JPH0833119B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine, and more particularly to improvement of correction control of fuel supply amount during transient operation.

<Prior Art> The following is known as a fuel supply control device for an internal combustion engine. That is, the intake air flow rate and the intake pressure are detected as the state quantities related to the intake air, and the basic fuel supply amount Tp is calculated based on these. Then, the basic fuel supply amount Tp, various correction coefficient COEF set based on the operating state of the engine cooling water temperature, feedback set based on the air-fuel ratio obtained via the oxygen concentration detection value in the exhaust gas The final fuel supply amount Ti (Ti = Tp × COEF × LA) corrected by the correction coefficient LAMBDA, the correction amount Ts by the battery voltage, etc.
MBDA + Ts) is calculated, and the calculated fuel supply amount Ti of fuel is injected and supplied to the engine by the fuel injection valve.

<Problems to be Solved by the Invention> By the way, in such a device for calculating and setting the fuel supply amount to control the fuel supply, an air flow meter for detecting an intake air flow rate or an intake pressure detection during transient operation is used. In addition to the detection delay of the pressure sensor and the calculation delay of the fuel supply amount by the control device, a difference occurs in the intake air flow rate and the intake pressure between the calculation of the fuel supply amount and the subsequent opening of the intake valve. Therefore, for example, at the time of acceleration, the fuel supply amount set for the actual intake air flow rate and intake pressure (request fuel supply amount) becomes small, and the air-fuel ratio becomes the target air-fuel ratio (theoretical air-fuel ratio).
More lean than that, the emission amount of nitrogen oxide NOx and hydrocarbon HC increases, and acceleration shock and acceleration responsiveness deteriorate due to the response delay of the average effective pressure.

In view of this point, the present applicant has proposed in Japanese Patent Application No. 63-39711 the basic fuel injection amount calculated based on the throttle valve opening (the opening area of the intake system) and the engine speed (rotation speed). The acceleration / deceleration correction amount is set based on the difference between the basic fuel injection amount and the amount obtained by the phase advance processing, and the basic fuel supply amount calculated based on the intake air flow rate and the intake pressure is corrected by the acceleration / deceleration correction amount. A fuel injection device configured to do so has been proposed. Also, in Japanese Patent Application No. 62-269467, the fuel supply amount required when the intake valve is opened is estimated based on the rate of change in the opening area of the intake system, and the basic fuel supply is calculated based on the intake air flow rate and intake pressure. I have previously proposed a configuration that corrects the amount.

However, the basic fuel injection amount calculated based on the opening area of the intake system and the engine rotation speed is set to a value approximately commensurate with the amount of air passing through the throttle valve. It is not possible to set the fuel corresponding to the intake air filled in the. That is, especially when the engine is decelerated with a small amount of air taken into the cylinder, the amount of intake air filled into the intake manifold collector gradually shifts to an amount commensurate with the opening of the throttle valve, and the amount of air filled into the intake marihold collector is gradually increased. Therefore, the basic fuel injection amount calculated on the basis of the opening area of the intake system and the engine rotation speed is largely deviated from the required amount corresponding to the collector filling air.

Therefore, during the acceleration / deceleration operation of the engine, the basic fuel injection amount calculated based on the intake air state amount (intake air flow rate, intake pressure, etc.) is calculated based on the opening area of the intake system and the engine rotation speed. Even if the correction is performed according to the amount, it is difficult to perform the desired acceleration / deceleration correction with which good air-fuel ratio controllability can be obtained.

That is, when the engine is in the decelerating operation state as shown in FIG. 12, for example, at the point Z, the basic fuel injection amount Tp in the past 10 ms
Change time of D (basic fuel injection amount based on intake pressure) and time to target timing of fuel supply amount setting TATIME
Predicting the required fuel amount at the target timing based on (ms), the predicted decrease amount C of the required fuel amount with respect to the reference point of TATIME becomes B × TATIME / 10, and the deceleration / reduction amount is based on this predicted decrease amount. Even if the correction is applied, the predictive correction will have a worse response than the basic fuel supply amount TpD having a response delay. On the other hand, when the required fuel amount at the target timing is predicted based on the change amount of the basic fuel injection amount TpA calculated based on the opening area of the intake system and the engine rotation speed and the time TATIME, the basic fuel is calculated. Although there is no response delay in the injection amount TpA, there is a problem in that the reduction prediction of the required fuel amount (predicted reduction amount D) becomes excessive because the intake manifold collector filling amount cannot be detected as described above.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the correction control of the fuel supply amount at the engine acceleration / deceleration, and to provide a fuel supply control device that can obtain more accurate air-fuel ratio controllability. To do.

<Means for Solving the Problem> Therefore, in the present invention, as shown in FIG. 1, first basic fuel supply amount setting means for setting the basic fuel supply amount based on the state quantity of intake air, and the first basic fuel supply amount setting means. Separately from the basic fuel supply amount setting means of No. 1, the second basic fuel supply amount is set based on the opening area of the intake system and the engine speed that are variably controlled.
And a weighted average basic fuel supply amount calculation means for calculating a weighted average basic fuel supply amount by performing a weighted average of the basic fuel supply amounts set by the second basic fuel supply amount setting means. A weighted average control means for performing the weighted average calculation by the weighted average basic fuel supply amount calculation means in time synchronization or engine rotation synchronization according to a weighting constant according to the engine speed, and the weighted average basic fuel supply amount calculation means. Acceleration / deceleration correction amount setting means for setting an acceleration / deceleration correction amount for correcting and setting the basic fuel supply amount set by the first basic fuel supply amount setting means on the basis of the weighted average weighted average basic fuel supply amount. And an acceleration / deceleration correction hand for correcting and setting the basic fuel supply amount set by the first basic fuel supply amount setting means based on the acceleration / deceleration correction amount set by the acceleration / deceleration correction amount setting means. And a fuel supply amount setting means for setting the fuel supply amount based on the basic fuel supply amount corrected and set by the acceleration / deceleration correction means, and a fuel supply amount based on the fuel supply amount set by the fuel supply amount setting means. And a fuel supply control means for driving and controlling the means.

