JPS63147944A - Air-fuel ratio learning control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make a uniform learning correction factor accurately correspond to a change in air density, by updating a learning correction factor every operational region according to a deviation of an air-fuel ratio feedback correction factor from a reference value, and correcting the uniform learning correction factor according to an average of updated quantities. CONSTITUTION:A control circuit 14 reads a suction air quantity from a data map according to a detection value from a throttle sensor 15 and an engine speed from a crank angle sensor 17, and computes a basic fuel injection quantity. When an engine is at low and medium speeds and under low and medium loads, the control circuit 14 computes an air-fuel ratio feedback correction factor according to a detection value from an O2 sensor 20, and updates a learning correction factor every operational region corresponding to the engine speed and the basic fuel injection quantity, according to a deviation of the learning correction factor from a reference value. An average of updated quantities is multiplied by a correction constant to correct and rewrite a uniform learning correction factor corresponding to a change in air density. A fuel injection quantity is computed from the basic fuel injection quantity, the air-fuel ratio feedback correction factor, the learning correction factor every operational region and the uniform learning correction factor.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to the electronic side having an air-fuel ratio feedback control function. The present invention relates to an air-fuel ratio learning control device for an automobile internal combustion engine having an In fuel injection device, and particularly relates to an air-fuel ratio learning control device that can respond favorably to changes in air density due to altitude or the like.

<Prior Art> Conventionally, in an internal combustion engine having an electronically controlled fuel injection device with an air-fuel ratio feedback control function,
Air-fuel ratio learning control devices such as those disclosed in Japanese Patent Application Laid-open No. 90944 and Japanese Patent Application Laid-open No. 190142/1983 are employed.

This is based on the signal from the 02 sensor installed in the engine exhaust system, which calculates the basic fuel injection amount from engine operating state parameters related to the amount of air taken into the engine (for example, engine intake air flow rate and engine speed). The reference value of the feedback correction coefficient during air-fuel ratio feedback control, in which the fuel injection amount is calculated by correcting it with a feedback correction coefficient set by proportional/integral control based on the feedback control of the air-fuel ratio to the target air-fuel ratio. The deviation from the basic fuel injection amount is learned for each predetermined area of the engine operating state and a learning correction coefficient is determined. 2. When calculating the fuel injection amount, the basic fuel injection amount is corrected by the area-specific learning correction coefficient, and the feedback correction coefficient is used. The base air-fuel ratio obtained from the fuel injection amount calculated without correction is made to match the target air-fuel ratio, and during air-fuel ratio feedback control, this is further corrected using a feedback correction coefficient to calculate the fuel injection amount. .

According to this, it is possible to eliminate the follow-up delay of the feedback control during the transient operation during the air-fuel ratio feedbank control, and it is possible to accurately obtain the desired air-fuel ratio when the air-fuel ratio feedback control is stopped.

In addition, a system that determines the basic fuel injection ff1Tp from the throttle valve opening α and the engine speed N (for example, the intake air flow rate Q is determined from α and N by referring to a map, and Tp-
A system that calculates Tp from the formula Q/N (K is a constant) or an air flow meter that calculates the intake air flow i.
A system that detects Q and calculates the basic fuel injection amount 'rp=K・Q/N from this and the engine speed N, and uses a flap type (volume flow rate detection type) as an air flow meter. Changes in air density are not reflected in the calculation of the basic fuel injection amount, but according to the learning control described above, as long as the learning progresses well, changes in air density due to altitude or intake temperature can be handled. can.

<Problems to be solved by the invention> However, if we consider the case of suddenly climbing to a high altitude (mountain), it is difficult to learn by the method of learning by area of the engine operating state because the driving pattern is transient when climbing a mountain. It is difficult to decide on an area for learning, and even if learning is possible, the area is limited, and in the majority of areas, learning hardly progresses. As a result, when you start normal driving on flat ground near the top of a mountain, the air-fuel ratio will deviate significantly from the target air-fuel ratio due to the control delay of the air-fuel ratio feedback control, and when the air-fuel ratio feed hack control is stopped. Therefore, there was a problem in that it resulted in poor drivability.

