JPH02271039A - Fuel supply controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent failure in setting the amount of compensation and deterioration in an air-fuel ratio controlling ability caused thereby by setting the amount of compensation for fuel supply through the amount of engine load variation and through the time it takes to a predetermined crank angle position, and by prohibiting compensation at the time of low rotation. CONSTITUTION:The amount of fuel supply is set by a fuel supply amount setting means B based on the intake amount or intake pressure by a driving condition detecting means A and the engine rotational speed. The amount of engine load variation is determined by an engine load variation calculating means C, based on the intake system opening area and on the engine rotational speed, while the amount of compensation for the fuel supply is determined by a compensation amount calculating means D based on the time H it takes from the calculation to a predetermined crank angle position. When the compensation amount exceeds a predetermined limit amount, the compensation amount is controlled to a predetermined value by a compensation amount control means E. The control is performed by a fuel supply control means F based on the compensated amount of fuel supply. When the engine rotational speed is not more than a predetermined value, compensation can be forced to be prohibited by a compensation prohibiting means G. Deterioration in air-fuel ratio control ability can thus be prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine, and more particularly to a device that improves transient operation performance by increasing control accuracy of fuel supply amount during transient operation. .

<Prior Art> The following types of fuel supply control devices for internal combustion engines are known.

That is, the intake air flow rate and intake pressure are detected as B quantities related to the intake air of the engine, and the basic fuel supply amount Tp is calculated based on these and the detected value of the engine rotation speed. Then, the basic fuel injection amount Tp is set based on various correction coefficients C0EF set based on operating conditions such as the engine cooling water temperature Tw, and an air-fuel ratio set based on the air-fuel ratio obtained through detection of the oxygen concentration in the exhaust gas. Fuel ratio feedback correction coefficient LAMBD
A, Calculate the final fuel injection iTi by correcting it with the correction numerator s etc. based on the battery voltage that is the driving power source of the fuel injection valve (Ti-TpXCOEFXLAMBDA+TS)
The calculated fuel injection amount Ti is intermittently supplied to the engine by a fuel injection valve or the like.

By the way, in such a fuel supply control device, during transient operation, there is a delay in the detection of the air flow meter for detecting the amount of intake air and a pressure sensor for detecting the intake pressure, and a delay in the calculation of the fuel supply amount by the control device. There is a problem in that the intake air flow rate and intake pressure change from the final setting of the fuel supply amount (start of supply) until the intake stroke in which the supplied fuel is actually drawn. For this reason, for example, during acceleration, the amount of fuel supplied is set to be smaller than the actual amount of intake air and intake pressure, which causes the air-fuel ratio of the intake mixture to become overly lean, reducing the amount of hydrocarbons HC and nitrogen oxides NOx in the exhaust gas. The increase in the concentration of fuel will cause acceleration shock and deterioration of acceleration response due to a delay in the response of the average effective pressure due to lean misfire.

In view of this, the applicant has proposed to improve the accuracy of fuel supply control during transient operation by predicting the intake air condition (engine load change) during transient operation and correcting the fuel supply amount based on the prediction. A fuel supply control device that can be improved has previously been proposed (see Japanese Patent Application No. 62-269467).

As mentioned above, when correcting the fuel supply amount based on the prediction of the intake air condition during transient operation, the engine load fluctuation amount is calculated based on the throttle valve opening and the engine rotation speed, and the Crank angle position W (
This is the target crank angle position for fuel supply amount control, for example, the intake BDC position. ), and based on the current amount of fluctuation, predict how much the engine load will change until it reaches the predetermined crank angle position of the intake stroke where the air-fuel mixture is actually taken in. In order to cope with the excess or deficiency in the fuel supply amount, the normal fuel supply amount, which is controlled based on the detected values of the intake air flow rate Q and the intake pressure PB, is corrected based on the predicted amount. .

<Problems to be Solved by the Invention> However, as described above, in the structure in which the amount of change in engine load is predicted up to a predetermined crank angle position and the fuel supply amount is corrected, the amount of change in engine load is predicted. Even if the crank angle is the same, the prediction time is longer at low rotations than at high rotations, so there is a risk that the error in the predicted amount will be large at low rotations.

Here, if the correction amount is set too low due to a prediction error, the air-fuel ratio controllability will be improved compared to when no correction is performed at all, but as shown in Figure 11, the correction amount may be set too high due to the prediction error. When this setting is made, there is a problem in that the air-fuel ratio controllability deteriorates, which adversely affects transient drivability and exhaust properties.

The present invention has been made in view of the above-mentioned problems, and improves transient drivability at low engine speeds by avoiding excessive correction of fuel supply amount due to prediction errors in engine load fluctuations at low engine speeds. The purpose is to improve.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, an operating state detection means for detecting state quantities related to either the intake air amount or the intake pressure and the engine rotational speed is provided. and a fuel supply amount setting means for setting the fuel supply amount based on the state quantity detected by the operating state detection means, and an engine load fluctuation amount based on the opening area of the engine intake system and the engine rotation speed which are variably controlled. an engine load fluctuation calculation means for calculating the engine load fluctuation amount, a time calculation means for calculating the time from when the engine load fluctuation amount is calculated to a predetermined crank angle position, and a time calculation means for calculating the engine load fluctuation amount and the time from the time to the predetermined crank angle position. a correction amount calculation means for calculating a correction amount of the fuel supply amount based on the correction amount calculation means; and a correction amount for correcting and setting the correction amount to a predetermined limit amount when the correction amount calculated by the correction amount calculation means exceeds a predetermined limit amount. The fuel supply control means includes a limiting means and a fuel supply control means for controlling the fuel supply to the engine based on the fuel supply amount that is obtained by correcting the fuel supply amount based on the correction amount.

Here, as shown by the dotted line in FIG. 1, it is preferable to provide a limit amount variable setting means for variably setting a predetermined limit amount in the correction amount limiting means depending on the engine operating state.

Furthermore, in place of the correction amount limiting means, as shown by the dotted line in FIG. may be provided.

<Operation> According to this configuration, the fuel supply amount is set by the fuel supply amount setting means, which is related to either the intake air amount or the intake pressure detected by the operating state detection means and the engine rotational speed.

On the other hand, the engine load fluctuation amount calculation means calculated the engine load fluctuation amount based on the opening area of the variably controlled engine intake system and the engine rotation speed, and the time calculation means calculated the engine load fluctuation amount. The time from the time to the predetermined crank angle position is calculated.

Further, the correction amount calculation means calculates the correction amount of the fuel supply amount based on the engine load fluctuation amount and the time to a predetermined crank angle position. Here, when the calculated correction amount exceeds a predetermined limit amount, the correction amount is corrected and set to the predetermined limit amount by the correction amount limiting means, and the correction amount is not set to exceed the predetermined limit amount. do it like this.

Then, the fuel supply control means controls the fuel supply to the engine based on the fuel supply amount that is obtained by correcting the fuel supply amount based on the correction amount.

Further, the limit amount variable setting means variably sets the limit amount of the correction amount limited by the correction amount limiting means according to the engine operating state, so that the correction amount is limited to an amount commensurate with the engine operating state. .

