A method for estimating intake air density at intake valve closing

Abstract

The application discloses a method for estimating intake air density at the closing moment of an intake valve, comprising the following steps: determining an input signal; obtaining the input signal of a current sampling period; estimating the input signal of a plurality of future sampling periods, comprising the following steps: estimating the fresh air density entering a cylinder in a next sampling period based on the actual EGR rate of the current sampling period; determining a self-learning correction coefficient; estimating the intake manifold gas flow correction value, the intake pressure and the actual EGR rate of the next sampling period in sequence according to the self-learning correction coefficient; further estimating the fresh air density entering the cylinder in a sampling period after the next sampling period, so as to obtain the fresh air density entering the cylinder in the plurality of future sampling periods; obtaining the remaining time of the closing of the intake valve of each cylinder; estimating the intake air density transient value at the closing moment of the intake valve of each cylinder; and finally determining the final value of the intake air density at the closing moment of the intake valve of each cylinder. The application can predict and estimate the intake air density entering the cylinder at the closing moment of the intake valve before the closing of the intake valve.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engines, and particularly relates to a method for estimating intake air density at the closing time of an intake valve. BACKGROUND

[0002] An engine intake system transmits the gas of the atmosphere to the cylinder, the intake system is complex in bending, the engine operating condition changes in a moment, and the control of the fuel injection quantity is determined based on the intake air quantity into the cylinder and the air-fuel ratio requirement. The intake air quantity into the cylinder refers to the intake air quantity into the cylinder at the closing time of the intake valve, but if the intake air quantity into the cylinder is calculated at the closing time of the intake valve, it is too late, because the engine will inject fuel during the intake stroke, and the fuel injection needs time, especially for multi-injection control, that is, the fuel injection will be realized before the closing of the intake valve, so as to improve the emission and combustion stability. Therefore, it is necessary to estimate the intake air quantity into the cylinder at the closing time of the intake valve before the closing of the intake valve.

[0003] The prior art CN202011247317.7 “Fresh air flow into cylinder estimation method and system” discloses a fresh air flow into cylinder estimation method, comprising the following steps: obtaining the fresh air flow into the cylinder before fitting; judging whether all the fitting parameter estimation accuracy conditions are met, if yes, calculating the fitting parameter; and calculating the estimated fresh air flow into the cylinder according to the fitting parameter. The scheme calculates the current fresh air quantity into the cylinder, but does not consider the estimation of the fresh air quantity into the cylinder at the closing time of the intake valve.

[0004] The prior art CN202210687977.X “Engine intake quantity correction method and engine system” provides an engine intake quantity correction method and engine system, wherein the correction method comprises the following steps: obtaining a conversion coefficient between the fuel quantity and the excess air coefficient; and a last correction calculation obtained feedforward correction value M; based on the conversion coefficient; and the last correction calculation obtained feedforward correction value M, obtaining an excess air coefficient model value Lambda model; obtaining an excess air coefficient measured value Lambda, and based on the excess air coefficient measured value Lambda, the excess air coefficient model value Lambda and the conversion coefficient, obtaining a fuel quantity correction value Am; obtaining a fuel injection quantity m, and based on the fuel quantity correction value Am and the fuel injection quantity m, obtaining a feedforward correction value M, completing the current correction calculation; based on the feedforward correction value obtained by each correction calculation, adjusting the intake quantity of the engine. The scheme calculates the optimized fresh air quantity into the cylinder, but does not consider the estimation of the fresh air quantity into the cylinder at the closing time of the intake valve.

[0005] The intake air density is a form of the intake air amount, and based on this, the application estimates the intake air density of the intake cylinder at the intake valve closing time, so as to set the fuel injection amount and timely and accurately ensure the fuel injection control. SUMMARY

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

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

[0008] determining an input signal;

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

[0010] estimating the input signal of the future multiple sampling periods, comprising:

[0011] estimating the fresh air density of the intake cylinder in the next sampling period based on the actual EGR rate of the current sampling period;

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

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

[0014] determining the actual EGR rate of the next sampling period according to the intake pressure of the next sampling period, and further estimating the fresh air density of the intake cylinder in the next sampling period, so as to obtain the fresh air density of the intake cylinder in the future multiple sampling periods;

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

[0016] estimating the intake air density transient value at the intake valve closing time of each cylinder according to the fresh air density of the intake cylinder in the future multiple sampling periods and the remaining time of the intake valve closing of each cylinder, and finally determining the intake air density final value at the intake valve closing time of each cylinder.

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

[0018] 1) all input signals for calculating the charge efficiency;

[0019] 2) input signals for calculating the intake manifold gas flow correction value;

[0020] 3) atmospheric pressure;

[0021] 4) throttle inlet gas pressure;

[0022] 5) throttle inlet gas temperature;

[0023] 6) throttle inlet gas pressure change rate obtained according to the throttle inlet gas pressure;

[0024] 7) throttle actual effective area;

[0025] 8) throttle actual effective area change rate obtained according to the throttle actual effective area;

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

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

[0028] 11) throttle outlet gas actual pressure;

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

[0030] 13) EGR valve outlet actual exhaust gas mass flow;

[0031] 14) actual EGR rate;

[0032] 15) gas temperature of the cylinder intake port;

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

[0034] 17) mixture density entering the cylinder; the mixture density entering the cylinder is determined by the throttle outlet gas actual pressure, the gas temperature of the cylinder intake port, and the charge efficiency;

[0035] 18) engine speed;

[0036] 19) engine cylinder number;

[0037] 20) engine single cylinder volume;

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

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

[0040]

[0041] dp = (pout - pin) / pin PreThrottledp(z) is the throttle inlet gas pressure rate of change for the previous sampling period; p(z) is the throttle inlet gas pressure for the previous sampling period; t is the sampling period; and T is the filter time constant for the throttle inlet gas pressure rate of change. PreThrottle dp(z) is the throttle inlet gas pressure rate of change for the previous sampling period; p(z) is the throttle inlet gas pressure for the previous sampling period; t is the sampling period; and T is the filter time constant for the throttle inlet gas pressure rate of change. PreThrottle p(z) is the throttle inlet gas pressure for the previous sampling period; and T is the filter time constant for the throttle inlet gas pressure. PreThrottle p(z) is the throttle inlet gas pressure for the previous sampling period; and t is the sampling period. c1 T is the filter time constant for the throttle inlet gas pressure rate of change.