Here, as shown by the dotted line in FIG. 1, the correction setting of the basic fuel supply amount based on the acceleration / deceleration correction amount by the acceleration / deceleration correction means is performed when the opening degree of the throttle valve interposed in the engine intake system and the engine rotation change. It is preferable to provide correction control means for performing the change when the speed changes.

Further, as shown in FIG. 2, first basic fuel supply amount setting means for setting the basic fuel supply amount based on the state quantity of intake air, and separately from the first basic fuel supply amount setting means. Second basic fuel supply amount setting means for setting the basic fuel supply amount based on the opening area of the intake system and the engine speed that are variably controlled, and the basic set by the second basic fuel supply amount setting means. Weighted average basic fuel supply amount calculation means for calculating the weighted average basic fuel supply amount by weighted average of the fuel supply amount, and the change ratio of the weighted average basic fuel supply amount and the fuel supply amount by this weighted average basic fuel supply amount calculation means Acceleration / deceleration correction amount prediction setting means for predictively setting the required acceleration / deceleration correction amount based on the time to the set predetermined target timing, and the first based on the acceleration / deceleration correction amount predicted and set by the acceleration / deceleration correction amount prediction setting means. A basic fuel supply amount predicting / correcting means for correcting and setting the latest basic fuel supply amount set by the basic fuel supply amount setting means; and a basic fuel supply corrected / set by the basic fuel supply amount or the basic fuel supply amount predicting / correcting means. A fuel supply amount setting means for setting a fuel supply amount based on the fuel supply amount; and a fuel supply control means for drivingly controlling the fuel supply means based on the fuel supply amount set by the fuel supply amount setting means. The engine fuel supply control device was constructed.

Here, as shown by the dotted line in FIG. 2, the basic fuel supply amount correction setting based on the acceleration / deceleration correction amount by the basic fuel supply amount prediction correction means is set when the opening degree of the throttle valve interposed in the engine intake system changes. Also, correction control means for performing the change when the engine speed changes may be provided.

<Operation> In the fuel supply control device shown in FIG. 1, as the first basic fuel supply amount, the basic fuel supply amount is set based on the intake air state amount such as the intake air flow rate and the intake pressure, and
In addition to the first setting means, the basic fuel supply amount setting means sets the basic fuel supply amount based on the opening area of the intake system and the engine rotation speed. Then, the weighted average basic fuel supply amount calculation means calculates the weighted average basic fuel supply amount by performing a weighted average of the basic fuel supply amounts set by the second basic fuel supply amount setting means, and the weighted average basic fuel supply amount is calculated. The acceleration / deceleration correction amount setting means sets the acceleration / deceleration correction amount of the basic fuel supply amount based on the amount. Here, the weighted average control means performs the weighted average calculation by the weighted average basic fuel supply amount calculation means in time synchronization or engine rotation synchronization according to a weighting constant according to the engine rotation speed, and changes in synchronization with the engine rotation. Accurately follow changes in the true required fuel amount during acceleration / deceleration operation. In this way, by performing a weighted average calculation of the basic fuel supply amount based on the opening area and the engine rotation speed, the weighted average basic fuel supply amount corresponds to the intake manifold charging air amount change during the acceleration / deceleration operation of the engine. It is designed to obtain a followability close to the change in the required fuel amount, and the acceleration / deceleration correction amount is set based on the weighted average basic fuel supply amount that provides the change characteristics close to the change in the required fuel amount. Improve the accuracy of correction. The acceleration / deceleration correction means corrects the basic fuel supply quantity set by the first basic fuel supply quantity setting means, that is, the basic fuel supply quantity set based on the state quantity of intake air, based on the acceleration / deceleration correction quantity. Set.

The fuel supply amount setting means sets a final fuel supply amount based on the basic fuel supply amount corrected and set by the acceleration / deceleration correction means.

When the fuel supply amount is set, the fuel supply control means drives and controls the fuel supply means based on the fuel supply amount to control the actual fuel supply to the engine.

Further, the correction control means causes the basic fuel supply amount to be corrected and set based on the state quantity of the intake air when the opening degree of the throttle valve interposed in the engine intake system changes and when the engine rotation speed changes. This is not limited to acceleration / deceleration operation in which the opening of the throttle valve changes, but to ensure operational stability even when the throttle valve opening is substantially constant, for example, when the engine speed decreases due to clutch meet or the like. This is because it is necessary to correct the fuel supply amount.

Next, in the fuel supply control device shown in FIG. 2, the functions of the first basic fuel supply amount setting means, the second basic fuel supply amount setting means, and the weighted average basic fuel supply amount calculating means are the fuel supply shown in FIG. Since it is the same as the case of the control device, the description of the operation is omitted.

Here, the acceleration / deceleration correction amount prediction setting means is requested based on the change rate of the weighted average basic fuel supply amount calculated by the weighted average basic fuel supply amount calculation means and the time until the predetermined target timing of the fuel supply amount setting. The acceleration / deceleration correction amount is predicted and set, and the basic fuel supply amount prediction / correction unit is set based on the predicted acceleration / deceleration correction amount by the first basic fuel supply amount setting unit based on the state quantity of the intake air. Correct and set the basic fuel supply amount. That is, based on the change rate of the weighted average basic fuel supply amount showing the followability close to the true required fuel amount change, the change amount of the weighted average basic fuel supply amount up to the predetermined target timing of the fuel supply amount setting is obtained, The acceleration / deceleration correction amount is set such that this change amount corresponds to the required correction amount.

Then, as in the case of the fuel supply control device shown in FIG. 1, the fuel supply amount setting means sets the final fuel supply amount based on the basic fuel supply amount corrected and set based on the acceleration / deceleration correction amount, The fuel supply control means drives and controls the fuel supply means based on the fuel supply amount.

Here, as in the case of the fuel supply control device shown in the first drawing, the correction control means sets the correction setting of the basic fuel supply amount based on the state quantity of the intake air to the opening degree of the throttle valve interposed in the engine intake system. It is performed when the engine speed changes or when the engine speed changes.

