JPH0792012B2 - Air-fuel ratio learning controller for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an air-fuel ratio learning control device for an internal combustion engine, and in particular,
The present invention relates to a fuel supply control device for an internal combustion engine, which is configured to calculate and set a basic fuel supply amount based on an opening area of an engine intake system and an engine rotation speed, with improved air-fuel ratio controllability.

<Prior Art> The opening area A of the engine intake system which is variably controlled is obtained through the throttle valve opening TVO and the like, and the basic fuel supply amount Tp is set based on the opening area A and the engine rotation speed N. An electronically controlled fuel supply device for an internal combustion engine configured as
-168949 gazette etc. are disclosed.

In this system, the basic fuel supply amount Tp is calculated based on the opening area A and the engine rotation speed N, and various correction coefficients COEF according to the engine operating conditions such as the engine temperature and the oxygen sensor provided in the exhaust system are used. The feedback correction coefficient LAMBDA that is set so that the air-fuel ratio detected via the signal of ## EQU1 ## approaches the target air-fuel ratio, and the correction amount Ts for correcting the change in the effective opening time of the fuel injection valve due to the battery voltage. Then, the basic fuel supply amount Tp is corrected by these, and the final fuel supply amount Ti (← Tp × COEF × LAMBDA + Ts) is calculated.

Then, a drive pulse signal having a pulse width corresponding to this fuel supply amount Ti is output to the fuel injection valve, and the fuel injection valve is opened for a predetermined time to inject and supply the fuel adjusted to a predetermined pressure, The fuel supply amount is controlled by the pulse width.

Further, the deviation from the reference value of the feedback correction coefficient LAMBDA is learned for each operating region divided into a plurality by the basic fuel supply amount Tp and the engine speed N, and the learning correction coefficient K _MAP is set and stored. , The learning correction coefficient K _MAP stored in this map is searched for according to the operating state, and the learning correction coefficient K _MAP obtained is included in the various correction coefficients COEF, so that the air-fuel ratio is corrected. There is something.

<Problems to be Solved by the Invention> However, when the basic fuel supply amount Tp is set from the opening area A obtained through the throttle valve opening TVO and the engine rotation speed N, if the throttle valve becomes dirty, Even if the opening TVO is the same as in the initial state, the opening area A actually obtained decreases at a large rate especially on the small opening side. Therefore, the characteristic of the intake air flow rate Q with respect to the throttle valve opening TVO is as shown in FIG. , Shows a larger decrease change on the small opening side. Therefore, if the throttle valve becomes dirty, the basic fuel supply amount that is larger than the engine required fuel amount is set on the small opening side, and the air-fuel ratio becomes rich.

The throttle valve opening TVO is set to the seventh value in the operating range divided by the engine speed N and the engine torque as parameters.
Since the air-fuel ratio enrichment ratio due to the dirt on the throttle valve is plotted in the operating region similarly having the engine speed N and the engine torque as parameters, it has the change characteristics as shown in FIG. The air-fuel ratio enrichment rate tends to increase as the rotation speed decreases and the torque decreases.

On the other hand, if the fuel injection valve deteriorates and the responsiveness deteriorates,
As shown in the figure, the amount of fuel actually injected and supplied is larger than that in the initial state, and the tendency becomes larger as the amount of fuel supply is smaller.

Here, in the operating region divided by the engine speed N and the engine torque as parameters, the fuel supply amount shows a change characteristic as shown in FIG. 10, so that the actual fuel supply amount due to deterioration of the fuel injection valve As shown in FIG. 11, the air-fuel ratio enrichment rate based on the change tends to be large on the low torque side in an operating region divided using the engine speed N and the engine torque as parameters.

Further, in the setting control of the basic fuel supply amount Tp based on the opening area A and the engine rotation speed N, even if the air density changes due to changes in altitude or intake air temperature, fuel supply control corresponding to this cannot be performed. , For example, if it is matched with lowland, the air-fuel ratio tends to become richer almost linearly as the altitude becomes higher, and the altitude (intake air temperature) becomes higher.
If the altitude (intake air temperature) is constant, even if the operating parameters such as torque and rotation speed change,
As shown in FIG. 13, it shows a constant enrichment rate.

