JP2725624B2 - Fuel injection valve for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve having a two-hole type air-assist adapter used for a fuel injection device of an automobile gasoline engine.

[0002]

2. Description of the Related Art A two-hole injector used in an electronically controlled fuel injector (hereinafter, referred to as an FFI injector) for a four-valve gasoline engine is known (for example, Japanese Utility Model Laid-Open No. 61-198574). Japanese Utility Model Laid-Open No. 59-172267 and Japanese Utility Model Laid-Open No. 61-164470 disclose examples in which an air injection hole is provided in an adapter of an injector. Among these, Japanese Utility Model Application Laid-Open No. 61-198574 discloses an injector body having one fuel injection hole, and a two-hole adapter attached to the tip of the injector body and having two holes and one gathering part where two holes gather. Is disclosed. There, fuel is injected from a fuel injection hole of an injector body into a collecting portion, and the fuel injected into the collecting portion is split into two by a partition provided between the two holes, and is injected through the two holes to correspond to the two holes. Each is injected into two intake ports.
The partition wall provided between the two holes is pointed toward the fuel injection hole to avoid collision with the fuel flow and to reduce the flow resistance. Although the adapter disclosed in Japanese Utility Model Laid-Open No. 59-172267 has an air injection hole, it is a type of adapter that injects fuel in an umbrella shape, and is not a two-hole type adapter targeted by the present invention. Moreover, air is directly applied to the fuel injected from the fuel injection holes. The adapter disclosed in Japanese Utility Model Application Laid-Open No. 61-164470 has a partition having a predetermined area between two holes, but since the tip of the pintle of the needle valve extends just near the partition between the two holes of the adapter. The fuel flowing through the annular gap between the needle valve and the injection hole of the valve body is guided to the tip of the pintle of the needle valve, flows into the two holes, and does not fall into the partition between the two holes. Japanese Utility Model Laid-Open No. 61-164470 also discloses an air injection hole, which is provided at an offset with respect to a plane including the center of the two holes and the axis of the adapter. It is provided so as to introduce air tangentially into the circular cross section of the portion, and contributes to generating a swirl flow in the fuel flow. Therefore, there is no idea that the fuel is atomized by colliding the fuel flow and the air flow with the fuel flow. Known in the prior art are an injector 70 having one fuel injection hole 71, an adapter 72 attached to the tip of the injector 70, and a two-hole 73 formed in the adapter 72, as shown in FIG.
And a gathering part 74 of two holes.

[0003]

The spray characteristics of a two-hole injector are essentially two columnar sprays. Since the spray is columnar, the particle size of the spray is large. As a result, there is a shortage of fuel evaporation time in the intake port and cylinder, insufficient mixing with air in the cylinder, and it is difficult to form a homogeneous mixture, and HC and CO emissions are insufficiently reduced, and There was a problem that the lean limit was not extended. SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve of an internal combustion engine having a two-hole type adapter capable of further atomizing a fuel spray ejected from a fuel injection hole.

[0004]

A fuel injection valve for an internal combustion engine according to the present invention which achieves the above objects is as follows. (1) an injector body having one fuel injection hole;
An adapter mounted on the injector body, wherein the adapter has two holes without step on the inner surface through which the fuel from the fuel injection hole is divided and passes. At a position facing the fuel injection hole between the holes, a columnar and liquid fuel from the fuel injection hole collides to form a fuel collision surface that changes the fuel into a liquid film by the collision, and the adapter has: A fuel injection valve for an internal combustion engine, comprising: an air injection hole for injecting air toward a liquid film-like fuel after a collision. (2) The fuel injection valve for an internal combustion engine according to (1), wherein the air from the air injection hole is jetted downstream from the fuel collision surface.

