JPH0243900B2 - NAINENKIKANNOGAKUSHUSEIGYOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a learning control device for a feedback control system for controlling the air-fuel ratio, idle speed, etc. of an internal combustion engine.

<Prior Art> Conventional learning control devices for internal combustion engines include, for example, an air-fuel ratio learning control device disclosed in Japanese Patent Application Laid-open No. 59-203828, and an air-fuel ratio learning control device disclosed in Japanese Patent Application Laid-Open No. 59-211738. There is a disclosed idle speed learning control device.

Here, a base air-fuel ratio learning control device will be described as an example in the case where the air-fuel ratio is feedback-controlled to the stoichiometric air-fuel ratio, which is a control target value, in an internal combustion engine having an electronically controlled fuel injection device.

A fuel injection valve used in an electronically controlled fuel injection system is opened by a drive pulse signal applied in synchronization with engine rotation, and during the valve opening period, fuel at a predetermined pressure is injected. . Therefore, the fuel injection amount is controlled by the pulse width of the drive pulse signal, and if this pulse width is set as Ti and the control signal corresponds to the fuel injection amount, then in order to obtain the stoichiometric air-fuel ratio, Ti is determined by the following equation. determined.

Ti=Tp・COEF・α+Ts However, Tp is the basic pulse width corresponding to the basic fuel injection amount, and is called the basic fuel injection amount for convenience. Tp＝
K・Q/N, where K is a constant, Q is the intake air flow rate, and N
is the engine speed. COEF is various correction coefficients such as water temperature correction. α is an air-fuel ratio feedback correction coefficient for air-fuel ratio feedback control (λ control) to be described later. Ts is a voltage correction amount, which is used to correct changes in the injection flow rate of the fuel injector due to changes in battery voltage.

Regarding λ control, an O ₂ sensor is installed in the exhaust system to detect the actual air-fuel ratio, and whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio is controlled by the slice level. A correction coefficient α is determined and the stoichiometric air-fuel ratio is maintained by varying this α.

Here, the value of the air-fuel ratio feedback correction coefficient α is changed by proportional-integral (PI) control to ensure stable control.

In other words, the output voltage of the O ₂ sensor is compared with the slice level voltage, and if it is higher or lower than the slice level, the air-fuel ratio is rich (lean) without suddenly enriching or thinning the air-fuel ratio. ), the air-fuel ratio is first lowered (raised) by P, and then gradually lowered (raised) minute by minute to make the air-fuel ratio leaner (richer).

However, under conditions where λ control is not performed, α
is clamped, and the desired air-fuel ratio is obtained by setting various correction coefficients COEF.

By the way, if the base air-fuel ratio under λ control conditions, that is, the air-fuel ratio when α = 1, could be set to the stoichiometric air-fuel ratio (λ = 1), feedback control would not be necessary. Due to factors such as variations in air flow meters, fuel injection valves, pressure regulators, and control units (for example, air flow meters, fuel injection valves, pressure regulators, and control units), changes over time, nonlinearity of the pulse width-flow rate characteristics of fuel injection valves, and changes in operating conditions and environment, Since the base air-fuel ratio deviates from λ=1, feedback control is performed.

However, if the base air-fuel ratio deviates from λ=1, it takes time to stabilize the step in the base air-fuel ratio to λ=1 through feedback control when the operating range changes significantly. For this purpose, the proportionality and integral constants (P/I) are increased, which causes overshoot and undershoot, resulting in poor controllability. In other words, if the base air-fuel ratio deviates from λ=1, the air-fuel ratio will be controlled within a range that deviates considerably from the stoichiometric air-fuel ratio.

As a result, the three-way catalyst is operated at a point where the conversion efficiency is poor, and not only does the cost increase due to an increase in the amount of precious metal in the catalyst, but the conversion efficiency further deteriorates as the catalyst deteriorates, making it necessary to replace the catalyst.

