JPS5963327A - Method of controlling fuel injection in engine - Google Patents

Abstract

PURPOSE:To aim at improvement in engine start performance, by increasing an amount of fuel injection when engine speed just after complete explosion of an engine is less than a target engine speed, and increase velocity of the engine speed after a fixed time is elapsed is less than a target velocity. CONSTITUTION:Engine speed Ne1 just after complete explosion of an engine is measured, and it is compared with a target engine speed Nup (about 2,000rpm) after complete explosion of the engine. If the engine speed Ne1<Nup, Ne1 is detected and then engine speed Ne2 at a time of ts is countered, thereby calculating thetaN=(Ne2-Ne1)/tS. thetaN is an increasing velocity of engine speed. If thetaN< thetaNset(thetaNset is a target increasing velocity of engine speed.), an amount of fuel is increased, so as to increase engine speed. Thus, engine start performance may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine fuel injection control method, and more specifically to an engine fuel injection control method suitable for quickly bringing the engine rotation speed to a target rotation speed after an engine complete explosion. Regarding the method.

The prior art will be explained with reference to FIG. FIG. 1 shows a fuel supply method during startup and warm-up. The amount of fuel to be supplied is determined by the basic injection amount determined by engine speed, intake air amount, intake pressure, etc., intake temperature increase determined by intake air temperature, water temperature increase determined by cooling water temperature, starting amount determined by engine condition, and post-start tank. Consists of volume and idle volume. When the start switch is turned on, fuel as shown is injected until the start switch is turned off. At the same time as the engine completely explodes, the starting operation shifts to the after-start tank amount and sets the actual air-fuel ratio to the air-fuel ratio required for warm-up. The air-fuel ratio during warm-up is set to be lean due to exhaust gas and fuel economy regulations, so the engine speed Net after complete detonation is
As shown in the figure, it takes rPA time to reach the number of rotations of the eye image (around 2000 units). This time TA becomes larger as the engine temperature becomes lower.In addition to slowing down the warm-up speed of the engine, if a load is applied before the engine reaches the target rotation speed (lights, on, air conditioner, etc.).

(on, etc.) could cause the engine to stall.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection control method for an engine that reduces the time required to reach a target rotational speed after a complete explosion.

The first feature of the present invention is that if the engine rotation speed immediately after the engine complete explosion is equal to or lower than the target rotation speed, and the rate of increase in the engine rotation speed after a predetermined time elapses after the engine complete explosion is equal to or lower than the target speed, the fuel The point is that 1% of the injection amount is increased, which corresponds to the amount increased after starting.

The second feature of the present invention is that when the intake air amount immediately after the engine completely explodes is less than or equal to the target intake air amount, and the time rate of change in the intake air amount after a predetermined period of time has elapsed after the engine complete explosion is less than or equal to the target value, The second feature is that the amount of fuel in the fuel injection amount is increased by an amount corresponding to the amount increased after starting.

An embodiment of the present invention will be briefly described with reference to FIGS. 2 and 3. In FIG. 2, when the start switch is turned on, the engine enters a crack/kink state. At this time, fuel supply is controlled by fuel injection according to a starting routine similar to that of the prior art (the state in which the starter switch is on in FIG. 1), and when the engine completely explodes, the star switch is turned off and the complete explosion routine begins. In the complete explosion routine, the engine speed N immediately after the complete explosion is
Measure e+ and compare it with the target rotation speed Nup (around 2000 yen) after complete explosion. If Ne1≧Nup, the routine shifts to a warm-up routine that controls the engine speed and air-fuel ratio according to the engine state. In the case of Ne1≧Nup, after detecting Ne, 16 o'clock work/jin is output. Here θ
N is the engine (9) revolution speed (aNe/at). Here, if θN≧θNas (representing the rate of increase in rotational speed), the engine moves to the previous warm-up routine without changing the amount increased after starting. However, θ81. In the case of 1, the engine speed is increased by increasing the amount of fuel corresponding to the amount increased after starting. The engine speed after increasing the amount of fuel is the next engine speed Ne
1 and based on the above procedure, Nel≧Nu
p, S or θN≧θN1. ．． If the following conditions are met, the amount of fuel will be increased to correspond to the increase in scenery after startup. This is shown in Figure 3 as a relationship between engine speed and time.The solid line shows the change characteristics of the engine speed in the case of the conventional example, and the dotted line shows the change characteristics of the engine speed in the case of the present invention. The chain line indicates the above-mentioned target engine speed characteristic 1, and the slope of the applicability curve indicates the rate of increase in engine speed θNum l.The engine speed according to this example is determined by increasing the amount of fuel compared to θN5et. It can be seen that the target rotational speed is reached smoothly and the time required to reach the target rotational speed is shortened compared to the conventional example.

FIG. 4 shows another embodiment of the present invention, in which the amount of intake air (detected by an air flow meter or the like) is used as a control variable instead of the engine speed, and similar effects can be obtained. In addition, in the same figure, G A I is the intake air amount immediately after the engine complete explosion, GAup is the target intake air amount, θA is the time change rate of the intake air amount at the time is elapsed after the complete explosion, and θAset is the target value. be.

As explained above, according to the present invention, the time required to reach the target rotational speed or the target intake air amount can be shortened, and smooth starting performance can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the conventional fuel injection control method, Fig. 2 is a flowchart showing the fuel injection control method according to the present invention, and Fig. 3 shows the change characteristics of the engine speed during startup and warm-up. Figure 4 shows another embodiment of the present invention in comparison with the conventional example.

Claims (1)

[Claims] 1. The fuel injection amount at engine startup is set to 1171J based on the detection outputs of various sensors that detect the operating state of the engine.
In the fuel injection control method for the engine to be controlled, when the engine speed immediately after the engine complete explosion is below the target speed, and when the engine speed increase rate after a predetermined period of time has elapsed after the engine complete explosion is below the target speed. A method for controlling fuel injection for an engine, characterized in that the fuel amount is increased by an amount corresponding to an amount increased after starting the fuel injection amount. 2. In an engine fuel injection control method that controls the fuel injection amount at engine startup based on the detection output of various sensors that detect the engine operating state, if the intake air amount immediately after the engine completes explosion is less than the target intake air amount, If the time change rate of the intake air amount after a predetermined period of time has elapsed after the engine complete explosion is less than the target (directly below), increase the amount of fuel corresponding to the increase after starting of the fuel injection amount by %. A fuel injection control method for an engine.