CN111929067A - Virtual cylinder pressure detection method of engine - Google Patents
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Abstract
The invention discloses a virtual cylinder pressure detection method of an engine, which is used for realizing the real-time optimization control of the combustion process of a gasoline engine and comprises the following steps: calibrating a Weber function for combustion prediction by using average experimental data of the test working condition points; calculating by using a combustion model based on a Weber function to obtain a predicted cylinder pressure curve so as to obtain a predicted maximum explosion pressure phase; analyzing the collected actual crankshaft signals of the engine, and obtaining the maximum explosion pressure phase close to the reality based on the actual crankshaft angular speed information; and comparing the predicted maximum explosion pressure phase with the actually measured maximum explosion pressure phase, outputting a predicted cylinder pressure curve if the predicted maximum explosion pressure phase is consistent with the actually measured maximum explosion pressure phase, otherwise, adjusting the combustion phase in the Weber function, and performing iterative calculation to enable the predicted maximum explosion pressure phase to be consistent with the actual maximum explosion pressure phase and then outputting the phase. The invention is beneficial to the real-time optimization control of the combustion process of the engine, thereby achieving the purposes of saving oil and reducing emission.
Description
Technical Field
The invention relates to the technical field of engine combustion process control, in particular to an engine virtual cylinder pressure detection method based on combustion model prediction and used for combustion information feedback.
Background
The combustion feedback control technology is an important technical development direction for improving the performance of the engine in practical application. At present, electronic control systems are adopted in most internal combustion engines for vehicles. However, in the current electronic engine control system, the combustion control is performed by an open-loop control method based on a MAP. Furthermore, in MAP-based control, all control parameters for the same engine model are set to be the same, and only some of the parameters are corrected and adjusted according to certain sensor parameters when the engine is operating individually. The combustion process is used as the core of the working process of the engine, and because effective feedback information is lacked, an open-loop control mode is always adopted in the current control system. This is not sufficient for the individual engine to optimize the combustion process in real time according to the manufacturing variations and the changes in the operating conditions. At present, a research unit proposes to adopt a cylinder pressure sensor to acquire the real-time cylinder pressure of an engine as an information source for combustion closed loop feedback. The combustion closed-loop control is that a certain combustion state index obtained by cylinder pressure calculation is used as a feedback variable, and control parameters such as ignition, oil injection and the like are adjusted according to the difference value between an optimized value and the feedback variable, so that the feedback variable approaches the optimized value as much as possible, and the purpose of optimizing the combustion process is further achieved. The combustion state closed-loop control has great application potential in the aspects of reducing the oil consumption and emission of the engine, controlling the cylinder balance, increasing the fuel adaptability of the engine, reducing the calibration workload, diagnosing faults and the like.
Although the closed-loop combustion control is an important and effective method for improving the engine performance, it is limited to the practical problems of cost and reliability of the cylinder pressure sensor, and although a method of performing feedback control of the combustion state by the cylinder pressure sensor has been widely studied, it is mainly studied in a laboratory and cannot be widely applied to mass-produced vehicles. At present, the cost of a single cylinder pressure sensor, which is widely accepted by Kistler corporation, is approximately equal to the sum of the costs of 40 automotive control systems, and the additional costs incurred in using the sensor are not counted. In view of the great potential of combustion feedback control in terms of fuel economy, in recent years, various combustion feedback methods have been proposed in place of cylinder pressure information, such as feedback using a crankshaft rotational speed variation signal and feedback using a cylinder vibration signal. These alternative combustion feedback methods all attempt to utilize the existing engine sensors of the system and, therefore, do not result in a significant increase in cost. However, neither the crankshaft rotational speed variation information nor the engine body vibration information is a direct measurement of the combustion process, and only indirect combustion information can be provided. Therefore, although the variable information measured by both of them includes certain combustion information, the combustion information can be extracted only from the signal. The signals of the two are large in noise, theoretical correlation does not exist in information extraction, only experience is relied on, the signal-to-noise ratio is poor, the measured value is unreliable, and the method is difficult to adopt for actual closed-loop control.
