JPH03175124A - Fuel supply device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent lowering of the rotating speed of an engine and the stall of the engine at start so as to enhance the starting performance of the engine by stopping correction of the amount of fuel flowing on the wall surface of the engine until a predetermined period of time elapses from the start of cranking. CONSTITUTION:A controller 1 computers the amount of intake air according to the flow passage cross section of an air intake passage and an engine rotating speed output from a rotating speed sensor 2, and then retrieves the amount of fuel attached to the wall surface of the engine according to the amount of intake air and computes the difference in the amount of fuel between the routine of this time and the previous routine. The difference in the amount of fuel is multiplied by a constant and a transient coefficient of correction is computed as a corrected amount of fuel flowing on the wall surface. The difference in the amount of fuel is set to zero until a predetermined period of time elapses after a starter switch 5 is turned on, so as to stop correction of the amount of fuel flowing on the wall surface. The most suitable amount of fuel supplied at the start of the engine is thus secured to prevent lowering of the rotating speed of the engine and the stall of the engine to enhance the starting performance of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply device for an internal combustion engine, and particularly to a technique for improving startability.

<Prior Art> Conventional examples of fuel supply devices for internal combustion engines include the following.

That is, data on the intake air flow rate Q or the basic fuel injection amount T corresponding to each operating range is prepared in advance for each of a plurality of operating ranges using the throttle valve opening degree and the engine rotational speed as parameters.
It is configured to be stored in the OM (or RAM) and retrieve data in the corresponding operating range from the ROM based on the detected values of the throttle valve opening and the engine rotational speed.

When searching for the intake air flow IQ, the basic injection amount TP (= to -Q/N;
After calculating the fuel injection amount T5 = T p
X COE F Xα+T is calculated.

Then, an injection pulse signal corresponding to the calculated fuel injection ITt is output to the fuel injection valve to inject and supply fuel to the engine.

In addition, when storing the basic injection amount TP in the ROM,
The basic injection amount T, which is retrieved based on the throttle valve opening degree and the engine rotational speed, is substituted into the calculation formula for the fuel injection amount T, to calculate the fuel injection amount T.

Here, in order to maintain the optimal air-fuel ratio during transient operation,
The amount of fuel flowing in liquid form along the inner wall of the intake passage (hereinafter referred to as wall flow fuel) is corrected as follows.

That is, after calculating the intake air flow rate Q (A/N') based on the flow passage cross-sectional area A of the intake passage obtained from the throttle valve opening and the engine rotation speed N, the wall surface adhesion IMFH is calculated from the map using this Q. Based on this wall surface adhesion amount MFH and the wall surface adhesion 31MF determined in the previous routine, a transient correction coefficient KATHO3 is calculated using the following equation.

KATHO3= (MFH-MF)xKMF; KM
F is a constant.

The calculated transient correction coefficient KAT HOS is added to the various correction coefficients C0EF, thereby correcting the wall flow of the fuel injection amount T.

Here, the wall flow correction is started from the time the starter switch is turned from on to off.

<Problems to be Solved by the Invention> However, in such a conventional fuel supply device, wall flow correction is performed from the time when the starter switch is switched from on to off, and the wall surface adhesion amount M at the time of wall flow correction is
Since FH is determined based on the throttle valve opening, if the engine key switch is operated quickly at startup, the following problems will occur.

That is, during normal cranking, the starter switch is turned on for about 0.8 to 1 second, as shown in Fig. 4, and during this time the engine rotational speed increases to a predetermined rotational speed and no trouble occurs.

On the other hand, if the starter switch is operated quickly as shown in the solid green stone in FIG. 4, the transient correction is started before the engine rotational speed increases. Therefore, during transient correction, the engine rotational speed increases rapidly regardless of the throttle valve opening being constant, so that the intake air flow rate determined from the throttle valve opening and the engine rotational speed is different from the throttle valve opening. Even though the degree is constant, it decreases as the engine rotation speed increases. Therefore, along with this, the wall surface adhesion amount M F H and the transient correction coefficient KAT HOS decrease as shown in the solid green stone in Figure 4, and the amount of fuel supplied to the engine decreases, resulting in a decrease in rotational speed ( This has the disadvantage of causing engine stall (Fig. 4, solid green stone) or engine stall (Fig. 4, solid green stone).

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide a fuel supply device for an internal combustion engine that can improve startability by preventing a decrease in rotational speed and occurrence of engine stall at the time of starting. do.

<Means for Solving the Problem> Therefore, as shown in FIG. 1, the present invention provides a fuel supply amount setting means A that sets the fuel supply amount based on the engine operating state.
, a correction amount setting means B for setting a wall flow fuel correction amount based on the engine operating state, and a wall flow correction means C for correcting the set fuel supply amount based on the set wall flow fuel correction amount. , a drive control means E for driving and controlling the fuel supply means based on the corrected fuel supply amount, and a cranking time detection means F for detecting the cranking time, and a cranking time detection means F for detecting the cranking time, and a cranking time detection means F for detecting the cranking time, and a cranking time detection means F for detecting the cranking time. determination means G for determining whether a predetermined time has elapsed since the end;
The apparatus is provided with operation means H that stops the operation of the wall flow correction means C within a predetermined time from the start of cranking, and operates the wall flow correction means C after the elapse of the predetermined time.

