JPH06336944A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To supply an appropriate quantity of fuel to appropriately control an air/fuel ratio by providing an injection quantity computing means computing the fuel injection quantity of a fuel injecting means in consideration of supplied fuel quantity according to the suction stroke of a cylinder. CONSTITUTION:The fuel injection control device of an internal combustion engine is provided with a fuel injection means M1 communicated with the plural cylinders of the internal combustion engine to inject and supply the fuel concurrently to respective cylinders. Also a driving control means M2 is provided which is drive-controlling the fuel injection means M1 to perform fuel injection respectively in the suction strokes of the respective cylinders. In an injection quantity computing means M3, the fuel injection quantity of the fuel injecting means M1 is computed in consideration of supplied the fuel quantity according to the suction strokes of other cylinders for satisfying the fuel requisition quantity of a cylinder performing its suction stroke based on a fuel distribution ratio to the respective cylinders at the time of fuel injection. Consequently, an appropriate quantity of fuel according to fuel requisition quantity can be supplied to plural cylinders from a common fuel injection valve, appropriately controlling the air/fuel ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for injecting and supplying fuel to a plurality of cylinders of the internal combustion engine by a common fuel injection valve. Is.

[0002]

2. Description of the Related Art As a conventional fuel injection control device for this kind of internal combustion engine, for example, those described in Japanese Utility Model Publication No. 33-3202 and Japanese Utility Model Publication No. 53-140810 can be cited.

In these fuel injection control devices, in order to reduce the number of fuel injection valves and reduce the cost, a common fuel injection valve is provided between the intake pipes of two adjacent cylinders of the internal combustion engine, and this fuel injection control device is used. The injection valve is configured to inject fuel into both intake pipes at the same time.

[0004]

As is well known, the intake negative pressure of the internal combustion engine varies depending on the intake, compression, combustion, and exhaust strokes. When fuel is injected into the intake pipe of a cylinder, a larger amount of fuel is supplied to the cylinder having the higher negative pressure. Therefore, the fuel demand amount of each cylinder is not satisfied, and the air-fuel ratio may not be accurately controlled.

Therefore, the present invention provides an internal combustion engine capable of supplying an appropriate amount of fuel from a common fuel injection valve to a plurality of cylinders in accordance with a required fuel amount, and thereby accurately controlling the air-fuel ratio. An object is to provide a fuel injection control device.

[0006]

As shown in FIG. 1, a fuel injection control device for an internal combustion engine communicates with a plurality of cylinders of the internal combustion engine and injects and supplies fuel to each cylinder at the same time. Based on a fuel injection means M1, a drive control means M2 for driving and controlling the fuel injection means M1 to execute fuel injection in the intake stroke of each cylinder, and a fuel distribution ratio to each cylinder at the time of the fuel injection. , An injection amount calculation means for calculating the fuel injection amount of the fuel injection means M1 in consideration of the amount of fuel already supplied in accordance with the intake strokes of the other cylinders so as to satisfy the fuel demand amount of the cylinder in which the intake stroke is being executed. And M3.

As shown in FIG. 1, a fuel injection control device for an internal combustion engine according to a second aspect of the present invention includes a fuel injection means M1 which communicates with a plurality of cylinders of the internal combustion engine and injects and supplies fuel to each cylinder simultaneously. Driving control means M2 for driving and controlling the fuel injection means M1 to execute fuel injection at the time when the fuel distribution ratios to the respective cylinders are substantially equal to each other, and total fuel demand for each cylinder are calculated to calculate the fuel consumption. The injection amount calculating means M3 is set as the fuel injection amount of the injection means M1.

A fuel injection control device for an internal combustion engine according to a third aspect of the present invention communicates with a plurality of cylinders of the internal combustion engine and drives and controls the fuel injection means for simultaneously injecting and supplying fuel to each cylinder and the fuel injection means. The first drive control means for executing fuel injection in the intake stroke of each cylinder, and the fuel demand amount of the cylinder executing the intake stroke based on the fuel distribution ratio to each cylinder at the time of fuel injection. In order to satisfy the above, the first injection amount calculation means for calculating the fuel injection amount of the fuel injection means in consideration of the supplied fuel quantity in association with the intake stroke of the other cylinder, and the drive control of the fuel injection means are performed. , Second drive control means for executing fuel injection at a time when the fuel distribution ratios to the respective cylinders are substantially equal to each other, and a total fuel requirement amount of the respective cylinders is calculated and set as a fuel injection amount of the fuel injection means. Calculation of the second injection amount And the first drive control means and the first injection amount calculation means execute fuel injection control when the internal combustion engine has a rotational speed lower than a predetermined speed, and when the internal combustion engine has a predetermined rotational speed or higher, The second drive control means and the second injection amount calculation means are provided with control switching means for executing fuel injection control.

