JP2000054942A - Air-fuel ratio control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a control accuracy of an air-fuel ratio by finding out a correcting value of the air-fuel ratio detected by ion current on the basis of the air-fuel ratio detected when an air-fuel ratio sensor is activated, and correcting the air-fuel ratio detected by the ion current by the corrected value. SOLUTION: When a transistor Tr51a is turned on/off by an ignition signal, high voltage is induced on a secondary winding wire 52b of an ignition coil 52. When spark discharging is generated on an ignition plug 50, mixture in a combustion chamber is ignited and burnt, and ionized. Ion current flows from a rated voltage power supply 116 through an ion current detecting resistance 118, and an ion current detecting signal is supplied to an ECU. In the ECU, a correcting value of an air-fuel ratio is learnt on the basis of the detected ion current value and the air-fuel ratio when an air-fuel ratio sensor is activated. When the air-fuel ratio sensor is not activated, the air-fuel ratio detected by ion current is corrected, and the air-fuel ratio is controlled by the air-fuel ratio after correction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, in which an appropriate amount of fuel is supplied in accordance with the amount of intake air, so that the mixture ratio of air and fuel (air-fuel ratio: A / F) is adjusted to a desired value. The present invention relates to a control device (air-fuel ratio control device).

[0002]

2. Description of the Related Art As one method for detecting the air-fuel ratio of an internal combustion engine, a method has been proposed in which an ion current corresponding to the amount of ions generated in a cylinder is measured, and the air-fuel ratio is detected based on the ion current. I have. That is, when a discharge is caused by the ignition plug and the air-fuel mixture in the cylinder burns, the air-fuel mixture is ionized. When a voltage is applied to the ignition plug while the mixture is in an ionized state, an ionic current flows. This ion current can be detected, and the air-fuel ratio can be detected based on the current value. The air-fuel ratio can be controlled by adjusting the fuel injection amount to the engine based on the detected air-fuel ratio.

For example, Japanese Patent Laying-Open No. 5-2221989 discloses a device for detecting the air-fuel ratio based on the ion current and controlling the fuel injection amount when the O ₂ sensor is still in an inactive state immediately after starting. are doing.

[0004]

When the relationship between the ion current value and the air-fuel ratio is examined, the ion current value changes due to factors other than the combustion state, such as deterioration of the spark plug. Therefore, it is difficult to accurately detect the air-fuel ratio based on the ion current, and there is a problem that the air-fuel ratio control accuracy cannot be maintained satisfactorily.

[0005] In view of the above problems, an object of the present invention is to provide an air-fuel ratio control device based on ion current, which can accurately measure air-fuel ratio regardless of fluctuations in ion current due to factors other than the combustion state, such as deterioration of a spark plug. The object of the present invention is to provide something that can control the

[0006]

SUMMARY OF THE INVENTION In recent years, the present invention provides an air-fuel ratio control for providing an air-fuel ratio feedback control by providing an air-fuel ratio sensor (A / F sensor) that generates a linear output with respect to the air-fuel ratio in an exhaust passage. The above-mentioned object is achieved by noting that the number of devices is increasing and providing devices as described below.

That is, according to the present invention, there is provided an ion current detecting means for detecting an ion current corresponding to an amount of ions generated by combustion of an air-fuel mixture in a cylinder of an internal combustion engine, and provided in an exhaust passage of the engine. Detection by the ionic current detecting means based on an air-fuel ratio sensor, an ionic current value detected by the ionic current detecting means when the air-fuel ratio sensor is activated, and an air-fuel ratio detected by the air-fuel ratio sensor; A correction value learning unit for learning a correction value for correcting an error; an ion current value detected by the ion current detection unit when the air-fuel ratio sensor is inactive; and a correction value learning unit. An air-fuel ratio control device for an internal combustion engine, comprising: a fuel injection amount adjusting means for adjusting a fuel injection amount based on a correction value.

