JP2000002131A - Idle speed control device for stratified charge combustion internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the speed of an internal combustion engine which can carry out stratified charge combustion, from temporarily and abruptly increasing, due to idle-up upon application of a load. SOLUTION: Fuel injection valves 11 are located around the peripheral part of the inner wall surface of a cylinder head 4 in the vicinity of a first intake valve 6a and a second intake valve 6b in an engine 1, and fuel from the fuel injection valves 11 is directly injected into a cylinder 1a. A throttle valve 23 adapted to be opened and closed by a step motor 22 is located in an intake air duct 20. An electronic control device (ECU) 30 increases the fuel rate directly fed from the fuel injection valves 11 when a load is applied to the engine in such a case that stratified charge combustion is carried out during idling of the engine 1. At this time, the increase in the fuel quantity is compensated in accordance with a fuel injection rate just before idle-up. Accordingly, it is possible to restrain variation in rotational speed from becoming larger in such a case the fuel injection rate is high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an internal combustion engine capable of performing stratified charge combustion.

[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. 4-370343 is known. In this technology, either a stratified combustion or a homogeneous combustion combustion method is adopted depending on operating conditions,
At least at low and medium loads, stratified fuel injection and ignition are controlled, and at high loads, homogeneous combustion fuel injection and ignition are controlled. When the engine is idling, only the fuel injection amount is controlled to increase or decrease according to the coolant temperature. With such a technique, stratified combustion at low load is favorably maintained, and warm-up during cold is promoted.

[0005]

However, in the technology described in the above-mentioned conventional publication, the following problems may occur. That is, during idling, when a load such as an air conditioner is applied to the engine, idle-up is generally performed to prevent a decrease in the engine speed. Here, in the case of a general engine that performs only homogeneous combustion, idle-up is performed by increasing the intake air amount.

[0006] On the other hand, in the above prior art, when stratified combustion is being performed, the idling up is performed by increasing the fuel injection amount. However, during stratified charge combustion, a change in the amount of fuel greatly affects combustion depending on the amount of fuel injection at the start of idle-up. For example, in the state where the fuel injection amount is large immediately before the start of idle-up, if the fuel amount is increased by the same amount as when the injection amount is small, the engine speed temporarily increases suddenly. Was likely to occur.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an idling speed control apparatus for an internal combustion engine capable of performing stratified combustion, in which the idle-up is performed when a load is applied to the internal combustion engine. By being done,
An object of the present invention is to provide an idling speed control device for a stratified combustion internal combustion engine that can suppress a temporary increase in the engine speed.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, as shown in FIG. 1, fuel is supplied into a cylinder of an internal combustion engine M1 to perform stratified combustion. The internal combustion engine M1 is in an idling state and the combustion state of the internal combustion engine M1 is a stratified charge combustion, and the load is applied to the internal combustion engine M1. Idle speed control of a stratified combustion internal combustion engine, comprising: an idle-up control device M3 for increasing the amount of fuel injected from the fuel injection device M2 to perform idle-up in order to suppress a decrease in the rotation speed of the engine M1. A fuel injection amount recognizing means M for recognizing a fuel injection amount from said fuel injection means M2.
4, an increase correction means M5 for correcting an increase in the fuel amount by the idle-up control means M3 according to the recognition result of the fuel injection amount recognition means M4 at the time when the idle-up control means M3 performs the idle-up. The main point is that it has been established.

According to a second aspect of the present invention, in the idle speed control device for a stratified combustion internal combustion engine according to the first aspect, the fuel amount increased by the idle-up control means M3 is an expected amount. Is the gist.

Further, according to the third aspect of the present invention, in the idle speed control device for a stratified combustion internal combustion engine according to the first or second aspect, the fuel injection amount recognizing means M4 at the time of performing the idle-up is provided. The gist is that when the recognized fuel injection amount is large, the degree of increase in the fuel amount is smaller than when the fuel injection amount is small.

