DE10315783B4 - Otto internal combustion engine with direct cylinder injection and associated control method - Google Patents

Abstract

Direct fuel injection direct injection gasoline engine having an exhaust gas recirculation system for recirculating and circulating a combustion gas in the cylinder (10), wherein
during a cold start, the exhaust gas recirculation system is operated and the fuel is supplied to the cylinder (10) during a compression stroke,
with means (3, 8) for determining intake port vacuum, wherein the exhaust gas recirculation system is operated when a certain intake port negative pressure is equal to or greater than a certain level.

Description

Technical field of the invention

The Invention relates to a spark ignition or an Otto internal combustion engine with direct cylinder injection, the fuel injected directly into a cylinder using a spark plug burns, and in particular a technology during the cold start of the engine.

In Recently, there has been the use of gasoline engines with direct cylinder injection, with which a lean burn can be achieved. An example for one Such a motor is a technology disclosed in Japanese Laid-Open Publication No. 11-324778 is disclosed in which it is stated that for simultaneous avoidance of oil thinning and Smoke generation during a cold start, an intake valve when exceeding a certain crankshaft angle after closing an exhaust valve opened and the fuel is injected while both valves are closed are. By avoiding an overlap of the opening periods From inlet and outlet valve hot combustion gas remains in one Combustion chamber, and the fuel is direct to facilitate atomization injected into the combustion chamber. This can be an attachment of Fuel on the piston head and on a cylinder wall and thus both oil dilution as also smoke formation can be prevented.

The post-published DE 100 52 344 A1 , which is considered to be the closest prior art teaches to exert pressure on the fuel when starting an internal combustion engine or a gasoline engine. The fuel is injected during a shift operation in a compression phase of the gasoline engine. A control unit for the engine measures the pressure acting on the fuel and allows or not the shift operation depending on this pressure.

The US 6,148,791 discloses to overlap an inlet and an exhaust valve while controlling the air / fuel ratio. The period of overlap increases as more air is needed. The air flow and the overlap can be changed via the valve path of the inlet valve. Under maximum load, the period of overlap is increased.

The US 6,340,014 B1 discloses to control an internal combustion engine from the start to the effectiveness of the catalyst in the stratified charge mode. In this case, a fluidized bed with a comparatively high proportion of fuel is injected around the ignition point, while at the same time prevailing in the rest of the cylinder space comparatively lean mixture.

There however, with this technology, the fuel during the cold start in an early Phase of the intake stroke is injected, is to carry out a homogeneous combustion formed a dense, homogeneous mixture, causing the fuel efficiency is deteriorated.

Summary the invention

The Invention therefore has the task of a gasoline engine with Cylinder direct injection and associated control method to provide with an improvement in the fuel efficiency during the Cold starts is achieved.

These The object is achieved by the subject matter of independent claims 1 and 8 solved.

Of the Otto engine according to the invention with direct cylinder injection, the injected into the cylinder Further, fuel burns using a spark plug an exhaust gas recirculation system which recirculates combustion gas for circulation in the cylinder, wherein the exhaust gas recirculation system while the cold start is operated and fuel during the compression stroke injected into the cylinder.

By the exhaust gas recirculation (EGR) system gets hot Exhaust gas returned to the cylinder, so that heats the intake air inside the cylinder and thereby the atomization the injected fuel is facilitated. Consequently, even can while a cold start an accumulation of fuel on a wall surface in the cylinder and consequently an oil dilution and a smoke development can be prevented. In addition, through the repatriation of the Exhaust gas lowered the combustion temperature and thus the NOx emission amount reduced. In addition, also during a cold start the fuel efficiency by injection of the fuel during the compression stroke improved.

advantageous embodiments are the subject of the dependent Claims.

It is advantageous if the engine further comprises means for detecting an intake passage negative pressure, and if the exhaust gas recirculation system is operated when the detected intake passage negative pressure is equal to or greater than a certain level. The reason for this is that EGR gas recirculation is difficult to accomplish with a small intake port vacuum, and in this case should be avoided better.

