JPH0874675A - Exhaust-gas reflux control device of internal combustion engine - Google Patents

Abstract

PURPOSE: To compensate an optimum amount of EGR with good responsiveness when varying the opening of an EGR control valve. CONSTITUTION: The basic number S0 of steps of a step motor 12 for driving an EGR control valve is calculated to meet engine operating requirements (N, Tp). A time constant (τ) is calculated from the number N of revolution of the engine 1, charging efficiency ηv , the volume V of an intake pipe and the opening (number of steps) Sn of the EGR control valve 11, and the weight (k) of moving average is calculated on the basis of the time constant. The number Sn ' of primary delay steps which corresponds to the uncorrected amount of EGR is calculated, and the corrected number of steps, HOS=S0 -Sn , is calculated based on the number Sn '. The basic number S0 of steps is corrected by the corrected number HOS of steps to calculate the corrected number of steps: Sn =S0 +HOS.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation (hereinafter referred to as EGR) control device for an internal combustion engine, and more particularly to an EGR control device capable of improving responsiveness when changing the EGR amount.

[0002]

2. Description of the Related Art Conventionally, an EGR passage is provided which communicates an exhaust pipe with an intake pipe and circulates a part of exhaust gas into intake air. An EGR control valve is provided in this EGR passage to meet engine operating conditions. The opening degree of the EGR control valve is controlled so that a predetermined EGR amount corresponding to the EGR control valve is obtained (see Japanese Utility Model Laid-Open No. 1-130058).

In addition, in response to changes in engine operating conditions, the EG
When the opening degree of the R control valve is changed, the EGR control valve delays the response and the EGR to the cylinder due to the volume effect of the intake pipe.
Correction control is performed to correct the gas inflow delay.

[0004]

However, in the conventional EGR control device, when the opening degree of the EGR control valve is changed in response to the change of the engine operating condition, the EGR control valve is changed.
When correcting the response delay of the control valve or the delay of the EGR gas inflow into the cylinder due to the volume effect of the intake pipe, the correction value is set to a constant value regardless of the engine speed. Of the EGR control valve cannot be adjusted even if the opening degree of the EGR control valve is changed, because it is not possible to cope with the change of the EGR control valve, the change of the filling efficiency by the variable valve operating device, and the change of the intake pipe volume by the variable intake pipe device. There was a problem.

In view of the above conventional problems, the present invention makes it possible to obtain an optimum EGR gas amount with good response when changing the opening of the EGR control valve in response to changes in engine operating conditions. The purpose is to

[0006]

Therefore, according to the present invention, as shown in FIG. 1 (A), a predetermined E according to the engine operating condition is satisfied.
Target opening setting means for setting the target opening of the EGR control valve so as to obtain the GR amount, and engine speed when the target opening of the EGR control valve changes in response to changes in engine operating conditions, Correction value calculating means for calculating a correction value for the opening degree of the EGR control valve based on the charging efficiency, the intake pipe volume, and the opening degree of the EGR control valve; and a correction means for correcting the target opening degree with the correction value. A drive means for driving the EGR control valve at the corrected target opening is provided to configure an EGR control device for an internal combustion engine.

Here, the correction value calculating means is means for calculating the time constant τ by the following equation (1), and τ = V / (C ₁ · S _n + C ₂ · η _V · N) ... (1) V: intake pipe volume S _n : EGR control valve opening
η _V : filling efficiency N: engine speed C ₁ , C ₂ : constant A means for calculating the weight k of the moving average by the following equation (2), and k = 1 / (1 + τ / t _s ) (2 ) t _S: the moving average formula the intervals following equation moving average calculation (3), for each of said time interval t _S,
'Means for calculating, S _n' opening S _n of the EGR control valve corresponding to the EGR amount when the uncorrected _{= k · S 0 + (1} -k) · S n '··· (3) S ₀ : Target opening determined by engine operating conditions A means for calculating the correction value HOS by the following equation (4) and HOS = S ₀ −S _n '... (4) may be included.

