JP2543762B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine,
The present invention relates to an apparatus that performs high-accuracy correction control of a fuel supply amount during engine acceleration operation to improve acceleration operation performance.

<Prior Art> The following is known as a fuel supply control device for an internal combustion engine.

An intake air flow rate and intake pressure are detected as state quantities related to the intake air amount of the engine, and a basic fuel supply amount Tp is calculated based on these and a detected value of the engine speed. Then, the basic fuel supply amount Tp, various correction coefficient COEF set based on the operating state of the engine temperature, the air-fuel ratio feedback correction coefficient set according to the air-fuel ratio obtained through the detection of the oxygen concentration in the exhaust gas LAMBDA, the final fuel supply amount Ti after being corrected by the correction amount Ts etc. for correcting the change in the effective opening time of the fuel injection valve due to the battery voltage which is the driving power source.
Is calculated (Ti ← Tp × COEF × LAMBDA + Ts), and the calculated amount of fuel is intermittently supplied to the engine by a fuel injection valve or the like at a timing synchronized with the engine rotation (JP-A-57-8328). Etc.).

<Problems to be Solved by the Invention> By the way, in such a device for calculating and setting the fuel supply amount and electronically controlling it, the detection delay of various sensors and the calculation delay of the control device occur during transient operation, and Since there is a time difference between the detection of the air amount and intake pressure and the intake stroke, the fuel supply amount is set smaller than the actual engine demand during acceleration, for example, and the air-fuel ratio becomes lean and the nitrogen in the exhaust gas is reduced. Increased emissions of oxide NOx and hydrocarbon HC,
There is a problem that the response delay of the average effective pressure causes acceleration shock and deterioration of acceleration response.

Therefore, the applicant of the present invention has conducted fuel control based on the engine load fluctuation amount obtained from the throttle valve opening (the opening area of the engine intake system) and the engine speed, and the time to the predetermined crank angle position in the intake stroke. I proposed a configuration that predicts the change in the required fuel amount up to the target position of (1) and sets the correction amount of the fuel supply amount based on this prediction result (see Japanese Patent Application No. 62-269467).

However, for example, the predetermined crank angle position of the intake stroke (target position of fuel control) is set as the intake BDC, and the fuel supply start timing synchronized with the engine rotation is the intake BDC of each cylinder.
If it is before the CA of 360 °, it is necessary to predict the fluctuation amount of the engine load during 360 ° rotation of the engine in order to correct the normal fuel supply amount, and it is difficult to predict the fluctuation amount accurately. For this reason, an error in the predicted value occurs, which has been a serious problem during acceleration operation in which highly accurate air-fuel ratio controllability is required in terms of operation performance.

In particular, in the early stage of acceleration of the engine in which the change in the required fuel amount rises (see FIG. 10), and in the later stage of acceleration in which the required fuel amount change reaches a plateau, the prediction error becomes large,
If the prediction period becomes long, the prediction error becomes large. Therefore, if the injection start timing is brought closer to the intake stroke (intake valve open; INT / V OPEN) as shown in A in FIG. 10, the prediction error is made. However, as shown in Fig. 11, the engine performance such as exhaust properties and fuel consumption depends on the timing of fuel supply, and the best timing depends on the engine as shown by the dotted line in Fig. 11. Since it is different, depending on the engine, intake as described above
In some cases, it may be necessary to start fuel supply before 360 ° CA of BDC, which makes it necessary to predict engine load fluctuations for a long period of time, and it may not be possible to ensure the accuracy of predictive control. .

Further, in a region where the injection supply amount by the fuel injection valve is small, as shown in FIG. 12, generally, the actual injection amount with respect to the set injection amount cannot be accurately supplied. Therefore, especially in a small displacement engine, every two revolutions of the engine. 1 time from the fuel injection valve
Since the amount of fuel to be injected and supplied at one time is secured to obtain the accuracy of the supply amount, the period for predicting the engine load fluctuation amount becomes long and accurate prediction control cannot be performed in this case as well.

The present invention has been made in view of the above problems, and accurately corrects the fuel supply amount with high responsiveness to an increase change in the required fuel amount after the normal fuel supply synchronized with the engine rotation is set. An object of the present invention is to provide a fuel supply control device capable of improving the air-fuel ratio controllability during engine acceleration operation.

<Means for Solving the Problems> The invention according to claim 1 is configured as shown in FIG.

In FIG. 1, the engine operating state detecting means detects the state quantity of the engine related to the intake air amount of the engine, and the required fuel amount calculating means calculates the engine quantity for each unit time preset based on the state quantity. The required fuel amount of is calculated.

Then, the main fuel injection control means performs the main fuel injection by each fuel injection valve provided for each cylinder of the engine at the timing corresponding to the intake stroke of each cylinder according to the calculated required fuel amount. Let

On the other hand, the change amount calculating means calculates the change amount per unit time of the required fuel calculated by the required fuel amount calculating means.

