JPS63295834A - Study control device for air-fuel ratio in internal combustion engine - Google Patents

Abstract

PURPOSE:To substantially improve drivability and emission, by providing a uniform study correction coefficient memory means which stores a uniform study correction coefficient for uniformly correcting a basic fuel injection amount for the total area in the operative condition of an engine. CONSTITUTION:An engine operative condition detecting means A detects an engine operative condition containing parameters relating to an amount of air sucked to an engine. A uniform study correction coefficient memory means D stores a uniform study correction coefficient for uniformly correcting a basic fuel injection amount for the total area in the engine operative condition. In this way, the engine, studying a change of density of air uniformly preferentially in a Q flat region, enables a good study control of air-fuel ratio to be performed for the change of density of air. Accordingly, drivability and emission can be substantially improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an air-fuel ratio learning control device for an automobile internal combustion engine having an electronically controlled fuel injection device with an air-fuel ratio feedback control function, and in particular, The present invention relates to an air-fuel ratio learning control device that can respond well to density changes.

<Prior art> Conventionally, in an internal combustion engine having an electronically controlled fuel injection device having 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 O2 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. A learning correction coefficient is determined by learning the deviation from the area for each predetermined engine operating state area, and when calculating the fuel injection amount, the basic fuel injection amount is corrected by the area-specific learning correction coefficient, and then corrected by the feedback correction coefficient. The air-fuel ratio obtained from the fuel injection amount calculated without any control 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. be.

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 feedback 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 amount Tp from the throttle valve opening α and the engine speed N (for example, the intake air flow tQ is determined from α and N by referring to a map, and Tp- is changed to -Q/
A system that calculates Tp from the formula N (K is a constant),
Alternatively, an air flow meter is provided to detect the intake air flow IQ, and from this and the engine speed N, the basic fuel injection fiT
In systems that calculate p=K・Q/N and use a flap type (volume flow detection type) air flow meter, changes in air density are not reflected in the calculation of the basic fuel injection amount, but the above Learning control can respond to changes in air density due to altitude or intake air temperature, as long as learning progresses smoothly.

<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. The area for learning is not determined, 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 feedback control is delayed, and when the air-fuel ratio feedback control is stopped, the base air-fuel ratio deviates greatly from the target air-fuel ratio, resulting in an overrich condition. ,
There have been problems in that it causes poor drivability, engine stalling, and poor restartability.

This requires learning and correcting changes in air density from the deviation from the reference value of the feedback correction coefficient during air-fuel ratio feedback control, but some of the learned deviations include parts such as fuel injection valves and throttle bodies. It also includes deviations in the base air-fuel ratio that depend on engine operating conditions due to variations, etc., so it is impossible to separate it from air density changes, and it is originally -
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

Also, the premise of learning is that air-fuel ratio feedback control is being performed, but conventionally, air-fuel ratio feedback control is generally based on air-fuel ratio feedback control. This is done only in the low rotation and low load area (including the medium rotation and medium load area) set as the ill 61 area.

This is because if feedback control is performed to the stoichiometric air-fuel ratio, which is the target air-fuel ratio, in a high rotation or high load region, there is a risk of engine seizure or catalyst burnout due to a rise in exhaust temperature, and in this region, the feedback correction coefficient This is to prevent engine seizure by clamping the engine and obtaining a rich output air-fuel ratio.

Therefore, when climbing from a lowland to a highland (mountain), the driver is mainly operating in a high load range, so there is almost no air-fuel ratio feedback control, and especially when climbing suddenly with an automatic transmission vehicle, the pedal is pressed firmly and the pedal is pressed firmly. In such cases, air-fuel ratio feedback control is stopped for a long time and no learning is performed at all. This is also one of the reasons why changes in air density cannot be learned quickly.

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 uses a uniform learning correction coefficient mainly for altitude correction and for uniformly learning air density changes, and parts. This is divided into area-specific learning correction coefficients for learning variations, etc. for each area, and the condition that allows learning only the air density changes. In the region where the intake air flow rate hardly changes with respect to the throttle valve opening change at each engine speed, the air density change is uniformly learned and the learning correction coefficient is uniformly rewritten, and in other regions, the parts The configuration is such that the variation is learned for each area and the area-based learning correction coefficient is rewritten.

