Method for estimating air inlet density at closing moment of air inlet valve

Abstract

The invention discloses a method for estimating the air inlet density at the closing moment of an air inlet valve. The method comprises the steps that an input signal is determined; acquiring an input signal of the current sampling period; estimating the input signals of multiple sampling periods in the future, including estimating the density of fresh air entering the cylinder in the next sampling period based on the actual EGR rate of the current sampling period; a self-learning correction coefficient is determined, an intake manifold gas flow correction value, intake pressure and an actual EGR rate of the next sampling period are sequentially estimated according to the self-learning correction coefficient, and then the density of fresh air entering the air cylinder in the next sampling period is estimated, so that the density of fresh air entering the air cylinder in multiple sampling periods in the future is obtained; and the remaining time of closing of the air inlet valves of all the air cylinders is obtained, the air inlet density transient value at the closing moment of the air inlet valves of all the air cylinders is estimated, and finally the air inlet density final value when the air inlet valves of all the air cylinders are closed is determined. According to the invention, the intake air density entering the cylinder at the intake valve closing moment can be predicted and estimated before the intake valve is closed.

Description

Technical Field

[0001] The invention belongs to the technical field of engines, and in particular relates to a method for estimating intake air density at the moment when an intake valve is closed. Background Art

[0002] The engine intake system transfers atmospheric gas to the cylinder. The intake system is complex and tortuous, and the engine operating conditions change rapidly. The control of the injection amount is determined based on the intake amount entering the cylinder and the air-fuel ratio requirements. The intake amount entering the cylinder refers to the intake amount entering the cylinder when the intake valve is closed. However, it is too late to calculate the intake amount entering the cylinder when the intake valve is closed, because the engine will inject fuel during the intake stroke, and injection takes time, especially multi-injection control, that is, injection will be realized before the intake valve is closed, thereby improving emissions and combustion stability. Based on this, it is necessary to estimate the intake amount entering the cylinder at the moment of intake valve closing before the intake valve is closed.

[0003] Prior art CN202011247317.7 "Fresh air flow rate estimation method and system entering the cylinder" discloses a method for estimating the fresh air flow rate entering the cylinder, including the following steps: obtaining the fresh air flow rate entering the cylinder before fitting; judging whether the accuracy conditions of all fitting parameter estimates are met, and if so, calculating the fitting parameters; and calculating the estimated fresh air flow rate entering the cylinder based on the fitting parameters. This scheme calculates the current amount of fresh air entering the cylinder, but does not consider estimating the amount of fresh air entering the cylinder at the moment when the intake valve is closed.

[0004] Prior art CN202210687977.X "Correction method and engine system for engine intake" provides a correction method and engine system for engine intake, wherein the correction method includes the following steps: obtaining the conversion coefficient between the oil quantity and the excess air coefficient; and the feedforward correction value M obtained by the last correction calculation; based on the conversion coefficient; and the feedforward correction value M obtained by the last correction calculation, obtaining the excess air coefficient model value Lambda model; obtaining the measured value Lambda of the excess air coefficient, and based on the measured value Lambda of the excess air coefficient, the model value Lambda of the excess air coefficient and the conversion coefficient, obtaining the oil quantity correction value Δm; obtaining the injection amount m, and based on the oil quantity correction value Δm and the injection amount m, obtaining the feedforward correction value M, completing this correction calculation; based on the feedforward correction value obtained by each correction calculation, adjusting the engine's intake. This scheme calculates the amount of fresh air entering the cylinder to optimize, but it does not consider estimating the amount of fresh air entering the cylinder at the moment when the intake valve is closed.

[0005] Intake density is a form of expression of intake volume. Based on this, the present application proposes real-time estimation of the intake density of the cylinder at the moment of intake valve closing, so as to realize the setting of the injection volume, thereby ensuring timely and accurate control of the injection. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a method for estimating the intake density at the moment of closing of the intake valve, which is used to estimate the intake density entering the cylinder at the moment of closing of the intake valve.

[0007] To achieve the above object, according to a first aspect of the present invention, a method for estimating intake air density at the time of intake valve closing is provided, the method comprising:

[0008] Determine the input signal;

[0009] Get the input signal of the current sampling period;

[0010] Estimate the input signal for multiple sampling periods in the future, including:

[0011] Based on the actual EGR rate of the current sampling period, the density of fresh air entering the cylinder in the next sampling period is estimated;

[0012] Determine a self-learning correction coefficient, and estimate an intake manifold gas flow correction value of a next sampling period according to the self-learning correction coefficient;

[0013] Determine the intake pressure of the next sampling period according to the intake manifold gas flow correction value of the next sampling period;

[0014] According to the intake pressure of the next sampling period, the actual EGR rate of the next sampling period is determined, and then the density of fresh air entering the cylinder in the next sampling period is estimated, so as to obtain the density of fresh air entering the cylinder in multiple future sampling periods;

[0015] Get the remaining closing time of each cylinder intake valve;

[0016] According to the density of fresh air entering the cylinder in multiple future sampling periods and the remaining time for closing the intake valve of each cylinder, the transient value of the intake density at the moment when the intake valve of each cylinder is closed is estimated, and finally the final value of the intake density when the intake valve of each cylinder is closed is determined.

[0017] In the above scheme, the input signal includes:

[0018] 1) All input signals used to calculate the charging efficiency;

[0019] 2) Input signal for calculating intake manifold gas flow correction value;

[0020] 3) Atmospheric pressure;

[0021] 4) Throttle inlet gas pressure;

[0022] 5) Throttle inlet gas temperature;

[0023] 6) The rate of change of the throttle inlet gas pressure obtained based on the throttle inlet gas pressure;

[0024] 7) Actual effective area of ​​throttle;

[0025] 8) The rate of change of the actual effective area of ​​the throttle valve obtained based on the actual effective area of ​​the throttle valve;

[0026] 9) Actual throttle pressure ratio: The actual throttle pressure ratio is the ratio of the actual pressure of the gas at the throttle outlet to the actual pressure of the gas at the throttle inlet;

[0027] 10) A first characteristic parameter; The first characteristic parameter is determined by a gas constant and a throttle inlet gas temperature;

[0028] 11) Actual gas pressure at throttle outlet;

[0029] 12) The actual pressure change rate of the throttle outlet gas obtained according to the actual pressure of the throttle outlet gas;

[0030] 13) Actual exhaust gas mass flow rate at the EGR valve outlet;

[0031] 14) Actual EGR rate;

[0032] 15) Gas temperature at the cylinder inlet;

[0033] 16) Fresh air mass flow entering the cylinder;

[0034] 17) Density of the mixed gas entering the cylinder; The density of the mixed gas entering the cylinder is determined by the actual pressure of the gas at the throttle outlet, the gas temperature at the inlet of the cylinder intake valve, and the charging efficiency;

[0035] 18) Engine speed;

[0036] 19) Number of engine cylinders;

[0037] 20) Engine single cylinder volume;

[0038] 21) The mass flow rate of the mixture entering the cylinder; The mass flow rate of the mixture entering the cylinder is determined by the density of the mixture entering the cylinder.

[0039] In the above scheme, the calculation method of the throttle inlet gas pressure change rate is:

[0040]

[0041] In the formula, dp PreThrottleis the rate of change of gas pressure at the throttle inlet, dp PreThrottle (z) is the rate of change of the throttle inlet gas pressure in the previous sampling period; p PreThrottle is the throttle inlet gas pressure, p PreThrottle (z) is the throttle inlet gas pressure of the previous sampling period; Δt is the sampling period, t c1 is the throttle inlet gas pressure change rate filtering time constant;

[0042] The calculation method of the actual effective area change rate of the throttle is:

[0043]

[0044] In the formula, dA ThrottleAct is the actual effective area change rate of the throttle, dA ThrottleAct (z) is the actual effective area change rate of the throttle valve in the previous sampling period; A ThrottleAct is the actual effective area of ​​the throttle, A ThrottleAct (z) is the actual effective area of ​​the throttle valve in the previous sampling period; t c2 is the filtering time constant of the actual effective area change rate of the throttle valve;

[0045] The first characteristic parameter is Where R is the gas constant, T Thr is the throttle inlet gas temperature;

[0046] The calculation method of the actual pressure change rate of the throttle outlet gas is:

[0047]

[0048] In the formula, dp MAP is the actual pressure change rate of the throttle outlet gas, dp MAP (z) is the actual pressure change rate of the throttle outlet gas in the previous sampling cycle; p MAP is the actual pressure of the gas at the throttle outlet, p MAP (z) is the actual gas pressure at the throttle outlet of the previous sampling cycle; t c3 is the filtering time constant of the throttle outlet gas pressure change rate;

[0049] The density of the mixture entering the cylinder is calculated as:

[0050]

[0051] In the formula, rho GasCyl is the density of the mixture entering the cylinder, r VE is the charging efficiency, M is the molar mass of the mixed gas, T port is the gas temperature at the cylinder intake valve inlet port;

[0052] The mass flow rate of the mixed gas entering the cylinder is calculated as:

[0053]

[0054] In the formula, is the mass flow rate of the mixed gas entering the cylinder, n is the engine speed, V is the volume of a single cylinder of the engine, and CNT is the number of engine cylinders.