Then, the additional injection control means, in addition to the main fuel injection by the main fuel injection control means, performs the additional fuel injection for every unit time on the basis of the change amount of the required fuel amount calculated by the change amount calculation means. At the same time, each fuel injection valve is used.

Here, the additional injection prohibiting means, when the fuel amount to be injection-controlled by the additional injection control means is less than the minimum fuel amount corresponding to the measurement limit of the fuel injection valve, each fuel by the additional injection control means. Prohibit performing additional fuel injection at the injection valve.

In addition, the integrated storage unit integrates and stores the fuel amount of the amount that is not injected because the additional fuel injection is prohibited by the additional injection prohibition unit.

Then, the additional injection amount adding means calculates the addition amount of the integrated value of the fuel amount stored in the integration storage means and the change amount of the required fuel amount calculated latest by the change amount calculating means as the additional injection control. It is set as the amount of fuel to be additionally injection-controlled by the means.

In the invention according to claim 2, instead of the additional injection amount adding means, a main injection amount adding means shown by a dotted line in FIG. 1 is provided.

The main injection amount addition means adds the integrated value of the fuel amount stored in the integration storage means to the fuel injection amount by the main fuel injection control means.

<Operation> According to the invention of claim 1, the change amount of the required fuel amount calculated for each unit time is calculated, and based on the change amount, in addition to the main fuel injection that is performed in time with the intake stroke. Thus, additional fuel injection is performed simultaneously for all the cylinders for each unit time, and the required fuel amount is reliably supplied in response to the increasing change in the required fuel amount during acceleration.

Further, when the amount of fuel to be additionally injected is smaller than the minimum amount of fuel, the fuel cannot be accurately measured by the fuel injection valve (see FIG. 12), so injection by the fuel injection valve is prohibited. .

Then, the fuel amount for which additional injection is prohibited and not injected is accumulated and stored, and the stored fuel amount is added to the change amount to be additionally injected in the next time and thereafter, and after addition If the injection amount is greater than or equal to the minimum fuel amount, the additional injection is executed.

Therefore, it is possible to reliably supply the fuel, which is insufficient in the main fuel injection, in the additional injection in non-rotational synchronization (every unit time) while maintaining the metering accuracy by the fuel injection valve.

On the other hand, in the invention described in claim 2, as in the invention described in claim 1, the amount of fuel that is not injected because additional injection is prohibited is accumulated and stored. , By adding to the fuel amount to be injected in the main fuel injection and correcting the increase in the main fuel injection amount, the fuel that should have been additionally injected in non-rotational synchronization is included in the main fuel injection in rotational synchronization and injected. .

Therefore, according to the second aspect of the present invention, the fuel amount required to be additionally injected is adjusted to the additional injection for each unit time and the intake stroke while maintaining the measurement accuracy of the fuel injection valve. It is possible to surely supply the fuel by correcting the increase of the main fuel injection.

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

In FIG. 2 showing a system configuration of an embodiment, air is sucked into an internal combustion engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, and an intake manifold 5. The air cleaner 2 has an intake air temperature (atmosphere temperature) TA
An intake air temperature sensor 6 for detecting (° C.) is provided.

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 for each cylinder.

The electromagnetic fuel injection valve 10 is intermittently driven to open by a drive pulse signal output from a control unit 11 having a microcomputer described later, and is pressure-fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator. Fuel that has been supplied to the intake manifold 5
Inject into and supply. That is, the amount of fuel supplied by the fuel injection valve 10 is controlled by the valve opening drive time of the fuel injection valve 10.

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

The control unit 11 outputs a crank unit angle signal PO output from the crank angle sensor 15 in synchronization with the engine rotation.
The crank reference angle signal REF is output by counting S for a predetermined time or at every predetermined crank angle position (every 180 degrees in the case of four cylinders, and in this embodiment, it is set as BTDC 120 degrees).
Is measured and the engine speed N is detected.

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. These signals are input to the control unit 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 detection signals from the various sensors, and also causes the fuel injection valve 10 to rotate the engine based on the set fuel injection amount Ti. At the same timing, the open drive control is performed to control the normal fuel supply, and the additional fuel supply (interrupt injection) is controlled separately from the normal fuel supply according to the increase in the required fuel amount.

Furthermore, the control unit 11 is an idle switch.
During the idle operation detected by the 8A and the neutral sensor 17, the idle rotation speed is feedback-controlled to the target idle rotation speed by controlling the opening degree of the idle control valve 19.

Next, various calculation processes for fuel supply control performed by the control unit 11 will be described in accordance with routines shown in flowcharts of FIGS. 3 to 6, respectively.

In the present embodiment, the functions as required fuel amount calculation means, change amount calculation means, main fuel injection control means, additional injection control means, additional injection prohibition means, integrated storage means, additional injection amount addition means, main injection amount addition means Is provided as software as shown in the flow charts of FIGS. Further, in the present embodiment, the engine operating state detection means detects the throttle sensor 8 for detecting the opening TVO of the throttle valve 7, the crank angle sensor 15 for outputting a detection signal synchronized with the engine rotation, and the intake pressure PB. Corresponding to the intake pressure sensor 9.

