JP2000303934A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inject fuel in a specified atomizing shape by decreasing a difference in a velocity of flow between fuel flowing the inner angle side of the side edge part on the inlet side of a nozzle and fuel flowing the outer angle side thereof. SOLUTION: This device comprises a seat part 24 on which a valve 19 seats; a fuel injection chamber 32 situated downstream from the seat part 24 and having a bottom formed by a spherical recessed surface 31; and a nozzle 33 extending in an inclining state through the wall part of the spherical recessed surface 31 of the fuel injection chamber 32. A chamfered surface 33a gently continued to a spherical recessed surface 31 is formed at the edge part on the inlet side of the nozzle 33. A chamfering amount of the inner angle side of the chamfered surface 33a is increased to a value higher than a chamfering amount on the outer angle side. This constitution, since a chamfering amount of the chamfered surface 33a is large on the inner angle side of the edge part on the inlet side of the nozzle 33, causes contraction to hardly occur to a flow of fuel and prevents the lowering of a velocity of flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle of a fuel injection valve used in a direct injection type gasoline engine for directly injecting fuel into a cylinder of an internal combustion engine.

[0002]

2. Description of the Related Art A conventional fuel injection nozzle is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-296531.
FIG. 10 is a cross-sectional view of the fuel injection nozzle disclosed in the publication. In FIG. 10, a fuel injection nozzle 120 has a seat portion 124 on which a valve 119 is seated, a fuel injection chamber 132 provided downstream of the seat portion 124 and having a bottom surface formed by a spherical concave surface 131, An injection hole 133 penetrating the wall of the spherical concave surface 131 of the chamber 132 in an inclined manner. Although not shown, the inlet side edge of the injection hole 133 is formed in an R shape (rounded shape). The R shape is not clearly described in the publication, but is presumed to be formed with a constant chamfer amount in the circumferential direction.

According to the fuel injection nozzle 120, the fuel passes through the seat portion 124 by opening the valve 119, passes through the fuel injection chamber 132, passes through the injection hole 133, and has a substantially conical spray shape (a two-dot chain line a in FIG. 10). .). The fuel injection nozzle 120 directly injects fuel into a cylinder in a direct injection gasoline engine.

[0004]

In the conventional fuel injection nozzle 120, although the injection hole 133 is inclined with respect to the fuel injection chamber 132, the R-shape of the inlet-side edge of the injection hole 133 is provided. Is constant in the circumferential direction, as is well known, a phenomenon similar to that in the case of a curved pipe occurs in the flow of fuel. That is, on the inner corner side of the inlet-side edge of the injection hole 133, the flow velocity becomes slow due to the contraction of the fuel flow, and on the outer corner side, the flow velocity becomes high because the contraction of the fuel flow hardly occurs. Phenomenon occurs. For this reason, a considerable difference occurs in the flow velocity between the fuel flowing on the inner corner side of the inlet-side end edge of the injection hole 133 and the fuel flowing on the outer angle side, and the spray shape a of the fuel injected from the injection hole 133 However, there was a problem that it was difficult to form a prescribed cone.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to solve the problem that the fuel flowing on the inner angle side of the inlet side edge of the injection hole and the outer angle side thereof. By reducing the difference in flow velocity with the fuel flowing through the
An object of the present invention is to provide a fuel injection nozzle capable of injecting fuel into a prescribed spray shape.

[0006]

According to a first aspect of the present invention, there is provided a fuel injection chamber having a seat portion on which a valve is seated, and a bottom surface provided downstream of the seat portion and formed by a spherical concave surface. And an injection hole that penetrates the wall of the spherical concave surface of the fuel injection chamber in an inclined manner, and has a chamfered surface that is smoothly continuous with the spherical concave surface at an inlet-side edge of the injection hole, This is a fuel injection nozzle in which the chamfer amount on the inner angle side of the chamfer surface is larger than the chamfer amount on the outer angle side. With such a configuration, since the chamfered surface of the chamfered surface is large on the inner corner side of the inlet-side end edge of the injection hole, the flow of the fuel is less likely to be contracted, and the decrease in the flow velocity is reduced. Thereby, the difference in flow velocity between the fuel flowing on the inner corner side of the inlet-side edge of the injection hole and the fuel flowing on the outer corner side thereof can be reduced, so that the fuel can be injected in a prescribed spray shape.

