JP5012594B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine in which a piston reciprocates in a cylinder.

  In a spark ignition type internal combustion engine that ignites an air-fuel mixture in a combustion chamber by an ignition plug, an internal combustion engine that injects fuel into an intake port that introduces air into the cylinder is widely used. For example, Patent Document 1 discloses an internal combustion engine provided with fuel injection valves in two intake ports.

JP 2006-125333 A (0031, 0032, FIG. 5)

  In an internal combustion engine in which a piston reciprocates in a cylinder, fuel may adhere to the inner surface of the cylinder on the exhaust port side. Further, when fuel is injected into the intake port, the fuel adheres to the intake valve and the intake port. Such fuel was discharged from the cylinder as unburned fuel and was not burned effectively. The present invention has been made in view of the above, and an object thereof is to reduce the adhesion of fuel to the inside of an internal combustion engine.

In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention is a space in a cylinder in which a piston reciprocates, a combustion space in which a mixture of fuel and air burns, A plurality of intake passages that are open to connect to the combustion space; and a fuel supply unit that is provided in each intake passage and injects the fuel, and each of the fuel supply units sends the fuel to the combustion space. with injecting along a direction crossing with each other internally, depending on the operating conditions of the internal combustion engine, the combustion mode of the internal prior Symbol combustion space, providing a time difference in the fuel injection timing of said plurality of fuel supply means homogeneous combustion And switching to stratified combustion with simultaneous fuel injection timings of the plurality of fuel supply means .

In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention is a space in a cylinder in which a piston reciprocates, a combustion space in which a mixture of fuel and air burns, A first intake passage and a second intake passage which are connected to the combustion space and open; a first fuel supply means which is provided in the first intake passage and injects the fuel; and the second intake passage. And a second fuel supply means for injecting the fuel, wherein the first fuel supply means and the second fuel supply means intersect the fuel inside the combustion space. with injecting along the direction, in response to said operating condition of the internal combustion engine, fuel before SL internal combustion mode of the combustion space, wherein the fuel injection timing of the first fuel supply means the second fuel supply means a homogeneous combustion to provide the injection timing and the secondary time difference, And switches the fuel injection timing of the serial first fuel supply means and the fuel injection timing of the second fuel supply means to the stratified combustion to the same time.

  As a result, fuel sprays from all the fuel supply means are injected so as to intersect within the combustion space, so that the fuel reaching the inner surface of the cylinder on the exhaust port side is reduced. Further, the fuel spray injected by the pair of fuel supply means disposed symmetrically with respect to the plane orthogonal to the crankshaft of the internal combustion engine passing through the central axis of the cylinder is formed near the plane, and the intake valve and the intake valve Since it passes through the gap with the mouth, the amount of fuel adhering to the intake passage and intake valve can be reduced.

In a preferred embodiment of the present invention, in the internal combustion engine, the stratified combustion is performed when operating in a region where a large amount of exhaust gas is recirculated to the combustion space, and the homogeneous combustion is performed using a large amount of exhaust gas in the combustion space. It is preferable that the operation is performed when the vehicle is not operated in the recirculation region and the accelerator opening is larger than the accelerator opening threshold .

  As a preferred aspect of the present invention, in the internal combustion engine, when the combustion mode in the combustion space is stratified combustion, the fuel injection timing is higher than when the combustion mode in the combustion space is homogeneous combustion. Is preferably retarded.

  The present invention can reduce the adhesion of fuel to the inside of an internal combustion engine.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, or those that are substantially the same, so-called equivalent ranges.

  In this embodiment, in an internal combustion engine including a plurality of intake passages that are connected to a combustion space in a cylinder in which a piston reciprocates and opens, fuel supply means (for example, a fuel injection valve) that injects fuel into each intake passage And each fuel supply means injects fuel in a direction in which the fuel sprays injected by the fuel supply means intersect within the combustion space.

  FIG. 1 is an explanatory diagram showing an internal combustion engine according to the present embodiment. In the following description, a single cylinder provided in the internal combustion engine 1 is taken out and described. However, the present invention can be applied regardless of a multi-cylinder internal combustion engine or a single cylinder internal combustion engine. The internal combustion engine 1 is a so-called reciprocating internal combustion engine in which a piston 5 reciprocates inside a cylinder 1S.

  The internal combustion engine 1 is controlled by an engine ECU (Electronic Control Unit) 50. The cylinder 1S of the internal combustion engine 1 is a cylindrical structure having one end attached to the cylinder head 1H and the other end attached to the crankcase 1C. A space 1B surrounded by the inner surface 1SW of the cylinder 1S, the top surface of the piston 5, and the inner surface of the cylinder head 1H is a space in which the fuel F supplied to the internal combustion engine 1 burns. This space 1B is called combustion space 1B. The fuel F supplied to the internal combustion engine 1 is a fuel containing hydrocarbons, for example, gasoline.

  A water jacket WJ is formed in the cylinder 1S. During operation of the internal combustion engine 1, water (cooling water) for cooling the internal combustion engine 1 is passed through the water jacket WJ to cool the internal combustion engine 1. The temperature of the cooling water is detected by the cooling water temperature sensor 42, taken into the engine ECU 50, and used for controlling the internal combustion engine 1.

  The cylinder head 1H has a first intake port 4A that is a first intake passage for introducing air (combustion air) A for combustion of the fuel F into the combustion space 1B and a second intake passage that is a second intake passage. An intake port 4B is formed. Thus, the internal combustion engine 1 includes a plurality of intake passages (intake ports) that are connected to the combustion space 1B and open. Further, an exhaust port 9 is formed in the cylinder head 1H of the internal combustion engine 1 as an exhaust passage for discharging the combustion gas (exhaust gas) Ex after the fuel F is burned in the combustion space 1B to the outside of the combustion space 1B.

