JP4232590B2 - Combustion control system for compression ignition internal combustion engine - Google Patents

Description

  The present invention relates to a combustion control system that controls the combustion state of a compression ignition type internal combustion engine.

  In a compression ignition type internal combustion engine, a premixed mixture of fuel and intake air is formed in the cylinder at a time before the top dead center of the compression stroke, and the premixed mixture is compressed and self-ignited to perform premixed compression autoignition combustion. Techniques for performing are known.

  Further, in order to stably perform premixed compression auto-ignition combustion in a wider operating range, a compression ignition type internal combustion engine that uses a plurality of types of fuel and controls the supply of these fuels according to the engine load of the internal combustion engine. It has been known. For example, Patent Document 1 discloses that only low-octane fuel is supplied to the intake port when the engine load is in the low load region, and low-octane fuel is supplied to the intake port when the engine load is in the middle / high load region. A technique for supplying high-octane fuel into a cylinder is disclosed.

In a compression ignition type internal combustion engine, a technique of performing premixed compression auto-ignition combustion when the engine load is in a low / medium load region and performing diffusion combustion when the engine load is in a high load region (for example, Patent Documents) 2), in a compression ignition type internal combustion engine that switches between premixed compression autoignition combustion and stratified combustion according to engine load, when premixed compression autoignition combustion is performed, the circulation of exhaust gas to the intake passage is stopped. Or the technique (for example, refer patent document 3) made to reduce rather than the time of layered combustion is known.
JP 2000-179368. Japanese Patent Application Laid-Open No. 11-324664. JP-A-9-32651. JP 2001-355471 A. Japanese Patent Laid-Open No. 11-351091.

  By the way, in a compression ignition type internal combustion engine using light oil and gasoline as fuel, premixed compression self-ignition combustion is performed by forming a premixed gas by both light oil and gasoline, or a premixed gas is formed only by light oil. In some cases, the combustion state such as premixed compression auto-ignition combustion performed at least or diffusion combustion performed using at least light oil is switched according to the engine load and the engine speed. In such a compression ignition type internal combustion engine, generally, when premixed compression self-ignition combustion is performed by forming a premixed gas only by light oil, the ignition timing is controlled or the combustion temperature is lowered. Therefore, a part of the exhaust is supplied into the cylinder. In addition, when performing diffusion combustion using at least light oil, part of the exhaust gas is supplied into the cylinder in order to lower the combustion temperature. That is, in these combustion states, by supplying a part of the exhaust gas into the cylinder, the premixed gas is ignited at a time before the vicinity of the top dead center of the compression stroke. And the generation of nitrogen oxides (NOx). However, when premixed compression auto-ignition combustion is performed by forming a premixed gas mixture of both light oil and gasoline, the ignition timing is controlled to an appropriate time based on the supply ratio of light oil and gasoline. If the gas is supplied into the cylinder, the ignition timing may deviate from an appropriate time, resulting in unstable combustion or misfire.

The present invention has been made in view of the above problems, and uses premixed compression auto-ignition combustion that is performed by using gas oil and gasoline as fuel and forming a premixed gas with both gas oil and gasoline. In a compression ignition type internal combustion engine that switches between a combustion state and other combustion states according to engine load and engine speed, premixed compression self-ignition combustion performed by forming a premixed gas with both light oil and gasoline is performed. It is an object to provide a technique capable of more stable combustion and suppressing misfire.

The present invention employs the following means in order to solve the above problems.
That is, according to the present invention, in a compression ignition type internal combustion engine using light oil and gasoline as fuel, when premixed compression self-ignition combustion is performed by forming a premixed gas by both light oil and gasoline, the present invention is applied to the cylinder. The supply of exhaust gas is stopped.

More specifically, the combustion control system for a compression ignition type internal combustion engine according to the present invention includes:
Using light oil and gasoline as fuel,
Premixed compression self-ignition combustion in which a premixed gas is formed of at least light oil of light oil and gasoline and the premixed gas is compressed and self-ignited, and diffusion combustion performed using at least light oil of light oil and gasoline Combustion switching means for switching according to engine load and engine speed;
Exhaust supply means for supplying a part of the exhaust into the cylinder;
A compression ignition type internal combustion engine comprising: an exhaust supply control means for controlling supply of exhaust gas into the cylinder by the exhaust supply means;
When premixed compression self-ignition combustion is performed by forming a premixed gas with both light oil and gasoline, the exhaust gas supply control means stops the supply of exhaust gas into the cylinder.