[0009]

According to the present invention, the fuel injection means M1 controlled by the drive control means M2 executes fuel injection in the intake stroke of each cylinder, and the injected fuel is not only supplied to the cylinder in the intake stroke but also to other cylinders. Is also supplied. Therefore, fuel is supplied to each cylinder along with the intake stroke of the other cylinders, and further fuel is supplied during the subsequent intake stroke of the cylinders, and the fuel is burned in the expansion stroke.

When each cylinder is performing the intake stroke, the amount of fuel already supplied in accordance with the intake strokes of the other cylinders is taken into consideration, and based on the fuel distribution ratio to each cylinder,
The injection amount calculation means M3 calculates a fuel injection amount enough to satisfy the fuel demand amount of the cylinder in the intake stroke, and this fuel injection amount is injected by the fuel injection means M1. Therefore, it becomes possible to supply an appropriate amount of fuel to each cylinder according to the required fuel amount. Further, since most of the required fuel amount is supplied to each cylinder during the intake stroke, the accuracy of injection amount control is improved to the level of independent injection.

According to the second aspect of the present invention, the fuel injection means M1 controlled by the drive control means M2 executes the fuel injection at the time when the fuel distribution ratios to the respective cylinders are substantially equal. Fuel is supplied. Here, the total fuel requirement amount, which is the sum of the fuel requirement amounts of the respective cylinders, is calculated by the injection amount calculation means M3, and the total fuel requirement amount is injected by the fuel injection means M1. It is possible to supply an appropriate amount of fuel according to the required amount. Further, since the fuel injection amount can be easily calculated only by obtaining the sum of the fuel demands of the respective cylinders, the number of words in the control system program is greatly reduced.

In the third aspect of the present invention, since the control by the first drive control means and the first injection amount calculation means performs fuel injection in the intake stroke of each cylinder, the period of the intake stroke in the high engine speed range. May be shortened and the fuel requirements of both cylinders may not be satisfied. On the other hand, the second drive control means for concentrating the fuel injection into each cylinder once and the second
Such a situation does not occur even in the high rotation speed range by the control of the injection amount calculation means of 1. In the present invention, when the internal combustion engine has a predetermined rotational speed or higher, the control by the first drive control means and the first injection amount calculation means is switched to the control by the second drive control means and the second injection amount calculation means. Even in the high engine speed range, an appropriate amount of fuel is supplied according to the fuel demand.

[0013]

【Example】

<First Embodiment> A fuel injection control apparatus for an internal combustion engine according to a first embodiment of the present invention will be described below.

FIG. 2 is an overall configuration diagram showing a fuel injection control device for an internal combustion engine which is a first embodiment of the present invention.

The internal combustion engine 1 provided with the fuel injection control device of the present embodiment is constructed as a spark ignition type four cylinder four cycle engine. As shown in the figure, an air cleaner (not shown) is provided on the upstream side of the intake passage 2 of the internal combustion engine 1, and one end of four intake branch pipes 3 is connected to the downstream side of the intake passage 2 to connect each intake branch. The other end of the pipe 3 is connected to a corresponding cylinder of the internal combustion engine 1. Then, the intake air is introduced into the intake passage 2 through the air cleaner due to the negative pressure generated during the intake stroke of each cylinder, and the flow rate of the intake air is adjusted by the throttle valve 4 provided in the intake passage 2. While being distributed to each intake branch pipe 3, they are supplied to each cylinder.

Between the intake branch pipes 3 of # 1 and # 2, and # 3
Fuel injection valves 5 are respectively arranged between the # 4 and # 4 intake branch pipes 3, and the tip ends of the fuel injection valves 5 are connected to the inside of the intake branch pipes 3 on both sides via communication holes 6 formed in a bifurcated shape. Is in communication with. Fuel stored in a fuel tank 7 of the vehicle is supplied to both fuel injection valves 5 by a fuel pump 10 via a first supply path 8 and a second supply path 9, and the fuel is opened. It is injected in a bifurcated shape toward each communication hole 6 when the valve is opened. Here, since the fuel injection valve 5 is positioned equidistant from the intake branch pipes 3 on both sides, the injected fuel is supplied into the intake branch pipe 3 through the communication hole 6 under the same conditions. The fuel supply pressure to the fuel injection valve 5 is adjusted to a predetermined value by the regulator 11, and the surplus fuel is recovered in the fuel tank 7 through the recovery passage 12.

