JP2015031241A - Combustion state control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion state control device of an internal combustion engine capable of avoiding generation of early combustion while preventing deterioration of exhaust emission.SOLUTION: Under a condition that combustion of mixed gas is detected at timing different from output timing of an ignition signal, an ECU 51 increases an amount of exhaust gas returned to a combustion chamber 10 and executes combustion state control which stops output of the ignition signal to an ignition plug 20 and transfers to self-ignition operation. Also, under the condition that a predetermined ignition condition is met after executing the combustion state control, the ECU 51: reduces an amount of intake air sucked into a cylinder 6 by controlling a throttle valve 18 in a manner that adjusts an opening thereof to a closing side; reduces the amount of the exhaust gas returned to the combustion chamber 10; and outputs the ignition signal to the ignition plug 20.

Description

  The present invention relates to a combustion state control device for an internal combustion engine, and more particularly to a combustion state control device for an internal combustion engine that suppresses combustion of an air-fuel mixture at a timing different from the ignition timing due to ignition of a spark plug.

Recently, in a spark ignition type gasoline engine mounted on a vehicle, a high compression ratio has been promoted from the viewpoint of improving fuel efficiency and output. In such an engine having a high compression ratio, for example, during low-speed and high-load operation, the compression pressure increases by controlling the intake air amount to a large value and a high compression ratio, and because of the low speed, ignition is performed. Due to the time available for normal flame propagation, premature combustion called preignition due to self-ignition tends to occur. Further, early combustion is likely to occur even when the intake air temperature in the cylinder is high.
If early combustion occurs, the temperature of a part of the piston or cylinder may rise abnormally, and a part of metal constituting the cylinder may be melted or the piston may be seized.

  Conventionally, as an example of suppressing early combustion, as described in Patent Document 1, for example, the fuel injection amount is increased to reduce the temperature in the combustion chamber by enriching the air-fuel ratio, As described in Patent Document 2, the injection timing is retarded so that fuel is injected during the compression stroke, and the period from the injection timing to ignition is shortened, that is, the heat receiving period of the fuel is shortened. Things are known.

JP 2011-85098 A JP 2002-339780 A

However, those described in Patent Document 1 both reduce the temperature in the combustion chamber by enriching the air-fuel ratio and those described in Patent Document 2 by retarding the injection timing. Therefore, there is a problem that incomplete combustion occurs, a large amount of unburned gas is discharged, and exhaust emission deteriorates.
In addition, those described in Patent Documents 1 and 2 show that, under conditions that induce significant early combustion, early combustion occurs even if the air-fuel ratio is enriched or the injection timing is retarded. May not be avoided.

  The present invention has been made paying attention to the above problems, and provides a combustion state control device for an internal combustion engine that can prevent the occurrence of early combustion while preventing the exhaust emission from deteriorating. It is intended to do.

  A first aspect of the present invention is a combustion state of an internal combustion engine comprising an ignition plug that ignites an air-fuel mixture in a combustion chamber of a cylinder provided in the internal combustion engine, and an ignition signal output unit that outputs an ignition signal to the ignition plug A control device, comprising a combustion detector for detecting that the air-fuel mixture has been combusted in the combustion chamber, and an exhaust gas recirculation amount adjusting member for adjusting the amount of exhaust gas recirculated into the combustion chamber, and outputting an ignition signal The exhaust gas recirculation amount adjusting member is controlled to increase the amount of exhaust gas recirculated into the combustion chamber on the condition that combustion of the air-fuel mixture is detected at a time different from the time, and the ignition signal output unit The combustion state control part which performs the combustion state control which stops an output and transfers to self-ignition operation is comprised.

  As a second aspect of the present invention, the combustion state control device includes an intake air amount adjusting member that adjusts an intake air amount supplied to the cylinder, and the combustion state control unit performs the combustion state control, On condition that a predetermined ignition condition is satisfied, the intake air amount adjusting member reduces the amount of intake air taken into the cylinder, and then reduces the amount of exhaust gas recirculated into the combustion chamber before outputting an ignition signal. The output of the ignition signal by the unit may be resumed.

As a third aspect of the present invention, the combustion state control device has a combustion intensity detection unit that detects the combustion intensity of the air-fuel mixture burned in the combustion chamber, and the combustion state control unit has a combustion intensity equal to or higher than a predetermined intensity. If so, the combustion state control may be executed.
As a fourth aspect of the present invention, the combustion state control unit may continue the combustion state control until the combustion intensity becomes less than the predetermined intensity when the combustion intensity is equal to or higher than the predetermined intensity.