According to a fourth aspect of the present invention, in the idle speed control apparatus for a stratified combustion internal combustion engine according to any one of the first to third aspects, the fuel amount is further reduced by the idle-up control means M3. After the dose has been increased,
Feedback control means for performing feedback control of the rotational speed of the internal combustion engine M1 by increasing or decreasing the fuel amount in accordance with the result of recognition by the fuel injection amount recognition means M4; and increasing or decreasing the fuel amount by the feedback control means. The gist is that feedback control increase / decrease correction means for correcting an increase / decrease in the fuel amount by the feedback control means in accordance with the result of recognition by the fuel injection amount recognition means M4 at the time of performing the control.

According to a fifth aspect of the present invention, in the idle speed control device for a stratified combustion internal combustion engine according to the fourth aspect, the fuel amount at the time when the fuel amount is increased or decreased by the feedback control means. Injection amount recognition means M4
The gist is that when the fuel injection amount recognized by the above is large, the degree of increase or decrease in the fuel amount is smaller than when the fuel injection amount is small.

Further, according to the present invention, in an internal combustion engine capable of performing stratified charge combustion, when the fuel injection amount at the start of idle-up is large, the fuel amount is smaller than when the fuel injection amount is small. The gist of the present invention is an idling speed control device for a stratified combustion internal combustion engine, characterized in that the degree of increase is small.

(Operation) According to the first aspect of the present invention, as shown in FIG. 1, fuel is supplied into the cylinder of the internal combustion engine M1 by the fuel injection means M2, and stratified combustion can be performed. When the load is applied to the internal combustion engine M1 when the internal combustion engine M1 is in the idling state and the combustion state is stratified combustion, the internal combustion engine M1 is supplied from the fuel injection means M2 by the idle-up control means M3. As a result, the idle amount is increased, and a decrease in the rotational speed of the internal combustion engine M1 is suppressed.

In the present invention, the fuel injection amount recognizing means M
4, the fuel injection amount from the fuel injection means M2 is recognized. Then, in the increase correction means M5, the idle-up control means M3 is controlled according to the fuel injection amount at the time when the idle-up control means M3 performs the idle-up.
3 is corrected.

Therefore, an increase in the fuel amount such that the rotation fluctuation does not vary is ensured according to the fuel injection amount at the time when the idle-up is performed. Therefore, at the time of idling-up, the rotational speed does not temporarily increase suddenly.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the fuel amount increased by the idle-up control means M3 is an expected amount. This expected amount is corrected, and the increase can be optimized.

Further, according to the third aspect of the present invention,
In addition to the effects of the invention described in claims 1 and 2, the fuel injection amount recognizing means M4 at the time when the idle-up is performed.
When the fuel injection amount recognized by the above is large, the degree of increase in the fuel amount is smaller than when the injection amount is small. Here, as the fuel injection amount at the time of performing the idling-up increases, the degree of increase in the rotational speed (the degree of increase in rotational fluctuation) when the amount of fuel increase increases tends to increase. Therefore, according to the present invention, the degree of increase in the number of revolutions when the fuel injection amount is large is suppressed, and the above-described operation is further ensured.

In addition, according to the invention described in claim 4,
In addition to the effects of the invention described in claims 1 to 3,
After the fuel amount is increased by the idle-up control unit M3, the feedback control unit performs feedback control of the rotation speed by increasing or decreasing the fuel amount according to the detection result of the fuel injection amount recognition unit M4. Then, in accordance with the fuel injection amount at the time when the fuel amount is increased or decreased by the feedback control means, the increase or decrease amount of the fuel amount by the feedback control means is corrected by the feedback control increase / decrease correction means. Therefore, even during the feedback control after the idle-up, an increase or decrease in the fuel amount such that the rotation fluctuation does not vary is secured.

In addition, according to the invention described in claim 5,
In addition to the effect of the invention according to claim 4, when the fuel injection amount at the time when the fuel amount is increased or decreased by the feedback control means is large, the fuel amount is smaller than when the fuel injection amount is small. The degree of change is small. Here, as described above, as the fuel injection amount at the time of increasing or decreasing increases,
When the amount of change is increased or decreased by the same amount, the degree of fluctuation of the rotational speed (the degree of increase in rotational fluctuation) tends to increase. Therefore, according to the present invention, the degree of increase or decrease in the number of revolutions when the fuel injection amount is large is suppressed, and the operation of the invention described in claim 4 is further ensured.