An electronic control unit (hereinafter simply referred to as "ECU") 2 for controlling fuel injection and ignition timing of the internal combustion engine 1
An air flow meter 22 for detecting an intake air amount Qa in the intake passage 2 and a rotation speed sensor 24 for detecting an engine rotation speed Ne provided in a distributor 23 of the internal combustion engine 1 are connected to the engine 1. The detection signal is ECU2
Input to 1. Further, both fuel injection valves 5 are connected to the ECU 21, and the fuel injection valve 5 is drive-controlled by a drive signal output from the ECU 21.

Next, an outline of fuel injection control by the fuel injection control device for the internal combustion engine of this embodiment will be described.

FIG. 3 is an explanatory view showing the transition of the fuel distribution ratio among the cylinders of the fuel injection control device for the internal combustion engine according to the first embodiment of the present invention, and FIG. 4 is the internal combustion engine according to the first embodiment of the present invention. 3 is a time chart showing a fuel injection state of the fuel injection control device of FIG.

First, when fuel is injected and supplied from the fuel injection valve 5 common to a pair of cylinders as in this embodiment, the fuel distribution ratio to both cylinders (when the fuel injection amount is 100%, How the ratio of the fuel supplied to each cylinder) changes will be described. This fuel distribution ratio is basically determined according to the ratio of the negative pressures in the intake branch pipes 3 of both cylinders (it varies depending on the stroke during which both cylinders are executing), and a larger amount is assigned to the side where the negative pressures are large. Fuel is supplied. FIG. 3 shows the transition of the fuel distribution ratio between # 1 and # 2. When any cylinder is in the intake stroke, the negative pressure in the intake branch pipe 3 on that side increases, so that the fuel distribution ratio changes. A large difference occurs (for example, 90% of the total injection amount is distributed to the cylinder on the intake stroke side, and the remaining 10% is distributed to the cylinder on the exhaust stroke or compression stroke side). During a stroke other than the intake stroke, the negative pressure in the intake branch pipe 3 approaches evenly and the difference in fuel distribution ratio is reduced (for example,
50% is distributed to both cylinders). Note that # 3 and # 4
The fuel distribution ratio also changes in the same way.

Here, in the present embodiment, when one of the paired cylinders is in the intake stroke and the difference in the fuel distribution ratio is the maximum (crank angle a ° CA and crank angle b ° shown in FIG. 3). CA), fuel injection to those cylinders is performed. That is, the fuel injection to each cylinder is executed twice, that is, when the cylinder is in the intake stroke and when the other cylinder is in the intake stroke. Is defined as main injection (indicated by M in FIG. 4), and a small amount of fuel injection to cylinders in other strokes is defined as preliminary injection (indicated by S in FIG. 4). So, for example, #
For 1, the main injection in the intake stroke is executed after the preliminary injection in the exhaust stroke as shown in FIG. 4, and the injected fuel is burned in the subsequent expansion stroke, and for # 2, in the compression stroke. The main injection in the intake stroke is performed after the pre-injection of 1, and the injected fuel is burned in the subsequent expansion stroke.

Then, the fuel injection amount for each cylinder is determined in consideration of the fuel amount already supplied by the preliminary injection when the cylinder executes the main injection. In other words, the other pair of cylinders performs the preliminary injection during the main injection, so it can be said that the fuel injection amount is always determined by giving priority to the main injection cylinder over the preliminary injection cylinder.

The method of calculating the fuel injection amount will be described below by taking the cylinders # 1 and # 2 as an example.

Now, the crank angle a ° C shown in FIG. 3 and FIG.
It is assumed that the fuel injection amount at the time point A (a larger amount of fuel is supplied to the cylinder of # 2 by main injection) is calculated, and the fuel distribution ratio at this time is # 1: # 2 = a1n: a2n, main injection A2n is the fuel demand amount of the # 2 cylinder that executes the fuel injection, and the fuel distribution ratio at the time of the previous injection of the crank angle b '° CA is # 1: # 2 =
a1'n-1: a2'n-1, the fuel injection amount at the previous injection is x1n-
Assuming 1, the current fuel injection amount x2n is

[0025]

[Equation 1]

It can be represented by In the first half of the right side, the fuel demand amount A2n
Fuel quantity that can be satisfied by one injection, the latter half of the right side is
The amount of fuel already supplied as preliminary injection to the cylinder # 2 during the previous injection (crank angle b '° CA) is shown. Therefore, if the actual injection amount of the fuel injection valve is controlled to this value x2n, it is possible to supply an appropriate amount of fuel that can satisfy the fuel demand amount A2n of the cylinder # 2.

