JPS6375327A - Fuel feed control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve acceleration and deceleration performance, by a method wherein, during acceleration and deceleration, a correction amount, reloadably stored at each running region, is read, and based on a detecting value from a wide range type O2 sensor, the correction amount is corrected from a devia tion between the detecting value and a demand air-fuel ratio. CONSTITUTION:A control unit 11 computes a fundamental fuel injection amount, based on an intake air amount from an airflow meter 6 and the number of revolutions from a crank angle sensor 10, and performs various kinds of correc tion based on detecting values from a throttle opening sensor 8, a water tempera ture sensor 12, a wide range type O2 sensor 14. Namely, during steady running in that a change factor of the opening of a throttle valve is below a given value, feedback correction is performed based on a detecting value from the O2 sensor 14. During acceleration and deceleration, a correction factor is read according to a change rate of the opening of the throttle valve, the number of revolutions, and a water temperature for setting, meanwhile, based on a difference between a present and a preceding value of an output from the O2 sensor 14, the correction factor is corrected.

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 particularly to control of the amount of fuel supplied during engine acceleration/deceleration.

(Prior Art) Conventionally, there are the following types of fuel supply devices for internal combustion engines.

That is, the intake air flow i detected by the air flow meter
The basic fuel supply amount Tp (=KXQ/N; is a constant) is calculated from 1Q and the engine rotational speed N detected by a crank angle sensor, etc., and various correction coefficients are calculated depending on the engine operating state such as the engine temperature. After calculating the air-fuel ratio feedbank correction coefficient α set based on C0EF, the oxygen concentration in the exhaust from the oxygen sensor installed in the exhaust passage, and the correction numerator s based on the battery voltage, the basic fuel injection ITp is corrected. final fuel injection ff1Ti (=TpxCO
EFxα+Ts).

Then, by outputting an injection pulse signal with a pulse width corresponding to the set fuel injection fiTi to the electromagnetic fuel injection valve, a predetermined amount of fuel was injected and supplied to the engine (Japanese Patent Laid-Open No. 59-203828 (Refer to the publication number, etc.)

By the way, when accelerating or decelerating the engine, air-fuel ratio feedback control based on the detection of the oxygen sensor is performed due to a delay in fuel supply, a delay in the detection of the intake air flow rate by the air flow meter, a delay in the calculation of the fuel injection amount, etc. Because of the response delay, air-fuel ratio feedback control is only performed during gentle accelerations and decelerations with relatively little response delay. Under acceleration and deceleration conditions exceeding a certain level, the air-fuel ratio feedback control is performed to correct fluctuations in the air-fuel ratio. The injection amount is being corrected to increase (during acceleration).

(Problem to be solved by the invention) However, even if the fuel increase/decrease correction amount is set in advance according to the acceleration/deceleration state, it is difficult to obtain good air-fuel ratio characteristics corresponding to various driving conditions. There are limits, and there are also variations and changes over time.

In addition, normal oxygen sensors can only detect whether the air-fuel ratio is rich or lean with respect to a predetermined value (for example, the stoichiometric air-fuel ratio) in an on/off manner. However, it was not always possible to perform well.

On the other hand, in recent years, instead of the oxygen sensor that performs on-off detection, an oxygen sensor that can measure the oxygen concentration in a gas over a wide range has been developed (SAE paper 85).
0378. (See Japanese Patent Application No. 167440/1983, etc.)

Therefore, if such a wide-range oxygen sensor is used as an air-fuel ratio sensor and a method is adopted in which the air-fuel ratio is feedback-controlled to a target value, an ON signal that only determines whether the air-fuel ratio is richer or leaner than one point (for example, the stoichiometric air-fuel ratio) , the air-fuel ratio control accuracy is greatly improved compared to the case where an OFF type oxygen sensor is used.

However, since wide-area oxygen sensors need to pump out and pump oxygen ions in response to changes in the air-fuel ratio, there is a considerable detection delay, and air-fuel ratio feedback control based on the detection from the sensor is required during acceleration and deceleration. cannot be done.

The present invention was developed in view of these conventional problems. During acceleration/deceleration operation, the amount of fuel supplied is adjusted to increase or decrease according to the acceleration/deceleration operation state, while adjusting the characteristics of the parts (fuel injection valve, air flow, etc.). In many cases, the acceleration/deceleration engine mixture ratio tends to deviate from the required mixture ratio due to variations or deterioration in the acceleration/deceleration engine (meters, etc.). It is an object of the present invention to provide a fuel supply control device for an internal combustion engine that can satisfy a required air-fuel ratio during deceleration as much as possible, thereby improving acceleration and deceleration performance as much as possible.

