quantity and fuel injection advance angle.

[0048] This requires prior collection of engine fuel economy data under different injection pressures and injection advance angles to establish a mathematical model. This model will then be used to calibrate fuel economy at high altitudes. The least squares method is used for multivariate nonlinear fitting, and the fitting model is as follows:

[0049]

[0050] In the formula: Q FMIN,h Minimum fuel supply at target altitude h, kg / h; P e,h Power at target altitude h, kW; R, injection advance angle, °CA; η R The thermal efficiency is denoted by R; a0, a1, a2 are fitting coefficients; BSFC MIN,h Minimum specific fuel consumption at altitude h, g / kWh; BSFC 目标,h The target specific fuel consumption is given at an altitude of h, in g / kWh.

[0051] Emissions Calibration: Heavy-duty vehicles in high-altitude environments primarily exhibit excessive NOx and soot emissions. Understanding the trade-off between these two emissions is a key focus and challenge in calibrating diesel engines for heavy-duty vehicles. NOx is rapidly generated in high-temperature, oxygen-rich environments, while soot is rapidly generated in oxygen-deficient environments. NOx emissions are mainly related to the engine's injection advance angle and exhaust gas recirculation (EGR) rate, while soot emissions are primarily related to the injection advance angle and EGR rate. Therefore, it is necessary to pre-fit relevant mathematical models before conducting performance calibration of engines operating at high altitudes.

[0052]

[0053] In the formula:

[0054] E NOx NOx emission concentration, ppm; E soot For carbon soot emission concentration, mg / m3; f EGR The engine's EGR rate is represented by b0, b1, b2, b3, and b4, which are fitting coefficients. c0, c1, and c2 are also fitting coefficients. r represents the air-fuel ratio. NOx,h NOx emission concentration at target altitude h, in ppm; E soot,h E represents the carbon soot emission concentration at the target altitude h, in mg / m3. NOx,0 NOx emission concentration in plains, ppm; E soot,0 The carbon soot emission concentration in the plains is expressed in mg / m3. The pollutant increase rate at the target altitude h; This represents the maximum permissible rate of increase for pollutants.

[0055] Constructing an adaptive calibration system for engine high-altitude performance: First, collect engine performance data at low altitudes, and fit the required mathematical formulas based on the given mathematical model. Then, perform adaptive calibration of relevant performance characteristics according to the needs of customers at high altitudes. The detailed process is as follows:

[0056] Power Module

[0057] Based on the power attenuation rate at the target altitude TMAX and nMAX calculate the permissible fuel injection quantity Q FMAX,h With intake air volume Q A,h :

[0058]

[0059] Fuel consumption and emissions module

[0060] Based on the target altitude P e,h BSFC 目标 Calculate the minimum fuel injection quantity Q FMIN,h With the optimal ignition angle R:

[0061]

[0062] according to Mathematical model, calculate fEGR; according to Mathematical model.

[0063]

[0064] In summary, the calibration parameter Q for engine performance in high-altitude environments can be obtained. FMIN,h Q A,h , R, f EGR In addition, the system's calculation logic can be upgraded as needed, such as by adding cyclic calculations and infinite approximation principles, to further optimize engine performance.

[0065] Example 2

[0066] Taking the rated operating point of a certain engine as an example, the feasibility of the relevant model of this patent is explained.

[0067] Obtain plain data, including engine injection parameters, intake parameters, engine power, engine fuel consumption, and emissions data, and use this data to fit the calibration formula:

[0068] The effect of injection angle on thermal efficiency: η R =a0R 2 +a1R+a2

[0069] Pollutant emission model:

[0070] Then, calibration tests can be conducted at a specific altitude. First, it is necessary to determine the engine power attenuation rate at that altitude. Economic indicators BSFC 目标,h Emission deterioration indicators Then, under specific altitude conditions, calibration tests (external characteristic tests and universal tests) are carried out. After obtaining the test data, the data is imported into the prepared model to perform calibration work on power performance, fuel economy and emission characteristics in sequence.

[0071] First, there is the performance calibration: based on the engine's design thermal efficiency η and target power decay rate. The maximum permissible speed n of the turbocharger Z,MAX The engine's maximum fuel consumption Q can then be calculated. FMAX,h Maximum intake volume Q A,h .

[0072]

[0073] The fuel economy at the current maximum fuel consumption is not optimal and needs to be adjusted. A pre-prepared thermal efficiency model can calculate the optimal injection advance angle R based on experimental data, thereby obtaining the minimum fuel consumption Q. FMIN,h The optimal fuel economy index BSFC is obtained based on the model formula. MIN,h .

