JPH0192546A - Fuel supply control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to prevent mis-fire even during acceleration, in an engine in which the amount of fuel is compensated so as to be increased during acceleration, by changing the acceleration increase compensating fuel amount between the case of acceleration from normal operation and the case of acceleration from deceleration. CONSTITUTION:During operation of an engine, a basic fuel computing means (c) computes a basic fuel supply amount in accordance with an operating condition of the engine detected by an operating condition detecting means (a). When an acceleration means (b) judges that the engine is shifted into an accelerating condition, a compensating amount computing means (d) computes a first acceleration increase compensating fuel amount upon acceleration from normal operation, or computes a second acceleration increase compensating amount upon acceleration from deceleration. Further, a supply amount setting means (e) compensates a basic supply amount in accordance with these acceleration compensating increase fuel amounts so as to set a final fuel supply amount, and accordingly, the amount of fuel fed to an engine from a fuel supply means (f) is controlled in accordance with the final fuel supply amount.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel supply device for an engine such as an automobile, and particularly to a device that performs fuel increase correction during acceleration.

(Prior art) Generally, when the required output for the engine changes,
It is necessary to control the fuel supply amount with good responsiveness according to the degree of demand, and this affects the air-fuel ratio particularly during transient operation, and influences driving performance such as drive feeling and exhaust composition.

Conventional fuel supply control devices for this type of internal combustion engine include:
For example, there is one described in Japanese Patent Publication No. 47-41288.

This device calculates the basic injection amount based on the intake air amount and engine speed, and also detects the opening degree of the throttle valve.
When the rate of increase exceeds a certain value, temporary addition of fuel is immediately performed independently of the basic injection amount, and the increase is corrected according to the degree of acceleration.In addition, during sudden acceleration, an asynchronous addition of fuel is performed separately from normal fuel injection control. Injection (interrupt injection) is performed to improve driving performance.

That is, since the amount of intake air increases rapidly during acceleration, the air-fuel ratio may be significantly leaner at the time of actual fuel injection than at the time of measurement. As described above, when the air-fuel ratio becomes excessively lean during acceleration, problems such as deterioration of acceleration response occur, resulting in deterioration of drivability. Therefore, in order to prevent the air-fuel ratio from becoming lean during acceleration to avoid deterioration in drivability, conventional examples perform synchronous or asynchronous fuel injection during acceleration as described above.

(Problem to be solved by the invention) However, in such a conventional fuel supply control device for an internal combustion engine, there is a large difference in the air-fuel ratio at the beginning of acceleration between acceleration from steady state and re-acceleration from deceleration. Despite this, the acceleration increase correction amount was the same in the same acceleration state, so if the acceleration increase correction is applied to acceleration from steady state, rich misfire will occur due to the enrichment of the air-fuel ratio when accelerating from deceleration. This may have a negative effect on drivability and exhaust emissions.On the other hand, if the acceleration increase correction is applied to an acceleration state from deceleration, lean misfire will occur due to the lean air-fuel ratio when accelerating from steady state, resulting in poor drivability and exhaust emissions. There was a problem that it worsened.

That is, the solid lines in Fig. 5 (A) to (C) show the changes in the throttle valve opening TVO1 air-fuel ratio and the combustion chamber pressure Pi when the state shifts from a steady state to an acceleration state, and the changes in the throttle valve opening TVO1 air-fuel ratio and combustion chamber pressure Pi when the state shifts from a steady state to an acceleration state are shown in solid lines. Valve opening TVO1 air-fuel ratio and combustion chamber pressure P
The change in i is shown by the broken line in the same figure. With respect to the change in the throttle valve opening TVO, the air-fuel ratio is on the lean side during acceleration from steady state, and when viewed in terms of the combustion chamber pressure Pi, it is shown by the solid line in the same figure (C). A lean misfire will occur. On the other hand, during re-acceleration after deceleration, the air-fuel ratio is on the Lynch side, and when viewed from Pi, the same figure (C
), a rich misfire occurs as shown by the broken line.

(Objective of the Invention) Therefore, the present invention prevents lean misfires when accelerating from steady state and rich misfires when accelerating from deceleration by changing the acceleration increase correction amount depending on acceleration from steady state and acceleration from deceleration. The aim is to improve driveability and exhaust emission characteristics.

