JPH0441945A - Fuel control device of engine - Google Patents

Abstract

PURPOSE:To suppress abrupt change of a fuel injection amount during shifting from acceleration to deceleration and vise versa by parallelly carrying out a plurality of annealing computations with different annealing degrees to an output of an air flow meter according to an operation condition, and controlling fuel while adopting the largest amendment values among the obtained values. CONSTITUTION:A fuel valve 17, which is located on a downstream side of a surge tank 16 formed on the downstream side of a throttle valve 11 and in the vicinity of an intake port 6, is controlled by a control unit 19. A rotation signal from a rotation sensor 20, an intake air amount signal from an air flow meter 12, etc., are inputted to the control unit 19 as information for computation of a control signal. In case that annealing of the fuel injection valve 17 is carried out in respect to a reference fuel injection amount, a plurality of annealings having different annealing degrees are always performed to, for example, decelerate and accelerate, against the output of the air flow meter. The value largest among the obtained plural air flow meter output amendment values is judged. The fuel injection amount is set based on the largest value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine fuel control device that performs a predetermined smoothing process on the output of an air flow meter.

(Prior art) Engines that are equipped with an air flow meter in the intake passage, detect the amount of air taken into the ennon by this air flow meter, and control the fuel injection amount according to this detected value have generally been used. Are known. By the way, when detecting the intake air amount using an air flow meter as described above, for example, in situations where the intake air amount changes suddenly due to sudden acceleration or deceleration of the engine, the air flow meter may detect the actual air due to its own inertia, etc. It may be possible to detect more or less than the amount. If the fuel injection amount is set based on such a detected value, the air-fuel ratio will sometimes become over-rich or over-lean, resulting in problems such as poor drivability or increased emissions. It happens. Therefore, in order to deal with such problems, smoothing processing is performed on the basic fuel injection amount determined by the engine speed, intake air amount, and constant during transient operating conditions such as during acceleration and deceleration. A fuel control device for an engine that corrects the basic fuel injection amount according to the value thus obtained has been proposed, for example, in Japanese Patent Laid-Open No. 58-25531.

(Problems to be Solved by the Invention) By performing smoothing processing on the basic fuel injection amount as described in the above publication, it is possible to reduce disturbances in the air-fuel ratio during acceleration, deceleration, etc. This makes it possible to prevent deterioration in drivability and emissions. However, as in this conventional example, switching the smoothing process according to each operating state (acceleration state or deceleration state) requires logic for determining acceleration/deceleration, and it is also necessary to determine the degree of smoothing in each operating state. For example, when the engine transitions from a deceleration state to an acceleration state, as shown by the thick solid line in FIG. 5, the pseudo charging efficiency CE (CE- to -
QA/NE; where K is a constant and QA is the intake air! , N
i indicates the engine rotation speed. ) would suddenly change at the time of the switch, which caused a problem in that the set value of the fuel injection amount would change suddenly and a torque shock would occur. In addition, in Figure 5, the CEO
The value of CE without the smoothing process, CEDEC, and CEAcc indicate the values when the smoothing process is performed during deceleration and acceleration, respectively.

The present invention has been made in view of the above-mentioned problems, and suppresses sudden changes in the fuel injection amount when transitioning from an acceleration state to a deceleration state or from a deceleration state to an acceleration state. The object of the present invention is to obtain a fuel control device for an engine that can supply fuel according to the amount of fuel required.

(Means for Solving the Problems) The present invention performs a plurality of smoothing calculations in parallel on the output of an air flow meter with different degrees of smoothing depending on the engine operating condition, It was discovered that by performing fuel control using the maximum value among the multiple correction values, it is possible to reduce the logic for determining acceleration/deceleration and to prevent torque-and-yoke during switching. As shown in Figure 1. That is, the engine fuel control device according to the present invention includes fuel injection amount setting means for setting the injection amount of fuel injected from the fuel injection valve based on the output of an air flow meter that detects the intake air amount of the engine. In the engine fuel control device, a smoothing processing means performs a plurality of smoothing processes with different degrees of smoothing on the output of the air flow meter, and a plurality of air flow meter output correction values obtained by the smoothing processing means. The present invention is characterized by comprising maximum output correction value determining means for outputting the largest value to the fuel injection amount setting means.

(Function) Regardless of the operating state of the engine, multiple smoothing processes with different degrees of smoothing, for example for deceleration and acceleration, are always performed on the output of the airflow meter, and the resulting The largest value among the airflow meter output correction values is determined, and the fuel injection amount is set based on that value. As a result, it is possible to suppress sudden changes in the fuel injection amount when transitioning from an acceleration state to a deceleration state or from a deceleration state to an acceleration state. fuel can be supplied.

(Example) Examples will be described below based on the drawings.

FIG. 2 is an overall system diagram of embodiments of the present invention.

As shown in the figure, in this embodiment, the engine body 1 includes a combustion chamber 5 defined by a cylinder 2, a piston 3 that reciprocates within the cylinder 2, and a cylinder head 4 that covers the upper part of the cylinder 2. The cylinder head 4 is provided with an intake boat 6 and an exhaust boat 7 that open into the combustion chamber 5, and an intake valve 8 and an exhaust valve 9 for opening and closing the intake boat 6 and the exhaust boat 7. ing. A throttle valve 11 is provided in an intake passage 10 communicating with the intake boat 6, and an air flow meter 12 is provided upstream of the throttle valve 11. Also,
An air cleaner 13 is provided on the upstream side of this air flow meter 12.
is connected. Further, a bypass passage 14 is provided that connects the intake passage upstream and downstream of the throttle valve II, and an ISC valve 15 is provided in the middle of the bypass passage 14. Further, a fuel injection valve 17 is disposed near the intake boat 6, further downstream of the surge tank I6 formed downstream of the throttle valve II. Further, the exhaust boat 7 communicates with an exhaust passage 18.