<Operation> In this way, by stopping the wall flow correction within a predetermined period of time after the start of cranking, the fuel injection amount at the time of starting is maintained at an optimum level, thereby improving startability.

<Example> An example of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, a control device consisting of a microcomputer etc. receives an engine rotational speed detection signal from a rotational speed sensor 2, a throttle valve opening detection signal from a throttle sensor 3, and a cooling water temperature detection signal from a water temperature sensor 4. and an on/off signal from a starter switch 5 serving as cranking detection means.

The control device operates according to the flowchart shown in FIG. 3, and outputs an injection pulse signal to the fuel injection valve 7 as a fuel supply means via the drive circuit 6.

The fuel injection valve 7 is of the so-called 5PI (single point injection) type, which is installed in the intake passage upstream of the throttle valve.

Here, the control device 1 constitutes a fuel supply amount setting means, a correction amount setting means, a wall flow correction means, a determining means, and an operating means. Further, the control device 1 and the drive circuit 6 constitute a drive control means.

Next, the operation will be explained according to the flowchart shown in FIG.

SL reads various signals from the rotational speed sensor 2 and the like.

In S2, basic injection ITp is searched from the map based on the detected engine speed and throttle valve opening.

In S3, it is determined whether the current driving state is accelerated driving, for example, based on the rate of change of the throttle valve opening. If YES, the process proceeds to S5, and if NO, the process proceeds to S4.

In S4, it is determined whether a predetermined time (for example, 1 to 2 seconds) has elapsed since the starter switch 5 was turned on (when cranking started), and if YES, the process advances to S5 and N.
If o, the process advances to S6.

The predetermined time may be changed depending on the cooling water temperature.

In S5, a fuel flow rate difference VMF is calculated. That is, the intake air flow rate (=A/
After calculating N), the wall surface adhesion amount MFH is searched based on this intake air flow rate. Then, the wall adhesion amount MF set in the previous routine is deleted from the retrieved wall adhesion amount MFH, and the fuel flow rate difference VMF (=MFH - MF) is calculated.

In S6, the fuel flow rate difference VMF set in the previous routine
It is determined whether or not exceeds zero. If YES, the process proceeds to S5, and if NO, the process proceeds to S7.

In S7, the fuel flow rate difference VMF is adjusted to stop the wall flow correction.
Set to zero.

In S8, the fuel flow rate difference VMF set in S5 or S7 is multiplied by a constant KMF to calculate a transient correction coefficient KATHO3 as a wall flow fuel correction amount.

In S9, various correction coefficients C0EF are calculated using the following equations.

C0EF= 1 +KATHO3+KTW+...+K
AS KTW is a water temperature correction coefficient, and KAS is a starting and post-start increase correction coefficient.

At 310, the fuel injection amount T is calculated using the following equation.

T,=T,XC0EFXαxTs α is the air-fuel ratio feedback correction coefficient, and Ts is the voltage correction amount based on the battery voltage.

An injection pulse signal corresponding to the fuel injection amount T calculated in this way is output to the fuel injection valve 7 via the drive circuit 6, and fuel is supplied to the engine.

As explained above, since the fuel flow difference VMF is set to zero and the wall flow correction is stopped within a predetermined time from when the starter switch 5 is turned on and when the fuel flow difference VMF is less than zero, the wall flow correction can be stopped. Since the necessary fuel injection amount can be secured at the same time, it is possible to prevent a decrease in rotational speed and the occurrence of engine stall, and improve startability. Moreover, since wall flow correction is performed even within a predetermined time during acceleration operation, acceleration performance can be maintained optimally.

<Effects of the Invention> As explained above, in the present invention, wall flow correction is stopped within a predetermined time from the start of cranking, so that an optimal fuel supply amount can be ensured at the time of startup, and a decrease in rotational speed can be prevented. , it is possible to prevent the occurrence of engine stall and improve startability.

[Brief explanation of drawings]

Fig. 1 is a claim correspondence diagram of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of the same as above,
FIG. 4 is a diagram for explaining the conventional drawbacks.

Claims (1)

[Claims] a fuel supply amount setting means for setting the fuel supply amount based on the engine operating state; a correction amount setting means for setting the wall flow fuel correction amount based on the engine operating state; In the fuel supply device for an internal combustion engine, the fuel supply device for an internal combustion engine includes a wall flow correction means for correcting the set fuel supply amount, and a drive control means for driving and controlling the fuel supply means based on the corrected fuel supply amount. a cranking time detection means for detecting the cranking time; a determination means for determining whether a predetermined time has elapsed from the start of cranking or the end of cranking; and an operation of the wall flow correction means within a predetermined time from the start of cranking. a fuel supply device for an internal combustion engine, comprising: operating means for stopping the wall flow correction means and operating the wall flow correction means after the predetermined time has elapsed.