Disclosure of Invention
The invention aims to overcome the problem of information feedback of engine combustion process control and provides a cylinder pressure virtual measurement method based on the combination of combustion model prediction and actual high-noise corner signal detection. The method is characterized in that an in-cylinder pressure curve predicted by a combustion model is used as a basis, key parameters are extracted through actually measuring crankshaft angular velocity change information, and the predicted pressure curve is calibrated, so that reconstruction of in-cylinder pressure is achieved, in-cylinder combustion information used for feedback control is further calculated, virtual sensing of combustion state information of an engine is achieved, and the problem of information sensing of combustion closed-loop feedback control is solved. The method is used for upgrading the existing engine based on prediction calibration control, simultaneously utilizes the known engine knowledge and theory, and realizes intelligent combustion sensing and feedback control by adopting real-time correction of 'correcting lines by points'.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a virtual cylinder pressure detection method of an engine is used for realizing the optimized control of the combustion process of a gasoline engine, and is characterized by comprising the following steps:
s1, measuring the average state of the steady-state combustion of the engine under different working conditions through experiments, and calibrating a Weber function for combustion prediction by using the obtained average data of the steady-state experiment of the engine;
s2, in practical application, according to ignition time, a prediction cylinder pressure curve is obtained through calculation by using a combustion model based on a Weber function, so that a predicted maximum explosion pressure phase is obtained, and a maximum explosion pressure searching range is determined;
s3, analyzing the collected actual crankshaft signals of the engine, and extracting actual most possible maximum explosion pressure phase information based on the change curve of the actual crankshaft angular speed;
s4, comparing the predicted maximum explosion pressure phase with the actual maximum explosion pressure phase, if the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase, predicting a cylinder pressure curve, and outputting the predicted cylinder pressure curve as a reconstructed cylinder pressure curve; otherwise, adjusting the combustion phase in the prediction model, performing iterative calculation, and outputting the reconstructed cylinder pressure curve after the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase.
And S5, calculating the maximum explosion pressure, the maximum explosion pressure phase, the maximum pressure rise rate phase, the in-cylinder temperature curve, the heat release rate curve, the combustion starting point CA10, the combustion phase CA50 and the combustion duration information required by the combustion feedback control based on the obtained reconstructed cylinder pressure curve, and providing the information for the combustion feedback control.
Specifically, a combustion information test is carried out on a test engine of a specific model through a bench calibration experiment, and information to be collected comprises rotation speed, air inlet pressure, circulating fuel injection quantity, ignition advance angle, CA50 and combustion heat release duration thetaduration. The working condition of the engine is determined by using the rotating speed and the air inlet pressure, and the engine combustion information obtained by testing under different working conditions is averaged to be used as the basis of the calibration of the prediction model. Establishing a functional relation between the combustion phase and the combustion duration along with the change of the working condition, the ignition angle and the fuel injection quantity so as to calibrate a combustion prediction model based on a Weber function, wherein the combustion prediction model can obtain a predicted cylinder pressure curve through the following formula:
MFBsi＝CE[1-exp(-WC×(θ-SOCsi)3)] (1)
SOCsi＝CA50-1.044×θduration (3)
wherein MFB is the burned mass fraction of fuel at crankshaft angle theta, theta is the crankshaft angle and SOC is the fuelSIFor the combustion start point of SIMeaning 1% crank angle, theta, of fuel combustiondurationIs a combustion duration, defined as the crank angle required for 1% to 99% of the fuel to be combusted,
is measured by experiments under different working conditions of CA50 and thetadurationThe gain factor of (2).
In the above formula, V (θ) is a cylinder volume at an arbitrary crank angle, D is a cylinder diameter (m), S is a stroke (m), λ is a link ratio, and λ is a compression ratio.
Based on the known fuel quantity and the current volume, the ideal gas state equation is passed
pV＝nRT (6)
Wherein p is the pressure of the ideal gas, V is the volume of the ideal gas, n represents the amount of the gas substance, T represents the thermodynamic temperature of the ideal gas, and R is the ideal gas constant; the temperature at each crank angle can be obtained, and the in-cylinder pressure at each angle can be obtained by superposing the influence of the fuel heat release amount, so that a cylinder pressure curve can be obtained.
The actual crankshaft signal of the engine is processed and calculated by information collected by a crankshaft sensor to obtain actual crankshaft angular speed information; specifically, the time interval between each tooth of the flywheel of the engine is acquired through the crankshaft sensor, and because the corresponding angle of every two teeth is a fixed crankshaft rotation angle, the real-time angular speed of the crankshaft can be obtained through further calculation. When the engine is burning, the engine angular velocity is made faster due to the increase in-cylinder pressure. The theoretically fastest angular velocity should be achieved when the in-cylinder pressure is at a maximum.
