JP4605049B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  In recent years, an apparatus for modeling an intake system of an internal combustion engine based on fluid dynamics and the like and controlling the internal combustion engine based on values of operating parameters calculated using the model has been studied. In such a device, for example, a throttle model, an intake pipe model, an intake valve model, etc. are constructed for the intake system of an internal combustion engine, and by using these models, in-cylinder filling is performed from the throttle valve opening, atmospheric pressure, atmospheric temperature, etc. An air flow rate or the like is calculated, and based on this, the internal combustion engine is controlled (for example, control of the fuel injection amount, etc.).

  However, even when the actual intake system is modeled relatively accurately in the initial state, for example, when the operating characteristics and flow characteristics of the throttle valve, intake valve, etc. gradually change over a long period of time. The actual intake system and model will not match. Even in the initial state, the characteristics of the throttle valve, the intake valve, and the like vary within tolerances, and may not always exactly match the model. For this reason, in the throttle model and the intake valve model, an error is likely to occur between the actual intake system and the model.

  Therefore, it has been studied to modify the throttle model and the intake valve model during the operation of the internal combustion engine. For example, in the device described in Patent Document 1, the intake air pressure is calculated based on the estimated value of the intake pipe pressure calculated using the model calculation formula of the intake pipe model and the measured value of the intake pipe pressure measured by the intake pipe pressure sensor or the like. The model calculation formula of the valve model is modified. This is because, since the value of the cylinder intake air flow rate calculated using the model calculation formula of the intake valve model is used as the model calculation formula of the intake pipe model, an error occurs in the model calculation formula of the intake valve model. This is because an error also occurs in the estimated value of the intake pipe pressure calculated using the model calculation formula of the intake pipe model.

  In this way, by modifying the throttle model, intake valve model, etc. during operation of the internal combustion engine, the operating characteristics and flow characteristics of the throttle valve, intake valve, etc. change over a long period of time, Even if the characteristics of the intake valve or the like vary, the actual intake system and the model can be matched.

JP 2004-263571 A JP2004176663 JP 2004-111590 JP 2000-291484 A JP2003-5804

  By the way, in each model such as the throttle model, the intake pipe model, and the intake valve model as described above, the calculation load is extremely high if it tries to faithfully represent the actual fluid flow around the throttle valve, in the intake pipe, and around the intake valve. Therefore, these models are approximate models of actual fluid flow. For this reason, when modeling the intake system of the internal combustion engine, an approximation error occurs depending on the engine operating region (hereinafter referred to as “modeling approximation error”). Since such modeling approximation error is generally relatively small, each model is often calculated using a model calculation formula without correcting the modeling approximation error.

  However, as in the device described in Patent Document 1, correction of the intake valve model or the like is performed to compensate for changes in the operating characteristics and flow characteristics of the throttle valve, the intake valve, etc., and variations in the characteristics of the intake valve, etc. in the initial state. In addition to errors caused by such characteristic changes and variations, the modeling approximation error is also corrected.

  Here, the correction of the intake valve model or the like is generally performed uniformly in all engine operation regions, whereas the modeling approximation error does not occur uniformly in all engine operation regions, but a specific engine operation region. In many cases, it becomes large only. For this reason, if the model is modified so that the modeling approximation error is removed in the engine operation region where the modeling approximation error is large, the model will rather deviate from the actual intake system in the engine operation region where the modeling approximation error is small. May be overcorrected.

  Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can correct an intake system model of the internal combustion engine so as not to over-correct in consideration of modeling approximation error.

In order to solve the above-mentioned problem, in the first invention, the first operation parameter estimation means for detecting or estimating the value of the first operation parameter, and the relationship between the first operation parameter and the second operation parameter are modeled, Second operating parameter estimating means for estimating the value of the second operating parameter using a model calculation formula based on the value of the first operating parameter detected or estimated by the first operating parameter estimating means; and the second operating parameter In a control device for an internal combustion engine comprising an engine control means for controlling the internal combustion engine based on a value of a second operation parameter estimated by the estimation means, a model correction for correcting a model calculation formula of the second operation parameter estimation means Means for correcting the actual value of the second operating parameter corresponding to the predetermined value of the first operating parameter. The relationship between the first operating parameter and the second operating parameter from the fitting error between the value and the estimated value of the second operating parameter calculated by the second operating parameter estimating means based on the predetermined value of the first operating parameter The model calculation formula is corrected on the basis of a correction error from which a modeling approximation error caused by modeling the above is eliminated.
According to the first aspect of the invention, the model calculation formula is corrected on the basis of the approximation error obtained by removing the modeling approximation error. Therefore, the operating characteristics and the flow characteristics of the throttle valve, the intake valve, etc. It is possible to correct the model calculation formula so as to compensate only for variations in characteristics of the intake valve or the like, that is, not to remove the modeling approximation error.

  In the second invention, in the first invention, the model calculation formula is not corrected by the model correcting means in the engine operation region where the modeling approximation error is expected to be greater than or equal to a predetermined error.

  In a third invention, in the first or second invention, the first operating parameter is an intake pipe pressure, and the second operating parameter is a cylinder intake air flow rate.

  According to the present invention, there is provided a control device for an internal combustion engine that can correct an intake system model of the internal combustion engine so as not to over-correct in consideration of modeling approximation error.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The engine body 1 schematically shown in FIG. 1 represents a direct injection spark ignition type internal combustion engine. However, the present invention may be applied to another spark ignition internal combustion engine such as a port injection type spark ignition internal combustion engine or a compression self-ignition internal combustion engine.

  As shown in FIG. 1, in the embodiment of the present invention, the engine body 1 includes a cylinder block 2, a piston 3 that reciprocates within the cylinder block 2, and a cylinder head 4 fixed on the cylinder block 2. . A combustion chamber 5 is formed between the piston 3 and the cylinder head 4. In the cylinder head 4, an intake valve 6, an intake port 7, an exhaust valve 8, and an exhaust port 9 are arranged for each cylinder. Further, as shown in FIG. 1, a spark plug 10 is disposed at the center of the inner wall surface of the cylinder head 4, and a fuel injection valve 11 is disposed around the inner wall surface of the cylinder head 4. Further, a cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3. Further, the cylinder head 4 is provided with an intake valve control device 13 capable of continuously changing the phase angle and the valve lift amount of the intake valve 6.

  The intake port 7 of each cylinder is connected to a surge tank 15 via an intake branch pipe 14, and the surge tank 15 is connected to an air cleaner 17 via an intake pipe 16. A throttle valve 19 driven by a step motor 18 is disposed in the intake pipe 16. On the other hand, the exhaust port 9 of each cylinder is connected to an exhaust pipe 20, and the exhaust pipe 20 is connected to a casing 22 containing an exhaust purification catalyst 21. In the following description, portions of the intake branch pipe 14, the surge tank 15, the intake pipe 16 and the like from the throttle valve 19 to the intake valve 6 are referred to as an intake pipe portion 23.

  The electronic control unit (ECU) 31 comprises a digital computer, and is connected to each other via a bidirectional bus 32, a RAM (random access memory) 33, a ROM (read only memory) 34, a CPU (microprocessor) 35, an input. A port 36 and an output port 37 are provided. The surge tank 15 is provided with an intake pipe pressure sensor 40 for detecting the pressure of air (intake gas) in the intake pipe portion 23, and the intake pipe pressure sensor 40 is proportional to the pressure in the intake pipe portion 23. The output voltage is generated, and this output voltage is input to the input port 36 via the corresponding AD converter 38.

  The intake pipe 16 upstream of the throttle valve 19 is provided with an air flow meter 41 for detecting the flow rate of intake air flowing through the intake pipe 16, and the configuration of the air flow meter 41 in this embodiment will be described later. To do. Further, an intake air temperature sensor 42 for detecting the intake air temperature and an atmospheric pressure sensor 43 for detecting the atmospheric pressure are provided in the vicinity of the air cleaner 17. The throttle valve 19 is provided with a throttle valve opening sensor 44 that detects the opening of the throttle valve 19, and the throttle valve opening sensor 44 generates an output signal corresponding to the throttle valve opening. These air flow meter 41, intake air temperature sensor 42, atmospheric pressure sensor 43 and throttle valve opening sensor 44 output signals corresponding to intake air flow rate (mass flow rate), intake air temperature (atmospheric temperature), atmospheric pressure and throttle valve opening, respectively. This output signal is input to the input port 36 via the corresponding AD converter 38.

  A load sensor 46 that generates an output voltage proportional to the amount of depression of the accelerator pedal 45 is connected to the accelerator pedal 45, and the output voltage of the load sensor 46 is input to the input port 36 via the corresponding AD converter 38. The The crank angle sensor 47 generates an output pulse every time the crankshaft rotates 15 degrees, for example, and this output pulse is input to the input port 36. The CPU 35 calculates the engine speed from the output pulse of the crank angle sensor 45.

  On the other hand, the output port 37 is connected to the spark plug 10, the fuel injection valve 11, the intake valve control device 13, and the step motor 18 via a corresponding drive circuit 39.