The internal combustion engine 1 in the present embodiment is a 4-cylinder engine, and the main fuel injection is the fuel injection valve provided for each cylinder.
It is configured such that 10 is driven and controlled separately according to the intake stroke of each cylinder.

The routine shown in the flowchart of FIG. 3 is executed every 10 ms.

First, in step 1, the intake pressure PB detected by the intake pressure sensor 9, the engine speed N calculated based on the detection signal from the crank angle sensor 15, the throttle valve opening TVO detected by the throttle sensor 8, etc. Enter.

In step 2, the opening area Amm (of the engine intake system) of the throttle chamber 4 variably controlled by the throttle valve 7
² is obtained by searching a preset map based on the throttle valve opening TVO input in step 1.

In step 3, based on the value obtained by dividing the opening area A obtained in step 2 by the engine rotation speed N, the basic volume efficiency QHφ (%) of the engine 1 corresponding to the steady operation is retrieved from the map. That is, the amount of absorbed air of the engine is predicted from the opening area A and the engine speed N.

In step 4, the basic volumetric efficiency QHφ obtained in step 3 is used as a weighted average for weighted averaging so as to approximately correspond to the true engine load change during transient operation of the engine 1, and the weighted weight X is used as the engine speed N. It is set based on the opening area A. Specifically, the constant a set according to the engine speed N and the value obtained by multiplying the constant b set also according to the engine speed N by the opening area A are added to obtain the final value. Then, the weight X is set. The weight X is
The weighting for the latest basic volumetric efficiency QHφ is shown, and since the true engine load changes faster with respect to the opening change of the throttle valve in the high rotation and high load region, the weighting weight X is the high rotation load region. It is designed to be so big.

In the next step 5, the basic volume efficiency QHφ obtained in step 3 according to the following equation and the volume efficiency QCYL calculated in step 5 at the previous execution of this routine are weighted and averaged using the weight X. Then, set the result as the latest volume efficiency QCYL.

QCYL ← (1−X) QCYL + X × QHφ If the volume efficiency QCYL is obtained according to the above equation, QHφ = QCYL during steady operation, and the volume efficiency QCYL is stabilized at a constant value. Then, according to the engine operating state at that time, the change in the volumetric efficiency QCYL is blunted with respect to the change in the basic volumetric efficiency QHφ. The volume efficiency QCYL is set to substantially correspond to the load change.

In step 6, the basic fuel injection amount (engine required fuel amount) ANTp based on the volume efficiency QCYL according to the opening area A and the engine rotation speed N is calculated by the following formula.

ANTp ← KCONA × QCYL Here, the calculated basic fuel injection amount ANTp is calculated based on the volumetric efficiency QCYL substantially corresponding to the true engine load change during the transient operation of the engine 1, which will be described later. The basic fuel injection amount TpPB set based on the intake pressure PB detected by the intake pressure sensor 9 is set to a value advanced by several tens of ms as shown in FIG. .

The basic fuel injection amount ANTp is set to obtain a change in the required fuel amount of the engine 1 during engine transient operation, and is set to a value whose phase is advanced by about several tens of ms with respect to the basic fuel injection amount TpPB. That is, taking into account the travel time until the fuel injected from the fuel injection valve 10 is sucked into the cylinder, a change in the required fuel amount is obtained based on this basic fuel injection amount ANTp, which will be described later. As described above, if additional fuel supply (interrupt injection) corresponding to the required fuel amount change is performed separately from the normal injection, the change in the required fuel amount can be responded with good responsiveness because the travel time of the fuel is considered in advance. Things.

Further, since the intake pressure PB pulsates under the influence of pressure pulsation generated in the intake passage, the basic fuel injection amount TpPB also pulsates, and a change in the basic fuel injection amount TpPB corresponds to a change in the true required amount. It may not be possible to change the required fuel amount.
If the detection is performed based on the basic fuel injection amount ANTp obtained from the opening area A and the engine rotation speed N as described above, the detection is not affected by the pressure pulsation, and the detection response is excellent. Thus, the change in the required fuel amount can be accurately detected.

In the next step 7, the basic fuel injection amount ANTp _OLD calculated in step 6 during the previous execution of this routine is subtracted from the basic fuel injection amount ANTp calculated in step 6 this time,
A change amount ΔANTp of the basic fuel injection amount ANTp (per unit time) during 10 ms around the execution of this routine is calculated. This change amount ΔANTp is a value in response to a change in the required fuel amount of the engine for 10 ms, and becomes a positive value when the engine 1 is accelerated and the required fuel amount shows an increasing tendency.

At step 8, the basic fuel injection amount ANTp calculated this time at step 6 is set to the previous value ANTp _OLD so as to be used for calculation of the change amount ΔANTp at step 7 at the next execution of this routine.