[0008] In the air-fuel ratio control apparatus for an internal combustion engine according to the present invention configured as described above, the correction for the air-fuel ratio detected by the ionic current is performed based on the air-fuel ratio detected when the air-fuel ratio sensor is activated. A value is obtained, and when the air-fuel ratio sensor is inactive, the air-fuel ratio based on the ionic current is corrected by the correction value, and the air-fuel ratio is controlled based on the corrected air-fuel ratio. Therefore, the air-fuel ratio control accuracy is improved.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine provided with an air-fuel ratio control device according to one embodiment of the present invention. The internal combustion engine 1 is an in-line 4-cylinder 4-stroke cycle reciprocating gasoline engine mounted on a vehicle. The engine 1 includes a cylinder block 2 and a cylinder head 3.
Four cylinders 4 extending in the up-down direction are arranged in the cylinder block 2 side by side in the thickness direction of the drawing, and a piston 5 is accommodated in each cylinder 4 so as to be able to reciprocate. Each piston 5
Are connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is
The rotational motion of the crankshaft 7 is converted through the connecting rod 6.

A combustion chamber 8 is provided between the cylinder block 2 and the cylinder head 3 above each piston 5. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 for communicating both outer surfaces thereof with the respective combustion chambers 8. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially vertically. In the cylinder head 3,
Above each valve 11, 12, an intake side camshaft 1 is provided.
3 and the exhaust-side camshaft 14 are provided rotatably. Cams 15 and 16 for driving the valves 11 and 12 are attached to the camshafts 13 and 14, respectively. Timing pulleys 17 and 18 provided at ends of the camshafts 13 and 14 are connected to a timing pulley 19 provided at an end of the crankshaft 7 by a timing belt 20.

The intake port 9 is connected to an intake passage 30 having an air cleaner 31, a throttle valve 32, a surge tank 33, an intake manifold 34, and the like. Air (outside air) outside the engine 1 is supplied to the intake passage 3 toward the combustion chamber 8.
0 sequentially passes through the respective parts 31, 32, 33 and 34. An idle adjustment passage 35 that bypasses the throttle valve 32 is provided with an idle rotation speed control valve (ISCV) 36 for adjusting the air flow during idling. Each intake port 9 is provided in the intake manifold 34.
An injector 40 for injecting fuel toward is mounted. The fuel is stored in a fuel tank 41, from which the fuel is pumped by a fuel pump 42, and a fuel pipe 4
3 and is supplied to the injector 40. Then, a mixture of fuel injected from the injector 40 and air flowing in the intake passage 30 is introduced into the combustion chamber 8 via the intake valve 11.

An ignition plug 50 is mounted on the cylinder head 3 to ignite the mixture. At the time of ignition, the igniter 51 that has received the ignition signal controls the supply and cutoff of the primary current of the ignition coil 52, and the secondary current is supplied to the ignition plug 5 via the ignition distributor 53.
0 is supplied.

The burned air-fuel mixture is guided to an exhaust port 10 via an exhaust valve 12 as exhaust gas. The exhaust port 10 has an exhaust manifold 61 and a catalytic converter 62.
The exhaust passage 60 provided with the above is connected. HC (hydrocarbon), which is an incomplete combustion component, is supplied to the catalytic converter 62.
And a three-way catalyst that simultaneously promotes the oxidation of CO (carbon monoxide) and the reduction of NO _x (nitrogen oxide) generated by the reaction of nitrogen in the air with unburned oxygen. . The exhaust gas thus purified in the catalytic converter 62 is discharged into the atmosphere.

The engine 1 is provided with various sensors. A water temperature sensor 74 for detecting the temperature of the cooling water of the engine 1 is attached to the cylinder block 2. An air flow meter 70 for detecting an intake air flow rate is attached to the intake passage 30. An intake air temperature sensor 73 for detecting the temperature of the intake air is attached near the air cleaner 31 in the intake passage 30.
In the intake passage 30, near the throttle valve 32, a throttle opening sensor 72 for detecting the rotation angle of the shaft is provided. When the throttle valve 32 is in the fully closed state, the idle switch 82 is turned on, and the throttle fully closed signal output from the idle switch 82 becomes active. The surge tank 33 is provided with a vacuum sensor 71 for detecting an internal pressure (intake pressure). An air-fuel ratio sensor (A / F sensor) 75 having an output characteristic substantially proportional to the air-fuel ratio of the exhaust gas (see FIG. 2) is attached to a portion of the exhaust passage 60 upstream of the catalytic converter 62.