[0005]

In the fuel injection valve of the internal combustion engine configured as described above, the liquid fuel ejected from the fuel injection hole of the injector body collides with a fuel collision surface located at a position facing the fuel injection hole, and the fuel collision occurs. It is converted into a flow of liquid fuel along the surface. The flow of this fuel is the cross-sectional area of the flow of the fluid x thickness =
According to the continuity theorem of the volume (constant), the thickness decreases as the cross-sectional area increases, and as a result, the columnar and liquid fuel flows as a liquid film. Then, an air flow is ejected from the air injection holes toward the flow of the fuel, and the air collides with the fuel, whereby the fuel is further broken up, and the atomization is further promoted. A mixture of air and atomized fuel is jetted through two holes. The fuel ejected from the two holes is a stream whose atomization has already been greatly promoted, unlike the related art.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a fuel injection valve for an internal combustion engine according to the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 to 3 show a first embodiment of the present invention. In the figure, reference numeral 2 denotes an injector main body, which has one fuel injection hole (fuel measurement injection hole) 4 on the axis of the injector main body 2. A needle valve 6 is movably inserted into the injector body 2 in the direction in which the axis extends. The tip of the needle valve 6 does not pass through the fuel injection hole 4. An air assist adapter 8 (also simply referred to as an adapter) is attached to a tip end of the injector body 2. The air assist adapter 8 has its axis aligned with the axis of the injector main body 2, and has two holes 10, 10 opposed to each other with the air assist adapter axis (also simply referred to as the adapter axis) interposed therebetween.
(There is no step on the inner surface as shown in FIGS. 1 and 5). The two holes 10, 10 are inclined with respect to the axis so as to move away from each other in the direction of fuel injection. The ends of the two holes 10, 10 on the injector body side are open to one collecting part 12, and the other ends are open to the intake ports. The fuel injection hole 4 of the injector body 2 is
The fuel which is opened to the fuel injection hole 12 and is injected into the collecting part 12 from the fuel injection hole 4 is divided into two holes 10 and 10 after flying the collecting part 12 and is injected into the intake port through the two holes 10 and 10. You. Up to the above structure, a conventionally known structure can be said.

The air assist adapter 8 has two holes 10,
Between 10, a fuel collision plane 14 is formed at a position facing the fuel injection hole 4 of the injector body 2 as a fuel collision plane composed of a plane orthogonal to the axis of the air assist adapter.
The fuel ejected from the fuel injection hole 4 and flying in the collecting section 12 toward the fuel collision plane 14 is columnar and liquid, and the liquid fluid collides at right angles to the fuel collision plane 14 to change the direction of the flow by air assist. Turning to a flow flowing along the fuel impingement plane 14, which extends radially outward and perpendicular to the adapter axis, is the solid powder flow of the liquid flow. One of the characteristics, the fuel impingement plane 14 is provided with a minimal area required to convert to a radially outward flow. In the case of this embodiment, the relationship between the diameter d of the fuel injection hole 4 and the effective equivalent diameter D of the fuel collision plane 14 is D> d. The gathering portion 12 has a cross section extending in a plane perpendicular to the axis of the air assist adapter, an ellipse extending between the two holes 10 and 10 (a shape in which semicircular portions at both ends are connected by a parallel portion in the middle), an ellipse, Consists of any of the circles. The fuel collision plane 14 is a part of a plane that defines the collecting section 12.

[0008] Air injection holes 18, 18 are provided in a wall 16 which defines the gathering portion 12 from the periphery. The hole axes of the air injection holes 18, 18 are arranged in a plane including the axis of the two holes 10, 10 and the axis of the air assist adapter. The axis of the air injection holes 18 is located closer to the injector body 2 than a plane including the fuel collision plane 14 and orthogonal to the axis of the air assist adapter. 1 is the axial distance between the axis of the air injection holes 18, 18 and the fuel collision plane 14. The air holes 18, 18
The injector main body 2 extends obliquely with respect to a plane including the fuel collision surface 14 and orthogonal to the axis of the air assist adapter.
Direction. Tilt angle θ of air injection holes 18, 18
In the relationship with the distance 1, the intersection of the extension of the axis of the air injection holes 18, 18 with the plane including the fuel collision surface 14 exists within the opening end of the two holes 10, 10 to the collecting portion 12. The angle is set so that Thus, the inclination angle θ of the air injection holes 18, 18 is such that the air jet ejected from the air injection holes 18, 18 is
The angle at which the fuel flows along the fuel collision plane 14 toward the radially outward direction and the leading end of which is in a liquid film split state collides from the upper surface in the drawing. The collecting portion 12 also functions as a space for allowing atomization of the fuel by collision of air with the liquid film split fuel, and it is preferable that the volume of this space be as small as possible in order to prevent fuel transport delay. For this reason, it is desirable to set the axial length L of the collecting part 12, that is, the distance L between the end face of the injector body 2 and the fuel collision plane 14, to be small. Distance L
Is a value to be determined from the velocity of the fuel columnar jet and the state of liquid film splitting.