As described above, in the system that controls the fuel supply by setting the basic fuel supply amount Tp based on the opening area A and the engine rotation speed N, even if matching is performed in the initial state, the dirt of the throttle valve, the fuel injection Since air-fuel ratio deviations occur with different characteristics due to valve deterioration, altitude, or changes in intake air temperature (see FIGS. 8, 11, and 13), as in the past, for example, basic fuel supply amount Tp and engine speed Even if a learning correction value of the air-fuel ratio is set for each operating region with N as a parameter and the learning correction value is used to absorb the air-fuel ratio deviation, dirt on the throttle valve that causes the air-fuel ratio deviation,
It is said that it is not possible to make corrections that are suitable for deterioration of the fuel injection valve, altitude or changes in intake air temperature, and a large air-fuel ratio step is generated depending on the operating region, so that highly accurate air-fuel ratio controllability cannot be stably obtained. There was a problem.

The present invention has been made in view of the above problems, and is capable of accurately performing air-fuel ratio correction control for each factor that causes an air-fuel ratio deviation, and is highly accurate in fuel supply control based on the opening area and the engine rotation speed. The purpose is to obtain air-fuel ratio controllability.

<Means for Solving the Problems> Therefore, in the air-fuel ratio learning control device for an internal combustion engine according to the present invention, as shown in FIG. 1, the opening area of the engine intake system and the engine rotation speed that are variably controlled are different from each other. State quantity detection means for detecting the state quantity involved, basic fuel supply quantity setting means for setting the basic fuel supply quantity based on the state quantity detected by this state quantity detection means, and the air-fuel ratio of the engine intake air-fuel mixture Air-fuel ratio detection means for detecting, and an air-fuel ratio feedback correction coefficient for setting the air-fuel ratio feedback correction coefficient for correcting the basic fuel supply amount so that the air-fuel ratio detected by this air-fuel ratio detection means approaches the target air-fuel ratio. Setting means,
Voltage correction amount setting means for setting a voltage correction amount for correcting the basic fuel supply amount according to a voltage change of the driving power source of the fuel supply means, and the basic fuel supply amount, the air-fuel ratio feedback correction coefficient and the voltage correction amount A first learning correction value for correcting the basic fuel supply amount by a ratio of the opening area to the detected value, a second learning correction value for correcting the air-fuel ratio feedback correction coefficient, and a third learning correction value for correcting the voltage correction amount. Fuel supply amount setting means for calculating the fuel supply amount including at least the learning correction value, and fuel supply control means for drivingly controlling the fuel supply means based on the fuel supply amount calculated by the fuel supply amount setting means. And a fuel calculation that stores the fuel supply amount calculated by the fuel supply amount setting means and the calculation parameter of the fuel supply amount for each of at least three different operating states. In the storage means and the calculation of at least three fuel supply amounts stored in the fuel calculation storage means, when the air-fuel ratio feedback correction coefficient is set to a reference value, the first, second and third learning correction values are A learning correction value setting means for learning and updating and setting each of them so as to be commonly applicable to the calculation of the three fuel supply amounts.

Further, as shown by the dotted line in FIG. 1, three learning correction values set by the learning correction value setting means are averaged, and the fuel supply amount is set by the three learning correction values that have been averaged. It is preferable to provide learning correction value averaging means for calculating the fuel supply amount by means.

Further, as indicated by the dotted line in FIG. 1, the transient operation determining means for determining the transient operating state of the engine, and the learning correction value setting means when the transient operating state of the engine is determined by the transient operating determining means. It is preferable to provide a learning correction value update prohibiting means for prohibiting update setting of three learning correction values.

<Operation> According to such a configuration, the state quantity detection means, the state quantities involved in the opening area of the engine intake system that is variably controlled, and the engine rotation speed are detected, and the basic fuel supply amount setting means detects these states. Set the basic fuel supply based on the amount.