In the next step 9, the change amount ΔAN determined in step 7
The value obtained by doubling Tp is taken as the amount of change in the required fuel injection amount in one cylinder in the last 10 ms, and the voltage correction amount Ts set based on the battery voltage is added to this amount of change, and the result is Is set to an interrupt injection amount (additional supply fuel amount) Y which is interrupted during normal fuel injection and additionally supplied.

In the present embodiment, a value obtained by doubling the basic fuel injection amount Tp calculated based on the engine operating state is set for convenience as a basic fuel supply amount for one cylinder, and is synchronized with the engine rotation described later. In the normal fuel supply control performed in the same manner, the basic fuel injection amount TpPB obtained from the intake pressure PB is doubled to calculate the final fuel injection amount Ti. ΔANTp is doubled.

Further, even if the drive of the fuel injection valve 10 is controlled based on the value 2 × ΔANTp, there is actually a response delay time of the fuel injection valve 10, and this delay is, of course, caused by the battery which is the driving power source of the fuel injection valve 10. Therefore, a voltage correction amount Ts set based on the battery voltage is added, and fuel equivalent to 2 × ΔANTp is actually injected and supplied from the fuel injection valve 10.

In the next step 10, a change amount 2 × ΔANTp of the required fuel amount during 10 ms, which is a value obtained by subtracting the battery voltage correction amount Ts from the interrupt injection amount Y, is set to the change amount Z.

Then, in step 11, the carry-in interrupt injection amount in the # 4 cylinder that has been integrated without interrupt injection until the last time is added to the interrupt injection amount Y (← 2 × ΔANTp + Ts) set in step 9 The value obtained by adding the value ΣQ4 is compared with the minimum injection amount (minimum fuel amount) Ti _min at which the interrupt injection control is permitted.

When Y + ΣQ4 is smaller than Ti _{min, the} routine proceeds to step 12 without executing the interrupt injection (prohibiting the additional supply of fuel), and the Z set in step 10 is set.
Is added to the integrated value ΣQ4 up to the previous time, and the result is newly set to the integrated value ΣQ4. Therefore, the integrated value ΣQ4
Is the additional supply fuel amount to be additionally injected based on the variation amount ΔANTp in the # 4 cylinder, but the additional supply is prohibited because the injection amount is less than the minimum injection amount Ti _min ,
The amount of interrupt injection is carried over without being injected at present.

The minimum injection amount Ti _min , when the drive control of the fuel injection valve 10 based on the injection amount less than this Ti _min , the variation of the fuel actually injected from the fuel injection valve 10 with respect to the valve opening drive time is large, This shows that the fuel injection amount cannot be accurately controlled by controlling the valve opening drive time (see FIG. 12).

Therefore, in the above-mentioned step 11, the interruption injection amount Y + the integrated valueΣQ4
When it is determined that is smaller than the minimum injection amount Ti _min , the interrupt injection (additional injection) is not performed this time, and the interrupt injection amount for this time is carried over to the next time (this carry-over amount is Σ
Equivalent to Q4. ), Next time the latest interrupt injection amount Y is added to this carry-over amount, and the result is the minimum injection amount Ti.
When the value exceeds _min , it will be interrupted.

That is, the interrupt injection amount (additional supply fuel amount) is the fuel injection valve 10
If it is less than the minimum injection amount Ti _min that corresponds to the measurement limit of, the accurate fuel supply control cannot be performed even if interrupt injection is performed, so carry over this interrupt injection amount to the next time Is an amount that exceeds the minimum injection amount Ti _min and the accuracy of fuel metering by the fuel injection valve 10 is obtained (with an injection amount at which the flow characteristic of the fuel injection valve 10 stabilizes), the integrated injection is performed. When ΣQ4 remains uninjected until the normal fuel injection start timing in the # 4 cylinder, ΣQ4 is added to the normal fuel supply (main fuel supply) that is synchronized with the engine rotation and the fuel carried over without being injected is added. Injection is performed, and at this time, the integrated value ΣQ4 is reset to zero.

Therefore, even when the required fuel amount (engine load) changes minutely at the start of engine acceleration or in the latter half of the period, minute interrupt injection amounts corresponding to this change are supplied collectively for several times. , The air-fuel ratio controllability by the interrupt injection amount is secured.

Also, by integrating the interrupt injection amount Y at the time of slow acceleration, even when the integrated value until the next ordinary injection so as not to exceed the minimum injection quantity Ti _min, integration of the carried over the interruption injection quantity Y Since the value is added to the normal fuel supply amount, the fuel injection amount increase correction is not stopped because the set interrupt injection amount Y is small.

However, as described above, when the interrupt injection amount Y set during the normal fuel supply is not cumulatively added to the normal injection amount without being interrupt-injected, the real-time property is impaired. Effective correction can be performed only when the fluctuation of (engine load) continues at substantially the same level.

