JPH10169489A - Fuel injection controller for stratified combustion internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an optimal amount of fuel for combustion when fuel injection is performed by a second fuel injection valve in a fuel injection controller including a first fuel injection valve for performing stratified combustion and the second fuel injection valve provided in its upstream side. SOLUTION: A main fuel injection valve 11 is disposed in the inner wall circumference of a cylinder head 4 located in the vicinity of the first and second intake valves 6a and 6b of an engine 1, and fuel from the main fuel injection valve 11 is directly injected into a cylinder 1a. One auxiliary fuel injection valve 56 for uniformly injecting fuel is provided in a surge tank 16. An electronic controller (ECU) 30 executes, when the engine 1 is in a high load state, fuel injection not only from the main fuel injection valve 11 but also from the auxiliary fuel injection valve 56. In this case, the amount and time of fuel injection from the auxiliary fuel injection valve 56 are set according to each engine speed.

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 system for a stratified combustion internal combustion engine, and more particularly, to a first fuel injection valve for supplying fuel into a cylinder of an internal combustion engine to enable stratified combustion. And a second fuel injection valve provided in an intake passage on the upstream side of the fuel injection control device.

[0002]

2. Description of the Related Art In a conventionally used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance. In such an engine, an intake passage is opened and closed by a throttle valve linked to an accelerator operation, and by this opening and closing, the amount of intake air supplied to a combustion chamber of the engine (consequently, a gas mixture in which fuel and air are homogeneously mixed). ) Is adjusted, thereby controlling the engine output.

[0003] However, in the technique based on the so-called homogeneous combustion described above, a large intake negative pressure is generated in accordance with the throttle operation of the throttle valve, and the pumping loss increases to lower the efficiency. On the other hand, by reducing the throttle of the throttle valve and supplying fuel directly to the combustion chamber, a combustible mixture is present near the ignition plug, and the air-fuel ratio of the portion is increased,
There is known a so-called "stratified combustion" technique for improving ignitability. In this technology, when the engine is under a low load, the injected fuel is unevenly supplied around the spark plug, and the throttle valve is opened almost fully to perform stratified combustion. Thereby, the pumping loss is reduced, and the fuel efficiency is improved.

As a technique capable of performing stratified combustion as described above, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 4-237854 is known. This technology has a first fuel injection valve arranged in a cylinder of an engine and a second fuel injection valve arranged in an intake pipe, and switches fuel injection according to a load of an internal combustion engine. ing. That is, when the load is low, fuel injection is performed in the compression stroke by the first fuel injection valve, and stratified combustion is executed. When the load is high, fuel injection is performed by the second fuel injection valve to execute homogeneous combustion.

[0005] When fuel injection by the second fuel injection valve is started, fuel injection from the first fuel injection valve in the intake stroke is also performed. By performing such control, the fluctuation of the amount of fuel flowing into the cylinder is suppressed, and the fluctuation of the combustion is reduced.

[0006]

However, in the above-mentioned prior art, the following problems may occur. That is, when the second fuel injection valve is provided relatively upstream of the intake pipe such as a surge tank, the fuel distribution to each cylinder is uneven when performing the intake pipe injection by the second fuel injection valve. Or delay of fuel flow into each combustion chamber, etc.
There was a possibility that sufficient fuel (fuel injection amount, fuel injection timing) could not be secured.

The present invention has been made in view of the above circumstances, and has as its object to provide a first fuel injection valve for supplying fuel into a cylinder of an internal combustion engine to enable stratified combustion,
In a fuel injection control device for a stratified combustion internal combustion engine including a second fuel injection valve provided in an intake passage on an upstream side of the fuel injection valve, when performing fuel injection by the second fuel injection valve, it is optimal for combustion. It is an object of the present invention to provide a fuel injection control device for a stratified combustion internal combustion engine that can secure a suitable fuel.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, as shown in FIG. 1, fuel is injected into a cylinder of an internal combustion engine M1 to enable stratified combustion. A first fuel injection valve M2 to be supplied, and an upstream side of the first fuel injection valve M2,
A second fuel injection valve M4 provided in the intake passage M3 of
Operating state detecting means M5 for detecting an operating state of the internal combustion engine M1 including at least a load; and when the detection result of the operating state detecting means M5 is at least a low load, the fuel from the first fuel injection valve M2 is The fuel injection from the second fuel injection valve M4 is executed when the detection result of the first fuel injection valve control means M6 for executing and controlling the injection and the operation state detection means M5 is at least a high load. And a second fuel injection valve control means M7 for controlling the fuel injection control of the stratified combustion internal combustion engine.
Intake air state detecting means M8 for detecting the intake air state of the vehicle
And when the second fuel injection valve control means M7 executes fuel injection from the second fuel injection valve M4,
The gist of the invention is to provide an injection amount calculation determining means M9 for calculating and determining the fuel injection amount from the second fuel injection valve M4 based on the detection result of the intake air state detecting means M8.