Furthermore, when a correction prohibition means is provided, instead of limiting the range of amounts that the correction amount can take, it is possible to forcibly correct the fuel supply amount based on the correction amount when the engine speed is below a predetermined value. This prevents the fuel supply amount from being corrected based on an excessive correction amount due to a prediction error.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing the system configuration of one embodiment, an internal combustion engine 1 includes an air cleaner 2. Air is taken in through the intake duct 3, the throttle chamber 4, and the intake manifold 5. The air cleaner 2 has an intake air (atmospheric) temperature TA ("
An intake air temperature sensor 6 is provided to detect C). The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q. The throttle valve 7 has its opening degree TV.
A throttle sensor 8 including an idle switch 8A that is turned ON at its idle position is attached along with a potentiometer that detects O.

The intake manifold 5 downstream of the throttle valve 7 is provided with an intake pressure sensor 9 that detects the intake pressure PB.
An electromagnetic fuel injection valve 10 is provided for each cylinder.

The fuel injection valves 10 are individually driven to open by injection pulse signals output from a control unit 11 built in a microcomputer (to be described later) for each cylinder in synchronization with the intake stroke of each cylinder. Fuel controlled to a predetermined pressure by a pressure regulator 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 driving time of the fuel injection valve 10.

Furthermore, a water temperature sensor 12 for detecting the cooling water temperature Tw in the cooling jacket of the engine 1 is provided, and the exhaust passage 1
An oxygen sensor 14 is provided within the engine 3 to detect the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas.

The control unit 1 counts the crank unit angle signal PO3 output from the crank angle sensor 15 in synchronization with engine rotation for a certain period of time or outputs a crank reference angle signal REF (4 cylinders) at each predetermined crank angle position. In this case, the engine rotational speed N is detected by measuring the period TREF (every 180').

In addition, the transmission attached to the engine 1 is provided with a vehicle speed sensor 16 for detecting the vehicle speed and a neutral sensor 17 for detecting the neutral position, and these signals are input to the control unit 11. A voltage signal from a battery 20, which is a power source for opening the engine, is input to the control unit 11 via an ignition switch 21.

Additionally, an auxiliary air passage 18 bypassing the throttle valve 7
is provided with an electromagnetic idle control valve 19 that controls 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 also calculates the fuel injection amount Ti for each cylinder based on the set fuel injection amount Ti. The injection valves 10 are individually controlled to open (sequential injection control). Further, the control unit 1 feedback-controls the idle rotation speed to the target idle rotation speed by controlling the opening degree of the idle control valve 19 during idle operation detected based on the idle switch 8A and the neutral sensor 17.

Next, various calculation processes for fuel control performed by the control unit 11 will be explained according to the routines shown in the flowcharts of FIGS. 3 to 9, respectively.

In this embodiment, the fuel supply amount setting means.

Engine load fluctuation amount calculation means 1 hour calculation means, correction amount calculation means, fuel supply control means, correction amount limiting means.

The functions of the limit amount variable setting means and the correction prohibition means are provided in the form of software as shown in the flowcharts of FIGS. 3 to 9, respectively.

Further, in this embodiment, the engine operating state detection means is the intake pressure sensor 9. This corresponds to the crank angle sensor 15 and the like.

The routine shown in the flowchart of FIG. 3 is executed every predetermined minute period (for example, 10 m5). First, in step 1, the opening degree TVO of the throttle valve 7 detected by the throttle sensor 8 is converted into an A/D converter. and enter.

In step 2, based on a value obtained by multiplying the intake pressure PB detected by the intake pressure sensor 9 and the engine rotational speed N calculated based on the detection signal from the crank angle sensor 15, a preset map is Find 2 by searching for the volumetric efficiency correction coefficient.

The volumetric efficiency correction coefficient 2 is a coefficient for correcting the basic volumetric efficiency QHφ, which is determined depending on the opening area A, in accordance with the true engine load fluctuation, as will be described later.

In step 3, the opening area A that is variably controlled by the throttle valve 7 of the engine 1 intake system is searched from the map based on the throttle valve opening degree TVO input in step 1, and this opening area A is It is divided by the speed N, and the basic volumetric efficiency QHφ is searched in the next step 4 based on the result of this division.

In step 4, the basic volumetric efficiency QHφ is retrieved from the map based on the A/H calculated in step 3. Then, in step 5, the basic volumetric efficiency QHφ obtained by searching in step 4, the volumetric efficiency QCYLO calculated in step 5 during the previous execution of this routine, and the volumetric efficiency correction coefficient obtained by searching in step 2. 2 and calculate the final volumetric efficiency QCYL according to the formula below.

QCYL4 - QHφ and the volumetric efficiency QCY according to the engine load condition at that time.
This will slow down the change in L relative to the Ma-Nbu search value,
As a result, the volumetric efficiency QCYL is set that substantially corresponds to the actual engine load change that is delayed with respect to the change in the opening area A and the engine rotational speed N with little detection delay.

In step 6, the basic fuel injection amount Tpqcy4 (engine load parameter) is calculated based on the volumetric efficiency QCYL according to the opening area A and the engine rotational speed N according to the following formula.

Tpqcyf←KCONAXQCYLXKTA2 Here, KCONA is a constant, QCYL is the volumetric efficiency calculated in step 5 above, and KTA2 is based on the intake air temperature TA ('C) detected by the intake air temperature sensor 6 in the background job (BGJ) described later. The intake air temperature (
air density) correction factor.

In the next step 7, from the basic fuel injection amount (basic fuel supply amount) Tpqcyf calculated in step 6 this time, the basic fuel injection amount M T pqcy 1 calculated in step 6 when this routine was executed last time (10 ms ago) is subtracted to obtain the basic fuel injection amount Tpqc per execution cycle of this routine.
Calculate the amount of change DLTTp (engine load fluctuation amount) in yl.

In the next step 8, the engine rotation speed N is compared with a predetermined value (for example, 600 rpm), and when the engine rotation speed N is higher than the predetermined value, the process proceeds to step 9 and the change amount DLTTp calculated in step 7 is calculated as the final value. However, when the engine speed N is lower than a predetermined value,
Proceeding to step 10, the change amount Z is set to zero, and fuel correction control based on the change amount Z (DLTTp) is prohibited.

This means that when the engine speed N is low, such as below a predetermined value, the basic fuel injection amount T pqcy 12 up to the target timing for setting the fuel supply amount for each cylinder is based on the current change amount Z (DLTTf+). When predicting the amount of change, the prediction time is longer than when the rotation is high, and a large prediction error is likely to occur, and if the amount of correction based on this prediction error is too large, the air-fuel ratio controllability will deteriorate. be.

As described later, the amount of change Z is equal to the engine 1 required fuel amount (
Based on this change ilZ, the interrupt injection amount (additional injection amount performed separately from normal injection) is set and the correction amount of the normal fuel injection amount Ti is set. .

As a measure to avoid excessive correction based on prediction errors when the engine 1 is running at low speeds, in addition to the configuration that forcibly sets the change tz to zero and prohibits correction as described above when the engine 1 is running at low speeds, the calculated amount of change The final change amount Z may be set by limiting DLTTp within a predetermined limit amount, so that an excessive correction amount is not set even if the prediction time becomes longer.

Such control is shown in the flowchart of FIG. 3 as a flow proceeding from step 7 in the direction A.

When the change amount DLTTp is calculated in step 7, in step a, the lower limit amount LOWLMT, which is the limit amount on the negative side that is preset for each operating state divided into multiple parts depending on the engine rotational speed N and the intake pressure PB, and the positive side The upper limit i1HILMT, which is the limit amount of , is determined by searching the map.