  By the way, in the control device for the internal combustion engine, the combustion chamber 5 is filled when the intake valve 6 is closed in order to set the air-fuel ratio of the air-fuel mixture burned in the combustion chamber 5 of the internal combustion engine to the target air-fuel ratio. The amount of air (hereinafter referred to as “cylinder charged air amount Mc”) is estimated, and the fuel injection valve 11 is set so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio based on the estimated cylinder charged air amount Mc. Defines the amount of fuel injected into the combustion chamber 5 (or intake passage) of the internal combustion engine (hereinafter referred to as “fuel injection amount”). Therefore, in order to accurately set the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber 5 of the internal combustion engine to the target air-fuel ratio, it is necessary to accurately estimate the cylinder charge air amount Mc.

  Usually, the in-cylinder charged air amount Mc is estimated from a large number of sensors such as an air flow meter and a large number of maps using output values from these sensors as arguments. However, when the in-cylinder charged air amount Mc is estimated using the map in this way, in order to make the estimated value of the in-cylinder charged air amount Mc more accurate, the number of necessary maps and their arguments are required. The number of will increase. If the number of maps increases in this way, the ROM of the ECU for storing the maps must have a large storage capacity, which increases the manufacturing cost of the control device for the internal combustion engine. Furthermore, in order to create each map, a calibration operation must be performed for each type of internal combustion engine in which the map is used, but the number of measurement points in this calibration operation increases according to the number of maps and the number of arguments thereof. If the number of maps and the number of arguments increase, the number of man-hours for fitting work will increase.

  In view of this, a control device for an internal combustion engine that calculates the in-cylinder charged air amount Mc by numerical calculation using various models without using a map has been studied. In such a control apparatus, the number of necessary maps is reduced as much as possible by using a lot of numerical calculations. This greatly reduces the number of man-hours for performing the fitting work, but also the in-cylinder charged air amount Mc Can be calculated accurately. Among such control devices, one proposed by the applicant of the present application is a control device equipped with the air model shown in FIG. The illustrated air model is the simplest model applied to an internal combustion engine, and this air model will be described below.

  As shown in FIG. 2, the air model includes a throttle model M10, an intake pipe model M20, and an intake valve model M30. The throttle model M10 includes an opening (throttle valve opening) θt of the throttle valve 19 detected by the throttle valve opening sensor 44 and an atmospheric pressure (or an intake pipe) around the internal combustion engine detected by the atmospheric pressure sensor 43. 16) Pa, the air temperature around the internal combustion engine detected by the intake air temperature sensor 42 (or the temperature of air sucked into the intake pipe 16) Ta, and an intake pipe model M20 described later. The calculated pressure in the intake pipe portion 23 (hereinafter referred to as “intake pipe pressure”) Pm is input, and the values of these input parameters are substituted into a model calculation formula of a throttle model M10 described later. The flow rate of air passing through the throttle valve 19 per unit time (hereinafter referred to as “the estimated value mt of the air flow rate through the throttle”) is calculated. . The estimated value mt of the throttle passage air flow rate calculated in the throttle model M10 is input to the intake pipe model M20.

  The intake pipe model M20 includes an estimated value mt of the throttle passage air flow rate calculated in the throttle model M10 and a flow rate of air flowing into the combustion chamber 5 per unit time described below (hereinafter referred to as “in-cylinder intake”). The definition of the in-cylinder intake air flow rate mc will be described in detail in the description of the intake valve model M30), and the values of these input parameters are described later. By substituting into the model calculation formula of M20, the pressure of the air existing in the intake pipe portion 23 (hereinafter referred to as “intake pipe pressure Pm”) and the temperature of the air existing in the intake pipe portion 23 (hereinafter referred to as “ (Referred to as “intake pipe temperature Tm”). The intake pipe pressure Pm and the intake pipe temperature Tm calculated in the intake pipe model M20 are both input to the intake valve model M30, and the intake pipe pressure Pm is also input to the throttle model M10.

  In addition to the intake pipe pressure Pm and the intake pipe temperature Tm calculated in the intake pipe model M20, an atmospheric temperature Ta is input to the intake valve model M30, and the values of these input parameters are set in the intake valve model M30 described later. By substituting in the model calculation formula, the cylinder intake air flow rate mc is calculated. The calculated in-cylinder intake air flow rate mc is converted into the in-cylinder charged air amount Mc, and the fuel injection amount from the fuel injection valve is determined based on the in-cylinder charged air amount Mc. The in-cylinder intake air flow rate mc calculated in the intake valve model M30 is input to the intake pipe model M20.

  As can be seen from FIG. 2, in the air model, the parameter value calculated in one model is used as an input value to another model. Therefore, in the entire air model, the actually input value is the throttle valve opening θt, There are only three parameters of the atmospheric pressure Pa and the atmospheric temperature Ta, and the cylinder charge air amount Mc is calculated from these three parameters.

Next, each model M10 to M30 of the air model will be described.
In the throttle model M10, an estimated value mt of the throttle passage air flow rate is calculated from the atmospheric pressure Pa, the atmospheric temperature Ta, the intake air pressure Pm, and the throttle valve opening θt based on the following equation (1). Here, μt in equation (1) is a flow coefficient in the throttle valve, which is a function of the throttle valve opening θt, and is thus determined from a map as shown in FIG. At indicates the opening cross-sectional area of the throttle valve, which is a function of the throttle valve opening θt, and is determined from the map as shown in FIG. Note that μt · At obtained by collecting the flow coefficient μt and the opening cross-sectional area At may be obtained from one throttle map from the throttle valve opening θt. R is a constant related to the gas constant, and is actually a value obtained by dividing the gas constant by the mass Mlmol of gas (air) per mol.

Φ (Pm / Pa) is a function shown in the following formula (2), and κ in the formula (2) is a specific heat ratio (a constant value). Since this function Φ (Pm / Pa) can be expressed in a graph as shown in FIG. 5, such a graph is stored as a map in the ROM 34 of the ECU 31 and is actually calculated using the equation (2). Alternatively, the value of Φ (Pm / Pa) may be obtained from the map.

  Expressions (1) and (2) of the throttle model M10 are such that the gas pressure upstream of the throttle valve 19 is the atmospheric pressure Pa, the gas temperature upstream of the throttle valve 19 is the atmospheric temperature Ta, and the gas downstream of the throttle valve 19 is Applying the mass conservation law, the energy conservation law, and the momentum conservation law to the model of the throttle valve 19 as shown in FIG. 6 with the pressure being the intake pipe pressure Pm, and further defining the equation of state of gas and the specific heat ratio , And by using the Mayer relation.

In the intake pipe model M20, the intake pipe pressure Pm and the intake pipe temperature Tm are calculated from the estimated value mt of the throttle passage air flow rate, the in-cylinder intake air flow rate mc, and the atmospheric temperature Ta based on the following formulas (3) and (4). Is calculated. Vm in the equations (3) and (4) is a constant equal to the volume of the intake branch pipe 14, the surge tank 15, the intake pipe 16 and the like (intake pipe portion 23) from the throttle valve 19 to the intake valve 6. is there.

Here, the intake pipe model M20 will be described with reference to FIG. When the total gas amount (total air amount) in the intake pipe portion 23 is M, the temporal change in the total gas amount M is the flow rate of the gas flowing into the intake pipe portion, that is, the estimated value mt of the air flow rate through the throttle, and the intake air Since it is equal to the difference between the flow rate of the gas flowing out from the pipe portion, that is, the in-cylinder intake air flow rate mc, the following equation (5) is obtained according to the law of conservation of mass, and the gas state in this equation (5) and the intake pipe portion 23 Equation (3) is obtained from the equation (Pm · Vm = M · R · Tm).

Further, the temporal change amount of the gas energy M · Cv · Tm in the intake pipe portion 23 is equal to the difference between the energy of the gas flowing into the intake pipe portion 23 and the energy of the gas flowing out of the intake pipe portion 23. Therefore, when the temperature of the gas flowing into the intake pipe portion 23 is the atmospheric temperature Ta and the temperature of the gas flowing out from the intake pipe portion 23 is the intake pipe temperature Tm, the following equation (6) is obtained from the energy conservation law. Equation (4) is obtained from Equation (6) and the gas equation of state.

In the intake valve model M30, the in-cylinder intake air flow rate mc is calculated from the intake pipe internal pressure Pm, the intake pipe internal temperature Tm, and the atmospheric temperature Ta based on the following equation (7). In the equation (7), a and b are intake valves in the case of an internal combustion engine having a variable valve mechanism that can change the phase angle (valve timing) and operating angle of the intake valve 6 from the engine speed Ne. 6 is a value determined from the phase angle and the working angle.

  The above-described intake valve model M30 will be described with reference to FIG. In general, the in-cylinder charged air amount Mc, which is the amount of air charged in the combustion chamber 5 when the intake valve 6 is closed, is determined when the intake valve 6 is closed (when the intake valve is closed). This is proportional to the pressure in the combustion chamber 5 when the intake valve 6 is closed. Further, the pressure in the combustion chamber 5 when the intake valve 6 is closed can be regarded as being equal to the pressure of the gas upstream of the intake valve 6, that is, the intake pipe pressure Pm. Therefore, the cylinder charge air amount Mc can be approximated as being proportional to the intake pipe pressure Pm.