Therefore, by setting the base air-fuel ratio to λ = 1 through learning, it is possible to eliminate the deviation from λ = 1 caused by the step in the base air-fuel ratio during the transition period, and to reduce the P/I component, improving controllability. An air-fuel ratio learning control device that aims to improve the
It was filed as Japanese Patent Application No. 58-76221 (Japanese Unexamined Patent Publication No. 59-203828) or Japanese Patent Application No. 58-197499.

This is because if the base air-fuel ratio deviates from the stoichiometric air-fuel ratio during air-fuel ratio feedback control, the air-fuel ratio feedback correction coefficient α increases to fill the gap. is detected, and the learning correction coefficient Kl based on the α
is determined and memorized, and when the same operating condition returns, the base air-fuel ratio is corrected using the stored learning correction coefficient Kl so as to have good responsiveness to the stoichiometric air-fuel ratio. Here, the learning correction coefficient Kl is stored for each region of a predetermined range obtained by dividing the RAM map into a grid according to appropriate parameters of the engine operating state such as engine speed and load.

Specifically, a map of the learning correction coefficient Kl corresponding to engine operating conditions such as engine speed and load is provided in RAM, and when calculating the fuel injection amount Ti, the basic fuel injection amount Tp is calculated as shown in the following formula. Correct using learning correction coefficient Kl.

Ti=Tp・COEF・Kl・α＋Ts Then, learn Kl by following the steps below.

In the steady state, the region of the engine operating state at that time is detected, and the deviation Δα from the reference value of α is detected as an average value. The standard value is λ=
The value corresponding to 1 is generally set to 1.0.

The Kl that has been learned up to now corresponding to the region of the engine operating state is searched.

The value of Kl+Δα/M is determined from Kl and Δα, and the memory is updated using the result (learning value) as a new Kl _(oew) . M is a constant.

In addition, the idle speed learning control device is used when an idle control valve is provided in the auxiliary air passage that bypasses the throttle valve, and the idle speed is controlled by adjusting the opening degree of this idle control valve. When performing feedback correction on the basic opening degree of the idle control valve corresponding to the target idle speed for each temperature by comparing the target idle speed and the actual idle speed, it is adjusted according to the cooling water temperature, which is a parameter of the engine operating state. A map of learning correction amount is provided,
The deviation of the feedback correction amount from the reference value is learned and the learning correction amount is corrected, and the basic opening degree is corrected using this learning correction amount, thereby stabilizing the control.

<Problems to be Solved by the Invention> By the way, in this learning control method, writing and reference to the map that stores the learning correction amount is performed without interpolation calculation (interpolation slows down the learning progress speed). .

However, in this way, the driving area where the learning progress is high (hereinafter referred to as the learning area)
In the driving state near the boundary between the learning correction amount and the area where the learning progress is low (hereinafter referred to as the unlearning area), the difference in learning correction amount between the two areas is large, so the control amount fluctuates and becomes stable. There was a problem that control performance could not be obtained.

In view of this, the applicant of the present application has further developed a system in which, when searching for the learning correction amount, the determination of the searched driving condition has hysteresis in the direction in which the driving condition changes. According to this application, fluctuations in the control state near the boundaries of each area can be prevented.

However, in this case, as shown in FIG. ,Nya
Since the operating region is determined with hysteresis only in the direction in which Tp increases, in the long term, the learning correction amount of the operating signal determined to be the center of the operating region where learning is performed is used. A deviation occurs in one direction between the center of the area to be corrected and
A problem arises in that the original function of learning control is impaired.

The present invention was made in view of the above-mentioned circumstances, and
It is an object of the present invention to prevent fluctuations in the learning state near the boundaries of each area where learning correction amounts are stored while maintaining a good learning control function.

<Means for solving the problem> For this reason, the present invention, when searching for a learning correction amount, determines the searched driving state by determining the driving range in two contradictory directions in which the parameters of the driving state change. Added hysteresis in the direction of expansion.

Specifically, the learning control device according to the present invention has a first
As shown in the figure, the following means (A) to (I) are provided.