  In the present invention, when performing premixed compression auto-ignition combustion, premixed gas is formed by supplying both light oil and gasoline, or only light oil, into the cylinder before the top dead center of the compression stroke. To do. The premixed gas is compressed and self-ignited to perform premixed compression self-ignition combustion. On the other hand, when performing diffusion combustion, gasoline is supplied into the cylinder before the compression stroke top dead center to form a premixed gas, and light oil is fed into the cylinder at a timing near the compression stroke top dead center. Supplying or supplying light oil without supplying gasoline into the cylinder near the top dead center of the compression stroke performs diffusion combustion using light oil as an ignition source. Therefore, in the present invention, the combustion state of the compression ignition internal combustion engine is switched by changing the supply timing of light oil and / or changing whether or not gasoline is supplied.

  In the present invention, the combustion performed when the premixed gas formed in the cylinder before the compression stroke top dead center is compressed and self-ignited is referred to as premixed compression self-ignition combustion. On the other hand, the combustion performed by using the fuel injected into the combustion chamber at the time near the compression stroke top dead center as the ignition source is referred to as diffusion combustion.

  Since gasoline is less ignitable than diesel, when premixed gas is formed by both gasoline and diesel oil, if the gasoline supply ratio is increased, the ignition timing of the premixed gas will be delayed and the gasoline supply ratio will be reduced. If it is lowered, the ignition timing of the premixed gas becomes earlier. Therefore, in the present invention, when premixed compression self-ignition combustion is performed by forming a premixed gas with both gasoline and light oil, the ignition timing is controlled to an appropriate time according to the supply ratio of gasoline and light oil. Yes. Hereinafter, premixed compression autoignition combustion performed by forming a premixed gas with both gasoline and light oil is referred to as first premixed compression autoignition combustion.

  According to the present invention, when the first premixed compression self-ignition combustion is performed, the inflow of exhaust gas into the cylinder is suppressed, so that the ignition timing can be suppressed from deviating from an appropriate timing. Accordingly, the first premixed compression self-ignition combustion can be made more stable, and misfire can be suppressed.

  In the present invention, the exhaust gas supply means has an exhaust gas recirculation passage for supplying a part of the exhaust gas to the intake system, and the exhaust gas supply control means is provided in the exhaust gas recirculation passage. When the first premixed compression auto-ignition combustion is performed, the exhaust recirculation passage is shut off to supply the exhaust gas into the cylinder. You may stop.

  As described above, when diffusion combustion is performed using at least light oil of light oil and gasoline, it is preferable to supply exhaust gas into the cylinder in order to lower the combustion temperature and suppress the generation of NOx. Therefore, when performing such diffusion combustion, the on-off valve may be opened. Hereinafter, diffusion combustion performed using at least light oil of light oil and gasoline is simply referred to as diffusion combustion.

  Here, when the combustion state is switched from diffusion combustion to first premixed compression self-ignition combustion, it is preferable to switch the combustion state after closing the on-off valve. Further, when switching the combustion state from the first premixed compression self-ignition combustion to the diffusion combustion, it is preferable to open the on-off valve substantially simultaneously with switching the combustion state or after switching the combustion state.

  According to such control, it is possible to more reliably suppress the exhaust gas from flowing into the cylinder when the first premixed compression self-ignition combustion is performed. Accordingly, the first premixed compression self-ignition combustion can be made more stable, and misfire can be suppressed.

  In the present invention, when premixed compression self-ignition combustion is performed, the first premixed compression self-ignition combustion performed by forming a premixed gas by both light oil and gasoline, and the premixed gas is formed only by light oil. The premixed compression autoignition combustion (hereinafter, referred to as second premixed compression autoignition combustion) may be switched according to the engine load and the engine speed.