Specifically, the average combustion information of different operating points required by the calibration of the combustion prediction model includes: CA50, duration of Combustion exotherm θdurationIntake pressure and cyclic injection quantity.
In the present invention, a combustion model based on a Weber function is usedAnd (4) molding. The combustion process of the gasoline engine is researched from the energy perspective, the combustion chamber can be simplified into a control volume with equal pressure, the temperature calculation is simplified into the superposition of the temperature change of the adiabatic reversible compression and expansion process, the temperature change caused by heat transfer and the influence of fuel heat release, and the CA50 (crank angle data when the combustion heat release is accumulated to be 50%) and the combustion heat release duration theta are inputduration(crank angle for fuel combustion 10% -90%), intake pressure, and fuel injection amount, thereby obtaining a predicted cylinder pressure curve, and obtaining a predicted maximum explosion pressure phase search range.
The predicted maximum burst pressure phase is compared with the actual maximum burst pressure phase, and if the predicted maximum burst pressure phase and the actual maximum burst pressure phase are consistent, a cylinder pressure curve is predicted and output as a reconstructed cylinder pressure curve. Otherwise, adjusting the combustion phase in the prediction model, performing iterative calculation, and outputting the reconstructed cylinder pressure curve after the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase. The obtained reconstructed cylinder pressure curve can calculate information such as maximum explosion pressure, maximum explosion pressure phase, maximum pressure rise rate phase, in-cylinder temperature curve, heat release rate curve, combustion starting point CA10, combustion phase CA50 and combustion duration required by combustion feedback control, and provides the information for the combustion feedback control.
The invention utilizes the combustion model feedforward based on the Weber function to be combined with the combustion information obtained by the actual engine to carry out real-time check and adjustment on the prediction information of the combustion model, can obtain accurate combustion information, and saves a sensor element using a cylinder pressure sensor on the engine, thereby greatly saving the cost in the control of the actual combustion process of the engine.
Drawings
Fig. 1 is a flowchart of a virtual cylinder pressure detection method of the present invention.
FIG. 2 is a graph comparing cylinder pressure detection methods with raw cylinder pressure data. Wherein, the dot-dash line is a cylinder pressure curve predicted by the combustion model, the dotted line is a real-time cylinder pressure curve in the actual cycle, and the solid line is the predicted cylinder pressure curve calculated by the method.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in FIG. 1, the virtual cylinder pressure detection method of the engine of the present invention is used for realizing the combustion process control of a gasoline engine, and comprises the following steps:
s1, measuring the average state of the steady-state combustion of the engine under different working conditions through experiments, and calibrating a Weber function for combustion prediction by using the obtained average data of the steady-state experiment of the engine.
S2, in practical application, according to ignition time, a prediction cylinder pressure curve is obtained through calculation by using a combustion model based on a Weber function, so that a predicted maximum explosion pressure phase is obtained, and a maximum explosion pressure searching range is determined;
s3, analyzing the collected actual crankshaft signals of the engine, and extracting actual most possible maximum explosion pressure phase information based on the change curve of the actual crankshaft angular speed;
and S4, comparing the predicted maximum explosion pressure phase with the actual maximum explosion pressure phase, if the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase, predicting a cylinder pressure curve, and outputting the predicted cylinder pressure curve as a reconstructed cylinder pressure curve. Otherwise, adjusting the combustion phase in the prediction model, performing iterative calculation, and outputting the reconstructed cylinder pressure curve after the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase.
And S5, calculating information such as maximum explosion pressure, maximum explosion pressure phase, maximum pressure rise rate phase, in-cylinder temperature curve, heat release rate curve, combustion starting point CA10, combustion phase CA50 and combustion duration required by combustion feedback control based on the obtained reconstructed cylinder pressure curve, and providing the information for the combustion feedback control.
Specifically, a predicted cylinder pressure curve is obtained by inputting calibrated combustion information into a combustion model based on a weber function.
Specifically, the calibrated combustion information includes CA50, and the duration of combustion heat release θdurationThe boundary conditions include intake pressure and cycleAnd (4) circularly spraying oil quantity, and establishing a function of combustion information along with the change of boundary conditions.