In addition, since mountain climbing is mainly performed in the non-air-fuel ratio feedback control area, which is a high-speed, high-load area, if the area is continuously in the non-air-fuel ratio feedback control area, it is considered to be a sudden climb with steady pedaling. , the learning correction coefficient is uniformly corrected by a predetermined value every predetermined time.

Therefore, the air-fuel ratio learning control device according to the present invention is configured to include the following means A to 0, as shown in FIG.

(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) Air-fuel ratio feedback control J that determines the engine operating state, detects the air-fuel ratio feedback control region that is the low rotation and low load region, and outputs the air-fuel ratio feedback control command.
89M region detection means (H) While outputting the air-fuel ratio feedback control command, compares the air-fuel ratio detected by the air-fuel ratio detection means with the target air-fuel ratio, and detects the basic air-fuel ratio so as to bring the actual air-fuel ratio closer to the target air-fuel ratio. Feedback correction coefficient setting means for increasing or decreasing a feedback correction coefficient by a predetermined amount for correcting the fuel injection amount (1) A basic fuel injection amount set by the basic fuel injection amount setting means and the uniform learning correction coefficient storage means The fuel injection amount is calculated based on the uniform learning correction coefficient stored in the area, the area-specific learning correction coefficient searched by the area-specific learning correction coefficient search means, and the feedback correction coefficient set by the feedback correction coefficient setting means. Injection amount calculation means (J) Fuel injection means for injecting and supplying fuel to 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 (K) Throttle valve at each engine speed uniform learning range detection means (L) for detecting a predetermined region in which a change in intake air flow rate is equal to or less than a predetermined ratio with respect to a change in the opening of the uniform learning region detecting means (L). When a predetermined z region is detected, the uniform learning correction coefficient of the uniform learning correction coefficient storage means is corrected and rewritten in the direction of learning the deviation of the feedback correction coefficient from the reference value and decreasing this. Uniform learning correction coefficient correction means (M) during output of the air-fuel ratio feedback control command, when the uniform learning area detection means does not detect that the predetermined area is within the predetermined area, the feedback correction coefficient is adjusted for each area of the engine operating state. area-specific learning correction coefficient correction means (N) for correcting and rewriting the area-specific learning correction coefficient in the area-specific learning correction coefficient storage means in a direction to learn and reduce the deviation from the reference value; non-air-fuel ratio feedback control region timing means (0) for measuring a continuous period of time in a non-air-fuel ratio feedback control region, which is a high rotation and high load region; A second uniform learning correction coefficient correcting means for modifying the uniform learning correction coefficient of the uniform learning correction coefficient storage means by a predetermined value for each time. The injection amount is set based on a parameter related to the amount of air taken into the engine, and the area-based learning correction coefficient retrieval means F retrieves the area corresponding to the actual engine operating state from the area-based learning correction coefficient storage means E. The feedback correction coefficient setting means H searches for area-specific learning correction coefficients, and compares the actual air-fuel ratio with the target air-fuel ratio while the air-fuel ratio feedback control area detection means G is outputting the air-fuel ratio feedback control command. The feedback correction coefficient is set by increasing or decreasing a predetermined amount based on, for example, proportional/integral control so that the fuel ratio approaches the target air-fuel ratio. The fuel injection amount calculation means I corrects the basic fuel injection amount using the uniform learning correction coefficient stored in the uniform learning correction coefficient storage means, also corrects it using the area-specific learning correction coefficient, and further corrects it using the feedback correction coefficient. By making the correction, the fuel injection amount is calculated. Then, the fuel injection means J is actuated by a drive pulse signal corresponding to this fuel injection amount.

On the other hand, during the output of the air-fuel ratio feedback control command by the air-fuel ratio feed pack control region detecting means G, the uniform learning region detecting means detects that the intake air flow rate almost changes with respect to the throttle valve opening change at each engine speed. It is detected whether or not it is in a predetermined region where it disappears, and if it is in the predetermined region, the uniform learning correction coefficient correction means learns the deviation of the feedback correction coefficient from the reference value and works in the direction of decreasing this. The uniform learning correction coefficient is corrected and the data in the uniform learning correction coefficient storage means is rewritten. In this way, the conditions under which only changes in air density can be learned, that is, variations in the system due to changes in throttle valve opening.

