JP2010024971A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve exhaust emission control efficiency by restricting adhesion of fuel to an intake port in an internal combustion engine. <P>SOLUTION: The internal combustion engine includes: an intake port 19 having branch passages 19a and 19b, being divided into two relative to a combustion chamber 18; an intake valve 21 for opening/closing the branch passages 19a and 19b; and two injectors 43a and 43b capable of injecting fuel to each of the branch passages 19a and 19b. A first injection hole 61 is provided in a central part of a tip of each of the injectors 43a and 43b, and a second injection hole 62 smaller than the first injection hole 61 is provided near the periphery of the first injection hole 61. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine that allows fuel to be injected into an intake port and introduced into the combustion chamber when communicating with the combustion chamber, and more particularly to a structure of a fuel injection valve.

  2. Description of the Related Art A port injection type spark ignition internal combustion engine that injects fuel into an intake port has been conventionally known. In this port injection type spark ignition internal combustion engine, the downstream end portion of the intake port branches into two branch passages, each branch passage communicates with the combustion chamber, and an intake valve is provided in each branch passage. A fuel injection valve capable of injecting fuel is provided. Therefore, when the intake valve is opened, fuel is injected from the fuel injection valve into each branch passage in the intake port, air-fuel mixture is sucked into the combustion chamber, and sparks from the spark plug ignite this mixture. After explosion and obtaining engine torque, combustion gas is discharged from the exhaust port to the exhaust system when the exhaust valve is opened.

  An example of such an internal combustion engine is described in Patent Document 1 below. In the internal combustion engine described in Patent Document 1, the downstream portion of the intake port is branched into two intake ports, and a fuel injection valve is attached to the upstream side of the branch portion, and the fuel injection valve has a fuel spray on the outer peripheral side. A spray with a particle size smaller than the spray particle size near the center is formed, and a fuel spray with a relatively large particle size is applied to the back of the umbrella of each intake valve, and a fuel spray with a relatively small particle size is applied to each intake air. It hits the inner wall of the port.

JP 2005-023875 A

  In the above-described conventional internal combustion engine, one fuel injection valve is provided in the intake port, and the fuel spray from the fuel injection valve is positioned near the center and the fuel spray having a large particle diameter and the outer peripheral side. It is composed of a fuel spray with a small particle size, a fuel spray with a large particle size is injected toward the back of the umbrella of each intake valve, and a fuel spray with a small particle size is injected toward the inner wall of each intake port .

  In this case, since the fuel injection valve needs to inject the fuel spray having a small particle diameter located on the outer peripheral side toward the inner wall of each intake port branched into two, the fuel spray injection angle is relatively large. Become. Increasing the fuel spray injection angle requires the nozzle hole to be inclined toward the outer peripheral side, which makes it difficult to design the nozzle hole.

  Further, since the fuel spray having a large particle size on the center side is injected toward the back of the umbrella of each intake valve, the fuel spray tends to adhere to the partition between the intake ports branched into two. As a result, the fuel is supplied in a liquid state to the combustion chamber, and combustion in the combustion chamber becomes insufficient, or the air-fuel ratio varies, and exhaust purification efficiency decreases.

  An object of the present invention is to solve such a problem, and an object of the invention is to provide an internal combustion engine that suppresses fuel adhesion to an intake port and improves exhaust purification efficiency.

  In order to solve the above-described problems and achieve the object, an internal combustion engine of the present invention opens and closes a combustion chamber, an intake port having a plurality of branch passages communicating with the combustion chamber, and each branch passage of the intake port. In the internal combustion engine comprising a plurality of possible intake valves and a plurality of fuel injection valves capable of injecting fuel into each branch passage of the intake port, each of the fuel injection valves is provided in the center of the tip portion. It has an injection hole and a 2nd injection hole provided in the outer periphery of the said 1st injection hole in a front-end | tip part, and an internal diameter smaller than this 1st injection hole.

  In the internal combustion engine of the present invention, the spray particle diameter injected from the second nozzle hole is set smaller than the spray particle diameter injected from the first nozzle hole.

  In the internal combustion engine of the present invention, the second nozzle hole is provided in a plurality of ring shapes around the outer periphery of the first nozzle hole.

  The internal combustion engine of the present invention is characterized in that a plurality of the first nozzle holes and the second nozzle holes are provided, and the number of the second nozzle holes is larger than that of the first nozzle holes.