The present invention will be described below by way of experiments conducted on a single cylinder engine of the Ricardo Hydra 140 type, in which the combustion model used in the present invention was used to predict the duration of combustion heat release θ using CA50durationEngine operating parameters such as intake pressure and cyclic fuel injection quantity are related to specific operating conditions of the engine.
CA50 and thetadurationIs calculated by
By the formula
MFB＝λ[1-exp(-WC×(θ-SOCsi)3)] (1)
SOCsi＝CA50-1.044×θduration (3)
Where MFB is the mass fraction of fuel burned at the crankshaft angle, WC is the crankshaft angle, SOCSIThe combustion start point of SI is defined as the crank angle of 1% of the fuel combustion, thetadurationDefined as the crank angle required for 10% to 90% of the fuel to burn, lambda is the combustion efficiency coefficient (typically ranging from 0.75 to 0.95),
is measured by experiments under different working conditions of CA50 and thetadurationDetermining CA50 and heat release duration for each operating condition, a prediction and simulation for the entire combustion process may be achieved.
Cylinder pressure calculation process during engine operation
On the basis, the whole cycle process of the engine is regarded as the superposition of the temperature change of the adiabatic reversible compression/expansion process, the temperature change caused by heat transfer and the influence of fuel heat release, the whole calculation process is divided into three sections, the first section is calculated from the opening moment of an intake valve to the combustion starting point, the second section is calculated from the combustion starting point to the combustion process ending, and the third section is calculated from the combustion process ending to the exhaust valve opening moment. The temperature T under the current crank angle is firstly obtained, and then the cylinder pressure P can be reversely obtained through an ideal gas state equation.
First, for the first stage expansion calculation, the cylinder volume V at any crank angle can be calculated as follows:
in the above formula, V (θ) is a cylinder volume at an arbitrary crank angle, D is a cylinder diameter (m), S is a stroke (m), λ is a link ratio, and λ is a compression ratio. Pi and Ti denote temperature and pressure per degree of crank angle. For the calculation of the first and third stage processes, since the initial temperature T is known0And pressure P0(using intake pressure instead), then the calculation process can be started and have:
wherein ViAnd Vi+1Respectively representing the volumes in the cylinder at the current crank angle moment and the next crank angle moment, wherein the adiabatic index k of the working medium is 1.4, TwallIs the cylinder inner wall temperature, s is the heat transfer area under the current crank angle, Δ t is the heat transfer time per degree of crank angle, CvThe constant volume specific heat capacity of the working medium, and M is the total mass of the working medium. Convective heat transfer coefficient hcThe formula is shown as the following formula, wherein K1And K2All are known coefficients, P is the current pressure (kPa), T is the current temperature (K), B is the cylinder diameter (m), and w is the average gas flow rate (m/s) in the cylinder.
Coefficient of convective heat transferhcThe calculation formula is shown as the following formula,
in the formula
Is the piston mean velocity (m/s), n is the engine speed, P is the pressure (kPa), T is the temperature (K), B is the bore diameter (m), and P and T are data recalling the last degree of crank angle.
The specific form of the temperature rise Δ T per crank angle degree in the second stage combustion process is calculated as follows:
ΔT＝Δt1+Δt2 (10)
wherein q islossIn terms of heat transfer loss, HlIs the lower heating value of gasoline, Delta mfuelM is the amount of fuel injectedGeneral assemblyTotal mass of all working substances trapped in the cylinder, CvIs the constant volume specific heat capacity of the total working medium.
