JPH09228899A - Egr device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control an actual EGR rate regardless of an aging effect and dispersion in manufacture for an engine by estimating an actual EGR rate based on the output of a cylinder inner pressure sensor, and thereby correcting the opening of an EGR valve based on errors between a target EGR rate and an estimated actual EGR rate. SOLUTION: A target EGR rate is set 8 in response to the operational condition of a diesel engine 1, and concurrently the target quantity of fuel. injection is also set up 7 based on an operational condition. And in a control part 17, a first target opening of an EGR valve is operated in response to an operational condition and the target EGR rate, and the EGR valve is thereby controlled in accordance with a target opening of the EGR valve where the aforesaid first target opening is corrected as specified. Beside, an actual EGR rate is estimated 19 based on a cylinder inner pressure sensor 15 and an engine rotation angle sensor 2, a second target opening of the EGR valve is operated 18 based on the target EGR rate and the estimated actual EGR rate, and the first target opening of the EGR valve is corrected as specified based on the aforesaid operated opening so as to be outputted as a third target opening of the EGR valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR device for a diesel engine, which controls the EGR rate according to the operating state of the engine.

[0002]

2. Description of the Related Art A conventional diesel engine EGR device is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-215426. The outline of the configuration is shown in FIG. In the figure, 1 is a diesel engine, 2 is an engine rotation angle sensor, 3 is an air flow meter, 4 is an EGR valve, 5
Is a fuel pump, 6 is an accelerator opening sensor, 7 is a fuel injection amount setting unit, 8 is a target EGR rate setting unit, 9 is an EGR valve opening control unit, 10 is an actual EGR rate estimating unit, and 11 is a cylinder intake gas mass. It is a flow rate estimation unit.

The fuel pump 5 supplies fuel to the diesel engine 1 according to the output of the fuel injection amount setting unit 7.
In the fuel injection amount setting unit 7, the engine rotation angle sensor 2
Then, the fuel injection amount is obtained using the output of the accelerator opening sensor 6 and a predetermined map. The target EGR rate setting unit 8 outputs the target EGR rate using the fuel injection amount setting unit 7, the output of the engine rotation angle sensor 2 and a predetermined map. The EGR valve opening control unit 9 controls the opening of the EGR valve 4 based on the target EGR rate which is the output of the target EGR rate setting unit 8 and the estimated actual EGR rate which is the output of the actual EGR rate estimation unit 10. . In the actual EGR rate estimation unit 10, the cylinder intake gas mass flow rate (Qc) which is the output of the cylinder intake gas mass flow rate estimation unit 11 and the fresh air flow rate (Qa) which is the output of the air flow meter 3 are estimated using the following equations. The EOR rate (e1) is calculated. In _{e1 = (Q 0 -Q C)} / Q C ... (1) cylinder intake gas mass flow rate estimation unit 11, from a predetermined map and the output of the engine rotation angle sensor 2, to estimate the cylinder intake gas mass flow rate.

FIG. 17 shows an outline of the configuration of the second conventional example. The second conventional example is a diesel engine 1, an engine rotation angle sensor 2, an air flow meter 3, an EGR valve 4, a fuel pump 5, an accelerator opening sensor 6, a fuel injection amount setting unit 7, a target EGR rate setting unit 8, an engine model. 12, a target EGR flow rate calculation unit 13, and a target EGR valve opening calculation unit 14.

The configurations of 1 to 8 are the same as those of the first embodiment, and the description thereof will be omitted. In the engine model 12, the fuel injection amount, which is the output of the fuel injection amount setting unit 7, the output of the engine rotation angle sensor 2, the fresh air flow rate, which is the output of the air flow meter 3, and the target EGR valve opening calculation unit 14. An engine model in which the output and the dynamics of the engine to be controlled are modeled in advance is used to calculate the differential pressure across the EGR valve, the delay coefficient in the intake system, and the cylinder intake gas mass flow rate estimated value. The target EGR flow rate calculation unit 13 calculates the target EGR flow rate from the target EGR rate that is the output of the target EGR rate setting unit 8 and the cylinder intake gas mass flow rate estimated value that is the output of the engine model 12. The target EGR valve opening calculation unit 14 uses the target EGR flow rate, which is the output of the target EGR flow rate calculation unit 13, the differential pressure across the EGR valve, which is the output of the engine model 12, and the delay coefficient in the intake system,
The target opening of the EGR valve is calculated and the opening of the EGR valve 4 is controlled.