Further, according to the invention described in claim 6,
In an internal combustion engine capable of performing stratified combustion, when the fuel injection amount of the internal combustion engine at the start of idle-up is large, the degree of increase in the fuel amount is smaller than when the fuel injection amount is small. Therefore, an increase in the fuel amount such that the rotation fluctuation does not vary is ensured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of a stratified combustion internal combustion engine idle speed control apparatus according to the present invention will be described in detail with reference to the accompanying drawings. .

FIG. 2 is a schematic configuration diagram showing an idle speed control device of a direct injection engine mounted on a vehicle in the present embodiment. Engine 1 as internal combustion engine
Has, for example, four cylinders 1a, and each of these cylinders 1a
3 is shown in FIG. As shown in these drawings, the engine 1 includes a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. A cylinder head 4 is provided on an upper portion of the cylinder block 2.
A combustion chamber 5 is formed between the two. 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. This spark plug 10 includes:
The igniter 12 via a distributor (not shown)
Is applied. And
The ignition timing of the ignition plug 10 is determined by the igniter 1
2 is determined by the output timing of the high voltage. Further, a fuel injection valve 11 is disposed 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 fuel injection valve 11 is directly injected into the cylinder 1a, so that not only homogeneous combustion but also so-called stratified combustion is performed. I have.

As shown in FIG. 2, a first intake port 7a and a 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 this embodiment is of a so-called electronic control type, and basically, the step motor 22 is
The throttle valve 23 is opened and closed by being driven based on the output signal from 0. 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 15
The intake passage is constituted by b and the like. 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 this 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.

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 idle-up control means, fuel injection amount recognition means, and increase correction 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 ° CA, for example.
An output pulse is generated each time the motor rotates, and the output pulse is input to the input port. In the CPU 34, the top dead center sensor 2
7 and the output pulse of the crank angle sensor 28, the engine speed NE is calculated (read).

Further, the rotation angle of the shaft 18 is
The swirl control valve sensor 29 detects the swirl control valve (SCV).
Seventeen opening degrees are detected. 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, the operating state of the engine 1 is detected by the top dead center sensor 27, the crank angle sensor 28, the swirl control valve sensor 29, the intake pressure sensor 61, the water temperature sensor 62, and the like.

On the other hand, the output port 36 is connected to each of the fuel injection valves 11 and each of the step motors 1 via a corresponding drive circuit 38.
9, 22, the igniter 12 and the EGR valve 53 (step motor). Then, based on signals from the sensors 25 to 29, 61, and 62, the ECU 30 operates according to a control program stored in the ROM 33,
The fuel injection valve 11, the step motors 19 and 22, the igniter 12, the EGR valve 53 and the like are suitably controlled.

Next, a program related to various controls according to the present embodiment in the idling speed control apparatus for a stratified combustion engine having the above configuration will be described with reference to a flowchart. That is, FIG. 4 is a flowchart showing an “idle-up control routine” executed by the ECU 30 on the assumption that stratified combustion is being performed when the engine 1 is idling,
For example, it is executed by interruption every predetermined crank angle.

When the processing shifts to this routine, the ECU
30 first determines in step 101 whether an idle-up request has been made. Here, the idle-up request means when an external load is applied.
For example, when the driver turns on the air conditioner switch, when the power steering (power steering) is operated, when the shift position is switched from the N range to the D range, or when another electric load is applied. Can be

If it is not determined in step 101 that an idle-up request has been made, it is determined that there is no need to perform idle-up, and the subsequent processing is temporarily terminated.

On the other hand, if there is an idle up request, step 10 is executed to execute idle up.
Move to 2. In step 102, the final injection amount QF (fuel injection amount) immediately before performing idle-up is read (recognized).

