JPH0988609A - Fuel diffusion structure of fuel injection device - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a fuel diffusion structure of a fuel injection device capable of uniformly diffusing fuel spray in a combustion chamber even with a single injection hole configuration. A cylindrical mesh member 15 is fixed to a cylinder head 1 so as to surround a nozzle hole 14α of a nozzle 14. The disc-shaped collision plate 16 is provided so as to seal the lower opening of the mesh member 15. Therefore, the collision plate 16 is arranged so as to face the injection hole 14α of the nozzle 14, and the facing surface forms the collision surface 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel diffusion structure applied to a fuel injection device for a direct injection diesel engine, for example.

[0002]

2. Description of the Related Art For example, a diesel engine is designed so that only air is sucked into a cylinder and is compressed to inject fuel to a high temperature place. Therefore,
The air (oxygen) utilization rate during combustion is lower than that of a gasoline engine that creates a mixture in advance, and the emission of black smoke is a problem. In order to reduce this emission, it is necessary to sufficiently diffuse the fuel spray in the combustion chamber and to sufficiently mix the air and the fuel spray.

Here, when the diesel engine is of the auxiliary combustion chamber type, compressed air flows into the auxiliary combustion chamber at a high speed at the end of the compression process, resulting in severe air turbulence. For this reason, mixing air and fuel spray is less of a problem. However, in the case of the direct injection type, although there is a swirl of the air, there is a problem in that the air and the fuel spray are not sufficiently mixed with that alone.

In order to solve such a problem, for example,
JP-A-4-124443 and JP-A-4-29862.
There are techniques disclosed in Japanese Patent Laid-Open No. 8 and Japanese Patent Laid-Open No. 6-17722.

In the techniques disclosed in JP-A-4-124443 and JP-A-4-298628, the collision plate is arranged to face the injection hole. Then, the fuel spray collides with the collision plate and is reflected to try to diffuse into the combustion chamber.

In the technique disclosed in Japanese Patent Laid-Open No. 6-17722, a mesh member is arranged instead of the collision plate.

[0007]

However, Japanese Unexamined Patent Publication No.
In the technologies of 124443 and Japanese Patent Laid-Open No. 4-298628, the diffusion of the fuel spray is limited to the entire circumferential direction of the collision plate, and it cannot be said that the fuel spray is uniformly diffused in the combustion chamber.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 6-17722, the mesh member only diffuses the fuel spray in the injection direction defined by the injection holes. Therefore, for example, when the nozzle has a single injection hole structure, the fuel spray cannot be uniformly diffused in the combustion chamber. Therefore, in this publication, in order to make up for this drawback, the multi-injection hole configuration of the nozzle is an indispensable condition, and it is necessary to control the accuracy of each injection hole and the machining of the nozzle is troublesome.

The present invention has been made by paying attention to the problems existing in the above-mentioned prior art, and the object thereof is, for example, to uniformly diffuse the fuel spray in the combustion chamber even with a single injection hole structure. An object of the present invention is to provide a fuel diffusion structure for an obtained fuel injection device.

[0010]

In order to achieve the above object, in the invention of claim 1, a fuel diffusion structure is provided in which a collision surface is arranged to face the injection hole and a mesh member is arranged around the collision surface. Is.

According to a second aspect of the present invention, the fuel injection device is applied to a reciprocating engine, and the combustion chamber is recessed in a surface of the piston facing the cylinder head.

In the invention of claim 3, the collision surface is a surface of the collision plate facing the injection hole, and the collision plate and the mesh member are fixed to the cylinder head side. In the invention of claim 4, the injection hole is a single injection hole.

(Operation) In the invention of claim 1 having the above structure, the fuel is injected by the fuel injection device toward the combustion chamber through the injection hole of the nozzle. This injected fuel spray is diffused in the entire circumferential direction of the collision surface, which is arranged so as to face the injection hole. Then, the fuel spray diffused by the collision surface is diffused again by the mesh member. In this way, by diffusing the injected fuel spray in two stages, the degree of diffusion of the fuel spray in the combustion chamber becomes uniform.

