JPH03156141A - Air-fuel ratio learning controller of engine - Google Patents

Abstract

PURPOSE:To make learning correction possible even when an air-fuel ratio deflects largely from a theoretical air-fuel ratio by providing an exhaust sensor output reversing reference time setting means, an exhaust output reversing judging means, an air-fuel ratio feedback correction coefficient setting means, and a learning means. CONSTITUTION:First, in regard to an output reversing period of an oxygen sensor 24 (exhaust sensor) concerning specified slice level a reference time is determined by an exhaust sensor output reversing reference time setting means 57 on the basis of an engine speed and a fundamental fuel injection quantity. An exhaust sensor output reversing judging means 58 decides whether an output of the sensor 24 is reversed within the reference time. When it is decided that the sensor 24 output is not reversed within the reference time, an air-fuel ratio feedback correction coefficient setting means 60 makes an integration constant of a proportional-plus-integral control smaller to determine an air-fuel ratio feedback correction coefficient alpha. In accordance with decrease of the integration constant, a learning means 61 increases or decreases a learning value by a specified amount to determine a learning correction coefficient, in the same direction as the air-fuel ratio feedback correction coefficient alpha.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides an air-fuel ratio that deviates significantly from the stoichiometric air-fuel ratio.
Engine air-fuel ratio prediction with learning correction-II rJl
Regarding 100 books.

[Problems that conventional technology and inventions try to solve] Previously, 0
In the air-fuel ratio feedback control of the engine using a liveness sensor such as the 2 sensor, production of the intake air system such as the intake air quasi-sensor, and the fuel system such as the injector. In order to quickly correct deviations in the air-fuel ratio due to variations in 'i' or changes over time, learning control is introduced to maintain the stoichiometric air-fuel ratio at all times even when operating conditions change significantly. are doing.

Buoy fwame 5, engine constant state [ii
711 is determined from 1 rotation number and f;
If the air-fuel ratio refresh/lean is repeated a predetermined number of times by proportional-integral control, the correction coefficient of the air-fuel ratio feedback correction coefficient α is determined as follows: Learn the center value; +'+
is stored as a correction coefficient (A-Bunlube correction coefficient), and the above air-fuel ratio feedback correction coefficient α
The center of is set to be XJ'$嘗(+I'lαO(=1)).

As a result, if the operating condition changes, the above learning will continue regardless of the integral speed applied to the proportional-integral control 21) of the air-fuel ratio feedback correction coefficient α (generally several %/second). Since the value is reflected in the fuel injection l1) IB, the air-fuel ratio can be maintained at the stoichiometric air-fuel ratio.

However, the 02 sensor itself deteriorated and the output performance Jr. If [is deteriorated and remains significantly deviated from the slice level-), or the stoichiometric air-fuel ratio is 1! In cases where the air-fuel ratio deviation is large and the conventional learning cannot be applied, the above-mentioned air-fuel ratio feedback correction coefficient α becomes the correction limit value; The air-fuel ratio lip/phosphorus can be repeatedly changed to 4+- without -C. 4j゛／・I was unable to perform the new 4j゛/・study, and the viscous] Mitsushi 1 was ;! ! : IC, which has the problem of reducing running performance by 1 (1).

To deal with this by λ1, a 02 hinge is installed on the upstream side of the catalyst = 1 inverter, and on the flow side, and [output F of the 02 hinge on the downstream side]1
1 deterioration downstream 02t? The so-called double 02 compensates for r10 and compensates for the air-fuel ratio control I +/i function.
L7 system system has been proposed, for example, special 1:!
l In IMI 63 45440, downstream side 02
In addition to improving the response speed of sensor 4), downstream side 02
Techniques have been disclosed to prevent deterioration of transmission, fuel efficiency, drivability, etc. due to deterioration of Ren 1J.

However, even with a double 02 center system like the preceding example, learning correction cannot be performed when the air-fuel ratio deviation from the stoichiometric air-fuel ratio is large as described in -1 and 2. In this situation, the control system becomes so complicated that only 21st I- and M (< only (・There is).

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and enables learning correction even when the air-fuel ratio deviates significantly from the stoichiometric air-fuel ratio, thereby reducing the deterioration of exhaust emissions and fuel efficiency. worsening,
It is an object of the present invention to provide an air-fuel ratio learning system for an engine that can prevent deterioration of drivability.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides an engine air-fuel ratio learning system m+V.
The device uses an air-fuel ratio feedback correction coefficient based on the output of the exhaust sensor and a learning correction coefficient based on the air-fuel ratio feedback correction coefficient to correct the basic fuel injection ratio and set the fuel angle injection adjustment. The air/fuel chemistry P" control I system "1 to d3 (, the output reversal period of the above-mentioned vitality sensor for a predetermined slice level, and the above-mentioned IJI.
Exhaust sensor output reversal determining means for determining whether or not the output of the air vent has reversed within the reference time set by the loss air sensor output reversal reference time setting means; If it is determined that the output of 1J has not reversed within the above reference time, or if it has been determined that the output of the exhaust sensor has reversed within the above reference 15 times, the integral constant of the proportional integral control is made smaller and the air-fuel ratio is adjusted to the above air-fuel ratio. If the air-fuel ratio feedback correction coefficient setting means for setting a noise back correction coefficient and the exhaust sensor output reversal determining means determine that the output of the exhaust sensor does not reverse within the reference time, the control unit determines that the output of the exhaust sensor does not reverse within the reference time, in response to the decrease in the integral constant. A learning means is provided for increasing or decreasing the learning value by a predetermined amount in the same direction as the air-fuel ratio noise pack correction coefficient and setting the learning correction coefficient.