[0074]

[0075] After resolving the calibration of engine power and fuel economy, the next step is to calibrate its pollutants. NOx and PM in diesel engines are the most challenging aspects of this calibration, requiring adjustments to the EGR rate to balance the trade-off between NOx and PM. Based on a pre-fitted pollutant emission model and experimental data, the recommended EGR rate f can be calculated. EGR .

[0076]

[0077] Finally, based on the minimum fuel consumption Q given by the model... FMIN,h The optimal injection advance angle R and recommended EGR rate were verified through actual engine bench tests. The actual power output Pe, actual fuel economy index BSFC, and pollutant emission degradation rate were calculated to determine if they met the target altitude requirements. If the actual test results differed from the predetermined targets, a secondary calibration could be performed.

Claims

1. An adaptive calibration method for engine high-altitude performance, characterized in that, Includes the following steps: Step (1): For the prototype that needs to be calibrated at high altitude, it is necessary to obtain engine performance data under standard atmospheric pressure and use this as a benchmark to carry out calibration work at high altitude. Step (2), dynamic performance calibration Based on an altitude simulation system, the intake and exhaust pressures of the engine at different altitudes are simulated. According to the target power, the fuel injection quantity and intake air quantity are optimized. The optimization process requires controlling the exhaust temperature to not exceed the maximum permissible exhaust temperature and the turbocharger speed to not exceed the maximum permissible speed. The power performance calibration specifically includes: ； Wherein, joint equation (1) is the objective function, and joint equation (2) is the conditional function; in the equation: The maximum fuel supply at the target altitude h. For plain power, H represents the power attenuation rate at the target altitude h. U Because of the low calorific value of the fuel, Q represents the engine's effective thermal efficiency. A,h The air intake volume at the target altitude h. For the intake volume of the plain, For the fuel supply to the plains, The turbocharger speed at the target altitude h. For compressor volume, air density, The charging efficiency of the compressor; Temperature at the target altitude h The maximum permissible exhaust temperature of the engine. This refers to the maximum permissible speed of the turbocharger; Step (3), fuel economy calibration Calibrling the engine's fuel consumption at high altitudes involves the engine's in-cylinder combustion process. Complete combustion of fuel can improve the engine's fuel utilization rate, that is, increase the engine's fuel economy. The parameters involved include fuel injection quantity and injection advance angle. It is necessary to collect data on engine fuel economy under different injection pressures and injection advance angles beforehand to establish a mathematical model. Then, the fuel economy at high altitudes will be calibrated using this mathematical model, employing the least squares method for multivariate nonlinear fitting. The fuel economy calibration specifically includes: ； Among them, equation (3) is the fuel supply model, equation (4) is the objective function, and equation (5) is the condition function; where: The minimum fuel supply for the target altitude h. The power at the target altitude h, This refers to the fuel injection advance angle. Thermal efficiency at the injection advance angle R; These are the fitting coefficients; BSFC MIN,h The lowest specific fuel consumption BSFC at an altitude of h 目标,h The target specific fuel consumption at altitude h; wherein, the least squares method for multivariate nonlinear fitting specifically includes: collecting experimental data on engine fuel economy under different injection advance angles R, with the injection advance angle R as the independent variable and thermal efficiency as the variable. As the dependent variable, the least squares method is used for the quadratic polynomial model. Perform fitting and determine the fitting coefficients. ; Step (4), emission calibration ； Wherein, equations (6) and (7) are emission concentration models, equation (8) is the objective function, and equation (9) is the conditional function; NOx emission concentration; This refers to the concentration of carbon soot emissions; The engine's EGR rate; , These are the fitting coefficients; The NOx emission concentration at the target altitude h; The carbon soot emission concentration at the target altitude h; The NOx emission concentration in the plains; The concentration of carbon soot emissions in the plains; The pollutant increase rate at the target altitude h; This represents the maximum permissible rate of increase for pollutants.

2. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program can be executed by a processor to implement the steps of the adaptive calibration method for engine high-altitude performance as described in claim 1.

3. An adaptive calibration system for engine high-altitude performance, implementing the adaptive calibration method for engine high-altitude performance as described in claim 1, characterized in that, include: The power module is configured to perform step (2) of the method as described in claim 1. The fuel consumption and emissions module is configured to perform steps (3) and (4) of the method as described in claim 1.

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