According to a second aspect of the present invention, there is provided a fuel injection nozzle according to the first aspect, wherein a valve seat having a seat portion is joined to a nozzle tip having a fuel injection chamber and an injection hole. With this configuration, the chamfered surface of the inlet-side edge of the nozzle hole can be easily and accurately processed by the end face processing in the nozzle tip before joining with the valve seat. For example, when the seat portion, the fuel injection chamber, and the injection hole are integrally provided, the chamfered surface of the inlet side edge of the injection hole must be processed through a thin and deep seat portion. However, according to the second aspect of the present invention, the problem is improved.
In addition, before joining, the characteristics of the valve seat and the nozzle tip, for example, the oil-tightness of the seat portion, the spraying characteristics of the injection holes, etc. can be independently evaluated. , It is possible to diversify the risks.

A third aspect of the present invention is the fuel injection nozzle according to the second aspect, wherein the nozzle tip is formed by metal injection molding or press molding. With this configuration, when the nozzle tip is formed by metal injection molding or press molding, the injection hole is formed with reference to the fuel injection chamber, so that the positional accuracy of the injection hole can be improved. If the valve seat is also made of metal, the valve seat and the nozzle tip can be easily joined by welding.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment will be described with reference to FIGS. First, the overall configuration of the fuel injection valve will be described based on the cross-sectional view of FIG. The fuel injection valve according to the present embodiment is used for a direct injection gasoline engine.

In the fuel injection valve 1, a solenoid coil 4 wound around a bobbin 3 is provided inside a substantially cylindrical housing 2. Inside the bobbin 3, a hollow shaft-shaped core 5 also serving as a fuel inflow pipe is provided. At the upper end of the core 5, a fuel connector 6 connected to a fuel pipe (not shown) is provided.
A strainer 7 is mounted inside the fuel connector 6.

An electrical connector 9 formed by resin molding is provided substantially at the center of the core 5. The electrical connector 9 is provided with a terminal 10. A power supply connector of an electronic control unit (not shown) is connected to the electric connector 9, and power is supplied to the solenoid coil 4 through a terminal 10. A valve spring 12 is inserted into the core 5 and then a spring pin 13 is inserted.
Is installed. The valve spring 12 urges the armature 14 disposed below the core 5 downward.

A substantially cylindrical body 16 is connected to the lower edge of the housing 2. The upper end of the body 16 is connected to the core 5 via a ring 17 located inside the bobbin 3. A fuel injection nozzle 20 is connected to a lower portion of the body 16 via a spacer 18 having a substantially C-shaped plate shape. A needle valve 19 is provided in the fuel injection nozzle 20 so as to be vertically movable, that is, axially movable.

An upper end of the needle valve 19 is connected to the armature 14 through a spacer 18. The needle valve 19 is provided with a stopper 19a located near and below the spacer 18. When the solenoid coil 4 is energized, the armature 14 is attracted against the urging force of the valve spring 12, and the needle valve 19 is slid until the stopper portion 19a comes into contact with the spacer 18, so that a seat portion described later is opened. .

Next, the fuel injection nozzle 20 will be described with reference to a partially enlarged view of FIG. The fuel injection nozzle 20 includes a substantially cylindrical valve seat 22 as a main body thereof, and a substantially flat nozzle tip 30 joined to a lower end surface thereof. A swirler 40 provided inside the valve seat 22 is provided. Have.

The valve seat 22 will be described. The valve seat 22 has a valve hole 23 and a seat portion 24. The valve hole 23 is formed in a substantially cylindrical shape with a bottom. A swirler mounting surface 23a for reducing the inner diameter is formed substantially at the lower center of the valve hole 23. The seat portion 24 is formed in a substantially tapered hole shape on the bottom surface of the valve hole 23, and is opened and closed by the lower end of the needle valve 19.

The valve seat 22 is formed by forging (for example,
It is made of metal formed by machining such as cold forging) and / or cutting. As the metal material of the valve seat 22, for example, a rod of SUS440C is used. Further, the seat portion 24 is provided on the valve seat 22.
Is subjected to quenching to improve the wear resistance. The upper end of the valve seat 22 is attached to the body 16 (see FIG. 1).

Next, the nozzle tip 30 will be described. FIG.
FIG. 5 is a sectional view of the nozzle tip 30, and FIG.
6 is a bottom view of the nozzle tip 30 shown in FIG. The nozzle tip 30 is connected to the valve seat 22.
(See FIG. 1), which is joined to the lower end
The fuel injection chamber 32 includes a fuel injection chamber 32 having a bottom surface formed by 1 and a circular injection hole 33 penetrating the wall of the spherical concave surface 31 of the fuel injection chamber 32 in an inclined manner. The fuel injection chamber 32 is located on the same axis as the valve hole 23 of the valve seat 22.