[Function] In the engine air-fuel ratio circular control device according to the present invention,
First, for a predetermined slice level, the engine rotation speed and the above! , and U s after wood fuel injection♀, set the support interval, and determine whether or not the output of the above '# sword sensor is reversed within this 1□tl'lt question. .

1) If it is determined that the output of the air loss distribution sensor 1) has not reversed within the above reference time, - [If it has been determined that the output of the air loss sensor 1) has reversed within the above reference time, Also, reduce the integral constant of proportional & 1-minute control and set the air-fuel ratio noid back compensation coefficient. In addition, the reduction of the above integral constant is 3
4, the learning value is increased or decreased by a predetermined value in the same direction as the air-fuel ratio feedback correction coefficient, and the learning correction coefficient is set 4.

Then, C1 corrects the basic fuel injection amount using the air-fuel ratio feedback correction coefficient and the learning correction coefficient, sets the fuel injection amount, and controls the air-fuel ratio.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

The drawings show an actual tS example of the present invention, Fig. 1 is a functional block diagram, Fig. 2 is a schematic diagram of a 1-engine control system, and Fig. 3 is an explanatory diagram showing steady state determination and a science 21 value table. , 4th
The figure is an explanatory diagram of the l-Itth N map to the rich/lean switching discrimination base, and Fig. 5 is 02t? An explanatory diagram that does not show the air-fuel ratio feedback correction and learning correction based on the lancer output voltage, and Fig. 6 shows the fuel injection control procedure. FIG. 8 is a flowchart showing the setting procedure, and FIG. 8 is a flow sheet showing the learning value update procedure.

(Configuration of engine fltII III system) No. 4 1 in the diagram
is the engine body, and the figure shows a horizontally opposed four-cylinder engine. An intake manifold 3 is communicated with an intake boat 2a formed in the cylinder head 2 of this one-engine Kokyu 1, and a throttle chamber 5 is communicated with the upstream side of this intake manifold 3 via an air chamber 4. An air cleaner 7 is attached to the upstream side via an intake pipe 6.

Further, the intake air aiI is placed directly downstream of the air cleaner 7 in the intake pipe 6? A throttle valve 5a (hot 941-type air flow meter in the figure) 8 is installed, and a throttle valve 5a installed in the throttle valve 5 is installed.
A throttle valve opening sensor 9a and an idle switch 9b for detecting whether the throttle valve is closed or closed are connected to the throttle valve 1.

Further, an injector 1° is disposed immediately upstream of each intake boat 2a of each cylinder of the intake manifold 3, and the tip of the injector is connected to the 8-air nfQ of the cylinder head 2 and exposed to the combustion chamber. A spark plug 11 is attached.

The injector 10 is communicated with a fuel tank 13 via a fuel supply passage 12, and the fuel supply passage 12 includes a fuel pump 14, a fuel filter 1,
5 is interposed.

Further, the injector 10 communicates with a fuel chamber 17a of a pressure regulator 17 via a return passage 16, and the downstream side of this fuel chamber 17a is connected to the fuel tank 1.
Furthermore, as shown by the dotted chain line in the figure, the pressure regulating chamber 17b of the pressure regulator 17 is also communicated with the intake manifold 3.

That is, from the fuel tank 13 to the fuel pump 14
The fuel fed under pressure passes through the fuel filter 15, reaches the injector 10 and the pressure regulator 17, and is supplied to the injector 10 while maintaining a constant pressure difference between the internal pressure of the inch manifold 3 and the fuel pressure. The fuel injection range from the injector 10 is controlled so as not to fluctuate due to fluctuations in the internal pressure of the intake manifold 3.

Further, a crank rotor 18 is pivotally attached to the crankshaft 1b of the engine main body 1, and this crank rotor 1
A crank angle sensor 19 made of a Ti magnetic pickup or the like for detecting the crank angle is provided on the outer periphery of the crank angle sensor 8 . Further, 1/
2 rotations of cams
A cam angle sensor 21 for cylinder discrimination is provided on the outer periphery of the cam rotor 20.

In addition, a cold fJl water lagoon sensor 22 faces the lie If cooling water passage (not shown in the figure) formed in the above-mentioned in-j-Kumamani hold 3, and
It communicates with air pipe 1-2b.
Reference numeral 25 is a catalyst converter.

(Circuit configuration of control device) 11. Reference numeral 830 is a control device, and the CPU of this control device 30 is 31. ROM32, R.A.
M33, 8 M34 with backup 1, OJ, Bi, I10
An interface 35 is further connected via a pass line 36, and a predetermined stabilized voltage is supplied from a constant voltage circuit 37.

- The fixed voltage circuit 37 is connected to the relay 39 via the control relay 38, and supplies control power to each part when the key switch 40 is turned on and the relay contact of the control relay 38 is closed. In addition, it is directly connected to the battery 39, and when the kiss switch 40 is turned off and the relay contact of the control relay 38 is opened, it supplies backup power to the backup RAM 3 /I and retains data. cover

In the input port of the above I10 interface 35,
- Registered Sen 1 No. 8.9a, 19, 21, 22゜2/I,
Then, the idle switch 9b is connected, and the positive terminal of the battery 39 is connected, and the terminal voltage VB is monitored.

The spark plug 11 is connected to the output port of the r10 interface 35 via the igniter 26, and the injector 10 is connected via the drive circuit /11. A fuel pump 14 is connected.

The ROM 32 stores a control program and fixed data such as a reference time map M P to for determining rich/lean switching, which will be described later.
The output values from the respective sensors after data processing and the data processed by the CPU 31 are stored. In addition, in the above backup 1, the learning value i-pull TBIR, which will be described later, is stored in ΔM34, and the stored data is retained even when the key switch f/10 is 01: There is.

