JPS60228741A - Air-fuel ratio control - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for controlling the amount of fuel supplied to an internal combustion engine such as an automobile gasoline engine, and particularly to sufficiently suppress deterioration of exhaust gas during deceleration driving. This invention relates to a control method that enables

[Background of the invention]

As interest in environmental conservation by preventing air pollution and the depletion of energy resources increases, efforts are being made to comprehensively control the operating conditions of automobile gasoline engines to improve exhaust gas conditions.
There is a growing demand for sophisticated control devices that can improve fuel efficiency, and as a result, microcomputers (microcomputers)
The system uses signals from a cooling water temperature sensor, a sensor that detects the presence or absence of oxygen in exhaust gas, and a sensor that provides data for each building that indicates the operating status of the engine, and calculates fuel supply amount, ignition timing, and idle speed. Electronic engine control devices (hereinafter referred to as EECs) have come into use, which perform various controls such as the number of engines and the amount of exhaust gas recirculation so as to always obtain the optimum operating state of the engine.

An example of a system in which such an EEC is applied to a fuel injection type internal combustion engine is proposed in Japanese Patent Application Laid-open No. 134721/1982, and this conventional example will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a partial sectional view schematically showing the entire engine control system. In the figure, intake air is supplied to the air cleaner 2. Throttle chamber 4. e. Pass through the trachea 6 and feed into the cylinder 8. The gas burned within the cylinder 8 passes through the exhaust pipe 10 from the cylinder 8 and is discharged into the atmosphere.

The throttle chamber 4 is provided with an injector 12 for injecting fuel.
The fuel ejected from the throttle chamber 4 is atomized in the air passage of the throttle chamber 4 and mixed with the pastoral air to form a mixture. is supplied to the combustion chamber of

An MD valve 14 is provided near the outlet of the injector 12. The control valve 14 is configured to be mechanically interlocked with an accelerator pedal, and is driven by the driver.

An air passage 22 is provided upstream of the FF valve 14 of the throttle chamber 4, and a hot-wire type air flow needle made of an electric heating element, that is, a flow rate sensor 24 is disposed in this air passage 22, and the flow rate sensor 24 is arranged in accordance with the air flow rate. An electrical signal AP is extracted that changes as the signal changes. Since the current sensor 24 made of this heating element (hot wire) is installed in the bypass air path 22, it is protected from high-temperature gas generated during backfire from the cylinder 8, and is also contaminated by dust in the intake air. It is also protected from being attacked. The outlet of the bypass metal passage 22 is opened near the narrowest part of the bench cutter, and the inlet thereof is opened on the upstream side of the pliers.

The injector 12 is constantly supplied with pressurized fuel from the fuel tank 30 via the fuel pump 32.
When an injection signal from the control circuit 60 is applied to the injector 12, fuel is injected from the injector 12 into the intake pipe 6.

The air-fuel mixture taken in from the intake valve 20 is compressed by the piston 50 and combusted by a spark from an ignition plug (not shown) K, and this combustion is converted into interlocking energy.

The cylinder 8 is cooled by cooling water 54. The temperature of this water is measured by a water temperature sensor 56, and this measured value T
W is used as engine temperature.

An Ot sensor 142 is provided in the exhaust gas ii'lO, which measures the presence or absence of Ol in the exhaust gas and outputs a measured value λ.

Further, a crank angle sensor (not shown) is provided on the crankshaft, which outputs a reference angle signal and a position signal at each reference crank angle and at each fixed angle (for example, 0.5 degrees) according to the rotation of the engine.

The output of this crank angle sensor, the output signal TW of the water temperature sensor 56, 0. Output signal λ of sensor 142 and heating element 24
The electric signal AF from the injector 12 and the ignition coil are driven by the output of a control circuit 60 consisting of a microcomputer, computer, etc.

Further, the throttle chamber 4 is provided with a bypass 26 that straddles the throttle valve 14 and communicates with the intake air 11ir6, and this bypass 26 has a bypass pulp 61 that is controlled to open and close.
is provided.

