JPH09119350A - Exhaust gas circulation controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide compatibility between safety in the stationary time and follow-up performance in the transient time by controlling the reference opening of an EGR valve, calculated according to the engine operating state so that the reference opening may be the weight-averaged opening by changing the weighting ratio in the stationary time and in the transient time to be judged on the basis of the differential pressure between exhaust system pressure and intake system pressure. SOLUTION: When an EGR valve 9 interposed in an EGR passage 10 for connecting an exhaust manifold 8 to an intake manifold 4 is controlled by a control unit 13, the reference opening of the EGR valve is calculated on the basis of the operating state of an engine, namely, the output of an air flow meter 16 and a rotational speed sensor 17. The weighting ratio in calculating of the opening of the EGR valve 9 by weighted average of the last weighted average value and the recently calculated reference opening is calculated according to the change of the engine operating state. The last weighted average value and the recently calculated reference opening value are weight-averaged on the basis of the weighting ratio, and the opening of the EGR valve 9 is so controlled as to be the weight-averaged EGR valve opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to exhaust gas recirculation of an internal combustion engine.
The present invention relates to an (EGR) control device, and more particularly to a technique for achieving both steady stability and transient followability.

[0002]

2. Description of the Related Art Generally, in a vehicle internal combustion engine, NO
An EGR control device that recirculates a part of the exhaust gas to the intake system is used to reduce x. As an EGR control device for a diesel engine, as disclosed in Japanese Patent Application Laid-Open No. 64-66447, a control amount of an EGR valve opening which is preset in a map for each engine operating state is searched to search for the EGR valve. Is generally controlled.

[0003]

However, in such an EGR control system, there are variations in turbocharger differentials such as transient optimization and turbocharged engines. However, in that case, the exhaust gas purification performance may be affected. The present invention has been made in view of such a conventional situation, and switches the weight in the weighted average processing of the EGR valve opening degree control amount between the steady state and the transient state to achieve steady stability and transient followability. Aim to be compatible.

[0004]

Therefore, according to the invention of claim 1, as shown in FIG. 1, exhaust gas is exhausted through an EGR valve provided in an EGR passage connecting an exhaust system and an intake system of an engine. In an exhaust gas recirculation control device for an internal combustion engine that recirculates a part of the above to an intake system, an operating state detecting means for detecting an operating state of the engine and a basic opening for calculating a basic opening degree of the EGR valve according to the operating state of the engine Degree calculating means, operating state change detecting means for detecting a change in the detected engine operating state, and a weighted average of a past weighted average value and the most recently calculated basic opening degree. And a weight ratio calculating means for calculating a weight ratio for calculating the change of the detected engine operating state, and an opening degree of the EGR valve based on the calculated weight ratio. Value and the most recently calculated base A weighted average processing means for performing a weighted average processing of the opening degree value, and an EGR valve drive means for driving the EGR valve so that the opening degree of the weighted averaged EGR valve is included. .

In this way, the basic opening degree of the EGR valve calculated according to the operating state of the engine is weighted by changing the weight ratio between the steady state and the transient state which are determined according to the change of the operating state. Since the opening degree of the EGR valve is controlled so as to have an averaged opening degree, the EGR control that achieves both the stability during steady state and the followability during transition is performed. Further, in the invention according to claim 2, the weight ratio calculating means decreases the weight of the past weighted average value as the detected change in the operating state is larger, and calculates the latest basic opening degree of the EGR valve. The feature is that the calculation is performed to increase the weight.

[0006] In this way, the following performance can be secured by reducing the weight of the weighted average value in the past and increasing the weight of the basic opening of the EGR valve calculated most recently during a transition in which the change in the operating state is large. On the contrary, in a steady state where the change in the operating state is small, the weight can be secured by increasing the weight of the past weighted average value and decreasing the weight of the most recently calculated basic opening of the EGR valve.

