JPH02264135A - Fuel feed control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To correct a fuel feed amount with high precision in proportion to an increase in a demand fuel amount by a method wherein fuel is additionally fed at intervals of a unit time based on a change amount computed by a change amount computing means separately from the feed of main fuel in linkage with rotation of an engine. CONSTITUTION:Based on an engine state amount pertaining to an intake air amount detected by an engine running state detecting means A, demand fuel of an engine is computed by a demand fuel computing means B to feed main fuel. A change amount per a unit time is computed by a change amount computing means C, and based on the computing result, a fuel additional feed control means D additionally feeds fuel at intervals of a unit time based on a change amount separately from main fuel fed in linkage with rotation of an engine. In which case, when the demand fuel computing means B computes a demand fuel amount based on the opening area of a suction system and an engine rotation speed, a weighted average processing means E performs weighted average so as to provide a phase state more progressed by a given time than a change in a demand fuel amount, and computes a change amount. This constitution high-precisely corrects a fuel feed amount in proportion to a change in a demand fuel amount.

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 in particular, to highly accurate correction control of the fuel supply amount during engine acceleration operation to improve acceleration operation performance. related to the device.

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

The intake air flow rate and intake pressure are detected as state quantities related to the intake air amount 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 supply amount Tp is adjusted according to various correction coefficients C0EF set based on operating conditions such as engine temperature, and an air-fuel ratio feedback correction coefficient set according to an air-fuel ratio determined through detection of oxygen concentration in exhaust gas. LAMBDA, calculate the final fuel supply amount T+ by correcting it with a correction numerator s, etc. to correct the change in the effective valve opening time of the fuel injection valve due to the battery voltage that is the driving power source Ti4-TpXCOE F
XLAMBDA+T S ), 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 (see Japanese Patent Laid-Open No. 578328, etc.).

<Problems to be Solved by the Invention> By the way, in a device that calculates and sets the fuel supply amount and controls it electronically, there is a delay in detection of various sensors and a delay in calculation of the control device during transient operation, and there is also a delay in the calculation of the control device. Because there is a time difference between the time when air flow rate and intake pressure are detected and the time during the intake stroke, for example, during acceleration, the fuel supply amount is set to be smaller than the actual amount required by the engine, and the air-fuel ratio becomes leaner, reducing the amount of nitrogen in the exhaust gas. There are problems such as an increase in the amount of oxide NOx and hydrocarbon HC discharged, and a delay in the response of the average effective pressure, resulting in acceleration shock and deterioration in acceleration response.

Therefore, the present applicant has developed a fuel control system based on the amount of engine load fluctuation obtained from the throttle valve opening (opening area of the engine intake system) and engine rotational speed, and the time to a predetermined crank angle position in the intake stroke. A system was previously proposed in which the change in the required fuel amount up to the target position is predicted and the correction amount of the fuel supply amount is set based on the prediction result (see Japanese Patent Application No. 62-269467).

However, for example, if the predetermined crank angle position (target position of fuel control) of the intake stroke is set as the intake BDC, the fuel supply start timing synchronized with engine rotation is the intake BD of each cylinder.
If it is before 360' CA of C, in order to correct the normal fuel supply amount, it is necessary to predict the amount of variation in the engine load while the engine rotates 360 degrees, and it is difficult to predict the amount of variation accurately. This has caused errors in predicted values, which has become a major problem during accelerated driving, where highly accurate air-fuel ratio control is required from the viewpoint of driving performance.

Especially in the early stages of engine acceleration when the required fuel amount changes (
(see Figure 10) and in the latter stages of acceleration when the change in the required fuel amount reaches a ceiling, the prediction error becomes large, and furthermore,
As the prediction period becomes longer, the prediction error increases, so as shown in A shown in FIG.
However, as shown in Figure 11, engine performance such as exhaust characteristics and fuel efficiency is affected by the timing of fuel supply, and the best timing is As shown by the dotted line in Figure 11, this differs depending on the engine, so depending on the engine, it may be necessary to start fuel supply 360°CA before the intake BDC as described above, and this may cause long-term engine load fluctuations. This meant that the accuracy of predictive control could not be ensured.

In addition, in areas where the amount of injection supplied by the fuel injection valve is small,
As shown in Figure 13, it is generally not possible to accurately supply the actual injection quantity relative to the set injection quantity, so in particular in small displacement engines, it is necessary to inject fuel to all cylinders simultaneously once every two revolutions of the engine. This method is used to ensure the amount of fuel injected from the fuel injector at one time to obtain accuracy in the amount of fuel supplied, so in this case as well, the period for predicting engine load fluctuations becomes longer. , accurate predictive control cannot be performed.