  For example, when the engine load is in the low load region, since the amount of fuel supplied into the cylinder is small, it is preferable to perform the second premixed compression auto-ignition combustion using all of the supplied fuel as light oil with high ignitability.

  In addition, as described above, when performing the second premixed compression self-ignition combustion, the ignition timing is controlled to suppress the occurrence of premature ignition and the generation of soot, and the combustion temperature is reduced to suppress the generation of NOx. Therefore, it is preferable to supply exhaust gas into the cylinder. Therefore, the open / close valve may be opened when performing the second premixed compression self-ignition combustion.

  Here, when switching the combustion state from the second premixed compression autoignition combustion to the first premixed compression autoignition combustion, it is preferable to switch the combustion state after closing the on-off valve. When switching the combustion state from the first premixed compression autoignition combustion to the second premixed compression autoignition combustion, the on-off valve is opened substantially simultaneously with switching the combustion state or after switching the combustion state. Is preferred.

  According to such control, similarly to the above, it is possible to more reliably prevent the exhaust gas from flowing into the cylinder when performing the first premixed compression self-ignition combustion. Accordingly, the first premixed compression self-ignition combustion can be made more stable, and misfire can be suppressed.

  In the present invention, light oil is used to form a premixed gas or to perform diffusion combustion, while gasoline is used only to form a premixed gas. Therefore, when supplying light oil into the cylinder, it may be injected directly into the cylinder, and when supplying gasoline into the cylinder, it may be injected into the intake port. The gasoline injected into the intake port is sucked into the cylinder while forming a mixture with the intake air.

  In the present invention, when exhaust gas is supplied into the cylinder, the closing timing of the exhaust valve may be retarded so that the exhaust gas once discharged to the exhaust port flows backward and flows into the cylinder. Further, the burned gas (exhaust gas) remaining in the cylinder may be increased by advancing the closing timing of the exhaust valve. When exhaust is supplied into the cylinder by controlling the closing timing of the exhaust valve, when performing the first premixed compression self-ignition combustion, the closing timing of the exhaust valve is set to the normal timing. Stop supplying exhaust to

  According to the combustion control system for a compression ignition type internal combustion engine according to the present invention, premixed compression self-ignition combustion is performed by using gas oil and gasoline as fuel and forming a premixed gas with both the gas oil and gasoline. In a compression ignition type internal combustion engine that switches between other combustion states according to engine load and engine speed, premixed compression self-ignition combustion performed by forming a premixed gas with both light oil and gasoline is more effective. Stable combustion and misfire can be suppressed.

  Hereinafter, specific embodiments of a combustion control system for a compression ignition type internal combustion engine according to the present invention will be described with reference to the drawings.

  Here, the case where the present invention is applied to a diesel engine for driving a vehicle will be described as an example. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 1 according to the present embodiment, its intake / exhaust system, and its control system.

  The internal combustion engine 1 has a cylinder 2, and a piston 14 is slidably provided in the cylinder 2. An intake port 5 and an exhaust port 6 are opened in the combustion chamber in the upper part of the cylinder 2. Openings to the combustion chamber of the intake port 5 and the exhaust port 6 are opened and closed by an intake valve 9 and an exhaust valve 10, respectively. The intake port 5 is connected to the intake passage 7, and the exhaust port 8 is connected to the exhaust passage 8.

  The intake passage 7 is provided with an intake throttle valve 11 for adjusting the flow rate of intake air flowing through the intake passage 7. The intake throttle valve 11 is provided with an intake throttle actuator 12 that is configured by a step motor or the like and that drives the intake throttle valve 11 to open and close.

  The internal combustion engine 1 uses light oil and gasoline as fuel, an in-cylinder fuel injection valve 3 that injects light oil into the combustion chamber in the cylinder 2, and an in-port fuel injection that injects gasoline into the intake port 5. And a valve 4. The gasoline injected into the intake port 5 forms an air-fuel mixture together with the intake air and is sucked into the cylinder 2.

