JPS6368736A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an extensive variation of the air-fuel ratio, by maintaining the initial value of the fuel injection correcting amount until the first injection timing, and increasing and correcting the fuel injection amount at the transient condition depending on the correcting amount, when the transient operation is detected. CONSTITUTION:An operational condition detecting device (a) to detect the operational condition of an engine is provided. And a transient detecting device (b) to detect that the engine is transferred to a specific transient condition is provided, and the fuel injection correcting amount, which varies from the initial injection timing as the basic point, is computed by a correcting amount arithmetic device (c). And the basic fuel injection amount is computed depending on the engine operational condition at an injection amount arithmetic device (d). And, as well as the injection signal is output at an injection timing synchronous to the engine rotation, the basic fuel injection amount is corrected depending on the correcting amount at the time when transferred to the transient condition. A fuel feeding device (e) is controlled depending on the injection signal after the correction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection control device for an internal combustion engine such as an automobile, and more particularly to a fuel injection control device for an internal combustion engine that performs fuel increase correction during a transient period.

(Prior Art) Generally, the amount of fuel required by an engine in a certain operating state uses the intake air amount of the engine at that time as one important parameter.

Conventional fuel supply control devices for internal combustion engines that determine the amount of fuel required by the engine from the amount of intake air include:
For example, there is one described in "New Automotive Engineering Handbook, Volume 4" (published by the Society of Automotive Engineers of Japan on September 30, 1981). This device detects the amount of air from the rotational displacement of a measuring plate of an air flow meter installed in the intake pipe, and converts this into an electrical signal using a potentiometer. This electrical signal is input to the control unit and divided by a predetermined trigger corresponding to the engine speed. Since the divided electrical signals correspond to the steady state intake air amount for each cylinder,
Based on this, the fuel injection amount is determined so that the air-fuel ratio becomes the target air-fuel ratio.

(Problems to be Solved by the Invention) However, in such a conventional fuel injection control device for an internal combustion engine, the fuel injection amount corresponding to the target air-fuel ratio is determined from the intake air amount in a steady state. Therefore, when the throttle valve is suddenly opened, for example, when the automobile is suddenly accelerated (hereinafter referred to as transient operation), the internal pressure of the air supply pipe is rapidly increased, promoting liquefaction of the fuel. A portion of this liquid fuel becomes a wall flow and stays inside the air supply pipe, and further, as the amount of accumulated accumulation increases, a portion of it flows into the combustion chamber. As described above, during transient operation, the air-fuel ratio fluctuates significantly, making it impossible to obtain the required appropriate air-fuel ratio, resulting in a problem of deterioration of acceleration performance and other drivability.

(Objective of the Invention) Therefore, the present invention maintains the initial value of the fuel injection correction amount until the first injection timing during the transient period, thereby appropriately correcting the air-fuel ratio during the transient period and eliminating large fluctuations in the mixture ratio. The purpose is to improve drivability.

(Means for Solving the Problems) In order to achieve the above object, the fuel injection 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) and a transient detection means for detecting that the engine has entered a predetermined transient state, a correction that calculates a fuel injection correction amount that changes based on the first injection timing when the engine enters the transient state; A quantity calculating means C calculates a basic fuel injection amount based on the operating state, outputs an injection signal at an injection timing synchronized with the engine rotation, and when transitioning to a transient state, calculates the basic fuel injection amount based on the fuel injection correction amount. It includes an injection amount calculation means d that corrects the injection amount, and a fuel supply means e that supplies fuel to the engine based on an injection signal.

(Function) In the present invention, when a transient operation is detected, the initial value of the fuel injection correction amount is held until the first injection timing during the transient, and the fuel injection amount during the transient is increased based on the correction amount. Ru. Therefore, the air-fuel mixture during transient times is appropriately corrected, and large fluctuations in the air-fuel ratio are eliminated.

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

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

First, the configuration will be explained. In FIG. 2, reference numeral 1 denotes an engine; intake air is supplied to each cylinder through an intake pipe 2 from an air cleaner (not shown), and fuel is injected by an injector (fuel supply means) 3 based on an injection signal St. Then, the air-fuel mixture in the cylinder is ignited and exploded by the discharge action of the spark plug 4, becomes exhaust gas, and is introduced into a catalytic converter (not shown) through the exhaust pipe 5, where the harmful components (Co, HC, NOx) is purified by a three-way catalyst and discharged.