The present invention has been made in view of the above problems, and it is an object of the present invention to accurately correct the fuel supply amount in real time in response to an increase 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 that can improve air-fuel ratio controllability during engine acceleration operation.

Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. a required fuel amount calculation means for calculating the required fuel amount of the engine based on the state quantity detected by the engine; and a change amount calculation means for calculating the amount of change per unit time in the required fuel amount calculated by the required fuel amount calculation means. In addition to the main fuel supply synchronized with engine rotation, additional fuel supply control means is provided for additionally supplying fuel at each unit time based on the amount of change calculated by the amount of change calculation means.

Here, for example, the intake air flow rate Q measured by an air flow meter
When the required fuel amount is determined based on the intake pressure PH measured by the pressure sensor and the intake pulsation, the time-synchronized required additional supply amount (pulse width corresponding to the fuel correction equivalent to the true engine load fluctuation) as shown in FIG. On the other hand, the required amount of change ΔTp in the required fuel amount differs from moment to moment, and if a corresponding correction is made, the air-fuel ratio controllability deteriorates.

For this reason, the engine operating state detection means detects the state quantities that are related to the opening area of the engine intake system and the engine rotational speed, which are variably controlled, and the required fuel amount calculation means detects the state quantities that are respectively related to the variable controlled engine intake system opening area and the engine rotation speed. Preferably, the required fuel amount is calculated by predicting the intake air amount of the engine based on the opening area and the engine rotational speed.

Furthermore, as shown by the dotted line in FIG. It is preferable to provide a weighted average processing means that performs a weighted average calculation so that the phase state is advanced by a predetermined time, and causes the change amount calculation means to perform a change amount calculation according to the required fuel amount as a result of this weighted average result. This means that if the travel time from when additional fuel is supplied in synchronization with the time until it is sucked into the cylinder is not supplied in advance, the air-fuel ratio will drop during acceleration. It's for a reason.

<Operation> In such a configuration, the engine operating state detection means detects the state quantity of the engine related to the intake air amount of the engine, and the required fuel amount calculation means calculates the required fuel amount of the engine based on the detection result. do.

The change amount calculating means calculates the amount of change per unit time in the required fuel amount, and the additional fuel supply control means calculates the amount of change per unit time in which the amount of change is calculated, apart from the main fuel supply synchronized with engine rotation. Additional fuel is supplied to the engine based on the amount of change each time.

Here, the engine operating state detecting means may be anything that detects state quantities that are respectively related to the opening area of the engine intake system and the engine rotational speed, which are variably controlled. In this case, the required fuel amount calculating means is The required fuel amount is calculated by predicting the intake air amount of the engine from the opening area and engine rotation speed.

Furthermore, when the required fuel amount calculation means calculates the required fuel amount based on the opening area and the engine rotational speed as described above, the weighted average processing means calculates the required fuel amount calculated by the required fuel amount calculation means. A weighted average calculation is performed to obtain a phase state that is a predetermined time ahead of the change in the required fuel amount that approximately corresponds to the actual engine load, and the amount of change per unit time in the required fuel amount as a result of this weighted average is changed. The amount is calculated by the quantity calculation means.

<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 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 includes a potentiometer that detects its opening degree TVO, and an idle switch 8A that is turned on at its fully closed position (idle position).
A throttle sensor 8 including a throttle sensor 8 is attached.

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 electromagnetic fuel injection valve 10 is driven to open intermittently by a drive pulse signal output from a control unit 11 incorporating a microcomputer, which will be described later, and is fed under pressure from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator. The fuel 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 for detecting the air-fuel ratio of the engine intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas.

The control unit 11 counts the crank unit angle signal PO8 outputted from the crank angle sensor 15 in synchronization with the engine rotation for a certain period of time or at every predetermined crank angle position (every 180° in the case of a 4-cylinder engine). Then B
T D Cl2O'. ) The period of the crank reference angle signal REF is measured and the engine rotation speed N is determined.
Detect.

In addition, a transmission attached to the engine 1 is provided with a vehicle speed sensor 16 for detecting vehicle speed and a neutral sensor 17 for detecting a neutral position, and these signals are input to the control unit 11.

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 detection signals from the various sensors described above, and also calculates the fuel injection amount Ti (pulse width of the injection pulse signal).
The fuel injection valves 10 are controlled to open at predetermined timings synchronized with the engine rotation based on the engine speed to control normal fuel supply, while the fuel injection valves 10 are controlled to open at predetermined timings synchronized with the engine rotation. Controls additional supply (interrupt injection) of Further, the control unit 11 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 supply control performed by the control unit 11 will be explained according to the routines shown in the flowcharts of FIGS. 3 to 6, respectively.