(A) Basic control amount setting means for setting basic control amounts corresponding to control target values of the internal combustion engine such as air-fuel ratio and idle speed (B) Grid that divides the engine operating state into multiple regions according to the parameters. A rewritable storage means (C) that stores the axes and learning correction amounts for correcting the basic control amount for each area surrounded by these grid axes. A learning correction amount search means (D) for searching for a learning correction amount in a region where the control target value and the actual value are compared, and determining a feedback correction amount for correcting the basic control amount so that the actual value approaches the control target value. Feedback correction amount setting means (E) that increases or decreases by a predetermined amount and sets the basic control amount set by the basic control amount setting means, the learning correction amount searched by the learning correction amount search means, and the feedback correction amount setting means Controlled amount calculating means (F) that calculates a controlled amount from the feedback correction amount that has been set; Control means (G) that operates according to the controlled amount and controls the air-fuel ratio, idle rotation speed, etc. From the reference value of the feedback correction amount. A learning correction amount correction means (H) that learns the average value of the deviation of and corrects and rewrites the learning correction amount corresponding to the range of engine operating conditions in the direction of decreasing this. Operating state change direction determining means (I) for determining the operating region in which the learning correction amount retrieved from the storage means by the learning correction amount retrieving means is determined for two contradictory directions in which the parameters of the engine operating state change. Operation area determination means (operation) in which the lattice axes that divide each operation area have hysteresis in the direction of expanding the operation area (operation) The basic control amount setting means A corresponds to control target values such as air-fuel ratio and idle rotation speed. The basic control amount to be controlled is set, for example, according to a predetermined calculation formula or by searching, and the learning correction amount retrieval means C searches the storage means B for the learning correction amount of the corresponding region based on the actual engine operating state, The feedback correction amount setting means D compares the control target value and the actual value, and sets the feedback correction amount by increasing or decreasing a predetermined amount based on, for example, proportional-integral control so that the actual value approaches the control target value. Then, the control amount calculation means E calculates the control amount by correcting the basic control amount with the learning correction amount and further correcting it with the feedback correction amount, and the control means F operates according to this control amount. The fuel injection amount or auxiliary air amount is controlled to control the air-fuel ratio, idle speed, etc.

Here, the storage means B stores the engine operating state in a plurality of areas partitioned by one or two parameters in a rewritable state with learning correction amounts. When searching for the learning correction amount, first, the operating state change direction determining means H determines the direction in which the parameter of the engine operating state changes, and then the operating region determining means determines the direction in which the parameter changes in the opposite direction. When the vehicle changes direction, the position of the lattice axis that divides the driving region in which the learning correction amount is stored is shifted in the direction in which the driving region expands to determine the driving region in which the search is performed, and based on the determination result. Search for learning correction amount.

This makes it possible to prevent hunting of the control amount due to differences in learning correction amounts retrieved from mutually adjacent operating regions when the operating state is near the grid axis. Since the center of the corrected operating region can be substantially coincident with the center, the learning control function can also be maintained satisfactorily.

<Embodiment> An embodiment in which the learning control device of the present invention is applied to an air-fuel ratio feedback control system of an internal combustion engine having an electronically controlled fuel injection device will be described below.

In FIG. 2, air is taken into the engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, and an intake manifold 5. As shown in FIG.

The intake duct 3 is provided with an air flow meter 6 as means for detecting the intake air flow rate Q, and outputs a voltage signal corresponding to the intake air flow rate Q signal. The throttle chamber 4 includes primary throttle valves 7 and 2 that are linked to an accelerator pedal (not shown).
A next throttle valve 8 is provided to control the intake air flow rate Q. Further, an auxiliary air passage 9 is provided that bypasses these throttle valves 7 and 8, and an idle control valve 10 is interposed in this auxiliary air passage 9. A fuel injection valve 11 is provided in the intake manifold 5 or the intake port of the engine 1 . The fuel injection valve 11 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped. Fuel that is pressure-fed and controlled to a predetermined pressure by a pressure regulator is injected and supplied to the engine 1. Therefore, the fuel injection valve 11 is a control means for controlling the fuel injection amount through its operation and controlling the air-fuel ratio to the optimum air-fuel ratio (stoichiometric air-fuel ratio) which is the control target value.