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

[0043]

[0044] dA(z) is the throttle actual effective area rate of change; dA(z) is the throttle actual effective area rate of change for the previous sampling period; A(z) is the throttle actual effective area for the previous sampling period; and t is the sampling period. ThrottleAct dA(z) is the throttle actual effective area rate of change; dA(z) is the throttle actual effective area rate of change for the previous sampling period; A(z) is the throttle actual effective area for the previous sampling period; and t is the sampling period. ThrottleAct dA(z) is the throttle actual effective area rate of change; dA(z) is the throttle actual effective area rate of change for the previous sampling period; A(z) is the throttle actual effective area for the previous sampling period; and t is the sampling period. ThrottleAct A(z) is the throttle actual effective area for the previous sampling period; and T is the filter time constant for the throttle actual effective area rate of change. ThrottleAct A(z) is the throttle actual effective area for the previous sampling period; and t is the sampling period. c2 T is the filter time constant for the throttle actual effective area rate of change.

[0045] The first characteristic parameter is where R is the gas constant, T is the throttle inlet gas temperature, and p is the throttle inlet gas pressure. Thr T is the throttle inlet gas temperature.

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

[0047]

[0048] dp(z) is the throttle outlet gas actual pressure rate of change; dp(z) is the throttle outlet gas actual pressure rate of change for the previous sampling period; p(z) is the throttle outlet gas actual pressure for the previous sampling period; and t is the sampling period. MAP dp(z) is the throttle outlet gas actual pressure rate of change; dp(z) is the throttle outlet gas actual pressure rate of change for the previous sampling period; p(z) is the throttle outlet gas actual pressure for the previous sampling period; and t is the sampling period. MAP dp(z) is the throttle outlet gas actual pressure rate of change; dp(z) is the throttle outlet gas actual pressure rate of change for the previous sampling period; p(z) is the throttle outlet gas actual pressure for the previous sampling period; and t is the sampling period. MAP p(z) is the throttle outlet gas actual pressure for the previous sampling period; and T is the filter time constant for the throttle outlet gas actual pressure rate of change. MAP p(z) is the throttle outlet gas actual pressure for the previous sampling period; and t is the sampling period. c3 T is the filter time constant for the throttle outlet gas pressure rate of change.

[0049] The method for calculating the intake gas density into the cylinder is:

[0050]

[0051] rho(z) is the intake gas density into the cylinder; rho(z) is the intake gas density into the cylinder for the previous sampling period; M is the molar mass of the intake gas; T is the gas temperature at the intake port of the cylinder intake valve; and t is the sampling period. GasCyl rho(z) is the intake gas density into the cylinder; rho(z) is the intake gas density into the cylinder for the previous sampling period; M is the molar mass of the intake gas; T is the gas temperature at the intake port of the cylinder intake valve; and t is the sampling period. VE M is the molar mass of the intake gas. port T is the gas temperature at the intake port of the cylinder intake valve.

[0052] The method for calculating the mass flow of the mixture entering the cylinder is:

[0053]

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

[0055] In the above scheme, the input signal of the current sampling period is acquired, including:

[0056] The default value of the input signal is determined, including:

[0057] 1) The default value of the intake pressure is the actual pressure of the gas at the throttle outlet 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 flow introduced into the cylinder via the intake manifold after the crankcase ventilation is 0;

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

[0061] 5) The mass flow of fresh air entering the cylinder is the mass flow of the mixture entering the cylinder read in real time;

[0062] 6) The default value of the fresh air density entering the cylinder is the density of the mixture entering the cylinder read in real time;

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

[0064] 8) The default value of the density of the mixture entering the cylinder is the density of the mixture entering the cylinder read in real time;

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

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

[0067] 11) The default value of the mass flow of the gas flowing through the throttle is the mass flow of the mixture entering the cylinder read in real time;

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

[0069] 13) the default value of the throttle pressure ratio flow coefficient 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 reading of the atmospheric pressure;

[0072] 16) the default value of the weighting coefficient is 1; the weighting coefficient is determined by the actual pressure of the gas outlet of the throttle 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, and the same input signal directly takes the value of the last sampling period in the next sampling period;

[0074] And update the input signal.

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

[0076]

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

[0078] In the above scheme, the input signal is updated, including:

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

[0080] 2) updating the mass flow of the gas flowing through the throttle;

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

[0082] 4) updating the density of the mixture entering the cylinder;

[0083] 5) updating the mass flow of the mixture according to the updated density of the mixture entering the cylinder;

[0084] 6) updating the weighting coefficient according to the actual pressure of the gas outlet of the throttle and the throttle inlet gas pressure 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 last sampling period;

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

[0086] ​8) updating the throttle gas flow characteristic parameter; updating the throttle actual pressure ratio; updating the throttle pressure ratio flow coefficient according to the throttle actual pressure ratio; updating the gas mass flow through the throttle;

[0087] 9) updating the charge efficiency according to the real-time values of all input signals for calculating the charge efficiency;

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

[0089] 11) updating the fresh air density into the cylinder according to the real-time acquired actual EGR rate and the updated intake mixture density into the cylinder;

[0090] 12) updating the mixture mass flow according to the updated intake mixture density into the cylinder;

[0091] 13) updating the fresh air mass flow into the cylinder according to the updated intake mixture mass flow into the cylinder, the real-time acquired actual EGR rate.

[0092] In the above scheme, the updating of the gas mass flow through the throttle comprises:

[0093]

[0094] wherein, is the gas mass flow through the throttle, p PreThrottle is the throttle inlet gas pressure, is the throttle pressure ratio flow coefficient, A ThrottleAct is the throttle actual effective area, T Thr is the throttle inlet gas temperature;

[0095] The updating of the fresh air density into the cylinder comprises:

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

[0097] wherein, rho AirCyl is the fresh air density into the cylinder, rho GasCyl is the intake mixture density into the cylinder, r EGRAct is the actual EGR rate;

[0098] The updating of the fresh air mass flow into the cylinder comprises:

[0099]

[0100] wherein, a fresh air mass flow into the cylinder, a mixture mass flow into the cylinder.

[0101] In the above scheme, the input signal of the next sampling period is estimated, including:

[0102] The input signal of the next sampling period is estimated.

[0103] The input signal of the subsequent sampling period of the next sampling period is estimated in turn.

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

[0105] 1) According to the updated input signal of the current sampling period and the real-time acquired input signal of the current sampling period, the weighting coefficient and the intake pressure change rate of the next sampling period are estimated.

[0106] 2) According to 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 within a set range.

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

[0108] 4) The intake manifold gas flow correction value of the next sampling period is estimated.

[0109] 5) According to the estimated intake pressure change rate and the intake pressure acquired in the current sampling period, the intake pressure of the next sampling period is estimated, and the estimated intake pressure is limited within a set range.