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

In FIG. 3 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 for detecting an intake (atmospheric) 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 throttle valve 7 is provided with a potentiometer for detecting the opening TVO and a throttle sensor 8 including an idle switch 8A which is turned on at the fully closed position (idle position).

The intake manifold 5 downstream of the throttle valve 7 is provided with an intake pressure sensor 9 for detecting an intake pressure PB.
An electromagnetic fuel injection valve 10 is provided as fuel supply means for each cylinder. The fuel injection valve 10 is valve-opening driven by an injection pulse signal output from a control unit 11 including a microcomputer, which will be described later, in synchronization with, for example, ignition timing, and is pressure-fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator. The fuel thus injected is injected and supplied into the intake manifold 5. That is, the fuel supply amount by the fuel injection valve 10 is controlled by the valve opening drive time of the 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 oxygen sensor 14 for detecting the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas in the exhaust passage 13. Is provided.

The control unit 11 counts the crank unit angle signal POS output from the crank angle sensor 15 for detecting the engine rotation speed N in synchronization with the engine rotation for a certain period of time or the crank reference angle signal REF (180 in the case of four cylinders). The engine rotation speed N is detected by measuring the cycle TREF every (°).

In addition, the transmission attached to the engine 1,
A vehicle speed sensor 16 for detecting a vehicle speed and a neutral sensor 17 for detecting a neutral position are provided and are input to these signal control units 11.

Also, an auxiliary air passage 18 that bypasses the throttle valve 7
Is provided with an electromagnetic idle control valve 19 for controlling the idle rotation speed via the amount of auxiliary air.

The control unit 11 calculates the fuel injection amount Ti (pulse width of the injection pulse signal) based on the various detection signals detected as described above, and controls the fuel injection valve 10 based on the set fuel injection amount Ti. Open drive control. Furthermore,
The control unit 11 feedback-controls the idle rotation speed to the target idle rotation speed by controlling the opening of the idle control valve 19 during the idle operation detected by the idle switch 8A and the neutral sensor 17.

Next, the fuel injection amount Ti setting control by the control unit 11 will be described according to the routines shown in the flowcharts of FIGS.

In the present embodiment, the first basic fuel supply amount setting means,
Second basic fuel supply amount setting means, weighted average basic fuel supply amount calculation means, acceleration / deceleration correction amount setting means, acceleration / deceleration correction means,
The functions of the fuel supply amount setting means, the fuel supply control means, the acceleration / deceleration correction amount prediction setting means, the basic fuel supply amount prediction correction means, the weighted average control means, and the correction control means are shown in FIG.
It is provided as software as shown in the flowchart of FIG. Further, in this embodiment, the intake pressure PB detected by the intake pressure sensor 9 corresponds to the state quantity of the intake air, but an air flow meter such as a hot wire type is provided to change the intake air flow rate Q to the intake pressure PB. May be treated as

The engine 1 in this embodiment is a four-cylinder internal combustion engine, and it is premised that a fuel injection valve 10 is provided for each cylinder to sequentially control the fuel supply, but the number of cylinders is not limited, and The fuel injection may be controlled by simultaneous injection or group injection.

The fuel injection amount setting routine shown in the flowchart of FIG. 4 is executed every predetermined minute time (for example, 10 ms).

First, in step 1, the engine speed N, the intake pressure PB, the throttle valve opening TVO, the intake temperature TA, etc. detected based on the detection signals from the various sensors are input.

In the next step 2, the opening area A of the intake system of the engine 1 is calculated based on the throttle valve opening TVO input in step 1.
(M ² ) is obtained by a search or calculation from the map.
When determining the opening area A, the overall opening area of the intake system is determined by taking into consideration the opening area of the auxiliary air passage 18 controlled by the idle control valve 19 and the predetermined leak opening area of the idle adjusting screw or the like. It is desirable to be prepared.

In step 3, the volumetric efficiency Q _H φ is calculated or retrieved from the map based on the value A / N obtained by dividing the opening area A by the engine speed N. Then, in the next step 4, the basic fuel injection amount TpA based on the opening area A and the engine rotation speed N is calculated according to the following equation.

TpA = K _CONA × Q _H φ × K _FLATA where K _CONA is a constant and K _FLATA is the volume efficiency Q _H φ in step 72 of the correction coefficient setting routine (background job) shown in the flowchart of FIG. It is a minute correction coefficient set based on the engine rotation speed N.

In the next step 5, a weighting constant X (weighting for past data) used when arithmetically averaging the basic fuel injection amount TpA is calculated based on the engine speed N by searching or computing from a map. The weighting constant X is set to a larger value when the engine speed N is smaller, and the lower the engine speed when the air amount sucked into the cylinder is smaller, the more the past data is weighted and the basic fuel injection amount is increased. The change in TpA is blunted.

That is, for example, during deceleration operation of the engine 1, since the intake manifold collector charging air amount gradually changes to the air amount corresponding to this fully closed state after the throttle valve 7 is fully closed, the basic fuel supply amount TpA The value of is too small compared to the actual demand (see Fig. 12). For this reason, by setting the weighting constant X larger at low rotation speeds when the amount of air taken into the cylinder is small, the change in TpA is blunted, and the above-mentioned underdetection of TpA (excessive detection during acceleration) is suppressed, Weighted average basic fuel supply Tp
A _AV is designed to exhibit a followability close to the true required fuel amount (true change in intake air state amount).

When the weighted average calculation of the basic fuel injection amount TpA is executed at the timing synchronized with the engine rotation, the weighting constant X may be a constant value.

In step 6, using the basic fuel injection amount TpA calculated in step 4 and the weighting constant X calculated in step 5, the weighted average calculation of the basic fuel injection amount TpA is performed according to the following equation.

Here, the numerator TpA _AVOLd in the above calculation formula is the weighted average value TpA _AV of the basic fuel injection amount TpA calculated in step 6 at the time of the previous execution of this routine, and when the weighting constant X becomes large, this previously calculated weighted average is calculated. The weighting of the value TpA _AVOLd slows down the change of the weighted average value TpA _AV .