  As described above, according to the first aspect, the amount of exhaust gas recirculated into the combustion chamber is set on condition that the combustion state control unit detects combustion of the air-fuel mixture at a timing different from the output timing of the ignition signal. In addition, the output of the ignition signal to the spark plug is stopped and the auto-ignition operation is started, so that the exhaust gas recirculated into the combustion chamber reduces the combustion temperature of the air-fuel mixture in the combustion chamber and An increase in combustion intensity in the combustion chamber caused by combustion can be suppressed. Therefore, the occurrence of early combustion of the air-fuel mixture can be suppressed. In addition to this, since ignition of the spark plug is stopped to shift to self-ignition operation, it is more effectively suppressed that the combustion intensity in the combustion chamber increases and early combustion of the air-fuel mixture is more effectively suppressed. can do.

  In addition, since the amount of exhaust gas recirculated into the combustion chamber in the stoichiometric operation state can be increased, incomplete combustion can be suppressed and nitrogen oxidation in the exhaust gas exhausted from the cylinder can be suppressed. The ratio of objects can be reduced, and deterioration of exhaust emission can be prevented.

According to the second aspect, the combustion state control unit, after executing the combustion state control, takes the intake air amount sucked into the cylinder by the intake air amount adjusting member on condition that a predetermined ignition condition is satisfied. Therefore, the amount of intake air supplied to the internal combustion engine can be reduced after the shift to the self-ignition operation. For this reason, it is possible to reduce the load on the internal combustion engine and make it difficult to burn the air-fuel mixture, and it is possible to suppress the occurrence of early combustion.
The combustion state control unit reduces the amount of intake air taken into the cylinder and then reduces the amount of exhaust gas recirculated into the combustion chamber and outputs an ignition signal to the spark plug. Immediately before, the reduction in the combustion temperature of the air-fuel mixture in the combustion chamber can be suppressed, and the reduction in the combustion intensity in the combustion chamber caused by the combustion of the air-fuel mixture can be suppressed. For this reason, it can prevent that the output of an internal combustion engine falls when it transfers to spark ignition driving | operation.

According to the third aspect, the combustion state control unit executes the combustion state control on the condition that the combustion intensity is equal to or higher than the predetermined intensity, so that it is promptly detected that the early combustion of the air-fuel mixture has occurred. Thus, the amount of exhaust gas recirculated into the combustion chamber can be increased. For this reason, generation | occurrence | production of the early combustion of air-fuel | gaseous mixture can be suppressed continuously.
According to the fourth aspect, since the combustion state control unit continues the combustion state control until the combustion intensity becomes less than the predetermined intensity when the combustion intensity is equal to or higher than the predetermined intensity, the combustion intensity of the mixture is suppressed. By increasing the amount of exhaust gas recirculated into the combustion chamber until it is, it is possible to prevent the early combustion of the air-fuel mixture from recurring.

FIG. 1 is a diagram showing an embodiment of a combustion state control device for an internal combustion engine of the present invention, and is a cross-sectional view of the internal combustion engine to which the combustion state control device is applied. FIG. 2 is a diagram showing an embodiment of the combustion state control device for an internal combustion engine of the present invention, and is a block diagram of the combustion state control device. FIG. 3 is a diagram showing an embodiment of the combustion state control device for an internal combustion engine of the present invention, and is a flowchart of the combustion state control program. FIG. 4 is a diagram showing an embodiment of the combustion state control device for an internal combustion engine of the present invention, and is a timing chart of the combustion state control process.

Embodiments of a combustion state control apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings.
1 to 4 are diagrams showing a combustion state control device for an internal combustion engine according to an embodiment of the present invention.
First, the configuration will be described. In FIG. 1, an engine 1 as an internal combustion engine includes a cylinder block 2, a cylinder head 3 provided at an upper portion of the cylinder block 2, a crankcase 4 provided at a lower portion of the cylinder head 3, and a lower portion of the crankcase 4. And an oil pan 5 in which oil (not shown) is stored.

