DE102015217812B4 - Control device for an internal combustion engine - Google Patents

Abstract

Control device for an internal combustion engine, which is designed to switch between spark-ignited combustion and premixed, compressed auto-igniting combustion, the control device providing a closing period in which both an inlet valve (12) and an outlet valve (22) for a period of an exhaust stroke to an intake stroke are closed to trap exhaust gas in a combustion chamber (7), and performing a closing period injection which injects fuel into the combustion chamber (7) during the closing period, and after the temperature rises in of the combustion chamber (7) performs the premixed, compressed auto-igniting combustion by burning the fuel injected during the closing period, comprising: a main combustion detection part (30) that detects generation of the premixed, compressed auto-igniting combustion; an exhaust valve control Mechanism (23), which in d he is able to variably change the opening and closing times of the exhaust valve (22); anda control part (3) which increases an injection amount of the fuel for the closing duration injection when the generation of the premixed, compressed auto-ignition combustion has progressed beyond a limit value, and which the opening and closing times of the exhaust valve (22) immediately before reaching the closing duration as a function of the injection quantity for the closing duration injection, the control part (3) determining the opening and closing times of the exhaust valve (22) such that even if the closing duration injection quantity is increased, a value of G / F in a predetermined range, where G / F is a ratio of an amount G of gas remaining in a cylinder to an amount F of fuel in the cylinder.

Description

[TECHNICAL AREA]

The present invention relates generally to a control device for internal combustion engines, in particular to a control device for internal combustion engines equipped with a premixed, compressed auto-ignition combustion function.

[STATE OF THE ART]

A typical form of combustion that occurs in internal combustion engines, e.g. Gasoline engines, widely used, are the form of spark-ignited combustion, in which a spark plug creates a spark discharge to ignite a fuel-air mixture. In recent years, gasoline engines have been developed which use a premixed, compressed auto-igniting combustion as a form of combustion, which introduces a gas that ignites at high temperatures into the cylinder in order to ignite the mixture itself. The premixed, compressed self-igniting combustion is usually called HCCI combustion (Homogenous Charge Compressoin Ignition).

HCCI combustion compresses the mixture in the cylinder to increase its temperature and pressure, causing the mixture to auto-ignite without the need for spark ignition. The HCCI combustion is intended to initiate the self-ignition of the mixture simultaneously at several points in each combustion chamber and has the advantages that the combustion duration is shorter and the thermal efficiency is higher than with spark-ignited combustion.

Some of the HCCI internal combustion engines described above are designed to have a Negative Valve Overlap (NVO) period in which the intake and exhaust valves are closed for a period of time from the exhaust stroke to the intake stroke in order to absorb some of the exhaust gas to be enclosed in the combustion chamber of the engine as internal EGR gas (exhaust gas recirculation), whereby the cylinder temperature, i.e. the temperature in the combustion chamber, is increased. Some of the HCCI internal combustion engines are designed to perform NVO injection, i.e., injection of fuel into the combustion chamber during the NVO period, so that the fuel is exposed to high pressure and temperature and therefore burns immediately, which in the Also called NVO combustion in the following. This causes the cylinder pressure to increase in the compression stroke prior to the main combustion period, thereby eliminating the likelihood of misfire in the main combustion period.

The exhaust gas emitted from the internal combustion engines in NVO operation hardly contains any unburned fuel if the fuel is excessively burned in the main combustion period. In a period of NVO combustion immediately after such excessive combustion, the rise in cylinder temperature is usually suppressed, so that the combustion of fuel in a subsequent main combustion cycle will be deteriorated because the internal EGR gas contains less unburned fuel.

In order to alleviate the problem described above, the document discloses JP 2013 - 19 345 A (See Patent Literature 1), a control system for an internal combustion engine which is developed to increase the amount of fuel injected into the engine in the NVO period immediately before fuel is excessively burned in the main combustion period in order to achieve NVO combustion improve, which increases the cylinder temperature. This prevents the deterioration of the combustion of the fuel in the main combustion cycle following the main combustion period in which the fuel is excessively burned.

US 2010/0 312 455 A1 discloses a control device for an internal combustion engine having a homogeneous compression ignition (HCCI) combustion mode in which a premixed air-fuel mixture is compressed in a combustion chamber so that auto-ignition of the engine occurs. Combustion of the mixture is performed without an ignition spark while both an intake valve and an exhaust valve are closed at a transition time from an exhaust stroke to an intake stroke of the engine.