  In the internal combustion engine of the present invention, the first injection hole is directed to a connecting portion between a shaft portion and an umbrella portion in the intake valve.

  In the internal combustion engine of the present invention, the fuel injection valve is capable of injecting fuel when the branch passage is opened by the intake valve.

  According to the internal combustion engine of the present invention, a plurality of fuel injection valves capable of injecting fuel are provided in each branch passage in the intake port, each of the fuel injection valves has a first injection hole located at the center of the tip portion, and a tip end. A second nozzle hole having an inner diameter smaller than that of the first nozzle hole is provided in the outer periphery of the first nozzle hole. Accordingly, each fuel injection valve injects fuel spray having a large particle size at the center and a small particle size at the outside toward each branch passage. Efficiency can be improved.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a horizontal sectional view of an intake port representing fuel spray from an injector in the internal combustion engine of the present embodiment, and FIG. FIG. 4 is a schematic diagram showing a tip portion of an injector in the internal combustion engine of the present embodiment, and FIG. 5 is a schematic configuration diagram showing an overall configuration of the internal combustion engine of the present embodiment.

  In the internal combustion engine of the present embodiment, as shown in FIG. 5, a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are respectively movable up and down in a plurality of cylinder bores 13 formed in the cylinder block 11. It is mated. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 14, and the combustion chamber 18 has a high central portion at the upper portion (lower surface of the cylinder head 12). It has a pent roof shape that is slanted. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 19 and the exhaust valve 20 are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction (upward in FIG. 1) for closing the intake port 19 and the exhaust port 20. ing. An intake cam shaft 23 and an exhaust cam shaft 24 are rotatably supported on the cylinder head 12, and the intake cam and the exhaust cam are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, the crankshaft sprocket fixed to the crankshaft 16 and the camshaft sprockets respectively fixed to the intake camshaft 23 and the exhaust camshaft 24 are wound with endless timing chains. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam and the exhaust cam move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. The exhaust port 20 can be opened and closed to allow the intake port 19 and the combustion chamber 18 to communicate with the combustion chamber 18 and the exhaust port 20. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine performs four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 rotate once. Will be.

  The valve mechanism of the engine is a variable intake valve timing mechanism (VVT: Variable Valve Timing-intelligent) 25 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. The intake variable valve mechanism 25 is configured by providing a VVT controller 26 at the shaft end of the intake camshaft 23, and the hydraulic pressure from the oil control valve 27 is supplied to an advance chamber and a retard chamber (not shown) of the VVT controller 26. By acting on this, the phase of the intake camshaft 23 with respect to the cam sprocket can be changed, and the opening / closing timing of the intake valve 21 can be advanced or retarded. In this case, the intake variable valve mechanism 25 advances or retards the opening / closing timing while keeping the operating angle (opening period) of the intake valve 21 constant. The intake camshaft 23 is provided with a cam position sensor 28 for detecting the rotational phase.

  A surge tank 30 is connected to the intake port 19 via an intake manifold 29, and an intake pipe 31 is connected to the surge tank 30. An air cleaner 32 is attached to an air intake port of the intake pipe 31. . An electronic throttle device 34 having a throttle valve 33 is provided on the downstream side of the air cleaner 32.

  An exhaust pipe 36 is connected to the exhaust port 20 via an exhaust manifold 35, and the exhaust pipe 36 has a three-way catalyst 37 for purifying harmful substances contained in the exhaust gas and a NOx occlusion reduction type catalyst 38. Is installed. This three-way catalyst 37 simultaneously purifies HC, CO, and NOx contained in the exhaust gas by an oxidation-reduction reaction when the air-fuel ratio (exhaust air-fuel ratio) is stoichiometric. The NOx occlusion reduction type catalyst 38 is in a rich combustion region or stoichiometric combustion region where the NOx contained in the exhaust gas is temporarily stored when the air-fuel ratio (exhaust air-fuel ratio) is lean, and the oxygen concentration in the exhaust gas is reduced. Sometimes, the stored NOx is released and NOx is reduced by the added fuel as a reducing agent.

  An exhaust gas recirculation passage (EGR passage) 39 is provided between the downstream side of the surge tank 30 in the intake pipe 31 and the upstream side of the three-way catalyst 37 in the exhaust pipe 36. Are provided with an EGR valve 40 and an EGR cooler 41. Further, an EGR gas temperature sensor 42 for detecting the temperature of the EGR gas is provided on the EGR passage 39 closer to the intake pipe 31 than the EGR valve 40.

