JPH1077883A - Air-fuel ratio control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dispersion of exhaust components of every vehicle by providing a control means controlling in such a way as to correct the air-fuel ratio feedback control quantity on the basis of the EGR quantity obtained by measurement. SOLUTION: When an internal combustion engine is started and control is started (100), processing of measuring the EGR quantity recirculated to an intake system of the internal combustion engine is performed (102). In case the difference between the EGR quantity obtained by this measurement and the set median of the EGR quantity by an EGR value is the value within a prescribed area, processing of correcting the air-fuel ratio feedback control quantity is performed (104) and ended (106). An air-fuel ratio can thereby be controlled taking account of the EGR quantity recirculated to the intake system so as to be able to reduce dispersion of exhaust components of every manufactured vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control system for an internal combustion engine, and more particularly to an air-fuel ratio control system capable of controlling an air-fuel ratio in consideration of an amount of EGR recirculated to an intake system.
It is possible to control the air-fuel ratio to an appropriate value according to the change in the R amount, prevent deterioration of the exhaust gas component, and control the air-fuel ratio to an appropriate value according to the change in the EGR amount due to manufacturing variations of the EGR valve. Further, the present invention relates to an air-fuel ratio control device for an internal combustion engine, which can reduce the variation in exhaust components of each manufactured vehicle.

[0002]

2. Description of the Related Art Some internal combustion engines mounted on vehicles and the like are provided with an air-fuel ratio control device for controlling an air-fuel ratio to a target value. The air-fuel ratio control device uses an O
_Two sensors are provided, and the operation of the fuel injection valve, which is a fuel supply means, is controlled by the air-fuel ratio feedback control amount so that the air-fuel ratio becomes a target value based on the detection signal of the O ₂ sensor.

[0003] Some internal combustion engines are provided with an exhaust gas recirculation control device for recirculating a part of exhaust gas to an intake system. The exhaust gas recirculation control device includes an EGR valve whose operation is controlled between an open state and a closed state, and controls the operation of the EGR valve between an open state and a closed state to recirculate exhaust gas to an intake system. NOx, which is a component of

As described above, an exhaust gas recirculation control device having an EGR valve whose operation is controlled between an open state and a closed state so as to recirculate a part of exhaust gas to an intake system of an internal combustion engine is disclosed in Japanese Unexamined Patent Publication No. There is one disclosed in Japanese Patent No. 51746.

The exhaust gas recirculation control device disclosed in Japanese Patent Laid-Open Publication No. Sho 62-51746 is provided with an EGR valve whose operation is controlled between an open state and a closed state by pressure.
The intake pipe pressure and the fuel injection amount are detected and stored as the respective operating states when the valve is operating in the open state and the closed state, and when the EGR valve is operating in the open state and the closed state, respectively. It is determined whether or not the difference between the detected values is within a predetermined range, and an alarm is issued when it is determined that the difference between the detected values is within a predetermined range.

[0006]

As described above, an internal combustion engine provided with an air-fuel ratio control device is provided with an exhaust gas recirculation control device having an EGR valve whose operation is controlled between an open state and a closed state. Some are provided.

The EGR amount of the exhaust gas recirculated to the intake system by the exhaust gas recirculation control device is determined by the diameter of the EGR passage since the operation of the EGR valve is controlled between an open state and a closed state. .

However, in such an exhaust gas recirculation control device in which the EGR amount is determined by the passage diameter of the EGR passage, the passage diameter becomes narrow due to the accumulation of carbon or the like in the EGR passage after the endurance of the new vehicle after a long-term operation. The actual EGR
As shown in FIG. 2, there is a problem that the EGR rate by the EGR valve decreases, and as a result, the EGR amount decreases.

Since the conventional air-fuel ratio control device performs control without considering such a change in the EGR amount after the endurance, the air-fuel ratio becomes thinner due to the decrease in the EGR amount, and the air-fuel ratio deviates from the target value. Therefore, there is a disadvantage that NOx in the exhaust gas increases to cause deterioration of the exhaust gas component.

Further, in the exhaust gas recirculation control device, the EGR amount may change due to manufacturing variations of the EGR valve.