US 2007/0 215 096 A1 discloses a control device for an internal combustion engine that performs spark ignited combustion and compression ignited combustion. With the control performed by the control device, the compression ignition combustion is stabilized even if the engine or an actuator for selectively executing the spark ignition and compression ignition combustion goes into a deteriorated state due to, for example, deposits.

[LIST OF PRINTED FONTS]

[PATENT LITERATURE 1]

Copy JP 2013 - 19 345 A

[SUMMARY OF THE INVENTION]

[PROBLEM TO BE SOLVED BY THE INVENTION]

In the control system according to Japanese Patent First Publication JP 2013 - 19 345 A however, increasing the amount of fuel injected in the NVO period to improve NVO combustion results in an increase in the amount of gas in the cylinder in the NVO period, resulting in an increase in the ratio just before the next main combustion cycle an amount G of gas remaining in the cylinder results in an amount F of fuel in the cylinder (which is hereinafter referred to as the G / F ratio). This causes the G / F ratio to decrease below a misfire limit in the next main combustion cycle so that the misfire can occur or the engine output torque can undesirably drop.

It is therefore an object of the present invention to provide a control device for an internal combustion engine capable of minimizing the likelihood of a misfire in a period of premixed compressed auto-ignition or a drop in engine output torque.

This object is achieved by a control device with the features of claim 1. Advantageous further developments emerge from the dependent claim.

[THE SOLUTION OF THE PROBLEM]

An aspect of the control device for an internal combustion engine according to the invention is a control device which is designed to switch between spark-ignited combustion and premixed, compressed-autoignition combustion, the control device providing a closing period in which both an intake valve and an exhaust valve for a period of an exhaust stroke to an intake stroke are closed to trap exhaust gas in a combustion chamber, and they perform a closing duration injection, which injects fuel into the combustion chamber during the closing duration, and after the temperature rises in the combustion chamber by a combustion of the performs the premixed, compressed self-igniting combustion during the closing period of the injected fuel. The control device includes a main combustion detection part that detects generation of the premixed, compressed auto-ignition combustion, an exhaust valve control mechanism that is able to variably change opening and closing timings of the exhaust valve, and a control part that controls an injection amount of the fuel for the closing duration injection is increased when the generation of the premixed, compressed auto-igniting combustion has progressed beyond a limit value, and the opening and closing times of the exhaust valve immediately before reaching the closing duration as a function of the injection quantity for the closing duration Injection delayed, wherein the control part determines the opening and closing times of the exhaust valve such that even if the closing duration injection amount is increased, a value of G / F is in a predetermined range, where G / F is a ratio of an amount G of in one cylinder remaining m is gas to an amount F of fuel in the cylinder.

[EFFECTS OF THE INVENTION]

In accordance with one aspect of the invention, it is possible to minimize the likelihood of misfire or a drop in torque in the process of premixed, compressed auto-igniting combustion.

Figure list

• 1 Fig. 13 is a conceptual block diagram of a control device for an internal combustion engine according to an embodiment of the invention.
• 2 Fig. 13 is a flowchart explaining processes for stabilizing combustion in a control device for an internal combustion engine according to an embodiment of the invention.
• 3 Fig. 13 is a timing chart showing a change in the ratio of an amount of residual gas to an amount of fuel in the cylinder caused by the combustion stabilization processes in a control device for an internal combustion engine according to an embodiment of the invention.
• 4th Fig. 13 is a graph representing a percentage of change in engine load caused by a closing duration injection amount and an exhaust valve delay in a control apparatus for an internal combustion engine according to an embodiment of the invention.
• 5 Fig. 13 is a graph representing a ratio of an amount of residual gas to an amount of fuel in the cylinder generated by a closing duration injection amount and an exhaust valve delay in a control device for an internal combustion engine according to an embodiment of the invention.

[DESCRIPTION OF THE EMBODIMENT]

An embodiment of the invention is described in detail below with reference to the drawings.

As in 1 shown includes a vehicle 1 equipped with a control device for an internal combustion engine according to an embodiment of the invention, an internal combustion engine 2 and an ECU 3 (Electric Control Unit) that functions as a control part.

In the engine 2 is a cylinder 5 educated. A piston 6th is in the cylinder 5 arranged to move vertically back and forth. A combustion chamber 7th is at an upper portion of the cylinder 5 Are defined. A cylinder pressure sensor 30th is in the combustion chamber 7th installed to the cylinder pressure, i.e. the pressure in the cylinder 5 , to eat.