(Means for Solving the Problems) In order to achieve the above object, the fuel supply control device for an internal combustion engine according to the present invention has an operating state detection system that detects the operating state of the engine, as shown in FIG. Means a, acceleration detection means for detecting that the engine is in an acceleration state, basic value calculation means C for calculating the basic supply amount of fuel based on the operating state of the engine, and when the engine shifts to an acceleration state. If the acceleration is from a steady state, a first acceleration increase correction amount is calculated to correct the basic supply amount, and if it is an acceleration from a deceleration state, a second acceleration increase correction amount is calculated to correct the basic supply amount. The final supply amount is determined based on the outputs of the correction amount calculation means d and the basic value calculation means C, and when the engine shifts to an acceleration state, the basic supply amount is corrected based on the first or second acceleration increase correction amount. a supply amount setting means e for setting the final supply amount; a fuel supply means f for supplying fuel to the engine based on the output of the supply amount setting means e;
It is equipped with

(Function) In the present invention, when the engine shifts from a steady state to an acceleration state, the basic supply amount is increased according to the first acceleration increase correction amount, and when the engine shifts from a deceleration state to an acceleration state, the basic supply amount is increased. The increase is corrected in accordance with the second acceleration increase correction amount. Therefore, an appropriate acceleration increase correction amount is supplied according to the air-fuel ratio at the initial stage of acceleration, and a lean misfire when accelerating from a steady state and a rich misfire when accelerating from deceleration are prevented.

(Example) Hereinafter, the present invention will be explained based on the drawings.

2 to 4 are diagrams showing one embodiment of the present invention.

First, the configuration will be explained. In FIG. 2, ▪ is an engine, in which intake air is supplied from an air cleaner 2 to each cylinder through an intake pipe 3, and fuel is injected by an injector (fuel supply means) 4 based on an injection signal Si. The exhaust gas combusted in the cylinders is introduced into the catalytic converter 6 through the exhaust pipe 5, where it removes harmful components (C) from the exhaust gas.
o, HC, NOx) are purified by a three-way catalyst and discharged.

The intake air flow rate Q is detected by an air flow meter 7 and controlled by a throttle valve 8 in the intake pipe 3. The opening TVO of the throttle valve 8 is detected by a throttle valve opening sensor (acceleration detection means) 9, and the rotation speed N of the engine 1 is detected by a crank angle sensor 10.
Detected by Further, the temperature TW of the cooling water flowing through the water jacket is detected by a water temperature sensor 11, and the idle state of the engine is detected by an idle switch 12. The idle switch 12 is ON when the throttle valve 8 is at a predetermined idle opening, and O when the throttle valve 8 is at a predetermined idle opening.
FF. Furthermore, the oxygen concentration in the exhaust gas is determined by the oxygen sensor 13.
The oxygen sensor 13 used has a characteristic that its output Vs suddenly changes at the stoichiometric air-fuel ratio.

The air flow meter 7, the throttle valve opening sensor 9, the crank angle sensor 10, and the idle switch 12 constitute the operating state detecting means 14, the water temperature sensor 11, the idle switch 12, and the oxygen sensor 13.
The output from is input to the control unit 15.

The control unit 15 has functions as a basic value calculation means, a correction amount calculation means, and a supply amount setting means.
21, ROM22, RAM23 and I10 port 24
Consisted of. The CPU 21 takes in necessary external data from the I10 boat 24 according to the program written in the ROM 22, and while exchanging data with the RAM 23, calculates processing values necessary for fuel supply control. , and outputs the processed data to the I10 boat 24 as necessary. Signals from the sensor group 7.9.10.12.13 are input to the I10 boat 24, and the injection signal Si is input from the I10 port 24.
is output. The ROM 22 stores calculation programs for the CPU 21, and the RAM 23 stores data used in calculations in the form of a map or the like.

Next, the effect will be explained.

FIG. 3 is a flowchart showing a fuel supply control program, and this program is executed once every predetermined period. First, the opening TVO of the throttle valve 8 is read at Pl, and the opening change (load speed) ΔTVO/Δt is calculated at P2. Next, in P3, the current opening degree change ΔTVO/Δt is compared with a predetermined value to determine whether the engine is in an accelerated state.