[0110] 6) The throttle gas flow characteristic parameter, the throttle actual pressure ratio, the throttle pressure ratio flow coefficient, and the gas mass flow through the throttle of the next sampling period are estimated.

[0111] 7) The charge efficiency of the next sampling period is estimated according to the updated intake pressure.

[0112] 8) The mixture density into the cylinder of the next sampling period is estimated according to the estimated intake pressure, the charge efficiency, and the gas temperature of the cylinder intake valve inlet.

[0113] 9) The mixture mass flow into the cylinder of the next sampling period is estimated according to the estimated mixture density into the cylinder.

[0114] 10) According to the estimated intake gas density into the cylinder and the actual EGR rate acquired in real time in the present sampling period, the fresh air density into the cylinder in the next sampling period is estimated;

[0115] 11) According to the estimated intake gas mass flow into the cylinder and the actual EGR rate acquired in real time in the present sampling period, the fresh air mass flow into the cylinder in the next sampling period is estimated;

[0116] 12) According to the actual EGR rate acquired in real time in the present sampling period, the actual exhaust gas mass flow at the EGR valve outlet, and the gas temperature at the intake port of the cylinder intake valve, the estimated intake gas mass flow into the cylinder, the actual EGR rate in the next sampling period is estimated.

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

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

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

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

[0121] p MAP-1 = p MAP + dp Man-1 x 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 manifold intake pressure change rate in the next sampling period, and Δt is the sampling period.

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

[0124]

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

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

[0127] calculate the average of the intake manifold gas flow correction values in the future multiple sampling periods, subtract the average from the intake manifold gas flow correction value in the current sampling period to 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] In the formula, X(z) is the evaluation parameter of the last sampling period; f(dm ManCorr_Err ) is a function of the estimated intake manifold gas flow correction value difference dm ManCorr_Err ; f(n, p Des ) is a coefficient determined by the engine speed n and the throttle valve outlet target intake air pressure p Des ; f(dm ManCorr_Err ) and f(n, p Des ) are obtained by calibration;

[0131] The updating conditions include:

[0132] 1) the throttle valve is not fully open;

[0133] 2) the real-time throttle valve outlet gas actual pressure fluctuation range is within a preset range;

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

[0135] 4) the throttle valve outlet target intake air pressure fluctuation is within a preset range;

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

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

[0138] All the above conditions are continuously met for more than a first preset time, then the self-learning correction coefficient r is updated Adapt Allow updating; first read the average value of engine speed, average value of throttle target pressure ratio, average value of atmospheric pressure and Average value Update the self-learning correction coefficient r in the same working condition of each parameter Adapt :

[0139]

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

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

[0142] According to the remaining time of each cylinder intake valve closing, the closing time of each cylinder intake valve is determined;

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

[0144] According to the obtained transient working condition coefficient, the fresh air density entering each cylinder in the current sampling period, and the intake air density transient value at the closing time of each cylinder intake valve, the estimated final value of the intake air density at the closing time of each cylinder intake valve is estimated.

[0145] In the above scheme, the estimated final value of the estimated intake air density at the closing time of each cylinder intake valve includes:

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

[0147] In the formula, rho AirCylFinal is the estimated final value of the intake air density, r Trans is the transient working condition coefficient, rho AirCylTrans is the intake air density transient value at the closing time of each cylinder intake valve, and rho AirCyl is the fresh air density entering each cylinder in the current sampling period.

[0148] According to a second aspect of the present application, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for estimating the intake air density at the intake valve closing time according to any one of the above aspects when executing the computer program.

[0149] According to a third aspect of the present application, a computer readable storage medium is provided, which stores a computer program, wherein the computer program is executable on a processor to implement the steps of the method for estimating the intake air density at the intake valve closing time according to any one of the above aspects.

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

[0151] The intake system is complex and the engine operating conditions change rapidly. By designing a model-based prediction algorithm that is constantly iterated and constantly corrected, the intake air density into the cylinder at the intake valve closing time is predicted and estimated before the intake valve closing, so as to realize the setting of the injection quantity, thereby timely and accurately ensuring the control of the injection. In the estimation process, the estimated intake manifold gas flow correction is updated in real time, thereby improving the estimation accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0152] Figure 1 A method flowchart for estimating the intake air density at the intake valve closing time is provided for the embodiments of the present application;

[0153] Figure 2 Another method flowchart for estimating the intake air density at the intake valve closing time is provided for the embodiments of the present application;

[0154] Figure 3 A partial method flowchart for estimating the input signal of the future multiple sampling periods is provided for the embodiments of the present application;

[0155] Figure 4 An intake system structure schematic diagram is provided for the embodiments of the present application;

[0156] Figure 5 A computer device structure schematic diagram is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0157] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict.

[0158] In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0159] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0160] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0161] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be 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, the first feature "above", "above" and "above" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0162] As shown in Figure 1 and Figure 3 The embodiment of the present application discloses a method for estimating the intake air density at the intake valve closing time, which comprises:

[0163] S1, determining an input signal;

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

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

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

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

[0168] According to the intake manifold gas flow correction value of the next sampling period, the intake pressure of the next sampling period is determined;

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

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

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

[0172] S6, finally determining the intake density final value at the closing time of each cylinder intake valve.

[0173] As Figure 2 shown, the embodiment discloses a method for estimating the intake density at the closing time of the intake valve, that is, estimating the intake density entering the cylinder in the future period of time, then reading the remaining time of the intake valve closing, so as to determine the corresponding intake density entering the cylinder at the closing time of the intake valve, and the obtaining method is also an iterative method. Figure 4 For the whole engine intake system configuration.

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

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

[0176] 1) for calculating the charge efficiency r VEAll input signals of the engine. Specific input signals can be seen in patent CN201910204711.3 "A correction method and system for charging efficiency" and Yiyulan. Factors affecting engine charging efficiency and improvement measures. Industry and Technology Forum. 2011.

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

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

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

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

[0181] 6) Throttle inlet gas pressure change rate dp PreThrottle , which is the change rate of throttle inlet gas pressure p PreThrottle To avoid the problem of rapid change of gas pressure change rate caused by large gas flow fluctuations and the hysteresis of the intake system, the calculation method of the change rate is optimized as follows:

[0182]

[0183] In the formula, dp PreThrottle (z) is the value of dp PreThrottle in the last sampling period, and its first default value is 0, p PreThrottle (z) is the throttle inlet gas pressure in the last sampling period, and its first default value is the atmospheric pressure value read at that time, t c1 is the throttle inlet gas pressure change rate filter time constant, which is 20ms in this example.