[In CPtJ 31, the intake air ff1f is adjusted according to the i and II control programs stored in the ROM 32.
The amount of intake air is determined from the output signal of the engine 8, and the above RAM is
33 and the various data stored in the backup RAM 34, the fuel injection amount is calculated according to the intake air, and the ignition B; A drive pulse width signal corresponding to the above is output to the injector 10 of the corresponding cylinder at a predetermined timing via the drive circuit 41 to inject fuel, and the ignition of the corresponding cylinder is performed via the igniter 26 at a predetermined timing. An ignition signal is output to the plug 11.

As a result, the air-fuel mixture at a predetermined air-fuel ratio in the corresponding cylinder explodes and burns, and the oxygen concentration contained in the exhaust gas is detected by the 02 sensor 24 facing the 1 trachea 23. This detection signal After the waveform has been shaped, the CPU 31 compares it with the quasi-voltage signal u, and deciphers whether the air-fuel ratio state of the engine is on the rich side or lean side with respect to the L1 standard air-fuel ratio J and the stoichiometric air-fuel ratio. If the air-fuel ratio is ridge, then l Q
If it is I+, lean, "1' is stored in the RAM 33. The CPU 31 stores the air-fuel ratio of ila Aiki, -+ j-j
is monitored at a predetermined time or every predetermined cycle, and the next data derivation process is performed.

(Functional configuration of control device) As shown in FIG. 1, the fuel Fl injection tII of the control device 30
I111 (Functions related to air-fuel ratio control 'a>
, voltage correction coefficient setting means 54, phytoback condition establishment determination means 55, learning condition determination means 56, exhaust sensor output reversal reference time setting means 57, exhaust sensor (02 sensor) output reversal determination means 58, integral constant correction means 59, Air-fuel ratio feedback correction coefficient setting means 60, learning means 61, fuel price: $31,116! It is composed of an IF suspension setting means 62 and an injector driving means 63.

In addition, the lower stage 57 for setting the above exhaust sensor output inversion ljttF-o is the reference 11 for determining lip/lean switching.
．． 1 interval setting means 57a, rich/lean switching discrimination base t
It is composed of v-[,'1 question map M Pto,
The learning f stage 61 includes a learning value updating means 61a, a learning value updating means 61a, and a learning value updating means 61a.
--/Ruo BIR1 Consists of learning correction coefficient setting means 6jb.

Intake air hanging sieve stage 50, -engine rotation speed outlet stage 5
1'C- is intake air port upper hole 8, crank angle 1J1
From the output signals of 9, the intake air amount Q and +engine rotation speed N are determined, respectively.

The U non-combustible FL output setting means 52 uses the intake air ωQ output from the intake air ω0 output stage 50 and the engine [i11 rotation r!
Based on iN, Hayashimoto fuel injection tension TpjFr is output by map search or by Rensen.

In addition, in the tree embodiment, the above basic fuel injection Q is determined by the function p.
4ffiTp is meddling (Tp = ni-Q/N:K
···constant).

Each scale increment correction coefficient setting means 53 outputs a throttle control (θ) signal of the throttle opening angle 9a, ON and OFF (Ij) of the idle switch 9b, and a cooling water temperature sensor 22.
cold 7Jl water thirst (Tw) (read No. 9, acceleration speed correction,
7) Set the increase correction coefficient CO [[ for each of the full-open increase supplement ■, post-idle increase supplement H2, cold 7Jl water shortage correction, etc.

The voltage correction coefficient setting means 54 sets the invalid injection time (
Pulse width) is read from a table (not shown), and this value is interpolated from A+injection time by -4 to 11 correction coefficient]S+setting.

Determining whether the Noedback Article fl is established (Ding Danpo) 5 C is 02
1? In addition to determining whether the current level 24 is in the idiosyncratic region or old, the cold 7Jl water thirst (TW
) signal, the engine speed N determined by the engine speed a calculating means 51, and the basic fuel injection dividing zero output means 5.
Read the basic fuel chanting sword amount Tp mentioned in step 2, and use the above 02
T? It is determined whether the air-fuel ratio feedback control condition f1 is satisfied even if the engine 24 is in the active region.

Whether or not the 02 sensor 24 is in the active region is determined by, for example, whether the output voltage VAr of the 02 sensor 24 is equal to or higher than a set value, and the output voltage V^[ of the 02 sensor 24 is set. Even if the CIs state is greater than the value, when the cold 7Jl water thirst Tw from the cooling water temperature sensor 122 is below a predetermined value (for example, below 50°C), the engine rotation speed N
is the set rotation speed NS or more (for example, 520 Orpm or more)
At the time, the above-mentioned parking fuel injection fiTp is the set value Tp
S or more (throttle substantially open region), it is determined that the air-fuel ratio noise back control condition f1 is not satisfied; otherwise,
In addition, only when the 02 sensor 124 is in the active state, it is determined that the air-fuel ratio feedback control condition is established.

In the learning condition determination stage f 56, when the feedback condition establishment determination means 55 determines that the air-fuel ratio feedback control condition f1 is established, the engine rotation speed N calculated by the engine rotation speed output means 51 and the tree parking lot are determined. Fuel injection suspension calculation f
Basic fuel injection m TD and reading calculated in stage 52;
It is determined whether the engine speed N and the sample fuel injection OA amount Tp are within a range from 71 to RIXMT (see FIG. 3) formed by each address of a learned value table BIR to be described later.

So-C1 The engine rotation speed N,! :12 fuel injections rti T 11 is within the matrix MT, a section in the 7 matrix MT is determined, and if this section is the same as the section selected last time, it is determined that the learning condition is satisfied.

In the exhaust sensor output reversal reference time setting means 57, when the learning condition determining means 56 determines that the learning condition is satisfied, the exhaust sensor output reversal reference time setting means 57a sets the first standard time setting means 57a for rich/lean switching determination.
So, 02t! When the output voltage VAF of the sensor 24 is reversed from the air-fuel ratio rich side to the air-fuel ratio lean side or from the air-fuel ratio lean side to the air-fuel ratio rich side with respect to the slice level Reference time t for determining lean switching.

will be established.