According to the second aspect of the present invention, as shown in FIG. 1, the first fuel injection valve M2 for supplying fuel into the cylinder of the internal combustion engine M1 so as to enable stratified combustion, A second fuel injection valve M4 provided upstream of the first fuel injection valve M2 in the intake passage M3 of the internal combustion engine M1 and an operation for detecting an operation state of the internal combustion engine M1 including at least a load; State detection means M5 and first fuel injection valve control means M6 for executing and controlling fuel injection from the first fuel injection valve M2 when the detection result of the operation state detection means M5 is at least a low load. And second fuel injection valve control means M7 for executing and controlling the fuel injection from the second fuel injection valve M4 when the detection result of the operation state detection means M5 is at least a high load. Stratified combustion internal combustion engine In fuel injection control device, the intake air state detector M8 for detecting an intake air condition of the internal combustion engine M1, by the second fuel injection valve control means M7,
When performing the fuel injection from the second fuel injection valve M4, the injection for calculating and determining the fuel injection timing from the second fuel injection valve M4 based on the detection result of the intake air state detection means M8. The point is that the timing calculation determining means M10 is provided.

Further, according to a third aspect of the present invention, in the fuel injection control device for a stratified combustion internal combustion engine according to the first or second aspect, the intake air state includes a rotation speed of the internal combustion engine M1, an intake air flow rate. And at least one of the strength of the vortex of the fuel mixture.

According to a fourth aspect of the present invention, in the fuel injection control apparatus for a stratified combustion internal combustion engine according to any one of the first to third aspects, the internal combustion engine M1 has a plurality of cylinders. At the same time, when the first fuel injection valve control means M6 executes the fuel injection from the first fuel injection valve M2, the first fuel injection valve is controlled so that the combustion in each cylinder is optimized. The gist is to correct the fuel injection amount from M2.

According to a fifth aspect of the present invention, in the fuel injection control apparatus for a stratified combustion internal combustion engine according to the fourth aspect, the correction of the fuel injection amount from the first fuel injection valve M2 is performed by the correction of the fuel injection amount. The gist is that the detection is performed based on the detection result of the intake air state detection means M8.

According to a sixth aspect of the present invention, in the fuel injection control apparatus for a stratified combustion internal combustion engine according to any one of the first to fifth aspects, the first fuel injection valve M2 is connected to the internal combustion engine M1. The gist is to inject fuel directly into the cylinder.

(Operation) According to the first aspect of the present invention, as shown in FIG. 1, the first fuel injection valve M2
Fuel is supplied into the cylinder of the internal combustion engine M1, whereby stratified combustion can be performed. Further, the fuel is uniformly supplied to the cylinder of the internal combustion engine M1 by the second fuel injection valve M4 provided in the intake passage M3 of the internal combustion engine M1 on the upstream side of the first fuel injection valve M2. sell. Further, the operating state detecting means M5 detects the internal combustion engine M1 including at least the load.
Is detected, and when the detection result is at least a low load, the fuel injection from the first fuel injection valve M2 is executed by the first fuel injection valve control means M6,
Controlled. At the same time, when the detection result of the operating state detecting means M5 is at least a high load, the fuel injection from the second fuel injection valve M4 is executed and controlled by the second fuel injection valve control means M7.

In the present invention, the intake air condition of the internal combustion engine M1 is detected by the intake air condition detecting means M8. When fuel injection from the second fuel injection valve M4 is executed by the second fuel injection valve control means M7, an injection amount calculation determination means is performed based on the detection result of the intake air state detection means M8. By M9, the fuel injection amount from the second fuel injection valve M4 is calculated and determined.

