JP2013036348A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve performance without directly installing, in a cylinder, a fuel injection device for directly injecting fuel to the inside (in the cylinder) of the cylinder.SOLUTION: Fuel is independently injected from a first injector 10 and a second injector 25 for injecting fuel so that fuel will reach a suction opening during a suction stroke, promotion of vaporization of fuel and maintenance of stratification of fuel are both arbitrarily regulated compatibly, a state of fuel reaching to the suction opening at timing of opening of a suction valve 7 in the suction stroke is accurately controlled, and the performance when fuel is directly injected to the inside of a combustion chamber 6 is maintained in a range of a wide operation condition from cold time to high load operation time at medium and high speed after warming-up.

Description

  In the present invention, by accurately setting the state of fuel injection into the intake passage, performance is improved without directly providing a fuel injection device in the cylinder (inside the cylinder) directly in the cylinder. The present invention relates to an internal combustion engine.

  2. Description of the Related Art As an internal combustion engine (engine), an engine is known that includes a direct injection injector that is provided inside a cylinder (in a cylinder) and injects fuel directly into the cylinder, and a port injection injector that injects fuel into an intake passage. (For example, refer to Patent Document 1).

  In an engine equipped with a direct-injector and a port-injector, high-pressure fuel is directly injected from the direct-injector into the cylinder, so that the latent heat of vaporization of the fuel is used for cooling the intake air and the temperature of the mixture is lowered. The occurrence of knocking can be suppressed. Furthermore, since the air density can be increased by cooling the intake air, the amount of intake air at the full load can be increased to improve the performance. In addition, by injecting fuel from the port injector into the intake passage, the residence time is secured and the homogenization of the air-fuel mixture can be promoted.

  However, in an engine provided with a direct injection injector and a port injection injector, the tip of the direct injection injector mounted in the cylinder is exposed to high-temperature and high-pressure combustion gas. For this reason, even when fuel is injected from the port injector to promote homogenization of the air-fuel mixture, in order to cool the tip of the direct injection by the cooling action of the fuel injection, the fuel from the direct injection injector The current situation is that it is necessary to continue the injection, and fuel injection cannot be performed only from the port injector. In addition, part of the fuel injected from the direct injection injector burns before it is sufficiently vaporized, or collides with the combustion chamber wall and burns in a liquid film, resulting in a large amount of particulate matter discharge. was there. Further, since it is necessary to inject fuel at a high pressure from the direct injection injector, there is a possibility that the power loss of the high-pressure pump may affect the performance.

  In addition, in order to perform direct injection, a temperature-resistant and pressure-resistant injector, a high-pressure fuel pump, a dedicated injector driver, and the like are required, which causes a problem that the cost of the fuel injection system increases.

  In addition, direct injection injectors need to ensure temperature resistance and pressure resistance, and further, because the tip is exposed to combustion gas, carbonization of combustion products and fuels tends to cause deposits to accumulate depending on operating conditions, Deposit measures were required. For this reason, the internal combustion engine provided with the direct injection injector has a problem that the cost of the fuel injection system increases.

JP 2009-228447 A

  The present invention has been made in view of the above situation, and does not include a direct injection injector that directly injects fuel into the cylinder, and the fuel reaches the intake opening when the intake valve opens during the intake stroke. By accurately controlling the state of the engine, the performance when fuel is directly injected into the cylinder is maintained in a wide range of operating conditions from cold to warm and medium to high speed high load operation. An object is to provide an internal combustion engine capable of obtaining high performance.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention includes an intake opening that communicates an intake passage and a cylinder, a first injector that injects fuel into the intake passage, and injection in the intake passage. A second injector for injecting fuel into the intake passage independently of fuel injection by the first injector so that the residence time of the fuel is longer than that of the first injector; and at least in the intake stroke from the first injector The fuel is injected so that the injected fuel reaches the intake opening during the intake stroke, and the fuel is injected from the second injector so that the injected fuel reaches the intake opening during the intake stroke. And a fuel injection control means.