The above-mentioned reference time 0 for rich/lean switching determination is determined by using the engine rotational speed N and the 3 unsatisfactory fuel injection patterns p as parameters for the retsu f/lean switching standard n, 51! ! Search the map for 1 Massi MP10 - (02 when set and normal)
The inversion layer of Renri 24 + lII J and Rin 1 are set at just the right time.

-1- Write down 1/' lean switching discrimination 41ry time map M P tof, L, as shown in Figure 4, yr engine rotation number N and) 1 non-flammable power 111fI Q4 product rp as parameters. It consists of a map, and each of the 7 dresses in this map
Between 1 and 1, 0 is determined in advance through experiments, etc., and is set to 1 to 7.

It is necessary to switch the lip/lean of the output voltage ffVAF of the above 02 center 2/I; Long.For example, idol I1.
The lip/lean switching time requires about 1 sec.
', If, '+10 is to=2-3 sec and G le.

The 021x output reversal determining means 58 reads the output voltage VA) of the 02 sensor 1J24 and determines the output voltage V.
Ar has reversed to the air-fuel ratio lip side or the air-fuel ratio lean side within the U-type time for rich/lean switching discrimination set by the above-mentioned ridge/lean switching discrimination semi-time setting means 57a with respect to the slice level VS. It is determined whether or not l! is sent to the learning value updating means 61a. /J-d and the above Rif-/Lean 1,7J exchange discrimination Kawamoto base within 10 hours
When the output voltage V8I of the 02 center 24 has a negative value of φλ, it is determined that the air-fuel ratio is largely deviated, and an I/O command signal is output to the integral constant correction means 59. In addition, 7! Outputs I (ll+correction information) to the learning value update stage 610.

With the five integral constant correction means, the above 02 t! The 1-value correction operation t1 command signal from the sensor output reversal determining means 58 is J, the air-fuel ratio feedback correction coefficient α is <1
) and outputs the I1m correction signal to the air-fuel ratio feedback correction coefficient setting means 60.

The air-fuel ratio feedback correction coefficient setting means 60 sets the output Ti If: V^[ of the 02 sensor 24 and the predetermined mesh level VS when the feedback regulation establishment determination means 55 determines that the air-fuel ratio noise back control clause f1 is satisfied. Based on the comparison, an air-fuel ratio feedback correction coefficient α is set using proportional-integral control.

1, then -[02 It 24 output voltage VAr
Compare the slice level vs.
I'>VS), the above air-fuel ratio feedback supplement W
Starting from the coefficient α, stepwise F by the proportionality constant P (α←
α-P), then the constant of integration is 1 minute (J gradually lowering (
α←α−I) Set the air-fuel ratio to be lean. the result,
When the fuel injection tiJ mother Ti, which will be described later, decreases and the air-fuel ratio becomes thinner (VAr<VS), the air-fuel ratio feedback correction coefficient α is changed to a proportionality constant ρ (J-stepwise (α←α−
+, P), and gradually increase the integral constant I from each (α←
α1I) Set the air-fuel ratio to be rich and repeat this step 1
゜In this case, when the I correction signal is manually input from the integral constant correction means 59, the air-fuel ratio feedback correction coefficient α becomes α←αKIXI or α←α0KIxl depending on the state of the air-fuel ratio. J, it is set.

It should be noted that in the feedback section 1-f) establishment discriminator stage 55, the 02 L-key 24 is inactive or activated.
When it is determined that the air-fuel ratio feedback control condition is not satisfied because the air-fuel ratio feedback control condition is determined to be in the almost hear region, the air-fuel ratio feedback correction coefficient α is fixed to α-1.

The Gakuden 1 means 61 uses the I value correction information from the 02 pincer output reversal discriminating means 58 to determine whether the learning condition is satisfied and When it is determined that the steady state is established, the learning value Delpull T B is set based on the air-fuel ratio feedback correction coefficient α set by the air-fuel ratio feedback correction coefficient setting means 60.
Update LR's school value K[R. Then, a learning correction coefficient KBI-RC is set in the interpolation module 1 from the learning value KLR stored in the learning value boolean TB[R.

That is, from the 02t sensor output inversion determining means 58 to 1
When the value correction information is input, the learned value is updated.
-C1 Ten air-fuel ratio noise back supplementary II-correction amount 1'l
tx do l-ki', L i'-611a O do 7
M, write △(x(△αα〇−α)) and write it! , 4 wood burner (g) product setting stage F) 2 C set work, 4 wood burner slope 11r) Q4 hanging I-p as a parameter, ;7
．． 5111'I table 1131RU) Stored in a predetermined trace
According to the 1st deviation; Te 1 degree ΔU of 11 ←-, the C minute setting allowance K1. Add R3;) or kl '6ice'l
' Update the above science 2'l lll'l K I R (Kl-RK 1.R+ K 1lisl-T,
Or (1, KIR(Kl)t K1-ll5IT)
.

Then, the air-fuel ratio is 11 normal 1. πdofisu, I I(+
When supplement 11 stops 1, 1-02 output reversal discrimination stage F) 8M' (1-02 L-IJ 24 (1) output voltage 1t, V8F is 1 times (for example, 3 times) If the above is reversed and it is determined that the steady state
1. ? +li tl coefficient % (Z middle +ll'Jα) No. 16 Ya ('1α0(=-1
) and find the partial noise RΔα (△α・−α〇−α), and the 1st space j1M ship Kl−R is −
Sasa update (Kllt←KLR−△α; see Figure 5)
.

