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

Abstract

The invention 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 steps of engine dynamic property calibration, engine fuel economy calibration and engine pollutant emission calibration at the high altitude; based on an engine performance calibration model, an engine plateau performance calibration self-adaptive system is constructed; the power attenuation rate of the target altitude is input through a power module, and the target fuel injection quantity and the target air inlet quantity are obtained; and according to the oil consumption and emission module, the minimum oil injection quantity, the air inflow, the oil injection advance angle, the exhaust gas recirculation rate and the power are obtained according to the target specific oil consumption and the maximum allowable increase rate of pollutants. According to the method, a self-adaptive calibration method is provided for an engine calibration engineer, the system can rapidly input target parameters of calibration variables according to the product performance tendency, the engineer is assisted in rapidly completing a calibration development test of a product, and the product development time can be shortened.

Description

Technical Field

[0001] The present invention relates to the field of automobile emission data analysis, and in particular to a method, storage medium and system for adaptively calibrating engine plateau performance. Background Art

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

[0003] Currently, various companies use engine benches with altitude simulation or engines in actual altitude environments for calibration. Targeted calibration is usually carried out based on customer performance requirements for engines at different altitudes. This is a "one person, one engine" calibration process, requiring calibration engineers to have extensive practical calibration experience and a large number of trial and verification tests. The calibration strategies for different engine models are inconsistent, so high-altitude engine performance calibration requires a significant investment of manpower, material resources, and time.

[0004] While existing technologies only consider engine performance solutions based on a single technical characteristic, this invention, from a systems engineering perspective, collaboratively considers multiple factors and objectives. This method and system proposes an adaptive engine high-altitude performance calibration method and system to assist calibration engineers in completing high-altitude engine performance calibration quickly, efficiently, and cost-effectively. The system optimizes and updates system parameters based on accumulated data to better meet the needs of real-time engine performance calibration development.

[0005] Therefore, there is an urgent need to provide an adaptive calibration method for engine plateau 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 the present invention is to provide an engine plateau performance adaptive calibration method, storage medium and system to assist calibration engineers in completing engine high-altitude performance calibration work quickly, efficiently and at low cost.

[0007] The technical solution of the present invention is:

[0008] According to a first aspect, the present invention provides a method for adaptively calibrating engine plateau 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 the altitude simulation system, the intake and exhaust pressures of the engine at different altitudes are simulated, and the injection amount and intake air volume are optimized according to the target power. The optimization process requires that the exhaust temperature cannot exceed the maximum allowable exhaust temperature and the turbocharger speed cannot exceed the maximum allowable speed. The details are as follows:

[0012]

[0013] Where:

[0014] Q FMAX,h is the maximum fuel supply at target altitude h, kg / h; P e,0 is the plain power, kW; is the power attenuation rate at the target altitude h; H U is the lower calorific value of the fuel, KJ / kg; η is the effective thermal efficiency (design thermal efficiency) of the engine; Q A,h is the air intake volume at target altitude h, kg / h; Q A,0 is the air intake volume in the plain, kg / h; Q F,0 is the fuel supply in the plain, kg / h; n Z is the supercharger speed at the target altitude h, r / min; V Z is the compressor capacity, m 3 ρ A is the air density, kg / m3; σ is the charging efficiency of the compressor; T 排，h is the exhaust temperature at the target altitude h, ℃; T 排,MAX is the maximum allowable exhaust temperature of the engine, °C; n Z,MAX The maximum permissible speed of the supercharger, r / min.

[0015] (3) Fuel economy calibration

[0016] Calibration of the engine's fuel consumption at plateaus involves the engine's in-cylinder combustion process. The complete combustion of fuel can improve the engine's fuel utilization rate, that is, the engine's fuel economy is increased.

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

[0018] Here, we need to collect data on engine fuel economy at different injection pressures and injection advance angles to establish a mathematical model, and then use the mathematical model to calibrate the fuel economy at high altitudes. Here, the least squares method is used for multivariate nonlinear fitting, and the fitting model is as follows:

[0019]

[0020] Where: Q FMIN,h is the minimum fuel supply at the target altitude h, kg / h; P e,his the power at the target altitude h, kW; R is the injection advance angle, °CA; η R is the thermal efficiency at the injection advance angle R; a0, a1, a2 are fitting coefficients; BSFC MIN,h is the minimum specific fuel consumption at altitude h, g / kWh; BSFC 目标,h is the target specific fuel consumption at altitude h, g / kWh.

