JPH0833123B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine,
In particular, it relates to a technique for increasing the fuel injection amount after starting.

<Prior Art> Conventionally, in an electronically controlled fuel injection device for an internal combustion engine, a basic fuel injection amount consisting of an intake air flow rate and an engine speed is set, and a correction according to the operating state of the engine is added to Then, the fuel injection amount to be injected by the fuel injection valve is set.

Here, as one of the corrections, there is a post-start increase correction, which is performed for a certain period of time after the engine is started (after the start switch ST / SW is switched from ON to OFF), as shown in FIG. Initial value set to increase as engine temperature (engine cooling water temperature Tw) decreases, as shown in the map in FIG.
From the MK _AS , the post-start increase correction coefficient K _AS is set by gradually decreasing with the gradual decrease value set according to the initial value MK _AS with the lapse of time. Is increased.

<Problems to be solved by the invention> By the way, since the above-mentioned map is set to match the standard gasoline, it is difficult to evaporate compared to the standard gasoline, and low vapor pressure gasoline (summer gasoline) When used in low winter, the amount of fuel injected from the fuel injection valve does not evaporate and the amount that adheres to the wall of the intake manifold increases, causing a delay in reaching the combustion chamber and temporarily Became lean, and there was a problem such as a drop in rotation after starting (see FIG. 7X).

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an electronically controlled fuel injection device for an internal combustion engine, which does not cause rotation loss after starting.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention, as shown in FIG. 1, changes from an initial value set according to the engine temperature for a certain time after the engine starts The post-starting increase correction coefficient setting means (a) for setting the post-start increase correction coefficient by gradually decreasing with the gradual decrease value set in accordance with In an electronically controlled fuel injection device for an internal combustion engine, comprising: a post-starting amount increase correction means (b) for increasing and correcting
(E) means are provided.

(C) Rotational drop detecting means for detecting a decrease in engine speed to a predetermined value or less during the certain period of time. (D) At the time of detecting the rotational drop, the post-startup is performed in order to increase the post-starting increase correction coefficient. Post-starting increase correction coefficient resetting means for resetting the increase correction coefficient (e) Gradual decrease value resetting means for resetting the gradual decrease value to the increasing side at the time of resetting the post-starting increase correction coefficient. <Operation> With the above configuration Then, the following effects can be obtained.

An initial value is set according to the engine temperature, a gradual decrease value is set according to the initial value, and the gradual decrease value is gradually decreased with the lapse of time from the initial value to set the post-start increase correction coefficient.

The fuel injection amount is increased and corrected based on the post-starting amount increase correction coefficient.

Then, when a decrease in the engine speed to a predetermined value or less is detected during a fixed period of time after starting (increase correction), the post-start increasing correction coefficient is reset to increase to prevent rotation drop. Along with this, the gradual decrease value is reset to the increasing side,
Even if the increase correction coefficient after starting is increased, the gradual decrease speed is increased by that amount so that the increase correction time is not changed significantly.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS.

 First, the system will be described with reference to FIG.

Air is drawn into the engine 1 from the air cleaner 2 through the intake duct 3, the throttle valve 4, and the intake manifold 5.

At the branch portion of the intake manifold 5, a fuel injection valve 6 is provided for each cylinder.

The fuel injection valve 6 is an electromagnetic fuel injection valve that is opened by energizing a solenoid, is closed by deenergizing, and is opened by being energized by a drive pulse signal from a control unit 12 described later. The fuel is pumped from the fuel pump and adjusted to a predetermined pressure by the pressure regulator.

A spark plug 7 is provided in the combustion chamber of the engine 1 to spark-ignite and ignite and burn the air-fuel mixture.

The control unit 12 includes a microcomputer including a CPU, a ROM, a RAM and an input / output interface, receives input signals from various sensors, performs arithmetic processing as described later, and operates the fuel injection valve 6. Control.

As the various sensors, a hot wire type air flow meter 13 is provided in the intake duct 3 to detect the intake air flow rate Q.