  An injector (fuel injection valve) 43 that injects fuel into the intake port 19 is attached to the cylinder head 12, and this injector 43 is attached to the cylinder head 12 and is inclined at a predetermined angle downward from the horizontal upper end. Has been. The injectors 43 attached to the respective cylinders are connected to a delivery pipe (not shown), and a fuel supply system is connected to the delivery pipe via a fuel supply pipe. In addition, the cylinder head 12 is provided with a spark plug 44 that is positioned above the combustion chamber 18, specifically, on the uppermost wall portion of the ceiling of the combustion chamber 18 to ignite the air-fuel mixture.

  An electronic control unit (ECU) 51 is mounted on the vehicle. The ECU 51 can control the fuel injection timing of the injector 43, the ignition timing of the spark plug 44, and the like. The fuel injection amount, injection timing, ignition timing, and the like are determined based on engine operating conditions such as temperature, throttle opening, accelerator opening, engine speed, and coolant temperature.

  That is, an airflow sensor 52 and an intake air temperature sensor 53 are mounted on the upstream side of the intake pipe 31, and the measured intake air amount and intake air temperature are output to the ECU 51. The electronic throttle device 34 is provided with a throttle position sensor 54, and the accelerator pedal is provided with an accelerator position sensor 55, which outputs the current throttle opening and accelerator opening to the ECU 51. The crankshaft 16 is provided with a crank angle sensor 56 and outputs the detected crank angle to the ECU 51. The ECU 51 discriminates an intake stroke, a compression stroke, an expansion stroke, an exhaust stroke in each cylinder based on the crank angle, and an engine. Calculate the number of revolutions. Further, the cylinder block 11 is provided with a water temperature sensor 57 and outputs the detected engine cooling water temperature to the ECU 51.

  An air-fuel ratio (A / F) sensor (or oxygen sensor) 58 is provided upstream of the three-way catalyst 37 in the exhaust pipe 36. The A / F sensor 58 detects the exhaust air / fuel ratio (oxygen amount) of the exhaust gas exhausted from the combustion chamber 18 through the exhaust port 20 and the exhaust manifold 35 to the exhaust pipe 36, and outputs the detected exhaust air / fuel ratio to the ECU 51. is doing. The ECU 51 corrects the fuel injection amount by feeding back the exhaust air-fuel ratio detected by the A / F sensor 58 and comparing it with the target air-fuel ratio set according to the engine operating state.

  Further, the ECU 51 can control the intake variable valve mechanism 25 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  In the internal combustion engine of the present embodiment configured as described above, as shown in FIGS. 1 to 3, the intake port 19 formed in the cylinder head 12 has a base end (upstream end) at the intake manifold 29. On the other hand, the tip end portions (downstream end portions) become branch passages 19a and 19b that branch into two in the horizontal direction, and each branch passage 19a and 19b communicates with one common combustion chamber 18. The intake valve 21 is provided corresponding to the two branch passages 19a and 19b. Each intake valve 21 has a shaft portion 21a that is supported by the cylinder head 12 so as to be movable in the axial direction, and the urging force of a valve spring (not shown) causes the umbrella portion 21b to be connected to each branch passage 19a, 19b and the combustion chamber. The communication part with 18 is closed. In FIG. 1, reference numeral 12 a denotes a partition wall that is integrally formed with the cylinder head 12 and divides the branch passages 19 a and 19 b.

  Further, two injectors 43 (43a, 43b) capable of injecting fuel toward the branch passages 19a, 19b are provided on the base end side of the intake port 19 in the cylinder head 11. Each injector 43a, 43b has the same configuration, and as shown in FIG. 4, the first injection hole 61 provided in the center of the tip end portion and the outer periphery of the first injection hole 61 in the tip end portion are provided. The second nozzle hole 62 has an inner diameter smaller than that of the first nozzle hole 61.

  That is, at the tip of the injectors 43a and 43b, four first injection holes 61 form a ring shape (square) at the center and are formed at equal intervals in the circumferential direction. In addition, at the tip of the injectors 43a and 43b, eight second nozzle holes 62, which are larger than the first nozzle holes 61, form a ring shape on the outer periphery of the four first nozzle holes 61, and are uniform in the circumferential direction. It is formed at intervals. In this case, the inner diameter of each second nozzle hole 62 is set smaller than the inner diameter of each first nozzle hole 61. Therefore, the spray particle diameter injected from each second nozzle hole 62 is set to be smaller than the spray particle diameter injected from each first nozzle hole 61.