  Here, the average air flow rate flowing out of the intake pipe portion 23 per a certain time (for example, a crank angle of 720 °), or the intake pipe portion 23 per a certain time (for example, a crank angle of 720 °). If the cylinder intake air flow rate mc (described in detail below) is obtained by dividing the amount of air sucked into the combustion chambers 5 of all cylinders by the predetermined time, the cylinder charge air amount Mc becomes the intake pipe pressure Pm. Therefore, it is considered that the in-cylinder intake air flow rate mc is also proportional to the intake pipe pressure Pm. From this, the above formula (7) is obtained based on the theory and empirical rules. The value a in the equation (7) is a proportional coefficient, and the value b is a value representing the burned gas remaining in the combustion chamber 5 (the amount of burned gas remaining in the combustion chamber 5 when the exhaust valve 8 is closed). Is divided by a time ΔT180 ° described later). In actual operation, the intake pipe temperature Tm may change greatly during transient operation, and Ta / Tm derived based on theory and empirical rule is multiplied as a correction for this.

  Here, the cylinder intake air flow rate mc will be described with reference to FIG. 9 when the internal combustion engine has four cylinders. In FIG. 9, the horizontal axis represents the rotation angle of the crankshaft, and the vertical axis represents the flow rate of air actually flowing from the intake pipe portion 23 into the combustion chamber 5 per unit time. As shown in FIG. 9, in a four-cylinder internal combustion engine, the intake valve 6 is opened in the order of, for example, the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, and the intake valve 6 corresponding to each cylinder is opened. Air flows from the intake pipe portion 23 into the combustion chamber 5 of each cylinder according to the valve opening amount. For example, the displacement of the flow rate of air flowing into the combustion chamber 5 of each cylinder from the intake pipe portion 23 is as shown by a broken line in FIG. The flow rate of the air flowing into is as shown by the solid line in FIG. Further, for example, the in-cylinder charged air amount Mc to the first cylinder is as shown by hatching in FIG.

  On the other hand, the in-cylinder intake air flow rate mc is obtained by averaging the flow rate of the air flowing into the combustion chambers 5 of all the cylinders from the intake pipe portion 23 shown by the solid line, and is indicated by a one-dot chain line in the drawing. In the cylinder intake air flow rate mc indicated by the one-dot chain line, in the case of four cylinders, the crankshaft is 180 ° (that is, the angle 720 ° at which the crankshaft rotates during one cycle in the four-stroke internal combustion engine) The in-cylinder charged air amount Mc is obtained by multiplying the time ΔT180 ° required for rotation by an angle divided by the number. Therefore, the cylinder intake air amount Mc is calculated by multiplying the cylinder intake air flow rate mc calculated by the intake valve model M30 by ΔT180 ° (Mc = mc · ΔT180 °). More specifically, in consideration of the fact that the in-cylinder charged air amount Mc is proportional to the pressure when the intake valve is closed, the in-cylinder intake air flow rate mc when the intake valve is closed is multiplied by ΔT180 °. The filling air amount Mc.

Next, a description will be given of a case where the air model is mounted on a control device for an internal combustion engine and the in-cylinder charged air amount Mc is actually calculated. The in-cylinder charged air amount Mc is expressed by solving the above equations (1), (3), (4), and (7) using an air model. In this case, in order to be processed by the ECU 31, these equations need to be discretized. When the formula (1), the formula (3), the formula (4), and the formula (7) are discretized using the time t and the calculation interval Δt, the following formulas (8), (9), and (10) are respectively obtained. And Equation (11) is obtained. The intake pipe internal temperature Tm (t + Δt) is calculated by equation (12) from Pm / Tm (t + Δt) and Pm (t + Δt) calculated by equations (9) and (10), respectively.

  In the air model implemented in this manner, the estimated value mt (t) of the throttle passage air flow rate at time t calculated by the equation (8) of the throttle model M10 and the equation (11) of the intake valve model M30 are calculated. The in-cylinder intake air flow rate mc (t) at time t is substituted into the equations (9) and (10) of the intake pipe model M20, whereby the intake pipe pressure Pm (t + Δt) and the intake pipe temperature at time t + Δt are calculated. Tm (t + Δt) is calculated. Next, the calculated Pm (t + Δt) and Tm (t + Δt) are substituted into the equations (8) and (11) of the throttle model M10 and the intake valve model M30, thereby estimating the throttle passing air flow rate at time t + Δt. mt (t + Δt) and in-cylinder intake air flow rate mc (t + Δt) are calculated. Then, by repeating such calculation, the cylinder intake air flow rate mc at any time t is calculated from the throttle valve opening θt, the atmospheric pressure Pa, and the atmospheric temperature Ta, and the calculated cylinder intake air flow rate is calculated. By multiplying mc by the time ΔT180 °, the in-cylinder charged air amount Mc at an arbitrary time t is calculated.

  At the time of starting the internal combustion engine, that is, at time t = 0, the intake pipe pressure Pm is equal to the atmospheric pressure (Pm (0) = Pa), and the intake pipe temperature Tm is equal to the atmospheric temperature (Tm (0)). = Ta), the calculation in each of the models M10 to M30 is started.

  In the air model, the atmospheric temperature Ta and the atmospheric pressure Pa are assumed to be constant. However, the air model may be a value that changes with time, for example, a value detected at time t by an intake air temperature sensor for detecting the atmospheric temperature. Is the atmospheric temperature Ta (t), and the value detected at time t by the atmospheric pressure sensor for detecting the atmospheric pressure is the atmospheric pressure Pa (t), the above equations (8), (10), and (11) May be substituted into.

  Incidentally, as described above, in the apparatus of FIG. 2, the cylinder intake charge amount is calculated by sequential calculation from the start of the engine using a model calculation formula that inputs only the throttle valve opening θt, the atmospheric temperature Ta, and the atmospheric pressure Pa. The For this reason, if an error occurs in each element model of the air model, the calculated in-cylinder charged intake air amount becomes inaccurate and the fuel injection amount cannot be accurately calculated.

  Here, considering each element model of the air model (throttle model M10, intake pipe model M20, intake valve model M30, etc.), even if there is no error in the modeling itself, changes in characteristics and manufacturing tolerances due to use. There may be an error (hereinafter referred to as “aging / manufacturing error”) due to variations due to the above. Therefore, in the present embodiment, each element model is modified to compensate for aging and manufacturing errors occurring in each element model based on the actually measured values.

  Here, among the element models included in the air model, the throttle model M10 and the intake valve model M30 are likely to vary due to manufacturing / assembly tolerances and characteristic changes (changes in flow coefficient, etc.) due to use. On the other hand, the intake pipe model M20 is a relatively simple model in which only the volume is a problem, and characteristic changes due to variations and use are unlikely to occur. There is no need to modify this model. Therefore, it is necessary to correct the model formula for the throttle model M10 and the intake valve model M30, which are likely to cause aging and manufacturing errors, based on actual measurement values during engine operation.

  Therefore, in the present embodiment, the intake valve model M30 is corrected based on the actually measured value during engine operation. In particular, in the present embodiment, the actual actual airflow passing air flow rate, throttle valve opening, intake pipe pressure, and the like are measured by the air flow meter 41, throttle valve opening sensor 44, intake pipe pressure sensor 40, etc. 2 is used to correct the throttle model M10, the intake valve model M30, etc. independently of the calculation of the in-cylinder charged intake amount in FIG. Below, the correction method of the intake valve model M30 is demonstrated.

  As described above, “a” used in the equation (7) of the intake valve model M30 is a proportional coefficient, and “b” is a conforming value representing the burned gas remaining in the combustion chamber 5. These conforming values a and b are conforming values determined in accordance with the engine operating state such as the engine speed NE, the intake valve phase angle and the working angle (which will be described below by taking the intake valve opening timing VVT as an example). is there. For this reason, the conforming values a and b are calculated in advance experimentally or by calculation for each map area as will be described later, for example, for each engine speed NE and the valve opening timing VVT of the intake valve 6, etc. ) And FIG. 10B, the map is stored in the ECU 31 as a map. During engine operation, when calculating the above equation (7) by the intake valve model M30, the engine rotational speed NE detected by the crank angle sensor 47 and the instruction of the intake valve opening timing VVT to the intake valve control device 13 are given. Based on the values and the like, the matching values a and b are calculated using the map. FIG. 10 (a) shows a map of the compliance value a, and FIG. 10 (b) shows a map of the compliance value b, where the x-axis represents the engine speed NE and the y-axis represents the intake valve opening. The valve timing VVT (advance angle as the y-axis increases) is shown.

  However, these conforming values a and b may have aging and manufacturing errors due to changes in characteristics due to use and variations due to manufacturing tolerances as described above. Thus, in the case where there are aging and manufacturing errors in the conforming values a and b, in order to accurately calculate the estimated value mc of the in-cylinder intake air flow rate by the equation (7) of the intake valve model M30, It is necessary to correct the conforming values a and b.

  Here, in the present embodiment, the adaptation values a and b are determined for each map area as described above. In the example shown in FIG. 10, the conforming values a and b are obtained for each map area (for example, the shaded portion in FIG. 10 represents one map area), that is, the engine speed at a constant interval and the constant interval. It is determined for each intake valve opening timing. Therefore, the adaptation values a and b must be corrected for each map area.

Therefore, in the present embodiment, the adaptation values a and b used in the equation (7) of the intake valve model M30 are corrected for each map area. Hereinafter, as an example, the engine speed NE and the intake valve opening timing VVT are in the map region B (that is, the engine speed NE is between NE ₀ and NE ₁ and the intake valve opening timing VVT is from VVT _0. A method of correcting the conforming values a and b (that is, the map values a _ij and b _ij in FIG. 10) in the case of being in the map area between VVT ₁ will be described.