  Further, the internal combustion engine 1 is provided with an exhaust gas recirculation passage 31 (hereinafter referred to as an EGR passage 31) for introducing a part of the exhaust gas flowing through the exhaust passage 8 into the intake passage 7. The EGR passage 31 has one end connected to the exhaust passage 8 and the other end connected to the intake passage 7. The EGR passage 31 is provided with an EGR valve 32 that adjusts the flow rate of the exhaust gas flowing through the EGR passage 31. When the EGR valve 32 is opened, the exhaust passage 8 is opened, and a part of the exhaust is introduced into the intake passage 7. The exhaust gas is supplied into the cylinder 2 as intake air together with the air flowing through the intake passage 7. On the other hand, when the EGR valve 32 is closed, the exhaust passage 8 is shut off and the supply of exhaust gas into the cylinder 2 is stopped.

Further, the internal combustion engine 1 is provided with a crank position sensor 13 that detects a rotation angle of a crankshaft that rotates in conjunction with the reciprocating motion of the piston 14.

  The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU: Electronic Control Unit) 20 for controlling the internal combustion engine 1. The ECU 20 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver. The ECU 20 is electrically connected to various sensors such as the crank position sensor 13, and output signals from the various sensors are input to the ECU 20. The ECU 20 is electrically connected to the in-cylinder fuel injection valve 3, the in-port fuel injection valve 4, the intake throttle actuator 12, and the like, and can control them. The ECU 20 stores various application programs and various control maps.

  The ECU 20 premixes the combustion state of the internal combustion engine 1 according to the operating state of the internal combustion engine 1 by first premixed compression self-ignition combustion performed by forming a premixed gas with light oil and gasoline, and only with light oil. Switching between the second premixed compression self-ignition combustion performed by forming the gas and the diffusion combustion performed using light oil and gasoline. The combustion state is switched by controlling the in-cylinder fuel injection valve 3 and the in-port fuel injection valve 4 to change the injection timing of the light oil into the combustion chamber and / or whether to inject gasoline into the intake port 5. This is done by changing whether or not.

  Here, the relationship between the operating state and combustion state of the internal combustion engine 1 in the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the engine load and engine speed of the internal combustion engine 1 and the combustion state. In FIG. 2, the vertical axis represents the engine load of the internal combustion engine 1, and the horizontal axis represents the engine speed of the internal combustion engine 1. The engine load is obtained from the command value output from the ECU 20 to the intake throttle actuator 12 based on the driver's accelerator depression amount, that is, the opening of the intake throttle valve 11. On the other hand, the engine speed is obtained by the ECU 20 from the output signal of the crank position sensor 13.

  When the operating state of the internal combustion engine 1 is in an operating region where the engine load and the engine speed are low as shown by (1) in FIG. Since the amount is small, it is difficult to obtain stable combustion with gasoline with low ignitability. Therefore, in this low-load low-rotation region, the combustion state of the internal combustion engine 1 is switched to the second premixed compression autoignition combustion which is premixed compression autoignition combustion using only light oil.

  When performing the second premixed compression self-ignition combustion, the ECU 20 stops the injection of gasoline into the intake port 5 by the in-port fuel injection valve 4 and the in-cylinder fuel before the timing near the top dead center of the compression stroke. Light oil is injected into the combustion chamber by the injection valve 3. By controlling the fuel injection in this way, a premixed gas only by light oil is formed, and the premixed gas is compressed and ignited to perform premixed compression self-ignition combustion.

  The second premixed compression auto-ignition combustion is performed using only light oil as described above. However, since premixed gas is formed, NOx and soot are compared with the case where diffusion combustion is performed using only light oil. Generation is suppressed.

  When the operation state of the internal combustion engine 1 is in an operation region where the engine load and the engine speed are medium as shown in FIG. 2 (2) (hereinafter referred to as a medium load intermediate rotation region), The amount of fuel supplied to the combustion chamber is larger and the temperature in the cylinder is higher than when the state is in the low load low rotation region. Therefore, if the premixed gas is formed only from light oil, pre-ignition may occur. Therefore, in the middle load mid-rotation region, the combustion state of the internal combustion engine 1 is switched to the first premixed compression autoignition combustion which is premixed compression autoignition combustion with light oil and gasoline. In the first premixed compression self-ignition combustion, by mixing gasoline having lower ignitability than light oil, the ignitability of the premixed gas can be suppressed, and the occurrence of premature ignition can be suppressed.