Exhaust gas is exhausted from the engine 1 via an exhaust manifold 12, an exhaust duct 13, a three-way catalyst 14, and a muffler 15.

The exhaust manifold 12 is provided with an O ₂ sensor 16 . This O ₂ sensor 16 outputs a voltage signal according to the ratio of the oxygen concentration in the atmosphere (constant) and the oxygen concentration in the exhaust gas, and the electromotive force changes suddenly when the air-fuel mixture is combusted at the stoichiometric air-fuel ratio. This is a known sensor. Therefore, the O ₂ sensor 16 is a means for detecting the air-fuel ratio (rich/lean) of the air-fuel mixture. The three-way catalyst 14 efficiently oxidizes or reduces CO, HC, and NOx in the exhaust gas near the stoichiometric air-fuel ratio of the air-fuel mixture.
It is a catalytic device that converts substances into other harmless substances.

In addition, a crank angle sensor 17 is provided. The crank angle sensor 17 is connected to the crank pulley 1
8 is provided with a signal disk plate 19,
For example, the teeth provided on the outer periphery of the plate 19
It outputs a reference signal every 120 degrees and a position signal every 1 degree. Here, the engine rotation speed N can be calculated by measuring the period of the reference signal. Therefore, the crank angle sensor 17 is a means for detecting not only the crank angle but also the engine speed N.

The air flow meter 6 and the crank angle sensor 1
7 and the O ₂ sensor 16 are both input to a control unit 30. Furthermore, the voltage of the battery 20 is directly applied to the control unit 30 as its operating power source and as the power supply voltage via the engine key switch 21. Furthermore, control unit 3
0 includes a water temperature sensor 22 that detects the engine cooling water temperature as necessary, a throttle sensor 23 including an idle switch that detects the throttle opening of the primary throttle valve 7, and a vehicle speed sensor 2 that detects the vehicle speed.
4. A signal from a neutral switch 25 or the like that detects the neutral position of the transmission is input. The control unit 30 performs arithmetic processing based on various input signals and outputs a drive pulse signal with an optimal pulse width to the fuel injection valve 11 to obtain the fuel injection amount for obtaining the optimal air-fuel ratio.

As shown in FIG. 3, the control unit 30 includes a CPU 31, a P-ROM 32, a CMOS-
It has a RAM 33 and an address decoder 34. Here, the RAM 33 is a rewritable storage means for learning control, and as the operating power source of this RAM 33, the battery 20 is used without going through the engine key switch 21 in order to retain the memory contents even after the engine key switch 21 is turned off. Connect via a suitable regulated power supply.

Among the input signals to the CPU 31, each voltage signal from the air flow meter 6, O ₂ sensor 16, battery 20, water temperature sensor 22, and throttle sensor 23 is an analog signal. The signal is input via a converter 36. The A/D converter 36 is connected to the address decoder 34 by the CPU 31.
and is controlled via the A/D conversion timing controller 37. The reference signal and position signal from the crank angle sensor 17 are inputted via a one-shot multi-circuit 38. The signal from the idle switch built in the throttle sensor 23 and the neutral switch 25
The signal from the digital input interface 39
The signal from the vehicle speed sensor 24 is input via a waveform shaping circuit 40.

An output signal from the CPU 31 (a driving pulse signal for the fuel injection valve 11) is sent to the fuel injection valve 11 via a current waveform control circuit 41.

Here, the CPU 31 performs input/output operations, arithmetic processing, etc. according to a program (stored in the ROM 32) based on the flowchart (fuel injection amount calculation routine and learning subroutine) shown in FIG. 4, and calculates the fuel injection amount. control.