The distributor 53 incorporates two rotors that rotate in synchronization with the rotation of the crankshaft 7, and detects the crank angle based on the rotation of one of the rotors to detect the reference position of the crankshaft 7. (C
A) is provided with a crank reference position sensor 80 that generates a reference position detection pulse every 720 ° CA in terms of A), and detects a rotation speed of the crankshaft 7 based on the rotation of the other rotor. Crank angle sensor 81 that generates a rotation speed detection pulse for each CA
Is provided. The vehicle is provided with a vehicle speed sensor 83 that generates a number of output pulses per unit time in proportion to the rotation speed of the transmission output shaft, that is, the vehicle speed.

Engine electronic control unit (engine ECU) 90
Is a microcomputer system that executes fuel injection control, ignition timing control, idle speed control, and the like.
The ignition timing control is based on the engine speed obtained from the crank angle sensor 81 and signals from other sensors, comprehensively determines the state of the engine, determines the optimal ignition timing, and sends an ignition signal to the igniter 51. It is. The idle rotation speed control detects an idle state based on a throttle fully closed signal from an idle switch 82 and a vehicle speed signal from a vehicle speed sensor 83, and sets a target rotation speed determined by an engine coolant temperature from a water temperature sensor 74 and an actual rotation speed. The engine speed is compared with the engine speed, the control amount is determined so as to reach the target speed according to the difference, and the ISCV 36 is controlled to adjust the air amount, thereby maintaining the optimum idle speed. .

In the fuel injection control, basically, a fuel injection amount for achieving a predetermined target air-fuel ratio, that is, an injection time by the injector 40 is calculated based on the intake air amount of the engine, and is calculated to a predetermined crank angle. At this time, the injector 40 is controlled to inject the fuel. In addition,
The intake air amount of the engine is calculated from the intake air flow rate measured by the air flow meter 70 and the engine rotation speed obtained from the crank angle sensor 81, or the intake pipe pressure and the engine rotation speed obtained from the vacuum sensor 71. Is estimated by In the calculation of the fuel injection amount, basic correction based on signals from the respective sensors such as the throttle opening sensor 72, the intake air temperature sensor 73, and the water temperature sensor 74, and air correction based on the signal from the air-fuel ratio sensor 75. Fuel ratio feedback correction, etc. are added.

Further, the engine 1 is provided with an ion current detection circuit 110 so that air-fuel ratio control based on the amount of ions generated in the cylinder after combustion can be performed. FIG. 3 is a diagram showing a circuit configuration of the ignition device and the ion current detection circuit 110. One end of a primary winding 52a of the ignition coil 52 is connected to a positive electrode of the battery 100, and the other end is connected to a collector of a switching transistor 51a in the igniter 51. The emitter of the transistor 51a is grounded, and an ignition signal is applied to its base. One end of the secondary winding 52b of the ignition coil 52 is connected to a diode 11
2 cathodes. The anode of the diode 112 is connected to the center electrode 50a of the ignition plug 50 provided for each cylinder via the distributor 53. The outer electrode 50b of the spark plug 50 is grounded.

The diode 112 and the distributor 5
3 is connected to a diode 114 and a constant voltage power supply 116.
And an ion current detection resistor 118. Therefore, a constant voltage is applied to the ignition plug 50 by the constant voltage power supply 116 during the ignition cycle. A connection point between the constant voltage power supply 116 and the ion current detection resistor 118 gives an output (voltage signal) of the ion current detection circuit 110. Then, the output of the ion current detection circuit is guided to the engine ECU 90.

Next, an ignition device and an ion current detection circuit 1
The operation of No. 10 will be described. First, when the ignition signal becomes high and the transistor 51a is turned on, a current flows through the primary winding 52a of the ignition coil. Next, when the ignition signal is turned low and the transistor 51a is turned off to cut off the primary current, the secondary winding 5 of the ignition coil 52 is turned off.
A high voltage is induced in 2b, and as a result, a spark discharge occurs in the spark plug 50. That is, when a negative high voltage is applied to the center electrode 50a of the ignition plug 50, spark discharge occurs between the center electrode 50a and the outer electrode (ground electrode) 50b, and the ignition coil secondary winding 52b A current circulates through the ignition plug 50 and the diode 112 to the secondary winding 52b.

