JPH1144261A - Exhaust recirculation control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize control by an exhaust recirculation device for an internal combustion engine formed such that an exhaust recirculation flow rate is controlled based on an engine rotation speed, an engine load, and an intake amount. SOLUTION: An EGR(an Exhaust Gas Recirculation) device 29 arranged in an engine 11 comprises an EGR passage 32 to interconnect an exhaust passage 28 and an intake passage 27; and an EGR valve 33 arranged in the middle of the EGR passage 28. The EGR valve 33 regulates an amount (an EGR amount) flowing through an EGR passage. The electronic control unit (ECU) 70 corrects an intake air pressure such that a fluctuation content of an intake air pressure according to a fluctuation of an EGR amount is erased. The ECU 70 calculates the target opening of the EGR valve 33 based on a rotation speed, a fuel injection amount, and an intake air pressure after correction, and the EGR valve 33 is controlled such that a calculated target opening and an actual opening coincide with each other.

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 control device for an internal combustion engine that controls the amount of exhaust gas recirculated from an exhaust passage of the internal combustion engine to an intake passage in accordance with an engine operating state.

[0002]

2. Description of the Related Art Generally, an exhaust gas recirculation control device provided in an internal combustion engine includes an exhaust gas recirculation passage connecting an exhaust passage and an intake passage of the engine, and an exhaust gas recirculation flow control valve provided in the middle of the passage. It is configured. In this control device,
When the exhaust flow control valve is opened, part of the exhaust flowing through the exhaust passage is returned to the intake passage through the exhaust reflux passage, and is mixed with the intake air. Since this exhaust gas contains a large amount of carbon dioxide (CO2) having a large heat capacity, the combustion temperature of the air-fuel mixture in the combustion chamber is lowered, and nitrogen oxides (NOx) contained in the exhaust gas are reduced.

On the other hand, when the amount of exhaust gas returned from the exhaust passage to the intake passage becomes excessive, the combustion state tends to deteriorate and the engine output tends to decrease. Therefore, in the above control device, the ratio of the exhaust gas recirculation flow rate to the intake air (including recirculated exhaust gas) amount, that is, the EGR (Exhaust Gas Recirculation) rate, is controlled by controlling the opening degree of the exhaust gas recirculation valve. It is desirable to set an appropriate size according to the operating state.

For this reason, conventionally, the opening degree of the exhaust ring flow control valve has been controlled according to the engine speed and the engine load. By doing so, the EGR rate can be adjusted according to the engine operating state, and the NGR can be adjusted without causing extreme deterioration of the combustion state or reduction of the engine output.
Ox can be reduced.

[0005] Even when the engine speed and the engine load are constant, the intake air amount fluctuates when the outside air pressure changes or when the engine is in a transient operation state. May fluctuate. Therefore, in the above control device, in order to adjust the EGR rate to a more appropriate size, it is necessary to consider the magnitude of the intake air amount when controlling the opening degree of the exhaust ring flow control valve.

Therefore, as disclosed in JP-A-61-279767 and JP-A-7-158516, in addition to the engine speed and the engine load, the intake air amount or the intake pressure that changes in accordance with the intake air amount is controlled. There has been proposed an exhaust gas recirculation control device that controls the opening degree of the exhaust gas recirculation flow control valve based on the control. As described above, by controlling the opening degree of the exhaust gas flow control valve based on the intake air amount and the intake pressure, the EGR rate can be controlled to a value suitable for the engine operating state even when the intake air amount fluctuates. .

[0007]

However, the control device that controls the opening degree of the exhaust flow control valve based on the intake air amount and the intake pressure has the following problems.

That is, the intake air amount and the intake air pressure change according to the EGR amount, in other words, the opening degree of the exhaust ring flow control valve. Therefore, when the target opening of the exhaust flow control valve is set based on the engine rotation speed, the engine load, and the intake air amount, and the opening of the adjustment valve is changed to the target opening, the opening change , A new target opening is set based on the intake air amount that has changed in accordance with. Then, when the opening of the exhaust ring flow control valve is changed based on this target opening, a new target opening is set again.

As a result, in the above control device, there has been a problem that the control is destabilized by repeatedly changing the opening of the exhaust ring flow control valve and resetting the target opening.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an exhaust recirculation control device for an internal combustion engine which controls an exhaust recirculation flow based on an engine speed, an engine load, and an intake air amount. And to stabilize the control.

