JP2020020322A - Internal combustion engine, and control device of internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine and a control device of an internal combustion engine, which can improve both miscibility of intake air and fuel and the combustion stability even when a fuel injection quantity is small.SOLUTION: A spark ignition internal combustion engine, in which fuel is directly injected into a cylinder, includes; an ignition plug that is provided at the top of the cylinder and has an ignition part; a first fuel injection valve that is provided at a peripheral part of the cylinder and injects at least partial fuel of a fuel injection quantity to be injected in one combustion cycle; and a second fuel injection valve that is provided at the top of the cylinder and injects a small quantity of fuel, which is deducted by the amount of the fuel injected from the first fuel injection valve from the fuel injection quantity to be injected in one combustion cycle, toward the ignition part after the ignition from the first fuel injection valve. The first fuel injection valve can normally atomize fuel of a fuel injection quantity for one combustion cycle, which is set to be capable of generating the maximum output of the internal combustion engine, and the second fuel injection valve can normally atomize fuel of a smaller quantity than the minimum fuel injection quantity that can be normally atomized in the first fuel injection valve.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a spark ignition type internal combustion engine that directly injects fuel into a cylinder and a control device for the internal combustion engine.

  2. Description of the Related Art Conventionally, a spark ignition type internal combustion engine such as a gasoline engine that ignites an air-fuel mixture by a spark plug and burns the mixture is known. As a spark ignition type internal combustion engine, there is an internal combustion engine in which fuel is directly injected into a cylinder.

  In such an internal combustion engine, control of the internal combustion engine may be performed in a predetermined operating state in which the proportion of fuel in the air-fuel mixture is small. For example, Patent Literature 1 discloses a technique in which when raising the temperature of a catalyst provided in an exhaust passage of an internal combustion engine, the air-fuel ratio of the internal combustion engine is made lean and the ignition timing is delayed.

  Further, in order to improve combustion efficiency in a direct injection type internal combustion engine, a technique has been proposed in which one cylinder is provided with two fuel injection valves. For example, Patent Documents 2 and 3 disclose an internal combustion engine in which one fuel injection valve is provided at the top of a cylinder and the other fuel injection valve is provided at the periphery of the cylinder.

JP 2015-187439 A JP 2007-32764 A DE 102 08 044 243 A1

  However, when the air-fuel ratio is set to a lean state as described in Patent Literature 1, combustion stability tends to decrease. On the other hand, it is known that combustion stability is improved by directly injecting fuel near the ignition portion of the ignition plug. This is due to the fact that turbulence is generated by directly injecting fuel near the ignition part, which assists the initial growth of the flame kernel.

  In the internal combustion engines disclosed in Patent Literatures 2 and 3, a part of fuel injected from one fuel injection valve provided at the top of the cylinder is directed to an ignition portion of a spark plug. Patent Document 2 does not disclose the ratio of the amount of fuel injected from two fuel injection valves. Patent Document 3 discloses that a ratio of a fuel injection amount between a fuel injection valve provided at a top portion and a fuel injection valve provided at a peripheral portion is set to 1: 2.

  However, when fuel is injected using two fuel injection valves, mixing of the intake air and the fuel becomes insufficient, and there is a possibility that the emission of particulate matter and nitrogen oxides increases.

  The present invention has been made in view of the above problems, and provides an internal combustion engine and a control apparatus for an internal combustion engine that can improve both the mixing performance and combustion stability of intake air and fuel even when the fuel injection amount is small. To provide.

  According to one aspect of the present invention, in a spark ignition type internal combustion engine in which fuel is directly injected into a cylinder, a spark plug provided at the top of the cylinder and having an ignition portion, and a spark plug provided at a peripheral portion of the cylinder and provided with one combustion A first fuel injection valve for injecting at least a portion of the fuel injection amount injected during the cycle; and a first fuel injection valve provided at the top of the cylinder for injecting fuel during one combustion cycle. A second fuel injection valve for injecting a small amount of fuel excluding fuel injected from the first fuel injection valve toward the ignition unit after injection from the first fuel injection valve; The valve is capable of normally spraying the fuel of the fuel injection amount of one combustion cycle set to be capable of generating the maximum output of the internal combustion engine, and the second fuel injection valve is capable of normally spraying the first fuel injection valve. Smaller than the minimum fuel injection amount Internal combustion engine, wherein the charge is possible normal spraying is provided.