[0184] 7) Throttle actual effective area A ThrottleAct , which can be obtained according to the relationship between the throttle actual opening and the throttle effective area measured by the sensor in patent CN202010109520.1 "Control system and method of electronic throttle valve of exhaust turbocharged engine".

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

[0186]

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

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

[0189] 10) Feature Parameter 1 Where R is the gas constant, which is taken as 287 J / (kg·K) in this example, and T Thr This represents the actual temperature of the gas entering the throttle valve.

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

[0191] 12) Actual throttle outlet gas pressure p MAP rate of change dp MAP To avoid drastic changes in the rate of air pressure change due to large airflow fluctuations, and to prevent overly aggressive calculations due to the hysteresis of the intake system, the optimized calculation method for the rate of change is as follows:

[0192]

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

[0194] 13) Actual exhaust gas mass flow rate at the EGR valve outlet Specifically, see patent CN202210756041.8 "EGR valve control method of low-pressure EGR system" for gas flow at EGR valve

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

[0196] 15) Gas temperature T at the gas inlet of the cylinder port Specifically, see patent CN202010752089.2 "Engine air inlet temperature control method and system" for the final calculated target air inlet temperature T.

[0197] 16) Fresh air mass flow into the cylinder Specifically, see patent CN202011247317.7 "Fresh air flow into the cylinder estimation method and system" for the estimated fresh air flow into the cylinder

[0198] 17) Mixture density rho entering the cylinder GasCyl , Where M is the molar mass of the mixture, 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 is the volumetric efficiency.

[0199] 18) Engine speed n.

[0200] 19) Engine cylinder number CNT.

[0201] 20) Engine single cylinder volume V.

[0202] 21) Mixture mass flow into the cylinder

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

[0204] (2.1) First, determine the input signals needed to execute the current sampling period, which are the first default values when the vehicle is powered on, and only run once. When calculating the next sampling period, the same input signal is still directly used as the output signal calculated in the last sampling period. The first default value is set as follows:

[0205] 1) Intake pressure p MAPDefault value, the actual intake pressure read in real time, i.e. the actual pressure of the gas at the throttle outlet p MAP ;

[0206] 2) Intake manifold gas flow correction value dm ManCorr Default value, take 0;

[0207] 3) Flow dm of the crankcase ventilation via the intake manifold to the cylinder CC Default value, take 0;

[0208] 4) PCV pipe pressure p in the crankcase ventilation pipe CC Default value, take the current actual atmospheric pressure p Ambient ;

[0209] 5) Fresh air mass flow into the cylinder Default value, take the current actual read fresh air mass flow into the cylinder The mixture is only fresh air when the vehicle is powered on;

[0210] 6) Fresh air density rho into the cylinder AirCyl Default value, take the current actual read fresh air density rho into the cylinder GasCyl The mixture is only fresh air when the vehicle is powered on;

[0211] 7) Mixture mass flow into the cylinder Default value, take the current actual read mixture mass flow into the cylinder

[0212] 8) Mixture density rho into the cylinder GasCyl Default value, take the current actual read mixture density rho into the cylinder GasCyl ;

[0213] 9) Charge efficiency r VE Default value, take 0;

[0214] 10) Throttle actual effective area A ThrottleAct Default value, take the actual read throttle actual effective area A ThrottleAct ;

[0215] 11) Gas mass flow through the throttle Default value, take the current actual read mixture mass flow into the cylinder

[0216] 12) Throttle actual pressure ratio Default value, take 1;

[0217] 13) Throttle pressure ratio flow coefficient Default value, take 1. The patent CN202010109520.1 "Waste gas turbocharged engine electronic throttle valve control system and method" can be seen that the parameters corresponding to the throttle target effective area and the throttle target intake flow Similarly, when calculating the actual effective area of the throttle and the actual intake flow

[0218] 14) Throttle gas flow characteristic parameter K ThrManDyn Default value, take 1. Normally, the throttle gas flow characteristic parameter K ThrManDyn Take

[0219] 15) Throttle inlet gas pressure p PreThrottle Default value, take the current actual atmospheric pressure p Ambient ;

[0220] 16) Coefficient r UseMAP Default value, take 1. The definition of coefficient r UseMAP And the normal acquisition method can be seen in the patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium".

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

[0222] 1) Update the actual pressure ratio of the throttle Where p MAP Is obtained according to the acquisition method of (2.1), p PreThrottle Is the real-time reading sensor value;

[0223] 2) Update the mass flow of gas flowing through the throttle Where p MAP Is obtained according to the acquisition method of (2.1), p PreThrottle , A ThrottleAct , T PreThrottle Are real-time read information. Is obtained according to the acquisition method of (2.1) p MAP And the real-time reading p PreThrottle , Its acquisition method can be seen in the patent CN202210755703.X "Electronic throttle control method of supercharged direct injection gasoline engine";

[0224] 3) Update the charge efficiency r VE , Based on real-time data signals to calculate the charge efficiency r VE ;

[0225] 4) Update the mixture density rho GasCyl , where p MAP Obtained according to the acquisition method (2.1), the charge efficiency r VE Obtained in the third), and other signals in the formula are real-time acquisition signals.

[0226] 5) Update the mass flow of the mixture entering the cylinder where rho GasCyl Obtained according to the fourth), and n is the real-time engine speed.

[0227] 6) Update the coefficient r UseMAP according to the above updated information, update the intake manifold gas flow correction value dm ManCorr . For specific updating methods, see patent CN202210301971.4 “Gas flow calculation method, device, and readable storage medium”;

[0228] 7) Update the intake pressure p MAP , and take the target intake pressure value p s

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

[0230] 9) Update the charge efficiency r VE , and calculate the charge efficiency r VE based on real-time data signals;

[0231] 10) Update the density rho GasCyl of the mixture entering the cylinder where p MAP is obtained according to the acquisition method (2.1), and the charge efficiency r VE is obtained in the ninth), and other signals in the formula are real-time acquisition signals.

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

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

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

[0235] Third step, estimate the observer in the next sampling period, the observer output in the next sampling period of each type of signal.

[0236] 1) Estimate the coefficient r in the next sampling period UseMAP-1 The specific updating method is seen in patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium". The input signals required for its estimation method are derived from the updated data in this sampling period and the real-time read data (real-time read data includes data that has not been updated in this sampling period), and the following is the same.

[0237] 2) Estimate the intake manifold intake pressure rate dp in the next sampling period Man-1 The specific updating method is also seen in patent CN202210301971.4 "Gas flow calculation method, device and readable storage medium". The input signals required for its estimation method are derived from the updated data in this sampling period and the real-time read data (real-time read data includes data that has not been updated in this sampling period). In this patent, the intake pressure rate dp Man-1 is obtained using the real-time calculated intake manifold gas flow correction value dm ManCorr .