Preferably is this exhaust gas recirculation system a variable valve train having a valve overlap amount of the intake valve and exhaust valve. An increase in the valve overlap amount makes it easier for the exhaust gas in the exhaust duct, back into the exhaust To pour cylinders after it has returned to the inlet channel.

in the Compared to other cases should have a variable rate of change the valve overlap while the cold start is preferably increased become. In other cases, this means during one Intake stroke injection, occurs in a sudden increase in the EGR gas quantity an uneven EGR gas distribution on, so that no homogeneous mixture can form more, which ultimately a can cause unstable combustion. In contrast, is at a compression stroke injection a homogeneous mixture only in an area around the spark plug required. Therefore, stable combustion can be performed even then if an uneven EGR gas distribution due to a sudden increase the valve overlap amount is caused.

Of the variable valve train can be a mechanism that, if either the release valve or the exhaust valve is open, the lift stroke of the each other valve changes. Such a change the stroke can, for example, by a three-dimensional Cams are achieved, reducing the EGR gas recirculation rate without change the basic timing of inlet and outlet controlled can be.

Further can while the cold start of the ignition the spark plug to a time after reaching top dead center by delayed the piston become. Due to a delay of ignition timing, becomes the amount of secondary combustion (Combustion during of the power stroke) to increase the exhaust gas temperature increases, thereby the warm-up behavior a catalyst for preventing exhaust gas deterioration improved becomes.

preferably, becomes the operation of the exhaust gas recirculation system so controlled that the amount of EGR gas increases as the degree of ignition delay angle increases is increased. Due to the delay of the ignition timing is the interior of the combustion chamber through the injected fuel cooled, and the amount of attached to the cylinder wall or the like Fuel increases which can lead to unstable combustion. That is why through an increase in the amount of EGR gas to facilitate fuel atomization and increase the cylinder internal temperature stabilizes the combustion and the Formation of black smoke and the like prevented.

In a range in which the degree of the ignition delay angle is large and in which an unstable combustion is expected, the exhaust gas recirculation system preferably further controlled so that the EGR gas amount with increasing Degree of ignition delay angle decreases. Becomes the degree of ignition delay angle even further increased, shortens the combustion time so far that the combustion becomes unstable can. In this case, the amount of EGR gas to stabilize the combustion decreases, which increases the fuel concentration and a sufficient combustion time is ensured.

Summary the drawings

1 Fig. 12 is a schematic drawing showing the structure of a cylinder direct injection type Otto internal combustion engine according to the present invention;

2 is a diagram that details the operation of the variable valve train 1 shows;

3 FIG. 10 is a flowchart illustrating a first control operation during start of an engine according to FIG 1 shows;

4 FIG. 11 is a flowchart showing the details of a method for determining whether or not a compression stroke injection is possible during the course of the 3 shown method is shown;

5 FIG. 10 is a flowchart illustrating an adjustment control of the valve timing that takes place in the course of the in 3 shown method is performed;

6 FIG. 14 is a flowchart illustrating a second control operation during engine startup according to FIG 1 represents;

7 Fig. 15 is a graph showing the variation of the intake air amount depending on the valve overlap amount;

8th Fig. 15 is a graph showing the fluctuation of the internal EGR gas amount depending on the valve overlap amount;

9 Fig. 12 is a graph illustrating the valve overlap amount set depending on the degree of ignition delay angle;

10 Fig. 12 is a drawing illustrating a cam head shape of an exhaust cam; and

11 is a drawing showing details of the operating principle of a variable valve train, in which the in 10 illustrated cam is used.

Full Description of the advantageous embodiments

following the details become more advantageous, inventive embodiments with reference to the attached Drawings explained. To understand Descriptions to facilitate, in each drawing so far as possible the same structural elements assigned the same reference numerals, and duplicate descriptions are avoided.

1 is a schematic drawing illustrating the structure of the spark ignition engine according to the invention or Otto internal combustion engine with direct cylinder injection. The internal combustion engine 1 is a gasoline engine of the type in which by means of a Hochdruckinjektors 43 Gasoline or fuel directly into a combustion chamber 13 is injected, and at which the ignition and the combustion with a spark plug 17 is performed.

A piston head 11 is in a cylinder 10 of the motor arranged so that an opposite longitudinal movement in the drawing is possible. The piston head 11 is through a connecting rod 12 connected to a crankshaft (not shown), and converts an opposing movement into a rotational movement. In the piston head of the piston head 11 is a hollow 11A educated. The space between the piston head of the piston head 11 and the cylinder head 14 forms the combustion chamber 13 ,

The injector 43 , an inlet valve 23 , an outlet valve 24 , and the spark plug 17 are on the border of the cylinder head 14 to the combustion chamber 13 arranged. Of these components is the injector 43 Aligned so that the fuel is directed towards the trough 11A in the piston head 11 can be injected. Further, the spark plug 17 between the inlet valve 23 and the exhaust valve 24 near a the injector 43 opposite edge region of the trough 11A arranged. The inlet valve 23 is between the combustion chamber 13 and the inlet channel 15 arranged, whereas the exhaust valve 24 between the combustion chamber 13 and the outlet channel 16 is arranged. Both valves 23 and 24 are each by cams 21 and 22 actuated. A variable valve train 2 has the task of opening and closing the intake valve 23 and the exhaust valve 24 to vary.

The injector 43 is with a fuel tank 40 Connected, and is fueled by a pump 41 is pressurized. At this fuel line is a fuel pressure sensor 42 provided for detecting the fuel pressure.

The operation of the internal combustion engine 1 is powered by an engine ECU 3 controlled. The output signals of a water temperature sensor 5 measuring a coolant temperature of a crank angle sensor 6 that measures a crank angle, a vacuum sensor 8th that has a negative pressure in the inlet channel 15 downstream of a throttle 7 detected, the fuel pressure sensor 42 and the like go into the engine ECU 3 one. The engine-ECU 3 controls the operation of the variable valve train 2 , the spark plug 17 and the injector 43 ,

2 is a drawing, the details of the operation of the variable valve train 2 shows. By setting a rotation phase of the cams 21 and 22 with respect to their respective camshafts, an opening (valve lift) control timing of both the intake valve 23 as well as the exhaust valve 24 adjusted, reducing the duration of the valve overlap, while both the inlet valve 23 as well as the exhaust valve 24 are open, can be adjusted. Below is a setting for adjusting the opening times of the valves 23 and 24 in the direction of "early" (equivalent to a displacement of the valve lift curve to the left in the drawing) as setting on the Frühwinkelseite, whereas a setting for adjusting the opening times of the valves in the direction of "late" (equivalent to a displacement of the valve lift curve to the right in the Drawing) is referred to as setting on the late-angle side. The valve overlap amount may be adjusted by adjusting the intake valve 23 on the early angle side, by adjusting the exhaust valve 24 be increased to the late-angle side or by executing both settings. That is, it may be enough if at least the valve timing of the intake valve 23 or the exhaust valve 24 is adjustable.

Next, the operation is during the start of the engine 1 explained. 3 FIG. 10 is a flowchart showing a first control operation during engine start. FIG 1 shows. This control is provided by the engine-ECU unless otherwise specified 3 carried out, and is in a certain time cycle from the start to the stoppage of the engine 1 repeated.

In step S1, a decision is made as to whether the engine is running 1 is in a starting phase or not. The starting phase not only refers to the time when the engine is started, but covers a whole period from the start to the complete heating of the engine 1 after a few minutes. if the decision was made in step S1 that the engine 1 is in a start-up phase, the process proceeds to step S2, where it is determined whether the prevailing operating conditions allow a compression stroke injection. A detailed flowchart of this method of determination is in 4 shown. First, in step S21, an intake port negative pressure Pi and a fuel pressure Pf are detected by reading the output signals of the negative pressure sensor 8th and the fuel pressure sensor 42 detected. In the next step S22, the intake port negative pressure Pi is compared with a threshold value α. If the intake port negative pressure Pi is greater than the threshold value α, the process proceeds to step S23, in which the fuel pressure Pf is compared with a threshold value β. If the fuel pressure Pf is greater than the threshold value β, the process proceeds to step S24. Assuming that the fuel pressure Pf has been reached at which compression stroke injection can be efficiently performed, and an intake port negative pressure Pi at which a sufficient EGR effect can be obtained, it is decided in step S24 that compression stroke injection is possible. whereupon the process is terminated.

On the other hand, if it is decided in step S22 that the intake port negative pressure Pi is equal to or smaller than the threshold value α, the introduction of EGR gas is inhibited so that the temperature in the combustion chamber 13 is lower and the atomization of the fuel is difficult. Consequently, in addition to the attachment of fuel to the wall of the cylinder 10 no stable stratified combustion can be performed. Therefore, the process proceeds to step S25, where it is judged that the compression stroke injection is not possible. Further, if it is decided in step S23 that the fuel pressure Pf is equal to or smaller than the threshold value β, the fuel pressure is insufficient, so that the fuel injection volume required in the compression stroke can not be ensured, which in the worst case may result in a misfire. Therefore, the process proceeds to step S25, where it is judged that the compression stroke injection is not possible.