An R-shaped chamfered surface 33a having a radius r is formed on the inlet-side edge of the injection hole 33 and smoothly continues to the spherical concave surface 31. In the chamfered surface 33a, the chamfer amount on the inner corner side (left side in FIG. 4) is set to be larger than the chamfer amount on the outer corner side (right side in FIG. 4). That is, the radius r of the R shape on the inner angle side is set to be larger than the radius r of the R shape on the outer angle side. Note that the radius r from the outer-side R shape to the inner-side R shape is
Is gradually changing. For example, the diameter of the injection hole 33 is φ
In the case of 0.5 mm, the radius r of the R shape on the inner corner side is 0.5
mm, the radius r of the R shape on the outer corner side is 0.1 mm. It should be noted that a straight chamfered surface may be used instead of the R-shaped chamfered surface 33a.

On the lower surface of the nozzle tip 30,
A plane portion 35 that is perpendicular to the injection hole 33 is formed. Thereby, the outlet side edge of the injection hole 33 is formed in a right-angled edge shape. Further, both end portions 30a located on both sides of the flat portion 35 of the nozzle tip 30 are thinned (see FIG. 4).

The nozzle tip 30 is made of metal formed by metal injection molding (also referred to as MIM molding). At the same time as the molding, the fuel injection chamber 32, the injection hole 33, and the plane portion 35 are formed. As is well known, the molding process of metal injection molding for molding the nozzle tip 30 is a kneading process of kneading a fine powder (also referred to as powder) of a metal material and a binder, and molding the kneaded material with an injection molding machine. A degreaser, a liquid degreasing step of removing the binder from the molded body with a solvent in a degreasing furnace, and a sintering step of sintering the degreased molded body in a sintering furnace. As a metal material of the nozzle tip 30, for example, fine powder of SUS316 is used. After forming the nozzle tip 30, the chamfered surface 33a is formed by end face processing by cutting.

The nozzle tip 30 is joined to the valve seat 22 as follows. That is, as shown in FIG. 2, the joining surface (the upper end surface in the figure) of the nozzle tip 30 is brought into contact with the front end surface (the lower end surface in the figure) of the valve seat 22 in a face contact manner. The valve seat 22 and the nozzle tip 30 are joined by welding the peripheral portions of the mutual butted surfaces by laser welding or the like (the reference numeral 21 is attached in the figure). In addition, valve seat 2
After joining the nozzle tip 2 to the nozzle tip 30, the sheet portion 24 is polished to complete the fuel injection nozzle 20.

Next, the swirler 40 will be described. In FIG. 2, the swirler 40 has a substantially cylindrical shape, and has an upper outer peripheral surface as a large-diameter surface and a lower outer peripheral surface as a small-diameter surface. The large diameter surface of the swirler 40 is fixed to the mounting surface 23a of the valve hole 23 by press fitting. Thereby, the fuel introduction chamber 42 around the small diameter surface of the swirler 40 is formed.
Are formed.

The lower end of the needle valve 19 is inserted into the hollow hole 40a of the swirler 40 so as to be slidable in the vertical direction. A sliding guide surface 43 for reducing the inner diameter is formed below the hollow hole 40a of the swirler 40, and the needle valve 19 is slidably guided.

At the center of the swirler 40, there is formed a communication hole 44 for communicating the space above the sliding guide surface 43 in the hollow hole 40a with the fuel introduction chamber 42. An annular swirl chamber 46 facing the seat portion 24 of the valve seat 22 is formed in an inner peripheral portion of a lower end surface of the swirler 40. FIG. 3 shows III-I of FIG.
A sectional view taken along line II is shown. In FIG. 3, a swirl hole 45 extending in a tangential direction of the swirl chamber 46 is formed in a lower end surface of the swirler 40. The fuel in the fuel introduction chamber 42 passes through the swirl hole 45 and swirl chamber 4
6, a swirling flow is given to the fuel.

In the fuel injection valve 1 constructed as described above, when the solenoid coil 4 is energized, the armature 14 is sucked against the urging force of the valve spring 12, the needle valve 19 is slid upward, and the seat portion is 24 is opened. Thereby, the fuel injection nozzle 20
The fuel pumped into the inside of the swirler 40
a, flows into the swirl chamber 46 through the communication hole 44, the fuel introduction chamber 42, and the swirl hole 45, and flows into the fuel injection chamber 32 while turning. The fuel that has flowed into the fuel injection chamber 32 flows toward the center of the bottom surface while turning along the spherical concave surface 31 of the fuel injection chamber 32, and is injected outside through the injection hole 33.

