JP5362595B2 - Intake air amount parameter calculation device and control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake air amount parameter calculation device of an internal combustion engine, calculating an intake air amount parameter with good accuracy irrespectively of a flow speed level of air passing through a throttle valve, and to provide a control valve of the internal combustion engine, improving control accuracy. <P>SOLUTION: A first target opening degree calculation part 110 of a target opening degree calculation device 100 uses a modeling method of regarding intake air as compressible fluid and regarding the throttle valve 13a as a nozzle and calculates a first target opening degree THN_CMD, and a second target calculation part 120 uses a modeling method of regarding intake air as incompressible fluid and regarding the throttle valve 13a as an orifice and calculates a second target opening degree THO_CMD. Weighted average operation using a weighting coefficient Kt is applied to the first and second target opening degrees THN_CMD, THO_CMD and a target opening degree TH_CMD is calculated. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an internal combustion engine intake air amount parameter calculation device for calculating an intake air amount parameter representing an intake air amount in an internal combustion engine including a throttle valve, and control of the internal combustion engine including the intake air amount parameter calculation device. Relates to the device.

  Conventionally, the present applicant has already proposed an intake air amount parameter calculation device for an internal combustion engine and a control device provided with the intake air amount parameter calculation device described in Patent Document 1. This internal combustion engine includes a throttle valve that changes the flow rate of air flowing in the intake passage (hereinafter referred to as “intake air”). The intake air amount parameter calculation device calculates a target value (hereinafter referred to as “target opening”) TH_CMD of the opening of the throttle valve as an intake air amount parameter representing the flow rate of intake air (hereinafter referred to as “intake air amount”). An atmospheric pressure sensor for detecting the atmospheric pressure PA, an intake air temperature sensor for detecting the intake air temperature TA, an air flow sensor for detecting the flow rate of air flowing in the intake passage as an intake air amount GAIR, and a downstream of the throttle valve An intake pressure sensor for detecting the pressure in the intake passage on the side as the intake pressure PB is provided.

  In the intake air amount parameter calculation device shown in FIG. 9 of Patent Document 1, modeling is performed in which air passing through the throttle valve (hereinafter referred to as “passing air”) is regarded as an incompressible fluid and the throttle valve is regarded as an orifice. Using the technique, the target opening TH_CMD is calculated. First, a target value (hereinafter referred to as “target differential pressure”) PBGA_CMD of a differential pressure PBGA, which is a deviation between the atmospheric pressure PA and the intake pressure PB, is calculated according to the operating state of the engine, and a target value ( GAIR_CMD (hereinafter referred to as “target intake air amount”) is calculated according to the operating state of the engine, and the effective intake air amount Qe is calculated according to the target intake air amount GAIR_CMD and the intake air amount GAIR.

  Further, a basic value Abase of an effective opening area A between the throttle valve and the intake passage is calculated according to the effective intake air amount Qe, and the basic value Abase is calculated based on the intake air temperature TA, the atmospheric pressure PA, and the target differential pressure PBGA. The effective opening area A is calculated by correcting according to the above. Further, the viscosity coefficient μ is calculated according to the intake air temperature TA, the number of ray nozzles Re is calculated according to the viscosity coefficient μ, the inner diameter D of the intake passage and the opening area A0 of the intake passage, and the number of ray nozzles Re, The correction coefficient Kc is calculated according to the ratio m between the effective opening area A and the opening area A0. Then, the corrected opening area A2 is calculated by correcting the effective opening area A with the correction coefficient Kc, and the target opening TH_CMD is calculated according to the value (A2 + ΔA) obtained by correcting the corrected opening area A2 with the feedback correction term ΔA. The

  Further, in the control device for the internal combustion engine, the intake air amount GAIR is controlled to be the target intake air amount GAIR_CMD by controlling the opening of the throttle valve using the target opening TH_CMD calculated as described above. .

JP 2008-196474 A

  According to the above-described conventional intake air amount parameter calculation device, the target opening degree TH_CMD is calculated using the modeling method in which the passing air is regarded as an incompressible fluid and the throttle valve is regarded as an orifice. In the calculation result of TH_CMD, high calculation accuracy can be secured in the region where the flow velocity of the passing air is low, but in the region where the flow velocity of the passing air is high, the influence of the compressibility of the passing air becomes larger compared to the low region , The calculation accuracy tends to decrease. In addition, when the opening degree of the throttle valve is controlled using the target opening degree TH_CMD having such a reduced calculation accuracy, the control accuracy is lowered.

  The present invention has been made to solve the above problems, and can calculate an intake air amount parameter of an internal combustion engine that can accurately calculate an intake air amount parameter regardless of the flow rate of air passing through the throttle valve. It is an object of the present invention to provide an internal combustion engine control device that can improve the control accuracy of the device.

  In order to achieve the above object, the invention according to claim 1 is directed to an intake air amount parameter (target) representing an intake air amount in an internal combustion engine 3 in which the intake air amount is changed by a throttle valve 13a provided in the intake passage 12. An intake air amount parameter calculation device (ECU 2, target opening calculation device 100, intake air amount calculation device 200) of the internal combustion engine 3 for calculating an opening degree TH_CMD and an intake air amount GAIR) on the upstream side of the throttle valve 13a. An upstream pressure detection means (atmospheric pressure sensor 23) for detecting the pressure in the intake passage 12 as an upstream pressure (atmospheric pressure PA), and the pressure in the intake passage 12 on the downstream side of the throttle valve 13a is set as a downstream pressure (intake). The downstream pressure detecting means (intake pressure sensor 25) for detecting the pressure PBA), and the air in the intake passage 12 is regarded as a compressible fluid and is A first intake air amount parameter calculating means (ECU2, first intake air amount parameter calculating means) for calculating a first intake air amount parameter (first target opening THN_CMD, first intake air amount GAIR_N) using a modeling method in which the valve 13a is regarded as a nozzle. Using the target opening degree calculation unit 110, the first intake air amount calculation unit 210), and a modeling technique that regards the air in the intake passage 12 as an incompressible fluid and the throttle valve 13a as an orifice, Second intake air amount parameter calculation means (ECU 2, second target opening calculation unit 120, second intake air amount calculation unit 220) for calculating parameters (second target opening THO_CMD, second intake air amount GAIR_O); When pressure ratios R_P and R_Pg, which are ratios between the detected downstream pressure and the detected upstream pressure, are in the first predetermined range (R_P ≦ R_P1, When _Pg ≦ R_P1g, the intake air amount parameter is set to the calculated first intake air amount parameter, and when the pressure ratios R_P and R_Pg are in the second predetermined region that is larger than the first predetermined region (R_P2) ≦ R_P, R_Pg2 ≦ R_Pg), the intake air amount parameter setting means (ECU2, target opening degree calculation device 100, intake air amount calculation device) that sets the intake air amount parameter to the calculated second intake air amount parameter 200).

  According to this intake air amount parameter calculation device for an internal combustion engine, the first intake air amount parameter is calculated using a modeling technique that regards the air in the intake passage as a compressive fluid and the throttle valve as a nozzle. In the case of the first intake air amount parameter, good calculation accuracy can be secured in a region where the flow rate of air passing through the throttle valve (hereinafter referred to as “passing air”) is high, but in a region where the flow rate of passing air is low, a high region. Compared to the above, the influence of the detection error of the downstream pressure detection means is increased, and thus the calculation accuracy is easily lowered. On the other hand, since the second intake air amount parameter is calculated using a modeling technique in which intake air is regarded as an incompressible fluid and the throttle valve is regarded as an orifice, in the case of the second intake air amount parameter, the flow velocity of the passing air is Although it is possible to ensure good calculation accuracy in the low region, it has characteristics that the calculation accuracy is easy in the region where the flow velocity of the passing air is high, because the influence of air compressibility is greater than in the low region. Yes. For the above reasons, in the region where the flow velocity of the passing air is high, the calculation accuracy of the first intake air amount parameter exceeds the calculation accuracy of the second intake air amount parameter, while in the region where the flow velocity of the passing air is low. Thus, the calculation accuracy of the second intake air amount parameter exceeds the calculation accuracy of the first intake air amount parameter.

  Therefore, according to the intake air amount parameter calculation apparatus for an internal combustion engine, when the pressure ratio is in the first predetermined range, the intake air amount parameter is set to the first intake air amount parameter, and the pressure ratio is set to be less than the first predetermined range. Is larger than the first predetermined region, that is, in the second predetermined region where the flow velocity of the passing air is lower than the first predetermined region, the intake air amount parameter is set to the second intake air amount parameter. The intake air amount parameter can be set to the one having the higher calculation accuracy of the first intake air amount parameter and the second intake air amount parameter in accordance with the height of the first intake air amount parameter. As a result, the intake air amount parameter can be calculated with higher accuracy than before, regardless of the flow velocity of the passing air.

  The invention according to claim 2 is the first intake air amount parameter calculation in the intake air amount parameter calculation device (ECU 2, target opening degree calculation device 100, intake air amount calculation device 200) of the internal combustion engine 3 according to claim 1. The means uses a pressure ratio function (flow rate function Ψ, Ψg) in the calculation method of the first intake air amount parameter derived using the modeling technique, and the pressure ratio function is theoretically the first predetermined region. It is a region that is equal to or less than a predetermined value R_P1, R_Pg1 of the pressure ratio when the local maximum values Ψmax, Ψgmax are shown.

