JPS6353366B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fuel supply amount control device for an internal combustion engine such as a gasoline engine. The present invention relates to an air-fuel ratio control device that can always obtain standard characteristics without requiring special adjustment.

[Background of the invention]

As interest in environmental conservation through the prevention of air pollution and the depletion of energy resources increases, control devices are designed to comprehensively control the operating conditions of automobile gasoline engines to improve exhaust gas conditions and improve the fuel ratio. has become desirable, and therefore,
Using a microcomputer, a cooling water temperature sensor and an O ₂ sensor that provides the oxygen concentration in exhaust gas
The engine is always operated optimally by taking in signals from sensors and other sensors that provide various data that represent the operating status of the engine, and controlling various aspects such as fuel supply amount, ignition timing, idle speed, and exhaust gas recirculation amount. Electronic engine control equipment (hereinafter referred to as EEC), which allows engine status information to be obtained, has come into use.

An example of a system in which such EEC is applied to a fuel injection type internal combustion engine is proposed in Japanese Patent Application Laid-open No. 134721/1983, 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 passes through an air cleaner 2, a throttle chamber 4, an intake pipe 6, and is supplied into a 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, and the fuel injected from the injector 12 is atomized within the air passage of the throttle chamber 4 and mixed with intake air. A mixture is formed, and this mixture is supplied to the combustion chamber of the cylinder 8 through the intake pipe 6 when the intake valve 20 is opened.

A throttle valve 14 is provided near the outlet of the injector 12. The throttle valve 14 is configured to be mechanically interlocked with the accelerator pedal and is driven by the driver.

An air passage 22 is provided upstream of the throttle valve 14 of the throttle chamber 4, and a hot wire air flow meter made of an electric heating element, that is, a flow rate sensor 24 is disposed in this air passage 22, and the air passage 22 is arranged to measure the air flow rate. An electrical signal AF that changes according to the air flow velocity determined from the relationship with the amount of heat transfer of the heating element is extracted. Since the flow rate sensor 24 made of this heating element (hot wire) is installed in the bypass air passage 22, it is protected from high-temperature gas generated when the cylinder 8 backfires, and is not contaminated by dust in the intake air. It is also protected from. The outlet of this bypass air passage 22 is opened near the narrowest part of the bench lily, and the inlet thereof is opened on the upstream side of the bench lily.

The injector 12 is constantly supplied with pressurized fuel from the fuel tank 30 via the fuel pump 32, and when an injection signal from the control circuit 60 is given to the injector 12, the injector 12
2, fuel is injected into the suction pipe 6.

The air-fuel mixture taken in from the intake valve 20 is transferred to the piston 5.
0 and the spark plug (not shown)
The spark generated by the fuel causes combustion, and this combustion is converted into kinetic energy. The cylinder 8 is cooled by cooling water 54, and the temperature of this cooling water is measured by a water temperature sensor 5.
6, and this measured value TW is used as the engine temperature.

The exhaust pipe 10 is provided with an O ₂ sensor 142,
Measures the O ₂ concentration in the exhaust gas and outputs the measured value λ.

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

The output of this crank angle sensor, water temperature sensor 56
The output signal TW of the O ₂ sensor 142, the output signal λ of the O 2 sensor 142, and the electric signal AF from the heating element 24 are inputted to a control circuit 60 consisting of a microcomputer, etc., and are subjected to calculation processing. and the ignition coil is driven.

Furthermore, the throttle chamber 4 includes a throttle valve 14.
A bypass 26 is provided that straddles the intake pipe 6 and communicates with the intake pipe 6, and this bypass 26 is provided with a bypass valve 61 that is controlled to open and close.

This bypass valve 61 faces the bypass 26 provided by bypassing the throttle valve 14, and is controlled to open and close by a pulse current, and the cross-sectional area of the bypass 26 is changed depending on the amount of lift. 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 for controlling the driving section, and the driving section adjusts the lift amount of the bypass valve 61 based on this opening/closing periodic signal.