Means for Solving the Problems> Therefore, as shown in FIG. A wide-area oxygen sensor that detects oxygen concentration over a wide area, an acceleration/deceleration detection means that detects the acceleration/deceleration state of the engine, and an air-fuel ratio of the air-fuel mixture based on the detected value of the oxygen sensor during steady operation of the engine. air-fuel ratio feedback correction means for feedback correcting the basic fuel supply amount so as to maintain the basic fuel supply amount at a constant target value; a correction amount storage means that can be freely rewritten and stored for each region divided into a plurality of areas, and a correction amount storage means that stores the correction amount so as to bring the air-fuel ratio closer to the required air-fuel ratio based on the detected value from the oxygen sensor when acceleration/deceleration operation is detected. a correction amount correction means that corrects and rewrites the correction amount stored in an area corresponding to the operating state of the means; and a correction amount correction means that corrects the basic fuel supply amount based on the correction amount retrieved from the correction amount storage means when acceleration/deceleration operation is detected. The configuration includes an acceleration/deceleration correction means for correcting the acceleration/deceleration, and a fuel supply means for supplying the amount of fuel corrected by the air-fuel ratio feedback correction means or the acceleration/deceleration correction means.

During steady operation, the basic fuel supply amount set by the basic fuel supply amount setting means according to the engine operating state is adjusted to a constant air-fuel ratio based on the detected value from the wide-range oxygen sensor by the air-fuel ratio feedback correction means. The corrected amount of fuel is corrected so as to approach the target value, and the corrected amount of fuel is supplied by the fuel supply means, and good air-fuel ratio feedback control is performed based on highly accurate air-fuel ratio detection.

On the other hand, during acceleration/deceleration operation detected by the acceleration/deceleration detection means, the correction amount correction means corrects the correction amount in the correction amount storage means corresponding to the operating state based on the output value from the wide area oxygen sensor. At the same time, the acceleration/deceleration correction means corrects the basic fuel supply amount by the corrected correction amount, and this corrected amount of fuel is supplied by the fuel supply means.

As a result, during acceleration and deceleration, the correction amount is corrected to correct the fluctuations in the air-fuel ratio detected by the wide-range oxygen sensor, thereby achieving good acceleration and deceleration performance that satisfies the required air-fuel ratio. .

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows the configuration of a fuel supply control device (electronically controlled fuel injection device) according to the present invention.

In the figure, an internal combustion engine 1 includes an air cleaner 2°, an intake duct 3. Throttle chamber 4 and intake manifold 5
Air is inhaled through.

The intake duct 3 is provided with a hot wire flowmeter 6 that detects the intake air flow rate Q, and outputs a voltage signal Us corresponding to the intake air flow rate Q. 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 iQ. A throttle opening sensor 8 is attached to the throttle valve 7 to detect its opening θ. The intake manifold 5 is provided with an electromagnetic fuel injection valve 9 for each cylinder, which is driven to open by an injection pulse signal from a control unit 11 containing a microcomputer (described later), and is pressurized from a fuel pump (not shown). The pressure is controlled to a predetermined pressure by a pressure regulator, and the fuel is injected into the intake manifold 5.

Furthermore, the cooling water temperature T in the cooling jacket 13 of the engine.

A water temperature sensor 12 is provided to detect the oxygen concentration in the exhaust gas in the exhaust passage 13, and a wide area oxygen sensor 14 is provided which can detect the oxygen concentration in the exhaust gas in the exhaust passage 13 over a wide area.

The control unit 11 detects the engine rotation speed N by counting the crank unit angle signal output from the crank angle sensor 10 in synchronization with the engine rotation for a certain period of time or by measuring the period of the crank reference angle signal.

The control unit 11 controls the intake air flow ff1Q and throttle valve opening degree θ detected as described above.

The fuel injection amount Ti is calculated based on the engine rotational speed N2, the engine cooling water temperature T8, and the exhaust oxygen degree S, and the fuel injection valve 9 is driven and controlled based on the set fuel injection iTi. That is, in this embodiment, the control unit 11 also serves as a basic fuel supply amount setting means, an air-fuel ratio feedback correction means, a correction amount storage means, a correction amount correction means, and an acceleration/deceleration correction means. The opening sensor 8 constitutes acceleration/deceleration detection means, and together with the fuel injection valve 9 constitutes a fuel supply means.