Furthermore, basic control amount (basic fuel injection amount) setting means,
As a learning correction amount (coefficient) search means, a feedback correction amount (coefficient) setting means, a control amount (fuel injection amount) calculation means, a learning correction amount (coefficient) modification means, a driving state change direction determining means, and an operating region determining means. The functions are achieved by the program.

Next, the operation will be explained with reference to the flowchart shown in FIG.

In FIG. 4, in step 1 (referred to as S1 in the figure; the same applies hereinafter), the intake air flow rate Q obtained from the signal from the air flow meter 6 and the engine rotation speed N obtained from the signal from the crank angle sensor 17. Basic fuel injection amount Tp (=K・Q/N)
Calculate. This part corresponds to the basic control amount setting means.

In step 2, various correction coefficients COEF are set.

In step 3, as shown in FIG. 5, the lattice axis of the engine speed N, which is one parameter that partitions the operating range in which the learning correction coefficient Kl is stored, for example, the subscript number n of N ₁ to N ₈ , is changed to 2. After initial setting, the process proceeds to step 4, where the actual rotational speed N is compared with a value N _o -ΔN obtained by subtracting a predetermined value ΔN (for example, 50 rpm) from the rotational speed N _o of the grating shaft.

If N≧N _o −ΔN, proceed to step 5 and set the rotation speed N to a predetermined value _ΔN .
is compared with the sum of N _o +ΔN.

If it is determined in step 5 that N>N _o +ΔN, proceed to step 6 and increase the value of n by 1, then return to step 4 again and increase the rotational speed N _o corresponding to the value of n increased by 1. The value obtained by subtracting ΔN from the actual rotation speed N is compared.

With this operation, in the comparison in step 4, N>
When N _o −ΔN, proceed to step 7.
Flag F _o-1 in the area of N corresponding to N _o-1 <N≦N _o
is set to 1, and all flags F _o-1 corresponding to other areas are reset to 0.

Next, proceed to step 9 and set the learning correction coefficient Kl.
In the operating region to search for, search for the region of rotation speed N.
It is determined that N _o-1 <N≦N _o .

Also, when the comparison in step 5 shows that N≦N _o +ΔN, proceed to step 8 and find that N _o-1 <N≦N _o
It is determined whether the flag F _{o-1 corresponding} to NO.
If so, proceed to step 10 and check the area of rotation speed N.
It is determined that N _o <N≦N _o+1 .

The method for determining the N region shown above will be explained using FIG. 5. Each grid N _o (n=
For 2 to 8), a band-shaped judgment area is set between the value obtained by subtracting ΔN and the value added. Judgment is made in step 4 and step 5. Then, for example, as the current N area is hatched with diagonal lines in the figure, N ₂ +ΔN that deviates from the band-shaped area
If it is in the range <N ₃ -ΔN, proceed from step 4 to step 7 with n=3 and set flag F ₂
= 1, and in step 9 the N area is set to N ₂ <N≦N ₃
It is determined that the area is

Next, the rotation speed N decreases from this state, and N ₂ −
When you move to the band-shaped region of ΔN≦N≦N ₂ +ΔN,
With n=2, proceed from step 5 to step 8. Here, in the previous flow, F ₂ = 1, so in the judgment in step 8, F ₁ ≠ 1
Therefore, the answer is NO and the process proceeds to step 10, where it is determined that the area is N ₂ <N≦N ₃ as in the previous time.
Furthermore, when the rotational speed N decreases and becomes N<N ₂ -ΔN and leaves the band-shaped region, the process proceeds from step 4 to step 7 with n=2, and after setting F ₁ =1,
Proceeding to step 9, the N area is re-determined to satisfy N ₁ <N≦N ₂ .

That is, when the rotation speed N decreases, the lower limit rotation speed that determines the area where the learning correction coefficient is searched is on the smaller side of the rotation speed lattice axis that partitions the area where the learning correction coefficient to be searched is stored. from the value of ΔN
This is the value obtained by subtracting , and this provides hysteresis in the direction of expanding the area.