This bypass pulp 61 is made to face the bypass 26 provided by bypassing the seal valve 14, and is controlled to open and close by pulse current, and the cross-sectional area of the bypass 26 is changed by the lift lid. The drive section is driven and controlled by the output of the control circuit 60. That is, the control circuit 60 generates an opening/closing periodic signal to control the driving section, and the driving section adjusts the lift amount of the bypass pulp 61 based on this opening/closing periodic signal.

The HG control valve 90 controls the passage between the exhaust pipe 10 and the intake pipe 6, and the EG ratio from the exhaust pipe IO to the intake pipe 6 is controlled.

Therefore, the injector 1zt-Tsukuda+m shown in Fig. 1 is used to control the air-fuel ratio (A/F) and fuel increase control, and the bypass pulp 61 and injector 12 are used to control the engine speed at idle (I8C). .

In addition, it is possible to control HGRili.

FIG. 2 is an overall configuration diagram of the control circuit 60 using a microcomputer, which includes a central processing unit 102 (hereinafter referred to as CPU) and a read-only memory 104 (
(hereinafter referred to as ROM) and random access memory 10
6 (hereinafter referred to as RAM) and an input/output circuit 108. The CPU 102 controls the input/output circuit 108 according to various programs stored in the OM 104.
It calculates the input data from and sends the result of the calculation to the input/output circuit 108 again. The intermediate storage required for these operations uses RAM 106. CPU 102. HOM
104. BAMl'06. Transfer of various data between the input/output circuits 108 is performed by a path line 110 consisting of a data bus, a control bus, and an address bus.

The input/output circuit 108 includes a first analog/digital converter 122 (hereinafter referred to as At) C1) and a second analog/digital φ converter 124 (hereinafter referred to as ADC).
2), an angle signal processing circuit 126, and a discrete input/output circuit 128 (hereinafter referred to as DIO) for inputting and outputting 1-bit information.

The ADC1 has a battery voltage detection sensor 132 (hereinafter ■B
(hereinafter referred to as TWS) and cooling water temperature sensor 56 (hereinafter referred to as TWS)
, the atmospheric temperature sensor 136 (hereinafter referred to as TAS), the adjustment generator 138 (hereinafter referred to as ■几S), the throttle sensor 140 (hereinafter referred to as 0TH8), and the 0. Sensor 142 (
Below 0. The output from the multiplexer 16 (denoted as S)
2 (hereinafter referred to as MPX), and MPX 162 selects one of these to perform analog/digital
The signal is input to a conversion circuit 164 (hereinafter referred to as ADC). A.D.
The digital value that is the output of C164 is stored in register 166 (
(hereinafter referred to as kLEG).

In addition, the flow rate sensor 24 (hereinafter referred to as AFS) is the ADC2.
124, is digitally converted via an analog/digital conversion circuit 172 (hereinafter referred to as ADC), and is set in a register 174 (hereinafter referred to as EG).

The angle sensor 146 (hereinafter referred to as ANGLS) outputs a signal indicating a reference crank angle, for example, 180 crank angle (hereinafter referred to as kLEF), and a signal indicating a minute angle, for example, 1 degree crank angle (hereinafter referred to as PO8). The signal is then applied to the angle signal processing circuit 126, where the waveform is shaped.

DIO(128)K is an idle switch 148, (hereinafter referred to as I
DLE-8W) and top gear switch 150
(hereinafter referred to as TOP-8W) and starter command switch 15
2 (hereinafter referred to as 8TART-8W) is input.

Next, a pulse output circuit and a controlled object based on the calculation results of the CPU will be explained. Injector control circuit 1134
(hereinafter referred to as INJC) is a circuit that converts the digital value of the calculation result into a pulse output. Therefore, the pulse INJ having a pulse width corresponding to the fuel injection amount is 1NJc113
4 and is applied to the injector 12 via an AND gate 1136.

The ignition pulse generation circuit 1138 (hereinafter referred to as IGNc) is a register (hereinafter referred to as ALIV) for setting the ignition timing.
and a register (hereinafter referred to as DWL) for setting the primary current supply start time of the ignition coil, and these data are set by the CPU.