[0238] 3) Estimate the throttle inlet gas pressure p in the next sampling period PreThrottle-1 The initial value of p PreThrottle-1 is p PreThrottle +Δt×dp PreThrottle , and it is limited to p PreThrottle +Δp Max and p PreThrottle +Δp Min (based on the change range of the engine throttle inlet gas pressure change characteristic, while avoiding the phenomenon that the prediction observer cannot converge to improve the prediction control accuracy, in this example Δp Max and Δp Min are 200kPa and -200kPa respectively), where p PreThrottle is the throttle inlet gas pressure in this sampling period (not the next sampling period), Δt is the sampling period, in this example 10ms, dp PreThrottle is the throttle inlet gas pressure rate in 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 x dA ThrottleAct , and it is limited within A ThrottleAct + ΔA Max and A ThrottleAct + ΔA Min (Designed based on the range of changes in the effective area of the throttle valve of the engine itself, while avoiding the phenomenon that the prediction observer cannot converge to improve the prediction control accuracy, in this example, ΔA Max and ΔA Min are 2000mm 2 and -2000mm 2 , respectively), where A ThrottleAct is the actual effective area of the throttle valve in the current sampling period (not the next sampling period), Δt is the sampling period, which is 10ms in this example, and dA ThrottleAct is the change rate of the actual effective area of the throttle valve in the current sampling period.

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

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

[0243] Note that the intake manifold gas flow correction value dm ManCorr in the current sampling period and the intake manifold gas flow correction value dm ManCorr-N in the subsequent sampling period (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 sampling period; if N=2, it is the intake manifold gas flow correction value in the second next sampling period; and so on. It can be seen that the array [dm ManCorr ,dm ManCorr-1 ,…dm ManCorr-N ] will be updated in each sampling period, because the data obtained in the future sampling period is constantly updated and moves to the left of the array, and after moving to the leftmost first position, the next sampling period is replaced.

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

[0245]

[0246] The above determination method, on the one hand, avoids the situation 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 perform iterative dynamic adjustment, thereby improving the control precision of the intake amount. The calibration method finally ensures that the precision of the intake amount and the installed intake amount sensor after comparison is within ±2%.

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

[0248] The initial value of the intake pressure p MAP-1 is p MAP + dp Man-1 × Δt, and is limited to be within p MAP + Δp MAPMax and p MAP + Δp MAPMin (based on the change range of the effective area change characteristics of the engine throttle, and to avoid the phenomenon that the prediction observer fails to converge to improve the prediction control precision, in the present example, Δp MAPMax and Δp MAPMin are 200 kPa and -200 kPa, respectively). Among them, p MAP is the intake pressure obtained in the present sampling period (not the next sampling period to be estimated).

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

[0250] 8) Estimate the charge efficiency r in the next sampling period VE-1 , other inputs are not updated. MAP-1

[0251] 9) Estimate the intake charge density rho in the next sampling period GasCyl-1

[0252] 10) Estimate the intake charge mass flow rate in the next sampling period where rho GasCyl is obtained from 4), n is the real-time engine speed.

[0253] 11) Estimate the fresh air density rho in the next sampling period AirCyl-1 , rho AirCyl-1 = rho GasCyl-1 x (1-r EGRAct ), where r EGRAct is the actual EGR rate in the current sampling period (not the next sampling period to be estimated).

[0254] 12) Estimate the fresh air mass flow rate 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 are the actual EGR rate and the actual exhaust mass flow rate at the EGR valve outlet in the current sampling period (not the next sampling period to be estimated).

[0257] ​​​Fourth step, the same method is used to estimate the observer in the next sampling period, the observer output in the next sampling period of each type of signal. The input determination method used to estimate the next sampling period of each type of signal is to determine the updated input signal of each type according to the last sampling period and the real-time acquired signal (where the real-time acquired signal refers to the signal of each type that is not updated in the last sampling period). This example is estimated until the next seventh sampling period of each type of signal (where the signal of the next sampling period introduced in the previous step refers to the signal of the first subsequent sampling period). The more subsequent sampling periods are estimated, the greater the computing power is increased, and the accuracy of the subsequent estimation is also getting worse. The signals beyond the seventh subsequent sampling period in this example are 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 ] entering the cylinder corresponding to different sampling periods [0, 10,..., 10xN] can be obtained. Where the sampling period is 0 (unit ms) refers to the current sampling period, the sampling period is 10 (unit ms) refers to the next sampling period, and so on. rho AirCyl is the fresh air density entering the cylinder in the current sampling period, rho AirCyl-1 is the fresh air density entering the cylinder in the next sampling period, and so on.

[0259] Next, determine the remaining time of each cylinder intake valve closing (i.e. the remaining time of the first cylinder number intake valve closing is t1, 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, so based on the actual phase of the intake VVT, 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, and 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 of each cylinder intake valve closing can be known.

[0260] Based on the determined remaining time [t1, t2,..., t CNT ] and the fresh air density [rho AirCyl , rho AirCyl-1 ,..., rho AirCyl-N ] entering the cylinder corresponding to different sampling periods [0, 10,..., 10xN], the estimated intake density transient value rho AirCylTransThe method of linear interpolation is that if the remaining time is between a certain sampling period and an adjacent sampling period, the intake air density at the intake valve closing time is interpolated using the estimated intake air density corresponding to the two sampling periods, in particular, if the remaining time is greater than 10xN ms, rho AirCyl-N is the estimated intake air density transient value at the intake valve closing time.

[0261] The fresh air density rho AirCyl into the cylinder in the current sampling period AirCylTrans , and the transient working condition coefficient r Trans , the estimated intake air density final value rho AirCylFinal at the intake valve closing time of each cylinder can be determined.

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

[0263] The determination method of the transient working condition coefficient r Trans is as follows:

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

[0265] Based on this, the estimated intake air density final value rho AirCylFinal at the intake valve closing time of each cylinder is determined. It can be multiplied by the volume V of a single cylinder to obtain the intake air amount of each cylinder, and the target oil injection amount of the intake air cylinder can be obtained by dividing the intake air amount by the target air-fuel ratio. Based on the target oil injection amount, the oil injector is controlled to be injected to achieve the oil injection amount.

[0266] This part will introduce in detail the acquisition method of the self-learning correction coefficient r Adapt .

