JP5429148B2 - Premixed compression self-ignition engine - Google Patents

Description

  The present invention is driven by a fuel containing gasoline and compresses and raises the temperature of the air-fuel mixture in which the fuel and air are mixed at least in a first operation region set at a low engine speed and low load. The present invention relates to a premixed compression self-ignition engine for ignition.

  Conventionally, as shown in Patent Document 1 below, in a premixed compression self-ignition engine using natural gas as a fuel, when the engine is operated in a low load region, a glow plug (heating means) is used to There is known a technique for performing premixed compression self-ignition combustion while heating.

  Specifically, in Patent Document 1, in a low load region of the engine, a period for closing both the intake valve and the exhaust valve is set from the exhaust stroke to the intake stroke, whereby a part of the burned gas is mixed in the next cycle. The air-fuel mixture thus mixed with the burned gas is heated above the self-ignition temperature of the fuel by the glow plug.

  As described above, if the air-fuel mixture is heated using a glow plug, sufficient ignitability is ensured and the air-fuel mixture is ensured even in a low-load region where there is little fuel and the in-cylinder temperature is low. Can be self-ignited.

JP 2004-316593 A

  The premixed compression self-ignition engine disclosed in Patent Document 1 is an engine using natural gas as a fuel. For example, a gasoline engine using gasoline as a fuel is widely used as a power source for automobiles. Even in such a gasoline engine, research on premixed compression self-ignition combustion in which a mixture of fuel and air is compressed and self-ignited has been actively conducted.

  Even in the case of a premixed compression self-ignition engine using gasoline as a fuel as described above, for example, the ignitability is low in a low load region where the fuel injection amount is small, and how to ensure the ignitability there. Is a problem. Of course, it is conceivable to perform heating with a glow plug in a low load region as in the above-mentioned Patent Document 1, but for example, if the compression ratio of the engine is sufficiently high, the inside of the cylinder is sufficiently heated and the ignitability is improved. Therefore, it is not necessary to use a glow plug even in a low load region where the fuel injection amount is small. Actually, according to research by the inventors of the present application, even if the engine has a compression ratio that is somewhat higher than the compression ratio (for example, about 9 to 11) of a general gasoline engine, It has already been confirmed that the air-fuel mixture can be ignited stably without using an ignition assist means such as a glow plug.

  However, in such a gasoline engine with a high compression ratio, for example, the accelerator pedal is greatly depressed to drive the vehicle comparatively vigorously from driving in a low load range, and the load is high (the fuel injection amount is large). In the case of an instant transition to the operation region, it is difficult to perform proper premixed compression self-ignition combustion under the same conditions as in the low load region. That is, while operating only in the low load range, the load is mainly increased, and the fuel injection amount is rapidly increased while maintaining the same fuel injection timing (for example, during the intake stroke) as in the low load range. When premixed compression self-ignition combustion is to be performed, abnormal combustion called pre-ignition may occur due to the high temperature in the cylinder, for example, the timing of self-ignition of the air-fuel mixture becomes too early. .

  On the other hand, premixed compression self-ignition combustion hardly occurs when the engine speed increases. That is, when the engine speed is high, the time during which the fuel is exposed to high temperature and high pressure (heat receiving period) is short, so that the fuel passes through the compression top dead center without being fully activated, and the mixture does not self-ignite ( The possibility of misfire) increases. For this reason, for example, when relatively slow acceleration is performed from the low rotation / low load range of the engine and only the rotation speed is mainly increased, misfire is particularly likely to occur. It was a problem how to ensure the ignitability of.

  The present invention has been made in view of the above-described circumstances, and abnormal combustion and misfire are caused either at the time of acceleration where the load is increased or at the time of acceleration where the rotational speed is increased. It is an object of the present invention to provide a premixed compression self-ignition engine capable of properly igniting an air-fuel mixture without causing ignition.

  In order to solve the above-described problems, the present invention is driven by fuel containing gasoline, and the fuel and air are mixed at least in a first operation region set at a low engine speed and a low load region. A premixed compression self-ignition engine that compresses and raises the temperature of the air-fuel mixture and self-ignites, heating means for forcibly increasing the in-cylinder temperature of the engine, an injector for injecting the fuel into the cylinder, and A control means for controlling the heating means and the injector, and the control means is at least at the time of acceleration when shifting from the state of operation in the first operation region to the second operation region having a higher load than the region. Divided injection in which fuel is injected from the injector at least twice during the predetermined period after the transition to the second operation region, the second half of the compression stroke and the first half of the expansion stroke By performing the above, the air-fuel mixture is self-ignited, while at the time of acceleration such that the state of operation in the first operation region shifts to the third operation region where the rotational speed is higher than that of the first and second operation regions. After the transition to the third operation region, the air-fuel mixture is self-ignited by operating the heating means while setting the fuel injection timing from the injector in the latter half of the compression stroke. (Claim 1).

  The “heating means for forcibly increasing the in-cylinder temperature” means means for increasing the in-cylinder temperature by a method other than the compression action by the piston.

  According to the present invention, the control (split injection) in which fuel is injected into the latter half of the compression stroke and the first half of the intake stroke at the time of a relatively steep acceleration where the load increases mainly is performed. The air-fuel mixture can be self-ignited without significant delay from the fuel injection in the second half of the stroke, and the combustion is continued based on the subsequent fuel injection in the latter stage (first half of the expansion stroke). As a whole, high output corresponding to the load can be ensured while preventing generation of heat energy.

  Also, during relatively slow acceleration, where the rotational speed increases, the in-cylinder temperature is forcibly increased by operating the heating means while setting the fuel injection timing in the latter half of the compression stroke. Even in a situation where the speed is high (that is, the heat receiving period of the fuel is short) and the ignitability of the air-fuel mixture tends to deteriorate, the air-fuel mixture can be surely self-ignited without causing misfire.

  As the heating means, a glow plug having a heat generating portion that generates heat when energized is suitable.

  In the above configuration, preferably, the control means executes the split injection and moves to the glow plug from the time of transition to the second operation region at the time of acceleration of transition from the first operation region to the second operation region. When the temperature of the heat generating part of the glow plug rises above a predetermined value, the split injection is canceled and the fuel injection timing from the injector is set only in the second half of the compression stroke. ).