The intake air flow rate remains almost unchanged with respect to the throttle valve opening at each engine speed, which is the region where the
The air density change is prioritized and learned uniformly in the area where the air density changes. It should be noted that this region is not without component variations, but this is a high opening range of the throttle valve, and compared to a low opening range, the main component variation is the fuel injector pulse width - injection flow rate. Variations in characteristics and intake air amount characteristics with respect to throttle valve opening are extremely small, and it is possible to learn by influencing air density.

If the area is outside the predetermined area, the area-based learning correction coefficient correction means M learns the deviation of the feedback correction coefficient from the reference value for each area of the engine operating state, and adjusts the area of the engine operating state in a direction to reduce this deviation. The area-by-area learning correction coefficient corresponding to the area-by-area learning correction coefficient is corrected and the data in the area-by-area learning correction coefficient storage means E is rewritten. In this way, parts variations and the like are learned for each area.

Also, if the air-fuel ratio feedback control area is continuously in the non-air-fuel ratio feedback control area, which is a high-speed, high-load area, air-fuel ratio feedback control is not performed and learning is not performed. The ill SI area timing means N measures the time, and if this state continues, it is determined that the pitch is a solid pitch, and the second uniform learning correction coefficient storage means O stores the uniform learning correction coefficient storage means at predetermined intervals. The uniform learning correction coefficient is corrected by a predetermined value and estimated learning is performed.In addition, it becomes possible to reliably learn the amount of air density change.

(Example> An embodiment of the present invention will be described 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. The fuel injection valve 6 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped.
The valve is opened by being energized by a drive pulse signal from a control unit 14, which will be described later, and fuel is injected and supplied under pressure from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator. Although this example is a single-point injection system, it may be a multi-point injection system in which a fuel injection valve is provided for each cylinder in a branch of an 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 the control unit 4, thereby igniting a spark to ignite and burn the air-fuel mixture.

From engine l, 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 including RAM, an A/D converter, and an input/output ink face, it receives input signals from various sensors, performs arithmetic processing as described below,
Controls the operation of the fuel injection valve 6 and ignition coil 8.

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 18 degrees of crank angle (in 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, the exhaust manifold 10 is provided with an Ot sensor 2o. This 0□ sensor 2o 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 14 via an engine key switch 22 as its operating power source and for detecting power supply voltage.

Furthermore, 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 CPU of the microcomputer built in the control unit 14 executes programs (fuel injection amount calculation routine, feedback control zone determination routine, proportional/integral control routine, learning routine, K
Arithmetic processing is performed according to the AL learning subroutine, the 4AP learning subroutine, and the KALT automatic correction routine to control fuel injection.

The basic fuel injection amount setting means, the area-based learning correction coefficient search means, the air-fuel ratio feedback control region detection means, the feedback correction coefficient setting means, the fuel injection amount calculation means, the uniform learning region detection means, the uniform learning correction coefficient correction means, Area-specific learning correction coefficient correction means, non-air fuel ratio feedback system? The function of the second uniform learning correction coefficient correcting means for the Ill JII area clock timer 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 9.

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 itQ corresponding to the throttle valve opening α and the engine speed N is determined in advance through experiments, etc., and is referred to a stored map in the ROM to search for Q corresponding to the actual α and N. and load it.

In step 3, -Q/N (K is a constant) is calculated from the intake air flow ff1Q and the engine speed N to the basic fuel injection amount Tp=corresponding to the amount of intake air per unit rotation. Here, steps 1 to 3 correspond to basic fuel injection amount setting means.

In step 4, the change rate of the throttle valve opening α detected based on the signal from the throttle sensor 15 or the acceleration correction coefficient due to switching from ON to OFF of the idle switch 16 is detected based on the signal from the water temperature sensor 18. Water temperature correction coefficient 9m according to the engine cooling water temperature TW
Various correction coefficients C0EF including a mixture ratio correction coefficient and the like are set according to the engine speed N and the basic fuel injection amount (load) Tp.