Generates a pulse IGN based on the set data,
A to amplifier 62 for supplying primary current to the ignition coil
This pulse IGN is applied via ND gate 1140.

The opening rate of the bypass valve 61 is controlled by a control circuit (hereinafter referred to as ISC).
It is controlled by a pulse ISC applied from 1142 (denoted C) to 1144 (AND gate) 1144. 1sc
The c1142 has a register l5CD for setting the pulse width and a register l8CP for setting the pulse period.

EG)1 controlling the control valve 90 EG)1. [Control pulse generation circuit 1178 (hereinafter referred to as EG) EC] K is a register wa that sets a value representing the duty of the pulse.
It has a register HGRP for setting kLo and a value representing the pulse period. EGRC output pulse E with
GR is connected to transistor 90 via AND gate 1156.
added to.

In addition, the input/output signal of the bit is connected to the circuit DIO (128).
controlled by As an input signal, LR-8W
A is number, 5TART-8W signal, T.

There is a P-8W signal. Further, as the output signal, there is a pulse output signal for driving the fuel pump to km.

This DIO is provided with a register DD 14192 for determining whether a terminal is used as an input terminal, and a register υ0UT 194 for latching output data.

The mode register 1160 is a register (hereinafter referred to as MOI) that holds instructions for commanding various states inside the input/output circuit 108.
)), for example, this mode register 1160
AND gate 1136,1 by setting the instruction to
140, 1144, and 1156 are all activated and inactivated. In this way, instructions are set in the KMOD register 1160 - K, INJC, 1GNC.

It is possible to control the stop and start of the l5CC output.

A signal LJIOI for controlling the fuel pump 32 is output to DIO (128).

Therefore, by applying this type of EEC, almost all controls related to internal combustion engines such as A/F control can be properly performed, and it is possible to fully meet the strict exhaust gas regulations for automobiles, while also achieving excellent fuel efficiency. You can get the engine.

By the way, in controlling A/F' in such EEC, control data for the injector 12 is obtained from data AF24 representing the intake air amount and engine rotation speed data N, and the result is set to 0. It is well known that data from the sensor 142 is corrected using shift feedback control to obtain a predetermined A/F.According to the control technology of this building, variations in mechanical parts, sensors and actuators, Even if the injection pulse deviates from the value that provides the optimum air-fuel ratio due to changes over time or environmental changes, the concentration of the specific component in the exhaust gas will be 0! Since the injection pulse is detected by the sensor 142 and feedback correction is performed according to the detected value, the injection pulse is always controlled to the optimum value.

However, such control works effectively when the engine operating condition is steady or changing slowly, but in transient operating conditions where the engine operating condition changes suddenly, the air-fuel ratio Since the feedback correction cannot follow the operating conditions, the air-fuel ratio state of the engine deviates significantly from the optimum value. For this reason, the purification efficiency of the catalytic converter, which is used to reduce harmful components in exhaust gas, is significantly deteriorated.

On the other hand, rod learning control has been proposed as a method for optimizing the injection pulse when the desired fuel-fuel ratio deviates significantly. As an example of learning control, Japanese Patent Application Laid-Open No. 57-26229
There is a publication. According to this method, the average value of the air-fuel ratio correction coefficient determined by the concentration of a specific component in exhaust gas when the engine is in an idling operating state is determined, and the average value falls within a predetermined range. The Fujisashi Ine positive amount is determined by learning control as shown in FIG. The learning control is used to request an error correction amount such that the value falls within a predetermined range, and the component that fluctuates depending on the rotational speed is determined from the error correction amounts for each of the idle and non-idle states as a function of the rotational speed, and the overall calculation is performed. The amount of error correction is determined.

However, this type of method has problems such as an increase in the amount of programs due to the difference between idle and non-idle processing, convergence of the error correction amount by learning control, and unambiguousness of the correction amount depending on the rotation speed. As mentioned above, it is not possible to correct a transient state in which the engine load state suddenly changes.