[0006]

However, the conventional EGR device for a diesel engine as described above has the following problems. In the first conventional example, 1) Since the actual cylinder intake gas mass flow rate depends on the engine speed and the intake pressure (collector internal pressure), the cylinder intake gas mass flow rate obtained only from the engine speed, especially in the transient region. Is not accurate. 2) Actually, because of the accumulation of gas inside the collector (change in collector internal gas density), the flow rate passing through the EGR valve is the difference between the cylinder intake gas mass flow rate and the fresh air flow rate, which is the output of the air flow meter. Don't 3) Since there is a capacity such as a collector and an intake pipe between the air flow meter and the cylinder, the fresh air flow rate output from the air flow meter and the fresh air flow rate component in the cylinder intake gas mass flow rate do not substantially match. Note that FIG. 18 shows a comparison result by simulation of the target EGR rate and the EGR rate control result according to the first conventional example.
As shown in this figure, in the first conventional example, the transient region (4.0
The error is large in ~ 4.4 sec). Therefore, the EGR rate becomes excessive and PM is likely to occur immediately after acceleration.

In the second conventional example, the EGR rate control in the transient region, which is the problem of the first conventional example, is performed by calculating the target EGR valve opening by using the engine model describing the dynamics of the engine. Can be done accurately. However, if there is an error between the engine model and the actual engine (change or variation in engine characteristics, foreign matter accumulation on the EGR valve, etc.), it cannot be corrected. Note that, in the second conventional example, FIG. 19 shows a comparison result by simulation of the actual EGR rate and the target EGR rate when foreign matter adheres to the EGR valve. As shown in this figure, in the second conventional example,
Since the error in the steady range (4.4 sec-) is large and the actual EGR rate is too small, NOx easily occurs. Further, because PM is suppressed, the output is also reduced due to the decrease in the fuel injection amount.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to improve the accuracy of the actual EGR rate in both the transient region and the steady region.

[0009]

In order to achieve the above-mentioned object, in the invention according to claim 1, a target EGR rate setting unit for outputting a target EGR rate according to the operating state of a diesel engine, and the target operating state are set to the operating state. A target fuel setting unit that sets a target fuel injection amount based on the fuel pump, a fuel pump that supplies fuel to the diesel engine according to the target fuel injection amount, and a first target EGR valve according to the operating state and the target EGR rate. A diesel engine E that includes a first target EGR valve opening calculation unit that outputs an opening amount and an EGR valve control unit that controls the EGR valve according to a third target EGR valve opening amount that is a predetermined correction
In the GR control device, the means for detecting the pressure in the combustion chamber of the diesel engine, the means for detecting the rotation angle of the diesel engine, and the information on the pressure in the combustion chamber, the rotation angle, and the fuel injection amount are actually used. An actual EGR rate estimating unit that estimates the EGR rate of the second target EGR rate, a second target EGR valve opening calculating unit that calculates a second target EGR valve opening based on the target EGR rate and the actual EGR rate estimated value, and the second A target EGR valve opening correction unit is provided which outputs the third target EGR valve opening degree by adding the predetermined correction to the first target EGR valve opening degree based on the target EGR valve opening degree. In the diesel engine EGR device according to claim 1, the actual EGR rate estimation unit has a mathematical model of a phenomenon inside the combustion chamber, and the model, the pressure inside the combustion chamber, the rotation angle, and the rotation angle The actual EGR rate may be estimated from the information on the fuel injection amount. (Claim 2) Further, in the diesel engine EGR device according to claim 1, the actual EGR rate estimation unit has lookup data of a phenomenon inside the combustion chamber, and the lookup data, the pressure inside the combustion chamber, and The actual EGR rate may be estimated from the rotation angle and the information on the fuel injection amount.
(Claim 3) The diesel engine E according to any one of claims 1 to 3.
In the GR device, the actual EGR rate estimation unit may estimate the actual EGR rate using information on the fuel injection timing. (Claim 4) The diesel engine E according to any one of claims 1 to 4.
In the GR device, in the second target EGR valve opening degree calculation,
The sum of a value obtained by multiplying an error between the target EGR rate and the actual EGR rate, an integrated value of the error, and a sign value of the error by a desired coefficient is the second target EGR valve opening. It may be a degree. (Claim 5) Further, in the diesel engine EGR device according to claim 5, the desired coefficient may be changed according to the operating state. (Claim 6) Further, in the diesel engine EGR device according to claim 5, the desired coefficient may be a constant. (Claim 7) Further, in the diesel engine EGR device according to claim 1, the third target EGR valve opening degree is the first target EG.
It may be the sum of the R valve opening and the second target EGR valve opening. (Claim 8) Further, in the diesel engine EGR device according to claim 1, the information of the fuel injection amount may be a target fuel injection amount set by a fuel injection setting unit according to an operating state. . (Claim 9) The EGR device for a diesel engine according to claim 1, further comprising means for detecting a fuel injection amount supplied from the fuel pump, and using the fuel injection amount as information of the fuel injection amount. You may do it. (Claim 10)