Therefore, when the fuel injection from the second fuel injection valve M4 is executed, an appropriate homogeneous injection amount according to the intake air condition is secured. According to the second aspect of the invention, when the fuel injection from the second fuel injection valve M4 is executed, the intake air state detection is performed instead of the injection amount according to the first aspect of the invention. The fuel injection timing from the second fuel injection valve M4 is calculated and determined by the injection timing calculation determining means M10 based on the detection result of the means M8.

Therefore, when the fuel injection from the second fuel injection valve M4 is executed, an appropriate homogeneous fuel injection timing according to the intake air condition is secured. Further, according to the third aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, the intake air condition includes the number of revolutions of the internal combustion engine M1, the intake air flow rate, and the fuel mixture. At least one of the vortex intensities. Therefore, the injection amount and the injection timing according to these parameters are secured.

In addition, according to the invention described in claim 4,
In addition to the effects of the inventions described in claims 1 to 3, since the internal combustion engine M1 has a plurality of cylinders, the distribution of fuel between the cylinders may vary. In contrast, in the present invention, the first
The first fuel injection valve M is controlled by the fuel injection valve control means M6.
When the fuel injection from the second fuel injection valve 2 is executed, the amount of fuel injection from the first fuel injection valve M2 is corrected, and control is performed so that combustion in each cylinder is optimized. Therefore, it is possible to suppress occurrence of variation in fuel distribution among the cylinders.

In addition, according to the invention described in claim 5,
In addition to the effect of the invention described in claim 4, the correction of the fuel injection amount from the first fuel injection valve M2 is performed based on the detection result of the intake air state detection means M8. Therefore, variation in fuel distribution is suppressed according to the state of intake air.

According to the sixth aspect of the invention, in addition to the functions of the first to fifth aspects, the fuel from the first fuel injection valve M2 is supplied to the cylinder of the internal combustion engine M1. It is directly injected into. Therefore, the distribution variation is directly suppressed by correcting the fuel directly injected into the cylinder.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a fuel injection control device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a fuel injection control device of a direct injection type engine mounted on a vehicle in the present embodiment. The engine 1 as an internal combustion engine includes, for example, four cylinders 1a, and the combustion chamber structure of each of the cylinders 1a is shown in FIG. As shown in these figures,
The engine 1 includes a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. The cylinder head 4 is located above the cylinder block 2.
Is provided, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged per cylinder 1a, and in the figure, the first intake valve 6a, the second intake valve 6b, the first intake port 7a, and the first intake port 7b in the figure. Two intake ports, a pair of exhaust valves as 8, and a pair of exhaust ports as 9 are shown.

As shown in FIG. 3, the first intake port 7a
Is composed of a helical intake port, and the second intake port 7
b consists of a straight port extending almost straight.
In addition, an ignition plug 10 is disposed at the center of the inner wall surface of the cylinder head 4. Further, a main fuel injection valve 11 as a first fuel injection valve is arranged for each cylinder 1a around the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the main fuel injection valve 11 is directly injected into the cylinder 1a, and the fuel injected from the main fuel injection valve 11 causes stratified combustion. Is performed.

As shown in FIG. 2, the first intake port 7a and the second intake port 7b of each cylinder 1a are respectively connected via a first intake path 15a and a second intake path 15b formed in each intake manifold 15. Connected to the surge tank 16. A swirl control valve 17 is arranged in each second intake passage 15b. These swirl control valves 17 are connected via a common shaft 18 to a step motor 19 as an actuator. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later.

The surge tank 16 includes an intake duct 20
Is connected to the air cleaner 21 through the intake duct 20.
Inside, a throttle valve 23 which is opened and closed by a separate step motor 22 is provided. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type.
By being driven based on the output signal from 30,
The opening and closing of the throttle valve 23 is controlled. By opening and closing the throttle valve 23, the amount of intake air introduced into the combustion chamber 5 through the intake duct 20 is adjusted. In the present embodiment, the intake duct 20, the surge tank 16, the first intake path 15a and the second intake path 1
5b and the like constitute an intake passage. In addition, near the throttle valve 23, its opening (throttle opening T
A throttle sensor 25 for detecting A) is provided. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder. The exhaust gas after combustion is discharged to an exhaust duct (not shown) via the exhaust manifold 14.