Further, as shown in FIG.
In addition to the configuration of (A), EGR gas temperature detection means for detecting the gas temperature in the EGR passage is provided, and the correction value calculation means changes the target opening degree of the EGR control valve in response to changes in engine operating conditions. At this time, the correction value of the opening degree of the EGR control valve may be calculated based on the engine speed, the charging efficiency, the intake pipe volume, the opening degree of the EGR control valve, and the EGR gas temperature.

In the case of the configuration shown in FIG. 1B, the means for calculating the time constant τ in the correction value calculating means calculates the time constant τ by the following equation (1) ′. τ = V / [C ₁ · S _n · (273 + T ₀ ) / (273 + T) + C ₂ · η _V · N] (1) ′ V: intake pipe volume S _n : EGR control valve opening
η _V : Filling efficiency N: Engine speed C ₁ , C ₂ : Constant T ₀ : Standard EGR gas temperature (° C) T: Actual EGR
Gas temperature (° C.) When a variable valve operating device that varies the lift characteristic of the intake valve according to the engine operating conditions is provided, a charging efficiency calculation unit that calculates the charging efficiency according to the lift characteristic is provided. Good.

When a variable intake pipe device is provided which varies the intake pipe volume in accordance with engine operating conditions, it is preferable to provide an intake pipe volume calculating means for calculating the intake pipe volume.

[0011]

According to the present invention, E
When the target opening of the GR control valve changes, the response delay of the EGR control valve and the EG to the cylinder due to the volume effect of the intake pipe
In order to correct the inflow delay of R gas, a correction value of the opening is calculated, the target opening is corrected by the correction value, and control is performed based on the corrected target opening. The EGR amount is proportional to the intake pipe volume, and exhibits a first-order lag response having a time constant inversely proportional to the engine speed (especially the product of the engine speed and the charging efficiency) and the opening degree of the EGR control valve. Engine speed, filling efficiency, intake pipe volume, and E
By calculating the correction value based on the opening of the GR control valve, the optimum EGR amount can be obtained with good response to the change in the target opening.

Specifically, the time constant τ is calculated from the engine speed N, the charging efficiency η _V , the intake pipe volume V, and the opening degree S _n of the EGR control valve by the equation (1), and the (2) By the formula,
The moving average weight k is calculated based on the time constant τ, and the opening (opening corresponding to the first-order lag) S _n ′ of the EGR control valve corresponding to the EGR amount when there is no correction is calculated by the equation (3). was calculated as the weight for the target opening degree S _0, by the equation (4), the target opening S ₀ by subtracting the first order lag corresponding opening S _n ', and calculates the correction value HOS.

By the correction value HOS calculated in this way, the primary delay is increased when the target opening is increased, and the primary delay is decreased when the target opening is decreased. The EGR amount sucked into the cylinder can be made equal to the target value, and NO due to insufficient EGR amount
It is possible to avoid the occurrence of x and the occurrence of engine instability due to an excessive amount of EGR.

Further, when the temperature of the EGR gas changes, the density of the gas changes and the delay behavior changes.
By providing the gas temperature detecting means, the correction value calculating means,
By calculating the correction value of the opening of the EGR control valve based on the engine speed, the charging efficiency, the intake pipe volume, the opening of the EGR control valve, and the EGR gas temperature, the delay due to the change of the EGR gas temperature is calculated. It is also possible to correct for changes in behavior. Particularly, since the EGR gas has a large temperature fluctuation range unlike fresh air, the effect of such correction is great.

Specifically, when calculating the time constant τ, the engine speed N, the charging efficiency η _V , the intake pipe volume V, the opening E _{n of} the EGR control valve, and the EGR are calculated by the equation (1) ′. The time constant τ is calculated from the gas temperature T. Further, when the variable valve operating device is provided, by calculating and using the filling efficiency according to the lift characteristic by the variable valve operating device, it is possible to cope with the change of the filling efficiency.

Further, when the variable intake pipe device is provided, the intake pipe volume can be calculated and used to cope with the change in the intake pipe volume.