The motor 2 is a four-stroke gasoline engine that runs through a sequence of four strokes: the intake stroke, the compression stroke, the power stroke and the exhaust stroke, in a period of time in which the piston 6th himself in the cylinder 5 moves up and down.

The piston 6th is connected to a crankshaft through a connecting rod, not shown. The connecting rod converts the up and down movement of the piston 6th into the rotational movement of the crankshaft.

A spark plug 8th and an injector 9 are in the combustion chamber 7th Installed. The spark plug 8th is with an electrode that is in the combustion chamber 7th protrudes, equipped. The ignition timing of the spark plug 8th are regulated by an igniter, not shown. The injector 9 includes a direct injection type fuel injection valve that feeds fuel supplied from a fuel tank by a fuel pump, not shown, into the combustion chamber 7th injects.

The motor 2 has an intake duct 11 and an exhaust duct 21st on. The intake duct 11 connects the combustion chamber 7th with an intake duct 14a which will be described later. In the intake duct 11 is an inlet valve 12 Installed.

The inlet valve 12 is opened or closed to the connection between the intake tract 14a and the combustion chamber 7th enable or block. The opening or closing of the inlet valve 12 is through an intake valve control mechanism 13 reached.

The intake valve control mechanism 13 can be implemented by an electromagnetic valve timing mechanism that controls the intake valve 12 by means of an electromagnetic actuator, which consists of an electromagnet and a spring, opens or closes. In particular, is the intake valve control mechanism 13 designed to energize the electromagnet to a movable portion that connects to the inlet valve 12 connected to tighten, reducing the inlet valve 12 is moved in a valve opening direction while always being urged in a valve closing direction by the spring.

The intake valve control mechanism 13 is electrical with the ECU 3 connected so that the excitation or the de-excitation of the electromagnet through the ECU 3 is controlled. Hence the ECU 3 able to open and close the intake valve 12 to change and thereby a valve opening time of the intake valve 12 easy to regulate.

The intake valve control mechanism 13 may alternatively be implemented by a hydraulic valve timing mechanism using a hydraulic actuator instead of an electromagnetic actuator. The intake valve control mechanism 13 may alternatively be implemented as a mechanical valve timing mechanism capable of timing the intake valve opening and closing 12 using cam members such as a main cam and an auxiliary cam.

The intake valve control mechanism 13 can be designed to the opening and closing times and the amount of lift of the intake valve 12 continuously by regulating the excitation current of the electromagnet by the ECU 3 to change.

An intake pipe 14th is with the intake duct 11 connected. In the suction pipe 14th is the intake tract 14a formed with the intake duct 11 is connected. An electronically controlled throttle valve 15th is in the intake stroke 14a Installed. The throttle valve 15th is electrical with the ECU 3 connected.

The throttle valve 15th is designed to open its throttle opening in response to a control signal from the ECU 3 is controlled to the amount of intake air into the engine 2 to regulate.

An exhaust valve 22nd is in the exhaust duct 21st Installed. The exhaust valve 22nd is opened or closed to the connection between an exhaust tract 24a which will be described later and the combustion chamber 7th enable or block. The opening / closing of the exhaust valve 22nd is operated by an exhaust valve control mechanism 23 reached.

The exhaust valve control mechanism 23 is structurally consistent with the intake valve control mechanism described above 13 and a detailed explanation of this is omitted here. The exhaust valve control mechanism 23 changes the opening and closing times of the exhaust valve 22nd by controlling energization or de-energization of an electromagnet by the ECU 3 in a variable way. The exhaust valve control mechanism 23 may alternatively be implemented as a hydraulic valve control mechanism using a hydraulic actuator instead of an electromagnetic actuator. The exhaust valve control mechanism 23 may alternatively be implemented by a mechanical control mechanism capable of changing the opening and closing timings of the exhaust valve through the use of cam members such as a main cam and an auxiliary cam. Hence the ECU 3 able to set the valve opening time of the exhaust valve 22nd to regulate in a simple way.

An exhaust pipe 24 is to the exhaust duct 21st connected. In the exhaust pipe 24 is the exhaust tract 24a formed in connection with the exhaust duct 21st stands.