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention.
First, the configuration will be described. The diesel engine EGR device according to the first embodiment includes a diesel engine 1,
Engine rotation angle sensor 2, air flow meter 3, EG
R valve 4, fuel pump 5, accelerator opening sensor 6, fuel injection amount setting unit 7, target EGR rate setting unit 8, engine model 12, target EGR flow rate calculation unit 13, in-cylinder pressure sensor 15,
F / F minute target EGR valve opening calculation unit 16, target EGR valve opening calculation unit 17, F / B target EGR valve opening calculation unit 18,
The actual EGR rate estimation unit 19, the first map selection unit 20, the combustion start timing detection unit 21, the maximum in-cylinder pressure detection unit 22, the fuel injection timing search unit 23, the second map selection unit 24, the actual EGR rate search unit 25. . The configurations of reference numerals 1 to 13 have the same configurations and operations as those of the above-described first and second conventional examples, and thus description thereof will be omitted.

The in-cylinder pressure sensor 15 measures the pressure inside the cylinder. The F / F minute target EGR valve opening calculation unit 16 performs exactly the same processing as the target EGR valve opening calculation unit 14 of the second embodiment. However, what is output is the target EGR valve opening degree for F / F. Target EGR valve opening calculation unit 17
Then, the output of the F / F minute target EGR valve opening calculation unit 16
The output of the target EGR valve opening calculation unit 18 for F / B is added to control the EGR valve 4 as the target EGR valve opening. In the F / B minute target EGR valve opening calculation unit 18, the target E
The PID control calculation is performed on the error between the output of the GR rate setting unit 8 and the output of the actual EGR rate estimating unit 19, and the target E for F / B is obtained.
Calculate the GR valve opening. However, other than the PID control calculation, for example, model following control may be performed. The PID control next processing will be described below. F / B
The minute target EGR valve opening calculation unit 18 is Afb_V when the target EGR rate configured by a calculation block as shown in FIG. 2 is Megr, the estimated actual EGR rate is Regr, and the F / B minute target EGR valve opening is Afb_V. Is calculated by the following formula.

Afb_V = Kd · (d / dt) · (Megr−Regr) + Kp · (Megr−Regr) + Ki · ∫ (Megr−Regr) dt (2) Here, Kd, Kp, and Ki are the operation of the engine. It may change depending on the state, or may be a constant. Kd, Kp, Ki
An example is shown in FIGS. 3 (A) (B) (C).

The actual EGR rate estimating unit 19 is a model that models the output of the in-cylinder pressure sensor 15, the output of the engine rotation angle sensor 2, the output of the fuel injection amount setting unit 7, and the combustion phenomenon inside the cylinder, or The actual EG rate is calculated using a preset map. Actual EGR rate estimation unit 1
The processing in 9 will be described in detail.

