JP2003193940A - Fuel injector and fuel injection valve of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain excellent combustion by suppressing degradation of homogeneity of the mixture of a fuel with air when forming fuel atomization expanding in a fan shape by the injection of the fuel in a combustion chamber during the homogeneous combustion. <P>SOLUTION: In an air intake stroke during the homogeneous combustion, not only a first fuel atomization 16 in a fan shape expanding in the width direction of the combustion chamber 2 is formed, but also a second fuel atomization 17 in a fan shape expanding in the axial direction of the combustion chamber 2 is also formed. The sectional area in the width direction of the combustion chamber 2 in the second fuel atomization 17 is smaller than that in the first fuel atomization 16. Therefore, the effect is small, in which the fuel atomization 17 is pressed by a head top part side of a piston 6 and an inner wall side of the combustion chamber 2 when the air sucked into the combustion chamber 2 from an intake passage 7 in the intake stroke flows along the axial direction of the combustion chamber 2 as the piston 6 moves. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device and a fuel injection valve for an internal combustion engine.

[0002]

2. Description of the Related Art In an in-cylinder injection type internal combustion engine mounted on a vehicle such as an automobile, fuel is directly injected from a fuel injection valve into a combustion chamber where air is sucked from an intake passage, and this fuel injection causes combustion chamber to be injected. A fuel spray is formed on. When a mixture of fuel and air is ignited by a spark plug in the combustion chamber, the mixture is combusted and the combustion energy at that time causes the piston to reciprocate. The combustion mode of the air-fuel mixture includes "homogeneous combustion" in which a homogeneous air-fuel mixture in which fuel is evenly mixed with air is combusted in accordance with the engine operating state, and stratification in which a combustible air-fuel mixture exists only around the spark plug. It is switched between "stratified combustion" in which the air-fuel mixture is burned.

When forming a homogeneous mixture during homogeneous combustion, fuel is injected during the intake stroke in which air is drawn into the combustion chamber from the intake passage as the piston moves. The fuel spray formed in the combustion chamber by the fuel injection during the intake stroke is entrained in the flow of air sucked into the combustion chamber from the intake passage and mixed with the same. Thus, a homogeneous mixture is formed in the combustion chamber.

Further, when forming a stratified mixture during stratified combustion, fuel is injected during a compression stroke in which air in the combustion chamber is compressed as the piston moves. The fuel spray formed in the combustion chamber by the fuel injection in the compression stroke is moved to the vicinity of the spark plug by using the penetration force of the spray itself after hitting the top of the piston. In this way, a stratified mixture is formed in the combustion chamber.

By the way, the fuel spray formed in the combustion chamber is produced by injecting the fuel from the fuel injection valve so as to spread in the width direction of the combustion chamber, so that the width of the combustion chamber is, for example, as disclosed in JP 2001-27170 A. It is shaped like a fan that spreads in the direction. It has been confirmed that the fuel spray formed in the combustion chamber has a fan shape as described above, so that the penetrating force of the spray itself is increased. Due to this spray shape, the fuel spray is moved close to the ignition plug during stratified combustion. We are trying to secure the necessary penetrating power.

Further, by making the fuel spray formed in the combustion chamber fan-shaped as described above, the fuel spray moves near the spark plug while entraining a large amount of air during stratified combustion. Therefore, as compared with the case where the fuel spray is formed in a conical shape, the vaporization of the fuel can be promoted, and the combustion of the stratified mixture can be improved.

[0007]

By injecting the fuel so that the fuel spray formed in the combustion chamber is fan-shaped as described above, the above effect can be obtained during stratified combustion, but during homogeneous combustion. Also in the case of stratified combustion, the fuel spray formed in the combustion chamber becomes fan-shaped.

When the fan-shaped fuel spray as described above is formed in the combustion chamber by the fuel injection in the intake stroke during the homogeneous combustion, the air sucked from the intake passage into the combustion chamber hits the fuel spray. Become. This air is drawn toward the piston side along the center axis direction of the combustion chamber (piston) with the movement of the piston during the intake stroke, so that the fan-shaped fuel spray is pushed in the thickness direction to the top side of the piston. It will be pressed against the inner wall of the combustion chamber.

When the fuel spray in the combustion chamber is suppressed in this manner, the fuel is unevenly present in the combustion chamber at the top of the piston and the inner wall of the combustion chamber, so that ignition by the ignition plug is performed. When it is performed, the fuel-rich mixture remains in that portion. Therefore, the homogeneity of the air-fuel mixture during homogeneous combustion deteriorates,
There is a problem that it is difficult to obtain good combustion of the air-fuel mixture.

The present invention has been made in view of such circumstances, and an object thereof is to form a fuel spray that spreads in a fan shape by fuel injection into a combustion chamber during homogeneous combustion,
An object of the present invention is to provide a fuel injection device and a fuel injection valve for an internal combustion engine capable of suppressing deterioration of the homogeneity of the air-fuel mixture of fuel and air resulting in poor combustion.