A conventional air-fuel ratio control apparatus has such an EG.
Since the change in the EGR amount due to manufacturing variations of the R valve is not taken into account, the air-fuel ratio deviates from a target value for each vehicle manufactured with the internal combustion engine provided with the air-fuel ratio control device, There is an inconvenience that the variation of the exhaust component of each vehicle increases.

[0012]

Therefore, in order to eliminate the above-mentioned disadvantages, an exhaust sensor is provided in an exhaust passage of an internal combustion engine, and an air-fuel ratio becomes a target value based on a detection signal of the exhaust sensor. In an air-fuel ratio control device for an internal combustion engine that controls the operation of a fuel supply means by an air-fuel ratio feedback control amount, the operation is controlled between an open state and a closed state so that a part of exhaust gas is recirculated to an intake system of the internal combustion engine. An exhaust gas recirculation control device provided with an EGR valve, which measures an EGR amount of exhaust gas recirculated to an intake system of the internal combustion engine, and uses the EGR amount obtained by the measurement to calculate the air-fuel ratio feedback. Control means for performing control to correct the control amount is provided, and the control means detects whether the EGR valve is open or closed, respectively. Control means for measuring the EGR amount based on either the difference between the measured intake pressure or the difference between the intake air amounts, and the control means determines the EGR amount obtained by the measurement and a design median value of the EGR valve. Control means for controlling the air-fuel ratio feedback control amount to be corrected when the difference between the EGR amount and the EGR valve is within a predetermined range, and the control means further comprises an EGR amount obtained by the measurement and a design of the EGR valve. When the difference between the median value and the median value is within a predetermined range, the control means performs control to correct an air-fuel ratio correction amount other than the air-fuel ratio feedback control amount.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an air-fuel ratio control device according to the present invention, an EGR amount recirculated to an intake system by an exhaust recirculation control device provided in an internal combustion engine is measured by a control means. By controlling to correct the air-fuel ratio feedback control amount of the fuel supply means by
The air-fuel ratio can be controlled in consideration of the amount of EGR recirculated to the intake system.

Further, in the air-fuel ratio control device of the present invention, the control means measures the EGR amount based on either the difference between the intake pressure detected or the difference between the intake air amounts detected in the open state and the closed state of the EGR valve. By doing
A change in the EGR amount can be measured using existing sensors, and when the difference between the EGR amount obtained by this measurement and the design median value of the EGR valve is a value within a predetermined range, the air-fuel ratio feedback control is performed. By controlling to correct the amount, when the difference is a value within a predetermined range, it can be diagnosed as normal and the air-fuel ratio can be properly controlled, and when the difference is a value outside the predetermined range, it is diagnosed as abnormal. Warning can be issued.

Further, according to the air-fuel ratio control apparatus of the present invention, the control means controls the EGR amount and the EGR amount obtained by the measurement.
When the difference between the design median value of the valve and the value within the predetermined range,
By performing control so as to correct the air-fuel ratio correction amount other than the air-fuel ratio feedback control amount, when the difference is within a predetermined range, it can be diagnosed as normal and the air-fuel ratio can be controlled more appropriately, and the difference can be controlled. If the value is out of the predetermined range, it can be diagnosed as abnormal and issue a warning.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 13 show an embodiment of the present invention. In FIG. 13, reference numeral 2 denotes an internal combustion engine mounted on a vehicle (not shown), 4 denotes a cylinder block, 6 denotes a cylinder head, 8 denotes an oil pan, and 10 denotes a crankshaft.

The internal combustion engine 2 includes an air cleaner 12, an intake pipe 14, a throttle body 16, a surge tank 18, an intake manifold 20, and an intake passage 22 as an intake system. The throttle body 16 is provided with a throttle valve 24. The internal combustion engine 2 includes an exhaust manifold 26, a front catalytic converter 28, an exhaust pipe 30, a rear catalytic converter 32, and a rear exhaust pipe 34 as an exhaust system, and an exhaust passage 36.

The internal combustion engine 2 is provided with a fuel injection valve 38 of a D-type injection system as a fuel supply means. The fuel injection valve 38 injects and supplies the fuel supplied from the fuel tank 40 toward the combustion chamber. The fuel tank 40 is provided with a level gauge 42.