  The injector 43a is configured so that the fuel spray A injected from the first injection holes 61 and the second injection holes 62 is injected radially into the branch passage 19a of the intake port 19. The formation position and the formation direction of the nozzle holes 61 and 62 are set. Further, the injector 43b is configured so that the fuel spray B injected from the first injection holes 61 and the second injection holes 62 is injected radially into the branch passage 19b of the intake port 19. The formation position and the formation direction of each nozzle hole 61 and 62 are set.

Further, the fuel sprays A and B from the injection holes 61 and 62 of the injectors 43a and 43b are located at the center of the fuel sprays A ₁ and B ₁ having large particle diameters injected from the first injection holes 61, respectively. The fuel sprays A ₂ and B ₂ having small particle diameters that are injected from the second injection holes 62 are positioned on the outer side so as to spread radially. As the fuel spray _A 1, _{B 1} is directed to a connecting portion between the shaft portion 21a and the valve head 21b of the intake valves 21, the injection holes 61, 62 are directed. On the other hand, the nozzle holes 61 and 62 are oriented so that the fuel sprays A ₂ and B ₂ do not contact the wall surfaces of the branch passages 19a and 19b.

  In the internal combustion engine of the present embodiment, the ECU 51 moves from the injectors 43a and 43b to the branch passages 19a and 19b during the intake stroke in which the intake valves 21 move downward and the branch passages 19a and 19b communicate with the combustion chamber 18. The injection timings of the injectors 43a and 43b are controlled so that the fuel is injected toward.

  Here, the fuel injection in the internal combustion engine of the present embodiment will be described in detail.

  As shown in FIGS. 1 to 4, when each intake valve 21 descends, each branch passage 19a, 19b in the intake port 19 is opened, and the intake port 19 and the combustion chamber 18 communicate with each other via each branch passage 19a, 19b. To do. At this time, each injector 43a, 43b injects fuel toward each branch passage 19a, 19b. Then, air in the intake port 19 is sucked into the combustion chamber 18 through the branch passages 19a and 19b, and fuel spray injected into the branch passages 19a and 19b is sucked into the combustion chamber together with this air. That is, a fuel / air mixture is introduced into the combustion chamber 18.

At this time, the fuel sprays A and B from the injectors 43a and 43b are injected toward the branch passages 19a and 19b, but the large-particle-size fuel sprays A ₁ and A injected from the first injection holes 61 are used. B ₁ is injected toward the connecting portion between the shaft portion 21 a and the umbrella portion 21 b in each intake valve 21, and the small particle size fuel sprays A ₂ and B ₂ injected from the second injection holes 62 are: It is injected so that it does not contact the wall surface of each branch passage 19a, 19b. Therefore, deposits are washed away by the fuel sprays A ₁ and B _{1 having} a large penetrating force when a part of the fuel sprays A ₁ and B _{1 having} a large particle size collide with the back of the umbrella portion 21b in each intake valve 21. Thus, this deposit is suppressed. Further, since the fuel sprays A ₂ and B ₂ having a small particle diameter pass near the wall surfaces of the branch passages 19a and 19b, the fuel adhesion to the wall surfaces is suppressed.

  Thereafter, the air-fuel mixture flowing into the combustion chamber 18 turns into a tumble flow and vertically swirls in the combustion chamber 18, and the tumble flow is compressed and split as the piston 14 rises to generate a large number of vortex flows. . Then, when a spark is generated from the spark plug 44, the air-fuel mixture is ignited and the combustion spreads in the combustion chamber 18.

  Thus, in the internal combustion engine of the present embodiment, the intake port 19 having the branch passages 19a and 19b branched into two with respect to the combustion chamber 18 is provided, and the intake valve 21 for opening and closing the branch passages 19a and 19b. And two injectors 43a and 43b capable of injecting fuel in the branch passages 19a and 19b. The first injection hole 61 is provided at the center of the tip of each injector 43a and 43b. A second nozzle hole 62 having a smaller diameter than the first nozzle hole 61 is provided on the outer periphery of the nozzle hole 61.