The engine built in this way 2 is a spark-ignited engine in which a mixture of intake air, its flow rate through the throttle valve 15th is controlled, and from injected fuel through the spark plug 8th ignited and burned. It is possible to achieve premixed, compressed auto-igniting (i.e., HCCI) combustion by adjusting the intake valve opening and closing times 12 and the exhaust valve 22nd by the intake valve control mechanism 13 and the exhaust valve control mechanism 23 The amount of fuel injected and the air drawn in are regulated within the combustion chamber 7th to pre-mix and to compress the mixture so that it ignites by itself. In other words, is the engine 2 Designed to switch between the spark-ignited mode of spark-ignited combustion and the HCCI mode of HCCI combustion.

In this embodiment, the engine thus constructed 2 through the ECU 3 controlled in its operating condition. The ECU 3 is formed from a processing unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory, working memory), a ROM (Read Only Memory), a flash memory, an input connection and an output connection.

In the ROM of the ECU 3 is a program saved to the computing unit as an ECU 3 to work with a large number of control constants and with a large number of maps. Specifically, the CPU executes a program stored in the ROM to make the computer unit function as an ECU.

A variety of sensors, such as the cylinder pressure sensor 30th , an accelerator pedal position sensor 31 and a crank angle sensor 32 , are with the input side of the ECU 3 connected. The accelerator pedal position sensor 31 measures an accelerator pedal position that is a position of an unillustrated accelerator pedal operated by a driver as an acceleration request, for example. The crank angle sensor 32 detects a rotation angle of the crankshaft. The ECU 3 calculates the engine speed based on the result of the detection input from the crank angle sensor 32 .

A variety of controlled objects, such as the spark plug described above 8th who have favourited the injector 9 , the throttle valve 15th , the intake valve control mechanism 13 and the exhaust valve control mechanism 23 , are with the output side of the ECU 3 connected.

The ECU 3 is designed to distinguish between spark ignited combustion and HCCI combustion according to the engine operating conditions 2 switch. In particular, the ECU determines 3 whether an operating range of the engine 2 is in a spark-ignited combustion region or in a HCCI-combustion region, by looking up using a combustion region map in which engine speed and engine load are parameters and then selecting either spark-ignited combustion or HCCI combustion, to be performed based on the determination.

The ECU 3 calculates an engine load based on the accelerator pedal position obtained from the accelerator pedal position sensor 31 is input, and the engine speed, which is determined by the result of the crank angle sensor 32 input detection is derived.

In the HCCI mode in which the HCCI combustion is performed, the ECU determines 36 the valve timing of the intake valve 12 and the exhaust valve 22nd and the amount of by the injector 9 fuel to be injected based on the engine speed and the engine load to output an engine load requested by the driver.

In the HCCI mode, the ECU sets 3 a closing period (ie an NVO period) in which both the inlet valve 12 as well as the exhaust valve 22nd for a period from the exhaust stroke to are closed to the intake stroke. The ECU 3 performs a dwell injection in which fuel is passed through the injector 9 is injected during the closing period. The ECU executes the closing duration injection 3 also through a main injection in which a larger amount of fuel than in the closing duration injection is injected for a predetermined period of time from the intake stroke to the compression stroke.

The closing duration injection does not have to be completely completed within the closing duration, but at least more than half of the closing duration injection must be carried out in the closing duration. The closing duration injection can be carried out completely in the closing duration. The duration of the closing duration injection are as a function of the operating conditions of the engine 2 set.

The ECU 3 monitors the cylinder pressure input from the cylinder pressure sensor 30th , and determines that the main combustion was excessive combustion when the main combustion period in which the cylinder pressure is detected by the cylinder pressure sensor 30th , exceeds a predetermined pressure limit value, has progressed beyond a predetermined limit value for the excessive combustion. Then the ECU increases 3 the amount of fuel to be injected in the process of closing duration injection by a specified closing duration injection increment. The ECU 3 also reduces the amount of fuel to be injected in the main injection immediately after the process of the closing duration injection, in which the injection amount was increased by one closing duration injection increment. In short, the total injection amount of fuel for the closing duration injection and the main injection is controlled to be kept constant. The cylinder pressure sensor 30th represents a main combustion detection part according to the invention.

The pressure limit value is a cylinder pressure at which it is possible to recognize main combustion, and it has been experimentally determined in advance and in the ROM of the ECU 3 saved. The limit value for excessive combustion is a rotation angle of the crankshaft at which it is possible to recognize excessive combustion, and has been experimentally derived in advance and in the ROM of the ECU 3 saved. The closing duration injection increment is an increment of the injection amount of fuel that compensates for the lack of fuel when the main combustion is excessive combustion, and is derived experimentally and in the ROM in the ECU 3 saved.