  The first intake port 4A, the second intake port 4B, and the exhaust port 9 are connected to the combustion space 1B, respectively, and one end of each of the combustion space 1B is opened to form an opening. Each other end opens at 1H. A first intake valve 10A and a second intake port are provided in an opening (first intake port) 4Ao of the first intake port 4A that opens into the combustion space 1B and an opening (second intake port) 4Bo of the second intake port 4B, respectively. A valve 10B is disposed, and an exhaust valve 15 is disposed at an opening (exhaust port) 9o of the exhaust port 9 that opens into the combustion space 1B. The first intake valve 10A opens and closes the first intake port 4Ao, the second intake valve 10B opens and closes the second intake port 4Bo, and the exhaust valve 15 opens and closes the exhaust port 9o.

  The fluid (air A or air A and fuel F) flowing in from the first intake port 4A and the second intake port 4B forms a tumble flow T in the combustion space 1B. The tumble flow T is directed from the first intake port 4A and the second intake port 4B to the exhaust port 9 on the cylinder head 1H side, and from the exhaust port 9 to the first intake port 4A and the second intake port near the top 5T of the piston 5. This is a flow toward the intake port 4B. The direction of the tumble flow T is not limited to this, and may be the opposite direction. The top 5T of the piston 5 is formed with a recess 5U so as not to inhibit the flow of the tumble flow T.

  The internal combustion engine 1 includes a first port injection valve 2 </ b> A in the first intake port 4 </ b> A as a first fuel supply unit that supplies the internal combustion engine 1, and a second fuel supply unit that supplies the internal combustion engine 1 as a second fuel supply unit. A port injection valve 2B is provided in the second intake port 4B. An ignition plug 7 is attached to the cylinder head 1H of the internal combustion engine 1 as ignition means for igniting an air-fuel mixture of fuel F and air A formed in the combustion space 1B.

  The air-fuel mixture in the combustion space 1B is ignited by the discharge from the spark plug 7 and burns. Thus, the internal combustion engine 1 is a so-called spark ignition type internal combustion engine. Here, the number of intake ports that are intake passages is not limited to two, and the number of port injection valves that are fuel supply means is not limited to two.

  The first port injection valve 2A and the second port injection valve 2B are attached to the port injection valve fuel distribution pipe 20, and their operations are controlled by the engine control unit 53 of the engine ECU 50. The first port injection valve 2A and the second port injection valve 2B are supplied with fuel from the port injection valve fuel distribution pipe 20, and inject the fuel F toward the first intake port 4Ao and the second intake port 4Bo. To do. As a result, the fuel F is supplied to the internal combustion engine 1. The fuel F injected from the first port injection valve 2A and the second port injection valve 2B becomes fuel spray and mixes with the air A flowing through the first intake port 4A and the second intake port 4B, and enters the combustion space 1B. Inflow. An air-fuel mixture of air A and fuel F is formed in the combustion space 1B.

  A throttle valve 14 is attached to an intake introduction passage 8 that is an intake passage connected to the first intake port 4A and the second intake port 4B. The throttle valve 14 includes a valve body 14V and a throttle valve actuator 14A that is attached to and operates the valve body 14V. By adjusting the opening of the valve body 14V, the passage cross-sectional area of the intake air introduction passage 8 changes, and the amount of air A introduced into the combustion space 1B is adjusted.

  An air flow sensor 40 is disposed upstream of the valve body 14V of the throttle valve 14 in the flow direction of the air A, and flows into the combustion space 1B, that is, the flow rate (mass flow rate) of the air A flowing through the intake passage. The flow rate of air A is measured. The flow rate of the air A measured by the air flow sensor 40 is taken into the engine ECU 50 and used for controlling the internal combustion engine 1. An air cleaner 70 is arranged upstream of the air flow sensor 40 in the flow direction of the air A. The air cleaner 70 flows into the intake air introduction passage 8 and dust or dust from the air A flowing into the combustion space 1B of the internal combustion engine 1. Is removed.

  The fuel F injected from the first port injection valve 2 </ b> A and the second port injection valve 2 </ b> B is stored in the fuel tank 19. A feed pump 13 is disposed inside the fuel tank 19. The feed pump 13 and the port injector fuel distribution pipe 20 are connected by a fuel pipe 18, and the fuel F in the fuel tank 19 discharged from the feed pump 13 passes through the fuel pipe 18 and is a fuel for the port injector. It is sent to the distribution pipe 20. The operation of the feed pump 13 is controlled by the engine control unit 53 of the engine ECU 50.

  When the first intake valve 10A and the second intake valve 10B are opened and the piston 5 moves toward the bottom dead center, the air A and the fuel F flow from the first intake port 4Ao and the second intake port 4Bo toward the combustion space 1B. The air-fuel mixture flows in (intake stroke). Here, the fuel F is supplied from the first port injection valve 2A and the second port injection valve 2B to the first intake port 4A and the second intake port 4B before the intake stroke. The injection mode is referred to as intake asynchronous injection. In the internal combustion engine 1, the fuel F may be injected from the first port injection valve 2 </ b> A and the second port injection valve 2 </ b> B in the intake stroke, and this fuel F injection mode is called intake synchronous injection.

  When the piston 5 passes the bottom dead center and the piston 5 heads to the top dead center (that is, the direction of the cylinder head 1H) with the first intake valve 10A, the second intake valve 10B, and the exhaust valve 15 closed, the combustion space The mixture of fuel F and air A formed in 1B is compressed (compression stroke). Before the piston 5 reaches top dead center, the spark plug 7 discharges and ignites the compressed air-fuel mixture. Thereby, the air-fuel mixture in the combustion space 1B burns. Here, the ignition timing of the spark plug 7 is controlled by the engine control unit 53 of the engine ECU 50.

  The piston 5 moves toward the bottom dead center by the combustion pressure when the air-fuel mixture burns (expansion stroke). The piston 5 that has passed through the bottom dead center moves again toward the top dead center. At this time, the exhaust valve 15 is opened, and the combustion gas (exhaust gas Ex) in the combustion space 1B passes through the exhaust port 9o to the exhaust port. 9 (exhaust stroke). This completes one cycle of the internal combustion engine. The exhaust gas Ex discharged to the exhaust port 9 is collected in an exhaust passage (for example, exhaust manifold) 9M, purified by the purification catalyst 71, and then released into the atmosphere. The fuel F in the next cycle is supplied from the first port injection valve 2A and the second port injection valve 2B into the first intake port 4A and the second intake port 4B, for example, during the exhaust stroke.

