JP2001280201A - Exhaust gas recirculation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation system equipped with precise controllability for the EGR(exhaust gas recirculation) by using proper sampling data about the EGR valve position and presuming accurately the actual excess air ratio in each cylinder. SOLUTION: The target excess air ratio (target λ) is set, and the intra- cylinder EGR amount of an internal combustion engine is derived from the degree of opening of an EGR valve 25 at the intake stroke of the applicable cylinder which is sensed and the differential pressure between in front of and after the EGR valve 25, and the intra-cylinder actual excess air ratio (actual λ) is presumed from the obtained EGR amount, the fuel supply amount into the engine cylinder, and the suction amount of fresh air, and a target EGR amount setting means 45 sets the target EGR amount on the basis of the target and actual excess air ratios while an EGR valve opening controlling means 46 drives the EGR valve 25 on the basis of the set target EGR amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an exhaust gas recirculation device suitable for use in a diesel engine.

[0002]

2. Description of the Related Art Generally, in a diesel engine, exhaust gas recirculation (EGR) is performed to reduce NOx in exhaust gas.
Has been introduced. However, when the amount of EGR introduced is increased, NOx in the exhaust gas can be reduced, but the particulate matter (PM) in the exhaust gas increases. That is, regarding the amount of EGR introduced, N
There is a trade-off relationship between the 0x amount and the PM amount.

[0003] The control of the EGR amount is generally performed by adjusting the opening degree of the EGR valve. As described above, in order to efficiently reduce the NOx amount and the PM amount, which are in a trade-off relationship with each other, it is necessary to control the air in the cylinder. Techniques have been developed for controlling the degree of opening of the EGR valve using the excess ratio (λ) as a parameter. In this technique, a target value (target λ) of the in-cylinder excess ratio is set according to the operating state of the engine (for example, engine speed and engine load), and the actual cylinder (actual λ) becomes the target λ. Thus, the opening degree of the EGR valve is feedback-controlled.

In this case, the actual λ can be obtained from the output of a linear air-fuel ratio sensor (LAFS) provided in an exhaust passage, but in the case of a diesel engine, the sensor is easily deteriorated by the influence of PM in the exhaust gas. In addition, since the response of the LAFS in the exhaust passage is delayed with respect to the change in the excess air ratio (that is, the excess air ratio in the cylinder) in the combustion chamber, an error occurs in the actual λ in a transient state such as acceleration or deceleration. Therefore, the EGR amount may not be properly controlled.

Therefore, a technique for calculating the actual λ from the intake air amount (new air amount), the fuel injection amount, and the EGR amount has been proposed in, for example, Japanese Patent Application Laid-Open No. H10-318047.

[0006]

When the actual λ is calculated as described above, the intake air amount, the fuel injection amount, the EG
It is necessary to determine the R amount. Among them, the intake air amount can be grasped by an air flow sensor or a boost pressure sensor, and the fuel injection amount can be grasped as a drive command value of the injector. Then, the EGR amount can be derived based on the EGR valve opening.

In this case, the opening degree of the EGR valve can be obtained by attaching a position sensor (hereinafter referred to as an EGR position sensor) to the EGR valve and sampling the position of the EGR valve at predetermined intervals by the EGR position sensor. Thus, the EGR amount can be derived at the sampling timing of the EGR position sensor using the value sampled by the EGR position sensor.

On the other hand, the fuel injection amount necessary for calculating the actual λ is calculated in the compression stroke of each cylinder. Generally, in order to increase the control accuracy, when calculating (estimating) the actual λ, EG
It is customary to use the most recent data as possible for the R valve position data, fuel injection amount, and the like. According to this, when calculating the actual λ of a certain target cylinder, it is calculated in the compression stroke of that cylinder. The actual λ of the cylinder is calculated based on the fuel injection amount, the EGR valve position, and the like obtained most recently.