Further, in the present embodiment, a known exhaust gas circulation (EGR) device 51 is provided. This EG
The R device 51 includes an EGR passage 5 as an exhaust gas circulation passage.
2 and an EGR valve 53 as an exhaust gas circulation valve provided in the middle of the passage 52. EGR passage 5
2 is an intake duct 20 downstream of the throttle valve 23;
It is provided so as to communicate with the exhaust duct. Further, the EGR valve 53 has a built-in valve seat, valve body, and step motor (all not shown), and these constitute an EGR mechanism. The opening degree of the EGR valve 53 fluctuates when the stepping motor intermittently displaces the valve body with respect to the valve seat. And the EGR valve 5
When the valve 3 opens, a part of the exhaust gas discharged to the exhaust duct flows to the EGR passage 52. The exhaust gas is
It flows to the intake duct 20 via the EGR valve 53. That is, a part of the exhaust gas is recirculated into the intake air-fuel mixture by the EGR device 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

In addition, as shown in FIGS. 2 and 4, in the present embodiment, the surge tank 16 is provided with one auxiliary fuel injection valve 56 as a second fuel injection valve.
The fuel from the auxiliary fuel injection valve 56 is mainly injected into the surge tank 16 at a high load.
Due to the injection, the cylinder 1a (# 1, # 2, # 3,
In 4), a homogeneous fuel is supplied.

The above-described ECU 30 is formed of a digital computer, and is connected to a RAM (random access memory) 3 via a bidirectional bus 31.
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 composed of a microprocessor, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes first fuel injection valve control means, second fuel injection valve control means, injection amount calculation determination means, and injection timing calculation determination means.

An accelerator sensor 26A for generating an output voltage proportional to the amount of depression of the accelerator pedal 24 is connected to the accelerator pedal 24.
Accelerator opening ACCP is detected by 6A. The output voltage of the accelerator sensor 26A is input to the input port 35 via the AD converter 37. Similarly, the accelerator pedal 24 has a fully-closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0".
Is provided. That is, the fully closed switch 26B
Generates a signal of "1" as the fully closed signal when the depression amount of the accelerator pedal 24 is "0", and generates a signal of "0" otherwise. And the fully closed switch 26
The output voltage of B is also input to the input port 35.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has a crankshaft of 30 ° C.
An output pulse is generated every time the A rotation is performed, and the output pulse is input to the input port. The CPU 34 reads the crank angle CCRNK from the output pulse of the crank angle sensor 28. Further, the CPU 34 calculates (reads) the engine speed NE from the output pulse of the top dead center sensor 27 and the output pulse of the crank angle sensor 28.

Further, the rotation angle of the shaft 18 is
The swirl control valve sensor 29 detects the opening degree of the swirl control valve 17. The output of the swirl control valve sensor 29 is input to the input port 35 via the A / D converter 37.

At the same time, the throttle sensor 25 detects the throttle opening degree TA. The output of the throttle sensor 25 is input to an input port 35 via an A / D converter 37.

In addition, in the present embodiment, an intake pressure sensor 61 for detecting the pressure (intake pressure PIM) in the surge tank 16 is provided. Further, a water temperature sensor 62 that detects the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. The output of both sensors 61 and 62 is also A /
The data is input to the input port 35 via the D converter 37.

In the present embodiment, the throttle sensor 25, the accelerator sensor 26A,
B, a top dead center sensor 27, a crank angle sensor 28, a swirl control valve sensor 29, an intake pressure sensor 61, a water temperature sensor 62, and the like constitute an operating state detecting means.

The top dead center sensor 27, the crank angle sensor 28 and the like constitute an intake air state detecting means. On the other hand, the output port 36 is connected to each of the main fuel injectors 11 and each of the step motors 19 and 2 via the corresponding drive circuit 38.
2. Igniter 1 for operating spark plug 10
2. It is connected to the EGR valve 53 (step motor) and the auxiliary fuel injection valve 56. Then, the ECU 30 determines R based on signals from the sensors 25 to 29, 61, and 62.
According to the control program stored in the OM 33, the main fuel injection valve 11, the step motors 19 and 22, the igniter 1
2. The EGR valve 53, the auxiliary fuel injection valve 56 and the like are suitably controlled. In the present embodiment, ignition is performed in the order of # 1, # 3, # 4, and # 2 for each cylinder 1a.