Further, the air-fuel ratio feedback correction coefficient setting means sets an air-fuel ratio feedback correction coefficient for correcting the basic fuel supply amount so that the air-fuel ratio detected by the air-fuel ratio detecting means approaches the target air-fuel ratio.

The voltage correction amount setting means sets a voltage correction amount for correcting the basic fuel supply amount according to the voltage change of the driving power source of the fuel supply means.

Then, the fuel supply amount setting means is
An air-fuel ratio feedback correction coefficient and a voltage correction amount, a first learning correction value for correcting the basic fuel supply amount by a ratio of the opening area to a detection value, and a second learning correction value for correcting the air-fuel ratio feedback correction coefficient, A fuel supply amount is calculated by including at least a third learning correction value for correcting the voltage correction amount.

The fuel supply control means drives and controls the fuel supply means based on the fuel supply amount calculated here.

On the other hand, the fuel calculation storage means stores the fuel supply amount calculated by the fuel supply amount setting means and the calculation parameter of the fuel supply amount for each of at least three different operating states, and sets the learning correction value. In the calculation of the at least three fuel supply amounts stored in the fuel calculation storage means, when the air-fuel ratio feedback correction coefficient is set to a reference value, the first, second and third learning correction values are Even if the air-fuel ratio feedback correction coefficient is set to a reference value, the target air-fuel ratio is adjusted using the first, second, and third learning correction values by learning and updating so as to be commonly applicable to the calculation of the three fuel supply amounts. A considerable fuel supply amount is calculated.

The learning correction value averaging means averages each of the three learning correction values set by the learning correction value setting means, and the fuel supply amount setting means uses the three learning correction values thus averaged. The calculation of the fuel supply amount is performed to avoid a sudden change in the learning correction value used for the fuel supply amount calculation.

Further, when the transient operation determining means determines the transient operating state of the engine, the learning correction value update prohibiting means prohibits the update setting of the three learning correction values by the learning correction value setting means, and during the transient operation. 3 based on the air-fuel ratio deviation
Avoid learning update of one learning correction value.

<Examples> Examples of the present invention will be described below.

In FIG. 2 showing the system configuration of one embodiment, air is taken into the internal combustion engine 1 via an air cleaner 2, an intake duct 3, a throttle chamber 4 and an intake manifold 5. The air cleaner 2 is provided with an intake air temperature sensor 6 that detects an intake air (atmosphere) temperature TA (° C.).

The throttle chamber 4 is provided with a throttle valve 7 interlocking with an accelerator pedal (not shown) to control the intake air flow rate Q. The opening of the throttle valve 7
A throttle sensor 8 including an idle switch 8A that is turned on at the fully closed position (idle position) is attached together with a potentiometer for detecting TVO.

The intake manifold 5 downstream of the throttle valve 7 is provided with an electromagnetic fuel injection valve 10 as fuel supply means for each cylinder.

The electromagnetic fuel injection valve 10 is intermittently opened and driven by a drive pulse signal output from a control unit 11 having a microcomputer, which will be described later, and is pressure-fed from a fuel pump (not shown) to a predetermined pressure by a pressure regulator. The fuel thus injected is injected and supplied into the intake manifold 5. That is, the amount of fuel supplied by the fuel injection valve 10 is controlled by the valve opening drive time of the fuel injection valve 10.

Further, a water temperature sensor 12 for detecting the cooling water temperature Tw in the cooling jacket of the engine 1 is provided, and an air-fuel ratio for detecting the air-fuel ratio of the engine intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas in the exhaust passage 13. Oxygen sensor as detection means
14 are provided.

The control unit 11 outputs the crank unit angle signal POS output from the crank angle sensor 15 in synchronization with the engine rotation.
Is counted for a certain period of time or at every predetermined crank angle position (4
The engine rotation speed N is detected by measuring the cycle of the crank reference angle signal REF output every 180 ° in the case of a cylinder.

The control unit 11 calculates the fuel injection amount Ti (pulse width of the drive pulse signal) based on the detection signals from the various sensors, and also causes the fuel injection valve 10 to rotate the engine based on the set fuel injection amount Ti. The open drive control is performed at a predetermined timing synchronized to control the fuel supply.