  As will be described later, when a calculation method for the intake air amount parameter representing the intake air amount is derived using a modeling method in which the passing air is regarded as a compressive fluid and the throttle valve is regarded as a nozzle, the calculation method is calculated based on the pressure ratio. Function is used. In the case of such a function of the pressure ratio, a theoretical maximum value is shown with respect to the change in the pressure ratio, and in the region where the pressure ratio is equal to or less than a predetermined value when the maximum value is exhibited, the flow velocity of the passing air is the sound speed. By exceeding, the value of the function of the pressure ratio does not change from the maximum value and becomes constant (see FIGS. 9 and 22 described later). Therefore, according to the intake air amount parameter calculation device for the internal combustion engine, the first predetermined region is set to a region equal to or smaller than the predetermined value of the pressure ratio when the pressure ratio function theoretically shows the maximum value. The first intake air amount parameter can be calculated only in the region where the function of the pressure ratio is held at the maximum value, and the calculation accuracy can be maintained at a high level.

  The invention according to claim 3 is the intake air amount parameter calculation device (ECU 2, target opening degree calculation device 100, intake air amount calculation device 200) of the internal combustion engine 3 according to claim 1 or 2, wherein the first predetermined range and The second predetermined area is set so as not to overlap with each other, and the intake air amount parameter setting means has the pressure ratio R_P, R_Pg between the first predetermined area and the second predetermined area (R_P1 <R_P <R_P2). , R_P1 <R_P <R_P2), the weighting coefficients Kt and Kg are calculated based on the pressure ratios R_P and R_Pg, and the weighted average calculation using the intake air amount parameter and the weighting coefficients Kt and Kg is performed in the first suction. It is set to the value given to the air quantity parameter and the 2nd intake air quantity parameter.

  According to the intake air amount parameter calculation device for an internal combustion engine, when the pressure ratio is between the first predetermined region and the second predetermined region, the weighting coefficient is calculated based on the pressure ratio, and the intake air amount parameter is Since the weighted average calculation using the weighting coefficient is set to the value obtained by performing the first intake air amount parameter and the second intake air amount parameter, the intake air amount parameter is set to the first intake air amount parameter and the second intake air amount. Unlike the case of switching directly from one of the parameters to the other, it is possible to avoid a sudden change in the intake air amount parameter accompanying a change in the pressure ratio.

  According to a fourth aspect of the present invention, there is provided an intake air amount parameter calculation device (ECU 2, target opening degree calculation device 100, intake air amount calculation device 200) of the internal combustion engine 3 according to any one of the first to third aspects. 3 includes a variable lift mechanism 40 that changes the intake lift LIFT, which is the maximum lift of the intake valve 4, and the first intake air amount parameter corresponds to one of the intake air amount GAIR and the opening TH of the throttle valve 13a. The first intake air amount parameter calculation means represents the other of the intake air amount GAIR and the opening degree TH of the throttle valve 13a in the first intake air amount parameter calculation method derived using the modeling method. When the values (intake air amount GAIR, opening degree function FTH) are used as independent variables, and the intake lift LIFT is not more than a predetermined value LIFT1 , Depending on the intake lift LIFT and the upstream pressure (atmospheric pressure PA), the correction means (ECU 2, the atmospheric pressure correction coefficient calculation unit 140 and 240) for correcting the first intake air amount parameter, characterized in that it comprises a.

  When the internal combustion engine includes a variable lift mechanism that changes the intake lift that is the maximum lift of the intake valve, as shown in FIG. 12 described later, the correlation between the intake air amount and the opening of the throttle valve is In the region where the intake lift is large, when the intake lift and the upstream pressure change, the influence is not so much, whereas in the region where the intake lift is small, when the intake lift and the upstream pressure change, It has been confirmed by the applicant's experiment that a large deviation occurs. Therefore, when the value representing the other of the intake air amount and the opening of the throttle valve is used as an independent variable in the first intake air amount parameter calculation method as in the intake air amount parameter calculation device of the internal combustion engine, In the region where the lift is small, when the intake lift and the upstream pressure change, the correlation between the intake air amount and the opening of the throttle valve changes, so that the calculation accuracy of the first intake air amount parameter decreases. There is a fear. On the other hand, according to the intake air amount parameter calculation device for the internal combustion engine, when the intake lift is equal to or less than a predetermined value, the first intake air amount parameter is corrected according to the intake lift and the upstream pressure. Even when the intake lift and the upstream pressure change in a region where the intake lift is small, the first intake air amount parameter can be accurately calculated while suppressing the influence thereof.

  A control device 1 for an internal combustion engine 3 according to a fifth aspect includes the intake air amount parameter calculation device (ECU 2, target opening degree calculation device 100) for the internal combustion engine 3 according to any one of the first to fourth aspects. The amount parameter calculation device calculates a target opening TH_CMD that is a target of the opening of the throttle valve 13a as an intake air amount parameter (step 5), and controls the internal combustion engine 3 using the calculated target opening TH_CMD. It is further characterized by further comprising first control means (ECU2, step 8).

  According to the control device for an internal combustion engine, as described above, the target opening degree that is the target of the opening degree of the throttle valve can be accurately calculated regardless of the flow rate of the passing air. By controlling the internal combustion engine using the target opening, high control accuracy can be ensured.

  A control device 1A for an internal combustion engine 3 according to a sixth aspect includes the intake air amount parameter calculation device (ECU 2, intake air amount calculation device 200) for the internal combustion engine 3 according to any one of the first to fourth aspects. The amount parameter calculating device calculates the intake air amount GAIR as the intake air amount parameter (step 10), and uses the calculated intake air amount GAIR to control the internal combustion engine 3 (ECU 2, step 13). , 14).

  According to this control device for an internal combustion engine, as described above, the intake air amount can be accurately calculated regardless of the flow rate of the passing air. Therefore, the internal combustion engine is controlled using such intake air amount. By controlling, high control accuracy can be ensured.

It is a figure showing a schematic structure of an internal-combustion engine to which a control device provided with an intake air amount parameter calculation device concerning a 1st embodiment of the present invention is applied. It is a block diagram which shows schematic structure of a control apparatus. It is a schematic diagram which shows schematic structure of an intake side valve mechanism. It is a figure which shows the change state of the intake lift by a variable lift mechanism. The valve lift curve of the intake valve and the valve lift curve of the exhaust valve when the cam phase is set to the most retarded value (solid line) and the most advanced angle value (two-dot chain line) by the variable cam phase mechanism are shown, respectively. FIG. It is a block diagram which shows schematic structure of the target opening calculation apparatus. It is a figure which shows an example of the map used for calculation of the weighting coefficient Kt. It is a block diagram which shows schematic structure of a 1st target opening calculation part. It is a figure which shows an example of the map used for calculation of flow function Ψ. It is a figure which shows an example of the map used for calculation of reference | standard opening degree THN_BASE. It is a figure which shows an example of the map used for calculation of the atmospheric pressure correction coefficient KPA. It is a figure which shows the relationship between the throttle valve opening degree TH, the measured value of the intake air amount GAIR, and the correction value when the intake lift LIFT is changed in the low lift region under the condition where the atmospheric pressure PA is low. It is a block diagram which shows schematic structure of a 2nd target opening calculation part. It is a figure which shows an example of the map used for calculation of reference | standard opening area A1_BASE. It is a figure which shows an example of the map used for calculation of viscosity coefficient (micro | micron | mu). It is a figure which shows an example of the map used for calculation of the 2nd correction coefficient K2. It is a figure which shows an example of the map used for calculation of 2nd target opening degree THO_CMD. It is a flowchart which shows the intake air amount control process by the control apparatus of 1st Embodiment. It is a block diagram which shows schematic structure of the intake air amount calculation apparatus in the control apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the map used for calculation of the weighting coefficient Kg. It is a block diagram which shows schematic structure of a 1st intake air amount calculation part. It is a figure which shows an example of the map used for calculation of flow function Ψg. It is a figure which shows an example of the map used for calculation of the opening degree function FTH. It is a figure which shows an example of the map used for calculation of atmospheric pressure correction coefficient KPA2. It is a block diagram which shows schematic structure of a 2nd intake air amount calculation part. It is a figure which shows an example of the map used for calculation of opening area Ath. It is a figure which shows an example of the map used for calculation of 2nd reference | standard air amount GAIR_O_BASE. It is a figure which shows an example of the map used for calculation of the 2nd correction coefficient K2g. It is a flowchart which shows the fuel-injection control process by the control apparatus of 2nd Embodiment.

  Hereinafter, an intake air amount parameter calculation device and a control device for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, the control device 1 includes an ECU 2, and the ECU 2, as will be described later, according to the operating state of the internal combustion engine (hereinafter referred to as “engine”) 3, will be described later. Various control processes such as a control process are executed.

  As shown in FIG. 1, the engine 3 is an in-line four-cylinder gasoline engine having four sets of cylinders 3a and pistons 3b (only one set is shown), and is mounted on a vehicle (not shown). The engine 3 includes a pair of intake valves 4 and 4 (only one is shown) and a pair of exhaust valves 7 and 7 (only one is shown), an intake camshaft 5 and an intake cam 6 provided for each cylinder 3a. An intake side valve mechanism 30 that opens and closes each intake valve 4, an exhaust side valve mechanism 70 that includes the exhaust camshaft 8 and the exhaust cam 9 and drives each exhaust valve 7 to open and close, and a fuel injection valve 10 ( Etc.).

  Each of the intake camshaft 5 and the exhaust camshaft 8 is rotatably attached to the cylinder head 3c via a holder (not shown) and extends along the arrangement direction of the cylinders 3a. An intake sprocket (not shown) is coaxially disposed on one end of the intake camshaft 5 and is rotatably provided. The intake sprocket is connected to the crankshaft 3d via a timing chain (not shown), and is connected to the intake camshaft 5 via a variable cam phase mechanism 60 described later. With the above configuration, the intake camshaft 5 rotates once every time the crankshaft 3d rotates twice. The intake cam 6 is provided on the intake camshaft 5 so as to rotate integrally therewith.