As described above, all conventional total fuel ratio control methods are unable to sufficiently suppress the deterioration of exhaust gas during transient operating conditions where engine operating conditions change rapidly. This has the drawback that it generates harmful components and tends to cause deterioration of exhaust gas.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art mentioned above, to sufficiently suppress deterioration of exhaust gases even when the continuous rotation state of the engine changes rapidly and to perform sudden deceleration operation, and to constantly reduce exhaust gas emissions. An object of the present invention is to provide an air-fuel ratio control method that can maintain a good condition of the air-fuel ratio.

[Summary of the invention]

In order to achieve this objective, the present invention is designed to learn when feedback correction continues for a certain period of time and when the address determined by the engine speed and load does not change in the entire range where feedback correction is performed based on the performance of specific components in exhaust gas. Steady-state learning is performed such that load fluctuations are treated as changes in the basic fuel injection time, and the extreme value of the subsequent air-fuel ratio correction coefficient is stored as the transient learning correction amount at the time of basic fuel injection, and the change in the basic fuel injection time is The percentage difference is that the amount of injected fuel is reduced to take into account mechanical engineering and fuel adhesion to the wall during sudden deceleration when the change is sudden and the absolute value of the basic fuel injection time is smaller than the basic fuel injection time in the idle state. There is.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, the air-fuel ratio control method according to the present invention will be explained in detail with reference to the illustrated embodiments. The hardware configuration of an embodiment of the present invention is the same as the conventional HEC described in FIGS. 1 and 2, but the control operation by the control circuit 60 including a microcomputer is different.
Some of the programs stored in the computer are different.

First, in the EEC shown in FIGS. 1 and 2, the fuel injection by the injector 12 is periodically performed intermittently in synchronization with the rotation of the engine, and the fuel injection amount is controlled only once.
This is done by controlling the valve opening time of the injector 12 and the toe box injection time TI during each injection operation.

Therefore, in one embodiment of the present invention, this injection time T1 is determined as follows.

T+=α・Tp ・(Kz+Kt −Ks ) ・(1
+ΣKI)・Concave curve (1) where, k: Coefficient determined by the injector Tp: Basic fuel injection time α: Air-fuel ratio correction coefficient Kt: Steady learning coefficient Kt: Transient learning coefficient 1: Various correction coefficients Ks: Shift coefficient Ql : Intake air flow rate N: Engine rotation speed, that is, the engine intake air flow rate Q, and the rotation speed N, determine the basic fuel injection time l1lp using equation (2), and roughly calculate the stoichiometric air-fuel ratio (k/F = 14.7). and 0. The air-fuel ratio correction coefficient α is changed by the signal λ of the sensor 142 to correct the fuel ratio by feedback, and after obtaining a more accurate stoichiometric air-fuel ratio, the steady learning correction amount is used to adjust the air-fuel ratio control. K to compensate for variations in the characteristics of various actuators and sensors and changes over time, and also to compensate for acceleration and deceleration using the transient learning coefficient KtK.
The fuel injection time TI is determined by subtracting the shift coefficient during sudden deceleration.

First, the learning coefficient Kt will be explained. 0. sensor 14
2 outputs a binary signal (high, low level voltage) depending on the presence or absence of oxygen in the exhaust gas. It is well known that the air-fuel ratio correction coefficient α is increased or decreased in steps based on this binary signal, and then the air-fuel ratio is controlled by gradually increasing or decreasing it. 0. FIG. 3 shows the state of the air-fuel ratio correction coefficient α which detects whether the air-fuel ratio is rich or partially rich based on the sensor output signal λ.

Here, 0. The air-fuel ratio correction coefficient α when the sensor signal is reversed is the lean to rich extreme value αrnax.

Let αmln be the extreme value of a part of Rich Karari, and its average value α
ave is calculated using the following formula.

The idea of this average value is well known, but in this example, the average value αawe is the upper limit value (T, U, L) and the lower limit value (T,
L, L), the average value αaVe and 1.
The deviation Kt of 0 is taken as the steady learning correction amount. The calculation of this steady learning correction amount Kt is 0. Feedback correction by the sensor is performed in all areas.

