JPH0573909B2 - - Google Patents

Description

Detailed Description of the Invention <Field of Industrial Application> The present invention relates to an air-fuel ratio control device for an internal combustion engine having an electronically controlled fuel injection device with an air-fuel ratio feedback control function, and in particular to an air-fuel ratio control device for an internal combustion engine that has an electronically controlled fuel injection device with an air-fuel ratio feedback control function. Set the intake air flow rate based on the speed and
The present invention relates to a device configured to set a basic fuel injection amount based on this intake air flow rate.

<Prior art> As an electronically controlled fuel injection device configured to set the intake air flow rate based on the throttle valve opening and the engine speed, there are conventional electronically controlled fuel injection devices as shown below (Japanese Patent Application No. 1986- (See No. 008127, etc.)

That is, a throttle valve opening sensor that detects the opening degree α of a throttle valve installed in the intake passage of an internal combustion engine, and a rotational speed sensor such as a crank angle sensor that detects the engine rotational speed are provided. The detection signal is input to the control unit for fuel injection control.

The ROM of the microcomputer built into the control unit stores the intake air flow rate Q corresponding to each of multiple operating regions (areas) that are divided using the throttle valve opening α and the engine rotational speed N as parameters. data is stored,
Based on the detected values of the throttle valve opening α and the engine rotational speed N, data on the intake air flow rate Q in the corresponding operating region is examined from the data.

Then, the basic fuel injection amount Tp (=K×Q/N; K is a constant) is calculated based on the measured intake air flow rate Q and the engine rotation speed N detected by the rotation speed sensor, and Air-fuel ratio feedback that is set to bring the actual air-fuel ratio closer to the target air-fuel ratio based on various correction coefficients (COEF) depending on engine operating conditions such as engine cooling water temperature and signals from the _O2 sensor installed in the exhaust system. The correction coefficient LAMBDA and the correction amount Ts for correcting the change in the effective valve opening time of the injection valve due to the battery voltage are determined, and the basic fuel injection amount Tp is corrected using these to obtain the final fuel injection amount Ti (= Calculate Tp×COEF×LAMBDA+Ts).

In addition, the air-fuel ratio feedback correction coefficient
The deviation from the standard value of LAMBDA is learned for each area of the engine operating state in advance and the learning correction coefficient K _{MAP is calculated.}
is determined and included in the various correction coefficients COEF, so that the base air-fuel ratio obtained by the fuel injection amount Ti calculated without correction by the air-fuel ratio feedback correction coefficient LAMBDA matches the target air-fuel ratio, and the air-fuel ratio feedback is During control, the fuel injection amount Ti is calculated by correcting it using the air-fuel ratio feedback correction coefficient LAMBDA, thereby eliminating the delay in following the air-fuel ratio during transient operation.

When the fuel injection amount Ti is set, a drive pulse signal with a pulse width corresponding to the fuel injection amount Ti is output to the fuel injection valve, thereby injecting and supplying a predetermined amount of fuel to the engine. There is also a system in which data on the basic fuel injection amount Tp is stored in correspondence to each operating range in which the throttle valve opening degree α and the engine rotational speed N are used as parameters.

By the way, if the fuel injection amount Ti is set based on the intake air flow rate Q that is retrieved based on the detected values of the throttle valve opening degree α and the engine rotational speed N as described above, or The fuel injection amount is based on the basic fuel injection amount Tp that is searched based on the detected values of degree α and engine rotational speed N.
When Ti is set, the amount of air supplied bypassing the throttle valve is the amount of fuel injection.
Since it is unrelated to the setting of Ti, when there is air supplied bypassing the throttle valve, the fuel injection amount Ti is set to match the intake air flow rate Q, which is smaller than the actual amount, resulting in an overlean air-fuel ratio. It becomes a thing.