In addition, the crank angle sensor 14 is provided, and in the case of four cylinders, the reference signal and the crank angle 1 for each crank angle of 180 ° are set.
It outputs a unit signal for every 2 °. Here, the engine speed N can be calculated by measuring the period of the reference signal or the number of generated unit signals within a predetermined time.

Further, a water temperature sensor 15 is provided facing the water jacket of the engine 1 to detect the cooling water temperature Tw. From this, the engine temperature can be known.

Further, ON / OFF signals are output from the start switch 17.

Here, the CPU of the microcomputer incorporated in the control unit 12 is a program on the ROM (fuel injection amount setting routine, first post-start increase amount correction coefficient setting routine, which is shown as a flowchart in FIGS. 3 to 5).
According to the second post-starting amount increase correction coefficient setting routine), arithmetic processing is performed to control the fuel injection amount.

First, the fuel injection amount setting routine will be described with reference to the flowchart in FIG.

In step 1 (denoted as S1 in the figure. The same applies hereinafter), the intake air flow rate Q and the engine speed N are input.

In step 2, the basic fuel injection amount T _P is set according to the following equation.

T _P = K · Q / N; K is a constant In step 3, the correction coefficient COEF including the post-starting increase correction coefficient close K _AS is set according to the following equation.

COEF = 1 + K _TW ＋ K _ST ＋ K _AS ＋ …… ； K _TW is the water temperature correction coefficient, K _ST is the startup increase correction coefficient In step 4, the voltage correction amount T _s is set according to the battery voltage.

In step 5, the fuel injection amount is calculated using the correction coefficient COEF, etc.
Set Ti according to the following equation.

T _i = T _P · COEF + T _s Here, steps 3 and 5 correspond to the post-starting increase correction means.

Then, the pulse width signal corresponding to the fuel injection amount Ti is
The fuel is output to the fuel injection valve 6 at a predetermined timing synchronized with the rotation of the engine.

Next, the first post-starting amount increase correction coefficient setting routine will be described with reference to the flowchart of FIG.

Incidentally, FIG. 6 shows the switching timing of the start switch (ST / SW) 17, and the control characteristics of the post-starting increase correction coefficient K _AS and the engine speed N.

In step 11, ON / OFF of the start switch 17 is determined.

When ON (during start-up), the routine proceeds to step 12, where 0 is assigned to the post-starting increase correction coefficient K _AS , and further the routine proceeds to step 13, where the resetting flag F is reset and this routine ends. To do.

On the other hand, in the determination in step 11, the start switch 17 is OF
If F (after starting), proceed to step 14 to turn from ON to OFF.
It is determined whether or not it has just been switched to.

Immediately (YES), the process proceeds to step 15 to search for the initial value MK _AS of the post-start increase correction coefficient K _AS based on the cooling water temperature Tw detected by the water temperature sensor 15 with reference to the map.

In step 16, the gradual decrease value DK of the increase correction coefficient after starting
Set _AS according to the following formula.

DK _AS = MK _AS / Cmax; Cmax is a constant increase amount after start. In step 17, the increase amount after start correction coefficient K _AS is set to the initial value MK.
Substitute _AS .

As a result, the post-start amount increase correction is started, and the post-start amount increase correction coefficient K _AS is gradually decreased with the passage of time according to the flowchart of FIG. 5 described later.

On the other hand, the start switch 17 is turned on by the judgment in step 14.
If it is not immediately after switching from to OFF (NO), the routine proceeds to step 18, where it is judged whether or not the reset flag F is set.

If not standing, the routine proceeds to step 19, where it is determined whether the engine speed N is less than or equal to a predetermined value A and the engine speed change amount ΔN is negative (<0) (during falling).

Note that this determination condition is for detecting the engine speed drop, but a range of the cooling water temperature at which engine speed drop is likely to occur depending on the gasoline property and engine condition may be added as the determination condition.

When YES, that is, when N ≦ A and ΔN <0,
Since cause rotation drop, the flow proceeds to step 20, by adding certain additional amount AK _AS to the after-start increment correction coefficient K _AS at that time, the post-start enrichment coefficient K _AS, reconfigure according to the following formula To do.