In the next step 7, the previous weighted average value TpA _AVOLd is subtracted from the latest weighted average value TpA _AV calculated in step 6 this time, and the change rate ΔTpA of the weighted average value TpA _AV per execution cycle (10 ms) of this routine. Find (= TpA _AV -TpA _AVOLd ).

At step 8, the calculation result TpA _AV at this step 6 is set to the previous value TpA _AVOLd in order to use it in the weighted average calculation at step 6 at the next execution of this routine.

In the next step 9, a flag F indicating which cylinder the fuel injection has ended in the sequential injection for supplying the fuel to each cylinder is determined. The flag F is
According to the routine shown in the flowchart of FIG. 6, each time the injection of each cylinder is completed, it is variably set corresponding to the cylinder number. For example, when the flag F is 1, the fuel injection of the # 1 cylinder is completed and This shows a state where fuel injection of the next fuel injection cylinder # 3 is not completed.

Here, the flag F shown in the flowchart of FIG.
The setting routine will be described. This routine is performed when the injection pulse signal sent to each fuel injection valve 10 falls (injection end Ti
end) and is executed when there is a fall of the corresponding injection pulse signal in any cylinder. First, in step 41, it is determined whether the engine 1 is in a rapid acceleration state or not. It is determined based on the change rate of the opening TVO.

When it is determined that the engine 1 is in the rapid acceleration state, the routine proceeds to step 42, where the interrupt injection pulse signal following the normal injection whose current injection end has been detected is immediately output. The pulse width of the interrupt injection pulse signal (interrupt injection amount) is 2 × ΔTpA
× Calculated with TATIME2 / 10. As described below, TATIME2 is the time ms until the nearest intake ATDC 100 °. In this case, TATIME2 is the intake ATDC 100 ° for the cylinder where fuel injection is completed.
It is the time until it becomes (a predetermined time of the intake valve open state).
Also, ΔTpA is 10 ms which is the execution cycle of the fourth illustrated routine.
Since it is the change rate of TpA during the period, ΔTpA × TATIME2 /
Reference numeral 10 is the predicted change amount of the basic fuel injection amount TpA from the end of injection to 100 ° of intake ATDC in the cylinder in which fuel injection has ended.

The intake ATDC 100 ° is a target timing for setting the injection amount in the increase / decrease correction and interrupt injection control during acceleration / deceleration in this embodiment, and the acceleration / deceleration is performed so that the fuel injection control corresponding to the required fuel amount at the set target timing can be performed. The goal is to set a correction amount.
Therefore, the amount of change in the basic fuel injection amount TpA up to the target timing is predicted, and the amount of change, that is, the excess or deficiency of the fuel injection amount, is supplemented by the interrupt injection following the normal injection. It should be noted that what is doubled is that the normal fuel injection amount Ti is calculated by 2 × effective injection amount Te (value obtained by correcting the basic fuel injection amount Tp with various correction coefficients) + voltage correction amount Ts as described later. Because it is done.

After the interrupt injection (after the output of the interrupt injection pulse signal) following the end of the normal injection during the rapid acceleration as described above, or when it is determined in step 41 that the engine 1 is not in the rapid acceleration, the routine proceeds to step 43.

In step 43, it is determined whether or not the current fuel injection end is in the # 1 cylinder, and if it is the injection end of the # 1 cylinder, the routine proceeds to step 44, where the flag F is set to 1, and # The flag F indicates that the fuel injection of one cylinder is completed and the fuel injection of the next injection cylinder # 3 is not completed.

When it is determined in step 43 that the injection of the # 1 cylinder is not completed, the routine proceeds to step 45, where it is determined whether the injection of the # 3 cylinder, which is the injection timing subsequent to the # 1 cylinder, is completed. Here, if it is determined that the injection is completed at the # 3 cylinder, the flag F is set to 3 in step 46, and
When it is not the time to finish the injection in the three cylinders, the routine proceeds to step 47, where it is judged whether or not it is the time to finish the injection in the # 4 cylinder, which is the injection timing next to the # 3 cylinder.

Here again, if the injection of the # 4 cylinder is completed, the process proceeds to step 48 to set the flag F to 4 in the same manner as described above.
When it is determined that the injection of the # 4 cylinder has not been completed, it means that the injection of the remaining # 2 cylinder has been completed, so the routine proceeds to step 49, where the flag F is set to 2.

Returning again to the routine shown in the flowchart of FIG. 4, in step 9, it is determined whether or not the flag F set as described above is 1. Here, when it is determined that the flag F is 1, it means that the injection of the # 1 cylinder has been completed and the injection of the # 3 cylinder, which is the next injection cylinder, has not been completed. Advance,
Intake ATDC10 which is the target timing for setting the injection amount (acceleration / deceleration correction amount) in the increase / decrease correction and the interrupt injection control
Time to 0 ° (target angle time) TATIME, TA
Set TIME2.

First, in step 10, the time Tm # 3CYL until the intake ATDC 100 ° in the next injection cylinder # 3 is set to TATIME, and in the next step 11, the intake ATDC 100 ° of the # 1 cylinder in which normal fuel injection is finished. Time to Tm # 1 CYL TATIM
Set to E2. Therefore, the TATIME indicates the time until the intake ATDC 100 ° (100 ° after the intake top dead center) which is the target timing of the fuel injection control in the cylinder where the injection is next ended, and TATIME2 is the time when the injection has just ended. It shows the time until the intake ATDC becomes 100 ° in the cylinder.

The Tm # 3CYL and Tm # 1CYL are set according to the routine shown in the flowchart of FIG. 7, including Tm # 2CYL and Tm # 4CYL used for other cylinders.

The routine shown in the flowchart of FIG. 7 is executed by interruption at intake TDC (intake top dead center) of each cylinder, and the crank reference angle signal output from the crank angle sensor 15 every 180 ° in the case of four cylinders. REF is, for example, BTDC80 °
If it is set to be output by, the intake angle TDC is detected and executed by counting the unit angle signal POS from the reference angle signal REF.