Next, a program related to various controls according to the present embodiment in the fuel injection control device for a stratified combustion engine having the above configuration will be described with reference to a flowchart. That is, FIG. 5 is a flowchart showing a “fuel injection control routine” for controlling the fuel injection amount and the injection timing in the present embodiment. For example, each cylinder 1a is interrupted by a predetermined crank angle.
It is executed every time.

When the processing shifts to this routine, the ECU
First, in step 101, based on the detection results of the crank angle sensor 28, the top dead center sensor 27, and the like,
The current crank angle CCRNK, engine speed NE, and the like are read. Further, the fuel injection amount QALL calculated by a separate routine is read.

Next, in step 102, it is determined whether or not the current load is high based on the fuel injection amount QALL read this time. And if not high load,
Assuming that the fuel injection from the auxiliary fuel injection valve 56 is not performed, the subsequent processing is temporarily terminated. On the other hand, if the load is currently high, it is determined that the fuel injection from the auxiliary fuel injection valve 56 needs to be performed, and the process proceeds to step 103.

In step 103, based on the engine speed NE as the intake air state read this time,
Calculate the auxiliary fuel injection valve injection ratio KSUB (0 ≦ KSU
B ≦ 1). Here, this sub fuel injection valve injection ratio KSUB
In the calculation of, for example, as shown by the solid line in FIG.
A map (mapA) that defines the auxiliary fuel injection valve injection ratio KSUB with respect to the engine speed NE at that time is taken into consideration. In the present embodiment, the reason why a map (mapA) having such characteristics is adopted is that, when the engine speed NE is low, the proportion of fuel from the auxiliary fuel injection valve 56 may be increased. This is because the presence of the swirl control valve 17 (high swirl strength) may cause a decrease in the charging efficiency. Further, when the engine speed NE is extremely high, even if the auxiliary fuel injection valve injection ratio KSUB is increased, it is difficult to introduce the fuel into the cylinder 1a. That is, as shown in FIG. 7, since there is an optimal (most torque-obtainable) auxiliary fuel injection valve injection ratio KSUB corresponding to the current engine speed NE, the value is calculated in step 103. It is.

Then, in the next step 104,
A value obtained by multiplying the currently read fuel injection amount QALL by the currently calculated auxiliary fuel injection valve injection ratio KSUB is set as the auxiliary fuel injector target injection amount QSUB. In this way, by the processing of steps 103 and 104, the optimum auxiliary fuel injector target injection amount QSUB is set according to the engine speed NE at that time.

Although not described in this flowchart, in the present embodiment, the auxiliary fuel injection valve injection ratio KSUB and, consequently, the auxiliary fuel injector target injection amount QS
As shown in FIG. 9, UB is set to the smallest value for the cylinder 1a (# 4) located closest to the auxiliary fuel injection valve 56, and is set to the cylinder 1a located farthest from the auxiliary fuel injection valve 56.
(♯1) is set to the largest value. This is because, as shown in FIG. 4, the fuel from the sub fuel injector 56 is closer to the cylinder 1a (in the order of # 4, # 3, # 2, # 1) closer to the sub fuel injector 56. More easily supplied, each cylinder 1a
This is for the purpose of equalizing the fuel supply amount for each interval.

Further, in step 105, the target injection timing AINJS of the auxiliary fuel injector in the corresponding cylinder 1a.
Is calculated. Here, the auxiliary fuel injection valve target injection timing A
In calculating INJS, for example, as shown in FIG. 8, a map (map) in which the auxiliary fuel injector target injection timing AINJS is determined with respect to the engine speed NE at that time.
B) is taken into account. In the present embodiment, as the engine speed NE increases, the auxiliary fuel injector target injection timing AINJS is advanced.