The internal combustion engine 2 is provided with an ignition device 44, a water temperature sensor 46 for detecting a cooling water temperature, a crank angle sensor 48 for detecting a rotation angle of the crankshaft 10, and an intake air temperature for detecting an intake air temperature. An air temperature sensor 50 is provided, a throttle opening sensor 52 for detecting the opening of the throttle valve 24 is provided, and an intake pressure sensor 54 for detecting intake pressure is provided.

The internal combustion engine 2 includes an evaporative fuel control device 56
Is provided. The evaporative fuel control device 56 includes the fuel tank 4
A canister 58 that adsorbs and holds the 0 evaporated fuel and releases and releases the adsorbed and held evaporated fuel is provided. The canister 58 is connected to the fuel tank 40 by the evaporation passage 60.
The purge passage 62 communicates with the surge tank 18, and the atmosphere passage 64 communicates with the atmosphere.

In the evaporation passage 60, the fuel tank 40
A tank internal pressure sensor 66, a separator 68, and a pressure control valve 70 are provided sequentially from the side. The pressure control valve 70 communicates with the surge tank 18 via a pressure passage 72. A negative pressure control valve 74 is provided in the pressure passage 72. A purge control valve 76 is provided in the purge passage 62. An atmosphere control valve 78 is provided in the atmosphere passage 64.

The internal combustion engine 2 is provided with an exhaust gas recirculation control device 80 for recirculating a part of exhaust gas to the intake system. The exhaust gas recirculation control device 80 includes an EGR valve 82 whose operation is controlled between an open state and a closed state. The EGR valve 82 is an EGR (not shown) that connects the exhaust system and the intake system.
It is provided in the passage. The actual EGR amount of the exhaust gas flowing through the EGR passage by the opening operation of the EGR valve 82 is:
It is determined by the passage diameter of the EGR passage.

The exhaust gas recirculation control device 80 includes a back pressure control valve 84, an EGR control valve 86, and an EGR determination valve 88. The pressure applied to the EGR valve 82 is controlled by these valves, and as shown in FIG. 5, the operation is controlled between an open state and a closed state to adjust the EGR amount.

The internal combustion engine 2 has an air-fuel ratio control device 90
Is provided. The air-fuel ratio controller 90 has an O ₂ sensor as an exhaust sensor in the exhaust passage 36. In this embodiment, a front O ₂ sensor 92 is provided in the exhaust manifold 26, and a rear O ₂ sensor 94 is provided in the rear exhaust pipe 34. The front O ₂ sensor 92 and the rear O ₂ sensor 94 are connected to control means 96 of the air-fuel ratio control device 90.

The control means 96 includes the fuel injection valve 3
8, a level gauge 42, an ignition device 44, a water temperature sensor 46, a crank angle sensor 48, and an intake air temperature sensor 50.
, Throttle opening sensor 52 and intake pressure sensor 54
, A tank pressure sensor 66, a negative pressure control valve 74, a purge control valve 76, an atmosphere control valve 78, an EGR control valve 86, and an EGR determination valve 88.

The air-fuel ratio control unit 90 controls the front O ₂ sensor 92 and the rear O ₂ sensor 94 by the control means 96.
The operation of the fuel injection valve 38 is controlled based on the air-fuel ratio feedback control amount so that the air-fuel ratio becomes the target value based on the detection signal.

The internal combustion engine 2 is provided with an exhaust gas recirculation control device 80 having an EGR valve 82 whose operation is controlled between an open state and a closed state so as to recirculate part of exhaust gas to the intake system.

The air-fuel ratio control device 90 of the internal combustion engine 2
The control means 96 measures the EGR amount of the exhaust gas recirculated to the intake system of the internal combustion engine 2 by the exhaust gas recirculation control device 80, and corrects the air-fuel ratio feedback control amount based on the EGR amount obtained by the measurement.

The control means 96 includes an EGR valve 82
EGR based on either the difference in intake pressure or the difference in intake air amount detected in the open state and the closed state of
And the EGR amount obtained by this measurement and the EGR
When the difference from the designed median value of the valve 82 is a value within a predetermined range, control is performed so as to correct the air-fuel ratio feedback control amount.

Next, the operation of the embodiment will be described.