FIG. 4 shows a table for writing one steady learning correction amount Ktt. In this table, Kt is written at division points determined by the basic fuel injection time Tp and the engine speed N. This learning timing is when the dividing point does not change and the number of extreme values reaches one. The table shown in FIG. 4 is defined as a steady learning map. In practical terms, it is almost impossible for this steady learning map to fill in all the division points (64 points in this case) through learning. For this reason,
Unlearned division points must be created by referring to learned division points.

Therefore, next, this method of creation will be explained.

FIG. 5 shows an example of a buffer map and a comparison map, which are used to create a steady learning map and have the same number of points as the division points of the steady learning map.

FIG. 6 shows a block diagram of a routine for creating a steady learning map. In (1), the steady learning map and comparison map are all cleared, and the steady learning correction amount is written to the buffer map. However, at this point; double 1F keys are not included in the buffer map. In (2), when the number of writes in the buffer map becomes 0, transfer the contents of the buffer map to the comparison map, and in (3), refer to the 0 contents committed to the buffer map, Create all buffer maps and transfer their contents to the steady learning map.

In (4), the contents of the comparison map are retransferred to the buffer map. From this point on, the KtO value is used to calculate the fuel injection time. Up to this point, Kt in equation (1) is 1.0
It is. In (5), the steady learning correction amount is added to both the steady learning map and the buffer map, and the air-fuel ratio correction coefficient α is set to 1.0, and the contents of the buffer map and the comparison map are compared. When the number of differences in the content becomes a certain number, the routines from (2) to (4) are repeated in (6).

According to this embodiment, since the steady-state learning correction Kt stores the deviation from 1.0, the air-fuel ratio correction coefficient α can be controlled around 1.0 with - times of correction, and the harmful exhaust gas Components can be reduced.

Also, in the steady learning map shown in Fig. 4, the basic fuel injection time Ill, ? or more and engine speed N? In the above example, map 1 in the rightmost column and bottom row is used, so that correction can be made to always provide the optimum power even in the power domain.

Next, an example of a learning routine for the constant voltage learning coefficient Kz will be described with reference to flowcharts shown in FIGS. 7 and 8.

The process according to this flowchart is repeated at a predetermined cycle after starting the process, and first, at step 300, the
．． It is determined whether or not feedback control is being performed, and if the result is Yes, the process proceeds to step 302. The result is NO
If so, proceed to step 332. In step 302 %
U! The sensor signal is λ = 1 (stoichiometric air-fuel ratio A/1” =
14.7)) is crossed. The result is no
In this case, the program proceeds to step 332 and performs well-known integration processing (not shown). If the result is Yes, proceed to step 3041c and (3) calculate the average value α8mae shown in 2. In step 306, it is determined whether the average value αawe is within the upper and lower limits shown in FIG. Clear and proceed to step 332. On the other hand, if the average value αeve is outside the upper and lower limits, in step 308, the difference between the average value αaVe and 1 is set as the steady learning correction amount Kt.

Next, in step 310, the current dividing point determined from the basic fuel injection time Tp and engine speed N shown in FIG. 4 is calculated, and in step 312, it is compared with the dividing point one time before this routine. Then, it is determined whether the dividing point has changed. If the dividing point has changed (Yes), the dividing point at which the steady learning correction amount Kt is written has not been determined, and the process proceeds to step 326. If the dividing point has not changed, the counter is incremented in step 314, and it is determined in step 316 whether the counter has reached n. Counter value is n
If not (No), proceed to step 332. When the counter value reaches n (Yes), the counter is cleared in step 318 and the process proceeds to step 320.

In step 320, steps (2) to (4) explained in FIG.
), it is determined whether the first generation of the steady learning map has been performed. If the map has not yet been created, the process proceeds to step 322 and subsequent steps, and the operation (1) described in FIG. 6 is performed. In step 322, it is determined whether the division point has already been written. If you are already in it (Y
es), do nothing and proceed to step 332. If the result is NO, in step 324, the steady learning correction amount KL calculated in step 308 is added to the dividing point. Step 3
If you have created the first steady learning map in step 20 (Ye
s), the process proceeds to step 328 and subsequent steps, and operations (5) and (6) explained in FIG. 6 are performed. In step 328, the learning curve 1 is added to the dividing point of the steady learning map and the buffer map.
Add liiiKt. Then, in step 330, the air-fuel ratio coefficient is set to 1.0.