[0011]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In order to achieve the above object, in the invention according to claim 1, in a fuel injection device for an internal combustion engine, which directly injects fuel into a combustion chamber where air is sucked from an intake passage, a fan-shaped first spreading in the width direction of the combustion chamber. The fuel injection means for forming the fuel spray No. 1 and the fan-shaped second fuel spray spreading in the central axis direction of the combustion chamber during the same intake stroke are provided.

The air taken into the combustion chamber from the intake passage during the intake stroke is drawn toward the piston along the central axis of the combustion chamber as the piston moves. Since the first fuel spray formed in the combustion chamber during the intake stroke has a fan shape that spreads in the width direction of the combustion chamber, it is pressed against the top of the piston and the inner wall of the combustion chamber by the air. . On the other hand, the second fuel spray formed in the combustion chamber during the same intake stroke as that in which the first fuel spray is formed becomes a fan shape that spreads in the central axis direction of the combustion chamber, and the width direction of the combustion chamber. The cross-sectional area of is small. Therefore, the second fuel spray is affected by the fact that even if the air flowing through the combustion chamber along the central axis direction is hit, it is pressed against the top of the piston and the inner wall of the combustion chamber. Hateful. Therefore, by forming the second fuel spray in the combustion chamber during the intake stroke, the air-fuel mixture with a high fuel concentration stays on the top of the piston and the inner wall of the combustion chamber, and the homogeneity of the air-fuel mixture deteriorates. Can be suppressed. Then, it is possible to prevent the good combustion from not being obtained due to the deterioration of the homogeneity of the air-fuel mixture.

According to a second aspect of the invention, in the first aspect of the invention, the fuel injection means forms the first fuel spray and the second fuel spray at the same time. In an internal combustion engine in which fuel is directly injected into the combustion chamber, the heat of vaporization is taken from the air in the combustion chamber when the fuel spray formed in the combustion chamber is vaporized, so the air is cooled and There is an effect that the air filling efficiency is increased and the knock resistance is improved. Regarding such effects, the maximum effect can be obtained by injecting fuel and efficiently vaporizing the fuel spray when the flow velocity of the air sucked into the combustion chamber from the intake passage becomes highest. According to the above configuration, the first fuel spray and the second fuel spray can be formed at the same time when the flow velocity of the air sucked from the intake passage into the combustion chamber becomes the highest, so that the first fuel spray and the second fuel spray can be formed simultaneously. It is possible to efficiently vaporize the second fuel spray together and obtain the above-described effect at a high level.

According to a third aspect of the present invention, in the second aspect of the invention, the fuel injection means is configured such that when the flow velocity of the air sucked into the combustion chamber from the intake passage becomes the highest, the first fuel is injected. The spray and the second fuel spray are simultaneously formed.

According to the above construction, both the first and second fuel sprays can be efficiently vaporized. for that reason,
It is possible to efficiently cool the air in the combustion chamber by using the heat of vaporization of the fuel, to enhance the efficiency of filling the combustion chamber with air and to improve the knock resistance at a high level.

According to the invention described in claim 4, in the invention described in any one of claims 1 to 3, the fuel injection means is:
The second fuel spray is formed on the upstream side of the flow of the intake air with respect to the first fuel spray.

The influence of receiving the flow of the air sucked into the combustion chamber from the intake passage is larger in the first fuel spray than in the second fuel spray. However, since the second fuel spray having the smaller influence is on the upstream side of the flow of the intake air than the first fuel spray, the first and second fuel sprays are generated by the flow of the intake air to the piston. When pushed toward the top of the head and the inner wall of the combustion chamber, the first and second fuel sprays are less likely to overlap. Therefore, it is possible to suppress an excessively high fuel concentration region in the combustion chamber due to the overlapping of the fuel sprays.

According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, the fuel injection means is:
A single fuel injection valve was provided for injecting the fuel so as to spread in the width direction of the combustion chamber, and at the same time for injecting the fuel so as to spread in the center axis direction of the combustion chamber.

According to the above arrangement, the first fuel spray and the second fuel spray
In comparison with the case where a plurality of fuel injection valves are used to form the fuel spray and the case where a mechanism for changing the spreading direction of the spray is provided by rotating the injection holes for fuel injection (fuel injection valve), The structure of the fuel injection device can be simplified, and the cost increase due to the complicated structure can be suppressed.

According to the invention of claim 6, in the invention of claim 5, the fuel injection valve has a first slit extending in the width direction of the combustion chamber and a second slit extending in the central axis direction of the combustion chamber. The fuel was to be injected from the slit of.