  Further, the intake side valve mechanism 30 is configured to open and close the intake valve 4 of each cylinder 3a against the urging force of the return spring 4a by the rotation of the intake camshaft 5 accompanying the rotation of the crankshaft 3d. As will be described later, the intake lift LIFT, which is the maximum lift during the opening of the intake valve 4, is changed steplessly and the valve timing of the intake valve 4 is changed steplessly. ing.

  On the other hand, the exhaust-side valve mechanism 70 opens and closes the exhaust valve 7 of each cylinder 3a against the urging force of the return spring 7a by the rotation of the exhaust camshaft 8 accompanying the rotation of the crankshaft 3d. Thus, during the exhaust stroke, the exhaust valve 7 is opened, and the combustion gas is discharged from the cylinder 3a to the exhaust passage 14.

  On the other hand, the fuel injection valve 10 is provided for each cylinder 3a, and is attached to the cylinder head 3c so as to inject fuel directly into the cylinder 3a. That is, the engine 3 is configured as a direct injection engine. The fuel injection valve 10 is electrically connected to the ECU 2, and the valve opening time and valve opening timing are controlled by the ECU 2. That is, the fuel injection amount and the injection timing are controlled.

  Further, the engine 3 is provided with a crank angle sensor 20. The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3d rotates.

  The CRK signal is output at one pulse every predetermined crank angle (for example, 1 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly ahead of the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle.

  On the other hand, a throttle valve mechanism 13 is provided in the intake passage 12 of the engine 3, and this throttle valve mechanism 13 includes a throttle valve 13 a and a TH actuator 13 b that opens and closes the throttle valve 13 a. The throttle valve 13a is rotatably provided in the intake passage 12, and changes the flow rate of the air flowing through the intake passage 12 by the change in the opening degree accompanying the rotation. The TH actuator 13b is a combination of a motor connected to the ECU 2 and a gear mechanism (both not shown). The TH actuator 13b is driven by a control input signal from the ECU 2 so that the opening degree of the throttle valve 13a (hereinafter, “ TH) is changed. In the following description, the air flowing through the intake passage 12 is referred to as “intake air”.

  Next, the intake side valve mechanism 30 described above will be described with reference to FIG. As shown in the figure, the intake side valve mechanism 30 includes an intake camshaft 5, an intake cam 6, a variable lift mechanism 40, a variable cam phase mechanism 60, and the like.

  The variable lift mechanism 40 opens and closes the intake valve 4 by the rotation of the intake camshaft 5 accompanying the rotation of the crankshaft 3d, and the intake lift LIFT is not between the minimum value LIFT_min and the maximum value LIFT_max shown in FIG. It is to change to the stage. Specifically, the variable lift mechanism 40 is configured in the same manner as the one proposed by the present applicant in Japanese Patent Application Laid-Open No. 2007-10052, etc., and the outline thereof will be briefly described below.

  The variable lift mechanism 40 includes a control shaft 41 and a rocker arm shaft 42, a rocker arm mechanism 43 provided on the shafts 41 and 42 for each cylinder 3a, and a lift actuator 50 (FIG. 2), a rotation restricting mechanism (not shown), and the like.

  The rocker arm mechanism 43 includes a link 44a, a roller shaft 44b, a roller 44c, a rocker arm 45, and the like. The lift actuator 50 is a combination of a motor and a reduction gear mechanism (both not shown), and is electrically connected to the ECU 2. When the lift actuator 50 is driven by a control input signal from the ECU 2, the control is performed. The shaft 41 is rotated, thereby rotating the link 44a about the roller shaft 44b.

  When the link 44a is in the zero lift position indicated by the solid line in FIG. 3, when the intake cam 6 rotates and the roller nose 44c is pushed toward the rocker arm shaft 42 by the cam nose, the link 44a is centered on the control shaft 41 as shown in FIG. Rotate clockwise. At this time, the guide surface 45a of the rocker arm 45 has a shape that coincides with an arc centered on the control shaft 41. Therefore, the rocker arm 45 is brought into the closed position shown in FIG. 3 by the urging force of the return spring 4a. Retained. As a result, the intake lift LIFT is held at the value 0, and the intake valve 4 is held in the closed state.

  On the other hand, when the link 44a is rotated from the zero lift position to the maximum lift position (position indicated by the two-dot chain line in FIG. 3) and held at that position, the link 44a is rotated by the rotation of the intake cam 6. When pivoting clockwise in FIG. 3 about the control shaft 41, the rocker arm 45 pivots downward from the valve closing position shown in FIG. 3 while resisting the biasing force of the return spring 4a to open the intake valve 4. To do. At that time, the amount of rotation of the rocker arm 45, that is, the intake lift LIFT becomes larger as the link 44a is closer to the maximum lift position. That is, the intake valve 4 opens with a larger lift as the link 44a is closer to the maximum lift position.

  Further, the rotation range of the control shaft 41 is regulated between the maximum lift position described above and the minimum lift position slightly rotated from the zero lift position to the maximum lift position side by the rotation restricting mechanism. It is configured. Thus, during the rotation of the intake cam 6, the intake valve 4 opens according to the valve lift curve shown by the solid line in FIG. 4 when the link 44a is at the maximum lift position, and the intake lift LIFT indicates its maximum value LIFT_max. At the same time, when the link 44a is at the minimum lift position, the valve 44 is opened according to the valve lift curve indicated by the two-dot chain line in FIG. 4, and the intake lift LIFT indicates the minimum value LIFT_min.

  As described above, in the variable lift mechanism 40, the intake lift LIFT is set to the predetermined minimum value LIFT_min by rotating the link 44a between the minimum lift position and the maximum lift position via the lift actuator 50. It is continuously changed between a predetermined maximum value LIFT_max.

  Further, the variable lift mechanism 40 is provided with a rotation angle sensor 21 (see FIG. 2). The rotation angle sensor 21 detects a rotation angle of the control shaft 41, and a detection signal indicating it. Is output to the ECU 2. The ECU 2 calculates the intake lift LIFT based on the detection signal of the rotation angle sensor 21.

  Next, the aforementioned variable cam phase mechanism 60 will be described. The variable cam phase mechanism 60 changes the relative phase (hereinafter referred to as “cam phase”) CAIN of the intake camshaft 5 with respect to the crankshaft 3d steplessly to the advance side or the retard side. It is provided at the end of the shaft 5 on the intake sprocket side.

  Specifically, the variable cam phase mechanism 60 is configured in the same manner as that proposed by the present applicant in Japanese Patent Application Laid-Open No. 2007-10052 and the like. When the cam phase solenoid valve 61 is driven by a control input signal from the ECU 2, the cam phase CAIN is set to a predetermined maximum retardation value and a predetermined maximum advance angle value. Change continuously between. Thereby, the valve timing of the intake valve 4 is changed steplessly between the most retarded timing shown by the solid line in FIG. 5 and the most advanced timing shown by the two-dot chain line in FIG.

  On the other hand, a cam angle sensor 22 (see FIG. 2) is provided at the end of the intake camshaft 5 opposite to the variable cam phase mechanism 60. The cam angle sensor 22 is composed of, for example, a magnet rotor and an MRE pickup, and outputs a CAM signal, which is a pulse signal, to the ECU 2 every predetermined cam angle (for example, 1 °) as the intake camshaft 5 rotates. . The ECU 2 calculates the cam phase CAIN based on the CAM signal and the above-described CRK signal.

  As described above, in the engine 3, the intake lift LIFT can be changed steplessly within a predetermined range by the variable lift mechanism 40, and the valve timing of the intake valve 4 is not changed within the predetermined range by the variable cam phase mechanism 60. It is configured so that it can be changed in stages.

  Further, as shown in FIG. 2, the atmospheric pressure sensor 23, the intake air temperature sensor 24, the intake pressure sensor 25, the throttle valve opening sensor 26, the accelerator opening sensor 27, and the LAF sensor 28 are electrically connected to the ECU 2. ing. The atmospheric pressure sensor 23 is composed of a semiconductor pressure sensor, detects the atmospheric pressure PA, and outputs a detection signal representing it to the ECU 2. This atmospheric pressure PA is detected as an absolute pressure. In the present embodiment, the atmospheric pressure sensor 23 corresponds to the upstream pressure detecting means, and the atmospheric pressure PA corresponds to the upstream pressure.

  The intake air temperature sensor 24 detects the temperature of air in the intake passage 12 (hereinafter referred to as “intake air temperature”) TA, and outputs a detection signal representing the detected temperature to the ECU 2. Further, the intake pressure sensor 25 is constituted by a semiconductor pressure sensor, for example, and detects a pressure PBA (hereinafter referred to as “intake pressure”) PBA in the intake passage 12 on the downstream side of the throttle valve 13a, and a detection signal representing it. Is output to the ECU 2. This intake pressure PBA is detected as an absolute pressure. In the present embodiment, the intake pressure sensor 25 corresponds to the downstream pressure detection means, and the intake pressure PBA corresponds to the downstream pressure.

  On the other hand, the throttle valve opening sensor 26 is composed of a potentiometer, detects the throttle valve opening TH, and outputs a detection signal representing it to the ECU 2. The accelerator opening sensor 27 detects an accelerator opening AP, which is an operation amount of an accelerator pedal (not shown), and outputs a detection signal representing the detected value to the ECU 2. Further, the LAF sensor 28 is provided upstream of the catalyst device in the exhaust passage 14, and in the exhaust passage 14 in a wide range of air-fuel ratios from a rich region richer than the stoichiometric air-fuel ratio to an extremely lean region. The oxygen concentration in the exhaust gas flowing through is detected linearly, and a detection signal representing it is output to the ECU 2.