The sampling period of the EGR position sensor is set according to the response of the EGR valve. Although depending on the engine speed, the sampling period is generally set to such an extent that several sampling periods exist in one stroke. For example, FIG. 4 is a diagram showing a sampling timing of data such as an EGR valve position and a calculation timing of a fuel injection amount in a four-cylinder engine in association with an engine crank angle (each stroke).
In FIG. 4, EPS1 to EPS9 indicate EGR valve position data obtained at each sampling timing.
r1 to λr9 indicate estimated values of the actual λ obtained corresponding to the respective EGR valve position data.

As shown in FIG. 4, if the fuel injection amount is calculated at, for example, B105 [105 ° before the compression top dead center (crank angle)], the fuel injection amount calculated here (this Is assumed to be Q1).
105 and the fuel injection amount obtained immediately after this.
GR valve position data (eg, EPS5 or EPS
6), the estimated value of the actual λ (for example, λr5 or λr6) is used.

However, to calculate such an estimated value (λr5 or λr6) of the actual λ, an appropriate value is adopted for the fuel injection amount, but for the data of the EGR valve position, the EGR value is actually stored in the cylinder. The detection data of the compression stroke is used instead of the detection data of the intake stroke in which the intake of air is performed, and the inappropriate data is used, so that an accurate estimated value of the actual λ cannot be obtained. Would.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an accurate excess air ratio in a cylinder can be accurately estimated by using appropriate sampling data with respect to an EGR valve position. An object of the present invention is to provide an exhaust gas recirculation device capable of controlling EGR (exhaust gas recirculation) with high accuracy.

[0013]

Therefore, in the exhaust gas recirculation apparatus according to the present invention, the exhaust gas in the exhaust passage of the internal combustion engine is controlled through the EGR passage by adjusting the opening of the EGR valve. Is returned to the intake passage,
At this time, the target excess air ratio setting means sets the target excess air rate in the cylinder corresponding to the operation state detected by the operation state detection means. On the other hand, the EGR amount deriving means derives the EGR amount from the detected value of the opening degree of the EGR valve during the intake stroke of the target cylinder detected by the opening degree detecting means. The actual excess air ratio in the cylinder is estimated from the EGR amount derived from the above, the fuel injection amount into the cylinder of the internal combustion engine, and the fresh air intake amount. Then, the target EGR amount setting means sets a target EGR amount based on the target excess air rate set by the target excess air ratio setting means and the actual excess air rate estimated by the actual excess air rate estimating means, and Based on the target EGR amount set by the target EGR amount setting means, the valve opening control
Drive the valve.

In the exhaust gas recirculation system according to the present invention, the EGR amount deriving means detects the opening degree of the target cylinder during the intake stroke as the detected value of the opening degree of the EGR valve during the intake stroke of the target cylinder. The EGR amount is derived using an average value of a plurality of sampling data periodically obtained by the detecting means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show an exhaust gas recirculation apparatus as an embodiment of the present invention. First, an engine (internal combustion engine) provided with the exhaust gas recirculation device will be described. As shown in FIG.
This engine 1 is a direct-injection diesel engine,
A high-pressure injection nozzle 3 is arranged above the cylinder 2 so that the injection port faces the inside of the combustion chamber 4, and the high-pressure injection nozzle 3 directly injects the fuel into the combustion chamber 4.

The intake passage 11 is provided with an air cleaner (not shown) at an upstream end. Further, from the upstream side, a compressor section of a turbocharger (supercharger) 30, an intercooler 13, an intake throttle valve 14, a surge tank 15 , Intake valve 1
6 are interposed. In the exhaust passage 21, from the upstream side,
An exhaust valve 22, a turbine section of the turbocharger 30, an oxidation catalyst for diesel (not shown), and the like are interposed.

An exhaust gas recirculation device (EGR) 23 for recirculating exhaust gas is provided between the exhaust passage 21 and the intake passage 11. The EGR 23 is an EGR passage (exhaust recirculation) provided from an upstream portion (for example, an exhaust manifold) of the exhaust passage 21 to a downstream portion (here, a portion between the intake throttle valve 14 and the surge tank 15) of the intake passage 11. ), And an EGR valve 25 for controlling the opening of the EGR passage 24.