According to the above structure, the first fuel spray is formed by the fuel injection from the first slit, and the second fuel spray is formed by the fuel injection from the second slit. The first and second fuel sprays can be accurately formed by the fuel injection valve.

According to the invention of claim 7, in the invention of claim 6, the second slit is formed on the upstream side of the flow of the intake air with respect to the first slit. did.

According to the above construction, the second fuel spray is applied to the first fuel spray.
Can be formed on the upstream side of the flow of the intake air with respect to the fuel spray. Therefore, when the first fuel spray, which is more easily affected by the flow of the intake air than the second fuel spray, is pressed by the intake air toward the top of the piston and the inner wall of the combustion chamber, It is difficult for the first and second fuel sprays to overlap. Therefore, it is possible to suppress an excessively high fuel concentration region in the combustion chamber due to the overlapping of the fuel sprays.

In the invention of claim 8, claim 6 or 7
In the invention described above, the gist is that the first slit and the second slit are formed so as not to overlap with each other.

If the first slit and the second slit overlap each other, the fuel injection amount per unit area is smaller than that of other portions because the resistance at the time of fuel injection becomes small in the overlapping portion. Is large. As a result, in the combustion chamber, the fuel concentration in the region corresponding to the overlapping portion of the first and second slits becomes higher than that in the other region, which is disadvantageous in obtaining good combustion. However, according to the above configuration, since the first slit and the second slit are separated from each other and do not overlap each other, it is possible to prevent the above-mentioned problems from occurring.

According to a ninth aspect of the invention, in the invention according to any one of the first to eighth aspects, the intake passage is connected to the combustion chamber in a state of being branched into a plurality of parts,
The fuel injection device includes a plurality of intake valves that open and close so as to connect and disconnect the plurality of intake passages and the combustion chamber, and the fuel injection means includes two adjacent intake valves of the plurality of intake valves. The second fuel spray is formed between the two.

According to the above construction, when the plurality of intake valves are opened and protrude into the combustion chamber during the intake stroke, at least one of the intake valves is hit by the second fuel spray in the combustion chamber, and the combustion is accompanied by the combustion. It is possible to prevent the uneven distribution of fuel in the chamber from deteriorating the homogeneity of the air-fuel mixture and the decrease in the margin for improving the filling efficiency using the heat of vaporization.

According to a tenth aspect of the present invention, there is provided a fuel injection valve for injecting fuel into a combustion chamber of an internal combustion engine, wherein first and second slits for injecting the fuel extend in directions orthogonal to each other. So formed.

According to the above construction, the first fuel spray that spreads in a fan shape is formed by the fuel injection from the first slit, and the second fuel that spreads in a fan shape is formed by the fuel injection from the second slit. A spray is formed, and the first and second fuel sprays spread in directions orthogonal to each other. Therefore, for example, by providing the fuel injection valve in the internal combustion engine so that the first fuel spray spreads in the width direction of the combustion chamber, the second fuel spray spreads in the central axis direction of the combustion chamber. When the fuel is injected from the fuel injection valve during the intake stroke of the internal combustion engine to form the first and second fuel sprays in the combustion chamber, the first fuel spray is directed to the central axis of the combustion chamber as the piston moves. The air from the intake passage along which the air is drawn toward the piston is pressed against the top of the piston and the inner wall of the combustion chamber. On the other hand, the second fuel spray has a small cross-sectional area in the width direction of the combustion chamber. Therefore, when the intake air flowing along the central axis direction of the combustion chamber hits the second fuel spray, It is unlikely to be affected by being pressed against the top of the head and the inner wall of the combustion chamber. Therefore, by forming the second fuel spray in the combustion chamber, it is possible to prevent the air-fuel mixture having a high fuel concentration from staying on the top side of the piston and the inner wall side of the combustion chamber and deteriorating the homogeneity of the air-fuel mixture. be able to. Then, it is possible to prevent the good combustion from not being obtained due to the deterioration of the homogeneity of the air-fuel mixture.

The eleventh aspect of the present invention is based on the tenth aspect of the present invention, wherein the first slit and the second slit are formed so as not to overlap with each other.

If the first slit and the second slit overlap each other, the fuel injection amount per unit area is smaller than that of the other portions because the resistance at the time of fuel injection becomes small in the overlapping portion. Is large. As a result, in the combustion chamber, the fuel concentration in the region corresponding to the overlapping portion of the first and second slits becomes higher than that in the other region, which is disadvantageous in obtaining good combustion. However, according to the above configuration, since the first slit and the second slit are separated from each other and do not overlap each other, it is possible to prevent the above-mentioned problems from occurring.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a cylinder injection spark ignition type engine mounted on an automobile will be described below with reference to FIGS.