As shown in FIG. 1, the air-fuel ratio control device 90
When the control is started by starting the internal combustion engine 2 (step 100), a process of measuring an EGR amount (EGRN) recirculated to the intake system of the internal combustion engine 2 is performed (step 102).
EGR amount (EGRN) obtained by this measurement and EGR
Design median EGR amount by valve 82 (EGRMD)
(EGRDAV) is within a predetermined range (EGRH <EGR).
When the value of DLAV <EGRL is satisfied, the air-fuel ratio feedback control amounts (DRL, DLR, P _R , P _L , I _R , I)
_The process of correcting _L (single or combination of _L ) is performed (step 104), and the process ends (step 104).

The process of measuring the EGR amount and the process of correcting the air-fuel ratio feedback control amount are performed as shown in FIGS.

In the process of measuring the EGR amount, as shown in FIG. 3, when the control is started (step 200), a process for determining whether the measurement execution condition is satisfied is performed (step 202), and whether or not the measurement execution condition is satisfied is determined. (Step 20)
4).

As the measurement execution conditions, for example, it is set that the warm-up of the internal combustion engine 2 has ended and that the vehicle equipped with the internal combustion engine 2 is running at a constant speed.

Determination of satisfaction of the measurement execution condition (step 2)
If 04) is NO, the process returns. When the determination of the satisfaction of the measurement execution condition (step 204) is YES, as shown in FIG. 5, the EGR valve 82 is forcibly changed from ON to OF.
F, ON from OFF and operate in an open state and a closed state, and measure the intake pressure in each state by the intake pressure sensor 54.
And an EGR amount (EGRN) is obtained from the difference between the intake pressure in the open state and the intake pressure in the closed state (step 20).
6).

In the case of an L-type injection system, the EGR amount (EGRN) can also be obtained from the difference in the amount of intake air detected by an intake air amount sensor (not shown).

The EGR amount (EGR) obtained by the above measurement
N) changes depending on the atmospheric pressure as shown in FIG. 6, and is corrected (EGRNA = EGRN × KATM) to a value (EGRNA) equivalent to a flat ground by the atmospheric pressure at the time of measurement (step 2).
08).

Since the measured value of the EGR amount varies as shown in FIG. 6, the value corrected by the atmospheric pressure (EG
RNA) to obtain an average value (EGRNAV) (step 210).

As shown in FIG. 7, the obtained average value (EGRNAV) of the EGR amount and the EGR value
The difference (EGR) is compared with the design median (EGRMD) of the quantity.
DLT) is calculated, and in order to further reduce the measurement variation, the difference (EGRDLT) is statistically processed to obtain an average value (EGRDLVA) (step 212), and the process ends (step 214).

The average value (EGRDLAV) of the obtained difference (EGRDLT) is used for processing for correcting the air-fuel ratio feedback control amount.

In the process for correcting the air-fuel ratio feedback control amount, as shown in FIG. 4, when the control is started (step 300), the average value (EGRDLV) of the difference (EGRDLT) obtained in the above (step 212) is set to a predetermined value. It is determined whether the value is within the range (step 30).
2).

In this determination (step 302), as shown in FIG. 8, the average value (EGRDLAV) is equal to the first determination value (E
It is determined whether or not the value is within a predetermined range between GRH) and the second determination value (EGRL) (EGRH <EGRDLAV).
<EGRL).

If the average value (EGRDLAV) is a value within a predetermined range between the first judgment value (EGRH) and the second judgment value (EGRL), and the judgment (step 302) is YES, FIG. The air-fuel ratio feedback control amount is corrected by the correction coefficient shown in FIG. 9 (step 304), and the process ends (step 306).

As the air-fuel ratio feedback control amount,
As shown in FIG. 9, the lean determination delay time DRL, rich determination delay time DLR, lean proportional correction amount P _L, the rich proportional correction amount P _R, the lean integral correction amount I _L, the rich proportional correction amount I _R, there is.