When the intake TDC is detected, first, at step 61, it is judged if the current intake TDC is the # 1 cylinder. Such a determination can be performed, for example, by making one of the reference angle signals REF output from the crank angle sensor 15 distinguishable from the other, so that each reference angle signal REF corresponds to each cylinder.

When it is determined in step 61 that the # 1 cylinder is the intake TDC, the routine proceeds to step 62, where the time from the current intake TDC to the intake ATDC 100 ° in each cylinder is set according to the following formula.

Here, TREF is an interval time of the reference angle signal REF output from the crank angle sensor 15, and the engine 1 is 180 °.
The time it took to spin. This intake TDC is # 1
Since it is a cylinder, since the crank angle is 100 ° after the intake ATDC of the # 1 cylinder is 100 °, the time required for the engine 1 to rotate 100 ° is the time T until the intake ATDC of the # 1 cylinder is 100 °.
m # 1 CYL. Similarly, for the # 3 cylinder, which is the injection timing next to the # 1 cylinder, the intake ATD after rotating by 180 °
Since C is 100 °, the time required to rotate 280 ° at 100 ° + 180 ° is the time to intake ATDC 100 ° of the # 3 cylinder Tm # 3
It becomes CYL. Similarly, Tm # 4CYL and Tm # 2CYL are obtained as described above.

On the other hand, if it is determined at step 61 that the current intake TDC is not the # 1 cylinder, the routine proceeds to step 63, where it is determined whether the current intake TDC is the # 3 cylinder. When it is the intake TDC of the # 3 cylinder, the process proceeds to step 64, and the time Tm # 1CYL to Tm # 4CYL from the intake TDC of the # 3 cylinder to the intake ATDC 100 ° of each cylinder is calculated in the same manner as in step 62 described above. .

Further, when it is determined in step 63 that the intake TDC of this time is not the # 3 cylinder, the process proceeds to step 65, and it is determined whether or not the intake TDC is the # 4 cylinder in accordance with the injection (ignition) cylinder order, and the # 4 cylinder is determined. Step 6 when the intake TDC of the cylinder
In step 6, similar to steps 62 and 64 above, # 4 intake TD
Time from C to intake ATDC 100 ° for each cylinder Tm # 1 CYL to Tm #
Calculate 4CYL.

When it is determined in step 66 that the intake TDC this time is not the # 4 cylinder, it is not the # 1 cylinder, # 3 cylinder, or # 4 cylinder, so it is the intake TDC of the # 2 cylinder. At this time, the routine proceeds to step 67. Then, the time Tm # 1CYL to Tm # 4CYL from the intake TDC of the # 2 cylinder to the intake ATDC of 100 ° of each cylinder is calculated in the same manner as in steps 62, 64 and 66 described above.

The time Tm # 1CYL to Tm # 4CYL from the predetermined intake TDC set in this way to the intake ATDC 100 ° of each cylinder is the 8th
1 every 1 ms according to the routine shown in the flowchart in the figure
The time from a certain time point to the nearest intake ATDC 100 ° of each cylinder from a certain time point is detected by Tm # 1CYL to Tm # 4CYL.

Now, returning to the flowchart of FIG. 4 again, when it is determined in step 9 that the flag F is 1, it is after the end of injection of the # 1 cylinder and before the end of injection of the # 3 cylinder, and # 1 cylinder intake ATDC10
There is a time Tm # 1CYL (TATIME2) by 0 °, and a time Tm # 3CYL (TATIME) by the intake ATDC 100 ° of the next injection cylinder # 3. Therefore, during the acceleration / deceleration operation of the engine 1, the acceleration / deceleration of the fuel injection amount corresponding to the above time up to the absorption ATDC 100 °, which is the target timing for setting the injection amount in the acceleration / deceleration correction and the interrupt injection control, is performed. Correction is required.

Therefore, in step 10, the time Tm to the intake ATDC 100 ° of the # 3 cylinder, which is the cylinder where the fuel injection is next completed, is performed.
# 3CYL is set to TATIME, and in the next step 11, time Tm to intake ATDC 100 ° of # 1 cylinder for which fuel injection has already ended is set to Tm # 1CYL is set to TATIME2. Based on TATIME and TATIME2, the acceleration / deceleration correction amount and the interrupt injection amount are set as described later.

On the other hand, when it is determined in step 9 that the flag F is not 1, it is determined in step 12 whether the flag F is 3 or not. When the flag F is 3, it means that after the fuel injection of the # 3 cylinder is completed and before the fuel injection of the # 4 cylinder is completed, similarly to the steps 10 and 11, the step # 4 is performed in the step 13.
The time Tm # 4CYL to the intake ATDC 100 ° of the cylinder is set to TATIME, and in the next step 14, the time Tm # 3CYL to the intake ATDC 100 ° of the # 3 cylinder is set to TATIME2.

Further, if it is determined in step 12 that the flag F is not 3, the process proceeds to step 15 and it is determined whether or not the flag F is 4. When the flag F is 4, it means that after the fuel injection of the # 4 cylinder is completed and before the fuel injection of the # 2 cylinder is completed, the step # 2 is executed in the step 16 as in the steps 10 and 11.
Cylinder intake ATDC 100 ° Time Tm # 2 CYL is set to TATIME, and in the next step 17, intake ATDC 100 ° of # 4 cylinder
Set time Tm # 4 CYL to TATIME2.

Further, when it is determined in step 15 that the flag F is not 4, the flag F should be 2. Therefore, after the fuel injection of the # 2 cylinder and before the end of the fuel injection of the # 1 cylinder,
At this time, in step 18, the intake ATDC of the # 1 cylinder is 100 °
Time to Tm # 1 CYL is set to TATIME and next step
In 19 the time Tm # 2 CYL to the intake ATDC 100 ° of the # 2 cylinder is T
Set to ATIME2.