In this embodiment, the EGR valve 25 is
It is configured as a negative pressure type that is opened by the negative pressure from the vacuum pump 26. The opening adjustment of the EGR valve 25
E inserted in the middle of the pipe from the vacuum pump 26
The adjustment is performed by controlling the negative pressure state of the EGR valve 24 by adjusting the opening of the GR solenoid 27 (for example, adjusting the opening by duty control).

The EGR solenoid 27, the high-pressure injection nozzle 3 and the intake throttle valve 14 are controlled by an ECU as control means.
(Engine control unit) 40. That is, the ECU 40 includes the engine speed (rotation speed) Ne detected by the crank angle sensor 61 and the accelerator position sensor (AP).
S) Accelerator opening (APS) detected by 62, boost pressure (intake pipe pressure) Pb detected by boost sensor 63, boost temperature (intake pipe temperature) Tb detected by boost temperature sensor 64, open EGR valve opening (actual EPS) detected by an EGR position sensor (EPS) 65 as a degree detecting means and the upstream pressure Peg of the EGR valve 25 detected by a pressure sensor 66
r is input, and the EGR solenoid 26 and the high-pressure injection nozzle 3 are controlled based on these detection information. Note that the crank angle sensor 61 and the accelerator position sensor (APS) 62 correspond to operating state detecting means for detecting the operating state of the internal combustion engine.

The function of controlling the EGR solenoid 27 and the intake throttle valve 14 in the ECU 40 will be described. As shown in FIG. 2, the ECU 40 is provided with a target excess air ratio in the cylinder (a target excess air ratio in the cylinder; A target excess air ratio setting means 41 for setting a target excess air ratio (also referred to as a target λ).
EGR amount deriving means 4 for deriving (calculating) GRcng
2A and the actual excess air ratio (the actual excess air ratio in the cylinder, hereinafter, the actual λ
Actual air excess ratio estimating means 42 for estimating
EGR valve basic position setting means 43 for setting a basic position of the GR valve opening, PI calculating means 44 for performing PI calculation of a difference between the target λ and the actual λ (actual λ−target λ), and a target position of the EGR valve. EGR valve target position setting means (target EGR amount setting means) 45 to be set, EGR valve command means (EGR valve opening degree control means) 46 for outputting a command signal to EGR valve 25 based on the target position, EG
A differential pressure calculating means 47 for calculating the differential pressure DEP before and after the R valve 25, and the pressure difference is increased through the intake throttle valve 14 when the differential pressure DEP before and after the EGR valve 25 calculated by the differential pressure calculating means 47 is equal to or less than a predetermined value. A differential pressure increase control means 48 is provided.

The EGR amount deriving means 42A includes EG
An R flow rate estimating means 42A 'is provided, and the EGR mass Grcng is calculated based on the EGR flow rate VEgr estimated by the EGR flow rate estimating means 42A'. The EGR flow rate estimating means 42A 'includes an EGR valve that processes detection data (EGR valve position sampling data) of the EGR valve opening (actual EPS) detected by the EGR position sensor (EPS) 65 prior to estimating the EGR flow rate. A position data processing means 42B is provided. Further, the intake throttle valve 14 and the differential pressure increase control means 4
8 constitutes a differential pressure increasing means 49.

The target excess air ratio setting means 41 calculates the target excess air ratio from the engine rotational speed Ne and the fuel injection amount (amount corresponding to the engine load) Q into the cylinder using a target λ setting map prepared in advance. (Target λ) is set. EG
In the R flow rate estimating means 42A, EG as an opening degree detecting means is used.
E detected by the R position sensor (EPS) 65
The EGR flow rate into the cylinder of the engine is estimated from the GR valve opening (actual EPS) and the differential pressure across the EGR valve 25 detected by the differential pressure calculating means 47 described later, and the estimation result is calculated as the actual excess air ratio. Output for estimation. However, actual EP
For S (EGR valve position), the value processed by the EGR valve position data processing means 42B is used.