  The ECU 2 includes a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the engine 2 according to the detection signals of the various sensors 20 to 28 described above. 3 is determined, and various control processes such as an intake air amount control process are executed. In the present embodiment, the ECU 2 includes an intake air amount parameter calculation device, first intake air amount parameter calculation means, second intake air amount parameter calculation means, intake air amount parameter setting means, correction means, and first control means. It corresponds to.

  On the other hand, as shown in FIG. 6, the control device 1 of this embodiment includes a target opening calculation device 100, and the target opening calculation unit 100 is specifically configured by the ECU 2. In the present embodiment, the target opening calculation unit 100 corresponds to an intake air amount parameter calculation device and an intake air amount parameter setting means.

  The target opening calculation device 100 calculates a target opening TH_CMD that is a target of the throttle valve opening TH as an intake air amount parameter. As shown in FIG. , A second target opening calculation unit 120, a weighting coefficient calculation unit 140, amplifiers 141 and 142, and an adder 143.

  As will be described later, the first target opening calculation unit 110 uses a modeling technique in which air passing through the throttle valve 13a (hereinafter referred to as “passing air”) is regarded as a compressible fluid and the throttle valve 13a is regarded as a nozzle. The first target opening THN_CMD is calculated. In the present embodiment, the first target opening degree calculation unit 110 corresponds to the first intake air amount parameter calculation means, and the first target opening degree THN_CMD corresponds to the first intake air amount parameter.

  The second target opening degree calculation unit 120 calculates the second target opening degree THO_CMD using a modeling technique that regards the passing air as an incompressible fluid and the throttle valve 13a as an orifice, as will be described later. . In the present embodiment, the second target opening degree calculation unit 120 corresponds to the second intake air amount parameter calculation means, and the second target opening degree THO_CMD corresponds to the second intake air amount parameter.

  Further, the weighting coefficient calculation unit 140 calculates the ratio between the target intake pressure PBA_CMD and the atmospheric pressure PA as a pressure ratio R_P (= PBA_CMD / PA), and searches the map shown in FIG. 7 according to the pressure ratio R_P. By doing so, the weighting coefficient Kt is calculated. The target intake pressure PBA_CMD is a target value of the intake pressure PBA, and a calculation method thereof will be described later.

  R_P1 and R_P2 in the figure represent predetermined values of the pressure ratio R_P, and are set so that the relationship of R_P1≈0.53 and the relationship of R_P1 <R_P2 are established. As shown in the figure, the weighting coefficient Kt is set to a value of 1.0 in the region of R_P ≦ R_P1, and a value of 0 in the region of R_P2 ≦ R_P, and in the region of R_P1 <R_P <R_P2, It is set to change in proportion to the change in the ratio R_P. The reason why the weighting coefficient Kt is set in this way will be described later.

On the other hand, the amplifiers 141 and 142 calculate values obtained by amplifying the first target opening THN_CMD and the second target opening THO_CMD by Kt and 1−Kt times, respectively. Then, the adder 143 calculates the target opening TH_CMD by the following expression (1) using the value thus amplified. That is, the target opening TH_CMD is calculated by a weighted average calculation of the first and second target opening THN_CMD, THO_CMD.

  As is apparent from the equation (1), when Kt = 1.0, that is, when R_P ≦ R_P1 is established and the flow velocity of the passing air is high, TH_CMD = THN_CMD, and when Kt = 0, In a region where R_P2 ≦ R_P is established and the flow velocity of the passing air is low, TH_CMD = THO_CMD. Further, when 0 <Kt <1, that is, in a region where R_P1 <R_P <R_P2 is established, the weighting degree of the first and second target opening THN_CMD, THO_CMD at the target opening TH_CMD is the weighting coefficient Kt. Determined by value.

  The target opening TH_CMD is calculated as described above for the following reason. That is, in the case of the first target opening THN_CMD, as will be described later, a region where the flow velocity of the passing air is high is calculated using a modeling method in which the passing air is regarded as a compressive fluid and the throttle valve 13a is regarded as a nozzle. However, although it is possible to ensure good calculation accuracy, in the region where the flow velocity of the passing air is low, the influence of the detection error of the intake pressure sensor 25 becomes larger than in the high region, and thus the calculation accuracy tends to be reduced. I have. On the other hand, in the case of the second target opening degree THO_CMD, the relationship is calculated using a modeling method in which the passing air is regarded as an incompressible fluid and the throttle valve 13a is regarded as an orifice. Although the calculation accuracy can be ensured, the region in which the flow velocity of the passing air is high has a characteristic that the calculation accuracy is likely to be lowered due to the influence of the air compressibility, as compared with the low region.

  As a result, the calculation accuracy of the first target opening THN_CMD exceeds the calculation accuracy of the second target opening THO_CMD in the region where the flow velocity of the passing air is high, and the second accuracy is calculated in the region where the flow velocity of the passing air is low. The calculation accuracy of the target opening THO_CMD exceeds the calculation accuracy of the first target opening THN_CMD. Therefore, in a region where the flow velocity of the passing air is high such that R_P ≦ R_P1 is established, the target opening TH_CMD is calculated as the first target opening THN_CMD with higher calculation accuracy than the second target opening THO_CMD, and R_P2 ≦ In a region where the flow rate of the passing air is low such that R_P is established, the target opening TH_CMD is calculated as the second target opening THO_CMD with higher calculation accuracy than the first target opening THN_CMD. Can be calculated with high calculation accuracy regardless of the flow velocity of the passing air.

  When 0 <Kt <1, the degree of weighting of the first and second target openings THN_CMD and THO_CMD at the target opening TH_CMD is determined by the value of the weighting coefficient Kt. This is because when the value of the first and second target openings THN_CMD and THO_CMD is large when the value is directly switched from one of THN_CMD and THO_CMD to the other, the intake air amount GAIR changes suddenly and torque This is because there is a possibility that a level difference will occur, so that it can be avoided. That is, as described above, in the region of R_P1 <R_P <R_P2 where the weighting coefficient Kt is 0 <Kt <1, the weighting coefficient Kt is set to change in proportion to the change in the pressure ratio R_P. When the pressure ratio R_P changes between two predetermined values R_P1 and R_P2, the weighting coefficient Kt gradually changes accordingly, whereby the first and second target openings THN_CMD and THO_CMD at the target opening TH_CMD are weighted. The degree of change will gradually change. As a result, generation of a torque step can be avoided.

  Next, the first target opening calculation unit 110 described above will be described with reference to FIG. As will be described below, the first target opening calculation unit 110 calculates the first target opening THN_CMD using a method of modeling the relationship between the throttle valve 13a and the intake air based on fluid dynamics. As shown in the figure, a flow rate function calculation unit 111, an opening degree function calculation unit 112, a reference opening degree calculation unit 113, an atmospheric pressure correction coefficient calculation unit 114, and a multiplier 115 are provided.

  First, the flow rate function calculation unit 111 calculates a flow rate function Ψ (a function of the pressure ratio) by searching a map shown in FIG. 9 according to the pressure ratio R_P. In this map, the flow rate function ψ is set to a smaller value as the pressure ratio R_P is larger in the region of R_P2 ≦ R_P, and is set to a constant value ψmax in the region of R_P ≦ R_P1. This is due to the following reason.

  That is, the theoretical value of the flow function ψ is a curved value indicated by a solid line in the region of R_P1 ≦ R_P in the same figure, and a curved value indicated by a broken line in the region of R_P ≦ R_P1 in the same figure. In other words, the theoretical value of the flow rate function Ψ is calculated so as to change upward in a convex curve with respect to the pressure ratio R_P, and to show a maximum value Ψmax when R_P = R_P1. However, in the region of R_P ≦ R_P1, the actual value of the flow function Ψ is held at the maximum value Ψmax in the region of R_P ≦ R_P1 because the flow velocity of the air passing through the throttle valve 13a exceeds the sonic speed. Therefore, in the map of FIG. 9, the map value of the flow function Ψ is set to a value indicated by a solid line.

Next, the opening function calculation unit 112 calculates the opening function FTH by the following equation (2).

GAIR_CMD in the above equation (2) is a target intake air amount that is a target of the intake air amount GAIR, and is calculated as described later. R is the gas constant of air. The above equation (2) is derived by the method described below. That is, when the passing air is regarded as a compressive fluid and an adiabatic flow and the throttle valve 13a is regarded as a nozzle, a model equation shown in the following equation (3) is obtained.

In the above equation (3), u is the flow velocity of the passing air, P ₁ and P ₂ are the upstream and downstream pressures of the throttle valve 13a, ρ ₁ is the density of the intake air upstream of the throttle valve 13a, κ Represents the specific heat ratio of the intake air.

Next, when the mass flow rate of the intake air is G, the opening area of the throttle valve 13a is A, the density of the intake air downstream of the throttle valve 13a is ρ ₂ , and the flow coefficient of the throttle valve 13a is Cd, Based on this, the following equation (4) is obtained.

Further, the following equation (5) is established for the isentropic change of the complete gas, and when this equation (5) is modified, the following equation (6) is obtained.

Substituting the above expression (6) into the above-described expression (4) yields the following expression (7).

Here, when terms other than Cd · A on the right side of the above equation (7) are rearranged by substituting the above equation (3), the following equation (8) is obtained.

When the above equation (7) is rewritten using this equation (8), the following equation (9) is obtained.

The density ρ of air is defined by the following equation (10) from the gas state equation PV = GRT.

By substituting the above equation (10) for ρ ₁ and P ₁ for P ₁ into the above equation (9), the following equation (11) is obtained.

Here, the term of the pressure ratio P ₂ / P _{1 in} the above equation (11) is defined as the following equation (12) as a flow function Ψ, and when the above equation (11) is rewritten using this, the following equation ( 13) is obtained.