The chemical reaction formula for complete combustion of fuel is:
namely, after 1mol of fuel is completely combusted by reaction with air, the increment delta n of the total molar number of the working substances is as follows:
the mole number of working media in the ith crankshaft angle interval is as follows:
ni＝nivc+nf0·Xbi·Δn (15)
in the formula: n isivcThe total mole of working media in the cylinder at the closing moment of an inlet valve is mole; n isf0Mole is the total mole of the fuel; xbiIs the accumulated burned mass percentage of fuel in the ith crank angle interval. Calculating to obtain N in the mass component of the waste gas generated after the reaction of the gasoline and the air2About 72% of CO219% of H2O accounts for 9 percent. Obtaining the constant volume specific heat capacity C of the three gas components by looking up a tablevkJ/(kg. K) are respectively represented by the following formulae:
Cv(N2)＝0.7304+0.00008955{t}℃ (16)
Cv(CO2)＝0.6837+0.0002406{t}℃ (17)
Cv(H2O)＝1.372+0.000311{t}℃ (18)
the constant volume specific heat capacity of the exhaust gas can be obtained according to the mass proportion coefficient as follows:
Cv(exhaust gas) ═ 0.7793+0.000138{ t }℃ (19)
The constant volume specific heat capacity of the air can also be obtained by the table lookup as follows:
Cv(air) 0.7088+0.000093{ t }℃ (20)
At the moment, the total constant volume specific heat capacity of the working medium is calculated as follows:
in summary, when the current crank angle temperature T is knowniIn the case of (1), the temperature T of the next crank angle can be obtained by the temperature rise DeltaTi+1Combined with the result of the variation of the mass in the cylinder, and thus through the ideal gasIn-cylinder pressure P for next degree of crank angle is obtained by state equationi+1. The calculation process is circulated until the MFB value is more than or equal to 0.99, the pressure and the temperature of the crank angle of the last degree are used as initial values and transmitted to the calculation of the expansion process of the third section, and the calculation method of the temperature and pressure course in the cylinder in the expansion process of the third section is consistent with that of the first section, so that the predicted cylinder pressure curve can be finally obtained.
Accuracy verification of combustion models
Setting a working condition point of 1000-3000r/min for the verification of a combustion model, selecting five-gear rotating speeds of 1000 rpm, 1500 rpm, 2000rpm, 2500 rpm and 3000rpm, respectively fixing the circulating fuel injection quantity to be 10, 14, 18, 22 and 26mg/cyc under each gear of rotating speed, and enabling the load range to cover the range from the average effective indicated pressure IMEP (equivalent instantaneous pressure) of 3bar to the IMEP of 9 bar; under each gear of circulating fuel injection quantity, the opening time of an intake valve is 330 degrees and 345 degrees CA crank angle, the closing time of an exhaust valve is EVC 370 degrees and 385 degrees CA crank angle, 4 groups of different intake and exhaust valve phases are formed to enrich the change situation of experimental working conditions, 4 points are arranged under each gear of rotating speed, the fuel-air equivalence ratio Lambda is changed by adjusting a throttle valve, the change range of Lambda is changed from 0.8 to 1 at intervals of 0.05, and the ignition angle is reasonably selected according to experience. The cylinder pressure data calculated by the combustion model is compared with the actual cylinder pressure data, and the error is not more than 5%.
Acquisition of crank shaft information
The engine crankshaft directly reflects the in-cylinder combustion condition in dynamics, and the invention acquires and analyzes the crankshaft information to obtain the actual combustion information such as the maximum explosion pressure phase and the like. The time information before each tooth of the flywheel is firstly acquired through a position sensor signal arranged on the engine flywheel, and the real-time angular speed of the crankshaft can be obtained through further calculation because the corresponding angle of every two teeth is a fixed crankshaft rotation angle. Through the angular velocity analysis, the combustion pressure peak phase of each combustion pressure peak value is found to have a crankshaft angular velocity extreme point corresponding to the crankshaft angular velocity extreme point in the actual combustion process of the engine. Through the information, the predicted cylinder pressure curve can be effectively subjected to feedback correction, so that an accurate transient cylinder pressure detection curve is obtained, and the purpose of real-time control over combustion is achieved.