  When the piston 5 comes close to top dead center, the first intake valve 10A and the second intake valve 10B are opened, the exhaust valve 15 is closed, and the next cycle of the internal combustion engine 1 is started. Thus, the internal combustion engine 1 is a four-stroke one-cycle internal combustion engine in which one cycle is completed while the piston 5 reciprocates twice within the cylinder 1S. The reciprocating motion of the piston 5 is transmitted to the crankshaft 6 in the crankcase 1C via the connecting rod 3 and converted into rotational motion.

  The rotation angle of the crankshaft 6 is detected by a crank angle sensor 41. The engine control unit 53 of the engine ECU 50 takes in the rotation angle of the crankshaft 6 detected by the crank angle sensor 41 and calculates the rotation speed (engine rotation speed) of the crankshaft 6 based on this. Here, the engine rotational speed is the rotational speed of the crankshaft 6 per unit time.

  As shown in FIG. 1, the first intake port 4 </ b> A and the second intake port 4 </ b> B and the exhaust passage 9 </ b> M where the exhaust gas Ex from the exhaust port 9 is collected are connected by an exhaust gas recirculation passage 16. The exhaust gas recirculation passage 16 is provided with a valve device (hereinafter referred to as an exhaust gas recirculation control valve) 17 controlled by the engine ECU 50. The exhaust gas recirculation control valve 17 has a function of changing the cross-sectional area of the exhaust gas recirculation passage 16 (the area of the cross section orthogonal to the flow direction of the exhaust gas Ex flowing through the exhaust gas recirculation passage 16).

  As a result, the exhaust passage 9M communicates with the first intake port 4A and the second intake port 4B through the exhaust gas recirculation passage 16, and the communication between the exhaust passage 9M and the first intake port 4A and the second intake port 4B is cut off. To do. As a result, the exhaust gas Ex in the exhaust passage 9M is introduced into the first intake port 4A and the second intake port 4B, or the introduction of the exhaust gas Ex into the first intake port 4A and the second intake port 4B is stopped. Can do.

  As the exhaust gas recirculation control valve 17, for example, an ON-OFF valve or a flow rate adjustment valve can be used. When an ON-OFF valve is used as the exhaust gas recirculation control valve 17, the amount of exhaust gas Ex flowing through the exhaust gas recirculation passage 16 can be adjusted by changing the ratio between the open time and the close time. When a flow rate adjusting valve is used as the exhaust gas recirculation control valve 17, the passage sectional area of the exhaust gas recirculation passage 16 is changed by adjusting the opening of the exhaust gas recirculation control valve 17, that is, the exhaust gas recirculation control valve 17. Thus, the amount of the exhaust gas Ex flowing through the exhaust gas recirculation passage 16 can be adjusted.

  When exhaust gas recirculation (hereinafter referred to as EGR (Exhaust Gas Recirculation)) is performed during operation of the internal combustion engine 1, the exhaust gas recirculation control valve 17 is opened, and the exhaust gas recirculation passage 16 is connected to the first intake port 4A and the first intake port. 2 Exhaust gas Ex discharged from the combustion space 1B is returned to the combustion space 1B via the intake port 4B. And the air-fuel mixture of the fuel F and the air A is burned in the state where the exhaust gas Ex exists in the combustion space 1B. This suppresses the generation of nitrogen oxides and reduces the fuel consumption of the internal combustion engine 1.

  Next, the engine ECU 50 will be described. The engine ECU 50 includes an input / output unit 50IO, a processing unit 50P, and a storage unit 50M that stores various maps used for controlling the internal combustion engine 1. The input / output unit 50IO includes an air flow sensor 40, a crank angle sensor 41, a coolant temperature sensor 42, an accelerator opening sensor 43, a first port injection valve 2A, a second port injection valve 2B, a spark plug 7, a feed pump 13, The throttle valve actuator 14A and the exhaust gas recirculation control valve 17 are connected. The input / output unit 50IO inputs / outputs input signals from the airflow sensor 40, the crank angle sensor 41, and the like, and output signals to the first port injection valve 2A, the second port injection valve 2B, and the like.

  The processing unit 50P includes, for example, a memory and a CPU (Central Processing Unit). The processing unit 50P includes a control condition determination unit 51, a fuel injection control unit 52, and an engine control unit 53. The storage unit 50M is a non-volatile memory such as a flash memory, a memory that can only be read such as a ROM (Read Only Memory), a memory that can be read and written such as a RAM (Random Access Memory), or a combination thereof. Can be configured. The storage unit 50M stores a control program used for controlling the internal combustion engine 1, a control data map, and the like.

  FIG. 2 is a schematic diagram showing a state in which an intake valve that opens and closes an intake port formed in the cylinder head of the internal combustion engine according to the present embodiment is opened. The internal combustion engine 1 according to the present embodiment is directed in a direction in which the sprays of fuel F injected by the respective fuel supply means, that is, the first port injection valve 2A and the second port injection valve 2B intersect within the combustion space 1B. The first port injection valve 2A and the second port injection valve 2B inject fuel F. When realizing this, the first port injection valve 2A and the second port injection valve 2B inject the fuel F by the intake synchronous injection described above.

  As shown in FIG. 2, the intake-synchronized injection is performed between the umbrella portion 12A of the first intake valve 10A and the first intake port 4Ao and between the umbrella portion 12B and the second intake port of the second intake valve 10B in the intake stroke. When there is a gap with 4Bo, fuel F is injected from the first port injection valve 2A and the second port injection valve 2B.