In the above equation (13), since the opening area A and the flow coefficient Cd are both functions determined by the throttle valve opening TH, the value Cd · A is defined as the opening function FTH (= Cd · A). When the above equation (13) is rewritten using the following equation, the following equation (14) is obtained.

In the above equation (14), the pressure loss on the upstream side of the throttle valve 13a is ignored, the upstream pressure P ₁ is replaced with the atmospheric pressure PA, the mass flow rate G is changed to the intake air amount GAIR, and the temperature T is changed to the atmospheric temperature TA. When each is replaced, the following equation (15) is obtained.

Furthermore, when the above equation (15) is arranged with respect to the opening degree function FTH, the following equation (16) is obtained.

  In the equation (16), when the intake air amount GAIR is replaced with the target intake air amount GAIR_CMD that is the target value, the above-described equation (2) is derived. A method for calculating the target intake air amount GAIR_CMD will be described later.

  On the other hand, the reference opening degree calculation unit 113 calculates the reference opening degree THN_BASE by searching the map shown in FIG. 10 according to the opening degree function FTH. The map of FIG. 10 represents the value of the target opening TH_CMD with respect to the opening function FTH when environmental conditions such as the atmospheric pressure PA, the intake pressure PBA, and the intake air temperature TA are under predetermined reference conditions.

  Further, the atmospheric pressure correction coefficient calculation unit 114 (correction means) calculates the atmospheric pressure correction coefficient KPA by searching the map shown in FIG. 11 according to the intake lift LIFT and the atmospheric pressure PA. In the figure, PA1 to PA3 are predetermined values of the atmospheric pressure PA, and are set so that the relationship PA1 <PA2 <PA3 is established. LIFT1 is a predetermined value of the intake lift LIFT, and is set to a value close to the aforementioned minimum value LIFT_min. As shown in the figure, the atmospheric pressure correction coefficient KPA is set to a value of 1 in the region of LIFT1 ≦ LIFT, and in the region of LIFT <LIFT1, for a reason described later, the lower the atmospheric pressure PA, It is set to a larger value.

Then, the multiplier 115 calculates the first target opening THN_CMD by the following equation (17).

  As described above, in the first target opening calculation unit 110, the first target opening THN_CMD is calculated by correcting the reference opening THN_BASE with the atmospheric pressure correction coefficient KPA. The reason will be described with reference to FIG. LIFT2 and LIFT3 in the figure are predetermined values of the intake lift LIFT, and are set so that LIFT3 <LIFT2 <LIFT1 holds. The curve indicated by the solid line in the figure shows the intake air when the throttle valve opening TH and the intake lift LIFT are changed in a state where the atmospheric pressure PA is lower than that in the above-described reference condition, that is, in a high altitude. The actual measurement value of the quantity GAIR is shown. In addition, the curve indicated by the broken line in the figure shows the intake air amount GAIR when the throttle valve opening TH and the intake lift LIFT are changed in a state where the atmospheric pressure PA is in the above-described reference condition, that is, on a flat ground. Is corrected so as to be a value at an atmospheric pressure PA corresponding to the same altitude as the value of the curve indicated by the solid line.

  As is clear from comparison of these two values, when the intake lift LIFT is at the predetermined value LIFT1, the correction value is almost the same as the actual measurement value by correcting the map value for flat ground according to the atmospheric pressure PA. Although there is no deviation, in the region where the intake lift LIFT is smaller than the predetermined value LIFT1, that is, the low lift region, the smaller the intake lift LIFT, the greater the degree to which the actually measured value falls below the correction value, resulting in a larger deviation. I know that. Therefore, in the present embodiment, the atmospheric pressure correction coefficient KPA is set to the tendency shown in FIG. 11 described above in order to suppress the occurrence of such a shift in the region where the atmospheric pressure PA is low and the intake lift LIFT is small. ing.

  Furthermore, in the case of the first target opening THN_CMD, as described above, the flow rate of the passing air is high because of the relationship calculated using the modeling method in which the passing air is regarded as a compressive fluid and the throttle valve 13a is regarded as a nozzle. Although a high calculation accuracy can be ensured in the region, the calculation accuracy tends to be lowered in the region where the flow velocity of the passing air is low because the influence of the detection error of the intake pressure sensor 25 becomes larger than in the high region. I have.

  Next, the second target opening calculation unit 120 described above will be described with reference to FIG. The second target opening degree calculation unit 120 uses the modeling method in which the passing air is regarded as an incompressible fluid and the throttle valve 13a is regarded as an orifice, as in the above-described Patent Document 1, to calculate the second target opening degree THO_CMD. Is to be calculated.

  As shown in the figure, the second target opening calculation unit 120 includes a reference opening area calculation unit 121, an opening area calculation unit 122, a first correction coefficient calculation unit 123, an opening area ratio calculation unit 124, and a viscosity coefficient calculation unit 125. A ray nozzle number calculating unit 126, a second correction coefficient calculating unit 127, a multiplier 128, and a final value calculating unit 129.

  First, the reference opening area calculation unit 121 calculates a reference opening area A1_BASE by searching a map shown in FIG. 14 according to the target intake air amount GAIR_CMD. This reference opening area A1_BASE represents a reference value of the opening area required to secure the target intake air amount GAIR_CMD when the throttle valve 13a is regarded as an orifice. In this map, the reference opening area A1_BASE is set to a larger value in order to ensure the larger the target intake air amount GAIR_CMD.

Next, the opening area calculation unit 122 calculates the opening area A1 by the following equation (18).

  PBGA_CMD in the above equation (18) is a target differential pressure, and is calculated by subtracting the target intake pressure PBA_CMD from the atmospheric pressure PA. A method for calculating the target intake pressure PBA_CMD will be described later. Further, PBGAbase in the above equation (18) is a predetermined reference differential pressure, and is set to a predetermined constant value of the intake differential pressure PBGA (= PA−PBA).

Further, the first correction coefficient calculation unit 123 calculates the first correction coefficient K1 as shown in the following equation (19). The first correction coefficient K1 is a value for correcting the density of the opening area A1.

  In the above equation (19), Tbase is the reference intake air temperature, and is set to the value of the intake air temperature TA under the reference conditions described above. Pbase is the reference atmospheric pressure, and is set to the value of the atmospheric pressure PA under the reference conditions described above.

  On the other hand, the opening area ratio calculation unit 124 calculates the opening area ratio R_A as the ratio A1 / Ad of the opening area A1 and the passage cross-sectional area Ad of the intake passage 12, and the viscosity coefficient calculation unit 125 determines the intake air temperature TA. Thus, the viscosity coefficient μ of the intake air is calculated by searching the map shown in FIG.

In addition, the ray nozzle number calculation unit 126 calculates the ray nozzle number Re by the following equation (20). In the following formula (20), D represents the inner diameter of the intake passage 12.

  Further, the second correction coefficient calculation unit 127 calculates the second correction coefficient K2 by searching the map shown in FIG. 16 according to the opening area ratio R_A and the number of ray nozzles Re. Re1 to Re3 in the figure are predetermined values of the number of ray nozzles Re, and are set so that the relationship of Re1 <Re2 <Re3 is established.

  As shown in the figure, in this map, the second correction coefficient K2 is set to a larger value as the aperture area ratio R_A is smaller or the number of ray nozzles Re is larger. This is because the smaller the opening area ratio R_A or the greater the number of lay nozzles Re, the more difficult the air flow passes through the throttle valve 13a. Accordingly, the opening area of the throttle valve opening is set to a larger value correspondingly. Because.

On the other hand, the multiplier 128 calculates the corrected opening area A1_MOD by the following equation (21).

  As shown in the above equation (21), the corrected opening area A1_MOD is calculated by correcting the opening area A1 with two correction coefficients K1 and K2.

  Further, the final value calculation unit 129 calculates the second target opening THO_CMD by searching the map shown in FIG. 17 according to the corrected opening area A1_MOD. In this map, the larger the corrected opening area A1_MOD, the larger the second target opening THO_CMD is set in order to secure it.

  As described above, in the case of the second target opening degree THO_CMD, a region in which the flow velocity of the passing air is low due to the relationship calculated using the modeling method in which the passing air is regarded as an incompressible fluid and the throttle valve 13a is regarded as an orifice. However, in the region where the flow velocity of the passing air is high, the influence of the air compressibility becomes larger in the region where the flow velocity of the passing air is high, so that the calculation accuracy is likely to decrease. .

  Next, an intake air amount control process executed by the ECU 2 will be described with reference to FIG. In this control process, the target opening TH_CMD is calculated by the above-described calculation method, and the throttle valve mechanism 13 is controlled using the target opening TH_CMD, and the variable lift mechanism 40 and the variable cam phase mechanism 60 are controlled. And is executed at a predetermined control cycle (for example, 10 msec).

  As shown in the figure, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), a target intake air amount GAIR_CMD is calculated. Specifically, a required torque PM_CMD required for the engine 3 is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP, and the required torque PM_CMD and the engine speed NE are calculated. Accordingly, the target intake air amount GAIR_CMD is calculated by searching a map (not shown).

  Next, the process proceeds to step 2, and after calculating the target cam phase CAIN_CMD according to the target intake air amount GAIR_CMD, at step 3, the target lift LIFT_CMD is calculated according to the target intake air amount GAIR_CMD and the target cam phase CAIN_CMD.

  Next, the process proceeds to step 4, and a target intake pressure PBA_CMD is calculated by searching a map (not shown) according to the target intake air amount GAIR_CMD and the target cam phase CAIN_CMD.

  In step 5 following step 4, the target opening TH_CMD is calculated by the calculation method of the target opening calculation device 100 described above.