  According to this configuration, it is possible to appropriately continue the compression self-ignition combustion while effectively preventing the deterioration of fuel consumption. That is, when split injection is executed, the end of combustion is delayed and exhaust loss and the like increase, so if combustion based on such split injection is continuously performed, fuel efficiency during acceleration deteriorates. There is a risk that. On the other hand, in the above configuration, when the glow plug is sufficiently heated, and even if the split injection is not performed (even when a large amount of fuel is injected at one time), a state is created in which the air-fuel mixture quickly self-ignites. After that, the fuel was injected once in the latter half of the compression stroke, and the combustion was performed for a short period of time based on the fuel injection, so the deterioration of fuel consumption was minimized while ensuring the high output necessary for acceleration. Can be suppressed.

  In the above configuration, preferably, the control means starts energizing the glow plug from the time of transition to the third operation region during acceleration to transition from the first operation region to the third operation region, and then When the temperature of the heat generating part of the plug rises above a predetermined value, the fuel injection timing from the injector is set in the latter half of the compression stroke.

  As described above, when the fuel injection timing is set to the latter half of the compression stroke after the glow plug has sufficiently generated heat, misfire caused by the retarded injection timing when the glow plug is cold. Can be prevented. Further, since the acceleration that shifts from the first operation region to the third operation region is a relatively slow acceleration, the rotation speed does not increase so much until the glow plug sufficiently generates heat. For this reason, there is no fear that a serious misfire will occur until the glow plug sufficiently generates heat, and the compression self-ignition combustion can be continued properly even immediately after the transition to the third operation region.

  In the above configuration, preferably, when the temperature of the heat generating portion of the glow plug rises to a predetermined upper limit value, the control unit may continue the operation in the second operation region or the third operation region. The amount of current supplied to the glow plug is reduced (claim 5).

  According to this configuration, it is possible to ensure the reliability of the glow plug by preventing excessive temperature rise of the glow plug and efficiently ensuring the ignitability of the air-fuel mixture by heating the glow plug with the minimum necessary current. Can do.

  In the present invention, preferably, the upper control means sets the fuel injection timing from the injector in the first operation region during the intake stroke (Claim 6).

  According to this configuration, the fuel injected during the intake stroke is sufficiently mixed with the air through the compression stroke, and the uniform mixture formed thereby is heated to a high temperature by the compression action of the piston, thereby ensuring the mixture. Can be self-ignited and combustion efficiency can be further increased.

  In the above configuration, preferably, the control means has a function of controlling the operation of the intake and exhaust valves of the engine, and is generated in a cylinder based on the operation control of the intake and exhaust valves in the first operating region. Then, internal EGR is performed in which a part of the burned gas remains in the cylinder (claim 7).

  According to this configuration, the self-ignition of the air-fuel mixture can be promoted using high-temperature burned gas, and the fuel consumption can be further improved by effectively reducing the pumping loss.

  As described above, according to the premixed compression self-ignition engine of the present invention, abnormal combustion or non-combustion is caused either at the time of acceleration where the load is increased or at the time of acceleration where the rotation speed is increased. The air-fuel mixture can be properly ignited without causing misfire.

It is a figure showing the whole engine composition concerning one embodiment of the present invention. It is a block diagram which shows the control system of an engine. It is a figure which shows an example of the control map for selecting the combustion form according to the driving | running state of an engine. It is the figure which showed the change of the operating point in 1st acceleration mode on the said control map. It is the figure which showed the change of the operating point in 2nd acceleration mode on the said control map. It is a figure for demonstrating the content of the control performed when the engine is drive | operating in the 1st driving | running area | region (A1) on the said control map. It is a figure for demonstrating the content of the control performed immediately after transfering to the 2nd driving | running area | region (A2) from the said 1st driving | operation area | region (A1). It is a figure for demonstrating the content of the control performed following the said FIG. 7, and explaining the content of the control performed when it transfers to the 3rd driving | running area | region (A3) from the said 1st driving | operation area | region (A1). . It is a figure for demonstrating the case where abnormal combustion occurs, (a) shows generation | occurrence | production of pre-ignition, (b) has shown generation | occurrence | production of knocking. 6 is a time chart showing temporal changes in fuel injection timing, glow energization amount, etc. in the first acceleration mode (arrow X1 in FIG. 4). 6 is a time chart showing temporal changes in fuel injection timing, glow energization amount, etc. in the second acceleration mode (arrow X2 in FIG. 5).

(1) Overall Configuration of Engine FIG. 1 is a diagram showing an overall configuration of an engine according to an embodiment of the present invention. The engine shown in the figure is a reciprocating piston type multi-cylinder gasoline engine mounted on a vehicle as a power source for driving driving. An engine body 1 of this engine includes a cylinder block 3 having a plurality of cylinders 2 (only one of which is shown in the drawing) arranged in a direction orthogonal to the paper surface, and a cylinder head 4 provided on the upper surface of the cylinder block 3. And a piston 5 inserted into each cylinder 2 of the cylinder block 3 so as to be slidable back and forth. In addition, the fuel supplied to the engine body 1 may be anything that contains gasoline as a main component, and the contents may be all gasoline, or gasoline containing ethanol (ethyl alcohol) or the like. But you can.

  The piston 5 is connected to the crankshaft 7 via a connecting rod 8, and the crankshaft 7 is driven to rotate about the central axis in accordance with the reciprocating motion of the piston 5.

  A combustion chamber 6 is formed above the piston 5, an intake port 9 and an exhaust port 10 are opened in the combustion chamber 6, and an intake valve 11 and an exhaust valve 12 that open and close the ports 9 and 10 are connected to the cylinder head 4. Are provided respectively.

  Here, in a narrow sense, the “combustion chamber” refers to a space formed above the piston 5 when it is at the top dead center. When referring to the space (combustion chamber in a broad sense) formed in the above, it is referred to as “inside the cylinder 2” or simply “inside the cylinder”.

  The intake valve 11 and the exhaust valve 12 are driven to open and close in conjunction with the rotation of the crankshaft 7 by valve mechanisms 13 and 14 including a pair of camshafts and the like disposed in the cylinder head 4.

  VVTs 15 and 16 are incorporated in the valve operating mechanisms 13 and 14 for the intake valve 11 and the exhaust valve 12, respectively. The VVTs 15 and 16 are called variable valve timing mechanisms and variably set the operation timings of the intake and exhaust valves 11 and 12. Since various types of VVT (variable valve timing mechanism) have already been put into practical use, a detailed description of the structure of the VVTs 15 and 16 is omitted here.