Further, the invention according to claim 3 is characterized in that the operating state change detecting means detects a change in the operating state of the engine based on a change in the accelerator opening. By doing so, it is possible to detect a change in the operating state of the engine easily and with good responsiveness.

Further, the invention according to claim 4 is such that the EGR passage interposed between the exhaust system and the intake system of the engine is connected to the EGR passage.
In an exhaust gas recirculation control device for an internal combustion engine, which recirculates a part of exhaust gas to an intake system via a valve, an operating state detecting means for detecting an operating state of the engine, and the EGR valve according to the detected operating state of the engine. Basic opening calculation means for calculating the basic opening of the engine, exhaust system pressure detection means for detecting the pressure of the exhaust system of the engine, intake system pressure detection means for detecting the pressure of the intake system of the engine, and past weighted average A weighted ratio when calculating the opening of the EGR valve by a weighted average of the value and the most recently calculated basic opening, based on the detected differential pressure between the exhaust system pressure and the intake system pressure of the engine. And a weighted average of the opening degree of the EGR valve, the weighted average value of the past weighted average value and the most recently calculated basic opening degree value of the opening degree of the EGR valve is calculated. Processing means and the weighted averaged E And EGR valve driving means for driving the EGR valve so that the opening degree of the R valves, that configured to include the features.

With this configuration, the basic opening degree of the EGR valve calculated according to the operating state of the engine is determined depending on the pressure difference between the exhaust system pressure and the intake system pressure, that is, in the steady state and in the transient state. EGR so that the weighted average is changed by changing the weight ratio.
Since the opening degree of the valve is controlled, EGR control that achieves both stability during steady state and followability during transition is performed. Further, in the invention according to claim 5, the weight ratio calculating means decreases the weight of the past weighted average value as the differential pressure between the exhaust system pressure and the intake system pressure of the engine is larger, and the latest calculated EGR is performed.
The calculation is performed so that the weight of the basic opening of the valve is increased.

By doing so, the weight of the weighted average value in the past is reduced and the weight of the basic opening degree of the latest calculated EGR valve is increased during the transition in which the differential pressure between the exhaust system pressure and the intake system pressure is large. In the steady state in which the differential pressure is small, the weighting of the weighted average value in the past is increased and the weighting of the basic opening degree of the EGR valve calculated most recently is decreased to ensure the stability.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3 showing the overall configuration of the embodiment, the supercharger 1 uses an air compressor 2 to remove air from the air filter 2 and suck the air taken into the intake passage 3 into an intake compressor 1A.
, And is fed into the downstream intake manifold 4.

On the other hand, to the fuel injection nozzle 6 mounted in the combustion chamber of the engine 5, fuel is pressure-fed by the injection pump 7 to each cylinder, and the fuel is supplied from the fuel injection nozzle 6 toward the combustion chamber. The injected fuel is ignited and burned at the end of the compression stroke. In addition, an EG in which the exhaust manifold 8 and the intake manifold 4 are connected and an EGR valve 9 is interposed
The R passage 10 is connected, and the throttle valve 31 for facilitating EGR by increasing the differential pressure between the exhaust pressure and the intake pressure by throttling the intake during EGR control on the upstream side of the intake compressor 1A in the intake passage 3. The throttle valve 31 is throttled to improve the exhaust gas and prevent noise, mainly at the time of idling or at low load, and at the same time, the opening degree of the EGR valve 9 is controlled to perform EGR control. Specifically, the vacuum pump 1
The negative pressure from 1 is passed through the solenoid valve 32 to the diaphragm device 3
3 to throttle the throttle valve 31, and at the same time, control the pressure introduced into the pressure chamber of the EGR valve 9 by controlling the dilution ratio of the negative pressure to the atmosphere by the duty-controlled solenoid valve 12. EG by controlling the opening
R rate is controlled. The EGR rate and the fuel injection control are performed by the control unit 13.