In this way, according to the determination of the flag F, the time TATIME2 to the intake air ATDC 100 ° of the cylinder just finished the fuel injection,
Next, when the time TATIME until the intake ATDC of the cylinder at which fuel injection ends becomes 100 ° is set, the routine proceeds to step 20, and the acceleration / deceleration operation of the engine 1 is performed based on the opening change rate ΔTVO of the throttle valve 7. Determine the state.

The opening change rate ΔTVO may be obtained as the difference between the throttle valve opening TVO input in step 1 during the previous execution of this routine and the current input value.

Then, at step 20, the throttle valve opening change rate ΔTVO
It is determined that the absolute value of is not substantially zero, and if the engine 1 is in the acceleration / deceleration operation state in which the opening of the throttle valve 7 is changing, the routine proceeds to step 22. In step 22, the acceleration / deceleration correction amount DLTTP for increasing / decreasing the basic fuel injection amount TpD calculated based on the intake air pressure PB which is the state quantity of the intake air and the engine rotation speed N is based on ΔTpA and the TATIME. calculate.

Further, even when it is determined in step 20 that the absolute value of the throttle valve opening change rate ΔTVO is substantially zero and it is determined that the engine 1 is not in the acceleration / deceleration operation state, the process proceeds to step 21 and the opening change is performed. When it is determined that the change rate ΔN of the engine rotation speed N obtained in the same manner as the rate ΔTVO is not zero, the process also proceeds to step 22 and the acceleration / deceleration correction amount DLTTp is calculated. This is because even if the opening TVO of the throttle valve 7 is substantially constant, for example, when the engine rotation speed N decreases due to a clutch meet or the like, acceleration / deceleration correction of the fuel injection amount is performed to improve the operational stability of the engine 1. This is because it is necessary to secure it.

On the other hand, when it is determined in step 20 that the throttle valve opening change rate ΔTVO is substantially zero, and when it is determined in step 21 that the change rate ΔN of the engine rotation speed N is also substantially zero, the acceleration / deceleration correction is performed. Since it is not necessary, the routine proceeds to step 23, where the acceleration / deceleration correction amount DLTTP is set to zero.

The acceleration / deceleration correction amount DLTTp in step 22 is calculated according to the following equation.

Here, ΔTpA is the amount of change in 10 ms of the value TpA _AV , which is the weighted average of the basic fuel injection amount TpA calculated based on the opening area A of the intake system and the engine speed N, and TATIME is , The intake ATDC100 of the cylinder where the injection is finished next
Since the time is up to °, the acceleration / deceleration correction amount DLTTp is
Next, it is the amount of change in the weighted average basic fuel injection amount TpA _AV from the present time of the cylinder where fuel injection ends to the intake ATDC 100 °, which is the target timing for setting the correction amount. Therefore, for example, when the flag F is 1 and the injection of the # 1 cylinder is completed, the # for the latest basic fuel injection amount Tp is #.
The required fuel injection amount for the three cylinders requires + DLTTp.

Here, the basic fuel injection amount TpA set based on the opening area A and the engine rotation speed N does not accurately follow the change in the intake manifold collector charging air amount during the acceleration / deceleration operation, but the basic fuel injection amount TpA is weighted. The TpA _AV obtained by averaging is a value close to the required basic fuel supply amount by substantially following the change in the intake manifold charging air amount, so the change ratio ΔTpA of the weighted average basic fuel injection amount TpA _AV and the target timing are The acceleration / deceleration correction amount DLTTp, which is predicted and set based on the time TATIME up to a certain intake ATDC 100 °, can be set to a value substantially commensurate with the required correction amount during the acceleration / deceleration operation of the engine 1. Therefore, this acceleration / deceleration correction amount DLTT
By correcting the basic fuel injection amount TpD set based on the intake pressure PB using p, the accuracy of fuel supply control during the acceleration / deceleration operation of the engine 1 is improved, and the acceleration / deceleration operability is improved.

When the acceleration / deceleration correction amount DLTTp is set as described above, the next step 24 is the intake pressure input in step 1.
Based on PB, the volumetric efficiency K _PB is obtained by a map search or calculation.

In the next step 25, the basic fuel injection amount TpD based on the intake pressure PB which is the state quantity of the intake air is calculated according to the following equation.

TpD = K _COND x PB x K _PB x K _FLATD x KTA where K _COND is a constant and K _FLATD is the intake pressure PB and engine speed in step 73 of the routine (background job) shown in the flowchart of FIG. The small correction coefficient KTA set based on N is also the intake temperature correction coefficient set based on the intake temperature TA in step 71 of the routine shown in the flowchart of FIG.

In the next step 26, the throttle valve opening change rate ΔTVO
Based on the above, it is determined whether the engine 1 is in the rapid acceleration operation state. When it is determined that the engine 1 is not in the rapid acceleration state based on the opening change rate ΔTVO, the process proceeds to step 27. In step 27, the basic fuel injection amount TpD calculated based on the intake pressure PB in step 25 is added to step 22 or step 23.
The acceleration / deceleration correction amount DLTTp set in step 2 is added and corrected to set the final basic fuel injection amount Tp.

When the weighted average value TpA _AV of the basic fuel injection amount TpA is changing in the decelerating operation state of the engine 1, the acceleration / deceleration correction amount DLTTp becomes a negative value and the basic fuel injection amount TpD decreases. Although corrected, the acceleration / deceleration correction amount DLTTp is a positive value in the operating state during acceleration of the engine 1, so the basic fuel injection amount TpD is increased and corrected.

On the other hand, when it is determined in step 26 that the engine 1 is in the rapid acceleration operation state, the routine proceeds to step 28, where it is determined whether or not the rapid acceleration determination in step 26 is the first time. Here, if it is the first time for the rapid acceleration determination, the routine proceeds to step 29, where the interrupt injection amount to be added to the normal injection is calculated and immediately output in order to perform the interrupt injection at the time of sudden acceleration.