[0055] In the above scheme, obtaining the input signal of the current sampling period includes:

[0056] Determines the default values ​​for input signals, including:

[0057] 1) The default value of the intake pressure is the actual pressure of the throttle outlet gas read in real time;

[0058] 2) The default value of the intake manifold gas flow correction value is 0;

[0059] 3) The default value of the crankcase ventilation flow introduced into the cylinder through the intake manifold is 0;

[0060] 4) The default value of the crankcase ventilation PCV pipe pressure is the atmospheric pressure read in real time;

[0061] 5) The fresh air mass flow rate entering the cylinder is the mixed gas mass flow rate entering the cylinder read in real time;

[0062] 6) The default value of the fresh air density entering the cylinder is the real-time reading of the mixed gas density entering the cylinder;

[0063] 7) The default value of the mixed gas mass flow rate entering the cylinder is the mixed gas mass flow rate entering the cylinder read in real time;

[0064] 8) The default value of the density of the mixed gas entering the cylinder is the real-time reading of the density of the mixed gas entering the cylinder;

[0065] 9) The default value of inflation efficiency is 0;

[0066] 10) The default value of the actual effective area of ​​the throttle valve is the actual effective area of ​​the throttle valve read in real time;

[0067] 11) The default value of the gas mass flow rate flowing through the throttle valve is the real-time reading of the mixed gas mass flow rate entering the cylinder;

[0068] 12) Actual throttle pressure ratio The default value is 1; MAP is the actual pressure of the gas at the throttle outlet, p PreThrottle is the throttle inlet gas pressure;

[0069] 13) Throttle pressure ratio flow coefficient The default value is 1; the throttle pressure ratio flow coefficient is used to calculate the actual effective area of ​​the throttle and the actual intake flow;

[0070] 14) The default value of the throttle gas flow characteristic parameter is 1;

[0071] 15) The default value of the throttle inlet gas pressure is the real-time atmospheric pressure;

[0072] 16) The default value of the weighting coefficient is 1; the weighting coefficient is determined by the actual throttle outlet gas pressure and the throttle inlet gas pressure after the vehicle is powered on;

[0073] The default value is only executed once when the vehicle is powered on. The same input signal directly takes the value of the previous sampling cycle in the next sampling cycle;

[0074] And update the input signal.

[0075] In the above scheme, the calculation method of the throttle gas flow characteristic parameters is:

[0076]

[0077] In the formula, K ThrManDyn is the characteristic parameter of throttle gas flow, T Thr is the throttle inlet gas temperature.

[0078] In the above scheme, updating the input signal includes:

[0079] 1) Update the actual throttle pressure ratio according to the actual throttle outlet gas pressure and the throttle inlet gas pressure;

[0080] 2) Update the gas mass flow rate flowing through the throttle;

[0081] 3) updating the charging efficiency according to the real-time values ​​of all input signals used to calculate the charging efficiency;

[0082] 4) Update the density of the mixed gas entering the cylinder;

[0083] 5) Update the mass flow rate of the mixed gas according to the updated density of the mixed gas entering the cylinder;

[0084] 6) updating the weighting coefficient according to the actual pressure of the gas passing through the throttle outlet and the gas pressure of the throttle inlet obtained in real time; updating the intake manifold gas flow correction value according to the value of the intake manifold gas flow correction value in the previous sampling cycle;

[0085] 7) updating the intake pressure with the target intake pressure value obtained in real time;

[0086] 8) Update the throttle gas flow characteristic parameters; update the throttle actual pressure ratio; update the throttle pressure ratio flow coefficient according to the throttle actual pressure ratio; update the gas mass flow rate flowing through the throttle;

[0087] 9) updating the charging efficiency according to the real-time values ​​of all input signals used to calculate the charging efficiency;

[0088] 10) updating the density of the mixed gas entering the cylinder according to the real-time acquired gas temperature at the inlet port of the cylinder intake valve, the actual gas pressure at the throttle outlet, and the updated charging efficiency;

[0089] 11) updating the density of fresh air entering the cylinder according to the actual EGR rate obtained in real time and the updated density of the mixed gas entering the cylinder;

[0090] 12) updating the mass flow rate of the mixed gas according to the updated density of the mixed gas entering the cylinder;

[0091] 13) Update the fresh air mass flow entering the cylinder according to the updated mixed gas mass flow entering the cylinder and the actual EGR rate obtained in real time.

[0092] In the above scheme, updating the gas mass flow rate flowing through the throttle valve includes:

[0093]

[0094] In the formula, is the gas mass flow rate flowing through the throttle, p PreThrottle is the throttle inlet gas pressure, is the throttle pressure ratio flow coefficient, A ThrottleAct is the actual effective area of ​​the throttle, T Thr is the throttle inlet gas temperature;

[0095] Updating the fresh air density entering the cylinder includes:

[0096] rho AirCyl = rho GasCyl ×(1-r EGRAct )

[0097] In the formula, rho AirCyl is the density of fresh air entering the cylinder, rho GasCyl is the density of the mixture entering the cylinder, r EGRAct is the actual EGR rate;

[0098] Updating the fresh air mass flow entering the cylinder includes:

[0099]

[0100] In the formula, is the fresh air mass flow rate entering the cylinder, is the mass flow rate of the mixture entering the cylinder.

[0101] In the above scheme, the input signal of multiple future sampling periods is estimated, including:

[0102] Estimate the input signal of the next sampling period;

[0103] sequentially estimating input signals of subsequent sampling periods of the next sampling period;

[0104] The method for estimating the input signal of the next sampling period includes:

[0105] 1) Estimate the weighting coefficient and intake pressure change rate of the next sampling period based on the updated input signal of the current sampling period and the input signal acquired in real time of the current sampling period;

[0106] 2) based on the throttle inlet gas pressure and the throttle inlet gas pressure change rate of the current sampling period, the throttle inlet gas pressure of the next sampling period is estimated, and the estimated throttle inlet gas pressure is limited to a set range;

[0107] 3) According to the actual effective area of ​​the throttle valve and the rate of change of the actual effective area of ​​the throttle valve in the current sampling period, the actual effective area of ​​the throttle valve in the next sampling period is estimated, and the estimated actual effective area of ​​the throttle valve is limited to a set range;

[0108] 4) Estimate the intake manifold gas flow correction value of the next sampling period;

[0109] 5) Based on the estimated intake pressure change rate and the intake pressure obtained in the current sampling period, estimate the intake pressure of the next sampling period, and limit the estimated intake pressure within a set range;

[0110] 6) Estimate the throttle gas flow characteristic parameters, the actual throttle pressure ratio, the throttle pressure ratio flow coefficient, and the gas mass flow rate flowing through the throttle in the next sampling period;

[0111] 7) Estimate the charging efficiency of the next sampling period based on the updated intake pressure;

[0112] 8) Based on the estimated intake pressure, charging efficiency, and gas temperature at the intake port of the cylinder intake valve, estimate the density of the mixed gas entering the cylinder in the next sampling period;

[0113] 9) Based on the estimated density of the mixed gas entering the cylinder, estimate the mass flow rate of the mixed gas entering the cylinder in the next sampling period;

[0114] 10) Based on the estimated density of the mixed gas entering the cylinder and the actual EGR rate obtained in real time during the current sampling period, the density of the fresh air entering the cylinder during the next sampling period is estimated;

[0115] 11) Based on the estimated mass flow of the mixed gas entering the cylinder and the actual EGR rate obtained in real time during the current sampling period, estimate the mass flow of fresh air entering the cylinder during the next sampling period;

[0116] 12) Estimate the actual EGR rate of the next sampling period based on the actual EGR rate obtained in real time during this sampling period, the actual exhaust gas mass flow rate at the EGR valve outlet, the gas temperature at the cylinder intake valve inlet, and the estimated mixed gas mass flow rate entering the cylinder.