In this embodiment, the functions of the required fuel amount calculation means, the change amount calculation means, the additional fuel supply control means, and the weighted average processing means are provided by software as shown in the flowcharts of FIGS. 3 to 6. ing. Further, in this embodiment, the engine operating state detection means corresponds to a throttle sensor 8 that detects the opening degree TVO of the throttle valve 7, and a crank angle sensor 15 that outputs a detection signal synchronized with the engine rotation.

Note that the internal combustion engine 1 in this embodiment is a four-cylinder engine,
Fuel supply is performed by driving and controlling the fuel injection valves 10 provided for each cylinder separately in accordance with the intake stroke of each cylinder.

The routine shown in the flowchart of FIG. 3 is executed every 10 m5.

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

In step 2, the opening area Amm of the throttle chamber 4 (of the engine intake system) is variably controlled by the throttle valve 7.
is determined by searching from a preset map based on the suit valve opening degree 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 rotational speed N, the basic volumetric efficiency QHφ (%) of the famous engine 1 during steady operation is retrieved from the map. That is, the intake air amount of the engine is predicted from the opening area A and the engine rotational speed N.

In step 4, the weighted weight X used when weighted averaging the basic volumetric efficiency QHφ determined in step 3 to approximately correspond to the true engine load change during transient operation of the engine 1 is set to the engine rotational speed N. Set based on the opening area A. Specifically, a constant a that is set according to the engine rotational speed N and a value obtained by multiplying the constant a that is also set according to the engine rotational speed N by the opening area A are added. Finally, the weighting weight X is set. This weighted weight X is
This shows the weighting for the latest basic volumetric efficiency QHφ, and since the true engine load changes faster in the high rotation and high load region relative to the throttle valve opening change, the weighted weight X is As the load area becomes larger.

In the next step 5, the basic volumetric efficiency QHφ calculated in step 3 this time according to the following formula and the volumetric efficiency QCYL calculated in step 5 during the previous execution of this routine are weighted averaged using the weighted weight X. and set the result as the latest volumetric efficiency QCYL.

QCYL←(1-X)QCYL+XXQHφ If the volumetric efficiency QCYL is determined according to the above formula, QHφ = QCYL during steady operation, and the volumetric efficiency QCYL
is stabilized at a constant value, but when the engine 1 is operated transiently, the change in the volumetric efficiency QCYL is slowed down with respect to the change in the basic volumetric efficiency QHφ depending on the engine operating state at that time, and as a result, the opening area A and the volumetric efficiency QCYL, which approximately corresponds to the actual engine load change that lags behind the change in engine rotational speed N.
is now set.

In step 6, the basic fuel injection amount (engine required fuel amount) ANTp is calculated based on the volumetric efficiency QCYL according to the opening area A and the engine rotational speed N using the following equation.

A N T p 〈-K CON A X Q CY
L Here, the calculated basic fuel injection amount ANTp is calculated based on the volumetric efficiency QCYL that approximately corresponds to the true engine load change during transient operation of the engine 1.
Intake pressure P detected by intake pressure sensor 9 described later
As shown in FIG. 7, the basic fuel injection amount TpPB set based on B is set to a value that is advanced in phase by about several tens of milliseconds.

The basic fuel injection amount ANTp is set to determine the change in the fuel amount required by the engine 1 during engine transient operation, and is a value that is phase advanced by about several tens of milliseconds with respect to the basic fuel injection amount TpPB. The basic fuel injection amount ANT takes into consideration the travel time until the fuel injected from the fuel injection valve 10 is sucked into the cylinder.
If the change in the required fuel amount is determined based on p, and additional fuel supply (interrupt injection) corresponding to the change in the required fuel amount is performed in addition to normal injection as described later, the travel time of the fuel can be taken into consideration in advance. Because of this, it can respond to changes in the required fuel amount with good responsiveness.

In addition, since the intake pressure PB pulsates under the influence of pressure pulsations occurring in the intake passage, the basic fuel injection amount 'rp
PB may also pulsate and the change in the basic fuel injection amount TpPB may not match the true change in the required amount, but the change in the required fuel amount can be calculated from the opening area A and the engine rotational speed N as described above. If the detection is based on the basic fuel injection amount ANTp, it is not affected by the pressure pulsation and has excellent detection response, so changes in the required fuel amount can be detected with high accuracy.