The calculation control of the fuel injection amount Ti will be explained based on the flowchart of FIG. 3.
(The same applies hereafter) In 1, the intake air flow rate Q1, engine rotational speed N, throttle valve opening θ, cooling water temperature T1, and exhaust oxygen concentration S detected by each sensor are input.

In step 2, the difference between the opening degree θ of the throttle valve 7 and the previous time, that is, the rate of change Δθ is calculated.

In step 3, it is determined whether the engine is in an acceleration state. Specifically, when the rate of change Δθ calculated in step 2 is a value greater than a predetermined value for the throttle valve to open, it is assumed that the engine is in an accelerating state, and the process proceeds to step 4, where flag n for acceleration/deceleration determination is set. Set to O as a value indicating acceleration.

If the determination in step 3 is No, the process proceeds to step 5, and if the rate of change Δθ is a predetermined value or more on the closing side, the process proceeds to step 6, where the flag n is set to l as a value indicating deceleration.

If the rate of change Δθ is less than the predetermined value, it is determined that the operation is steady, and the process proceeds to step 7 without performing acceleration/deceleration correction to bring the air-fuel ratio closer to the target value based on the detected value from the wide-range oxygen sensor 14. After increasing/decreasing the feedback correction coefficient α and clamping correction values Ka and Kb for acceleration, which will be described later, to 0, the process proceeds to step 25.

During acceleration/deceleration, the process proceeds from step 4 or 6 to step 8, and in step 8, the current output value S of the oxygen sensor 14,
The difference ΔS between the output value 81-3 and the previous output value 81-3 is calculated.

In step 9, ΔS is positive (rich), negative (lean) or 0
Determine whether

If ΔS is determined to be 0 in step 9, step 24
However, when it is determined that ΔS is negative (lean), the process advances to step IO, and it is determined whether the flag n is 0 or not.

If n=0, proceed to step 11 and set the water temperature T.

It is determined whether or not after the completion of the 111th aircraft in which T exceeds the set value T-0. If NO, that is, before the warm-up is completed, the process advances to step 12 and the water temperature T retrieved from the memory. A correction is made to increase the value of the acceleration increase correction coefficient KF by a predetermined proportion ΔKvit1.

Here, the acceleration increase correction coefficient is set to a large value because the water temperature T, 4 is low and is difficult to become juvenile.

If it is determined in step 11 that warm-up has been completed, the process proceeds to step 13, where it is determined whether the engine speed is a specific rotation speed, for example 1200 rpm, and if YES, the process proceeds to step 14. Then, the acceleration increase correction coefficient for the rate of change Δθ of the throttle valve opening θ retrieved from the memory is corrected by increasing 1 to a predetermined percentage Δ.

Here, the acceleration increase correction coefficient is set to a large value because the response delay increases as Δθ increases.

The reason why the correction is performed only at a specific rotational speed is because the characteristics of Kl are determined with the rotational speed constant.

If the determination in step 13 is NO, step 15
Proceed to and check that the rate of change Δθ of the throttle valve opening is above a certain level (for example, slow acceleration where the time from fully closed to fully open is 0.5 seconds or more)
After determining that , the acceleration increase correction coefficient for the rotation speed N is corrected by increasing it by 3 at a predetermined rate Δ using the throttle 16. Here, the acceleration/deceleration correction coefficient is calculated as the rotation speed increases. This is set large because errors due to delays increase.

When the vehicle is lean during acceleration in this way, correction learning is performed to increase each acceleration increase correction coefficient and shift to a rich state.

Also, in the determination at step 9, ΔS is determined to be positive, that is, the air-fuel ratio is determined to be rich, and the process proceeds to step 17 where n=0.
If the determination is YES, that is, the acceleration is in progress, the same determination as in step 11.13.15 is made in step 1B, 20.22, but it is determined that the warm-up is not yet completed. If so, in step 19, the acceleration increase correction coefficient for the water temperature is decreased by a predetermined proportion ΔKrff1, and when the rotation speed is 1200 rpm, the acceleration increase correction coefficient for the change rate is decreased by a predetermined proportion ΔKl, and then At other rotational speeds, the acceleration increase correction coefficient for the rotational speed N is corrected by decreasing it by 3 at a predetermined rate Δ under the condition that Δθ=a certain value or higher.

When the engine is rich during acceleration in this way, correction learning is performed to reduce each acceleration increase correction coefficient and shift to lean.

On the other hand, during deceleration, n==1, so when it is determined to be rich in step 9, the process proceeds from step 17 to step 11 and thereafter, and KF is performed under each condition.