That is, an on-off valve is interposed in the bypass intake passage that bypasses the throttle valve, and this on-off valve is controlled to open, for example, when the electrical load increases during idling or when the air conditioner is activated, thereby opening the bypass intake passage. In a system in which the amount of air is increased to prevent a drop in the idle rotational speed, air that is not related to the throttle valve opening degree α is supplied by the opening control of the on-off valve.
Therefore, air other than the intake air flow rate Q, which is uniquely determined based on the detected values of the throttle valve opening α and the engine rotational speed N, is supplied, and is supplied bypassing the throttle valve. There is a shortage of fuel to compensate for the air content.

For this reason, conventionally, the retrieved intake air flow rate Q
(or the basic fuel injection amount Tp) is corrected by a predetermined amount based on the on/off status of the on-off valve that opens and closes the bypass intake passage. When controlling the idle speed by opening and closing the bypass intake passage, the negative pressure in the intake passage is large and the airflow flowing through the bypass intake passage becomes a sonic flow, so the flow rate depends on the opening area of the bypass intake passage. It remains approximately constant. Therefore, when the bypass intake passage is opened by the on-off valve, it is assumed that a predetermined amount of air is being supplied through the bypass intake passage.
The amount of fuel is increased in proportion to the amount of bypass air.

<Problems to be Solved by the Invention> However, in order to correctly reflect the amount of air supplied via the bypass intake passage in the setting of the fuel injection amount Ti as described above, it is necessary to use the bypass intake passage opened by the on-off valve. It is necessary that the opening area of the bypass intake passage be constant, and if there are variations in the opening area of the bypass intake passage due to manufacturing variations in the on-off valve, the amount of air actually supplied through the bypass intake passage will fluctuate, causing In the initial increase correction, the fuel injection amount Ti commensurate with the actual intake air flow rate Q is not set, and the air-fuel ratio deviates from the target air-fuel ratio.

Therefore, when there is variation in the opening area of the bypass intake passage, the learning correction coefficient K _MAP learned by air-fuel ratio feedback control when the bypass intake passage is closed (opened)
Even if the fuel injection Ti is corrected when the bypass intake passage is open (closed), the desired air-fuel ratio cannot be obtained, and the air-fuel ratio will fluctuate if the bypass intake passage is opened or closed during idle operation. In order to avoid such instability in idle operation, it is necessary to minimize the manufacturing tolerance of the on-off valve, resulting in an increase in manufacturing costs. .

The present invention has been made in view of the above-mentioned problems, and makes it possible to learn manufacturing variations in on-off valves that open and close bypass intake passages, thereby ensuring idling stability and relaxing manufacturing tolerances on on-off valves. The purpose is to reduce manufacturing costs.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. An engine rotation speed detection means for detecting the rotation speed, and an intake air flow rate of the engine in the relevant operating state based on the detected values of the throttle valve opening degree and the engine rotation speed, and a basic fuel injection amount based on the intake air flow rate. basic fuel injection amount setting means for setting the bypass intake passage; bypass intake passage opening/closing means for controlling opening/closing of the bypass intake passage that bypasses the throttle valve in accordance with increases and decreases in engine external load; basic fuel injection amount increase correction means for setting the basic fuel injection amount by increasing the basic fuel injection amount set by the basic fuel injection amount setting means by a predetermined amount when the basic fuel injection amount setting means is open; and detecting an engine exhaust component. and an air-fuel ratio detection means for detecting the air-fuel ratio of the engine intake air-fuel mixture; and an air-fuel ratio detected by the air-fuel ratio detection means and a target when the bypass intake passage is closed by the bypass intake passage opening/closing means. a first learning correction amount that learns and sets a correction amount for correcting the basic fuel injection amount set by the basic fuel injection amount setting means so that the actual air-fuel ratio approaches the target air-fuel ratio by comparing the air-fuel ratio; setting means; comparing the air-fuel ratio detected by the air-fuel ratio detection means with a target target air-fuel ratio when the bypass intake passage is opened by the bypass intake passage opening/closing means, and determining the actual air-fuel ratio as the target air-fuel ratio; a second learning correction amount setting means for learning and setting a correction amount for correcting the basic fuel injection amount set by increasing the basic fuel injection amount by the basic fuel injection amount increase correction means so as to approach the basic fuel injection amount; a first fuel injection amount for setting the fuel injection amount based on the basic fuel injection amount set by the amount setting means and the correction amount set by the first learning correction amount setting means;
a second fuel that sets a fuel injection amount based on the basic fuel injection amount corrected by the basic fuel injection amount correction device and the correction amount set by the second learning correction amount setting device; Injection amount setting means; Drive pulse signal output means for outputting a drive pulse signal corresponding to the fuel injection amount set by the first fuel injection amount setting means or the second fuel injection amount setting means to the fuel injection means. A learning control device for the air-fuel ratio of an internal combustion engine was configured.