An embodiment of the actual EGR rate estimating section 19 is shown in FIG. Hereinafter, a method for estimating the actual EGR rate by map search will be described. First, FIGS. 5 (A), (B), and (C) show the outline of the relationship among the in-cylinder pressure, the fuel injection timing, the EGR rate, and the fuel injection amount. E at the same fuel injection amount and the same fuel injection timing
When only the GR rate is increased, the combustion start timing (the time from the intake bottom dead center to the start of combustion after fuel injection. Combustion start timing = fuel injection timing + ignition delay time) remains almost unchanged (T1). , The maximum cylinder pressure occurs (Pmax → P
max ') The combustion period becomes long (T2 → T2'). When the fuel injection timing is delayed with the same fuel injection amount and the same EGR rate, the combustion start time is delayed (T1 → T1 ′), the maximum in-cylinder pressure decreases (Pmax → Pmax ′), and the combustion period is long (T2 → T2). ')Become. Same fuel injection timing, same EGR
When the fuel injection amount is reduced by the rate, the combustion start timing does not change (T1) and the maximum in-cylinder pressure decreases (Pmax → Pma).
x ′), and the combustion period becomes short (T2 → T2 ′). Further, when the engine speed becomes high, even if the fuel injection amount, fuel injection timing, and EGR rate are the same, the combustion start timing is relatively delayed, and the combustion period is converted into crank angle,
become longer.

A map of the above relationships is shown in FIG.
8 shows. FIG. 6 shows the relationship between the combustion start timing and the fuel injection timing. This relationship changes depending on the engine speed.
FIG. 7 shows the relationship between the fuel injection timing, the maximum in-cylinder pressure, and the EGR rate. This relationship changes depending on the engine speed and the fuel injection amount. This is because, for example, when the fuel injection amount increases, the maximum in-cylinder pressure increases even with the same EGR rate. FIG.
Shows the relationship between the combustion period, the large cylinder pressure, and the EGR rate. This relationship changes depending on the fuel injection timing and the fuel injection amount.
This is for the same reason as the map of FIG.

Based on the above facts, the actual EGR rate estimation unit 19
The embodiment will be described with reference to FIG. First map selection unit 2
At 0, it is determined from the output of the engine rotation angle sensor 2 which map of the map A group is to be used for the fuel injection timing search. Map A group is a map for obtaining the fuel injection timing from the combustion start timing.

The combustion start timing detector 21 determines the combustion start timing (T1 in FIG. 5) from the outputs of the cylinder pressure sensor 15 and the engine rotation angle sensor. Fuel injection amount is 0
The combustion start timing is the time when a difference of a predetermined value or more occurs with respect to the change in the cylinder pressure at the time. A schematic diagram is shown in FIG.

The maximum in-cylinder pressure detector 22 determines the maximum in-cylinder pressure (Pmax in FIG. 5) from the output of the in-cylinder pressure sensor 15.

The fuel injection timing search unit 23 determines the fuel injection timing using the map selected by the first map selection unit 20 and the output of the combustion start timing detection unit 21. An example of how to determine the fuel injection timing is shown in FIG.

The second map selecting section 24 determines which map of the map B group should be used to retrieve the actual EGR rate from the output of the fuel injection amount setting section 7 and the output of the engine rotation angle sensor 2. Here, a means for measuring the fuel injection amount may be provided and the measured value may be used.

The map B group is a map set for each engine speed and fuel injection amount, and is a map for obtaining the actual EGR rate from the maximum in-cylinder pressure and fuel injection timing. Map example Figure 7
Shown in

In the actual EGR rate search section 25, the output of the maximum in-cylinder pressure detection section 22 and the output of the fuel injection timing search section 23
Using the map selected by the second map selection unit 24, the actual E
Calculate the GR rate. An example of how to determine the actual EGR rate is shown in FIG.