Correctly learn Kl, Kz, Kz to the increasing side, and conversely, if it is determined to be lean in step 9, proceed from step 10 to step l and the same < KF, Kl, K3
Learn to modify to the decreasing side.

In this way, step 12.14゜1 during acceleration/deceleration
6, 19.21.23, the process proceeds to step 24 where the final acceleration/deceleration correction value Ka (depends on the intake air flow rate) and correction value Kb (depends on the fuel density) is calculated using the following formula.

Ka= (-1)'1 (Kl +:l) ・K
tKb= (-1)' -KF However, K! is determined by, for example, the following equation as a value substantially inversely proportional to the current basic fuel injection ff1Tp (previous value determined in step 25, which will be described later).

Kt = (MAXTp-current Tp)/(MAXTp-
MINTp) Here, MAXTp is the basic fuel injection 1iTp when the throttle valve is fully opened, and MINTp is the minimum basic fuel injection ff1Tp during deceleration. Furthermore, K2 is also ΔS
Although correction may be performed based on the above, since the amount of correction is sufficiently small, learning is not performed in this embodiment, and the calculation is simplified.

In step 25, the latest basic fuel injection amount is calculated using the following equation.

~ Next, in step 26, the final fuel injection amount Ti is calculated using the following equation.

T i =Tp −C0EF・α+TS Here, C0E
F is the total value of various correction coefficients, and is composed of the water temperature coefficient Ktw l starting correction coefficient K A M + air-fuel ratio correction coefficient KMII and the acceleration/deceleration correction coefficient Kb (COEF=
1+Kt□+Kas+□+Kb).

The changes in the air-fuel ratio during acceleration and deceleration when such control is performed will be explained based on FIG.
First, the air-fuel ratio becomes over-lean, and then air flows into the intake pipe with large negative pressure downstream of the throttle valve, causing the detected value of the intake air flow rate to become excessive, resulting in over-rich, as shown by the dotted line in the figure. become. Fuel increase correction is performed to correct this, but the air-fuel ratio still fluctuates due to buzzing and differences in acceleration/deceleration conditions, and if the fuel increase is too large, overrich may occur early. There is also.

The detected value of the wide-range oxygen sensor 14 has a response delay as shown by the solid line with respect to the actual air-fuel ratio shown by the dotted line.

Therefore, when the learning control according to the above embodiment is performed, when lean is made at the beginning of acceleration, each acceleration increase correction coefficient KF, +, 2 is increased by 2 in step 12.14.15, and the fuel increase correction amount is further increased. This has been modified to make
The air-fuel ratio is corrected in the rich direction, and then when the detected value of the air-fuel ratio shifts to the rich direction, steps 1B and 2 are performed.
0.21 for each coefficient.

Ka is reduced and the fuel increase correction amount is corrected to be reduced, thereby suppressing over-richness due to overshoot.

In other words, even if the fluctuation characteristics of the air-fuel ratio before learning are different, the detected value of the air-fuel ratio is always corrected in the direction of stabilization. As shown, stable air-fuel ratio characteristics are obtained from the initial stage of acceleration, improving acceleration performance and improving exhaust emission characteristics.

In particular, if the fuel properties differ, the air-fuel ratio characteristics will differ, but even in this case, the air-fuel ratio characteristics can be improved by performing learning.

In the case of deceleration, contrary to the case of acceleration, over-richness occurs initially due to a delay in the detection of the intake air flow rate, and then over-leaning occurs as residual air on the downstream side of the throttle valve is replenished in response to a decrease in the amount of fuel injection. become Therefore, the actual air-fuel ratio changes as shown by the dotted line in the figure, and the detected value by the wide-range oxygen sensor 14 changes as shown by the solid line due to the response delay.

On the other hand, during deceleration, Ka and Kb become negative values and KF
, ni+, Ks each act as a deceleration region correction coefficient,
If there is a rich tendency during deceleration, step 12, 14.15
By increasing each correction coefficient in , the weight loss correction amount increases, thereby correcting the lean tendency, and conversely, when the lean tendency occurs, the various correction coefficients decrease in step 18.20゜21 and the weight loss correction amount decreases. Therefore, it is corrected in the rich direction. Therefore, even during deceleration, the air-fuel ratio can be stabilized as shown by the chain line in the figure, and deceleration performance and exhaust emission characteristics can be improved.

Note that the maps for the correction coefficients Ky, ni+, and 3 may be set separately for acceleration and deceleration to improve accuracy.