After C1, if the output voltage VΔ[ of the 02 sensor 24 is determined to have been reversed once or more by the 02 output anti-east discrimination means 58 in the manner 1111, the bias is determined to be 0△.
The predetermined 7111 values of α are added to the learned value KLR) or t is subtracted C>L, and the learned value Kll't is updated (K
l−R←11 Δα/M: △α × O’s addition Q, Δα
〉C decreases when O).

In addition, M is a constant that determines the ratio of learning (me 1 historical ability 1).

Upper class 2'l (fi 'J' -1ruT [3l
It 4. L, hackup R△M3/l,
J shown in Figure 3, sea urchin 3. +KIR is stored in non-flammable learning and a3 is set to 1, and C is K11 (-
・1.0 is stored.

In the PI supplementary + r coefficient setting f stage 61b, the above-mentioned fufu fuel injection IdQ output stage! □Fumoto Fuel Injection 11 that came out n at 52
The above learning with Tp as a parameter (pilable T [
3[Search R, interpolate 3I C'>'s knee J-'
J Learning 'i+8 i) E Section FI K B L RC
will be established.

The fuel injection ω setting means 62 also does the above! Non-combustible injection) 1 suspension setting F stage 52 indicates that L fuel injection suspension Tp is set by the various increase correction coefficient setting means 53Q set various increase correction coefficients CO [[, the above air-fuel ratio phytback correction Coefficient setting means 60' (-set air-fuel ratio feedback correction coefficient α, voltage correction coefficient setting means 54-C set ゛Pressure correction coefficient 1-3), the above-mentioned learning correction coefficient setting means 61b Set.゛1/, 1/, Gate correction amount number 1 RI U C · Gate correction to set fuel injection IJI suspension Ti = Tp xcO [FxKBLRc×α) 1-
8), Kono fuel II an injection F11. A drive pulse 6 is output to the injector 10 of the corresponding cylinder at a predetermined timing via the injector drive means 63.

As a result, as shown in Figure '55, the air-fuel ratio deviates greatly by 1 from the stoichiometric air-fuel ratio, causing the above-mentioned 02 t? Green 24
If the output FaffVAF deviates significantly from the slice level ■S, the air-fuel ratio feedback correction coefficient α
However, the correction amount related to the integral constant ril is smaller than usual (α←α±Ki×■; O<Kku1), and the
(lffKLR is slightly updated by m (Kl[t←K1.l
+±KLR3[T), the basic fuel injection ff1Tp is corrected based on the air-fuel ratio feedback correction coefficient α and the learning value KLR (pU correction if-coefficient) (BLRC), and the fuel injection f?ITi is set.

Therefore, as shown by the broken line in FIG. 5, conventionally, when the air-fuel ratio deviates significantly from the stoichiometric air-fuel ratio), the air-fuel ratio feedback correction coefficient α is corrected by an integral constant of 1, and the control limiter (for example, 0. 75α≦1゜2), learning is not performed and the air-fuel ratio continues to deteriorate.
If so, sticking of the fuel ratio noidback correction coefficient α to the control limiter is avoided, and the air-fuel ratio can be maintained at the stoichiometric air-fuel ratio by the air-fuel ratio feedback correction coefficient α and the learning correction coefficient KBLRC.

(Dynamic fl-) Next, the control procedure of the control device 30 will be explained according to the flow mill shown in FIGS. 6 to 8.

(Fuel injection control procedure) Figure 6 shows the fuel injection control procedure. l! returned.

Yoji, sudotsubu 5IOI, crank angle sensor 19, intake air! 13 Read the output from Renri 8], -
The engine rotation vi, N, and the intake air amount Q are t>ilj.

Next, proceed to C゛, step 5102, and perform the above step 5.
From the L engine rotational speed N and the intake air aQ extracted in step 101, calculate the non-flammable jet z1 jet Q4 sheet 1-p.
=KxQ/N:K...constant), proceed to knob 5103.

Sujtsu l5I03ζ゛ is cold j9 water thirst Renri 22, me]
Read the cold 14 + water dry 1 urw, the water dry 1 urw, and the idle switch output from the idle switch 9a and idle switch 9b, and in step 5104, coolant correction correction, acceleration/deceleration correction, all questions. Augmentation supplement 11/'After idle 11
i Set the correction coefficient CO[1 for various increases related to suspension supplement 1, etc.].

Next, proceed to step 3105/\ and release 39 lines;
"Injector 10 disabled 1 due to voltage VB of 1.4"
1C1QJ Set voltage correction coefficient TS+ to interpolate between B and j, and proceed to sub1-sub5IOG.

In step 8106, the learning value table T' 131. Search for R and set the learning correction coefficient 1 (B1.l1lC) for the interpolation filter.

Next-C, proceed to step 5107 and load RAM 33
Air-fuel ratio feedback correction coefficient α
(Zo 1 of the curved air-fuel ratio feedback correction coefficient setting described later)
step 810
Proceed to step 8.

s) s + o a ”c is the step 510 above.
I released 2rC'l! 1 to real twist II oQ 躬b”+T
11 wo, J Sunosofu 5104-(set various increase correction coefficient CO[F, step S10 !+
'-(-The voltage correction coefficient IS set and the air-fuel ratio feedback correction coefficient U read out in the first step 5107.
In addition to the correction coefficient KB1 set in step 5ioc above. Perform learning correction using RC and set fuel injection III fii Ti (Ti = T(l
xcorl'xKBLRCxαITS).

Then, in step 5109, the step 310B is set to 'C', and a drive pulse width corresponding to 1 liter of fuel is output to the injector 10 of the corresponding cylinder at a predetermined timing.

(Air-fuel ratio feedback correction coefficient setting procedure) Next, the setting procedure of the air-fuel ratio feedback correction coefficient α will be explained according to the flowchart of FIG.