FIG. 10 shows the target EGR in the first embodiment.
A comparison result of the rate and the actual EGR rate by simulation is shown. Transient (4 to 4.4 sec), steady (4.4 sec)
It can be seen that both of them match better than the second conventional example.

FIG. 11 is a diagram showing a second embodiment of the present invention. First, the configuration will be described. The diesel engine EGR device according to the second embodiment includes a diesel engine 1, an engine rotation angle sensor 2, an air flow meter 3, an EGR valve 4, a fuel pump 5, an accelerator opening sensor 6, and a fuel injection. Amount setting unit 7, target EGR rate setting unit 8, engine model 12, target EGR flow rate calculation unit 13, in-cylinder pressure sensor 15, F / F minute target EGR valve opening calculation unit 16, target EGR valve opening calculation unit 17, F / B minute target EGR valve opening calculation unit 18, maximum in-cylinder pressure detection unit 22, fuel injection valve lift sensor 26, actual EGR rate estimation unit 27, fuel injection timing calculation unit 28, second map selection unit 29, actual EGR The rate search unit 30 is included. The configurations of reference numerals 1 to 22 have the same configurations and operations as those of the first embodiment, and thus the description thereof will be omitted.

The fuel injection valve lift sensor 26 measures the start of fuel injection. The actual EGR rate estimating unit 27 is a model that models the output of the in-cylinder pressure sensor 15, the output of the engine rotation angle sensor 2, the output of the fuel injection valve lift sensor 26, and the fuel phenomenon inside the cylinder, or is set in advance. The actual EGR rate is calculated using the map. FIG. 12 shows an internal schematic diagram of the actual EGR rate estimation unit 27. In the fuel injection timing calculation unit 28, the fuel injection valve lift sensor 26
The fuel injection timing is calculated from the fuel injection start time obtained from the above and the output of the engine rotation angle sensor 2.

The second map selecting section 29 determines which map of the map B group should be used to retrieve the actual EGR rate from the outputs of the fuel injection amount setting section 7 and the engine rotation angle sensor. An example of the map is shown in FIG.

In the actual EGR rate searching section 30, the map B selected by the second map selecting section 29 and the maximum in-cylinder pressure detecting section 22 are selected.
Of the fuel injection timing calculation unit 28
Calculate the GR rate.

FIG. 13 is a diagram showing a third embodiment of the present invention. First, the configuration will be described. The diesel engine EGR device according to the second embodiment includes a diesel engine 1, an engine rotation angle sensor 2, an air flow meter 3, an EGR valve 4, a fuel pump 5, an accelerator opening sensor 6, and a fuel injection. Amount setting unit 7, target EGR rate setting unit 8, engine model 12, target EGR flow rate calculation unit 13, in-cylinder pressure sensor 15, F / F minute target EGR valve opening calculation unit 16, target EGR valve opening calculation unit 17, F / B minute target EGR valve opening calculation unit 18, first map selection unit 20, combustion start timing detection unit 21, maximum in-cylinder pressure detection unit 22, fuel injection timing search unit 2
3, an actual EGR rate estimation unit 31, a combustion time search unit 32, a combustion period calculation unit 33, a second map selection unit 34, an actual EGR rate search unit 35. The configurations of reference numerals 1 to 23 are the same as the configurations and actions of the first embodiment, and thus the description thereof will be omitted.

FIG. 14 shows a schematic diagram of the internal structure of the actual EGR rate estimating section 31. The combustion time search unit 32 obtains the combustion time (T2 unit in FIG. 9 is [sec]) from the output of the fuel injection amount setting unit 7 and the output of the in-cylinder pressure sensor 15 using a map. An example of the map is shown in FIG. However, the calculation may be internally performed using a well-known simulation method of the combustion phenomenon.

The combustion period calculation unit 33 obtains the combustion period (unit: ° C / A) using the output of the combustion time search unit 32, the output of the engine rotation angle sensor 2 and the following equation.

T2 [° C / A] = T2 [sec] × N [° / sec] (3) [] is a unit of each variable.