  A water jacket (not shown) through which the cooling water flows is provided inside the cylinder block 3 and the cylinder head 4, and an engine water temperature sensor SW1 for detecting the temperature of the cooling water in the water jacket includes the above-described water temperature sensor SW1. The cylinder block 3 is provided.

  The cylinder block 3 is provided with an engine rotation speed sensor SW2 that detects the rotation speed of the crankshaft 7 as the rotation speed of the engine.

  The cylinder head 4 is provided with one set of spark plugs 20, injectors 21, and glow plugs 22 for each cylinder 2.

  The spark plug 20 is provided so as to face the inside of the cylinder (inside the cylinder 2) from the side of the exhaust side (left side in FIG. 1). The tip of the spark plug 20 is an electrode part protruding into the cylinder, and a spark is discharged from the electrode part into the cylinder in response to power supply from an ignition circuit (not shown).

  The injector 21 is provided so as to face the inside of the cylinder from above, and has an injection port at the tip for injecting fuel (fuel including gasoline) supplied from a fuel supply pipe (not shown) into the cylinder. doing. And the fuel injected from the injection port of this injector 21 and the air in a cylinder are mixed, and the air-fuel mixture which consists of a fuel and air is formed in a cylinder.

  The glow plug 22 corresponds to the heating means according to the present invention, and is provided so as to face the inside of the cylinder from the side of the intake side (right side in FIG. 1). The tip of the glow plug 22 is a heat generating part protruding into the cylinder, and the inside of the cylinder is heated by energizing the heat generating part as necessary.

  The glow plug 22 is provided with a glow temperature sensor SW3 (see FIG. 2) for detecting the temperature of the heat generating portion.

  The engine main body 1 configured as described above has a geometric compression ratio set to 16 or more and 22 or less. That is, while the geometric compression ratio of a general gasoline engine is about 9 to 11, the geometric compression ratio of the engine body 1 of this embodiment is a considerably high value of 16 or more and 22 or less. Is set to

  An intake passage 23 and an exhaust passage 24 are connected to the intake port 9 and the exhaust port 10 of the engine body 1, respectively. That is, intake air (fresh air) from the outside is supplied into the cylinder through the intake passage 23, and burned gas (exhaust gas) generated in the cylinder is discharged to the outside through the exhaust passage 24. It has become.

  The intake passage 23 is provided with a throttle valve 25 for adjusting the amount of fresh air that flows through the intake passage 23 and is introduced into the cylinder. The throttle valve 25 is an electronically controlled throttle valve, and is electrically opened and closed according to the opening degree of an accelerator pedal (not shown) provided in a vehicle (a vehicle equipped with the engine of FIG. 1). That is, the accelerator pedal is provided with an accelerator opening sensor SW4 (FIG. 2). Based on the accelerator pedal opening (accelerator opening) detected by the accelerator opening sensor 33, an electric type (not shown) is provided. This actuator opens and closes the throttle valve 25. However, in the engine of the present embodiment, the amount of fresh air is also adjusted by internal EGR (burned gas residual operation) described later, so that the throttle valve 25 is not necessarily driven in proportion to the accelerator opening. Absent.

  The exhaust passage 24 is provided with a catalytic converter 26 for purifying exhaust gas. For example, a three-way catalyst is incorporated in the catalytic converter 26, and harmful components in the exhaust gas passing through the exhaust passage 24 are purified by the action of the three-way catalyst.

(2) Control System FIG. 2 is a block diagram showing an engine control system. The ECU 30 shown in the figure is a device for comprehensively controlling each part of the engine, and includes a well-known CPU, ROM, RAM, and the like.

  Various information from various sensors is input to the ECU 30. For example, the ECU 30 is electrically connected to the engine water temperature sensor SW1, the engine rotational speed sensor SW2, the glow temperature sensor SW3, and the accelerator opening sensor SW4. Various information such as the cooling water temperature Tw, the engine rotation speed Ne, the temperature of the heat generating portion of the glow plug 22 (heat generation temperature) Tg, and the accelerator opening degree Ac are each input to the ECU 30.

  The ECU 30 is also electrically connected to the VVT 15 and 16, the spark plug 20, the injector 21, the glow plug 22, and the throttle valve 25, and outputs drive control signals to these devices. It is configured.

  The specific functions of the ECU 30 will be described. The ECU 30 includes a determination unit 31, a fuel control unit 32, an ignition control unit 32, a glow control unit 34, and a valve control unit 35 as main functional elements. Have.

  Based on the engine speed Ne and the load T (target torque) specified from the detected values of the engine speed sensor SW2 and the accelerator opening sensor SW4, the determination means 31 performs any operation in the control map of FIG. It is determined whether the engine is operating in the region.

  Specifically, in the control map of FIG. 3, the first operation area A1 is set in an area where the engine speed Ne and the load T are relatively low (low rotation / low load area). Further, a second operation region is set in a region on the higher load side than the first operation region A1, and a third operation region is set in a region on the higher rotation side than the first operation region A1 and the second operation region A2. The operation area A3 is set.

  During operation of the engine, which operation region (A1 to A3) in FIG. 3 corresponds to the operation point of the engine (point on the control map specified from each value of the load T and the rotational speed Ne). Accordingly, an appropriate combustion mode is selected. Note that what type of combustion is selected in each operation region will be described later.

  The fuel control means 32 controls the injection amount and timing of fuel injected from the injector 21 into the cylinder. Specifically, the fuel control means 32 includes a load T (target torque) calculated from a detection value (accelerator opening Ac) of the accelerator opening sensor SW4 and the engine rotation speed specified from the engine rotation speed sensor SW2. A target fuel injection amount and injection timing are calculated based on information such as Ne, and the valve opening timing and valve opening period of the injector 21 are controlled based on the calculation result.

  The ignition control means 33 controls the timing (ignition timing) at which the spark plug 20 performs spark discharge. However, in this embodiment, as will be described later, in any of the first to third operation regions A1 to A3 shown in FIG. 3, a combustion mode (compressed self-ignition combustion) that self-ignites the air-fuel mixture irrespective of spark ignition. ) Is selected, the spark ignition from the spark plug 20 is stopped at least when the engine is warm. That is, the spark plug 20 operates only when it is difficult to self-ignite the air-fuel mixture (for example, when forced combustion by spark ignition is required), such as when starting the engine or operating in an extremely cold state, Otherwise it does not work basically.

  The glow control means 34 supplies current to the glow plug 22 to raise the temperature of its heat generating portion, and the heat temperature Tg of the glow plug (temperature of the heat generating portion) is determined based on the detected value of the glow temperature sensor SW3. The temperature is controlled to a desired temperature.