In the next step 7, the basic fuel injection amount ANTp calculated in step 6 during the previous execution of this routine is calculated from the basic fuel injection amount ANTp calculated in step 6 this time.
D is subtracted to obtain the basic fuel injection amount ANTp (per unit time) during the 10m5 period around which this routine is executed.
The amount of change ΔANTp is calculated. This amount of change ΔA,,N
Tp is a value corresponding to a change in the required fuel amount of the engine over a period of 10 m5, and becomes a positive value when the engine 1 is accelerated and the required fuel amount tends to increase.

In step 8, the basic fuel injection amount ANTp calculated in step 6 this time is set to the previous value AN, TPOLI+ so that it will be used for calculating the change amount ΔANTp in step 7 the next time this routine is executed. do.

In the next step 9, the amount of change ΔAN obtained in step 7
The value obtained by doubling TP is taken as the amount of change in the required fuel injection amount for one cylinder over the recent 10 m5, and the voltage correction numerator s set based on the battery voltage is added to this amount of change, and the result is is set to an interrupt injection amount Y that is added during normal fuel injection.

In this embodiment, the basic fuel supply amount for one cylinder is set to be twice the basic fuel injection amount Tp calculated based on the engine operating state for convenience. Even in the normal fuel supply control performed, the final fuel injection amount Ti is calculated by doubling the basic fuel injection amount TpPB obtained from the intake pressure PB, so the amount of change is ΔANTp is multiplied by 2. Furthermore, even if the fuel injection valve 10 is driven and controlled based on this value 2×ΔANTp, there is actually a response delay time of the fuel injection valve 10, and this delay is caused by the battery that is the driving power source of the fuel injection valve 10. It changes depending on the voltage of
By adding the voltage correction numerator s set based on the battery voltage, fuel corresponding to 2×ΔANTp is actually injected and supplied from the fuel injection valve 10.

In the next step 10, the change amount Z in the required fuel amount during 10 m5, which is the value obtained by subtracting the battery voltage correction numerator s from the interrupt injection amount Y, is set as the change amount Z.

Then, in step 11, the interrupt injection amount Y (←2×ΔANTp+Ts) set in step 9 is added to the integrated amount, which is the carryover interrupt injection amount in the #4 cylinder, which has been integrated without interrupt injection until the previous time. The value obtained by adding the value ΣQ4 and the minimum injection amount T t, Iin for which interrupt injection control is permitted.
Compare with.

When Y0ΣQ4 is smaller than T1m1n, the process proceeds to step 12 without performing interrupt injection,
The accumulated value Σ up to the previous time is added to Z set in step 10 above.
Q4 is added and the result is set as a new integrated value ΣQ4. Therefore, the integrated value ΣQ4 becomes an interrupt injection amount that should be additionally injected in the #4 cylinder based on the change amount ΔANTp, but is currently not injected and carried over.

The minimum injection amount T1m1n is such that if the fuel injection valve 10 is driven and controlled based on an injection amount less than this T1mzn, there will be a large variation in the fuel actually injected from the fuel injection valve 10 with respect to the valve opening drive time, and the valve will not open. This indicates that the fuel injection amount cannot be accurately controlled by controlling the driving time (see FIG. 13).

Therefore, in step 11, the interrupt injection amount Y + the integrated value ΣQ
4 is smaller than the minimum injection amount T 1m1n, no interrupt injection (additional injection) is performed this time, and the interrupt injection amount for all injections is carried over to the next time (this carryover amount corresponds to ΣQ4). ), next time, the interrupt injection amount Y is further added to this carried over amount, and the result is the minimum injection amount T.
Interrupt injection is performed when the angle exceeds i, 1°.

That is, when the interrupt injection amount is smaller than the minimum injection amount 71a+in, accurate fuel supply control cannot be performed even if interrupt injection is performed, so the current interrupt injection amount is carried over to the next time and the integrated result is Interrupt injection is performed when the minimum injection amount Tx,... is exceeded, and when the integrated value ΣQ4 remains without being injected until the normal fuel injection start time in #4 cylinder, it is synchronized with the engine rotation. The amount ΣQ4 carried over without being injected is added to the normal fuel supply, and the fuel is injected, and at this time, the integrated value ΣQ4 is reset to zero. Furthermore, the interrupt injection amount Y set in step 9 is
Every time the minimum injection amount T1m1n is exceeded, 10ms
An interrupt is executed each time (see FIG. 9).

If it is determined in step 11 that the interrupt injection amount Y+integrated value ΣQ4 is greater than or equal to the minimum injection amount Ti, 47, step 13
Then, the flag F100d4 for determining the allowable crank angle range for interrupt injection in the #4 cylinder is determined. As described later, the flag F 100d 4 is the cylinder discrimination value ncyj! becomes 4 (reference angle signal R
This is when EF is the ignition reference signal for the #1 cylinder, and is also the normal injection start time for the #4 cylinder. )from,#
Zero is set between the 4-cylinder intake BDC (or a predetermined crank angle between intake ATDC 100° and intake BDC), and 1 is set otherwise, and when flag F100d 4 is zero Interrupt injection is now permitted (see Figure 8).