K _AS = K _AS + AK _{AS In} step 21, the gradually decreasing value DK _AS is reset according to the following equation.

DK _AS = K _AS / (Cmax-C) where C is the elapsed time after the start (counter value for timing measured in step 33 of FIG. 5 described later), and Cmax
-C indicates the remaining time of the constant post-start increase amount Cmax for performing the post-start increase amount correction.

The gradual decrease value DK _AS is reset by the increase correction coefficient K after starting.
_This is because the deceleration rate is increased so that the increase time does not change even if the _AS is reset and becomes larger.

In step 22, the reset flag F is set and the routine is finished.

On the other hand, if the reset flag F has already been set in the determination in step 18 and if the determination in step 19 is NO, the routine is terminated as it is.

Here, step 19 corresponds to the rotation decrease detecting means, step 20 corresponds to the post-starting increase correction coefficient resetting means, and step 21 corresponds to the gradually decreasing value resetting means.

Next, the second post-starting amount increase correction coefficient setting routine executed every unit time will be described with reference to the flowchart in FIG.

In step 31, start switch (ST / SW) 17 is turned on.
・ Determine OFF.

When it is ON, the routine proceeds to step 32, where the counter value C for clocking is set to 0, and this routine is finished as it is.

On the other hand, in the judgment of step 31, the start switch 17 is OF
If it is F, the routine proceeds to step 33, where 1 is added to the counter value C for clocking, and the routine proceeds to step 34.

In step 34, the counter value C for timing is compared with the post-start increase amount Cmax, and the counter value C is compared with the post-start increase amount Cm.
When it is less than ax, the routine proceeds to step 35, where the post-starting amount increase correction coefficient K _AS is set according to the following equation, and this routine is ended.

K _AS = K _AS −DK _AS Here, step 35 corresponds to the increase correction coefficient setting means after starting.

When C ≧ Cmax, this routine is finished as it is.

At this time, since the increase correction coefficient K _AS after starting is 0, the increase correction is not performed.

The reason why the increase time is made constant is that the time until it stabilizes at idle is almost constant, and that changing this time affects other controls.

<Effects of the Invention> As described above, according to the present invention, when the engine speed decreases to a predetermined value or less during a certain time after the engine is started,
The increase correction coefficient after starting is reset to increase, and the gradual decrease value is reset to the increasing side accordingly, so it is possible to effectively prevent the rotation drop after starting. To be

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram of an embodiment of the present invention, FIG. 3 is a flow chart of a fuel injection amount setting routine, and FIG. Flow chart of coefficient setting routine, FIG.
The flowchart of the correction coefficient setting routine after starting, FIG. 6 is a diagram showing the control characteristics, FIG. 7 is a diagram showing the conventional control characteristics, and FIG. 8 is the cooling water temperature and the initial value of the increasing correction coefficient after starting. It is a diagram showing a relationship. 1 ... Engine, 6 ... Fuel injection valve, 12 ... Control unit, 13 ... Air flow meter, 14 ... Crank angle sensor, 15 ... Water temperature sensor, 17 ... Start switch

Claims (1)

[Claims] 1. An increase correction coefficient after starting by gradually decreasing with time, from an initial value set according to the engine temperature for a certain time after engine startup, by a gradually decreasing value set according to the initial value. In the electronically controlled fuel injection device for an internal combustion engine, which has a post-starting amount increase correction coefficient setting means for setting and an after-start amount increase correction means for increasing and correcting the fuel injection amount by the post-start amount increase correction coefficient, , A rotation decrease detecting means for detecting a decrease in the engine speed to a predetermined value or less, and at the time of detecting the rotation decrease, reset the post-start increase correction coefficient so as to increase the post-start increase correction coefficient. An electronically controlled fuel injection device for an internal combustion engine, comprising: an increase correction coefficient resetting means; and a gradual decrease value resetting means for resetting the gradual decrease value to the increasing side when resetting the post-starting increase correction coefficient. .