[0117] In the above scheme, the estimated intake manifold gas flow correction value of the next sampling period includes:

[0118] dm ManCorr-1 =[dm ManCorr +f(|dp Man-1 |)]×(1+r Adapt )

[0119] Where, dm ManCorr-1 is the intake manifold gas flow correction value of the next sampling cycle, dm ManCorr is the intake manifold gas flow correction value, r Adapt is the self-learning correction coefficient, f(|dp Man-1 |) is the estimated intake pressure change rate dp of the intake manifold in the next sampling period Man-1 The absolute value of function;

[0120] The estimated intake pressure for the next sampling period includes:

[0121] p MAP-1 =p MAP +dp Man-1 ×Δt

[0122] In the formula, p MAP-1 is the intake pressure in the next sampling period, p MAP is the intake pressure, dp Man-1 is the intake pressure change rate of the intake manifold in the next sampling period, and Δt is the sampling period;

[0123] The actual EGR rate estimated for the next sampling period includes:

[0124]

[0125] In the formula, r EGRAct-1 is the actual EGR rate of the next sampling period, r EGRActis the actual EGR rate, is the actual exhaust gas mass flow rate at the EGR valve outlet, is the mass flow rate of the mixed gas entering the cylinder in the next sampling cycle, V IntakeManifold is the intake manifold volume.

[0126] In the above scheme, the updating method of the self-learning correction coefficient is:

[0127] Calculate the average value of the intake manifold gas flow correction value of multiple future sampling cycles, subtract the average value from the intake manifold gas flow correction value of the current sampling cycle, and obtain the estimated intake manifold gas flow correction value difference dm ManCorr_Err ;

[0128] Calculate the evaluation parameter X:

[0129] X=X(z)+dm ManCorr_Err ×f(dm ManCorr_Err )×f(n,p Des )

[0130] Where X(z) is the evaluation parameter of the previous sampling period; f(dm ManCorr_Err ) is the estimated intake manifold gas flow correction value difference dm ManCorr_Err Function; f(n,p Des ) is the engine speed n and the throttle outlet target intake pressure p Des Determined coefficient; f(dm ManCorr_Err ) and f(n,p Des ) calibration acquisition;

[0131] The update conditions include:

[0132] 1) The throttle is not fully open;

[0133] 2) The actual pressure fluctuation range of the gas at the throttle outlet in real time is within the preset range;

[0134] 3) Engine speed fluctuation is within the preset range;

[0135] 4) The target intake pressure fluctuation at the throttle outlet is within the preset range;

[0136] 5)dm ManCorr_Err The fluctuation range is within the preset range;

[0137] 6) Transient operating coefficient r Trans is 0; if the throttle is in a stable condition, the transient condition coefficient r Trans is 0, otherwise the transient operating coefficient r Trans is 1;

[0138] If all the above conditions are met continuously for more than the first preset time, the self-learning correction coefficient r Adapt Allow update; first read the average engine speed, average throttle target pressure ratio, average atmospheric pressure and average value Update the self-learning correction coefficient r under the same working conditions of all parameters Adapt :

[0139]

[0140] In the formula, k1 is the weighting coefficient, r Adapt (z) is the self-learning correction coefficient of the previous sampling period.

[0141] In the above scheme, the instantaneous value of the intake density at the closing time of the intake valve of each cylinder is estimated according to the density of fresh air entering the cylinder in multiple future sampling periods and the remaining time of closing the intake valve of each cylinder, and the final value of the intake density when the intake valve of each cylinder is closed is finally determined, including:

[0142] Determine the closing time of the intake valve of each cylinder according to the remaining closing time of the intake valve of each cylinder;

[0143] If the closing time of the intake valve of a cylinder is between two adjacent sampling periods, the density of fresh air entering the cylinder corresponding to the two sampling periods is linearly interpolated to obtain the transient value of the intake density at the closing time of the intake valve of the cylinder;

[0144] The final value of the estimated intake density when the intake valve of each cylinder is closed is estimated based on the obtained transient operating condition coefficient, the density of the fresh air entering each cylinder in the current sampling period, and the transient value of the intake density when the intake valve of each cylinder is closed.

[0145] In the above scheme, the estimated final value of the intake density when the intake valve of each cylinder is closed includes:

[0146] rho AirCylFinal =r Trans ×rho AirCylTrans +(1-r Trans )×rho AirCyl

[0147] In the formula, rho AirCylFinal To estimate the final value of the intake air density, r Trans is the transient operating coefficient, rho AirCylTrans is the transient value of the intake density when the intake valve of each cylinder is closed, rho AirCyl It is the density of fresh air entering each cylinder in the current sampling period.

[0148] According to a second aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned methods for estimating the intake air density at the moment of intake valve closing are implemented.

[0149] According to a third aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of any one of the above-mentioned methods for estimating the intake air density at the moment of intake valve closing are implemented.

[0150] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0151] The intake system is complex and the engine operating conditions change quickly. By designing a model-based prediction algorithm that is constantly iterated and revised, the density of the intake air entering the cylinder at the moment of intake valve closing is estimated before the intake valve closes, so as to set the injection amount and ensure timely and accurate control of the injection. During the estimation process, the estimated intake manifold gas flow correction is updated in real time to improve the estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0152] Figure 1 A flow chart of a method for estimating intake air density at the time of intake valve closing provided by an embodiment of the present invention;

[0153] Figure 2 A flow chart of another method for estimating intake air density at the time of intake valve closing provided by an embodiment of the present invention;

[0154] Figure 3 A flow chart of a part of a method for estimating input signals of multiple future sampling periods provided by an embodiment of the present invention;

[0155] Figure 4 A schematic diagram of the structure of an air intake system provided by an embodiment of the present invention;

[0156] Figure 5 A schematic diagram of the structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0157] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0158] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0159] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0160] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0161] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0162] like Figure 1 and Figure 3 As shown, the embodiment of the present application discloses a method for estimating the intake density at the time of closing the intake valve, the method comprising:

[0163] S1. Determine the input signal;

[0164] S2, obtain the input signal of the current sampling period;

[0165] S3, estimating the input signal of multiple sampling periods in the future, including:

[0166] Based on the actual EGR rate of the current sampling period, the density of fresh air entering the cylinder in the next sampling period is estimated;

[0167] Determine a self-learning correction coefficient, and estimate an intake manifold gas flow correction value of a next sampling period according to the self-learning correction coefficient;

[0168] Determine the intake pressure of the next sampling period according to the intake manifold gas flow correction value of the next sampling period;

[0169] According to the intake pressure of the next sampling period, the actual EGR rate of the next sampling period is determined, and then the density of fresh air entering the cylinder in the next sampling period is estimated, so as to obtain the density of fresh air entering the cylinder in multiple future sampling periods;

[0170] S4, obtaining the remaining closing time of the intake valve of each cylinder;

[0171] S5. estimating the instantaneous value of the intake density at the closing time of the intake valve of each cylinder according to the density of the fresh air entering the cylinder in multiple future sampling periods and the remaining closing time of the intake valve of each cylinder;

[0172] S6. Finally determine the final value of the intake density when the intake valve of each cylinder is closed.

[0173] like Figure 2 As shown, this embodiment discloses a method for estimating the intake density at the moment of closing of the intake valve, that is, estimating the intake density entering the cylinder in a future period of time, and then reading the remaining time for closing the intake valve, so as to determine the intake density entering the cylinder corresponding to the moment of closing the intake valve, and its acquisition method is also a continuous iterative method. Figure 4 Configure the entire engine intake system.

[0174] The intake density estimation method is mainly divided into several steps. The first step is to determine the input signal required by the entire algorithm; the second step is to execute the observer under the current sampling period (the sampling period in this example is 10ms), and the observer outputs various signals under the current sampling period; the third step is to continuously output the predictor under multiple future sampling periods, and the predictor predicts various signals under multiple future sampling periods.

[0175] The first step is to determine the input signal required by the entire algorithm, that is, the general method of obtaining various signals:

[0176] 1) Used to calculate the inflation efficiency r VEAll input signals of the engine. For specific input signals, see patent CN201910204711.3 "A method and system for correcting charging efficiency" and Yi Yulan. Factors affecting engine charging efficiency and measures to improve it. "Industry and Technology Forum". 2011.

[0177] 2) Used to calculate the intake manifold gas flow correction value dm in patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium" ManCorr Input signal.

[0178] 3) Atmospheric pressure p Ambient , which can be detected by sensors.

[0179] 4) Throttle inlet gas pressure p PreThrottle , which can be detected by sensors.

[0180] 5) Throttle inlet gas temperature T Thr , which can be detected by sensors.