The target injection timing AINJ of the auxiliary fuel injection valve
S is set for each cylinder 1a, and as shown in FIG. 9, the cylinder 1a (# 4) closest to the auxiliary fuel injection valve 56 is set to the latest timing, The cylinder 1a (# 1) located farthest from the injection valve 56 is set at the earliest time. This is because, as shown in FIG. 4, the cylinder 1a (# 4,
This is because the order of (3, # 2, # 1) is easier to supply the fuel from the auxiliary fuel injection valve 56 earlier, and the fuel supply timing between the cylinders 1a is made uniform.

Next, in step 106, the cylinder 1a to be used for injection from the main fuel injection valve 11 is calculated and determined based on the crank angle CCRNK detected this time.

In the following step 107, an injection amount correction coefficient QALL [i] corresponding to the cylinder 1a calculated in step 106 is calculated. Here, when calculating the injection amount correction coefficient QALL [i], for example, a map (not shown) that defines the injection amount correction coefficient QALL [i] with respect to the engine speed NE at that time is taken into consideration.

Further, in the next step 108, the sub-injection valve target injection amount QSUB is calculated from the fuel injection amount QALL.
Is subtracted from the injection amount correction coefficient QALL
The value obtained by multiplying [i] is set as the main fuel injector target injection amount QMAIN [i] of the corresponding cylinder 1a. As a result, the amount of fuel injection from the main fuel injection valve 11 is optimized. Then, the ECU 30 once ends the subsequent processing.

Next, the operation and effect of this embodiment will be described. (A) In the present embodiment, when the engine 1 is in a high load state, fuel injection from not only the main fuel injection valve 11 but also the auxiliary fuel injection valve 56 is executed. In this case, the fuel injection amount from the auxiliary fuel injection valve 56 (the auxiliary fuel injection valve target injection amount QSUB) is set according to the current engine speed NE. For this reason, it is possible to secure an optimal homogeneous amount of fuel in accordance with the engine speed NE at that time, thereby securing an optimal combustion state and torque.

(B) In the present embodiment, the fuel injection timing from the auxiliary fuel injection valve 56 (the auxiliary fuel injection valve target injection timing AINJS) is set according to the engine speed NE. For this reason, a more optimal homogeneous fuel supply time can be secured, and the combustion state and output performance can be further improved.

(C) Further, in the present embodiment, since a plurality of cylinders 1a are provided, the distribution of fuel among the cylinders 1a may vary. On the other hand, in the present embodiment, the fuel injection amount and the injection timing are set according to each cylinder 1a.

In particular, for the cylinder 1a (# 4) located closest to the auxiliary fuel injection valve 56, the injection amount is smallest,
Further, the injection timing is set to be late, and for the cylinder 1a (# 1) farthest from the auxiliary fuel injection valve 56,
The injection amount is largest and the injection timing is set earlier. Therefore, it is possible to suppress variations in the amount and timing of fuel supply between the cylinders 1a, and as a result, it is possible to further improve the combustion state.

(D) In addition, in the present embodiment, when the fuel injection from the main fuel injection valve 11 is also performed in a high load state, the amount of fuel injection from the main fuel injection valve 11 is also controlled by the engine. The correction is performed based on the rotational speed NE. Therefore, even if the above-described control may cause a variation in the fuel supply between the cylinders 1a, the fuel injection from the main fuel injection valve 11 that can directly inject the fuel into the cylinders 1a. , It is possible to eliminate the variation and secure an appropriate fuel supply. As a result, the combustion in each cylinder 1a can be further optimized.

The present invention is not limited to the above embodiment, and may be configured as follows, for example. (1) In the above embodiment, the target injection timing AINJS of the auxiliary fuel injection valve is calculated for each cylinder 1a.
On the other hand, as shown in FIG. 10, for example, the fuel may be injected once (or twice) every two rotations of the crankshaft. In this case, it is desirable that the injection stop period is adapted to correspond to the cylinder close to the auxiliary fuel injection valve 56. By employing such control, it is possible to sufficiently cope with a case where the fuel demand from the auxiliary fuel injection valve 56 is large, and to simplify the control.

(2) In the above embodiment, both the injection amount and the injection timing of the fuel from the auxiliary fuel injection valve 56 are set based on the engine speed NE. Only the setting may be made. Further, the correction of the fuel injection amount from the main fuel injection valve 11 may be omitted.