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 KAL4 is stored as an initial value O at the time when learning has not started, and this is read.

In step 6, a map is created on the RAM as an area learning correction coefficient storage means in which area learning correction coefficients K14Ap are stored corresponding to the engine speed N representing the engine operating state and the basic fuel injection amount (load) Tp. with reference to the actual N
, Tp, which searches for and reads the K MAP corresponds to the area-by-area learning correction coefficient retrieval means. In addition, the map of □- in the area-based learning correction coefficient divides the areas of the engine operating state into a grid of about 8 x 8, with the horizontal axis of the engine rotation speed N and the vertical axis of the basic fuel injection ITp, and calculates the area for each area. Area-based learning correction coefficients KMAP are stored, and when learning has not started, all initial values 0 are stored.

In step 7, the feedback correction coefficient L is set by the proportional/integral control routine shown in FIG. 5, which will be described later.
AMBDA is read. Note that the reference value of this feedback correction coefficient LANBDA is 1.

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 flow rate 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 −COEF ・(LAMBDA+
Katt+KMAP)+TsIn step 10, the calculated Ti is set in the output register. This allows predetermined engine rotation synchronization (for example, every 2 rotations)
At the fuel injection timing, a drive pulse signal having a pulse width of Ts is applied to the fuel injection valve 6, and fuel injection is performed.

Fig. 4 shows a feedback control zone determination routine. In principle, air-fuel ratio feedback control is performed in the case of the air-fuel ratio feedback # column region of low rotation and low load, which is indicated by hatching in Fig. 10, and This is to stop air-fuel ratio feedback control in the case of Therefore, is this routine based on air-fuel ratio feedback? 11
1? This corresponds to the il area comparison detection means.

In step 21, a comparison Tp is searched from the engine speed N,
In step 22, the actual basic fuel injection amount Tp (actual Tp)
Compare and compare 'rp.

If actual Tp≦comparison Tp, that is, if the rotation is low and the load is low, proceed to step 23 to reset the delay timer (counted up by a clock signal), and then proceed to step 26 to set the λcont flag to 1. set. This is to perform air-fuel ratio feedback control when the engine speed is low and the load is low.

In the case of actual Tp> comparison Tp, that is, in the case of high rotation or high load, in principle, proceed to step 27 and set λcont
Set the flag to O. This is to stop the air-fuel ratio feedback control, separately obtain a rich output air-fuel ratio, suppress a rise in exhaust temperature, and prevent engine 1 seizure and catalyst 12 burnout.

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, a predetermined time (for example, 10 seconds) has elapsed. Until then, proceed to step 26 and λc
The ont flag continues to be set to 1 to continue air-fuel ratio feedback control.

This is to increase the opportunity to learn about the uniform learning correction coefficient KAL since mountain climbing is performed in a high load area.

However, in the judgment at step 25, whether the engine speed is N or the specified value (
For example, if the engine speed exceeds 3,800 rpm, or if this condition continues for a predetermined period of time, air-fuel ratio feedback control is stopped for safety reasons.

FIG. 5 shows a proportional/integral control routine, which is executed every predetermined time (for example, 10 m5), thereby setting the feedback correction coefficient LAMBDA. Therefore, this routine corresponds to feedback correction coefficient setting means.

In step 31, the value of the λcont flag is determined, and if it is 0, this routine is ended. In this case, the feedback correction coefficient LAMBDA is the previous value (or reference value 1)
is clamped, and air-fuel ratio feedback control is stopped.

If the λcont flag is 1, proceed to step 32 and set it to 0! Output voltage V of sensor 20. 2, and in the next step 33, the slice level voltage V r corresponding to the stoichiometric air-fuel ratio is read.
*F is compared to determine whether the air-fuel ratio is rich or lean.

'When the air-fuel ratio is lean (V ox < V-t), the process proceeds from step 33 to step 34 to determine whether or not it is the time of reversal from rich to lean (immediately after the reversal), and when the ratio is reversed, step 35 is performed. Then, the feedback correction coefficient LAMBDA is increased by a predetermined proportionality constant of 2 compared to the previous value. Otherwise, the process proceeds to step 36 and the feedback correction coefficient LA? '1BDA is increased by a predetermined integral constant of 1 minute with respect to the previous value, and thus the feedback correction coefficient L
Increase AMBDA with a constant slope. Note that P>>I.

