JPS63186936A - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to cope with the request for increasing the fuel injection quantity, in a prescribed high-load high-speed operating region, by providing the second injection pulse signal output means which outputs an injection pulse signal, prior to the first injection pulse signal output means, in the number of injection times less than that by the first one. CONSTITUTION:A control means B by which an electromagnetic type fuel injection valve A equipped in the intake air passage on the upstream side of a throttle valve is electrified and driven in response to an injection pulse signal is provided. On the other hand, the first output means C which outputs an injection pulse signal in the prescribed number of times per the number of revolutions of an engine, and the first setting means D which sets the pulse width of the injection pulse signal sent by this means C in correspondence to the operating conditions of the engine are provided respectively. Further, the second output means E which outputs an injection pulse signal, in a prescribed high-load high-speed operating range, prior to the first output means C, in the number of injection times less than that by the first output means C, and the second setting means F which sets the pulse width of the injection pulse signal sent by this means E in correspondence to the operating conditions of the engine are provided respectively.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a so-called single point injection (S, P, r, ) type in which an electromagnetic fuel injection valve is installed in the intake passage upstream of the throttle valve of an internal combustion engine. This invention relates to an electronically controlled fuel injection device.

<Prior Art> In an electronically controlled fuel injection system for an internal combustion engine, an electromagnetic fuel injection valve installed in the intake passage is generally energized and driven by an injection pulse signal having a pulse width corresponding to the injection amount. In this case, Ti during the injection pulse is determined by the following equation.

Ti=TpXCOEF+Ts Here, Tp is in the fundamental pulse and is determined by the following equation.

Tp-KxQ/N Note that K is a constant, Q is the intake air flow rate, N is the engine speed, and C0EF is various correction coefficients that are mainly set based on the engine cooling water temperature. Further, Ts is for correcting a change in the injection flow rate of the fuel injection valve (valve opening delay) due to a change in the buff battery voltage.

In the so-called single point injection (S, P, 1.) type, in which an electromagnetic fuel injection valve is installed in the intake passage upstream of the throttle valve of the engine, fuel is injected in synchronization with an ignition signal, etc. every two revolutions of the engine. The injection pulse width Ti for the valve
The injection pulse signal is outputted to the fuel injection valve to inject and supply fuel to the engine.

<Problems to be Solved by the Invention> By the way, the allowable maximum value 711111X of the pulse width Ti of the injection pulse signal, that is, the maximum injection time, is
Injection cycle (interval of injection start timing) determined by T
The required injection interval time ΔT (for example, 0.3 seconds) is determined by (T
1 maw ” T - ΔT), therefore, in the engine high load, high rotation region where the injection period T is short and the required injection amount is large, the required injection can be achieved by injection with this maximum injection pulse width Ti□8 as the engine output increases. When the injection amount cannot be obtained, the injection amount per unit time is increased by enlarging the nozzle hole of the fuel injection valve or increasing the fuel pressure, thereby securing the required injection interval time ΔT and then achieving the required injection amount. I made sure to get the injection amount.

However, if the injection amount per unit time by the fuel injector is increased in this way to meet the requirement for the maximum injection amount, it becomes difficult to control the injection amount in operating regions such as idling where the required injection amount is low. There was a problem.

The present invention has been made in view of the above-mentioned problems, and provides an electronically controlled fuel that can respond to the request for an increase in the required injection amount in the high engine load and high rotation region while suppressing the enlargement of the injection hole of the fuel injection valve and the increase in fuel pressure. The purpose is to provide an injection device.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. an injection valve drive control means, a first injection pulse signal output means for outputting the injection pulse signal at a unit engine rotational speed or a predetermined number of times;
a first injection pulse width setting means for setting the pulse width of the injection pulse signal by the injection pulse signal output means in accordance with the engine operating state; and a first injection pulse width setting means giving priority to the first injection pulse signal output means in a predetermined high load, high rotational operating region. a second injection pulse signal output means for outputting an injection pulse signal a predetermined number of times less than the number of injections by the first injection pulse signal output means; and a pulse width of the injection pulse signal output by the second injection pulse signal output means. An electronically controlled fuel injection device for an internal combustion engine is provided with a second injection pulse width setting means that is set according to the engine operating state.

<Operation> According to this electronically controlled fuel injection device, for example, the first injection pulse signal output means outputs an injection pulse signal every A rotation of the engine (twice per rotation), and the second injection pulse signal output means outputs an injection pulse signal every A rotation of the engine (twice per rotation). If the output is performed once per engine rotation, the injection period T by the second injection pulse signal output means will be twice that of the first injection pulse signal output means if the engine rotation speed is the same. However, since the necessary injection interval ΔT that determines the maximum injection pulse width T 111aK is constant regardless of the injection period T, the maximum injection pulse width Ti□ in the second injection pulse signal output means is shown in FIG. , 1g (=27-ΔT) is the maximum injection pulse width Ti, □+ (-
'r-ΔT) by the required injection interval ΔT.