The EGR valve 9 is provided with a lift sensor 34 for detecting the lift amount of the valve body. After the combustion, the exhaust turbine 1B of the supercharger 1 is driven to rotate by the exhaust manifold 8, and the particulates (exhaust particulates) and the like contained in the exhaust are collected by the filter 14 and silenced by the muffler 15. After being released into the atmosphere.

An air flow meter 16 for detecting the intake air flow rate is provided in the intake passage 3 upstream of the intake compressor 1A of the supercharger 1, a rotation speed sensor 17 for detecting an engine rotation speed Ne, and the fuel injection. A lever opening sensor 18, which detects the control lever opening of the pump 7,
A water temperature sensor 19 for detecting the water temperature is provided, and the opening degree of the EGR valve 9 is set on the basis of these detected values, and the EGR valve 9 is driven so as to reach the opening degree to perform EGR control.

Various calculations by the control unit 13 will be described below. First, a routine for calculating the intake system pressure (hereinafter referred to as intake pressure) Pm will be described with reference to the flowchart of FIG. This routine corresponds to the intake system pressure detecting means in the inventions according to claims 4 and 5. In step (denoted as S in the figure. The same applies to the following), at 1, the intake air amount Qac per cylinder and the intake EG per cylinder calculated in a separate routine described later.
The R amount Qec, the intake air temperature Ta, the EGR temperature Te, and the volumetric efficiency equivalent value Kin are input.

In step 2, the intake pressure Pm is calculated by the following equation based on each value input in step 1 and the volume ratio (volume per cylinder / collector volume of the intake system) Kvol known in advance. . Pm = R / Kvol / Kin × (Qac × Ta + Qec
XTe) Next, a routine for calculating the exhaust system pressure (EGR outlet pressure, hereinafter referred to as exhaust pressure) Pexh will be described with reference to the flowchart of FIG. This routine corresponds to the exhaust system pressure detecting means in the inventions according to claims 4 and 5.

In step 11, the exhaust amount Qe discharged from one cylinder, which is calculated in another routine described later, is used.
Input xh, intake EGR amount Qec per cylinder, exhaust temperature Texh, and engine speed Ne. Step 12
Then, each value entered in step 11 and the constant Kpexh,
Opexh and the exhaust pressure Pexh by the following equation based on
Is calculated.

Pexh = (Qexh-Qe) × Texh
× Ne × Kpexh + Opexh FIG. 6 shows a flowchart for calculating an intake air amount per cylinder (hereinafter referred to as cylinder intake air amount) Qac. Incidentally, this routine constitutes a cylinder intake air amount calculation means. In step 21, the air flow meter 16
Read the output value (voltage) Q ₀ of the intake air flow rate by.

In step 22, the intake air flow rate Qasm is obtained from the output value Q _{0 using a} conversion table. In step 23, a weighted average process is performed on the intake air flow rate Qasm to obtain Qas0. In step 24, the engine rotation speed Ne detected by the rotation speed sensor 17 is read.

In step 25, the cylinder intake air amount Qac0 for the intake air flow rate detected by the air flow meter 16 is calculated from the weighted average value Qas0 of the intake air flow rate, the engine speed Ne and the constant KCON # by the following equation. . Qac0 = Qas0 / Ne × KCON # In step 26, the intake air amount Qac per cylinder is
The delay processing is performed for 0 times n times, and the intake air amount Qacn at the intake collector inlet is calculated. Specifically, the Qac0 from the latest to the past n times before is stored, and the Qac0 value n times before is taken out as Qacn.

In step 27, the intake air amount Qac per cylinder is calculated by the following equation using the constant Kvol and the volumetric efficiency equivalent value Kin. Qac = Qac _n-1 x (1-Kvol x Kin) + Qa
cn × Kvol × Kin In this way, the intake air amount Qac per cylinder can be accurately obtained.