This EGR valve position data processing means 42
In B, the combustion stroke (explosion stroke) of the cylinder to be estimated
All EGs sampled in the intake stroke immediately before
The averaging process (here, simple averaging) is performed on the R valve position sampling data, and this value is used for estimating the EGR flow rate. For example, as shown by the broken line in FIG. 4 described above, while the fuel injection amount is calculated in the compression stroke of a certain target cylinder, here B105 [105 ° before compression top dead center (crank angle)], EGR is performed. As the valve position, the intake stroke of this target cylinder, that is, B360-B180 [360-360 before compression top dead center]
180 ° (crank angle)], the average value EPS _AV (= ΣEP) of a plurality of sampled data (three in FIG. 4)
S _{n + 1 to} EPS _{n + k} / k), and calculates the average value EPS
_AV is the actual EPS (EGR valve position).
FIG. 4 shows the respective mean values shown in EPS _AV1 ~EPS _AV3, the actual calculated to correspond to the average value EPS _AV1, EPS _AV2 lambda at λr _AV1 ~λr _{A V.}

The actual excess air ratio estimating means 42 calculates the actual excess air ratio (actual λ) from the cylinder intake air amount (in-cylinder intake air amount) Ga and the fuel injection amount Q into the cylinder by the following equation (1). Is calculated. Actual λ = Ga / Q / theoretical air-fuel ratio (1) Here, the fuel injection amount Q can be given as a target value of the fuel injection amount from the high-pressure injection nozzle 3, for example, and the cylinder intake air amount Ga is From the total intake amount Ge to the cylinder, E
It can be calculated by subtracting the EGR mass Grcng introduced by GR (Ga = Ge-Grcng).

Of these, the total intake amount Ge to the cylinder is:
As shown in the following equation (2), the engine speed Ne and the boost pressure P
b and the boost temperature Tb. In the following equation (2), Vh is the engine stroke volume, η
v is the volume efficiency, and γb is the specific weight determined from the boost pressure Pb, the atmospheric pressure Pa, and the boost temperature Tb. Ge∝ [Ne × Vh × ηv × γb (Pb, Pa, Tb)] (2) Further, the EGR mass Grcng is obtained by the EGR flow rate estimation means 42A.
In the EGR flow rate estimation means 42A, the actual E
As the product of the EGR valve passage flow rate VEgr which can be calculated from the PS and the differential pressure DEP before and after the EGR valve 25, and the EGR gas density ρegr which can be calculated from the fuel injection amount Q and the engine temperature (generally, engine coolant temperature) Tw. The EGR mass Grcng can be obtained by correcting the calculated EGR mass value Gr with the fresh air mass ratio Ra in the exhaust gas as in the following equation (3).

Grcng = Gr * (1-Ra) (3) where Gr = Vegr * ρegr where, the EGR valve passage flow rate (EGR flow rate) VEgr
Is estimated by the EGR flow rate estimation means 42A '. That is, the EGR flow rate estimating means 42A 'converts the sampling data of the actual EPS detected by the EPS 65 into the EGR data.
From the value averaged by the valve position data processing means 42B and the differential pressure DEP before and after the EGR valve 25 calculated by the differential pressure calculating means 47, the EGR flow rate is determined by a three-dimensional map having a correspondence relationship as shown in FIG. Can be estimated.

In the differential pressure calculating means 47, the boost pressure (intake pipe pressure) detected by the boost sensor 63 is used.
EGR valve 2 detected by Pb and pressure sensor 66
5 (= Pegr−Pb) is calculated.
At this time, as for the boost pressure Pb and the upstream pressure Pegr of the EGR valve 25 used for the calculation, similarly to the sampling data processing of the EGR valve position, data obtained by averaging data obtained in the intake stroke of the target cylinder is used. To

The EGR gas density ρegr is determined by the fuel injection amount Q and the engine temperature (generally, the engine coolant temperature) T
and w. On the other hand, the EGR valve basic position setting means 43 uses the basic EGR valve position setting map prepared in advance, based on the engine speed Ne and the amount of fuel injection (an amount corresponding to the engine load) Q into the cylinder, to obtain an EGR valve basic position.
Set the basic valve position.