Further, in the following step 103,
A correction coefficient K is obtained and set based on the final injection amount QF read this time. Here, when setting the correction coefficient K, a map as shown in FIG. 5 is taken into consideration. That is, the value of the correction coefficient K is set to a smaller value (1.0 ≧ K1>K2>K3>) as the final injection amount QF immediately before performing the idle-up is larger (q1 <q2 <q3 <... <Qn).
...>Kn> 0).

In step 104, the value obtained by multiplying the expected control amount tPE for the external load by the correction coefficient K set this time is set as the final idle-up amount PE.

Further, at step 105, the ECU
30 is the final idle-up amount P calculated and set this time.
E is reflected in the final injection amount QF. That is, the ECU 30
Sets the final injection amount QF to a value obtained by adding the final idle-up amount PE to the separately calculated basic injection amount QBASE. Then, the subsequent processing ends once.

As described above, in the "idle-up control routine", when stratified charge combustion is being performed,
When the idle-up request is issued, the fuel injection amount is increased by the final idle-up amount PE.
In calculating the idle-up amount PE, a correction is made based on the final injection amount QF immediately before the idle-up. Although not described here, if there is an idle-up request in the case where homogeneous combustion is being performed, the intake air amount (throttle opening in the present embodiment) is increased as in the conventional case. As a result, idle-up is performed.

Next, the operation and effect of this embodiment will be described. (A) In the present embodiment, when the engine 1 is idling and the combustion state of the engine 1 is stratified combustion, when a load is applied to the engine 1,
The amount of fuel directly supplied from the fuel injection valve 11 is increased. Here, at the time of stratified combustion, a change in the amount of fuel greatly affects combustion according to the final injection amount QF at that time. For example, as shown in FIG. 8, in a state where the final injection amount QF immediately before idling-up is high, when the fuel amount is increased by the same amount as when the final injection amount QF is low, the change amount of the engine speed NE increases, and the engine speed increases. The number NE temporarily increases rapidly. Conversely, when the final injection amount QF immediately before idling-up is large, the amount of fuel required for idling-up is small when it is intended to obtain the same rotational speed fluctuation as when it is small.

On the other hand, in the present embodiment, a correction is made according to the final injection amount QF at the time when the idle-up is performed. More specifically, as shown in FIG. 7, when a load is applied (immediately before idle-up is performed)
When the final injection amount QF is large [FIG. 7 (b)], the correction coefficient K becomes smaller as compared with the case where the injection amount QF is small [FIG. 7 (a)]. (Final idle-up amount PE) becomes small. By performing such control, the same increase in the engine speed NE can be obtained regardless of whether the final injection amount QF is large or small. Therefore, even when the final injection amount QF immediately before idling-up is large at the time of idling-up, the engine speed NE does not temporarily increase suddenly.

(B) By optimizing the correction coefficient K in this manner, the amount of change in the engine speed NE during idle-up can be made the same. Therefore, in this case, an increase in the rotational speed NE as originally planned can be expected.

(C) Further, as shown in FIG. 6, when the final injection quantity QF immediately before idling-up is large, when the final injection quantity QF is small, an attempt is made to obtain the same rotational speed fluctuation. In addition, the amount of fuel required for idling up is small. As a result, the fuel efficiency can be further improved.

(Second Embodiment) Next, a second embodiment of the present invention will be described. However, since the configuration and the like of this embodiment are the same as those of the above-described first embodiment, the same members and the like are denoted by the same reference numerals and description thereof is omitted. And, below, the first
The following description focuses on differences from the first embodiment.

In the present embodiment, it is premised that the same processing as in the first embodiment is performed. That is, at the time of idle-up, the above-mentioned "idle-up control routine" is performed. In addition to this, in the present embodiment, after idle-up is performed, feedback control of the engine speed NE (by increasing or decreasing the final injection amount QF, the engine speed NE is reduced to the target engine speed). Control).

That is, FIG. 9 assumes that the stratified combustion is being performed when the engine 1 is idling, and that the feedback control executed by the ECU 30 after the above-described idle-up control has been executed. Is a flowchart showing a "routine", which is executed, for example, by interruption every predetermined crank angle.

When the processing shifts to this routine, the ECU
30 first determines in step 201 whether the feedback control condition is satisfied. Here, the feedback control condition includes, for example, that the actual engine speed NE has once reached the target engine speed after idling up.

