JPS60116841A - Controller of fuel injection for multicylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To facilitate control and to improve performance of an engine, by a method wherein at the time of a changeover from sequential injection to simultaneous injection to all cylinders, the injection is made to shift to all cylinders injection from the next injection timing to which a discriminating signal of the simultaneous injection has applied. CONSTITUTION:When a changeover is made from sequential injection to simultaneous injection in case of application of the titled controller to a series five- cylinder engine, a matter whether sequential injection is possible or not is discriminated by comparing a time (t) between A and B and the size of an injection pulse width tp which can be known through an engine speed. Then when it is discriminated that the sequential injection is impossible, all cylinders are controlled so that they are made to inject simultaneously through injection timing C available directly after realization of the discrimination. Then at the time of changeover from the simultaneous injection to the sequential injection, the cylinders are controlled so that individual injection corresponding to each of the cylinders is made to reopen in order from the cylinder corresponding to simultaneous injection timing to all the cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel injection device for a multi-cylinder engine, and particularly to a fuel injection control device for switching from sequential injection to full injection.

[Background of the invention]

As is well known, the fuel injection system injects fuel into all cylinders of a multi-cylinder engine at the same time.
As described in Japanese Patent Application No. 240, a method is used in which the fuel is divided into two parts and fuel is alternately injected into each of the 1/2 cylinders. In the case of this injection method, only one dedicated circuit for outputting the injection signals in the control unit is sufficient as long as the respective injection signals do not overlap. Normally, in an engine, it is necessary to provide one fuel injection valve for each cylinder, which is optimal for engine control. However, when one fuel injection valve is provided for each cylinder, there is only one device for driving each fuel injection valve, and this driving device is operated by injection pulses from a microcomputer. On the other hand, the amount of fuel injected from the fuel injection valve is determined by the opening area and injection time of the nozzle of the fuel injection valve. By increasing the opening area of the nozzle, the amount of fuel injected per unit time can be increased. However, the opening area of the nozzle cannot be made large because of the problem of making the fuel finer and the problem of poor controllability when the amount of fuel is small. Therefore, if a certain amount of fuel is required, the valve must be opened for a certain period of time. By the way, the amount of mixture (gasoline and air) supplied to each cylinder of the engine is almost constant, and the amount of fuel does not change during normal driving. The valve must be opened. However, as the engine speed increases, the time from the time of ignition to the time of ignition becomes narrower, and when it becomes shorter than the time of one fuel injection, a situation occurs in which the amount of supplied fuel becomes insufficient.

That is, each cylinder's intake air 1. All cylinders will not be able to synchronize with the combustion cycle. For this reason, it has the disadvantage that it is difficult to make full use of the engine's performance.

Therefore, a method has been proposed in which sequential injection is maintained in practical use, and when the load is high, the injection is switched to group injection in which the injection is divided into two or three groups. However, even with this method of switching to group injection, control is complicated,
This has the disadvantage that control becomes more complicated if grouping is not done evenly.

[Purpose of the invention]

An object of the present invention is to provide a fuel injection control device that is easy to control and that can fully utilize engine performance.

[Summary of the invention]

The present invention shifts to all-cylinder injection from the next injection timing after inputting the all-cylinder simultaneous injection discrimination signal, and when the sequential injection discrimination signal is input, the all-cylinder simultaneous injection occurs after the timing of the discrimination signal. By starting sequential injection from the cylinder at the specified timing, control is facilitated and engine performance is fully utilized.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 1 schematically shows an engine to which the present invention is applied.

In the figure, an engine 1 is connected to an intake pipe 2 in which fuel injection valves 3 are provided in correspondence with the number of cylinders. The intake pipe 2 provided for each cylinder is
They are combined into one in the upstream collector 4, and upstream of this collector 4 there is a throttle valve 5 for determining the amount of intake air.
is provided. Air corresponding to the opening degree of the throttle valve 5 is sucked into the intake pipe 2 via the collector 4. This amount of air taken in is measured by an air flow sensor 6 provided upstream of the throttle valve 5.

On the other hand, the engine rotation speed is detected by a ft rotation sensor built into the power distributor 13. This detected engine speed is taken into a control unit (12). Further, a signal from the engine temperature sensor 11, a combustion gas mixture ratio signal from the 0□ sensor 10, and the like are input to the control unit 12.

Furthermore, fuel is supplied to the engine through an injector 3.
The amount of fuel is measured by the valve opening time. Further, the fuel injected from the injector 3 is sent after the fuel in the fuel tank 7 is pressurized and regulated by a fuel pump 8 and a regulator 9.