When the air-fuel ratio is rich (Voz>V-t), the process proceeds from step 33 to step 37, where it is determined whether or not it is the time of reversal from lean to rich (immediately after the reversal), and when the air-fuel ratio is reversed, the process proceeds to step 38. 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 and the feedback correction coefficient LA? IBDA is decreased by a predetermined integral constant of 1 minute with respect to the previous value, and thus the feedback correction coefficient LAMBDA
decrease with a constant slope.

FIG. 6 shows a learning routine, FIG. 7 shows a KAL learning subroutine, and FIG. 8 shows a KMAP learning subroutine.

In step 41 of FIG. 6, the value of the λcont flag is determined, and if it is 0, the process proceeds to step 42 and the count value CA
After clearing LT and CMAp, this routine ends. This is because learning cannot be performed when air-fuel ratio feedback control is stopped.

When the λcon t flag is 1, that is, during air-fuel ratio feedback control, the process advances to step 43 and subsequent steps to perform learning for the uniform learning correction coefficient correction means (hereinafter referred to as KALT learning) and learning for the area-specific learning correction coefficient KHAP. , lA, learning).

In other words, the KAL learning is performed in a predetermined high load region (hereinafter referred to as "intake air flow -ffiQ") in which the intake air flow -ffiQ hardly changes with respect to the change in the throttle valve opening α at each engine speed N, as shown with hunting in Fig. 11. Since the K MAP learning is performed in other areas, in step 43, a comparison α is searched from the engine speed N, and in step 44, the actual throttle valve opening α (actual α )
and comparison α1. The steps 43 and 44 correspond to uniform learning area detection means.

As a result of the comparison, if actual α≧comparison α (Q flat region), the process proceeds to steps 48 and 49, and after clearing the count value CMAP, the Katt learning subroutine shown in FIG. 7 is executed.

However, in the case of a single point injection system, in the region where the throttle valve opening is extremely large, the intake flow velocity becomes slow and the distribution to each cylinder deteriorates, so the region of poor distribution is assigned by the throttle valve opening relative to the engine speed. KAL7 learning is prohibited at throttle valve openings greater than that. Therefore, in step 45, a comparison α2 is searched from the engine speed N, and in a step 46, the actual α and the comparison α2 are compared, and if the actual α>comparison α2, the step 50.
1, and after clearing the count value CALT, the 8th
Move to the K MAP learning subroutine shown in the figure.

In addition, in the case of a single point injection system, the distance from the fuel injector 6 to the combustion chamber of the engine 1 is long, and accurate K Att learning cannot be performed due to the influence of wall flow fuel during acceleration. waits for a predetermined time, that is, until the wall flow becomes steady, and then performs KAL learning. Therefore, in step 47, it is determined whether or not a predetermined acceleration time has elapsed. If the predetermined time has not elapsed, the process proceeds to step 50.51, and after clearing the count value CALT,
Move to the MAP learning subroutine.

If the determination at step 44 is that actual α<comparison α1, the process proceeds to step 50.51, and after clearing the count value CALT, the process proceeds to the OKMAP learning subroutine shown in FIG.

Next, the KALT learning subroutine shown in FIG. 7 will be explained. This KALT learning subroutine corresponds to uniform learning correction coefficient correction means.

In step 61, it is determined whether the output of the 0□ sensor 20 has been reversed, that is, the direction of increase or decrease of the feedback correction coefficient LAMBDA has been reversed, and when this subroutine is repeated to reverse the output, a count value C representing the number of times of reversal is determined in step 62.
When AL is increased by 1 and CALT=3, for example, the process proceeds from step 63 to step 64, where the deviation (LAMBDA-1) of the current feedback correction coefficient LAMBDA from the reference value 1 is temporarily stored as ΔLAMBDA 1. , start learning.