As shown in FIG. 8, the air-fuel ratio feedback control amount is corrected by calculating, for example, a lean determination delay time correction coefficient CDRL and a rich determination delay time correction coefficient CDLR from an average value (EGRDLAV). min correction coefficient CP _L, obtains the rich proportional correction amount correction coefficient CP _R, or lean integration correction amount correction coefficient CI _L, rich proportional correction amount correction coefficient CI _R, a seek.
In FIG. 8, the delay, the proportional component, and the integral component are shown in one diagram, but have different correction coefficients.

The air-fuel ratio feedback control amount, the correction coefficient _{CDRL, CDLR, CP L, CP} R, CI L, C
The _{I R DRL 0LD, DLR OLD,} CP LOLD, CP ROLD,
By multiplying CI _LOLD , CI _ROLD , CDR, CD
It is corrected to L, CP, CP, CI, and CI.

The air-fuel ratio controller 90 determines the corrected CD
The operation of the fuel injection valve 38 is controlled by R, CDL, CP, CP, CI, and CI. The air-fuel ratio feedback control amount is determined by the CDR, CDL, CP, CP, CI, CI
Is corrected alone or in combination. For example, when the average value (EGRDLAV) is large, the EGR amount is small and the air-fuel ratio becomes thin. Therefore, the lean determination delay time DRL is lengthened, the rich time is lengthened, and the lean time is shortened.

On the other hand, whether the average value (EGRDLAV) is smaller than the first judgment value (EGRH) or the second judgment value (EGRH).
RL), the value is out of the predetermined range, and if the determination (step 302) is NO, it is diagnosed that the EGR amount is abnormal,
A warning is issued by turning on a lamp (not shown) or sounding a buzzer (not shown) (step 308), and the process ends (step 306).

In the determination (step 308), the correction coefficient (EGRVAL) is set to the first determination value (EGR).
If the value is outside the predetermined range smaller than H), it is diagnosed that the flow rate of the EGR amount is excessive, and if the correction coefficient (EGRVAL) is outside the predetermined range larger than the second determination value (EGRL), E is set.
Diagnosis is made that the GR amount is too low.

As described above, the air-fuel ratio control device 90 measures the amount of EGR recirculated to the intake system by the exhaust gas recirculation control device 80 provided in the internal combustion engine 2 by the control means 96, and obtains the EGR amount obtained by the measurement. By performing control so as to correct the air-fuel ratio feedback control amount of the fuel injection valve 38 based on the amount, the air-fuel ratio can be controlled in consideration of the EGR amount returned to the intake system.

For this reason, the air-fuel ratio control device 90 can control the air-fuel ratio in consideration of the amount of EGR recirculated to the intake system, so that the air-fuel ratio can be controlled in accordance with a change in the EGR amount after endurance due to long-term operation. It is possible to control the air-fuel ratio to an appropriate value, to prevent deterioration of exhaust components, and to control the air-fuel ratio to an appropriate value in accordance with a change in the EGR amount due to a variation in manufacturing of the EGR valve. It is possible to reduce the variation in the exhaust component of each vehicle.

In the air-fuel ratio control device 90, the control means 96 controls the EGR amount based on either the difference in intake pressure or the difference in intake air amount detected when the EGR valve 82 is open or closed. By measuring, the change in the EGR amount can be measured by using the existing sensors, and the EGR amount obtained by this measurement and E
When the difference from the designed median value of the GR valve 82 is a value within a predetermined range, control is performed so as to correct the air-fuel ratio feedback control amount. Can be properly controlled, and when the difference is a value outside the predetermined range, it can be diagnosed as abnormal and a warning can be issued.

For this reason, the air-fuel ratio control device 90 can be implemented in a cost-effective manner by using existing sensors, and can issue a warning when the EGR amount is abnormal. Abnormalities can be quickly dealt with, and extreme deterioration of exhaust components can be prevented.

Further, the air-fuel ratio control device 90 controls the EGR amount and the EG
When the difference between the design center value of the R valve 82 and the design value is within a predetermined range, control can be performed to correct an air-fuel ratio correction amount other than the air-fuel ratio feedback control amount.

In the process of correcting the air-fuel ratio correction amount other than the air-fuel ratio feedback control amount, as shown in FIG. 11, when the control is started (step 400), the difference (EGRDLT) obtained in (step 212) of FIG. ) Is determined whether or not the average value (EGRDLAV) is within a predetermined range (step 402).