This requires learning and correcting changes in air density from the deviation from the basic value of the feedback correction coefficient during air-fuel ratio feedbank control, but some of the learned deviations include fuel injection valves, throttle bodies, etc. It also includes deviations in the base air-fuel ratio that depend on engine operating conditions due to variations in parts, etc., so it is impossible to separate them from changes in air density.
Changes in air density, which should be able to be learned regularly, must be learned for each area while the engine is operating, and if you suddenly climb to a high altitude, you will not be able to learn for each area, and learning will not actually progress. This is due to

In view of these conventional problems, the present invention provides an air-fuel ratio learning control for an internal combustion engine that can quickly learn air density changes and perform air-fuel ratio learning control well when driving up a mountain. The purpose is to provide equipment.

Means for Solving the Problems> In order to achieve the above object, the present invention uniformly learns air density changes mainly for altitude correction, in addition to area-based learning correction coefficients. Set a uniform learning correction coefficient for the purpose, calculate the average value of the update amount of the area-specific learning correction coefficient updated within a predetermined period, and perform uniform learning correction by considering this as the uniform air density change for all areas. The structure is such that it is replaced with coefficients.

Therefore, the air-fuel ratio learning control device according to the present invention, as shown in FIG. 1, is configured to include the following means A to M.

(A) Engine operating state detection means for detecting the engine operating state including at least parameters related to the amount of air taken into the engine. (B) Detecting engine exhaust components and thereby detecting the air-fuel ratio of the engine intake mixture. Air-fuel ratio detection means (C) Basic fuel injection amount setting means for setting the basic fuel injection amount based on the parameters detected by the engine operating state detection means (D) The basic fuel injection amount for all areas of the engine operating state. A rewritable uniform learning correction coefficient storage means (E) storing a uniform learning correction coefficient for uniformly correcting the basic fuel injection amount for each area of the engine operating state. rewritable area-based learning correction coefficient storage means (F) area-based learning for searching area-based learning correction coefficients for areas in corresponding engine operating states from the area-based learning correction coefficient storage means based on the actual engine operating state; Correction coefficient search means (G) Feedback correction for comparing the air-fuel ratio detected by the air-fuel ratio detection means with the target air-fuel ratio and correcting the basic fuel injection amount so as to bring the actual air-fuel ratio closer to the target air-fuel ratio. Feedback correction coefficient setting means (H) for increasing or decreasing a coefficient by a predetermined amount; a basic fuel injection amount set by the basic fuel injection amount setting means; a uniform learning correction coefficient stored in the uniform learning correction coefficient storage means; Fuel injection amount calculation means (1) for calculating the fuel injection amount based on the area-specific learning correction coefficient searched by the area-specific learning correction coefficient search means and the feed hack correction coefficient set by the feedback correction coefficient setting means. a fuel injection means (J) for injecting fuel into the engine on and off in response to a drive pulse signal corresponding to the fuel injection amount calculated by the fuel injection amount calculation means; area-based learning correction coefficient correction means (K) for correcting and rewriting the area-based learning correction coefficients in the area-based learning correction coefficient storage means in a direction to reduce the deviation from the area-specific learning correction coefficient storage means; Update amount average value calculation means (L) for calculating the average value of the update amount of the area-specific learning correction coefficient for each area when the area-specific learning correction coefficient is updated in the area where the engine is in operation state; and the uniform learning correction coefficient storage. Uniform learning correction coefficient correction means (M) for updating the uniform learning correction coefficient for correcting and rewriting the uniform learning correction coefficient of the uniform learning correction coefficient storage means by adding the average value obtained by the update amount average value calculating means to the uniform learning correction coefficient of the means; Correcting and rewriting the area-specific learning correction coefficient in the area-specific learning correction coefficient storage means by subtracting the average value by the update amount average value calculation means from the area-specific learning correction coefficient which is the basis of the calculation by the quantity average value calculation means. Second area-specific learning correction coefficient correction means (Operation) The basic fuel injection amount setting means C sets the basic fuel injection amount corresponding to the target air-fuel ratio based on parameters related to the amount of air taken into the engine. , the area-specific learning correction coefficient retrieval means F searches the area-specific learning correction coefficient storage means E for the area-specific learning correction coefficient of the area corresponding to the actual engine operating state, and the feedback correction coefficient setting means G searches the area-specific learning correction coefficient for the area corresponding to the actual engine operating state. The air-fuel ratio is compared with the target air-fuel ratio, and the feedback correction coefficient is set by increasing or decreasing a predetermined amount based on, for example, proportional/integral control so that the actual air-fuel ratio approaches the target air-fuel ratio.