[0267] First, calculate the self-learning correction coefficient r. Adapt The evaluation parameter X. This has been introduced previously and will be continuously updated [dm]. ManCorr ,dm ManCorr-1 ,…dm ManCorr-N In this example, N=7, therefore the intake manifold gas flow correction value dm under the current sampling period can be determined. ManCorr Since seven estimates have already been made, the average of the seven estimates will be calculated, and dm will be... ManCorr Subtracting the seven data points and averaging them yields the difference in the estimated intake manifold gas flow correction value, 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 time is the time when the vehicle is powered on, with an initial value of 0. The transient operating condition coefficient r... Trans If it is not 0, clear X(z) to zero.

[0270] Where, p Des The target intake pressure at the throttle outlet is mentioned in patent CN202010109520.1, "Control System and Method for Electronic Throttle Valve of Exhaust Gas Turbocharged Engine".

[0271] f(dm M an C orr_ E rr) represents the difference in dm between the estimated intake manifold gas flow rate correction value and the actual flow rate. ManCorr_Err The function, f(dm) M an C orr_ E rr) and f(n,p Des The method for determining the intake manifold gas flow correction value (dm) involves vehicle calibration after the engine is installed. Calibration is performed at different engine speeds and target intake pressures to determine the difference. ManCorr_Err The accuracy of the intake air volume is ensured to be within ±2% of the actual intake air volume (which can be achieved by installing an intake air volume sensor). The calibration data for this example are shown in Tables 2 and 3.

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

[0273]

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

[0275]

[0276] self-learning correction coefficient r Adapt The condition for allowing updating is:

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

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

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

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

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

[0282] 6) The transient condition coefficient r Trans is 0.

[0283] After all the above conditions are continuously met for more than a preset time t1 (1.2s in this example), the self-learning correction coefficient r Adapt is allowed to be updated.

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

[0285] The method for updating the self-learning correction coefficient r Adapt updates the self-learning correction coefficient r Adapt under the corresponding working condition (the engine speed, the throttle target pressure ratio, the atmospheric pressure are the same as the average values of the engine speed, the throttle target pressure ratio, and the atmospheric pressure read in the previous t2).

[0286]

[0287] wherein k1 is a weighting coefficient, and in this example, 0.8.

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

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

[0290] The flowchart of the method for estimating the intake air density at the intake valve closing time according to the present application can refer to Figure 1 and Figure 2 .

[0291] As Figure 5 shown is a structural schematic diagram of a computer device provided by an embodiment of the present application, such as a smartphone, a tablet computer, a notebook computer, a desktop computer, a rack-mounted server, a blade server, a tower server, or a cabinet server (including a standalone server or a server cluster composed of multiple servers), etc. The computer device 20 of the present embodiment at least includes but is not limited to a memory 21 and a processor 22 that can be communicatively connected through a system bus, as shown in Figure 5 It should be noted that Figure 5 only the computer device 20 with components 21-22 is shown, but it should be understood that it is not required to implement all the shown components, and more or fewer components can be alternatively implemented.

[0292] In the present embodiment, the memory 21 (i.e., a readable storage medium) includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an 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) The memory 21 can also be an external storage device of the computer device 20, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device 20. Of course, the memory 21 can also include both an internal storage unit and an external storage device of the computer device 20. In the present embodiment, the memory 21 is generally used to store an operating system and various application software installed on the computer device 20, such as program codes of the method for estimating the intake air density at the intake valve closing time in the method embodiment, etc. In addition, the memory 21 can also be used to temporarily store various data that have been output or will be output.

[0293] The processor 22 may, in some embodiments, be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor 22 is generally operable to control overall operation of the computer device 20. In the present embodiment, the processor 22 is arranged to run program code stored in the memory 21 or to process data, for example to run program code stored in the memory 21 for a method of estimating the intake air density at the intake valve closing time to implement the method of estimating the intake air density at the intake valve closing time 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 memory (for example, an 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 magnetic disk, an optical disk, a server, an App application store, and the like, having stored thereon a computer program, which, when executed by a processor, implements the corresponding function. The computer readable storage medium of the present embodiment is used to store program code of the method of estimating the intake air density at the intake valve closing time, which, when executed by the processor, implements the method of estimating the intake air density at the intake valve closing time in the method embodiment.

[0295] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) having computer-usable program code contained therein.

[0296] The present application is described with reference to the flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as a combination of flows and / or blocks in the flowcharts and / or block diagrams, 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 apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 The means for implementing one or more functions specified in a flow or a plurality of flows and / or blocks Figure 1 The means for implementing one or more functions specified in a flow or a plurality of flows and / or blocks

[0297] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the flow Figure 1 one or more flowcharts and / or blocks Figure 1 one or more flowcharts and / or blocks

[0298] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flow Figure 1 one or more flowcharts and / or blocks Figure 1 one or more flowcharts and / or blocks

[0299] In summary, the present application proposes a method for estimating the intake air density at the intake valve closing time, by designing a constantly iterative and constantly corrected model-based prediction algorithm to predict the intake air amount into the cylinder at the intake valve closing time before the intake valve closing, for realizing the setting of the fuel injection amount, so as to timely and accurately ensure the control of the fuel injection. In the estimation process, the real-time updating of the estimated intake manifold gas flow correction is performed, and the estimation accuracy is improved.

[0300] It should be noted that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0301] It should be noted that according to the needs of implementation, each step / component described in the present application can be split into more steps / components, or two or more steps / components or part of the operation of the steps / components can be combined into a new step / component, to achieve the purpose of the present application.

[0302] Those skilled in the art will readily understand that the above are only preferred embodiments of the present application, and are not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for estimating an intake air density at an intake valve closing timing, characterized by, The method comprises: determining an input signal; obtaining the input signal of a current sampling period; estimating the input signal of a plurality of future sampling periods, comprising: estimating the fresh air density entering the cylinder in the next sampling period based on the actual EGR rate of the current sampling period; determining a self-learning correction coefficient, and estimating the intake manifold gas flow correction value of the next sampling period according to the self-learning correction coefficient; determining the intake pressure of the next sampling period according to the intake manifold gas flow correction value of the next sampling period; determining the actual EGR rate of the next sampling period according to the intake pressure of the next sampling period, and further estimating the fresh air density entering the cylinder in the next sampling period, thereby obtaining the fresh air density entering the cylinder in the plurality of future sampling periods; obtaining the remaining time of the closing of the intake valve of each cylinder; estimating the intake density transient value at the closing time of the intake valve of each cylinder according to the fresh air density entering the cylinder in the plurality of future sampling periods and the remaining time of the closing of the intake valve of each cylinder, and finally determining the final value of the intake density at the closing time of the intake valve of each cylinder; wherein estimating the intake density transient value at the closing time of the intake valve of each cylinder according to the fresh air density entering the cylinder in the plurality of future sampling periods and the remaining time of the closing of the intake valve of each cylinder, and finally determining the final value of the intake density at the closing time of the intake valve of each cylinder, comprises: determining the time of the closing of the intake valve of each cylinder according to the remaining time of the closing of the intake valve of each cylinder; if the closing time of the intake valve of a certain cylinder is located between two adjacent sampling periods, then the fresh air densities entering the cylinder corresponding to the two sampling periods are linearly interpolated to obtain the intake density transient value at the closing time of the intake valve of the certain cylinder; estimating the final estimated intake density value at the closing time of the intake valve of each cylinder according to the obtained transient operating condition coefficient, the fresh air density entering each cylinder in the current sampling period, and the intake density transient value at the closing time of the intake valve of each cylinder.