The injection amount of the interrupt injection in step 29 is 2 × ΔTpA
× TATIME2 + Ts is calculated, and the change amount of the weighted average basic fuel injection amount TpA _AV during the time until the intake ATDC of the cylinder just after the normal fuel injection reaches 100 ° is set as the interrupt injection amount. There is. However, the Ts is
This is for correcting the change in the effective valve opening time of the fuel injection valve 10 due to the change in the voltage of the battery.

That is, at the first time when the rapid acceleration operation of the engine 1 is determined, until the cylinder at which normal fuel injection is completed reaches the intake ATDC of 100 °, the intake ATDC is started from that point on the cylinder for which injection has been completed.
Weighted average basic fuel injection amount T up to 100 °
The amount corresponding to the change amount of pA _AV is injected separately from the normal injection, and in the rapid acceleration operation state,
Following the routine shown in the flow chart of FIG. 6, ΔTpA (weighted average basic fuel injection amount T
Interrupt injection based on pA _AV change rate) is performed, and when not in rapid acceleration operation state (slow acceleration, deceleration, steady operation),
The correction setting of the basic fuel injection amount TpD based on the acceleration / deceleration correction amount DLTTp in step 27 is performed.

Then, in step 30, the fuel injection amount Ti used for fuel injection at normal timing is set according to the following formula.

Ti = 2Tp × LAMBDA × KBLRC × (COEF + TpKFUEL) + Ts Where, Tp is the correction result when the basic fuel injection amount TpD based on the intake pressure PB is corrected in step 27, and step 27 In this case, the basic fuel injection amount TpD set based on the intake pressure PB is used as it is. Further, the LAMBDA, the air-fuel ratio detected via the oxygen concentration in the exhaust detected by the oxygen sensor 14,
This is the air-fuel ratio feedback correction coefficient for feedback control to the target air-fuel ratio (theoretical air-fuel ratio) when the predetermined feedback control condition is satisfied. The deviation from the reference value of this air-fuel ratio feedback correction coefficient LAMBDA is learned and obtained without LAMBDA. The learning correction coefficient that is learned so that the base air-fuel ratio becomes the target air-fuel ratio is the KBLRC.

Further, the COEF is various correction factors and is mainly set based on the cooling water temperature Tw, and at the time of starting or low water temperature (when cold)
In order to improve drivability, the fuel injection amount Ti is increased and the air-fuel ratio is increased by various corrections.

Further, TpKFUEL is a wall flow correction coefficient for correcting a response delay during acceleration / deceleration operation of the wall flow (liquid fuel flowing along the inner wall of the intake passage).
TpKFUEL is set according to the routine shown in the flowcharts of FIGS.

The routine shown in the flowchart of FIG. 9 is executed every predetermined minute time (for example, 10 ms).
In step 91, the acceleration / deceleration operation state of the engine 1 is determined depending on whether or not the throttle valve opening change rate ΔTVO is substantially zero.

When it is determined in step 91 that the opening change rate ΔTVO is not zero and the engine 1 is in the acceleration / deceleration operation state, the routine proceeds to step 93, where the opening change rate ΔTVO is substantially zero and the throttle valve 7 is at a constant opening. During a certain steady operation, it is determined in step 92 whether the rate of change ΔN of the engine rotation speed N is substantially zero. When it is determined in step 92 that the rotational speed change rate ΔN is not zero, in step 91 the opening change rate ΔTVO.
The process proceeds to step 93 in the same manner as when it is determined that is not zero.

In step 93, the cooling water temperature detected by the water temperature sensor 12
The correction coefficient K is set by multiplying the coefficients obtained based on Tw and the engine rotation speed N, respectively. In the next step 94, the coefficient K, the variation ΔTpA of the weighted average basic fuel injection amount TpA _AV in 10 ms obtained in the flowchart of FIG. 4, and the crank angle sensor 15 output the crank angle every 180 °. The wall flow correction coefficient B is set according to the following equation based on the output interval time TREF of the reference angle signal REF.

B ← K × ΔTpA × TREF / 10 That is, the wall flow correction coefficient B is the weighted average basic fuel injection amount TpA between the crank angles of 180 ° which is the injection interval in the sequential injection control of the four-cylinder internal combustion engine of the present embodiment.
_The correction amount based on the cooling water temperature Tw and the engine rotation speed N is added to the variation amount of _AV .

On the other hand, it is determined in step 92 that the rotational speed change rate ΔN is substantially zero, and the opening change rate ΔTVO and the rotational speed change rate ΔN are determined.
When the engine 1 is in a stable operating state in which both and are substantially zero, the routine proceeds to step 95, where the wall flow correction coefficient B is set to zero.

Then, in the next step 96, the absolute value of the wall flow correction coefficient B obtained as described above and the absolute value of the wall flow correction coefficient A obtained for each reference angle signal REF according to the routine shown in the flowchart of FIG. When | B | is greater than | A |, the routine proceeds to step 97, where B is set as the final wall flow correction coefficient TpKFUEL, and when | A | is greater than or equal to | B |, it proceeds to step 98. Go to A for the final wall flow correction factor TpKF
UEL is set so that the larger absolute value of A and B is set as the wall flow correction coefficient TpKFUEL.

The routine shown in the flow chart of FIG. 10 is executed every time the reference angle signal REF is output from the crank angle sensor 15. First, in step 101, the wall flow correction at the time of the execution of this routine last time (before the crank angle 180 °). The value of 1 / X 'of TpKFUEL _OLD is subtracted from TpKFUEL _OLD which is the value of coefficient TpKFUEL, and the subtraction result is defined as the wall flow correction coefficient A. That is,
The wall flow correction coefficient A is a value obtained by multiplying the wall flow correction coefficient TpKFUEL at a crank angle of 180 ° before by (X′−1) / X ′. Incidentally, X'is the cooling water temperature in the routine (background job) shown in the flowchart of FIG.
It is variably set according to Tw, and X'is set to a smaller value in the cold state where the cooling water temperature Tw is low, so that the change of the wall flow correction coefficient A becomes more blunt.

After setting the wall flow correction coefficient A with the switch 101, in the next step 102, the current wall flow correction coefficient TpKFUEL is set as the previous value TpKFUEL _OLD for the calculation in step 101 at the time of execution of the next routine.