  Next, the routine proceeds to step 6 where cam phase control processing is executed. In this control process, a duty ratio of a control input signal to be supplied to the cam phase solenoid valve 61 is calculated by searching a map (not shown) according to the target cam phase CAIN_CMD, and the control input signal thus calculated is calculated. By supplying to the cam phase solenoid valve 61, the cam phase CAIN is controlled to be the target cam phase CAIN_CMD.

  Next, in step 7, an intake lift control process is executed. In this control process, the value of the control input signal to be supplied to the lift actuator 50 is calculated by a predetermined feedback control method using the intake lift LIFT and the target lift LIFT_CMD, and the control input signal thus calculated is used as the lift actuator 50. , The intake lift LIFT is feedback controlled so as to converge to the target lift LIFT_CMD.

  In step 8 following step 7, an opening degree control process is executed. In this control process, a duty ratio of a control input signal to be supplied to the TH actuator 13b is calculated by searching a map (not shown) according to the target opening TH_CMD, and the control input signal thus calculated is used as the TH actuator. By supplying to 13b, the throttle valve opening TH is controlled to be the target opening TH_CMD. As described above, after the opening degree control process of step 8 is executed, this process is terminated.

  As described above, according to the target opening calculation apparatus 100 of the first embodiment, the target opening TH_CMD is calculated by the weighted average arithmetic expression (1) of the first target opening THN_CMD and the second target opening THO_CMD. In addition, the weighting coefficient Kt of the equation (1) is calculated by searching the map of FIG. 7 according to the pressure ratio R_P. Accordingly, in a region where the flow velocity of the passing air is high such that R_P ≦ R_P1 is established, the target opening TH_CMD is calculated as the first target opening THN_CMD and R_P2 ≦ In a region where the flow rate of the passing air is low such that R_P is established, the target opening TH_CMD is calculated as the second target opening THO_CMD by Kt = 0.

  In this case, as described above, in the first target opening THN_CMD and the second target opening THO_CMD, the calculation accuracy of the first target opening THN_CMD is the calculation of the second target opening THO_CMD in the region where the flow rate of the passing air is high. In a region where the accuracy exceeds the accuracy and the flow velocity of the passing air is low, the calculation accuracy of the second target opening THO_CMD is calculated so as to exceed the calculation accuracy of the first target opening THN_CMD. Accordingly, the target opening TH_CMD is calculated as the first target opening THN_CMD in a region where the flow rate of the passing air is high such that R_P ≦ R_P1 is established, and the flow rate of the passing air is low so that R_P2 ≦ R_P is satisfied. By calculating the target opening TH_CMD as the second target opening THO_CMD in the region, the target opening TH_CMD is set to the first target opening THN_CMD and the second target opening THO_CMD according to the flow velocity of the passing air. It can be calculated as one having higher calculation accuracy. As a result, the target opening TH_CMD can be calculated with higher accuracy than before, regardless of the flow rate of the passing air.

  Further, when the pressure ratio R_P is in the region of R_P1 <R_P <R_P2, when the pressure ratio R_P changes between the two predetermined values R_P1 and R_P2, the weighting coefficient Kt gradually changes accordingly, thereby causing the target opening. The degree of weighting of the first and second target openings THN_CMD and THO_CMD at the degree TH_CMD gradually changes. Thereby, unlike the case of switching directly from one of the first target opening THN_CMD and the second target opening THO_CMD to the other, it is possible to avoid a rapid fluctuation of the target opening TH_CMD accompanying the change in the pressure ratio R_P. .

  Further, in the map of FIG. 9, since the flow function Ψ is set to the theoretical maximum value Ψmax in the region of R_P ≦ R_P1, the first target opening degree THN_CMD is held at the maximum value Ψmax. It is possible to calculate only in the region to be performed, and the calculation accuracy can be maintained at a high level.

  In addition, when the intake lift LIFT is equal to or smaller than the predetermined value LIFT1, an atmospheric pressure correction coefficient KPA is calculated according to the intake lift LIFT and the atmospheric pressure PA, and the reference opening THN_BASE is corrected by the atmospheric pressure correction coefficient KPA. Thus, since the first target opening THN_CMD is calculated, even when the intake lift LIFT and the atmospheric pressure PA change in a region where the intake lift LIFT is small, the first target opening THN_CMD is suppressed while suppressing the influence thereof. Can be calculated with high accuracy.

  Further, according to the control device 1 of the first embodiment, since the target opening TH_CMD is calculated with high accuracy as described above, the throttle valve opening TH is controlled using such target opening TH_CMD. Therefore, high control accuracy can be ensured. In addition to this, the target opening TH_CMD is calculated so as to avoid abrupt fluctuations accompanying changes in the pressure ratio R_P, so that the occurrence of a torque step can be avoided.

  The first embodiment is an example in which the target opening TH_CMD is calculated as the intake air amount parameter. However, the intake air amount parameter of the present invention is not limited to this, and the intake air representing the intake air amount is used. What is necessary is just to calculate a quantity parameter. For example, the throttle valve opening TH may be calculated as the intake air amount parameter.

  Moreover, although 1st Embodiment is an example using the control apparatus 1 which controls the throttle valve opening TH using target opening TH_CMD as a control apparatus, the control apparatus of this invention is not restricted to this, A target What is necessary is just to control an internal combustion engine using opening degree TH_CMD. For example, a control device that controls the ignition timing of the internal combustion engine using the target opening TH_CMD may be used.

  Next, an intake air amount parameter calculation device and control device for an internal combustion engine according to a second embodiment of the present invention will be described. In the case of the second embodiment, the mechanical configuration of the internal combustion engine and the electrical configuration of the control device (various sensors 20 to 28 and ECU 2 etc.) are the same as the configuration of the first embodiment described above. Description will be made mainly on points different from 1, and description of the same configuration will be omitted. In the present embodiment, the ECU 2 includes an intake air amount parameter calculation device, first intake air amount parameter calculation means, second intake air amount parameter calculation means, intake air amount parameter setting means, correction means, and second control means. It corresponds to.

  As shown in FIG. 19, the control device 1A of the present embodiment includes an intake air amount calculation device 200 that calculates an intake air amount GAIR. Using the calculated intake air amount GAIR, as described later, The fuel injection control process is executed. In the present embodiment, the intake air amount calculation device 200 corresponds to an intake air amount parameter calculation device and intake air amount parameter setting means.

  As shown in the figure, the intake air amount calculation device 200 includes a first intake air amount calculation unit 210, a second intake air amount calculation unit 220, a weighting coefficient calculation unit 240, amplifiers 241, 242, and an adder 243. Yes.

  First, the first intake air amount calculation unit 210 calculates the first intake air amount GAIR_N using a modeling method in which the passing air is regarded as a compressive fluid and the throttle valve 13a is regarded as a nozzle, as will be described later. In the present embodiment, the first intake air amount calculation unit 210 corresponds to the first intake air amount parameter calculation means, and the first intake air amount GAIR_N corresponds to the first intake air amount parameter.

  Further, the second intake air amount calculation unit 220 calculates the second intake air amount GAIR_O using a modeling technique in which the passing air is regarded as an incompressible fluid and the throttle valve 13a is regarded as an orifice, as will be described later. . In the present embodiment, the second intake air amount calculation unit 220 corresponds to the second intake air amount parameter calculation means, and the second intake air amount GAIR_O corresponds to the second intake air amount parameter.

  Further, the weighting coefficient calculation unit 240 calculates the ratio between the intake pressure PBA and the atmospheric pressure PA as a pressure ratio R_Pg (= PBA / PA), and searches the map shown in FIG. 20 according to the pressure ratio R_Pg. Thus, the weighting coefficient Kg is calculated.

  R_Pg1 and R_Pg2 in the drawing represent predetermined values of the pressure ratio R_Pg, and are set so that the relationship of R_Pg1≈0.53 and the relationship of R_Pg1 <R_Pg2 are established. As shown in the figure, the weighting coefficient Kg is set to a value of 1.0 in the region of R_Pg ≦ R_Pg1, and a value of 0 in the region of R_Pg2 ≦ R_Pg, and in the region of R_Pg1 <R_Pg <R_Pg2, It is set to change in proportion to the change in the ratio R_Pg. The reason why the weighting coefficient Kg is set as described above is the same as the reason for setting the weighting coefficient Kt described above.

On the other hand, the amplifiers 241 and 242 calculate values obtained by amplifying the first intake air amount GAIR_N and the second intake air amount GAIR_O by Kg and 1-Kg times, respectively. Then, the adder 243 calculates the intake air amount GAIR by using the value thus amplified and the weighted average arithmetic expression of the following expression (22).

  As is clear from this equation (22), when Kg = 1.0, that is, when R_Pg ≦ R_Pg1 is established and the flow velocity of the passing air is high, GAIR = GAIR_N, and when Kg = 0, In a region where R_Pg2 ≦ R_Pg is established and the flow velocity of the passing air is low, GAIR = GAIR_O. Further, when 0 <Kg <1, that is, in a region where R_Pg1 <R_Pg <R_Pg2 is established, the degree of weighting of the first and second intake air amounts GAIR_N and GAIR_O in the intake air amount GAIR is determined by the weighting coefficient Kg. Determined by value.

  The reason why the intake air amount GAIR is calculated using the weighted average calculation as described above is the same as the reason why the weighted average calculation is used in the calculation of the target opening TH_CMD described above. That is, the first intake air amount GAIR_N and the second intake air amount GAIR_O are calculated by a calculation method in which the passing air is regarded as a compressible fluid and an incompressible fluid, and thus the flow velocity of the passing air is high. In the region, the calculation accuracy of the first intake air amount GAIR_N exceeds the calculation accuracy of the second intake air amount GAIR_O, and in the region where the flow velocity of the passing air is low, the calculation accuracy of the second intake air amount GAIR_O is the first intake air amount. This will exceed the calculation accuracy of the air amount GAIR_N. Accordingly, in the region of R_Pg ≦ R_Pg1, the intake air amount GAIR is set to the first intake air amount GAIR_N with higher calculation accuracy, and in the region of R_Pg2 ≦ R_Pg, the intake air amount GAIR is set to the second intake air with higher calculation accuracy. This is to ensure good calculation accuracy by setting the amount GAIR_O.