(3) In the above embodiment, the engine speed NE is used as the intake air state. However, the intake air flow rate detected by an air flow meter or the like (not shown) or the swirl control valve sensor 2
The state of the intake air may be recognized based on the degree of opening of the swirl control valve detected by the control unit 9.

(4) In the above embodiment, a map (mapA) shown by a solid line in FIG. 6 is adopted, but a map shown by a two-dot chain line in FIG. You may do so.

In the case where the swirl control valve 17 is not provided, a map (dashed line in the figure) having a characteristic that the auxiliary fuel injection valve injection ratio KSUB decreases as the engine speed NE increases. Is also good.

(5) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1. However, the present invention is embodied in a so-called general stratified combustion or weak stratified combustion type. You may. For example, the intake ports 7a, 7b
Of the type which injects toward the back side of the umbrella portion of the intake valves 6a and 6b. Although the main fuel injection valve 11 is provided on the side of the intake valves 6a and 6b, a type that directly injects the fuel into the cylinder bore (combustion chamber 5) is also included.

(6) In the above embodiment, the present invention is embodied in the case of the gasoline engine 1 as the internal combustion engine. However, the present invention can be embodied in the case of a diesel engine or the like.

The technical ideas that are not described in each claim of the claims but can be grasped from the above embodiment will be described below. (A) a first fuel injection valve for supplying fuel into a cylinder of the internal combustion engine to enable stratified combustion, and an upstream side of the first fuel injection valve and an intake passage of the internal combustion engine. In a fuel injection control device for a stratified combustion internal combustion engine provided with a second fuel injection valve provided, a fuel injection time injected from the second fuel injection valve varies depending on an intake air state of the internal combustion engine. Characterized in that:

(B) A first fuel injection valve for supplying fuel into a cylinder of the internal combustion engine so as to enable stratified combustion, and an upstream side of the first fuel injection valve, In a fuel injection control device for a stratified charge combustion internal combustion engine having a second fuel injection valve provided in an intake passage, a fuel injection timing injected from the second fuel injection valve changes an intake air state of the internal combustion engine. It is characterized in that it varies depending on.

(C) In the fuel injection control device for an internal combustion engine according to claim 1, the internal combustion engine has a plurality of cylinders, and the injection amount calculation determining means determines the second fuel injection. It is characterized in that the injection amount is variable depending on the ease with which fuel from the valve is introduced into each cylinder.

With such a configuration, it is possible to suppress variations in fuel distribution among the cylinders, and it is possible to ensure a more excellent combustion state. (D) In the fuel injection control device for an internal combustion engine according to claim 2, the internal combustion engine has a plurality of cylinders, and the injection timing calculation determining means determines whether or not the injection timing is to be calculated from the second fuel injection valve. It is characterized in that the injection timing is made variable depending on the ease with which fuel is introduced into each cylinder.

With such a configuration, it is possible to suppress a variation in fuel distribution among the cylinders, and it is possible to ensure a more excellent combustion state.

[0064]

As described in detail above, according to the present invention,
Stratified combustion including a first fuel injection valve for supplying fuel into a cylinder of an internal combustion engine to enable stratified combustion, and a second fuel injection valve provided in an intake passage upstream of the first fuel injection valve In the fuel injection control device for an internal combustion engine, when performing the fuel injection by the second fuel injection valve, an excellent effect that an optimum fuel for combustion can be ensured can be obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram showing a basic concept of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel injection control device for a stratified combustion engine according to one embodiment.

FIG. 3 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 4 is a schematic diagram showing a positional relationship between an auxiliary fuel injection valve and each cylinder;

FIG. 5 is a flowchart showing a “fuel injection control routine” executed by the ECU.

FIG. 6 is a map showing a relationship between an engine speed and an injection ratio of an auxiliary fuel injection valve.

FIG. 7 is a graph showing a relationship between torque and charging efficiency with respect to an auxiliary fuel injection valve injection ratio at a certain engine speed.

FIG. 8 is a map showing a relationship between an engine speed and a target injection timing of an auxiliary fuel injection valve.

FIG. 9 is a timing chart showing an injection state from an auxiliary fuel injection valve corresponding to each cylinder.