[0017]

Embodiments of the present invention will be described below. [First Embodiment] FIG. 2 shows the system configuration of the first embodiment. Air controlled by the throttle valve 3 in the throttle chamber 2 is sucked into the engine 1 through an intake valve 5 after passing through an intake pipe (intake manifold) 4.
Further, a fuel injection valve 6 is provided for each cylinder in a branch portion of the intake pipe 4, and an amount of fuel injection valve 6 injected from the fuel injection valve 6 at a predetermined timing synchronized with engine rotation corresponds to an engine operating condition. Fuel is supplied to the engine 1 via the intake valve 5, whereby an air-fuel mixture is formed in the cylinder.

The intake valve 5 is driven by an intake cam 7. The intake cam 7 has a cam profile for low rotation / low load and a cam profile for high rotation / high load. A variable valve operating device is configured to change the lift characteristic of the intake valve 5 according to the engine operating conditions. The air-fuel mixture sucked into the cylinder of the engine 1 is ignited by a spark plug 8 and burned at an ignition timing according to engine operating conditions, and exhaust gas is exhausted through an exhaust valve (not shown) (exhaust manifold). It is discharged to 9.

An EGR passage 10 is provided which connects the exhaust pipe 9 and the intake pipe 4 to recirculate a part of the exhaust gas into the intake air.
An EGR control valve 11 is provided in the EGR passage 10. The EGR control valve 11 is driven by a step motor 12 as a driving means to control its opening. Here, the amount of fuel injection and the injection timing of the fuel injection valve 6, the ignition timing by the spark plug 8, the lift characteristic of the intake valve 5 by the intake cam 7, and the opening degree of the EGR control valve 11 by the step motor 12 are the microcomputer. It is controlled by a signal from the built-in control unit 13.

For these controls, the control unit 13 includes a crank angle sensor 14 for detecting the crank angle of the engine 1, an air flow meter 15 for detecting the intake air flow rate upstream of the throttle valve 3, and a water temperature for detecting the cooling water temperature. Signals are respectively sent from the sensor 16, the throttle sensor 17 that detects the opening of the throttle valve 3, and the pressure sensor 19 that detects the EGR gas pressure between the EGR control valve 11 and the EGR orifice 18 on the upstream side in the EGR passage 10. It has been entered.

The control of the EGR control valve 11 (step motor 12) by the control unit 13 will be described below. In this control, the EG control is performed in response to changes in engine operating conditions.
When the target opening degree of the R control valve 11 (the basic number of steps of the step motor 12) S ₀ changes, the response delay of the EGR control valve 11 and the inflow delay of the EGR gas into the cylinder due to the volume effect of the intake pipe 4 are delayed. For correction, a correction value of opening (correction step number) HOS is calculated, the target opening is corrected by the correction value, and the target opening after correction (post-correction step number)
The control is based on S _n = S ₀ + HOS. First, the necessity of such correction will be described with reference to FIG.

FIG. 3 is a timing chart. In this figure, the engine operating conditions change at time t ₀ , the target opening (basic step number) S ₀ changes from St ₀ to St ₁ , and then at time t ₁ , as shown in (A). It is assumed that the target opening degree (basic step number) S ₀ returns from St ₁ to St ₀ . In addition, in this example, for the sake of explanation, it is assumed to change stepwise.

With respect to the change of the target opening degree (basic step number) S ₀ , the EGR amount sucked into the cylinder is (B)
Shows a first-order lag response. The time constant τ at this time is approximated as follows. τ = V / (C ₁ · St ₀ + C ₂ · η _V · N) V: Intake pipe volume η _V : Filling efficiency N: Engine speed C
₁ , C ₂ : constant Therefore, when the EGR amount increases with respect to the target EGR amount, only the difference between the step response and the first-order lag response is EG
R amount is insufficient. On the contrary, the EG
When the R amount decreases, the EGR amount becomes excessive due to the difference between the first-order lag response and the step response.