FIG. 2 shows the input/output relationship shown in FIG. 1 using a block diagram, with sensors on the left side and actuators on the right side of the control unit ECU.

! Inside the ECU, there is a waveform shaping circuit shown on the left, an AD converter, input/output exchange, an l10LSI section that performs arithmetic processing, a CPU that issues commands to this, and a CPU on the right that drives output actuators. Drive circuits etc. are arranged.

FIG. 3 shows fuel injection pulses and injection timing using an example of an in-line five-cylinder engine. In addition, the characteristics of the injector are gmm in order to inject the maximum amount.
degree is necessary. Further, FIG. 3 shows the situation with respect to the crank angle when the intake timing and injection timing are completely synchronized in a five-cylinder engine. That is, since one cycle is 720'', the angle between the intake air of the first cylinder and the fifth cylinder that comes next is 144 degrees.

Therefore, if the engine speed increases, the angle 14
The time required to rotate 4 degrees, that is, the time between AB is 3
000f[Xll, when outputting an injection pulse of 4nIS at a high engine load, for example 5 mS, the injection pulses will overlap at the beginning and end υ of each valve opening. However, as mentioned above, in order to realize this complicated system, an expensive 110LSI is required, so it is impossible to realize sequential injection as shown in FIG. 3 in the entire engine area.

An embodiment of the present invention is shown in FIGS. 4 and 5.

FIG. 4 shows the case of switching from sequential injection to simultaneous injection, and the case of switching from joint injection to sequential injection as shown in FIG. 5, respectively.

First, the case of switching from sequential injection to simultaneous injection in all cylinders in FIG. 4 will be described.

Whether or not sequential injection is possible can be determined by comparing the magnitude of the time t between AB and the injection pulse width t, which can be determined from the engine rotation speed. As a result of this determination, a determination signal is established when sequential injection is impossible. In the injection timing shown in FIG. 4 immediately after this determination signal is established, all cylinders are injected at the same time starting from C. Originally, this timing C is the injection timing for only the 3rd cylinder, and after the injection of the 3rd, 2nd, and 4th cylinders is completed,
It is common to move to simultaneous injection in all cylinders.

In this way, if all cylinders are injected at the same time from injection timing C immediately after the discrimination signal is established, the first and fifth cylinders will be injected twice in one cycle when compared to one cycle of 2/gin. Therefore, extra fuel will be injected, but when switching from sequential to simultaneous injection, it is always in the direction of acceleration, and these injections have an advantageous effect on improving drivability.

Therefore, after the determination signal is established, fuel is injected at the same time in all cylinders starting from the closest injection type (regardless of whether the injection timing for the cylinder being visited was incorrect or not).

Next, the case of switching from simultaneous injection to sequential injection in FIG. 5 will be described.

Now, when the determination signal 0 for switching to sequential injection is established, sequential injection does not start immediately but is stopped for only one cycle. That is, for example, if simultaneous injection was performed at A, sequential injection must be restarted from the cylinder corresponding to the cylinder where simultaneous injection was performed, that is, from A. The determination is shown in FIG. Even if the determination is made at any timing after A until the next A, the timing at which this determination is made has no relation to the restart of injection. Therefore, if simultaneous injection is performed at timing C, injection will always be restarted from the C typing, that is, from the third cylinder, no matter when the determination is established.

Therefore, according to this embodiment, sequential injection that fully brings out the performance of the engine is possible with an inexpensive control unit.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily control the engine and to fully utilize the engine performance.

[Brief explanation of drawings]

1 and 2 are configuration diagrams of a fuel injection device to which the present invention is applied, FIG. 3 is an explanatory diagram of injection timing, and FIGS. 4 and 5.
The figure shows an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 3... Injector, 5... Throttle valve, 12... Control unit. Agent Patent Attorney Tatsuyuki Unuma

Claims (1)

[Claims] 1. In a fuel injection control device for a multi-cylinder internal combustion engine that calculates the amount of fuel to be supplied to an engine with multiple cylinders from the engine speed and intake air amount and injects the fuel individually corresponding to each cylinder, the operating time of fuel injection When the difference between the combustion cycle time and the combustion cycle time between cylinders of the engine becomes less than a predetermined time, the next injection timing is switched to simultaneous injection in all cylinders, and when a signal to cancel simultaneous injection in all cylinders is output, all cylinders are injected simultaneously. A fuel injection control device for a multi-cylinder internal combustion engine, characterized in that individual injection corresponding to each cylinder is restarted sequentially from a cylinder corresponding to cylinder simultaneous injection timing.