When it is determined that the main combustion was the excessive combustion, the ECU decelerates 3 the opening and closing times of the exhaust valve 22nd , just before the closing time is reached, by a preselected exhaust valve delay. The exhaust valve delay is an angular amount that the crankshaft must be rotated around the opening and closing times of the exhaust valve 22nd to delay. For example, the exhaust valve retardation is derived from a map, described later, which determines the exhaust valve retardation as a function of the closing duration injection amount. The map is derived experimentally and in the ROM of the ECU 3 saved.

In this way, the opening and closing timings of the exhaust valve 22nd retarded, reducing the amount of gas remaining in the cylinder prior to the closing duration injection operation to reduce the G / F ratio in the following cycle. Thus, in the following cycle of main combustion, the G / F ratio is decreased below or equal to a misfire limit, and thereby the likelihood of misfire or a drop in torque is minimized.

The combustion stabilization processes of a thus constructed control device for internal combustion engines according to this embodiment will be described with reference to FIG 2 explained. The processes for stabilizing the combustion, which are described below, are started when entering the HCCI mode, in which the HCCI combustion is started, and are carried out at a given time interval, and are carried out when entering the spark-ignited mode Mode in which spark-ignited combustion is carried out is ended.

In step S11 calculates the ECU 3 first the engine load based on accelerator pedal position and engine speed. In step S12 determines the ECU 3 next, the valve timing and the injection amount of fuel based on the engine speed and the engine load to control a variety of controlled objects.

In the next step S13 determines the ECU 3 whether or not the duration of the main combustion has advanced beyond a limit value for the excessive combustion described above. If it is determined that the main combustion period has not progressed beyond the excessive combustion limit, the ECU ends 3 the operations.

If in step S13 When it is determined that the main combustion period has advanced beyond the excessive combustion limit, the ECU increases 3 in step S14 the Closing duration injection amount by the closing duration injection increment described above and also reduces the main injection amount by the closing duration injection increment. In the next step S15 decelerates the ECU 3 the opening and closing times of the exhaust valve 22nd by the exhaust valve delay described above based on the increased closing duration injection amount.

The effects of the combustion stabilization processes described above are referenced to 3 described below.

When in a conventional control device for internal combustion engines as shown in FIG 3A As shown, the main combustion is the excessive combustion and has progressed (indicated by E / C in the drawing), then the closing period injection amount is increased, but in the closing period the amount of gas remaining in the cylinder is increased because the closing period injection Injection quantity is increased in order to activate the closing period combustion, ie the combustion in the closing period. As a result, the G / F ratio before a subsequent main combustion cycle is greater than or equal to the misfire limit, which can lead to a misfire or a drop in torque.

In this in 3B As shown in the embodiment shown, the closing duration injection amount is increased when the main combustion was excessive combustion and has progressed (indicated by E / C in the figures). In addition, the opening and closing times of the exhaust valve 22nd delayed by the exhaust valve delay, corresponding to the increased closing duration injection quantity. The delay in the opening and closing times of the exhaust valve 22nd causes, as illustrated in “PISTON SPEED” in 3B that the exhaust valve 22nd is opened in a period of time in which the piston speed increases (as enclosed by the dashed line in the drawing), whereby an increased amount of burnt gas is emitted.

The delay in the opening and closing times of the exhaust valve 22nd causes, as illustrated in "CYLINDER VOLUME" in 3B that the exhaust valve 22nd is opened in a period of time in which the cylinder volume decreases (as enclosed by the dashed line in the drawing), thereby emitting an increased amount of burned gas. This results in a drop in the amount of gas remaining in the cylinder during the closing period, causing the G / F ratio to drop below the misfire limit before a subsequent cycle of main combustion, thereby minimizing the likelihood of misfire or a drop in torque.

The map in the internal combustion engine control apparatus that determines the exhaust valve delay as a function of the closing duration injection amount is described below.

4th Fig. 13 is a graph representing a percentage (%) of change in engine load associated with the closing duration injection amount and the exhaust valve delay. In order to avoid a change in the engine load resulting from the adjustment of the opening and closing times of the exhaust valve 22nd linked to the increase in the duration of the injection quantity, the opening and closing times of the exhaust valve 22nd adjusted within an adjustment range in which the change in engine load is between + 1% and -1% (ie an area enclosed by the thick line in the figure).