<Function> According to the air-fuel ratio learning control device configured as described above,
When the bypass intake passage is opened by the bypass intake passage opening/closing means, the basic fuel injection amount increase correction means adjusts the fuel injection amount set by the basic fuel injection amount setting means in anticipation of the amount of air supplied via the bypass intake passage. Correct the increase. Further, the correction amount for correcting the basic fuel injection amount so as to bring the actual air-fuel ratio closer to the target air-fuel ratio may be the first or second correction amount depending on whether the bypass intake passage is opened by the bypass intake passage opening/closing means. 2 Learning correction amount setting means selectively learns and sets, and when the bypass intake passage is closed, the basic fuel injection amount set by the basic fuel injection amount setting means and the correction learned with the bypass intake passage closed. The fuel injection amount is set by the first fuel injection amount setting means based on the amount, and when the bypass intake passage is open, the basic fuel injection amount corrected to increase by the basic fuel injection amount increase correction means and the bypass intake passage are opened. The fuel injection amount is set by the second fuel injection amount setting means based on the correction amount learned in the state where the fuel injection amount is set.

That is, the learning correction amount corresponding to when the bypass intake passage is closed and the learning correction amount corresponding to when the bypass intake passage is open are respectively set independently.

<Example> An example of the present invention will be described below based on the drawings.

FIG. 2 shows the hardware configuration of this embodiment.

The control unit 6, which has a built-in microcomputer, detects the opening α of the throttle valve 3, which is detected by the throttle valve opening sensor 4, which serves as a throttle valve opening detection means, and the rotational speed sensor, which serves as an engine rotational speed detection means. There is a close relationship between the engine rotation speed N detected by the engine rotation speed N and the air-fuel ratio of the engine intake air-fuel mixture detected by the _O2 sensor 10 as an air-fuel ratio detection means installed in the exhaust passage 11. The oxygen concentration in the exhaust gas and the engine cooling water temperature Tw in the cooling jacket detected by the water temperature sensor 12 are inputted. The control unit 6 also includes a normally closed electromagnetic on-off valve 9 as a bypass intake passage opening/closing means for opening and closing a bypass intake passage 8 provided by bypassing the throttle valve 3, and an electromagnetic fuel injection valve as a fuel injection means. 7 are controlled to open and close by energization control.

That is, the control unit 6 controls the opening of the electromagnetic on-off valve 9 when an external load increases, such as when an electrical load increases or when an air conditioner is activated, and also controls the fuel injection amount according to the engine operating state detected based on each of the sensors. The control unit 6 includes a basic fuel injection amount setting means, a basic fuel injection amount setting means,
It also serves as basic fuel injection amount increase correction means, first learning correction amount setting means, second learning correction amount setting means, first fuel injection amount setting means, second fuel injection amount setting means, and drive pulse signal output means. .

Learning control of the air-fuel ratio in the electronically controlled fuel injection system having such a configuration will be explained with reference to the flowcharts of FIGS. 3 to 5 and the time chart of FIG. 6.

In the fuel injection amount calculation routine shown in FIG. The engine rotational speed N detected for the engine is read.

In step 2, the intake air flow rate Q (intake air flow rate Q when the bypass suction passage 8 is closed) corresponding to the throttle valve opening degree α and the engine speed N is determined in advance through experiments, etc., and stored. be
Referring to the map on the ROM, the intake air flow rate Q corresponding to the actual α and N is retrieved and read.