Next, various calculation processes for fuel supply control performed by the control unit 11 will be described according to the routines shown in the flowcharts of FIGS.

In this embodiment, basic fuel supply amount setting means, air-fuel ratio feedback correction coefficient setting means, voltage correction amount setting means,
The functions of the fuel supply amount setting means, the fuel supply control means, the learning correction value setting means, the fuel calculation storage means, the learning correction value averaging means, the transient operation determining means, and the learning correction value update prohibiting means are the same as those shown in FIGS. Software is provided as shown in the flowchart of FIG. Further, in the present embodiment, the state quantity detecting means includes a throttle sensor 8 for detecting the opening TVO of the throttle valve 7 for variably controlling the opening area A of the throttle chamber 4, and a crank for outputting a detection signal synchronized with the engine rotation. The angle sensor 15 corresponds.

The routine shown in the flowchart of FIG.
This is executed for each rotation (1rev). First, in step 1 (indicated as S1 in the figure. The same applies below), the oxygen sensor (O ₂ / S) 14 outputs the oxygen according to the oxygen concentration in the exhaust gas. Input the converted detection signal after AD conversion.

In the next step 2, the air-fuel ratio feedback correction coefficient LAMBDA is manipulated in advance for each operating state divided into a plurality of engine speeds N and a basic fuel injection amount (basic fuel supply amount) Tp set in a routine described later. Data corresponding to the current engine rotation speed N and the basic fuel injection amount Tp is searched and obtained from the map storing the amount.

The air-fuel ratio feedback correction coefficient LAMBDA is used for correction calculation of the basic fuel injection amount Tp, and is set so that the air-fuel ratio detected by the oxygen sensor 14 approaches the target air-fuel ratio (theoretical air-fuel ratio). In the embodiment, setting control is performed by proportional / integral control, and the manipulated variables obtained by searching from the map are a rich control proportional amount PR, a lean control proportional amount PL, and an integral amount I.

In step 3, the output of the oxygen sensor 14 obtained by AD conversion in step 1 is compared with a slice level (eg, 500 mV) corresponding to the target air-fuel ratio, and the air-fuel ratio of the engine intake air-fuel mixture is rich with respect to the target. Or lean.

If it is determined that the air-fuel ratio is rich, the routine proceeds to step 4 and the rich initial determination flag FR is determined. Since the rich initial determination flag FR is set to zero in the lean state of the air-fuel ratio, the rich initial determination flag FR is determined to be zero in this step 4 when it is the first time of rich detection.

If FR = 0 and the rich detection is the first time, step 5
Go to and the air-fuel ratio feedback correction coefficient LAMB up to the previous time
By subtracting the lean control proportional PL obtained in step 2 from the DA value and setting the result as a new air-fuel ratio feedback correction coefficient LAMBDA, the fuel supply amount is reduced and corrected, and the air-fuel ratio is corrected. So that the rich state of is eliminated.

After the air-fuel ratio feedback correction coefficient LAMBDA is proportionally controlled by the lean control proportion PL, the rich initial discrimination flag FR is set to 1 in step 6 while the lean initial discrimination flag FL is set to zero.

And when the air-fuel ratio rich state continues,
When it is determined in step 4 that the rich initial determination flag FR is 1, the process proceeds to step 7.

In step 7, the air-fuel ratio feedback correction coefficient LAMBDA
The integral I is subtracted from the previous value of and the result is newly set in the air-fuel ratio feedback correction coefficient LAMBDA. Therefore, the air-fuel ratio feedback correction coefficient LAMBDA is gradually decreased by the integral amount I in step 7 every time the engine 1 makes one revolution until the rich state of the air-fuel ratio is resolved.

When the air-fuel ratio rich state is eliminated by the decrease of the air-fuel ratio feedback correction coefficient LAMBDA by the integral control and it is determined in step 3 that the air-fuel ratio is lean, the routine proceeds to step valve 8 this time, and the lean first-time determination flag FL Is determined.