Reference numeral 20 denotes a cylinder head or an intake manifold to which an injector 22 composed of the air assist adapter 8 and the injector body 2 is fixedly attached. Reference numeral 42 denotes an air introduction passage, and reference numeral 24 denotes an annular air passage for guiding the air from the air introduction passage 42 to each of the air injection holes 18. The air introduction passage 42 is connected to an air source (not shown). 26 is an O-ring. FIG. 3 shows an injector 22 to which the air assist adapter 8 having the above-mentioned structure is mounted, of which the structure on the injector body 2 side is conventionally known.
28 is a magnet for driving the needle valve 6 in the axial direction, and 30 is a fuel filter. FIG. 4 shows a state in which the injector 22 is mounted on a four-valve gasoline engine. The injector 22 is installed just upstream of the partition wall 36 of the two intake ports 32 and 34, and supplies fuel to the two intake ports 32 and 34. Inject. 38 and 40 are exhaust ports.

Next, the operation of the first embodiment will be described. The fuel ejected from the fuel injection hole 4 of the injector body 2 flies in a collecting column 12 in the form of a liquid column, and collides with a fuel collision plane 14 as a fuel collision surface. In the fuel collision plane 14, the flow direction of the fuel is changed in a direction orthogonal to the axis of the air assist adapter in a direction radially outward,
It flows like a film along the fuel collision plane 14. The thickness of the film of the liquid fuel becomes thinner toward the outside in the radial direction, and eventually splits and flies outward in the radial direction, thereby promoting the formation of droplets and atomization. Air injection holes from the upper surface to this liquid film split fuel flow
The air jets from 18 and 18 obliquely collide with the air flow and the fuel flow to further atomize the fuel and promote atomization. The mixture of fuel and air whose atomization has been promoted is 2
Ejected through holes 10,10. The flow that is gushing out of the two holes 10, 10 has already been atomized,
It is not a pure liquid column like the conventional one.

Second Embodiment FIG. 5 shows a second embodiment of the present invention. In the figure, 51
Indicates an injector body. Injector body 51
A fuel injection hole 52 for measuring fuel from a fuel supply passage (not shown) is provided at a tip end of the ball 53.
And a seat portion 54 having a curved inner wall. An adapter 55 is attached downstream of the fuel injection hole 52,
The adapter 55 is provided with two holes 56 that diverge fuel from the fuel injection hole 52 in a predetermined direction and inject the fuel from an outlet. The two holes 56, 56 are inclined with respect to the axis so as to move away from each other as they go downstream in the fuel injection direction. Between the two holes 56, 56 and the fuel injection holes 52, there is provided a collecting portion 57 that joins the two holes 56, 56. 2 holes 56, 56
Are branched by a fuel collision portion 58 having a V-shaped cross section which tapers toward the upstream so that the axes A _{1 and} A ₂ have a predetermined opening angle. In the present embodiment, the center position of the fuel injection hole 52 and the branch position of the center of the passage of the two holes 56, 56 coincide with the injection valve shaft 59, and the extension of the fuel injection hole 52
It is set so as to pass through the upstream end 58a of 58. Upstream end 58
“a” has an arc-shaped cross section and forms a fuel collision surface facing the fuel injection hole 52. On the outer circumference of the adapter 55,
Air delivery 60 is located. An O-ring 62 is mounted in a groove 61 formed on the inner peripheral surface of the upper end of the air delivery 60, and the O-ring 62 seals a gap between the air delivery 60 and the injector body 51. On the other hand, a seal ring 63 is provided on the inner peripheral surface of the lower end of the air delivery 60.
The seal ring 63 seals the gap between the outer peripheral surface of the adapter 55 and the inner peripheral surface of the air delivery 60. An air introduction pipe 68 that allows air to flow into an annular air passage 64 formed between the air delivery 60, the injector body 51, and the adapter 55 is attached to an outer peripheral surface of the air delivery 60. Adapter 55 has 2
Air injection holes 65, 65 are provided which extend diagonally in a direction approaching the injector body 51 as the distance from the holes 56, 56 increases, and eject air toward the vicinity of the upstream end 58a of the fuel collision portion 58. The axes 66a, 66a of the air injection holes 65, 65
58 is located downstream of the upstream end 58a. That is,
In the case of this embodiment, the air from the air injection holes 65, 65 is jetted slightly downstream from the upstream end of the fuel collision portion 58. The ring-shaped member located at the outer periphery of the lower end of the air delivery 60 is a holding member for fixing the injection valve.
67.