According to the second aspect of the present invention, the fuel is directly injected into the combustion chamber formed in the piston. In such a direct injection type reciprocating engine, the air and the fuel spray are not sufficiently mixed. Therefore, it is particularly effective to apply the invention of claim 1 to this type of engine.

In the third aspect of the invention, the collision plate and the mesh member are fixed to the cylinder head side. Therefore, regardless of the stroke position of the piston, the positional relationship between the collision plate and the mesh member and the nozzle does not change. Therefore, for example, even when the fuel injection timing is changed, the diffusion action of the collision plate and the mesh member does not change.

According to the fourth aspect of the present invention, the nozzle having the single injection hole configuration facilitates the accuracy control of the injection holes as compared with the multiple injection hole configuration. Therefore, the same nozzle can be easily processed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The fuel diffusion structure of the present invention will be described below.
First to fifth embodiment of a fuel injection device applied to a direct injection diesel engine as a reciprocating engine
An embodiment will be described. In addition, in 2nd-5th embodiment, the same number is attached | subjected to the same member as 1st Embodiment.

(First Embodiment) FIG. 1 is an enlarged partial sectional view showing a cylinder head 1 to a cylinder block 2 of a direct injection diesel engine. In the figure, 3 indicates a cylinder formed in the cylinder block 2. The piston 4 is housed in the cylinder 3. The combustion chamber 5 is recessed in the center of the upper surface of the piston 4, which is the surface facing the cylinder head 1. Further, in the figure, 6 indicates an intake port, 7 indicates an intake system of an intake valve, and 8
Is an exhaust valve, and 9 is an exhaust system of an exhaust port.

The insertion hole 10 is formed so as to penetrate above the center of the combustion chamber 5 in the cylinder head 1. The fuel injection valve 12 constituting the fuel injection device 11 has an insertion hole 10
Is inserted and arranged, and is engaged with a step portion 10α formed at an intermediate position of the insertion hole 10 via a seal member 13.
The nozzle 14 of the fuel injection valve 12 extends to a small diameter portion of the insertion hole 10 below the step portion 10α and faces the combustion chamber 5 with its tip end surface. Further, one injection hole 14α is formed in the tip end surface of the nozzle 14 and defines the injection direction of the fuel F in the central direction of the combustion chamber 5.

In the present embodiment, the fuel injection device 11 is provided with a fuel diffusion structure so that the injected fuel spray F is uniformly diffused in the combustion chamber 5. That is, as shown in FIGS. 1 and 2A and 2B, a cylindrical mesh member 15 is formed.
Is made of a heat resistant material such as stainless steel. The mesh member 15 is fixed to the cylinder head 1 so as to surround the opening of the insertion hole 10 on the combustion chamber 5 side. The disc-shaped collision plate 16 is also made of a heat-resistant material. The collision plate 16 is the mesh member 1
5 is provided so as to seal the lower opening. Therefore, the collision plate 16 is arranged so as to face the injection hole 14α of the nozzle 14, and the facing surface forms the collision surface 16α of the present embodiment. Each mesh hole 15α forming the mesh member 15 has a quadrangular shape as shown in an enlarged view in FIG. 2 (b).

Next, the operation of the present embodiment will be described. Now, as shown in FIG. 1, when the piston 4 reaches the vicinity of the top dead center, the fuel injection device 11 injects the fuel F into the combustion chamber 5 via the fuel injection valve 12. The injected fuel spray F collides with the collision surface 16α of the collision plate 16 and is reflected,
Most of them are diffused in the entire circumferential direction of the collision plate 16. The fuel spray F diffused by the collision plate 16 is
6 toward the mesh member 15 disposed around the periphery of the No. 6 and diffused again by the mesh member 15. The diffusion of the fuel spray F by the mesh member 15 causes each fuel particle to pass through the mesh hole 15α as it is, or the mesh hole 15α.
This is done by grazing the meat portion between α and passing it, colliding with the meat portion and returning to the inside of the cylindrical space, colliding with other fuel particles and disturbing the scattering direction.