In step 3, it is determined whether the normally closed electromagnetic on-off valve 9 that opens and closes the bypass suction passage 8 that bypasses the throttle valve 3 is on or off (the drive signal output is on or off).
When the bypass suction passage 8 is controlled to close, the process proceeds to step 4, and when it is on and the bypass suction passage 8 is controlled to open, the process proceeds to step 7.

In step 4, the bypass intake passage 8 is closed and the intake air flow rate Q retrieved based on the detected values of α and N approximately corresponds to the actual value. Based on the speed N and the intake air flow rate Q retrieved in step 2, a basic fuel injection amount Tp (=K×Q/N; K is a constant) is calculated.

In the next step 5, the air-fuel ratio learning correction coefficient K _MAP1 for when the electromagnetic on-off valve 9 is OFF is stored for each operating state classified by the engine rotational speed N representing the engine operating state and the basic fuel injection amount Tp. With reference to a map on a certain RAM, a learning correction coefficient K _MAP1 corresponding to the actual engine speed N and basic fuel injection amount Tp is searched and read.

In step 6, the learning correction coefficient _KMAP1 for when the electromagnetic on-off valve 9 is off, which was read in step 5, is set as the learning correction coefficient _KMAP used for calculating the fuel injection amount Ti.

On the other hand, in step 7, since the bypass intake passage 8 is in an open state, the amount of air supplied via the bypass intake passage 8 is stored in advance.
Add Q ₀ (air amount corresponding to the opening area of the electromagnetic on-off valve 9) to the intake air flow rate Q found in step 2 to obtain the basic fuel injection amount Tp {K×Q+Q ₀ )/N;
K is a constant}.

This is because when the electromagnetic on-off valve 9 is on and the bypass intake passage 8 is open, the opening area of the bypass intake passage 8 is added to the effective opening area of the intake passage determined by the throttle valve opening α. On the other hand,
Since the intake air flow rate Q searched by α, N is not set including the opening area of this bypass intake passage 8, the intake air flow rate Q searched by α, N is By adding the quantity Q ₀ , an intake air flow rate Q that approximately corresponds to the actual intake air flow rate Q is determined and used for calculating the basic fuel injection amount Tp.

In the next step 8, the learning correction coefficient K of the air-fuel ratio when the electromagnetic on-off valve 9 is on is set for each area of the operating state of the number divided by the engine rotational speed N representing the engine operating state and the basic fuel injection amount Tp. Referring to the map in the RAM that stores _MAP2 , the learning correction coefficient K _MAP2 corresponding to the actual engine speed N and basic fuel injection amount Tp is searched and read.

In step 9, the learning correction coefficient _KMAP2 for when the electromagnetic on-off valve 9 is on, read in step 5, is set as the learning correction coefficient _KMAP used in calculating the fuel injection amount Ti.

In this way, the amount of air supplied via the bypass suction passage 8 is controlled by turning on and off the electromagnetic on-off valve 9.
In addition to controlling the addition of Q ₀ , the learning correction coefficients K _MAP1 and K _MAP2 corresponding to each state are selected and searched by turning on/off the electromagnetic on/off valve 9, and the values are used to calculate the fuel injection amount Ti. It is designed to be used for As a result, even if there are variations in the opening area of the bypass intake passage 8 when the electromagnetic on-off valve 9 is turned on due to manufacturing variations, the basic fuel injection amount Tp can be adjusted using the learning correction coefficient K _MAP2 that has learned the air-fuel ratio change due to the variation. A correction calculation is performed so that a desired air-fuel ratio can be obtained.