[0181] 6) Throttle inlet gas pressure change rate dp PreThrottle , is the throttle inlet gas pressure p PreThrottle In order to avoid the problem of drastic changes in the air pressure rate caused by large airflow fluctuations and overly aggressive calculations due to the hysteresis of the intake system, the calculation method for optimizing the change rate is as follows:

[0182]

[0183] In the formula, dp PreThrottle (z) is dp PreThrottle The value of the previous sampling period. The default value for the first sampling period is 0. PreThrottle (z) is the throttle inlet gas pressure of the previous sampling cycle. Its initial default value is the atmospheric pressure value read at that time. c1 is the throttle inlet gas pressure change rate filter time constant, which is 20ms in this example.

[0184] 7) Actual effective area of ​​throttle valve A ThrottleAct , which can be obtained based on the correspondence between the actual throttle opening and the effective throttle area measured by the sensor in patent CN202010109520.1 "Control system and method for electronic throttle of exhaust gas turbocharged engine".

[0185] 8) Throttle actual effective area change rate dA ThrottleAct , is the actual effective area of ​​the throttle valve A ThrottleActIn order to avoid the problem of drastic changes in the air pressure rate caused by large airflow fluctuations and overly aggressive calculations due to the hysteresis of the intake system, the calculation method for optimizing the change rate is as follows:

[0186]

[0187] In the formula, dA ThrottleAct (z) is dA ThrottleAct The value of the previous sampling period. The default value for the first sampling period is 0. ThrottleAct (z) is the actual effective area of ​​the throttle valve in the previous sampling period. Its initial default value is the maximum effective area of ​​the throttle valve. In this example, it is 2123.7 mm 2 , t c2 is the filtering time constant of the actual effective area change rate of the throttle valve, which is 20ms in this example.

[0188] 9) Actual throttle pressure ratio Actual throttle outlet gas pressure p MAP The actual gas pressure at the throttle inlet is PreThrottle Ratio

[0189] 10) Characteristic parameter 1 Where R is the gas constant, which is 287 J / (kg·K) in this example, T Thr is the actual temperature of the gas at the throttle inlet.

[0190] 11) Actual gas pressure at throttle outlet p MAP .

[0191] 12) Actual gas pressure at throttle outlet p MAP The rate of change of dp MAP In order to avoid the problem of drastic changes in the air pressure rate caused by large air flow fluctuations and overly aggressive calculations due to the hysteresis of the intake system, the calculation method for optimizing the change rate is as follows:

[0192]

[0193] In the formula, dp MAP (z) is dp MAP The value of the previous sampling period. The default value for the first sampling period is 0. MAP (z) is the actual gas pressure at the throttle outlet of the previous sampling cycle. Its initial default value is the atmospheric pressure value read at that time. c3 is the throttle outlet gas pressure change rate filter time constant, which is 20ms in this example.

[0194] 13) Actual exhaust gas mass flow at EGR valve outlet For details, please refer to the gas flow at the EGR valve in patent CN202210756041.8 "A method for controlling an EGR valve of a low-pressure EGR system"

[0195] 14) Actual EGR rate r EGRAct For details, see the EGR rate calculated in patent CN202310312052.1 "Control method, device, electronic device and storage medium of EGR rate of engine system".

[0196] 15) Gas temperature T at the cylinder inlet port For details, see the target air intake temperature T finally calculated in patent CN202010752089.2 "Engine air intake temperature control method and system".

[0197] 16) Fresh air mass flow into the cylinder For details, please refer to patent CN202011247317.7 "Fresh air flow estimation method and system for entering the cylinder" for estimating the fresh air flow entering the cylinder

[0198] 17) Density of the mixture entering the cylinder rho GasCyl , Where M is the molar mass of the mixed gas, which is 29 g / mol in this example, R is the ideal gas constant, which is 8.314 J / (mol·K) in this example, and r VE For the charging efficiency.

[0199] 18) Engine speed n.

[0200] 19) Number of engine cylinders CNT.

[0201] 20) Engine single cylinder volume V.

[0202] 21) Mass flow of mixed gas entering the cylinder

[0203] The second step is to execute the observer under the current sampling period (the sampling period in this example is 10ms), and the observer outputs various signals under the current sampling period.

[0204] (2.1) First, determine the input signal required to execute the current sampling cycle. The input signal is the default value when the vehicle is powered on and is only executed once. When calculating the next sampling cycle, the same input signal still directly uses the output signal calculated in the previous sampling cycle. The default value for the first time is set as follows:

[0205] 1) Intake pressure p MAPThe default value is the real-time actual intake pressure read, that is, the actual throttle outlet gas pressure p MAP ;

[0206] 2) Intake manifold gas flow correction value dm ManCorr The default value is 0;

[0207] 3) The flow rate of crankcase ventilation introduced into the cylinder through the intake manifold dm CC The default value is 0;

[0208] 4) Crankcase ventilation PCV pipe pressure p CC The default value is the current actual atmospheric pressure p Ambient ;

[0209] 5) Fresh air mass flow into the cylinder The default value is the actual mass flow rate of the mixed gas entering the cylinder. When the vehicle is powered on, the mixture is only fresh air;

[0210] 6) Density of fresh air entering the cylinder rho AirCyl The default value is the current actual density of the mixed gas entering the cylinder rho. GasCyl . When the vehicle is powered on, the mixture contains only fresh air;

[0211] 7) Mass flow of mixed gas entering the cylinder The default value is the actual mass flow rate of the mixed gas entering the cylinder.

[0212] 8) Density of the mixture entering the cylinder rho GasCyl The default value is the current actual density of the mixed gas entering the cylinder rho. GasCyl ;

[0213] 9) Inflating efficiency r VE The default value is 0;

[0214] 10) Actual effective area of ​​throttle valve A ThrottleAct The default value is the actual effective area A of the throttle valve actually read. ThrottleAct ;

[0215] 11) Gas mass flow through the throttle The default value is the actual mass flow rate of the mixed gas entering the cylinder.

[0216] 12) Actual throttle pressure ratio The default value is 1;

[0217] 13) Throttle pressure ratio flow coefficient The default value is 1. The parameters corresponding to the throttle target effective area and the throttle target intake flow can be seen in the patent CN202010109520.1 "Control system and method for exhaust gas turbocharged engine electronic throttle" Similarly, the actual effective area of ​​the throttle and the actual intake flow are calculated using

[0218] 14) Throttle gas flow characteristic parameter K ThrManDyn The default value is 1. Under normal circumstances, the throttle gas flow characteristic parameter K ThrManDyn Pick

[0219] 15) Throttle inlet gas pressure p PreThrottle The default value is the current actual atmospheric pressure p Ambient ;

[0220] 16) Coefficient r UseMAP The default value is 1. UseMAP The definition and the acquisition method under normal circumstances can be found in patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium".

[0221] (2.2) After determining all the above input signals, complete the following work:

[0222] 1) Update the actual throttle pressure ratio where p MAP According to the acquisition method of (2.1), p PreThrottle is the sensor value read in real time;

[0223] 2) Update the gas mass flow rate flowing through the throttle where p MAP According to the acquisition method of (2.1), p PreThrottle , A ThrottleAct , T PreThrottle Information read in real time. is p obtained according to the method of (2.1) MAP and the real-time read p PreThrottle Obtain, the acquisition method can be found in patent CN202210755703.X "An electronic throttle control method for a supercharged direct injection gasoline engine";

[0224] 3) Update the inflation efficiency r VE , calculate the charging efficiency r based on the real-time data signal VE ;

[0225] 4) Update the density of the mixture entering the cylinder rho GasCyl , where p MAP According to the acquisition method of (2.1), the inflation efficiency r VE is obtained in step 3), and the other signals in this formula are signals obtained in real time;

[0226] 5) Update the mass flow of the mixed gas entering the cylinder where rho GasCyl According to step 4), n is the engine speed obtained in real time;

[0227] 6) Based on the updated information above, update the coefficient r UseMAP , update the intake manifold gas flow correction value dm ManCorr . For the specific update method, please refer to patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium";

[0228] 7) Update the intake pressure p MAP , take the target intake pressure value p obtained in real time from patent CN202210344294.4 "Model optimization method, device, equipment and readable storage medium for intake pressure" s

[0229] 8) Update the throttle gas flow characteristic parameter K ThrManDyn , update the actual throttle pressure ratio Update throttle pressure ratio flow coefficient Update the gas mass flow through the throttle

[0230] 9) Update the inflation efficiency r VE , calculate the charging efficiency r based on the real-time data signal VE ;

[0231] 10) Update the density of the mixture entering the cylinder rho GasCyl , where p MAP According to the acquisition method of (2.1), the inflation efficiency r VE is obtained in step 9), and the other signals in this formula are signals obtained in real time;

[0232] 11) Update the fresh air density rho entering the cylinder AirCyl , rho AirCyl = rho GasCyl ×(1-r EGRAct ), where r EGRAct is the actual EGR rate of the current sampling period;

[0233] 12) Update the mass flow of the mixed gas entering the cylinder where rho GasCyl According to 10), n is the engine speed obtained in real time;

[0234] 13) Update the fresh air mass flow entering the cylinder

[0235] The third step is to estimate the observer in the next sampling period, and the observer outputs various signals in the next sampling period.