Therefore, at time t₀Immediately after
NOx is generated due to₁Excessive EGR immediately after
Therefore, engine instability occurs. Therefore, as shown in (C)
As described above, EGR corresponding to the EGR amount without correction
Opening of control valve (opening corresponding to first-order delay; step corresponding to first-order delay)
Number) S_n′ Is calculated and the target opening (basic step number) S
₀From the opening corresponding to the first-order delay (the number of steps corresponding to the first-order delay)
S_n′ Is subtracted from the
Number) HOS = S ₀-S_n’ And said
Target opening (basic step number) S₀The above-mentioned correction value (after correction
By correcting the number of steps) with HOS, (D)
Target opening after correction (number of steps after correction) S_n= S
₀+ HOS is calculated, and control is performed based on this.

In this way, the increase correction for the primary delay is performed immediately after time t ₀ , and the decrease correction for the primary delay is performed immediately after time t ₁ . As a result, as shown in (E), the EGR amount sucked into the cylinder after the correction becomes equal to the target value, and it is possible to avoid the above-described generation of NOx and engine instability.

The control of the EGR control valve 11 (step motor 12) by the control unit 13 will be described with reference to the flowchart of FIG. The EGR control routine of FIG. 4 is executed every predetermined time (t _S sec). Step 1
(Indicated as S1 in the figure. The same applies hereinafter), the water temperature Tw is detected based on the signal from the water temperature sensor 16.

In step 2, it is judged whether or not the water temperature Tw is, for example, 70 ° C. or more. If the water temperature is lower than 70 ° C., the process proceeds to step 16 to stop the EGR, and the driving step number S _n of the step motor 12 is set. To the minimum value. As a result, the EGR control valve 11 is fully closed and the EGR rate is set to 0%. In step 3, it is determined whether the water temperature Tw is 110 ° C. or lower,
Even when the water temperature is higher than 110 ° C., the process proceeds to step 16 to stop the EGR and the number of driving steps S _n of the step motor 12
To the minimum value. As a result, the EGR control valve 11 is fully closed and the EGR rate is set to 0%.

As a result of the judgment in steps 2 and 3, if 70 ° C. ≦ Tw ≦ 110 ° C., the process proceeds to step 4.
In step 4, the engine speed N is detected based on the signal from the crank angle sensor 14 (engine speed detecting means).
In step 5, the intake air flow rate Q is detected based on the signal from the air flow meter 15.

In step 6, from the intake air flow rate Q and the engine speed N, the basic fuel injection amount Tp = K.Q / N (however,
K is a proportional constant corresponding to the flow rate of the fuel injection valve) (Tp is a value corresponding to a load, load detecting means). In step 7, the engine speed N and the basic fuel injection amount (load)
Using Tp as a parameter of the engine operating condition, the basic step number S ₀ of the step motor 12 corresponding to the target opening degree of the EGR control valve 11 is calculated accordingly. This calculation may be performed by referring to the map and searching. FIG. 5 shows an example of a map of the basic step number S ₀ . Further, FIG. 6 shows an example of a map of the EGR rate for reference. Incidentally, FIG.
The map of FIG. 6 shows the number of basic steps and the EGR rate at each grid point, and when values other than the grid points are obtained, interpolation calculation is performed. The part of step 7 corresponds to the target opening setting means.

In step 8, the lift characteristic of the intake valve 5 by the variable valve operating device is determined from the engine speed N and the basic fuel injection amount Tp, and the charging efficiency η _V is calculated. The part of step 8 corresponds to the charging efficiency calculation means. After this,
Proceed to step 11. In step 11, the time constant τ is calculated by the following equation. τ = V / (C ₁ · S _n + C ₂ · η _V · N) V: intake pipe volume S _n : driving step number η _V : filling efficiency N: engine speed C ₁ , C ₂ : constant, that is, in the cylinder The intake EGR amount is proportional to the intake pipe volume, and has a time constant that is inversely proportional to the engine speed (especially the product of the engine speed and the charging efficiency) and the opening degree (drive step number) of the EGR control valve. Since it shows a delayed response,
The time constant τ is determined by the above formula.