The procedure for setting this air-fuel ratio feedback compensation coefficient α is
1 gram is a program that is opened at a predetermined time or (, L is repeated every predetermined period. First, step S201-
(', cold rJl water temperature T-, engine speed N, and l
j Based on this fuel injection Tp, the air-fuel ratio fiber n
1ll Determine whether V11 clause is established.

In the step 3201, when it is determined that the air-fuel ratio feedback control condition f1 is not satisfied, the subj "tub 320
Step 521G Heji 1 from 1! Then, the air-fuel ratio feedback correction coefficient α is fixed at α-1 and the program is exited ('J). If it is determined that the air-fuel ratio feedback control condition is satisfied, the process proceeds from step 5201 to step 5202.

Proceeding to step 5202, the output voltage VA of the 02 sensor 24 is read, and in the step 5203, the output voltage V Compare and determine whether the fuel ratio is currently on the lip side or the phosphorus side.

Above step 52031', V Ar> VS,
Although it is 1J, the air-fuel ratio is separated from the knob side, but 1
From Snowtub 5203 to S)-Z 5204), there is a lip/lean switching issue [18 G1 is Hira]
- (determine whether or not there is).

The rich/lean switching discrimination flag FIAGI is used to indicate the reversal of the output voltage V of the 02 center 2/I from the air-fuel ratio phosphorus side to the air-fuel ratio rich side, or from the air-fuel ratio lip-side to the air-fuel ratio phosphorus side. When the reversal occurs, the value changes, and the air-fuel ratio changes from the lean side to the air-fuel ratio lip side (-1 → 0, and the air-fuel ratio lip side changes to the air-fuel ratio lean side, resulting in 0-).
It becomes 1.

According to (, above step 5204'C-1 [[^G1-1
In the case of , the above air-fuel ratio feedback correction coefficient α (or proportional constant [) + J) is skipped in the plus h direction, and the air-fuel ratio is corrected by the integral constant 1, so that the air-fuel ratio becomes rich. Step S20 from i-tub 5204
Proceed to step 5 and set the L-shaped fuel ratio noise back correction coefficient α to the proportional constant r! I, p (non-inname 1j direction hess) Tsubusa 1!
α-α-P), suit l3209 ('upper, 2 lip/lean I, IJ conversion determination flag I'1AG1 cleared)
'Site(Fl^G1(O)bu[') Grams can be handled.

-h1 Above stripe 52011 IIΔGl=O,
! 1. In addition, the air-fuel ratio feedback supplement i E Proceeding to step S206 from 5204, l i11'
+ It is determined whether or not the correction adjustment l'1AG2 has been inserted.

Upper i211ff + Correction Nolag [[8G2 L, above 0
2 output of 2/I; lj If VΔ" is lip/
IJ QCn for determining lean ref. Switching discrimination base it, Il, 'i
During the interval 0, the output voltage f1i V^[ of the above 02 sensor 24
If it is determined that has been reversed, the process proceeds from step 5206 to step 5207, where the air-fuel ratio S-back correction coefficient α is decreased by the integral constant 1 (α←α−1), and the step 5206 After 5209
Noru.

10,000, in the 1st jump 3206, [1^G2-1, that is, within the reference low interval 10 for determining the above-mentioned Ritsu f/Lean switching] 02 Hin 4J 2,! When it is determined that the output voltage V8[ is not inverted, the process proceeds from step 5206 to step 75208, where the integral constant 1 +, m predetermined complementary 1F-coefficient Ki (0<Ki < 1) is set to the east stop. to be smaller than iδ, and the air-fuel ratio feedback compensation i
Reduce the decrease in f coefficient α (α←α−KiXl), ■I
71, please pass the above Suntsubu 5209 (Bu [J Gram (
Friend.

-PJ, upper 7d suit 7S203r, V Ar<,'
V S , 1J/r If the fuel ratio η' is determined to be on the lean side, the process proceeds from step 5203 to step 52.
Proceed to step 10 and similarly set the lip/lean switching determination flag F.
Determine whether IAG1 is hit or not, and
If l = O, -d, the air-fuel ratio feedback correction coefficient α becomes the proportionality constant P, J, in the negative direction.
If the air-fuel ratio is in a state where the air-fuel ratio is made lean by gradually reducing the knob by the constant value of 1, proceed to step S2+1/\.

Step 5211C changes the air-fuel ratio feedback correction coefficient α to a proportionality constant P or to a positive direction (α←a
i-p), and the process proceeds to step 5215C, where the lip/lean switching determination flag F1. Set AGl to 1~ (
rLAGl1-1)
Gl = 1,! 1%)), if the air-fuel ratio feedback correction coefficient α is 1 and the skip in the positive direction by the proportionality constant P is actually t1, then step 5210 is performed.
Proceeding to step 5212, the I value correction nolag rLAG
It is determined whether or not 2 is hit.

In step 5212 of No. 11, "In the case of l-8C2-0, proceed to step 5213, increase the air-fuel ratio feedback correction coefficient α by the integral constant I, and
) proceed to step 5215 while FIAG2 = 1
However, if the output voltage ΔF of the 02 sensor 24 is not reversed within the ridge/lean switching time [θ], the steps 5212 to 5 are performed.
Proceeding to step 214, the correction coefficient is multiplied by 1 to the integral constant 1 to make the correction of the air-fuel ratio feedback correction coefficient α by the integral constant 1 smaller than the appropriate value α←α to K1
X1)', proceed to Slurtub 5215.

Then, step S215'-('', the above lip/
Clear the lean switching determination flag rlAG1 (FLA
GI←0) Bu [1 gram can be collected.

(Learned value update procedure) The learning value update procedure is indicated by the lobe 1.-1. (10 grams of one update procedure is shown in FIG. 8), and is repeated at a predetermined time or every predetermined cycle.