[0236] 1) Estimate the coefficient r for the next sampling period UseMAP-1 For the specific update method, please refer to patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium". The input signal required for its estimation method comes from the data updated in this sampling period and the data read in real time (the data read in real time includes the data not updated in this sampling period), and the same applies to the following.

[0237] 2) Estimate the intake pressure change rate dp of the intake manifold in the next sampling period Man-1 The specific update method can also be found in patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium". The input signal required for its estimation method comes from the data updated in this sampling period and the data read in real time (the data read in real time includes the data not updated in this sampling period). In this patent, the intake pressure change rate dp Man-1 The acquisition of the intake manifold gas flow correction value dm calculated in real time will be used ManCorr .

[0238] 3) Estimate the throttle inlet gas pressure p in the next sampling period PreThrottle-1 , p PreThrottle-1 The initial value is p PreThrottle +Δt×dp PreThrottle , and restrict it to p PreThrottle +Δp Max and p PreThrottle +Δp Min Internal (based on the range of the change characteristics of the throttle inlet gas pressure of the engine itself, and avoiding the phenomenon of the prediction observer not being able to converge to improve the prediction control accuracy, this example Δp Max and Δp Min Take 200kPa and -200kPa respectively), where p PreThrottle is the throttle inlet gas pressure in this sampling period (not the estimated next sampling period), Δt is the sampling period, 10ms in this example, dp PreThrottle It is the rate of change of the throttle inlet gas pressure during this sampling period.

[0239] 4) Estimate the actual effective area A of the throttle valve in the next sampling period ThrottleAct-1 .

[0240] Actual effective area A ThrottleAct-1 The initial value is A ThrottleAct +Δt×dA ThrottleAct , and restrict it to A ThrottleAct +ΔA Max and A ThrottleAct +ΔA Min Internal (based on the change range of the engine's own throttle effective area change characteristics, while avoiding the phenomenon of the prediction observer failing to converge to improve the prediction control accuracy, this example ΔA Max and ΔA Min Take 2000mm respectively 2 and -2000mm 2 ), where A ThrottleAct is the actual effective area of ​​the throttle valve in this sampling period (not the estimated next sampling period), Δt is the sampling period, 10ms in this example, dA ThrottleAct It is the actual effective area change rate of the throttle valve in this sampling period.

[0241] 5) Estimate the intake manifold gas flow correction value dm in the next sampling period ManCorr-1 :

[0242] dm ManCorr-1 =[dm ManCorr +f(|dp Man-1 |)]×(1+r Adapt ), where f(|dp Man-1 |) is the estimated intake pressure change rate dp of the intake manifold in the next sampling period Man-1 The absolute value of is shown in Table 1. Adapt It is a self-learning correction coefficient, which will be continuously updated and stored in time. Adapt This will be described in detail later.

[0243] Note that the intake manifold gas flow correction value dm in the current sampling period ManCorr And the estimated intake manifold gas flow correction value dm in the following sampling period ManCorr-N (N=1, 2, 3, ...) will be recorded in array form [dm ManCorr ,dm ManCorr-1 ,…dm ManCorr-N ], where dm ManCorr-Nis the intake manifold gas flow correction value in the next Nth sampling cycle. If N = 1, it refers to the intake manifold gas flow correction value in the next sampling cycle; if N = 2, it refers to the intake manifold gas flow correction value in the next sampling cycle; and so on. It can be seen that [dm ManCorr ,dm ManCorr-1 ,…dm ManCorr-N ] will be updated in each sampling cycle. Because of continuous sampling and updating, the data obtained in the future sampling cycles will continue to move to the left of the array. After moving to the first position on the left, it will be replaced by the next sampling cycle.

[0244] Table 1 f(|dp Man-1 |) Calibration table

[0245]

[0246] The above determination method, on the one hand, avoids that if the intake manifold gas flow correction value is updated greatly when the intake pressure changes greatly, the intake pressure change rate of the intake manifold will be further increased, thereby causing the control to fail to converge; on the other hand, only when the intake pressure changes slightly, the intake manifold gas flow correction value is adjusted to iteratively dynamically adjust and improve the control accuracy of the intake volume. Its calibration method ultimately ensures that the accuracy of the intake volume and the installed intake volume sensor is within ±2%.

[0247] 6) Estimate the intake pressure p in the next sampling period MAP-1 .

[0248] Intake pressure p MAP-1 The initial value is p MAP +dp Man-1 ×Δt, and limit it to p MAP +Δp MAPMax and p MAP +Δp MAPMin Internal (based on the change range of the engine's own throttle effective area change characteristics, while avoiding the phenomenon of the prediction observer failing to converge to improve the prediction control accuracy, this example Δp MAPMax and Δp MAPMin Take 200kPa and -200kPa respectively). Among them, p MAP The intake pressure obtained in this sampling cycle (not the estimated next sampling cycle).

[0249] 7) Estimate the throttle gas flow characteristic parameter K in the next sampling period ThrManDyn-1 , estimate the actual throttle pressure ratio in the next sampling period Estimate the throttle pressure-to-flow coefficient for the next sampling period Estimate the gas mass flow rate through the throttle valve in the next sampling period

[0250] 8) Estimate the inflation efficiency r in the next sampling period VE-1 The estimation method is to use the updated intake pressure p MAP-1 , other inputs are not updated.

[0251] 9) Estimate the density of the mixed gas entering the cylinder in the next sampling period rho GasCyl-1 ,

[0252] 10) Estimate the mass flow rate of the mixed gas entering the cylinder in the next sampling period where rho GasCyl According to step 4), n is the engine speed obtained in real time.

[0253] 11) Estimate the fresh air density rho entering the cylinder in the next sampling period AirCyl-1 , rho AirCyl-1 = rho GasCyl-1 ×(1-r EGRAct ), where r EGRAct It is the actual EGR rate of this sampling cycle (not the estimated next sampling cycle).

[0254] 12) Estimate the fresh air mass flow rate entering the cylinder in the next sampling period

[0255] 13) Estimate the actual EGR rate r in the next sampling period EGRAct-1 :

[0256] Where V IntakeManifold is the intake manifold volume, r EGRAct and They are respectively the actual EGR rate in this sampling period (not the estimated next sampling period) and the actual exhaust gas mass flow rate at the EGR valve outlet.

[0257] In the fourth step, the same method is used to estimate the observer in the subsequent sampling period, and the observer outputs various signals in the subsequent sampling period. The input determination method used to estimate various signals in the next sampling period is to determine the updated various input signals and real-time acquired signals based on the previous sampling period (wherein the real-time acquired signals refer to various signals that have not been updated in the previous sampling period). This example estimates various signals up to the seventh subsequent sampling period (wherein the estimated signal of the next sampling period introduced above refers to the estimated signal of the first subsequent sampling period). The more subsequent sampling periods are estimated, the greater the computing power, and at the same time, the accuracy of subsequent estimates becomes worse and worse. This example refers to the signals beyond the seventh subsequent sampling period being the same as the signals of the seventh sampling period.

[0258] Based on the above method, the fresh air density [rho AirCyl ,rho AirCyl-1 ...,rho AirCyl-N ]. The sampling period of 0 (unit: ms) refers to the current sampling period, the sampling period of 10 (unit: ms) refers to the next sampling period, and so on. AirCyl is the fresh air density entering the cylinder in the current sampling period, rho AirCyl-1 is the density of fresh air entering the cylinder in the next sampling period, and so on.

[0259] Next, determine the remaining closing time of the intake valve of each cylinder (i.e., the remaining closing time of the intake valve of cylinder No. 1 is t 1 , and so on). The engine body design will provide the relationship between the engine crankshaft phase and the cam phase when the VVT ​​is not in action. Then, when the VVT ​​is in action, based on the actual intake VVT ​​phase, the relationship between the engine crankshaft phase and the cam phase at the actual VVT phase can be obtained. The intake valve closing position and the cam phase are uniquely determined, so the relationship between the engine crankshaft phase and the intake valve closing position can be known. By reading the crankshaft phase, it can be known how many degrees the crankshaft needs to rotate if the intake valve is to be closed. Based on the current engine speed, the remaining time for the intake valve of each cylinder to be closed can be known.