[0011]

In order to achieve the above object, the present invention provides an exhaust gas recirculation control device for an internal combustion engine.
An exhaust recirculation passage that communicates the exhaust passage and the intake passage connected to the combustion chamber of the engine, an exhaust recirculation flow control valve that is provided in the exhaust recirculation passage, and adjusts an amount of exhaust gas that recirculates from the exhaust passage to the intake passage; Engine speed detecting means for detecting the engine speed, engine load detecting means for detecting the engine load, intake air amount detecting means for detecting the amount of intake air sucked into the combustion chamber, and the opening degree of the exhaust ring flow control valve Based on the opening degree detected by the opening degree detecting means and the opening degree detected by the opening degree detecting means.
Correction means for correcting the intake air amount detected by the intake air amount detection means so that the variation due to the change in the exhaust ring flow rate is reduced, and the engine rotational speed and engine load detected by each detection means, and the corrected Target opening calculating means for calculating a target opening related to the opening of the exhaust ring flow control valve based on the intake air amount; and control means for controlling the opening of the exhaust ring flow adjusting valve based on the target opening. That is the purpose.

The intake air amount detecting means may directly detect the amount of intake air taken into the combustion chamber, such as an air flow meter, or may indirectly detect the amount of intake air from an intake pressure, such as an intake pressure sensor. The amount may be detected.

In the above configuration, the intake amount detecting means detects an amount of intake air taken into the combustion chamber, and the opening degree detecting means includes:
The opening of the exhaust ring flow control valve is detected. The correction means corrects the intake air amount based on the degree of opening of the exhaust gas flow control valve so as to cancel out the fluctuation due to the change in the exhaust gas flow. And
The target opening calculating means calculates the target opening of the exhaust ring flow control valve based on the corrected intake air amount and the engine speed and the engine load detected by the engine opening detecting means and the engine load detecting means. . Further, the control means controls the opening of the exhaust ring flow control valve based on the target opening.

As described above, according to the above configuration, the intake air amount is corrected so as to cancel the fluctuation due to the change in the exhaust air flow rate, and the target opening degree of the exhaust air flow rate adjusting valve is determined based on the corrected intake air amount. Is calculated. Therefore, even when the exhaust gas flow rate changes according to the opening degree of the exhaust gas flow rate adjustment valve, and the intake air amount fluctuates with the change, the fluctuation of the target opening degree due to the fluctuation is suppressed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a multi-cylinder diesel engine (hereinafter simply referred to as “engine”) 11 mounted on a vehicle. Engine 11
Has a cylinder block 12 in which a plurality of cylinders 14 (one of which is shown in the figure) are formed, and a cylinder head 13 assembled on the cylinder block 12. A piston 15 is housed in each cylinder 14 so as to be able to reciprocate. The piston 15 is connected to a crankshaft 17 via a connecting rod 16.

The space above the piston 15 in the cylinder 14 is a main combustion chamber 18. The same number of sub-combustion chambers 19 as the cylinders 14 are formed below the cylinder head 13, and each sub-combustion chamber 19 is connected to the corresponding main combustion chamber 18 by an injection hole 21. An injection nozzle 22 is attached to the cylinder head 13, and its tip faces the sub-combustion chamber 19. This injection nozzle 22 is connected to a fuel injection pump 23 by a fuel conduit 24.

The fuel injection pump 23 is a well-known distribution pump, and its drive shaft 23a is drivingly connected to the crankshaft 17. The fuel injection pump 23 is driven by the rotation of the crankshaft 17 to supply the fuel to the injection nozzle 22 in an amount corresponding to the engine load. The fuel injection pump 23 includes a timer device for adjusting the fuel injection timing, a solenoid valve for adjusting the fuel injection amount (both not shown), and the like.

Each of the main combustion chambers 18 has a cylinder head 13.
, An intake port (not shown) and an exhaust port 25 are formed. In addition, an intake valve (not shown) and an exhaust valve 26 are supported on the cylinder head 13 so as to be reciprocally movable, and the intake and exhaust ports 25 are opened and closed by the reciprocating movement. Furthermore, the cylinder head 1
3 is connected to an intake passage 27 communicating with the intake port and an exhaust passage 28 communicating with the exhaust port 25.