Therefore, by repeating the processing according to these steps 300 to 332, the !, 4t1 product of (1) (e (6)) explained in FIG. 6 was obtained.
Become.

Next, using the flowchart in Figure 8, we explained to the 6th ward (
2) Explain the operations of (3) and (4)1.

At step 350, it is determined whether the first steady learning map has been created. If it has not been created yet (No).

Proceeding to step 354, the number of buffer maps loaded is checked. When the number becomes m traps, step 3
Proceed to step 56, but if m has not yet been reached, proceed to step 37
Heading towards 0. If the first steady learning map is created in step 350 (Yes), then in step 352 the difference in data between the buffer map and the comparison map is checked. If there is one difference in content between the buffer map and the comparison map, the process proceeds to step 356, where a steady learning map is created. If there is no difference in the internal medicine, step 3
Heading towards 70.

At step 356, a map creation flag is set;
Prohibit writing learning results. In step 358, internal medicine in the buffer map is transferred to the comparison map, and in step 3
At 60, a steady learning map is created using the buffer map. In step 362, the contents of the created buffer map are transferred to the steady learning map, and in step 364, the contents of the comparison map are transferred to the buffer map. At step 366, a flag indicating that a steady learning map has been created is set. This flag is & used for determination in step 350 and step 320 in FIG.

In step 368, the map creation flag set in step 356 is reset.

Next, FIG. 9 shows the basic fuel injection time ip and the air-fuel ratio correction coefficient α in a transient state.

Changes in the transient state can be known from the amount of change Δl1lp in the basic fuel injection time ip over time. During the acceleration period when ΔTp is increasing and the deceleration period when it is decreasing, the air-fuel ratio integrity coefficient α shows extreme values a, Jf, and b. These extreme values a and b exceed the upper limit values (K, U, L). Tashi, lower limit value (
K.1. ．． 1. ) The difference Kacc and Kd e when
Let c be the transient learning correction amount, and the acceleration learning correction amount K a cc
, deceleration i/correction amount Kdec. Each of these correction amounts is enriched in the acceleration learning map and the deceleration learning map.

Fig. 1θ and Fig. 11 show an acceleration learning map and a deceleration learning map. These maps are maps consisting of the basic fuel injection time change ΔTp and the engine speed, and the dividing point is calculated from the engine speed N at the time when the maximum change Δl1lp in acceleration and deceleration period per hour is detected. is calculated, and the correction amounts Kacc and Kdee at the subsequent extreme values are written at the division points.

Next, an example of transient learning will be explained using a flowchart.

In step 400, 0. Determine whether feedback control is in progress. If it is not under control, proceed to step 424. If the control is in progress, select step 402, check whether the 02 sensor has reversed or not, and if it has just been reversed, select step 404KM.
nothing. If it is not immediately after the reversal, head to Mechitsubu 424. At step 404, acceleration or deceleration is checked. Acceleration/deceleration is checked by looking at the fluctuation of the basic fuel injection time ip per certain time. If it is not acceleration/deceleration, the process proceeds to step 424.

If it is acceleration/deceleration, proceed to step 406. In step 406, a steady learning map is created and it is determined whether it is in use. If the steady learning map has not been created, the process advances to step 424. If the steady learning map is in a use permitted state, the process advances to step 408.

In step 408, it is determined whether or not the total fuel ratio bucket positive constant α has the upper and lower limit internal pressure values shown in FIG. - If it is within the upper and lower limits, the process proceeds to step 424. If the result is No, the process advances to step 410. In step 410, if the air-fuel proportionality positive coefficient α is above the upper limit value (m, u, h), if the result in step 412 is NO, the process proceeds to step 414, and the learned correction amount Δα of acceleration/deceleration, respectively. Calculate. In step 416, a division point is calculated based on the engine rotational speed at the time when acceleration/deceleration is detected and the change ΔTp in the basic fuel injection time at that time. In step 418, it is determined whether the detected acceleration or deceleration is acceleration or deceleration, and if acceleration is detected, step 4
At step 20, the acceleration learning correction amount Δα is added to the acceleration learning map, and if it is deceleration, the deceleration learning correction amount Δα is added to the deceleration learning map at step 422.