Then, in the next step b, the upper limit amount H1, LMT searched in step a and the change amount DLT calculated in step 7 are calculated.
Comparing with Tp, the amount of change DLTTp is the upper limit 31HI L
When exceeding MT, proceed to step C and change the amount of change DL.
TTp is corrected to the upper limit amount HI LMT, and the upper limit i1
HI Prevents the amount of change DLTTp from being set exceeding LMT.

In addition, in step d, the lower limit amount L searched in step a
Compare OWLMT with the amount of change DLTTp calculated in step 7, and if the amount of change DLTTp is less than the lower limit amount LOWLMT, proceed to step e, correct and set the amount of change DLTTp to the lower limit amount LOWLMT, and set the amount of change DLTTp to the lower limit amount LOWLM.
Change 11DLTTp below T is not set.

The amount of change DL limited within the upper and lower mass sales limits as described above
TTp is finally set to the amount of change Z in step f.

In this way, if the amount of change DLTTp is set to be within the upper and lower mass sales limits set from the engine rotational speed N and the intake pressure PB, even if the engine rotation speed is low and the prediction time is long, However, since the amount of change Z during acceleration and deceleration is estimated to be smaller than the actual amount, the amount of change in the basic fuel injection amount T pqey l up to the target timing is oversized by 1! This is something that can be avoided.

During normal fuel supply, the wall flow (fuel adhering to the wall of the intake passage) reaches an equilibrium state with an amount corresponding to the engine load at that time, but when fuel supply stop control is performed during deceleration operation, the wall flow This is drastically reduced compared to when fuel is supplied. For this reason, when accelerating immediately after stopping fuel supply, it is necessary to perform fuel control by estimating the rate of change in the basic fuel injection amount T I)qCyβ higher than usual. In some cases, it is preferable to increase the amount of change Z.

As mentioned above, when the rotation is low below a predetermined value, the amount of change Z is set to zero to prohibit correction, or the change NZ is limited to an amount within the upper and lower mass sales limits, and when the rotation is low, After processing is performed to prevent the correction amount from being set excessively based on the prediction error, the process proceeds to step 11.

In step 11, the basic fuel injection amount T pqcy 42 calculated in step 6 this time is set to the previous value MTpqcyj2.
The next time this routine is executed, the current basic fuel injection amount T pqcy R is set as the previous value and the change amount DLT is set.
Let Tp be calculated.

Then, in step 12, it is determined whether the amount of change Z set as described above is zero.

Here, when it is determined that the change 1z is approximately zero (including when the amount of change is set to zero in step 10 at a predetermined low rotation speed), the change 1z approximately corresponds to the true engine load. Since the basic fuel injection amount T pqcy (l is stable at a substantially constant value, it can be assumed that the engine 1 is in a steady operating state. In this case, the process advances to step 13 and the steady operating state is set in the transient flag Ftr. Set zero to indicate.

Further, in the steady operation determination state of the engine 1, in the next step 14, the interrupt injection amount y1 corresponding to each cylinder is determined. ~y44 and normal injection correction amount y1~y4
(The engine 1 in this embodiment has four cylinders, and the suffix indicates the cylinder number) are all set to zero so that the transient correction control of the fuel supply amount according to the change amount Z is not performed.

The above interrupt injection amount Yx-Van and normal injection correction amount y
, ~y4 corresponds to the correction amount of the normal fuel supply amount in this embodiment.

That is, when the engine 1 is in a steady operating state, the amount of fuel required by the engine 1 (the amount of air taken into the cylinder) is approximately constant, so the amount of fuel set according to the engine operating state at a predetermined fuel injection timing is Injection MTi is almost the same as the true engine required amount that appears in the intake stroke after the start of injection, even if there is a detection delay of various sensors, and the injection start timing (final setting of fuel injection amount) and the true engine required fuel amount are Even if there is a time difference from the timing when the engine appears, it is possible to inject and supply fuel that matches the engine demand, so when steady operation is determined as described above, interrupt injection ffi)' II~y
Aa and the normal injection correction amount yI-y4 are all set to zero, and correction control of the fuel supply amount corresponding to the time difference is not performed.

On the other hand, when it is determined in step 12 that the amount of change Z is not approximately zero, there is a change in the basic fuel injection amount T pqcy 1, and as described above, the difference between the injection start timing and the timing at which the true engine required fuel amount appears. Because this is a transient operating state where there is a delay in the response of fuel supply control due to timing,
Proceed to step 15 and subsequent steps and interrupt injection amount y, ~'/a
a and the normal injection correction amount ylI~"Jaa.

That is, during transient operation of the engine 1 where the amount of intake air increases or decreases, the amount of intake air corresponding to the amount of intake air at a predetermined fuel injection start timing and the true required fuel amount of the engine 1 that appears in the intake stroke after the start of injection. Since a deviation will occur between the two due to the passage of time, the change in the required fuel amount (excess/deficiency of the fuel supply amount) according to the deviation is expressed as the amount of change in the basic fuel injection amount Tpqcyj2, which is Z. Based on this prediction, the system attempts to eliminate response delays in fuel supply control during transient operation, including slow acceleration/deceleration states.

In step 15, it is determined whether the transient flag Ftr is zero or one. The transient flag Ftr is set to zero in step 13 during steady operation of the engine 1 when the amount of change Z is determined to be approximately zero in step 12, so the first time the transition from steady to transient operation is , in step 15, it is determined that the transient flag Ftr is zero.

At the first time of such transient determination, in step 16, interrupt injection 'l Y , ~y44 (additional injection amount of fuel to be performed during normal injection) is performed for each cylinder (#1cyj!~#4cyj2). ) is calculated according to the following formula.

y ++”TatmlX Z xl/10x Ktwa
ccX 2y zz”Tatm2X Z X 1/10
x K twaccX 2)' a:+←Tatm3X
Z XI/IOX K twaccX 2)/44
(-Tatm4X Z XI/IOX K twacc
X 2 In the above calculation formula, Tatml ~ Tatm
4 represents the target timing time (ms) for each cylinder, which is the time from the current time to the target timing (predetermined crank angle position) for setting the fuel supply amount for each cylinder. Note that the target timing is a target crank angle position in the intake stroke at which an amount of intake air corresponding to the true required amount appears, and in this embodiment, it is the intake BDC.

Further, K twacc is a water temperature correction coefficient that is set according to the cooling water temperature Tw that is representative of the engine temperature detected by the water temperature sensor 12. At the first time of transient (acceleration) discrimination,
Since the above-mentioned interrupt injection amounts y, ~y44 are injected and supplied separately from the normal fuel injection supply, the water temperature Tw
If correction is not made in accordance with the water temperature, it will not be possible to draw the desired amount into the cylinder when the engine is cold due to changes in the wall surface adhesion amount, etc. (This is why the water temperature correction coefficient K twac is multiplied.

Furthermore, the amount of change Z is 10 m, which is the execution cycle of this routine.
5 is the amount of change in the basic fuel injection amount Tpqcyj2 (basic fuel injection amount based on the opening area A and the engine rotational speed N), while Tatml to Tatm4 indicates the time up to the target timing in nts units. from,
By multiplying the amount of change Z by 1710, it is converted into the amount of change per 1 ms.