If it is decided as a result of this process that compression stroke injection is possible, the process proceeds to step S3 of the main process 3 continues, and the injection timing is set to the compression stroke. Subsequently, in step S4, a VVT target value is set so that the valve overlap becomes large, whereupon the process is terminated. Accordingly, the variable valve train 2 the phases of the cams 21 and 22 such that the valve timing of the intake valve 23 and the exhaust valve 24 reach the target value, thereby increasing the valve overlap amount, and the injector 43 injects the fuel during the compression stroke. By increasing the valve overlap amount, an internal EGR effect can be achieved by once in the exhaust duct 16 ejected combustion gas during the intake stroke back into the combustion chamber 13 is returned. In this way, the backflow amount of EGR gas is increased, thereby increasing the current compression ratio, the temperature in the combustion chamber 13 quickly lifted by the hot combustion gas, whereby the fuel atomization facilitates and attachment of the fuel to the inner wall of the Brennkammmer 13 and the like, and improves combustion stability through charge stratification, thereby preventing emission of black smoke. Consequently, the emission behavior is improved. In addition, stratified combustion with an air / fuel ratio of about 15 to 16, which is slightly leaner than the theoretical air / fuel ratio, is possible, whereby the fuel efficiency and emission performance can be improved.

On the other hand, if it is decided in step S2 that the compression stroke injection is not possible, the process proceeds to step S5 where the injection timing is set to the intake stroke; then the VVT target value is set in step S6 so that the valve overlap amount becomes small. In this case, the operating conditions do not meet the requirements for efficiently performing a compression stroke injection, and therefore intake stroke injection is performed. However, since the combustion speed in intake stroke injection is small, and an increase in the valve overlap amount in intake stroke injection during startup causes uneven EGR gas distribution within the combustion chamber 13 caused, which prevents a homogeneous mixture formation, the combustion can become unstable. Therefore, by reducing the valve overlap amount and suppressing the EGR gas backflow, stable combustion is performed, thereby preventing deterioration of the exhaust behavior.

If it is decided in step S1 that the engine 1 is not in the starting phase, the process proceeds to step S7 where the injection timing and the VVT target value are set according to the engine load and the engine speed. For example, the fuel is injected at a low speed and a low load during the compression stroke, and the stable combustion is performed to improve the fuel efficiency and the exhaust gas performance. At high engine speed and high load, the fuel is injected during the intake stroke, so that a homogeneous Mixture formed and a homogeneous combustion is performed to ensure a high output.

When adjusting the valve timing of the intake valve 23 and the exhaust valve 24 through the variable valve train 2 Preferably, the following control should be performed. 5 Fig. 10 is a flowchart showing such setting control, the control being in the course of the control process 3 is performed.

First, in step S31, a decision is made as to whether the engine is running 1 is in the starting phase. if it is decided in step S31 that the engine is in a starting phase, the process proceeds to step S32, where it is judged whether the compression stroke injection is set. If it is decided that the compression stroke injection is set, the process proceeds to step S33 in which a high rate of change of the valve overlap is set; in the subsequent step S34 becomes a current control amount of the variable valve train 2 calculated so that the set rate of change can be achieved. According to this process, in a compression stroke injection, the valve overlap amount is promptly set to the target value and the internal EGR gas amount is increased to increase the in-cylinder temperature and facilitate the fuel atomization, thereby enabling stable combustion.

Will in step 31 on the other hand decided that the engine 1 is not in a startup phase, or it is decided in step S32 that the compression stroke injection is not set, meaning that the intake stroke injection is set, the process proceeds to step S35 where a low rate of change of the valve overlap is set and the current one Control amount of the variable valve train 2 is calculated in the subsequent step S34 so that the set rate of change can be achieved. In this process, in particular, in a suction stroke injection, a sudden change in the valve overlap amount and thereby a sudden change in the internal EGR gas supply are avoided. Consequently, a sudden change of the combustion conditions and thus an unstable combustion is prevented.

Below are some other embodiments of operation during engine startup 1 explained in more detail. 6 FIG. 10 is a flowchart illustrating a second control operation during engine start. FIG 1 represents. Unless otherwise stated, this control will also be provided by the engine ECU 3 carried out and from the start to the stoppage of the engine 1 repeated at a certain time.