[0021] (4) Emission calibration

[0022] Heavy-duty vehicles primarily experience excessive NOx and soot emissions in high-altitude environments. The trade-off between these two emissions is a key and challenging aspect of heavy-duty diesel engine calibration. NOx is rapidly generated in high-temperature, oxygen-rich environments, while soot is rapidly generated in oxygen-deficient environments. NOx is primarily correlated with the engine's injection advance angle and exhaust gas recirculation (EGR rate), while soot is primarily related to the injection advance angle and EGR rate. Therefore, prior mathematical modeling is crucial for high-altitude engine performance calibration.

[0023]

[0024] Where:

[0025] E NOx is the NOx emission concentration, ppm; E soot is the soot emission concentration, mg / m3; f EGR is the EGR rate of the engine; b0, b1, b2, b3, b4 are fitting coefficients; c0, c1, c2 are fitting coefficients; r is the air-fuel ratio; E NOx,h is the NOx emission concentration at the target altitude h, ppm; E soot,h is the soot emission concentration at the target altitude h, mg / m3; E soot,h is the soot emission concentration at the target altitude h, mg / m3; E NOx,0 is the NOx emission concentration in the plain, ppm; E soot,0 is the soot emission concentration in the plain, mg / m3; is the pollutant increase rate at the target altitude h; is the maximum permissible increase rate of pollutants.

[0026] According to a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which can be executed by a processor to implement the steps of the engine plateau performance adaptive calibration method described in the present invention.

[0027] According to a third aspect, the present invention provides an engine plateau performance calibration adaptive system, comprising:

[0028] Power module, power attenuation rate according to target altitude 、T MAX With n MAX Calculate the permissible injection quantity Q FMAX,h and intake air volume Q A,h :

[0029]

[0030] Fuel consumption and emission module, according to the target altitude P e,h , BSFC 目标 , calculate the minimum injection quantity Q FMIN,h With the best 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 of the engine performance under plateau environment can be obtained FMIN,h , Q A,h , R, f EGR .

[0035] Furthermore, the system calculation logic can be upgraded as needed, such as adding setting loop calculation and infinite approximation principle, which can further optimize the performance of the engine.

[0036] The beneficial effects of the present invention include:

[0037] Aiming at the problem of deterioration of performance of traditional diesel engines at plateaus, the present invention proposes an adaptive calibration method for engines at high altitudes. First, it is necessary to obtain plain data of the engine model to be calibrated, and use the plain data to develop a model to obtain benchmark models such as power, economy, and emissions. Then, based on the target performance of the engine at the altitude to be calibrated, the injection parameters and intake parameters under the target performance of the engine at each altitude point are calibrated. With the help of the model, product development time can be further shortened, and the synergy of the model can achieve refined calibration of engine performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 : Flowchart of the adaptive calibration method of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is described in detail below through embodiments and in conjunction with the accompanying drawings.

[0040] Example 1

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

[0042] Power calibration: At high altitudes, engine performance is the primary concern of many car owners, so we first conduct engine power optimization at high altitudes. Based on the altitude simulation system, we simulate the intake and exhaust pressures of the engine at different altitudes. Based on the target power, we optimize the injection and intake volumes. The optimization process requires that the exhaust temperature does not exceed the maximum allowable exhaust temperature, and the supercharger speed does not exceed the maximum allowable speed. The details are as follows:

[0043]

[0044] Where:

[0045] Q F,h is the fuel supply at the target altitude h, kg / h; P e,0 is the plain power, kW; 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 (design thermal efficiency) of the engine; Q A,h is the air intake volume at target altitude h, kg / h; Q A,0 is the air intake volume in the plain, kg / h; Q F,0 is the fuel supply in the plain, kg / h; n Z is the supercharger speed at the target altitude h, r / min; V Z is the compressor capacity, L; ρ A is the air density, kg / m3; σ is the charging efficiency of the compressor; T 排，h is the exhaust temperature at the target altitude h, ℃; T 排,max is the maximum allowable exhaust temperature of the engine, °C; n Z,max The maximum permissible speed of the supercharger, r / min.

[0046] Fuel economy calibration: It mainly calibrates the engine's fuel consumption at high altitudes, involving the engine's in-cylinder combustion process. The complete combustion of fuel can improve the engine's fuel utilization rate, that is, the engine's fuel economy is increased.