  When 0 <Kg <1, the degree of weighting of the first and second intake air amounts GAIR_N and GAIR_O in the intake air amount GAIR is determined by the value of the weighting coefficient Kg. This is because if the difference between the first and second intake air amounts GAIR_N and GAIR_O is large when one of the GAIR_N and GAIR_O is directly switched to the other, the intake air amount GAIR changes suddenly and torque This is because there is a possibility that a level difference will occur, so that it can be avoided. That is, as described above, in the region of R_Pg1 <R_Pg <R_Pg2 where the weighting coefficient Kg is 0 <Kg <1, the weighting coefficient Kg is set to change in proportion to the change in the pressure ratio R_Pg. When the pressure ratio R_Pg changes between two predetermined values R_Pg1 and R_Pg2, the weighting coefficient Kg gradually changes accordingly, so that the intake air amount GAIR is changed from the value on one side to the value on the other side of GAIR_N and GAIR_O. It will gradually change toward. As a result, generation of a torque step can be avoided.

  Next, the first intake air amount calculation unit 210 described above will be described with reference to FIG. The first intake air amount calculation unit 210 uses the same modeling method as the first target opening calculation unit 110 described above, that is, the passing air is regarded as a compressible fluid and an adiabatic flow, and the throttle valve 13a is regarded as a nozzle. The first intake air amount GAIR_N is calculated by using a modeling technique. As shown in the figure, the flow rate function calculation unit 211, the opening function calculation unit 212, the first reference air amount calculation unit 213, An atmospheric pressure correction coefficient calculation unit 224 and a multiplier 215 are provided.

  First, the flow function calculation unit 211 calculates a flow function Ψg by searching a map shown in FIG. 22 according to the pressure ratio R_Pg. In this map, the flow function Ψg is set to a smaller value as the pressure ratio R_Pg is larger in the region of R_Pg2 ≦ R_Pg, and is set to a constant value ψgmax in the region of R_Pg ≦ R_Pg1. This is due to the same reason as described in FIG.

  Further, the opening function calculation unit 212 calculates the opening function FTH by searching a map shown in FIG. 23 according to the throttle valve opening TH.

Further, the first reference intake air amount calculation unit 213 calculates the first reference intake air amount GAIR_N_BASE by the following equation (23).

  The above equation (23) corresponds to the above-described equation (15) in which the intake air amount GAIR is replaced with the first reference intake air amount GAIR_N_BASE, and the flow function Ψ is replaced with the flow function Ψg. That is, the first reference intake air amount GAIR_N_BASE is calculated using the equation (23) derived from the model equation (3) described above.

  On the other hand, the atmospheric pressure correction coefficient calculation unit 214 (correction means) described above calculates the atmospheric pressure correction coefficient KPA2 by searching the map shown in FIG. 24 according to the intake lift LIFT and the atmospheric pressure PA. As shown in the figure, the atmospheric pressure correction coefficient KPA2 is set to a value of 1 in the region of LIFT1 ≦ LIFT, and is set to a smaller value in the region of LIFT <LIFT1 as the atmospheric pressure PA is lower. Has been. As is clear from FIG. 12 described above, in the region where the intake lift LIFT is small, that is, the low lift region, the measured value (value indicated by the solid line) of the intake air amount GAIR is corrected as the atmospheric pressure PA is lower. This is because the degree below (the value indicated by the broken line) becomes larger, and it corresponds to that.

Further, the multiplier 215 calculates the first intake air amount GAIR_N by the following equation (24).

  As described above, in the first intake air amount calculation unit 210, the first intake air amount GAIR_N is calculated by correcting the first reference intake amount GAIR_N_BASE with the atmospheric pressure correction coefficient KPA2, so the atmospheric pressure PA is low. In addition, the first intake air amount GAIR_N can be accurately calculated while suppressing the occurrence of the above-described deviation in the region where the intake lift LIFT is small.

  Further, in the case of the first intake air amount GAIR_N, as described above, the flow velocity of the passing air is high because of the relationship calculated using the modeling method in which the passing air is regarded as a compressive fluid and the throttle valve 13a is regarded as a nozzle. Although high calculation accuracy can be ensured in the region, the region where the flow velocity of the passing air is low has a characteristic that the calculation accuracy tends to be lower than that in the high region.

  Next, the second intake air amount calculation unit 220 described above will be described with reference to FIG. The second intake air amount calculation unit 220 uses the same modeling method as the second target opening calculation unit 120 described above, that is, a modeling method that regards the passing air as an incompressible fluid and regards the throttle valve 13a as an orifice. Thus, the second intake air amount GAIR_O is calculated.

  As shown in the figure, the second intake air amount calculation unit 220 includes an opening area calculation unit 221, a second reference air amount calculation unit 222, a calculated intake air amount calculation unit 223, a first correction value calculation unit 224, and a viscosity coefficient calculation. A unit 225, a ray nozzle number calculation unit 226, an aperture area ratio calculation unit 227, a second correction value calculation unit 228, and a multiplier 229.

  First, the opening area calculation unit 221 calculates the opening area Ath by searching a map shown in FIG. 26 according to the throttle valve opening TH.

  Further, the second reference air amount calculation unit 222 calculates a second reference air amount GAIR_O_BASE by searching a map shown in FIG. 27 according to the opening area Ath.

Further, the calculated intake air amount calculation unit 223 calculates the intake air differential pressure PBGA (= PA−PBA) by subtracting the intake air pressure PBA from the atmospheric pressure PA, and applies this to the following equation (25). A calculated intake air amount GAIR_O_CAL is calculated.

On the other hand, the first correction value calculation unit 224 calculates the first correction value KG1 as the reciprocal of the first correction coefficient K1 described above, as shown in the following equation (26).

  Similarly to the viscosity coefficient calculation unit 125 described above, the viscosity coefficient calculation unit 225 calculates the intake air viscosity coefficient μ by searching the map shown in FIG. 15 according to the intake air temperature TA. .

Further, the ray nozzle number calculation unit 226 calculates the ray nozzle number Reg by the following equation (27).

  On the other hand, the opening area ratio calculation unit 227 calculates the opening area ratio R_Ag as a ratio Ath / Ad between the opening area Ath and the passage sectional area Ad of the intake passage 22.

  Further, the second correction value calculation unit 228 calculates the second correction value KG2 as described below. First, the second correction coefficient K2g is calculated by searching the map shown in FIG. 28 according to the opening area ratio R_Ag and the number of ray nozzles Reg. Reg1 to Reg3 in the figure are predetermined values of the number of Ray nozzles Reg, and are set so that the relationship of Reg1 <Reg2 <Reg3 is established. This map corresponds to a map obtained by replacing the number of ray nozzles Re with the number of ray nozzles Reg, the area ratio R_A with the opening area ratio R_Ag, and the second correction coefficient K2 with the second correction coefficient K2g in FIG.

Next, as shown in the following equation (28), the second correction value KG2 is calculated as the reciprocal of the second correction coefficient K2g.

Then, the multiplier 228 calculates the second intake air amount GAIR_O by the following equation (29).

  As shown in the above equation (29), the second intake air amount GAIR_O is calculated by correcting the second reference air amount GAIR_O_BASE with two correction values KG1 and KG2.

  As described above, in the case of the second intake air amount GAIR_O, a region where the flow velocity of the passing air is low is calculated using a modeling method in which the passing air is regarded as an incompressible fluid and the throttle valve 13a is regarded as an orifice. However, although high calculation accuracy can be ensured, the region where the flow velocity of the passing air is high has a characteristic that the calculation accuracy is likely to be lower than that in the low region.

  Next, the fuel injection control process executed by the ECU 2 will be described with reference to FIG. This control process calculates the fuel injection amount TOUT and the fuel injection timing INJ using the intake air amount GAIR calculated as described above, and is executed in synchronization with the generation timing of the TDC signal.

  As shown in the figure, first, in step 10, the intake air amount GAIR is calculated by the calculation method of the intake air amount calculation device 200 described above.

  Next, the routine proceeds to step 11 where a basic injection amount TI_BASE is calculated by searching a map (not shown) according to the intake air amount GAIR.

  Next, in step 12, a feedback correction coefficient KAF is calculated. Specifically, the target air-fuel ratio KCMD is calculated according to the operating state of the engine 3 so that the actual air-fuel ratio calculated based on the detection signal of the LAF sensor 28 converges to the target air-fuel ratio KCMD. The feedback correction coefficient KAF is calculated by a predetermined feedback control algorithm.

  In step 13 following step 12, the fuel injection amount TOUT is calculated. Specifically, various correction values are calculated according to various operating state parameters such as engine water temperature, atmospheric pressure PA, and intake air temperature TA, and the basic injection amount TI_BASE is calculated using these correction values and feedback correction coefficient KAF. By correcting, the fuel injection amount TOUT is calculated.

  Next, the routine proceeds to step 14, where a fuel injection timing INJ is calculated by searching a map (not shown) according to the engine speed NE and the fuel injection amount TOUT. Thereafter, this process is terminated. As described above, when the fuel injection amount TOUT and the fuel injection timing INJ are calculated in the fuel injection control process, the valve opening timing and the valve closing timing of the fuel injection valve 10 are controlled based on these values.