When CALT=4 or more, the process proceeds from step 63 to step 65, where the deviation of the feedback correction coefficient LAMBDA from the reference value 1 (LAMBDA-
1) is temporarily stored as ΔLAMBDA2. ΔLAMBDA l and ΔLAMBDA stored at this time
, are 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, as shown in FIG.

In this way, the upper and lower peak values ΔLAMBDA of the deviation from the reference value 1 of the feedback correction coefficient LAMBDA are calculated.
l.

Once ΔLAMBDA 2 is determined, the process proceeds to step 66, where their average value τff1 (see the following equation) is determined.

ΔLAMBDA= (ΔLAMBDA, +ΔLAMB
DAz)/Secondly, the process proceeds to step 67 to read out the current uniform learning correction coefficient K Att (initial value O) stored at a predetermined address in the RAM.

Next, the process proceeds to step 68, where a predetermined proportion of the average value ΔLAMBDA of the deviation from the feedback correction coefficient from the reference value of the feedback correction coefficient is added to the current uniform learning correction coefficient KALT according to the following formula, thereby setting LA to the new uniform learning correction coefficient. The data of the uniform learning correction coefficient at a predetermined address in the RAM is corrected and rewritten.

KAL? ←KAL7+MAL?・τyu punishment■ (MA
L? is the addition rate constant, O < M att < 1)
After this, in step 69, ΔLAMBO is used for the next learning.
Assign At to ΔLAMBDAI.

Then, in step 70, KAL? Increase the learning counter by 1. This KALT learning counter is set to O by the initialization routine executed when the engine key switch 22 (or start switch) is turned on, and is the number of times KAL learning has been performed since the engine key switch 22 is turned on. is being counted.

Next, the OKMAP learning subroutine shown in FIG. 8 will be explained. This K MAP learning subroutine corresponds to area-specific learning correction coefficient correction means.

In step 81, it is determined whether or not the engine speed N representing the engine operating state and the basic fuel injection tTp 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 CHAP is cleared. After that, this subroutine ends.

If the area is the same as the previous time, the output of the 02 sensor 20 is reversed in step 83, that is, the feedback correction coefficient LA
It is determined whether the direction of increase/decrease in MBDA has been reversed, and each time this subroutine is repeated and reversed, a count (IIcMAP) representing the number of reversals is incremented by 1 in step 84.
For example, when CMAP=3, the process proceeds from step 85 to step 86 and the current feedback correction coefficient L is
Deviation of AMBDA from reference value l (LAMBDA-1)
is temporarily stored as ΔLAMBD^1 and learning is started.

When C5Ap=4 or more, the process proceeds from step 85 to step 87, where the deviation (LAMBDA) of the feedback correction coefficient LAMBDA from the reference value l at that time is
-1) is temporarily stored as ΔLAMBDA.

In this way, the upper and lower peak values ΔLAMBD^ of the deviation of the feedback correction coefficient LAMBDA from the reference value 1,
.

ΔLAMBDA! Once determined, the process proceeds to step 88 and their average value -ffiη is determined.

Next, the process proceeds to step 89, where the learning value for each area stored in the MA knob on the RAM corresponding to the current area is compared with a predetermined value. (Weighting is a constant) MWAP is set to a relatively small value M0 including 0. If the value is greater than or equal to the predetermined value, the addition ratio constant (weighting is a constant) MMAP is set to a relatively large value M (where Ml <<Matt) in step 92.

Next, the process proceeds to step 93, and a new area-specific learning correction is performed by adding a predetermined percentage of the average value m of the deviation of the feed pack correction coefficient from the reference value to the current area-specific learning correction coefficient K, 4A, according to the following formula. The coefficient KMAP is calculated, and the area-specific learning correction coefficient data for the same area of the map on the RAM is corrected and rewritten.

KMAP ←Ktap +Mssp ・ΔLAMB
DA After this, in step 94, ΔLAM is set for the next learning.
Substitute BOat into ΔLAMBDA I .

Regarding the above-mentioned addition ratio constant (weighting is a constant), Mat
The reason for setting t >> MNAF is to proceed with learning related to changes in air density first, and then perform 4□ learning for each area. In addition, the engine key switch 22
The value of M M A p is changed according to the number of KALT learning after turning on the start switch (or the start switch).
This is to suppress the progress of KMAP learning until a learning is experienced, and in extreme cases, set KMAP = 0 and prohibit learning.