In step 12, the moving average weight k is calculated by the following equation. This is an approximation for performing the calculation in a discrete value system and shortening the calculation time. k = 1 / (1 + τ / t _s ) τ: time constant t _s : time interval of moving average calculation (execution cycle of this routine) However, the calculation of the weight k of the moving average in step 11 and step 12 is the target opening degree. It may be performed only when the (basic step number) S ₀ changes (see FIG. 3F).

In step 13, the EGR control valve corresponding to the EGR amount without correction is calculated by the following equation (moving average equation).
The first-order delay equivalent step number S _n 'corresponding to the opening degree of 11 (first-order delay equivalent opening degree) is calculated with k being a weight for the basic step number S ₀ corresponding to the target opening degree. _{S n '= k · S 0} + (1-k) · S n' Incidentally, when S _n 'is the last execution of the routine on the right side of the equation (t
_This is the number of steps corresponding to the first-order delay calculated before _S sec).

In step 14, the correction step number H corresponding to the opening correction value is obtained by subtracting the primary delay equivalent step number S _n 'from the basic step number S ₀ by the following equation.
Calculate the OS. HOS = S ₀ −S _n ′ Therefore, the steps 11 to 14 correspond to the correction value calculating means.

In step 15, the corrected step number H OS is added to the basic step number S ₀ by the following equation to obtain the corrected step number S _n corresponding to the corrected target opening degree.
To calculate. S _n = S ₀ + HOS The step 15 corresponds to the correction means.

When the post-correction step number S _n is calculated as described above, the opening of the EGR control valve 11 is controlled with good response to the target opening by the step motor 12 as the driving means, using this as the number of driving steps. To be done. [Second Embodiment] FIG. 7 shows the system configuration of the second embodiment.

The difference from FIG. 2 is that the EG in the EGR passage 10 is
As the EGR gas temperature detecting means for detecting the R gas temperature,
A temperature sensor (for example, thermocouple) 20 is provided, and its signal is input to the control unit 13. FIG.
6 is a flowchart of an EGR control routine of the second embodiment. 4 is different from FIG. 4 in that step 10 is added after step 8, and in this step 10, the EGR gas temperature T is detected based on the signal from the temperature sensor 20.

Further, step 11 is changed to step 11 ', and in this step 11', the time constant τ is calculated by the following equation. τ = V / [C ₁ · S _n · (273 + T ₀ ) / (273 + T) + C ₂
・ Η _V・ N] V: Intake pipe volume S _n : Number of driving steps η _V : Filling efficiency N: Engine speed C ₁ , C ₂ : Constant T ₀ : Standard EGR gas temperature (° C) T: Actual EGR
Gas temperature (° C.) The standard EGR gas temperature T ₀ is a temperature when the constant C ₁ is matched in the experiment.

Others are the same. As described above, in the present embodiment, when the temperature of the EGR gas changes, the density of the gas changes, and the behavior of the delay changes, so this can be corrected. In particular, since the EGR gas has a large temperature fluctuation range unlike fresh air, the effect of such correction is great.

[Third Embodiment] FIG. 9 shows the system configuration of the third embodiment. What is different from FIG. 7 is that a variable intake pipe device is provided that makes the intake pipe volume variable according to the engine operating conditions in order to increase the charging efficiency under all engine operating conditions. That is, the sub intake pipe 21 is provided in such a manner that the upstream side and the downstream side of the collector portion of the intake pipe (main intake pipe) 4 communicate with each other, and the main intake pipe 4 and the sub intake pipe 21 are connected to each other.
Electromagnetic on-off valves 22 and 23 are provided at the communicating portions of the respective places. Therefore, by opening and closing these on-off valves 22 and 23 in synchronization with each other, the main intake pipe 4 and the sub intake pipe 21 can be connected or separated from each other, thereby changing the intake pipe volume.

These on-off valves 22 and 23 receive engine operating conditions (N, Tp) according to signals from the control unit 13.
It will be opened and closed according to. FIG. 10 is a flow chart of the EGR control routine of the third embodiment. The difference from FIG. 8 is that
Step 9 is added after step 8, and in this step 9, from the engine speed N and the basic fuel injection amount Tp,
The operating state of the intake pipe variable device is determined and the intake pipe volume V is calculated. That is, assuming that the volume of the main intake pipe 4 is V _M and the volume of the sub intake pipe 21 is V _S , V = V _M when connected.
It is calculated as + V _S and V = V _M at the time of disconnection. The step 9 corresponds to the intake pipe volume calculating means. After this, proceed to Step 10.