FIG. 1 is an enlarged sectional view showing the periphery of the combustion chamber 2 in the engine 1. The engine 1 is provided with a cylinder block 4 having a plurality of cylinders 3 (only one is shown in FIG. 1), a cylinder head 5 attached to the cylinder block 4, and reciprocally movable in the cylinder 3. And a piston 6. The combustion chamber 2 is defined by the cylinder block 4, the cylinder head 5, and the piston 6.

An intake passage 7 and an exhaust passage 8 are connected to the combustion chamber 2. Then, the combustion chamber 2 and the intake passage 7 are connected / disconnected by the opening / closing operation of the intake valve 9, and the combustion chamber 2 and the exhaust passage 8 are connected / disconnected by the opening / closing operation of the exhaust valve 10. The intake valve 9 is opened during the intake stroke of the engine 1, and the exhaust valve 10 is opened during the exhaust stroke of the engine 1.

The intake passage 7 is connected to the combustion chamber 2 in a branched state as shown in FIG. The intake valve 9 described above is provided in each intake passage 7 after being branched into two.
Two combustion chambers 2 are provided for each combustion chamber 2 so that communication between the combustion chamber 2 and the combustion chamber 2 can be established.

When the intake valve 9 is opened during the intake stroke of the engine 1, air is taken into the combustion chamber 2 from the intake passage 7 branched into two. This air is the piston 6
1 is pulled toward the piston 6 in the combustion chamber 2 and moves along the central axis L1 of the combustion chamber 2 (the central axis of the cylinder 3 and the piston 6).

The engine 1 has a fuel injection valve 11 for directly injecting fuel into the combustion chamber 2 and an ignition plug 1 for igniting a mixture of fuel and air existing in the combustion chamber 2.
2 and are provided. When the air-fuel mixture burns due to ignition by the spark plug 12, the combustion energy at that time causes the piston 6 to reciprocate, and the engine 1 is driven. The fuel injection of the fuel injection valve 11 is controlled by the electronic control unit 13 mounted on the vehicle to control the operation of the engine 1.

The combustion modes of the air-fuel mixture are "homogeneous combustion" in which a homogeneous air-fuel mixture in which fuel is evenly mixed with air is combusted in accordance with engine operating conditions, and combustible air-fuel mixture only around the spark plug 12. Is switched between "stratified combustion", in which a stratified mixture is burned.

When forming a homogeneous mixture during homogeneous combustion, fuel is injected from the fuel injection valve 11 into the combustion chamber 2 during the intake stroke. The fuel spray formed in the combustion chamber 2 by this fuel injection is entrained in the flow of air drawn into the combustion chamber 2 from the intake passage 7 and mixed with the same. In this way, a homogeneous mixture is formed in the combustion chamber 2, and the homogeneous combustion is realized by burning the mixture.

When forming a stratified mixture during stratified combustion, fuel is injected from the fuel injection valve 11 into the combustion chamber 2 during the compression stroke. The fuel spray formed in the combustion chamber 2 by this fuel injection hits the inner wall of the concave cavity 6a formed at the crown of the piston 6, and utilizes the penetration force of the spray itself and the cavity 6a to cause the spark plug 12 to discharge. Moved to near. Thus, a stratified mixture is formed in the combustion chamber, and the stratified combustion is realized by burning the mixture.

Next, the fuel injection valve 11 will be described with reference to FIGS.
Will be described in detail with reference to. FIG. 3 is a front view showing the injection hole shape of the fuel injection valve 11. First and second slits 14 and 15 extending in directions orthogonal to each other are formed in the fuel injection valve 11 as injection holes for injecting fuel. The first slit 14 extends in the radial direction of the fuel injection valve 11. On the other hand, the second slit 15 is separated from the first slit 14 by a predetermined distance at a position corresponding to the center in the longitudinal direction of the first slit 14, and the fuel injection valve 1
It extends in the radial direction of 1 and in the direction orthogonal to the first slit 14.

When fuel injection from the fuel injection valve 11 is executed, the fuel is injected through the first and second slits 14 and 15 shown in FIG.
And fuel is injected as shown in FIG. Note that FIG. 5 shows a first fuel spray 16 formed by the fuel injected through the first slit 14 and a second fuel spray 16 formed by the fuel injected through the second slit 15.
3 shows the spray shape of the fuel spray 17 of FIG. In addition, FIG. 6 shows the first and second fuel sprays 1
6 and 7 show spray shapes when viewed from above.

As can be seen from these figures, the first fuel spray 16 has a fan shape that spreads in the radial direction of the fuel injection valve 11, and the second fuel spray 17 spreads in the direction orthogonal to the first fuel spray 16. It has a fan shape. Further, the first fuel spray 16 and the second fuel spray 17 are formed apart from each other so as not to overlap each other. This is the first fuel spray 1
This is because the first slit 14 for forming 6 and the second slit 15 for forming the second fuel spray 17 are formed so as not to overlap each other.