The second map selecting section 34 determines which map of the map C group should be used to search for the actual EGR rate from the output of the engine rotation angle sensor 2 and the output of the fuel injection timing searching section 23. The map C group is a map in which the engine speed and the fuel injection timing are set, and is a map for obtaining the actual EGR rate from the maximum in-cylinder pressure and the combustion period. An example of the map is shown in FIG.

In the actual EGR rate search section 35, the map C selected by the second map selection section 34 and the maximum in-cylinder pressure detection section 22 are selected.
The actual EGR rate is obtained by using the output of 1 and the output of the combustion period calculation unit 33.

As described above, according to each of the embodiments, the configuration is such that the in-cylinder pressure sensor 15 and the actual EGR rate estimating section 19, 27, 31 for estimating the actual EGR rate based on the in-cylinder pressure sensor 15.
Since the EGR valve opening degree is corrected based on the error between the target EGR rate and the estimated actual EGR rate, the actual EGR rate can be controlled accurately even if there is a temporal change in the engine or manufacturing variations.

Further, in the first embodiment, only the in-cylinder pressure sensor 15 is added to the conventional example. Therefore, the present invention can be applied at low cost without significantly modifying the engine body.

In the second embodiment, the fuel injection timing is measured as compared with the first actual form, so that the calculation in the actual EGR rate estimating unit 27 also reduces the map capacity. for that reason,
An inexpensive controller can be used because the load on the computing capacity of the controller is lightened.

[0037]

As described above, according to the present invention, the in-cylinder pressure sensor and the actual EG for estimating the actual EGR rate based on the in-cylinder pressure sensor.
Since the EGR valve opening is corrected based on the error between the target EGR rate and the estimated actual EGR rate by the R rate estimation unit, even if there is a change over time in the engine or manufacturing variations, the actual E
The GR rate can be controlled.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a schematic diagram of processing of a target EGR valve opening degree calculation unit for F / B.

FIG. 3 is an example of a Kd, Kp, and Ki map.

FIG. 4 is a schematic diagram of an internal configuration of an actual EGR rate estimation unit 19.

FIG. 5 is a conceptual diagram of a relationship among an in-cylinder pressure, an EGR rate, a fuel injection timing, and a fuel injection amount.

FIG. 6 is an example of a map for obtaining a fuel injection timing from a combustion start timing according to the first embodiment.

FIG. 7 is an example of a map for obtaining an actual EGR rate from the fuel injection timing and the maximum in-cylinder pressure according to the first embodiment.

FIG. 8 is a map for obtaining an actual EGR rate from the maximum in-cylinder pressure and combustion injection timing according to the third embodiment.

FIG. 9 is a diagram showing changes in in-cylinder pressure due to combustion.

FIG. 10 is a diagram showing an EGR rate control simulation result in the first embodiment.

FIG. 11 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 12 is a schematic diagram of an internal configuration of an actual EGR rate estimation unit 27.

FIG. 13 is an overall configuration diagram of a third embodiment of the present invention.

FIG. 14 is a schematic diagram of an internal configuration of an actual EGR rate estimation unit 31.

FIG. 15 is an example of a map for obtaining a combustion time from a fuel injection amount.

FIG. 16 is an overall configuration diagram of a first conventional example.

FIG. 17 is an overall configuration diagram of a second conventional example.

FIG. 18 is a comparison result of the predicted EGR rate and the true EGR rate in the first conventional example.

FIG. 19 is an EGR rate simulation result when foreign matter adheres to the EGR valve in the second conventional example.

[Explanation of symbols]