The engine 11 has an exhaust gas recirculation (EGR: Exha
ust Gas Recirculation) control device (hereinafter abbreviated as “EGR device”) 29 is provided. The EGR device 29 connects the exhaust passage 28 and the intake passage 27 to each other.
The vehicle includes a GR passage 32 and an EGR valve 33 provided in the middle of the EGR passage 32.

The EGR valve 33 includes a valve body 36 and a valve body 3
The valve seat 6 includes a valve seat 38 for taking off and seating, a diaphragm (not shown) connected to the valve body 36, and a negative pressure chamber (not shown) partitioned by the diaphragm. This negative pressure chamber is connected to a negative pressure pump (not shown) via a negative pressure adjusting valve 39. The negative pressure adjusting valve 39 is an electromagnetic valve operated by an electric signal, and adjusts a negative pressure supplied from the negative pressure pump and acting on the negative pressure chamber to a magnitude corresponding to the electric signal.

In the EGR device 29, the magnitude of the negative pressure in the negative pressure chamber is adjusted by the negative pressure adjusting valve 39, and the diaphragm bends in response to the negative pressure, whereby the valve body 36 reciprocates. . The opening between the EGR valve 33 is adjusted by adjusting the distance between the valve body 36 and the valve seat 38 in accordance with the reciprocating movement. The amount of exhaust gas recirculated from the exhaust passage 28 to the intake passage 27 through the EGR passage 32, that is, the EGR amount is determined according to the opening of the EGR valve 33.

In the EGR device 29 according to the present embodiment, the exhaust gas is recirculated only when the engine 11 is operating at a low load or a medium load, and is stopped when the engine 11 is operating at a high load. This is because, at the time of high-load operation, the exhaust gas is recirculated into the intake passage 27, so that the amount of intake air (the amount of oxygen used for combustion) becomes insufficient and black smoke may be emitted. Here, the high load in the present embodiment refers to a time when the accelerator pedal 41 provided in the driver's seat is greatly depressed, for example, a state where the accelerator opening degree indicating the degree of depression is 70% or more. Can be

A partition wall 42 extending in the flow direction of the intake air is provided upstream of the portion where the EGR passage 32 is connected in the intake passage 27. Due to the partition wall 42, a part of the intake passage 27 is partially
The main flow path 43 is divided into a sub flow path 44 having a smaller flow sectional area than the main flow path 43.

A main intake throttle valve 45 is rotatably supported in the main flow path 43. The main intake throttle valve 45 is connected to the wire 4
7, and is connected to the accelerator pedal 41, and rotates in conjunction with depression of the accelerator pedal 41.

On the other hand, a sub intake throttle valve 48 is rotatably supported in the sub flow path 44. The auxiliary intake throttle valve 48 is connected to a diaphragm type actuator 51.
A negative pressure chamber (not shown) in the actuator 51 is connected to a negative pressure pump via a negative pressure adjusting valve 52. The negative pressure adjusting valve 52 switches the opening degree of the auxiliary intake throttle valve 48 to a fully closed state, a half open state, or a fully open state by adjusting the negative pressure acting on the negative pressure chamber.

The engine 11 includes a turbocharger 53
Is installed. The turbocharger 53 is constituted by a turbine 55 arranged in the exhaust passage 28, a compressor 54 arranged in the intake passage 27, and a shaft 56 connecting the two 54, 55. In the turbocharger 53, the turbine 5
By rotating the compressor 5 and driving the compressor 54, the intake air flowing through the intake passage 27 is compressed, and the intake air pressurized to the atmospheric pressure or more is supplied into each of the combustion chambers 18, 19. Further, the engine 11 is provided with a waste gate valve 57 for adjusting the supercharging pressure of the turbocharger 53. This waste gate valve 5
The valve 7 is opened when the supercharging pressure of the turbocharger 53 exceeds the set pressure, thereby maintaining the supercharged pressure at or below the set pressure.

Further, the engine 11 is provided with various sensors for detecting its operating state. The fuel injection pump 23 has a built-in rotation speed sensor 60 that detects the rotation speed of the drive shaft 23a to detect the rotation speed of the crankshaft 17, that is, the rotation speed NE of the engine. The cylinder block 12 detects the temperature of the cooling water (cooling water temperature) THW,
A water temperature sensor 61 that outputs a signal corresponding to the temperature is attached.

In the intake passage 27, each intake throttle valve 45,
Downstream of the intake pressure P in the intake passage 27,
An intake pressure sensor 62 that detects IM and outputs a signal corresponding to the intake pressure PIM is provided. This intake pressure PIM
Has a correlation with the amount of intake air (intake amount) introduced into each of the combustion chambers 18 and 19, and the intake amount increases as the intake pressure PIM increases. Further, the intake pressure sensor 62 detects the pressure of intake air after being supercharged by the turbocharger 53.

In the vicinity of the main intake throttle valve 45, there is provided an accelerator sensor 63 for detecting the amount of depression of the accelerator pedal 41, that is, the accelerator opening ACCP from the opening of the throttle valve 45. The EGR valve 33 is provided with an opening sensor 64 for detecting the opening of the EGR valve 33. The opening degree sensor 64 detects the position of the valve body 36 in the reciprocating direction so that the EGR valve 33
Of the actual opening degree ELACT is detected.

Each of these sensors 60 to 64 is connected to an electronic control unit (hereinafter referred to as “ECU”) 70 provided in the vehicle. The ECU 70 has a rotation speed NE, a cooling water temperature THW, an intake pressure PIM, and an accelerator opening. A detection signal corresponding to the degree ACCP and the actual opening degree ELACT is output.

The ECU 70 includes a central processing unit (CPU) for performing arithmetic processing, a read-only memory (ROM) in which a predetermined control program and function data are stored in advance, a CPU
A random access memory (RAM) for temporarily storing the calculation results and the like, an input circuit to which the sensors 60 to 64, etc. are connected, the negative pressure regulating valves 39, 52, the timer device of the fuel injection pump 23, and the solenoid valve Output circuits and the like to be connected are connected by a bus. The ECU 70
By controlling the negative pressure regulating valves 39 and 52, the fuel injection pump 23 and the like based on the detection signals from the sensors 60 to 64, EGR amount control, intake throttle control, fuel injection timing control, fuel injection amount control, etc. Execute

Next, a control procedure relating to the EGR amount control of the present embodiment will be described. FIG. 2 is a flowchart showing a processing routine for controlling the EGR amount. ECU
70 executes this processing routine at predetermined time intervals (for example, “8
ms ”).

In step 100 shown in FIG.
U70 is a rotational speed NE, an intake pressure PIM, and an actual opening ELACT of the EGR valve 33 based on detection signals from the rotational speed sensor 60, the intake pressure sensor 62, and the opening sensor 64.
And the fuel injection amount QFIN stored in the RAM of the ECU 70 is read.

The fuel injection amount QFIN is an amount of fuel supplied from the fuel injection pump 23 to the injection nozzle 22, and corresponds to an engine load in the present embodiment. The fuel injection amount QFIN is calculated based on the accelerator opening ACCP and the rotation speed NE in another fuel injection amount control routine (not shown), and is stored in the RAM of the ECU 70. In this embodiment, the engine speed detecting means is constituted by the rotational speed sensor 60 and the accelerator sensor 63.

Next, at step 102, the ECU 7
0 calculates the basic opening degree ELBSE based on the rotation speed NE and the fuel injection amount QFIN. This basic opening ELBSE
Is a reference when controlling the opening of the EGR valve 33, and is determined without considering the magnitude of the intake pressure PIM. The ROM of the ECU 70 stores function data defining the relationship between the rotation speed NE, the fuel injection amount QFIN, and the basic opening degree ELBSE.
The function data is referred to when calculating the basic opening degree ELBSE.

FIG. 3 is a graph showing the function data. As shown in the figure, the engine 1 fuel injection amount QFIN
It can be understood that the basic opening degree ELBSE is calculated to be smaller and the EGR amount is smaller at the time of a high load operation in which is larger.
The basic opening degree ELBS increases as the rotation speed NE increases.
Although E is calculated to be large, when the rotational speed NE becomes extremely high, the basic opening degree ELBSE is calculated to be small. This is because in a high rotation speed region, the amount of intake air (the amount of oxygen supplied to combustion) is generally insufficient, and black smoke tends to be generated.