If the cross-sectional area of passage of the mesh holes 15α is too large, most of the fuel spray F will pass through the mesh holes 15α and the diffusion action will be weakened. On the contrary, if the cross-sectional area of passage is too small, most of the fuel spray F cannot pass, and the diffusion action is weakened. Therefore, in the present embodiment, the passage cross-sectional area of the mesh hole 15α is determined in accordance with the particle size distribution of the fuel particles in the cylindrical space of the mesh member 15 so as to achieve a favorable diffusion action.

The present embodiment having the above-mentioned structure has the following effects. (1) The collision plate 16 and the mesh member 15 are adapted to diffuse the injected fuel spray F in two stages. Therefore, the degree of diffusion of the fuel spray F in the combustion chamber 5 becomes uniform. Therefore, the air and the fuel spray F are sufficiently mixed, and the emission can be reduced.

(2) The present embodiment is embodied in a direct injection diesel engine. That is,
Embodying the present invention in an engine of this type in which the diffusion action of the fuel spray F can be expected only to the extent of swirl is particularly effective for achieving the effect of the above (1).

(3) The collision plate 16 and the mesh member 15 are fixed to the cylinder head 1 side. Therefore, the positional relationship between the collision plate 16 and the mesh member 15 and the nozzle 14 is constant regardless of the stroke position of the piston 4.
Therefore, even when the fuel injection timing is changed, the diffusion effect of the fuel spray F by the collision plate 16 and the mesh member 15 does not change.

(4) According to the above (1), the single injection hole structure 14
Even with α, a sufficient diffusion effect of the fuel spray F is obtained. The nozzle 14 having the single injection hole configuration 14α is easier to control the accuracy of the injection hole 14α during processing than the nozzle 14 having the multiple injection hole configuration, and is suitable for mass production of the nozzle 14 and eventually the engine.

(5) By arranging the collision plate 16 and the mesh member 15, the effect of reducing the kinetic energy of the fuel spray F applied at the time of injection is reduced as compared with the technique of the conventional publication having only one of them. Is large. Therefore, for example, even if the fuel injection amount increases at the time of high engine load, the amount of the fuel spray F reaching the wall surface of the combustion chamber 5 and adhering to the wall surface before the ignition can be reduced. That is, the amount of fuel particles drifting in the combustion chamber 5 at the time of ignition can be increased, and the above-mentioned diffusion effect can be enhanced.

(Second Embodiment) FIG. 3 shows a second embodiment. In the present embodiment, a plurality of (two) injection holes 17α having different fuel injection directions are provided in the nozzle 17. In the present embodiment, the nozzle 17 has a multi-injection structure, so that the fuel spray F from the injection stage.
And the fuel spray F is sufficiently mixed.

(Third Embodiment) FIG. 4 shows a third embodiment. In the present embodiment, the mesh member 18
The method of fixing is different from that of the first embodiment. That is,
The mesh member 18 extended upward as compared with the mesh member 15 of the first embodiment is inserted and arranged in the small diameter portion of the insertion hole 10 with the extended portion. Further, the mesh member 18 is sandwiched and fixed by the fuel injection valve 12 and the seal member 13 with a flange portion 18α formed at the upper opening edge of the extended portion thereof. Therefore, in this embodiment, the mesh member 18 is securely fixed.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment. In this embodiment, the collision plate 19 and the mesh member 20 are fixed to the piston 4 side. That is, the collision plate 19 has the leg portion 19α attached to the back side thereof.
And is fixed to the inner bottom surface of the combustion chamber 5. The cylindrical mesh member 20 is fixed to the outer peripheral edge of the upper surface of the collision plate 19.