Next, the operation of the second embodiment will be described. The fuel ejected from the fuel injection holes 52 of the injector body 51 flies in a collecting column 57 in the form of a liquid column, and collides with an upstream end 58a having an arc-shaped cross section of the fuel collision unit 58 that tapers toward the upstream. . As a result, the fuel is formed into a liquid film spray. The air jets from the air injection holes 65, 65 are obliquely applied to the liquid film spray flowing through the two holes 56, 56, and the fuel is further atomized by the collision of the air flow and the fuel flow, and the atomization is promoted. Is done. The mixed flow of fuel and air whose atomization has been promoted is ejected to the combustion chamber side (not shown) through the two holes 56. In addition, when the air injection holes are arranged upstream of the upstream end of the fuel collision section, the amount of spray that stays in the collection section due to the turbulence of air in the collection section increases, and the amount of fuel adhering to the inner wall of the adapter collection section slightly increases. It becomes a tendency. Therefore, in the present embodiment, the opening of the air injection hole 65 is provided downstream of the top of the fuel collision portion 58,
The amount of fuel adhering to the inner wall of the adapter assembly is reduced.

[0013]

According to the fuel injection valve of the internal combustion engine of the first and second aspects, the following effects can be obtained. (A) First, atomization of fuel is greatly improved because the air collision effect is applied to the liquid film splitting effect due to the collision of the spray with the fuel collision surface. Even if air is directly impinged on a conventional columnar jet, the atomization efficiency is poor and a large amount of airflow energy is required. In the present invention, however, the airflow is applied to atomization due to liquid film splitting of the jet. Since the efficiency of atomization is increased, the amount of air for air assist can be minimized. (B) Even when applied to an intake port having a complicated structure such as a four-valve engine, fuel wall adhesion can be effectively suppressed, and drivability, fuel efficiency, smoldering, and the like are improved. (C) Since the width of the fuel particle size distribution is small and the particle sizes are uniform, a homogeneous mixture can be formed in the engine cylinder. (D) To supply air into the cylinder by premixing of air and fuel,
The function of promoting mixing such as swirl in the cylinder becomes unnecessary. (E) The tip of the injector body is cooled by air flowing through the air injection holes formed in the adapter, and the restartability of the fuel injection valve at high temperatures can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of the vicinity of an adapter of a fuel injection valve of an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an overall sectional view of an injector equipped with the air assist adapter of FIG. 1;

FIG. 4 is a plan view of a four-valve engine equipped with the injector of FIG. 3;

FIG. 5 is a sectional view of the vicinity of an adapter of a fuel injection valve of an internal combustion engine according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing an example of a conventional fuel injection valve.

[Explanation of symbols]

 2,51 Injector body 4,52 Fuel injection hole 8,55 Air assist adapter (adapter) 10,56 2 hole 12,57 Assembly part 14,58a Fuel collision surface 16 Wall 18,65 Air injection hole

Continuation of the front page (56) References Japanese Utility Model Showa 61-188796 (JP, U) Japanese Utility Model Showa 58-52375 (JP, U) Japanese Utility Model Showa 61-1114071 (JP, U)

Claims (2)

(57) [Claims] 1. An injector body having one fuel injection hole, an adapter attached to the injector body,
Wherein the adapter is opposed to the fuel injection hole between the two holes in a fuel injection valve of an internal combustion engine having two holes with no steps on an inner surface through which fuel from the fuel injection hole is separately passed. At a position where a columnar and liquid fuel from the fuel injection hole collides to form a fuel collision surface that changes the fuel into a liquid film by the collision, and the adapter includes:
A fuel injection valve for an internal combustion engine, comprising: an air injection hole for injecting air toward a liquid film-like fuel after a collision. 2. The fuel injection valve for an internal combustion engine according to claim 1, wherein the air from the air injection hole is jetted downstream from the fuel collision surface.