In the PI calculating means 44, the deviation between the target λ set by the target excess air ratio setting means 41 and the actual λ estimated by the actual excess air ratio estimating means 42 (= target λ−actual λ) Is subjected to PI calculation processing. In the EGR valve target position setting means 45, the EGR valve basic position set by the EGR valve basic position setting means 43 and the PI
The EGR valve target position EPSt is set by adding the I-processed value.

The EGR valve command means 46 sends a command signal (= EPSt-) to the EGR valve 25 based on the EGR valve target position EPSt set by the EGR valve target position setting means 45 and the current EGR valve position ESP.
ESP). The differential pressure increase control means 48 compares the differential pressure DEP of the EGR valve 25 calculated by the differential pressure calculating means 47 with a predetermined value, and when the differential pressure DEP is equal to or less than the predetermined value, the intake throttle valve 14 is activated. The differential pressure across the EGR valve 25 is increased by squeezing. This is because the EGR flow rate can be properly grasped, and the EGR can be controlled with high accuracy.

That is, in the present apparatus, as described above, the EG
R flow rate (EGR valve passing flow rate) Vegr to EPS65
Actual EPS (opening of EGR valve 25) detected from
The EGR valve 25 calculated by the differential pressure calculating means 47
The correspondence map shown in FIG.
Estimated by the group. In FIG. 3,
ΔPi (ie, ΔP₁~ ΔP₁₁) Indicates the differential pressure across EGR
And ΔP₁, ΔP_Two, ΔP_Two..... DELTA.P₁₁In the order of (i
The greater the value, the greater the differential pressure across EGR. Ma
In addition, the pressure difference between adjacent pressure differentials is ΔP ₁When
ΔP_Two, ΔP_TwoAnd ΔP_Three, ΔP_ThreeAnd Δ
P_FourAre 5 mmHg, ΔP_FourAnd Δ
P_Five, ΔP_FiveAnd ΔP₆, ΔP₆And ΔP
₇Are 10 mmHg, ΔP₇Or later
Indicates that the pressure difference between adjacent pressure differentials is
You.

However, in the low load region where the EGR requirement is high, as shown by a region A in FIG. 3, the differential pressure across the EGR valve is very small, for example, about several mmHg, and a large amount of EGR is required. Therefore, since the EGR valve opening degree is almost fully opened, the change in the EGR flow rate is sensitive to the change in the differential pressure across the EGR valve, and a small error in the differential pressure across the EGR valve is estimated.
The GR flow rate is greatly changed.

Therefore, in this case, the intake throttle valve 14 is throttled to increase the differential pressure across the EGR valve 25 so that the change in the EGR flow is not sensitive to the change in the differential pressure across the EGR valve. Even if an error occurs in the differential pressure between the EGR valve and the EGR valve, the estimated EGR flow rate is not greatly deviated, so that the EGR flow rate can be properly grasped. The intake throttle valve 14
Is controlled to a state corresponding to the operating state of the engine, but the differential pressure increase control means 48 corrects the target opening of the intake throttle valve 14 to the throttle side in accordance with the operating state of the engine, thereby increasing the differential pressure. Try to increase.

Since the exhaust gas recirculation system as one embodiment of the present invention is configured as described above, the target excess air ratio setting means 41 sets the target λ according to the operating state of the engine, and When the excess air ratio estimating means 42 estimates the actual λ, the PI calculating means 44 calculates the difference between the target λ and the actual λ by PI. On the other hand, when the EGR valve basic position setting means 43 sets the EGR valve basic position, the EGR valve target position setting means 45 adds the set EGR valve basic position and the PI calculation processing value, and sets the EGR valve target position. The position is set and the EGR valve command means 46 is set.
Is based on the target position and the actual EGR valve position.
A command signal is output to the GR valve 25.