[0260] Based on the determined remaining time [t 1 ,t 2 ,...,t CNT ], and the fresh air density [rho AirCyl ,rho AirCyl-1 ...,rho AirCyl-N ], linear interpolation is used to obtain the estimated transient value of intake density rho of each cylinderAirCylTrans (The linear interpolation method is that if the remaining time is between a certain sampling period and the adjacent sampling period, the estimated intake density corresponding to the two sampling periods is used to interpolate the transient value of the intake density at the time when the intake valve is closed. In particular, if the remaining time is greater than 10×N ms, then rho AirCyl-N as the transient value of the intake density at the moment of intake closing).

[0261] The density of fresh air entering the cylinder during the current sampling period is rho AirCyl and the estimated transient value of intake density rho for each cylinder AirCylTrans , and transient operating coefficient r Trans , we can determine the estimated final intake density rho when the intake valve of each cylinder is closed AirCylFinal :

[0262] rho AirCylFinal =r Trans ×rho AirCylTrans +(1-r Trans )×rho AirCyl

[0263] Transient operating coefficient r Trans The method to determine is:

[0264] The throttle mentioned in patent CN202210345939.6 "Throttle effective area calculation method, device, equipment and readable storage medium" is in a steady-state condition, which includes the throttle target intake density is stable, the ratio of throttle flow and effective area is stable, the actual intake pressure at the throttle outlet is stable, the actual intake pressure at the throttle inlet is stable and the throttle is not fully open. If the throttle is in a stable condition, the transient condition coefficient r Trans is 0, otherwise the transient operating coefficient r Trans Once the throttle is in a stable condition, the transient condition coefficient r Trans Set to 1; however, the transient operating coefficient r Trans The rate of change of reduction is not less than -0.2 / 10ms.

[0265] Based on this, the estimated final value of intake density rho when the intake valve of each cylinder is closed is determined AirCylFinal . It can be multiplied by the volume V of a single cylinder to get the intake volume of each cylinder, and the intake volume can be divided by the target air-fuel ratio to get the target injection volume of the intake cylinder. Based on the target injection volume, the injector is controlled to achieve the injection volume.

[0266] This section will introduce the self-learning correction coefficient r in detail. Adapt Method of obtaining .

[0267] First, calculate the self-learning correction coefficient r Adapt The evaluation parameter X. As mentioned above, it will be continuously updated [dm ManCorr ,dm ManCorr-1 ,…dm ManCorr-N ], and in this example N = 7, so we can know the intake manifold gas flow correction value dm in the current sampling period ManCorr If 7 estimates have been made before, then the average of the 7 estimates will be calculated and dm ManCorr Subtract the average value of 7 data to get the estimated intake manifold gas flow correction value difference dm ManCorr_Err .

[0268] Evaluation parameter X = X(z) + dm ManCorr_Err ×f(dm ManCorr_Err )×f(n,p Des )

[0269] In the formula, X(z) is the evaluation parameter calculated in the previous sampling period, and its initial moment is the moment when the vehicle is powered on, and the corresponding value at the initial moment is 0. Trans When it is not 0, clear X(z) to zero.

[0270] Among them, p Des It can be seen that the throttle outlet target intake pressure is mentioned in patent CN202010109520.1 "Control system and method for electronic throttle of exhaust gas turbocharged engine".

[0271] f(dm M an C orr_ E rr) is the estimated intake manifold gas flow correction value difference dm ManCorr_Err The function, f(dm M an C orr_ E rr) and f(n,p Des ) is determined by calibrating the vehicle after the engine is installed on the vehicle, calibrating at different engine speeds and different target intake pressures, and calibrating the estimated intake manifold gas flow correction value difference dm ManCorr_Err The accuracy of the air intake is to ensure that the accuracy of the engine air intake and the actual air intake (which can be achieved by installing an air intake sensor) is within ±2%. The calibration data of this example are shown in Table 2 and Table 3.

[0272] Table 2 f(dm ManCorr_Err ) Calibration table

[0273]

[0274] Table 3f(n,p Des) Calibration table

[0275]

[0276] Self-learning correction factor r Adapt The conditions for allowing updates are:

[0277] 1) The throttle is not fully open, that is, the throttle opening is less than 100% (the definition of throttle opening can be found in patent CN202010109520.1 "Control system and method for electronic throttle of exhaust gas turbocharger engine");

[0278] 2) The actual pressure fluctuation range of the throttle outlet gas detected by the sensor is within ±0.5kPa;

[0279] 3) The engine speed n fluctuation range is within ±15rpm;

[0280] 4) Throttle outlet target intake pressure p Des The fluctuation range is within ±2kPa;

[0281] 5)dm ManCorr_Err The fluctuation range is within ±0.05g / s;

[0282] 6) Transient operating coefficient r Trans is 0.

[0283] When all the above conditions are met continuously for more than the preset time t1 (1.2s in this example), the self-learning correction coefficient r Adapt Allow updates.

[0284] After entering the self-learning update, read the average engine speed within the preset time t2 (t2 in this example is 0.5s), the throttle target pressure ratio (throttle outlet target intake pressure p Des The average value of the throttle valve outlet gas pressure detected by the sensor, the average value of the atmospheric pressure and average value If the self-learning correction coefficient r appears within t2 during the self-learning update process Adapt If the conditions for allowing update are not met, the self-learning correction coefficient r will not be updated. Adapt .

[0285] Update self-learning correction coefficient r Adapt The self-learning correction coefficient r is updated under the corresponding working conditions (the engine speed, throttle target pressure ratio, atmospheric pressure and the average engine speed, throttle target pressure ratio and atmospheric pressure read at t2 are the same). Adapt :

[0286]

[0287] Where k1 is the weighting coefficient, which is 0.8 in this example.

[0288] Self-learning correction coefficient r under other working conditions Adapt Not updated.

[0289] Self-learning correction factor r Adapt After the update is completed, the dm under the corresponding working condition will be updated immediately ManCorr-1 ,…dm ManCorr-N , other working conditions are not updated.

[0290] The flow chart of the method for estimating the intake air density at the time of intake valve closing of the present application can be referred to Figure 1 and Figure 2 .

[0291] like Figure 5 The figure is a schematic diagram of the structure of a computer device provided by an embodiment of the present invention, such as a smart phone, tablet computer, laptop computer, desktop computer, rack server, blade server, tower server or cabinet server (including an independent server, or a server cluster composed of multiple servers) that can execute programs. The computer device 20 of this embodiment includes at least but is not limited to: a memory 21 and a processor 22 that can communicate with each other via a system bus, such as Figure 5 It should be pointed out that Figure 5 Only computer device 20 is shown with components 21 - 22 , but it should be understood that implementing all of the components shown is not a requirement, and more or fewer components may alternatively be implemented.

[0292] In this embodiment, the memory 21 (i.e., readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM). The memory 21 may also be an external storage device of the computer device 20, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the computer device 20. Of course, the memory 21 may also include both the internal storage unit of the computer device 20 and its external storage device. In this embodiment, the memory 21 is generally used to store the operating system and various application software installed on the computer device 20, such as the program code of the method for estimating the intake density at the time of closing the intake valve in the method embodiment. In addition, the memory 21 may also be used to temporarily store various data that have been output or are to be output.

[0293] The processor 22 may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chips in some embodiments. The processor 22 is generally used to control the overall operation of the computer device 20. In this embodiment, the processor 22 is used to run the program code stored in the memory 21 or process data, for example, to run a device storing a program code for a method for estimating the intake density at the time when the intake valve is closed, so as to implement the method for estimating the intake density at the time when the intake valve is closed in the method embodiment.

[0294] The present application also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, and the program realizes corresponding functions when executed by a processor. The computer-readable storage medium of this embodiment is used to store the program code of the method for estimating the intake density at the time when the intake valve is closed, and when executed by the processor, the method for estimating the intake density at the time when the intake valve is closed of the method embodiment is realized.

[0295] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0296] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0297] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0298] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0299] In summary, the present invention proposes a method for estimating the intake density at the time of intake valve closing. By designing a model-based prediction algorithm that is continuously iterated and continuously corrected, the intake amount entering the cylinder at the time of intake valve closing is predicted and estimated before the intake valve is closed, so as to realize the setting of the injection amount, thereby ensuring the control of injection in a timely and accurate manner. During the estimation process, the estimated intake manifold gas flow correction is updated in real time, thereby improving the estimation accuracy.