Since the lean first-time determination flag FL is set to zero in the rich state of the air-fuel ratio in step 6, if this time is the first time of lean detection, this step 8
Then, the judgment of FL = 0 is made.

If FL = 0 and it is the first time of lean detection, step 9
Go to and add PR for rich control proportional to the previous value of the air-fuel ratio feedback correction coefficient LAMBDA to correct the fuel increase. Then, in the next step 10, the rich initial discrimination flag FR is set to zero while the lean initial discrimination flag FL is set.
Set to 1.

When it is determined in step 8 that the lean initial determination flag FL is 1, and the lean state continues, the process proceeds to step 11. In this step 11, the integral I is added to the air-fuel ratio feedback correction coefficient LAMBDA. Control the integration.

As described above, air-fuel ratio feedback correction coefficient LAMBDA
Is variably set by the proportional / integral control, the transient flag Ftr is determined in the next step 12.

The transient flag Ftr is set to zero when the engine 1 is continuously operating for a predetermined time or longer as will be described later, and is set to 1 otherwise.

When the engine 1 is in a stable steady operation state, the transient flag F
When tr is zero, the routine proceeds to step 13, where it is the first time that the steady state discrimination in this step 12 is made, that is,
It is determined by the steady-state first-time determination flag Ftrm whether or not it is the first time that the steady-state operation is determined.

The steady-state initial determination flag Ftrm is set to 1 in step 18 when the engine 1 is in transient operation (when the transient flag Ftr is set to 1). In the first switch to, the steady first-time discrimination flag Ftrm is 1.

When the transient flag Ftr is zero and the steady-state first-time determination flag Ftrm is 1, the steady-state first-time determination flag Ftrm is set to zero in step 14, and then in step 15, the learning correction value a, Data is stored for learning b and c.

That is, in step 15, the fuel injection amount Ti calculated recently is calculated.
Is set to the memory value MTI, the MTI value up to the previous time is set to MT2, the MT2 value up to the previous time is set to MT3, and the recent 3 conditions with Ftr = 0 and Ftrm = 1
The fuel injection amount Ti for each time is stored.

Further, here, the parameter used to calculate the fuel injection amount Ti set and stored in MTI3, MTI2, MTI1 is 2 ×.
Similarly, Tp × COEF is calculated from the latest value, Para1, Para2, Para3.
Set each to. Here, Tp is the basic fuel injection amount obtained from the opening area A of the engine intake system and the engine rotation speed N, and COEF is various corrections mainly set by the cooling water temperature Tw detected by the water temperature sensor 12. Coefficient, and
The factor doubled is a coefficient for using a basic fuel injection amount common to the fuel control (sequential injection control) which is performed at the timing of the intake stroke of each cylinder and the all-cylinder simultaneous injection control. The double corresponds to the fuel injection amount Ti used for the normal sequential injection control (see the flowchart in FIG. 4).

Further, in this step 15, the data of the opening area A used when calculating the basic fuel injection amount Tp is similarly obtained in the past three times MA1,
Memorize across MA2 and MA3.

Therefore, the storage of the calculation data of the fuel injection amount Ti in step 15 is updated at the first time when the engine 1 transits to transient operation and shifts to steady state, and in normal operation of the internal combustion engine, during steady operation after transient. Since exact reproducibility of operating conditions cannot be expected, data is collected under different operating conditions (engine load, engine speed).

Then, in the next step 16, the air-fuel ratio feedback correction coefficient LA is used by using the data stored in step 15 in the past three times of calculation of the fuel injection amount Ti with different operating states.
MBDA is set to an initial value of 1, and three learning correction values a, b, c (first, third, second learning correction values) that are used for learning and updating when calculating the normal fuel injection amount Ti Is set as an unknown value and the calculation formula of the fuel injection amount Ti is reset, and three learning correction values a,
Solving a simultaneous equation consisting of the following three equations for the fuel injection amount Ti, in which some numerical value is substituted for values other than b and c,
Three learning correction values a, b, c are obtained.