That is, if there are variations in the opening area of the bypass intake passage 8 when the valve is turned on due to manufacturing variations in the electromagnetic on-off valve 9, the actual amount of air Q ₀ obtained through the bypass intake passage 8 may differ from the intended amount. , the basic fuel injection amount Tp does not correspond to the target air-fuel ratio in the additive control of the air amount Q ₀ , and the learning correction coefficient K _MAP that is learned to bring the air-fuel ratio closer to the target air-fuel ratio is Different values will be learned depending on when the switch is turned off and when the switch is off. However, if the fuel injection amount Ti is calculated based on the learning correction coefficient K _MAP that is learned independently when the electromagnetic on-off valve 9 is on and off as in this embodiment, the electromagnetic on-off valve 9 is turned on when idling.・Even if it is switched off, the fuel injection amount is set according to the learning correction coefficient K _MAP that has been learned so that it approaches the target air-fuel ratio in the state after the switch, so the air-fuel ratio may fluctuate from the target air-fuel ratio. can be avoided.

Step 6 or Step 9 to Step 1
When it goes to 0, it includes an acceleration correction based on the rate of change of the throttle valve opening α detected by the throttle valve opening sensor 4, a water temperature correction corresponding to the cooling water temperature Tw detected by the water temperature sensor 12, etc. Set various correction coefficients COEF.

In step 11, an air-fuel ratio feedback correction coefficient LAMBDA set in a proportional/integral control routine shown in FIG. 4, which will be described later, is read. Note that the reference value of this air-fuel ratio feedback correction coefficient LAMBDA is 1.

In step 12, a voltage correction amount Ts is set based on the battery voltage value. This is to correct changes in the effective valve opening time of the fuel injection valve 7 due to changes in battery voltage.

In step 13, the fuel injection amount Ti is calculated according to the following equation.

Ti=Tp×COEF×(LAMBDA+K _MAP )+Ts In step 14, the calculated fuel injection amount Ti
Set in the output register. As a result, when a predetermined fuel injection timing synchronized with the engine rotation is reached, a drive pulse signal having a pulse width of Ti is applied to the fuel injection valve 7, and fuel is injected and supplied.

FIG. 4 shows a proportional/integral control routine, which is executed at predetermined intervals (for example, 10 ms), thereby setting the air-fuel ratio feedback correction coefficient LAMBDA.

In step 21, it is determined whether or not the current operating state is in a range where air-fuel ratio feedback control (λ control) is performed. , when the machine is cold, etc.), this routine ends. In this case, the air-fuel ratio feedback correction coefficient LAMBDA is clamped to the previous value (or reference value 1), and the air-fuel ratio feedback control is stopped.

When the operating state is such that feedback control of the air-fuel ratio is performed, the process proceeds to step 22 to read the output voltage V ₀₂ of the O ₂ sensor 10, and then proceeds to the next step 23.
The richness or leanness of the air-fuel ratio is determined by comparing it with the slice level voltage V _ref corresponding to the stoichiometric air-fuel ratio.

When the air-fuel ratio is lean (V ₀₂ <V _ref ), the process proceeds from step 23 to step 24 to determine whether or not it is the time of reversal from rich to lean (immediately after reversal), and when the air-fuel ratio is reversed, the process proceeds to step 25. The air-fuel ratio feedback correction coefficient LAMBDA is increased by a predetermined proportionality constant P relative to the previous value. Otherwise, proceed to step 26 and set the air-fuel ratio feedback correction coefficient.
LAMBDA is increased by a predetermined integral constant with respect to the previous value, thus adjusting the air-fuel ratio feedback correction coefficient.
Increase LAMBDA at a constant slope (see Figure 6). Note that P>>I.

When the air-fuel ratio is rich (V ₀₂ > V _ref ), the process proceeds from step 23 to step 27, where it is determined whether or not it is the time of reversal from lean to rich (immediately after reversal), and when the air-fuel ratio is reversed, the process proceeds to step 28. The air-fuel ratio feedback correction coefficient LAMBDA is decreased by a predetermined proportionality constant P from the previous value. Otherwise, proceed to step 29 and set the air-fuel ratio feedback correction coefficient.
LAMBDA is decreased by a predetermined integral constant I with respect to the previous value, and the air-fuel ratio feedback correction coefficient is
Decrease LAMBDA at a constant slope (see Figure 6).

FIG. 5 shows a learning routine in which the learning correction coefficient K _MAP is learned independently depending on whether the electromagnetic on-off valve 9 is on or off.