  When performing the first premixed compression self-ignition combustion, the ECU 20 injects gasoline into the intake port 5 by the in-port fuel injection valve 4 during the intake stroke. Further, the ECU 20 injects light oil by the in-cylinder fuel injection valve 3 before the time near the top dead center of the compression stroke. By controlling the fuel injection in this way, a premixed gas is formed by both light oil and gasoline, and the premixed gas is compressed and ignited to perform premixed compression self-ignition combustion.

  Note that, in the first premixed compression self-ignition combustion, as described above, the occurrence of premature ignition is suppressed and the time for forming the premixed gas becomes long, so that the generation of NOx and soot is suppressed.

  When the operating state of the internal combustion engine 1 is in an operating region where the engine load and the engine speed are high as shown by (3) in FIG. 2 (hereinafter referred to as a high load high rotational region), the operating state of the internal combustion engine 1 is The amount of fuel supplied to the combustion chamber is larger and the temperature in the cylinder is higher than in the middle load mid-rotation region. For this reason, even if a premixed gas is formed by both light oil and gasoline, there is a risk of premature ignition. Therefore, in this high load high rotation region, the combustion state of the internal combustion engine 1 is switched to diffusion combustion with light oil and gasoline.

  When performing diffusion combustion with light oil and gasoline, the ECU 20 injects gasoline into the intake port 5 by the in-port fuel injection valve 4 during the intake stroke. Further, the ECU 20 injects light oil by the in-cylinder fuel injection valve 3 at a time near the top dead center of the compression stroke. By controlling the fuel injection in this way, a premixed gas is formed by gasoline, and diffusion combustion is performed in which the mixed gas burns using light oil as an ignition source.

  In addition, in the diffusion combustion with light oil and gasoline, a premixed gas is formed by gasoline, but since gasoline has low ignitability, premature ignition hardly occurs. In addition, compared to diffusion combustion using only light oil, the amount of light oil injected at a time near the compression top dead center is reduced by the amount of gasoline that forms the premixed gas, so that the generation of NOx and soot is suppressed. .

Next, the exhaust supply control into the cylinder 2 in each combustion state will be described.
When the second premixed compression self-ignition combustion is performed, the ECU 20 opens the EGR valve 32 and supplies exhaust gas into the cylinder 2 in order to lower the combustion temperature and control the ignition timing. Further, when performing diffusion combustion with light oil and gasoline, the ECU 20 opens the EGR valve 32 and supplies exhaust gas into the cylinder 2 in order to lower the combustion temperature. On the other hand, in the first premixed compression auto-ignition combustion, the ignition timing is controlled to an appropriate time based on the supply ratio of light oil and gasoline. Therefore, when exhaust gas is supplied into the cylinder 2, the ignition timing shifts from the appropriate time. Combustion may become unstable or misfire may occur. Therefore, when performing the first premixed compression self-ignition combustion, the ECU 20 closes the EGR valve 32 and stops the supply of exhaust gas into the cylinder 2.

  Next, the switching control of the combustion state of the internal combustion engine 1 in the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a combustion state switching control routine of the internal combustion engine 1. This routine is stored in advance in the ECU 20, and is a routine that is repeated every predetermined time during the operation of the internal combustion engine 1.

  In this routine, the ECU 20 first reads the current combustion state of the internal combustion engine 1 in S101. The combustion state at this time may be determined from the injection timing of light oil from the in-cylinder fuel injection valve 3 and whether or not gasoline is injected from the in-port fuel injection valve 4.

Next, the ECU 20 proceeds to S <b> 102, and a request for a combustion state required in the internal combustion engine 1 from the engine load obtained from the opening degree of the intake throttle valve 11 and the engine speed obtained from the output signal of the crank position sensor 13. Deriving the combustion state. In the ECU 20, the relationship between the engine load and engine speed of the internal combustion engine 1 shown in FIG. 2 and the combustion state is stored in advance as MAP. In S102, the required combustion state is calculated from this MAP.