Assuming that the first and second slits 14 and 15 are
When the two overlap, the resistance at the time of injecting fuel becomes small in the overlapped portion, so that the fuel injection amount per unit area becomes larger in the overlapped portion than in the other portions. As a result, in the fuel spray formed when the fuel injection is performed, the fuel concentration of the portion corresponding to the overlapping portion of the first and second slits 14 and 15 is higher than that of the other portions, and good combustion is obtained. Will be at a disadvantage. However, by forming the first slit 14 and the second slit 15 so as to be separated from each other as described above, the first fuel spray 16 and the second fuel spray 17 are separated from each other, and It is possible to suppress the occurrence of such problems.

Further, the fuel injection valve 11 for the engine 1
The attachment is preferably performed so as to satisfy the following conditions [1] to [4]. [1] The first fuel spray 16 spreads in the width direction of the combustion chamber 2 (cylinder 3, piston 6 width direction), and the second fuel spray 17 spreads in the central axis direction of the combustion chamber 2 (cylinder 3, piston 6).
Spread in the direction of the central axis of the).

[2] When fuel is injected during the intake stroke to perform homogeneous combustion, the first fuel spray 16 is formed at a position closer to the piston 6 than the position when the intake valve 9 is opened. [3] The second fuel spray 17 is formed upstream of the first fuel spray 16 in the flow of intake air in the intake stroke and so as not to hit the spark plug 12.

[4] The second fuel spray 17 is formed between the two intake valves 9 shown by the alternate long and two short dashes line in FIG. 6 so that the distances X from the two intake valves 9 are equal to each other.
Here, regarding the advantage of forming the fuel spray as shown in the above [1] to [4] by the fuel injection from the fuel injection valve 11, only the fan-shaped fuel spray spreading in the width direction of the combustion chamber 2 is formed. Description will be made based on a comparison with the related art.

During the intake stroke of the engine 1, the air sucked into the combustion chamber 2 from the intake passage 7 is drawn toward the piston 6 as described above and flows along the central axis of the combustion chamber 2. . Therefore, conventionally, when fuel injection in the intake stroke is performed to perform homogeneous combustion, the air flowing as described above hits the fuel spray that spreads in a fan shape in the combustion chamber 2, and the spray sprays the top of the piston 6 and the combustion. It is pressed against the inner wall side of the chamber 2. In this case, it becomes difficult for the fuel spray and the air to be mixed, and even after the transition from the intake stroke to the compression stroke, as shown by the alternate long and two short dashes line in FIG. To exist.

Therefore, even when the ignition by the spark plug 12 is performed, the fuel rich portion and the fuel lean portion remain in the combustion chamber 2, and the homogeneity of the mixture during homogeneous combustion is maintained. It becomes worse and it becomes difficult to obtain good combustion of the air-fuel mixture. In addition, when the vaporization heat of the fuel spray is used to efficiently cool the air in the combustion chamber 2 to increase the efficiency of filling the combustion chamber 2 with air and to improve the knock resistance, combustion is performed from the intake passage 7. When the flow velocity of the air sucked into the chamber 2 becomes high and the fuel becomes easy to vaporize, the fuel spray has to be formed. In this case, the fuel flow in the combustion chamber 2 is more likely to be pressed to the crown portion side of the piston 6 or the inner wall side of the combustion chamber 2 by the flow of the air having a high flow velocity, and the above-mentioned problem becomes remarkable.

On the other hand, in the present embodiment, when the fuel injection in the intake stroke is performed in order to carry out the homogeneous combustion, as described above, the first and second fuel sprays 16 and 17 are in the same intake stroke. Is formed in the combustion chamber 2. The formation of the first and second fuel sprays 16 and 17 is performed by the electronic control unit 13
The drive control of the fuel injection valve 11 is performed, for example, during the period in which the flow velocity of the air sucked from the intake passage 7 into the combustion chamber 2 becomes the highest in the intake stroke.

Since the first fuel spray 16 has a fan shape that spreads in the width direction of the combustion chamber 2, the air flowing along the central axis direction of the combustion chamber 2 causes the top of the piston 6 and the combustion chamber 2 to move. It is pressed down on the inner wall side. But the second
The fuel spray 17 has a fan shape that spreads in the central axis direction of the combustion chamber 2 and has a small cross-sectional area in the width direction of the combustion chamber 2. Therefore, when the air hits, the top of the piston 6 and the combustion are Less susceptible to being pressed against the inner wall of the chamber 2.

Therefore, during the intake stroke, the second fuel spray 17
Is formed in the combustion chamber 2, it is possible to prevent the air-fuel mixture having a high fuel concentration from staying on the top of the piston 6 and the inner wall of the combustion chamber 2 and deteriorating the homogeneity of the air-fuel mixture. Then, it is possible to prevent a situation where good combustion cannot be obtained due to deterioration of the homogeneity of the air-fuel mixture during homogeneous combustion.