The spark discharge at the spark plug 50 causes
When the mixture in the combustion chamber ignites and burns, the mixture is ionized. When the air-fuel mixture is in an ionized state, there is conductivity between both electrodes of the ignition plug 50. In addition, since a voltage is applied between both electrodes of the ignition plug 50 by the constant voltage power supply 116, an ionic current flows. That is, the ion current is supplied from the positive electrode of the constant voltage power supply 116 to the ion current detection resistor 118 and the ignition plug 50.
Then, the current flows through the diode 114 to the negative electrode of the constant voltage power supply 116. Then, a voltage of “ion current value × detection resistance value” appears at a connection point between the ion current detection resistor 118 and the constant voltage power supply 116, and the voltage is supplied to the ECU 90 as an ion current detection circuit output.

Note that, even in the same combustion state, the peak value of the output voltage of the ion current detection circuit (hereinafter simply referred to as ion output) varies for each combustion. However, when the ion output is measured for a certain number of times of combustion in the same combustion state and the average value is obtained, the average value has a certain correlation with the air-fuel ratio. FIG. 4 is a characteristic diagram showing a relationship between an air-fuel ratio and an average value of ion outputs over a predetermined number of times. As shown in this figure, the ion output average value becomes maximum near the output air-fuel ratio (the weight ratio of air and fuel (about 12.5) at which the output becomes maximum), and the air-fuel ratio leaner than that also occurs. There is also a tendency for the air-fuel ratio on the rich side to decrease.

FIG. 5 is a time chart showing the behavior of the engine speed, the injection correction coefficient, and the air-fuel ratio during and after the start of the engine to explain the air-fuel ratio control according to the present invention. When starting (cranking) is started at time t ₀ , the rotation speed rapidly increases, but when a complete explosion is reached, the rotation speed decreases, and at time t ₁ , the rotation speed drops to a constant rotation speed. . During this start-up period, the air-fuel ratio cannot be detected, so that a mixture having a rich air-fuel ratio is burned in consideration of the variation.

Normally, the air-fuel ratio sensor is not activated until a certain temperature is reached. Conventionally, the operation of such a rich control is performed for several seconds (15 to 20 seconds) after the start until the air-fuel ratio sensor is activated. Had been continued. However, in the present invention, after starting, the first idling period early from the time t ₁ the rotational speed is stable up to time t _2, the detected ion current, for detecting an air-fuel ratio at the present time based on the current value Like that. In the example shown in FIG. 5, in the period from t ₁ to t _2, the actual air-fuel ratio is, than the target air-fuel ratio of the first idling operation has become lean, so that the fact is detected.

At time t ₂ when the determination of the combustion state by the ion current, that is, the determination of the air-fuel ratio is completed, the injection correction coefficient is set according to the detected air-fuel ratio, and the fuel injection amount is changed. In the example of FIG. 5, since it is detected that the actual air-fuel ratio is leaner than the target air-fuel ratio, the injection correction coefficient is set to a value that increases the fuel injection amount. Incidentally, the injection correction coefficient at the time t ₂ is gradually then gradually decreases, as the warm-up proceeds, the ratio of fuel drawn into among the barrel of the injected fuel considering going to increase It is.

However, as described above, the ion current value does not always accurately reflect the air-fuel ratio because it changes due to factors other than the combustion state, such as deterioration of the spark plug. In the example shown in FIG. 5, the time t ₂ after, despite the injection correction coefficient is large and the air-fuel ratio becomes leaner than the target air-fuel ratio, which is the ion current value is the actual air This is because the air-fuel ratio richer than the fuel ratio is displayed, and the increase in the injection amount is insufficient. That is, in order to achieve the target air-fuel ratio, the injection correction coefficient needs to be the one indicated by the dotted line, and a detection error has occurred.

[0028] Therefore, in the present invention, at time t ₃ when the feedback control is started air-fuel ratio sensor based on the output of the air-fuel ratio sensor is activated, based on the actual air-fuel ratio detected by the air-fuel ratio sensor, an ion current Learning the detection error due to Then, the learned detection error is reflected the next time the air-fuel ratio control is performed based on the ion current after the engine is started. Hereinafter, a specific example of these processes will be described in detail.

FIG. 6 is a flowchart of the air-fuel ratio detection process using the ion current. This processing is performed at time t _{1 in} FIG.
Started from. First, in step 202, cylinder j
(J = 1, 2, 3, 4), a predetermined number of times (for example, 32
The average value of the ion output detected for each combustion over the first combustion is calculated, and is defined as IAV (j). This I
AV (j) is an amount correlated with the air-fuel ratio as shown in FIG. Next, at step 204, the current engine speed NE is calculated.