At the time of estimating the actual λ, the EGR flow rate (EGR valve passing flow rate) Vegr is used to obtain the EGR amount. When the EGR flow rate is obtained, the EGR valve opening degree processed by the EGR valve position data processing means 42B is used. (EGR
Valve position) and E calculated by the differential pressure calculating means 47.
The differential pressure DEP before and after the GR valve 25 is used. At this time, the EGR valve position data
Combustion stroke (explosion stroke) of the cylinder whose R flow rate is to be estimated
The sampling data obtained in the intake stroke immediately before is averaged, and this value is used for EGR flow rate estimation. Therefore, when the EGR intake is actually performed in the cylinder (in the intake stroke). The EGR valve position data of (2) will be used appropriately.

Therefore, the EGR amount can be accurately estimated, an accurate estimated value of the actual λ can be obtained, and the EGR (exhaust gas recirculation) can be controlled with high accuracy. Further, in a low load region where the EGR requirement is high, as shown by a region A in FIG. 3, the differential pressure across the EGR valve is very small, for example, about several mmHg, and a large amount of EGR is required. Since the opening degree of the valve is close to the full opening, E
Although a slight error in the differential pressure between the front and rear of the GR valve causes the estimated EGR flow rate to be largely deviated, the present apparatus is provided with the differential pressure increasing means 49, so that such a problem can be avoided.

That is, when the differential pressure across the EGR valve is equal to or lower than the predetermined pressure, the intake throttle valve 14 is throttled to increase the differential pressure across the EGR valve 25, and as shown in FIG. The EGR flow rate is estimated according to a line having a higher differential pressure of 25 before and after. For example, if the target EGR flow rate is at the level shown as the target EGR flow rate in FIG. 3, the actual EGR flow rate usually exists in the vicinity thereof, but by increasing the differential pressure across the EGR valve 25 in FIG. As shown by an arrow (arrow from right ● to left ●), the EGR flow rate can be ensured while the opening of the EGR valve 25 is relatively small.

As described above, in a region where the differential pressure across the EGR valve 25 is relatively large and the opening of the EGR valve 25 is not so large, the change in the EGR flow with respect to the error in the differential pressure across the EGR valve is small. Therefore, even if there is some error in the calculated value of the differential pressure across the EGR valve, the influence on the estimated value of the EGR flow rate is small, and the EGR amount can be properly grasped.

Thus, the feedback control of the EGR valve using the in-cylinder excess ratio λ as a parameter can be accurately performed, and the EGR control can be appropriately performed. Note that the present invention is not limited to the above embodiment, and can be applied in various modifications.

For example, in the above-described embodiment, the EGR flow rate is estimated by simply averaging sampling data obtained in the intake stroke of the cylinder to be estimated. Also, even if the EGR flow rate is estimated using only one representative value of the sampling data obtained in the intake stroke, the estimation accuracy of the EGR flow rate can be improved to some extent.

In the above-described embodiment, the intake throttle valve 14 is used as the differential pressure increasing means 49. However, if the engine is equipped with a VG turbo, the differential pressure can be increased by reducing the variable vanes of the VG turbo. You can do it. Further, in the above-described embodiment, the intake throttle valve 14 is used as the differential pressure increasing means 49. However, if the engine has a VG turbo, the differential pressure is increased by reducing the variable vanes of the VG turbo. can do.

Also, instead of the differential pressure across the EGR valve,
It is also conceivable to estimate the EGR flow rate using the upstream pressure of the EGR valve. Further, in the above-described embodiment, the present invention is applied to a diesel engine provided with a turbocharger, but is also suitable for a naturally-aspirated diesel engine, a lean-burn gasoline engine, and the like. Furthermore, regarding the specific configuration and control procedure of the engine control system,
Changes can be made without departing from the spirit of the present invention.

[0043]

As described in detail above, according to the exhaust gas recirculation system of the present invention, the EGR amount used for estimating the actual excess air ratio is determined by the EGR amount in the intake stroke of the cylinder to be estimated. Since the estimation is performed using the detected value of the opening of the valve, the EGR amount can be appropriately estimated, the accuracy of estimating the actual excess air ratio is improved, and the EGR control can be performed more accurately.