In this way, the wall flow correction coefficient B, which is set based on the latest data for each minute time, is compared with the wall flow correction coefficient A, which is obtained by reducing the past wall flow correction coefficient TpKFUEL for each crank angle of 180 °. The larger absolute value finally becomes the wall flow correction coefficient Tp
By setting as KFUEL, the wall flow correction coefficient TpKFUEL
It is possible to prevent the absolute value of () from suddenly decreasing and changing to disturb the air-fuel ratio.

By the way, the fuel injection amount Ti at the normal timing set in step 30 is updated and set in the output register at any time,
At the injection timing, the latest fuel injection amount Ti set in this output register is read out, and the fuel injection amount Ti
An injection pulse signal having a pulse width corresponding to is output to the corresponding fuel injection valve 10, and the fuel injection supply by the fuel injection valve 10 is controlled.

In this embodiment, the intake ATDC 100 ° is set as the injection amount setting target timing, but the intake ATDC 100 ° is not limited to the intake ATDC 100 °, and may be variably set according to the characteristics of the engine 1.

<Effect of the Invention> As described above, according to the present invention, the basic fuel supply amount set based on the opening area of the engine intake system and the engine rotation speed is synchronized with the time synchronization or the engine according to the weighting constant according to the engine rotation speed. The weighted average basic fuel supply amount is synchronized with the rotation, and the weighted average basic fuel supply amount follows the change in the required amount according to the change in the intake manifold collector charging air amount during acceleration / deceleration operation. The acceleration / deceleration correction amount set by the above can be adapted to the required correction amount. Therefore, by correcting the basic fuel supply amount set based on the intake air state amount such as intake air flow rate and intake pressure based on the acceleration / deceleration correction amount, the fuel control accuracy in the engine acceleration / deceleration operation state is improved. Thus, the acceleration / deceleration drivability is improved.

Further, as described above, the acceleration / deceleration correction amount is set based on the amount of change in the weighted average basic fuel supply amount that follows the required amount change during acceleration / deceleration operation and the time to the target timing for setting the fuel supply amount. Thus, the acceleration / deceleration correction amount can be set more accurately in accordance with the required fuel amount.

[Brief description of drawings]

1 and 2 are block diagrams showing the configuration of the present invention, respectively, and FIG. 3 is a system schematic diagram showing an embodiment of the present invention.
4 to 11 are flowcharts showing the control contents of the fuel supply in the above embodiment respectively, and FIG. 12 is a time chart for explaining the problems of the conventional acceleration / deceleration correction control. 1 ... Engine, 6 ... Intake air temperature sensor, 7 ... Throttle valve, 8 ... Throttle sensor, 9 ... Intake pressure sensor, 10
...... Fuel injection valve, 11 ...... Control unit, 15 ......
Crank angle sensor

Claims (3)

[Claims] 1. A first basic fuel supply amount setting means for setting a basic fuel supply amount based on a state quantity of intake air, and an intake air variably controlled separately from the first basic fuel supply amount setting means. Second basic fuel supply amount setting means for setting the basic fuel supply amount based on the opening area of the system and the engine rotation speed, and the basic fuel supply amount set by the second basic fuel supply amount setting means are weighted. A weighted average basic fuel supply amount calculation means for calculating the weighted average basic fuel supply amount on average, and a weighted average calculation by the weighted average basic fuel supply amount calculation means are time-synchronized with the weight constant according to the engine speed or the engine. Weighted average control means for performing rotation synchronization, and basic fuel set by the first basic fuel supply amount setting means based on the weighted average basic fuel supply amount weighted averaged by the weighted average basic fuel supply amount calculation means. Acceleration / deceleration correction amount setting means for setting an acceleration / deceleration correction amount for correcting and setting the fuel supply amount, and the first basic fuel supply amount based on the acceleration / deceleration correction amount set by the acceleration / deceleration correction amount setting means. Acceleration / deceleration correction means for correcting and setting the basic fuel supply amount set by the setting means, and fuel supply amount setting means for setting the fuel supply amount based on the basic fuel supply amount corrected and set by the acceleration / deceleration correction means, A fuel supply control device for an internal combustion engine, comprising: a fuel supply control means for driving and controlling the fuel supply means based on the fuel supply quantity set by the fuel supply quantity setting means. 2. An intake air which is variably controlled separately from a first basic fuel supply amount setting means for setting a basic fuel supply amount based on a state quantity of intake air and the first basic fuel supply amount setting means. Second basic fuel supply amount setting means for setting the basic fuel supply amount based on the opening area of the system and the engine rotation speed, and the basic fuel supply amount set by the second basic fuel supply amount setting means are weighted. Weighted average basic fuel supply amount calculating means for calculating the weighted average basic fuel supply amount on average, change rate of the weighted average basic fuel supply amount by the weighted average basic fuel supply amount calculating means, and predetermined target timing for setting fuel supply amount Acceleration / deceleration correction amount prediction setting means for predictively setting the required acceleration / deceleration correction amount based on the time until, and the first basic fuel supply amount based on the acceleration / deceleration correction amount predicted and set by the acceleration / deceleration correction amount prediction setting means. Setting means Basic fuel supply amount predicting / correcting means for correcting and setting the latest basic fuel supply amount set in 1., and fuel supply for setting the fuel supply amount based on the basic fuel supply amount corrected / corrected by the basic fuel supply amount predicting / correcting means. A fuel supply control device for an internal combustion engine, comprising: an amount setting means; and a fuel supply control means for driving and controlling the fuel supply means based on the fuel supply amount set by the fuel supply amount setting means. 3. A correction setting of the basic fuel supply amount based on the acceleration / deceleration correction amount by the acceleration / deceleration correction unit or the basic fuel supply amount prediction correction unit when the opening of a throttle valve interposed in an engine intake system is changed, and 3. The fuel supply control device for an internal combustion engine according to claim 1 or 2, further comprising correction control means for performing a change in engine speed.