Others are the same. However, step 8
When calculating the charging efficiency η _V in accordance with the lift characteristic of the intake valve 5 by the variable valve operating device in, the operating state of the variable intake pipe device may be taken into consideration. Thus, in this embodiment,
When the intake pipe variable device is provided, it is possible to cope with a change in the intake pipe volume by considering the intake pipe volume due to the device.

[0042]

As described above, according to the present invention, when the target opening degree of the EGR control valve changes in response to changes in engine operating conditions, engine speed, charging efficiency, intake pipe volume, and By calculating the correction value of the opening degree of the EGR control valve based on the opening degree of the EGR control valve, the cylinder is affected by the response delay of the EGR control valve and the volume effect of the intake pipe regardless of changes in the engine speed. Properly corrects the delay of EGR gas inflow to the EGR gas and responds optimally to changes in the target opening.
It is possible to obtain the amount, and it is possible to prevent the generation of NOx due to the insufficient EGR amount and the occurrence of engine instability due to the excessive EGR amount.

Further, by calculating the correction value by the equations (1) to (4), the calculation can be performed relatively easily and the calculation time can be shortened. Also, EG
When the temperature of the R gas changes, the density of the gas changes and the behavior of the delay changes. However, the EGR gas temperature detecting means is provided and the correction value calculating means uses the engine speed, the charging efficiency,
By calculating the correction value of the opening of the EGR control valve based on the intake pipe volume, the opening of the EGR control valve, and the EGR gas temperature, even if the fluctuation range of the EGR gas temperature is large, the optimum EGR amount is always obtained. Obtainable.

Further, when the correction is made by the EGR gas temperature, the correction value is calculated by the above equations (1) ′ to (4) so that the calculation can be performed relatively easily and the calculation time can be shortened. Can be achieved. Further, when the variable valve operating device is provided, by calculating and using the filling efficiency in accordance with the lift characteristic of the variable valve operating device, it is possible to deal with the change in the filling efficiency.

When the variable intake pipe device is provided, the intake pipe volume can be calculated and used to cope with the change in the intake pipe volume.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention.

FIG. 2 is a system configuration diagram of the first embodiment of the present invention.

FIG. 3 is a timing chart showing the necessity of correction.

FIG. 4 is a flowchart of an EGR control routine.

FIG. 5 is a diagram showing a map of the number of basic steps.

FIG. 6 is a diagram showing a map of an EGR rate.

FIG. 7 is a system configuration diagram of a second embodiment of the present invention.

FIG. 8 is a flowchart of an EGR control routine according to the second embodiment.

FIG. 9 is a system configuration diagram of a third embodiment of the present invention.

FIG. 10 is a flowchart of an EGR control routine according to the third embodiment.

[Explanation of symbols]

 1 engine 3 throttle valve 4 intake pipe (main intake pipe) 5 intake valve 6 fuel injection valve 7 intake cam (variable valve device) 8 spark plug 9 exhaust pipe 10 EGR passage 11 EGR control valve 12 step motor 13 control unit 14 crank Angle sensor 15 Air flow meter 20 Temperature sensor 21 Sub intake pipe 22,23 Open / close valve (variable intake pipe device)

Claims (6)