Finally, at step 206, cylinder j (j
= 1, 2, 3, 4), an injection correction coefficient KION (j) corresponding to the average ion output value IAV (j) and the engine speed NE is calculated by referring to a predetermined map. The injection correction coefficient KION (j) based on the ion current
Is experimentally determined in advance to correct the injection amount so that the target air-fuel ratio in the first idle state is achieved. In this example, the injection correction coefficient is adapted based on the ion output average value and the rotation speed, but by further adding the ignition timing and the like as a parameter,
Further accuracy can be improved.

FIG. 7 is a flowchart of the air-fuel ratio control process using the ion current. This process, during the period from time t ₂ to end the determination of the air-fuel ratio due to the ion current until time t ₃ when it is possible to feedback control by the air-fuel ratio sensor is performed for each injection cycle. First, in step 302, a current engine operating state is detected from outputs from various sensors. Next, in step 304,
Based on the detected operating state, the amount of air G _{A taken} into the cylinder during the intake stroke is calculated.

[0032] Next, in step 306, the G _F ← G _A / R _AF becomes operational, and calculates the fuel injection amount G _F to achieve the target air-fuel ratio R _AF in the fast idle state. Then
In step 308, the fuel injection amount G _F a basic injection time T
Convert to P. Next, at step 310, the number j (1, 2, 3, or 4) of the cylinder related to the current injection is determined.

Next, at step 312, the basic injection time TP is corrected to obtain the final injection time T by the calculation of T ← TP * [KION (j) + ΔKAFS (j)] * α. Note that KION (j) is an injection correction coefficient determined in the air-fuel ratio detection process using the ion current, as described above. ΔKAFS (j) is a correction amount obtained in an air-fuel ratio detection error learning process described later. Α is a correction coefficient based on other factors such as the engine cooling water temperature. Note that “[KION (j) + ΔK
AFS (j)] * α ″ corresponds to the injection correction coefficient in FIG. 5. In the last step 314, T is set in the injection drive circuit as the injection time of the j-th cylinder.

FIG. 8 is a flowchart of the air-fuel ratio detection error learning process. This process is executed at time t ₃ (see FIG. 5) at which the air-fuel ratio sensor is activated and feedback control based on the output of the air-fuel ratio sensor is started. First, in step 402, cylinder j (j = 1, 2, 3,
For each 4), the average value of the ion output detected for each combustion over a predetermined number of combustions is calculated, and the average value is calculated based on the IAV.
(J). Next, at step 404, the current engine speed NE is calculated.

Next, at step 406, cylinder j (j
= 1, 2, 3, 4), the air-fuel ratio AFION (j) according to the average ion output value IAV (j) and the engine speed NE is calculated by referring to a predetermined map.
In this example, the air-fuel ratio is calculated based on the ion output average value and the rotation speed, but an ignition timing or the like may be further added as a parameter. Next, step 408
Now, the air-fuel ratio AF based on the output of the air-fuel ratio sensor 75 is referred to by referring to a predetermined map as shown in FIG.
C is detected.

Next, at step 410, cylinder j (j
= 1,2,3,4), the calculation of ΔAF (j) ← AFION (j) −AFC gives the air-fuel ratio detection error ΔA due to the ion current.
Find F (j). This ΔAF (j) is an amount representing how much the air-fuel ratio deviates to the lean side from the actual air-fuel ratio.

In the last step 412, cylinder j (j = j)
The correction value ΔKAFS (j) for compensating the air-fuel ratio detection error due to the ion current is obtained by the calculation of ΔKAFS (j) ← 1 / (− ΔAF (j)) for each of 1, 2, 3, 4). As described above, this correction value ΔKAFS (j) is used in step 31 of the air-fuel ratio control process using the ion current shown in FIG.
Used in 2. Therefore, the correction value ΔKAFS
(J) is the injection correction coefficient KION (j) based on the ion current when ΔAF (j)> 0, that is, when the actual air-fuel ratio is richer than the air-fuel ratio based on the ion current.
On the other hand, when ΔAF (j) <0, that is, when the actual air-fuel ratio is leaner than the air-fuel ratio based on the ionic current, the injection correction coefficient KION (j) based on the ionic current is increased. Act like so.