 1 Diesel Engine 2 Engine Rotation Angle Sensor 3 Air Flow Meter 4 EGR Valve 5 Fuel Pump 6 Accelerator Opening Sensor 7 Fuel Injection Amount Setting Section 8 Target EGR Rate Setting Section 9 EGR Valve Opening Control Section 10 Actual EGR Rate Estimation Section 11 Cylinder Intake Gas mass flow rate estimation unit 12 Engine model 13 Target EGR flow rate calculation unit 14 EGR valve target opening calculation unit 15 In-cylinder pressure sensor 16 F / F minute target EGR valve opening calculation unit 17 Target EGR valve opening calculation unit 18 F / B Minute target EGR valve opening calculation unit 19 Actual EGR rate estimation unit 20 First map selection unit 21 Combustion start timing detection unit 22 Maximum in-cylinder pressure detection unit 23 Fuel injection timing search unit 24 Second map selection unit 25 Actual EGR rate search unit 26 Fuel Injection Valve Lift Sensor 27 Actual EGR Rate Estimator 28 Fuel Injection Timing Calculator 29 Second Map Selector 3 0 actual EGR rate search unit 31 actual EGR rate estimation unit 32 combustion time search unit 33 combustion period calculation unit 34 second map selection unit 35 actual EGR rate search unit

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Claims (10)

[Claims] 1. A target EGR rate setting unit that outputs a target EGR rate according to an operating state of a diesel engine, a target fuel setting unit that sets a target fuel injection amount based on the operating state, and a target fuel injection amount According to the fuel pump for supplying fuel to the diesel engine, the operating state and the target EG
A first target EGR valve opening calculation unit that outputs the first target EGR valve opening according to the R ratio, and a third target EGR valve opening calculation unit that adds a predetermined correction thereto.
In an EGR control device for a diesel engine, which comprises an EGR valve control unit for controlling the EGR valve according to a target EGR valve opening, a means for detecting a pressure in a combustion chamber of the diesel engine and a rotation angle of the diesel engine are detected. Means, an actual EGR rate estimation unit that estimates an actual EGR rate from information on the pressure in the combustion chamber, the rotation angle, and the fuel injection amount; and a second based on the target EGR rate and the actual EGR rate estimated value. A second target EGR valve opening calculation unit that calculates the target EGR valve opening, and based on the second target EGR valve opening, the predetermined correction is added to the first target EGR valve opening, and the third target EGR valve opening is calculated. Goal E
An EGR device for a diesel engine, comprising a target EGR valve opening correction unit that outputs a GR valve opening. 2. The diesel engine E according to claim 1.
In the GR device, the actual EGR rate estimation unit has a mathematical model of a phenomenon inside the combustion chamber, and the actual EGR ratio is estimated from the information on the model, the pressure inside the combustion chamber, the rotation angle, and the fuel injection amount.
An EGR device for a diesel engine, characterized by estimating a GR rate. 3. The diesel engine E according to claim 1.
In the GR device, the actual EGR rate estimation unit has look-up data of a phenomenon inside the combustion chamber, and based on the look-up data, the pressure inside the combustion chamber, the rotation angle, and the information about the fuel injection amount, the actual EGR rate. An EGR device for a diesel engine, which is characterized by estimating a rate. 4. The diesel engine EGR device according to claim 1, wherein the actual EGR rate estimation unit estimates the actual EGR rate by using information on a fuel injection timing. EGR device for. 5. The EGR device for a diesel engine according to claim 1, wherein in the calculation of the second target EGR valve opening degree, an error between the target EGR rate and the actual EGR rate, an integrated value of the error, and The sum of the values obtained by multiplying at least one of the sign values of the error by a desired coefficient is the second target EGR.
E for diesel engines characterized by valve opening
GR device. 6. The diesel engine E according to claim 5.
In the GR device, the desired coefficient changes according to the operating state, and the EG for diesel engine is characterized.
R device. 7. The diesel engine E according to claim 5.
An EGR device for a diesel engine, wherein the desired coefficient is a constant in the GR device. 8. The diesel engine E according to claim 1.
In the GR device, the third target EGR valve opening degree is set to the first target EGR valve opening degree.
An EGR device for a diesel engine, which is a sum of a target EGR valve opening and the second target EGR valve opening. 9. The diesel engine E according to claim 1.
In the GR device, the information on the fuel injection amount is a target fuel injection amount set by a fuel injection setting unit according to an operating state, the EGR device for a diesel engine. 10. The diesel engine EGR device according to claim 1, further comprising means for detecting a fuel injection amount supplied from the fuel pump, and using the fuel injection amount as information on the fuel injection amount. Characteristic EGR device for diesel engine.