  Therefore, the spray particle diameter injected from the second nozzle hole 62 in each injector 43a, 43b is smaller than the spray particle diameter injected from the first nozzle hole 61. From the injectors 43a, 43b, the center particle The fuel sprays A and B having a large diameter and a small outside particle size are injected toward the branch passages 19a and 19b, and the exhaust gas is suppressed while preventing fuel from adhering to the intake port 19 (branch passages 19a and 19b). The purification efficiency can be improved.

Further, in the internal combustion engine of the present embodiment, the second injection holes 62 are provided in a plurality of ring shapes around the outer periphery of the first injection holes 61. Accordingly, the fuel sprays A (A ₁ , A ₂ ) and B (B ₁ , B ₂ ) injected from the first injection hole 61 and the second injection hole 62 are injected so as to spread radially, and the diffusion efficiency is increased. Can be improved.

  Further, in the internal combustion engine of the present embodiment, a plurality of first injection holes 61 and a plurality of second injection holes 62 are provided, and more second injection holes 62 than the first injection holes 61 are provided. Therefore, the spray amount of the fuel spray that spreads radially can be made substantially the same on the inner side and the outer side, and an appropriate air-fuel mixture can be generated.

Further, in the internal combustion engine of the present embodiment, the first injection hole 61 is directed to the connection portion between the shaft portion 21 a and the umbrella portion 21 b in the intake valve 21. Therefore, the fuel sprays A ₁ and B ₁ from the first injection hole 61 having a large penetration force easily collide with the back side of the umbrella portion 21b, and deposit accumulation can be suppressed.

  In the internal combustion engine of this embodiment, the injectors 43a and 43b can inject fuel into the branch passages 19a and 19b when the branch passages 19a and 19b are opened by the intake valve 21. Therefore, by injecting fuel during the intake stroke, fuel adhesion to the wall surface of the intake port is prevented, and an appropriate air-fuel mixture can be supplied to the combustion chamber 18.

  In the above-described embodiment, the tip of the intake port 19 is branched into two to form two branch passages 19a and 19b. However, three or more may be formed, and in this case, the same number of injectors may be provided. It is good.

  As described above, the internal combustion engine according to the present invention is provided with a plurality of fuel injection valves that communicate with the combustion chamber from the intake port through the plurality of branch passages and can inject fuel into each branch passage. The first injection hole is provided in the center of the portion, and the second injection hole having a small diameter is provided in the outer periphery of the first injection hole, thereby suppressing fuel adhesion to the intake port and improving exhaust purification efficiency. Yes, it is useful for any internal combustion engine.

It is a principal part longitudinal cross-sectional view in the internal combustion engine which concerns on one Example of this invention. It is a horizontal sectional view of an intake port showing fuel spray from an injector in an internal-combustion engine of this example. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is the schematic showing the front-end | tip part of the injector in the internal combustion engine of a present Example. It is a schematic block diagram showing the whole structure in the internal combustion engine of a present Example.

Explanation of symbols

12 Cylinder head 14 Piston 18 Combustion chamber 19 Intake port 19a, 19b Branch passage 20 Exhaust port 21 Intake valve 22 Exhaust valve 43, 43a, 43b Injector (fuel injection valve)
44 Spark plug 61 First nozzle hole 62 Second nozzle hole

Claims (6)

A combustion chamber;
An intake port having a plurality of branch passages communicating with the combustion chamber;
A plurality of intake valves capable of opening and closing each branch passage of the intake port;
A plurality of fuel injection valves capable of injecting fuel into each branch passage of the intake port;
An internal combustion engine comprising:
Each of the fuel injection valves includes a first injection hole provided in the center of the tip end portion, and a second injection hole provided in the outer periphery of the first injection hole at the tip end portion and having an inner diameter smaller than the first injection hole. Have
An internal combustion engine characterized by that.   2. The internal combustion engine according to claim 1, wherein the spray particle diameter injected from the second nozzle hole is set smaller than the spray particle diameter injected from the first nozzle hole.   3. The internal combustion engine according to claim 1, wherein the second injection hole is provided in a plurality of ring shapes around an outer periphery of the first injection hole.   4. The device according to claim 1, wherein a plurality of the first nozzle holes and the second nozzle holes are provided, and the second nozzle holes are provided more than the first nozzle holes. 5. Internal combustion engine.   5. The internal combustion engine according to claim 1, wherein the first injection hole is directed to a connection portion between a shaft portion and an umbrella portion of the intake valve.   The internal combustion engine according to any one of claims 1 to 5, wherein the fuel injection valve is capable of injecting fuel when the branch passage is opened by the intake valve.

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