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

[0048] Here, it is necessary to collect engine fuel economy data under different injection pressures and injection advance angles in advance to establish a mathematical model, and then use the mathematical model to perform high-altitude fuel economy calibration. Here, the least squares method is used for multivariate nonlinear fitting, and the fitting model is as follows:

[0049]

[0050] Where: Q FMIN,h is the minimum fuel supply at the target altitude h, kg / h; P e,h is the power at the target altitude h, kW; R is the injection advance angle, °CA; η R is the thermal efficiency at the injection advance angle R; a0, a1, a2 are fitting coefficients; BSFC MIN,h is the minimum specific fuel consumption at altitude h, g / kWh; BSFC 目标,h is the target specific fuel consumption at altitude h, g / kWh.

[0051] Emissions Calibration: Heavy-duty vehicles primarily experience excessive NOx and soot emissions in high-altitude environments. The trade-off between these two emissions is a key and challenging aspect of heavy-duty diesel engine calibration. NOx is rapidly generated in high-temperature, oxygen-rich environments, while soot is rapidly generated in oxygen-deficient environments. NOx is primarily related to the engine's injection advance angle and exhaust gas recirculation (EGR rate), while soot is primarily related to the injection advance angle and EGR rate. Therefore, it is necessary to develop relevant mathematical models before conducting high-altitude engine performance calibration.

[0052]

[0053] Where:

[0054] E NOx is the NOx emission concentration, ppm; E soot is the soot emission concentration, mg / m3; f EGR is the EGR rate of the engine; b0, b1, b2, b3, b4 are fitting coefficients; c0, c1, c2 are fitting coefficients; r is the air-fuel ratio; E NOx,h is the NOx emission concentration at the target altitude h, ppm; E soot,h is the soot emission concentration at the target altitude h, mg / m3; E NOx,0 is the NOx emission concentration in the plain, ppm; E soot,0 is the soot emission concentration in the plain, mg / m3; is the pollutant increase rate at the target altitude h; is the maximum permissible increase rate of pollutants.

[0055] Constructing an adaptive system for engine plateau performance calibration: First, collect the engine's plateau performance data, and fit the required mathematical formula based on the given mathematical model. Then, perform adaptive calibration of the relevant performance based on the plateau customer's demand for engine performance. The detailed process is as follows:

[0056] Power Module

[0057] Power reduction rate according to target altitude TMAX and nMAX are used to calculate the permissible injection quantity Q FMAX,h and intake air volume Q A,h :

[0058]

[0059] Fuel consumption and emissions module

[0060] According to the target altitude P e,h , BSFC 目标 , calculate the minimum injection quantity Q FMIN,h With the best ignition angle R:

[0061]

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

[0063]

[0064] In summary, the calibration parameter Q of the engine performance under plateau environment can be obtained FMIN,h , Q A,h , R, f EGR In addition, the system calculation logic can be upgraded as needed, such as adding setting loop calculation and infinite approximation principle, which can further optimize the 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 illustrated.

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

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

[0069] Pollutant emission model:

[0070] After that, the calibration test at a certain altitude can be carried out. First, the engine power attenuation rate at this altitude needs to be determined. Economic performance indicator BSFC 目标,h , emission degradation index Then, tests that require calibration (external characteristic tests, universal tests) are carried out under specific altitude conditions. After obtaining the test data, the data is imported into the prepared model to calibrate the power, fuel economy and emission characteristics in turn.

[0071] The first is the dynamic calibration: according to the engine design thermal efficiency η, target power attenuation rate Maximum permissible speed of the supercharger n Z,MAX , you can calculate the maximum fuel consumption Q of the engine FMAX,h , maximum air intake Q A,h .

[0072]

[0073] The fuel economy under the current maximum fuel consumption is not optimal, and fuel economy adjustment is required. The thermal efficiency model prepared in advance can calculate an injection advance angle R with the best thermal efficiency based on the test data, and the minimum fuel consumption Q can be obtained. FMIN,h , according to the model formula to obtain the best fuel economy index BSFC MIN,h .

[0074]

[0075] After solving the calibration of engine power and fuel economy, it is necessary to calibrate its pollutants. Diesel engine NOx and PM are the most difficult parts of calibration. It is necessary to balance the trade-off relationship between NOx and PM by adjusting the EGR rate. According to the pre-fitted pollutant emission model and the test data, the recommended EGR rate f can be calculated. EGR .

[0076]

[0077] Finally, according to the minimum fuel consumption Q given by the model FMIN,h , the optimal injection advance angle R, and the recommended EGR rate are verified by actual engine bench testing. The actual power Pe, actual fuel economy index BSFC, and pollutant emission degradation rate are calculated to ensure they meet the target altitude requirements. If the actual test results differ from the established targets, a secondary calibration can be performed.

