JPH03189344A - Fuel supply device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve startability by stopping operation of wall flow compensation means at the time of cranking and when the variation rate of engine speed is judged to be a specified value of more, and providing an operation means which operates the wall flow compensation means at the other time. CONSTITUTION:A cranking time is detected by a cranking detection means F, engine speed is detected by an engine speed detection means G, and engine load is detected by an engine load detection means H. An engine variation rate judging means I judges that whether variation rate of the engine speed detected at the time when the detected engine load is at a specified value or less than, is at a specified value or more, or not. In an operation means G, the operation of a wall flow compensation means C is stopped when the variation rate of the engine speed at a cranking time is judged at a specified value or more, and the wall flow compensation means C is operated at the time when it is less than. Starting of rotations is judged by the variation rate of engine load and the engine speed, and the wall flow compensation means C is stopped at the judging and cranking times.

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 Tp 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 the intake air flow rate Q, the basic injection amount TP (= to -Q/Ni
K is a constant), then the fuel injection amount Ti=TrXCO
EFXα+T is calculated.

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

Moreover, when storing the basic injection amount T2 in the ROM,
The basic injection amount T2 retrieved based on the throttle valve opening degree and the engine speed is substituted into the equation for the fuel injection amount T to calculate the fuel injection @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 i1Q (A/N) based on the cross-sectional area A of the intake passage obtained from the throttle valve opening and the engine speed N, the wall adhesion iiMFH is searched from the map using this Q. And this wall surface adhesion amount MF
Based on H and the wall 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 KATHO3 is added to the various correction coefficients C0EF to correct 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 by the broken line 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 by the solid line in FIG. 4, the transient correction is started before the engine speed increases. Therefore, during transient correction, the engine speed increases rapidly even though the throttle valve opening remains constant, so the intake air flow rate determined from the throttle valve opening and the engine rotational speed increases even if the throttle valve opening remains constant. Nevertheless, it decreases as the engine speed increases. Therefore, along with this, the wall surface adhesion amount MFH and the transient correction coefficient KATHO3 decrease as shown by the solid line in FIG.
As the amount of fuel supplied to the engine decreases, the rotational speed decreases (
(shown by the dashed line in Figure 4) or cause an engine stall (shown by the dashed line in Figure 4).
There is a problem that this results in a problem (shown by the solid line in FIG. 4).

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 rotation detecting means for detecting the engine rotation speed. Speed detection means G;
An engine load detection means H that detects the engine load; and a rotation rate change determination means I that determines whether the detected rate of change in engine rotation speed is equal to or greater than a predetermined value when the detected engine load is less than or equal to a predetermined value. , operating means J that stops the operation of the wall flow correction means C during the cranking and when the rate of change is determined to be equal to or higher than a predetermined value, and operates the wall flow correction means C at other times; .

<Operation> In this way, the rotation rise at the time of starting is determined from the engine load and the rate of change of the rotational speed, and the wall flow correction is stopped at the time of this determination and during cranking.

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

In FIG. 2, a control device W1 consisting of a microcomputer, etc. includes a rotational speed sensor 2 as rotational speed detection means.
a throttle valve opening detection signal from the throttle sensor 3 as an engine load detection means, a cooling water temperature detection signal from the water temperature sensor 4, and a starter switch 5 as a cranking detection means. On/off signals are input.

The control device 1 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 rotational rate of change determination means, and an operation 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, the basic injection amount Tp is searched from the map based on the detected engine speed and throttle valve opening.

In S3, it is determined whether the starter switch 5 is on or not,
When the answer is YES, the process proceeds to 310, and when the answer is No, the process proceeds to S4.

In S4, it is determined whether or not the current driving state is accelerated driving, based on the rate of change of the throttle valve opening, for example. If YES, the process advances to S8, and if NO, the process advances to S5.

In S5, it is determined whether or not the throttle valve opening degree detected by the throttle sensor 3 is less than or equal to a predetermined value (a value close to fully closed). If YES, the process advances to S6, and if No, S
Proceed to step 8.

In S6, it is determined whether the detected rate of change in the engine rotational speed is equal to or greater than a predetermined value. If YES, it is determined that the rotation is rising during startup, and the process proceeds to S7; if NO, the process proceeds to S8. Here, the rate of change in engine rotational speed is high: approximately 50 Orpm/100 rpm during dry cooking (throttle valve fully open).
m5ec and approximately 150 to 20 Orpm/100 when the auxiliary air control valve for the air conditioner is opened at idle.
m5ec and about 30Orpm7100msec at startup
There is. Therefore, it is possible to determine when the rotation starts at startup based on the throttle valve opening degree and the rate of change in engine speed.

In S7, the fuel flow rate difference VMF set in the previous routine is
It is determined whether or not exceeds zero. If YES, the process proceeds to S8, and if NO, the process proceeds to S9.

In S8, a fuel flow rate difference VMF is calculated. That is, the intake air flow rate (=A/
After calculating N), the wall 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 S9 and SIO, the fuel difference VMF is set to zero in order to stop wall flow correction.

In Sll, 38. The fuel flow rate difference VMF set in S9 or 310 is multiplied by a constant KMF to calculate a transient correction coefficient KATHO3 as a wall flow fuel correction amount.

In S12, various correction coefficients C0EF are calculated using the following equations.

C0EF 1 +KATHO3+KTW+...10KA
S KTW is a water temperature correction coefficient, and KAS is a starting and post-start increase correction coefficient.

In S13, the fuel injection amount T is calculated using the following equation.

T! = T p X COE F X a X T
3α is an air-fuel ratio feedback correction coefficient, and Ts is a voltage correction factor based on battery voltage.

An injection pulse signal corresponding to the fuel injection amount Tt 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, wall flow correction is performed by setting the fuel flow rate difference VMF to zero when the starter switch 5 is turned on and at the time of starting when the rate of change in rotational speed is equal to or higher than a predetermined value and when the fuel flow rate difference VMF is less than or equal to zero. Since the fuel injection amount required for starting can be secured even if the starter switch 5 is operated quickly, a decrease in rotational speed and occurrence of engine stall can be prevented and starting performance can be improved. 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, the wall flow correction is stopped during cranking and when the rotation starts immediately after cranking, so that the optimum fuel supply amount can be ensured at the time of starting. Therefore, it is possible to prevent a decrease in rotational speed and the occurrence of engine stall, thereby improving 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. cranking detection means for detecting engine rotation speed; engine load detection means for detecting engine load; and engine rotation detection means for detecting engine rotation speed when the detected engine load is below a predetermined value. rotation rate of change determining means for determining whether the rate of change in speed is equal to or greater than a predetermined value; and stopping the operation of the wall flow correction means during cranking and when the rate of change is determined to be equal to or greater than a predetermined value. , operating means for operating the wall flow correction means at other times. A fuel supply device for an internal combustion engine.