Next, the intake E per cylinder during EGR control
A routine for calculating the GR amount will be described with reference to the flowchart of FIG. Note that this routine is a cylinder intake EG
It constitutes an R amount calculation means. In step 31, the EGR flow rate Qe to the intake system calculated by the routine described later.
Enter

In step 32, the engine speed Ne is read. In step 33, the EGR amount Qecn per cylinder volume sucked into the intake collector is calculated from the EGR amount Qe and the engine rotation speed Ne. Step 3
In 4, the cylinder EGR amount Qec sucked into the cylinder is calculated by the following equation using the constant Kvol and the volume efficiency equivalent value Kin.

Qec = Qec _n-1 × (1-Kvol × K
in) + Qecn × Kvol × Kin FIG. 8 is a flowchart of a routine for calculating the temperature Ta of intake air (fresh air not containing EGR gas). still,
This process is unnecessary when the sensor has a sensor that directly detects the intake air temperature.

In step 41, the intake pressure Pm _n-1 obtained last time is input. In step 42, the intake air temperature Ta is calculated from the relationship of adiabatic change according to the following equation. Ta = TA # × (Pmn _-1 / PA #) ^{(K-1) / K} + TOF
F # Here, TA # and PA # are the temperature and pressure in the standard state, and TOFF # is the temperature increase from the atmosphere until the air enters the intake collector. These values are corrected according to the water temperature and the like. You may.

FIG. 9 is a flowchart of a routine for calculating the temperature Te at the inlet of the EGR gas to the intake collector. In step 51, the exhaust gas temperature Texh obtained in the routine described later is input. In step 52, the EGR temperature Te is calculated by the following equation.

Te = Texh × KTLOS # KTLOS # is a temperature reduction coefficient of EGR by the EGR passage. FIG. 10 is a flowchart of a routine for calculating the volumetric efficiency equivalent value Kin. It should be noted that this routine constitutes the volumetric efficiency equivalent value calculating means. In step 61, the intake pressure Pmn _-1 obtained last time is input.

In step 62, a pressure correction coefficient K is calculated from the intake pressure Pm _n-1 using a table as shown in FIG.
Calculate inp. In step 63, the engine speed Ne
Then, the rotation correction coefficient Kinn is calculated using a table as shown in FIG. In step 64, the volumetric efficiency Kin is calculated by the following equation using the pressure correction coefficient Kinp and the rotation correction coefficient Kinn.

Kin = Kinp × Kinn FIG. 13 is a flowchart of a routine for calculating the exhaust gas temperature Texh at the EGR outlet. It should be noted that this process is unnecessary when the sensor has a sensor for directly detecting the exhaust temperature.
In step 71, the fuel injection amount Qfo injected retrospectively by the cycle delay from the fuel injection in the intake stroke to the exhaust stroke is input.

In step 72, the intake air temperature Tno calculated retroactively by the same cycle delay as described above is input. In step 73, the exhaust pressure Pexh _n-1 calculated in FIG.
Enter In step 74, the basic exhaust gas temperature Texhb is retrieved from the table as shown in FIG. 14 from the cycle delay fuel injection amount Qfo.

In step 75, an intake air temperature correction coefficient Ktehxh1 is calculated from the intake air temperature Tno by the following equation. Ktexh1 = (Tno / TA #) ^{KN The} intake air temperature correction coefficient Ktehxh1 is obtained as the KN power of the ratio of the intake air temperature to the standard temperature as described above, and indicates the increase rate of the exhaust temperature due to the increase of the intake air temperature. is there.

In step 76, the exhaust pressure Pexh is set.
_The temperature rise correction coefficient Ktexh2, which is the rate of rise in exhaust gas temperature due to the rise in exhaust gas pressure, is calculated from _{n-1 based} on the adiabatic change. Ktexh2 = (Pnehx _n-1 / PA #) ^{(Ke-1) / Ke In} step 77, the basic exhaust gas temperature Texhb, the intake air temperature correction coefficient Ktexh1, and the temperature increase correction coefficient Ktehx.
From h2, the exhaust temperature Texh is calculated by the following equation.