Furthermore, in the fuel supply control device in this embodiment, as will be described later, for convenience of calculation, the normal fuel injection MTi is calculated by doubling the basic fuel injection amount TPI)b based on the intake pressure PB. Therefore, it is necessary to multiply by 2 accordingly.

However, when the change IZ (change amount DLTTp) is a negative value during deceleration and the correction request is on the negative side, the interrupt injection amount Vz~y44 is set to zero, or the interrupt injection amount yz~ The negative operation of y44 prevents interrupt injection from actually occurring.

Interrupt injection calculated in this way'] V +
I~y44 is the basic fuel injection amount T pqcy f! in the time from the current moment to the target timing of each cylinder. , that is, the amount of change in the engine required fuel amount up to the target timing, is predicted and set for each cylinder. This indicates that the interrupt injection amount ylI-y44 is insufficient in the cylinder due to the accelerated operation of the engine 1 at least from the current point in time.

In step 16, set the interrupt injection amount y, ~yaa 1
Then, in the next step 17, the normal injection correction amount y1 to y
Let each of 4 be zero. That is, at the first time of transient determination (acceleration determination) of the engine 1, interrupt injection (additional supply control) is used to cope with the response delay in fuel supply due to acceleration operation, and a correction for the response delay is added to the normal fuel injection amount Ti. Control (normal supply correction control) is not performed.

In the next step 18, the transient flag Ftr is set to 1 in response to the transient determination in the current step 12, so that the continuation state of the transient operation is determined by the transient flag Ftr.

Then, in step 19, it is determined whether or not normal fuel injection is being performed in any cylinder, and if normal fuel injection is being performed in any cylinder, main injection control is performed without executing interrupt injection control. The routine is ended as is, but if normal fuel injection is not being performed in any cylinder, the corresponding interrupt injection amount)'++-144 of fuel is interrupted for the cylinder immediately after normal fuel injection has ended. The process proceeds to step 22 and subsequent steps in order to inject the fuel.

On the other hand, when it is determined in step 15 that the transient flag Ftr is 1, a transient (acceleration) determination is performed in step 12 based on the change 1z, and the flag setting in step 18 has been performed before the previous time. Since it is a transient continuation determination state, instead of correcting the response delay of fuel supply control by interrupt injection, normal fuel injection 11 is performed.
A correction for the response delay is added to Ti. Therefore, at this time, the routine proceeds to step 20, and normal injection correction amounts y1 to y4 used for increasing/decreasing correction of the normal fuel injection amount Ti are calculated according to the following formula.

y, 4-TatmlX Z Xi/10V zz-
Tatm2X Z Xi/10y s*”Tatm3X
Z xi/10y 4. +Tatm4X Z XI/
10 Here, Tatml to Tatm4 are interrupt injection'
fk )' The time until the target timing of setting the fuel supply amount for each cylinder (m
s), and this time Tatml-Tatm4 and 1m
By multiplying by ZXI/10, which is the amount of change in the basic fuel injection amount T pqcy l per s, the change in the required fuel amount from the current time to the target timing is predicted and set for each cylinder.

However, in the calculation of the normal injection correction amounts y, to y4, the interrupt injection amounts y1. The reason why the multiplied temperature correction coefficient K twacc is not used in the calculation of ~y44 and is not doubled is this normal injection correction amount)'I"")
'a is added to the basic fuel injection amount T ppb calculated based on the intake pressure PB as described later, and this addition result is doubled and further corrected based on the cooling water temperature Tw to obtain the final value. The fuel injection amount Ti is calculated.
This is because

Note that the normal injection correction amount y is calculated using the above formula.

~y4 becomes a positive value when the engine 1 accelerates, and the normal injection amount is corrected to increase, but when the engine 1 decelerates, it becomes a negative value and the normal injection amount is corrected to decrease.

When the normal injection correction amount)'I-3'4 is calculated in step 20, in the next step 21, the interrupt injection amount yII~
Set Y44 to all zeros. As a result, when the engine 1 continues in a transient state, the normal injection correction if y + to y is applied to the fuel injection performed at the normal timing instead of the interrupt injection.
4 is applied so that correction corresponding to the fuel control response delay during transient times is applied.

Here, to explain again by returning to step 19, the transient (
When determining the initial acceleration (acceleration), the interrupt injection amount y, ~y44
is calculated and set, and it is determined in step 19 whether or not there is a cylinder in which normal fuel injection is being performed at this time. If it is determined here that there is no cylinder in which normal fuel injection is being performed, Then, the process proceeds to step 22, where it is determined whether or not a predetermined time (for example, 1 ms) or more has elapsed since the normal fuel injection.

Then, whether or not to add a voltage correction numerator s for correcting an invalid injection amount due to a delay in the operation of the fuel injection valve 10 according to the battery voltage to the interrupt injection amounts y11 to Yaa is switched according to the determination result. do.

That is, when performing interrupt injection corresponding to the transient response delay, the control process corresponds to the closing operation delay time of the fuel injector 10 from the valve closing drive control (when the drive pulse signal is OFF) of the fuel injector 10 in normal fuel injection. If it is within a predetermined time (a time shorter than the time from when the drive pulse signal is turned off to when the fuel injection valve 10 is actually fully closed), interrupt injection will be performed following normal injection. The desired amount can be injected without making a correction using the voltage correction numerator s as a measure against the delay in opening the valve, and the voltage correction numerator s ends up being over-corrected.

On the other hand, if more than the predetermined time has elapsed since the end of normal fuel injection, the same conditions as normal injection (fuel injection valve 10
The fuel injection valve 10 will be opened when the fuel injection valve 10 is opened (fully closed state), and unless the operation delay is corrected by the voltage correction numerator s, an interrupt injection drive pulse with a pulse width equivalent to the interrupt injection amount y, 1 to y44 will be given. This is because, in reality, only an amount of fuel smaller than the set amount will be injected.

Whether the current time is within a predetermined time from the end of normal fuel injection control is determined by the count value cnt, which is incremented by 1 every 1 ms, as described later, and the count value cnt at the end of normal injection control (drive pulse). (when the signal is OFF) Tiend
This is done by comparing the value cntota at . Since the count value cnt is counted and amplified every 1 ms as described above, cnt and cn
The fact that t, , , are not equal means that there is a difference of at least 1 between them and at least 1 ms from Tiend.
Indicates that the above has passed.

Therefore, when it is determined in step 22 that cnt=cntoLa, the state is such that less than 1 ms has elapsed since the normal injection end time Tiend or the end time Tiend, so the process advances to step 23 and subsequent steps to interrupt the injection amount. Interrupt injection is controlled without adding the voltage correction numerator s to y, to y44. On the other hand, in step 22, cnt
When it is determined that =I=cntota, at least 1 ms or more has elapsed since the end of normal injection T1end, so the process advances to step 3° and thereafter to determine the interrupt injection amount y1. ~y44 voltage correction numerator s
is added to control interrupt injection.

In this way, at the interrupt injection timing which is the first time of transient determination, if a predetermined time period corresponding to the operation delay of the fuel injection valve 10 or more has elapsed from the end of normal fuel injection control, and under the same conditions as normal fuel injection control, When it is necessary to control the opening drive of the fuel injection valve 10, by adding the voltage correction numerator s and performing correction according to the operation delay of the fuel injection valve 10, the target timing time Ta tml to Tatm4 and the amount of change Z Interrupt injection Ill V set accurately based on
+ 1-3' a a of fuel can actually be injected and supplied, and the actual amount of injected fuel will not be insufficient due to a delay in the operation of the fuel injection valve 10.