The contents of the branch, which proceeds to step S2 or S7 after step S1, and the branch, which proceeds to step S3 or S5 after step S2, are identical to those of in 3 illustrated first control operation identical, so that a detailed description is omitted. After the injection timing is set to the compression stroke in step S3, the process proceeds to step S51 where the degree of ignition delay angle is set. The degree of the ignition delay angle may be set with reference to a map depending on the operating conditions of the engine 1 like that through the coolant temperature sensor 5 measured coolant temperature and the through the vacuum sensor 8th measured negative pressure in the inlet channel 15 , was prepared. On this basis, a retardation process is carried out in which the ignition timing of the spark plug 17 at a time after reaching TDC (top dead center) (hereinafter simply referred to as "after TDC") by the piston head 11 is set at the transition from the compression stroke to the power stroke.

In the next step S52, the VVT target value is set. For example, the VVT target value is set to an overlap amount at which an intake air amount or an internal EGR gas amount becomes maximum according to the engine speed. 7 and 8th FIG. 15 is graphs illustrating the variations of the intake air amount and the internal EGR gas amount depending on the valve overlap amount. As in 7 As shown, when the engine speed is constant, there is a valve overlap amount at which the intake air amount becomes maximum. if this value is set for the valve overlap amount, the charge efficiency is maximized. Furthermore, the proportion of secondary combustion (combustion during the working cycle) is increased by a retardation of the ignition and the exhaust gas temperature is increased for faster activation of a catalytic converter. Consequently, exhaust of unburned HCs can be suppressed. As in 8th as shown, with respect to the internal EGR gas amount, there is a valve overlap amount at which the internal EGR gas amount becomes maximum at a constant engine speed. At this time, the valve overlap amount with the maximum intake air amount and the valve overlap amount with the maximum EGR gas amount may mutually overlap, but usually assume different values. When the valve overlap amount for the maximum EGR gas amount is selected, the effect of the facilitated fuel atomization and the early cylinder internal heat maximized. This maintains combustion stability while maximizing the reduction effect of black smoke emissions.

However, if the injection timing at startup is set to the intake stroke at step S5, the process proceeds to step S53 where the ignition timing is set to the early-angle side. In step S54, as in step S6 in FIG 3 , the VVT target value is then set to a small overlap amount. The control runs as in the first control mode. The same applies to the control outside the start.

Here, for explanation, an example has been taken in the case where the VVT target value is set based on the current engine speed to the valve overlap amount at which the intake air amount or the EGR gas amount becomes maximum. However, the VVT target value may also be set based on the degree of the ignition delay angle. As in 9 In this case, the valve overlap amount becomes maximum when the degree of the ignition delay angle ΔI becomes a predetermined value ΔIth. When the degree of the ignition delay angle ΔI is smaller than the predetermined value ΔIth, the valve overlap amount may be increased as the degree of the ignition delay angle increases, whereas if the degree of the ignition delay angle ΔI is greater than the predetermined value ΔIth, the valve overlap amount may be decreased as the degree of the ignition delay angle increases , The greater the degree of ignition retard angle, the more likely fuel to accumulate on the inner wall of the cylinder 10 on. Therefore, in an area where the degree of the ignition delay angle is relatively small, increasing the valve overlap amount with the degree of the ignition delay angle increases the internal EGR gas amount and the in-cylinder temperature in fuel injection, thereby facilitating fuel atomization. Consequently, an accumulation of the fuel on the inner wall of the cylinder 10 prevents the stability of the combustion is maintained and at the same time the production of black smoke is prevented. On the other hand, the combustion tends to become unstable with increasing degree of ignition delay angle. In an area where combustion is unstable, the internal EGR gas amount is reduced to improve combustion stability.

The value ΔIth is a threshold value based on experimental data or the like, and may be in the engine ECU 3 get saved. Further, it may be adjusted during operation depending on the combustion conditions (such as the exhaust air-fuel ratio or engine speed change).