In the following step 104, the ECU 70
Calculates a steady intake pressure PIMST based on the rotation speed NE and the fuel injection amount QFIN. This steady intake pressure PIMS
T corresponds to the intake pressure when the operating state of the engine 11 is in a steady state and the EGR amount is “0”. The ROM of the ECU 70 stores function data defining the relationship between the rotational speed NE, the fuel injection amount QFIN, and the steady-state intake pressure PIMST.
This function data is referred to when calculating the steady intake pressure PIMST.

FIG. 4 is a graph showing the function data. As shown in the figure, as the rotational speed NE or the fuel injection amount QFIN increases, the steady intake pressure PIMST is calculated to a larger value. The relationship among the rotational speed NE, the fuel injection amount QFIN, and the steady intake pressure PIMST changes based on the throttle opening characteristic and the supercharging characteristic of the turbocharger 53.

Next, at step 106, the ECU 7
0 calculates the intake pressure correction term PIME based on the actual opening ELACT and the rotation speed NE. Hereinafter, the intake pressure correction term PIME will be described. The engine 11 is provided with a turbocharger 53.
The intake air compressed by 3 is introduced into each combustion chamber 18, 19. Here, the EGR valve 33 is opened, and a part of the exhaust gas flows through the EGR passage 32 to the intake passage 27.
, The energy of the exhaust gas available in the turbocharger 53 decreases. Therefore, the intake pressure PIM
Will decrease as the EGR amount increases, in other words, as the actual opening degree ELACT of the EGR valve 33 increases. The intake pressure correction term PIM is a change (decrease) in the intake pressure PIM caused by the exhaust gas recirculation.
This is for correcting so as to cancel out.

The ROM of the ECU 70 stores the actual opening degree ELAC.
Function data defining the relationship between T and the rotational speed NE and the intake pressure correction term PIM is stored. The ECU 70
The function data is referred to when calculating the intake pressure correction term PIME.

FIG. 5 is a graph showing the function data. As shown in the figure, the intake pressure correction term PIME is EG
The larger the actual opening ELACT of the R valve 33 is, the larger the calculated value is. The reason why the intake pressure correction term PIM is calculated as described above is that, as described above, the larger the actual opening degree ELACT, the larger the EGR amount and the larger the intake pressure PIM.

When the rotational speed NE is a predetermined value (for example, 25
When the supercharging pressure of the turbocharger 53 is low, the intake pressure correction term PIME is calculated to be smaller as the rotation speed NE is lower. The reason why the intake pressure correction term PIME is calculated in this manner is that the rotation speed N
This is because the smaller the E is, that is, the lower the supercharging pressure of the turbocharger 53 is, the smaller the reduction amount of the intake pressure PIM accompanying the exhaust recirculation becomes.

Next, at step 108, the ECU 7
0 is a pressure ratio PCM based on the following equation (1) from the steady intake pressure PIMST, the intake pressure PIM, and the intake pressure correction term PIM.
Calculate P.

PCMP = (PIM + PIME) / PIMST (1) As is apparent from the above equation (1), when calculating the pressure ratio PCMP, the intake pressure PIM and the intake pressure correction term PI
The correction is made so that the fluctuation due to the change in the EGR amount is canceled by the addition of the ME. Therefore, E
Even if the intake pressure PIM fluctuates with a change in the GR amount, the pressure ratio PCMP is not affected by the fluctuation, and is maintained at a constant value.

In the following step 110, the ECU 70
Calculates the opening correction term ELPIM based on the pressure ratio PCMP and the rotation speed NE. The opening correction term ELPIM is the intake pressure (PIM + P) after correcting the basic opening ELBSE.
This is a correction term for correcting the EGR valve 33 by subtracting the opening correction term ELPIM from the basic opening ELBSE, as described later.
The target opening ELTRG is calculated.

The ROM of the ECU 70 stores function data defining the relationship between the opening correction term ELPIM and the rotational speed NE and pressure ratio PCMP. ECU 70
Refers to this function data when calculating the opening correction term ELPIM.

FIG. 6 is a graph showing the function data. As shown in the figure, the opening degree correction term ELPIM is set such that the smaller the pressure ratio PCMP, that is, the steady intake pressure PIMST
Is calculated to be larger as the corrected intake pressure (PIM + PIME) is smaller. Thus, the opening correction term ELPI
The reason for calculating M is that the smaller the pressure ratio PCMP, the smaller the amount of intake air introduced into each of the combustion chambers 18 and 19 (the amount of oxygen supplied for combustion). Is required to be reduced.