The EGR control valve 90 controls the passage between the exhaust pipe 10 and the intake pipe 6, and controls the passage from the exhaust pipe 10 to the intake pipe 6.
EGR amount is controlled.

Therefore, the injector 12 shown in FIG. 1 is controlled to control the air-fuel ratio (A/F) and fuel increase control, and the bypass valve 61 and the injector 12 control the engine speed at idle (ISC).
Furthermore, by controlling the EGR control valve 90, the EGR amount can be controlled.

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), a read-only memory 104 (hereinafter referred to as ROM), and a random access memory 106 (hereinafter referred to as ROM). (hereinafter referred to as RAM) and an input/output circuit 108.
The CPU 102 calculates input data from the input/output circuit 108 using various programs stored in the ROM 104, and returns the calculation results to the input/output circuit 108 again. RAM 106 is used for intermediate storage necessary for these operations. CPU102,
ROM104, RAM106, input/output circuit 108
Various types of data are exchanged between them via a bus line 110 consisting of a data bus, a control bus, and an address bus.

The input/output circuit 108 includes a first analog-to-digital converter 122 (hereinafter referred to as ADC1).
and a second analog-to-digital converter 12
4 (hereinafter referred to as ADC2) and angle signal processing circuit 1
26 and a discrete input/output circuit 128 (hereinafter referred to as DIO) for inputting and outputting 1-bit information.

ADC1 has a battery voltage detection sensor 132
(hereinafter referred to as VBS) and cooling water temperature sensor 56 (hereinafter referred to as VBS)
(hereinafter referred to as TWS) and atmospheric temperature sensor 136 (hereinafter referred to as TAS)
), the adjustment voltage generator 138 (hereinafter referred to as VRS), and the throttle angle sensor 140 (hereinafter referred to as θTHS)
The outputs of the O ₂ sensor 142 (hereinafter referred to as O ₂ S) are added to the multiplexer 162 (hereinafter referred to as MPX), and the MPX 162 selects one of them and performs analog/digital conversion. The signal is input to a circuit 164 (hereinafter referred to as ADC). ADC1
The digital value that is the output of 64 is stored in register 166.
(hereinafter referred to as REG).

In addition, the negative pressure sensor 144 (hereinafter referred to as VCS)
It is input to the ADC2.124, converted to digital via the analog-to-digital conversion circuit 172 (hereinafter referred to as ADC), and converted into a register 124 (hereinafter referred to as ADC).
REG).

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

DIO 128 includes an idle switch 148 that operates when the throttle valve 14 returns to the fully closed position.
(hereinafter referred to as IDLE-SE), top gear switch 150 (hereinafter referred to as TOP-SW), and starter switch 152 (hereinafter referred to as START-SW)
is entered.

Flow rate sensor 24 (hereinafter referred to as AFS) is ADC2
is input to analog/digital/conversion circuit 1
72 (hereinafter referred to as ADC), it is digitally converted and set in a register 174 (hereinafter referred to as REG).

Next, the pulse output circuit and control target based on the calculation results of the CPU will be explained. The injector control circuit 1134 (denoted as INJC) is a circuit that converts the digital value of the calculation result into a pulse output. Therefore, a pulse INJ having a pulse width corresponding to the fuel injection amount is generated by the INJC 1134 and applied to the injector 12 via the AND gate 1136.

The ignition pulse generation circuit 1138 (hereinafter referred to as IGNC) has a register (hereinafter referred to as ADV) for setting the ignition timing and a register (hereinafter referred to as DWL) for setting the primary current energization start time of the ignition coil.
These data are set by the CPU. Generates a pulse IGN based on the set data,
Amplifier 6 for supplying primary current to the ignition coil
This pulse through AND gate 1140 to 2
Add IGN.

The opening rate of the bypass valve 61 is determined by the control circuit (hereinafter referred to as
ISCC) 1142 to AND gate 1144
is controlled by a pulse ISC applied via. ISCC 1142 has a register ISCD for setting the pulse width and a register ISCP for setting the repetition pulse period.