2. The method for estimating the intake air density at the intake valve closing timing according to claim 1, characterized by, The input signal comprises: 1) all input signals for calculating the charge efficiency; 2) input signals for calculating the intake manifold gas flow correction value; 3) atmospheric pressure; 4) throttle inlet gas pressure; 5) throttle inlet gas temperature; 6) throttle inlet gas pressure change rate obtained according to the throttle inlet gas pressure; 7) actual effective area of the throttle; 8) actual effective area change rate of the throttle obtained according to the actual effective area of the throttle; 9) actual pressure ratio of the throttle; the actual pressure ratio of the throttle is the ratio of the actual pressure of the throttle outlet gas to the actual pressure of the throttle inlet gas; 10) first characteristic parameter; the first characteristic parameter is determined by the gas constant and the throttle inlet gas temperature; 11) actual pressure of the throttle outlet gas; 12) 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 outlet of the EGR valve; 14) actual EGR rate; 15) gas temperature at the cylinder intake port; 16) fresh air mass flow rate entering the cylinder; 17) the density of the mixture entering the cylinder; the density of the mixture entering the cylinder is determined by the actual throttle outlet gas pressure, the temperature of the gas at the cylinder intake port, and the volumetric efficiency; 18) the engine speed; 19) the number of engine cylinders; 20) the engine single cylinder volume; 21) the mass flow of the mixture entering the cylinder; the mass flow 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 timing according to claim 2, characterized by, The method for calculating the throttle inlet gas pressure rate of change is: wherein is the throttle inlet gas pressure rate of change, is the throttle inlet gas pressure rate of change for the previous sample period; is the throttle inlet gas pressure, is the throttle inlet gas pressure for the previous sample period; is the sample period, is the throttle inlet gas pressure rate of change filter time constant; The method for calculating the throttle actual effective area rate of change is: wherein is the throttle actual effective area change rate, is the throttle actual effective area change rate of the previous sampling period; is the throttle actual effective area, is the throttle actual effective area of the previous sampling period; is the throttle actual effective area change rate filter time constant; The first characteristic parameter is ; wherein, is the gas constant, is the throttle inlet gas temperature; The method for calculating the throttle outlet gas actual pressure rate of change is: wherein is the throttle outlet gas actual pressure change rate, is the throttle outlet gas actual pressure change rate of the previous sampling period; is the throttle outlet gas actual pressure, is the throttle outlet gas actual pressure of the previous sampling period; is the throttle outlet gas pressure change rate filter time constant; The method for calculating the density of the mixture entering the cylinder is: wherein is the density of the mixture entering the cylinder, is the volumetric efficiency, is the molar mass of the mixture, is the temperature of the gas at the inlet of the intake valve of the cylinder. The method for calculating the mass flow of the mixture entering the cylinder is: wherein is the mass flow of the mixture into the cylinder, is the engine speed, is the engine single cylinder volume, is the number of engine cylinders.

4. The method for estimating the intake charge density at the intake valve closing timing according to claim 2, characterized by, The input signals of the current sampling period are obtained, including: The default values of the input signals are determined, including: 1) the default value of the intake pressure is the real-time reading of the throttle outlet gas actual pressure; 2) the default value of the intake manifold gas flow correction value is 0; 3) the default value of the flow of the crankcase ventilation introduced to the cylinder via the intake manifold is 0; 4) the default value of the pressure in the PCV pipe of the crankcase ventilation is the real-time reading of the atmospheric pressure; 5) the mass flow of fresh air entering the cylinder is the real-time reading of the mass flow of the mixture entering the cylinder; 6) the default value of the density of fresh air entering the cylinder is the real-time reading of the density of the mixture entering the cylinder; 7) the default value of the mass flow of the mixture entering the cylinder is the real-time reading of the mass flow of the mixture entering the cylinder; 8) the default value of the density of the mixture entering the cylinder is the real-time reading of the density of the mixture entering the cylinder; 9) the default value of the volumetric efficiency is 0; 10) the default value of the throttle actual effective area is the real-time reading of the throttle actual effective area; 11) the default value of the mass flow of the gas flowing through the throttle is the real-time reading of the mass flow of the mixture entering the cylinder; 12) Actual pressure ratio of throttle with a default value of 1 ; wherein, is the actual pressure of the gas at the throttle outlet, is the pressure of the gas at the throttle inlet; 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 rate; 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 reading of the atmospheric pressure; 16) the default value of the weighting coefficient is 1; the weighting coefficient is determined by the throttle outlet gas actual pressure and the throttle inlet gas pressure after the vehicle is powered on; The default values are only executed once when the vehicle is powered on, and the same input signals directly take the values of the previous sampling period in the next sampling period; and the input signals are updated.

5. The method for estimating the intake air density at the intake valve closing timing according to claim 4, characterized by, The method for calculating the throttle gas flow characteristic parameter is: wherein is the throttle gas flow characteristic parameter, is the throttle inlet gas temperature.

6. The method for estimating the intake charge density at the intake valve closing timing according to claim 4, characterized by, The input signals are updated, including: 1) the throttle actual pressure ratio is updated according to the throttle outlet gas actual pressure and the throttle inlet gas pressure; 2) the mass flow of the gas flowing through the throttle is updated; 3) the volumetric efficiency is updated according to the real-time values of all input signals used to calculate the volumetric efficiency; 4) the density of the mixture entering the cylinder is updated; 5) the mass flow of the mixture is updated according to the updated density of the mixture entering the cylinder; 6) the weighting coefficient is updated according to the real-time throttle outlet gas actual pressure and the throttle inlet gas pressure; the intake manifold gas flow correction value is updated according to the value of the intake manifold gas flow correction value in the previous sampling period; 7) the intake pressure is updated with the real-time target intake pressure value; 8) updating the throttle gas flow characteristic parameter; updating the throttle actual pressure ratio; updating the throttle pressure ratio flow coefficient according to the throttle actual pressure ratio; updating the gas mass flow through the throttle; 9) updating the charge efficiency according to the real-time values of all input signals for calculating the charge efficiency; 10) updating the intake mixture density into the cylinder according to the gas temperature at the intake port of the cylinder intake valve, the throttle outlet gas actual pressure and the updated charge efficiency; 11) updating the fresh air density into the cylinder according to the updated intake mixture density into the cylinder and the real-time acquired actual EGR rate; 12) updating the intake mixture mass flow according to the updated intake mixture density into the cylinder; 13) updating the fresh air mass flow into the cylinder according to the updated intake mixture mass flow into the cylinder and the real-time acquired actual EGR rate.