Then, the fuel injection amount calculation means H corrects the basic fuel injection amount with the uniform learning correction coefficient stored in the uniform learning correction coefficient storage means, and also with the area-specific learning correction coefficient,
Further, the fuel injection amount is calculated by correcting it using a feedback correction coefficient. The fuel injection means I is actuated by a drive pulse signal corresponding to this fuel injection interval.

On the other hand, the area-specific learning correction coefficient correction means J learns the deviation from the reference value of the feedback correction coefficient for each area of the engine operating state, and makes area-specific learning correction corresponding to the area of the engine operating state in the direction of decreasing this deviation. The coefficients are corrected and the data in the area-specific learning correction coefficient storage means E is rewritten.

In this way, parts variations, etc., including air density changes, are learned for each area.

Further, the update amount average value calculation means calculates the average value of the update amount of the area-based learning correction coefficient for each area when the area-based learning correction coefficient is updated in a plurality of areas within a predetermined period. When this calculation is performed, the uniform learning correction coefficient correction means adds the average value obtained by the update amount average value calculation means K to the uniform learning correction coefficient in the uniform learning correction coefficient storage means and stores the uniform learning correction coefficient storage means. Rewrite the data. In this way, the average value is regarded as the air density change for all areas, and is uniformly replaced with the learning correction coefficient. Conversely, the second area-specific learning correction coefficient correction means M subtracts the average value calculated by the update amount average value calculation means K from the area-specific learning correction coefficient, which is the basis of calculation by the update amount average value calculation means. The data in the area-specific learning correction coefficient storage means E is rewritten. In this way, the area-by-area learning correction coefficient is made to include parts variations other than the air density change.

<Example> The present invention will be explained in detail below.

In FIG. 2, air is taken into the engine 1 through an air cleaner 2, a throttle body 3, and an intake manifold 4. As shown in FIG.

A throttle valve 5 that operates in conjunction with an accelerator pedal (not shown) is provided within the throttle body 3, and a fuel injection valve 6 serving as fuel injection means is provided upstream thereof. This fuel injection valve 6 is an electromagnetic fuel injection valve that is energized to a solenoid to open the valve and then stopped energizing to close the valve. Fuel is injected and supplied from a fuel pump that does not operate, and is adjusted to a predetermined pressure by a pressure regulator. Although this example is a single point injection system,
A multi-point injection system may be used in which a fuel injection valve is provided for each cylinder in a branch of the intake manifold or in an intake boat of the engine.

An ignition plug 7 is provided in the combustion chamber of the engine 1.

A high voltage generated by an ignition coil 8 is applied to the ignition plug 7 via a distributor 9 based on an ignition signal from a control unit 14, thereby igniting a spark to ignite and burn the air-fuel mixture.

From engine 1, exhaust manifold 10. Exhaust duct 11
．． Exhaust gas is discharged via the three-way catalyst 12 and the muffler 13.

The control unit 14 includes a CPU and a ROM.

Equipped with a microcomputer that includes a RAM, an A/D converter, and an input/output interface, it receives human input signals from various sensors, performs arithmetic processing as described below, and controls the fuel injection valve 6 and ignition coil 8. Control operation.

As the various sensors, a potentiometer type throttle sensor 15 is provided on the throttle valve 5,
A voltage signal corresponding to the opening degree α of the throttle valve 5 is output.

Also provided within the throttle sensor 15 is an idle switch 16 that is turned ON when the throttle valve 5 is in the fully closed position.

Further, a crank angle sensor 17 is built into the distributor 9 and outputs a position signal every 2 degrees of crank angle and a reference signal every 180 degrees of crank angle (in the case of 4 cylinders).

Here, the engine rotation speed N can be calculated by measuring the number of pulses of the position signal or the cycle of the reference signal per unit time.

Further, a water temperature sensor 18 that detects the engine cooling water temperature Tw, a vehicle speed sensor 19 that detects the vehicle speed vsp, and the like are provided.

These throttle sensors 15. The crank angle sensor 17 and the like are means for detecting the engine operating state.

Further, an 02 sensor 20 is provided in the exhaust manifold lO. This 0□ sensor 20 is a known sensor whose electromotive force suddenly changes when the air-fuel mixture is combusted near the stoichiometric air-fuel ratio, which is the target air-fuel ratio.