During the same intake stroke as the formation of the second fuel spray 17, the fan-shaped first fuel spray 16 spreading in the width direction of the combustion chamber 2 is also formed. Therefore, although the first fuel spray 16 is pressed to the top portion side of the piston 6 and the inner wall side of the combustion chamber 2 by the intake air during the intake stroke, the first fuel spray 16 of the combustion chamber 2 does not work. It becomes possible to promote the diffusion of the fuel in the width direction.

The second fuel spray 17, which is less affected by the flow of intake air, is located closer to the intake passage 7 in the combustion chamber 2 than the first fuel spray 16, which is greatly affected, that is, the intake air. It is formed on the upstream side of the first fuel spray 16 in the flow of intake air in the stroke. Therefore, when the first and second fuel sprays 16, 17 are pushed to the top of the piston 6 and the inner wall of the combustion chamber 2 by the flow of the intake air, the first and second fuel sprays 16, 1
7 is hard to overlap. Then, the first and second fuel sprays 1
It is possible to suppress the generation of an excessively high fuel concentration region in the combustion chamber 2 due to the overlapping of 6 and 17.

Further, the second fuel spray 17 is formed between the two intake valves 9. Therefore, when the intake valve 9 opens and protrudes into the combustion chamber 2 during the intake stroke, the second fuel spray 17 hits the intake valve 9, causing uneven distribution of the fuel in the combustion chamber 2 and mixing. It becomes possible to suppress the deterioration of the homogeneity of the air.

Next, the difference in the combustion fluctuation rate of the air-fuel mixture between when the fuel spray is formed as in the conventional case and when the fuel spray is formed as in this embodiment will be described with reference to FIG. .

FIG. 8 is a graph showing how the combustion fluctuation rate of the air-fuel mixture changes with changes in the fuel injection timing when fuel is injected during the intake stroke to perform homogeneous combustion. . In the figure, the broken line shows the transition of the combustion fluctuation rate with respect to the change of the fuel injection timing when the fuel spray is formed as in the conventional case, and the solid line shows the fuel injection when the fuel spray is formed as in the present embodiment. It shows the transition of the combustion fluctuation rate with respect to the change of the period.

As can be seen from this figure, in the period A in which the flow velocity of the air sucked into the combustion chamber 2 from the intake passage 7 becomes faster, the combustion fluctuation rate deteriorates in the conventional case (broken line), whereas in the present embodiment. In the form (solid line), deterioration of the combustion fluctuation rate is suppressed. This is because conventionally, good combustion cannot be obtained due to the deterioration of the homogeneity of the air-fuel mixture described above in the period A, whereas in the present embodiment, the first and second fuel sprays 16 and 17 in the combustion chamber 2 are obtained. This is because the homogeneity of the air-fuel mixture in the period A is improved by the formation of, and good combustion is obtained. Therefore, in the period A, conventionally, the fuel consumption rate deteriorates as the combustion variation rate deteriorates, whereas in the present embodiment, the deterioration of the combustion variation rate is suppressed, so that the fuel consumption rate is maintained good. Become.

In FIG. 8, the alternate long and two short dashes line indicates the position where the second fuel spray 17 is closer to the piston 6 than the first fuel spray 16, that is, the first fuel spray 16 of the intake air flow.
It also shows the transition of the combustion fluctuation rate when the deviation is formed on the downstream side. The injection hole shape of the fuel injection valve 11 in this case may be as shown in FIG. 4, for example. This injection hole shape and the injection hole shape shown in FIG.
The only difference is that the position of the slit 15 is on one side of the both sides of the first slit 14 in the width direction or on the other side.

Even when the injection hole shape of the fuel injection valve 11 is as shown in FIG. 4, the combustion fluctuation of the air-fuel mixture is as shown in FIG.
In the period A as shown by the two-dot chain line, the injection hole shape is better than the conventional one (broken line), and the fuel consumption rate is also better than the conventional one. Therefore, such an injection hole shape can be adopted.

According to this embodiment described in detail above, the following effects can be obtained. (1) During the intake stroke during homogeneous combustion, not only the fan-shaped first fuel spray 16 that spreads in the width direction of the combustion chamber 2 is formed, but also the fan-shaped second fuel spray 16 that spreads in the central axis direction of the combustion chamber 2. The fuel spray 17 is also formed. Regarding the second fuel spray 17, the cross-sectional area in the width direction of the combustion chamber 2 is the first fuel spray 16
It is smaller than Therefore, when the air sucked into the combustion chamber 2 from the intake passage 7 during the intake stroke flows along the central axis direction of the combustion chamber 2 with the movement of the piston 6 and hits the second fuel spray 17, The influence of the spray 17 being pushed toward the crown of the piston 6 and the inner wall of the combustion chamber 2 is small. By thus forming the second fuel spray 17 in the combustion chamber 2 during the intake stroke, a large amount of air-fuel mixture having a high fuel concentration stays at the top of the piston 6 and the inner wall of the combustion chamber 2 during homogeneous combustion. As a result, the deterioration of the homogeneity of the air-fuel mixture can be suppressed. Then, it is possible to prevent the good combustion from not being obtained due to the deterioration of the homogeneity of the air-fuel mixture.