FIG. 11 is a time chart of the intake pipe pressure Pm, the engine speed NE, and the intake valve opening timing VVT during operation of the internal combustion engine. In the illustrated example, the engine speed NE at time t ₀ later has a NE ₀ or more, and the time t ₁ the engine rotational speed in the subsequent NE has become NE ₁ or more. That is, the engine speed NE has a value between NE ₀ and NE ₁ over from time t ₀ to time t _1, and the value between NE ₀ and NE ₁ in other time is not. On the other hand, the intake valve opening timing VVT is a value between VVT ₀ and VVT ₁ from time t ₀ to time t ₁ .

Thus, the VVT engine rotational speed NE and the intake valve opening timing, the time t ₀ before rather than in the map region B, at time t ₀ over the time t ₀ with entering the map area B to time t ₁ It is in the map area B. Then detached from the map area B at time t _1, after time t ₁ is not in the map area B. Then, when the values of the engine speed NE and the intake valve opening timing VVT are within the map region B, that is, from time t ₀ to time t ₁ , the expression (7) of the intake valve model M30 is calculated. In this case, matching values a and b (that is, map values a _ij and b _ij ) corresponding to the map area B are used.

Here, considering the above formula (6) again, the left side of the formula (6) represents a temporal change amount of the internal energy of the gas in the intake pipe portion 23, and the right side of the formula (6) is represented by Cp · mt · Ta represents the energy of the gas flowing into the intake pipe portion 23, and Cp · mc · Tm represents the energy of the gas flowing out of the intake pipe portion 23, respectively. Here, considering the gas state equation (Pm · Vm = M · R · Tm) in the intake pipe portion 23, the left side of the equation (6) can be expressed as the following equation (13).

Therefore, the temporal change amount of the internal energy from time t ₀ to time t ₁ can be expressed by the following formula (14). In particular, since the actual value Pmr of the intake pipe pressure is detected by the intake pipe pressure sensor 40, by using the actual value Pmr of the intake pipe pressure in the equation (14), the interval between time t ₀ and time t ₁ is used. The actual amount of change in internal energy over time can be accurately calculated. In equation (14), Pmr (t ₀ ) represents the actual value of the intake pipe pressure at time t ₀ , and Pmr (t ₁ ) represents the actual value of the intake pipe pressure at time t ₁ .

On the other hand, regarding the energy of the gas flowing into the intake pipe portion 23 (that is, Cp · mt · Ta on the left side of the equation (6)), the substantial variable is only the throttle passage air flow rate mt. If the throttle passage air flow rate mt can be accurately calculated or detected by the air flow meter 43 or the like, the energy of the gas flowing into the intake pipe portion 23 can be accurately calculated. In particular, the energy of the gas flowing into the intake pipe portion 23 from time t ₀ to time t ₁ can be calculated by the following equation (15).

Thus, the temporal change amount of the internal energy from time t ₀ to time t ₁ is the above equation (14), and the energy of the gas flowing into the intake pipe portion 23 from time t ₀ to time t ₁ is the above-described equation (14). Since each is accurately calculated by the equation (15), the gas flowing out from the intake pipe portion 23 from the time t ₀ to the time t ₁ is calculated by the following equation (16) obtained by subtracting the equation (14) from the equation (15). Energy can be calculated accurately.

Here, as described above, the energy of the gas flowing out from the intake pipe portion 23 can be expressed by Cp · mc · Tm, and the cylinder calculated by the intake valve model M30 (ie, equation (7)) as this mc. When the estimated value mc of the internal intake air flow rate is used, the energy of the gas flowing out from the intake pipe portion 23 from time t ₀ to time t ₁ can be expressed by the following equation (17). Since both the equations (16) and (17) represent the energy of the gas flowing out from the intake pipe portion 23, the values calculated by these equations should be the same.

  However, if there is an error in the model calculation formula (7) of the intake valve model M30, the values calculated by the formula (16) and the formula (17) do not match. In particular, in the above formula (17), considering that the actual value Pmr of the intake pipe pressure detected by the intake pipe pressure sensor 40 is used as the intake pipe pressure, the formula (16) does not match the formula (17). In this case, it is considered that there is an error in the conforming values a and b used in Equation (7).

Therefore, in this embodiment, the error rate of the actual in-cylinder intake air flow rate with respect to the estimated value mc of the in-cylinder intake air flow rate calculated by the intake valve model M30 (the actual in-cylinder intake air flow rate / calculated by the intake valve model M30). The estimated value of the in-cylinder intake air flow rate (hereinafter referred to as “conformity error rate”) is α. Since the value calculated by multiplying the equation (17) by the adaptation error rate α is equal to the value calculated by the equation (16), the following equation (18) is established. When the equation (18) is solved for the matching error rate α, the matching error rate α can be expressed as the following equation (19).

The adaptation error rate α calculated in this way is the actual in-cylinder intake when the engine operating state is in a specific map region, for example, when the engine speed NE and the intake valve opening timing VVT are in the map region B. It represents the error rate between the air flow rate and the estimated value mc of the in-cylinder intake air flow rate calculated by the intake valve model M30. In order to compensate for the error in the in-cylinder intake air flow rate, in this embodiment, the matching values a and b (that is, the map values a _ij and b _ij ) corresponding to the map region B are multiplied by the error rate α. It is assumed that the new matching values a ′ and b ′ corresponding to the map area B are set (a _ij ′ = α · a _ij , b _ij ′ = α · b _ij ). In this way, by correcting the adaptation values a and b used in the equation (7) of the intake valve model M30, the estimated value mc of the cylinder intake air flow rate calculated by the intake valve model M30 is changed to the actual cylinder intake air. The value can be approximately equal to the flow rate. That is, the intake valve model M30 is corrected so as to substantially match the intake system around the actual intake valve.

  As described above, in this embodiment, the engine operating state (for example, the engine speed NE and the intake valve opening timing VVT) enters the specific map area (for example, the map area B) and then leaves. The actual value of the energy of the gas flowing out from the intake pipe portion 23 (that is, the value calculated using the energy conservation law of the intake pipe portion 23) and the intake valve model M30 of such gas energy are calculated. By correcting the map values of the adaptation values a and b corresponding to the specific map region based on the ratio between the actual value and the value calculated using the intake valve model M30, Even when the internal combustion engine is in a transient operation, the map values of the adaptation values a and b can be corrected accurately.

  Here, the estimated value of the intake pipe pressure calculated by the intake pipe model M20 is calculated using the estimated value of the in-cylinder intake air flow rate calculated by the intake valve model M30 a predetermined time ago. Therefore, for example, based on the deviation between the actual value of the intake pipe pressure and the estimated value of the intake pipe pressure calculated by the intake pipe model M20 using the estimated value of the in-cylinder intake air flow rate calculated by the intake valve model M30. If the map values of the adaptive values a and b are to be corrected, the measured value of the intake pipe pressure is a value corresponding to the current actual in-cylinder intake air flow rate, whereas the intake pipe model M20 calculates the intake pipe internal pressure. Since the estimated value of the pressure is a value corresponding to the estimated value mc of the in-cylinder intake air flow rate calculated by the intake valve model M30, the intake valve is relatively accurately obtained when the internal combustion engine is in steady operation. Although the model can be corrected, the intake valve model cannot be corrected accurately when the internal combustion engine is in transient operation.

  On the other hand, in the present embodiment, the intake pipe from when the engine operating state (for example, the engine speed NE and the intake valve opening timing VVT) enters the specific map region (for example, the map region B) and then leaves. The actual value of the energy of the gas flowing out from the portion 23 (that is, the value calculated using the energy conservation law of the intake pipe portion 23) and the value calculated using the intake valve model M30 of the energy of such gas And the map values of the matching values a and b are corrected so that these values match. Thus, by comparing the total amount of energy of the gas flowing out from the intake pipe portion 23 while the engine operating state is in a specific map region, that is, between the integrated values of the energy outflow amount per unit time during such period. By comparing these, the conforming values a and b corresponding to this specific map region can be accurately corrected even when the internal combustion engine is in a transient operation.

Next, a case where the adaptation error rate α is actually calculated from the estimated value mt of the throttle passage air flow rate and the actually measured value Pmr of the intake pipe pressure based on the above equation (19) will be described. The ECU 31 cannot directly calculate the integral term in the equation (19). Therefore, the integral term for the estimated value mt of the throttle passage air flow rate in the equation (19) is calculated by the following equation (20) discretized using the time t and the calculation interval Δt, and the intake pipe pressure Pm is calculated. The integral term is calculated by the following equation (21) discretized using the time t and the calculation interval Δt.

As for the integral term for the estimated value mt of the throttle passing air flow rate, the estimated value mt (t) of the throttle passing air flow rate at the time t is substituted into the equation (20). An integral term value mtint (t) for the estimated value mt is calculated. Regarding the integral term for the actual measured value Pmr of the intake pipe pressure, the actual measured value Pmr (t) of the intake pipe pressure at time t is substituted into the equation (21), whereby the actual measured value Pmr of the intake pipe pressure at time t. The integral term value hint (t) for is calculated. In calculating any integral term, when the engine speed NE and the intake valve opening timing VVT enter the target map region, that is, the estimated value mt (t ₀ ) of the throttle passage air flow at time t ₀ . Then, the above formula (20) and formula (21) are calculated using the actual measurement value Pmr (t ₀ ) of the intake pipe pressure as an initial value.