Therefore, the 0□ sensor 20 is an air-fuel ratio (rich/lean) detection means.

Furthermore, a battery 21 is connected to the control unit 1-14 via an engine key switch 22 as its operating power source and for detecting power supply voltage.

In addition, as an operating power source for the RAM in the control unit 14, a battery 21 is connected via a suitable stabilized power source without going through the engine key switch 22 in order to retain the memory contents even after the engine key switch 22 is turned off. .

Here, the CPIJ of the microcomputer stored in the control unit 14 is executed by the programs (fuel injection amount calculation routine, feedback control zone determination routine, proportional/integral control routine) on the ROM shown as flowcharts in FIGS. 3 to 7. , a first learning routine, and a second learning routine) to control fuel injection.

The basic fuel injection amount setting means, the area-based learning correction coefficient search means, the feedback correction coefficient setting means, the fuel injection amount calculation means, the area-specific learning correction coefficient correction means, the updated average value calculation means, the uniform learning correction coefficient correction means, and The function as the second area-specific learning correction coefficient correction means is achieved by the program. Further, a RAM is used as the uniform learning correction coefficient storage means and the area-specific learning correction coefficient storage means.

Next, the state of the arithmetic processing of the microcomputer in the control unit 14 will be explained with reference to the flowcharts shown in FIGS. 3 to 7.

In the fuel injection amount calculation routine shown in FIG.
(Denoted as Sl in the figure. The same applies hereinafter), the throttle valve opening α detected based on the signal from the throttle sensor 15 and the engine rotation speed N calculated based on the signal from the crank angle sensor 17. Load.

In step 2, the intake air flow IQ corresponding to the throttle valve opening α and the engine speed N is determined in advance through experiments, etc., and Q corresponding to the actual α and N is searched by referring to a map in the ROM that is stored. and load it.

In step 3, the basic fuel injection amount Tp corresponding to the intake air amount per unit rotation is determined from the intake air flow rate Q and the engine rotation speed N.
=K - Q/N (K is a constant) is calculated. here,
Steps 1 to 3 correspond to basic fuel injection amount setting means.

In step 4, the rate of change in the throttle valve opening α detected based on the signal from the throttle sensor 15 or the acceleration correction caused by switching the idle switch 16 from ON to OFF is detected based on the signal from the water temperature sensor 18. Then, various correction coefficients C0EF including water temperature correction factors are set according to the engine cooling water temperature Tw.

In step 5, RA is uniformly used as a learning correction coefficient storage means.
A uniform learning correction coefficient storage means stored at a predetermined address of M is read. Incidentally, the uniform learning correction coefficient KAL□ is stored as the initial value O at the time when learning has not started, and this is read.

In step 6, the area-specific learning correction coefficient K14AP is stored in the RAM as an area-specific learning correction coefficient storage means corresponding to the engine speed N representing the engine operating state and the basic fuel injection amount (load) Tp. With reference to the map, KM1 corresponding to the actual N and Tp is searched and read. This part corresponds to the area-specific learning correction coefficient search means. The learning correction coefficient K MAP for each area is based on the engine speed N.
With Tp as the horizontal axis and basic fuel injection amount Tp as the vertical axis, areas of the engine operating state are divided into grids of about 8 x 8, and □ is stored in the area learning correction coefficient for each area, and learning starts. At the time when the data is not set, the initial value 0 is stored in all cases.

In step 7, the feedback correction coefficient LA is set by the proportional/integral control routine shown in FIG. 5, which will be described later.
Load MBDA. Furthermore, this feedback correction coefficient L
The reference value of AMBDA is l.

In step 8, a voltage correction numerator s is set based on the voltage value of the battery 21. This is to correct changes in the injection flowmeter of the fuel injection valve due to fluctuations in battery voltage.

In step 9, the fuel injection amount Ti is calculated according to the following equation. This part corresponds to the fuel injection amount calculation means.

T i = T p −C0EF ・(
LAMBDΔ+ K ALT + K MAP)+
In step 10, the calculated Ti is set in the output register. As a result, at a predetermined fuel injection timing synchronized with engine rotation (for example, every two rotations), a drive pulse signal having a Ti pulse is applied to the fuel injection valve 6, and fuel injection is performed.

