JPH0249952A - Internal combustion engine fuel supply control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine that performs preliminary injection for forming a preliminary mixture.

<Prior art> While each cylinder is equipped with a main fuel injection valve, an auxiliary fuel injection valve is provided in the upstream part of the intake passage to perform preliminary injection, form a preliminary mixture, and increase charging efficiency through the cooling effect of the heat of vaporization. Or,
Some are designed to improve flammability.

In addition, in a device that performs this type of preliminary mixture formation, an ultrasonic atomization device is installed downstream of the auxiliary fuel injection valve, and the fuel injected from the auxiliary fuel injection valve is made to adhere to the vibrator of the ultrasonic device and become atomized. A device designed to promote the change in speed has become common (see Japanese Utility Model Application Publication No. 62-200157, etc.).

<Problems to be Solved by the Invention> Incidentally, in conventional devices of this type, the fuel injection period of the auxiliary fuel injection valve is also performed in synchronization with the engine rotation, but in particular, as described above, the ultrasonic wave In a type of atomizer that promotes atomization of fuel, in a low rotation range such as idling, the time required for the fuel injected from the auxiliary fuel injection valve to atomize, as shown in FIG. The interval (period of the reference crank angle signal) between cylinders at the same stroke time may be longer.

In this case, there will be a period in which the supply of fuel injected from the auxiliary fuel injection valve is interrupted, but since rotational fluctuations tend to become large in the low rotational speed range, the amount of fuel for each cylinder may vary depending on the intake timing and fuel supply delay time. The non-uniformity of the supply amount is large, which further promotes rotational fluctuations and impairs stability.

The present invention was developed in view of these conventional problems, and by changing the injection interval from the auxiliary fuel injection valve, continuous fuel supply is performed, thereby making the fuel supply amount uniform among the cylinders. An object of the present invention is to provide a fuel supply control device for an internal combustion engine that achieves improved stability.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes a main fuel injection valve that injects fuel to each cylinder, and also injects fuel to all cylinders in the upstream portion of the intake passage. In a fuel supply control device for an internal combustion engine including an auxiliary fuel injection valve for forming a preliminary air-fuel mixture, an atomization time estimating the time required for the fuel injected from the auxiliary fuel injection valve to be atomized from the operating state. The fuel injection device includes an estimating means and an injection timing control means for injecting fuel from the auxiliary fuel injection valve at each estimated atomization time.

Further, the atomization time estimating means may estimate the atomization time based on, for example, the required injection amount from the auxiliary fuel injection valve and the engine rotation speed.

The injection timing control means injects fuel from the auxiliary fuel injection valve at every atomization time estimated by the atomization time estimating means based on, for example, the required injection amount from the auxiliary fuel injection valve and the engine rotation speed. It will be held on.

Therefore, the fuel supply from the auxiliary fuel injection valve is performed continuously without interruption, and the amount of fuel supplied to each cylinder can be made uniform even due to rotational fluctuations.

<Example> do.

In FIG. 2 showing the configuration of an embodiment, an internal combustion engine l is equipped with a main fuel injection valve 3 that injects fuel at a predetermined timing for each intake port of each cylinder of an intake manifold 2, and a throttle valve 4. An auxiliary fuel injection valve 5 that injects fuel to all cylinders is installed at the upstream side of the intake passage near the upstream side (or downstream side) of the engine.

A vibrator 6A of an ultrasonic atomization device 6 is provided near the downstream side of the throttle valve 4, and the fuel injected from the auxiliary fuel injection valve is attached thereto and atomized by ultrasonic vibration.

An air flow meter 7 for detecting the intake air flow rate Q is provided upstream of the throttle valve 4 of the intake manifold 2 . In addition, a crank angle sensor 8 for detecting engine rotational speed N. Cooling water temperature T. Water temperature sensor for detection9. Signals from the 02 sensor 10, etc., which detects the oxygen concentration in exhaust gas to detect the air-fuel ratio for air-fuel ratio feedback control, are input to the control unit 11, and the control unit 11 responds to the operating state based on these signals. Main fuel injection valve 3
The amount and timing of each fuel injection from the auxiliary fuel injection valve 5 are set.

Next, fuel injection control by the control unit 1 will be explained according to the flowchart shown in FIG.

In step (denoted as S in the figure) (2), signals from various sensors are read.

In step 2, the basic injection pulse width MT when the fuel injection amount for each cylinder per engine rotation is obtained only by the main fuel injection valve 3 is calculated using the following equation.

MTP = K - Q/N In step 3, the effective injection pulse width M of the main fuel injector 3
T is calculated using the following equation.

MT, = MT, ・α・K, -COEF(1xinJ
) Here, α is a feedback correction coefficient K for air-fuel ratio feedback control, which is set by proportional-integral control or the like based on the signal from the 0□ sensor 10.

C0EF is a learning correction coefficient for improving responsiveness during transient operation by bringing the feedback correction coefficient α closer to the reference value.
are various correction coefficients set based on water temperature T8, etc.,
7 indicates the injection amount sharing ratio with respect to the total injection amount of the auxiliary fuel injection valve 5.