Further, the crank angle b ° shown in FIGS. 3 and 4 is obtained.
It is assumed that the fuel injection amount at the time point of CA (the cylinder of # 1 is supplied with a larger amount of fuel in the main injection) and the fuel distribution ratio at this time is # 1: # 2 = a1′n: a2 ′. Assuming that the fuel demand amount of the # 1 cylinder that executes the main injection is A1n, the current fuel injection amount x1n is

[0028]

[Equation 2]

It can be represented by The first half of the right-hand side is the required fuel amount A1n based on the current fuel distribution ratio.
Fuel quantity that can be satisfied by one injection, the latter half of the right side is
The amount of fuel already supplied as preliminary injection to the cylinder # 1 at the time of the previous injection (crank angle a ° CA) is shown. Therefore,
By controlling the actual injection amount of the fuel injection valve to this value x1n, it is possible to supply an appropriate fuel amount that can satisfy the fuel demand amount A1n of the cylinder # 1.

In this way, the # 1 and # 2 cylinders alternately repeat the preliminary injection and the main injection, and at the time of each main injection, the fuel injection amount is determined prior to the other cylinder, and the fuel demand amount A1n, A2n is satisfied. In addition, details are not explained, but #
The fuel injection amount is calculated in the completely same procedure for the 3rd and 4th cylinders.

By the way, as described above, each cylinder is controlled so as to satisfy the final required fuel amount A1n, A2n by adjusting the fuel injection amount at the time of main injection. When the intake air amount is momentarily reduced due to closing or the like, the fuel demand amounts A1n and A2n may be drastically reduced and become less than or equal to the fuel amount supplied in the preliminary injection.
That is, at this time, the required fuel amounts A1n and A2n have already been satisfied at the time of the preliminary injection, so that if the main injection is subsequently performed, the fuel injection amount becomes excessive. Therefore, at the time of the crank angle a ° CA described above,

[0032]

[Equation 3]

When the relationship is established, or when the crank angle is b ° CA,

[0034]

[Equation 4]

When the relation of (1) is established, it is considered that the required fuel amount A1n, A2n has already been satisfied, and the fuel injection at that time is stopped (x1n = 0, x2n = 0), and the excess amount is exceeded. Of the air-fuel ratio to the rich side due to various fuel injection amounts.

On the other hand, as described above, the required fuel amount A1n, A2
Although n does not fall below the amount of fuel that has been supplied in the preliminary injection, when the main injection is executed next, the fuel injection amount x1n, x2
Even if n is limited to the minimum injection amount xmin of the fuel injection valve 5, the required fuel amount A1n, A2n may be exceeded and the fuel injection amount may become excessive. Therefore, the above crank angle a ° C
At the time of A,

[0037]

[Equation 5]

When the relationship is established, or when the crank angle is b ° CA,

[0039]

[Equation 6]

When the relation of (2) is established, it is considered that the required fuel amount A1n, A2n will be exceeded if the main injection is executed, and the fuel injection timing is set to the crank angle a ° CA or the crank angle b.
° Correct from CA. The first half of the right side of the equations 5 and 6 is the fuel amount supplied to the cylinders # 2 and # 1 when the fuel injection amount x2n, x1n is the minimum injection amount xmin, and the second half of the right side is Indicates the amount of fuel that has already been supplied as preliminary injection to the cylinders # 2 and # 1 during the previous injection.

That is, as shown in FIG. 3, the fuel injection timing before correction is set so that the difference between the fuel distribution ratios to both cylinders is maximized. The difference in distribution ratio can be reduced to reduce the amount of fuel supplied to the main injection cylinder. As a result, the fuel demands A1n and A2n of the main injection cylinders are satisfied to prevent the air-fuel ratio from being disturbed to the rich side due to an excessive fuel injection amount. The correction processing of the fuel injection timing at this time is performed by the fuel distribution ratios a1n: a2n, when the left side and the right side of Equations 5 and 6 are equal.
a1'n: a2'n is calculated, and the fuel distribution rate a1n: a2
The fuel injection timing at which n, a1'n: a2'n is realized is obtained from a map (not shown) and executed.

Next, an EC for executing the above fuel injection control
The processing of U21 will be described.

FIG. 5 is a flow chart showing a fuel injection control routine executed by the ECU of the fuel injection control device for the internal combustion engine according to the first embodiment of the present invention.

The routine shown in the figure is executed every predetermined crank angle. Now, assuming that it is just before the crank angle a ° CA at which the main injection into the cylinder # 2 is performed, the ECU 21 first calculates the required fuel amount A2n for the cylinder # 2 in step S1. This calculation process is similar to that of the general fuel injection control, and is performed based on the intake air amount Qa detected by the air flow meter 22, the engine speed Ne detected by the speed sensor 24, and the like. Next, in step S2, the fuel injection timing a ° CA at which the difference between the fuel distribution ratios of the cylinders # 2 and # 1 is maximized, and the fuel distribution ratios a1n: a2n at that time are obtained from a map not shown. That is, the characteristic of the fuel distribution ratio shown in FIG. 3 changes according to the operating state of the internal combustion engine 1. Therefore, for example, based on the engine speed Ne, the intake negative pressure detected by an intake pressure sensor (not shown), etc. Optimal fuel injection timing a ° CA in operating condition
And the fuel distribution ratio a1n: a2n.