7. The method for estimating the intake charge density at the intake valve closing timing according to claim 6, characterized by, The updating of the gas mass flow through the throttle includes: wherein is the mass flow of gas through the throttle, is the throttle inlet gas pressure, is the throttle pressure ratio flow coefficient, is the throttle actual effective area, is the throttle inlet gas temperature; The updating of the fresh air density into the cylinder includes: wherein is the fresh air density into the cylinder, is the mixture density into the cylinder, is the actual EGR rate; The updating of the fresh air mass flow into the cylinder includes: wherein is the fresh air mass flow into the cylinder, is the mixture mass flow into the cylinder.

8. The method of estimating intake charge density at intake valve closing time according to claim 1, wherein, The input signals of the future multiple sampling periods are predicted, including: The input signals of the next sampling period are predicted; The input signals of the subsequent sampling periods of the next sampling period are predicted in turn; The method for predicting the input signals of the next sampling period includes: 1) predicting the weighting coefficient and the intake pressure change rate of the next sampling period according to the updated input signals of the present sampling period and the real-time acquired input signals of the present sampling period; 2) predicting the throttle inlet gas pressure of the next sampling period according to the throttle inlet gas pressure and the throttle inlet gas pressure change rate of the present sampling period, and limiting the predicted throttle inlet gas pressure within a set range; 3) predicting the throttle actual effective area of the next sampling period according to the throttle actual effective area and the throttle actual effective area change rate of the present sampling period, and limiting the predicted throttle actual effective area within a set range; 4) predicting the intake manifold gas flow correction value of the next sampling period; 5) predicting the intake pressure of the next sampling period according to the predicted intake pressure change rate and the acquired intake pressure of the present sampling period, and limiting the predicted intake pressure within a set range; 6) predicting the throttle gas flow characteristic parameter, the throttle actual pressure ratio, the throttle pressure ratio flow coefficient and the gas mass flow through the throttle of the next sampling period; 7) predicting the charge efficiency of the next sampling period according to the updated intake pressure; 8) predicting the intake mixture density into the cylinder of the next sampling period according to the predicted intake pressure, the charge efficiency and the gas temperature at the intake port of the cylinder intake valve; 9) predicting the intake mixture mass flow into the cylinder of the next sampling period according to the predicted intake mixture density into the cylinder; 10) predicting the fresh air density into the cylinder of the next sampling period according to the predicted intake mixture density into the cylinder and the real-time acquired actual EGR rate of the present sampling period; 11) estimating the fresh air mass flow into the cylinder in the next sampling period according to the estimated mixture mass flow into the cylinder and the actual EGR rate obtained in real time in the current sampling period; 12) estimating the actual EGR rate in the next sampling period according to the actual EGR rate obtained in real time in the current sampling period, the actual exhaust gas mass flow at the outlet of the EGR valve, and the gas temperature at the inlet of the cylinder intake valve, and the estimated mixture mass flow into the cylinder.

9. The method for estimating the intake charge density at the intake valve closing time according to claim 8, characterized by, The estimated intake manifold gas flow correction value in the next sampling period comprises: wherein is the intake manifold gas flow correction value for the next sampling period, is the intake manifold gas flow correction value, is the self-learning correction coefficient, is a function of the absolute value of the estimated intake manifold pressure change rate for the next sampling period . The estimated intake pressure in the next sampling period comprises: In the formula, is the intake pressure in the next sampling period, is the intake pressure, is the intake manifold intake pressure change rate in the next sampling period, is the sampling period; The estimated actual EGR rate in the next sampling period comprises: wherein is the actual EGR rate for the next sampling period, is the actual EGR rate, is the actual exhaust gas mass flow at the EGR valve outlet, is the mass flow of the mixture into the cylinder for the next sampling period, is the intake manifold volume.

10. The method for estimating the intake charge density at the intake valve closing time according to claim 9, characterized by, The method for updating the self-learning correction coefficient comprises: The average value of the intake manifold gas flow correction values of the future plurality of sampling periods is calculated, the intake manifold gas flow correction value of the current sampling period is subtracted from the average value, and the estimated intake manifold gas flow correction value difference is obtained ; Computing evaluation parameters X : In the formula, is an evaluation parameter of the previous sampling period; is a function of the estimated intake manifold gas flow correction value difference ; is a coefficient determined from the engine speed n and the throttle valve outlet target intake air pressure ; and is a calibration acquisition; The update conditions comprise: 1) the throttle valve is not fully open; 2) the actual pressure fluctuation range of the gas at the outlet of the throttle valve is within a preset range; 3) the engine speed fluctuation is within a preset range; 4) the target intake pressure fluctuation at the outlet of the throttle valve is within a preset range; 5) the fluctuation range is within a preset range; 6) Transient operating condition coefficient is 0; if the throttle is in a steady operating condition, the transient operating condition coefficient is 0, otherwise the transient operating condition coefficient is 1 ; All the above conditions are continuously satisfied for more than a first predetermined time, then the self-learning correction coefficient is updated Allowing updating; first read the average value of engine speed, average value of throttle target pressure ratio, average value of atmospheric pressure and Average value , update the self-learning correction coefficient under the same working condition of each parameter : wherein is a weighting factor, is a self-learning correction factor of the previous sampling period.

11. The method for estimating the intake charge density at the intake valve closing time according to claim 10, characterized by, The estimated final value of the estimated intake density when the intake valve of each cylinder is closed comprises: wherein is the final value of the intake air density, is the transient condition coefficient, is the transient value of the intake air density at the time of closing of the intake valve of each cylinder, is the fresh air density entering each cylinder for the current sampling period.

12. A computer device, comprising: A computer program product, comprising a memory and a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for estimating the intake density when the intake valve is closed according to any one of claims 1 to 11.

13. A computer-readable storage medium, characterized in that, A computer program product, comprising a memory and a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for estimating the intake density when the intake valve is closed according to any one of claims 1 to 11.

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