If the feedback control condition is not satisfied in step 201, it is determined that the feedback control has not yet been performed, and the subsequent processing is temporarily terminated.

On the other hand, when the feedback control condition is satisfied, the process proceeds to step 202 to execute the feedback control. In step 202, the current final injection amount (fuel injection amount) Q
Read F.

In the following step 203,
A correction coefficient β is obtained and set based on the final injection amount QF read this time. Here, when setting the correction coefficient β, a map as shown in FIG. 10 is taken into consideration. That is, the larger the final injection amount QF immediately before reflecting the control amount DI to the final injection amount QF in the feedback control (α1 <
α2 <α3 <... <αn), and the value of the correction coefficient β is set to a small value (1.0 ≧ β1>β2>β3>...>βn>
0).

In step 204, a value obtained by multiplying the feedback integration constant tKDI by the correction coefficient β set this time is added to the previous control amount DI _i-1 , and the value is added to the current control amount DI _i-1. Set as DI. The feedback integration constant tKDI can take a positive value or a negative value depending on whether the current engine speed NE is smaller than the target engine speed.

Further, at step 205, the ECU
Reference numeral 30 denotes a control amount DI calculated this time and set to a final injection amount QF.
To reflect. Then, the subsequent processing ends once.
As described above, in the “feedback control routine”, when the feedback control condition is satisfied, the fuel injection amount is increased or decreased by the current control amount DI. Further, when setting the control amount DI, a correction is made based on the final injection amount QF immediately before reflecting the control amount DI. Although not described here, in the case where the homogeneous combustion is performed, the feedback control is performed by increasing or decreasing the intake air amount (throttle opening in the present embodiment) as in the related art. .

Next, the operation and effect of this embodiment will be described. (C) According to the present embodiment, in addition to the operation and effect of the above-described first embodiment, after idle-up is performed, feedback control of the engine speed NE is executed by increasing or decreasing the fuel amount. . At this time, the amount of increase or decrease of the fuel amount is corrected according to the final injection amount QF at the time when the amount of fuel is increased or decreased. Therefore, even during the feedback control after the idle-up, it is possible to secure an increase or decrease in the fuel amount such that the rotation fluctuation does not vary.

More specifically, when the final injection amount QF at the time when the control amount DI is reflected is large, the correction coefficient β and, consequently, the degree of increase and decrease of the fuel amount are larger than when the injection amount QF is small. small. Here, as described above, as the final injection amount QF at the time of increasing or decreasing increases, the degree of fluctuation of the rotational speed NE when the amount of increase or decrease by the same amount (the degree of increase in rotational fluctuation) tends to increase. become. Therefore, according to the present embodiment, the degree of increase or decrease of the rotation speed when the final injection amount QF is large is suppressed, and a temporary sudden increase in the engine rotation speed NE during feedback control can also be suppressed.

The embodiment is not limited to the above, but may be modified as follows. (1) Although the description has been omitted in the above embodiment, even when the load is reduced (or released), that is, when the idle-up is released, the reduction in the fuel amount is corrected according to the final injection amount QF. You may do so. In this case, it is possible to prevent a temporary sudden decrease in the engine speed NE.

(2) In the above-described embodiment, at the time of homogeneous combustion, the intake air amount is adjusted by employing an electronically controlled throttle mechanism including the throttle valve 23 and the step motor 22. On the other hand, an idle speed control valve provided in a bypass intake passage that bypasses a throttle valve 23 provided in the intake passage, and an actuator that opens and closes the idle speed control valve are provided.
The intake air amount may be adjusted by the SC mechanism.

(3) 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 a fuel injection valve is provided on the intake valves 6a and 6b side, a type in which fuel is injected directly into the cylinder bore (combustion chamber 5) is also included.

(4) 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.

[0063]

As described in detail above, according to the present invention,
In an idle speed control device for an internal combustion engine capable of performing stratified combustion, it is possible to suppress a sudden increase in the engine speed by performing idle-up when a load is applied to the internal combustion engine. It has an excellent effect.

[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 illustrating an idle speed control device of the stratified combustion engine according to the first embodiment.

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

FIG. 4 is a flowchart showing an “idle-up control routine” executed by the ECU.

FIG. 5 is a map showing a relationship between a correction coefficient and a final injection amount immediately before idle-up.

FIG. 6 is a graph showing the relationship between the final injection amount immediately before idling-up and the amount of change in rotation speed.

FIG. 7 is a timing chart showing a relationship between a load, an engine speed, and a fuel injection amount over time,
(A) shows the behavior when the final injection amount immediately before idle-up is small, and (a) shows the behavior when the final injection amount immediately before idle-up is large.

FIG. 8 is a graph showing a relationship between a final injection amount immediately before idling-up and a fuel amount required for idling-up when the engine rotational speed is increased by a predetermined rotational speed.

FIG. 9 is a flowchart illustrating a “feedback control routine” executed by the ECU.

FIG. 10 is a map showing a relationship between a correction coefficient and a final injection amount immediately before a control amount is reflected.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as internal combustion engine, 11 ... Fuel injection valve, 2
2 ... Step motor, 23 ... Throttle valve, 30 ... Idle-up control means, fuel injection amount recognition means, increase correction means, feedback control means, and feedback control increase / decrease correction means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G301 HA04 HA13 HA16 JA04 KA07 KA10 LA03 LA05 LB04 LC04 MA11 ND01 NE01 NE06 PA07Z PA11Z PA14Z PE01A PE01Z PE03Z PE08Z PF03Z PF11Z

Claims (6)

[Claims] 1. A fuel injection means capable of supplying fuel into a cylinder of an internal combustion engine to perform stratified combustion, and when the internal combustion engine is in an idling state and the combustion state of the internal combustion engine is a stratified combustion. And an idle-up control unit that performs idle-up by increasing the amount of fuel injected from the fuel injection unit in order to suppress a decrease in the rotation speed of the internal combustion engine when a load is applied to the internal combustion engine. An idling speed control device for a stratified combustion internal combustion engine, comprising: a fuel injection amount recognizing means for recognizing a fuel injection amount from the fuel injection means; and An increase correction unit that corrects an increase in the amount of fuel by the idle-up control unit according to a recognition result of the fuel injection amount recognition unit. Idle speed control device for a stratified combustion internal combustion engine. 2. The idling speed control device for a stratified combustion internal combustion engine according to claim 1, wherein the fuel amount increased by the idle-up control means is an expected amount. 3. The idle speed control device for a stratified combustion internal combustion engine according to claim 1, wherein the fuel injection amount recognized by the fuel injection amount recognition means at the time of performing the idle-up is large. Is an idling speed control device for a stratified combustion internal combustion engine, characterized in that the degree of increase in the fuel amount is smaller than when the fuel injection amount is small. 4. The apparatus according to claim 1, wherein the fuel injection amount is further increased after the idle-up control means increases the fuel amount. A feedback control unit that performs feedback control of a rotation speed of the internal combustion engine by increasing or decreasing the fuel amount according to a recognition result of the recognition unit; and a feedback control unit that increases or decreases the fuel amount by the feedback control unit. An idling speed control device for a stratified combustion internal combustion engine, comprising: feedback control increase / decrease correction means for correcting an increase / decrease in fuel amount by the feedback control means in accordance with a result of recognition by a fuel injection amount recognition means. 5. The idling speed control apparatus for a stratified combustion internal combustion engine according to claim 4, wherein the fuel injection amount recognized by the fuel injection amount recognition unit at the time when the fuel amount is increased or decreased by the feedback control unit. An idling speed control device for a stratified combustion internal combustion engine, wherein when the fuel injection amount is large, the degree of increase and decrease of the fuel amount is smaller than when the fuel injection amount is small. 6. An internal combustion engine capable of performing stratified charge combustion, characterized in that when the fuel injection amount at the start of idle-up is large, the degree of increase in the fuel amount is smaller than when the fuel injection amount is small. Idle speed control device for a stratified combustion internal combustion engine.