Then, the calculation of the adaptive error rate α by the equation (19) is performed after the engine speed NE and the intake valve opening timing VVT have departed from the target map area, that is, after time t ₁ . Since it is the throttle-passing air flow rate estimate mt (t ₀₎ an initial value at time t ₀ for formula (20), the value of the integral term for the estimated value mt of the throttle passage air flow rate at time t ₁ mtint ( t ₁ ) represents the integral value of mt from time t ₀ to time t ₁ , and the initial value for equation (21) is the intake pipe pressure Pm (t ₀ ) at time t ₀ . the value of the integral term for the actual measurement values Pmr of the intake pipe pressure at the time t ₁ hint (t ₁₎ represents an integral value of a · Pm + b from time t ₀ to time t _1. For this reason, the fitting error rate α in the map area is calculated by the following equation (22).

  By the way, in the above description, the adaptation error rate α is calculated by the equation (19) using the actual value of the intake pipe pressure detected by the intake pipe pressure sensor 40. However, the actual pressure in the intake pipe portion 23 varies greatly due to the intake pulsation, and the intake pipe pressure detected by the intake pipe pressure sensor 40 also varies greatly as shown by the solid line in FIG. On the other hand, in the intake pipe model M20 and the intake valve model M30 described above, the pressure pulsation generated in the intake pipe portion 23 is ignored and one cycle of the actual pressure in the intake pipe portion 23 (in this embodiment, the crank angle is 720 °). ) Is used as the intake pipe pressure Pm (hereinafter referred to as “average value between cycles”). Further, the output of the intake pipe pressure sensor 40 often includes noise.

Therefore, when the adaptation error rate α is calculated by directly using the actually measured values Pmr (t ₀ ) and Pmr (t ₁ ) of the intake pipe pressure at time t ₀ and time t ₁ detected by the intake pipe pressure sensor 40, that is, When the engine speed NE and the intake valve opening timing VVT enter and exit from a certain map area, the measured value Pmr of the intake pipe pressure detected by the intake pipe pressure sensor 40 is directly used to make a fit error. If the rate α is calculated, the value of the calculated matching error rate α may be inaccurate.

  Therefore, in the present embodiment, as described above, the actual value Pmr of the intake pipe pressure detected by the intake pipe pressure sensor 40 is directly used to calculate the adaptation error rate α, and is detected by the intake pipe pressure sensor 40. The adaptation error rate α is calculated using the average value between cycles of the actually measured value of the intake pipe pressure (broken line in FIG. 12). That is, the average value between cycles of the actually measured value of the intake pipe pressure detected by the intake pipe pressure sensor 40 in the cycle including the time when the engine speed NE and the intake valve opening timing VVT enter a certain map area is entered into this map. Is used as the actual measured value Pmr of the intake pipe pressure at the time, and the average value between cycles of the actually measured value of the intake pipe pressure detected by the intake pipe pressure sensor 40 in the cycle including the time when the map is separated from the map area Using the measured value Pmr of the in-pipe pressure, the matching error rate α is calculated by the above equation (19).

  In this way, by using the average value between cycles of the actually measured value of the intake pipe pressure detected by the intake pipe pressure sensor 40 as the measured value Pmr of the intake pipe pressure used in the expression (19), it is input to the expression (19). The measured value Pmr of the intake pipe internal pressure is a value that excludes the influence of pressure pulsation generated in the intake pipe portion 23 in the same manner as the intake pipe internal pressure Pm used in the intake pipe model M20 and the intake valve model M30. Therefore, the matching error rate α can be accurately calculated by the equation (19). Further, it is possible to suppress the influence of noise included in the output of the intake pipe pressure sensor 40 when calculating the adaptation error rate α.

By the way, in the above description, the adaptation values a and b are constant regardless of the value of the intake pipe pressure Pm. However, depending on the map area, even if the map area is the same, there are two different values when the intake pipe pressure Pm is less than a predetermined pressure Pmk (Pm <Pmk) and when the pressure is higher (Pm ≧ Pmk). It has been found that by taking (for example, a ₁ , b ₁ and a ₂ , b ₂ ), the cylinder intake air flow rate mc may be determined more accurately. In other words, the in-cylinder intake air flow rate mc can be calculated more accurately by changing the above equation (7) into the following equation (23). In this case, the straight lines represented by these two equations are connected at a point of Pm = Pmk. The solid line in FIG. 13 illustrates equation (23).

  The cylinder intake air flow rate mc can be more accurately calculated by approximating the relationship between the intake pipe pressure Pm and the cylinder intake air flow rate mc with the two straight lines represented by the above equation (23). In particular, it is considered that the burnt gas flows back to the intake port 7 particularly when there is a period in which both the intake valve 6 and the exhaust valve 7 are open (that is, valve overlap). That is, in the case where there is a valve overlap, when the intake pipe pressure Pm is equal to or higher than the predetermined pressure Pmk, the higher the intake pipe pressure Pm, the more the backflow of burned gas decreases significantly. As the value a increases, the value b decreases.

  However, even if the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc is approximated by the two straight lines expressed by the above equation (23) as shown by the solid line in FIG. An error often occurs with respect to the relationship between the pressure and the in-cylinder intake air flow rate. That is, when the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc is approximated by the above two straight lines, as shown in FIG. The amount of change in the cylinder intake air flow rate / the amount of change in the intake pipe pressure) changes rapidly. However, in the relationship between the actual intake pipe pressure and in-cylinder intake air flow rate, the inclination gradually changes as shown by the broken line in FIG. Therefore, when the relationship between the intake pipe pressure and the cylinder intake air flow rate is approximated by the two straight lines expressed by the above equation (23), the relationship between the actual intake pipe pressure and the cylinder intake air flow rate is Thus, an error corresponding to the interval between the solid line and the broken line in FIG. 13 occurs. That is, when the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc is modeled so as to be approximated by the two straight lines represented by the above equation (23), A modeling approximation error (Errm in FIG. 13) corresponding to the interval occurs. As can be seen from FIG. 13, the modeling approximation error is particularly large in the vicinity of the point Pm = Pmk, that is, in the vicinity of the bending point between two straight lines.

  However, since such modeling approximation error is relatively small, it is within an allowable range in calculating the cylinder intake air flow rate mc based on the intake pipe pressure Pm by the intake valve model M30. If the model calculation formula of the intake valve model is created so as to eliminate such modeling approximation error, the calculation load for calculating the cylinder intake air flow rate by the intake valve model becomes extremely large. For this reason, in the present embodiment, the in-cylinder intake air flow rate mc is calculated based on the intake pipe pressure Pm using the above equation (23) without removing such modeling approximation error of the intake valve model. Yes.

When the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc is modeled as two straight lines, the intake pipe pressure is detected based on the actual measured value Pmr detected by the intake pipe pressure sensor 40. As described above, when the model calculation formula of the intake valve model M30 is corrected, that is, when the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ of the formula (23) are corrected based on the intake pipe pressure Pmr, the correction operation is performed. Accordingly, the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc expressed by the model calculation formula of the intake valve model M30 deviates from the actual relationship between the intake pipe pressure and the in-cylinder intake air flow rate. There is. This will be described below.

Correction of applicable values a ₁ , a ₂ , b ₁ , and b ₂ in the engine operating region in which the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc is represented by two straight lines as shown in Equation (23). As a method for performing the above, a method similar to the above-described correction method can be considered. That is, using the above equation (19), the adaptation error rate α is calculated when the engine speed NE and the intake valve opening timing VVT are in a certain specific map area, and then the adaptation corresponding to the specific map area is performed. The values a ₁ , a ₂ , b ₁ , b ₂ multiplied by the adaptation error rate α are used as new adaptation values a ₁ , a ₂ , b ₁ , b ₂ (a ₁ = α · a ₁ , a ₂ = Α · a ₂ , b ₁ = α · b ₁ , b ₂ = α · b ₂ ).

  FIG. 14 is a diagram showing the relationship between the intake pipe pressure Pm and the cylinder intake air flow rate mc, as in FIG. For example, the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc represented by the current equation (23) is as shown by a solid line A in FIG. Consider a case where the relationship with the in-cylinder intake air flow rate is as shown by a one-dot chain line B in FIG.

In this case, the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc expressed by the equation (23) is suitable for the actual relationship between the intake pipe pressure and the in-cylinder intake air flow rate, that is, in FIG. Applicable values a ₁ , a ₂ , b ₁ of equation (23) so that the relationship shown by the broken line C (hereinafter referred to as “the relationship between the corrected target intake pipe pressure and the cylinder intake air flow rate”) is obtained. B ₂ need to be corrected. Here, when the intake pipe pressure Pm is Pm ₁ away from the Pmk, the adaptation error rate α is calculated as described above, and the adaptation values a ₁ , a as described above are calculated based on the adaptation error rate α. ₂ , b ₁ , b ₂ are corrected, the intake pipe pressure Pm and the cylinder intake air flow rate mc represented by the equation (23) using the corrected adaptation values a ₁ , a ₂ , b ₁ , b ₂ The relationship is as shown by the broken line C in FIG.