In this judgment (step 402), as shown in FIG. 8, the average value (EGRDLAV) is equal to the first judgment value (E
It is determined whether or not the value is within a predetermined range between GRH) and the second determination value (EGRL) (EGRH <EGRDLAV).
<EGRL).

If the average value (EGRDLAV) is a value within a predetermined range between the first judgment value (EGRH) and the second judgment value (EGRL), and if the judgment (step 402) is YES, the EGR amount becomes empty. The air-fuel ratio correction amount other than the fuel ratio feedback control amount is corrected (step 404), and the process ends (step 406).

This correction is made by, for example, an EGR decrease correction coefficient (EGRF). The EGR decrease correction coefficient (EGRF) is obtained when the air-fuel ratio is controlled so as to approach the stoichiometric air-fuel ratio by performing the air-fuel ratio feedback control.
When the exhaust gas for EGR is introduced into the intake passage 22, the air-fuel ratio generally shifts to the rich side, so that the fuel injection amount of the fuel injection valve 38 is reduced.

The EGR decrease correction coefficient (EGRF) is shown in FIG.
1. As shown in FIG. 12, the air-fuel ratio correction amount is obtained from the difference (EGRDLT), and the air-fuel ratio correction amount is corrected by the obtained EGR reduction correction coefficient (EGRF) to obtain the final air-fuel ratio.

On the other hand, the average value (EGRDLAV) is smaller than the first judgment value (EGRH) or the second judgment value (EGRH).
RL), the value is outside the predetermined range, and if the determination (step 402) is NO, it is diagnosed that the EGR amount is abnormal,
A warning is issued by turning on a lamp (not shown) or sounding a buzzer (not shown) (step 408), and the process ends (step 406).

In the judgment (step 408), the correction coefficient (EGRVAL) is set to the first judgment value (EGRVAL).
If the value is outside the predetermined range smaller than H), it is diagnosed that the flow rate of the EGR amount is excessive, and if the correction coefficient (EGRVAL) is outside the predetermined range larger than the second determination value (EGRL), E is set.
Diagnosis is made that the GR amount is too low.

As described above, the air-fuel ratio control device 90
When the difference between the measured EGR amount and the designed median value of the EGR valve 82 is within a predetermined range, the control means 96 controls to correct the air-fuel ratio correction amount other than the air-fuel ratio feedback control amount. Thereby, when the difference is within a predetermined range, it can be diagnosed as normal and the air-fuel ratio can be controlled more appropriately, and when the difference is outside the predetermined range, it can be diagnosed as abnormal and issue a warning. .

Therefore, the air-fuel ratio control device 90
By being able to issue a warning when the GR amount is abnormal, it is possible to quickly cope with the EGR amount abnormality, and to prevent extreme deterioration of the exhaust gas component.

[0064]

As described above, in the air-fuel ratio control device of the present invention, the control means measures the amount of EGR recirculated to the intake system by the exhaust gas recirculation control device provided in the internal combustion engine, and is obtained by this measurement. By performing control so as to correct the air-fuel ratio feedback control amount of the fuel supply unit based on the EGR amount, the air-fuel ratio can be controlled in consideration of the EGR amount returned to the intake system.

For this reason, this air-fuel ratio control device can control the air-fuel ratio in consideration of the amount of EGR recirculated to the intake system. It is possible to control the air-fuel ratio to an appropriate value, to prevent deterioration of the exhaust gas component, and to control the air-fuel ratio to an appropriate value in accordance with a change in the EGR amount due to manufacturing variations of the EGR valve. The variation of the exhaust component of each vehicle can be reduced.

In the air-fuel ratio control device according to the present invention, the control means measures the EGR amount based on at least one of the difference between the intake pressure and the difference between the intake air amounts detected in the open state and the closed state of the EGR valve. Thus, the change in the EGR amount can be measured using the existing sensors, and the EGR amount and the EG
By controlling the air-fuel ratio feedback control amount to be corrected when the difference from the design center value of the R valve is within a predetermined range, it is diagnosed that the air-fuel ratio is normal when the difference is within a predetermined range. Appropriate control can be performed, and when the difference is a value outside the predetermined range, an abnormality can be diagnosed and a warning can be issued.