In step 31, it is determined whether or not the operating state is one in which air-fuel ratio feedback control is performed. If the operating state is in which no feedback control is performed, the process proceeds to step 34, where the count value C _MAP is cleared and then this routine is executed. finish. This is because learning cannot be performed when air-fuel ratio feedback control is stopped.

If the current operating state is an operating state in which air-fuel ratio feedback control is performed and the process advances to step 32,
It is determined whether or not the electromagnetic on-off valve 9 has been switched on and off. If the switching has not been carried out and the on state or off state is maintained, the process proceeds to step 33, and if the switching has been carried out, the process proceeds to step 34. Proceed to and clear the count value _CMAP , then end this routine.

In step 33, it is determined whether or not the engine rotation speed N, which represents the engine operating state, and the basic fuel injection amount Tp are in the same area as the previous time. If the area has changed, the process proceeds to step 34, and the engine is in the same area as the previous time. If so, it is determined in step 35 whether the output of the O ₂ sensor 10 has been reversed, that is, the direction of increase or decrease of the air-fuel ratio feedback correction coefficient LAMBDA has been reversed, and each time this routine is repeated and determined, the number of reversals is counted in step 36. Add 1 to the count value C _MAP that represents, for example,
When C _MAP = 3, proceed from step 37 to step 38, temporarily store the deviation (LAMBDA - 1) of the current air-fuel ratio feedback correction coefficient LAMBDA from the reference value 1 as ΔLAMBDA ₁ , and start learning. .

Then, when C _MAP = 4 or more, step 37
The program then proceeds to step 39, where the deviation (LAMBDA-1) of the air-fuel ratio feedback correction coefficient LAMBDA from the reference value 1 at that time is temporarily stored as _ΔLAMBDA2 .

In this way, the feedback correction coefficient
Once the upper and lower peak values ΔLAMBDA ₁ and ΔLAMBDA ₂ of deviation from the standard value 1 of LAMBDA are determined, the process proceeds to step 40 to determine their average value.

Next, in step 41, it is determined whether the electromagnetic on-off valve 9 is on or off, and the learning correction coefficient for when it is off is determined.
K _MAP1 learning and learning correction coefficient K _MAP2 for on time
Have students select and perform learning.

When it is determined in step 41 that the electromagnetic on-off valve 9 is off, in step 42, the off-time learning correction coefficient K _MAP1 (initial value 0 ) is searched and read.

Then, the process proceeds to step 43, where a predetermined percentage of the average value ΔLAMBDA of the deviation of the air-fuel ratio feedback correction coefficient from the reference value is added to the current learning correction coefficient K _MAP1 according to the formula, thereby creating a new off-time correction coefficient. Calculate learning correction coefficient K _MAP1 ,
Correct and rewrite the off-time learning correction coefficient K _MAP1 data in the same area of the map on RAM.

K _MAP1 ←K _MAP1 +M _MAP (M _MAP is an addition ratio constant, 0<M _MAP <1) After this, in step 46, ΔLAMBDA ₂ is substituted into ΔLAMBDA ₁ for the next learning.

Similarly, when it is determined in step 41 that the electromagnetic on-off valve 9 is on, in step 44, the on-time learning correction coefficient K _MAP2 ( The initial value 0) is searched and read.

Then, the process proceeds to step 45, and a new on-time setting is created by adding a predetermined percentage of the average value ΔLAMADA of the deviation of the air- _fuel ratio feedback correction coefficient from the reference value to the current learning correction coefficient K MAP2 according to the following formula. Calculate the learning correction coefficient K _MAP2 ,
Correct and rewrite the on-time learning correction coefficient K _MAP2 data in the same area of the map on RAM.

K _MAP2 ←K _MAP2 +M _MAP・After this, in step 46, ΔLAMBDA ₂ is substituted into ΔLAMBDA ₁ for the next learning.