The opening correction term ELPIM is equal to the rotation speed N.
The smaller the value of E, the larger the calculated value. The reason why the opening degree correction term ELPIM is calculated in this manner is that the rotation speed NE
Is smaller, the combustion state of the engine 11 becomes unstable and black smoke tends to be generated. Therefore, it is necessary to reduce the EGR amount in order to stabilize the combustion state.

Next, at step 112, the ECU 7
0 calculates the target opening ELTRG from the basic opening ELBSE and the opening correction term ELPIM based on the following equation (2). ELTRG = ELBSE-ELPIM ...
(2) Then, in step 114, the ECU 70 generates a control signal based on the target opening ELTRG and outputs the control signal to the negative pressure regulating valve 39, whereby E
The opening of the GR valve 33 is controlled so as to match the target opening ELTRG. After executing the processing of step 114, the ECU 70 once ends the processing of this routine.

Next, a control mode of the EGR amount control in the present embodiment will be described with reference to a time chart shown in FIG. FIGS. 7A to 7C show temporal changes in the actual opening ELACT, the intake pressure PIM, and the fuel injection amount QFIN when the EGR amount is controlled based on the control procedure of the present embodiment. .

FIGS. 8A to 8C show actual values obtained when the intake pressure PIM is not corrected by using the intake pressure correction term PIM when the pressure ratio PCMP is calculated in step 108 described above. Opening ELACT, intake pressure PIM,
And a temporal change in the fuel injection amount QFIN are shown as comparative examples.

As shown in FIG. 7 and FIG.
1, when the fuel injection amount QFIN decreases and the basic opening ELBSE is calculated to be larger, the target opening ELT
RG is changed to a larger value. As a result, in the period from timing t1 to timing t2 shown in FIGS. 7 and 8, the actual opening ELACT increases, and the EGR amount increases with the increase.

Here, in the comparative example, when the intake pressure PIM decreases as shown in FIG. 8 (b) with an increase in the EGR amount, the target opening degree E increases in accordance with the decrease in the intake pressure PIM.
LTRG is changed to a smaller value. Therefore, in the comparative example, as shown in FIG.
Thereafter, the actual opening ELACT starts to decrease. As a result, the EGR amount decreases with the decrease in the actual opening ELACT,
The intake pressure PIM increases. Then, the target opening ELTRG is changed to a larger value in accordance with the increase of the intake pressure PIM.
LACT increases.

As described above, in the comparative example, the target opening degree ELT is changed according to the change in the intake pressure PIM accompanying the change in the EGR amount.
Since the RG is changed, a hunting phenomenon in which the actual opening degree ELACT fluctuates occurs, and it becomes difficult to stably control the EGR amount.

In this regard, in the present embodiment, as described above, the intake pressure PIM is corrected so as to cancel out the fluctuation caused by the change in the EGR amount. Then, based on the corrected intake pressure (PIM + PIME), the pressure ratio PCMP
Is calculated, and the target opening ELTRG is calculated using the opening correction term ELPIM based on the pressure ratio PCMP. Therefore, even if the intake pressure PIM fluctuates with a change in the EGR amount, the target opening ELTRG does not fluctuate due to the influence of the change, and the target opening ELTRG is controlled by the rotation speed NE and the fuel injection amount. It is kept at a predetermined value based on QFIN and the corrected intake pressure (PIM + PIME).
Therefore, as shown in FIG. 7A, after the timing t2, the actual opening ELACT quickly converges to the predetermined target opening ELTRG. As a result, according to the present embodiment, the EGR amount control can be stabilized.

Further, in the present embodiment, the actual opening degree ELACT
And the intake pressure correction term PI based on the rotational speed NE
ME is calculated. Therefore, the change in the supercharging pressure in the turbocharger 53 is taken into consideration, and the intake pressure correction term PIM can be made to match the variation in the intake pressure PIM due to the change in the EGR amount. As a result, according to the present embodiment, it is possible to reliably suppress the change in the target opening ELTRG due to the change in the EGR amount.
GR amount control can be further stabilized.

The above embodiment can be implemented by changing the configuration as follows. In the above embodiment, the present invention is applied to the diesel engine 11
However, the present invention can also be applied to an EGR device of a gasoline engine.