It should be noted that although past data is not stored for the voltage correction amount Ts, in general the voltage correction amount Ts does not change finely for each operating state, so the standard value (value at standard voltage) should be substituted. I am doing it. In addition, the learning correction value
The initial values of a, b, and c are a for zero, b for 1, and c for 1, respectively.
Is.

As will be described later, in this embodiment, the fuel injection amount Ti is calculated by the following formula.

Here, since the data of Ti, 2 × Tp × COEF, A are stored respectively, the air-fuel ratio feedback correction coefficient LAMBDA is set to the initial value 1, the learning correction values a, b, c are set to unknown values, and further the voltage correction is performed. By substituting the standard value for the minute Ts, the arithmetic expression of the fuel injection amount Ti can be reconstructed. While there are three unknowns (a, b, c), there are three arithmetic expressions. Since the values are set, the learning correction values a, b, and c, which are unknowns, can be obtained as a simultaneous equation of three arithmetic expressions. still,
,, are weighted average values of the learning correction values a, b, and c.

That is, in the arithmetic expression in step 16, since the air-fuel ratio feedback correction coefficient LAMBDA is set to the initial value 1, an air-fuel ratio deviation occurs due to some cause, and the air-fuel ratio feedback correction coefficient LAMBDA When the central value is changed from the initial value 1, this correction is not added to the calculation in step 16, and the correction amount is distributed to the three learning correction values a, b, c by the simultaneous equations. .

Of the three learning correction values a, b, c, the learning correction value a is Since the basic fuel injection amount Tp is corrected with, the larger the opening area A is, the larger the correction becomes. This characteristic is that when the throttle valve 7 shown in FIGS. 6 to 8 is contaminated. It will correspond to the air-fuel ratio control error,
When the throttle valve 7 becomes dirty and the opening area A with respect to the opening TVO decreases and the air-fuel ratio becomes rich, the correction can be performed by the learning correction value a.

Further, since the learning correction value b is multiplied by the voltage correction amount Ts, by correcting a fixed amount regardless of the operating state, the smaller the fuel injection amount Ti, the more the learning correction value b is adjusted. The correction becomes large. The above characteristics are shown in FIGS.
As shown in Fig. 11, the fuel injection valve 10 deteriorates and the fuel injection amount Ti
This corresponds to the characteristic that the smaller the value of the, the greater the effect thereof appears, and the learning correction value b can accurately absorb the air-fuel ratio deviation due to the deterioration of the fuel injection valve 10.

Further, since the learning correction value c is multiplied by the basic fuel injection amount Tp, the basic fuel injection amount Tp is corrected by a fixed ratio regardless of the operating state. The above characteristics correspond to the characteristics when the air density changes due to changes in altitude and intake air temperature, and as shown in Figs. 12 and 13, the air-fuel ratio is uniformly deviated in all operating conditions. The value c can absorb the air-fuel ratio deviation due to the change in the air density.

In this way, the learning correction values a, b, c are learned and the fuel injection amount Ti
When used in the calculation of, the air-fuel ratio deviation due to the dirt of the throttle valve 7 having different characteristics, the deterioration of the fuel injection valve 10, and the air density change can be corrected in accordance with each characteristic, Accurate air-fuel ratio correction control can be performed without causing a step difference in the air-fuel ratio.

Although the learning correction values a, b, and c are learned by the simultaneous equations, the data is not used as it is for the calculation of the fuel injection amount Ti, but
In the next step 17, the weighted average calculation of each learning correction value a, b, c is performed according to the following formula, and the learning correction value is
A large change in a, b, c is avoided, and the learning correction values weighted and averaged here are used to calculate the fuel injection amount Ti.

← (1.0−X) + a × X ← (1.0−Y) + b × Y ← (1.0−Z) + c × Z Here, X, Y, Z are weighted averages of the respective learning correction values a, b, c. It is a weighting factor used for the calculation, and 0 ≦ X, Y, Z ≦ 1.0.

Next, the calculation setting of the fuel injection amount Ti and the transient determination will be described according to the routine shown in the flowchart of FIG.