Then, in step S3, the crank angle b '°
At the time of the preliminary injection of CA, it is judged whether or not the fuel demand amount A2n has already been satisfied (whether or not the relationship of Formula 3 is established), and when the fuel demand amount A2n is not yet satisfied, the main injection It is determined that there is room for performing the process, and the process proceeds to step S4. Further, in step S4, it is determined whether or not the fuel demand amount A2n will be exceeded when the main injection to the # 2 cylinder is executed (whether or not the relationship of Formula 5 is established), and the fuel demand amount A2n will be exceeded. When it is estimated that the fuel injection timing a ° CA does not need to be corrected, the process proceeds to step S5.

Then, in step S5, the step S
The fuel injection amount x2n at the crank angle a ° CA is calculated according to the equation 1 based on the required fuel amount A2n obtained in step 1 and the fuel distribution ratio a1n: a2n obtained in step S2.
Next, at step S6, when the fuel injection timing a ° CA obtained at step S2 is reached, fuel injection is performed with the fuel injection amount x2n, and this routine is ended.

If the required fuel amount A2n is already satisfied in step S3, the process proceeds to step S7, and the fuel injection is stopped to prevent the fuel injection amount from becoming excessive.

On the other hand, in step S4, the required fuel amount A2
When it is estimated that the value exceeds n, the process proceeds to step S8, the fuel injection timing a ° CA is corrected to reduce the amount of fuel supplied to the cylinder # 2, and the corrected fuel injection timing is reached in step S6. At this time, the fuel injection amount x2n is set to the minimum injection amount xmin of the fuel injection valve 5, and then the fuel injection is executed.

As described above, in this embodiment, the fuel injection valve 5 functions as the fuel injection means M1 and the ECU 21 when the processing of step S6 is executed as the drive control means M2.
However, the ECU 21 functions as the injection amount calculation means M3 when executing the process of step S5.

As described above, the fuel injection control device for the internal combustion engine according to the present embodiment has the cylinders # 1 and # 2 of the internal combustion engine 1 or # 3.
And the fuel injection valve 5 communicating with the inside of the intake branch pipe 3 of the # 4 cylinder to simultaneously inject and supply fuel to each cylinder, and the fuel injection valve 5 is drive-controlled so that the fuel is injected in the intake stroke of each cylinder. The amount of fuel that has already been supplied as a preliminary injection to satisfy the fuel requirement of the cylinder that performs main injection in the intake stroke based on the fuel distribution ratio while performing fuel injection at the time when the difference in distribution ratio is maximum. The ECU 21 for calculating the fuel injection amount of the fuel injection valve 5 is added. This corresponds to the embodiment of the invention of claim 1.

Therefore, when each cylinder executes the main injection, a fuel injection amount that satisfies the required fuel amount is calculated and injected by the fuel injection valve 5. Therefore, it is possible to supply an appropriate amount of fuel to each cylinder according to the required fuel amount, and thus to accurately control the air-fuel ratio.

Moreover, most of the required fuel amount (for example, 90%) is supplied to each cylinder by the main injection in the intake stroke, and the mode of fuel supply is independent injection in which the fuel injection is concentrated in the intake stroke. Very close. Therefore, the accuracy of the injection amount control can be improved to the level of independent injection.

<Second Embodiment> A fuel injection control apparatus for an internal combustion engine according to a second embodiment of the present invention will be described below. The configuration of the fuel injection control device of this embodiment is shown in FIG.
Is the same as that of the first embodiment shown in FIG.
21 is in the fuel injection control executed. Therefore, the difference will be mainly described.

FIG. 6 is a time chart showing a fuel injection state of a fuel injection control device for an internal combustion engine which is a second embodiment of the present invention, and FIG. 7 is a fuel injection control device for an internal combustion engine which is a second embodiment of the present invention. FIG. 4 is an explanatory diagram showing a map for calculating the fuel injection timing of

As described with reference to FIG. 3, in the first embodiment, one of the cylinders # 1 or # 2 (cylinder # 3 or # 4) has the largest difference in fuel distribution ratio during the intake stroke. At a certain time, the fuel injection to both cylinders was executed twice in total, but in the present embodiment, when the difference in fuel distribution ratio is almost 0 (both fuel distribution ratio to both cylinders is 50%). Fuel injection is concentrated and executed once. It should be noted that the crank angle satisfying the condition of the fuel distribution ratio is 2 degrees of c ° CA and d ° CA shown in FIG.
As for the crank angle d ° CA, it is 720 ° C. before the injected fuel is burned in the expansion stroke because the crank valve is immediately after the intake valve of the cylinder # 2 is closed.
A or more is required, which is not preferable in terms of responsiveness. Therefore, in this embodiment, fuel injection is executed at the crank angle c ° CA.