  As described above, according to the intake air amount calculation device 200 of the second embodiment, the intake air amount GAIR is calculated by the weighted average arithmetic expression (22) of the first intake air amount GAIR_N and the second intake air amount GAIR_O. In addition, the weighting coefficient Kg of the equation (22) is calculated by searching the map of FIG. 20 according to the pressure ratio R_Pg. Accordingly, in a region where the flow velocity of the passing air is high such that R_Pg ≦ R_Pg1 is established, Kg = 1.0, so that the intake air amount GAIR is calculated as the first intake air amount GAIR_N, and R_Pg2 ≦ In a region where the flow velocity of the passing air is low such that R_Pg is established, Kg = 0, and the intake air amount GAIR is calculated as the second intake air amount GAIR_O.

  In this case, as described above, the first intake air amount GAIR_N and the second intake air amount GAIR_O calculate the second intake air amount GAIR_O in the region where the flow velocity of the passing air is high. In a region where the accuracy exceeds the accuracy and the flow velocity of the passing air is low, the calculation accuracy of the second intake air amount GAIR_O is calculated to exceed the calculation accuracy of the first intake air amount GAIR_N. Therefore, in a region where the flow velocity of the passing air is high where R_Pg ≦ R_Pg1 is satisfied, the intake air amount GAIR is calculated as the first intake air amount GAIR_N, and the flow velocity of the passing air is low such that R_Pg2 ≦ R_Pg is satisfied. By calculating the intake air amount GAIR as the second intake air amount GAIR_O in the region, the intake air amount GAIR is set to the first intake air amount GAIR_N and the second intake air amount GAIR_O according to the flow rate of the passing air. It can be calculated as one having higher calculation accuracy. As a result, the intake air amount GAIR can be calculated with higher accuracy than before regardless of the flow rate of the passing air.

  Further, when the pressure ratio R_Pg is in the region of R_Pg1 <R_Pg <R_Pg2, when the pressure ratio R_Pg changes between the two predetermined values R_Pg1 and R_Pg2, the weighting coefficient Kg gradually changes accordingly, so that the intake air The degree of weighting of the first and second target openings THN_CMD and THO_CMD in the amount GAIR gradually changes. Thus, unlike the case of directly switching from one of the first intake air amount GAIR_N and the second intake air amount GAIR_O to the other, it is possible to avoid a sudden change in the intake air amount GAIR accompanying the change in the pressure ratio R_Pg. .

  Further, in the map of FIG. 22, the flow rate function Ψg is set to the theoretical maximum value Ψgmax in the region of R_Pg ≦ R_Pg1, so the first intake air amount GAIR_N is held at the maximum value Ψgmax. It is possible to calculate only in the region to be performed, and the calculation accuracy can be maintained at a high level.

  In addition, when the intake lift LIFT is equal to or smaller than the predetermined value LIFT1, an atmospheric pressure correction coefficient KPA2 is calculated according to the intake lift LIFT and the atmospheric pressure PA, and the first reference intake air amount GAIR_N_BASE is calculated using the atmospheric pressure correction coefficient KPA2. Is corrected, the first intake air amount GAIR_N is calculated. Therefore, even when the intake lift LIFT and the atmospheric pressure PA change in a region where the intake lift LIFT is small, the first intake air is suppressed while suppressing the influence thereof. The quantity GAIR_N can be calculated with high accuracy.

  Further, according to the control device 1A of the second embodiment, the intake air amount GAIR is calculated with high accuracy as described above, and therefore, by executing the fuel injection control using such an intake air amount GAIR, High control accuracy can be ensured. In addition to this, the intake air amount GAIR is calculated so as to avoid abrupt fluctuations due to changes in the pressure ratio R_Pg, so that it is possible to avoid the occurrence of a torque step.

  The second embodiment is an example in which the intake air amount GAIR is calculated as the intake air amount parameter. However, the intake air amount parameter of the present invention is not limited to this, and the intake air representing the intake air amount is used. What is necessary is just to calculate a quantity parameter. For example, the target intake air amount GAIR_CMD may be calculated as the intake air amount parameter.

  The second embodiment is an example in which the control device 1A that executes the fuel injection control using the intake air amount GAIR is used as the control device. However, the control device of the present invention is not limited to this, and the intake air is used. What is necessary is just to control an internal combustion engine using quantity. For example, a control device that controls the ignition timing of the internal combustion engine using the intake air amount GAIR may be used.

DESCRIPTION OF SYMBOLS 1 Control apparatus 1A Control apparatus 2 ECU (Intake air amount parameter calculation device, 1st intake air amount parameter calculation means, 2nd intake air amount parameter calculation means, intake air amount parameter setting means, correction means, 1st control means, 1st (2 control means)
Reference Signs List 3 Internal combustion engine 4 Intake valve 12 Intake passage 13a Throttle valve 23 Atmospheric pressure sensor (upstream pressure detection means)
25 Intake pressure sensor (downstream pressure detection means)
40 Variable lift mechanism 100 Target opening degree calculation device (intake air amount parameter calculation device, intake air amount parameter setting means)
110 First target opening degree calculation unit (first intake air amount parameter calculation means)
114 Atmospheric pressure correction coefficient calculation unit (correction means)
120 2nd target opening degree calculation part (2nd intake air amount parameter calculation means)
200 Intake air amount calculation device (intake air amount parameter calculation device, intake air amount parameter setting means)
210 First intake air amount calculation unit (first intake air amount parameter calculation means)
214 Atmospheric pressure correction coefficient calculation unit (correction means)
220 Second intake air amount calculation unit (second intake air amount parameter calculation means)
PA atmospheric pressure (upstream pressure)
PBA intake pressure (downstream pressure)
TH Throttle valve opening TH_CMD Target opening (intake air volume parameter)
THN_CMD First target opening (first intake air amount parameter)
THO_CMD Second target opening (second intake air amount parameter)
R_P Pressure ratio R_P1 Predetermined value
Ψ Flow function (function of pressure ratio)
Ψmax local maximum
Kt Weighting coefficient LIFT Intake lift LIFT1 Predetermined value KPA Atmospheric pressure correction coefficient GAIR Intake air amount (intake air amount parameter)
GAIR_N First intake air amount (first intake air amount parameter)
GAIR_O Second intake air amount (second intake air amount parameter)
R_Pg Pressure ratio R_Pg1 Predetermined value
Ψg flow function (function of pressure ratio)
Ψgmax maximum
Kg Weighting coefficient KPA2 Atmospheric pressure correction coefficient FTH Opening function (value indicating the opening of the throttle valve)

Claims (6)

In an internal combustion engine in which an intake air amount is changed by a throttle valve provided in an intake passage, an intake air amount parameter calculation device for an internal combustion engine that calculates an intake air amount parameter representing the intake air amount,
Upstream pressure detection means for detecting the pressure in the intake passage upstream of the throttle valve as upstream pressure;
Downstream pressure detection means for detecting the pressure in the intake passage on the downstream side of the throttle valve as the downstream pressure;
First intake air amount parameter calculating means for calculating a first intake air amount parameter using a modeling technique in which the air in the intake passage is regarded as a compressive fluid and the throttle valve is regarded as a nozzle;
A second intake air amount parameter calculating means for calculating a second intake air amount parameter using a modeling technique in which the air in the intake passage is regarded as an incompressible fluid and the throttle valve is regarded as an orifice;
When the pressure ratio, which is the ratio of the detected downstream pressure and the detected upstream pressure, is in the first predetermined range, the intake air amount parameter is set to the calculated first intake air amount parameter. And an intake air amount parameter setting means for setting the intake air amount parameter to the calculated second intake air amount parameter when the pressure ratio is in a second predetermined region greater than the first predetermined region;
An intake air amount parameter calculation apparatus for an internal combustion engine, comprising: The first intake air amount parameter calculation means uses a function of the pressure ratio in the calculation method of the first intake air amount parameter derived using the modeling method,
2. The intake air amount of the internal combustion engine according to claim 1, wherein the first predetermined region is a region equal to or less than a predetermined value of the pressure ratio when the function of the pressure ratio theoretically shows a maximum value. Parameter calculation device. The first predetermined area and the second predetermined area are set so as not to overlap each other,
The intake air amount parameter setting means calculates a weighting coefficient based on the pressure ratio when the pressure ratio is between the first predetermined region and the second predetermined region, and sets the intake air amount parameter to The intake air of the internal combustion engine according to claim 1 or 2, wherein a weighted average calculation using the weighting coefficient is set to a value applied to the first intake air amount parameter and the second intake air amount parameter. Quantity parameter calculation device. The internal combustion engine includes a variable lift mechanism that changes an intake lift that is a maximum lift of the intake valve,
The first intake air amount parameter is a value corresponding to one of the intake air amount and the opening of the throttle valve,
The first intake air amount parameter calculating means independently calculates a value representing the other of the intake air amount and the throttle valve opening in the first intake air amount parameter calculation method derived using the modeling method. The correction means for correcting the first intake air amount parameter according to the intake lift and the upstream pressure when the intake lift is equal to or less than a predetermined value. 4. An intake air amount parameter calculation apparatus for an internal combustion engine according to any one of items 1 to 3. An intake air amount parameter calculation device for an internal combustion engine according to any one of claims 1 to 4,
The intake air amount parameter calculation device calculates a target opening that is a target of the opening of the throttle valve as the intake air amount parameter,
A control apparatus for an internal combustion engine, further comprising first control means for controlling the internal combustion engine using the calculated target opening degree. An intake air amount parameter calculation device for an internal combustion engine according to any one of claims 1 to 4,
The intake air amount parameter calculation device calculates the intake air amount as the intake air amount parameter,
A control device for an internal combustion engine, further comprising second control means for controlling the internal combustion engine using the calculated intake air amount.

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