The EGR amount control pulse generation circuit 180 (hereinafter referred to as GRC) that controls the EGR control valve 90 has a register that sets a value representing the pulse duty.
It has EGRD and a register EGRP for setting a value representing the pulse repetition period. This EGRC
The output pulse EGR of is applied to transistor 90 via AND gate 1156.

Further, the 1-bit input/output signal is controlled by the circuit DIO128. IDLE-SW as input signal
signal, TOP-SW signal, and START-SW signal. Further, the output signal includes a pulse output signal for driving the fuel pump. This DIO has a register DDR192 for determining whether the terminal is used as an input terminal or an output terminal,
Register DOUT for latching output data
194 are provided.

The mode register 1160 is a register (hereinafter referred to as MOD) that holds instructions for commanding various states inside the input/output circuit 108. For example, by setting an instruction in the mode register 1160, the AND gates 1136, 1140, 1144,
All 1156 are activated or deactivated. Like this MOD register 11
By setting the command to 60, INJC and
You can control the stop and start of IGNC and ISCC output.

As mentioned above, DIO 128 is a 1-bit signal input/output circuit, and is a register (hereinafter referred to as DDR) 1 that holds data for determining input or output.
92 and a register 194 (hereinafter referred to as DOUT) for holding data to be output.
This DIO 128 outputs a signal DIO0 for controlling the fuel pump 32.

Therefore, if such EEC is applied, A/
Almost all controls related to the internal combustion engine, such as F control, can be appropriately performed, and it is possible to obtain an engine that satisfactorily satisfies strict exhaust gas regulations for automobiles and has an excellent fuel ratio.

By the way, in controlling the A/F in such an EEC, for example, data AF representing the amount of intake air is used.
and engine speed data N, injector 1
2 control data and send the results to the O ₂ sensor 14.
Corrected by feedback control using the data in 2.
Although a predetermined A/F is obtained, in an operating range where the O ₂ sensor 142 is not yet activated, such as immediately after the engine is started, correction by the above-mentioned feedback control cannot be performed, and the oven is turned off during this period. This results in a kind of prospective control state due to loop control.

In this state, if the characteristics of various actuators such as the injector 12 and various sensors such as the flow rate sensor 24 deviate from standard values, errors will occur in the A/F control at that time, and the required control result will be is not obtained.

On the other hand, variations inevitably exist in the characteristics of such actuators and sensors, and it is practically impossible to eliminate this variation.

For this reason, with the conventional A/F control method using EEC, there is a risk that the temperature of the O ₂ sensor may not reach a predetermined value immediately after the engine is started, and the correct A/F may not be obtained in the operating range where it is not activated. In order to prevent this, it is necessary to perform sufficient adjustment work, so-called tuning, in accordance with variations in the characteristics of these actuators and sensors prior to use of the system.

Further, the characteristics of such actuators and sensors are subject to so-called aging, and therefore, unless tuning is performed during use, sufficient A/F characteristics cannot be maintained.

Therefore, with conventional EEC-based A/F control devices, there is a risk that sufficient A/F control cannot be obtained in the operating range until the O ₂ sensor is activated, and to prevent this, tuning is often required. The disadvantage was that it was necessary to carry out

[Purpose of the invention]

An object of the present invention is to provide an A/F control device that eliminates the above-mentioned drawbacks of the prior art and allows sufficiently accurate A/F control in the O ₂ sensor inactive area without tuning. It is in.

[Summary of the invention]

In order to achieve this objective, the present invention calculates injector control data using basic data determined according to the engine load and a correction coefficient for the basic data, and uses this correction coefficient _as It is characterized by learning based on the feedback of the idle target rotation speed, and when the output of the O ₂ sensor becomes stuck at either lean or rich in the activation region, it is made to learn by escaping from this stuck state. .