Further, when interrupt injection is performed following normal fuel injection within a predetermined time from the end of normal fuel injection control, there is no need for increase correction by the voltage correction numerator s, and the voltage correction valve Ts
If the voltage correction numerator s is added, the actual supply amount will become larger than the set amount, so the interruption injection of an excessive amount is prevented by not adding the voltage correction numerator s.

Here, to explain the interrupt injection control that is continuous to normal fuel injection and is performed without adding the voltage correction numerator s, in step 23, the injection discrimination flag for #1 cylinder F I C
Determine whether YL is 1 or zero. When the #1 cylinder injection discrimination flag FICYL is 1, the cylinder to which fuel is to be injected at the next predetermined injection timing is #1.
When the injection discrimination flag FICYL for the #1 cylinder is 1, the injection discrimination flag F2CYL for the #2 cylinder to the injection discrimination flag F for the #4 cylinder, which will be described later, is used.
4CYL is set to zero. The setting of the injection discrimination flag FICYL for the #1 cylinder to the injection discrimination flag F4CYL for the #44 cylinder will be described in detail later.

In the four-cylinder internal combustion engine 1 of this embodiment, the fuel' injection is #1c
3f! →#3cyj! -+#4cyj2-+#! 2cy
Since the injection is performed every 180 degrees of crank angle in the order of f, when the #1 cylinder injection discrimination flag F I CYL is 1, the #2 cylinder has finished normal injection.

Therefore, when it is determined in step 23 that the flag F I CYL is 1, the process proceeds to step 24 and interrupt injection is performed in the #2 cylinder. That is, in step 24, #
A drive pulse signal with a pulse width corresponding to the interrupt injection amount y2□ is output to the fuel injection valve 1o provided in the second cylinder, and an interrupt injection corresponding to response delay correction of fuel control is performed following normal fuel injection. By performing this in the #2 cylinder, normal fuel injection and the interrupt injection amount Vzt for correcting the response delay are inhaled in the recent intake stroke.

As mentioned above, the interrupt injection performed on the #2 cylinder is performed based on the amount of change in the fuel requirement from immediately after the normal injection in the #2 cylinder to a predetermined target timing in the intake stroke of the #2 cylinder. As a result, when accelerating, an amount equivalent to the response delay is additionally injected into #2 cylinder, where normal fuel injection has already ended, resulting in a lean air-fuel ratio at the beginning of acceleration due to the fuel control response delay. is suppressed.

If the configuration is configured such that the next fuel injection start timing is waited for in the first acceleration determination, and the normal fuel injection amount is corrected according to the response delay, the cylinder that has already started fuel injection in the first acceleration determination Since it is not possible to compensate for the response delay in the above-mentioned intake stroke, it is possible to effectively prevent the air-fuel ratio from becoming lean at the beginning of acceleration by inhaling the response delay correction bone fuel separately from the normally supplied fuel during the recent intake stroke. That's what I do.

Further, if it is determined in step 23 that the flag F I CYL is zero, the process proceeds to step 25, and this time #33
It is determined whether the cylinder injection flag F3CYL is 1 or zero. Here, when it is determined that the flag F3CYL is 1, it is a state in which fuel should be injected into the #3 cylinder at the next injection timing and it is immediately after the end of injection in the #1 cylinder, so in this case, step 26 Proceed to #1
A drive pulse signal with a pulse width corresponding to interrupt injection 1 y++ is output to a fuel injection valve 10 provided in a cylinder, and an interrupt corresponding to response delay correction of fuel control is performed following normal fuel injection.

Further, if it is determined in step 25 that the flag F3CYL is zero, the process proceeds to step 27, where it is determined whether the injection specific flag F4CYL for the #44 cylinder is 1 or zero. Here, if it is determined that the flag F4CYL is 1, step 28 is performed in the same manner as described above.
By proceeding to , the fuel injection valve 10 of the #3 cylinder is caused to perform an interrupt injection corresponding to the interrupt injection amount y33.

When it is determined that the flag F4CYL is zero in step 27, the remaining injection specific flag F2CY for the #22 cylinder
Since L should be 1, proceed to step 29 and perform interrupt injection 11"l for the fuel injection valve 10 of the #4 cylinder.
a) Perform interrupt injection equivalent to 4.

As described above, when it is the first time of transient discrimination and it is still within a predetermined time from the end of normal fuel injection, the interrupt injection amount yII-y44 set for the cylinder for which the normal injection has just ended is applied. This allows interrupt injection to be performed accordingly.

On the other hand, when it is determined in step 22 that cnt≠cntotd, unless the voltage correction numerator s is added to the interrupt injection amounts y11 to 3'44 as described above, the amount of fuel equivalent to the interrupt injection amounts yz to y44 will actually be reduced. Since no injection is provided, each interrupt injection m )' Il-V 4 a
An interrupt injection drive pulse signal with a pulse width corresponding to the sum of the voltage correction numerator s and the voltage correction numerator s is output to the fuel injection valve 10 provided in each cylinder. This is the same as when it is determined that

First, in step 30, the #1 cylinder injection discrimination flag F
Determine whether I CYL is 1 or zero. Here flag F1. If CYL=1, the normal injection of the #2 cylinder has ended and the state is waiting for the next fuel supply to the #1 cylinder, so the process advances to step 31 and the interrupt set for the #2 cylinder is executed. An interrupt drive pulse signal having a pulse width corresponding to the value obtained by converting the voltage correction numerator s to the injection amount y2□ is output to the fuel injection valve 10 provided in the #2 cylinder.

Thereafter, the calculation processing in steps 32 to 36 is performed in the same manner, and the interrupt injection amount y1 is determined for the cylinder where normal fuel injection has been completed. Interrupt injection is performed with a pulse width corresponding to the value obtained by adding the voltage correction numerator s to ~y44.

In this way, when the transient determination is performed for the first time and more than a predetermined time has elapsed since the end of normal injection, the operation delay of the fuel injector 10 by the voltage correction molecule s is performed in the same manner as normal injection control. Interrupt injection is performed by correcting the time, so that fuel corresponding to the response delay is accurately additionally injected into the cylinder after normal injection.

In addition, in the routine shown in the flowchart of FIG. 3 above,
If any cylinder is in the middle of normal fuel injection at the first time of transient determination, the routine is supposed to end without performing an interrupt injection, but in such a situation,
When the fuel injection in the cylinder currently injecting is completed according to the routine shown in the flowchart of FIG. 4 (actually, when the drive pulse signal is OFF), in step 22, cnt =
Interrupt injection similar to that when it is determined that cn to ta is performed is performed. However, such interrupt injection after waiting for the end of normal injection is executed only when normal injection ends within 10 m5 (execution cycle of the flowchart shown in the third figure) after the initial determination of transient operation, and If the normal injection does not end within the time, the control is switched to correction control based on the normal injection correction jlVI-Ya for the next normal injection.