Crank angle range in which zero is set to flag F 100d 4 (from intake BTDC 120° to intake ATDC 100°)
゜～Intake BDC) is the intake stroke (intake valve open: ■NT/V 0PE) in which the supplied fuel is taken in after the normal fuel supply starts in the #4 cylinder.
This indicates the time up to the last fuel injection period when fuel is taken in at N), and even if an interrupt injection is performed at a time exceeding the above crank angle range, it will not be taken into the cylinder during the current intake stroke and a new fuel will be injected. The fuel remains upstream of the intake valve until the next intake stroke when the normal fuel injection amount is set. In this embodiment, the flag F100d is set to accommodate changes in the required fuel amount from the start (set) of normal fuel injection until the intake stroke.
When 4 is 1, interrupt injection for #4 cylinder is #4
This becomes an excess correction in the cylinder.

Therefore, when it is determined in step 13 that the flag F 100d 4 is zero, the interrupt injection amount based on the change amount ΔANTp (2×ΔANT p +T s + ΣQ4)
In contrast, when flag F 100d 4 is 1, interrupt injection is prohibited, or interrupt injection is performed but this interrupt injection is carried over to the next intake stroke without being inhaled immediately. The integrated value Σq4 of the injection amount is determined, and this integrated value Σq4 is calculated from the fuel injection amount Ti of the next normal injection in the #4 cylinder performed every reference angle signal REF.
is subtracted to supply fuel.

That is, if it is determined in step 13 that the flag F 100d 4 is zero, the process proceeds to step 15 and 2×ΔAN
A drive pulse signal with a pulse width equivalent to Tp+Ts+ΣQ4 is output to the fuel injection valve 10 provided in the #4 cylinder, and the #4
In addition to the normal injection for each reference angle signal REF, fuel corresponding to the change in the required fuel amount is injected into the cylinder in an interrupt manner. Then, in the next step 16, since the interrupt injection including the integrated value 294 minutes was performed in step 15, the integrated value ΣQ4
Reset to zero.

Furthermore, when the timing of the interrupt injection is during normal fuel injection in the #4 cylinder, it is sufficient to output an interrupt drive pulse signal having a pulse width equivalent to 2×ΔANTp+ΣQ4 following the end of the normal fuel injection. .

On the other hand, if it is determined in step 13 that the flag F 100d 4 is 1, then even if interrupt injection is performed on the #4 cylinder, there is no intake in the recent intake stroke, so interrupt injection is permitted. In this case, in step 14, the current interrupt injection amount 2×ΔANTp×ΣQ4 and the previous non-intake interrupt injection cumulative value Σq4 are added, and if cylinder #4 is not inhaled in the recent intake stroke, the next Find the total amount of interrupt injection that remains upstream of the intake valve until the intake stroke.

Here, the set integrated value Σq4 is not inhaled until the next intake stroke of cylinder #4 and remains upstream of the intake valve of cylinder #4.
This integrated value Σq4 is subtracted from the next normal injection of the 4 cylinders to correct the stagnation, so that the stagnation upstream of the intake valve is not excessively supplied into the cylinder due to the interrupt injection. do it like this.

When the integrated value Σq4 is updated and set in step 14, the process proceeds to the next step 15, where 2×ΔANTp+Ts+
An interrupt drive pulse signal with a pulse width equivalent to ΣQ4 is
It is output to the four-cylinder fuel injection valve 10, and in the next step 16, the integrated value ΣQ4 is reset to zero.

Furthermore, when it is determined in step 13 that the flag F 100d 4 is 1, even if the interrupt injection is performed, the intake will not be immediately injected into the #4 cylinder. Therefore, as shown by the dotted line in FIG. The interrupt injection may be prohibited by jumping through steps 14 to 16. In this case, all the injected fuel is sucked into the cylinder during the recent intake stroke, so the setting of the integrated value Σq4 is No longer needed.

The above steps 11 to 16 are arithmetic processing for interrupt injection control in cylinder #4, but for other cylinders #2. #
1. Similar arithmetic processing is performed simultaneously in #3 as well.