The fuel injection nozzle 2 of the fuel injection valve 1 described above
According to 0, since the chamfered amount of the chamfered surface 33a is large on the inner corner side of the inlet-side edge of the injection hole 33 (see FIG. 4), the flow of the fuel is less likely to be contracted, and the decrease in the flow velocity is reduced. As a result, the difference in flow velocity between the fuel flowing on the inner angle side of the inlet-side edge of the injection hole 33 and the fuel flowing on the outer angle side thereof can be reduced. (Indicated by a chain line A). By the way, the reason for chamfering the outer corner side of the inlet side edge of the injection hole 33 is, for example, if it is formed at the edge of the pin angle, the edge is removed due to separation due to the flow of the fuel, and the injection flow rate increases over time. This is to prevent the change with time.

Also, since the valve seat 22 having the seat portion 24 and the nozzle tip 30 having the fuel injection chamber 32 and the injection hole 33 are joined, the valve seat 2
In the nozzle tip 30 before joining with the nozzle tip 2, the chamfered surface 33 a on the inlet side edge of the injection hole 33 can be easily and accurately processed by end face processing. For example, when the seat portion 24, the fuel injection chamber 32, and the injection hole 33 are integrally provided, the chamfered surface 33a of the inlet side edge of the injection hole 33 must be machined through the thin and deep seat portion 24. However, there is a problem that the process is complicated and difficult to process, but such a problem can be improved. Further, for example, burrs when the injection holes 33 are formed by cutting and spatters when formed by laser processing are easily removed, and a stable spray shape can be obtained.

Before joining, the characteristics of the valve seat 22 and the nozzle tip 30, such as the oil-tightness of the seat portion 24 and the spraying characteristics of the injection hole 33, can be independently evaluated. Even if a defect occurs, it is possible to diversify risks.

Further, when the nozzle tip 30 is formed by metal injection molding, by forming the injection hole 33 with reference to the fuel injection chamber 32, the positional accuracy of the injection hole 33 can be improved. If the valve seat 22 is also made of metal, the valve seat 22 and the nozzle tip 30 can be easily joined by welding. The nozzle tip 30
Can be press-formed instead of metal injection-molded. Also in this case, the injection holes 33 are based on the fuel injection chamber 32.
Is formed, the positional accuracy of the injection hole 33 can be improved.

[Second Embodiment] A second embodiment will be described with reference to the drawings. The second embodiment is a modification of the nozzle tip 30 of the first embodiment, and a description overlapping with the first embodiment will be omitted. FIG. 7 is a sectional view of the nozzle tip 30, FIG. 8 is a top view thereof, and FIG. 9 is a bottom view thereof.
As shown in FIGS. 7 to 9, the plane portion 3 of the nozzle tip 30
5 is made thicker over the entire circumference.

The present invention is not limited to the above embodiment, but can be modified without departing from the scope of the present invention. For example, the number, formation position, ejection direction, and the like of the injection holes 33 are appropriately selected and are not limited to the above. Further, the fuel injection nozzle 20 of the present invention
The present invention is not limited to the direct injection type engine, and can be used for the fuel injection valve 1 used for another engine. Further, the fuel injection nozzle 20 is connected to the valve seat 22 and the nozzle tip 30.
Instead of having a two-piece structure, it is also possible to integrally mold by, for example, MIM molding.

[0032]

According to the fuel injection nozzle of the present invention, it is possible to reduce the difference in the flow velocity between the fuel flowing on the inner angle side of the inlet-side end edge of the injection hole and the fuel flowing on the outer angle side thereof. It can be sprayed in a prescribed spray shape.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel injection nozzle according to a first embodiment.

FIG. 2 is an enlarged view of a part around an injection hole of FIG. 1;

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view of a nozzle tip.

FIG. 5 is a top view of the nozzle tip.

FIG. 6 is a bottom view of the nozzle tip.

FIG. 7 is a sectional view of a nozzle tip according to a second embodiment.

FIG. 8 is a top view of the nozzle tip.

FIG. 9 is a bottom view of the nozzle tip.

FIG. 10 is a sectional view of a fuel injection nozzle showing a conventional example.

[Explanation of symbols]

 19 Valve 22 Valve Seat 24 Seat 30 Nozzle Tip 31 Spherical Concave Surface 32 Fuel Injection Chamber 33 Injection Hole 33a Chamfered Surface

Claims (3)

[Claims] A fuel injection chamber provided downstream of the seat portion and having a bottom surface formed by a spherical concave surface; and a spherical concave wall portion of the fuel injection chamber being inclined. And a chamfered surface that is smoothly continuous with the spherical concave surface at the inlet-side edge of the orifice, wherein the chamfered amount on the inner angle side of the chamfered surface is smaller than the chamfered amount on the outer angle side. Larger fuel injection nozzle. 2. The fuel injection nozzle according to claim 1, wherein a valve seat having a seat portion is joined to a nozzle tip having a fuel injection chamber and an injection hole. 3. The fuel injection nozzle according to claim 2, wherein the nozzle tip is formed by metal injection molding or press molding.