Figure 4 shows the feedbank control zone determination routine, in which air-fuel ratio feedback control is performed in principle at low-medium speeds and low-medium loads, and air-fuel ratio feedback control is stopped at high speeds or high loads. It is something.

In step 21, a comparison Tp is searched from the engine speed N,
In step 7 step 22, the actual basic fuel injection amount 'rp (actual T
Compare p) with comparison Tp.

If actual Tp≦comparison'rp, that is, if the rotation is low or medium and the load is low or medium, the process proceeds to step 23 and the delay timer (
After resetting the λcont flag (counted up by the clock signal), the process proceeds to step 26, where the λcont flag is set to 1. This is to perform feedback control of the air-fuel ratio in the case of low to medium speeds and low to medium loads.

If actual Tp>comparison Tp, that is, if the rotation is high or the load is high, in principle, proceed to step 27 and set λcon
Set the t flag to O. This is to stop the feedback control of the air-fuel ratio, separately obtain a rich output air-fuel ratio, suppress the rise in exhaust temperature, and prevent the engine 1 from seizing and the catalyst 12 from burning out.

Here, even in the case of high rotation or high load, by comparing the value of the delay timer with a predetermined value in step 24, after shifting to high rotation or high load, until a predetermined time elapses, step 26 The process continues to set the λcant flag to 1, and continues feedback control of the air-fuel ratio. This is to increase the opportunity to learn about changes in air density since mountain climbing is performed in a high rotation/high load range. However, if the engine speed N exceeds a predetermined value (for example, 3800 rpm) as determined in step 25, the feedback control of the air-fuel ratio is stopped for safety reasons.

FIG. 5 shows a proportional/integral control routine, which is executed at predetermined time intervals (for example, 10 ms), thereby setting the feedback correction coefficient LAMBDA. Therefore, this routine corresponds to feedback correction coefficient setting means.

In step 31, the value of the λcon t flag is determined, and O
If so, this routine ends. In this case, the feedback correction coefficient LAMBDA is the previous value (or the reference value l
), and feedback control of the air-fuel ratio is stopped.

If the λcon t flag is 1, the process advances to step 32 and the output voltage of the 02 sensor 20 is determined. 2, and in the next step 33, the slice reher voltage V r corresponding to the stoichiometric air-fuel ratio is read.
By comparing with af, it is determined whether the air-fuel ratio is rich or lean.

When the air-fuel ratio is lean (Voz<"raf), the process proceeds from step 33 to step 34, where it is determined whether or not it is the time of reversal from rich to lean (immediately after the reversal). When the air-fuel ratio is reversed, the process proceeds to step 35. The feedback correction coefficient LA
Increase MBD^ by a predetermined proportionality constant of 2 minutes relative to the previous value. Otherwise, the process proceeds to step 36, where the feedback correction coefficient LAMBDA is increased by a predetermined integral constant of 1 minute from the previous value, and thus the feedback correction coefficient LA? '1
Increase BDA at a constant slope. Note that p>>l.

When the air-fuel ratio is rich (■.2>■, .f), the process proceeds from step 33 to step 37, where it is determined whether it is the time of reversal from lean to rich (immediately after reversal), and when the air-fuel ratio is reversed, step 38 is performed. Proceed to feedback correction coefficient LAMB
DA is decreased by a predetermined proportionality constant of 2 minutes from the previous value. Otherwise, the process proceeds to step 39, where the feedback correction coefficient LAMBDA is decreased by a predetermined integral constant of 1 with respect to the previous value, and thus the feedback correction coefficient LAMBDA is decreased at a constant slope.

FIG. 6 shows the first learning routine. This first learning routine corresponds to area-specific learning correction coefficient correction means.

In step 80, the value of the λcon t flag is determined and 0
In this case, the routine proceeds to step 82, where the count value C is cleared, and then this routine ends. This is because learning cannot be performed when air-fuel ratio feedback control is stopped.

When the λcont flag is 1, that is, during air-fuel ratio feedbank control, the process advances to step 81.

In step 81, it is determined whether or not the engine speed N representing the engine operating state and the basic fuel injection mTp are in the same area as the previous time, and if the area has changed, the process proceeds to step 82 and the count value C is cleared. After that, this routine ends.