A cylinder 6 as a cylinder is provided inside the cylinder block 2, and a piston 7 is provided inside the cylinder 6 so as to be capable of reciprocating in the vertical direction. The piston 7 is connected to the crankshaft 9 via a connecting rod 8. The crankshaft 9 is rotatably supported by the crankcase 4, and the reciprocating motion of the piston 7 in the vertical direction is converted into the rotational motion of the crankshaft 9 via the connecting rod 8.
Here, in FIG. 1, one cylinder 6 is illustrated, but the number of cylinders 6 is four, for example, in the case of a four-cylinder engine. However, the engine 1 of the present embodiment is not limited in the number of cylinders.

A combustion chamber 10 surrounded by the top of the piston 7, the cylinder 6 and the bottom of the cylinder head 3 is formed at the top of the cylinder 6. The combustion chamber 10 is formed by an intake port formed in the cylinder head 3. 11 and the exhaust port 12.
The cylinder head 3 is provided with an intake valve 13 and an exhaust valve 14, and the intake valve 13 and the exhaust valve 14 are reciprocated in the vertical direction by an intake cam and an exhaust cam (not shown). The exhaust port 12 is opened and closed.

An intake pipe 15 is connected to the cylinder head 3, and the intake pipe 15 has an intake passage 15 a communicating with the intake port 11. An air cleaner 16 is connected to the upstream end of the intake pipe 15, and the air cleaner 16 purifies the outside air introduced into the intake passage 15a. Further, a throttle valve 18 driven by a stepping motor 17 is provided in the intake pipe 15, and this throttle valve 18 adjusts the opening degree of the intake passage 15 a, so that the cylinder 6 is connected via the intake port 11. The amount of intake air introduced into the is adjusted. The stepping motor 17 and the throttle valve 18 of the present embodiment constitute an intake air amount adjusting member.
An injector 19 is provided at a portion of the intake pipe 15 on the downstream side of the throttle valve 18, and the injector 19 injects fuel into the combustion chamber 10 through the intake port 11.

A spark plug 20 is provided at the bottom of the cylinder head 3. The spark plug 20 is a fuel injected from the injector 19 into the combustion chamber 10 and an intake pipe supplied from the intake pipe 15 into the combustion chamber 10. By igniting the air-fuel mixture, the air-fuel mixture is combusted in the combustion chamber 10. Thus, the engine 1 of this embodiment is a spark ignition engine.
The cylinder head 3 is provided with an exhaust pipe 21, which has an exhaust passage 21 a that communicates with the exhaust port 12 and exhausts exhaust gas from the cylinder 6. The exhaust pipe 21 is provided with an exhaust valve 23 driven by a stepping motor 22, and this exhaust valve 23 adjusts the opening degree of the exhaust passage 23 a so that the amount of exhaust gas recirculated into the combustion chamber 10. To be adjusted.

Specifically, when the opening degree of the exhaust valve 23 is reduced, a part of the exhaust gas discharged to the exhaust passage 21a is recirculated into the combustion chamber 10 as EGR gas. Further, the exhaust gas is restricted so that the exhaust gas stays in the combustion chamber 10, so that the EGR gas is recirculated into the combustion chamber 10. The amount of EGR gas increases as the opening of the exhaust valve 23 decreases.
Further, a three-way catalyst 24 is provided at a portion of the exhaust pipe 21 downstream of the exhaust valve 23, and this three-way catalyst 24 purifies nitrogen oxides, carbon monoxide and hydrocarbons in the exhaust gas. It has become.

An air flow meter 31 is provided in the intake pipe 15 downstream of the air cleaner 16. The air flow meter 31 detects the amount of intake air taken into the engine 1 per unit time and detects the amount of intake air. A detection signal is output to 51.
A crank angle sensor 32 is provided in the vicinity of the crankshaft 9, and the crank angle sensor 32 outputs a signal synchronized with the rotation of the crankshaft 9 to the ECU 51.

As shown in FIG. 2, the ECU 51 includes a CPU (Central Processing Unit) 52, a ROM (Read Only Memory) 53, a RAM (Random Access Memory) 54, an input interface 55, an output interface 56, and the like.
Based on the crank pulse signal input from the crank angle sensor 32 via the input interface 55, the ECU 51 calculates, for example, the engine speed (rpm) per minute as the cylinder discrimination and the engine speed per unit time. To do.

In addition, a signal is input to the input interface 55 from the accelerator opening sensor 33, and the ECU 51 opens the accelerator pedal operated by the driver based on the input signal from the accelerator opening sensor 33. Detect the degree.
In addition, an ion sensor 34 is incorporated in the spark plug 20, and the ion sensor 34 detects that the air-fuel mixture has been combusted in the combustion chamber 10 by ignition of the spark plug 20, and inputs it to the input interface 55 of the ECU 51. And the ionic current is output.