[0300] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0301] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0302] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating the intake air density at the time of intake valve closing, characterized in that: The method includes: Determine the input signal; Get the input signal of the current sampling period; Estimate the input signal for multiple sampling periods in the future, including: Based on the actual EGR rate of the current sampling period, the density of fresh air entering the cylinder in the next sampling period is estimated; Determine a self-learning correction coefficient, and estimate an intake manifold gas flow correction value of a next sampling period according to the self-learning correction coefficient; Determine the intake pressure of the next sampling period according to the intake manifold gas flow correction value of the next sampling period; According to the intake pressure of the next sampling period, the actual EGR rate of the next sampling period is determined, and then the density of fresh air entering the cylinder in the next sampling period is estimated, so as to obtain the density of fresh air entering the cylinder in multiple future sampling periods; Get the remaining closing time of each cylinder intake valve; According to the density of fresh air entering the cylinder in multiple future sampling periods and the remaining time for closing the intake valve of each cylinder, the transient value of the intake density at the moment when the intake valve of each cylinder is closed is estimated, and finally the final value of the intake density when the intake valve of each cylinder is closed is determined.

2. The method for estimating the intake air density at the intake valve closing time according to claim 1, characterized in that: Input signals include: 1) All input signals used to calculate the charging efficiency; 2) Input signal for calculating intake manifold gas flow correction value; 3) Atmospheric pressure; 4) Throttle inlet gas pressure; 5) Throttle inlet gas temperature; 6) The rate of change of the throttle inlet gas pressure obtained based on the throttle inlet gas pressure; 7) Actual effective area of ​​throttle; 8) The rate of change of the actual effective area of ​​the throttle valve obtained based on the actual effective area of ​​the throttle valve; 9) Actual throttle pressure ratio: The actual throttle pressure ratio is the ratio of the actual pressure of the gas at the throttle outlet to the actual pressure of the gas at the throttle inlet; 10) A first characteristic parameter; The first characteristic parameter is determined by a gas constant and a throttle inlet gas temperature; 11) Actual gas pressure at throttle outlet; 12) The actual pressure change rate of the throttle outlet gas obtained according to the actual pressure of the throttle outlet gas; 13) Actual exhaust gas mass flow rate at the EGR valve outlet; 14) Actual EGR rate; 15) Gas temperature at the cylinder inlet; 16) Fresh air mass flow entering the cylinder; 17) Density of the mixed gas entering the cylinder; The density of the mixed gas entering the cylinder is determined by the actual pressure of the gas at the throttle outlet, the gas temperature at the inlet of the cylinder intake valve, and the charging efficiency; 18) Engine speed; 19) Number of engine cylinders; 20) Engine single cylinder volume; 21) The mass flow rate of the mixture entering the cylinder; The mass flow rate of the mixture entering the cylinder is determined by the density of the mixture entering the cylinder.

3. The method for estimating the intake air density at the intake valve closing time according to claim 2, characterized in that: The calculation method of the throttle inlet gas pressure change rate is: In the formula, dp PreThrottle is the rate of change of gas pressure at the throttle inlet, dp PreThrottle (z) is the rate of change of the throttle inlet gas pressure in the previous sampling period; p PreThrottle is the throttle inlet gas pressure, p PreThrottle (z) is the throttle inlet gas pressure of the previous sampling period; Δt is the sampling period, t c1 is the throttle inlet gas pressure change rate filtering time constant; The calculation method of the actual effective area change rate of the throttle is: In the formula, dA ThrottleAct is the actual effective area change rate of the throttle, dA ThrottleAct (z) is the actual effective area change rate of the throttle valve in the previous sampling period; A ThrottleAct is the actual effective area of ​​the throttle, A ThrottleAct (z) is the actual effective area of ​​the throttle valve in the previous sampling period; t c2 is the filtering time constant of the actual effective area change rate of the throttle valve; The first characteristic parameter is Where R is the gas constant, T Thr is the throttle inlet gas temperature; The calculation method of the actual pressure change rate of the throttle outlet gas is: In the formula, dp MAP is the actual pressure change rate of the throttle outlet gas, dp MAP (z) is the actual pressure change rate of the throttle outlet gas in the previous sampling cycle; p MAP is the actual pressure of the gas at the throttle outlet, p MAP (z) is the actual pressure of the throttle outlet gas in the previous sampling cycle; t c3 is the filtering time constant of the throttle outlet gas pressure change rate; The density of the mixture entering the cylinder is calculated as: In the formula, rho GasCyl is the density of the mixture entering the cylinder, r VE is the charging efficiency, M is the molar mass of the mixed gas, T port is the gas temperature at the cylinder intake valve inlet port; The mass flow rate of the mixed gas entering the cylinder is calculated as: In the formula, is the mass flow rate of the mixed gas entering the cylinder, n is the engine speed, V is the volume of a single cylinder of the engine, and CNT is the number of engine cylinders.

4. The method for estimating the intake air density at the time of intake valve closing according to claim 2, characterized in that: Get the input signal of the current sampling period, including: Determines the default values ​​for input signals, including: 1) The default value of the intake pressure is the actual pressure of the throttle outlet gas read in real time; 2) The default value of the intake manifold gas flow correction value is 0; 3) The default value of the crankcase ventilation flow introduced into the cylinder through the intake manifold is 0; 4) The default value of the crankcase ventilation PCV pipe pressure is the atmospheric pressure read in real time; 5) The fresh air mass flow rate entering the cylinder is the mixed gas mass flow rate entering the cylinder read in real time; 6) The default value of the fresh air density entering the cylinder is the real-time reading of the mixed gas density entering the cylinder; 7) The default value of the mixed gas mass flow rate entering the cylinder is the mixed gas mass flow rate entering the cylinder read in real time; 8) The default value of the density of the mixed gas entering the cylinder is the real-time reading of the density of the mixed gas entering the cylinder; 9) The default value of inflation efficiency is 0; 10) The default value of the actual effective area of ​​the throttle valve is the actual effective area of ​​the throttle valve read in real time; 11) The default value of the gas mass flow rate flowing through the throttle valve is the real-time reading of the mixed gas mass flow rate entering the cylinder; 12) Actual throttle pressure ratio The default value is 1; MAP is the actual pressure of the gas at the throttle outlet, p PreThrottle is the throttle inlet gas pressure; 13) Throttle pressure ratio flow coefficient The default value is 1; the throttle pressure ratio flow coefficient is used to calculate the actual effective area of ​​the throttle and the actual intake flow; 14) The default value of the throttle gas flow characteristic parameter is 1; 15) The default value of the throttle inlet gas pressure is the real-time atmospheric pressure; 16) The default value of the weighting coefficient is 1; the weighting coefficient is determined by the actual throttle outlet gas pressure and the throttle inlet gas pressure after the vehicle is powered on; The default value is only executed once when the vehicle is powered on. The same input signal directly takes the value of the previous sampling cycle in the next sampling cycle; And update the input signal.

5. The method for estimating the intake air density at the intake valve closing time according to claim 4, characterized in that: The calculation method of the throttle gas flow characteristic parameters is: In the formula, K ThrManDyn is the characteristic parameter of throttle gas flow, T Thr is the throttle inlet gas temperature.

6. The method for estimating the intake air density at the time of intake valve closing according to claim 4, characterized in that: Update input signals, including: 1) Update the actual throttle pressure ratio according to the actual throttle outlet gas pressure and the throttle inlet gas pressure; 2) Update the gas mass flow rate flowing through the throttle; 3) updating the charging efficiency according to the real-time values ​​of all input signals used to calculate the charging efficiency; 4) Update the density of the mixed gas entering the cylinder; 5) Update the mass flow rate of the mixed gas according to the updated density of the mixed gas entering the cylinder; 6) updating the weighting coefficient according to the actual pressure of the gas passing through the throttle outlet and the gas pressure of the throttle inlet obtained in real time; updating the intake manifold gas flow correction value according to the value of the intake manifold gas flow correction value in the previous sampling cycle; 7) updating the intake pressure with the target intake pressure value obtained in real time; 8) Update the throttle gas flow characteristic parameters; update the throttle actual pressure ratio; update the throttle pressure ratio flow coefficient according to the throttle actual pressure ratio; update the gas mass flow rate flowing through the throttle; 9) updating the charging efficiency according to the real-time values ​​of all input signals used to calculate the charging efficiency; 10) updating the density of the mixed gas entering the cylinder according to the real-time acquired gas temperature at the inlet port of the cylinder intake valve, the actual gas pressure at the throttle outlet, and the updated charging efficiency; 11) updating the density of fresh air entering the cylinder according to the actual EGR rate obtained in real time and the updated density of the mixed gas entering the cylinder; 12) updating the mass flow rate of the mixed gas according to the updated density of the mixed gas entering the cylinder; 13) Update the fresh air mass flow entering the cylinder according to the updated mixed gas mass flow entering the cylinder and the actual EGR rate obtained in real time.