  Next, the ECU 20 proceeds to S103, and determines whether or not the required combustion state calculated in S102 and the current combustion state read in S101 are the same. If it is determined in S103 that the required combustion state and the current combustion state are the same, the ECU 20 temporarily ends the execution of this routine because there is no need to switch the combustion state of the internal combustion engine 1. On the other hand, if it is determined in S103 that the requested combustion state is not the same as the current combustion state, the ECU 20 proceeds to S104.

  In S104, the ECU 20 determines whether or not the required combustion state calculated in S102 is the first premixed compression self-ignition combustion. If it is determined in S104 that the required combustion state is the first premixed compression self-ignition combustion, the ECU 20 proceeds to S105. On the other hand, when it is determined that the requested combustion state is not the first premixed compression self-ignition combustion, the ECU 20 proceeds to S107.

  In step S105, the ECU 20 closes the EGR valve 32. That is, the EGR passage 31 is shut off and the supply of exhaust gas into the cylinder 2 is stopped.

  Next, the ECU 20 proceeds to S106, and after the EGR valve 32 is closed, after the combustion cycle in the cylinder 2 has elapsed, the ECU 20 switches the combustion state of the internal combustion engine 1 to the first premixed compression self-ignition combustion. That is, the injection timing of the light oil by the in-cylinder fuel injection valve 3 is changed to a timing before the timing near the top dead center of the compression stroke, and gasoline injection by the in-port fuel injection valve 4 is started during the intake stroke ( When the diffusion combustion with light oil and gasoline is switched to the first premixed compression auto-ignition combustion, the gasoline injection is continued). The injection amount of light oil and gasoline is also changed according to changes in engine load. After switching the combustion state of the internal combustion engine 1 to the first premixed compression self-ignition combustion, the ECU 20 once ends the execution of this routine.

  On the other hand, the ECU 20 having advanced to S107 substantially changes the combustion state of the internal combustion engine 1 to the required combustion state (second premixed compression auto-ignition combustion or diffusion combustion by light oil and gasoline) at the same time as opening the EGR valve 32. Switch. That is, the combustion state of the internal combustion engine 1 is switched substantially simultaneously with opening the EGR passage 31 and starting the supply of exhaust gas into the cylinder 2.

  That is, when switching the combustion state from the first premixed compression autoignition combustion to the second premixed compression autoignition combustion, the injection of gasoline by the in-port fuel injection valve 4 is stopped almost simultaneously with the opening of the EGR valve 32. . When the combustion state is switched from the first premixed compression auto-ignition combustion to the diffusion combustion by light oil and gasoline, the injection timing of the light oil by the in-cylinder fuel injection valve 3 is substantially the same as the opening of the EGR valve 32. Change to a time near top dead center.

  In addition, when switching the combustion state from the second premixed compression self-ignition combustion to the diffusion combustion by light oil and gasoline, while stopping the EGR valve 32, the fuel injection valve 4 in the port stops the gasoline injection, The timing of light oil injection by the in-cylinder fuel injection valve 3 is changed to a timing before the timing near the top dead center of the compression stroke. Conversely, when switching the combustion state from diffusion combustion with light oil and gasoline to second premixed compression self-ignition combustion, gasoline injection by the in-port fuel injection valve 4 during the intake stroke while the EGR valve 32 remains open Is started, and the injection timing of light oil by the in-cylinder fuel injection valve 3 is changed to a timing near the top dead center of the compression stroke.

As described above, the injection amounts of light oil and gasoline are changed according to changes in engine load. After switching the combustion state of the internal combustion engine 1 to each required combustion state, the ECU 20 once ends the execution of this routine.

  Here, in S107, the EGR valve 32 may be opened after switching the combustion state of the internal combustion engine 1 to the required combustion state.

  According to this routine, when the combustion state of the internal combustion engine 1 is switched from the other combustion state to the first premixed compression self-ignition combustion, the combustion state is switched after the supply of exhaust gas into the cylinder 2 is stopped. On the other hand, when switching from the first premixed compression auto-ignition combustion to another combustion state, the supply of exhaust gas into the cylinder 2 is started substantially simultaneously with the switching of the combustion state or after switching the combustion state. Therefore, when the combustion state of the internal combustion engine 1 is the first premixed compression self-ignition combustion, the inflow of exhaust gas into the cylinder 2 is suppressed. Thus, the first premixed compression autoignition combustion that forms the premixed gas by both light oil and gasoline can be made more stable combustion, and misfire can be suppressed.

The figure which shows schematic structure of the internal combustion engine which concerns on this invention, its intake-exhaust system, and its control system. The figure which showed the relationship between the engine load of an internal combustion engine, an engine speed, and a combustion state. The flowchart figure which shows the combustion state switching control routine of an internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... In-cylinder fuel injection valve 4 ... In-port fuel injection valve 11 ... Intake throttle valve 12 ... Intake throttle actuator 13 ... Crank position sensor 20・ ECU
31..Exhaust gas recirculation passage (EGR passage)
32 ・ ・ EGR valve

Claims (8)

Using light oil and gasoline as fuel,
Premixed compression self-ignition combustion in which a premixed gas is formed of at least light oil of light oil and gasoline and the premixed gas is compressed and self-ignited, and diffusion combustion performed using at least light oil of light oil and gasoline Combustion switching means for switching according to engine load and engine speed;
Exhaust supply means for supplying a part of the exhaust into the cylinder;
A compression ignition type internal combustion engine comprising: an exhaust supply control means for controlling supply of exhaust gas into the cylinder by the exhaust supply means;
When premixed compression auto-ignition combustion is performed by forming a premixed gas only from light oil, or when diffusive combustion is performed using at least light oil of light oil and gasoline, the exhaust supply control means causes the inside of the cylinder to When the premixed compression auto-ignition combustion is performed by forming the premixed gas with both light oil and gasoline, the exhaust gas supply control means supplies the exhaust gas into the cylinder. A combustion control system for a compression ignition type internal combustion engine characterized by stopping the combustion. The exhaust supply means has an exhaust recirculation passage for supplying a part of the exhaust to the intake system,
The exhaust gas supply control means includes an on-off valve provided in the exhaust gas recirculation passage for opening or closing the exhaust gas recirculation passage;
2. The compression according to claim 1, wherein when the premixed compression auto-ignition combustion is performed by forming a premixed gas with both light oil and gasoline, the exhaust supply control means closes the on-off valve. A combustion control system for an ignition type internal combustion engine.   When switching the combustion state from diffusion combustion performed using at least light oil of light oil and gasoline to premixed compression self-ignition combustion performed by forming a premixed gas with both light oil and gasoline, the on-off valve is closed. 3. The combustion control system for a compression ignition type internal combustion engine according to claim 2, wherein the combustion state is switched after the valve is operated. When switching the combustion state from premixed compression auto-ignition combustion, which is performed by forming a premixed mixture of both light oil and gasoline, to diffusion combustion, which uses at least light oil of light oil and gasoline, the combustion state is switched. 4. The combustion control system for a compression ignition type internal combustion engine according to claim 2, wherein the on-off valve is opened substantially simultaneously with or after the combustion state is switched.   The combustion switching means, when performing premixed compression autoignition combustion in the compression ignition internal combustion engine, premixed compression autoignition combustion performed by forming a premixed gas by both light oil and gasoline, and only by light oil. 5. The compression ignition type internal combustion engine according to claim 2, wherein premixed compression self-ignition combustion performed by forming a premixed gas is switched according to an engine load and a rotational speed. Combustion control system.   When switching the combustion state from premixed compression auto-ignition combustion performed by forming premixed gas only from light oil to premixed compression auto-ignition combustion performed by forming premixed gas from both light oil and gasoline, 6. A combustion control system for a compression ignition type internal combustion engine according to claim 5, wherein the combustion state is switched after the on-off valve is closed.   When switching the combustion state from premixed compression autoignition combustion, which is performed by forming a premixed gas mixture with both light oil and gasoline, to premixed compression autoignition combustion, which is performed by forming a premixed gas only with light oil, combustion The combustion control system for a compression ignition type internal combustion engine according to claim 5 or 6, wherein the on-off valve is opened substantially simultaneously with switching the state or after switching the combustion state.   The combustion control of a compression ignition type internal combustion engine according to any one of claims 1 to 7, wherein in the compression ignition type internal combustion engine, light oil is directly injected into the cylinder and gasoline is injected into an intake port. system.

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