Therefore, by setting the number of injections to %, the amount of fuel that must be supplied in one injection doubles, but the maximum injection pulse width T ill@X, that is, the injection time, increases by more than twice as much. Extra fuel can be injected. For this reason, in the engine high-load, high-speed region where the injection period T is short and the required amount is large, it cannot be satisfied with the normal number of fuel injections. (The required injection interval ΔT cannot be secured unless the injection interval is increased or the fuel pressure is increased.) This can be met by reducing the number of injections.

<Example> An embodiment of the present invention will be described below based on the drawings.

In FIG. 2 showing one embodiment, detection signals from various sensors installed in various parts of the engine are input to a control unit 4 that includes a microcomputer, and the control unit 4 receives these signals. The drive circuit 5 outputs an injection pulse signal, which is set as described later based on
is driven to inject an amount of fuel corresponding to the pulse width Ti of the injection pulse signal. That is, in this embodiment, the control unit 4 and the drive circuit 5 constitute a fuel injection valve drive control means, and the control unit 4 and the drive circuit 5 constitute a fuel injection valve drive control means. a second injection pulse signal output means; a first injection pulse signal output means; It also serves as second injection pulse width setting means.

The various sensors include a crank angle sensor 1 that outputs an engine speed signal N, an air flow meter 2 that outputs an intake air flow rate signal Q, and a water temperature sensor 3 that outputs an engine cooling water temperature signal Tw.

Next, fuel injection control in this embodiment will be explained according to the flowcharts of FIGS. 3 and 4.

The injection pulse width setting control routine shown in the flowchart of FIG. 1, the intake air flow iiQ detected by the air flow meter 2, and the cooling water temperature Tw detected by the water temperature sensor 3 are input.

In step 2, the basic pulse width Tp (=KX
Q/N; is a constant).

In step 3, the cooling water temperature Tw input in step 1 is
Mainly, various correction coefficients C0EF are set.

In step 4, the basic pulse width T set in step 2 is
The effective injection pulse width Te is calculated using p and the various correction coefficients C0EF set in step 3 (Te-TpXC
OEF).

In step 5, it is determined whether the current engine operating state is in an operating range where the number of injections per revolution of the engine should be reduced. In this embodiment, normally once per engine revolution (
Fuel injection is performed once per revolution A, and the number of injections is reduced to once per engine revolution in a predetermined high-load, high-speed range. As shown in FIG. 5, the predetermined high-load, high-speed region is defined by the basic fuel injection ITp as the engine load (the opening degree of the throttle valve 60 may be substituted) and the engine speed N. In the operating area where
The operating range in which the number of injections is reduced is defined as a time when the engine speed N and the basic fuel injection amount Tp each exceed a predetermined value (Nl, TI)+). Therefore, in step 5, the engine speed N input in step 1 and the basic pulse width Tp calculated in step 2 are set to the predetermined values (Nl).

Tp+) to determine whether it is in a predetermined high load/high rotation range.

When it is determined in step 5 that the current operating state is in a predetermined high load, high rotation region where the number of injections should not be reduced, the process proceeds to step 6, where the cooling water temperature Tw input in step 1 is set to a predetermined value Tw. It is determined whether the engine is completely warmed up when the temperature exceeds the temperature.

This is because when the engine is cold, the atomization of the fuel deteriorates, so if the number of injections is reduced and the amount of fuel supplied in one injection is increased, good air-fuel mixture cannot be produced.

If it is determined in step 6 that the cooling water temperature Tw exceeds the predetermined value TwI, the process proceeds to step 7 and indicates that the operating state is one in which injection should be performed once per engine revolution. Set the rotation flag to 1. Then, in step 8, the effective injection pulse width set corresponding to two injections per engine revolution is doubled to obtain an injection pulse width T.
Set i (=2Te+T3). Here, the correction numerator s
is for correcting a change in the injection flow rate of the fuel injector due to a change in battery voltage (correcting a delay in the rise of the valve body).

On the other hand, when it is determined in step 5 that the current engine operating state is not in the predetermined high-load, high-speed region, that is, the engine speed N input in step 1 and the basic pulse width Tp calculated in step 2 are both within the predetermined range. value or less (N+, Tp
+; see Fig. 5), and when it is determined in step 6 that the cooling water temperature Tw is less than or equal to the predetermined value Tw, the process proceeds to step 9 and the 1 rotation/rotation flag is set to 0. . That is, when proceeding from step 5 or step 6 to step 9, two injections are performed per normal engine rotation,
In the next step 10, the effective injection pulse width Te calculated in step 4 is used as is, and the injection pulse width Ti (=
Te+Ts).

The injection pulse signal having the injection pulse width Ti thus set is output to the drive circuit 5 according to the routine shown in the flowchart of FIG.