In step 5301, similar to the 11] grams tube 5201 for setting the air-fuel ratio feedback correction coefficient described above,
It is determined whether the air-fuel ratio noise back control conditions are satisfied based on the cold u1 water temperature TW, the engine speed N, and the basic fuel injection height Tp.
If 1 gram can be handled and condition f4 is satisfied, step 530
Proceed to step 2.

Next, in step 5302, the engine speed N and basic fuel injection ff1Tl] are read out, and the process proceeds to step 5303, where the engine speed N and 11 fuel injections Tp are within the range of the matrix MT (as shown in FIG. 3). No≦N5
It is determined whether or not Nn, TpO≦1-p≦Tpn).

Above step S 303 t-1 above 71~Rix M
If it is determined that it is outside T,
If it is determined that the 1292 rotation speed N and the basic fuel injection MTp are within the update control target range of the helix M1-C, the process proceeds to step 5304. Number of revolutions Nd”-Record jt Main fuel injection Ff
The partition position F in the matrix MT is determined by il'p.
'1' is specified, for example, as section 1) 1 in FIG. It is determined whether the learning conditions are satisfied by comparing the position of the warehouse and the IJ section.

If the position of the section determined by 1!
Proceed to step 05, store the position l of the partition in the matrix MT specified in this program in RΔM33 as the previous partition position data, proceed to step 3306, clear the counter (C10), and exit the program (). .

In addition, in the first program execution, since there is no previous partition position) - evening, steps 5303 to 53
05 hejanbu, Su up 8306 light, overtake the program by 1 no.

7J, in step 5304 above, if the position of the previous 11.1 grams C identified section and the position of the section identified this time are the same, the steps from step 5304 to step S3
Proceeding to 07, the engine rotation speed N [read by the distribution slap 5302] and the basic fuel injection ff1Tp are balanced to 0, and the ref/lean switching is determined n+ >;ttll: i,
Search the % interval map M P to and set the quasi-costal interval 10 for ridge/lean cutting discrimination.

Next, proceeding to step 8308/\, 02t? Nri 24
Read the output voltage ＾1, and this output voltage is 1
- Shoes 1/Lean switching determination HiIt set in step 8307, determines whether the air-fuel ratio has reversed from the air-fuel ratio lip side to the air-fuel ratio phosphorus side or from the air-fuel ratio lean side to the air-fuel ratio ridge side within the intercostal space [O]. Discern.

- [In the subassembly 8308, the above rich/lean switching discrimination base i1'-11,j is between 0 and 02 zen 1) 2
If it is determined that there is no inversion of the output voltage V^' of 4, the process proceeds from step 8308 to step 5309, where the l value correction flag F[8G2 is set to 1- ('1^12←1)
.

Next, the process proceeds to step 5310 to calculate the deviation amount Δα between the current air-fuel ratio feedback correction coefficient α and the air-fuel ratio feedback correction coefficient 11aα0 for the base air-fuel ratio (Δα←α0−α), and in step 5111, It is determined whether the deviation amount Δα is Δα<0.

”-♂ If Δα<0 in suit tube 5311, proceed from step 5311 to step 5312, and read mT for basic fuel 117i read in step 5302 above.
Using p as a parameter Bff l/j-7-Pull TO
1, It is searched, and in step 5313, the learned value KLR
The minute setting value K LR3ET is added to the new learning value K IR+-K 1. R1-KIR3[T
), Proceed to step 5317. Note that the learning value update in -C is performed in response to the I value correction in step 5214 in the air-fuel ratio feedback correction coefficient setting program described above.

-・1 No. If the deviation amount Δα is △α≧O in the above step 3311, the process proceeds from the step 5311 to step 5314, where it is determined whether the deviation Δα is Δα>0, and Δα−
In the case of 0, the 02 sensor 2/I is determined to be malfunctioning, and the process is performed in step 5315.
Proceed to.

In step 5315, the learning value table T B LR is searched using the base non-combustible injection suspension Tp read in step 5302 as a parameter, and the process proceeds to step 331G/\ where the learning value K1. Minute setting value K from R LR8 [Deenergize T]
K LR+-K LR-
K1-R8Fr: Corresponding to the I value correction in step 5208 in the air-fuel ratio feedback correction coefficient setting program), the process proceeds to step 5317.

Then, in step 5317, there is no reversal of the output voltage VAF of the o2 sensor 4f 2 /l within 1 hour [θ] for rich/lean switching discrimination, and the learning value is updated in accordance with the ll1i correction of the air-fuel ratio feedback correction coefficient α. The I value correction learning value update flag E [AC3 is executed (Fl8 to 3←1) indicating that the I value correction learning value update flag has been performed.

-Buno, 1st sub-j knob 5308, [1. The above time to 021! Nri 24
If there is a reversal of l to the output type J3V, proceed from step 5308 to step 5318, clear the 11f1 correction nolag rlAG2 (rl 8 to 2 O), step 5319, counter force/syn 1 ~(Click the target) Ara/Riru (C(-C10).

And Menozzo 5320'r, the /J und (uol of the above counter is ``) (for example, 3) J, a small abomination, a fixed farm f,
-1 no, Karan 1 to Haku becomes n to -L, and fixed-batta Buddha 4
The sig 5321/\ advances indistinguishably.

J, engine rotational speed N and basic fuel r'l 1l (
The operating status according to l rJ・1♀Tp is road-to-road, and ■
First, if the output voltage ffVAr of the sensor 24 is reversed once or more, it is determined to be in a steady state, and the process proceeds to 'Csushi/5321, clearing the above counter (Cri-0).
Rir.