[Embodiments of the invention]

Embodiments of the air-fuel ratio control device according to the present invention will be described below with reference to the drawings.

One embodiment of the present invention has the same hardware configuration as the conventional EEC explained in FIGS. 1 and 2,
However, the control operation by the control circuit 60 including a microcomputer is different, and therefore a part of the program stored in the ROM 104 is different.

First, in the EEC shown in Figures 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 by the valve opening time of the injector 12 in one injection operation, that is, the injection time T _i . This is done through control.

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

T _i =K〓・K _b・K _l・Q _A /N (1+ΣK _i )...(1) T _p =Q _A /N ...(2) Here, K〓: Air-fuel ratio coefficient K _b : Basic Coefficient K _l : Learning coefficient Q _A : Intake air flow rate N: Engine speed K: Various correction coefficients T _p : Basic fuel injection time In other words, the basic fuel injection time is determined from the engine intake air amount Q _A and the rotation speed N. Through this, the theoretical A/F (=14.7) can be roughly obtained,
The air-fuel ratio coefficient K is changed using the signal λ of the O ₂ sensor 142 to correct the A/F by feedback, and after obtaining more accurate A/F control, the basic coefficient K _b and the learning coefficient are _Kl is used to correct variations in characteristics of various actuators and sensors and changes over time. Here, the basic coefficient K _b is used to correct variations in characteristics of various actuators and sensors, that is, initial values, and the learning coefficient K _l is used to correct changes over time.

First, correction of the basic coefficient K _b will be explained.

In this embodiment, the O ₂ sensor 142 is not activated yet, such as during warm-up after starting the engine.
In the operating range where the signal λ representing the output A/F cannot be obtained, the basic coefficient K _b is changed so that the actual engine speed N converges to the idle target speed N _REF ,
As a result, even if there are variations in the characteristics of various actuators and sensors, the A/F does not deviate greatly from the theoretical A/F in the idle operation range where A/F feedback control cannot be performed, and furthermore, the A/F feedback After shifting to the current operating range, this basic coefficient K _b is further corrected when the output of the O ₂ sensor 142 is stuck in a lean or rich state. While the O ₂ sensor 142 is not activated, the idle target rotation speed N _REF is determined from the engine coolant temperature TW by table search as shown in FIG. 3, and compared with the actual engine rotation speed N. do. At this time, the air-fuel ratio coefficient K〓, the basic coefficient K _b , and the learning coefficient K _l are all
1.0, that is, (K = K _b = K _l = 1.0).

Now, for example, as shown in Fig. 4, if the actual rotation speed N is larger than the target rotation speed N _REF , the basic coefficient K _b is sequentially decreased in steps by a predetermined value ΔK _b each time. Then, find the basic coefficient K _b when N=N _REF is obtained and memorize it.
Thereafter, the injection time T _i is calculated as the basic coefficient K _b until the O ₂ sensor 142 is activated, and A/
Control F.

At this time, the opening degree of the bypass valve 61 is set such that when the injection time T _i is controlled in advance through experiments etc. so that the actual rotation speed N = target rotation speed N _REF is achieved, the output A/F≒ Set the value to obtain 14.7 (theoretical A/F).

Therefore, according to this embodiment, even if the characteristics of various actuators and sensors vary from standard values, there is no possibility that the A/F will deteriorate significantly in the operating range where A/F feedback control is not performed. .

Next, the O ₂ sensor (air-fuel ratio sensor) 142 is activated, and the basic coefficient K _b is reset in the operating region where the output A/F signal λ can be taken in and A/F feedback control is entered. I will explain about it.

In this operating range, even if there are variations in the characteristics of the actuator or sensor, as long as they are within a predetermined range, they are compensated for by feedback control, so the output A/F is always at the set value, e.g.
14.7 should converge to the theoretical A/F, but if the characteristics of the actuator or sensor vary from the standard value beyond the above-determined range, the value of the output signal λ of the O ₂ sensor 14 will become rich or lean. There is a possibility that the output A/F will remain stuck on one side, so-called sticking, and the feedback control for the output A/F may be stopped.