FIG. 13 shows the relationship between the basic fuel injection time and each correction according to the present invention. A is steady learning, B is accelerated learning.

C shows each region 7 of deceleration learning. D indicates a region where 3 acts on the shift coefficient expressed by equation (1).

A flowchart relating to this shift coefficient Ks is shown in FIG. In step 600, step 366 of FIG.
Check whether the creation of the steady learning map is complete using the map creation flag set in .

If the creation is completed, the process advances to step 602; if the creation is incomplete, the process advances to step 616. In step 602, if the current basic fuel injection time is smaller than the basic fuel injection time at idle, the process proceeds to step 604, and the air-fuel ratio correction coefficient α is set to 1.
．． Set to 0. In step 606, the set state of the lean shift flag is checked, and if it is not set, the lean shift time is set in step 608, and the lean shift flag is set in step 610. Step 6
In step 12, it is checked whether the time set in step 608 has become zero, and if it is not zero, in step 614,
Set the lean shift work to 8. As a result, the basic fuel injection time becomes thinner by Ks during the lean shift time during the period (shown in the DC1413 diagram) in which the basic fuel injection time is smaller than the basic fuel injection time during idling.

In step 616, the lean shift flag is reset, and in step 618, the lean shift work is set to zero.

Here, the lean shift time is updated in a separate task (not shown).

Therefore, according to this embodiment, the basic fuel injection time Tp is the basic fuel injection time in the idle state (idle Ill,
) only when the shift coefficient is smaller than
acts, and according to equation (1), the firing time Ti is further reduced by /J%
Work to improve. And with this.

This prevents the concentration of A/F caused by fuel adhering to the inner wall of the intake pipe and being sucked into the cylinder in large numbers during rapid deceleration, making it possible to keep the harmful components in the exhaust gas within regulations.

Here, the magnitude of the shift coefficient Ks may be proportional to the amount of change in the basic fuel injection time during sudden deceleration or the air-fuel ratio correction coefficient.

In addition, if the shift coefficient is only air-fuel ratio feedback control without learning control, even if the air-fuel ratio correction coefficient is fixed at its current value and the shift coefficient is set during sudden deceleration, harmful components of exhaust gas will not be removed. can do.

Further, in the embodiment described above, whether or not it is a sudden deceleration is determined based on the basic fuel injection time, but it can also be determined using a value obtained by dividing the intake pipe negative pressure value or the throttle angle by the engine rotation speed.

FIG. 15 is a flowchart in which a shift coefficient of 3 can be requested for learning during sudden deceleration. Step 700 and step 702 are equivalent to step 600 and step 6 in FIG.
This is the same process as 02. In step 704, the set state of the lean shift flag is checked, and if it is not set, the lean shift time is set in step 706, and the lean shift flag is set in step 708. In step 710, it is checked whether the air-fuel ratio correction coefficient is within the upper or lower limit values, and if it is within the upper or lower limit values, the process proceeds to step 718.

If the air-fuel ratio correction coefficient is not within the upper or lower limit values, the process proceeds to step 712, and if the air-fuel ratio correction coefficient is greater than or equal to the upper limit value, the process proceeds to step 714. If the air-fuel ratio correction coefficient is below the lower limit, step 7
Proceed to step 16. In step 714, the air-fuel ratio correction coefficient and 1
．． Add the difference of 0 to the lean shift memory, step 71
In step 6, the difference between the air-fuel ratio correction coefficient and 1.0 is subtracted from the lean shift memory, and the value of G is stored in the lean shift memory. In step 718, if the lean shift time is not zero, in step 720, steps 714 and 716 are
Calculate or store the value in the lean shift memory in the lean shift work. In step 722, the one-shift flag that was set in step 708 is reset.