Claims

1. A method for adaptively calibrating engine plateau performance, characterized in that: include: (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. (2) Dynamic calibration Based on the altitude simulation system, the intake and exhaust pressures of the engine at different altitudes are simulated. The fuel injection and intake volumes are optimized according to the target power. During the optimization process, the exhaust temperature must not exceed the maximum allowable exhaust temperature, and the turbocharger speed must not exceed the maximum allowable speed. (3) Fuel economy calibration Calibration of the engine's fuel consumption at plateaus involves the combustion process within the engine's cylinders. The complete combustion of fuel can improve the engine's fuel utilization, which means the engine's fuel economy is increased. The parameters involved are injection quantity and injection advance angle; Here, it is necessary to collect engine fuel economy data at different injection pressures and injection advance angles in advance to establish a mathematical model, and then use the mathematical model to perform high-altitude fuel economy calibration. Here, the least squares method is used for multivariate nonlinear fitting; (4) Emission calibration Among them, formula (1) and (2) are emission concentration models, formula (3) is the objective function, and formula (4) is the conditional function; where: E NOx is the NOx emission concentration; E soot is the soot emission concentration; f EGR is the EGR rate of the engine; b0, b1, b2, b3, b4, c0, c1, c2 are fitting coefficients; E NOx,h is the NOx emission concentration at the target altitude h; E soot,h is the soot emission concentration at the target altitude h; E NOx,0 is the NOx emission concentration in the plain; E soot,0 is the carbon soot emission concentration in the plain; is the pollutant increase rate at the target altitude h; is the maximum permissible increase rate of pollutants.

2. The method according to claim 1, characterized in that The dynamic calibration specifically includes: Among them, the joint formula (5) is the objective function, and the joint formula (6) is the conditional function; where: Q FMAX,h is the maximum fuel supply at target altitude h, P e,0 is the plain power, δ h is the power attenuation rate at the target altitude h; H U is the lower calorific value of the fuel, η is the effective thermal efficiency of the engine; Q A,h is the air intake volume at target altitude h, Q A,0 is the air intake volume of the plain, Q F,0 is the fuel supply in the plain, n Z is the supercharger speed at the target altitude h, V Z is the compressor capacity, ρ A is the air density, σ is the charging efficiency of the compressor; T 排，h is the exhaust temperature at the target altitude h, T 排,MAX is the maximum allowable exhaust temperature of the engine, n Z,MAX The maximum permissible speed of the supercharger.

3. The method according to claim 1, characterized in that The fuel economy calibration specifically includes: Among them, the combined formula (7) is the model of fuel supply, formula (8) is the objective function, and formula (9) is the conditional function; where: Q FMIN,h is the minimum fuel supply at the target altitude h, P e,h is the power at the target altitude h, R is the injection advance angle, η R is the thermal efficiency at the injection advance angle R; a0, a1, a2 are fitting coefficients; BSFC MIN,h is the minimum specific fuel consumption BSFC at altitude h 目标,h is the target specific fuel consumption at altitude h.

4. 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 engine plateau performance adaptive calibration method as described in any one of claims 1 to 3.

5. An engine plateau performance adaptive calibration system that implements the engine plateau performance adaptive calibration method according to any one of claims 1 to 3, characterized in that: include: Power module, power attenuation rate δ according to target altitude h 、T MAX With n MAX Calculate the permissible injection quantity Q FMAX,h and intake air volume Q A,h : Among them, the joint formula (10) is the objective function, and the joint formula (11) is the conditional function; the fuel consumption and emission module, according to the target altitude P e,h , BSFC 目标 , calculate the minimum injection quantity Q FMIN,h With the best ignition angle R: Among them, the joint formula (12) is the model of the injection amount, the formula (13) is the objective function, and the formula (14) is the conditional function; according to Mathematical model, calculate f EGR ;according to Mathematical model to calculate P: Among them, the combined formula (15) and (6) is the model of emission concentration, formula (17) is the objective function, and formula (18) is the conditional function; Get the calibration parameters of engine performance in plateau environment: Minimum injection quantity Q FMIN,h , intake volume Q A,h , the optimal ignition angle R and the engine's EGR rate f EGR .

6. The system according to claim 5, characterized in that It also includes setting up cyclic calculations and infinite approximation principles to further optimize engine performance.

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