On the other hand, when it is determined in step 11 that the interrupt injection amount Y + the integrated value ΣQ4 is equal to or greater than the minimum injection amount Ti _min , the fuel amount to be interrupt-injected this time is an amount that can be accurately measured by the fuel injection valve 10. Therefore, the routine proceeds to step 13, where the flag F100d4 for judging the allowable crank angle range of the interrupt injection in the # 4 cylinder is judged. As will be described later, the flag F100d4 is set when the cylinder discrimination value ncyl reaches 4 (when the reference angle signal REF is the ignition reference signal of the # 1 cylinder, and the normal injection start timing of the # 4 cylinder). However, from # 4 cylinder intake BDC (or intake ATDC 100 ° ~ intake BDC
Zero is set up to the predetermined crank angle between
Otherwise, 1 is set and flag F100 is set.
Interrupt injection is allowed when d4 is zero (see FIG. 8).

The crank angle range in which the flag F100d4 is set to zero (intake BTDC 120 ° to intake ATDC 100 ° to intake BDC) is #
In four cylinders, it shows the time from the start of normal fuel supply to the last fuel injection timing when fuel is taken in during the intake stroke (intake valve open; INT / V OPEN) in which this supplied fuel is taken in, Even if the interrupt injection is performed at a time exceeding the crank angle range, it is not sucked into the cylinder in this intake stroke, and stays upstream of the intake valve until the next intake stroke when a new normal fuel injection amount is set. Will be done. In the present embodiment, since it is intended to cope with the change in the required fuel amount from the start (set) of the normal fuel injection to the intake stroke, the # 4 cylinder when the flag F100d4 is 1 is set. The interrupt injection with respect to is a surplus correction in the # 4 cylinder.

Therefore, when it is determined in step 13 that the flag F100d4 is zero, the interrupt injection amount (2 × ΔANTp + Ts + ΣQ4) based on the change amount ΔANTp is injected, whereas
When the flag F100d4 is 1, the interrupt injection is prohibited, or the interrupt injection is executed, but the integrated value Σ of the interrupt injection amount that is not immediately sucked and is carried over to the next intake stroke.
After obtaining q4, the integrated value Σq4 is subtracted from the fuel injection amount Ti of the normal injection in the next # 4 cylinder performed for each reference angle signal REF to supply the fuel.

That is, when it is determined in step 13 that the flag F100d4 is zero, the process proceeds to step 15 to output a drive pulse signal having a pulse width equivalent to 2 × ΔANTp + Ts + ΣQ4 to the fuel injection valve 10 provided in the # 4 cylinder, In addition to the normal injection for each reference angle signal REF, fuel corresponding to the change in the required fuel amount is interrupt-injected into the # 4 cylinder. Then, in the next step 16, since the interrupt injection including the integrated value ΣQ4 is performed in step 15, the integrated value ΣQ4 is reset to zero.

Note that when the timing of the interrupt injection is during normal fuel injection in the # 4 cylinder, an interrupt drive pulse signal having a pulse width equivalent to 2 × ΔANTp + 4Q4 may be output following the end of the normal fuel injection. .

On the other hand, if it is determined in step 13 that the flag F100d4 is 1, it is not inhaled in the latest intake stroke even if the interrupt injection is performed on the # 4 cylinder. Is the current interrupt injection amount 2 × ΔANTp in step 14.
+ ΣQ4 and the non-intake interrupt injection integrated value Σq4 up to the previous time are added to calculate the total amount of interrupt injection that is not sucked in the latest intake stroke in the # 4 cylinder and stays upstream of the intake valve until the next intake stroke. Ask.

Here, the integrated value Σq4 that is set remains in the upstream of the intake valve of the # 4 cylinder without being sucked in until the next intake stroke of the # 4 cylinder.
This accumulated value Σq4 is subtracted from the next normal injection of the four cylinders to correct the amount of staying, so that the amount of staying upstream of the intake valve due to the interrupt injection is not excessively supplied to the cylinder. To do so.

When the integrated value Σq4 is updated and set in step 14, the process proceeds to the next step 15, in the same manner as when the flag F100d4 is determined to be zero, the interrupt drive pulse signal having the pulse width equivalent to 2 × ΔANTp + Ts + ΣQ4 is changed to # It outputs to the fuel injection valve 10 of four cylinders, and the integrated value ΣQ4 is reset to zero in the next step 16.

Further, when it is determined in step 13 that the flag F100d4 is 1, the fuel is not immediately sucked into the cylinder of the # 4 cylinder even if the interrupt injection is performed. Therefore, as shown by the dotted line in FIG. It is also possible to jump over 16 to prohibit the interrupt injection, and in this case, all of the injected fuel is sucked into the cylinder in the recent intake stroke,
It is not necessary to set the integrated value Σq4.

Steps 11 to 16 are arithmetic processing for interrupt injection control in the # 4 cylinder. Other cylinders # 2, # 1, #
3, the same arithmetic processing is performed at the same time.