In step 724, the lean shift work is made zero.

As a result, compensation for sudden deceleration can be performed using a shift coefficient of 3 determined by learning.

Note that the fuel injection time # can be calculated by referring to the lean shift work.

As a result of the above, in this embodiment, in addition to a series of steady learning and transient learning in air-fuel ratio control, correction for sudden deceleration (correction by shift coefficient KsK) is applied, so sudden deceleration It is possible to sufficiently suppress the generation of harmful components that appear in the form of spikes in exhaust gas when the air-fuel ratio is controlled. Since the operating conditions can be corrected at the same time, it is not only possible to remove harmful components of exhaust gas, but also to eliminate variations in sensors and actuators and aging effects even in the power range where air-fuel ratio feedback control is not performed. Since the correction is performed using a steady learning map, it is possible to easily provide an air-fuel ratio control method for an internal combustion engine that can always make optimum power correction.

Further, since the steady state learning correction amount in a stable state is calculated by counting the number of inversions of the air-fuel ratio correction coefficient, taking into account that the division points of the steady state learning map do not change, a reliable steady state learning map can be obtained.

After creating the steady-state learning map, the transient learning map uses p and changes in the air-fuel ratio correction coefficient α during acceleration and deceleration as the learning correction amount, so fluctuations in the air-fuel ratio are suppressed even in transient states, and harmful components of exhaust gas can be removed and drivability can be improved.

〔Effect of the invention〕

As explained above, according to the present invention, even when the engine is operated at rapid deceleration, the state of exhaust gas can be suppressed to a light fraction, thereby eliminating the drawbacks of the conventional technology and maintaining the exhaust gas in a good condition at all times. It is possible to easily provide an air-fuel ratio control method that can control the air-fuel ratio.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of an electronic engine control device, FIG. 2 is a block diagram showing an example of a control circuit, FIG. 3 is an explanatory diagram of the operation of the air-fuel ratio correction coefficient in a steady learning state, and FIG.
Figure 5 is a configuration diagram showing an embodiment of the steady learning map in the present invention, Figure 5 is a layout diagram showing an embodiment of the steady learning map, buffer, and relative soft mag in the present invention, and Figure m6 is an embodiment of the steady learning map in the present invention. An explanatory diagram of the creation status of each map in the example,
7 and 8 are flowcharts for explaining the air-fuel ratio control operation in a steady learning state according to an embodiment of the present invention, and FIG. 9 is an explanatory diagram of the learning operation according to an embodiment of the present invention during acceleration and deceleration. 10 and 11 are configuration diagrams showing an embodiment of the acceleration/deceleration learning map according to the present invention, FIG. 12 is a flowchart explaining the transient learning control processing operation according to the embodiment of the present invention), and FIG. 14 is an explanatory diagram of the transient learning operation in an embodiment of the present invention, FIG. 14 is a freechart showing the control operation using a shift coefficient in an embodiment of the present invention, and FIG. 15 is an illustration of the shift coefficient in the present invention. 3 is a flowchart illustrating an example of a learning operation. 12... Injector (fuel injection valve), 24.
...Intake air flow rate sensor, 56...Cooling water temperature sensor. 142...0. sensor. Figure 1 Figure 2 Figure 3 Yu Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 bTp Figure 12 Figure 13 - One hour Figure 14

Claims (1)

[Claims] 1. A basic value of the amount of fuel supplied by the fuel injection valve is calculated according to the intake air amount among the operating conditions of the internal combustion engine, and the basic value is corrected according to other operating conditions. In this air-fuel ratio control method, a correction means is provided that operates only when the basic value becomes equal to or less than the basic value of the fuel supply amount when the internal combustion engine is in an idling state, and the correction operation by this correction means adjusts the basic value at this time. An air-fuel ratio control method that is configured to perform a multiplication operation by a coefficient that takes a value of 1 or less. 2. An air-fuel ratio control method according to claim 1, characterized in that the coefficient taking a value of 1 or less is determined by learning based on air-fuel ratio correction during deceleration of the internal combustion engine. .