  That is, ions are generated during the combustion of the air-fuel mixture, and when the ions reach the electrode of the spark plug 20, the ion sensor 34 uses the ion current to flow between the electrodes of the spark plug 20. And an ion current is output to the input interface 55 in proportion to the magnitude of the combustion intensity corresponding to the combustion pressure. Here, the ion current value increases as the combustion intensity of the air-fuel mixture burned in the combustion chamber 10 increases.

  As described above, the ion sensor 34 of the present embodiment detects that the air-fuel mixture has been combusted in the combustion chamber 10 and constitutes a combustion detector. Further, the ECU 51 determines the magnitude of the combustion intensity based on the magnitude of the rate of increase of the ionic current value input from the ion sensor 34, and the ECU 51 together with the ion sensor 34 has the combustion chamber 10. A CPU 52 that functions as a combustion intensity detector 61 that detects the combustion intensity of the air-fuel mixture burned inside is provided.

  The output interface 56 of the ECU 51 is connected to the stepping motors 17 and 22, the injector 19, and the spark plug 20. The ECU 51 includes an air flow meter 31, a crank angle sensor 32, an accelerator opening sensor 33, and an ion sensor 34. The fuel injection amount, the fuel injection timing, the ignition timing, the opening degree of the throttle valve 18 and the opening degree of the exhaust valve 23 are controlled based on the input signal.

  Specifically, the ECU 51 is a basic injection in which the relationship between the engine parameters and the basic injection amount, which are detected values of the air flow meter 31, the crank angle sensor 32, and the accelerator opening sensor 33 representing the operating state of the engine 1 is determined in advance. The basic injection amount and the injection timing are calculated using the quantity map, and an injection signal corresponding to the basic injection amount and the injection timing is output to the injector 19. This basic injection amount is set so that the air-fuel ratio in the cylinder 6 is a stoichiometric value that is the target air-fuel ratio, and this basic injection amount map is stored in the storage area of the ROM 53.

Further, the ECU 51 calculates an ignition timing with reference to an ignition timing map in which the relationship between the engine parameter and the ignition timing is determined in advance, and outputs an ignition signal corresponding to the ignition timing to the spark plug 20. The ignition timing is usually set in the vicinity of the MBT that has been advanced to the maximum so that the maximum torque can be obtained. The ignition timing map is stored in the storage area of the ROM 53. Here, the ECU 51 of the present embodiment includes a CPU 52 that functions as an ignition signal output unit 62 that outputs an ignition signal to the spark plug 20.
A CPU 52 is provided.

  Further, the ECU 51 calculates the intake air amount by using the intake air amount map in which the relationship between the engine parameter and the intake air amount is determined in advance, and outputs a signal corresponding to the calculated intake air amount to the stepping motor 17. The opening of the throttle valve 18 is adjusted by the stepping motor 17.

  On the other hand, when the ion current value of the ion sensor 34 is larger than the threshold value of the increase rate of the ion current value stored in the storage area of the ROM 53, the ECU 51 has caused early combustion of the air-fuel mixture in the combustion chamber 10 It comes to judge.

Early combustion is abnormal combustion that occurs before the ignition timing of the spark plug 20, unlike the original combustion that spreads throughout the combustion chamber 10 by ignition of the spark plug 20. When this early combustion occurs, the combustion intensity becomes larger than the original combustion due to ignition of the spark plug 20, and the rate of increase of the output value of the ionic current value increases.
The ECU 51 determines that the early combustion of the air-fuel mixture in the combustion chamber 10 has occurred when the rate of increase of the ion current value of the ion sensor 34 is greater than the threshold value. The ECU 51 determines that early combustion has occurred on the condition that the ion sensor 34 has detected combustion of the air-fuel mixture at a time different from the output timing of the ignition signal of the ignition plug 20, and drives the stepping motor 22. Thus, control is performed so that the opening degree of the exhaust valve 23 is reduced, and combustion state control for stopping outputting the ignition signal to the spark plug 20 is executed.

  When the opening degree of the exhaust valve 23 decreases, the amount of exhaust gas recirculated into the combustion chamber 10, that is, the amount of EGR gas increases. Further, in the early combustion state, the combustion intensity of the air-fuel mixture in the combustion chamber 10 is increased, so that the self-ignition operation is performed even if the ignition plug 20 is not ignited.