[Claims] 1. An internal combustion engine comprising: an exhaust gas recirculation passage that connects an exhaust pipe and an intake pipe to recirculate a part of exhaust gas into intake air; and an exhaust gas recirculation control valve interposed in the exhaust gas recirculation passage. Target opening degree setting means for setting the target opening degree of the exhaust gas recirculation control valve so as to obtain a predetermined exhaust gas recirculation amount according to the engine operating condition, and the target opening degree of the exhaust gas recirculation control valve corresponding to the change of the engine operating condition Correction value calculating means for calculating a correction value of the opening degree of the exhaust gas recirculation control valve based on the engine speed, the charging efficiency, the intake pipe volume, and the opening degree of the exhaust gas recirculation control valve when the degree changes, An exhaust gas recirculation control device for an internal combustion engine, comprising: a correction unit that corrects a target opening amount by the correction value; and a driving unit that drives an exhaust gas recirculation control valve to the corrected target opening amount. 2. The correction value calculating means is a means for calculating a time constant τ according to the following equation (1), and τ = V / (C ₁ · S _n + C ₂ · η _V · N) ... ( 1) V: intake pipe volume S _n : opening degree of exhaust gas recirculation control valve η
_V : charging efficiency N: engine speed C ₁ , C ₂ : constant A means for calculating the weight k of the moving average by the following equation (2), and k = 1 / (1 + τ / t _s ) (2) t _S: the moving average formula the intervals following equation moving average calculation (3), for each of said time interval t _S,
'Means for calculating, S _n' opening S _n of the exhaust gas recirculation control valve corresponding to the exhaust gas recirculation amount when the uncorrected _{= k · S 0 + (1} -k) · S n '··· (3 ) S ₀ : Target opening determined by engine operating conditions Means for calculating the correction value HOS by the following equation (4) and HOS = S ₀ −S _n '... (4) The exhaust gas recirculation control device for an internal combustion engine according to claim 1, 3. An internal combustion engine comprising: an exhaust gas recirculation passage for communicating a part of exhaust gas into the intake air by communicating an exhaust pipe and an intake pipe; and an exhaust gas recirculation control valve interposed in the exhaust gas recirculation passage, Target opening degree setting means for setting a target opening degree of the exhaust gas recirculation control valve so as to obtain a predetermined exhaust gas recirculation amount according to engine operating conditions, and exhaust gas recirculation gas temperature detection means for detecting the gas temperature in the exhaust gas recirculation passage When the target opening of the exhaust gas recirculation control valve changes in response to changes in engine operating conditions, the engine speed, charging efficiency, intake pipe volume, exhaust gas recirculation control valve opening, and exhaust gas recirculation gas temperature are changed. Based on the correction value calculating means for calculating a correction value for the opening of the exhaust gas recirculation control valve, a correction means for correcting the target opening with the correction value, and an exhaust gas recirculation control valve for the corrected target opening. And a driving means for driving, are provided. Exhaust gas recirculation control system for an internal combustion engine to be. 4. The correction value calculating means calculates the time constant τ by the following equation (1) ′, and τ = V / [C ₁ · S _n · (273 + T ₀ ) / (273 + T) + C ₂ · Η _V · N] (1) ′ V: intake pipe volume S _n : exhaust recirculation control valve opening η
_V: charging efficiency N: engine speed C _1, C _2: constants T _0: standard exhaust recirculation gas temperature (℃) T: the actual exhaust gas recirculation gas temperature (℃) equation (2), the moving average weights k K = 1 / (1 + τ / t _S ) ... (2) t _S : Time interval for calculating moving average At each time interval t _S by the moving average formula of the following formula (3),
'Means for calculating, S _n' opening S _n of the exhaust gas recirculation control valve corresponding to the exhaust gas recirculation amount when the uncorrected _{= k · S 0 + (1} -k) · S n '··· (3 ) S ₀ : Target opening determined by engine operating conditions Means for calculating the correction value HOS by the following equation (4) and HOS = S ₀ −S _n '... (4) The exhaust gas recirculation control device for an internal combustion engine according to claim 3, 5. A variable valve device for varying a lift characteristic of an intake valve according to an engine operating condition, and a charging efficiency calculating means for calculating a charging efficiency according to the lift characteristic. The exhaust gas recirculation control device for an internal combustion engine according to any one of claims 1 to 4. 6. A variable intake pipe device for varying the intake pipe volume according to engine operating conditions, and intake pipe volume calculation means for calculating the intake pipe volume by the variable intake pipe device. Item 6. An exhaust gas recirculation control device for an internal combustion engine according to any one of items 5.