That is, as shown in FIG. 6, the fuel injection into the cylinders # 1 and # 2 (indicated by I in FIG. 6) is performed at the compression top dead center of the cylinder # 1 (hereinafter simply referred to as "TDC"). ), And fuel injection into the cylinders # 3 and # 4 (also indicated by I in FIG. 6) is performed near TDC of the cylinder # 4. In addition,
As described in the first embodiment, since the characteristic of the fuel distribution ratio changes according to the operating state of the internal combustion engine 1, in this embodiment, as shown in FIG. 7, the fuel-fuel distribution according to the engine speed Ne The fuel injection timing at which the rate becomes 50% is sought.

At the time of each fuel injection, the total fuel requirement amount, which is the sum of those fuel requirement amounts (for example, the sum of A1n and A2n in the first embodiment), is satisfied in order to satisfy the fuel demand amounts of the corresponding cylinders. Is jetted.

Next, an EC for executing the above fuel injection control
The processing of U21 will be described.

FIG. 8 is a flow chart showing a fuel injection control routine executed by the ECU of the fuel injection control device for the internal combustion engine according to the second embodiment of the present invention.

The routine shown in the figure is executed every predetermined crank angle. Now, assuming that it is just before executing the main injection into the cylinders # 1 and # 2, the ECU 21 first calculates the total fuel demand amount for the cylinders # 1 and # 2 in step S11. Next, in step S12, the fuel injection timing at which the fuel / fuel distribution ratio becomes 50% is calculated according to the map of FIG. 7, and in step S13, the fuel injection of the total fuel demand amount is executed when the fuel injection timing is reached. Exit the routine.

As described above, in the present embodiment, the fuel injection valve 5 functions as the fuel injection means M1 and the ECU 21 when the process of step S13 is executed as the drive control means M2.
However, the ECU 21 functions as the injection amount calculation means M3 when executing the process of step S11.

As described above, the fuel injection control device for the internal combustion engine according to the present embodiment has the cylinders # 1 and # 2 of the internal combustion engine 1 or # 3.
And the fuel injection valve 5 communicating with the intake branch pipe 3 of the # 4 cylinder to inject and supply fuel to each cylinder at the same time, and the fuel injection valve 5 is drive-controlled to distribute the fuel to each cylinder. The ECU 21 is configured to execute the fuel injection of the total required fuel amount of each cylinder at the substantially same time. This corresponds to the embodiment of the invention of claim 2.

Therefore, the fuel of the total required fuel amount injected by the fuel injection valve 5 is divided and supplied to each cylinder substantially evenly. Therefore, it is possible to supply an appropriate amount of fuel to each cylinder according to the required fuel amount, and thus to accurately control the air-fuel ratio.

Moreover, since the fuel injection to each cylinder is performed in a stroke other than the intake stroke, the accuracy of the injection quantity control is inferior to that of the first embodiment, but only the sum of the fuel demands of each cylinder is obtained. Since the fuel injection amount can be calculated very easily with, the number of words in the program of the ECU 21 can be greatly reduced and the manufacturing cost can be reduced as compared with the first embodiment in which the fuel injection amount is calculated according to the equations 1 and 2. it can.

<Third Embodiment> A fuel injection control device for an internal combustion engine according to a third embodiment of the present invention will be described below. The configuration of the fuel injection control device of this embodiment is shown in FIG.
Is the same as that of the first embodiment shown in FIG.
21 is in the fuel injection control executed. Therefore, the difference will be mainly described.

FIG. 9 is an explanatory view showing the switching state of the fuel injection control of the fuel injection control device for the internal combustion engine which is the third embodiment of the present invention, and FIG. 10 is the fuel for the internal combustion engine which is the third embodiment of the present invention. It is a flow chart which shows a control change routine which ECU of an injection control device performs.

For convenience of explanation, control for executing fuel injection to both cylinders during the intake stroke described in the first embodiment (see FIG. 5)
Is defined as unequal injection control, and the control (routine shown in FIG. 8) that executes fuel injection when the fuel distribution ratio to both cylinders is 50% described in the second embodiment is uniform injection control. In this embodiment, the non-uniform injection control is executed in the low and middle engine speed range, and the uniform injection control is executed in the high engine speed range.