The routine shown in the flowchart of FIG. 4 is executed when there is valve closing drive control in any of the drive pulse signals output for each fuel injection valve 10. First, in step 41, #1 Cylinder injection discrimination flag F I
Determine whether CYL is 1 or zero. If it is determined that the flag F I CYL is 1 here, fuel will be injected and supplied to the #1 cylinder at the next injection timing, and the current drive pulse signal OFF is set to #1. This indicates that the fuel supply control was for two cylinders. For this reason, in step 41 the flag FICYL=
If it is determined that the value is 1, the process proceeds to step 42, where an interrupt injection drive pulse signal having a pulse width equivalent to the interrupt injection amount y2□ is output to the fuel injection valve 10 of the #2 cylinder.

The above-mentioned interrupt injection control is performed in step 23 described above.
〜This is the same as step 29, so the following steps 43〜
47 will be omitted.

When the interrupt injection control for the cylinder that has finished normal fuel injection during execution of this routine ends, in step 48, 1
The current value of the counter value cnt which is amplified by 1 every ms is c
ntotd, so that the determination in step 22 is made based on this cntota.

Note that when the transient operation of the engine 1 continues and the normal injection correction t y + to y4 is set in step 2°, and the interrupt injection amounts y11-y44 are set to zero in the next step 21, the main luatin This prevents interrupt injection from occurring. Also, when it is determined in step 12 that the engine 1 is in steady operation based on the change NZ, the interrupt injection according to the routine shown in FIG. 4 is not performed.

Next, according to the routine shown in the flowchart of Fig. 5, the setting control of the fuel injection amount (fuel supply amount) Ti used for normal fuel injection control (sequential fuel supply control) performed in accordance with the timing of the intake stroke of each cylinder is performed. explain.

The routine shown in the flowchart of FIG. 5 is executed at predetermined minute intervals of about 10 m5. First, in step 51, the basic volumetric efficiency correction coefficient Kpb is calculated based on the intake pressure PB detected by the intake pressure sensor 9. is determined by searching from a preset map.

In the next step 52, a minute correction coefficient KFL set in a background job to be described later is added to the basic volumetric efficiency correction coefficient Kpb obtained by searching from the map in step 51.
Multiply by AT and correct it to obtain the final volumetric efficiency correction coefficient KQ
CYL (←K pb X KFLAT) Calculate.

In the next step 53, the basic fuel injection amount Tppb is calculated based on the intake pressure PB according to the following formula.

Tppb4-KCONDX F' B XKQCYLX
K T A where KCOND is a constant, PB is the intake pressure detected by the intake pressure sensor 9, KQCYL is the volumetric efficiency correction coefficient set in step 52 above, KTA
is an intake air temperature correction coefficient that is set based on the intake air temperature TA in a background job to be described later.

Then, in the next step 54, the fuel injection amounts Til to Ti4 for each cylinder are calculated according to the following formulas.

Ti1=2(Tppb-t-y+)XCOEFxL
AMBDA+ T 5Ti2←2(Tppb 10 y z
)XCOEFXLAMBDA+ T sT i3'-
2(T ppb + Y x) X C0EF X L
AMBDA 10T sT i4←2(Tppb + ”
/ 4) X C0EF X LAMBDA + T
s In the above equation, T ppb is calculated from step 53 above.
The basic fuel injection amount calculated based on the intake pressure PB,
3'I""V4 is the normal injection correction amount for each cylinder calculated in step 20 of the flowchart of FIG. Further, C0EF is various correction coefficients set according to the engine operating state mainly based on the cooling water temperature Tw detected by the water temperature sensor 12, and LAMBDA is the correction coefficient of the engine intake air-fuel mixture detected via the oxygen sensor 14. This is a feedback correction coefficient for bringing the air-fuel ratio closer to the target air-fuel ratio. Furthermore,
Ts is a voltage correction amount corresponding to the activation delay of the fuel injection valve 10, which is the same as that used in the interrupt injection control,
By adding this voltage correction amount, the fuel injection valve 10
Even if the activation delay time changes depending on the battery voltage, the desired amount of fuel is injected and supplied.

As mentioned above, if the normal injection correction amounts y1 to y4 are added to the basic fuel injection amount T ppb, the engine 1
The predetermined injection timing (fuel injection valve 10
engine 1 at the output timing of the drive pulse signal to
Even when a deviation occurs in the true required amount in the intake stroke with respect to the required fuel amount, the deviation is predictively corrected based on the normal injection correction amounts y1 to y4, and the amount is corrected to increase during acceleration and decrease during deceleration. By correcting this, it is possible to eliminate the response delay in fuel supply control.

Next, the setting control of various coefficients will be explained according to the background job (BGJ) shown in the flowchart of FIG.

In step 61, an intake air temperature correction coefficient KTA2 is searched from a preset map based on the intake air temperature TA(C) detected by the intake air temperature sensor 6. This intake air temperature correction coefficient KTA2 is used to calculate the basic fuel injection amount T pqcy 1 in step 6 above.

Further, in step 62, the intake air temperature correction coefficient KTA is similarly searched, but this intake air temperature correction coefficient KT
A is the basic fuel injection amount Tpp in step 53
This is used to calculate b.

In the next step 63, a water temperature correction coefficient K twacc is searched from a preset map based on the cooling water temperature Tw detected by the water temperature sensor 12. This water temperature correction coefficient K twacc is used in the calculation of the interrupt injection 'I y++ to yaa in step 16.

Furthermore, in the next step 64, a minute value is calculated from a preset map based on the intake pressure PB detected by the intake pressure sensor 9 and the engine rotation speed N calculated based on the detection signal from the crank angle sensor 15. Search and find the correction coefficient KFLAT. This minute correction coefficient KFLAT is used in the correction calculation of the basic volumetric efficiency correction coefficient Kpb in step 52.

Next, follow the routine shown in the flowchart in Figure 7.
The setting control of the 1-cylinder injection discrimination flag FICYL to the #4 cylinder injection necessary discrimination flag F4CYL and the normal fuel injection control will be explained.

In this embodiment, in order to make the supply end timing of the normal fuel injection amount match the opening timing of the intake valve of each cylinder, the fuel injection start timing is varied from the fuel injection amount Til to Ti4 calculated for each cylinder. Although this embodiment is designed to control the fuel injection, a configuration may also be adopted in which normal fuel injection is started at a constant crank angle position.

This routine is executed when it is determined that a predetermined fuel injection timing (injection start timing) has arrived based on the detection signal output from the crank angle sensor 15. First, in step 71, It is determined whether the #1 cylinder injection determination flag F i CYL is 1 or zero.

As described later, the #1 cylinder injection discrimination flag F I CYL is the injection start timing of the #2 cylinder and is the #1 cylinder injection determination flag F I CYL.
Since the flag F I CYL is set to 1 when the output of the drive pulse signal in the pulse corresponding to the fuel injection amount Ti2 set for two cylinders is started, the flag F I CYL is set to 1.
When it is determined that is 1, it can be determined that it is the injection timing for the #l cylinder where fuel should be injected next to the #2 cylinder. Therefore, when the flag F ICYL=1, the process proceeds to step 72 and the fuel injection amount T set for the #1 cylinder is injected into the fuel injection valve 10 of the #1 cylinder.
Start outputting a drive pulse signal with a pulse width equivalent to H.

Then, in the next step 73, the #3 cylinder injection discrimination flag F3CYL is set to 1, while the other flags FICYL, F2CYL, and F4CYL are each set to zero.

In this way, if the flag F3CYL is set to 1 when fuel injection is supplied to the #1 cylinder, the next time the main lunitin is executed at the injection timing, step 71
When it is determined that the flag FICYL is zero, the process proceeds to step 74, where the flag F
Since it is determined that 3CYL is 1, the process advances from step 74 to step 75. In step 75, a drive pulse signal having a width corresponding to the fuel injection amount Ti3 set for cylinder #3 in step 54 is output to the fuel injection valve 10 provided in cylinder #3.

When the fuel supply control for the #3 cylinder is performed in step 75, in the next step 7G, 1 is set in the #4 cylinder injection determination flag F4CYL corresponding to the #4 cylinder to be subjected to fuel injection control next to the #3 cylinder. On the other hand, the other flags FICYL, F2CYL, and F3CYL are each set to zero.

As a result, when this routine is executed at the next injection timing, steps 71 → 74 will be executed.
→Proceed to step 77, and in this step 77 flag F
When 4CYL is determined to be 1, the process proceeds to step 78, where a drive pulse signal is outputted to the fuel injection valve 10 of the #4 cylinder in the same manner as in step 72.75 described above. Then, in the next step 79, the injection discrimination flag F2 for the #2 cylinder, which is the next fuel injection cylinder, is
Set CYL to 1 and set other flags to zero.

After setting the flag F2CYL to 1 and terminating this routine, when the injection timing comes and this routine is executed again, it is determined in step 77 that the flag F4CYL is zero, so that steps 77 to 80 are executed. Proceed to.

In step 80, a drive pulse signal is outputted to the fuel injection valve 10 of the #2 cylinder in the same manner as in steps 72, 75, and 78 described above. Then, in the next step 81, the flag F I CYL is set to 1, and the other flags are set to zero.

In this way, the flag FICYL-F4CYL is set to 1 only in the flag corresponding to the cylinder to which fuel is to be injected next time when the injection timing is reached and a drive pulse signal is output to the injection cylinder at that time. , flags corresponding to other cylinders that do not inject fuel are set to zero, and when the injection timing comes, it can be determined that the cylinder whose flag is set to 1 is the cylinder that should inject fuel. It is.

Next, Tatm indicates the time (ms) until the target timing for setting the fuel supply amount for each cylinder (the predetermined timing in the intake stroke at which the amount of intake air corresponding to the true required amount appears).
The setting control of 1 to Ta tm4 will be explained according to the routine shown in the flowchart of FIG.

In the case of the four-cylinder engine 1 of this embodiment, the routine shown in the flowchart of FIG. 8 is executed every time the reference angle signal REF, which is output from the crank angle sensor 15 at every 180° crank angle, is input. .

Note that the reference angle 1 word REF is set to be output at the ignition reference position of each cylinder (for example, BTDC90@), so that, for example, the one corresponding to the #1 cylinder can be distinguished from the others. The reference angle signal REF is used to determine which cylinder's ignition reference position is located.

When the reference angle signals RE and F are output from the crank angle sensor 15 and this routine is executed, first, step 9
1, TRE the period (IIS) which is the interval time from the previous reference angle signal REF output to the current reference angle signal REF.
Set to F. Therefore, in the case of this embodiment, the TRE
F corresponds to the time required for the crankshaft to rotate by 180@, and the engine rotational speed N can be calculated based on the TREF.

In the next step 92, the current reference angle signal REF is #
It is determined whether it corresponds to the first cylinder (#1cyβ) (is it the ignition reference position of the #1 cylinder)?

Here, if it is determined that the current reference angle signal REF corresponds to the #1 cylinder, the process proceeds to step 93, and the target timing times Tatml to Tatm4 are updated as shown in the following formula.

Tatml"TREFX3+'ATREFTatm3←
% T RE F Tatm4←TREF+y2TREF Tatm2←TREFX2+y2TREF Since the current reference angle signal REF corresponds to the ignition reference position of the #1 cylinder, the ignition of the #3 cylinder is performed after the ignition of the #1 cylinder is performed. Before cylinder #3 is ignited, air intake is performed in cylinder #3.

In the case of this embodiment, the reference angle signal REF is the intake B of each cylinder.
It is output at the TDC 90° position, and the predetermined timing at which the intake air amount corresponding to the true fuel requirement appears during the intake stroke (intake valve open) is the intake BDC, which is the center position between the reference angle signals REF. I'm assuming.

Therefore, the target timing crank angle position for the fuel setting of #3 cylinder (intake BDC of #3 cylinder) is a position rotated by 90 degrees from the current reference angle signal REF (intake BTDC of #1 cylinder). The crankshaft is at 90° for the time
Time required to rotate TRE F x90°/1
80'T, so the target timing time T for #3 cylinder
y2TREF is set to atm3.

The target timing crank angle position of the #4 cylinder, which is the next intake stroke after the #3 cylinder, is delayed by 180 degrees with respect to the target timing crank angle position of the fuel setting of the #3 cylinder, so Tatm4 is Tat+n3+TREF. becomes. Similarly, Tatm2 is Tatm3+2xTR
EF (Tatm4+TREF) and Tatml is Tatm3+3XTREF (Tatm2+TREF)
becomes.

Note that when the target timing crank angle position for fuel setting is not at the center position between the reference angle signals REF, if the crank angle from the reference angle signal REF to the predetermined target timing crank angle position is Xo, then in step 93 Tatm3=TR, EF x In general, the suction force is strongest at 90° after intake top dead center (intake ATDC 90') in steady state.
Since this timing approaches the intake bottom dead center (intake BDC) when accelerated, the target timing crank angle position is preferably set between intake ATDC 90' and intake BDC.

On the other hand, in step 92, the current reference angle signal REF is #1.
If it is determined that the position does not correspond to the ignition reference position of the cylinder, the process advances to step 94. In step 94, it is determined whether the current reference angle signal REF corresponds to the ignition reference position of the #3 cylinder. When it is determined that the ignition reference position corresponds to the ignition reference position of the #3 cylinder, the closest intake stroke is that of the #4 cylinder, and the fuel setting target timing during the intake stroke is approximately at the center position between REF. , proceed to step 95 and write 'AT' to Tatm4 this time.
Set RE F and set other target timing times Tatml~T according to the 180° delay according to the firing order.
Set up atm3.

Furthermore, in step 94, the current reference angle signal REF is set to #3.
If it is determined that the reference angle signal REF does not correspond to the ignition reference position of the cylinder, the process proceeds to step 96, where it is determined whether the current reference angle signal REF corresponds to the ignition reference position of the #4 cylinder. If the ignition reference position is reached, step 9
Proceed to step 7 and set y2TREF to Tat...2 in the same way as above, and do other things.

Even if there is a delay, settings are made in accordance with the delay of 180 degrees.

When it is determined in step 96 that the current reference angle signal REF does not correspond to the ignition reference position of the #3 cylinder, since it should be the ignition reference position of the #2 cylinder, the process advances to step 98 and this time Tatm2 is set. y2TREF is set, and other settings are made according to the delay in 180° increments.

As described above, the target timing time Tatml~Ta
At tm3, the crank angle sensor 15 receives the reference angle signal REF.
Every time TREF is output, the latest TREF (engine rotation speed N
) is updated and set as the time until the next fuel setting target timing for each cylinder. Therefore, 1
The target timing time for one cylinder starts when the first reference angle signal REF of engine operation is output, and starts as the time from that point until the next intake BDC, and then 1lI
It decreases with the passage of time every ls, and when the reference signal REF is output again, it becomes zero at the intake BDC of that cylinder while being corrected to increase or decrease according to the engine rotational speed N at that time.

In this way, the target timing time Tat for each cylinder is
If ml~Tatm3 is set, it is possible to read the target timing time Tatml~Tatm3 for each cylinder individually without being affected by the engine speed N, etc., so that the corrected fuel supply can be performed. The requested correction amount for the cylinder is the target timing time T a
It can be set accurately based on tml to Tatm3.

The target timing times Tatml to Tatm3 (ms) for each cylinder, which are updated and set for each reference angle signal REF in the routine shown in the flowchart of FIG. 8, are counted down according to the routine shown in the flowchart of FIG. 9, respectively.

The routine shown in the flowchart of FIG. 9 is executed every Ims, which is the minimum unit of the target timing time Tatml to Tatm3 (ms).
The subtracted values are newly set in Tatml to Tatm3, respectively, and each time this routine is executed, the target timing time Tatml to Tatm3 (ms) is decreased by Ims, and the target timing time Tat is set from the time the reference angle signal REF is output. Ta~Tatm3 (ms) sequentially represents the time until the target timing.

In this way, according to the flowchart in FIG. 8, the reference angle signal REF is updated and set based on the latest engine rotational speed N, and is then subtracted every Ims to determine the time from the current time to the fuel setting target timing for each cylinder. T indicating
atml~T a tm3 is the above-mentioned interrupt injection amount y
11-y1. It is used to calculate and set the normal injection correction amount)'I-3'4, and accurately performs fuel supply correction control in accordance with the response delay of fuel control due to engine transient operation for each cylinder.

Also, in the next step 102, the count value cnt (free run counter) is incremented by 1, and this count value cn
t is the end of normal injection (when the drive pulse signal is OFF) T
is set to cntota in iend, and
The cntoLd and the latest count value cnt are compared in the step 22 to determine whether or not it is immediately after normal fuel injection.

As described above, according to this embodiment, the basic fuel injection WkTpqc is set based on the opening area A and the engine rotational speed N.
The amount of change in yl (engine load parameter) and the time T from that point to the predetermined crank angle position of the intake stroke of each cylinder
Based on atml to Ta atm4, the response delay of fuel supply control during transient operation is predicted and set for each cylinder, and during the first acceleration, interrupt injection (additional supply control) is used to prevent fuel shortage in the recent intake stroke. This prevents the air-fuel ratio from becoming lean at the initial stage of acceleration, while at the same time correcting the normal fuel injection amount Ti for each cylinder according to the predicted response delay during the transient period (normal supply correction control). This makes it possible to accurately prevent air-fuel ratio controllability from deteriorating for each cylinder due to a delay in control response during acceleration/deceleration operation (including during slow acceleration/deceleration).

Furthermore, in carrying out the above-mentioned response delay correction control, it is not necessary to particularly distinguish transient operation into acceleration and steady state, and the time periods Tatml to Tatm4 can be distinguished by acceleration/deceleration and interrupt injection/normal injection correction. Since the data at that point in time can be used without having to worry about it, simple control software can make the air-fuel ratio lean at the beginning of acceleration and correct the response delay in normal fuel supply during acceleration and deceleration.

Furthermore, when engine 1 is running at low speeds, there is a risk that a large error will occur in predicting engine load fluctuations due to the longer prediction time. By limiting the amount DLTTp within a predetermined limit amount, it is possible to prevent an excessive correction amount from being set due to a prediction error, and to improve air-fuel ratio controllability during transient operation even when the engine 1 is operating at low speed. Can be secured.

In this embodiment, the basic fuel injection amount Tppb in normal sequential injection control is calculated based on the intake pressure PB detected by the intake pressure sensor 9, but instead of the intake pressure sensor 9, An air flow meter such as a hot wire type that detects the intake air flow rate Q may be provided, and the basic fuel injection amount Tp may be calculated based on the intake air flow rate Q.

<Effects of the Invention> As explained above, according to the present invention, the amount of fuel supplied is determined based on the amount of engine load fluctuation obtained from the opening area of the intake system and the engine rotational speed, and the time to a predetermined crank angle position. By setting the correction amount, it is possible to accurately set the correction amount corresponding to the response delay of the fuel supply control that occurs during transient times in response to the engine request, and at the same time, it is possible to accurately set the correction amount corresponding to the response delay of the fuel supply control that occurs during transient times. By prohibiting correction at low engine speeds when the prediction error becomes large, it is possible to prevent deterioration of air-fuel ratio controllability due to erroneously setting an excessive correction amount, and also to keep the correction amount within the limit amount! Ijllt1M
This can prevent the correction amount from being set excessively even when the engine speed is low and the prediction time is long, and the air-fuel ratio controllability will not deteriorate significantly even when the engine speed is low.

[Brief explanation 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, FIGS. 3 to 9 are flowcharts showing control details in the above embodiment, and FIG. The figure is a diagram showing the relationship between the opening timing of the intake valve and the pressure difference between the front and rear of the intake valve, and FIG. 11 is a time chart for explaining problems in conventional transient correction control. 1...411M 7...Throttle valve 8.
...Throttle sensor 9...Intake pressure sensor 1
0...Fuel injection valve 11...Control unit 1
5... Crank angle sensor patent applicant Fujio Sasashima, agent of Japan Electronics Co., Ltd., patent attorney Figure 3 Part 2 A□

Claims (3)

[Claims] (1) Operating state detection means that detects state quantities related to either the intake air amount or intake pressure and the engine speed, and a fuel supply amount that sets the fuel supply amount based on the detected state quantities. a setting means; an engine load fluctuation amount calculating means for calculating an engine load fluctuation amount based on an opening area of an engine intake system that is variably controlled and an engine rotational speed; and a predetermined crank angle from the time when the engine load fluctuation amount is calculated. time calculation means for calculating the time to the position; correction amount calculation means for calculating the correction amount of the fuel supply amount based on the engine load fluctuation amount and the time to the predetermined crank angle position; and the calculated correction amount. correction amount limiting means for correcting and setting a correction amount to the predetermined limit amount when the amount of fuel exceeds a predetermined limit amount; A fuel supply control device for an internal combustion engine, comprising a fuel supply control means for controlling the fuel supply. 2. The fuel supply control device for an internal combustion engine according to claim 1, further comprising variable limit amount setting means for variably setting a predetermined limit amount in the correction amount limiting means in accordance with engine operating conditions. (3) Operating state detection means that detects state quantities related to either the intake air amount or intake pressure and the engine speed, and a fuel supply amount that sets the fuel supply amount based on the detected state quantities. a setting means; an engine load fluctuation amount calculating means for calculating an engine load fluctuation amount based on an opening area of an engine intake system that is variably controlled and an engine rotational speed; and a predetermined crank angle from the time when the engine load fluctuation amount is calculated. time calculation means for calculating the time to the position; correction amount calculation means for calculating the correction amount of the fuel supply amount based on the engine load fluctuation amount and the time to the predetermined crank angle position; a fuel supply control means for controlling the fuel supply to the engine based on the fuel supply amount corrected based on the correction amount; A fuel supply control device for an internal combustion engine, comprising: a means for inhibiting correction;