That is, when the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ are corrected as described above based on the adaptation error rate α when the intake pipe pressure Pm is Pm ₁ , the adaptation before correction is performed based on Pm _1. The in-cylinder intake air flow rate mc ₁ (point on the solid line A in the figure) calculated by the equation (23) using the values a ₁ , a ₂ , b ₁ , and b ₂ , and the intake pipe pressure Pm is Pm ₁ . A fitting value a ₁ so as to remove an error (hereinafter referred to as “fitting error Errra”) with respect to an actual in-cylinder intake air flow rate mc ₁ ′ (a point on the chain line B in the figure) at a certain time, a ₂ , b ₁ , b ₂ are corrected. When the intake pipe pressure Pm is Pm ₁ , the modeling approximation error Errm hardly exists as described above. Therefore, the adaptation error Errra hardly includes the modeling approximation error Errm. Thus, the modified adaptation values a ₁ , a ₂ , b ₂ are modified by modifying the adaptation values a ₁ , a ₂ , b ₁ , b ₂ so as to eliminate the adaptation error Era (ie based on the adaptation error rate α). The relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc represented by Expression (23) using b ₁ and b ₂ is as shown by a broken line C in FIG. Therefore, when the adaptation values a ₁ , a ₂ , b ₁ , b ₂ are corrected based on the adaptation error rate α calculated when the intake pipe pressure Pm is in a region away from the Pmk, these adaptation values a ₁ , a ₂ , b ₁ , b ₂ can be appropriately corrected.

On the other hand, when the intake pipe pressure Pm is Pm ₂ in the vicinity of the Pmk, the adaptation error rate α is calculated as described above, and the adaptation values a ₁ , a ₂ , b ₁ , b are calculated based on the adaptation error rate α. _{When 2} is corrected, the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc represented by the equation (23) using the corrected adaptation values a ₁ , a ₂ , b ₁ , and b ₂ is shown in FIG. The relationship is as shown by the two-dot chain line D.

That is, when the intake pipe pressure Pm is Pm ₂ , the modeling approximation error Errm as described above exists, and the adaptation error Erra includes the modeling approximation error Errm. Therefore, when the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ are corrected so as to remove the adaptation error Erra, the modeled approximation error Errm that does not need to be removed is removed, and as a result, the corrected adaptation value is corrected. The relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate mc expressed by the equation (23) using a ₁ , a ₂ , b ₁ , and b ₂ is as shown by a two-dot chain line D in FIG. End up. Therefore, when the adaptation values a ₁ , a ₂ , b ₁ , b ₂ are corrected based on the adaptation error rate α calculated when the intake pipe pressure Pm is Pm ₂ , these adaptation values a ₁ , a ₂ , B ₁ and b ₂ cannot be corrected appropriately, resulting in excessive correction.

Therefore, in the present embodiment, the model calculation formula is corrected, that is, the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ of the intake valve model M30 are corrected, and the modeling approximation error Errm included in the adaptation error Errra is removed. I will do it based on what I did. Hereinafter, a method of correcting the model calculation formula in the present embodiment will be described.

The adaptation error rate α at an arbitrary intake pipe pressure Pm calculated as described above (hereinafter, the case where the intake pipe pressure is Pm ₂ ) is determined based on the intake pipe pressure Pm ₂ before the correction. value _{a 1, a 2, b 1} , b 2 a cylinder intake air flow rate mc ₂ calculated by equation (23) using its intake pipe in actual in-cylinder intake corresponding to the pressure Pm ₂ air flow rate mc ₂ (Α = mc ₂ '/ mc ₂ ).

On the other hand, according to the equation (23) using the adaptation values a ₁ ′, a ₂ ′, b ₁ ′, b ₂ ′ modified so as to match the relationship between the corrected target intake pipe pressure and the cylinder intake air flow rate. modeling the ratio of the arbitrary intake pipe pressure Pm ₂ cylinder intake air flow rate mc 2 calculated based on _'and' and its intake pipe actual cylinder intake air flow rate corresponding to the pressure Pm ₂ mc ₂ ' The approximate error rate β is assumed. A method for obtaining the modeled approximate error rate β will be described later.

When the modeling approximation error rate β is set in this way, it is calculated based on an arbitrary intake pipe pressure Pm ₂ by the equation (23) using the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ before correction. The above arbitrary intake air according to the equation (23) using the value obtained by multiplying the in-cylinder intake air flow rate mc ₂ by the adaptation error rate α and the modified adaptation values a ₁ ′, a ₂ ′, b ₁ ′, b ₂ ′. The value obtained by multiplying the in-cylinder intake air flow rate mc ₂ ″ calculated based on the in-pipe pressure Pm ₂ by the modeling approximate error rate β is an actual in-cylinder corresponding to the arbitrary intake pipe pressure Pm ₂ . Since the intake air flow rate mc ₂ ′ is shown, the following equation (24) is established. And if this is modified, it can be expressed as the following formula (25).

Here, when α / β is a correction error rate γ (γ = α / β), the correction error rate γ is an adaptation value a ₁ , a ₂ , b before correction when the intake pipe pressure is Pm _{2. 1,} b-cylinder intake air flow rate mc ₂ calculated by equation (23) using _2, corrected target corrected adaptation values a to accommodate the relationship between the intake pipe pressure and the cylinder intake air flow rate _This represents the ratio to the in-cylinder intake air flow rate mc ₂ ″ calculated by the equation (23) using ₁ ′, a ₂ ′, b ₁ ′, b ₂ ′. Such a relationship is not limited to when the intake pipe pressure is Pm ₂ , but is considered to hold in all regions of the intake pipe pressure. Therefore, in the present embodiment, a new adaptation value is obtained by multiplying the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ before correction by the correction error rate γ (a ₁ ′ = γ · a ₁ , a ₂ ′ = γ · a ₂ , b ₁ ′ = γ · b ₁ , b ₂ ′ = γ · b ₂ ).

  Here, the modeling approximation error rate β is modeled so that the relationship between the intake pipe pressure Pm and the cylinder intake air flow rate mc in the intake valve model M30 is approximated by the two straight lines represented by the above equation (23). Represents the error rate generated with respect to the relationship between the actual intake pipe pressure and the cylinder intake air flow rate (that is, the error rate of the broken line C with respect to the alternate long and short dash line B in FIGS. 14 and 15). ). This modeling approximate error rate β is basically determined for each engine speed NE, intake valve opening timing VVT, and the like when the intake valve model M30 is created. Therefore, the engine speed NE is created after the intake valve model M30 is created. Also, it is obtained by experiment or calculation for each intake valve opening timing VVT or the like. And it is memorize | stored in ROM34 of ECU31 as a map as shown in FIG.15 (b).

Thus, according to the present embodiment, the intake valve model M30 is not corrected based on the adaptation error, but the intake valve model M30 is corrected based on the model error obtained by removing the modeling approximation error. I am going to do that. That is, in the present embodiment, the adaptation values a ₁ , a ₂ , b ₁ , b ₂ used for the model calculation formula (23) of the intake valve model M30 based on the adaptation error rate divided by the modeling approximate error rate. Is going to be fixed. As a result, the intake valve model M30 can be appropriately corrected even in the engine operation region where the modeling approximation error is large.

FIG. 16 is a flowchart showing a control routine of a correction operation for the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ used in the model calculation formula (23) of the intake valve model M30. Each routine is executed by interruption every certain time interval.

  First, in step 101, the engine speed NE, the intake valve opening timing VVT, and the actual measured value Pmr of the intake pipe pressure are respectively output signals from the crank angle sensor 47, input signals to the intake valve control device 13, and intake pipe pressure sensors. Detected based on the output signal from 40. Next, at step 102, based on the engine speed NE and the intake valve opening timing VVT detected at step 101, it is determined whether or not the map area has moved between the previous control routine and the current control routine. The If it is determined in step 101 that the map area has not moved, the control routine is terminated.

  On the other hand, if it is determined in step 101 that the map area has moved, that is, the engine speed NE and the intake valve opening timing VVT have left the map area in the previous control routine (hereinafter referred to as “previous map area”). If it is determined that the process has been performed, the process proceeds to step 103. In step 103, the above equation (19) is satisfied based on the actual measured value Pmr of the intake pipe pressure when the engine speed NE and the intake valve opening timing VVT are within the immediately preceding map region, the throttle passage air flow rate mt, and the like. An error rate α is calculated. Next, at step 104, the engine speed NE and the intake valve opening timing VVT corresponding to the immediately preceding map area, and the intake pipe pressure when the engine speed NE and the intake valve opening timing VVT are in the immediately preceding map area. The modeled approximate error rate β is calculated using the map shown in FIG. 15B based on the average value of the actual measurement values Pmr. Next, at step 105, a value obtained by dividing the adaptive error rate α by the modeled approximate error rate β is set as a corrected error rate γ (γ = α / β).

In step 106, the current adaptation value modified error ratio γ calculated in step _{105 a 1, a 2, b} 1, b new adaptation value obtained by multiplying the _{2 a 1, a 2, b} 1, b 2 (A ₁ = γ · a ₁ , a ₂ = γ · a ₂ , b ₁ = γ · b ₁ , b ₂ = γ · b ₂ ).