If the area is the same as the previous time, in step 83 the output of the 0□ sensor 20 is inverted, that is, the feedback correction coefficient LA
It is determined whether or not the direction of increase/decrease in MBDA has been reversed. Each time this routine is repeated and reversed, a count value C representing the number of reversals is air-filled in step 84. For example, when C=3, step 85 Proceeding to step 86, the reference value 1 of the current feedback correction coefficient LAMBDA is determined.
The deviation from (LA gate BDA-1) is ΔLAMBDA,
Temporarily memorize it as , and start learning.

When C=4 or more, the process proceeds from step 85 to step 87, where the feedback correction coefficient L at that time is
Deviation of AMBDA from standard value 1 (LAMBDA -1
) is temporarily stored as ΔLAMBDA t. ΔLAMBDA and ΔLA gate BDA stored at this time
As shown in FIG. 8, z is the upper and lower peak values of the deviation from the reference value 1 of the feedback correction coefficient LAMBDA from the previous (for example, the third) reversal to the current (for example, the fourth) reversal.

In this way, the feedback correction coefficient LAMB'DA
The upper and lower peak values ΔLAMBDA of the deviation from the reference value l
,.

Once ΔLAMBDA2 is determined, the process proceeds to step 88 to determine their average value -N[four sides 1].

Next, the process proceeds to step 89, where the learning correction coefficient for each area is stored in the map on the RAM corresponding to the current area.
AP (initial value 0) is searched and not read.

Next, proceeding to step 90, a new area-specific learning correction coefficient K is calculated by adding a predetermined ratio of the average value ΔLAMBDA of the deviation from the reference value of the feedback correction coefficient to the current area-specific learning correction coefficient KMAP according to the following formula. , corrects and rewrites the area-by-area learning correction coefficient data for the same area of the map on the RAM.

KJIAP ”K, 4Ap +M・τmouth MBDA (M is an addition rate constant, Q<M<1) After this, in step 91, ΔLAMBD for the next learning
Substitute Az into ΔLAMBDA.

FIG. 7 shows the second learning routine. This second learning routine functions as update amount average value calculation means, uniform learning correction coefficient correction means, and second area-based learning correction coefficient correction means.

In step 101, the value of a timer (counted up by a clock signal) is compared with a predetermined value (for example, 10 minutes), and if it is within the predetermined value, the process proceeds to step 102, where K MAP learning (i.e., the step in FIG. 6) is performed. 90) has been executed, and only if it has been executed, the process advances to step 103 to determine whether the flag for determining the number of learning times is 0. If YES, the process advances to step 104 to complete the learning. KMAP update amount ΔK due to area and learning performed
MAPI (=M·ΔLAMBDA) is stored, and the flag is set to 1 in step ``105''.

Then, when the process returns to step 101 and KMAP learning is executed again while the timer value is within the predetermined value, the flag is set to 1 in step 105, so the determination in step 103 becomes NO and the process proceeds to step 106. Proceed to Step 1 to determine whether the area where learning was performed this time is the same as the area where learning was performed last time.
Returning to step 04, the update amount Δ is newly stored and updated with □, and if different, the process proceeds to step 107 and A, . . . are stored in this area and the update amount Δ.

In this way, when learning is performed in two different areas, the process proceeds to step 108, where the flag is set to O and the timer is reset, and then the process proceeds to step 109, where the update amounts ΔKMAPI and Δ of these two areas are changed. , 2 and calculates the average value ΔK MAFM. This step 101~
A portion 109 corresponds to update amount average value calculation means.

Next, in step 110, a predetermined address in the RAM is written.
Read out the current uniform learning correction coefficient KALT that has been α.

Next, proceeding to step 111, the data of the new uniform learning correction coefficient correction means is obtained by adding the correction value corrected by multiplying the update amount average value ΔKMAPM by the correction constant k to the current uniform learning correction coefficient KALT according to the following formula. Correct and rewrite. This step 111 corresponds to uniform learning correction coefficient correction means.

KAL? ←KALT 10k・Δ□PM Next, proceed to step 112 and calculate the update amount average value ΔK, A, according to the following formula.
The correction values k and ΔK of the update amount average value are calculated from the learning correction coefficient K14AP for each area based on the calculation of , respectively.
A new learning correction coefficient K MAP for each area is calculated by subtracting the MA process, and the data of the learning correction coefficient K MAP for the same area in the map on the RAM is rewritten. This step 112 corresponds to the second area-specific learning correction coefficient correction means.