Therefore, in this embodiment, even when the output signal λ of the O ₂ sensor 142 becomes stuck, the basic coefficient K _b is rewritten to a value at which the sticking of the output signal λ of the O ₂ sensor 142 is canceled. The settings are reset, so that the operation shown in FIG. 5 is performed.

Before time t ₀₀ , the engine intake air flow rate Q _A
When _the basic fuel injection time T _p , which _is determined by The air-fuel ratio coefficient K〓 repeatedly increases and decreases depending on the leanness and richness of λ, and operates so that the average value of the output A/F is maintained at 14.7.

Next, at time t ₀₀ , the engine operating conditions are
For example, when the throttle opening or load torque changes, the basic fuel injection time T _p also changes, and as a result, if the basic coefficient K _b = 1.0, the air-fuel ratio coefficient will change.
Even if K〓 is changed to the maximum, the injection time
Suppose that it is no longer possible to return the output A/F to the theoretical A/F of 14.7 depending on T _i . For example, in FIG. 5, the output signal λ of the O ₂ sensor 142 becomes rich at time t ₀₀ , and thereafter, even if the air-fuel ratio coefficient K is set to the minimum limit L, the output signal λ remains rich.
It shows a state with a hem.

Therefore, when this state occurs, it is determined that the binding has occurred at time a at time t ₀₁ after a predetermined period of time, for example, 30 seconds has passed. However, since such stiffness may be temporary due to a change in the engine operating conditions that caused the change in the basic fuel injection time T _p , the basic coefficient should be corrected immediately at this point a. Instead of entering the equation, try returning the air-fuel ratio coefficient K to 1.0 at this point a. Then, if the sticking is temporary, the output signal λ starts to change at this point a, so that it is possible to proceed directly to A/F feedback control at this time.

On the other hand, if the sticking is not temporary, the output signal λ will remain rich (or lean) even after this point a, so that 30 seconds from the time t ₀₁ of this point a. It was determined that the jamming definitely occurred starting at time b at time t ₀₂ after 30 seconds had elapsed, and from time b onwards,
The basic coefficient K _b is corrected, and the basic coefficient K _b is successively changed (decreased in this case) by a predetermined value Δk _b in steps. At this time, the air-fuel ratio coefficient K is fixed at 1.0, and the O ₂ sensor 14
This is done while checking the output signal λ of step 2. In this way, the time when the amount of change (decrease value) of the basic coefficient K _b becomes k _b
When it is detected at t ₀₃ that the output signal λ has changed from the rich lean state to the lean state, the value of the basic coefficient K _b at this time is set as the new basic coefficient value, and the basic fuel injection time T _p at this time is set as the new basic coefficient value. with RAM106
to be memorized.

This process is repeated in the same way from time t ₁₁ to t ₁₂ every time burring occurs after time t ₁₀ , and each time,
If the newly set basic coefficient K _b is stored in the RAM 106 together with the basic fuel injection time T _p , the 6th
A table of the basic coefficient K _b for the basic fuel injection time T _p as shown in the figure is obtained, and once this tabulation is completed, the basic fuel injection time T _p
The basic coefficient K _b is searched by , and the injection time T _i is calculated.

Therefore, according to this embodiment, even if there are variations in the characteristics of various actuators and sensors, the predetermined basic coefficient K _b is automatically set accordingly.
Since variations in characteristics are absorbed and compensated for, accurate A/F feedback control is always possible and exhaust gas can be maintained in good condition.

Next, correction of the learning coefficient _Kl will be explained.

As mentioned above, this learning coefficient K _l changes over time in the characteristics of various actuators and sensors, and as a result, the output signal λ of the O ₂ sensor 142
This is to deal with the case where a gap occurs, and the operation to correct it is as shown in Figure 7, which is the same as the case of the basic coefficient K _b in Figure 5. A table shown in FIG. 8 is created to perform A/F feedback control. In addition, in this example, the learning coefficient K _l
The correction amount k _l is also tabulated.