In the above embodiment, the correction values a ₁ , a ₂ , b ₁ , and b ₂ of the intake valve model M30 are corrected based on the modeled approximation error Errm included in the adaptation error Erra. The adaptive error rate α divided by the modeled approximate error rate β is multiplied by the adaptive values a ₁ , a ₂ , b ₁ , and b ₂ of the intake valve model M30. However, the method of removing the modeling approximation error Errm from the fitting error Erra is not limited to the above method, and for example, the following method may be used.

  That is, in the above embodiment, the modeled approximation error rate β is used to remove the modeled approximation error Errm, but a modeled approximation error amount β ′ may be used instead. Here, the modeling approximate error amount β ′ is modeled so that the relationship between the intake pipe pressure Pm and the cylinder intake air flow rate mc in the intake valve model M30 is approximated by two straight lines represented by the above equation (23). As a result, an error amount generated with respect to the relationship between the actual intake pipe pressure and the cylinder intake air flow rate is represented (that is, the error amount between the alternate long and short dash line B and the broken line C in FIG. 14 is represented. ) This modeled approximate error amount β ′ is obtained as a map obtained by experiment or calculation for each engine speed NE, intake valve opening timing VVT, etc. after the intake valve model M30 is created, similarly to the modeled approximate error rate β. It is stored in the ROM 34 of the ECU 31.

During the operation of the internal combustion engine, an adaptation error rate α is calculated at an arbitrary intake pipe pressure Pm (hereinafter, the case where the intake pipe pressure is Pm ₂ ), and the arbitrary intake pipe pressure Pm ₂ is calculated. Based on this, the in-cylinder intake air flow rate mc ₂ is calculated by the equation (23) using a ₁ , a ₂ , b ₁ , b ₂ before correction (mc ₂ = a ₂ · Pm ₂ + b ₂ ). Further, an actual in-cylinder intake air flow rate mc ₂ ′ corresponding to the intake pipe pressure Pm ₂ is calculated based on the adaptation error rate α and the in-cylinder intake air flow rate mc ₂ (mc ₂ ′ = α · mc ₂ ). .

On the other hand, since the modeling approximation error amount β ′ represents the error amount of the broken line C with respect to the alternate long and short dash line B in FIGS. 14 and 15 as described above, the modeling approximation corresponding to the arbitrary intake pipe pressure Pm ₂ described above. The error amount β ′ matches the relationship between the actual in-cylinder intake air flow rate mc ₂ ′ at the arbitrary intake pipe internal pressure Pm ₂ and the corrected target intake pipe internal pressure and in-cylinder intake air flow rate. modified adaptation values _{a 1 ', a 2',} b 1 ', b 2' formula with (23) by any of the above intake pipe pressure Pm ₂ cylinder intake air flow rate mc ₂ calculated based on ' It represents the difference with '. Therefore, the cylinder intake air flow rate mc ₂ ″ is obtained by subtracting the modeling approximate error amount β ′ from the actual cylinder intake air flow rate mc ₂ ′ calculated as described above (mc ₂ ′). '= Mc ₂ ' -β ').

Here, the modified error rate gamma 'is, mc ₂ as described above' to be equal to '/ mc _2, expressed as the following equation (26). When this is expressed in a generalized form with respect to an arbitrary intake pipe pressure Pm, the following expression (27) is obtained. Then, a new adaptation value is obtained by multiplying the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ before correction by the correction error rate γ ′ (a ₁ ′ = γ ′ · a ₁ , a ₂ ′ = γ ′ · a ₂ , b ₁ ′ = γ ′ · b ₁ , b ₂ ′ = γ ′ · b ₂ ). In this way, the modeling approximation error Errm included in the adaptation error Erra may be removed, and the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ of the intake valve model M30 may be corrected based on the modeling approximation error Errm.

Next, a modified example of the above embodiment will be described. In the above embodiment, after the correction error rate γ is calculated, the correction error rate γ is multiplied by the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ to correct these adaptation values at the same rate. However, not only when the matching values a ₁ , a ₂ , b ₁ , and b ₂ have the same level of error, but also when the error only in the matching value a ₁ is large, or the error only in the matching value b ₁ There is also a large case. Therefore, in order to correct the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ accurately, the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ are not corrected at the same rate, but the respective adaptation values a ₁ , A ₂ , b ₁ , b ₂ must be corrected.

Therefore, in the present modification, the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ are individually corrected based on the correction error rate γ calculated as described above. In this modified example, first, when the engine speed NE and the intake valve opening timing VVT are in a certain map region, the correction error rate γ (or the correction error rate γ ′) is calculated and the correction error rate α The average value Pmave of the intake pipe pressure Pm during the integration period in the calculation of the engine, that is, the period during which the engine speed NE and the intake valve opening timing VVT are in the map region is calculated. For convenience, the correction error rate and the average value of the intake pipe pressure calculated in this way are denoted by γ ₁ and Pm ₁ , respectively. Thereafter, when the engine speed NE and the intake valve opening timing VVT are within the map region, the correction error rate γ and the average value Pmave of the intake pipe pressure are calculated again as described above. For convenience, the correction error rate and the average value of the intake pipe pressure calculated in this way are denoted by γ ₂ and Pm ₂ , respectively. Similarly, the correction error rate γ and the average value Pmave of the intake pipe pressure are further calculated twice, and the correction error rate and the average value of the intake pipe pressure thus calculated are respectively expressed as γ ₃ , Pm ₃ and γ _4. , Pm ₄ . Pm ₁ and Pm ₂ are less than Pmk, and Pm ₃ and Pm ₄ are Pmk or more.

FIG. 17 is a graph showing the relationship between the intake pipe pressure Pm and the cylinder intake air flow rate mc when the engine speed NE and the intake valve opening timing VVT are in the map region. The relationship between the in-cylinder intake air flow rate mc and the intake pipe internal pressure Pm represented by the equation (23) of the intake valve model M30 before the adaptive values a ₁ , a ₂ , b ₁ , b ₂ are corrected is shown in FIG. The relationship indicated by a solid line in FIG.

Here, γ ₁ · (a ₁ · Pm ₁ + b ₁ ) calculated using the corrected error rate γ ₁ and the intake pipe pressure Pm ₁ calculated as described above is when the intake pipe pressure is Pm _1. It represents the cylinder intake air flow rate of the corrected target, also modified error rate γ _2, γ _3, γ ₄ and the intake pipe pressure _{Pm 2, Pm 3, Pm 4} γ 2 · is calculated using (a ₁ · Pm ₂ + b ₁ ), γ ₃ · (a ₂ · Pm ₃ + b ₂ ), γ ₄ · (a ₂ · Pm ₄ + b ₂ ) are the values when the intake pipe pressure is Pm ₂ , Pm ₃ , Pm ₄ It accurately represents the actual in-cylinder intake air flow rate. From this, the point (Pm ₁ , γ ₁ · (a ₂ · Pm ₁ + b ₂ )), point (Pm ₂ , γ ₂ · (a ₂ · Pm ₂ + b ₂ )), point (Pm ₃ , γ ₃ · (A ₁ · Pm ₃ + b ₁ )) and the point (Pm ₄ , γ ₄ · (a ₁ · Pm ₄ + b ₁ )) are straight lines (broken lines in FIG. 17) are the corrected target intake pipe pressure and in-cylinder This is considered to be consistent with the relationship with the intake air flow rate. Therefore, by correcting the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ so that the two straight lines represented by the equation (23) using the modified adaptation values pass through the four points, the intake valve model The relationship between the intake pipe pressure and the in-cylinder intake air flow rate represented by the equation (23) of M30 can be made to almost exactly match the relationship between the correction target intake pipe internal pressure and the in-cylinder intake air flow rate.

Therefore, in the present embodiment, using the correction error rates γ ₁ , γ ₂ , γ ₃ , γ ₄ and the intake pipe pressures Pm ₁ , Pm ₂ , Pm ₃ , Pm _{4 described above} , 29), the adaptive values a ₁ , a ₂ , b ₁ , and b ₂ are corrected by the equations (30) and (31). In these equations (28), (29), (30), and (31), the conforming values a ₁ ′, a ₂ ′, b ₁ ′, and b ₂ ′ indicate the conforming values after correction, respectively. ing.

In this way, by adjusting the adaptation values a ₁ , a ₂ , b ₁ , b ₂ , the adaptation values a ₁ , a ₂ , b ₁ , b ₂ can be individually corrected. The relationship between the intake pipe pressure and the cylinder intake air flow rate expressed by the equation (23) using the values a ₁ , a ₂ , b ₁ , and b ₂ is expressed as follows: It becomes possible to match the relationship of the above almost accurately.

In this embodiment, the correction error rate γ is calculated for four different intake pipe pressures (Pm _{1 to} Pm ₄ ). However, if these are four or more, the correction error rate is set for any number of intake pipe pressures Pm. γ may be calculated. In addition, at least two of these intake pipe pressures Pm _{1 to} Pm ₄ need to be less than Pmk, and at least two must be Pmk or more.