  In this case, the fuel F is injected so that the spray of the fuel F injected by the first port injection valve 2A and the second port injection valve 2B intersects inside the combustion space 1B. Accordingly, the first port injection valve 2A injects the fuel F toward the gap RA closer to the central axis (cylinder central axis) Z of the cylinder 1S shown in FIG. 2 than the stem 11A of the first intake valve 10A. Further, the second port injection valve 2B injects the fuel F toward the gap RB closer to the cylinder center axis Z than the stem 11B of the second intake valve 10B. That is, the fuel F is injected between the first intake valve 10A and the second intake valve 10B, more specifically, between the stem 11A and the stem 11B. As a result, the fuel F spray injected by the first port injection valve 2A and the fuel F spray injected by the second port injection valve 2A flow into the combustion space 1B.

  In the present embodiment, the intake F synchronous injection, that is, the spray of the fuel F injected from the first port injection valve 2A and the second port injection valve 2B while the first intake valve 10A and the second intake valve 10B are open. The fuel F is injected from the first port injection valve 2A and the second port injection valve 2B so as to intersect within the combustion space 1B. As a result, the fuel spray passes through the gap between the intake valve and the intake port formed near the cylinder center axis Z, so that the first intake port 4A, the second intake port 4B, the first intake valve 10A, the first intake valve 2 The amount of fuel F adhering to the intake valve 10B can be reduced. Further, since the fuel spray from the first port injection valve 2A and the second port injection valve 2B is injected so as to intersect within the combustion space 1B, it reaches the inner surface 1SW of the cylinder 1S on the exhaust port 9o side shown in FIG. The fuel F to be reduced decreases. As a result, the adhesion of fuel to the inside of the internal combustion engine 1 is suppressed, and the injected fuel spray is reliably introduced into the combustion space 1B. As a result, the latent heat of vaporization of the fuel F is effectively used for cooling the air A, and knocking is improved (intake air temperature reduction effect) and the intake air filling amount into the combustion space 1B is increased (intake air temperature is reduced by reducing the intake air temperature). The effect of (mass increase) is reliably obtained.

  In addition, the fuel F injected from the first port injection valve 2A and the second port injection valve 2B is supplied to the first intake port 4Ao and the second intake air by the air A flowing in from the first intake port 4Ao and the second intake port 4Bo. It is diffused into the cylinder 1S by a strong flow toward the piston 5, that is, a tumble flow T (FIG. 1) formed between the port 4Bo. In this process, the fuel F and the air A are sufficiently mixed. Further, since the fuel F heading toward the inner surface 1SW of the cylinder 1S is reduced by the tumble flow T, the amount of the fuel F adhering to the inner surface 1SW of the cylinder 1S is reduced. As a result, the fuel dilution of the lubricating oil that lubricates the sliding portion of the internal combustion engine 1 can be suppressed, and the unburned fuel F discharged from the combustion space 1B can be reduced.

  The fuel F spray injected by the first port injection valve 2A is directed toward the gap RA, and the fuel F spray injected by the second port injection valve 2B is directed toward the gap RB, and within the combustion space 1B. The injection direction of each fuel F is set so that both intersect. That is, the direction of spraying of fuel F by the first port injection valve 2A and the direction of spraying of fuel F by the second port injection valve 2B are close to a plane passing through the cylinder center axis Z and orthogonal to the crankshaft 6 shown in FIG. , So that the sprays of both fuels F approach each other. Thus, when the fuel F is simultaneously injected from the first port injection valve 2A and the second port injection valve 2B, the spray of the fuel F injected by the first port injection valve 2A and the fuel F injected by the second port injection valve 2B The spray intersects and collides. When there are three or more port injection valves that are intake passages and fuel supply means, fuel is injected so that fuel sprays injected from all the fuel supply means intersect.

  FIGS. 3A and 3B are schematic diagrams illustrating fuel injection modes when the internal combustion engine according to the present embodiment is operated by homogeneous combustion. FIGS. 4A and 4B are schematic diagrams illustrating fuel injection modes when the internal combustion engine according to the present embodiment is operated by stratified combustion. In the present embodiment, the internal combustion engine 1 is operated by switching the combustion mode in the combustion space 1B between homogeneous combustion and stratified combustion according to the operating conditions of the internal combustion engine 1.

  When operating the internal combustion engine 1 with homogeneous combustion, in order to sufficiently diffuse the fuel F into the air A inside the cylinder 1S (inside the combustion space 1B), the fuel F is injected at the initial stage of the intake stroke, and the first port A time difference is provided between the fuel injection timing of the injection valve 2A and the fuel injection timing of the second port injection valve 2B. Accordingly, as shown in FIG. 3A, the fuel spray (first fuel spray) FmA from the first port injection valve 2A and the fuel spray (second fuel spray) FmB from the second port injection valve 2B are Do not collide. The tumble flow T shown by the two-dot chain line in FIG. 3-2, that is, the first fuel spray FmA and the strong flow toward the piston 5 formed between the first intake port 4Ao and the second intake port 4Bo. The fuel of the second fuel spray FmB is diffused into the air A. In the present embodiment, since the recess 5U is formed at the top of the piston 5, the attenuation of the tumble flow T can be suppressed, so that the fuel in the fuel spray Fm is sufficiently diffused into the air A. After the fuel is sufficiently diffused into the air A and a homogeneous air-fuel mixture Gm is formed in the cylinder 1S (in the combustion space 1B), the air-fuel mixture is ignited by the spark plug 7. The initial stage of the intake stroke is, for example, a range of 400 degrees to 350 degrees before ignition top dead center, and preferably a range of 420 degrees to 360 degrees before ignition top dead center.

  When the internal combustion engine 1 is operated by stratified combustion, the fuel F is injected at the latter stage of the intake stroke, and when the internal combustion engine 1 is operated by stratified combustion, the fuel injection timing of the first port injection valve 2A and the second port injection The fuel injection timing of the valve 2B is set at the same time. As a result, as shown in FIG. 4A, the first fuel spray FmA and the second fuel spray FmB collide with each other in the combustion space 1B and between the first intake port 4Ao and the second intake port 4Bo. . The latter stage of the intake stroke is, for example, in the range of 220 degrees to 180 degrees before ignition top dead center, and preferably in the range of 200 degrees to 240 degrees before ignition top dead center. That is, in stratified combustion, the fuel injection timing is retarded as compared with homogeneous combustion.

  While the fuel F is atomized by the collision between the fuel sprays described above, the fuel F is prevented from diffusing into the entire combustion space 1B. Further, it is formed between the first intake port 4Ao and the second intake port 4Bo by injecting the fuel F later in the intake stroke, that is, by retarding the fuel injection timing rather than the homogeneous combustion. The tumble flow T is weakened, the diffusion of the fuel F is suppressed, and the atomized fuel F remains in the vicinity of the spark plug 7. As a result, as shown in FIG. 4B, a layer of the air-fuel mixture Gm is formed in the vicinity of the spark plug 7, and stratification in the combustion space 1B is promoted. After the air-fuel mixture Gm is formed in the vicinity of the spark plug 7, the air-fuel mixture is ignited by the spark plug 7.

  For example, when a large amount of exhaust gas Ex is introduced into the combustion space 1B by the execution of EGR, combustion deterioration such as reduction in the ignitability of the air-fuel mixture Gm or loss of flame occurs. However, according to the stratified combustion of the present embodiment, a layer of the air-fuel mixture Gm can be effectively created in the vicinity of the spark plug, so that combustion deterioration can be suppressed.

  Here, for example, as shown in FIG. 3A and FIG. 4A, the axis (first spray axis) ZFA of the first fuel spray FmA and the axis (second spray axis) ZFB of the second fuel spray FmB May be crossed. In this way, the first fuel spray FmA and the second fuel spray FmB can be reliably crossed inside the combustion space 1B, and in the case of stratified combustion, both can be reliably collided. When there are three or more fuel supply means (for example, port injection valves), the axis of fuel spray injected from all the fuel supply means may be crossed.

  Even if the first spray axis ZFA and the second spray axis ZFB do not intersect with each other, the fuel may be injected so that the first fuel spray FmA and the second fuel spray FmB intersect in the combustion space 1B. When there are three or more fuel supply means, the fuel may be injected so that the fuel sprays injected from all the fuel supply means intersect. Next, fuel supply control of the internal combustion engine according to this embodiment will be described.

  FIG. 5 is a flowchart showing the procedure of fuel supply control of the internal combustion engine according to the present embodiment. 6 to 9 are conceptual diagrams of data maps in which control information used for fuel supply control of the internal combustion engine according to the present embodiment is described. In executing the fuel supply control (hereinafter referred to as fuel supply control) of the internal combustion engine according to the present embodiment, in step S101, the control condition determination unit 51 constituting the processing unit 50P of the engine ECU 50 starts the internal combustion engine 1. (Elapsed time after starting) t is acquired and compared with a predetermined elapsed time threshold tc after starting.

  When it is determined No in step S101, that is, when the control condition determination unit 51 determines that t ≦ tc, the fuel supply control according to the present embodiment is not executed. This is because the state of the internal combustion engine 1 is not stable when a predetermined time (post-start elapsed time threshold tc) has not elapsed after the internal combustion engine 1 is started.

  When it is determined Yes in step S101, that is, when the control condition determining unit 51 determines that t> tc, the process proceeds to step S102. In step S102, the control condition determination unit 51 acquires the cooling water temperature Tw of the internal combustion engine 1 from the cooling water temperature sensor 42, and compares it with the cooling water temperature threshold value Twc. The coolant temperature threshold value Twc is used to determine whether or not the warm-up of the internal combustion engine 1 has been completed.

  When it is determined No in step S102, that is, when the control condition determining unit 51 determines that Tw ≦ Twc, the warm-up of the internal combustion engine 1 is not completed, so the fuel supply control according to this embodiment is performed. Do not execute. When it is determined Yes in step S102, that is, when the control condition determining unit 51 determines that Tw> Twc, the warm-up of the internal combustion engine 1 is completed, and the process proceeds to step S103.

  In step S103, the control condition determination unit 51 determines whether or not the internal combustion engine 1 is operated in a region where a large amount of EGR, that is, a large amount of exhaust gas Ex is recirculated to the combustion space 1B. The mass EGR is, for example, a case where EGR is executed at 80% or more of the maximum EGR rate assumed in the internal combustion engine 1. Here, the EGR rate is Qe / (Qe + Qa) × where Qe is the amount of exhaust gas Ex introduced into the combustion space 1B and Qa is the amount of air A introduced into the combustion space 1B (intake air amount). 100 (%).

  When a large amount of exhaust gas Ex is introduced into the combustion space 1B, the air-fuel mixture in the combustion space 1B becomes difficult to burn, and combustion deterioration such as misfire and disappearance of flame tends to occur. For this reason, in this embodiment, when mass EGR is performed, the internal combustion engine 1 is operated by stratified combustion to suppress deterioration of combustion. For this reason, in step S103, it is determined whether or not the internal combustion engine 1 is operated in a region where large-volume EGR is performed.

  A region in which EGR is executed is determined based on the load factor KL of the internal combustion engine 1 and the engine speed Ne, and the EGR rate at that time is determined. The data map shown in FIG. 6 describes EGR rates (E1, E2, E3) according to the load factor KL of the internal combustion engine 1 and the engine speed Ne. This data map is referred to as an EGR rate setting map 60. A region where the EGR rate is outside E1 is a region where EGR is not executed, that is, EGR rate = 0. In addition, an area indicated by EGR_L in the EGR rate setting map 60 is an area where large-scale EGR is executed.

  The control condition determination unit 51 obtains the engine speed Ne based on the signal of the crankshaft 6 detected by the crank angle sensor 41 shown in FIG. 1, and the intake air amount of the internal combustion engine 1 obtained from the signal detected by the airflow sensor 40. A load factor KL is obtained based on Qa. When the load factor KL and the engine speed Ne are obtained, the control condition determination unit 51 gives the load factor KL and the engine speed Ne to the EGR rate setting map 60 shown in FIG. It is determined whether or not the engine 1 is operating.

  When it determines with No in step S103, ie, when the control condition determination part 51 determines with the internal combustion engine 1 not being drive | operated in the area | region which performs mass EGR, it progresses to step S104. In step S104, the control condition determination unit 51 acquires the accelerator opening OA from the accelerator opening sensor 43, and compares it with a predetermined accelerator opening threshold OAc.

  In the homogeneous combustion, the fuel F and the air A are sufficiently mixed and then ignited, so that the combustion proceeds smoothly, so that a high output can be obtained. When the accelerator opening OA is larger than the accelerator opening threshold OAc, it can be determined that the driver is requesting a high output from the internal combustion engine 1, so the internal combustion engine 1 is operated by homogeneous combustion. Thus, the accelerator opening threshold value OAc is used to determine whether or not to operate the internal combustion engine 1 with homogeneous combustion.

  When it is determined No in step S104, that is, when the control condition determination unit 51 determines that OA ≦ OAc, it can be determined that the internal combustion engine 1 is not required to output high power and that a large amount of EGR is not executed. In this case, the fuel supply control according to the present embodiment is not executed, and for example, fuel is injected from the first port injection valve 2A and the second port injection valve 2B by intake asynchronous injection.

  If it is determined Yes in step S104, that is, if the control condition determination unit 51 determines that OA> OAc, it can be determined that the internal combustion engine 1 is required to have a high output. In this case, in step S105, the control condition determination unit 51 determines to operate the internal combustion engine 1 in the homogeneous combustion mode. Proceeding to step S106, the fuel injection control unit 52 constituting the processing unit 50P of the engine ECU 50 determines the fuel injection timing and the fuel injection amount of the first port injection valve 2A and the second port injection valve 2B. In this case, the fuel injection timing and the fuel injection amount in the homogeneous combustion are determined.

  When the total fuel supply amount determined by the operating conditions of the internal combustion engine 1 is τa, the fuel injection amounts of the first port injection valve 2A and the second port injection valve 2B are τa / 2, respectively. As described above, in the homogeneous combustion mode, a time difference is provided between the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B. The data map of FIG. 7 is a homogeneous fuel first fuel injection timing map 61 describing the fuel injection timing of the first port injection valve 2A, and the data map of FIG. 8 is the fuel injection timing of the second port injection valve 2B. 2 is a second fuel injection timing map 62 at the time of homogeneous combustion.

  The homogeneous fuel first fuel injection timing map 61 and the homogeneous combustion second fuel injection timing map 62 are both at the crank angle before ignition top dead center (BTDC) with reference to ignition top dead center. The fuel injection timing is described. The homogeneous fuel first fuel injection timing map 61 and the homogeneous combustion second fuel injection timing map 62 both describe the fuel injection timing in relation to the engine speed Ne of the internal combustion engine 1 and the load factor KL. is there. That is, if the engine speed Ne and the load factor KL of the internal combustion engine 1 are given to the first fuel injection timing map 61 at the time of homogeneous combustion and the second fuel injection timing map 62 at the time of homogeneous combustion, the corresponding fuel injection timing can be obtained.

  In the first fuel injection timing map 61 at the time of homogeneous combustion shown in FIG. 7, the fuel injection timing of the first port injection valve 2A is away from the advance side, that is, the ignition top dead center side in the order of ISA1, ISA2, ISA3, ISA4. Migrate to Since ISA1, ISA2, ISA3, and ISA4 are represented by the crank angle before ignition top dead center (BTDC) with reference to ignition top dead center, ISA1 <ISA2 <ISA3 <ISA4. In other words, the larger the crank angle before the ignition top dead center, the more advanced.

  In the homogeneous combustion second fuel injection timing map 62 shown in FIG. 8, the fuel injection timing of the second port injection valve 2B shifts to the advance side, that is, the ignition top dead center side in the order of ISB1 and ISB2. Since ISB1 and ISB2 are expressed by crank angles before ignition top dead center (BTDC), ISB1 <ISB2.

  Of the fuel injection timings of the first port injection valve 2A, ISA1 is the most retarded side, that is, the latest fuel injection timing with respect to the ignition top dead center. Of the fuel injection timings of the second port injection valve 2B, ISB2 is the fuel injection timing that is the most advanced, that is, the earliest fuel injection timing with respect to the ignition top dead center. Comparing ISA1 and ISB2, ISB2 is retarded from ISA1, that is, later than the ignition top dead center (ISA1> ISB2). Thus, since the fuel injection timing ISB2 on the most advanced side of the second port injection valve 2B is on the more retarded side than the fuel injection timing ISA1 on the most retarded side of the first port injection valve 2A, the same load factor is obtained. At KL and the engine speed Ne, the first port injection valve 2A always injects fuel earlier than the second port injection valve 2B.

  As can be seen from the first fuel injection timing map 61 at the time of homogeneous combustion and the second fuel injection timing map 62 at the time of homogeneous combustion, in this embodiment, as the load factor KL increases, the fuel injection timing of the first port injection valve 2A and the second fuel injection timing The fuel injection timing of the port injection valve 2B is shifted to the advance side. Since the fuel injection amount τ also increases as the load factor KL increases, the fuel injection timing is advanced as the load factor KL increases, so that the fuel increased by the increase in the load factor KL is reliably injected. It can be introduced into the combustion space 1B.

  In this embodiment, the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B are shifted to the advance side as the engine speed Ne increases. Since the period during which fuel can be injected is shortened by increasing the engine speed Ne, the fuel injection timing is set to the advance side as the engine speed Ne increases, so that all fuel can be reliably introduced into the combustion space 1B.

  In step S106, the fuel injection control unit 52 obtains the engine speed Ne based on the signal of the crankshaft 6 detected by the crank angle sensor 41, and the intake air amount of the internal combustion engine 1 obtained from the signal detected by the airflow sensor 40. A load factor KL is obtained based on Qa. Then, the fuel injection control unit 52 gives the obtained engine speed Ne and load factor KL to the first fuel injection timing map 61 at the time of homogeneous combustion and the second fuel injection timing map 62 at the time of homogeneous combustion, and the first port injection. The fuel injection timing of the valve 2A and the fuel injection timing of the second port injection valve 2B are determined.

  When the fuel injection timing and fuel injection amount of the first port injection valve 2A and the second port injection valve 2B are determined in step S106, the process proceeds to step S107. In step S107, the fuel injection control unit 52 injects fuel from the first port injection valve 2A and the second port injection valve 2B at the fuel injection timing and the fuel injection amount determined in step S106. As a result, the first fuel spray FmA and the second fuel spray FmB injected into the combustion space 1B at the beginning of the intake stroke do not collide, and the fuel diffuses into the air by the tumble flow T shown in FIG. 3-2. Thus, a homogeneous air-fuel mixture is formed in the combustion space 1B. The engine control unit 53 sets an appropriate ignition timing according to the operating conditions of the internal combustion engine 1, discharges from the spark plug 7, and ignites the air-fuel mixture in the combustion space 1B. As described above, since the air-fuel mixture in the combustion space 1B is sufficiently homogeneous, good combustion can be obtained.

  Next, it returns to step S103 and demonstrates. When it is determined Yes in step S103, that is, when the control condition determining unit 51 determines that the internal combustion engine 1 is operating in the region where the large amount of EGR is performed, the process proceeds to step S108, where the control condition determining unit 51 Then, it is determined that the internal combustion engine 1 is operated in the stratified combustion mode. Next, in step S106, the fuel injection control unit 52 determines the fuel injection timing and the fuel injection amount of the first port injection valve 2A and the second port injection valve 2B. In this case, the fuel injection timing and fuel injection amount in stratified combustion are determined.

  Assuming that the total fuel supply amount determined by the operating conditions of the internal combustion engine 1 is τa, the fuel injection amounts of the first port injection valve 2A and the second port injection valve 2B are respectively τa / 2 as described above. Further, as described above, in the stratified combustion mode, the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B are made the same. The data map of FIG. 9 is a stratified combustion fuel injection timing map 63 describing the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B during stratified combustion.

  The stratified combustion fuel injection timing map 63 describes the fuel injection timing at the crank angle (BTDC) before the ignition top dead center with reference to the ignition top dead center. The stratified combustion fuel injection timing map 63 describes the fuel injection timing in relation to the engine speed Ne of the internal combustion engine 1 and the load factor KL. That is, if the engine speed Ne and the load factor KL of the internal combustion engine 1 are given to the stratified combustion fuel injection timing map 63, the fuel injection timings of the corresponding first port injection valve 2A and second port injection valve 2B can be obtained. .

  In the stratified combustion fuel injection timing map 63 shown in FIG. 9, the fuel injection timings of the first port injection valve 2A and the second port injection valve 2B are advanced, that is, the ignition top dead center side in the order of IS1, IS2, IS3. Move away from. Since IS1, IS2, and IS3 are expressed by the crank angle before ignition top dead center (BTDC) with respect to ignition top dead center, IS1 <IS2 <IS3. In other words, the larger the crank angle before the ignition top dead center, the more advanced.

  Of the fuel injection timings during stratified combustion, IS3 is the most advanced fuel injection timing, that is, the earliest fuel injection timing with respect to ignition top dead center during stratified combustion. On the other hand, among the fuel injection timings of the second port injection valve 2B at the time of homogeneous combustion, ISB1 is the most retarded side, that is, at the time of homogeneous combustion, the fuel injection timings and the second ports of all the first port injection valves 2A. Among the fuel injection timings of the injection valve 2B, this is the latest fuel injection timing with respect to the ignition top dead center.

  Comparing IS3 and ISB1, IS3 is retarded from ISB1, that is, later than the ignition top dead center (IS3 <ISB1). In this way, since the fuel injection timing IS1 on the most advanced angle side in the stratified combustion is on the more retarded side than the fuel injection timing ISB1 on the most retarded side in the homogeneous combustion, the load factor KL and the engine speed Ne are the same. Then, the fuel is always injected later in the stratified combustion than in the homogeneous combustion.

  As can be seen from the stratified combustion fuel injection timing map 63, in this embodiment, as the load factor KL increases, the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B are advanced. Transition. Since the fuel injection amount τ also increases as the load factor KL increases, the fuel injection timing is advanced as the load factor KL increases, so that the fuel increased by the increase in the load factor KL is reliably injected. It can be introduced into the combustion space 1B.

  In this embodiment, the fuel injection timing of the first port injection valve 2A and the fuel injection timing of the second port injection valve 2B are shifted to the advance side as the engine speed Ne increases. Since the period during which fuel can be injected is shortened by increasing the engine speed Ne, the fuel injection timing is set to the advance side as the engine speed Ne increases, so that all fuel can be reliably introduced into the combustion space 1B.

  In step S106, the fuel injection control unit 52 obtains the engine speed Ne based on the signal of the crankshaft 6 detected by the crank angle sensor 41, and the intake air amount of the internal combustion engine 1 obtained from the signal detected by the airflow sensor 40. A load factor KL is obtained based on Qa. Then, the fuel injection control unit 52 gives the obtained engine speed Ne and the load factor KL to the stratified combustion fuel injection timing map 63, and the fuel injection timing of the first port injection valve 2A and the second port injection valve 2B. The fuel injection timing is determined.

  When the fuel injection timing and fuel injection amount of the first port injection valve 2A and the second port injection valve 2B are determined in step S106, the process proceeds to step S107. In step S107, the fuel injection control unit 52 injects fuel from the first port injection valve 2A and the second port injection valve 2B at the fuel injection timing and the fuel injection amount determined in step S106. As a result, the first fuel spray FmA and the second fuel spray FmB injected in the latter stage of the intake stroke collide in the combustion space 1B to atomize the fuel, and the fuel diffuses throughout the combustion space 1B. Is suppressed. As a result, an air-fuel mixture layer is formed in the vicinity of the spark plug 7 as shown in FIG.

  The engine control unit 53 sets an appropriate ignition timing according to the operating conditions of the internal combustion engine 1, discharges from the spark plug 7, and ignites the air-fuel mixture in the combustion space 1B. Further, the engine control unit 53 opens the exhaust gas recirculation control valve 17 shown in FIG. 1 to a predetermined opening, and executes EGR. According to the above procedure, even if a large amount of exhaust gas Ex is present in the combustion space 1B due to a large amount of EGR, since the air-fuel mixture layer is formed in the vicinity of the spark plug 7, deterioration of combustion is suppressed.

  As described above, in the present embodiment, in an internal combustion engine having a plurality of intake passages, fuel supply means for injecting fuel is provided in each intake passage, and the fuel supply means is configured to perform fuel spray injected by each fuel supply means. Fuel is injected in a direction that intersects within the combustion space. As a result, fuel sprays from all the fuel supply means are injected so as to intersect within the combustion space, so that the fuel reaching the inner surface of the cylinder on the exhaust port side is reduced. Further, the fuel spray injected by the pair of fuel supply means disposed symmetrically with respect to the plane orthogonal to the crankshaft of the internal combustion engine passing through the central axis of the cylinder is closer to the central axis of the cylinder (more specifically, the above-mentioned Since it passes through the gap between the intake valve and the intake port formed near the plane, the amount of fuel adhering to the intake passage and the intake valve can be reduced. As a result, the amount of fuel adhering to the inside of the internal combustion engine is reduced, so that the injected fuel spray is reliably introduced into the combustion space. Thus, the latent heat of vaporization of the fuel is effectively used for cooling the air, so that knocking can be reliably improved and the amount of intake air charged into the combustion space is increased.

  As described above, the internal combustion engine according to the present invention is useful for an internal combustion engine having a fuel injection valve in an intake port, and particularly suitable for generating an air-fuel mixture suitable for homogeneous combustion and stratified combustion in a combustion space. ing.

It is explanatory drawing which shows the internal combustion engine which concerns on this embodiment. It is a mimetic diagram showing the state where the intake valve which opens and closes the intake port formed in the cylinder head of the internal-combustion engine concerning this embodiment opened. It is a schematic diagram which shows the aspect of fuel injection in the case of operating the internal combustion engine which concerns on this embodiment by homogeneous combustion. It is a schematic diagram which shows the aspect of fuel injection in the case of operating the internal combustion engine which concerns on this embodiment by homogeneous combustion. It is a schematic diagram which shows the aspect of fuel injection in the case of operating the internal combustion engine which concerns on this embodiment by stratified combustion. It is a schematic diagram which shows the aspect of fuel injection in the case of operating the internal combustion engine which concerns on this embodiment by stratified combustion. It is a flowchart which shows the procedure of the fuel supply control of the internal combustion engine which concerns on this embodiment. It is a conceptual diagram of the data map in which the control information used for the fuel supply control of the internal combustion engine which concerns on this embodiment was described. It is a conceptual diagram of the data map in which the control information used for the fuel supply control of the internal combustion engine which concerns on this embodiment was described. It is a conceptual diagram of the data map in which the control information used for the fuel supply control of the internal combustion engine which concerns on this embodiment was described. It is a conceptual diagram of the data map in which the control information used for the fuel supply control of the internal combustion engine which concerns on this embodiment was described.

Explanation of symbols

1 Internal combustion engine 1B Combustion space (space)
1C Crankcase 1H Cylinder head 1S Cylinder 1SW Inner surface 2A 1st port injection valve 2B 2nd port injection valve 3 Connecting rod 4A 1st intake port 4B 2nd intake port 4Ao 1st intake port 4Bo 2nd intake port 5 Piston 5T Top 5U Recessed portion 6 Crankshaft 7 Spark plug 8 Intake introduction passage 9 Exhaust port 9o Exhaust port 9M Exhaust passage 10A First intake valve 10B Second intake valve 11A, 11B Stem 12A, 12B Umbrella portion 15 Exhaust valve 20 Port fuel distribution pipe for injection valve 40 Airflow sensor 41 Crank angle sensor 42 Cooling water temperature sensor 43 Accelerator opening sensor 50 Engine ECU
50IO Input / output unit 50M Storage unit 50P Processing unit 51 Control condition determination unit 52 Fuel injection control unit 53 Engine control unit 60 EGR rate setting map 61 First fuel injection timing map during homogeneous combustion 62 Second fuel injection timing map during homogeneous combustion 63 Fuel injection timing map during stratified combustion

Claims (4)

A space in the cylinder in which the piston reciprocates, and a combustion space in which a mixture of fuel and air burns;
A plurality of intake passages that connect and open to the combustion space;
Fuel supply means for injecting the fuel provided in each intake passage,
Each of the fuel supply means injects the fuel along a direction intersecting each other inside the combustion space,
Depending on the operating conditions of the internal combustion engine ,
The combustion mode of the internal prior Symbol combustion space, a homogeneous combustion providing a time difference in the fuel injection timing of said plurality of fuel supply means, the switching to the stratified combustion to simultaneously the fuel injection timing of said plurality of fuel supply means the internal combustion engine shall be the feature. A space in the cylinder in which the piston reciprocates, and a combustion space in which a mixture of fuel and air burns;
A first intake passage and a second intake passage which are connected to the combustion space and open;
First fuel supply means provided in the first intake passage for injecting the fuel;
Second fuel supply means provided in the second intake passage for injecting the fuel;
The first fuel supply means and the second fuel supply means inject the fuel along a direction intersecting each other inside the combustion space;
Depending on the operating conditions of the internal combustion engine ,
The interior of the combustion mode before Symbol combustion space, said first and homogeneous combustion to provide a fuel injection timing and the secondary time difference of fuel injection timing and the second fuel supply means in the fuel supply means, said first fuel supply means timing of fuel injection and the inner combustion engine you and switches to the stratified combustion to simultaneously the fuel injection timing of the second fuel supply means.   The stratified combustion is performed when operating in a region where a large amount of exhaust gas is recirculated to the combustion space,
  The homogeneous combustion is performed when the engine is not operated in a region where a large amount of exhaust gas is recirculated to the combustion space and the accelerator opening is larger than an accelerator opening threshold. 3. The internal combustion engine according to 2.   4. The fuel injection timing is retarded when the combustion mode in the combustion space is stratified combustion, compared to when the combustion mode in the combustion space is homogeneous combustion. The internal combustion engine described.

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