When not in an acceleration state (in steady operation), use the following formula in P4■
A normal basic injection amount (basic pulse width) Tp is calculated according to the following.

'rp=K・ □ ・・・・・・■ However, K: Constant Q: Intake air amount N: Engine speed
2 is turned on for a predetermined time (in this example, 0.5
sec) has elapsed (idle switch ON≧0.5
If the idle switch is ON < 0.5, it is determined that the acceleration is from steady running and the air-fuel ratio immediately after acceleration is on the lean side, and fuel injection during acceleration is performed according to the following formula (■) in P6. Calculate the quantity T I) +.

'rp, = MX5+K・-・・・・・・・■ However, M: Acceleration increase pulse width 5: Number of interruptions (5 injections) On the other hand, when the idle switch is ON≧0.5, the acceleration is from deceleration driving. Judging that the air-fuel ratio immediately after acceleration is on the rich side, P, the fuel injection amount during acceleration is calculated according to the following formula 〇.
I) Calculate z.

Tp2=Mx5Xα10K・−・・・・・・■However, α:
Deceleration correction coefficient Next, in P8, the above T p , T p + or '
rp2 is stored in the I10 register, and an injection signal Si having a fuel injection pulse width corresponding to Tp, Tp+, TI)2 is output to the injector 4 at a predetermined crank angle, and the current process ends.

Figure 4 (A) to (C) show the throttle valve opening TVO1 after the start of acceleration.
5 is a timing chart showing changes in air-fuel ratio and combustion chamber pressure Pi. As shown in Figure (A), in the case of acceleration from steady state, the air-fuel ratio immediately after acceleration is on the lean side and lean misfires are likely to occur. The basic injection amount is corrected by the 1-acceleration increase correction amount). Furthermore, in the case of deceleration, the air-fuel ratio is on the rich side and rich misfire is likely to occur, so the basic injection amount is corrected by the acceleration increase correction amount (second acceleration increase correction amount) multiplied by the deceleration correction coefficient. Therefore, the same figure (
As shown in Fig. B), the air-fuel ratio changes depending on the acceleration state, regardless of whether the acceleration is from steady state or from deceleration, and as shown in Fig. As is clear, the occurrence of lean misfires and rich misfires can be appropriately prevented.

(Effect) According to the present invention, since the acceleration increase correction amount is changed depending on acceleration from steady state and acceleration from deceleration, lean misfire when accelerating from steady state and rich misfire when accelerating from deceleration can be prevented. It is possible to improve drivability and exhaust emission characteristics.

[Brief explanation of the drawing]

Fig. 1 is a basic conceptual diagram of the present invention, Figs. 2 to 4 are diagrams showing an embodiment of the present invention, Fig. 2 is an overall configuration diagram thereof, and Fig. 3 is a diagram showing an embodiment of the present invention.
FIG. 4 is a flowchart showing the fuel supply control program, FIG. 4 is a timing chart for explaining its operation, and FIG. 5 is a timing chart for explaining its operation, showing a conventional fuel supply control device for an internal combustion engine. It is. 1...Engine, 4...Injector (fuel supply means), 9...
... Throttle valve opening sensor (acceleration detection means), 14...
... Operating state detection means, 15... Control unit (basic value calculation means, correction amount calculation means, supply amount setting means).

Claims (1)

[Scope of Claims] a) Operating state detection means for detecting the operating state of the engine; b) Acceleration detection means for detecting that the engine is in an accelerated state; c) Based on the operating state of the engine, determining the basis of fuel a basic value calculation means for calculating the supply amount; d) when the engine shifts to an acceleration state, calculates a first acceleration increase correction amount that corrects the basic supply amount if the acceleration is from a steady state; e) correction amount calculation means for calculating a second acceleration increase correction amount for correcting the basic supply amount if the acceleration is: e) determining the final supply amount based on the output of the basic value calculation means, and and f) supply amount setting means for correcting the basic supply amount based on the first or second acceleration increase correction amount to set a final supply amount; f) supplying fuel to the engine based on the output of the supply amount setting means; A fuel supply control device for an internal combustion engine, comprising: a fuel supply means for supplying fuel;