That is, as described in the first embodiment, in the uneven injection control, the fuel injection is executed in the intake stroke of both cylinders (# 1 and # 2 or # 3 and # 4 cylinders). When the internal combustion engine is in the operating state of high rotation and high load, the intake stroke period is shortened although the injection pulse of the fuel injection valve 5 requires a certain length. It is possible that the injection pulses in the intake stroke of the above overlap each other and the respective fuel requirements are not satisfied. On the other hand, in the uniform injection control in which the fuel injection into both cylinders is concentrated once, such a situation does not occur even at high rotation and high load. Therefore, the lower limit rotational speed at which overlapping of the injection pulses is expected when the non-uniform injection control is executed is set to the high speed setting rotation speed NHI, and as shown in FIG. 9, the engine speed Ne is set to the high speed setting rotation speed. When NHI is exceeded, the control shifts from non-uniform injection control to uniform injection control, and when the engine speed Ne falls below the low-range set speed NLO, which is set to be somewhat lower than the high-range set speed NHI, it again becomes unbalanced. Control is performed so as to shift to uniform injection control.

The processing of the ECU 21 will be described below.
The CU 21 executes the routine shown in FIG. 10 for each predetermined crank angle, and first determines in step S21 whether or not the control switching flag F is set. The control switching flag F represents the type of fuel injection control to be executed,
Clear indicates execution of non-uniform injection control, and set indicates execution of uniform injection control, which are cleared when the ECU 21 is started. Therefore, the ECU 21 proceeds from step S21 to step S22 to determine whether or not the engine speed Ne exceeds the high range set speed NHI, and the high range set speed N is determined.
If HI is exceeded, the control switching flag F is set in step S23, and this routine ends. After that, when the process of step S21 is executed, it is determined that the control switching flag F is set and the process proceeds to step S24.
It is determined whether the engine speed Ne is lower than the low-range set speed NLO. When the engine speed Ne falls below the low-range set speed NLO, the control switching flag F is cleared in step S25, and this routine ends.

As described above, the control switching flag F is set, and when the flag F is cleared, the non-uniform injection control is executed according to the routine of FIG. 5, and when it is set, the uniform injection control is executed according to the routine of FIG. Control is executed. As described above, the rotation speed NHI for switching to the uniform injection control and the rotation speed NLO for switching to the non-uniform injection control.
Is to prevent continuous switching near the boundary between both injection controls.

As described above, in the present embodiment, the fuel injection valve 5 functions as the fuel injection means, and the ECU 21 when executing the process of step S6 as the first drive control means,
The ECU 21 when executing the process of step S5 as the first injection amount calculating means, the ECU 21 when executing the process of step S13 as the second drive control means, and the ECU 21 when executing the process of step S11 as the second injection amount calculating means The EC when the ECU 21 when executing the processing executes the processing of steps S21 to S25 as the control switching means.
U21 works respectively.

As described above, the fuel injection control device for the internal combustion engine of the present embodiment executes the non-uniform injection control in the low and medium speed range of the internal combustion engine and the uniform injection control in the high speed range. This corresponds to the third embodiment of the invention.

Therefore, when the non-uniform injection control is executed, the injection amount is switched to the uniform injection control in a high rotation range where the fuel injection amount may be insufficient, and an appropriate amount of fuel is supplied in accordance with the fuel demand amount. The air-fuel ratio control can be controlled more accurately as compared with the fuel injection control device of the first embodiment that performs the uneven injection control in the range.

By the way, in the first to third embodiments, the fuel injection control device for the four-cylinder internal combustion engine 1 is embodied, and the fuel injection valve 5 is shared for every two cylinders. When the present invention is carried out, the present invention is not limited to this. The point is that an internal combustion engine having two or more cylinders is targeted and fuel is injected and supplied from a common fuel injection valve to the plurality of cylinders. If Therefore, for example, an internal combustion engine with five or more cylinders is targeted, or fuel is injected from a common fuel injection valve to three or four cylinders.
It may be configured to supply.

Further, in the first embodiment, the fuel injection is executed when the difference between the fuel distribution ratios to both cylinders is maximum, and in the second embodiment, the fuel distribution ratios to both cylinders are both 50%. Although the fuel injection was executed at this time, the fuel injection timing is not necessarily limited to these fuel injection timings, and if the control is performed in the vicinity thereof, the operation described in each of the embodiments can be performed to satisfy the fuel demand amount. it can.

[0076]

As described above, according to the fuel injection control device for the internal combustion engine of the first aspect, while each cylinder is performing the intake stroke, the fuel is already supplied along with the intake stroke of the other cylinder. In consideration of the fuel amount, based on the fuel distribution ratio to each cylinder, a fuel injection amount that is sufficient to satisfy the fuel demand amount of the cylinder in the intake stroke is injected. Therefore, it is possible to supply an appropriate amount of fuel to each cylinder according to the required fuel amount, and thus to accurately control the air-fuel ratio. Moreover, since most of the required fuel amount is supplied to each cylinder during the intake stroke, the accuracy of injection amount control can be improved to the level of independent injection.