(2) During the same intake stroke in which the second fuel spray 17 is formed, the fan-shaped first fuel spray 16 that spreads in the width direction of the combustion chamber 2 is also formed. for that reason,
Although the first fuel spray 16 is pressed to the top of the piston 6 and the inner wall of the combustion chamber 2 by the intake air during the intake stroke, the first fuel spray 16 causes the first fuel spray 16 to move in the width direction of the combustion chamber 2. About fuel diffusion can be promoted.

(3) In the engine 1 in which fuel is directly injected into the combustion chamber 2, the heat of vaporization is taken from the air in the combustion chamber 2 when the fuel spray formed in the combustion chamber 2 is vaporized. Therefore, there is an effect that the air is cooled and the efficiency of filling the combustion chamber 2 with air is increased. Regarding these effects, the maximum effect can be obtained by injecting fuel and efficiently vaporizing the fuel spray when the flow velocity of the air taken into the combustion chamber 2 from the intake passage 7 becomes highest. Therefore, during the period A in which the flow velocity of the intake air is highest during the intake stroke during homogeneous combustion, the first
And by forming the second fuel sprays 16 and 17,
The fuel sprays 16 and 17 can be efficiently vaporized, and the above-mentioned effects can be obtained at a high level.

(4) The first fuel spray 16 has a larger effect than the second fuel spray 17 due to the flow of the air sucked into the combustion chamber 2 from the intake passage 7. However, the second fuel spray 17 having the above-mentioned influence is smaller than the first fuel spray 17.
Is formed on the upstream side of the flow of the intake air above the fuel spray 16. Therefore, the first and second fuel sprays 16,1
When 7 is pushed to the crown side of the piston 6 and the inner wall side of the combustion chamber 2 by the flow of the intake air, the first and second fuel sprays 16 and 17 are less likely to overlap. Therefore, it is possible to suppress an excessively high fuel concentration region in the combustion chamber 2 due to the overlapping of the fuel sprays.

(5) Since the first and second slits 14 and 15 are formed as the injection holes for injecting fuel into the fuel injection valve 11, the first and second fuel sprays 16 and 17 are formed into a single fuel. It can be accurately formed by the injection valve 11. Therefore, the structure of the fuel injection device of the engine 1 can be simplified as compared with, for example, the case of using a plurality of fuel injection valves to form the first fuel spray 16 and the second fuel spray 17. It is possible to suppress an increase in cost due to the complicated structure.

(6) Since the second slit 15 is formed on the upstream side of the flow of intake air with respect to the first slit 14, the second fuel spray 17 is sucked more than the first fuel spray 16. It can be accurately formed on the upstream side of the air flow.

(7) The first slit 14 and the second slit 15 are formed so as to be separated from each other. Therefore, the first
As in the case where the second slits 14 and 15 overlap each other, in the fuel spray formed when the fuel injection is performed, the fuel concentration of the portion corresponding to the overlapping portion becomes darker than other portions, and good combustion is achieved. It is possible to suppress a disadvantage in obtaining it.

(8) The second fuel spray 17 is formed between the two intake valves 9. Therefore, when the intake valve 9 opens and protrudes into the combustion chamber 2 during the intake stroke during homogeneous combustion, the second fuel spray 17 hits the intake valve 9, which causes uneven distribution of fuel in the combustion chamber 2. It is possible to suppress deterioration of the homogeneity of the air-fuel mixture.

(9) Since the second fuel spray 17 is formed so as to have the equal distance X between the two intake valves 9,
When the second fuel spray 17 is biased toward one of the two intake valves 9 for some reason, it is possible to avoid the second fuel spray 17 from hitting the intake valve 9 as much as possible.

The above embodiment can be modified as follows, for example. When forming the second fuel spray 17 between the two intake valves 9, the distances between the second fuel spray 17 and the two intake valves 9 do not necessarily have to be equal to each other.

The present invention may be applied to an engine connected to the combustion chamber 2 in a state where the intake passage 7 is branched into three or more. In this case, one combustion chamber 2 is provided with a number of intake valves 9 corresponding to the number of branches of the intake passages 7, and opening and closing of the intake valves 9 connects and disconnects each intake passage 7 and the combustion chamber 2. It Then, the fuel injection valve 11 is attached to the engine 1 so that the second fuel spray 17 is formed between the two adjacent intake valves 9 of the plurality of intake valves 9.