Texh = Texhb × Ktexh1 × Ktexh2 FIG. 15 is a flowchart of a routine for calculating the EGR flow rate Qe. In step 81, the intake pressure Pm and the exhaust pressure P
Exh and the actual lift amount Lifts are input. Step 82
Then, the opening area AVe of the EGR passage is retrieved from the actual lift amount Lifts from a table as shown in FIG. 16, for example.

At step 83, the EGR flow rate Q is calculated by the following equation.
Calculate e. Qe = Ave × (Pexh−Pm) ^1/2 × KR # where KR # is a constant and the flow velocity q at the front-rear differential pressure ΔP.
Equation q = (ΔP · 2ρ) ^1/2 to a value approximately equal to (2ρ) ^1/2 (where ρ is the density of the exhaust gas). FIG. 17 shows a flow chart of a cycle processing routine for the cylinder intake air amount, the fuel injection amount, and the cylinder intake temperature.

In step 91, the cylinder intake air amount Qa
c, fuel injection amount Qsol, and cylinder intake air temperature Tn are input. The cylinder intake air temperature Tn can be calculated, for example, by the following equation. (Qac × Ta + Qec × Te) / (Qac + Qec) In step 92, the Qac, Qsol, and Tn are cycled. In order to match the phase with the exhaust stroke, delay processing is performed by Qac and Tn in the intake stroke by the number of cylinders minus one, and by Qsol in the compression stroke by the number of cylinders minus two.
The processing ends with xh, Tno, and Qfo.

FIG. 18, FIG. 20 and FIG. 21 show flowcharts of actual EGR control. FIG. 18 is a flowchart of a routine for calculating the command lift amount Liftt of the EGR valve. In step 101, the intake pressure Pm, the exhaust pressure Pexh, and the required EGR amount Tqe are input.

In step 102, the required flow passage area Tav of the EGR valve is calculated by the following equation. Here, KR # is the one used in step 83 of FIG. In step 103, the target lift amount M is calculated from the Tav from a table showing the relationship between the flow path area and the lift amount as shown in FIG. 19, for example.
Calculate lift. Step 101 to Step 103
The functions up to are equivalent to the basic opening calculation means in the present invention, and the intake pressure Pm, the exhaust pressure Pexh, and the required EG required to obtain the target lift amount Mlift corresponding to the basic opening.
Various sensors (the air flow meter 16, the rotation speed sensor 17, etc.) for obtaining the R amount Tqe correspond to the operating state detecting means.

In step 104, the target lift amount Ml is set.
Weighted average processing is performed on ift to obtain Tlift. The processing method of the weighted average and the setting of the constant will be described later. In step 105, the weighted average value Tlift is advanced by an amount corresponding to the valve operation delay, and the value is set to the command lift amount Lift.
Output as tt. FIG. 20 is a flowchart for calculating the required EGR amount Tqe.

In step 111, the engine speed Ne, the target EGR rate Megr, and the cylinder intake air amount Qac are input. In step 112, the target EGR flow rate Tqec0 to the intake collector is obtained by multiplying the cylinder intake air amount Qac by the target EGR rate Megr. Step 113
Then, the intake EGR amount Tqec0 is advanced by the advancing process for the intake system volume to obtain the target EGR flow rate Tqec to the cylinder.

In step 114, the target EGR flow rate T
The required EGR amount Tqe per cylinder is obtained from qec, the engine speed Ne, and the constant KCON #. FIG. 21 is a flowchart of a routine for calculating the target EGR rate Megr. In step 121, the engine speed Ne and the fuel injection amount Qsol are input.

In step 122, based on the engine speed Ne and the fuel injection amount Qsol which is the representative value of the load, the target EGR rate Meg is calculated from the table shown in FIG. 22, for example.
Search r. FIG. 23 is a flowchart of a routine for calculating the fuel injection amount Qsol. In step 131,
The engine speed Ne and the control lever opening CL are read.

In step 132, the basic fuel injection amount Mqd is calculated from the engine speed Ne and the control lever opening CL.
The rv is searched from a table as shown in FIG. 24, for example. In step 133, the basic fuel injection amount Mqdrv
Is corrected by various correction factors such as water temperature to obtain Qsoll. In step 134, the maximum fuel injection amount is limited and output as Qsol.

FIG. 25 is a flowchart of a routine for weighted averaging the target lift amount Mlift. Step 141
Then, the accelerator opening degree Tvo is read. In step 142, the difference | Tvo-Tvo _nm | between the accelerator opening Tvo and the accelerator opening read value Tvo _{nm a} predetermined number of times before.
Is taken as ΔTvo.

The function of step 142 corresponds to the operating state change detecting means. In step 143, it is determined whether ΔTvo is smaller than the predetermined value DTVO #, and the predetermined value DTVO # is determined.
If it is smaller than O #, go to step 144 and set a predetermined value DTVO #.
If so, the process proceeds to step 145 to set each weighted averaging coefficient Nlift. Target lift amount M in step 146
The weighted average value Tlift of the lift amount is calculated by performing the weighted average processing on the lift according to the following equation. Tlift = 1/2
^Nlift × Mlift + (1-1 / 2 ^Nlift ) × Tlift
_n-1 Here, when ΔTvo is smaller than the predetermined value DTVO #, that is, when the change in the operating state is small, step 144
Weighted averaging coefficient Nlift = NIFFTS set by
# Is set to a large value compared with the weighted averaging coefficient Nlift = NLIFTT # set in step 145 when ΔTvo is equal to or larger than the predetermined value DTVO #, that is, when the change in the operating state is large.

In this way, in a steady state where the change in the operating state is small, the weighted averaging coefficient Nlift is increased and the weight 1/2 of the target lift amount Mlift set to the latest is set.
^Nlift is reduced and the weighted average value Tlift until the last time
Steady stability is secured by increasing the weight of _n-1 (1-1 / 2 ^Nlift ), and the weighted averaging coefficient Nlift is set to a small value at the time of a transition where the change in the operating state is large, and is set to the latest value. it is possible to ensure the transient trackability by increasing the weight 1/2 ^Nlift target lift amount Mlift.

By setting the weighted averaging coefficient Nlift, the weighting ratio between the past weighted average value and the latest value is set. Therefore, the weighting ratio is set according to the change in the driving state. Step 143, Step 14
The functions of 4 and step 145 correspond to the weight ratio calculating means in the inventions of claims 1 to 3. Also step
The function of 146 corresponds to the weighted average processing means in the present invention.

Next, another embodiment of the present invention (embodiments of the invention according to claims 4 and 5) will be described.
Since the system configuration and the control in FIGS. 1 to 24 are executed in the same manner, the description thereof will be omitted. In the present embodiment, the first
The routine shown in FIG. 26 is executed instead of the routine shown in FIG. 25 of the embodiment.

In step 151, the intake pressure Pm and the exhaust pressure Pexh are read. In step 152, the differential pressure ΔP (= Pexh-Pm) between the intake pressure Pm and the exhaust pressure Pexh is calculated. In step 153, based on the differential pressure ΔP,
The weighted averaging coefficient Nlift is retrieved from the preset table shown in FIG.

In step 154, in step 14 of FIG.
The weighted average value Tlift is calculated by the same formula as shown in FIG.
Is calculated. Here, the weighted averaging coefficient Nlift
As shown in FIG. 27, is the intake pressure Pm and the exhaust pressure Pex.
The smaller the differential pressure ΔP from h, the larger the value is set. This is for the following reason. In the case of an engine with a supercharger, during transition, the exhaust pressure starts to rise, and then the intake pressure rises, so the time-series differential pressure increases during transition. Further, in a steady state, more EGR is generally applied than in a transient state, so the exhaust energy required for supercharging is reduced by applying more EGR, so the exhaust pressure is reduced, and the intake pressure is also reduced accordingly. The ratio is due to the reason that the differential pressure decreases because the exhaust pressure is higher.

Therefore, in a steady state where the differential pressure ΔP is small, the weighted averaging coefficient Nlift is increased to reduce the weight 1/2 ^Nlift of the target lift amount Mlift set to the latest, and the weighted average value Tlift _n-1 up to the previous time. Weight of (1-
Steady stability is secured by increasing (1/2 ^Nlift )
When the differential pressure ΔP is large, the weighted averaging coefficient Nlift
The target lift amount Mlift set to the latest
The transient followability can be secured by increasing the weight of 1/2 ^Nlift .

The functions of steps 152 and 153 correspond to the weight ratio calculating means of the inventions according to claims 4 and 5, and the function of step 154 corresponds to the weighted average processing means.

[0052]

As described above, according to the first aspect of the invention, the basic opening degree of the EGR valve is weighted averaged by changing the weight ratio between the steady state and the transient state according to the change of the operating state. Since the EGR valve is controlled according to the opening degree, the EGR control that achieves both the stability during steady state and the followability during transition is performed.

Further, according to the second aspect of the present invention, when the operating state is largely changed, the follow-up performance can be secured by increasing the weight of the basic opening calculated in the latest, and the operating state is small. In the steady state, stability can be secured by increasing the weight of the past weighted average value. Claim 3
According to the invention, the change in the operating state of the engine can be detected easily and with good responsiveness.

According to the invention of claim 4, EG
The opening degree of the EGR valve is controlled to a weighted average opening degree of the basic opening degree of the R valve depending on the pressure difference between the exhaust system pressure and the intake system pressure by changing the weighting ratio between the steady state and the transient state. , EGR control that achieves both stability during steady state and followability during transition is performed. According to the fifth aspect of the present invention, when the pressure difference between the exhaust system pressure and the intake system pressure is large, the follow-up performance can be secured by increasing the weight of the basic opening degree of the EGR valve calculated most recently. In the steady state where the differential pressure is small, stability can be secured by increasing the weight of the past weighted average value.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and function of the invention according to claims 1 to 3.

FIG. 2 is a block diagram showing a configuration and a function of the invention according to claim 4 and claim 5;

FIG. 3 is a diagram showing a system configuration of an embodiment of the present invention.

FIG. 4 is a flowchart of a routine for calculating an intake system pressure according to the above embodiment.

FIG. 5 is a flowchart of a routine for similarly calculating exhaust system pressure.

FIG. 6 is a flowchart of a routine for similarly calculating a cylinder intake air amount.

FIG. 7 is a flowchart of a routine for similarly calculating a cylinder intake EGR amount.

FIG. 8 is a flowchart of a routine that similarly calculates an intake air temperature.

FIG. 9 is a flowchart of a routine for similarly calculating the EGR temperature.

FIG. 10 is a flowchart of a routine that similarly calculates a volume efficiency equivalent value.

FIG. 11 is a pressure correction table used for calculation of the volumetric efficiency equivalent value.

[FIG. 12] Similarly, a rotation correction table.

FIG. 13 is a flowchart of a routine for similarly calculating the exhaust temperature.

FIG. 14 is a table of basic exhaust temperature used for calculating the exhaust temperature.

FIG. 15 is a flowchart of a routine that similarly calculates an EGR flow rate.

FIG. 16 is a valve lift passage area characteristic table used for the EGR flow rate calculation.

FIG. 17 is a flowchart showing a cycle processing routine for each value.

FIG. 18 is a flowchart of a routine that similarly calculates a command EGR valve lift amount.