According to the fuel injection control device for the internal combustion engine of the second aspect, the fuel of the total fuel demand amount injected by the fuel injection means is supplied to the respective cylinders in a substantially evenly divided manner. On the other hand, it is possible to supply an appropriate amount of fuel according to the required fuel amount, and thus to accurately control the air-fuel ratio. Moreover, since the fuel injection amount can be easily calculated only by obtaining the sum of the required fuel amount of each cylinder, the number of words in the control system program can be significantly reduced, and the manufacturing cost can be reduced.

According to the fuel injection control device for the internal combustion engine of the third aspect, when the internal combustion engine has a predetermined rotational speed or higher, the control by the first drive control means and the first injection amount calculation means is changed to the second drive control. Since the control is switched to the control by the means and the second injection amount calculation means, an appropriate amount of fuel is supplied in accordance with the required fuel amount even in the high rotation speed range, and the air-fuel ratio control can be controlled more accurately.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram conceptually showing the contents of a fuel injection control device for an internal combustion engine according to first and second embodiments of the present invention.

FIG. 2 is an overall configuration diagram showing a fuel injection control device for an internal combustion engine that is a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a transition of a fuel distribution ratio among cylinders of a fuel injection control device for an internal combustion engine which is a first embodiment of the present invention.

FIG. 4 is a time chart showing a fuel injection state of the fuel injection control device for the internal combustion engine according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a fuel injection control routine executed by the ECU of the fuel injection control device for the internal combustion engine according to the first embodiment of the present invention.

FIG. 6 is a time chart showing a fuel injection state of a fuel injection control device for an internal combustion engine which is a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a map for calculating a fuel injection timing of a fuel injection control device for an internal combustion engine which is a second embodiment of the present invention.

FIG. 8 is a flowchart showing a fuel injection control routine executed by the ECU of the fuel injection control device for the internal combustion engine according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a switching state of fuel injection control of a fuel injection control device for an internal combustion engine which is a third embodiment of the present invention.

FIG. 10 is a flowchart showing a control switching routine executed by the ECU of the fuel injection control device for the internal combustion engine according to the third embodiment of the present invention.

[Explanation of symbols]

 M1 fuel injection means M2 drive control means M3 fuel injection amount calculation means 1 internal combustion engine 5 fuel injection valve 21 ECU

Claims (3)

[Claims] 1. A fuel injection unit that communicates with a plurality of cylinders of an internal combustion engine and injects and supplies fuel to each cylinder at the same time; and a drive control of the fuel injection unit so that fuel is injected in each intake stroke of each cylinder. Based on the fuel distribution ratio to each cylinder at the time of the fuel injection, in order to satisfy the fuel requirement of the cylinder that is performing the intake stroke, the supply control means that has already been supplied along with the intake stroke of the other cylinders. A fuel injection control device for an internal combustion engine, comprising: an injection amount calculation means for calculating a fuel injection amount of the fuel injection means in consideration of a fuel amount. 2. A fuel injection unit that communicates with a plurality of cylinders of an internal combustion engine and injects and supplies fuel to each cylinder at the same time; and by drivingly controlling the fuel injection unit, a fuel distribution ratio to each of the cylinders is substantially equalized. Drive control means for executing fuel injection at the same time; and injection amount calculation means for calculating a total fuel demand amount of each cylinder and setting it as a fuel injection amount of the fuel injection means. Fuel injection control device for internal combustion engine. 3. A fuel injection unit that communicates with a plurality of cylinders of an internal combustion engine and injects and supplies fuel to each cylinder at the same time; and a drive control of the fuel injection unit so that fuel is injected in each intake stroke of each cylinder. Based on the fuel distribution ratio to each cylinder at the time of fuel injection, the first drive control means for executing the First injection amount calculation means for calculating the fuel injection amount of the fuel injection means in consideration of the supplied fuel amount, and drive control of the fuel injection means so that the fuel distribution rate to each cylinder is substantially equal. Second drive control means for executing fuel injection at a certain time; second injection amount calculation means for calculating a total fuel requirement amount of each cylinder and setting it as a fuel injection amount of the fuel injection means; When the engine speed is below the specified speed , The first drive control means and the first injection amount calculation means are caused to execute fuel injection control, and when the internal combustion engine has a predetermined rotation speed or more, the second drive control means and the second injection amount calculation means A fuel injection control device for an internal combustion engine, comprising: a control switching unit that executes fuel injection control.