That is, the interrupt injection amounts ΣQ1 to ΣQ4 that are carried over without interrupt injection are set for each cylinder, and the sum of this carried over amount and the latest calculated interrupt injection amount Y is the minimum injection amount T.
Interrupt injection is performed when i1 or above, and the flag F indicates that the interrupt injection timing is not within the crank angle range in which interrupt injection is permitted in that cylinder.
When it is determined at 100d4, the interrupt injection amounts Σq1 to Σq4 that are not inhaled are integrated for each cylinder in order to subtract the interrupt injection amount from the next normal injection amount synchronized with the reference angle signal REF. Such interrupt injection control is performed in steps 17 to 22 for the #2 cylinder and steps 23 to 22 for the #1 cylinder.
28, steps 29 to 34 are performed in the #3 cylinder, so that interrupt injection can be performed in multiple cylinders at the same time (see FIG. 9).

Therefore, according to this embodiment, Y+ΣQ1~4≧T1m+
When the conditions of n are met, interrupt injection is performed simultaneously in each cylinder every 10m5, which is the execution cycle of this routine, and normal fuel supply (main fuel supply) synchronized with engine rotation is started. In other words, if the required fuel amount of the engine increases after the normal fuel supply amount is finally set, it is possible to additionally supply the increased amount of fuel to the engine. Improves air-fuel ratio control during acceleration. However, since the interrupt injection control does not predict changes in the required fuel amount over a long period of time, but directly calculates the amount of change in the required fuel amount per unit time (10 ms), the fuel correction control fewer errors,
Further, unlike the case where the interrupt injection amount is set based on a change in the throttle valve opening degree T■0, etc., the number of man-hours required to match the interrupt injection amount with the engine request is not required.

After controlling the interrupt injection based on the change in the required fuel amount for each cylinder in this way, in the next step 35, the volumetric efficiency correction coefficient KQCYL used to calculate the basic fuel injection amount TpPB based on the intake pressure PB is Set. The volumetric efficiency correction coefficient KQCYL is calculated based on the intake pressure PB in step 41 of the background job shown in FIG.
It is obtained by multiplying by a minute correction coefficient KFLAT set based on the engine speed N and the engine speed N.

In the next step 36, the intake pressure PB is calculated according to the following formula:
A basic fuel injection amount TpPB for normal fuel supply is calculated based on .

TpPB4-KCONDXPBXKQCYLXKTA Here, KCOND is a constant based on the injection characteristics of the fuel injection valve 10, and KTA is the intake air temperature TA that is set based on the intake air temperature TA detected by the intake air temperature sensor 6 in step 42 of the background job shown in the fourth song. This is a temperature (intake air density) correction coefficient.

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

Ti ←2XTpPBXLAMBDAXCOEF+T
sHere, LAMBDA calculates the air-fuel ratio detected through the oxygen concentration in the exhaust gas detected by the oxygen sensor 14,
C0EF is an air-fuel ratio feedback correction coefficient that is feedback-controlled to approach the target air-fuel ratio, and Ts is various correction coefficients that are set according to operating conditions such as the cooling water temperature Tw detected by the water temperature sensor 12. This is the same battery voltage correction used when implementing interrupt injections based on changes in the amount of fuel required.

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

In this embodiment, the reference angle signal REF is BTDC
This reference angle signal REF is the reference position for ignition timing control for each cylinder, and also controls the timing of the intake stroke for each cylinder in synchronization with this reference angle signal REF. At the same time, normal fuel injection is performed. The reference angle signals R and EF are designed to enable cylinder discrimination in correspondence with the cylinder that is the ignition reference position. For example, when the reference angle signal REF is the ignition reference position for the #1 cylinder, the fuel is determined for the #4 cylinder. When the fuel injection is started and the reference angle signal REF is at the ignition reference position of the #3 cylinder, fuel injection is started for the #2 cylinder (see FIG. 8).

First, in step 51, it is determined whether the current reference angle signal REF corresponds to the ignition reference position of the #1 cylinder. Here, if it is determined that the ignition reference position is for the #1 cylinder, the process advances to step 52 and the fuel injection valve 10 of the #4 cylinder, which is the cylinder where normal fuel injection synchronized with the engine rotation should be started, is activated. On the other hand, a drive pulse signal having a pulse width equivalent to Ti+ΣQ4-Σq4 is output.

ΣQ4 is a value corresponding to the change in the amount of required fuel remaining without interruption injection in the #4 cylinder up to the current reference signal REF, and Σq4 is the value corresponding to the change in the required fuel amount remaining without interruption injection in the #4 cylinder up to the current reference signal REF. Since this is fuel that has been injected but remains without being sucked into the cylinder, it is corrected by adding and subtracting each amount from the normal fuel injection amount Ti.

Furthermore, the fuel injection amount Ti used in step 52 is the latest value of the fuel injection amount Ti calculated every 10 m5 according to the flowchart in FIG.