K, A, ←KMAP k・ΔK MAPM In this way, the average value of the update amount of the area-specific learning correction coefficient updated in different areas within a predetermined period is calculated, and this is calculated as the air density that changes uniformly in all areas. The learning correction coefficient is uniformly replaced based on the average value.

On the other hand, if it is determined in step 101 that the value of the timer exceeds the predetermined value, that is, if learning has not been performed in a different area within the predetermined time, the process proceeds to step 113 where the learning correction coefficient K ALT is uniformly incremented. Predetermined amount ΔK every time
After updating with the value decreased by ALT, step 114
reset the flag to 0.

In other words, deceleration operation continues for a long time when exiting the stage, and λ control is not performed, so learning of K MAP is not performed. Assuming that it is increasing, it is decreased by a predetermined amount ΔKAL7, and finally becomes 0 (corresponding to flat land).

In addition, in this embodiment, the KMA of two areas within a predetermined period
Although the learning correction coefficient K ALT is uniformly updated every time P is learned, it may be updated every time K MAP of three or more areas is learned.

Furthermore, it goes without saying that the present invention can also be applied to a device that detects the intake air flow rate as a volumetric flow rate.

<Effects of the Invention> As explained above, according to the present invention, it is possible to quickly learn the change in air density, and the learning control of the air-fuel ratio can be performed well even during a sudden pitching, and the learning control can be performed not only during pitching but also during subsequent driving. This has the effect of preventing defects.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a system diagram showing an embodiment of the invention, Figs. 3 to 7 are flowcharts showing the contents of calculation processing, and Fig. 8 is feedback correction. FIG. 3 is a diagram showing how coefficients change. ■... Engine 5... Throttle valve 6... Fuel injection valve 14... Control unit 15
...Throttle sensor 17...Crank angle sensor 20...0□ sensor

Claims (1)

[Scope of Claims] Engine operating state detection means for detecting an engine operating state including at least parameters related to the amount of air taken into the engine; an air-fuel ratio detection means for detecting; a basic fuel injection amount setting means for setting a basic fuel injection amount based on the parameter detected by the engine operating state detection means; and a basic fuel injection amount setting means for setting the basic fuel injection amount for all areas of the engine operating state. a rewritable uniform learning correction coefficient storage means that stores a uniform learning correction coefficient for uniformly correcting the amount of fuel; and a learning correction coefficient for each area for correcting the basic fuel injection amount for each area of the engine operating state. a rewritable area-specific learning correction coefficient storage means; and an area-specific learning correction coefficient for searching the area-specific learning correction coefficient of the area of the corresponding engine operating state from the area-specific learning correction coefficient storage means based on the actual engine operating state. a search means; and a predetermined feedback correction coefficient for comparing the air-fuel ratio detected by the air-fuel ratio detection means with a target air-fuel ratio and correcting the basic fuel injection amount so as to bring the actual air-fuel ratio closer to the target air-fuel ratio. the basic fuel injection amount set by the basic fuel injection amount setting means, the uniform learning correction coefficient stored in the uniform learning correction coefficient storage means, and the area-specific learning. a fuel injection amount calculation means for calculating a fuel injection amount based on the area-specific learning correction coefficient searched by the correction coefficient search means and the feedback correction coefficient set by the feedback correction coefficient setting means; a fuel injection means for injecting fuel into the engine on and off in response to a drive pulse signal corresponding to the fuel injection amount; area-specific learning correction coefficient correction means for correcting and rewriting the area-specific learning correction coefficient in the area-specific learning correction coefficient storage means in a direction of decreasing the area-specific learning correction coefficient; update amount average value calculation means for calculating an average value of the update amount of the area-specific learning correction coefficient for each area when the area-specific learning correction coefficient is updated; Uniform learning correction coefficient correction means for correcting and rewriting the uniform learning correction coefficient of the uniform learning correction coefficient storage means by adding the average value or its correction value by the calculation means; and the basis of calculation of the update amount average value calculation means. a second area where the area-specific learning correction coefficient in the area-specific learning correction coefficient storage means is corrected and rewritten by subtracting the average value or its correction value by the update amount average value calculating means from the area-specific learning correction coefficient; A learning control device for an air-fuel ratio of an internal combustion engine, comprising: a separate learning correction coefficient correcting means;