Here, the reason why the basic coefficient K _b and the learning coefficient K _l are provided separately will be explained.

In the above embodiment, the tables shown in FIGS. 6 and 8 are written in the RAM 106, so the engine is stopped and the control circuit 60 is turned off.
, these tables will disappear.
Therefore, in this case, the basic coefficient K _b and the learning coefficient
There is no point in providing K _l independently, and it is sufficient to provide only the basic coefficient K _b .

However, as an embodiment of the present invention,
The table in Figure 6 was created once by using the RAM 106 as a non-volatile memory by battery backup and storing the tables in Figures 6 and 8 for a predetermined period of time. There is also one in which the basic coefficient K _b is not modified. In other words, in this embodiment, during an appropriate period from when the engine is first operated until the table shown in FIG. 6 is created,
Every time a deviation occurs in the output signal λ of the O ₂ sensor 142, only the basic coefficient K _b is corrected, and during this period, the learning coefficient K _l is not corrected and K _l is maintained at 1.0. After the above-mentioned appropriate period has elapsed, the basic coefficient K _b is not corrected, but only the learning coefficient K _l is corrected each time a deviation occurs, and only the table in Figure 8 is rewritten. We will continue to do so.

According to this embodiment, the basic coefficient K _b is an initial value corresponding to the initial characteristics of various actuators and sensors when they start being used, and the learning coefficient K _l is a value that changes over time depending on the characteristics that have changed up to that point. from,
By comparing these coefficients K _b and K _l , it is possible to know the state of change in the characteristics of various actuators and sensors, making it possible to predict their lifespans.

Next, an example of the setting routine for these basic coefficients K _b and learning coefficients K _l is shown in Figs. 9, 10, and 1.
This will be explained using the flowchart shown in FIG.

The process according to this flowchart is repeated at a predetermined period after the engine is started. First, in step 300, it is determined whether or not the air-fuel ratio sensor (O ₂ sensor 142) is activated, and the result is If NO, it is determined in step 302 whether the idle switch is ON or not. If the idle switch is in the idle state, the process proceeds to step 304, and if it is not in the idle state, the process proceeds to step 356. In step 304, a check is made to see if fuel is being increased in the fast idle state, and if fuel is being increased, step 356 is performed.
Proceed to. If the increase has been completed, proceed to step 306, check the flag and find the basic coefficient at idle.
It is determined whether or not the correction of K _b has been completed, and if it has been completed, the process proceeds to step 319, but if it has not been completed, the process proceeds to step 308, in which the current actual engine rotation speed N is changed to the idle target rotation speed N _REF (third Check whether the difference is within 150 rpm with respect to the figure).

When the result in step 308 is YES,
That is, when the speed is |N _REF -N|150 rpm, the routine proceeds from step 314 to step 316, where a flag indicating completion of setting of the basic coefficient K _b during idling is set, and this basic coefficient K _b is set for control purposes.

On the other hand, when the result in step 308 is NO, the process proceeds to step 310, where the relationship between the actual rotational speed N and the target rotational speed N _REF is checked, and the actual rotational speed N
is larger, the basic coefficient is set in step 312.
A predetermined value Δk _b is subtracted from K _b , and (K _b −Δk _b ) is set as a new coefficient K _b . If the result in step 310 is NO, that is, the actual rotational speed N is smaller, the process proceeds to step 318, where a predetermined value Δk _b is added to the basic coefficient K _b , and (K _b +Δk _b ) is calculated as a new coefficient K. Let it be _b . And these steps 316, 312,
After 318, the process advances to step 356 and exits from this flow.