In the next step 53, the flag F100d4 for determining whether or not the fuel injected in the #4 cylinder is sucked into the cylinder is set to zero, and the #4 cylinder is determined from the current reference angle signal REF. It is possible to determine that the fuel injected in is being sucked into the cylinder during the most recent intake stroke.

Note that the flag F 1ood 4 is set to zero here.
is configured to be set to 1 at the intake BDC of the #4 cylinder according to the flowchart in FIG. 6, which will be described later.
Flag F 100d 4 is the ignition reference position of #1 cylinder (#
Zero is set only during the period from the normal injection start timing of the #4 cylinder to the intake BDC of the #4 cylinder.

Furthermore, in step 54, ΣQ4 and Σq4, which were used to correct 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 are respectively newly set.

In step 55, the cylinder discrimination value ncyj2 is set to 4, and based on the cylinder discrimination value ncyj2, the normal injection start time of the #4 cylinder until before the normal injection start time of the next injection cylinder, the #2 cylinder, is determined. so that it can be determined that it is the time.

On the other hand, in step 51, the current reference angle signal REF is #1.
If it is determined that the position does not correspond to the cylinder ignition reference position, the process proceeds to step 56 and the current reference angle signals RE, F are determined.
It is determined whether or not corresponds to the ignition reference position of the #3 cylinder.

Here, when the current reference angle signal REF corresponds to the ignition reference position of the #3 cylinder, Ti+ΣQ2Σq2 is performed as 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 driving pulse signal with a corresponding pulse width is output (step 57), while the flag F100d2 is reset to zero in step 58.
), the data of ΣQ2 and Σq2 used for normal fuel control are reset to zero (step 59), and the cylinder discrimination value ncyI! , is set to 2 (step 60).

On the other hand, if it is determined in step 56 that the ignition reference position does not correspond to the ignition reference position of the #3 cylinder, the process proceeds to step 61 and determines whether or not the reference angle signal REF corresponds to the ignition reference position of the #4 cylinder. When the ignition reference position is for the #4 cylinder, normal fuel injection is performed for the #1 cylinder and various data corresponding to the #1 cylinder are set in the same manner as described above (steps 62 to 65).

Furthermore, when it is determined in step 61 that the ignition reference position is not for the #4 cylinder, the current reference angle signal REF is set to the #2 cylinder ignition reference position.
This should be the cylinder's ignition reference position, so step 66~
At step 69, normal fuel injection is performed for the #3 cylinder and various data corresponding to the #3 cylinder are set.

Next, the routine shown in the flowchart of FIG. 6 is executed interruptively at the TDC position of each cylinder. For example, a counter is provided to input the reference angle signal REF from the crank angle sensor 15 and the unit angle signal PO3. , the reference angle signal RE output by this counter at BTDC120°
When the TDC position is detected by counting the unit angle signal PO3 from F and an interrupt signal is output to the external interrupt terminal of the CPU at the TDC position, the interrupt routine shown in FIG. 6 is executed. has been done.

First, in step 81, the cylinder discrimination value ncyffi is set to 2.
If the cylinder discrimination value ncyl is 2, the process proceeds to step 82 and the flag F100d4 is determined.
Set 1 to . Cylinder discrimination value ncyj! is 2, as shown in FIG. 8, the intake BTDC1 of the #2 cylinder
In the range of 20° to 1806, TDC at this time
is the intake TDC of the #2 cylinder and is also the intake BDC of the #4 cylinder. Therefore, at TDC when the cylinder discrimination value ncyl is 2, it is detected that the #4 cylinder has become the intake BDC, and even if fuel is injected beyond this period in the #4 cylinder, the intake stroke will continue until the next intake stroke. Therefore, the flag F 100d 4 is set to 1 so that it can be determined that it is time for the injected fuel for the #4 cylinder to stagnate.

Further, in step 81, the cylinder discrimination value ncyj! If it is determined that the cylinder determination value nc is not 2, the process proceeds to step 83 and the cylinder determination value nc is determined.
Determine whether yj2 is 1 or not. Cylinder discrimination value ncy
If j2 is 1, as shown in Figure 8, the current TDC
corresponds to the intake BDC of #2 cylinder, so step 84
The program then proceeds to set the flag F 100d 2 to 1.

Furthermore, in step 83, the cylinder discrimination value ncyj! If it is determined that the cylinder determination value ncyjl! is not 1, the process advances to step 85 and the cylinder determination value ncyjl! is 3 or not. If the cylinder discrimination value ncyj2 is 3, the current TD
Since C corresponds to the intake BDC of #1 cylinder, step 8
Proceed to step 6 and set the flag F100dl to 1.