This routine is executed every 10 ms. First, in step 21, the detection signal output from the throttle sensor 8 according to the opening TVO of the throttle valve 7 is AD-converted and input.

In the next step 22, the opening change amount ΔTVO of the throttle valve 7 per execution cycle of this routine is obtained based on the difference between the opening TVO input in step 21 at the previous execution of this routine and the input value this time, It is determined whether or not this variation ΔTVO is substantially zero.

When the change amount ΔTVO is substantially zero, the throttle valve 7 is not opened / closed and the opening degree TVO is maintained at a substantially constant value. Therefore, the transient operation state of the engine 1 is not discriminated. Proceed to 23.

In step 23, it is determined whether or not the change amount ΔN of the engine rotation speed N obtained in the same manner as the change amount ΔTVO is substantially zero. Here, when the change amount ΔN is substantially zero and there is no change in the opening TVO of the throttle valve 7 and the engine rotation speed N, it is assumed that the engine 1 is operating in a substantially steady state, and the next step 26 Determines whether the counter value cnt is zero.

On the other hand, when at least one of the change amount ΔTVO and the change amount ΔN is not substantially zero, the transient operation of the engine 1 is discriminated, the routine proceeds to step 24, where the transient flag Ftr is set to 1, and at step 25, ΔTVO and ΔN are set. Institution 1 determined from
A predetermined value (for example, 200) is set to the count value cnt for measuring the elapsed time after shifting to the steady operation of.

The count value cnt is not limited to the steady / transient operation of the engine 1, and when it is not zero, it is counted down by one every time this routine is executed in step 27.
If it is determined from ΔN and ΔN, a predetermined value is set in step 25, so that the predetermined value is maintained during transient operation.

On the other hand, when the operation shifts to the steady operation, the predetermined value is not set in step 25, so the value is gradually decreased each time this routine is executed, and when the count value cnt = 0 is determined in step 26, the process proceeds to step 28. Zero is set in the transient flag Ftr.

That is, even if the steady operation of the engine 1 is determined based on ΔTVO and ΔN, the transient flag Ftr is not immediately set to zero, but the time elapses until the engine 1 stabilizes to the true steady operation. The transient flag Ftr is set to zero. The first time that the transient flag Ftr is set to zero,
In the flowchart of FIG. 3, the process proceeds from step 12 to step 13 to learn and update the learning correction values a, b, c.

In the next step 29, the opening area A of the throttle chamber 4 is obtained based on the throttle valve opening TVO input in step 21. When a system for performing feedback control of the idle rotation speed by controlling the opening area of the auxiliary air passage provided by bypassing the throttle valve 7, the opening area for this auxiliary air passage is set to the opening area. A
It is desirable to add it to and correct it.

In step 30, the basic volume efficiency QHφ (%) of the engine 1 is calculated based on the value obtained by dividing the opening area A calculated in step 29 by the engine rotation speed N.

In the next step 31, the weighting weight X used in the weighted average calculation for making the basic volume efficiency QHφ follow the true engine load change is set based on the opening area A obtained in step 29.

Then, in step 32, the volumetric efficiency QCYL is set by weighted averaging the basic volumetric efficiency QHφ according to the following formula.

QCYL ← QHφ × X + QCYL (1-X) In step 33, the basic fuel injection amount (basic fuel injection amount) based on the opening area A and the engine speed N according to the following formula
Calculate Tp.

Tp ← QCYL × KTA × KCON × KFLAT where QCYL is the volumetric efficiency of the engine 1 obtained in step 32, K
TA is an intake temperature (air density) correction coefficient set based on the intake temperature TA in step 42 of the background job shown in the flowchart of FIG. 5, KCON is a constant based on the injection characteristics of the fuel injection valve 10, and KFLAT is the It is a minute correction coefficient obtained on the basis of the engine speed N and the volumetric efficiency QCYL in step 41 of the background job shown in the flowchart of FIG.