  According to another aspect of the present invention, there is provided a control device for an internal combustion engine for controlling the internal combustion engine, wherein the first fuel injection valve control unit controls the driving of the first fuel injection valve; A second fuel injection valve control unit that controls the driving of the fuel injection valve, wherein the second fuel injection valve control unit operates in a predetermined operating state in which the proportion of fuel in the air-fuel mixture formed in the cylinder is small. The present invention provides a control device for an internal combustion engine, characterized in that a small amount of fuel in a fuel injection amount is injected from a second fuel injection valve toward an ignition section.

  As described above, according to the present invention, even when the fuel injection amount is small, it is possible to improve both the mixability of the intake air and the fuel and the combustion stability.

1 is a schematic diagram illustrating a configuration example of an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a schematic diagram of the internal combustion engine according to the embodiment as viewed from above. FIG. 3 is an explanatory diagram for explaining injection performance of a first fuel injection valve and a second fuel injection valve. It is a schematic diagram which shows the state of the spray seen from the side of the cylinder. FIG. 5 is a schematic view showing a spray state when the cylinder in FIG. 4 is viewed in a direction of an arrow X. FIG. 5 is a schematic view showing a spray state when the cylinder in FIG. 4 is viewed in the direction of arrow Y. FIG. 5 is a schematic diagram showing a spray state when the cylinder of FIG. 4 is viewed in the direction of arrow Z. FIG. 2 is an explanatory diagram illustrating a configuration example of a control device for the internal combustion engine according to the embodiment. 4 is a flowchart of fuel injection control executed by the control device for the internal combustion engine according to the embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1. Configuration example of internal combustion engine>
A configuration example of the internal combustion engine 1 according to the present embodiment will be described with reference to FIGS. FIG. 1 shows a cross section of one cylinder 11 in the internal combustion engine 1 of the present embodiment. FIG. 2 is a schematic view of the internal combustion engine 1 of FIG. 1 as viewed from above.

  The internal combustion engine 1 is an example of a spark ignition type gasoline engine that directly injects fuel into a cylinder 11. The internal combustion engine 1 is a so-called 4-stroke spark ignition gasoline engine, and is mounted on, for example, an automobile and functions as a power source of the automobile.

  The internal combustion engine 1 includes a cylinder 11, an intake valve 21, an exhaust valve 31, an intake camshaft 23, an exhaust camshaft 33, a piston 13, a connecting rod 15, a spark plug 41, a first fuel injection valve 45, and a second fuel injection valve. 43 is provided.

  The piston 13 is slidably housed in the cylinder 11. The space defined by the piston 13 in the cylinder 11 functions as the combustion chamber 5. The shape of the combustion chamber 5 is a so-called pent roof type.

  One end of the connecting rod 15 is supported by the piston 13 via a pin. The other end of the connecting rod 15 is rotatably supported by a crankshaft (not shown). The piston 13 is connected to a crankshaft via a connecting rod 15.

  The intake port 19 and the exhaust port 17 are connected to the cylinder 11, respectively. The intake port 19 is tubular and branches into two from the intake passage 7 and is connected to the combustion chamber 5 (see FIG. 2). The exhaust port 17 is tubular, and the two exhaust ports 17 connected to the combustion chamber 5 join to form one exhaust passage 9 (see FIG. 2).

  The cylinder 11 is provided with two intake valves 21 and two exhaust valves 31. The intake camshaft 23 extends substantially parallel to the crankshaft in a direction in which the two intake valves 21 are arranged. The exhaust camshaft 33 extends substantially parallel to the crankshaft in a direction in which the two exhaust valves 31 are arranged.

  One end of each intake valve 21 is located inside the combustion chamber 5 and at or near a portion where the intake port 19 (branch) opens to the combustion chamber 5. An intake cam 25 contacts the other end of each intake valve 21.

  The intake cam 25 is driven to rotate by the intake camshaft 23. The rotation of the intake cam 25 causes the intake valve 21 to reciprocate. Thereby, the intake valve 21 opens and closes between (the branch of) the intake port 19 and the combustion chamber 5.

  Similarly, when the exhaust cam 35 is rotationally driven by the exhaust cam shaft 33, the exhaust valve 31 reciprocates. Thereby, the exhaust valve 31 opens and closes between (the branch of) the exhaust port 17 and the combustion chamber 5.