  In the present invention according to claim 1, from the first injector in which the fuel is injected so that the fuel reaches the intake opening during the intake stroke, and the second injector in which the residence time of the injected fuel is longer than that of the first injector By independently injecting the fuel, fuel vaporization and maintaining fuel stratification can be adjusted at will, and fuel can reach the intake opening when the intake valve opens during the intake stroke. Maintaining the performance when fuel is injected directly into the cylinder in a wide range of operating conditions from cold to warm and medium / high speed high load operation by controlling the state of the engine accurately and high It becomes possible to obtain performance.

  The first injector is preferably supplied with fuel for stratified combustion at least in the intake stroke and in a cold state such as at the start. Further, in the middle / high speed, high load state, it is preferable to supply all or most of the required fuel amount. The second injector preferably injects fuel during the exhaust stroke, promotes vaporization of the fuel in a cold state such as at the time of start-up, and cannot be supplied from the first injector in a medium or high speed, high load state. It is preferable to supply fresh fuel.

  An internal combustion engine according to a second aspect of the present invention is the internal combustion engine according to the first aspect, further comprising operating state determining means for determining an operating state of the engine, wherein the fuel injection control means is the operating state determining means. In accordance with this determination, fuel injection from the first injector and fuel injection from the second injector are controlled.

  In the present invention according to claim 2, the fuel is injected from the second injector in which the fuel is injected so that the fuel reaches the intake opening during the intake stroke according to the operating state of the engine determined by the operating state determining means. In addition, fuel can be injected from the first injector.

  The internal combustion engine of the present invention according to claim 3 is the internal combustion engine according to claim 1 or 2, wherein the fuel injection control means injects fuel from the second injector in a stroke before an intake stroke. It is characterized by that.

  In the present invention according to claim 2, fuel can be injected from the second injector in an exhaust stroke that is a stroke before the intake stroke. If the fuel can be injected so that the fuel reaches the intake opening during the intake stroke, the fuel can be injected from the second injector in a stroke before the exhaust stroke depending on the state of the intake port.

  An internal combustion engine according to a fourth aspect of the present invention is the internal combustion engine according to any one of the first to third aspects, wherein opening and closing timings of the intake valve and the exhaust valve of the engine are changed, A valve opening / closing timing changing unit that forms a valve overlap period in which the intake valve is opened before the valve is closed, and the fuel injection control unit is configured to output the valve overlap period formed by the valve opening / closing timing changing unit. Thereafter, fuel is injected from the first injector and the second injector so that the fuel from the first injector and the second injector reaches the intake opening.

  In the present invention according to claim 4, since the fuel is injected so that the fuel from the first injector and the second injector reaches the intake opening after the valve overlap period, that is, after the exhaust valve is closed. The fuel can be prevented from being blown into the exhaust passage.

  The internal combustion engine of the present invention according to claim 5 is the internal combustion engine according to any one of claims 1 to 4, wherein the fuel injection control means is started by the operating state determination means. The fuel is injected from the first injector and the second injector when it is determined that the engine is in a warm-up operation state or a medium-high speed / high-load operation state.

  In the present invention according to claim 5, when it is determined that there is a possibility that the fuel cannot be sufficiently vaporized in a cold state or the like, the second injector in which the fuel is injected so that the fuel reaches the intake opening during the intake stroke Injecting the fuel from the first injector and injecting the fuel from the first injector promotes the vaporization of the fuel until the fuel injected from the second injector reaches the intake opening, and is sent to the inside of the cylinder. Stratified combustion of the fuel injected from the injector is ensured. Thereby, increase of unburned HC and PM (particulate matter) can be suppressed while maintaining the stability of combustion, and occurrence of dilution of engine oil can be suppressed.

  Further, for example, by injecting fuel from the first injector after the fuel injected from the second injector reaches the intake opening, it is possible to form a mixture having a light and shade as in the case of direct injection. As a result, carbon monoxide is largely generated due to incomplete combustion in the dark portion, but oxygen remains in the light portion, so that the carbon monoxide and oxygen discharged to the exhaust pipe cause an oxidation reaction in the exhaust purification catalyst and generate heat. For this reason, an early temperature rise effect of the catalyst can be obtained.

  According to the fifth aspect of the present invention, when it is determined that the vehicle is operating at a medium or high speed and high load, the fuel is injected from the second injector into which fuel is injected so that the fuel reaches the intake opening during the intake stroke. In addition to injecting fuel from the first injector, it is possible to inject fuel corresponding to an operation state that requires a large amount of fuel in a single stroke. This eliminates the possibility of fuel carryover to the next stroke, suppresses fuel blow-through and eliminates unburned HC, and promotes fuel vaporization to suppress PM (particulate matter) increase. Can do.

  The internal combustion engine of the present invention according to claim 6 is the internal combustion engine according to claim 5, wherein the fuel injection control means determines that the engine is in a start / warm operation state by the operation state determination means. In this case, the fuel injection amount of the second injector is increased compared to the fuel injection amount of the first injector, and if it is determined that the engine is in a medium / high speed / high load operation state, the second injector Fuel is injected from the first injector and the second injector so that the fuel injection amount of the first injector is larger than the fuel injection amount.

  In the present invention according to claim 6, in a cold state such as at the time of start-up, a large amount of fuel whose vaporization is promoted by increasing the fuel injection amount of the second injector is supplied. A large amount of fuel is supplied into the cylinder by increasing the fuel injection amount of one injector.

  The internal combustion engine of the present invention according to claim 7 is the internal combustion engine according to claim 5 or 6, wherein the fuel injection control means is in the start / warm operation state by the operation state determination means. Is determined, the injection timing is set so that the fuel injected from the second injector reaches the intake opening and then the fuel is injected from the first injector, and the engine is in the middle high speed / high load operation state. Is determined so that the time when the fuel injected by the second injector reaches the intake opening and the time when the fuel injected by the first injector reaches the intake opening are substantially the same. An injection timing is set.

  In the present invention according to claim 7, in the start-up / warm-up operation state, the fuel injected by the second injector reaches the intake opening, and then the fuel injected by the first injector reaches the intake opening. The fuel injected by the second injector and accelerated in vaporization can be pushed into the cylinder by the fuel injected by the first injector, and the fuel injected by the first injector is collected around the spark plug to stabilize the combustion. In addition, an early temperature rise effect can be obtained by forming a mixture of light and light and supplying carbon monoxide and oxygen to the catalyst after combustion.

  Also, when the medium / high speed high load state, the time when the fuel injected by the second injector reaches the intake opening and the time when the fuel injected by the first injector reaches the intake opening are substantially the same. It is possible to minimize the blow-through of fuel into the exhaust passage.

  An internal combustion engine according to an eighth aspect of the present invention is the internal combustion engine according to any one of the first to seventh aspects, wherein the second injector is provided in an intake passage upstream of the first injector. It is arranged.

  In the present invention according to claim 8, since the second injector is arranged in the intake passage upstream of the first injector, the residence time of the fuel injected from the second injector in the intake passage is secured, and the fuel is vaporized. It can be promoted sufficiently.

  It is also possible to arrange the first injector and the second injector at the same position in the intake passage in the flow direction and direct the injection port of the second injector toward the upstream side of the intake passage. In this case, the fuel is injected from the second injector to the upstream side of the intake passage and is sent to the intake opening side by the intake air flow, so that the residence time of the fuel in the intake passage is secured.

  The internal combustion engine of the present invention accurately controls the state of fuel arrival at the intake opening when the intake valve opens during the intake stroke without providing the cylinder with a direct injection injector that directly injects fuel into the cylinder. As a result, it is possible to maintain the performance when fuel is directly injected into the cylinder and obtain high performance in a wide range of operating conditions from cold to warm and medium / high speed high load operation. It becomes possible.

1 is a schematic configuration diagram of an internal combustion engine according to an embodiment of the present invention. It is a principal part block diagram in FIG. It is a schematic block diagram of fuel injection control. It is a control flowchart of fuel injection. It is stroke explanatory drawing explaining a fuel-injection time. It is stroke explanatory drawing explaining a fuel-injection time.

  The internal combustion engine of the present invention will be described with reference to FIGS.

  FIG. 1 shows an overall schematic configuration of an internal combustion engine according to an embodiment of the present invention, FIG. 2 (a) shows a configuration of a side surface around an intake port, and FIG. 2 (b) shows a plan view around an intake port. The configuration is shown.

  As shown in FIG. 1, a spark plug 3 is attached to a cylinder head 2 of an engine body (hereinafter referred to as an engine) 1 that is an internal combustion engine (engine) for each cylinder, and a high voltage is output to the spark plug 3. An ignition coil 4 is connected. In the cylinder head 2, an intake port 5 (intake passage) is formed for each cylinder, and an intake valve 7 is provided in each intake port 5 at an intake opening on the combustion chamber 6 side. The intake valve 7 is opened and closed in accordance with a cam of a camshaft (not shown) that rotates in accordance with the engine rotation, so that the intake ports 5 and the combustion chambers 6 are communicated and blocked.

  One end of an intake manifold 9 is connected to each intake port 5, and the intake manifold 9 communicates with each intake port 5. An electromagnetic first fuel injection valve (first injector) 10 is attached to the intake manifold 9 (or cylinder head 2), and fuel is supplied from the fuel tank to the first injector 10 via a fuel pipe.

  An electromagnetic second fuel injection valve (second injector) 25 is attached to the upstream side of the first injector 10 of the intake manifold 9 (or the cylinder head 2), and is connected from the fuel tank to the second injector 25 via a fuel pipe. Fuel is supplied. The first injector 10 and the second injector 25 independently inject fuel into the intake port 5.

  An exhaust port 11 is formed for each cylinder in the cylinder head 2, and an exhaust valve 12 is provided on the combustion chamber 6 side of each exhaust port 11. The exhaust valve 12 is opened and closed in accordance with a cam of a camshaft (not shown) that rotates in accordance with the engine rotation, so that the exhaust ports 11 and the combustion chamber 6 are communicated / blocked. One end of an exhaust manifold 13 is connected to each exhaust port 11, and the exhaust manifold 13 communicates with each exhaust port 11.

  In addition, since such an engine is a well-known thing, it abbreviate | omitted about the detail of the structure.

  An intake pipe 14 is connected to the intake manifold 9 on the upstream side of the first injector 10 and the second injector 25, and an electromagnetic throttle valve 15 is attached to the intake pipe 14 to detect the valve opening degree of the throttle valve 15. A throttle position sensor 16 is provided. The depression state of the accelerator pedal 61 is detected by the accelerator position sensor 62, and the throttle valve 15 is operated based on the detection information of the accelerator position sensor 62. Further, the accelerator position sensor 62 detects the release of the accelerator pedal 61 (deceleration / downhill traveling).

  An air flow sensor 17 that measures the amount of intake air is provided upstream of the throttle valve 15. As the air flow sensor 17, a Karman vortex type or hot film type air flow sensor is used. A surge tank 18 is provided in the intake pipe 14 between the intake manifold 9 and the throttle valve 15.

  An exhaust pipe 20 is connected to the other end of the exhaust manifold 13, and an exhaust gas circulation port (EGR port) 21 is branched to the exhaust manifold 13. One end of an EGR pipe 22 is connected to the EGR port 21, and the other end of the EGR pipe 22 is connected to the intake pipe 14 upstream of the surge tank 18. An EGR valve 23 is provided in the EGR pipe 22 close to the surge tank 18, and a part of the exhaust gas is introduced into the intake pipe 14 upstream of the surge tank 18 through the EGR pipe 22 by opening the EGR valve 23. Is done.

  The EGR device recirculates a part of the exhaust gas to the intake system (surge tank 18) of the engine 1, lowers the combustion temperature in the combustion chamber 6 of the engine 1, and reduces the emission amount of nitrogen oxides (NOx). When the EGR valve 23 is opened and closed, a part of the exhaust gas is recirculated to the intake system as EGR gas at a predetermined EGR rate according to the opening degree.

  By returning the exhaust gas to the intake system of the engine 1 by the EGR device, the amount of air regulated by the throttle valve 15 can be reduced, that is, a large amount of air does not flow even when the throttle valve 15 is opened. The throttle loss of the throttle valve 15 can be reduced. Further, even in the low speed and low rotation range, the intake air flowing into the combustion chamber can be disturbed.

  The intake pipe 14 upstream of the surge tank 18 is provided with a supercharger 51. The supercharger 51 causes the exhaust gas of the engine 1 to rotate an exhaust turbine 51a provided in the exhaust manifold 13 to the exhaust turbine 51a. By the operation of the directly connected intake compressor 51b, the intake air is pressurized and the volume density is increased, and the intake air whose pressure is increased and the volume density is increased is sent to the combustion chamber 6 (supercharged).

An exhaust purification catalyst (for example, a three-way catalyst) 55 is interposed in the exhaust pipe 20 connected to the exhaust manifold 13, and exhaust gas is purified by the exhaust purification catalyst 55. For example, the exhaust purification catalyst 55 purifies hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), etc. in the exhaust gas when the exhaust air-fuel ratio is near the stoichiometric air-fuel ratio (stoichiometric). Further, when the exhaust air / fuel ratio becomes an oxidizing atmosphere (lean air / fuel ratio), HC and CO are oxidized and purified, and oxygen (O ₂ ) is added until the exhaust air / fuel ratio becomes a reducing atmosphere (rich air / fuel ratio). When the air-fuel ratio is stored and becomes a rich air-fuel ratio, NOx is reduced and purified, and the stored O ₂ is released, and HC and CO are oxidized and purified.

  The engine 1 is provided with a variable valve mechanism 63 that arbitrarily changes the lift amount and lift timing (valve operating state) of the intake valve 7 and the exhaust valve 12, and the cam phase is changed by the variable valve mechanism 63. For example, the operation states of the intake valve 7 and the exhaust valve 12 are arbitrarily set. Further, the engine 1 is provided with a crank angle sensor 32 that detects a crank angle and obtains an engine rotation speed (Ne), and a water temperature sensor 33 that detects a cooling water temperature.

  The ECU (electronic control unit) 31 includes an input / output device, a storage device (ROM, RAM, etc.), a central processing unit (CPU), a timer counter, and the like. The ECU 31 performs comprehensive control of the engine 1.

  Various sensors such as the throttle position sensor 16, the air flow sensor 17, the crank angle sensor 32, the water temperature sensor 33, and the accelerator position sensor 62 described above are connected to the input side of the ECU 31, and detection information from these sensors is input. The Further, information on the variable valve mechanism 63 is input to the ECU 31, and information on the lift amount and lift timing of the intake valve 7 and the exhaust valve 12 is sent.

  On the other hand, the output side of the ECU 31 is connected with various output devices such as the ignition coil 4, the throttle valve 15, the first injector 10, the drive device of the second injector 25, the EGR valve 23, and the variable valve mechanism 63. Yes. These various output devices include a fuel injection amount calculated by the ECU 31 based on detection information from various sensors, a fuel injection period, a fuel injection timing, an ignition timing, an operation timing / operation amount of the EGR valve 23, an intake valve 7 and The operating state (valve operating state) of the exhaust valve 12 and the like are output.

  Based on detection information from various sensors, the air-fuel ratio is set to an appropriate target air-fuel ratio, an amount of fuel corresponding to the target air-fuel ratio is injected from the injector 10 at an appropriate timing, and the throttle valve 15 is opened appropriately. The spark ignition is performed at an appropriate timing by the spark plug 3.

  The engine 1 of the present embodiment includes a first injector 10 in the intake passage, and a second injector 25 on the upstream side of the first injector 10, that is, so that the fuel injection path is longer than the first injector 10. The fuel is injected from the first injector 10 and the second injector 25 (fuel injection control means). That is, the fuel injected from the first injector 10 at least in the intake stroke, injected from the second injector 25 in the exhaust stroke before the intake stroke, and injected at the timing when the intake valve 7 is opened. Is controlled to reach the vicinity of the intake valve 7 (intake opening).

  That is, the first injector 10 in which the fuel is injected with good controllability and the residence time in the intake passage are secured so that the fuel reaches the intake opening during the intake stroke, and vaporization of the fuel is sufficiently promoted. The fuel can be injected independently from the second injector 25 into which the fuel is injected.

  As a result, it is possible to arbitrarily adjust both the promotion of fuel vaporization and the maintenance of fuel stratification, and accurately control the state of fuel arrival at the intake opening when the intake valve 7 opens during the intake stroke. And maintaining the performance when fuel is injected directly into the combustion chamber 6 in a wide range of operating conditions from cold to warm and medium to high speed high load operation, to obtain high performance Is possible.

  By injecting fuel from the first injector 10 and the second injector 25 so that the injected fuel reaches the vicinity (intake opening) of the intake valve 7 when the intake valve 7 is open, the intake port The fuel can be supplied while suppressing the adhesion of the fuel to the umbrella part of the intake valve 7 or the intake valve 7, and the vaporization latent heat of the fuel can be used for cooling the intake air.

  For this reason, the temperature of the air-fuel mixture is lowered to suppress the occurrence of knocking, and the air density is increased to increase the amount of intake air at full load, thereby maximizing the effect of intake air cooling even for port injection. be able to.

  The engine 1 according to this embodiment includes an operation state determination unit that determines an operation state, and injects fuel from the first injector 10 according to the determination of the operation state determination unit (according to the operation state of the engine 1). And the injection of the fuel from the 2nd injector 25 is controlled.

  Specific control of fuel injection will be described with reference to FIGS.

  3 is a schematic configuration of a control block for fuel injection control, FIG. 4 is a control flowchart for fuel injection, FIG. 5 is a description of the stroke of fuel injection timing during start-up / warm-up operation, and FIG. The stroke explanation of the fuel injection timing is shown.

  As shown in FIG. 3, the ECU 31 has an engine speed (Ne) based on detection information from the crank angle sensor 32, detection information from the airflow sensor 17, detection information from the accelerator position sensor 62, detection information from the throttle position sensor 16, Phase lift information (valve phase, valve lift) and vehicle speed information based on information from the variable valve mechanism 63 are input.

  The ECU 31 is provided with an operation state determination unit 71 that determines the operation state of the engine 1. The operation state determination unit 71 is, for example, in a start (cranking) state or a warm-up operation state according to various input information. Or whether the vehicle is in a medium / high speed, high-load operation state. Information on the operation state determined by the operation state determination means 71 is sent to the injection state setting means 72. In the injection state setting means 72, the fuel injection amount and fuel injection timing of the first injector 10 and the second injector 25 are set according to the operating state. The fuel injection amount and fuel injection timing set by the injection state setting means 72 are sent to the first injector injection means 73 and the second injector injection means 74.

  The first injector injection means 73 outputs a fuel injection instruction to the first injector 10 so that the fuel injection amount set by the injection state setting means 72 is injected at least in the intake stroke. The second injector injection means 74 outputs a fuel injection instruction to the second injector 25 so that the fuel injection amount set by the injection state setting means 72 is injected in the exhaust stroke before the intake stroke. The

  A specific processing situation will be described.

  As shown in FIG. 4, when the process starts, the operating state is read in step S1, and the fuel injection amount and fuel injection timing are determined in step S2. In step S3, it is determined whether the engine is in the starting operation (cranking is in progress). If it is determined that the engine is not in the starting operation, it is determined in step S4 whether the operation is a warm-up operation.

  If it is determined in step S3 that the engine is in the starting operation, or if it is determined in step S4 that it is in the warming-up operation, that is, if it is determined that the engine 1 is in the starting / warming-up operation state, the engine is started in step S5. -Fuel injection for warm-up operation is executed.

  If it is determined in step S4 that it is not a warm-up operation, it is determined in step S6 whether the vehicle is in a medium (high) speed / high load operation (medium / high speed / high load operation). If it is determined in step S6 that the operation is medium (high) speed / high load operation, fuel injection for high load operation is executed in step S7.

  If it is determined in step S6 that the operation is not middle (high) speed / high load operation, normal operation fuel injection is executed in step S8. In normal operation fuel injection, a predetermined amount of fuel is injected from the first injector 10 at a time including at least the intake stroke.

  Based on FIG. 5, fuel injection for start-up / warm-up operation will be described.

  In start-up / warm-up operation, it is considered that the fuel cannot be sufficiently vaporized in the cold state or the like, so that the fuel reaches the intake opening during the intake stroke (shown by the solid line in FIG. 5). Fuel is injected from the second injector 25 into which fuel is injected (shown by the dotted line in FIG. 5), and fuel is injected from the first injector 10 in the intake stroke (shown by the dotted line in FIG. 5).

  The fuel injection amount (width in the left-right direction in FIG. 5) is set such that the amount of fuel injected from the second injector 25 is larger than the amount of fuel injected from the first injector 10. The injection timing is set so that the fuel injected from the second injector 25 reaches the intake opening and then injected from the first injector 10 (shown by the dotted line in FIG. 5).

  Thereby, the arrival time of the fuel at the intake opening is set so that the fuel injected from the second injector 25 reaches the intake opening after all of the fuel injected from the second injector 25 reaches the intake opening. Is done. The fuel injected from the second injector 25 is set to reach the intake opening after the valve overlap period.

  In the fuel injection in the start-up / warm-up operation, the fuel injected from the second injector 25 is promoted to be vaporized by the time it reaches the intake opening, sent to the inside of the combustion chamber 6, and injected from the first injector 10. The stratified combustion of fuel is ensured. Thereby, increase of unburned HC and PM (particulate matter) can be suppressed while maintaining the stability of combustion, and occurrence of dilution of engine oil can be suppressed.

  In addition, the fuel injected from the first injector 10 after the fuel injected from the second injector 25 has reached the intake opening allows the sufficiently vaporized fuel to be converted into the combustion chamber 6 with the fuel injected from the first injector 10. The fuel injected by the first injector 10 can be collected around the spark plug to stabilize the combustion, and the combustion can be stabilized when the ignition timing is retarded. By forming carbon dioxide and supplying carbon monoxide and oxygen to the catalyst after combustion, an early temperature rise effect can be obtained.

  Based on FIG. 6, fuel injection for medium (high) speed / high load operation will be described.

  In medium (high) speed / high load operation, fuel corresponding to operating conditions that require a lot of fuel is injected in a single stroke, so that the fuel reaches the intake opening during the intake stroke. Fuel is injected from the second injector 25 (shown by a solid line in FIG. 6), and fuel is injected from the first injector 10 from the exhaust stroke to the intake stroke (shown by a solid line in FIG. 6).

  The fuel injection amount (width in the left-right direction in FIG. 6) is set such that the amount of fuel injected from the first injector 10 is larger than the amount of fuel injected from the second injector 25. The injection timing is set so that the timing at which the fuel injected by the second injector 25 reaches the intake opening and the timing at which the fuel injected by the first injector 10 reaches the intake opening are substantially the same ( (Indicated by a dotted line in FIG. 6). The fuel injected from the first injector 10 and the fuel injected from the second injector 25 are set to reach the intake opening after the valve overlap period (shown by the dotted line in FIG. 6). is there).

  As a result, a large amount of fuel can be injected in a single stroke (during the intake stroke), there is no risk of carry over of fuel to the next stroke, and fuel blowout into the exhaust passage is minimized. Thus, it is possible to suppress the blow-through of the fuel, eliminate the increase in unburned HC, and suppress the increase in PM (particulate matter).

  In the embodiment described above, the timing for injecting fuel from the second injector 25 is set to the exhaust stroke that is the stroke before the intake stroke, but the expansion stroke that is the stroke before the exhaust stroke is determined depending on the state of the intake path. It is also possible to inject fuel.

  In addition, the example in which the second injector 25 is arranged upstream of the first injector 10 has been described, but the first injector 10 and the second injector 25 are arranged at the same position in the intake passage in the flow direction, and the second injector 25 is arranged. It is also possible to direct the injection port to the upstream side of the intake passage. In this case, the fuel is injected from the second injector 25 to the upstream side of the intake passage and is sent to the intake opening side by the intake air flow, so that the residence time of the fuel in the intake passage is secured.

  Therefore, the engine 1 described above does not have a direct injection injector that directly injects fuel into the combustion chamber 6 inside the cylinder, and the fuel reaches the intake opening when the intake valve 7 opens during the intake stroke. By accurately controlling this, the performance when fuel is directly injected into the combustion chamber 6 is maintained in a wide range of operating conditions from the cold state to the middle / high speed high load operation after warming, High performance can be obtained.

  In the present invention, by accurately setting the state of fuel injection into the intake passage, performance is improved without directly providing a fuel injection device in the cylinder (inside the cylinder) directly in the cylinder. It can be used in the industrial field of internal combustion engines.

1 Engine body (Engine)
2 Cylinder Head 3 Spark Plug 4 Ignition Coil 5 Intake Port 6 Combustion Chamber 7 Intake Valve 9 Intake Manifold 10 First Fuel Injection Valve (First Injector)
DESCRIPTION OF SYMBOLS 11 Exhaust port 12 Exhaust valve 13 Exhaust manifold 14 Intake pipe 15 Throttle valve 16 Throttle position sensor 17 Air flow sensor 18 Surge tank 20 Exhaust pipe 21 Exhaust gas circulation port (EGR port)
22 EGR pipe 25 Second fuel injection valve (second injector)
31 ECU
32 Crank angle sensor 33 Water temperature sensor 51 Supercharger 55 Exhaust purification catalyst 61 Accelerator pedal 62 Accelerator position sensor 63 Variable valve mechanism 71 Operating state determination means 72 Injection state setting means 73 First injector injection means 74 Second injector injection means

Claims (8)

An intake opening communicating the intake passage and the cylinder;
A first injector for injecting fuel into the intake passage;
A second injector for injecting fuel into the intake passage independently of fuel injection by the first injector so that the residence time of the injected fuel in the intake passage is longer than that of the first injector;
At least in the intake stroke, fuel is injected from the first injector so that the injected fuel reaches the intake opening during the intake stroke, and the injected fuel reaches the intake opening during the intake stroke. An internal combustion engine comprising: fuel injection control means for injecting fuel from the second injector. The internal combustion engine according to claim 1,
Provided with an operating state determining means for determining the operating state of the engine;
The fuel injection control means includes
An internal combustion engine that controls injection of fuel from the first injector and injection of fuel from the second injector according to the determination of the operating state determination means. The internal combustion engine according to claim 1 or 2,
The fuel injection control means includes
An internal combustion engine, wherein fuel is injected from the second injector in a stroke before an intake stroke. The internal combustion engine according to any one of claims 1 to 3,
Valve opening / closing timing changing means for forming a valve overlap period in which the intake valve is opened before the exhaust valve is closed, and the opening / closing timing of the intake valve and the exhaust valve of the engine is changed;
The fuel injection control means includes
From the first injector and the second injector, the fuel from the first injector and the second injector reaches the intake opening after the valve overlap period formed by the valve opening / closing timing changing means. An internal combustion engine characterized by injecting fuel. The internal combustion engine according to any one of claims 1 to 4,
The fuel injection control means includes
Fuel is injected from the first injector and the second injector when the operation state determination means determines that the engine is in a start / warm-up operation state or a medium / high speed / high load operation state. An internal combustion engine. The internal combustion engine according to claim 5,
The fuel injection control means includes
When the operation state determination means determines that the engine is in a start / warm operation state, the fuel injection amount of the second injector is increased compared to the fuel injection amount of the first injector, and the engine When it is determined that the high-speed / high-load operation state is established, the fuel from the first injector and the second injector is increased so that the fuel injection amount of the first injector is larger than the fuel injection amount of the second injector. An internal combustion engine characterized by injecting fuel. The internal combustion engine according to claim 5 or 6,
The fuel injection control means includes
When the operation state determination means determines that the engine is in a start / warm-up operation state, the fuel injected from the second injector is injected from the first injector after reaching the intake opening. And when it is determined that the engine is in a medium / high speed / high load operation state, the time when the fuel injected by the second injector reaches the intake opening, and the injection by the first injector An internal combustion engine characterized in that the injection timing is set so that the timing at which the injected fuel reaches the intake opening is substantially the same. The internal combustion engine according to any one of claims 1 to 7,
The internal combustion engine, wherein the second injector is disposed in an intake passage upstream of the first injector.