FIG. 9 shows a KALT automatic correction routine, which corresponds to the non-air-fuel ratio feedback control area timing means and the second uniform learning correction coefficient correction means.

In step 101, the value of the λcant flag is determined.

When the λcon t flag is 1, that is, during air-fuel ratio feedback control, the process advances to step 102 and the timer value T is
Set IM to 0 and end this routine.

When the λcont flag is O, that is, when the air-fuel ratio feedback control is stopped due to high rotation or high load, the process proceeds to step 3 and the timer value TIM is counted up.

Therefore, steps 101 to 103 correspond to the non-air-fuel ratio feedback control area timing means.

After counting up the timer value TIM, step 1
04, it is determined whether the timer value TIM is greater than or equal to a predetermined value. If the value is less than the predetermined value, this routine ends.

When the timer value TIM exceeds a predetermined value, the process proceeds from step 104 to step 105, and a new uniform learning correction coefficient KALT is set by subtracting the predetermined value β from the current uniform learning correction coefficient KALT according to the following formula. R
Correct and rewrite the uniform learning correction coefficient data at a predetermined address of AM.

KAL? '-KAL-β After this, proceed to step 106 and set the timer value TIM to 0.
and exit this routine.

Therefore, steps 104 and 105 correspond to the second uniform learning correction coefficient modification means.

In this way, if the operation continues in the high rotation or high load region and the air-fuel ratio feedback control continues to stop, it is determined that the pedal is stuck uphill, and the learning correction coefficient correction means is uniformly adjusted by a predetermined value at predetermined intervals. By decreasing the amount, even when stepping uphill in an automatic transmission vehicle, etc., the change in air density can be reliably estimated and learned, and deterioration of drivability and emissions can be prevented.

<Effects of the Invention> As explained above, according to the present invention, since the air density changes are learned with uniform priority in the Q-flat eTJ region, it is possible to learn the air density changes at high speed, and it is possible to learn the air density changes at high speed, such as when driving up a mountain. Even in this case, it is possible to perform good learning control of the air-fuel ratio against changes in air density. Also, even if you step on the pitch in an auto transmission car, etc.,
By detecting this, it is possible to estimate and learn the amount of change in air density, which allows for better response to changes in air density, resulting in significant improvements in drivability, emissions, etc. .

[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 9 are flow charts showing the calculation processing contents, and Fig. 10 is the air-fuel ratio FIG. 11 is a diagram showing the learning area for the uniform learning correction coefficient, and FIG. 12 is a diagram showing how the feedback correction coefficient changes. 1... Engine 5... Throttle valve 6... Fuel injection 'R valve 14... Control unit 15.
...Throttle sensor 17...Crank angle sensor 20...O2 sensor Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio SasashimaFigure 4Figure 6 Machine/Sekiguchi transfer throttle/nottle valve opening degree α

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; an air-fuel ratio feedback control region detecting means for determining an engine operating state, detecting an air-fuel ratio feedback control region that is a low rotation and low load region, and outputting an air-fuel ratio feedback control command; and the air-fuel ratio feedback control command. During the output, a feedback correction coefficient is predetermined 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 an engine on and off in response to a drive pulse signal corresponding to a fuel injection amount; uniform learning region detection means for detecting a predetermined region in which the air-fuel ratio feedback control command is output; uniform learning correction coefficient correction means for correcting and rewriting the uniform learning correction coefficient of the uniform learning correction coefficient storage means in a direction to learn and reduce the deviation from the value; When the learning area detecting means does not uniformly detect that the predetermined area is within the predetermined area, the area-specific learning correction coefficient Area-specific learning correction coefficient correction means for correcting and rewriting area-specific learning correction coefficients in the storage means; a non-air-fuel ratio feedback control area timer that measures time; and a second unit that corrects the uniform learning correction coefficient of the uniform learning correction coefficient storage means by a predetermined value at predetermined time intervals during time measurement by the non-air-fuel ratio feedback control area timer. 1. A learning control device for an air-fuel ratio of an internal combustion engine, comprising: uniform learning correction coefficient correcting means;