FIG. 10 is a timing chart showing an injection state from an auxiliary fuel injection valve in another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 11 ... Main fuel injection valve as a 1st fuel injection valve, 17 ... Swirl control valve, 25 ... Throttle sensor which comprises operating state detecting means, 26A ... It constitutes operating state detecting means Accelerator sensor, 26B Fully-closed switch constituting operating state detecting means, 27 Top dead center sensor constituting operating state detecting means and intake air state detecting means, 28 constituting operating state detecting means and intake air state detecting means Crank angle sensor,
29: a swirl control valve sensor constituting the operating state detecting means; 30 ... an ECU constituting the first fuel injection valve control means, the second fuel injection valve control means, the injection amount calculation determining means, the injection timing calculation determining means, 56: an auxiliary fuel injection valve as a second fuel injection valve; 61, an intake pressure sensor constituting operating state detecting means; 62, a water temperature sensor constituting operating state detecting means.

Claims (6)

[Claims] 1. A first fuel injection valve for supplying fuel to a cylinder of an internal combustion engine so as to enable stratified combustion, and an upstream side of the first fuel injection valve and an intake air of the internal combustion engine. A second fuel injection valve provided in the passage; operating state detecting means for detecting an operating state of the internal combustion engine including at least a load; and when the result of the operation state detecting means is at least a low load, First fuel injection valve control means for executing and controlling fuel injection from the first fuel injection valve; and when the detection result of the operating state detection means is at least a high load, the second fuel injection valve A fuel injection control device for a stratified combustion internal combustion engine, comprising: a second fuel injection valve control means for executing and controlling the fuel injection of the internal combustion engine; and an intake air state detection means for detecting an intake air state of the internal combustion engine; 2 fuel injection When fuel injection from the second fuel injection valve is executed by the firing valve control means, a fuel injection amount from the second fuel injection valve is calculated based on the detection result of the intake air state detection means. A fuel injection control device for a stratified combustion internal combustion engine, comprising: an injection amount calculation determining means for determining. 2. A first fuel injection valve for supplying fuel into a cylinder of the internal combustion engine to enable stratified combustion, and an upstream side of the first fuel injection valve and an intake air of the internal combustion engine. A second fuel injection valve provided in the passage; operating state detecting means for detecting an operating state of the internal combustion engine including at least a load; and when the result of the operation state detecting means is at least a low load, First fuel injection valve control means for executing and controlling fuel injection from the first fuel injection valve; and when the detection result of the operating state detection means is at least a high load, the second fuel injection valve A fuel injection control device for a stratified combustion internal combustion engine, comprising: a second fuel injection valve control means for executing and controlling the fuel injection of the internal combustion engine; and an intake air state detection means for detecting an intake air state of the internal combustion engine; 2 fuel injection When executing fuel injection from the second fuel injection valve by the injection valve control means, the fuel injection timing from the second fuel injection valve is calculated based on the detection result of the intake air state detection means. A fuel injection control device for a stratified combustion internal combustion engine, comprising: an injection timing calculation determining means for determining. 3. The fuel injection control device for a stratified combustion internal combustion engine according to claim 1, wherein the state of the intake air is a rotation speed of the internal combustion engine, an intake air flow rate, and a strength of a vortex of a fuel mixture. At least one of them
A fuel injection control device for a stratified combustion internal combustion engine. 4. The fuel injection control device for a stratified combustion internal combustion engine according to claim 1, wherein said internal combustion engine has a plurality of cylinders, and said first fuel injection valve control means. Thus, when executing fuel injection from the first fuel injection valve, the fuel injection amount from the first fuel injection valve is corrected so that combustion in each cylinder is optimized. A fuel injection control device for a stratified combustion internal combustion engine. 5. The fuel injection control device for a stratified combustion internal combustion engine according to claim 4, wherein the correction of the fuel injection amount from the first fuel injection valve is performed based on a detection result of the intake air state detection means. A fuel injection control device for a stratified combustion internal combustion engine. 6. The fuel injection control device for a stratified combustion internal combustion engine according to claim 1, wherein the first fuel injection valve injects fuel directly into a cylinder of the internal combustion engine. A fuel injection control device for a stratified combustion internal combustion engine, characterized in that it is a fuel injection control device.