In step 4, the final fuel injection pulse width MT of the main fuel injection valve 5 is performed every 1/2 rotation of the engine.

is calculated using the following formula.

MT= =2xMT, +MTs However, MT is the invalid injection pulse width of the main fuel injection valve 3 based on the panteri voltage.

In step 5, the basic injection pulse is determined based on the MT, which is used to obtain the total injection amount per engine rotation using one auxiliary fuel injection valve 5 when a corresponding injection amount is injected by the main fuel injection valves 3 corresponding to the number of cylinders. The width ST is calculated using the following equation.

ST, = MT, ・K.

However, K indicates the ratio of the injection pulse widths of the auxiliary fuel injection valve 5 and the main fuel injection valve 3 for the same flow rate, and this value is determined depending on the number of fuel injection valves and the difference in flow rate characteristics.

In step 6, the effective injection pulse width ST of the auxiliary fuel injection valve 5 is calculated using the following equation.

ST, =ST, ・α, to -C0EF -X1nj
Next, in step 7, it is determined whether the engine rotation speed N calculated based on the signal from the crank angle sensor 8 exceeds a low rotation setting value N0.

If it is determined that the width ST is greater than the auxiliary fuel injection valve 5, the process proceeds to step 8, and the final fuel injection pulse width ST from the auxiliary fuel injection valve 5 is calculated using the following equation.

STi = 1/2XST, +ST! ! However, the coefficient of 1/2 means that the auxiliary fuel injector 5 is 1/2 of the engine.
This is to perform injection twice per rotation, and ST is the invalid injection pulse width of the auxiliary fuel injection valve 5 based on the battery voltage.

In step 9, an injection pulse having the pulse width ST□ set as described above is outputted to the auxiliary fuel injection valve 5 for preliminary injection every time the reference crank angle signal is input from the crank angle sensor 8. Note that fuel injection from the main fuel injection valve 3 for each cylinder is also performed at the same cycle.

On the other hand, in the judgment at step 7, the engine rotation speed N is the set value N.
If it is determined to be 0 or less, proceed to step 10,
The amount of fuel from the auxiliary fuel injection valve 5 is determined from a map stored in advance in the ROM based on the amount of fuel adhering to the vibrator 6A estimated from the engine rotational speed N and the effective injection pulse width ST of the auxiliary fuel injection valve 5. The atomization time T int until the injected fuel adheres to the vibrator 6A and finishes atomization is searched and determined. The function of step 10 corresponds to an atomization time estimating means.

Next, the process proceeds to step 11, in which the final fuel injection amount ST when the auxiliary fuel injection valve 5 injects at intervals of the atomization time is calculated using the following equation.

STi = 1/2XT, , t /T,. ,XST,+
ST3 In step 12, the injection pulse having the pulse width ST set as above is applied to the atomization time T.
i n to the auxiliary fuel injection valve 5 for preliminary injection. The function of step 12 corresponds to injection timing control means.

If such control is performed, the next fuel injection will start at the timing when the atomization of the injected fuel from the auxiliary fuel injection valve 5 is completed at low rotation speeds below the special idle setting value N0, as shown in FIG. Fuel supply from the auxiliary fuel injection valve 5 to the cylinders is performed continuously without interruption.

Therefore, even if there is a shift in the intake stroke for each cylinder or a delay in fuel supply due to rotational fluctuations at low rotational speeds, the amount of fuel supplied to each cylinder can be equalized, preventing rotational fluctuations from being exacerbated and providing stable You can improve your sexuality.

In this example, an apparatus equipped with an ultrasonic atomizer is shown, but the atomization time is not limited to this, and the atomization time can be set under the condition that the atomization time of the injected fuel is shorter than the injection period in synchronization with the engine rotation. It is only necessary to estimate this and change it to the period.

<Effects of the Invention> As explained above, according to the present invention, the preliminary injection period can be set to the estimated atomization time of the injected fuel from the auxiliary fuel injection valve, so the fuel supply can be maintained even at low rotation speeds. This can be done continuously, thereby making it possible to equalize the amount of fuel supplied between cylinders and improving the stability of the engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
A diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing the fuel injection control routine of the same embodiment, FIG. 4 is a time chart showing the injection timing of the same control example, and FIG. 5 is a conventional example. 3 is a time chart showing the injection timing. ■...Engine 3...Main fuel injection valve 5...Auxiliary fuel injection valve 7...Air flow meter 8...
・Crank angle sensor 11...Control unit Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima No. 4 Figure 5 8f659 single j

Claims (2)

[Claims] (1) Fuel supply for an internal combustion engine that is equipped with a main fuel injection valve that injects fuel into each cylinder and an auxiliary fuel injection valve that injects fuel into all cylinders upstream of the intake passage for forming a preliminary mixture. The control device includes: an atomization time estimating means for estimating the time required for the fuel injected from the auxiliary fuel injection valve to be atomized based on the operating state; 1. A fuel supply control device for an internal combustion engine, comprising: injection timing control means for injecting fuel. (2) The fuel supply control device for an internal combustion engine according to claim 1, wherein the atomization time estimating means estimates the atomization time based on the required injection amount from the auxiliary fuel injection valve and the engine rotation speed.