Here, the stepping motor 22 and the exhaust valve 23 of the present embodiment constitute an exhaust gas recirculation amount adjusting member, and the ECU 51 includes a CPU 52 that functions as a combustion state control unit 63.
In addition, when the state in which the rate of increase of the ionic current value of the ion sensor 34 is equal to or greater than the threshold continues, the ECU 51 determines that the combustion intensity in the combustion chamber 10 is equal to or greater than a predetermined intensity, and performs the above-described combustion state control. Run.
In addition, after executing the above-described combustion state control, the ECU 51 uses the exhaust valve opening map as an engine parameter with signals from the air flow meter 31, the crank angle sensor 32, the accelerator opening sensor 33, and the ion sensor 34 as engine parameters. 23 is calculated, and this opening signal is output to the stepping motor 22. The exhaust valve opening degree map is stored in the storage area of the ROM 53.

In addition, after the above-described combustion state control is executed, the ECU 51 turns the stepping motor 17 on as a predetermined ignition condition when a state where the rate of increase of the ion current value of the ion sensor 34 is less than a threshold value continues for a predetermined time. Driven to control the opening of the throttle valve 18 to the closed side to reduce the amount of intake air taken into the cylinder 6. Next, after driving the stepping motor 22 to control the opening of the exhaust valve 23 to the open side to reduce the amount of exhaust gas recirculated into the combustion chamber 10, an ignition signal is output to the spark plug 20 at the ignition timing. To do.
Therefore, when the rate of increase of the ion current value of the ion sensor 34 is equal to or greater than the threshold, the ECU 51 determines that the rate of increase of the ion current value of the ion sensor 34 is less than the threshold, that is, the combustion intensity in the combustion chamber 10 is a predetermined intensity. The combustion state control is continued until it becomes less than the value.

Next, the combustion state control process will be described with reference to FIGS.
FIG. 3 is a flowchart of the combustion state control program stored in the storage area of the ROM 53, and this combustion state control program is executed by the CPU 52.
In FIG. 3, the CPU 52 determines whether or not it is an ignition timing (step S1). In step S1, the CPU 52 refers to the ignition timing map, calculates the ignition timing based on input signals from the air flow meter 31, the crank angle sensor 32, and the accelerator opening sensor 33, and determines that it is the ignition timing. An ignition signal i corresponding to the timing is output to the spark plug 20 (step S10).

If the CPU 52 determines that it is not the ignition timing in step S1, it determines whether or not the rate of increase of the ionic current value is greater than or equal to the threshold P based on the input signal from the ion sensor 34 (step S2). If the CPU 52 determines that the rate of increase of the ion current value is less than the threshold value P, the CPU 52 determines that the combustion intensity in the combustion chamber 10 is small and that early combustion, which is combustion at a timing different from the ignition timing, has not occurred. Return to step S1. Therefore, the CPU 52 executes normal ignition timing control when early combustion has not occurred.
In step S2, if the CPU 52 determines that the rate of increase of the ionic current value is equal to or higher than the threshold value P before the output of the ignition signal i as shown in FIG. Is determined to have occurred, and the routine proceeds to combustion state control.

In the combustion state control, the CPU 52 refers to the exhaust valve opening map, and inputs signals from the air flow meter 31, the crank angle sensor 32, and the accelerator opening sensor 33, that is, the engine load and the combustion intensity input from the ion sensor 34. The exhaust valve 23 is controlled to the closed side so that the opening degree according to the size is obtained (step S3). For this reason, a part of the exhaust gas exhausted from the combustion chamber 10 to the exhaust pipe 21 is recirculated into the combustion chamber 10 as EGR gas.
Next, the CPU 52 stops the output of the ignition signal i (step S4). In FIG. 4, in order to compare the output timing of the ion current of the ion sensor 34 and the output timing of the ignition signal, the ignition signal at the timing when the output is stopped is indicated by a broken line.

Further, when early combustion occurs, the combustion intensity in the combustion chamber 10 is large, and therefore the engine 1 shifts from the spark ignition operation to the self-ignition operation after the exhaust valve 23 is controlled to the closed side.
Next, the CPU 52 determines whether or not the increase rate of the ion current value is less than the threshold value P based on the input signal from the ion sensor 34 (step S5), and the increase rate of the ion current value is equal to or more than the threshold value P. If it is determined, the process returns to step S3.
In step S5, when the CPU 52 determines that the increase rate of the ionic current value is less than the threshold value P, the CPU 52 determines whether or not the time during which the increase rate of the ionic current value is less than the threshold value P continues for a certain time T. (Step S6).