The intake air flow IQa is measured using a flap type air flow meter 6.
and is controlled by the throttle valve 7 in the intake pipe 2. The opening degree TVO of the throttle valve 7 is detected by the throttle valve opening sensor 8, and the intake air flow iQa and the throttle valve opening degree T
Each of the VO is input to an A/D converter 9.10, converted into an intake air amount Q and a throttle opening α having digital values, and output.

The crank angle of the engine is detected by a crank angle sensor 11, and the crank angle sensor 11 outputs a unit signal S corresponding to 2 degrees of the crank angle and a discrimination signal S2 for cylinder discrimination to the microcomputer 20.

The air flow meter 6, throttle valve opening sensor 8, and crank angle sensor 11 constitute an operating state detection means 12.

The microcomputer 20 has the functions of a transient detection means, a correction amount calculation means, and an injection amount calculation means.
U21, ROM22, RAM23 and I10 port 2
Consisting of 4. The CPU 21 imports necessary external data from the I10 port 24 according to the program stored in the ROM 22, and also imports the necessary external data from the RAM 2.
It performs arithmetic processing while exchanging data with the I10 port 24, and outputs the processed data to the I10 port 24 as necessary. That is, signals from the A/D converter 9.10 and the crank angle sensor 11 are input to the I10 boat 24, and an injection signal (injector drive pulse) Si is output from the I10 boat 24. ROM22
stores the calculation program for the CPU 21,
The RAM 23 is a so-called working memory that temporarily stores data used in calculations, calculation results, etc.

Next, the action will be explained.

FIG. 3 is a flowchart showing a fuel injection control program written in the ROM 22, and this program is executed once every predetermined period of time (for example, 10 ms). In the figure, first, P is the crank angle sensor 11.
The engine rotation speed N is calculated based on the cylinder discrimination signal S2 from , and the intake air amount Q is read at P2. Next, the basic fuel injection amount 'rp is calculated at P according to the following equation (2).

”rp=KX □ ・・・・・・■However, K:
In the constant P4, it is determined from the amount of change in the throttle valve opening TVO that a transition to a transient operation state such as acceleration (hereinafter simply referred to as transient operation) has occurred according to the following equation (2). Note that this determination may be determined based on the amount of change in the basic fuel injection ITp as shown in the following equation (0).

TVO-T, VO-1>SLI......■However, TVO,: Previous value S L l slice level TI' T p-+ > S L z...
... ■However, 'rp-,: Previous value SL, z When it is determined that the operation is transient at slice level P4, P.

Then, the fuel injection correction amount rpc is calculated according to the following equation (2).

TI' C= A X (-) n...
・・■However, A: Constant■In the formula, the index n represents the number of times step P4 is executed during the transient operation period, and the exponent n represents the number of times step P4 is executed during a predetermined period of time (for example, 10
m s ), the initial value rOJ is counted up by +1. In other words, the index n immediately after transition to transient operation
is the initial value "0", and the fuel injection correction amount Tp at this time
The value of c is the largest. Furthermore, when the transient operation continues and this program is executed again, the index n=l and the fuel injection correction amount rpc becomes 1/2. In this way, while the transient operation continues, the fuel injection correction 1 in FIG.
It changes exponentially from 1/2.1/4.1/8 of rAJ.

In Pb, it is determined whether or not fuel injection was performed between the transition to transient operation and the execution of this program.
If after fuel injection, set the injection correction amount rpc to 172 at P7.
Make it. Further, if it is determined at P6 that fuel injection has not been performed yet, step P7 is jumped to. Therefore, the value of the fuel injection correction amount Tpc in this process remains at the initial value rAJ, and this initial value “A
” continues to be held until the next process (for example, after 10 m5) is executed. As a result, fuel injection correction 1
As shown by the solid line in Figure 4 (C), Tpc has a characteristic in which the initial value rAJ is maintained until the first fuel injection timing after transition to transient operation, and the amount decreases exponentially from there. exhibits. In P8, fuel injection lTi,
Calculated according to the following formula 〇, the injection signal Si (see Fig. 4 (dl)) whose pulse width is set corresponding to P and the fuel injection amount Ti of the lever is output to the injector 3 at a predetermined crank angle timing. .

T i =Tp +Tp c . . . ■The injector 3 opens and injects fuel into the combustion chamber while this injection signal St is input.