That is, the interrupt injection amounts ΣQ1 to ΣQ4 carried over without interrupt injection are set for each cylinder, and the added value of this carryover amount and the latest calculated interrupt injection amount Y is the minimum injection amount Ti.
When the interrupt injection is performed when it is _min or more and the interrupt injection timing is not within the crank angle range in which the interrupt injection is permitted in the cylinder, it is determined by the flags F100d1 to F100d4 that the interrupt injection is performed. Next reference angle signal REF
The interrupt injection amounts Σq1 to Σq4 that are not sucked in are integrated for each cylinder so as to be subtracted from the normal injection amount that is synchronized with. This interrupt injection control is performed in steps 17 to 22 for the # 2 cylinder, steps 23 to 28 for the # 1 cylinder, and steps 29 to 34 for the # 3 cylinder so that interrupt injection can be performed simultaneously in multiple cylinders. (See Figure 9).

Therefore, according to the present embodiment, if the conditions of Y + ΣQ1 to 4 ≧ Ti _min are met, interrupt injection is performed simultaneously in each cylinder every 10 ms, which is the execution cycle of this routine.
Normal fuel supply synchronized with engine rotation (main fuel supply)
In other words, if the required fuel amount of the engine increases and changes after the normal fuel supply amount is finally set, it is possible to exactly supply the increased demand amount to the engine. Therefore, the air-fuel ratio controllability during engine acceleration is improved.

However, the interrupt injection control does not predict a long-term change in the required fuel amount of the engine, but directly calculates the change amount of the required fuel amount per minute unit time (10 ms). There are few correction control errors, and in the case of requiring man-hours to match the interrupt injection amount with the engine request, such as when setting the interrupt injection amount based on changes in the throttle valve opening TVO, etc. Absent.

In this way, when the interrupt injection based on the required fuel amount change is controlled for each cylinder, the next step 35 is to determine the intake pressure
A volume efficiency correction coefficient KQCYL used to calculate the basic fuel injection amount TpPB based on PB is set. Volume efficiency correction factor KQC
YL is a basic correction coefficient KP set based on the intake pressure PB
B is obtained by multiplying B by a minute correction coefficient KFLAT that is set based on the intake pressure PB and the engine speed N in step 41 of the background job shown in FIG.

In the next step 36, the basic fuel injection amount for main fuel injection (the required fuel amount of the engine) TpPB based on the intake pressure PB is calculated according to the following equation.

TpPB ← KCOND × PB × KQCYL × KTA where KCOND is a constant based on the injection characteristics of the fuel injection valve 10, and KTA is the intake air temperature TA detected by the intake air temperature sensor 6 in step 42 of the background job shown in FIG.
Is an intake temperature (intake density) correction coefficient set based on

Then, in the next step 37, a fuel injection amount Ti common to each cylinder supplied in synchronization with the engine rotation is calculated according to the following equation.

Ti ← 2 × TpPB × LAMBDA × COEF + Ts Here, LAMBDA is air-fuel ratio feedback that is feedback-controlled so that the air-fuel ratio detected via the oxygen concentration in the exhaust gas detected by the oxygen sensor 14 approaches the target air-fuel ratio. The correction coefficient, COEF are various correction coefficients set according to the operating state such as the cooling water temperature Tw detected by the water temperature sensor 12, and Ts is the time when performing the interrupt injection based on the change in the required fuel amount for 10 ms. This is the same battery voltage correction as that used in (1).

Next, the routine shown in the flowchart of FIG. 5 is executed every time the crank angle sensor 15 outputs the reference angle signal REF.

In this embodiment, the reference angle signal REF is output at BTDC 120 °.
Is a reference position for ignition timing control for each cylinder, and normal fuel injection is performed in synchronization with the reference angle signal REF in each cylinder at the timing of the intake stroke. The reference angle signal REF can identify the cylinder corresponding to the cylinder that is the ignition reference position. For example, when the reference angle REF is the ignition reference position of the # 1 cylinder, fuel injection is started to the # 4 cylinder. The reference angle signal REF
At the ignition reference position of the # 3 cylinder, fuel injection is started to the # 2 cylinder (see FIG. 8).

First, in step 51, the current reference angle signal REF is #
It is determined whether the ignition timing corresponds to the ignition reference position of one cylinder. If it is determined that the ignition reference position of the # 1 cylinder is reached, the routine proceeds to step 52, where the fuel injection valve 10 of the # 4 cylinder, which is the cylinder in which the normal fuel injection synchronized with the engine rotation is to be started. , Ti + ΣQ4−Σq4 equivalent pulse signal is output.

ΣQ4 is a value corresponding to the change in the required fuel amount that has not been interrupted by the # 4 cylinder before the current reference signal REF, and Σq4 is # up to the current reference signal REF.
Since the fuel is interrupted and injected into the four cylinders but remains without being sucked into the cylinders, it is corrected by adding and subtracting from the normal fuel injection amount Ti. Further, the fuel injection amount Ti used in step 52 is the latest value of the fuel injection amount Ti calculated every 10 ms according to the flowchart of FIG.

In the next step 53, the flag F100d4 for determining whether the fuel injected in the # 4 cylinder is injected into the cylinder is set to zero, and the reference angle signal RE of this time is set.
The fuel injected from the F to the # 4 cylinder can be determined to be in the state of being sucked into the cylinder in the latest intake stroke.