  CPU52 returns a process to step S3, when the increase rate of an ionic current value becomes more than the threshold value P within the fixed time T. FIG. On the other hand, if the CPU 52 determines that the time during which the rate of increase of the ionic current value is less than the threshold value P continues for a certain time T, the CPU 52 determines that a predetermined ignition condition is satisfied and drives the stepping motor 17. Then, the opening Q1 of the throttle valve 18 is controlled to the closed side so that the opening according to the engine load and the magnitude of the combustion intensity input from the ion sensor 34 is obtained (step S7). For this reason, the amount of intake air supplied into the cylinder 6 decreases. Here, instead of determining whether or not the time during which the increase rate of the ionic current value is equal to or greater than the threshold value P continues for a certain time T, the CPU 52 determines the number of times that the increase rate of the ionic current value is equal to or greater than the threshold value P. You may make it discriminate | determine whether it continued twice.

Next, the CPU 52 drives the stepping motor 22 to control the opening Q2 of the exhaust valve 23 to the opening side so that the opening according to the engine load and the magnitude of the combustion intensity input from the ion sensor 34 is obtained (step). S8). For this reason, the amount of EGR gas recirculated into the combustion chamber 10 decreases and the amount of exhaust gas discharged from the cylinder 6 increases.
When the CPU 52 controls the exhaust valve 23 to open, after canceling the output stop of the ignition signal i (step S9), the CPU 52 returns the process to step S1 and shifts to normal ignition timing control.

  As described above, the ECU 51 of the present embodiment increases the amount of exhaust gas recirculated into the combustion chamber 10 on the condition that the combustion of the air-fuel mixture is detected at a time different from the output time of the ignition signal i, and the ignition plug. Since the output of the ignition signal to 20 is stopped and the self-ignition operation is started, the combustion temperature of the air-fuel mixture in the combustion chamber 10 can be lowered by the exhaust gas recirculated into the combustion chamber 10. For this reason, the increase in the combustion intensity in the combustion chamber 10 generated by the combustion of the air-fuel mixture can be suppressed, and the occurrence of early combustion of the air-fuel mixture can be suppressed. In addition, since the ignition of the spark plug 20 is stopped and the self-ignition operation is started, an increase in the combustion intensity in the combustion chamber 10 is more effectively suppressed, and the early combustion of the air-fuel mixture is more effective. Can be suppressed.

Further, since the amount of exhaust gas recirculated into the combustion chamber 10 in the stoichiometric operation state is increased, incomplete combustion can be suppressed and the exhaust gas discharged from the cylinder 6 can be suppressed. The proportion of nitrogen oxides occupied can be reduced, and exhaust emission can be prevented from deteriorating.
In addition, the ECU 51 of the present embodiment controls the opening of the throttle valve 18 to the closed side after the combustion state control is executed and the intake that is sucked into the cylinder 6 under the condition that the predetermined ignition condition is satisfied. Since the amount of air is reduced, the amount of intake air supplied to the engine 1 can be reduced after the shift to the self-ignition operation. For this reason, it is possible to reduce the load on the engine 1 and make it difficult to burn the air-fuel mixture, and to suppress the occurrence of early combustion.

Further, the ECU 51 of the present embodiment reduces the amount of intake air taken into the cylinder 6 and then reduces the amount of exhaust gas recirculated into the combustion chamber 10 and outputs an ignition signal to the spark plug 20. Immediately before shifting to the spark ignition operation, it is possible to suppress a decrease in the combustion temperature in the combustion chamber 10 caused by the combustion of the mixture by suppressing a decrease in the combustion temperature of the mixture in the combustion chamber 10. For this reason, it can prevent that the output of the engine 1 falls when it transfers to spark ignition driving | operation.
Further, the ECU 51 of the present embodiment executes the combustion state control on the condition that the rate of increase of the ion current value of the ion sensor 34 is equal to or greater than the threshold value P, that is, the combustion intensity is equal to or greater than the predetermined intensity. It is possible to quickly detect that the early combustion of the air-fuel mixture has occurred and increase the amount of exhaust gas recirculated into the combustion chamber 10. For this reason, generation | occurrence | production of the early combustion of air-fuel | gaseous mixture can be suppressed continuously.