In the previous descriptions, as in 2 illustrated an example of a change in the valve overlap by shifting the valve lift curve on the early-angle side and the late-angle side without changing the waveform explained. as 10 shows, however, the cam 22 for opening and closing the exhaust valve 24 For example, be shaped so that it has a different shape in the axial direction, in such a way that the cam 22 in a cross-sectional plane, only one cam head 22a and in another cross-sectional plane two cam heads 22a and 22b owns, leaving the exhaust valve 24 , as in 11 shown, reopened while the inlet valve 23 is open. Using this type of valvetrain, the valve overlap is increased to perform internal EGR. The cam 21 for opening and closing the inlet valve 23 can be shaped so that it has two cam heads, in such a way that the inlet valve 23 even then is opened while the exhaust valve 24 is open. With this construction, the valve overlap amount can be adjusted by shifting the cams 21 or 22 be changed in the axial direction of the camshaft, resulting in a simple construction and further improving the reliability of the valve train 2 allows.

Of course, instead of controlling the valve overlap amount, a feedback system may also be provided, the burned gas from the exhaust passage 16 directly into the inlet channel 15 returns.

As described above and according to the embodiments will the fuel atomization facilitates and the cylinder inside fast during the cold start heated by the fuel during the compression stroke is injected and EGR gas is introduced. Consequently, the combustion is stabilized, the emission of black Smoke and a deterioration of emission behavior prevented and the fuel efficiency improved.

Furthermore is due to the delay of the ignition timing on after TDC an early Activation of the catalyst achieved and the warm-up behavior improves, thereby preventing deterioration of the exhaust behavior can be.

Claims (14)

Direct fuel injection direct injection gasoline engine with an exhaust gas recirculation system for the recirculation and circulation of a combustion gas in the cylinder ( 10 ), in which During a cold start, the exhaust gas recirculation system is operated and the fuel to the cylinder ( 10 ) is supplied during a compression stroke, with a device ( 3 . 8th ) for determining intake port vacuum, wherein the exhaust gas recirculation system is operated when a certain intake port negative pressure is equal to or greater than a certain level. Internal combustion engine according to claim 1, wherein the exhaust gas recirculation system is a variable valve train ( 2 ) having a valve overlap amount of an intake valve ( 23 ) and an exhaust valve ( 24 ). Internal combustion engine according to claim 2, wherein during the Cold starts a variable rate of change the valve overlap compared to other cases elevated becomes. Internal combustion engine according to claim 2 or 3, wherein when either the inlet valve ( 23 ) or the exhaust valve ( 24 ) is open, the variable valve train ( 2 ) changes the stroke rate of the other valve. Internal combustion engine according to one of claims 1 to 4, wherein during the cold start the ignition timing of a spark plug ( 17 ) is delayed until a time after top dead center is reached by the piston. An internal combustion engine according to claim 5, wherein the operation the exhaust gas recirculation system is controlled to increase an amount of recirculated gas, when the degree of ignition timing retardation is increased. Internal combustion engine according to claim 6, wherein in one Range in which the degree of ignition timing delay is large and an unstable combustion is expected, the operation of the exhaust gas recirculation system is controlled so that the amount of recirculated gas is reduced, when the degree of ignition timing retardation is increased. Control method for a gasoline direct injection spark ignition internal combustion engine having an exhaust gas recirculation system for recirculating and circulating a combustion gas in the cylinder ( 10 ), wherein during a cold start the exhaust gas recirculation system operated and the fuel to the cylinder ( 10 ) is supplied during a compression stroke, with the step of determining an intake port vacuum, wherein the exhaust gas recirculation system is operated when a certain intake port negative pressure is equal to or greater than a certain level. Control method according to claim 8, wherein the exhaust gas recirculation system is a variable valve train ( 2 ) having a valve overlap amount of an intake valve ( 23 ) and an exhaust valve ( 24 ). A control method according to claim 9, wherein during the Cold starts a variable rate of change the valve overlap compared to other cases elevated becomes. A control method according to claim 9 or 10, wherein when either the inlet valve ( 23 ) or the exhaust valve ( 24 ) is open, the variable valve train ( 2 ) changes the stroke rate of the other valve. Control method according to one of claims 8 to 11, wherein during the cold start an ignition point of a spark plug ( 17 ) is retarded until after the top dead center is reached by the piston. A control method according to claim 12, wherein an operation the exhaust gas recirculation system is controlled so that the amount of recirculated gas is increased, when the degree of ignition timing retardation is increased. Internal combustion engine according to claim 13, wherein in one Range in which the degree of ignition timing delay is large and an unstable combustion is expected, the operation of the exhaust gas recirculation system is controlled so that the amount of recirculated gas is reduced, when the degree of ignition timing retardation is increased.