Therefore, these steps 300 to 318
By repeating the process according to
The operation explained in the figure is obtained, and deterioration of the output A/F before the O ₂ sensor 142 is activated is prevented. Note that these steps 310, 312, 3
In the process at step 18, only when |N _REF -N| has become significantly large does step 312 or step 3
Instead of the predetermined value Δk _b in 18, twice this,
2Δk _b or 3Δk _b , which is three times the value, may be used. According to this embodiment, the time required to complete setting of the basic coefficient K _b can be shortened, and the control response speed can be increased. can do.

Next, when the result at step 300 or step 306 is YES, the process proceeds to step 319, where it is checked whether or not _O2 feedback is being performed, and when the result is NO, the process proceeds to step 356. On the other hand, step 3
If the result in step 19 is YES, proceed to step 320.
Next, it is checked whether the table creation for the basic fuel injection time T _p of the basic coefficient K _b explained in FIG. 6 has been completed. Note that this step 320
To make this determination, for example, a flag that is set when a predetermined time has elapsed after the engine was first started may be prepared and checked. Also, this is an example in which the RAM 106 is used as a non-luminous memory by battery backup, etc., and two types of coefficients, the basic coefficient K _b and the learning coefficient K _l , are used to _calculate the injection time T i. , and in an embodiment in which the RAM 106 is not a non-luminous memory and therefore only the basic coefficient K _b is used without using the learning coefficient K _l , step 320 of 2 is unnecessary. If the result of step 319 is YES, proceed directly to step 322.

Returning to step 320 in FIG. 9, if the result here is NO _, the process proceeds to the process of correcting the basic coefficient K _b in FIG.
It is determined whether or not learning is in progress, and if learning is in progress, the process directly advances to step 332. On the other hand, if learning is not in progress, proceed to step 324, and check whether the output signal λ of the air-fuel ratio sensor has reversed between lean and rich through the theoretical A/F point of 1, that is, 14.7. When a reversal is detected, the process passes through step 352 to clear the edge counter and exits to step 356. Further, if no reversal is detected, the process proceeds to step 326 and checks the hem counter, and depending on whether or not 30 seconds have elapsed, the occurrence of the hem is detected; if 30 seconds have not elapsed, the process proceeds to step 346. , it is determined whether the signal λ is rich or lean, and depending on the result, the process proceeds to either step 348 or 350. When the signal is rich, 1 is subtracted from the air-fuel ratio coefficient K〓, and when it is lean, the air-fuel ratio coefficient K〓 is reduced. Add 1. Therefore, this results in the operation between times t ₀₀ and t ₀₁ in FIG. 5.

On the other hand, if it is determined in step 326 that there is a burr, the process proceeds to step 328, where it is checked whether or not it is the first burr. If it is the first burr, the air-fuel ratio coefficient K is set to 1 via step 344. Therefore, the operation at point a (or point c) in FIG. 5 is obtained.

If the result in step 328 is NO, that is, it is determined that the second hemlock has occurred, step 3 is performed.
Proceed to step 30 to set the learning flag and the air-fuel ratio coefficient.
After processing to set K〓 to 1, step 33
2, and in this step 332 it is checked whether the state of heeling is on the rich side or not. If it is not rich, that is, lean, the process goes to step 334, where a predetermined value Δk _b is added to the basic coefficient K _b , and the other side is checked. , when it becomes rich, the basic coefficient is changed in step 336.
Subtract a predetermined value Δk _b from K _b . Then step 3
Step 38 checks whether the output signal λ has reversed between rich and lean, and if it has not reversed, step 3
However, when a reversal is detected, the process proceeds to step 340, where the basic fuel injection time at this time is determined.
Together with T _p , the basic coefficient K _b at this time is
Thereafter, the learning flag is reset through step 342, and then the process exits to step 356. Therefore, these steps 330 to 336
The operation from time t ₀₂ to t ₀₃ in FIG. 5 is obtained through the processing, and further, in step 340, the table shown in FIG. 6 is created.

At this time, it goes without saying that certain limits must be set for the maximum and minimum values of the basic coefficient _Kb .