  The valve control means 35 performs control for driving the VVTs 15 and 16 to change the operation timing of the intake and exhaust valves 11 and 12. In particular, in a region where the load T in FIG. 3 is relatively low (the low load side of the first operation region A1 and the third operation region A3), the valve control means 35 is configured to Based on the control of the operation timing, the amount of burnt gas (internal EGR gas) remaining in the cylinder is increased / decreased to adjust the increase in the cylinder temperature.

(3) Combustion mode in each operation region Next, based on the control of the ECU 30 having the above function, what combustion mode is in each operation region (A1, A2, A3) shown in FIG. Explain whether it is selected. As a premise of this explanation, it is assumed that the engine coolant temperature Tw is sufficiently warm (that is, the operation is warm). Therefore, in any case of the above operation regions A1 to A3, the combustion mode (compressed self-ignition combustion) that self-ignites the air-fuel mixture is selected regardless of the spark ignition. However, in order to perform appropriate compression self-ignition combustion, it is necessary to change the fuel injection timing from the injector 21 and the ON / OFF of the glow plug 22 depending on the operation regions A1 to A3, and the ECU 30 sets the operating point of the engine. Such control (control of the injector 21 and the glow plug 22) is executed while sequentially determining.

  That is, when the engine is started, the ECU 30 determines that the engine operating point (load T and rotational speed Ne) is as shown in FIG. 3 based on the detected values of the engine rotational speed sensor SW2 and the accelerator opening sensor SW4. It is sequentially determined which operation region corresponds to the control map. Then, depending on whether the determined operation region is one of the first operation region A1, the second operation region A2, and the third operation region A3 in FIG. To do.

(I) 1st operation area A1
When the engine is operated in the first operation region A1, general premixed compression self-ignition combustion is performed in which an air-fuel mixture of fuel and air is self-ignited by the compression action of the piston 5. Specifically, in the first operation region A1, the injector 21 moves into the cylinder at a stage considerably before the compression top dead center (the top dead center between the compression stroke and the expansion stroke) (for example, during the intake stroke). By injecting fuel, the mixture of the injected fuel and air (new air) introduced into the cylinder from the intake passage 23 is sufficiently heated to a high temperature and pressure by the compression action of the piston 5. Let the mixture self-ignite.

  FIG. 6 shows the fuel injection timing θi (° CA) in the first operation region A1 and the heat generation rate RH (J / deg) generated by combustion based on the fuel injection. In the example of FIG. 6, the fuel injection is started in the first half of the intake stroke, more specifically, when about 30 ° CA has elapsed from the exhaust top dead center (the top dead center between the exhaust stroke and the intake stroke). ing. The fuel injected during the intake stroke is sufficiently mixed with air before reaching the compression top dead center, and the uniform air-fuel mixture formed thereby is compressed and heated to a temperature near the compression top dead center. Self-ignited (premixed compression self-ignition combustion). The waveform J1 of the heat generation rate generated by this combustion has, for example, a shape that starts to rise immediately before the compression top dead center and reaches a peak at a point just past the compression top dead center.

  Here, in the first operation region A1, particularly in the region close to the low load, the fuel injection amount is considerably small, so the compression ratio of the engine of the present embodiment is set to a relatively high value (16 to 22). However, it is considered that the air-fuel mixture cannot be surely self-ignited only by the compression action of the piston 5. Therefore, in the region near the low load in the first operation region A1, the operation timing of the intake / exhaust valves 11 and 12 by the VVT 15 and 16 is set so that the intake valve 11 and the exhaust valve 12 are in the middle of the exhaust stroke to the intake stroke. A period during which both are closed (so-called negative overlap period) is provided. If such a negative overlap period is provided, a part of the high-temperature burned gas generated in the cylinder remains in the cylinder (internal EGR). Rises and promotes self-ignition of the air-fuel mixture. In addition, by leaving the burned gas in the cylinder, the amount of fresh air is adjusted without significantly reducing the throttle valve 25, so that the pumping loss is reduced.

(Ii) Second operation area A2
The second operation region A2 where the engine speed Ne is low and the load T is high is a region where the engine operating point temporarily passes when acceleration is performed as indicated by an arrow X1 in FIG. That is, when the driver depresses the accelerator pedal deeply in order to accelerate the vehicle comparatively vigorously from a state where the vehicle is stopped or traveling at a low speed, first, as indicated by the arrow X1, The operating point of the engine changes in such a manner that only the load T increases rapidly and then the engine speed Ne gradually increases. At this time, the operating point of the engine passes through the second operating region A2 mainly in the early stage of acceleration in which only the load T increases. Hereinafter, the form of acceleration as shown by the arrow X1 is referred to as a first acceleration mode.

  When the operating point of the engine shifts to the second operating region A2 in association with the first acceleration mode, unlike the first operating region A1, the fuel injection timing θi from the injector 21 is set to be greatly delayed, and the compression stroke During the period from the second half to the first half of the expansion stroke, fuel is injected (see FIGS. 6 and 7), and the glow plug 22 is operated to increase the in-cylinder temperature. The latter half of the compression stroke refers to the range from the compression top dead center (the top dead center between the compression stroke and the expansion stroke) to the previous 90 ° CA (crank angle), and the first half of the expansion stroke is the compression upper half. The range from the dead center to 90 ° CA after the lapse.

  The engine is operated in the combustion mode as described above. In the second operation region A2, the load is higher than that in the first operation region A1, and the amount of fuel to be injected is large, so pre-ignition and knocking are likely to occur. Because.

  That is, in the second operation region A2, since the amount of fuel injection is large, the generated thermal energy is large and the temperature in the cylinder is likely to increase. For this reason, when fuel is injected at the same timing (for example, during the intake stroke) as the first operation region A1 with a relatively low load and a small fuel injection amount, the waveform of FIG. As shown in J4, the air-fuel mixture self-ignites at a relatively early timing during the compression stroke, and abnormal combustion (pre-ignition) occurs in which the heat generation rate RH reaches a peak before the compression top dead center. There is a fear.

  At this time, if the fuel injection timing θi into the cylinder is greatly delayed, for example, if the fuel is injected after the latter half of the compression stroke, the time during which the fuel is exposed to high temperature is shortened. It is considered that the pre-ignition as described above can be avoided. However, since the start timing of the self-ignition is delayed with the delay of the fuel injection, this time, as shown by the waveform J5 in FIG. 9B, an abnormality in which a large amount of heat energy is generated at once due to the self-ignition. Combustion (knocking) may occur.

  When the pre-ignition or knocking described above occurs, not only the efficiency of the engine is deteriorated, but also a large noise and vibration are generated, leading to damage to the piston and the like. Therefore, in order to avoid both pre-ignition and knocking and to perform appropriate compression self-ignition combustion, in the second operation region A2, as shown in FIGS. 7 and 8, the fuel injection timing θi is expanded from the latter half of the compression stroke. While setting up to the first half of the stroke, the glow plug 22 is operated to forcibly raise the in-cylinder temperature.

  Specifically, when the operating point of the engine shifts to the second operating region A2, first, as shown in FIG. 7, fuel is injected from the injector 21 in two parts (θ1, θ2) in the second half of the compression stroke and the first half of the expansion stroke. Control (split injection) is performed. By performing such divided injection, the first fuel injection performed in the second half of the compression stroke is small, and the decrease in the in-cylinder temperature due to the latent heat of vaporization of the fuel is suppressed, so the ignition delay time is shortened. For example, as shown in the figure, self-ignition can be caused slightly before the compression top dead center. Thereafter, the second fuel injection is performed in the middle of the combustion based on the first fuel injection (the first half of the expansion stroke), and the combustion caused by the second fuel injection continues, and as shown by the waveform J2 in FIG. A relatively long period of combustion without energy generation is realized. Thereby, generation | occurrence | production of the rapid thermal energy which leads to knocking etc. can be avoided, ensuring the high thermal energy according to load as a whole.

  Further, in the second operation region A2, simultaneously with the execution of the divided injection as described above, control for energizing the glow plug 22 and increasing the temperature Tg of the heat generating portion is started. Then, after a certain amount of time has passed and the glow plug 22 has sufficiently generated heat, the split injection is released, and the timing of fuel injection from the injector 21 is set only in the second half of the compression stroke, as shown in FIG. The

  That is, after the energization of the glow plug 22 is started, it takes a little time (for example, about 1 or 2 seconds) until the temperature Tg of the heat generating portion sufficiently rises. Such divided injection (control for injecting fuel in the second half of the compression stroke and the first half of the expansion stroke) is executed. On the other hand, after the heat generation temperature Tg of the glow plug 22 has sufficiently increased (for example, to 600 ° C. or higher) due to continued energization, even if a relatively large amount of fuel is injected at one time, the self-emission is not significantly delayed from that injection. Since ignition starts, there is no need to worry about abnormal combustion such as knocking, and split injection is no longer necessary. Therefore, in accordance with a sufficient temperature rise of the glow plug 22, the fuel injection form from the injector 21 is changed from the divided injection shown in FIG. 7 to the fuel once in the latter half of the compression stroke as shown in FIG. It is switched to single injection to be injected. As a result, while a relatively large amount of fuel corresponding to the load is injected once in the latter half of the compression stroke, the heat release rate RH peaks slightly after the compression top dead center as shown by the waveform J3 in the figure. Appropriate compression self-ignition combustion can be caused.

(Iii) Third operation area A3
The third operation region A3 having a higher rotational speed Ne than the first and second operation regions A1 and A2 is a region where the operating point of the engine enters when acceleration is performed as indicated by an arrow X2 in FIG. . That is, when the driver keeps stepping on the accelerator pedal shallowly in order to accelerate the vehicle slowly from a state where the vehicle is stopped or traveling at a low speed, the load T The operating point of the engine changes mainly such that only the rotational speed Ne increases gradually without increasing so much. In the process of increasing the rotational speed Ne, the operating point of the engine enters the third operating region A3. Hereinafter, the form of acceleration as shown by the arrow X2 is referred to as a second acceleration mode.

  When the operating point of the engine shifts to the third operating region A3 with the second acceleration mode, the inside of the cylinder is heated using the glow plug 22 as in the control of FIG. 8 described in the second operating region A2. While the air-fuel mixture is ignited, control is performed. That is, in the third operation region A3, since the engine rotational speed Ne is relatively high, the fuel heat receiving period (the time during which the fuel is exposed to a high temperature environment near the compression top dead center) is short, and the air-fuel mixture is not ignited automatically. It's hard to get up. For this reason, the in-cylinder temperature is forcibly increased using the glow plug 22 to create an environment in which the air-fuel mixture easily ignites, and fuel is injected from the injector 21 in the latter half of the compression stroke. Auto-ignite. That is, the use of the glow plug 22 in the third operation region A3 is used not for the purpose of preventing pre-ignition and knocking as in the second operation region A2, but for the purpose of assisting the self-ignition of the air-fuel mixture. The In this case, the fuel injection timing θi from the injector 21 is slightly shifted to the advance side from that in the second operating region A2 because the fuel heat receiving period is short and the air-fuel mixture is difficult to self-ignite.

  In particular, on the low load side in the third operation region A3, by performing internal EGR (operation for leaving high-temperature burned gas in the cylinder), the temperature in the cylinder is further increased, and the air-fuel mixture is surely obtained. Let it ignite.

  Here, even if energization to the glow plug 22 is started immediately after the transition to the third operation region A3, as described above, a certain amount of time (until the temperature Tg of the heat generating portion is sufficiently generated) For example, about 1 second is required. However, during acceleration (indicated by an arrow X2 in FIG. 5), the engine operating point shifts from the first operation region A1 set in the low rotation / low load region to the third operation region A3 on the higher rotation side. In the second acceleration mode shown), the operating point changes relatively slowly unlike in the first acceleration mode indicated by the arrow X1 in FIG. 4, and therefore the first operating region A1 and the third operating region A3. Since the heat generation temperature Tg of the glow plug 22 rises to a sufficient temperature during a slight transition from the boundary to the high rotation side (for example, while passing through the belt-like region A3 ′ shown in FIG. 5), at that time By delaying the fuel injection timing θi from the injector 21 until the latter half of the compression stroke, it is possible to continuously perform the compression self-ignition combustion without causing any serious misfire.

(4) Example of Operation (i) First Acceleration Mode Next, in the first acceleration mode indicated by the arrow X1 in FIG. 4, the fuel injection timing from the injector 21, the energization amount of the glow plug 22, etc. The control method will be described with reference to FIG.

  Each graph of FIG. 10 shows, from the top, the accelerator opening Ac, the engine speed Ne, the engine load T, the fuel injection timing θi from the injector 21, the heat generation temperature (glow temperature) Tg of the glow plug 22, and the glow plug 22. The time change of the energization amount (glow energization amount) Ig is shown. In the example of operation shown in this figure, the engine is initially operated in an idling state, and at a subsequent time point t1, the accelerator pedal is stepped on vigorously and sudden acceleration is started. As a result, the engine load T rises to a fairly high value (about 80% of the total load) in a very short time. In FIG. 10, the time point when the load T reaches a value corresponding to the point P1 (boundary point between the first and second operation regions A1 and A2) in FIG.

  Further, the engine rotation speed Ne starts to increase with the depression of the accelerator pedal as described above. The increase in the rotational speed Ne becomes more gradual than the increase in the load T, and the rotational speed Ne continues to increase gradually even after the accelerator pedal is gradually released after the time point t3. In FIG. 10, a time point at which the engine speed Ne reaches a value corresponding to the point P2 (a boundary point between the second and third operation regions A2 and A3) in FIG. 4 is a time point t6.

  After the time t6, the engine rotational speed Ne increases to a higher rotational speed (about 4500 rpm), and the high rotational speed is maintained for a while. Then, when the accelerator pedal is further loosened at time t7, both the load T and the rotational speed Ne are decreased, and the operation is shifted to the low speed operation (FIG. 4 shows such a change in the operating point during deceleration as indicated by the arrow X1. Shown as'). In FIG. 10, a time point at which the engine speed Ne reaches a value corresponding to the point P3 (boundary point between the first and third operation regions A1 and A3) in FIG. 4 is a time point t8.

  In the case of the operation in the first acceleration mode as described above, the period from the initial state to the time point t2 (the time point when the point P1 in FIG. 4 is reached) immediately after the start of the rapid acceleration corresponds to the first operation region A1. To do. Accordingly, during this period, control (premixed compression self-ignition combustion) is performed in which fuel is injected from the injector 21 during the intake stroke and self-ignition is performed by the compression action of the piston 5 while sufficiently mixing the fuel with air. The At this time, since it is not necessary to heat the inside of the cylinder by the glow plug 22, the energization to the glow plug 22 is stopped.

  On the other hand, the period from the time point t2 to the time point t6 (the time point at which the point P2 in FIG. 4 is reached) corresponds to the second operation region A2, and immediately (at time point t2) the fuel injection from the injector 22 is immediately performed in the latter half of the compression stroke. The split injection divided into two times in the first half of the expansion stroke is executed (W portion in FIG. 10), and energization to the glow plug 22 is started. Then, at the time t4 when the heat generation temperature Tg of the glow plug 22 (detected value of the glow temperature sensor SW3) reaches the predetermined value Tg1 due to the energization, the divided injection is released, and the fuel injection timing θi is once in the latter half of the compression stroke. Set to only. That is, in the second operation region A2 where the load is relatively high, the amount of fuel to be injected is large. Therefore, in order to properly self-ignite the injected large amount of fuel without causing pre-ignition, knocking, etc. Such control is executed.

  Next, since the period from the time point t6 to the time point t8 (the time point at which the point P3 in FIG. 4 is reached) corresponds to the third operation region A3, energization of the glow plug 22 (heating in the cylinder) is performed here. And the fuel injection timing θi is set to once in the latter half of the compression stroke. However, the fuel injection timing θi is slightly shifted to the advance side with respect to the injection timing when the compression stroke injection is performed in the second operation region A2 (periods t2 to t6). That is, the third operation region A3 in which the rotational speed Ne is relatively high and the heat receiving period of the fuel is short by executing the fuel injection in the latter half of the compression stroke (a little earlier time) while continuing the heating by the glow plug 22. However, the air-fuel mixture is surely self-ignited.

  Here, the heating temperature (temperature of the heat generating portion) Tg by the glow plug 22 reaches a predetermined upper limit value Tg2 (for example, about 1000 ° C.) at a time point t5 before the time point t6. In order to avoid an unnecessarily high temperature, the energization amount Ig to the glow plug 22 is reduced. That is, once the heat generating part of the glow plug 22 reaches a certain high temperature, it can maintain a high temperature state even when the energization amount Ig is small. Ig is lowered (afterglow). In the illustrated example, the energization amount Ig is reduced from 100% to about 50% after the time point t5. On the other hand, the heat generation temperature Tg of the glow plug 22 is maintained at substantially the same value as the upper limit value Tg2 even after the energization amount Ig is reduced.

  Finally, in the period after the time point t8 (the time point at which the point P3 in FIG. 4 is reached), the energization of the glow plug 22 is stopped and the injector 21 is turned off in order to correspond to the first operation region A1. The fuel injection timing θi is returned during the intake stroke. However, even if the energization of the glow plug 22 is stopped, the heat generation temperature Tg of the glow plug 22 does not immediately decrease, so during that time, the fuel injection timing θi is gradually returned to the advance side, and the heat generation temperature Tg Is reduced to the original injection timing (first half of the intake stroke) in the first operating state A1. This is because abnormal combustion such as pre-ignition may occur if the injection timing θi is suddenly advanced to the first half of the intake stroke while the heat generation temperature Tg of the glow plug 22 remains high (that is, the in-cylinder temperature remains high). Because.

(Ii) Second Acceleration Mode Next, in the second acceleration mode indicated by the arrow X2 in FIG. 5, how the fuel injection timing from the injector 21 and the energization amount of the glow plug 22 are controlled along with the change in the operating state. Whether this is done will be described with reference to FIG.

  In the operation example shown in FIG. 11, the engine is initially operated at a low speed, and from the time point ta thereafter, the accelerator pedal is gradually depressed to start slow acceleration. Thereby, after the time Ta, the engine speed Ne and the load T are gradually increased. In FIG. 11, the time point tb is the time point at which the rotational speed Ne reaches a value corresponding to the point P4 (boundary point between the first and third operation regions A1, A3) in FIG. After this time tb, the engine rotational speed Ne increases to a higher rotational speed (about 4000 rpm), and the high rotational speed is maintained thereafter.

  In the case of the operation in the second acceleration mode as described above, a period from the initial state to the above-described time tb (a time point at which the point P4 in FIG. 5 is reached) that has passed for a while after the start of the slow acceleration is the first operation region A1. Corresponding to Therefore, during this period, control (premixed compression self-ignition combustion) is performed in which fuel is injected from the injector 21 and self-ignited during the intake stroke. Further, since heating by the glow plug 22 is not required, energization to the glow plug 22 is stopped.

  On the other hand, since the period after the time tb corresponds to the third operation region A3, energization to the glow plug 22 is started immediately (at the first time tb). Then, at the time tc when the heat generation temperature Tg of the glow plug 22 reaches the predetermined value Tg1 'due to the energization, the fuel injection timing θi from the injector 21 is changed and delayed from the first half of the intake stroke to the second half of the compression stroke. That is, by performing the compression stroke injection while heating the inside of the cylinder by the glow plug 22, the air-fuel mixture is surely self-ignited even in the high rotation range where misfire is likely to occur. In the example shown in the figure, the injection timing θi is changed at a time (stepwise) at the time point tc, but the injection timing θi may be gradually changed as the temperature of the glow plug 22 rises.

  Here, the period from the time point tb at which the operation shifts to the third operation region A3 to the time point tc at which the heat generation temperature Tg of the glow plug 22 sufficiently increases (the fuel injection timing θi is delayed in the second half of the compression stroke) This corresponds to a region A3 ′ (a period required for heating the glow plug 22) in FIG. As can be seen from FIG. 11, in the second acceleration mode (slow acceleration), from the time tb when the operation proceeds to the third operation region A3 to the time tc when the heat generation temperature Tg of the glow plug 22 is sufficiently increased Since the engine speed Ne does not increase so much, there is no concern that a serious misfire will occur during that time. After that, the glow plug 22 is sufficiently heated at the time tc, so that the subsequent compression self Ignition combustion is also performed without problems.

  Thereafter, the heat generation temperature Tg of the glow plug 22 reaches the upper limit value Tg2 at the time td. For this reason, after this time point td, the energization amount Ig to the glow plug 22 is reduced (afterglow) in order to avoid a higher temperature than necessary.

(5) Operational effects and the like As described above, the engine of this embodiment includes an injector 21 that injects fuel containing gasoline into the cylinder, and a glow plug 22 (heating means) that forcibly increases the in-cylinder temperature. And an ECU 30 (control means) for controlling the injector 21 and the glow plug 22. Then, under the control of the ECU 30, for example, at the time of acceleration when shifting from the first operation region A1 set in the low rotation / low load region of the engine to the second operation region A2 having a higher load than this (arrow in FIG. 4) (In the first acceleration mode exemplified in X1), the divided injection in which the fuel is injected from the injector 21 in two steps, the second half of the compression stroke and the first half of the expansion stroke, from the time t2 when the operation shifts to the second operation region A2. At the same time, energization of the glow plug 22 is started. Further, after that, at the time t4 when the temperature Tg of the heat generating portion of the glow plug 22 rises to a predetermined value Tg1 or more, the split injection is released, and the fuel injection timing θi from the injector 21 is set only in the latter half of the compression stroke. According to such a configuration, it is possible to appropriately ensure a high output corresponding to the load while preventing abnormal combustion such as knocking during acceleration where the load T increases mainly.

  That is, in the above-described embodiment, by performing the control (split injection) for injecting fuel into two times, the latter half of the compression stroke and the first half of the intake stroke, at the time of relatively sudden acceleration where the load T increases. The mixture can be self-ignited without much delay from the first fuel injection, and the combustion is continued on the basis of the second fuel injection that follows to generate sudden thermal energy that leads to knocking. As a whole, a high output corresponding to the load can be secured.

  Simultaneously with the execution of the divided injection, energization of the glow plug 22 is started, and then the divided injection is canceled after the heat generation temperature Tg of the glow plug 22 has sufficiently increased (to a predetermined value Tg1). Since the fuel injection timing θi is set only in the latter half of the compression stroke, the compression self-ignition combustion can be properly continued while effectively preventing the deterioration of fuel consumption.

  That is, when split injection is executed, the end of combustion is delayed and exhaust loss and the like increase, so if combustion based on such split injection is continuously performed, fuel efficiency during acceleration deteriorates. There is a risk that. On the other hand, in the above-described configuration, the glow plug 22 is sufficiently heated, and even if the divided injection is not performed (even if a large amount of fuel is injected at one time), a state in which the air-fuel mixture quickly self-ignites is created. After that, the fuel is injected once in the latter half of the compression stroke, and the combustion is performed for a short time based on the fuel injection, so that the high output necessary for acceleration is secured and the deterioration of the fuel consumption is minimized. Can be suppressed.

  Moreover, in the said embodiment, at the time of the acceleration which transfers to 3rd driving | operation area | region A3 whose rotational speed Ne is higher than this from said 1st driving | operation area | region A1 (at the time of the 2nd acceleration mode illustrated to the arrow X2 of FIG. 5). In this case, when the energization to the glow plug 22 is started from the time tb when the operation is shifted to the second operation region A3, and then the temperature Tg of the heat generating portion of the glow plug 22 rises to a predetermined value Tg1 ′ or more, the injector The fuel injection timing θi from 21 is set in the latter half of the compression stroke. According to such a configuration, the air-fuel mixture can be surely self-ignited without causing misfire during acceleration such that the rotational speed Ne mainly increases.

  That is, in the third operation region A3 where the rotational speed Ne is high, the time during which the fuel is exposed to high temperature and high pressure (heat receiving period) is short, and the self-ignition of the air-fuel mixture is relatively difficult to occur. At the time of the transition, by injecting fuel in the latter half of the compression stroke while heating the inside of the cylinder using the glow plug 22, it is possible to improve the deterioration of ignitability and to ensure that the air-fuel mixture self-ignites. Of course, even if energization of the glow plug 22 is started at the time of transition to the third operation region A3, the heat generation temperature Tg of the glow plug 22 does not immediately rise sufficiently. However, the acceleration that shifts from the first operation region A1 to the third operation region A3 on the high rotation side is a relatively slow acceleration as shown in FIG. 11, so that the glow plug 22 generates sufficient heat. The rotational speed Ne does not increase so much by the time, and since the fuel injection timing θi is set in the latter half of the compression stroke after the glow plug 22 has sufficiently generated heat, a serious misfire may occur during that time. However, the compression self-ignition combustion is properly continued even immediately after the transition to the third operation region A3.

  Further, in the above embodiment, energization to the glow plug 22 is started with the transition from the first operation area A1 to the second operation area A2 or the third operation area A3, and then the temperature Tg of the glow plug 22 is set to the upper limit value Tg2. Is increased, the energization amount Ig to the glow plug 22 is reduced even if the operation in the second operation area A2 or the third operation area A3 is continued. The reliability can be ensured and the reliability can be ensured, and the ignitability of the air-fuel mixture can be efficiently ensured by causing the glow plug 22 to generate heat with the minimum necessary current.

  In the above-described embodiment, since the fuel injection timing θi from the injector 21 is set during the intake stroke in the first operation region A1 with low rotation and low load, the injected fuel is sufficiently air from the intake stroke to the compression stroke. The uniform air-fuel mixture formed thereby is heated to a high temperature by the compression action of the piston, so that the air-fuel mixture can be surely self-ignited and the combustion efficiency can be further increased.

  Further, in the first operation area A1, since the internal EGR is performed in which a part of the burned gas generated in the cylinder remains in the cylinder, the high-temperature burned gas is used for the self-fuel mixture. Ignition can be promoted, and pumping loss can be effectively reduced to further improve fuel efficiency.

  In the above embodiment, as shown in FIG. 3 and the like, the combustion by the self-ignition of the air-fuel mixture (compression self-ignition combustion) is performed in all the operation regions (first to third operation regions A1 to A3) of the engine. However, the air-fuel mixture may be forcibly ignited by spark ignition by the spark plug 20 at least in the high rotation and high load region (upper right corner in the map region of FIG. 3).

  Moreover, in the said embodiment, immediately after transfering from 1st operation area | region A1 to 2nd operation area | region A2 with a higher load than this, control which divides fuel into 2 steps, a compression stroke second half and an expansion stroke first half (division | segmentation Injection), however, it is sufficient that the divided injection includes at least two fuel injections in the second half of the compression stroke and the first half of the expansion stroke. Three or more divided injections including other times are required. You may go.

  Further, in the above embodiment, at the transition time t2 to the second operation region A2, the split injection in which fuel is injected separately in the second half of the compression stroke and the first half of the expansion stroke is executed, and energization to the glow plug 22 is started. Thereafter, after the heat generation temperature Tg of the glow plug 22 rises to the predetermined value Tg1 (after time t4), the split injection is canceled and fuel is injected only in the latter half of the compression stroke. In the operation region A2, the air-fuel mixture may always be self-ignited by split injection without energizing the glow plug 22. The second operation region A2 is a region that passes temporarily during sudden acceleration, and is not a region that is constantly operated. Therefore, even if split injection is always performed in the same region, the period extends for a long time. This is unlikely to cause significant deterioration in fuel economy.

  In the above embodiment, in order to ensure the ignitability in the first self-ignition region A1, by providing a negative overlap period in which both the intake valve 11 and the exhaust valve 12 are closed from the exhaust stroke to the intake stroke, The internal EGR is performed so that a part of the high-temperature burned gas remains in the cylinder. For example, the exhaust valve 12 is opened not only in the exhaust stroke but also in the intake stroke, so that the burned gas is brought into the cylinder from the intake port. The internal EGR may be realized by reversing the flow.

  In addition, due to the high temperature inside the cylinder due to the internal EGR as described above, the ignition of the air-fuel mixture is performed by igniting the spark plug 20 in an auxiliary manner instead of ensuring the ignitability in a relatively low load region. You may perform what is called ignition assist.

  In the above embodiment, the glow plug 22 is used as a heating means for forcibly increasing the in-cylinder temperature of the engine. However, the present invention is not limited to this as long as the temperature can be raised in a short time.

11 Intake valve 12 Exhaust valve 21 Injector 22 Glow plug (heating means)
30 ECU (control means)
A1 1st operation area A2 2nd operation area A3 3rd operation area Tg1, Tg1 '(Temperature) predetermined value Tg2 (Temperature) upper limit

Claims (7)

Premixing that is driven by fuel containing gasoline and compresses and raises the temperature of the air-fuel mixture, which is a mixture of the fuel and air, at least in the first operating region set at a low engine speed and low load. A compression self-ignition engine,
Heating means for forcibly increasing the in-cylinder temperature of the engine;
An injector for injecting the fuel into the cylinder;
Control means for controlling the heating means and the injector,
The control means includes
When accelerating from the state operating in the first operating region to the second operating region having a higher load than the region, at least a predetermined period after the transition to the second operating region, the second half of the compression stroke, and the expansion While performing split injection in which fuel is injected from the injector divided into at least two times in the first half of the stroke, the air-fuel mixture is self-ignited,
At the time of acceleration such as shifting from the state operating in the first operating region to the third operating region having a higher rotational speed than the first and second operating regions, after the transition to the third operating region, A premixed compression self-ignition engine characterized in that an air-fuel mixture is self-ignited by operating the heating means while setting the fuel injection timing from the injector in the latter half of the compression stroke. The premixed compression self-ignition engine according to claim 1,
A premixed compression self-ignition engine characterized in that the heating means is a glow plug having a heat generating part which generates heat when energized. The premixed compression self-ignition engine according to claim 2,
The control means executes the split injection and starts energization of the glow plug from the time of transition to the second operation region at the time of acceleration of transition from the first operation region to the second operation region. The premixed compression self-ignition engine, wherein the split injection is canceled when the temperature of the heat generating portion of the glow plug rises to a predetermined value or more, and the fuel injection timing from the injector is set only in the latter half of the compression stroke. . The premixed compression self-ignition engine according to claim 2 or 3,
The control means starts energization of the glow plug from the time of transition to the third operation region during acceleration of transition from the first operation region to the third operation region, and then the temperature of the heat generating part of the glow plug is increased. A premixed compression self-ignition engine characterized in that the fuel injection timing from the injector is set in the latter half of the compression stroke when it rises above a predetermined value. The premixed compression self-ignition engine according to claim 3 or 4,
When the temperature of the heat generating part of the glow plug rises to a predetermined upper limit value, the control means energizes the glow plug even if the operation in the second operation region or the third operation region is continued. A premixed compression self-ignition engine characterized by reducing the amount. The premixed compression self-ignition engine according to any one of claims 1 to 5,
The pre-mixing compression self-ignition engine, wherein the upper control means sets the fuel injection timing from the injector in the first operation region during the intake stroke. The premixed compression self-ignition engine according to claim 6,
The control means has a function of controlling the operation of the intake / exhaust valve of the engine, and in the first operation region, a part of the burned gas generated in the cylinder based on the operation control of the intake / exhaust valve. A premixed compression self-ignition engine characterized by executing an internal EGR that causes the fuel to remain in the cylinder.

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