Accurate virtual cylinder pressure detection method
On the basis of a Ricardo Hydra 140 single-cylinder engine, the cylinder pressure detection steps are as follows:
at a working condition point of 2000rpm, the oil injection amount per cycle is 16mg/cyc, the load is the average effective pressure IMEP of 3.3bar, the air inlet pressure is 0.54bar, CA50 at a certain working condition point is 10 degrees CA after the top dead center is compressed, the combustion duration is 23 degrees CA, a combustion model is input to obtain a predicted cylinder pressure curve, the obtained predicted maximum explosion pressure phase is 14 degrees CA after the top dead center is compressed, and the corresponding search range of the transient maximum explosion pressure phase is 11 degrees to 17 degrees CA after the top dead center is compressed; the method comprises the steps that through acquisition of crankshaft signals, searching and analyzing are carried out in the range, and the phase position of the transient maximum explosion pressure in actual operation is obtained and is 16 degrees CA of the compression top dead center; adjusting input combustion information by predicting the error between the pressure phase and the actual phase, firstly adjusting the value of CA50, keeping the adjustment amount consistent with the error amount, namely the error is 2 degrees, the adjustment amount is also 2 degrees, the direction is consistent with the error value, namely when the actual value is larger than the predicted value, increasing the input of CA 50; when the actual value is smaller than the predicted value, reducing the input of CA50, and increasing the predicted CA50 value by 2 degrees CA; and then adjusting the value of the combustion duration, wherein the value of the combustion duration is not a constant value, different gain coefficients need to be multiplied on the basis of the error value according to different working conditions, the value of the gain coefficient is determined by fitting CA50 and the combustion duration under different working conditions, the gain coefficient under the working conditions is 0.83, the adjusting value of the combustion duration is 1.66 ℃ A, and the predicted maximum explosion pressure phase is consistent with the actual phase through twice iterative adjustment, so that a more accurate curve of the transient cylinder pressure is obtained. Fig. 2 is a graph comparing the effects of actual adjustment.
The method is applied to the existing Ricardo Hydra 140 single-cylinder engine, and under the condition that the diluted combustion is not more than 80bar of pressure limit value and 8bar/CA of pressure rise rate limit, under the prediction method of the invention, the average effective pressure error between the calculated cylinder pressure and the transient cylinder pressure obtained by actual operation is not more than 10%.
The invention can obtain accurate enough combustion information by checking and adjusting the prediction information of the combustion model in real time, can realize feedback control of the combustion process, saves an expensive cylinder pressure sensor arranged on a common engine, greatly saves the cost of the combustion feedback control of the engine, thereby realizing a method for obtaining cylinder pressure data with low price and reliability, realizing more accurate combustion control of the actual engine, reducing the actual combustion phase overshooting due to the feedback control mode of the knock sensor and greatly improving the economy of the engine in actual operation.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A virtual cylinder pressure detection method of an engine is used for realizing the optimized control of the combustion process of a gasoline engine, and is characterized by comprising the following steps:
s1, measuring the average state of the steady-state combustion of the engine under different working conditions through experiments, and calibrating a Weber function for combustion prediction by using the obtained average data of the steady-state experiment of the engine;
s2, in practical application, according to the ignition time, a predicted cylinder pressure curve is calculated by using a combustion model based on a Weber function, so that a predicted maximum explosion pressure phase is obtained, and a maximum explosion pressure searching range is determined;
s3, analyzing the collected actual crankshaft signals of the engine, and extracting actual most possible maximum explosion pressure phase information based on the change curve of the actual crankshaft angular speed;
s4, comparing the predicted maximum explosion pressure phase with the actual maximum explosion pressure phase, if the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase, predicting a cylinder pressure curve, and directly outputting the predicted cylinder pressure curve as a reconstructed cylinder pressure curve; otherwise, adjusting the combustion phase in the prediction model, performing iterative calculation, and outputting a reconstructed cylinder pressure curve after the predicted maximum explosion pressure phase is consistent with the actual maximum explosion pressure phase;
and S5, calculating the maximum explosion pressure, the maximum explosion pressure phase, the maximum pressure rise rate phase, the in-cylinder temperature curve, the heat release rate curve, the combustion starting point CA10, the combustion phase CA50 and the combustion duration information required by the combustion feedback control based on the obtained reconstructed cylinder pressure curve, and providing the information for the combustion feedback control.
2. The virtual cylinder pressure detection method of an engine according to claim 1, characterized in that a predicted cylinder pressure curve is obtained by inputting a combustion model parameter calibrated in advance into a combustion prediction model based on a weber function.
3. The virtual cylinder pressure detection method of the engine according to claim 2, wherein the actual combustion information is extracted from the information on the change in the angular velocity of the crankshaft measured in real time, and the predicted cylinder pressure curve is checked and adjusted to obtain a cylinder pressure curve as close to the actual cylinder pressure as possible.
4. The virtual cylinder pressure detection method of the engine according to claim 3, wherein the combustion information provided is CA50, combustion heat release duration θ calculated from a cylinder pressure curvedurationAverage indicated pressure and combustion temperature.
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