FIG. 19 is a flow passage area lift characteristic table used for calculation of the commanded EGR valve lift amount.

FIG. 20 is a flowchart of a routine that similarly calculates a required EGR amount.

FIG. 21 is a flowchart of a routine that similarly calculates a target EGR rate.

FIG. 22 is a target EGR used to calculate the target EGR rate.
Rate map table.

FIG. 23 is a flowchart of a routine for similarly calculating a fuel injection amount.

FIG. 24 is a fuel injection amount map table used for calculating the fuel injection amount.

FIG. 25 is a flowchart of a routine for performing a weighted average process on the target EGR lift amount.

FIG. 26 is a flowchart of a routine for performing a weighted average process on a target EGR lift amount according to another embodiment of the present invention.

FIG. 27 is a weighted average coefficient map table used for the weighted average processing of the above.

[Explanation of symbols]

 5 Diesel engine 13 Control unit 16 Air flow meter 17 Rotation speed sensor 18 Lever opening sensor 19 Water temperature sensor 31 Throttle valve 34 Lift sensor

Claims (5)

[Claims] 1. An EGR connecting an exhaust system and an intake system of an engine.
In an exhaust gas recirculation control device for an internal combustion engine, which recirculates a part of exhaust gas to an intake system via an EGR valve provided in a passage, an operating condition detecting means for detecting an operating condition of the engine, and Basic opening calculation means for calculating a basic opening of the EGR valve, operating state change detection means for detecting a change in the detected engine operating state, a past weighted average value and the latest calculated basic opening The weight ratio when calculating the opening degree of the EGR valve by a weighted average of the degree and the weight ratio calculating means for calculating the opening degree of the EGR valve according to the change in the detected engine operating state; Weighted average processing means for performing a weighted average processing of the past weighted average value and the latest calculated basic opening value based on the calculated weight ratio, and the weighted averaged opening degree of the EGR valve. EGR
An exhaust gas recirculation control device for an internal combustion engine, comprising: an EGR valve drive means for driving a valve. 2. The weight ratio calculating means decreases the weight of the weighted average value in the past as the detected change in the operating state increases, and increases the weight of the basic opening degree of the EGR valve calculated most recently. The calculation according to claim 1
An exhaust gas recirculation control device for an internal combustion engine according to item 1. 3. The exhaust gas recirculation control device for an internal combustion engine according to claim 1, wherein the operating state change detecting means detects a change in the operating state of the engine based on a change in the accelerator opening. . 4. An EGR connecting an exhaust system and an intake system of an engine.
In an exhaust gas recirculation control device for an internal combustion engine, which recirculates a part of exhaust gas to an intake system via an EGR valve provided in a passage, an operating condition detection means for detecting an operating condition of the engine, and the detected operation of the engine. Basic opening calculation means for calculating the basic opening of the EGR valve according to the state, exhaust system pressure detection means for detecting the pressure of the exhaust system of the engine, and intake system pressure detection for detecting the pressure of the intake system of the engine Means for calculating the opening degree of the EGR valve based on a weighted average of a past weighted average value and the most recently calculated basic opening degree, the detected exhaust system pressure of the engine and the intake system A weight ratio calculating means for calculating based on a pressure difference from the pressure, an opening of the EGR valve, a weighted average value in the past based on the calculated weight ratio, and the latest calculated basic opening value. Weighted averaging process for weighted averaging If, EGR so that the opening degree of the weighted averaged EGR valve
An exhaust gas recirculation control device for an internal combustion engine, comprising: an EGR valve drive means for driving a valve. 5. The weight ratio calculating means decreases the weight of the past weighted average value as the differential pressure between the exhaust system pressure and the intake system pressure of the engine is larger, and the most recently calculated basic opening degree of the EGR valve. The exhaust gas recirculation control device for an internal combustion engine according to claim 4, wherein the calculation is performed so as to increase the weight of