(Fifth Embodiment) FIG. 6 shows a fifth embodiment. In this embodiment, the apex of the convex portion 21 formed on the bottom surface of the combustion chamber 5 is formed into a flat surface, and the flat surface is used as the collision surface 22. In the present embodiment, the number of parts (collision plates) can be reduced by providing the collision surface 22 using the shape of the combustion chamber 5.

The following embodiments can be carried out without departing from the spirit of the present invention. (1) To be embodied in a secondary combustion chamber type diesel engine. Further, as a reciprocating engine other than a diesel engine, for example, a direct injection type gasoline engine should be embodied. (2) The shape of the mesh holes 15α was quadrangular.
However, the shape is not limited to this, and other polygons such as a triangle and a pentagon, and a circle such as a perfect circle and an ellipse. Alternatively, combine multiple types of these. (3) Arrange the mesh members 15, 18, and 20 in double or more. By doing so, the diffusion effect of the fuel spray F is further enhanced. (4) The mesh hole 15α located in the direction in which the amount of reflection of the fuel spray F is large due to the collision surface 16α is made small, and the mesh hole 15α in the direction in which the amount of reflection is small is made large,
To make the amount of fuel spray passed through each mesh hole 15α uniform. (5) The mesh members 15, 18 and 20 are fixed to the cylinder head 1 side, and the collision plates 16 and 19 are fixed to the piston 4 side. The reverse configuration may be used. (6) In the fifth embodiment, the collision surface 22 is provided with a ceramic coating or the like to make it difficult for the fuel spray F to adhere to the surface 22. The same coating may be applied to the collision surface 16α of the first to fourth embodiments.

The technical idea that can be understood from the above embodiment will be described. The nozzle 17 has a plurality of injection holes 17α.
The fuel diffusion structure according to claim 1, wherein the fuel diffusion structure is provided.

In this way, the diffusion effect of the fuel spray F can be enhanced from the injection stage.

[0035]

According to the invention of claim 1 having the above-mentioned structure, the fuel spray can be uniformly diffused in the combustion chamber. Therefore, there is a good mixture of air and fuel spray,
Emissions can be reduced.

According to the invention of claim 2, the application of the invention of claim 1 to the direct injection type reciprocating engine is particularly effective for exerting its effect. According to the invention of claim 3, the diffusing action by the collision plate and the mesh member is stably exhibited.

According to the invention of claim 4, the nozzle can be easily processed, which is suitable for mass production.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of a direct injection diesel engine.

2A is a sectional view taken along the line AA of FIG. 1, and FIG. 2B is an enlarged view of a mesh member.

FIG. 3 is an enlarged sectional view of an essential part showing a second embodiment.

FIG. 4 is an enlarged cross-sectional view of an essential part showing a third embodiment.

FIG. 5 is an enlarged cross-sectional view of an essential part showing a fourth embodiment.

FIG. 6 is an enlarged cross-sectional view of an essential part showing a fifth embodiment.

[Explanation of symbols]

5 ... Combustion chamber, 11 ... Fuel injection device, 14 ... Nozzle, 14
α ... injection hole, 15 ... mesh member, 16α ... collision surface.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuo Sato 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (4)

[Claims] 1. A fuel injection device having a nozzle facing a combustion chamber through an injection hole, wherein a collision surface is arranged to face the injection hole, and a mesh member is arranged around the collision surface. 2. The fuel diffusion structure according to claim 1, wherein the fuel injection device is applied to a reciprocating engine, and the combustion chamber is recessed in a surface of the piston facing the cylinder head. 3. The fuel diffusion structure according to claim 2, wherein the collision surface is a surface of the collision plate facing the injection hole, and the collision plate and the mesh member are fixed to the cylinder head side. 4. The fuel diffusion structure according to claim 1, wherein the injection hole is a single injection hole.