Next, the process returns to step 320 in FIG. 9, and when the result here is YES, that is, it is determined that the table in FIG. 6 has been created, the process proceeds to the process in FIG. K _l correction processing is performed. However, since the processing routine of FIG. 11 merely replaces the basic coefficient K _b of the processing routine of FIG. 10 with the learning coefficient K _l ,
The explanation will be omitted.

Next, FIGS. 12 and 13 show the operation of another embodiment of the present invention, and this embodiment is the fifth embodiment.
What is different from the embodiments shown in _FIGS .
Keep K〓 unchanged and keep it at 1.0, and only when the occurrence of burr is confirmed, the air-fuel ratio coefficient K〓
The only point is that the amount is increased or decreased.

According to this embodiment, there are many lean-side states, so it is possible to obtain the effect that it greatly contributes to improving fuel efficiency.

In addition, in the above embodiment, the detection of the output A/F is
An air-fuel ratio sensor using an _O2 sensor is used, but
The present invention is not limited to this, and can be implemented, for example, by a lean sensor that detects that the output A/F is in a lean state, and similar effects can be obtained.

In addition, although the above embodiments have been described in the case where they are applied to a fuel injection type engine using the injector 12, it goes without saying that the present invention can also be applied to an electronically controlled carburetor type engine. Furthermore, the present invention can be implemented as a system that uses an intake negative pressure sensor instead of the flow rate sensor 24 to determine the basic fuel supply amount (corresponding to T _p ).

〔Effect of the invention〕

As explained above, according to the present invention, the A/F
Even if there are variations in the characteristics of the various actuators and sensors necessary for controlling the Except for the drawbacks, sufficiently good exhaust gas conditions can be obtained without any adjustment work even in the operating range where A/F feedback control is not performed, and the characteristics in the operating range where A/F feedback control is performed. It is possible to easily provide an air-fuel ratio control device for an internal combustion engine that can prevent the occurrence of control operation abnormalities due to changes in the temperature without requiring any adjustment work, and can always maintain a good exhaust gas condition.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram showing an example of an electronic engine control device, Fig. 2 is a block diagram of the control circuit, Fig. 3 is a characteristic diagram showing the relationship between target idle speed and engine cooling water temperature, and Fig. 4 is a diagram showing the relationship between target idle speed and engine cooling water temperature. Figure, Figure 5,
FIG. 6, FIG. 7, and FIG. 8 are operation explanatory diagrams of one embodiment of the air-fuel ratio control device according to the present invention, and FIG.
10 and 11 are flowcharts showing the control processing operation of one embodiment, and FIG. 12 and FIG.
FIG. 3 is an explanatory diagram of the operation of another embodiment of the present invention. 12... Injector (fuel injection valve) 24...
Intake air flow rate sensor, 56...Cooling water temperature sensor,
61...Bypass valve, 142...O ₂ sensor (air-fuel ratio sensor).

Claims (1)

[Claims] 1. The fuel supply amount is controlled based on the basic supply amount determined according to the operating conditions of the engine and a correction coefficient set in advance for the basic supply amount, and the air fuel supply amount is controlled based on the detection signal of the output air-fuel ratio sensor. In an air-fuel ratio control device of a type that performs feedback control of the fuel ratio, a learning control means for rewriting the correction coefficient is provided, and the learning control means is used to control the idle speed at the time before the output air-fuel ratio sensor is activated. When the numerical value corresponding to the amount of fuel supply necessary to keep the engine idle speed within the target idle speed can be calculated, and when the output of the output air-fuel ratio sensor remains in either a lean or rich state for a predetermined period of time or more. and a numerical value corresponding to the amount of fuel supplied necessary to reverse the output of the internal combustion engine, characterized in that when the numerical value corresponding to the amount of fuel supplied to reverse the output can be calculated, these numerical values are set as a new correction coefficient. Fuel ratio control device. 2. The air-fuel ratio control device according to claim 1, wherein the correction coefficient is composed of two types: a basic coefficient and a learning coefficient.