Next, using Mechitube 5322, calculate the deviation Δα between the average value α of the air-fuel ratio feedback correction coefficient α during 11 skips and the dead II1 value α0.Δα←αOα)
, in step 5323, using the fuel injection II suspension T p read in step 5302 as a parameter, calculate:
I l+fl Search for learning 1fiKLR from the corresponding address in table T B LR, and proceed to step 5324.

In step 5324, the I value correction learning value update flag r1
．． Determine whether AC3 is hit or not, and set FLAG
3.-○, Zunawara, 1 until the last B1kogram fruition
1. At point J3, the output voltage V of the above 02 senna 24
This is a normal state in which the correction is reversed within the reference time to for determining the ridge/lean switching, and there is no learning curve for the IIdi correction.
If NKt-n has not been updated, the process proceeds from step 5324 to step 5325, where the learning value KLR retrieved in step 5323 and the step 532 are updated.
From the deviation aΔα obtained in step 2, a new learning value K [R is set (KLR4−KLR−Δα/MUM: a constant that determines the ratio of updating the learning value), and the process proceeds to step 8328.

10,000, in the above step 5324, F [8 G3 = 1, that is, the previous output voltage of the above 02 Zenri 2/I ■ A [ is 1 - the base value for determining the knob/lean switching is between 0.1 ( The update of 11 (to the learning value without inverting within 0 is minute setting candy K IR3
[When T is J, the process proceeds from step 5324 to step 5326, and step 5
From the science and Il+riKLR retrieved in step 323, the deviation amount Δα obtained in step 3322-(-t1 is reduced and set as a new learning value (1(+, R←-K IR-Δα), learning value table TBI- The value of the corresponding address of H is updated, and the process proceeds to step 5327, where the 'fuel ratio noise back compensation correction number α is set to α=1, and the process proceeds to step 3328.

Then, in step 3328, the I value correction learning value update flag rLAG3 is cleared (FLAFG3←0), and the program is terminated.

[Effects of the Invention] As explained above, according to the present invention, the output reversal period of the active sensor for a predetermined slice level is determined based on the engine speed and the basic fuel injection tAfjl. A quasi-time is set, and it is determined whether or not the output of the exhaust sensor 4 is reversed during this reference period.

Then, when it is determined that the output of the upper distribution 1 ki sen 1 no is not reversed within the upper distribution ■ time, and when it is determined that the output of the 1 no + ki sensor has reversed the above ILi% within the time, Suppose that the above-mentioned air-fuel ratio feedback correction coefficient is set by decreasing the integral constant of the proportional-integral control, and in response to the decrease in the above-mentioned integral constant, the learning value is increased or decreased by a predetermined value in the same direction as the above-mentioned air-fuel ratio feedback correction coefficient. Conventionally, since a correction coefficient is provided, when the air-fuel ratio deviates from the stoichiometric air-fuel ratio, the air-fuel ratio feedback correction coefficient reaches the upper and lower limits of control and becomes stuck, causing the air-fuel ratio to deteriorate without learning. This will be prevented.

In other words, even when the air-fuel ratio deviates significantly from the stoichiometric air-fuel ratio, appropriate learning correction can be performed, and excellent effects such as preventing deterioration of exhaust emissions, deterioration of fuel efficiency, and deterioration of drivability can be achieved. be done.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a functional block diagram, Fig. 2 is a schematic diagram of the engine control system, and Fig. 3 shows steady state determination and a learning value table. 1 explanatory diagram, Fig. 4 is an explanatory diagram showing the reference time block for determining lip/lean switching, Fig. 5 is an explanatory diagram showing the air-fuel ratio feedback correction and learning correction based on the output voltage of 02 centigrade, and Fig. 6 is an explanatory diagram. is moe F
Figure 7 shows the flowchart showing the injection control procedure;
Figures 17-1 to 8 are diagrams showing the Gakushinchin saragae procedure.
も+r −1・. 1...Engine body 24...02t? Nri (IJI Ki Senri) 57...
- Air sensor output inversion Lt quasi-interrogation setting means 58...0
2t? Air-fuel ratio output reversal determination means 60...Air-fuel ratio feedback correction coefficient setting means 61
...Learning means N...] - Engine rotation speed Tp...L4 wood fuel injection suspension T-i...fuel tpI injection OA suspension α...air-fuel ratio feedback correction coefficient K BLIIC
...Gakudo 1 correction coefficient VA [...O2 sensor (exhaust sensor) vS...Slice level to...Reference time I...Integration constant KIR...Learning (learning)) t Jt th 3 Figure 4 TpO, 1Tp2't+3 ・ ya) 1- Figure 5

Claims (1)

[Claims] Air-fuel ratio learning control that corrects the basic fuel injection amount using an air-fuel ratio feedback correction coefficient based on the output of an exhaust sensor and a learning correction coefficient based on the air-fuel ratio feedback correction coefficient, and sets the fuel injection amount. In the apparatus, an exhaust sensor output reversal reference time setting means for setting a reference time based on an engine rotation speed and the basic fuel injection amount with respect to an output reversal period of the exhaust sensor for a predetermined slice level; exhaust sensor output reversal determining means for determining whether the output has reversed within the reference time set by the exhaust sensor output reversal reference time setting means; If it is determined that the output of the exhaust sensor has not reversed within the reference time, the air-fuel ratio is set by decreasing the integral constant of the proportional-integral control and setting the air-fuel ratio feedback correction coefficient. When the feedback correction coefficient setting means and the exhaust sensor output reversal determining means determine that the output of the exhaust sensor does not reverse within the reference time, the feedback correction coefficient is the same as the air-fuel ratio feedback correction coefficient in response to the decrease in the integral constant. What is claimed is: 1. An air-fuel ratio learning control device for an engine, comprising: learning means for increasing/decreasing a learning value by a predetermined amount in the directions and setting a learning correction coefficient.