5 Fig. 13 is a graph representing the value of the G / F ratio produced by the closing duration injection amount and the exhaust valve delay. An area enclosed by the dashed line in the figure indicates the adjustment area in 4th at. To a change in the G / F ratio resulting from the increase in the closing duration injection quantity in the adjustment range of 4th to avoid, the opening and closing times of the exhaust valve 22nd regulated. For example, the exhaust valve delay is determined such that the value of the G / F ratio remains in a target adjustment range enclosed by the thick line in the figure.

As described above, in this embodiment, the ECU is 3 which determines that the main combustion was excessive combustion when the period of the main combustion, in which period is determined by the cylinder pressure sensor 30th The measured cylinder pressure exceeds a preselected pressure limit value, has progressed beyond the preselected limit value for the excessive combustion, and which increases the injection quantity of the fuel for the closing duration injection by the preselected closing duration injection increment and which increases the opening and closing times of the exhaust valve 22nd is delayed as a function of the injection amount of the fuel for the closing period injection immediately before the closing period is reached.

This delays the opening and closing times of the exhaust valve 22nd as a function of the injection amount of the fuel for the closing duration injection, so that the exhaust valve 22nd is open at a time when a large amount of burned gas is emitted. Therefore, the large amount of burned gas is discharged to reduce the amount of gas remaining in the cylinder before the closing duration injection operation, so that the amount of residual gas before a subsequent main combustion cycle is reduced, thereby reducing the likelihood of misfire or dropping in torque is minimized in the process of premixed, compressed auto-igniting combustion.

The ECU 3 also increases the amount by which the opening and closing times of the exhaust valve 22nd can be delayed immediately before reaching the closing period when the injection amount of the fuel for the closing period injection is increased.

This determines the opening and closing times of the exhaust valve 22nd more delayed immediately before reaching the closing period when the injection quantity of the fuel for the closing period injection is increased. This enables a large amount of burned gas to be emitted as the injection amount of the fuel for the closing period injection increases to decrease the amount of gas remaining in the cylinder before the closing period injection operation, thereby reducing the amount of residual gas before a subsequent cycle of main combustion, which minimizes the likelihood of misfire or a drop in torque in the premixed, compressed autoignition combustion process.

Although the embodiment of the invention has been disclosed, it will be apparent to one skilled in the art that all possible modifications can be made to the embodiment shown without departing from the principle of the invention, and such modifications and their equivalents are included in the appended claims.

List of reference symbols

1

vehicle

2

Engine (combustion engine)

3

ECU (control part)

7th

Combustion chamber

9

Injector

12

Inlet valve

21st

Exhaust duct

22nd

outlet valve

23

Exhaust valve control mechanism

30th

Cylinder pressure sensor (main combustion detection part)

Claims (2)

Control device for an internal combustion engine, which is designed to switch between spark-ignited combustion and premixed, compressed auto-igniting combustion, the control device providing a closing period in which both an inlet valve (12) and an outlet valve (22) for a period of an exhaust stroke to an intake stroke are closed to trap exhaust gas in a combustion chamber (7), and performing a closing period injection which injects fuel into the combustion chamber (7) during the closing period, and after the temperature rises in the combustion chamber (7) carries out the premixed, compressed auto-igniting combustion by a combustion of the fuel injected during the closing period, comprising: a main combustion detecting part (30) which detects generation of the premixed compressed autoignition combustion; an exhaust valve control mechanism (23) capable of variably changing the opening and closing timings of the exhaust valve (22); and a control part (3) which increases an injection amount of the fuel for the closing duration injection when the generation of the premixed, compressed auto-igniting combustion has progressed beyond a limit value, and which the opening and closing times of the exhaust valve (22) immediately before reaching the closing duration as a function of the injection quantity for the closing duration injection, the control part (3) determining the opening and closing times of the exhaust valve (22) such that even if the closing duration injection quantity is increased, a value of G / F in a predetermined range, where G / F is a ratio of an amount G of gas remaining in a cylinder to an amount F of fuel in the cylinder. Control device for an internal combustion engine according to Claim 1 wherein the control part (3) increases an amount by which the opening and closing times of the exhaust valve (22) are delayed immediately before reaching the closing period, when the injection amount of the fuel for the closing period injection is increased.

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