Further, the ECU 51 of this embodiment, when the rate of increase of the ion current value of the ion sensor 34 is equal to or higher than the threshold value P, until the rate of increase of the ion current value of the ion sensor 34 becomes less than the threshold value P, that is, the combustion intensity. Since the combustion state control is continued until the gas becomes less than the predetermined intensity, the amount of exhaust gas recirculated into the combustion chamber 10 is increased until the combustion intensity of the mixture is suppressed, and the early combustion of the mixture reoccurs. Can be prevented.
In addition, although the engine 1 of this embodiment uses the ion sensor 34 as a combustion detection part and a combustion intensity detection part, it replaces with the ion sensor 34 and uses the in-cylinder pressure sensor which detects the pressure in the cylinder 6 directly. Alternatively, a knock sensor that detects vibration when the air-fuel mixture is burned in the combustion chamber 10 may be used.

Moreover, although the engine 1 of this embodiment employ | adopts the internal EGR system which provided the exhaust valve 23 in the middle of the exhaust pipe 21, it is not limited to this. For example, an EGR pipe for connecting the intake pipe 15 and the exhaust pipe 21 and an EGR valve provided on the EGR pipe are provided, and a part of the exhaust gas introduced into the exhaust pipe 21 is supplied to the intake pipe 15 through the EGR pipe. An external EGR system for refluxing may be employed. In this case, the EGR valve may be controlled by driving the stepping motor that drives the EGR valve in the same manner as controlling the exhaust valve 23 and the stepping motor 22.
Further, the engine 1 of the present embodiment is provided with the exhaust valve 23 in the exhaust pipe 21 to adjust the amount of EGR gas recirculated into the combustion chamber 10, but this is not limiting, and a variable valve lift mechanism is provided. It is also possible to reduce the lift amount of the exhaust valve 14 and increase the residual gas amount in the combustion chamber 10.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 6 ... Cylinder (cylinder), 10 ... Combustion chamber, 17 ... Stepping motor (intake air amount adjusting member), 18 ... Throttle valve (intake air amount adjusting member), 20 ... Spark plug, 22 ... Stepping motor (exhaust gas recirculation amount adjusting member), 23 ... Throttle valve (exhaust gas recirculation amount adjusting member), 34 ... Ion sensor (combustion detector, combustion intensity detector), 52 ... CPU (combustion intensity detector, ignition) Signal output unit, combustion state control unit), 61 ... combustion intensity detection unit, 62 ... ignition signal output unit, 63 ... combustion state control unit

Claims (4)

A combustion state control device for an internal combustion engine comprising an ignition plug that ignites an air-fuel mixture in a combustion chamber of a cylinder provided in the internal combustion engine, and an ignition signal output unit that outputs an ignition signal to the ignition plug,
A combustion detector for detecting that the air-fuel mixture has been combusted in the combustion chamber;
An exhaust gas recirculation amount adjusting member for adjusting the amount of exhaust gas recirculated into the combustion chamber;
Controlling the exhaust gas recirculation amount adjusting member to increase the amount of exhaust gas recirculated into the combustion chamber on the condition that combustion of the air-fuel mixture is detected at a time different from the output timing of the ignition signal, A combustion state control device for an internal combustion engine, comprising: a combustion state control unit for executing combustion state control for stopping the output of an ignition signal by the ignition signal output unit and shifting to a self-ignition operation . An intake air amount adjusting member for adjusting an intake air amount supplied to the cylinder;
The combustion state control unit reduces the intake air amount sucked into the cylinder by the intake air amount adjustment member on the condition that a predetermined ignition condition is satisfied after the combustion state control is executed, 2. The combustion state control device for an internal combustion engine according to claim 1, wherein after the amount of exhaust gas recirculated into the combustion chamber is reduced, output of the ignition signal by the ignition signal output unit is resumed. A combustion intensity detector for detecting the combustion intensity of the air-fuel mixture burned in the combustion chamber;
The combustion state control device for an internal combustion engine according to claim 1 or 2, wherein the combustion state control unit performs the combustion state control on condition that the combustion intensity is equal to or greater than a predetermined intensity. .   The internal combustion engine according to claim 3, wherein the combustion state control unit continues the combustion state control until the combustion intensity becomes less than a predetermined intensity when the combustion intensity is equal to or higher than a predetermined intensity. Combustion state control device.

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