Further, according to the exhaust gas recirculation apparatus of the present invention, the EGR is performed by using the average value of a plurality of sampling data periodically obtained by the opening degree detecting means during the intake stroke of the target cylinder. Since the flow rate is estimated, EG
The R amount can be more appropriately estimated, the estimation accuracy of the actual excess air ratio is further improved, and the EGR control can be performed with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an internal combustion engine provided with an exhaust gas recirculation device as one embodiment of the present invention.

FIG. 2 is a block diagram illustrating control by an exhaust gas recirculation device as one embodiment of the present invention.

FIG. 3 illustrates the relationship between the differential pressure across the EGR valve, the EGR valve opening, and the EGR flow rate for explaining the problem of the present invention and explaining the operation of the exhaust gas recirculation device as one embodiment of the present invention. FIG.

FIG. 4 is a time chart explaining the problem of the present invention and explaining the operation of the exhaust gas recirculation device as one embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 11 intake passage 21 exhaust passage 23 exhaust recirculation device (EGR) 24 EGR passage 25 EGR valve 41 target excess air ratio setting means 42 actual excess air ratio estimation means 42A EGR amount derivation means 42A 'EGR flow rate estimation means 42B EGR valve position data Processing means 45 EGR valve target position setting means (target EGR amount setting means) 46 EGR valve command means (EGR valve opening degree control means) 47 Differential pressure calculating means 49 Differential pressure increasing means 61 Crank angle sensor as operating state detecting means 62 Accelerator position sensor (APS) as operating state detecting means 65 Opening degree detecting means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 25/07 580 F02M 25/07 580H F02D 41/04 355 F02D 41/04 355 43/00 301 43/00 301H 301N 301W (72) Inventor Setsuo Nishihara 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation F-term (reference) 3G062 AA01 AA03 AA05 BA02 BA04 BA06 EA08 ED01 ED04 FA02 FA04 FA05 FA06 FA09 FA13 GA02 GA04 GA06 GA12 GA15 GA21 GA23 3G084 AA01 AA03 BA05 BA08 BA13 BA20 DA10 EA05 EA11 EB12 EC01 EC03 FA02 FA10 FA11 FA13 FA33 FA37 3G301 HA02 HA04 HA06 HA11 HA13 JA21 KA06 KA23 LA03 LB11 LC03 LC07 MA11 NA08 NB03 NC02 PD02 PA03 PDZ PF16Z

Claims (2)

[Claims] 1. An EGR passage which communicates an exhaust passage of an internal combustion engine with an intake passage to recirculate exhaust gas in the exhaust passage into the intake passage, and is provided in the EGR passage to recirculate into the intake passage. In an exhaust gas recirculation device having an EGR valve for adjusting an amount of exhaust gas, an operating state detecting means for detecting an operating state of the internal combustion engine, and an in-cylinder corresponding to an operating state detected by the operating state detecting means Target excess air ratio setting means for setting the target excess air ratio, opening degree detecting means for detecting the opening degree of the EGR valve, and the EGR valve during the intake stroke of the target cylinder detected by the opening degree detecting means An EGR amount deriving unit that derives an EGR amount into the cylinder of the internal combustion engine based on the detected opening degree of the internal combustion engine; an EGR amount derived by the EGR amount deriving unit; a fuel injection amount to the cylinder; of Actual air excess ratio estimating means for estimating the actual excess air ratio in the cylinder from the fresh air intake amount; and a target excess air ratio set by the target excess air ratio setting device and the actual excess air ratio estimating device. Target EGR for setting the target EGR amount based on the actual excess air ratio
An exhaust gas recirculation apparatus comprising: an amount setting unit; and an EGR valve opening control unit that drives the EGR valve based on a target EGR amount set by the target EGR amount setting unit. 2. The EGR amount deriving means, as an opening detection value of the EGR valve during an intake stroke of the target cylinder,
2. The exhaust gas recirculation system according to claim 1, wherein the EGR amount is derived by using an average value of a plurality of sampling data periodically obtained by the opening degree detection means during an intake stroke of the target cylinder. Circulation device.