The fuel injection valve 11 as shown in FIG.
The first slit 14 and the second slit 15 may be overlapped with each other. As shown in FIG. 10, the second slits 15 are formed on both sides of the first slit 14 in the fuel injection valve 11 in the width direction.
You may form a, 15b.

First fuel spray 16 and second fuel spray 1
7 and 7 may be formed by separate fuel injection valves instead of being formed by a single fuel injection valve 11. Also,
Only one slit may be provided in the fuel injection valve as an injection hole for fuel injection, and a mechanism may be provided to control the spreading direction of the fuel spray by rotating the injection hole (fuel injection valve). In this case, rotate the fuel injection valve 90 ° during the same intake stroke,
By injecting fuel before and after the rotation, two types of fuel sprays having different spreading directions of 90 ° are formed in the combustion chamber 2. In each of the modified examples described above, the timing for forming the first fuel spray 16 and the second
The timing of forming the fuel spray 17 can be appropriately shifted.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing the vicinity of a combustion chamber of an engine to which a fuel injection device and a fuel injection valve of this embodiment are applied.

FIG. 2 is a schematic view showing a shape of an intake passage of the engine.

FIG. 3 is a front view showing a shape of an injection hole of the fuel injection valve.

FIG. 4 is a front view showing another example of the injection hole shape of the fuel injection valve.

FIG. 5 is a side view showing the shape of fuel spray formed by fuel injection from a fuel injection valve.

FIG. 6 is a plan view showing the shape of fuel spray formed by fuel injection from a fuel injection valve.

FIG. 7 is an enlarged cross-sectional view showing the distribution of fuel in the combustion chamber when conventional fuel injection is executed.

FIG. 8 is a graph showing how the combustion variation rate of the air-fuel mixture changes when the fuel injection timing is changed during fuel injection in the intake stroke.

FIG. 9 is a front view showing another example of the injection hole shape of the fuel injection valve.

FIG. 10 is a front view showing another example of the injection hole shape of the fuel injection valve.

[Explanation of symbols]

1 ... Engine, 2 ... Combustion chamber, 3 ... Cylinder, 4 ... Cylinder block, 5 ... Cylinder head, 6 ... Piston, 6a
... Cavity, 7 ... Intake passage, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 11 ... Fuel injection valve, 12 ...
Spark plug, 13 ... Electronic control device, 14 ... First slit, 15 ... Second slit, 16 ... First fuel spray, 1
7 ... Second fuel spray.

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Claims (11)

[Claims] 1. A fuel injection device for an internal combustion engine in which fuel is directly injected into a combustion chamber where air is sucked from an intake passage, and a fan-shaped first fuel spray that spreads in the width direction of the combustion chamber,
A fuel injection device for an internal combustion engine, comprising: a fuel injection unit that forms a fan-shaped second fuel spray that spreads in the central axis direction of the combustion chamber during the same intake stroke. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection means simultaneously forms the first fuel spray and the second fuel spray. 3. The fuel injection means, when the flow velocity of the air sucked into the combustion chamber from the intake passage is the highest,
The fuel injection device for an internal combustion engine according to claim 2, wherein the first fuel spray and the second fuel spray are simultaneously formed. 4. The internal combustion engine according to claim 1, wherein the fuel injection means forms the second fuel spray on the upstream side of the flow of the intake air with respect to the first fuel spray. Fuel injection device. 5. The fuel injection means comprises a single fuel injection valve for injecting fuel so as to spread in the width direction of the combustion chamber and at the same time for injecting fuel so as to spread in the central axis direction of the combustion chamber. A fuel injection device for an internal combustion engine according to claim 1. 6. The fuel injection valve injects fuel from a first slit extending in a width direction of the combustion chamber and a second slit extending in a central axis direction of the combustion chamber. A fuel injection device for an internal combustion engine as described. 7. The fuel injection device for an internal combustion engine according to claim 6, wherein the second slit is formed on the upstream side of the flow of the intake air with respect to the first slit. 8. The fuel injection device for an internal combustion engine according to claim 6, wherein the first slit and the second slit are formed so as not to overlap each other. 9. The intake passage is connected to the combustion chamber in a state in which the intake passage is branched into a plurality of parts, and is opened / closed so as to establish communication between the intake passage and the combustion chamber. The internal combustion engine according to claim 1, further comprising a plurality of intake valves, wherein the fuel injection means forms the second fuel spray between two adjacent intake valves of the plurality of intake valves. Engine fuel injectors. 10. A fuel injection valve for injecting fuel into a combustion chamber of an internal combustion engine, comprising first and second slits for injecting the fuel,
A fuel injection valve formed so as to extend in directions orthogonal to each other. 11. The fuel injection valve according to claim 10, wherein the first slit and the second slit are formed so as not to overlap with each other.