The routine shown in the flowchart of FIG. 4 is executed every two revolutions of the engine (at a predetermined crank angle position every two revolutions) based on the engine speed signal N from the crank angle sensor 1, and is executed in step 21. Now, the 1 time/time set in step 7 or step 9 of the flowchart in FIG.
Determine whether the 1 rotation flag is 1 or 0. Here, when it is determined that the 1 time/1 rotation flag is 1,
That is, when the current engine operating state is in a predetermined high-load, high-speed region where the number of injections should be reduced, the process advances to step 22 to determine whether the injection reservation flag is set to 1 to perform one injection per engine revolution. Determine whether it is O. Here, when it is determined that the injection reservation flag is O,
Proceeding to step 25, the injection reservation flag is set to 1, and the process returns without outputting an injection pulse signal.

On the other hand, when it is determined in step 22 that the injection reservation flag is 1, the process proceeds to step 23, where the injection reservation flag is set to O, and the process proceeds to step 24, in which the injection reservation flag set in step 8 of the flowchart of FIG. Pulse width Ti
Output an injection pulse signal having (-2Te+Ts).

In other words, since this routine is executed every two revolutions of the engine, normally (when the 1st/1st revolution flag is O and the process advances from step 21 to step 24), each time this routine is executed, Injection pulse signal (pulse width Ti=Te
+Ts), but the current engine operating state is one in which the number of injections should be reduced (the 1st/1st revolution flag is 1).
), and when one injection is performed per engine, an injection pulse signal is output every two times this routine is executed.

As described above, according to this embodiment, the number of injections per engine rotation is reduced by half in the engine high load, high rotation region where the injection period T becomes short and the required injection amount increases.

By the way, the maximum value Ti□8 of the injection pulse width Ti is determined by the injection period T determined by the engine speed N and the valve body that avoids continuous injection by the fuel injection valve 8 and occurs when the fuel injection valve 8 closes. is determined by the required injection interval time ΔT (approximately constant regardless of the injection period T) in order to avoid variations in the injection amount at the start of injection due to the jump phenomenon of (
Ti□8-T-ΔT) Therefore, if the number of injections per engine rotation is reduced by half and the injection cycle is set to 2T, the maximum injection pulse width Ti□8 becomes 2T- under the same engine speed N.
ΔT, and by halving the number of injections, even if the amount of fuel to be injected is doubled, an extra time of ΔT is available for injection. Therefore, if the number of injections in the high engine load, high rotation region is reduced as described above, the amount that can be injected (maximum injection ii) increases compared to the normal number of injections.

In other words, with two injections per engine revolution, in a predetermined high-load, high-speed region where the pulse width Ti exceeding the maximum injection pulse width 71smX is set, the maximum injection pulse width Ti□ can be reduced by reducing the number of injections. The required amount can be met within 8. Therefore, even if the pulse width Ti is set to exceed the maximum injection pulse width T1mmx with two injections per engine revolution, there is no need to enlarge the nozzle hole of the fuel injection valve 8 or increase the fuel pressure. This makes it possible to maintain good injection amount control in operating regions where the required amount of injection amount is small, such as in idling operating conditions.

<Effects of the Invention> As explained above, according to the present invention, by reducing the number of injections per engine unit rotational speed in a predetermined high-load, high-speed region of the engine, the maximum injection amount in such a region is reduced. This makes it possible to respond to requests for increasing the maximum injection amount without enlarging the injection hole of the fuel injection valve or increasing the fuel pressure, and it is also possible to control the injection amount in areas where the required injection amount is small. This has the effect of keeping it in good condition.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the present invention, Fig. 3 is a flow chart showing injection pulse width setting control in the above embodiment, and Fig. 4 is the same embodiment as above. FIG. 5 is a flowchart showing the output control of the injection pulse signal in the above embodiment.
The graph showing the 6N region and FIG. 6 are time charts for explaining the present invention in detail. 1... Crank angle sensor 2... Air flow meter 3... Water temperature sensor 4... Control unit 5... Drive circuit 6... Throttle valve 7
...Intake passage 8...Fuel injection valve

Claims (1)

[Claims] a fuel injection valve drive control means that energizes and drives an electromagnetic fuel injection valve installed in an intake passage upstream of a throttle valve in response to an injection pulse signal; and a fuel injection valve drive control means that outputs the injection pulse signal at a predetermined number of times per unit engine speed. a first injection pulse signal output means; a first injection pulse width setting means for setting the pulse width of the injection pulse signal by the first injection pulse signal output means according to the engine operating state; , the first injection pulse signal signal output means has priority over the first injection pulse signal output means.
a second injection pulse signal output means for outputting an injection pulse signal at a predetermined number of times less than the number of injections by the injection pulse signal output means; and a pulse width of the injection pulse signal output by the second injection pulse signal output means to an engine operating state. An electronically controlled fuel injection device for an internal combustion engine, comprising: second injection pulse width setting means for setting the width accordingly.