  The ignition plug 41 is provided on the top 11 a of the cylinder 11. The ignition portion 41 a provided at the tip of the ignition plug 41 projects into the combustion chamber 5 at a position close to the axis of the cylinder 11 and surrounded by the intake port 19 and the exhaust port 17.

  The first fuel injection valve 45 is provided on the peripheral portion 11b of the cylinder 11. The peripheral portion 11b of the cylinder 11 refers to a region that is located substantially outside the intake port 19 and the exhaust port 17 that open to the cylinder 11. The peripheral portion 11b of the cylinder 11 includes both a surface located in the axial direction of the cylinder 11 and a peripheral surface of the cylinder 11. The tip of the first fuel injection valve 45 projects into the combustion chamber 5 at a position on the outer peripheral side of the intake port 19 and injects fuel into the combustion chamber 5.

  The second fuel injection valve 43 is provided at the top 11 a of the cylinder 11. The top 11 a of the cylinder 11 refers to a region including the axis of the cylinder 11, which is generally surrounded by the intake port 19 and the exhaust port 17 opening to the cylinder 11. The tip of the second fuel injection valve 43 projects into the combustion chamber 5 and injects fuel toward the ignition portion 41 a of the ignition plug 41.

  During the intake stroke of the internal combustion engine 1, the intake valve 21 opens and the volume of the combustion chamber 5 increases, so that air flows into the combustion chamber 5 via the intake port 19. Fuel is injected from the first fuel injection valve 45 or from the first fuel injection valve 45 and the second fuel injection valve 43 in accordance with the inflow of air to form an air-fuel mixture.

  In the compression stroke after the intake stroke, the air-fuel mixture in the combustion chamber 5 is compressed. When the spark plug 41 generates a spark at a predetermined timing, the air-fuel mixture is ignited and burns. This increases the volume of the combustion chamber 5 (combustion stroke).

  Thereafter, the exhaust valve 31 is opened and the volume of the combustion chamber 5 is reduced, so that the air-fuel mixture after combustion flows out of the combustion chamber 5 through the exhaust port 17 (exhaust stroke). The piston 13 reciprocates by combustion with the intake stroke to the exhaust stroke as one combustion cycle. The reciprocating motion is converted into rotational motion of the crankshaft via the connecting rod 15.

<2. Function of First Fuel Injection Valve and Second Fuel Injection Valve>
Next, the functions of the first fuel injection valve 45 and the second fuel injection valve 43 provided in the internal combustion engine 1 will be described in detail.

  The first fuel injection valve 45 is provided on a peripheral portion 11 b of the cylinder 11. In the internal combustion engine 1 according to the present embodiment, the first fuel injection valve 45 is provided on the peripheral portion 11b of the cylinder 11 between the openings of the two intake ports 19 (see FIG. 2). The first fuel injection valve 45 injects fuel excluding the fuel injected from the second fuel injection valve 43 out of the fuel injection amount injected during one combustion cycle.

  The first fuel injection valve 45 has a function of injecting most of the fuel injection amount set according to the required torque to be output to the internal combustion engine 1 during the intake stroke to form a mixture in the combustion chamber 5. The front end of the first fuel injection valve 45 projects into the combustion chamber 5 near the opening of the intake port 19 and injects fuel toward the airflow introduced through the intake port 19.

  The first fuel injection valve 45 has, for example, five or more relatively many injection holes. Thus, the fuel injected from the first fuel injection valve 45 can be widely injected toward the entire combustion chamber 5.

  The second fuel injection valve 43 is provided on the top 11 a of the cylinder 11. The second fuel injection valve 43 injects a small amount of fuel out of the fuel injection amount injected during one combustion cycle toward the ignition portion 41a of the ignition plug 41.

  The second fuel injection valve 43 has a function of injecting a small amount of fuel toward the ignition portion 41a at the time of the ignition operation of the air-fuel mixture by the ignition plug 41, and imparting turbulent flow generation kinetic energy to the formed flame kernel. . Thereby, the flame is efficiently propagated to the entire air-fuel mixture in the combustion chamber 5, and the combustion stability is improved.

  The second fuel injection valve 43 has, for example, one to three injection holes. By injecting fuel from a small number of injection holes, the accuracy of injecting a small amount of fuel toward the ignition portion 41a of the ignition plug 41 can be improved.

  Each of the first fuel injection valve 45 and the second fuel injection valve 43 is a control valve including, for example, an electromagnetic actuator or an electrostrictive actuator. The first fuel injection valve 45 and the second fuel injection valve 43 are controlled by a control device (ECU: Electronic Control Unit).

  Responsiveness of the control valve from the start of power supply to the actuator until the valve is opened, responsiveness from the stop of power supply to the actuator until the valve is closed, the total cross-sectional area of the injection hole and the fuel passage area, etc. The injection performance of the control valve differs depending on the type.

  When the injection performance of the control valve is different, the maximum fuel injection amount that allows normal spraying in one combustion cycle is different. Further, depending on the injection performance of the control valve, not only the maximum fuel injection amount but also the minimum fuel injection amount for normal spraying differs.

  The normal sprayable state refers to a state in which the injected fuel is atomized without forming droplets.

  FIG. 3 is an explanatory diagram for explaining the injection performance of the first fuel injection valve 45 and the second fuel injection valve 43. 3 shows the fuel injection amount Q_fl of one combustion cycle set to be able to generate the maximum output of the internal combustion engine 1. The first fuel injection valve 45 is configured to inject the fuel of the fuel injection amount Q_fl during at least one combustion cycle.

  In the center of FIG. 3, the minimum fuel injection amount Q_min of the first fuel injection valve 45 that allows normal spraying is shown. The first fuel injection valve 45 configured to inject the fuel injection amount Q_fl capable of generating the maximum output of the internal combustion engine 1 cannot normally spray the fuel less than the minimum fuel injection amount Q_min.

  The right side in FIG. 3 shows a combustion auxiliary injection amount Q_com required to impart turbulent flow kinetic energy to the flame kernel formed by the ignition operation of the ignition plug 41. The second fuel injection valve 43 is configured to be capable of injecting the fuel of the combustion auxiliary injection amount Q_com.

  In the internal combustion engine 1 according to the present embodiment, in order to suppress the mixing of the fuel and air respectively injected from the first fuel injection valve 45 and the second fuel injection valve 43 from becoming insufficient, in the intake stroke, The first fuel injection valve 45 injects most of the target fuel injection amount.

  In addition, at the time of the ignition operation after the mixture is formed in the combustion chamber 5, the second fuel injection valve 43 injects a very small amount of fuel to assist combustion into the mixture. Therefore, the second fuel injection valve 43 has a performance capable of injecting the fuel having the combustion auxiliary injection amount Q_com smaller than the minimum fuel injection amount Q_min that can be normally sprayed by the first fuel injection valve 45.

  For example, the fuel injection amount from the second fuel injection valve 43 in one combustion cycle may be in the range of 5 to 15% of the fuel injection amount from the first fuel injection valve 45.

  4 to 7 show states of spraying by the first fuel injection valve 45 and the second fuel injection valve 43. FIG. 4 is a schematic diagram showing a spray state as viewed from the side of the cylinder 11 along the axial direction of the intake camshaft. FIG. 5 is a schematic diagram showing a spray state when the cylinder 11 of FIG. 4 is viewed in the direction of arrow X. FIG. 6 is a schematic diagram showing a spray state when the cylinder 11 of FIG. 4 is viewed in the direction of arrow Y. FIG. 7 is a schematic diagram showing a spray state when the cylinder 11 of FIG. 4 is viewed in the direction of arrow Z.

  4 to 7, the spray from the first fuel injection valve 45 is shown by dot hatching, and the spray from the second fuel injection valve 43 is shown by cross hatching. 4 to 7 show an example in which the first fuel injection valve 45 has six injection holes and the second fuel injection valve 43 has two injection holes.

  The first fuel injection valve 45 provided on the peripheral portion 11b of the cylinder 11 injects fuel over a wide range through six injection holes directed to the entire combustion chamber 5. The injected fuel is mixed with air introduced through the intake port 19 to form an air-fuel mixture in the combustion chamber 5.

  Therefore, most of the target injection amount set in accordance with the required output of the internal combustion engine 1 during the intake stroke is injected from the first fuel injection valve 45 over a wide range. As a result, an air-fuel mixture uniformly mixed and dispersed in the combustion chamber 5 can be formed.

  The second fuel injection valve 43 provided at the top 11a of the cylinder 11 injects a very small amount of fuel through two injection holes directed to the ignition portion 41a of the ignition plug 41.

  Therefore, when the air-fuel mixture formed in the combustion chamber 5 is ignited by the ignition plug 41, a small amount of fuel is injected from the second fuel injection valve 43 to impart turbulent flow kinetic energy to the flame kernel. Thereby, the flame can be efficiently propagated to the entire combustion chamber 5 to improve the combustion stability.

  Since the fuel injected from the second fuel injection valve 43 is a very small amount of fuel for assisting combustion, there is a possibility that the fuel injected from the first fuel injection valve 45 and the air are prevented from being uniformly mixed and dispersed. Reduced.

<3. Configuration example of control device>
A configuration example of a control device 100 that controls the internal combustion engine 1 according to the present embodiment will be described with reference to FIG. An example of the configuration of the control device 100 described below is an operation mode in which a small amount of fuel is injected into the air-fuel mixture formed in the cylinder 11 by a small amount of fuel injection by the second fuel injection valve 43 (hereinafter, referred to as a “lean combustion mode”). ).

  FIG. 8 is a block diagram functionally showing a configuration example of the control device 100. The control device 100 includes an operation mode setting unit 101, a target injection amount calculation unit 103, a first fuel injection valve control unit 107, a second fuel injection valve control unit 105, and a spark plug control unit 109.

  A part or all of the control device 100 may be configured by, for example, a microcomputer or a microprocessor unit. In this case, some or all of the above-described units constituting the control device 100 may be functions realized by executing a program by a microcomputer or the like.

  Further, a part or the whole of the control device 100 may be configured by an updatable device such as firmware, or may be a program module or the like executed by a command from a CPU (Central Processing Unit) or the like.

  The control device 100 includes a storage element or a storage device (not shown) such as a random access memory (RAM) or a read only memory (ROM). The control device 100 further includes a drive circuit (not shown) for driving the ignition plug 41, the first fuel injection valve 45, and the second fuel injection valve 43.

(Operation mode setting section)
The operation mode setting unit 101 sets an operation mode of the internal combustion engine 1. The operation mode setting unit 101 can set the operation mode of the internal combustion engine 1 to the lean combustion mode. The lambda value of the air-fuel mixture supplied to the cylinder 11 of the internal combustion engine 1 in the lean combustion mode may be in the range of 2.0 to 3.0.

  The lean combustion mode is set when, for example, a catalyst such as a three-way catalyst provided in the exhaust passage 9 of the internal combustion engine 1 is heated and activated. In this case, the operation mode setting unit 101 may determine whether to set the operation mode to the lean combustion mode by acquiring the catalyst temperature information.

  However, the lean combustion mode is not limited to the case of activating the catalyst, and may be set for other purposes.

(Target injection amount calculation unit)
The target injection amount calculation unit 103 calculates a target fuel injection amount Q_tgt according to the required output of the internal combustion engine 1. The method for calculating the target fuel injection amount Q_tgt is not particularly limited. For example, the target injection amount calculation unit 103 calculates a target fuel injection amount Q_tgt based on the required output of the internal combustion engine 1 and the rotation speed of the internal combustion engine 1 with reference to an injection amount map stored in advance.

(First fuel injection valve control unit)
The first fuel injector control unit 107 controls the driving of the first fuel injector 45. When the operation mode is set to the lean combustion mode, the first fuel injection valve control unit 107 mainly performs the first fuel injection in the intake stroke mainly on the amount of fuel obtained by subtracting the combustion auxiliary injection amount Q_com from the target fuel injection amount Q_tgt. Inject from valve 45.

  When the operation mode is not set to the lean combustion mode, the first fuel injection valve control unit 107 injects the fuel having the target fuel injection amount Q_tgt from the first fuel injection valve 45 mainly in the intake stroke.

(Second fuel injection valve control unit)
The second fuel injector control unit 105 controls the driving of the second fuel injector 43. The second fuel injection valve control unit 105 drives the second fuel injection valve 43 when the operation mode is set to the lean combustion mode, and adjusts the fuel amount of the combustion auxiliary injection amount Q_com according to the ignition operation of the ignition plug 41. To the ignition part 41a.

  The combustion auxiliary injection amount Q_com may be a fixed value set in advance or a variable value according to the target fuel injection amount Q_tgt.

  When the operation mode is not set to the lean combustion mode, the second fuel injector control unit 105 stops driving the second fuel injector 43 and does not perform the fuel injection by the second fuel injector 43. It may be.

  In the control device 100 according to the present embodiment, a small amount of fuel for assisting the combustion in the lean combustion mode in which the ratio of the fuel in the air-fuel mixture is small and the combustion stability tends to decrease is directed to the ignition portion 41a of the ignition plug 41. It is configured to inject.

(Spark plug control unit)
The spark plug control unit 109 controls the driving of the spark plug 41. The spark plug control unit 109 drives the spark plug 41 according to the ignition timing appropriately set according to the operation state, and ignites the mixture formed in the combustion chamber 5.

<4. Operation example of internal combustion engine>
An example of a control process performed by the control device 100 will be described with reference to FIG. FIG. 9 shows a flowchart of the fuel injection control executed by the control device 100.

  The target injection amount calculation unit 103 of the control device 100 calculates a target fuel injection amount Q_tgt (Step S11). For example, the target injection amount calculation unit 103 calculates the required output of the internal combustion engine 1 based on the required acceleration such as the amount of depression of the accelerator pedal and the information on the rotation speed of the internal combustion engine 1, and refers to the injection amount map. The target fuel injection amount Q_tgt is calculated based on the information on the required output and the number of revolutions.

  Next, the first fuel injection valve control unit 107 and the second fuel injection valve control unit 105 of the control device 100 determine whether or not the operation mode of the internal combustion engine 1 is set to the lean combustion mode (step S13).

  When the operation mode is not set to the lean combustion mode (S13 / No), the first fuel injection valve control unit 107 of the control device 100 drives the first fuel injection valve 45 in the intake stroke of each cylinder 11 to drive the first fuel injection valve 45. The fuel of the target fuel injection amount Q_tgt is injected into the combustion chamber 5 (step S21).

  As a result, the fuel is dispersed and mixed with the air introduced into the combustion chamber 5 during the intake stroke, and a mixture is formed in the combustion chamber 5.

  Next, the ignition plug control unit 109 of the control device 100 drives the ignition plug 41 at an ignition timing appropriately set according to the operation state to ignite the mixture formed in the combustion chamber 5 (step S23).

  Thereby, the flame propagates into the combustion chamber 5 and the air-fuel mixture in the combustion chamber 5 burns. When the proportion of fuel in the air-fuel mixture is not small, the flame easily propagates into the combustion chamber 5 and combustion stability is easily maintained.

  On the other hand, when the operation mode is set to the lean combustion mode in step S13 (S13 / Yes), the first fuel injection valve control unit 107 drives the first fuel injection valve 45 in the intake stroke of each cylinder 11. Then, the fuel other than the combustion auxiliary injection amount Q_com from the target fuel injection amount Q_tgt is injected into the combustion chamber 5 (step S15).

  Next, the second fuel injection valve control unit 105 of the control device 100 drives the second fuel injection valve 43 in accordance with or immediately before the ignition timing appropriately set in accordance with the operation state, and calculates the combustion auxiliary injection amount Q_com. The fuel is injected toward the ignition portion 41a of the ignition plug 41 (step S17).

  Next, the ignition plug control unit 109 drives the ignition plug 41 in accordance with the ignition timing to ignite the air-fuel mixture formed in the combustion chamber 5 (step S19). At this time, turbulent flow generation kinetic energy is applied to the flame kernel formed because fuel is being injected from the second fuel injection valve 43 toward the ignition portion 41a.

  Thus, even when the proportion of fuel in the air-fuel mixture is small, the flame efficiently propagates over the entire combustion chamber 5 and the combustion stability is improved.

  As described above, the internal combustion engine 1 according to the present embodiment is provided in the peripheral portion 11b of the cylinder 11 and is capable of normally spraying the fuel having the fuel injection amount Q_fl set to be able to generate the maximum output of the internal combustion engine 1. One fuel injection valve 45 is provided. Further, the internal combustion engine 1 includes a second fuel injection valve 43 provided at the top 11a of the cylinder 11 and capable of normal spraying of a smaller amount of fuel than the minimum fuel injection amount Q_min of the first fuel injection valve 45 capable of normal spraying. .

  Therefore, a very small amount of fuel can be injected from the second fuel injection valve 43 toward the ignition portion 41a of the ignition plug 41. Therefore, even when the proportion of fuel in the air-fuel mixture is small, turbulence generating kinetic energy can be imparted to the flame kernel formed by the ignition operation of the ignition plug 41, and the combustion stability can be improved.

  Further, in the internal combustion engine 1 according to the present embodiment, since the fuel that is injected during the intake stroke to form the air-fuel mixture is injected from one first fuel injection valve 45, the mixing of the air and the fuel may be insufficient. Can be reduced.

  Further, the control device 100 for the internal combustion engine 1 according to the present embodiment causes the first fuel injection valve 45 to inject the fuel of the target fuel injection amount Q_tgt when the operation mode of the internal combustion engine 1 is not set to the lean combustion mode. . On the other hand, when the operation mode is set to the lean combustion mode, control device 100 directs a very small amount of fuel of target fuel injection amount Q_tgt from second fuel injection valve 43 to ignition portion 41a of ignition plug 41. Inject.

  Therefore, even when the proportion of fuel in the air-fuel mixture is small, turbulence generating kinetic energy can be imparted to the flame kernel formed by the ignition operation of the ignition plug 41, and the combustion stability can be improved. As a result, the emission amount of particulate matter and nitrogen oxides can be suppressed.

  Further, the control device 100 for the internal combustion engine 1 according to the present embodiment supplies fuel for forming an air-fuel mixture from one first fuel injection valve 45 during the intake stroke regardless of whether the operation mode is the lean combustion mode. Inject. Therefore, the possibility that mixing of air and fuel becomes insufficient can be reduced.

  As described above, the internal combustion engine 1 and the control device 100 of the internal combustion engine 1 according to the present embodiment can improve both the mixability of intake air and fuel and the combustion stability. As a result, the emission amount of particulate matter and nitrogen oxides can be suppressed.

  As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 11 ... Cylinder, 11a ... Top part, 11b ... Peripheral part, 41 ... Spark plug, 41a ... Ignition part, 43 ... Second fuel injection valve 45, a first fuel injection valve, 100, a control device, 101, an operation mode setting unit, 103, a target injection amount calculation unit, 105, a second fuel injection valve control unit , 107... First fuel injection valve controller, 109... Spark plug controller

Claims (6)

In a spark ignition type internal combustion engine (1) in which fuel is directly injected into a cylinder (11),
An ignition plug (41) provided at the top (11a) of the cylinder (11) and having an ignition section (41a);
A first fuel injection valve (45) provided in a peripheral portion (11b) of the cylinder (11), for injecting at least a part of fuel in a fuel injection amount injected during one combustion cycle;
A small amount of fuel provided at the top (11a) of the cylinder (11) and excluding fuel injected from the first fuel injection valve (45) out of the fuel injection amount injected during one combustion cycle, A second fuel injection valve (43) that injects toward the ignition section (41a) after injection from the first fuel injection valve (45),
The first fuel injection valve (45) is capable of normally spraying fuel having a fuel injection amount of one combustion cycle set to be capable of generating the maximum output of the internal combustion engine (1),
The internal combustion engine, wherein the second fuel injection valve (43) can normally spray a smaller amount of fuel than a minimum fuel injection amount that can be normally sprayed by the first fuel injection valve (45). The fuel injection amount from the second fuel injection valve (43) is in the range of 5 to 15% of the fuel injection amount from the first fuel injection valve (45). An internal combustion engine according to claim 1. The internal combustion engine according to claim 1 or 2, wherein the second fuel injection valve (43) includes one to three injection holes directed to the ignition part (41a). The second fuel injection valve (43) imparts turbulent flow generation kinetic energy to a flame kernel formed by an ignition operation of the ignition plug (41) by the small amount of fuel injection. An internal combustion engine according to any one of claims 1 to 3. An internal combustion engine control device (100) for controlling an internal combustion engine (1) according to any one of the preceding claims,
A first fuel injection valve control unit (107) for controlling driving of the first fuel injection valve (45);
A second fuel injection valve control unit (105) for controlling the driving of the second fuel injection valve (43);
The second fuel injection valve control unit (105) includes:
In a predetermined operating state in which the proportion of fuel in the air-fuel mixture formed in the cylinder (11) is small, the fuel injection amount from the second fuel injection valve (43) toward the ignition portion (41a) is increased. A control device for an internal combustion engine, which injects a small amount of fuel. The predetermined operating state is:
It is at least one of an operation state in which the lambda value of the air-fuel mixture is in the range of 2-3, or an operation state in which the temperature of the catalyst provided in the exhaust passage (9) of the internal combustion engine (1) is increased. The control device for an internal combustion engine according to claim 5, wherein

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