The flag F100d4 set to zero here is the intake BD of the # 4 cylinder in accordance with the flowchart of FIG. 6 described later.
The flag F100d is configured so that 1 is set by C.
Zero is set for 4 only from the ignition reference position of the # 1 cylinder (normal injection start timing of the # 4 cylinder) to the intake BDC of the # 4 cylinder.

In step 54, ΣQ4 and Σq4 used for correcting the normal fuel injection amount Ti in step 52 are reset to zero, respectively, until the reference angle signal REF corresponding to the ignition reference position of the # 1 cylinder is output next time. In ΣQ4 and Σq4
So that and are newly set.

In step 55, the cylinder discriminating value ncyl is set to 4, and based on the cylinder discriminating value ncyl, from the normal injection start timing of the # 4 cylinder to before the normal injection start timing of the next injection cylinder # 2. It is determined that it is time.

On the other hand, when it is determined in step 51 that the current reference angle signal REF does not correspond to the ignition reference position of the # 1 cylinder, the routine proceeds to step 56, where the current reference angle signal REF is # 3.
It is determined whether or not it corresponds to the ignition reference position of the cylinder.

Here, when the reference angle signal REF this time corresponds to the ignition reference position of the # 3 cylinder, Ti + ΣQ2 is set as the normal fuel injection control for the fuel injection valve 10 of the # 2 cylinder in the same manner as in steps 52 to 55. A drive pulse signal having a pulse width equivalent to Σq2 is output (step 57), while the flag F100d2 is reset to zero (step 58), and the data of ΣQ2 and Σq2 used for normal fuel control are reset to zero (step 59). ), And 2 is set to the cylinder discrimination value ncyl (step 60).

On the other hand, if it is determined in step 56 that the ignition reference position is not equivalent to the # 3 cylinder ignition position, then the process proceeds to step 61, where it is determined whether the reference angle signal REF is equivalent to the ignition reference position of the # 4 cylinder. When it is the ignition reference position of the # 4 cylinder,
Normal fuel injection to # 1 cylinder and # 1
Set various data corresponding to cylinders (step 62).
~ 65).

Further, when it is determined in step 61 that the ignition reference position is not for the # 4 cylinder, the reference angle signal REF this time should be the ignition reference position for the # 2 cylinder. Therefore, in steps 66 to 69, normal fuel injection for the # 3 cylinder is performed. And various data corresponding to the # 3 cylinder are set.

Next, the routine shown in the flowchart of FIG. 6 is executed by interrupt at the TDC position of each cylinder. For example, the reference angle signal REF from the crank angle sensor 15 and the unit angle signal P
A counter for inputting the OS is provided.
Unit angle signal from reference angle signal REF output at DC 120 °
Detect TDC position by counting POS,
When an interrupt signal is output to the external interrupt terminal of the CPU at position C, the interrupt routine shown in FIG. 6 is executed.

First, at step 81, it is judged if the cylinder discrimination value ncyl is 2, and if the cylinder discrimination value ncyl is 2, the routine proceeds to step 82, where a flag F100d4 is set to 1.
When the cylinder discrimination value ncyl is 2, it is within the range of 120 ° to 180 ° of intake BTDC of the # 2 cylinder as shown in FIG.
The TDC at this time is the intake TDC of the # 2 cylinder, and the # 4
It is also the intake BDC of the cylinder. Therefore, in the TDC when the cylinder discrimination value ncyl is 2, it is detected that the # 4 cylinder becomes the intake BDC, and the # 4 cylinder inhales until the next intake stroke even if fuel injection is performed beyond this time. Since it will be distilled without being set, 1 is set to the flag F100d4 so that it is possible to determine that it is the time when the injected fuel is retained in the # 4 cylinder.

If it is determined in step 81 that the cylinder discrimination value ncyl is not 2, the routine proceeds to step 83, where the cylinder discrimination value ncyl becomes 1
Is determined. If the cylinder discrimination value ncyl is 1, as shown in FIG. 8, the current TDC is the intake B of the # 2 cylinder.
Since it corresponds to DC, the routine proceeds to step 84, where 1 is set in the flag F100d2.

Further, when it is determined in step 83 that the cylinder discrimination value ncyl is not 1, the routine proceeds to step 85, where the cylinder discrimination value ncy1 is determined.
It is determined whether or not l is 3. Cylinder discrimination value ncyl is 3
Then, as described above, this time TDC is intake B of cylinder # 1
Since it corresponds to DC, the routine proceeds to step 86, where 1 is set in the flag F100d1.

If it is determined in step 85 that the cylinder discrimination value ncyl is not 3, the cylinder discrimination value ncyl should be 4, so the routine proceeds to step 87 and sets 1 to the flag F100d3.

In this way, when the intake BDC of each cylinder is reached, the flag F10
1 is set in 0d1 to F100d4, and flags F100d1 to F100d
It is possible to determine whether or not the fuel is injected into the cylinder by 4 and whether it is in the state of being sucked into the cylinder in the latest intake stroke.