In the next step 34, the final fuel injection amount (fuel supply amount) Ti is calculated according to the following equation using the basic fuel injection amount Tp, the learning correction value learned in the routine shown in the flowchart of FIG. 3, and the like. Calculate

Here, the set fuel injection amount Ti is set in the output register, and at the predetermined fuel injection start timing, the latest fuel injection amount Ti set in this output register is set.
Is read and a drive pulse signal having a pulse width corresponding to the read fuel injection amount Ti is given to the fuel injection valve 10 to inject and supply fuel.

<Effects of the Invention> As described above, according to the present invention, in the internal combustion engine in which the basic fuel injection amount is controlled based on the opening area of the engine intake system and the engine rotation speed, dirt on the throttle valve, fuel injection valve Even if an air-fuel ratio deviation of different characteristics occurs due to deterioration of the fuel supply device or altitude change, it is possible to perform fuel correction corresponding to the cause of each air-fuel ratio deviation.
It is possible to improve the drivability by improving the air-fuel ratio controllability of the internal combustion engine without causing a step difference in the air-fuel ratio due to the operating state to deteriorate the drivability.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, and FIGS. 3 to 5 are flow charts showing the contents of fuel supply control in the same embodiment as above. 6 to 8 are diagrams for explaining the characteristics of the air-fuel ratio deviation due to the contamination of the throttle valve, and FIGS. 9 to 11 are the characteristics of the air-fuel ratio deviation when the fuel injection valve deteriorates. And FIGS. 12 and 13 are diagrams for explaining the characteristics of the air-fuel ratio deviation when there is a change in altitude, respectively. 1 ... Engine, 4 ... Throttle chamber 7 ... Throttle valve, 8 ... Throttle sensor 10 ... Fuel injection valve, 11 ... Control unit 14 ... Oxygen sensor, 15 ... Crank angle sensor

Claims (3)

[Claims] 1. A state quantity detecting means for detecting a state quantity respectively relating to an opening area of an engine intake system which is variably controlled and an engine rotation speed, and a basic fuel supply quantity is set based on the detected state quantity. Basic fuel supply amount setting means, air-fuel ratio detecting means for detecting the air-fuel ratio of the engine intake air-fuel mixture, and air-fuel ratio feedback for correcting the basic fuel supply amount so that the detected air-fuel ratio approaches the target air-fuel ratio. Air-fuel ratio feedback correction coefficient setting means for setting a correction coefficient, voltage correction amount setting means for setting a voltage correction amount for correcting the basic fuel supply amount according to a voltage change of a drive electrode of the fuel supply means, and A basic fuel supply amount, an air-fuel ratio feedback correction coefficient, and a voltage correction amount, a first learning correction value for correcting the basic fuel supply amount by a ratio of the opening area to a detected value, and the air-fuel ratio A second learning correction value for correcting the fed back correction coefficient,
A fuel supply setting means for calculating a fuel supply amount including at least a third learning correction value for correcting the voltage correction amount; and a fuel supply control for driving and controlling the fuel supply means based on the calculated fuel supply amount. Means, fuel operation storage means for respectively storing the calculated fuel supply amount and operation parameters of the fuel supply amount for at least three different operating states, and at least the fuel operation storage means stored in the fuel operation storage means. In the calculation of the three fuel supply amounts, when the air-fuel ratio feedback correction coefficient is used as a reference value, the first, second and third learning correction values are commonly applied to the calculation of the three fuel supply amounts. An air-fuel ratio learning control device for an internal combustion engine, comprising: learning correction value setting means that respectively learns and updates and sets as described above. 2. The three learning correction values set by the learning correction value setting means are averaged, and the three learning correction values thus averaged are used to determine the fuel supply amount by the fuel supply amount setting means. 2. The air-fuel ratio learning control device for an internal combustion engine according to claim 1, further comprising learning correction value averaging means for performing calculation. 3. A transient operation discriminating means for discriminating a transient operating state of the engine, and when the transient operating state of the engine is discriminated by the transient operating discriminating means, the learning correction value setting means sets three learning correction values. 3. An air-fuel ratio learning control device for an internal combustion engine according to claim 1, further comprising: learning correction value update prohibiting means for prohibiting update setting.