As described above, in this embodiment, the fuel injection correction 1Tpc is changed based on the first injection timing after transition to transient operation, so that the amount of fuel injected into the combustion chamber is adjusted regardless of when the transient operation occurs. The increase is corrected appropriately, and the air-fuel ratio during transient times is stably set.

FIG. 5.6 is a diagram showing a second embodiment of the present invention, and is an example in which the present invention is applied to a group injection type fuel injection control device. FIG. 5 is a flowchart showing the program of the fuel injection control device in this embodiment. Incidentally, steps having the same contents as those in the first embodiment will be given the same step numbers as in the first embodiment, and the explanation thereof will be omitted. In the same figure, the fuel injection correction for #1 group is 4! with rPz+J!
t (hereinafter simply referred to as TpC) and the fuel injection correction amount for #2 group (hereinafter simply referred to as rpc),
Calculate according to the following formulas ■ and ■.

Tp c + =A X () ' --@Tp c
t =Ax (-)n・・・・・・■However, A: constant These rp c and T p c z have characteristics such that they decrease exponentially from the initial value rAJ as in the first embodiment. Specifically, they are shown by the dashed-dotted line and the dashed-double-dotted line in FIG. 6(C).

Next, it is checked whether or not the #1 group fuel injection was performed after the transition to transient operation at r P zzJ and before this program is executed. If fuel injection is being performed, Tpc is halved by "rPtz"; if not, Pt3 is jumped. That is, when fuel injection is not performed, the value of rp C1 is set to the initial value rAJ.
This holding is continued until the fuel injection timing of the #1 group arrives. Then r P t
aJ, r P zsJ, for #2 group, #1
The same processing as for groups is performed. Tpc and Tpc2, whose initial values rAJ are held in this way, are
The fuel injection amount of #1 group (hereinafter simply referred to as Ti) according to the following equations (■) and (■) for rPzJ and rPgJ, respectively.

) and the fuel injection amount of #2 group (hereinafter simply referred to as Tiz).

Ti+ =Tp+Tpc, ・・・・・・■T iz
=Tp +Tp cz -...-■ Then, P2B
Now, an injection signal Si having a pulse width corresponding to Ti, , and Ti2 is generated, and is output to the injector of each group at the injection timing of each group, and the current process ends.

In the next process, the sizes of Tp C and Tp C2 will be 1/2, and in the next process, they will be 1/4. In this way, even in this embodiment, TpC and Tp
The initial value rAJ of ct is maintained until a predetermined injection timing, and then decreases exponentially. Therefore, the first
Effects similar to those of the embodiment can be obtained.

Note that the present invention is not limited to what is shown in each of the above embodiments. The point is that the initial value of the fuel injection correction amount only needs to be maintained until the first injection timing of that cylinder during a transient period, and it can be applied even to systems that individually control the injection timing of multiple injectors, for example. Needless to say.

(Effects) According to the present invention, since the initial value of the fuel injection correction amount is maintained until the first injection timing during a transient period, it is possible to eliminate large fluctuations in the air-fuel ratio during a transient period, improving drivability. can be done.

[Brief explanation of the drawing]

Fig. 1 is a basic conceptual diagram of the present invention, Figs. 2 to 4 are diagrams showing a first embodiment of the invention, Fig. 2 is a schematic configuration diagram thereof, and Fig. 3 is a fuel injection control program thereof. Flowcharts, FIGS. 4A to 4D are timing charts for explaining the operation, FIGS. 5 and 6 are diagrams showing a second embodiment of the present invention, and FIG. 5 is a fuel injection control program thereof. The flowchart shown in FIG.
... Operating state detection means, 20 ... Microcomputer (transient detection means, correction amount calculation means, injection amount calculation means).

Claims (1)

[Scope of Claims] a) Operating state detection means for detecting the operating state of the engine; b) Transient detection means for detecting that the engine has entered a predetermined transient state; and c) When the engine has entered a predetermined transient state, d) a correction amount calculation means for calculating a fuel injection correction amount whose amount changes with the first injection timing as a base point; and d) a correction amount calculation means for calculating a basic fuel injection amount based on the operating condition and an injection signal at an injection timing synchronized with engine rotation. e) fuel supply means for supplying fuel to the engine based on the injection signal; and e) fuel supply means for supplying fuel to the engine based on the injection signal. A fuel injection control device for an internal combustion engine, comprising: