WO1998026170A1

WO1998026170A1 - Idling revolution control device for stratified-charge combustion internal combustion engine

Info

Publication number: WO1998026170A1
Application number: PCT/JP1997/004517
Authority: WO
Inventors: Hiroyuki Mizuno; Tetsuzi Nagata
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 1996-12-12
Filing date: 1997-12-08
Publication date: 1998-06-18

Abstract

Arranged around an inner wall surface of a cylinder head (4) near a first intake valve (6a) and second intake valve (6b) of an engine (1) is a fuel injection valve (11), from which a fuel is jetted directly into a cylinder (1a). Provided in an intake duct (20) is a throttle valve (23) adapted to be opened and closed by a step motor (22). An electronic control unit (ECU) (30) increases an amount of fuel directly supplied from the fuel injection valve (11) when stratified-charge combustion is effected at the time of idling of the engine (1). While it takes a predetermined period of time from detection of application of a load to actual application of the load to the engine (1), an amount of fuel is gradually increased by a calculation which causes time lag in a response of an amount of fuel. Accordingly, an unproportional increase in only an amount of fuel compared with a moderate load is eliminated.

Description

Technical Description Idling speed control system for stratified combustion internal combustion engine

The present invention relates to an internal combustion engine capable of performing stratified combustion, and more particularly to an idle speed control device for an internal combustion engine capable of performing stratified combustion. Background art

Conventionally, in a generally 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, the intake passage is opened and closed by a throttle valve linked to the operation of the accelerator, and this opening and closing causes the amount of intake air to be supplied to the combustion chamber of the engine (the result is a homogeneous mixture of fuel and air). Is adjusted and the engine output is controlled accordingly.

In the above-described technique based on so-called homogeneous combustion, 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, the flammable mixture is unevenly distributed near the spark plug, and the air-fuel ratio in the relevant portion is increased to improve ignitability. So-called “stratified combustion” technology is known. In this technique, when the engine is under a low load, the injected fuel is unevenly supplied around the ignition plug, and the throttle valve is almost fully opened to perform stratified combustion. As a result, 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. 7-166169 is known. With this technology, the cylinder head An injector is mounted, and fuel is directly injected into the combustion chamber from the injector. By controlling the injection amount and the injection timing of the fuel injected from the injector, stratified charge combustion is performed in a low / medium load region.

Further, in this technology, when stratified combustion is performed at the time of idling of the engine, the fuel injection amount is controlled while the stratified combustion is being performed. By performing such control, the idling speed is controlled while stratified combustion is performed.

Further, in the technology disclosed in Japanese Patent Application Laid-Open No. 4-370343, either a stratified combustion or a homogeneous combustion combustion method is employed depending on the operating conditions, and at least at low / medium loads, stratified fuel injection is performed. In addition, fuel injection and ignition for homogeneous combustion are controlled at high load. When the engine is idling, only the fuel injection amount is controlled to increase or decrease according to the cooling water temperature. With this technology, stratified combustion at low load is maintained well, and warm-up during cold operation is promoted.

However, in the technique described in the above-mentioned conventional publication, the following problem may occur. In other words, 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 amount of intake air.

In this case, a certain period of time is required from when the load signal is input to when the load is actually applied to the engine, but a signal to increase the amount of intake air, that is, the idle speed control port / valve throttle valve It takes a predetermined time for the amount of intake air to actually increase after the signal for increasing the opening is output.

On the other hand, in the above-described prior art, when stratified combustion is being performed, the idle-up is performed by increasing the fuel injection amount.

However, the fuel injection amount is actually increased after the signal for increasing the fuel injection amount is output, because fuel is directly injected into the combustion chamber. It doesn't take long. As a result, a problem that the engine speed is excessively increased may occur.

In addition, during stratified combustion, changes in the amount of fuel greatly affect combustion depending on the engine speed at that time. For example, in a state where the engine speed is high, if the fuel amount is increased by the same amount as when the engine speed is low, the engine speed may be too high.

In addition, during stratified combustion, a change in the amount of fuel greatly affects combustion depending on the amount of fuel injected at the start of idle-up. For example, if the fuel injection amount immediately before the start of idle-up is large and the fuel injection amount is small in the state and the fuel amount is increased equivalently to the case, the engine speed may be too high. .

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, wherein the engine is operated when a load is applied to the internal combustion engine and idle-up is performed. It is an object of the present invention to provide an idling speed control device for a stratified combustion internal combustion engine capable of ensuring the stability of the speed. Disclosure of the invention

An idle speed control device for a stratified combustion internal combustion engine according to claim 1 of the present application includes: an internal combustion engine capable of performing stratified combustion; operating state detection means for detecting an operating state of the internal combustion engine; and a load on the internal combustion engine. , An idle-up control means for performing idle-up to suppress a decrease in the rotational speed of the internal combustion engine; and an idle-speed control device for a stratified combustion internal combustion engine, comprising: The control means includes: a fuel amount increasing means for increasing an amount of fuel supplied to the internal combustion engine; and a fuel increase increased by the fuel amount increasing means in accordance with the operating state detected by the operating state detecting means. Correction means for correcting the amount.

An idling speed control device for a stratified combustion internal combustion engine according to claim 2 is the idling speed control device for a stratified combustion internal combustion engine according to claim 1, wherein The state detection means includes load input signal detection means for detecting a load input signal indicating that a load is applied to the internal combustion engine, and the correction means detects the load input signal detected by the load input signal detection means. A fuel amount response characteristic correcting means for causing a time delay in response characteristic of the fuel amount increased by the fuel amount increasing means in response.

The idling speed control device for a stratified combustion internal combustion engine according to claim 3 is the idling speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the fuel amount response characteristic correcting means is: It is characterized in that the fuel amount is gradually increased in accordance with the elapsed time from the detection of the load input signal.

An idling speed control device for a stratified combustion internal combustion engine according to claim 4 is the idling speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the fuel amount response characteristic correction means comprises: The fuel amount is increased after a predetermined time. An idle speed control device for a stratified combustion internal combustion engine according to claim 5 is the idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the load input signal detecting means further comprises: The type of load applied to the internal combustion engine is detected, and the fuel amount increasing means varies the fuel increase amount according to the degree of the load based on the type of the load detected by the load input signal detecting means. It is characterized by doing.

The idle speed control device for a stratified combustion internal combustion engine according to claim 6 is the idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the idle-up control means includes: When the combustion state is homogeneous combustion, an intake air amount increasing means for increasing an intake air amount of the internal combustion engine is further provided.

An idle speed control device for a stratified combustion internal combustion engine according to claim 7 is the idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the idle speed control device is An idle-up releasing unit configured to release the idle-up when it is detected that the load on the internal combustion engine has been reduced; The gap canceling means includes: a fuel amount reducing means for reducing an amount of fuel supplied to the internal combustion engine; and a fuel reduced by the fuel amount reducing means in response to the load input signal detected by the load input signal detecting means. The fuel cell system is characterized in that it comprises a reduced fuel amount response characteristic correction means for causing a time delay in the amount response characteristic.

An idle speed control device for a stratified combustion internal combustion engine according to claim 8 is the idle speed control device for a stratified combustion internal combustion engine according to claim 1, wherein the operating state detecting means includes: A rotation speed detection means for detecting the rotation speed of the engine; and the correction means, wherein the fuel increase is performed in accordance with a detection result of the rotation speed detection means immediately before the idle-up control is performed by the idle-up control means. It is characterized in that an increase correction means for correcting the amount is provided.

An idling speed control device for a stratified combustion internal combustion engine according to claim 9 is the idling speed control device for a stratified combustion internal combustion engine according to claim 8, wherein the fuel increased by the fuel amount increasing means. The amount is a prospective amount.

An idle speed control device for a stratified combustion internal combustion engine according to claim 10 is the idle speed control device for a stratified combustion internal combustion engine according to claim 8, wherein the idle speed control device immediately before the idle-up is performed. When the rotation speed detected by the rotation speed detection means is high, the degree of increase in the fuel amount is smaller than when the rotation speed is low.

An idle speed control device for a stratified combustion internal combustion engine according to claim 11 is the idle speed control device for a stratified combustion internal combustion engine according to claim 8, wherein the idle speed control device includes: Feedback control means for performing feedback control of the internal combustion engine by increasing or decreasing the fuel amount in accordance with the detection result of the rotational speed detecting means after the fuel amount is increased by the fuel amount increasing means; A feedback control increase / decrease correction means for correcting the increase / decrease amount of the fuel amount by the feedback control means in accordance with the detection result of the rotational speed detection means at the time when the fuel amount is increased / decreased by the stage. It is characterized by. An idling speed control apparatus for a stratified combustion internal combustion engine according to claim 12 is the idling speed control apparatus for a stratified combustion internal combustion engine according to claim 11, wherein the feedback control means When the rotational speed detected by the rotational speed detecting means at the time of increasing or decreasing the fuel amount is high, the degree of increase or decrease of the fuel amount is smaller than when the rotational speed is low. And

An idle speed control device for a stratified combustion internal combustion engine according to claim 13 is the idle speed control device for a stratified combustion internal combustion engine according to claim 1, wherein the idle speed control device is: A fuel injection means for supplying fuel into a cylinder of the internal combustion engine; an operating state detecting means including fuel injection amount detecting means for detecting a fuel injection amount from the fuel injection means; Is characterized by comprising an increase correction means for correcting the fuel increase amount in accordance with the detection result of the fuel injection amount detection means immediately before the idle up control is performed by the idle up control means.

The idling speed control device for a stratified combustion internal combustion engine according to claim 14 is the idling speed control device for a stratified combustion internal combustion engine according to claim 13, wherein the idling speed control device is increased by the fuel amount increasing means. The amount of fuel to be supplied is an estimated amount.

An idling speed control device for a stratified combustion internal combustion engine according to claim 15 is the idling speed control device for a stratified combustion internal combustion engine according to claim 13, wherein the idling speed control is performed immediately before the idle-up is performed. When the fuel injection amount detected by the fuel injection amount detecting means is large, the degree of increase in the fuel amount is smaller than when the fuel injection amount is small.

An idle speed control device for a stratified combustion internal combustion engine according to claim 13 is the idle speed control device for a stratified combustion internal combustion engine according to claim 13, wherein the idle speed control device is Feedback control means for feedback-controlling the internal combustion engine by increasing or decreasing the fuel amount in accordance with the detection result of the fuel injection amount detection means after the fuel amount is increased by the fuel amount increase means; The detection result of the fuel injection amount detecting means at the time when the fuel amount is increased or decreased by the feedback control means Accordingly, a feedback control increase / decrease correction means for correcting the increase / decrease amount of the fuel amount by the feedback control means is further provided.

An idling speed control device for a stratified combustion internal combustion engine according to claim 17 is the idling speed control device for a stratified combustion internal combustion engine according to claim 16, wherein the feedback control means When the fuel injection amount detected by the fuel injection amount detecting means at the time of increasing or decreasing the fuel amount is large, it is determined that the degree of increase or decrease of the fuel amount is smaller than when the fuel injection amount is small. Features.

According to a certain curved surface of the present invention, as shown in FIG. 1, the operating state of the internal combustion engine MI capable of performing stratified combustion is detected by the operating state detecting means M2. Then, at the time of idling of the internal combustion engine M1, when the operating state detecting means M2 detects that a load is applied, the idle-up control means M3 performs idle-up. This suppresses a decrease in the rotation speed of the internal combustion engine Ml.

In the present invention, when the combustion state of the internal combustion engine Ml is stratified combustion, the fuel is directly supplied to the internal combustion engine Ml by the fuel amount increasing means M4, which is a component of the idle-up control means M3. The amount of fuel used is increased. In the present invention, the operating state detecting means M2 detects the increase in the fuel amount increased by the fuel amount increasing means M4 by the correcting means M5 which is a component of the idle-up control means M3. Required corrections are made based on operating conditions.

Therefore, various state variables of the internal combustion engine (for example, the load input signal to the internal combustion engine M1, the load actually applied to the internal combustion engine M1, the rotation speed of the internal combustion engine M1, and the fuel injection amount to the internal combustion engine M1) Even if there is a non-linear relationship between the two, a correction based on each non-linear relationship is added to the increase in the amount of fuel supplied to the internal combustion engine Ml.

Therefore, it is possible to prevent only the rotation speed from increasing even when the fuel increase is not so required.

According to another curved surface of the present invention, as shown in FIG. 2, a load applied to the internal combustion engine Ml capable of performing stratified combustion is detected by the load input signal detection means M2A. Soshi When the load is detected by the load input signal detection means M 2 A during idling of the internal combustion engine M 1, idle-up is performed by the idle-up control means M 3 A. Thus, a decrease in the rotation speed of the internal combustion engine Ml is suppressed.

In the present invention, when the combustion state of the internal combustion engine Ml is stratified combustion, the fuel is directly supplied to the internal combustion engine Ml by the fuel amount increasing means M4A which is a component of the idle-up control means M3A. The amount of fuel used is increased. Here, a predetermined time is required between the time when the load is detected to be applied and the time when the load is actually applied to the internal combustion engine MI. On the other hand, the increase in the amount of fuel actually supplied to the internal combustion engine M1 after the instruction to increase the amount of fuel by the fuel amount increasing means M4A is theoretically performed in an extremely short time. On the other hand, in the present invention, the fuel amount response characteristic correcting means M5A, which is a component of the idle-up control means M3A, causes a time delay in the response characteristic of the fuel amount increased by the fuel amount increasing means M4A. Cause.

For this reason, it takes time for the fuel amount to increase in response to the predetermined time required for the load actually applied to the internal combustion engine Ml to increase. Therefore, it is not possible to increase only the fuel even when the load is not so large.

Further, in addition to the above operation, when the fuel amount is gradually increased by the fuel amount response characteristic correcting means M5A when the fuel amount is increased, the above operation is more effectively achieved. Furthermore, the fuel amount response characteristic correction means M5A may further delay the increase in the fuel amount. Therefore, in addition to the above-described effects, it is possible to make the increase in the fuel amount more easily compatible with the increase in the load.

At the same time, the rate of increase in the fuel amount may be made variable in accordance with the degree of the load detected by the load input signal detection means M2. Therefore, even if the type and the degree of the load are different, the rotation speed does not suddenly increase.

In addition, when the combustion state of the internal combustion engine Ml is homogeneous combustion, the idle-up may be performed by increasing the intake air amount of the internal combustion engine Ml. Also, when the load input signal detecting means M2 detects that the load on the internal combustion engine Ml has been reduced during idling of the internal combustion engine Ml, the idle-up canceling means cancels the idle-up. May be performed. At this time, when the combustion state of the internal combustion engine Ml is stratified combustion, the fuel amount supplied to the internal combustion engine M1 is reduced by the fuel amount reduction control means, which is a component of the idle-up canceling means. At this time, a time delay is caused in the reduction of the fuel amount by the reduced fuel amount response characteristic correction means, which is a component of the idle-up release control means. Therefore, even when the load is released, it takes a certain amount of time to reduce the load actually applied to the internal combustion engine Ml, and it takes time to reduce the fuel amount. . Therefore, the fuel quantity alone does not decrease even if the load is not so small.

According to still another curved surface of the present invention, as shown in FIG. 3, fuel can be supplied into the cylinder of the internal combustion engine Ml by the fuel injection means M6 to perform stratified combustion. When the load is applied to the internal combustion engine Ml when the internal combustion engine Ml is in an idling state and the combustion state is stratified combustion, the fuel amount increasing means M4B The amount of fuel supplied from the fuel injection means M6 is increased, whereby idle-up is performed, and a decrease in the rotational speed of the internal combustion engine M1 is suppressed.

Now, in the present invention, the rotation speed of the internal combustion engine Ml is detected by the rotation speed detection means M2B. Then, in the increase correction means M5B, the increase in the fuel amount by the fuel amount increase means M4B is corrected according to the rotation speed immediately before the idle-up is performed by the fuel amount increase means M4B.

Therefore, according to the rotation speed immediately before the idle-up is performed, an increase in the fuel amount such that the rotation varies or does not occur is secured. Therefore, when idling up, the number of revolutions does not increase too much.

Further, the fuel amount increased by the fuel amount increasing means M 4 B may be an expected amount. The expected amount will be corrected, and the increase in the amount can be optimized. Furthermore, even if the rotational speed detected by the rotational speed detecting means M 2 B immediately before performing the idle-up is high, and if the rotational speed is low, the increase in the fuel amount is small compared to the case, Good. Here, the higher the rotation speed immediately before performing the idle-up, the higher the rotation speed when the same amount is increased. Therefore, according to the present invention, an increase in the number of rotations when the number of rotations is high is suppressed, and the above-described operation is further ensured.

Further, after the fuel amount is increased by the fuel amount increasing means M 4 B, the feedback control means controls the rotational speed feedback by increasing or decreasing the fuel amount according to the detection result of the rotational speed detecting means M 2 B. May be performed. Then, according to the number of revolutions at the time when the fuel amount is increased or decreased by the feedback control unit, the increase or decrease amount of the fuel amount by the feedback control unit is corrected by the feedback control increase / decrease correction unit. Therefore, even during the feedback control after the idle-up, an increase or decrease of the fuel amount such that the rotation is not dispersed is secured.

In addition, when the rotational speed at the time when the fuel amount is increased or decreased by the feedback control means is high, the degree of increase or decrease in the fuel amount may be smaller than when the rotational speed is low. Here, as described above, the higher the rotational speed at the time of increasing or decreasing, the higher the rotational speed when the amount of increase or decrease by the same amount tends to increase. Therefore, according to the present invention, the increase and decrease of the rotation speed when the rotation speed is high is suppressed, and the effect of the present invention is further ensured.

Furthermore, in an internal combustion engine capable of performing stratified combustion, when the rotation speed of the internal combustion engine at the start of idling-up is high, the rotation speed is low, and the degree of increase in the fuel amount is small compared to the case. Therefore, an increase in the fuel amount such that the rotation does not vary is secured. According to still another curved surface of the present invention, as shown in FIG. 4, fuel can be supplied into the cylinder of the internal combustion engine Ml by the fuel injection means M6 to perform stratified combustion. When the load is applied to the internal combustion engine Ml when the internal combustion engine Ml is in an idling state and its combustion state is stratified combustion, the fuel amount increasing means M4C As a result, the amount of fuel supplied from the fuel injection means M6 is increased, whereby idling is performed, and a decrease in the rotational speed of the internal combustion engine M1 is suppressed.

Now, in the present invention, the fuel injection amount from the fuel injection means M 6 is detected by the fuel injection amount detection means M 2 C. Then, in the increase correction means M5C, the increase in the fuel amount by the fuel amount increase means M4C is corrected in accordance with the fuel injection amount immediately before the idle-up is performed by the idle-up control means M3.

Accordingly, an increase in the fuel amount such that the rotation does not vary is secured according to the fuel injection amount immediately before the idle-up is performed. Therefore, when idling up, there is no possibility that the rotation speed will rise too much.

Further, the fuel amount increased by the fuel amount increasing means M 4 C may be an expected amount. The expected amount will be corrected, and the increase in the amount can be optimized. Furthermore, when the fuel injection amount detected by the fuel injection amount detecting means M 2 C at the time of performing the idle-up is large, the degree of increase in the fuel amount may be smaller than when the injection amount is small. . Here, the larger the fuel injection amount at the time of performing the idle-up, the larger the number of revolutions tends to be when the fuel injection amount is increased. Therefore, according to the present invention, an increase in the number of revolutions when the fuel injection amount is large is suppressed, and the above-described operation is further ensured.

Further, after the fuel amount is increased by the fuel amount increasing means M 4 C, the feedback control means controls the number of revolutions based on the fuel injection amount detecting means M 2 C according to the detection result of the fuel injection amount detecting means M 2 C. May be performed. 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 feedback control increase / decrease correction means corrects the increase / decrease amount of the fuel amount by the feedback control means. You. Therefore, even during the feedback control after the idle-up, the increase and decrease of the fuel amount such that the rotation does not vary is secured.

In addition, when the fuel injection amount is large at the time when the fuel amount is increased or decreased by the feedback control means, the degree of increase or decrease of the fuel amount is larger than when the fuel injection amount is small May be small. Here, as described above, as the fuel injection amount at the time of increasing or decreasing is increased, the rotational speed when the amount of increase or decrease is increased by the same amount tends to increase. Therefore, according to the present invention, the increase and decrease of the rotational speed when the fuel injection amount is large is suppressed, and the operation of the present invention is further ensured.

Furthermore, 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 does not vary is ensured. BRIEF DESCRIPTION OF THE FIGURES

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

FIG. 2 is a conceptual configuration diagram showing the basic concept of correcting the fuel increase amount according to the load input according to the present invention.

FIG. 3 is a conceptual configuration diagram showing a basic concept of correcting the fuel increase amount according to the rotation speed according to the present invention.

FIG. 4 is a conceptual configuration diagram showing a basic concept of correcting the fuel increase amount according to the fuel injection amount according to the present invention.

FIG. 5 is a schematic configuration diagram showing an idle speed control device for a stratified combustion engine according to one embodiment.

FIG. 6 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 7 is a flowchart showing an “idle speed control routine” executed by the ECU.

FIG. 8 is a diagram for explaining the operation and effect of the embodiment, and is a timing chart showing behaviors of an air conditioner switch, a magnet clutch, a final injection amount, and an engine speed.

Figure 9 shows the flow of the “idle-up control routine” executed by the ECU. It is a chart.

FIG. 10 is a map showing the relationship between the engine speed and the correction coefficient immediately before idling-up.

FIG. 11 is a graph showing the relationship between the engine speed immediately before idling-up and the amount of change in the engine speed when the same fuel amount is increased.

FIG. 12 is a flowchart showing a “feedback control routine” executed by the ECU.

Figure 13 is a map showing the relationship between the engine speed and the correction coefficient just before the control amount is reflected.

FIG. 14 is a flowchart showing the “idle-up control routine” executed by the ECU.

Figure 15 is a map showing the relationship between the correction coefficient and the final injection amount immediately before idle-up.

Fig. 16 is a graph showing the relationship between the final injection amount immediately before idling-up and the amount of change in the rotational speed.

Fig. 17 is a timing chart showing the relationship between load, engine speed, and fuel injection amount over time. (A) shows the case where the final injection amount immediately before idle-up is small, (b) Shows the behavior when the final injection amount immediately before idle-up is large, respectively.

FIG. 18 is a graph showing the relationship between the final injection amount immediately before idle-up and the fuel amount required for idle-up when the engine speed is increased by a predetermined speed.

FIG. 19 is a flowchart showing a “feedback control routine” executed by the ECU.

FIG. 20 is a map showing the relationship between the correction coefficient and the final injection amount immediately before the control amount is reflected. BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment that embodies an idle speed control device for a stratified combustion internal combustion engine according to the present invention will be described in detail with reference to the drawings.

FIG. 5 is a schematic configuration diagram showing an idle speed control device of a direct injection engine mounted on a vehicle in the present embodiment. The engine 1 as an internal combustion engine has, 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. A cylinder head 4 is provided above the cylinder block 2, 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, reference numeral 6a denotes a first intake valve, 6b denotes a second intake valve, and 7a denotes a first intake port. 7b shows a second intake port, 8 shows a pair of exhaust valves, and 9 shows a pair of exhaust ports.

As shown in FIG. 6, the first intake port 7a is composed of a helical intake port, and the second intake port 7b is composed of a straight port extending almost straight. An ignition plug 10 is provided at the center of the inner wall surface of the cylinder head 4. A high voltage from the igniter 12 is applied to the ignition plug 10 via a distributor (not shown). The ignition timing of the ignition plug 10 is determined by the output timing of the high voltage from the igniter 12. 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 injector 11 is directly injected into the cylinder 1a, so that not only homogeneous combustion but also so-called stratified combustion is performed. As shown in Fig. 5, the first intake port 7a and the second intake port 7b of each cylinder 1a Are connected to the surge tank 16 via a first intake path 15a and a second intake path 15b formed in each intake manifold 15, respectively. In each of the second intake passages 15b, a swirl control parileb 17 is arranged. These swirl control valves 17 are connected to a step motor 19 as an actuator via a common shaft 18. 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 nozzle 16 is connected to an air cleaner 21 via an intake duct 20.In the intake duct 20, a throttle valve 23 which is opened and closed by a separate step motor 22 is provided. ing. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type. Basically, the throttle motor 23 is driven based on an output signal from the ECU 30 to provide a throttle valve. Valves 23 are controlled to open and close. 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 is constituted by the intake duct 20, the surge tank 16, the first intake path 15a, the second intake path 15b, and the like. In the vicinity of the throttle valve 23, a throttle sensor 25 for detecting its opening (throttle opening TA) is provided. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder. Then, the exhaust gas after combustion is discharged to an exhaust duct (not shown) through the exhaust manifold 14.

Further, in the present embodiment, a known exhaust gas circulation (EGR) device 51 is provided. The EGR device 51 includes an EGR passage 52 as an exhaust gas circulation passage, and an EGR valve 53 as an exhaust gas circulation valve provided in the passage 52. The EGR passage 52 is provided to communicate between the intake duct 20 downstream of the throttle valve 23 and the exhaust duct. The EGR valve 53 has a built-in valve seat, valve body, and step motor (all not shown). The EGR mechanism is configured. The opening degree of the EGR valve 53 fluctuates when the step motor intermittently displaces the valve body with respect to the valve seat. When the EGR valve 53 opens, a part of the exhaust gas discharged to the exhaust duct flows to the EGR passage 52. The exhaust gas 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, by adjusting the opening of the EGR valve 53, the recirculation amount of the exhaust gas is adjusted.

The above-described ECU 30 is formed of a digital computer, and a RAM (random access memory) 32, a ROM (read-only memory) 33, and a CPU (microprocessor) connected to each other via a bidirectional bus 31. Central processing unit) 34, input port 35 and output port 36.

An accelerator sensor 26A that generates an output voltage proportional to the amount of depression of the accelerator pedal 24 is connected to the accelerator pedal 24, and the accelerator sensor 26A detects the accelerator opening ACCP. The output voltage of the accelerator sensor 26 A is input to the input port 35 via the AD converter 37. Similarly, the accelerator pedal 24 is provided with a fully-closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0". That is, the fully closed switch 26B generates a signal of “1” as a fully closed signal when the depression amount of the accelerator pedal 24 is “0”, and generates a signal of “0” otherwise. The output voltage of the fully closed switch 26 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, and this output pulse is input to the input port 35. The crank angle sensor 28 generates an output pulse every time the crankshaft rotates 30 ° CA, for example, and this output pulse is input to the input port. The CPU 34 calculates (reads) the crank position 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 detected by a swirl control valve sensor 29, whereby the opening degree of the swirl control port 17 (SCV) 17 is detected. Then, the output of the scale controller 29 is input to the input port 35 via the AZD converter 37.

In addition, by the slot Torusensa 2 5, _c output of the slot Torusensa 2 5 throttle opening TA is detected is input to the input port 35 via an A / D converter 3 7.

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 for detecting the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. The outputs of these sensors 61 and 62 are also input to the input port 35 via the AZD converter 37.

In the present embodiment, the throttle sensor 25, the accelerator sensor 26A, the fully closed switch 26B, the top dead center sensor 27, the crank angle sensor 28, the swirl control port and the valve sensor 29, the intake pressure The operation state is detected by the sensor 61, the water temperature sensor 62, and the like.

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

Next, a program relating to the correction of the fuel increase amount according to the load input in the idle speed control device of the stratified combustion engine having the above configuration will be described with reference to a flowchart.

That is, Fig. 7 shows that stratified combustion is performed when the engine 1 is idling. 6 is a flowchart showing an “idle speed control routine” executed by the ECU 30 on the premise that the routine is executed, and is executed, for example, by interruption every predetermined crank angle.

When the process proceeds to this routine, the ECU 30 first determines in step 101 whether an idle-up request has been issued. Here, the idle-up request means that when the air conditioner switch is turned on by the driver, when power steering (C. ヮ ste) is operated, when the shift position is switched from the N range to the D range, For example, when an electric load is applied.

If it is not determined in step 101 that the idle-up request has been issued, 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, the process proceeds to step 102. In step 102, all the fuel amount-converted correction terms (for example, air conditioner correction term DC AC, power steering correction term DPS, electric load correction term DB, torque converter correction term DE, etc.) corresponding to various loads are added. At the same time, the sum is set as a temporary idle-up correction term t PE.

Further, in the following step 103, the ECU 30 performs an operation to cause a time delay in the increase in fuel with respect to the temporary idle-up correction term t PE calculated this time, and adds the result to a new value. Idle-up correction term Set as PE. That is, the previous idle-up correction term PEi-1 is multiplied by (n-l), and the value calculated by adding the temporary idle-up correction term t PE calculated this time to n is divided by n. Correction term Set as PE.

Then, in step 104, the new idle-up correction term PE calculated and set this time is reflected in the final injection amount QF. That is, the ECU 30 sets a value obtained by adding the idle-up correction term PE to the separately calculated basic injection amount QB ASE not including the idle-up amount as the final injection amount QF. And then The process ends once.

As described above, in the above-mentioned “idle-up control routine”, when stratified combustion is being performed, if an idle-up request is made, the fuel injection amount is increased by the amount of the idle-up correction term PE. In calculating the idle-up correction term PE, a value of a calculation result for causing a time delay in increasing the fuel is used. Although not described here, the intake air amount (throttle opening in the present embodiment) increases as in the conventional case when there is an idle-up request when homogeneous combustion is performed. By being let go, idle up is performed.

Next, the operation and effect of the present 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, the amount of fuel directly supplied from the fuel injection valve 11 is increased. Here, a predetermined time is required from when the load is detected to when the load is actually applied to the engine 1. For example, as shown in Fig. 8, there is a delay between the time the air conditioner switch is turned on by the driver and the time the magnet switch of the air conditioner is actually turned on. On the other hand, the amount of fuel actually supplied into the cylinder 1a after the command to increase the fuel amount by the ECU 30 is increased in a much shorter time than the delay described above. On the other hand, in the present embodiment, the amount of fuel gradually increases as shown by the two-dot chain line in FIG. For this reason, it takes time for the fuel amount to increase in response to the predetermined time required for the load actually applied to the engine 1 to increase. Therefore, unlike the prior art, the fuel amount alone does not increase even though the load is not so large. As a result, it is possible to prevent the engine speed NE from becoming too high.

(Mouth) In the present embodiment, the idle-up correction term PE, which is the amount of increase in the fuel amount, is made variable according to the degree of load. Therefore, the type and degree of load Therefore, it is possible to surely prevent the engine speed NE from increasing even if the values are different.

The present embodiment is not limited to the above, and may be changed as follows.

(1) In the above embodiment, when calculating the idling-up correction term PE, a calculation was performed to cause a time delay in the increase in fuel, thereby limiting the rate of increase in fuel. In addition, the increase in the engine speed NE may be suppressed by delaying the timing of the increase in the fuel amount, that is, by causing a dead time. With such a configuration, the increase in the amount of fuel can be easily adjusted to the increase in the load, and the effect of preventing an increase in the engine speed NE can be obtained.

Further, the delay time when the timing is delayed may be made variable according to the degree of load. In this case, the above-described effects are more reliably achieved.

(2) Although the description has been omitted in the above-described embodiment, even when it is detected that the load has been reduced (or released), an operation for causing a time delay in reducing the fuel is performed as described above. Then, a restriction may be imposed on the rate of decrease in the amount of fuel. In this case, the fuel quantity alone does not suddenly decrease even though the load is not so small. As a result, it is possible to prevent the engine speed NE from dropping.

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

(4) In the above embodiment, the present invention is applied to the in-cylinder injection type engine 1. However, the present invention may be embodied in a type that performs so-called general stratified combustion or weak stratified combustion. For example, a type that injects fuel toward the back side of the umbrella of the intake valves 6a and 6b of the intake ports 7a and 7b is included. In addition, although fuel injection valves are provided on the intake valves 6a and 6b, those that directly inject into the cylinder bore (combustion chamber 5) are also included.

(5) Further, 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 diesel engine and the like.

Next, a program relating to the correction of the fuel increase amount according to the rotational speed in the idling rotational speed control device for a stratified combustion engine having the above-described configuration will be described with reference to a flowchart.

That is, FIG. 9 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. This is executed by an interrupt for each crank angle.

When the process proceeds to this routine, the ECU 30 first determines in step 201 whether an idle-up request has been issued. Here, the idle-up request is when an external load is applied. For example, when the driver turns on the air switch, when the power steering (power steering) is operated, the shift position is shifted from the N range. When switching to the D range, other electric loads are applied.

If it is not determined in step 201 that the idle-up request has been issued, 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, the process proceeds to step 202 to execute the idle-up. In step 202, idle up Read the engine speed NE immediately before performing.

Further, in the following step 203, a correction coefficient K is obtained and set based on the engine speed NE immediately before performing the idle-up. Here, in setting the correction coefficient K, a map as shown in FIG. 10 is taken into consideration. In other words, the higher the engine speed NE immediately before the idle-up is, the higher the value of the correction coefficient K is set to a smaller value (1.0 ≥ K 1> K2). > K3> ~> Κη> 0).

Then, in step 204, a value obtained by multiplying the expected control amount tΡΕ for the external load set as described above by the correction coefficient K set this time is set as the final idle-up amount PE.

Further, in step 205, the ECU 30 reflects the final idle-up amount PE calculated and set this time to the final injection amount QF. That is, the ECU 30 sets a value obtained by adding the final idle-up amount PE to the separately calculated basic injection amount QB ASE as the final injection amount QF. Then, the subsequent processing ends once.

As described above, in the above-mentioned "idle-up control routine", when stratified combustion is performed, if there is an idle-up request, the fuel injection amount is increased by the final idle-up amount PE. Is performed. When calculating the idle-up amount PE, a correction is made based on the engine speed NE immediately before the idle-up. Although not described here, when there is an idling-up request during homogeneous combustion, the intake air amount (throttle opening in the present embodiment) is reduced in the same manner as before when the idle-up request is made. By being increased, idle-up is performed.

Next, the operation and effect of the present embodiment will be described.

(A) In this embodiment, when the engine 1 is idling and the combustion state of the engine 1 is stratified combustion, a load is applied to the engine 1. In this case, 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 depending on the engine speed NE at that time. For example, as shown in Fig. 11, when the engine speed NE immediately before idle-up is high, the engine speed is lowered, and the fuel amount is increased by the same amount, the engine speed NE Change increases, and the engine speed NE rises too high.

In contrast, in the present embodiment, the idle-up amount is corrected according to the engine speed NE immediately before the idle-up is performed. More specifically, when the engine speed NE immediately before idling is high, the correction coefficient K is smaller than when the engine speed NE is low, and the degree of increase in the fuel amount (final idle-up amount). PE) becomes smaller. Therefore, when idling up, the engine speed NE does not increase too much.

(Mouth) In addition, by appropriately adjusting the correction coefficient K, it is possible to make the amount of change in the engine speed NE at the time of idling-up the same. Therefore, in such a case, an increase in the rotational speed NE as expected from the beginning can be expected.

Next, feedback control of the engine speed NE after idle-up (controlling the engine speed NE to the target speed by increasing or decreasing the final injection quantity QF) is explained. I do.

That is, FIG. 12 is based on the premise that stratified combustion is being performed at the time of idling of the engine 1, and furthermore, the “feedback control” executed by the ECU 30 after the above-described idle-up control is executed. Is a flowchart showing a “routine”, for example, executed by interruption every predetermined crank angle.

When the process proceeds to this routine, the ECU 30 first determines in step 301 whether the feedback control condition has been satisfied. Here, the feedback control condition refers to, for example, the actual engine Rotation speed NE force, that the target rotation speed has been reached once.

If the feedback control condition is not satisfied in step 301, 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 302 to execute the feedback control. In step 302, the current engine speed NE is read.

Further, in the following step 303, a correction coefficient L is obtained and set based on the engine speed NE read this time. Here, when setting the correction coefficient L, a map as shown in FIG. 13 is taken into consideration. In other words, the higher the engine speed NE immediately before reflecting the control amount DI to the final injection amount QF during feedback control, the higher the value of the correction coefficient L is set to a smaller value (1/31 <yS S ^ S ySn) (1. 0≥L 1> L 2> L 3 "> L n> 0).

Then, in step 304, a value obtained by multiplying the feedback integration constant tKDI by the correction coefficient L set this time is added to the previous control amount DIi-1, and the value is added to the current control amount DIi-1. Set as DI quantity. 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, in step 305, the ECU 30 reflects the control amount DI calculated and set this time on the final injection amount QF. Then, the subsequent processing ends once. As described above, in the above “feedback control routine”, when the feedback control condition is satisfied, the fuel injection amount is increased or decreased by the current control amount DI. When setting the control amount DI, a correction is made based on the engine speed NE immediately before the control amount DI is reflected. Although not described here, when 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 past. I You.

Next, the operation and effect of the present embodiment will be described.

(C) According to the present embodiment, in addition to the above-described effects, after the idle-up is performed, the 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 in the fuel amount is corrected according to the engine speed NE 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 does not vary.

More specifically, when the engine speed NE at the time when the control amount DI is reflected is high, the correction coefficient L and, consequently, the degree of increase and decrease in the fuel amount are smaller than when the engine speed NE is low. . Here, as described above, as the rotational speed NE at the time of increasing or decreasing increases, the change in the rotational speed NE when the amount of increase or decrease by the same amount tends to increase. Therefore, according to the present embodiment, the degree of increase / decrease in the engine speed when the engine speed NE is high is suppressed, and the increase / decrease in the engine speed NE during feedback control can also be suppressed.

The embodiments are not limited to the above, it may be modified as follows _c

(1) Although the description has been omitted in the above embodiment, when the load is reduced (or released), that is, when the idle-up is released, the engine speed NE immediately before the release of the idle-up is also determined. weight loss of the fuel quantity in this case may _c be corrected can be prevented a drop in the engine speed NE Te.

(2) In the above embodiment, during 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, the amount of intake air is reduced by an ISC mechanism consisting of an idle speed control parileb provided in a bypass intake passage that bypasses the throttle valve 23 provided in the intake passage and an actuator for opening and closing the valve. It may be adjusted. (3) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1; however, the present invention may be embodied in a so-called general stratified combustion or weak stratified combustion type. . For example, a type in which the fuel is injected toward the back side of the head of the intake valves 6a and 6b of the intake ports 7a and 7b is included. In addition, although fuel injection valves are provided on the intake valves 6a and 6b side, there are also types that directly inject into the cylinder bore (combustion chamber 5).

(4) Further, in the above-described 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 diesel engine.

Next, a program relating to the correction of the fuel increase amount in accordance with the fuel injection amount in the idle speed control device for a stratified combustion engine having the above-described configuration will be described with reference to a flowchart. Here, the fuel injection amount is used for correcting the fuel increase amount instead of the above-described rotation speed.

That is, FIG. 14 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. Executed at every interrupt.

When the process proceeds to this routine, the ECU 30 first determines in step 401 whether an idle-up request has been issued. Here, the idle-up request is when an external load is applied. For example, when the driver turns on the air switch, when the power steering (power steering) is operated, the shift position is shifted from the N range. When switching to the D range, other electric loads are applied.

If it is not determined in step 401 that the 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, the process proceeds to step 402 to execute idle-up. In step 402, the final injection amount QF (fuel injection amount) immediately before performing idle-up is read (recognized).

Further, in the following step 403, a correction coefficient K is obtained and set based on the final injection amount QF immediately before performing the idle-up. Here, when setting the correction coefficient K, a map as shown in FIG. 15 is taken into consideration. That is, as the final injection amount QF immediately before performing the idle-up is larger (ql <q2 く q3 く ... qn), the value of the correction coefficient K is set to a smaller value (1.0≥K1 〉 K2> K3> ~〉 Kn> 0).

In step 404, a value obtained by multiplying the expected control amount t PE for the external load set as described above by the correction coefficient K set this time is set as the final idle-up amount PE.

Further, in step 405, the ECU 30 reflects the final idle-up amount PE calculated and set this time on the final injection amount QF. That is, the ECU 30 sets a value obtained by adding the final idle-up amount P E to the separately calculated basic injection amount Q BASE as the final injection amount QF. Then, the subsequent processing ends once.

As described above, in the above-mentioned "idle-up control routine", when stratified combustion is performed, if there is an idle-up request, the fuel injection amount is increased by the final idle-up amount PE. Is performed. 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 homogeneous combustion, the intake air amount (throttle opening in the present embodiment) is the same as in the past when an idle-up request is made. Is increased, idle-up is performed.

Next, the operation and effect of the present embodiment will be described. (A) In this embodiment, when the engine 1 is idling and the combustion state of the engine 1 is stratified combustion, when the load is applied to the engine 1, the fuel injection valve 11 directly The amount of fuel to be supplied is increased. Here, at the time of stratified combustion, a change in the amount of fuel greatly affects combustion depending on the final injection amount QF at that time. For example, as shown in Fig. 18, when the final injection amount QF immediately before idling-up is large and the fuel amount is increased by the same amount as when the final injection amount QF is small, the amount of change in the engine speed NE increases, Engine speed NE is too high. Conversely, when the final injection amount QF immediately before idling-up is small, if an attempt is made to obtain the same change in rotation speed as when it is large, the amount of fuel required for idling-up will be large.

On the other hand, in the present embodiment, the idle-up amount is corrected according to the final injection amount QF immediately before the idle-up is performed. More specifically, as shown in Fig. 17, when the final injection amount QF at the time when the load is applied (immediately before the idle-up is performed) is large [Fig. 17 (b)], the injection amount QF is The correction coefficient K is smaller and the degree of increase in the fuel amount (final idle-up amount PE) is smaller than in the case of small [Fig. 17 (a)]. 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 become too high.

(Mouth) In addition, by optimizing the correction coefficient K in this way, it is possible to make the amount of change of the engine speed NE at the time of idling up the same. Therefore, in this case, an increase in the rotation speed NE as expected from the beginning can be expected.

(C) Further, as shown in FIG. 16, when the final injection amount QF immediately before idling-up is large, when the final injection amount QF is small, when the same rotational speed change is attempted to be obtained, However, the amount of fuel required for idle-up is small. As a result, more fuel Costs can be improved.

Next, the feedback control of the engine speed NE after the idle-up is performed (controlling the engine speed NE to the target speed by controlling the final injection amount QF to increase or decrease) will be described. .

That is, FIG. 19 shows that the ECU 30 is executed by the ECU 30 after the above-described idle-up control is executed, on the assumption that the stratified combustion is executed when the engine 1 is idling. 4 is a flowchart illustrating a “feedback control routine”, which is executed, for example, by interruption every predetermined crank angle.

When the process shifts to this routine, the ECU 30 first determines in step 501 whether or not the feedback control condition has been satisfied. Here, the feedback control condition includes, for example, that the actual engine speed NE has once reached the target speed after the idle-up.

Then, if the feedback control condition is not satisfied in step 501, it is determined that the feedback control has not yet been performed, and the subsequent processing is temporarily terminated.

In contrast, when the feedback control condition is satisfied, in the subsequent, the process proceeds to Step ₅ 0 2 in order to execute the feedback control. In step 502, the current final injection amount (fuel injection amount) QF is read.

Further, in the following step 503, a correction coefficient / δ is obtained and set based on the final injection amount QF read this time. Here, in setting the correction coefficient, a map as shown in FIG. 20 is taken into consideration. That is, the value of the correction coefficient S is set to a smaller value as the final injection amount QF immediately before reflecting the control amount DI to the final injection amount QF in the feedback control is larger (α 1 <α 2 and α 3 << αη). (1.0 ≥ β 1> S 2> S 3> ■■■> β η> 0).

Then, in step 504, the feedback integration constant t KD I Then, the value multiplied by the correction coefficient / S set this time is added to the previous control amount D l i-1 and the value is set as the current control amount DI. The feedback integration constant t KDI can take a positive value or a negative value depending on whether or not the current engine speed NE is smaller than the target engine speed.

Further, in step 505, ECU30 is the control amount D calculated this time.

I is reflected in the final injection amount QF. Then, the subsequent processing ends once. As described above, in the above “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 the control amount DI is reflected. Although not described here, when 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 past. I

^ o

Next, the operation and effect of the present embodiment will be described.

(C) According to the present embodiment, in addition to the above-described effects, after the idle-up is performed, the 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 does not vary.

More specifically, when the final injection amount QF at the time when the control amount DI is reflected is large, the degree of increase and decrease of the correction coefficient and, consequently, the fuel amount is smaller than when the injection amount QF is small. Here, as described above, the larger the final injection amount QF at the time of increasing or decreasing, the larger the tendency of the rotation speed NE to increase or decrease by the same amount. 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 the engine rotation speed during the feed-pack control is reduced. The increase / decrease of NE can also be suppressed.

Note that the embodiment is not limited to the above, and may be changed as follows.

(1) Although the description has been omitted in the above-described embodiment, when the load is reduced (or released), that is, even when the idle-up is released, the final injection amount QF immediately before the release of the idle-up is applied. Alternatively, the decrease in the fuel amount may be corrected. In this case, it is possible to prevent the engine speed NE from dropping.

(2) In the above embodiment, during 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, the idle air speed control valve provided in the bypass intake passage that bypasses the throttle valve 23 provided in the intake passage and the ISC mechanism consisting of the actuator for opening and closing the valve are used to suction air. You can also adjust the volume.

(3) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1; however, the present invention may be embodied in a so-called general stratified combustion or weak stratified combustion type. . For example, a type in which the fuel is injected toward the back side of the head of the intake valves 6a and 6b of the intake ports 7a and 7b is included. In addition, although fuel injection valves are provided on the intake valves 6a and 6b side, there are also types that directly inject into the cylinder bore (combustion chamber 5).

(4) Further, in the above-described embodiment, the present invention is embodied in the case of the gasoline engine 1 as the internal combustion engine, but may be embodied in the case of a diesel engine and the like. Industrial applicability

As described above in detail, according to the present invention, in the idle speed control device for an internal combustion engine capable of performing stratified combustion, the engine speed is increased by performing idle-up when a load is applied to the internal combustion engine. Can be prevented from rising too much Has an excellent effect of

Claims

The scope of the claims

1. an internal combustion engine capable of performing stratified combustion;

Operating state detecting means for detecting an operating state of the internal combustion engine;

Idle-up control means for performing idle-up when a load is applied to the internal combustion engine to suppress a decrease in the rotational speed of the internal combustion engine;

An idle speed control device for a stratified combustion internal combustion engine comprising:

The idle-up control means includes a fuel amount increasing means for increasing a fuel amount supplied to the internal combustion engine;

Correction means for correcting the fuel increase amount increased by the fuel amount increase means in accordance with the operation state detected by the operation state detection means;

An idle speed control device for a stratified combustion internal combustion engine, comprising:

2. The operating state detecting means includes a load input signal detecting means for detecting a load input signal indicating that a load is applied to the internal combustion engine,

The correction means includes a fuel amount response characteristic correction for causing a time delay in a response characteristic of the fuel amount increased by the fuel amount increasing means in response to the load input signal detected by the load input signal detection means. 2. The idle speed control device for a stratified combustion internal combustion engine according to claim 1, characterized by comprising means.

3. The stratified-combustion internal combustion engine according to claim 2, wherein the fuel amount response characteristic correcting means gradually increases the fuel amount in accordance with an elapsed time after the detection of the load input signal. Engine idle speed control device. 4. The idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein said fuel amount response characteristic correcting means increases the fuel amount after a predetermined time. δ. The load input signal detecting means further detects the type of load applied to the internal combustion engine, and the fuel amount increasing means determines the degree of the load based on the type of the load detected by the load input signal detecting means. 3. The idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein the amount of increase in the fuel is varied according to the following.

6. The idle-up control means further comprises intake air amount increasing means for increasing the intake air amount of the internal combustion engine when the combustion state of the internal combustion engine is homogeneous combustion. Idle speed control for stratified combustion internal combustion engine described in range 2

7. The idle speed control device further includes idle-up releasing means for releasing the idle-up when it is detected that the load on the internal combustion engine has been reduced,

The idle-up canceling means includes a fuel amount reducing means for reducing an amount of fuel supplied to the internal combustion engine;

Reduced fuel amount response characteristic correction means for causing a time delay in response characteristic of the fuel amount reduced by the fuel amount reduction means in response to the load input signal detected by the load input signal detection means. 3. The idle speed control device for a stratified combustion internal combustion engine according to claim 2, wherein:

8. The operating state detecting means includes a rotational speed detecting means for detecting the rotational speed of the internal combustion engine,

The correction means includes an increase correction means for correcting the fuel increase amount according to a detection result of the rotation speed detection means immediately before the idle-up control means performs the idle-up. The stratified combustion internal combustion engine according to claim 1 Idle speed control device.

9. The idling speed control apparatus for a stratified combustion internal combustion engine according to claim 8, wherein the fuel amount increased by the fuel amount increasing means is an expected amount.

10. If the rotation speed detected by the rotation speed detection means immediately before the idle-up is performed is high, the rotation speed is low, and the degree of increase in the fuel amount is small compared to the case. 9. The idling speed control device for a stratified combustion internal combustion engine according to claim 8, characterized in that:

11. After the fuel amount is increased by the fuel amount increasing means, the idle speed control device increases or decreases the fuel amount in accordance with the detection result of the rotation speed detecting means. Feedback control means for feedback controlling the engine;

The feedback control means corrects the increase or decrease of the fuel amount by the feedback control means in accordance with the detection result of the rotation speed detecting means at the time of increasing or decreasing the fuel amount by the feedback control means. 9. The idle speed control apparatus for a stratified combustion internal combustion engine according to claim 8, further comprising a correction unit.

1 2. When the rotation speed detected by the rotation speed detection unit at the time when the fuel amount is increased or decreased by the feedback control unit is high, the fuel amount is increased or decreased compared to when the rotation speed is low. The idling speed control apparatus for a stratified combustion internal combustion engine according to claim 11, characterized in that the degree of rotation is small.

13. The idle speed control device further comprises a fuel injection means capable of supplying fuel into a cylinder of the internal combustion engine.

The operation state detecting means detects a fuel injection amount from the fuel injection means. Comprising detection means,

The correction means includes an increase correction means for correcting the fuel increase amount in accordance with a detection result of the fuel injection amount detection means immediately before the idle-up is performed by the idle-up control means. The idle speed control device for a stratified combustion internal combustion engine according to claim 1, characterized in that:

14. The idle speed control device for a stratified combustion internal combustion engine according to claim 13, wherein the fuel amount increased by the fuel amount increasing means is an expected amount. 15. When the fuel injection amount detected by the fuel injection amount detecting means immediately before the idle-up is performed is large, the fuel injection amount is small. The idle speed control device for a stratified combustion internal combustion engine according to claim 13, wherein the degree of increase is small. 16. After the fuel amount is increased by the fuel amount increasing means, the idle speed control device increases or decreases the fuel amount in accordance with the result of detection by the fuel injection amount detecting means. Feedback control means for performing feedback control of the fuel injection amount, and feedback control means for controlling the fuel injection amount at the time when the fuel amount is increased or decreased by the feedback control means. 14. The idle speed control device for a stratified combustion internal combustion engine according to claim 13, further comprising feedback control increase / decrease correction means for correcting an increase / decrease amount of the fuel amount.

17. When the fuel injection amount detected by the fuel injection amount detecting means 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. 16. The idling speed control device for a stratified combustion internal combustion engine according to claim 16, wherein the degree of increase or decrease of the engine speed is small.