The fuel injection valve 17 is operated by a control signal from the control unit 19. The control unit 19 receives a rotation signal from a rotation sensor 20 attached to the engine body l, an intake air amount signal from the air flow meter 12, and the like as information for calculating this control signal.

In this embodiment, the smoothing process for the basic fuel injection amount of the fuel injection valve 17 is performed as follows.

FIG. 3 is a characteristic diagram of Namaji processing. As shown in the figure,
The vertical axis shows the pseudo charging efficiency CE defined by the intake air amount Q^ and the engine speed NE (CE=to-QA/NE
; However, if K is a constant) and time (t) is plotted on the horizontal axis, the above CE value will be calculated based on the air flow during deceleration or acceleration if the output of the air flow meter 12 is not smoothed. Since the meter 12 undershoots or overshoots due to inertia, the raw value of CE C
EO deviates significantly from actual intake air IQA.

On the other hand, the value CEDEc, which has been subjected to a relatively large degree of smoothing for deceleration, is shown by a dotted line in the figure, while the value CEDEc, which has been subjected to a relatively large degree of smoothing for acceleration, is shown by a dotted line. The value CEACC obtained is shown by the chain line in the figure. In this embodiment, both the deceleration smoothing value CEDEC and the acceleration smoothing value CEACC are always calculated regardless of the engine operating state, and the values are calculated in advance to control the fuel injection amount. The CE value is the larger of these values (indicated by a thick solid line in FIG. 3).

) is used.

By always using the maximum smoothing correction value as the CE value in this way, it is possible to suppress sudden changes in the fuel injection amount when transitioning from a deceleration state to an acceleration state. Note that during acceleration, there is a desire to increase output by increasing the amount of fuel, while during deceleration, the air flow meter I2 undershoots too much and the inconvenience of reducing the fuel injection amount is avoided. Since there is a demand for smoothing, processing with varying degrees of smoothing is performed as described above, which makes it possible to meet these demands and to supply the appropriate fuel according to each driving state of acceleration or deceleration. becomes possible. In addition, by performing the above-mentioned smoothing process, it becomes possible to reduce the logic for determining acceleration/deceleration, which was conventionally required in the smoothing process when transitioning from a deceleration state to an acceleration state. .

FIG. 4 is a flowchart for executing the above control.

When started, first, various signals such as the engine rotational speed (NE) and intake air 1 (QA) are read in, and from these values, a value CEO is calculated representing the pseudo charging efficiency. This value CEO is determined by the arithmetic expression -QA/NE (K; constant).

Next, the CEO is smoothed according to acceleration and deceleration, respectively. Among these, the value CEACC[+] obtained by the annealing process that matches the acceleration is the value CEACC[+I] from the previous annealing process and the annealing coefficient K.
Acc and the value CEO obtained in the previous step
It is obtained by adding the product of and (1-KACc). Here, the smoothing coefficient K ACC is a coefficient that takes a value of 1 or less and indicates the degree to which the moe equivalency value is reflected in the current value, and the larger this coefficient is, the greater the degree to which the previous value is reflected. are doing.

On the other hand, the value CEDEC[f
] is also calculated in the same way as in the case of acceleration above. However, in this case, the acceleration coefficient KACC is the deceleration coefficient K oI! It is set smaller than c.

In other words, the acceleration smoothing process reflects the previous value to a smaller degree than the deceleration smoothing process, and therefore,
“During acceleration, processing is performed to obtain a value closer to the CEO obtained from the actual output value of the airflow meter.

Next, the smoothed value CEACC for acceleration and the smoothed value CE for deceleration calculated in the previous step, respectively.
Compare the magnitude of DEC, and if the acceleration value CEACC is larger, set the CE value used for setting the basic fuel injection amount to the acceleration value CEACC, and conversely, set the acceleration value CEACC to the deceleration value CEDEC. If the value is larger, set the CE value to the deceleration value CE
Set to DEC.

Next, it reads signals related to engine operating conditions such as water temperature and intake temperature, and corrects the water temperature accordingly.

Calculate correction It (C) such as intake temperature correction.

Then, a final pulse (T) is calculated by multiplying the pulse of the basic fuel injection amount based on the CE value by the correction amount (C), and the result is output to the injector (fuel injection valve).

In addition, in the above-mentioned embodiment, the case of transitioning from the deceleration state to the acceleration state has been described, but the same control can be performed also in the case of transitioning from the acceleration state to the deceleration state.

(Effects of the Invention) Since the present invention is configured as described above, each acceleration or deceleration operation can be performed while suppressing sudden changes in the fuel injection amount when transitioning from an acceleration state to a deceleration state or from a deceleration state to an acceleration state. Fuel can be supplied depending on the situation.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is an overall system diagram of an embodiment of the present invention, Fig. 3 is a characteristic diagram of smoothing processing in the embodiment, and Fig. 4 is a control diagram of the embodiment. FIG. 5 is a flowchart for executing the process, and is a characteristic diagram of the conventional smoothing process. l: Engine body, ■2: Air flow meter, 17 Fuel injection valve, 19: Control unit.

Claims (1)

[Claims] (1) In a fuel control device for an engine, the air flow meter includes a fuel injection amount setting means for setting an injection amount of fuel injected from a fuel injection valve based on an output of an air flow meter that detects an intake air amount of the engine. smoothing processing means for performing a plurality of smoothing processes with different degrees of smoothing on the output of the output; and a fuel injection amount setting means that sets the largest value among the plurality of airflow meter output correction values obtained by the smoothing processing means. 1. A fuel control device for an engine, comprising a maximum output correction value determining means that outputs a maximum output correction value.