In the above embodiment, even if the ion current changes due to the deterioration of the plug, the deposit in the combustion chamber, or the like, the change is compensated. In addition, since the ion current is detected for each cylinder and the injection amount is determined,
The air-fuel ratio control for each cylinder can be performed even when the plug detectability differs for each cylinder, such as when the plug is replaced only for a specific cylinder.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various embodiments can be adopted. For example, various circuit configurations can be considered as the ion current detection circuit. Further, the control method of the fuel injection amount is not limited to the illustrated method.

[0040]

As described above, according to the present invention,
In the air-fuel ratio control device based on the ionic current, the air-fuel ratio can be accurately controlled regardless of the ionic current fluctuation due to factors other than the combustion state, such as deterioration of the ignition plug.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine including an air-fuel ratio control device according to one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an air-fuel ratio and an output voltage of an air-fuel ratio sensor.

FIG. 3 is a diagram showing a circuit configuration of an ignition device and an ion current detection circuit.

FIG. 4 is a characteristic diagram showing a relationship between an air-fuel ratio and an average value of ion output at a predetermined number of times.

FIG. 5 shows the engine speed at the time of starting the engine and after starting the engine,
5 is a time chart showing behaviors of an injection correction coefficient and an air-fuel ratio.

FIG. 6 is a flowchart of an air-fuel ratio detection process using an ion current.

FIG. 7 is a flowchart of an air-fuel ratio control process using an ion current.

FIG. 8 is a flowchart of an air-fuel ratio detection error learning process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... In-line 4 cylinder 4-stroke cycle reciprocating gasoline engine 2 ... Cylinder block 3 ... Cylinder head 4 ... Cylinder 5 ... Piston 6 ... Connecting rod 7 ... Crank shaft 8 ... Combustion chamber 9 ... Intake port 10 ... Exhaust port 11 ... Intake valve 12 ... Exhaust valve 13 ... Intake side camshaft 14 ... Exhaust side camshaft 15 ... Intake side cam 16 ... Exhaust side cam 17,18,19 ... Timing pulley 20 ... Timing belt 30 ... Intake passage 31 ... Air cleaner 32 ... Throttle valve 33 ... Surge tank 34 ... Intake manifold 35 ... Idle adjust passage 36 ... Idle speed control valve (ISCV) 40 ... Injector 41 ... Fuel tank 42 ... Fuel pump 43 ... Fuel pipe 50 ... Ignition plug 51 ... Igniter 52 ... Ignition coil 53 ... Point Distributor 60 Exhaust passage 61 Exhaust manifold 62 Catalytic converter 70 Air flow meter 71 Vacuum sensor 72 Throttle opening sensor 73 Intake temperature sensor 74 Water temperature sensor 75 Air-fuel ratio sensor 80 Crank reference position sensor 81 Crank Angle sensor 82 Idle switch 83 Vehicle speed sensor 90 Engine ECU 100 Battery 110 Ion current detection circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G019 AB02 CD06 DC01 DC06 GA00 GA01 GA05 GA08 GA09 GA11 GA13 GA18 LA05 3G084 BA09 BA13 DA04 DA22 EB11 EB17 FA05 FA10 FA11 FA20 FA26 FA29 FA33 FA38 3G301 JA16 MA01 MA11 ND01 ND21 PC07Z PA11Z PD03A PD03Z PE01Z PE03Z PE08Z PF01Z

Claims (1)

[Claims] 1. An ion current detecting means for detecting an ion current corresponding to an amount of ions generated by combustion of an air-fuel mixture in a cylinder of an internal combustion engine; an air-fuel ratio sensor provided in an exhaust passage of the engine; And correcting a detection error by the ion current detection unit based on an ion current value detected by the ion current detection unit and an air-fuel ratio detected by the air-fuel ratio sensor when the air-fuel ratio sensor is activated. Correction value learning means for learning a correction value, based on an ion current value detected by the ion current detection means when the air-fuel ratio sensor is inactive, and a correction value learned by the correction value calculation means. An air-fuel ratio control device for an internal combustion engine, comprising: a fuel injection amount adjusting means for adjusting a fuel injection amount.