7. The method for estimating the intake air density at the intake valve closing time according to claim 6, characterized in that: Updating the mass flow of gas through the throttle valve includes: In the formula, is the gas mass flow rate flowing through the throttle, p PreThrottle is the throttle inlet gas pressure, is the throttle pressure ratio flow coefficient, A ThrottleAct is the actual effective area of ​​the throttle, T Thr is the throttle inlet gas temperature; Updating the fresh air density entering the cylinder includes: rho AirCyl =rho GasCyl ×(1-r EGRAct ) In the formula, rho AirCyl is the density of fresh air entering the cylinder, rho GasCyl is the density of the mixture entering the cylinder, r EGRAct is the actual EGR rate; Updating the fresh air mass flow entering the cylinder includes: In the formula, is the fresh air mass flow rate entering the cylinder, is the mass flow rate of the mixture entering the cylinder.

8. The method for estimating the intake air density at the intake valve closing time according to claim 1, characterized in that: Estimate the input signal for multiple sampling periods in the future, including: Estimate the input signal of the next sampling period; sequentially estimating input signals of subsequent sampling periods of the next sampling period; The method for estimating the input signal of the next sampling period includes: 1) Estimate the weighting coefficient and intake pressure change rate of the next sampling period based on the updated input signal of the current sampling period and the input signal acquired in real time of the current sampling period; 2) based on the throttle inlet gas pressure and the throttle inlet gas pressure change rate of the current sampling period, the throttle inlet gas pressure of the next sampling period is estimated, and the estimated throttle inlet gas pressure is limited to a set range; 3) According to the actual effective area of ​​the throttle valve and the rate of change of the actual effective area of ​​the throttle valve in the current sampling period, the actual effective area of ​​the throttle valve in the next sampling period is estimated, and the estimated actual effective area of ​​the throttle valve is limited to a set range; 4) Estimate the intake manifold gas flow correction value of the next sampling period; 5) Based on the estimated intake pressure change rate and the intake pressure obtained in the current sampling period, estimate the intake pressure of the next sampling period, and limit the estimated intake pressure within a set range; 6) Estimate the throttle gas flow characteristic parameters, the actual throttle pressure ratio, the throttle pressure ratio flow coefficient, and the gas mass flow rate flowing through the throttle in the next sampling period; 7) Estimate the charging efficiency of the next sampling period based on the updated intake pressure; 8) Based on the estimated intake pressure, charging efficiency, and gas temperature at the intake port of the cylinder intake valve, estimate the density of the mixed gas entering the cylinder in the next sampling period; 9) Based on the estimated density of the mixed gas entering the cylinder, estimate the mass flow rate of the mixed gas entering the cylinder in the next sampling period; 10) Based on the estimated density of the mixed gas entering the cylinder and the actual EGR rate obtained in real time during the current sampling period, the density of the fresh air entering the cylinder during the next sampling period is estimated; 11) Based on the estimated mass flow of the mixed gas entering the cylinder and the actual EGR rate obtained in real time during the current sampling period, estimate the mass flow of fresh air entering the cylinder during the next sampling period; 12) Estimate the actual EGR rate of the next sampling period based on the actual EGR rate obtained in real time during this sampling period, the actual exhaust gas mass flow rate at the EGR valve outlet, the gas temperature at the cylinder intake valve inlet, and the estimated mixed gas mass flow rate entering the cylinder.

9. The method for estimating the intake air density at the intake valve closing time according to claim 8, characterized in that: The estimated intake manifold gas flow correction value for the next sampling period includes: dm ManCorr-1 =[dm ManCorr +f(|dp Man-1 |)]×(1+r Adapt ) Where, dm ManCorr-1 is the intake manifold gas flow correction value of the next sampling period, dm ManCorr is the intake manifold gas flow correction value, r Adapt is the self-learning correction coefficient, f(|dp Man-1 |) is the estimated intake pressure change rate dp of the intake manifold in the next sampling period Man-1 The absolute value of function; The estimated intake pressure for the next sampling period includes: p MAP-1 =p MAP +dp Man-1 ×Δt In the formula, p MAP-1 is the intake pressure in the next sampling period, p MAP is the intake pressure, dp Man-1 is the intake pressure change rate of the intake manifold in the next sampling period, and Δt is the sampling period; The actual EGR rate estimated for the next sampling period includes: In the formula, r EGRAct-1 is the actual EGR rate of the next sampling period, r EGRAct is the actual EGR rate, is the actual exhaust gas mass flow rate at the EGR valve outlet, is the mass flow rate of the mixed gas entering the cylinder in the next sampling cycle, V IntakeManifold is the intake manifold volume.

10. The method for estimating the intake air density at the time of closing the intake valve according to claim 9, characterized in that: The updating method of the self-learning correction coefficient is: Calculate the average value of the intake manifold gas flow correction value of multiple future sampling cycles, subtract the average value from the intake manifold gas flow correction value of the current sampling cycle, and obtain the estimated intake manifold gas flow correction value difference dm ManCorr_Err ; Calculate the evaluation parameter X: X=X(z)+dm ManCorr_Err ×f(dm ManCorr_Err )×f(n,p Des ) Where X(z) is the evaluation parameter of the previous sampling period; f(dm ManCorr_Err ) is the estimated intake manifold gas flow correction value difference dm ManCorr_Err Function; f(n,p Des ) is the engine speed n and the throttle outlet target intake pressure p Des Determined coefficient; f(dm ManCorr_Err ) and f(n,p Des ) calibration acquisition; The update conditions include: 1) The throttle is not fully open; 2) The actual pressure fluctuation range of the gas at the throttle outlet in real time is within the preset range; 3) Engine speed fluctuation is within the preset range; 4) The target intake pressure fluctuation at the throttle outlet is within the preset range; 5)dm ManCorr_Err The fluctuation range is within the preset range; 6) Transient operating coefficient r Trans is 0; if the throttle is in a stable condition, the transient condition coefficient r Trans is 0, otherwise the transient operating coefficient r Trans is 1; If all the above conditions are met continuously for more than the first preset time, the self-learning correction coefficient r Adapt Allow update; first read the average engine speed, average throttle target pressure ratio, average atmospheric pressure and average value Update the self-learning correction coefficient r under the same working conditions of all parameters Adapt : In the formula, k1 is the weighting coefficient, r Adapt (z) is the self-learning correction coefficient of the previous sampling period.

11. The method for estimating the intake air density at the intake valve closing time according to claim 1, characterized in that: According to the density of fresh air entering the cylinder in multiple future sampling cycles and the remaining time for closing the intake valve of each cylinder, the transient value of the intake density at the time when the intake valve of each cylinder is closed is estimated, and the final value of the intake density when the intake valve of each cylinder is closed is finally determined, including: Determine the closing time of the intake valve of each cylinder according to the remaining closing time of the intake valve of each cylinder; If the closing time of the intake valve of a cylinder is between two adjacent sampling periods, the density of fresh air entering the cylinder corresponding to the two sampling periods is linearly interpolated to obtain the transient value of the intake density at the closing time of the intake valve of the cylinder; The final value of the estimated intake density when the intake valve of each cylinder is closed is estimated based on the obtained transient operating condition coefficient, the density of the fresh air entering each cylinder in the current sampling period, and the transient value of the intake density when the intake valve of each cylinder is closed.

12. The method for estimating the intake air density at the time of intake valve closing according to claim 11, characterized in that: The estimated final value of the intake density when the intake valve of each cylinder is closed includes: rho AirCylFinal =r Trans ×rho AirCylTrans +(1-r Trans )×rho AirCyl In the formula, rho AirCylFinal To estimate the final value of the intake air density, r Trans is the transient operating coefficient, rho AirCylTrans is the transient value of the intake density when the intake valve of each cylinder is closed, rho AirCyl It is the density of fresh air entering each cylinder in the current sampling period.

13. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method for estimating the intake air density at the closing moment of the intake valve as claimed in any one of claims 1 to 12 are implemented.

14. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method for estimating the intake air density at the closing moment of the intake valve as claimed in any one of claims 1 to 12 are implemented.

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