On the other hand, when the rotational speed N increases from the shaded area in Fig. 5 and moves to the band-shaped area where N ₃ -ΔN≦N≦N ₃ +ΔN, the process proceeds to step 8 with n=3, but according to the flow up to the previous time. Since F ₂ =1 is set in step 7, the determination here is YES, and the process proceeds to step 9, where it is determined that the N region satisfies N ₂ <N≦N ₃ .

Furthermore, when the rotational speed N increases and becomes N>N ₃ +ΔN, the process proceeds to step 4 after n=4 in step 6, and since N<N ₄ -ΔN, F ₃ is increased in step 7. = 1, the process proceeds to step 9 and the N area is determined again as N ₃ <N≦N ₄ .

That is, when the number of rotations N increases, the upper limit number of rotations for determining the search area is the value obtained by adding a predetermined value ΔN to the value on the larger side of the lattice axis of the storage area. Hysteresis in the direction of expanding the area is also provided when the area increases.

Here, in step 7, flag F _o-1 is set,
In addition, by the function of determining the flag F _o-1 in step 8, it is possible to determine whether the rotational speed N is increasing or decreasing. Therefore, the functions of steps 7 and 8 serve as the driving state change direction determining means. corresponds to Step 3~
The functions of step 6, steps 9 and 10 correspond to the driving range determining means.

Next, the basic fuel injection amount, which is another parameter that demarcates the operating region in which the learning correction coefficient Kl is memorized.
Regarding Tp, the region in which Kl is searched is determined in exactly the same way as in the case of rotation speed N.

That is, in steps 12 and 13, the basic fuel injection amount is
It is determined whether or not Tp is in a band-shaped region between the value obtained by subtracting and adding a predetermined value ΔTp to the lattice axis _Tpo , and in step 15, a flag G _o-1 is set;
At step 16, flag G _o-1 is determined, and at steps 17 and 18, the Tp area is determined.

Here, as in the case of the N region, step 15,
The function 16 corresponds to the driving state change direction determination means, and steps 11 to 14 and steps 17 and 18
This corresponds to the operating range determination means of the function.

Next, the process proceeds to step 19, where the N area determined in step 9 or step 10 and step 17
Or with the Tp region determined in step 18,
The learning correction coefficient Kl stored in the operating region surrounded by the grid axes N and Tp is searched. This step 19 corresponds to a learning correction amount search means.

In step 20, a voltage correction amount Ts is set based on the voltage value of the battery 20.

In step 21, it is determined whether the λ control condition is met.

Here, if the condition is not the λ control condition, for example, in a high rotation, high load region, etc., the air-fuel ratio feedback correction coefficient α is clamped to the previous value (or reference value α ₁ ) and the process proceeds from step 22 to step 23, which will be described later. .

In the case of λ control condition, step 22~
At step 24, the output voltage of the O ₂ sensor 16 and the slice level voltage are compared to determine whether the air-fuel ratio is rich or lean, and the air-fuel ratio feedback correction coefficient α is set by integral control or proportional-integral control. This part corresponds to the feedback correction amount setting means. Specifically, in the case of integral control, when it is determined that the air-fuel ratio is rich as a result of the comparison in step 22, the air-fuel ratio feedback correction coefficient α is decreased by a predetermined integral ( ) with respect to the previous value in step 23, and vice versa. , when it is determined that the air-fuel ratio is lean, in step 24 the air-fuel ratio feedback correction coefficient α is increased by a predetermined integral ( ) with respect to the previous value. In the case of proportional-integral control, in addition to this, when reversing rich←→lean, an increase or decrease is performed by a predetermined proportional amount (P) larger than the integral () in the same direction as the integral ().

In step 25, a new learning correction coefficient Kl _(oew) is calculated from the learning correction coefficient Kl retrieved in step 21 and the average value of the deviation Δα of the air-fuel ratio feedback correction coefficient α from the reference value _α1 according to the following formula. setting, correct and rewrite the learning correction coefficient data in the same area.

This step 25 corresponds to learning correction amount modification means.