For this reason, the air-fuel ratio control device can be implemented in a cost-effective manner by using existing sensors, and can issue a warning when the EGR amount is abnormal. Can be quickly dealt with, and extreme deterioration of exhaust components can be prevented.

Further, in the air-fuel ratio control device according to the present invention, the control means controls the EGR amount obtained by measurement and the EGR amount.
When the difference between the design median value of the valve and the value within the predetermined range,
By performing control so as to correct the air-fuel ratio correction amount other than the air-fuel ratio feedback control amount, when the difference is within a predetermined range, it can be diagnosed as normal and the air-fuel ratio can be controlled more appropriately, and the difference can be controlled. If the value is out of the predetermined range, it can be diagnosed as abnormal and issue a warning.

For this reason, this air-fuel ratio control device
A warning can be issued when the amount is abnormal.
An abnormality in the R amount can be promptly dealt with, and extreme deterioration of the exhaust gas component can be prevented.

[Brief description of the drawings]

FIG. 1 is a main flowchart of an air-fuel ratio control device showing an embodiment of the present invention.

FIG. 2 is a diagram showing a change in an EGR rate.

FIG. 3 is a flowchart of an EGR amount measurement process.

FIG. 4 is a flowchart of a correction process of an air-fuel ratio feedback control amount.

FIG. 5 shows vehicle speed, ON / OFF of an EGR valve, and EGR.
It is a timing chart with the intake pressure at the time of valve ON and OFF.

FIG. 6 is a diagram showing correction of a measured EGR amount by atmospheric pressure.

FIG. 7 is a diagram for calculating an average value of a difference between a measured EGR amount and a design median value of an EGR valve.

FIG. 8 is a diagram for obtaining a correction coefficient from an average value of a difference between a measured EGR amount and a design median value of an EGR valve.

FIG. 9 is a timing chart of the output of the O ₂ sensor of the air-fuel ratio control device and the air-fuel ratio feedback control amount.

FIG. 10 is a flowchart of a correction process of the air-fuel ratio control device showing another embodiment of the present invention.

FIG. 11 is a diagram for calculating an EGR decrease correction coefficient from an average value of a difference between a measured EGR amount and a design median value of the EGR valve.

FIG. 12 is a diagram showing an air-fuel ratio map set based on an engine speed and an engine load.

FIG. 13 is a system configuration diagram of the air-fuel ratio control device.

[Explanation of symbols]

2 engine 22 intake passage 36 exhaust passage 38 to the fuel injection valve 48 a crank angle sensor 52 throttle position sensor 54 intake air pressure sensor 80 exhaust gas recirculation control device 82 EGR valve 90 air-fuel ratio control system 92 front O ₂ sensor 94 rear O ₂ sensor 96 Control means

Claims (4)

[Claims] An exhaust sensor is provided in an exhaust passage of an internal combustion engine, and the operation of a fuel supply means is controlled by an air-fuel ratio feedback control amount based on a detection signal of the exhaust sensor so that the air-fuel ratio becomes a target value. In the fuel ratio control device, there is provided an exhaust gas recirculation control device including an EGR valve whose operation is controlled between an open state and a closed state so as to recirculate a part of the exhaust gas to the intake system of the internal combustion engine. E of exhaust gas recirculated to the intake system of the internal combustion engine
An air-fuel ratio control apparatus for an internal combustion engine, comprising: a control unit that measures a GR amount and corrects the air-fuel ratio feedback control amount based on the EGR amount obtained by the measurement. 2. The control unit according to claim 1, wherein the EGR valve detects an EGR valve based on one of an intake pressure difference and an intake air amount difference detected between an open state and a closed state.
The air-fuel ratio control device for an internal combustion engine according to claim 1, which is a control means for measuring an amount. 3. The control means corrects the air-fuel ratio feedback control amount when a difference between an EGR amount obtained by the measurement and a design median value of the EGR valve is within a predetermined range. 2. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the control unit is a control unit. 4. The air-fuel ratio correction amount other than the air-fuel ratio feedback control amount when the difference between the EGR amount obtained by the measurement and the design median value of the EGR valve is a value within a predetermined range. 2. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the control unit is a control unit that performs control to make correction.