In this embodiment, the fuel supply amount in the main fuel supply control synchronized with the engine rotation is calculated based on the intake pressure PB, but instead of the intake pressure sensor 9, the intake air amount Q is detected. An air flow meter may be provided and a normal fuel supply amount may be calculated based on the intake air amount Q detected by the air flow meter.

Further, when the main fuel injection is performed in synchronization with the intake stroke of each cylinder, the injection start timing is not limited, and for example, the injection start timing is variable so that the injection end timing is at a constant crank angle position. It may be controlled.

<Effects of the Invention> As described above, according to the present invention, it is possible to accurately perform the fuel injection corresponding to the increase change in the required fuel amount, which cannot be handled by the main fuel injection (rotation synchronous injection) whose timing is adjusted to the intake stroke. It is possible to improve the accuracy of air-fuel ratio control at the time of period acceleration, prohibit the additional injection of the fuel amount below the measurement limit, and perform the asynchronous injection of the fuel amount that should have been injected in the prohibited injection ( Since the injection is performed in addition to the additional injection per unit time) or the rotation synchronous injection (main fuel injection), the fuel supply amount can be corrected in response to a minute increase in the required fuel amount while maintaining the metering accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing one embodiment of the present invention, FIG. 3 to FIG. The figure is a time chart for explaining the characteristics in the weighted average calculation of the required fuel amount in the same embodiment,
FIG. 8 and FIG. 9 are time charts for explaining the control characteristics in the above embodiment, respectively, and FIG. 10 is a time chart for explaining the problems of the conventional fuel correction control,
FIG. 11 is a diagram showing the relationship between fuel supply timing and engine performance, and FIG. 12 is a diagram showing the injection characteristics of the fuel injection valve. 1 ... Engine, 4 ... Throttle chamber 5 ... Intake manifold, 7 ... Throttle valve 8 ... Throttle sensor, 9 ... Intake pressure sensor 10 ... Fuel injection valve, 11 ... Control unit 15 ... Crank angle Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-46060 (JP, A) JP-A-53-41642 (JP, A) JP-A-60-62627 (JP, A)

Claims (2)

(57) [Claims] 1. A fuel injection valve provided for each cylinder of an engine, an engine operating state detecting means for detecting a state quantity of the engine relating to an intake air amount of the engine, and a state detected by the engine operating state detecting means. A required fuel amount calculation means for calculating the required fuel amount of the engine for each preset unit time based on the amount, and a change amount per unit time of the required fuel amount calculated by the required fuel amount calculation means Change amount calculation means, main fuel injection control means for performing main fuel injection by each fuel injection valve in accordance with the calculated required fuel amount, in synchronization with the intake stroke of each cylinder, and the main fuel Apart from the main fuel injection by the injection control means,
Additional injection control means for causing each fuel injection valve to simultaneously perform additional fuel injection per unit time on the basis of the change amount of the required fuel amount calculated by the change amount calculation means, and injection by the additional injection control means Additional injection for prohibiting execution of additional fuel injection at each fuel injection valve by the additional injection control means when the amount of fuel to be controlled is less than the minimum fuel amount corresponding to the metering limit of the fuel injection valve. Prohibiting means, totalizing storage means for accumulating and storing the amount of fuel for which additional fuel injection has been prohibited by the additional injection inhibiting means and the additional fuel injection has not been performed, and the fuel amount stored in the totalizing storage means Additional injection amount adding means for setting the addition amount of the integrated value of the above and the latest change amount of the required fuel amount calculated by the change amount calculating means as the fuel amount to be additionally injection controlled by the additional injection control means. And A fuel supply control device for an internal combustion engine, comprising: 2. A fuel injection valve provided for each cylinder of the engine, an engine operating state detecting means for detecting a state quantity of the engine relating to an intake air amount of the engine, and a state detected by the engine operating state detecting means. A required fuel amount calculation means for calculating the required fuel amount of the engine for each preset unit time based on the amount, and a change amount per unit time of the required fuel amount calculated by the required fuel amount calculation means Change amount calculation means, main fuel injection control means for performing main fuel injection by each fuel injection valve in accordance with the calculated required fuel amount, in synchronization with the intake stroke of each cylinder, and the main fuel Apart from the main fuel injection by the injection control means,
Additional injection control means for causing each fuel injection valve to simultaneously perform additional fuel injection per unit time on the basis of the change amount of the required fuel amount calculated by the change amount calculation means, and injection by the additional injection control means Additional injection for prohibiting execution of additional fuel injection at each fuel injection valve by the additional injection control means when the amount of fuel to be controlled is less than the minimum fuel amount corresponding to the metering limit of the fuel injection valve. Prohibiting means, totalizing storage means for accumulating and storing the amount of fuel for which additional fuel injection has been prohibited by the additional injection inhibiting means and the additional fuel injection has not been performed, and the fuel amount stored in the totalizing storage means A main fuel injection amount adding means for adding the integrated value of the above to the fuel injection amount by the main fuel injection control means, and a fuel supply control device for an internal combustion engine.