  Next, an internal combustion engine control apparatus according to a second embodiment of the present invention will be described. When the relationship between the intake pipe pressure Pm and the in-cylinder intake air flow rate is approximated by two straight lines as shown in equation (23) as shown by the solid line in FIG. In the region X), the modeling approximation error Errm between the in-cylinder intake air flow rate calculated by the equation (23) and the actual in-cylinder intake air flow rate is large, and although not shown in FIG. The modeling approximation error Errm is also large in a region where the pressure is large (region Y in the figure). Further, in these regions, the modeling approximation error Errm greatly fluctuates even if the intake pipe pressure slightly shifts. For this reason, even if the modeling approximation error Errm is removed as described above, the model calculation formula may not be appropriately corrected in these regions (that is, the regions X and Y).

  Therefore, in this embodiment, the modeling approximation error with respect to the amount of change in the intake pipe pressure in the engine operating region where the modeling approximation error Errm is equal to or greater than a predetermined error or the map of the modeling approximation error rate β and the modeling approximation error amount β ′. In an engine operating region (hereinafter referred to as “correction prohibited region”) in which the amount of change in the rate β and the modeling approximate error amount β ′ (hereinafter referred to as “modeled approximate error change amount”) is a predetermined amount or more. The model calculation formula is not corrected, and the model calculation formula is corrected only in other engine operation regions (hereinafter referred to as “correction allowable region”). That is, in the map area shown in FIG. 18, the area X and the area Y correspond to the correction prohibited areas, and the model calculation formula is not corrected in these areas. Thereby, according to the present embodiment, the model calculation formula is corrected only when the model calculation formula can be corrected accurately.

  It should be noted that the area where the modeling approximation error Errm is large and the area where the modeling approximation error change is large differ for each map area. Therefore, for example, in the map region where the relationship between the intake pipe pressure and the cylinder intake air flow rate can be approximated by a single straight line, the modeling approximation error Errm is relatively small and the change amount of the modeling approximation error is also small. In most areas, the model formula is corrected. On the other hand, for example, in a map region where the engine speed NE is high and the intake valve opening timing VVT is advanced, a region where the modeling approximation error Errm is large or a region where the modeling approximation error is large is wide ( That is, since the area X and the area Y in FIG. 18 are wide), the model formula is not corrected in a considerable area.

FIG. 19 shows a control routine for a correction operation of the adaptation values a ₁ , a ₂ , b ₁ , and b ₂ used in the model calculation formula (23) of the intake valve model M30 in the control device of the second embodiment of the present invention. It is a flowchart. Each routine is executed by interruption every certain time interval. In the flowchart shown in FIG. 19, steps 121, 122, and 124 to 127 are the same as steps 101 to 106 shown in FIG.

In step 123, when the engine speed NE and the intake valve opening timing VVT corresponding to the previous map area detected in step 121, and the engine speed NE and the intake valve opening timing VVT are in the previous map area. Based on the average value of the actual measured value Pmr of the intake pipe pressure, it is determined whether or not it is the correction allowable region. If it is determined in step 123 that the average values of the engine speed NE, the intake valve opening timing VVT, and the actual measured value Pmr of the intake pipe pressure in the previous map area are not in the correctable area, the control routine is terminated. The adaptation values a ₁ , a ₂ , b ₁ , b ₂ corresponding to the immediately preceding map area are not corrected. On the other hand, if it is determined in step 123 that the average values of the engine speed NE, the intake valve opening timing VVT, and the actual measured value Pmr of the intake pipe pressure in the previous map region are within the correction allowable region, steps 124 to 127 are performed. Then, the adaptation values a ₁ , a ₂ , b ₁ , b ₂ corresponding to the immediately preceding map area are corrected.

  In the above-described embodiment, whether the engine is in the correction allowable region or the correction prohibited region is determined based on whether the engine speed NE and the intake valve opening timing VVT, the engine speed NE and the intake valve opening timing VVT are immediately before. Although it is performed based on the average value of the actually measured value Pmr of the intake pipe pressure when it is in the map region, the operation parameter as a judgment criterion is not limited to these, for example, in addition to these operation parameters, or the intake pipe pressure Instead of the average value of the actual measurement value Pmr, the throttle opening degree TA or the like may be used.

Next, a modified example of the second embodiment of the present invention will be described. In the above embodiment, the output of the intake pipe pressure sensor 40 is used to correct the adaptive values a ₁ , a ₂ , b ₁ , and b ₂ . Further, as described above, the throttle passage air flow rate mt is used in calculating the adaptation error rate α. As a method of obtaining the throttle passage air flow rate mt, there are a method of calculating by the throttle model M10 and a method of directly using the output of the air flow meter 43. Here, in order to accurately calculate the throttle passage air flow rate mt using the throttle model M10, it is necessary to correct the model formula of the throttle model M10 using the output of the air flow meter 43. For this reason, in order to accurately obtain the throttle passage air flow rate mt, the output of the air flow meter 43 is used regardless of which method is used. In other words, in the above-described embodiment, the output of the air flow meter 43 is used to correct the conforming values a ₁ , a ₂ , b ₁ , and b ₂ .

  Here, the detection accuracy of the intake pipe pressure and the intake pipe passage air flow rate by the intake pipe pressure sensor 40 and the air flow meter 43 is not constant in all engine operation regions, and there is an engine operation region with poor detection accuracy. For example, taking the air flow meter 43 as an example, it is known that the detection accuracy is poor when the throttle opening of the throttle valve 19 is large. This is because when the throttle opening is large, a backflow may occur in the intake pipe 16 due to the intake pulsation, but the backflow cannot be detected by the hot-wire air flow meter 43, and the backflow air flow is prevented from flowing forward. This is because the intake pipe passage air flow rate is detected as the air flow.

  Thus, if the detection accuracy of the sensors 40, 43, etc. is poor, if the model formula is corrected using the output of the sensors 40, 43, the model formula cannot be corrected accurately. Therefore, in this modified example, the model calculation formula is not corrected in the engine operation region where the detection accuracy of the intake pipe pressure sensor is lower than the predetermined accuracy. Thereby, according to the present modification, the model calculation formula is corrected only when the model calculation formula can be corrected accurately.

  In the above description, there is a modeling approximation error only when the relationship between the intake pipe pressure and the cylinder intake air flow rate is approximated by two straight lines as shown in Equation (23). The model calculation formula is corrected to eliminate the error. However, there is a slight modeling approximation error even when the relationship between the intake pipe pressure and the cylinder intake air flow rate is approximated by a straight line. In this case as well, the modeling approximation error should be removed as described above. The model calculation formula may be corrected.

It is a figure which shows the whole internal combustion engine carrying the control apparatus of this invention. It is a block diagram of an air model. It is a figure which shows the relationship between a throttle-valve opening degree and a flow coefficient. It is a figure which shows the relationship between a throttle-valve opening degree and opening cross-sectional area. It is a figure which shows function (PHI) (Pm / Pa). It is a figure which shows the basic concept of a throttle model. It is a figure which shows the basic concept of an intake pipe model. It is a figure which shows the basic concept of an intake valve model. It is a figure regarding the definition of the cylinder filling gas amount and the cylinder intake gas amount. It is a figure which shows the map of the values a and b defined based on the engine speed and the intake valve opening timing. 4 is a time chart of intake pipe pressure, engine speed, and intake valve opening timing. It is a time chart of the pressure in an intake pipe. It is the figure which showed the relationship between the pressure in an intake pipe and the in-cylinder intake air flow rate. FIG. 14 is a diagram showing an example of the relationship between the intake pipe pressure and the in-cylinder intake air flow rate, as in FIG. 13. It is the figure which showed the example of the relationship between the pressure in an intake pipe, the in-cylinder intake air flow rate, and the modeling approximation error rate. It is a flowchart which shows correction operation | movement of the conformity value used with the model calculation formula of an intake valve model. It is the figure which showed the relationship between the pressure in an intake pipe and the in-cylinder intake air flow rate. It is a figure for demonstrating the control apparatus of 2nd embodiment of this invention. It is a flowchart which shows the correction operation of the adaptation value used with the model calculation formula of an intake valve model in the control apparatus of 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 5 Combustion chamber 6 Intake valve 7 Intake port 8 Exhaust valve 11 Fuel injection valve 14 Intake branch pipe 15 Surge tank 16 Intake pipe 19 Throttle valve 23 Intake pipe part

Claims (3)

First operation parameter estimation means for detecting or estimating a value of the first operation parameter;
The relationship between the first operating parameter and the second operating parameter is modeled, and the second operating parameter is calculated using a model calculation formula based on the value of the first operating parameter detected or estimated by the first operating parameter estimating means. Second operating parameter estimating means for estimating a value;
An internal combustion engine control device comprising engine control means for controlling the internal combustion engine based on the value of the second operation parameter estimated by the second operation parameter estimation means;
A model correcting means for correcting the model calculation formula of the second operating parameter estimating means;
The model correction means is configured to calculate the second operation parameter estimation means calculated by the second operation parameter estimation means based on the actual value of the second operation parameter corresponding to the predetermined value of the first operation parameter and the predetermined value of the first operation parameter. Based on the correction error obtained by removing the modeling approximation error caused by modeling the relationship between the first operation parameter and the second operation parameter from the fitting error with the estimated value of the two operation parameters, A control device for an internal combustion engine that performs correction.   2. The control device for an internal combustion engine according to claim 1, wherein the model calculation formula is not corrected by the model correction means in an engine operation region where the modeling approximation error is expected to be greater than or equal to a predetermined error.   The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the first operating parameter is an intake pipe internal pressure, and the second operating parameter is an in-cylinder intake air flow rate.

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