The above embodiment was applied to a system in which each cylinder was equipped with a fuel injection valve, but the so-called single point injection (SPI) system, which has one fuel injection valve upstream of the intake passage, such as upstream of the throttle valve, was applied later. It can also be applied to

In this type, the intake passage on the downstream side of the injection is long, and the delay time for the fuel that adheres to the intake passage wall and flows (wall flow fuel) to reach the combustion chamber is large, so the correction is mainly for the air-fuel ratio change associated with this. becomes.

Specifically, during acceleration, the wall flow fuel amount increases due to the lower temperature and the lower evaporation property, and the faster the acceleration, the greater the increase, so as shown in Fig. 5, the wall flow fuel amount increases. Even though an increase correction is being performed, if the fuel is still lean, the correction coefficient KAl:C is slightly increased, and if the fuel is rich, the correction coefficient is slightly decreased.

On the other hand, during deceleration, the residual wall flow fuel downstream of the throttle valve continues to flow in response to a decrease in the intake air flow rate, resulting in an overrich tendency.

Before warm-up is completed, the wall flow fuel amount is mainly affected by temperature, so the reduction correction coefficient K DC? shown in FIG. - is set, but if the correction coefficient Koctw is still to be enriched, the correction coefficient Koctw is modified to increase, and conversely, if the correction coefficient Koctw is to be enriched, learning is performed to decrease the correction coefficient Koctw.

After warming up, the larger the throttle valve opening just before deceleration, the
Furthermore, as the engine speed increases, the wall flow fuel amount downstream of the throttle valve increases, so the reduction correction coefficient KDCθ is as shown in FIGS. 6 and 7.

K flcN is set.

Therefore, if a rich tendency occurs during deceleration after warm-up is completed, increase Kc,4 a little under the condition of constant rotation speed (for example, 120 rpm), and set the throttle valve to a predetermined opening (for example, 4/4) just before deceleration. ), the correction is made to slightly increase KDeθ.

Then, the final fuel injection iTi is determined by the following equation.

7i=ni-Q/N'α・(COEF +KACC-KI
, c) 10TsKDC=KDCθ・K, 3. H Even with this, stable air-fuel ratio characteristics can be obtained during deceleration, and acceleration/deceleration performance and exhaust emission performance can be improved.

Incidentally, acceleration/deceleration and rich/lean determination may be performed in the same manner as in the embodiment described above.

<Effects of the Invention> As explained above, according to the present invention, good air-fuel ratio feedback control can be performed using a wide-area oxygen sensor, and the amount of fuel supplied during acceleration/deceleration can be detected by the wide-area sensor. By performing learning control based on the value, stable air-fuel ratio characteristics can be obtained, acceleration/deceleration performance is improved, and exhaust emission characteristics are also improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a 1m function of the configuration of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a flowchart showing a calculation routine for the fuel injection amount, and Fig. 4 is a flowchart showing the calculation routine of the fuel injection amount.
Diagram for explaining changes in air-fuel ratio during deceleration, Figure 5~
FIG. 8 is a diagram showing the characteristics of various correction coefficients in another embodiment. 1... Engine 6... Air flow meter 8...
・Throttle opening sensor 9...Fuel injection valve 1
0... Crank angle sensor 11... Control unit Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 1

Claims (1)

[Claims] A basic fuel supply amount setting means that sets the basic fuel supply amount based on the engine operating state, a wide range oxygen sensor that detects the oxygen concentration in the exhaust gas of the engine over a wide range, and an acceleration sensor that detects the acceleration/deceleration state of the engine. - deceleration detection means, and air-fuel ratio feedback correction means for feedback-correcting the basic fuel supply amount so as to maintain the air-fuel ratio of the mixture at a constant target value based on the detected value of the oxygen sensor during steady operation of the engine; a correction amount storage means for freely rewriting and storing the correction amount of the basic fuel supply amount for each region divided into a plurality of regions depending on the operating state, based on the operating state during acceleration/deceleration operation of the engine; correction amount correction means for correcting and rewriting the correction amount stored in the area corresponding to the operating state of the correction amount storage means so as to bring the air-fuel ratio closer to the required air-fuel ratio based on the detected value from the oxygen sensor; Acceleration/deceleration correction means corrects the basic fuel supply amount based on the correction amount retrieved from the correction amount storage means when acceleration/deceleration operation is detected, and the amount corrected by the air-fuel ratio feedback correction means or the acceleration/deceleration correction means. A fuel supply control device for an internal combustion engine, comprising a fuel supply means for supplying fuel.