Further, when it is determined in step 85 that the cylinder discrimination value ncyffi is not 3, the cylinder discrimination value ncyI! , should be 4, so proceed to step 87 and set the flag F.
Set 1 to 100a 3.

In this way, when the intake BDC of each cylinder is reached, the flag F
100dl~F100d4 is set to 1, and flags F100dl~F100d4 determine whether or not fuel is being injected into that cylinder and sucked into the cylinder during the recent intake stroke. It is possible to do so.

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 the intake air flow rate Q is detected instead of the intake pressure sensor 9. Equipped with an air flow meter,
The normal fuel supply amount may be calculated based on the intake air flow rate Q detected by the air flow meter.

Furthermore, in this embodiment, the fuel is injected separately at the timing of the intake stroke of each cylinder, but in some cases, the fuel injection valves 10 of all cylinders may be actuated and controlled simultaneously, or in a group consisting of a plurality of cylinders. Even if the fuel injection valves 10 are driven and controlled simultaneously in units, similar effects can be obtained by performing interrupt injection as in this embodiment. Furthermore,
Even when normal fuel is supplied to each cylinder at a timing that matches the intake stroke of each cylinder, the injection start timing is not limited; 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 explained above, according to the present invention, fuel is additionally supplied every unit time based on the amount of change in the required fuel amount per unit time, so that the engine rotation is synchronized with the engine rotation. It is possible to accurately perform fuel correction in response to an increase in the amount of fuel required, which cannot be accommodated by normal fuel supply, and the air-fuel ratio controllability during engine acceleration is improved.

In addition, by calculating the required fuel amount based on the opening area of the engine intake system and the engine rotation speed, it is possible to avoid fluctuations in the required fuel amount calculated for setting the additional fuel amount to be supplied due to intake pulsation. This prevents incorrect additional supply of fuel due to the influence of intake pulsation.

Furthermore, when calculating the required fuel amount based on the opening area and the engine rotational speed, a weighted average calculation is performed so that the phase state is advanced by a predetermined time from the change in the required fuel amount that approximately corresponds to the actual engine load. As a result, the amount of change in the required fuel amount can be calculated in consideration of the travel time of the fuel, and by supplying additional fuel based on the amount of change, additional fuel can be supplied with good response.

[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 6 are flowcharts showing control details in the above embodiment, and FIG. The figure is a time chart for explaining the characteristics in the weighted average calculation of the required fuel amount in the above embodiment,
FIGS. 8 and 9 are time charts for explaining the control characteristics in the above embodiment, respectively. FIG. 10 is a time chart for explaining the problems of conventional fuel correction control. FIG. 11 is the fuel supply timing. Fig. 12 is a time chart showing the amount of change in the required fuel amount when the required fuel amount is calculated from the intake pressure.
FIG. 3 is a diagram showing the injection characteristics of the fuel injection valve. 1...Engine 4...Thrower 5...Intake manifold 8...Throttle sensor 10...Fuel injection valve Engineering 1...K15...Crank angle sensor Torchan huff...Throttle valve 9...Intake Pressure Sensant Trol Unit Patent Applicant Japan Electronics Co., Ltd. Agent Patent Attorney Fujio Sasashima

Claims (3)

[Claims] (1) A fuel supply control device for an internal combustion engine configured to calculate a fuel supply amount corresponding to the intake air amount of the engine and intermittently supply fuel to the engine at a timing synchronized with the engine rotation, the device comprising: an engine operating state detection means for detecting a state quantity of the engine related to the intake air amount; a required fuel quantity calculation means for computing a required fuel quantity of the engine based on the state quantity detected by the engine operating state detection means; a change amount calculating means for calculating the amount of change per unit time in the required fuel amount calculated by the required fuel amount calculating means; A fuel supply control device for an internal combustion engine, comprising: additional fuel supply control means for additionally supplying fuel every unit time based on the fuel supply control means. (2) The engine operating state detecting means detects state quantities that are respectively related to the opening area and engine rotation speed of the engine intake system which are variably controlled, and the required fuel amount calculating means detects state quantities that are related to the opening area and the engine rotation speed of the engine intake system which are variably controlled, and the required fuel amount calculating means 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein the fuel supply control device for an internal combustion engine is configured to calculate the required fuel amount by predicting the intake air amount of the engine from the engine rotational speed. (3) A weighted average calculation is performed on the required fuel amount calculated by the required fuel amount calculating means so that the required fuel amount is in a phase state that is advanced by a predetermined time from a change in the required fuel amount that approximately corresponds to the actual engine load, and 3. The fuel supply control device for an internal combustion engine according to claim 2, further comprising weighted average processing means for causing the change amount calculation means to calculate the amount of change in accordance with the required fuel amount of the average result.