In the above embodiment, when calculating the basic opening degree ELBSE of the EGR valve 33, the fuel injection amount QFIN is used as the amount corresponding to the engine load.
For example, the intake air amount Q is detected by an air flow meter, and an amount obtained by dividing the intake air amount Q by the rotation speed NE (Q / NE) can be used as the engine load.

In the above embodiment, the intake pressure correction term PIM
Although E is calculated based on the actual opening ELACT and the rotation speed NE, it may be calculated based only on the actual opening ELACT.

In the above embodiment, the engine 11 is provided with the turbocharger 53 as a supercharger.
A supercharger may be provided instead of, or in addition to, the turbocharger 53.

In the above embodiment, the intake air amount detecting means according to the present invention is constituted by the intake air pressure sensor 62. However, the intake air amount sensor may be constituted by an air flow meter instead of the intake air pressure sensor 62.

In the above embodiment, the opening of the EGR valve 33 is adjusted by controlling the negative pressure adjusting valve 39, and the actual opening ELACT of the EGR valve 33 is detected by the opening sensor 64. . On the other hand, the opening degree of the EGR valve may be adjusted using a stepping motor. In this configuration, EC
Since the opening of the EGR valve can be determined based on the number of pulse signals output from the U to the stepping motor, a sensor for detecting the opening of the EGR valve is not required. In this configuration, the ECU that detects the opening of the EGR valve based on the number of pulse signals corresponds to the opening detecting means in the present invention.

[0063]

According to the present invention, the intake air amount is corrected so as to cancel out the fluctuation due to the change of the exhaust air flow amount, and the exhaust air flow amount adjusting valve is adjusted based on the corrected intake air amount, the engine speed and the engine load. Is calculated. Therefore, even when the exhaust gas flow rate changes according to the opening degree of the exhaust gas flow rate adjustment valve, and the intake air amount fluctuates with the change, the fluctuation of the target opening degree due to the fluctuation is suppressed. As a result, according to the present invention, it is possible to stabilize the exhaust gas recirculation control.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of an EGR device and the like according to an embodiment.

FIG. 2 is a flowchart showing a control procedure relating to EGR amount control.

FIG. 3 is a graph illustrating a relationship between a fuel injection amount, a rotation speed, and a basic opening degree.

FIG. 4 is a graph illustrating a relationship between a fuel injection amount, a rotation speed, and a steady intake pressure.

FIG. 5 is a graph illustrating a relationship between an actual opening degree and a rotation speed of an EGR valve and an intake pressure correction term.

FIG. 6 is a graph illustrating a relationship between a pressure ratio, a rotation speed, and an opening degree correction term.

FIG. 7 is a time chart illustrating a control mode according to the embodiment.

FIG. 8 is a time chart illustrating a control mode in a comparative example.

[Explanation of symbols]

11 ... Diesel engine, 18 ... Main combustion chamber, 19 ... Sub combustion chamber, 27 ... Intake passage, 28 ... Exhaust passage, 32 ... EG
R passage, 33: EGR valve, 39: negative pressure regulating valve, 60
... Rotation speed sensor, 61 ... Water temperature sensor, 62 ... Intake pressure sensor, 63 ... Accelerator sensor, 64 ... Opening degree sensor, 70
... ECU.

Claims (1)

[Claims] 1. An exhaust recirculation passage communicating with an exhaust passage and an intake passage connected to a combustion chamber of an internal combustion engine, and an amount of exhaust gas provided in the exhaust recirculation passage and flowing from the exhaust passage to the intake passage is adjusted. An exhaust ring flow rate adjusting valve, an engine speed detecting means for detecting an engine speed, an engine load detecting means for detecting an engine load, and an intake amount detecting means for detecting an amount of intake air sucked into the combustion chamber. An opening detecting means for detecting an opening of the exhaust ring flow control valve; and correcting the detected intake air amount based on the detected opening to cancel a variation due to a change in the exhaust ring flow. Correction means; target opening degree calculation means for calculating a target opening degree of the exhaust ring flow control valve based on the detected engine speed and engine load and the corrected intake air amount; Goals Exhaust gas recirculation control apparatus for an internal combustion engine and a control means for controlling the opening degree of the exhaust gas recirculation amount adjusting valve based on the time.