Kl _(oew) ←Kl+/M (M is a constant, M>1) Thereafter, in step 26, the fuel injection amount Ti is calculated according to the following equation. This part corresponds to the control amount calculation means.

Ti=Tp・COEF・Kl・α+Ts When the fuel injection amount Ti is calculated, a drive pulse signal with a pulse width of Ti is output at a predetermined timing in synchronization with the engine rotation, and is sent via the current waveform control circuit 41. is applied to the fuel injection valve 11, and fuel injection is performed.

In this way, engine speed N and basic injection amount
Even if Tp fluctuates in the vicinity of the lattice axes N _{o and} T _po , the size of the lattice axes in the region where the learning correction coefficient Kl is searched has hysteresis depending on the direction in which these change, so that the adjacent learning regions It is possible to prevent hunting of the air-fuel ratio due to the difference in Kl between the current range and the unlearned range, and stable controllability can be obtained.

In addition, since the engine speed N and the basic fuel injection amount Tp have hysteresis in the direction of increasing and decreasing the operating range, respectively,
The provision of hysteresis allows the center of the operating region in which the learning correction coefficient Kl is stored to substantially coincide with the center of the operating region that is expanded by providing the hysteresis when determining the operating region. It is possible to avoid the negative influence of the learning function on the learning function, and it is possible to stably perform good learning control.

Although this embodiment has been described as being applied to air-fuel ratio control, it goes without saying that it can also be applied to idle rotation speed control, ignition timing control, etc.

<Effects of the Invention> As explained above, according to the present invention, when searching for a learning correction amount, the lattice axes of the operating state parameters that partition the operating region to be searched are set in two contradictory directions in which the parameters change. Since the configuration has hysteresis in the direction in which the operating range expands, it is possible to prevent hunting of the control amount when the operating state is near the grid axis, and the provision of hysteresis also improves the learning function. Adverse effects can be avoided as much as possible, and stable controllability can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration and functions of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is a block diagram of the control unit in Fig. 2, and Fig. 4 is a block diagram showing the configuration and functions of the present invention. Flowchart showing control details,
Figure 5 is a schematic diagram of the learning correction amount map, and Figure 6 is a schematic diagram of the learning correction amount map.
FIG. 7 is a time chart showing the relationship between the O ₂ sensor output and the feedback correction amount, and is a map diagram for explaining the learning control method of the prior application. 1... Engine, 6... Air flow meter, 10...
Idle control valve, 11...Fuel injection valve, 16...
O ₂ sensor, 17... Crank angle sensor, 30...
...control unit.

Claims (1)

[Scope of Claims] 1. Basic control amount setting means for setting basic control amounts corresponding to control target values of the internal combustion engine such as air-fuel ratio and idle speed; rewritable storage means that stores lattice axes for partitioning and learning correction amounts for correcting the basic control amount for each area surrounded by these lattice axes, and the storage means based on the actual engine operating state. a learning correction amount search means for searching for a learning correction amount for a corresponding region from the control target value; and a feedback correction amount for comparing the control target value and the actual value and correcting the basic control amount so as to bring the actual value closer to the control target value. a feedback correction amount setting means for setting by increasing or decreasing by a predetermined amount; the basic control amount set by the basic control amount setting means; the learning correction amount searched by the learning correction amount search means; and the feedback correction amount setting means A control amount calculation means for calculating a control amount from the set feedback correction amount; a control means that operates according to the control amount to control the air-fuel ratio, idle rotation speed, etc.; and a reference for the feedback correction amount. learning correction amount correction means for learning the average value of the deviation from the value, and correcting and rewriting the learning correction amount corresponding to the area of the engine operating state during that time in the direction of decreasing the learning correction amount; an operating state change direction determination means for determining the direction; and a determination means for determining the operating region in which the learning correction amount retrieved from the storage means by the learning correction amount retrieving means is performed in two contradictory directions in which parameters of the engine operating state change. 1. A learning control device for an internal combustion engine, comprising: operating region determination means that moves a grid axis that divides each operating region in a direction in which the operating region expands to provide hysteresis.