In this way, when the electromagnetic on-off valve 9 is off, the off-time learning correction coefficient K _MAP1 is learned, and when the electromagnetic on-off valve 9 is on, the on-time learning correction coefficient K _MAP2 is learned. Therefore, even if the amount of air obtained through the bypass intake passage 8 when the electromagnetic on-off valve 9 is on varies due to manufacturing variations in the electromagnetic on-off valve 9, this manufacturing variation can be learned. If the learning correction coefficients K _MAP1 and K _MAP2 are used differently depending on whether the solenoid on-off valve 9 is turned on or off during idling operation, the solenoid on-off valve 9 will be turned on or off in response to an increase or decrease in external load during idling operation. Even if the switch is turned off, the learning correction coefficient KMAP is used to bring the air-fuel ratio closer to the target air-fuel ratio in the state after switching, so the air-fuel ratio can be kept constant.

<Effects of the Invention> As explained above, according to the present invention, in a device in which the opening and closing of the bypass intake passage that bypasses the throttle valve is controlled according to increases and decreases in engine external load, when the bypass intake passage is opened, The air-fuel ratio is learned independently when the air-fuel ratio is closed and when the air-fuel ratio is closed, and two learning correction amounts are used depending on the open/closed state, so even if the bypass intake passage is switched open or closed during idling, the air-fuel ratio will remain unchanged. This has the effect of being able to maintain a constant value and improving idle stability.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the present invention, Figs. 3 to 5 are flowcharts showing control programs in the above embodiment, and Fig. 6 is an empty This is a time chart showing the characteristics of the fuel ratio feedback correction coefficient. DESCRIPTION OF SYMBOLS 1...engine, 3...throttle valve, 4...throttle valve opening sensor, 5...rotational speed sensor, 6...control unit, 7...fuel injection valve, 8...bypass intake passage, 9...electromagnetic on-off valve, 10...O ₂ sensor.

Claims (1)

[Scope of Claims] 1. Throttle valve opening detection means for detecting the opening of a throttle valve installed in the intake passage of the engine; Engine rotational speed detection means for detecting the rotational speed of the engine; Throttle valve opening basic fuel injection amount setting means that sets an intake air flow rate of the engine in the operating state based on detected values of and engine rotational speed, and sets a basic fuel injection amount based on the intake air flow rate; and bypassing the throttle valve. bypass intake passage opening/closing means for controlling the opening/closing of a bypass intake passage according to an increase/decrease in engine external load; a basic fuel injection amount increase setting means for setting the basic fuel injection amount by increasing the basic fuel injection amount by a predetermined amount; and an air-fuel ratio detection device for detecting engine exhaust components and thereby detecting the air-fuel ratio of the engine intake air-fuel mixture. and comparing the air-fuel ratio detected by the air-fuel ratio detection means with a target air-fuel ratio when the bypass intake passage is closed by the bypass intake passage opening/closing means to bring the actual air-fuel ratio closer to the target air-fuel ratio. first learning correction setting means for learning and setting a correction amount for correcting the basic fuel injection amount set by the basic fuel injection amount setting means; and a first learning correction setting means for learning and setting a correction amount for correcting the basic fuel injection amount set by the basic fuel injection amount setting means; The air-fuel ratio detected by the air-fuel ratio detection means when the air-fuel ratio is set is compared with the target air-fuel ratio, and the basic fuel injection amount increase correction means performs an increase correction so as to bring the actual air-fuel ratio closer to the target air-fuel ratio. a second learning correction amount setting means for learning and setting a correction amount for correcting the basic fuel injection amount, and a basic fuel injection amount set by the basic fuel injection amount setting means and the first learning correction amount setting. a first means for setting the fuel injection amount based on the correction amount set by the means;
a second fuel that sets a fuel injection amount based on the basic fuel injection amount corrected by the basic fuel injection amount correction device and the correction amount set by the second learning correction amount setting device; Injection amount setting means; Drive pulse signal output means for outputting a drive pulse signal corresponding to the fuel injection amount set by the first fuel injection amount setting means or the second fuel injection amount setting means to the fuel injection means. An air-fuel ratio learning control device for an internal combustion engine, characterized by comprising: