JP2010048109A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine in which the number of PM particles is reduced at the fuel injection by means of a fuel injection means for performing fuel injection to an inside of an intake passage. <P>SOLUTION: In the internal combustion engine 1, a fuel injection direction of a PFI injector 21 is allowed to be nearly parallel with an upper surface of an intake port 15. Besides, more than about a half of the fuel is subjected to injection to an upper region when dividing the intake port 15 into two regions of the upper and lower regions with the dividing plane passing the center of the intake valve 17. Thus, the number of the PM particles is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine provided with an intake passage injection injector that injects fuel into an intake passage.

  2. Description of the Related Art An internal combustion engine having an intake passage injector for injecting fuel into an engine intake passage and an in-cylinder injector for injecting fuel into an engine combustion chamber is known. In such an internal combustion engine, the number of PM particles can usually be significantly reduced when injected with an intake manifold injector, compared with when injected with an in-cylinder injector. When the injection amount of the injector increases, the number of PM particles resulting from the injection of the intake manifold injector may increase significantly. This is improved by performing control to limit the injection amount of the intake manifold injector, but if the injection method of PFI (Port Fuel Injection) is not appropriate, it will not be improved even if the above control is performed, or There is a problem that the number of PM particles resulting from the injection of the intake manifold injector may deteriorate from a region where the injection quantity of the intake manifold injector is small.

  Further, in Patent Document 1, for the purpose of promoting the vaporization of the fuel after warming up, the fuel is injected toward the center of the intake valve or downward, but the contact angle between the attached fuel and the airflow direction is large, and the flow velocity However, there is a problem that large particle size particles are generated and the number of PM particles increases when cold.

JP 2005-90258 A

  The present invention has been made in view of the above, and an object of the present invention is to provide an internal combustion engine capable of reducing the number of PM particles when fuel is injected by a fuel injection means for injecting fuel into an intake passage. And

  In order to solve the above-described problems and achieve the object, the present invention provides an internal combustion engine having fuel injection means for injecting fuel into an intake passage, wherein the direction of fuel injection from the fuel injection means is changed to the intake passage. It is characterized in that approximately half or more of the fuel is injected into a region in the upper surface direction when the intake passage is divided into two in the upper surface and lower surface directions in a direction substantially parallel to the upper surface.

  According to the internal combustion engine of the present invention, in the internal combustion engine provided with the fuel injection means for injecting fuel into the intake passage, the fuel injection direction from the fuel injection means is a direction substantially parallel to the upper surface of the intake passage, In addition, since approximately half or more of the fuel is injected into the region in the upper surface direction when divided into the upper surface and the lower surface direction of the intake passage, the fuel is injected by the fuel injection means for injecting the fuel into the intake passage. There is an effect that it becomes possible to provide an internal combustion engine capable of reducing the number of PM particles in the case.

  Hereinafter, an embodiment of an internal combustion engine according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

(Embodiment 1)
1 is a schematic diagram of an engine according to Embodiment 1 of the present invention, FIG. 2 is a schematic diagram for explaining an injection angle with respect to an intake port of the PFI injector of FIG. 1, and FIG. 3 is a fuel injection of the PFI injector. It is a schematic diagram for demonstrating an area | region.

  An engine 1 shown in FIG. 1 is a dual-injector type internal combustion engine, and a piston 13 that reciprocates in the vertical direction in the drawing is disposed in a cylinder 11 that constitutes a cylinder of the engine 1. It is connected to a crankshaft (not shown) via a connecting rod (not shown). A combustion chamber 14 defined by a cylinder 11 and a cylinder head 12 is formed above the piston 13, and the combustion chamber 14 communicates with an intake port 15 and an exhaust port 16 via an intake valve 17 and an exhaust valve 18. is doing. The intake port 15 is provided with a PFI injector 21 that injects fuel into the intake port 15.

  As shown in FIG. 2, the injection port of the PFI injector 21 is provided in a direction substantially parallel to the upper surface of the intake port 15, and the PFI injector 21 is in a direction substantially parallel to the upper surface of the intake port 15 and its upper surface. The region on the upper surface side when the fuel is injected so as to be in contact with the fuel and approximately half or more of the injected fuel passes through the center of the intake valve 17 and is divided into the upper surface and the lower surface of the intake port 15 as shown in FIG. A is configured to be injected into A (the wall surfaces of the intake valve 17 and the intake port 15).

  An exhaust purification catalyst (not shown) is provided in the exhaust port 16 on the exhaust valve 18 side. The cylinder head 12 is equipped with a DI (Direct Injection) injector (in-cylinder fuel injection valve) 20 that directly injects fuel into the combustion chamber 14. The DI injector 20 is positioned on the intake port 15 side and is inclined at a predetermined angle in the vertical direction. The DI injector 20 is capable of injecting fuel toward the top surface of the piston 13 so that the fuel rides on the intake air flow generated in the combustion chamber 14. Further, the cylinder head 12 is provided with a spark plug 19 that is located above the combustion chamber 14 and ignites the air-fuel mixture.

  The operations of the DI injector 20, the PFI injector 21, and the spark plug 19 are controlled by an engine control unit (hereinafter referred to as ECU) 10, which includes various sensors (crank angle sensor, accelerator opening sensor, air flow meter, not shown). Various information is input from a water temperature sensor or the like.

  Next, the behavior of the fuel injected from the PFI injector 21 of the engine 1 having the above configuration will be described. While the intake valve 17 is closed, the PFI injector 21 injects fuel so as to be in contact with the upper surface in a direction substantially parallel to the upper surface of the intake port 15, and approximately half or more of the injected fuel is injected into the intake valve 15. It injects into the area | region of the upper surface side when passing through the center of 17 and dividing into 2 in the upper surface and lower surface direction of the intake port 15. As a result, the injected fuel adheres to the upper surface of the intake port 15 and the upper side of the intake valve 17. In the intake stroke, the flow upstream of the intake port 15 is fast, and the intake air flows at a shallow angle with respect to the fuel liquid film 25b attached to the upper surface of the intake valve 17 and the upper surface of the intake port 15. Even when the fuel droplets 25a flow into the combustion chamber 14, atomization is promoted and the number of PM particles is reduced. In addition, by spraying in contact with the upper surface of the intake port 15, when it is separated from the fuel liquid film 25b by the air flow to become the fuel droplets 25a, a selective action works and a large particle size spray is not generated. Since the spray with the diameter is generated or remains as the fuel liquid film 25b, the number of PM particles decreases. In contrast, in the prior art, spray is usually injected toward the center of the intake valve or downward (region B in FIG. 3) for the purpose of promoting vaporization of the fuel after warming up. Since the contact angle between the produced fuel and the airflow direction is large and the flow velocity is slow, large particles are generated, and the number of PM particles increases when cold.

  As described above, according to the first embodiment, the fuel injection direction of the PFI injector 21 is set to a direction substantially parallel to the upper surface of the intake port 15 and passes through the center of the intake valve 17 and the upper surface of the intake port 15 and Since approximately half or more of the fuel is injected into the region on the upper surface side when divided into two in the lower surface direction, the number of PM particles can be reduced.

(Embodiment 2)
An internal combustion engine according to Embodiment 2 will be described with reference to FIGS. FIG. 4 is a schematic diagram of an engine according to Embodiment 2 of the present invention. 4, parts having the same functions as those in FIG. 1 are denoted by the same reference numerals, and description of common parts is omitted. The engine 1 according to Embodiment 2 shown in FIG. 4 is configured so that the fuel injection angle (direction) of the PFI 21 can be changed, and an injection angle changing mechanism 30 that changes the injection angle of the PFI 21, and an intake port 15 An airflow control valve 40 for controlling the direction of airflow and an intake valve temperature detecting means 50 for detecting the intake valve temperature are provided.

  The injection angle changing mechanism 30 includes a rack and pinion mechanism that includes a rack 30a and a pinion 30b. The ECU 10 controls the fuel injection angle of the PFI injector 21 by drivingly controlling the position of the rack 30a. As the rack 30a moves, the pinion 30b is driven to rotate, and the fuel injection angle of the PFI injector 21 fixed to the pinion 30b can be changed. The airflow control valve 40 is driven and controlled by the ECU 10, and its angle is changed. The intake valve temperature detection means 50 detects the intake valve temperature of the intake valve 17 and outputs it to the ECU 10.

  FIG. 5 is a flowchart for explaining the PM particle number reduction control executed by the ECU 10. In the figure, first, the ECU 10 calculates the intake valve temperature and the PFI injection amount (step S1). Next, the ECU 10 determines whether or not the intake valve temperature ≦ the threshold value Th1 (step S2). If the intake valve temperature ≦ threshold Th1 is not satisfied (“No” in step S2), the ECU 10 returns. If the intake valve temperature ≦ threshold Th1 is satisfied (“Yes” in step S2), the ECU 10 It is determined whether or not the injection amount ≧ threshold value Th2 (step S3). The ECU 10 returns when PFI injection amount ≧ threshold Th2 is not satisfied (“No” in step S3), while the ECU 10 returns PFI when PFI injection amount ≧ threshold Th2 is satisfied (“Yes” in step S3). The fuel injection angle control of the injector 21 is executed (step S4).

  Specifically, in the fuel injection angle control, the ECU 10 calculates the injection angle of the PFI injector 21 with reference to the PFI injection amount / intake valve temperature / injection angle map based on the PFI injection amount and the intake valve temperature. The injection angle changing mechanism 40 is controlled so that the injection angle of the PFI injector 21 becomes the calculated fuel injection angle.

  FIG. 6 is a diagram illustrating an example of a PFI injection amount / intake valve temperature / injection angle map. As shown in the figure, the PFI injection amount / intake valve temperature / injection angle map is a step in which a suitable injection angle calculated by experiment or simulation is between 0 ° and MAX with the PFI injection amount and the intake valve temperature as variables. Registered. Here, the injection angle = 0 ° is the base injection angle, and the injection angle = MAX is the spray angle at which the upper end of the spray and the upper surface of the intake port 15 are substantially parallel. The larger the PFI injection amount and the lower the intake valve temperature, the larger (upward) the injection angle is set.

  Next, the ECU 10 executes control of the airflow control valve 40 (step S5). Specifically, the ECU 10 calculates the angle of the airflow control valve 40 based on the PFI injection amount and the intake valve temperature with reference to the PFI injection amount / intake valve temperature / airflow control valve angle map, and the airflow control valve Control is performed so that the angle of 40 becomes the calculated angle.

  FIG. 7 is a diagram illustrating an example of a PFI injection amount / intake valve temperature / airflow control valve angle map. As shown in the figure, the PFI injection amount / intake valve temperature / airflow control valve angle map has a 0 ° angle of a suitable airflow control valve 40 calculated by experiment or simulation using the PFI injection amount and the intake valve temperature as variables. It is registered in stages between ~ MAX. Here, the angle θ = 0 ° of the airflow control valve 40 is the base airflow control valve angle, and the airflow above the intake port 15 becomes faster as the angle θ is larger. The larger the PFI injection amount and the lower the intake valve temperature, the larger the angle of the airflow control valve 40 is set (the side that accelerates the flow toward the upper side of the intake port 15).

  As described above, according to the second embodiment, the ECU 10 changes the injection angle of the PFI injector 21 via the injection angle changing mechanism 30 based on the PFI injection amount and the intake valve temperature. Therefore, it is possible to promote vaporization after warm-up.

  In addition, since the ECU 10 changes the angle of the airflow control valve 40 based on the PFI injection amount and the intake valve temperature, the fuel atomization effect can be promoted.

  As described above, the internal combustion engine according to the present invention is useful for an internal combustion engine provided with an intake manifold injector and an internal combustion engine provided with an intake manifold injector and an in-cylinder injector.

It is a schematic diagram of the engine which concerns on Embodiment 1 of this invention. It is a schematic diagram for demonstrating the injection angle with respect to the intake port of the PFI injector of FIG. It is a schematic diagram for demonstrating the fuel injection area | region of a PFI injector. It is a schematic diagram of the engine which concerns on Embodiment 2 of this invention. It is a flowchart for demonstrating PM particle number reduction control performed by ECU. It is a figure which shows an example of a PFI injection quantity and intake valve temperature / injection angle map. It is a figure which shows an example of a PFI injection amount and intake valve temperature / airflow control valve angle map.

Explanation of symbols

1 engine 10 ECU
DESCRIPTION OF SYMBOLS 15 Intake port 17 Intake valve 20 DI injector 21 PFI injector 30 Injection angle change mechanism 40 Airflow control valve 50 Intake valve temperature detection means

Claims (4)

In an internal combustion engine provided with fuel injection means for injecting fuel into the intake passage,
The direction of fuel injection from the fuel injection means is a direction substantially parallel to the upper surface of the intake passage, and approximately half or more of the fuel is in a region in the upper surface direction when divided into the upper surface and the lower surface direction of the intake passage. An internal combustion engine that performs injection. An intake valve temperature detecting means for detecting the temperature of the intake valve;
Fuel injection angle changing means for changing the fuel injection angle of the fuel injection means based on the fuel injection amount of the fuel injection means and the temperature of the intake valve detected by the intake valve temperature detection means;
The internal combustion engine according to claim 1, further comprising: An airflow control valve for controlling the airflow in the intake passage;
Airflow control valve angle changing means for changing the angle of the airflow control valve based on the fuel injection amount of the fuel injection means and the temperature of the intake valve detected by the intake valve temperature detection means;
The internal combustion engine according to claim 1, further comprising:   The internal combustion engine according to any one of claims 1 to 3, further comprising second fuel injection means for injecting fuel into the cylinder.

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