JP3813804B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve for an internal combustion engine used for an automobile engine or the like.
[0002]
[Prior art]
A fuel injection valve (injector) for an internal combustion engine is generally driven by electromagnetic force, and various types of injection holes for injecting fuel have been proposed.
[0003]
For example, in the fuel injection valve described in Japanese Patent Application Laid-Open No. 62-82268, in the pintle type, an injection hole for measuring the fuel and a communication space (branch orifice) for injecting the fuel separately in two downstream thereof are provided. The vapor is formed by a separate member, and the ratio of the area of the sum of the cross-sectional areas of the communication space and the gap between the injection hole and the pintle, and the ratio of the minimum hole diameter of the communication space and the branch orifice injection hole length are set. The prevention of occurrence and reduction of metering properties are aimed at.
[0004]
In JP-A-8-144895, in a needle type fuel injection valve in which a plurality of injection holes are provided in a sac part (nozzle part), the relationship between the inner diameter Dr of the injection hole and the length Dl of the injection hole is expressed as Dr × 3. The fuel rectifying effect is given by setting 0 ≦ D1.
[0005]
[Problems to be solved by the invention]
One of the objects of the present invention is to provide a fuel injection valve capable of realizing easy machining of an injection hole while ensuring mechanical strength at a valve seat against a collision of a valve body.
[0006]
Further, as a fuel injection valve related to this, in order to simplify the number of parts and assembly in a fuel injection valve of a system in which a plurality of fuel injection holes are provided to inject fuel in a plurality of directions (at least two directions). In addition, a member for measuring fuel and a member for injecting fuel in multiple directions are formed as separate members, and a linear spray shape is formed so that good emission can be obtained.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is basically configured as follows.
[0008]
That is, the present invention is a fuel injection valve having a bottomed cylindrical member attached to the tip, and the bottomed cylindrical member is a depression provided with a valve seat that cooperates with a valve body at the center of the bottom. Having at least one fuel injection hole in the recess,
Said protrusion inner surface in the central portion of the bottom portion of the bottomed cylindrical member is put into the dent portion is provided, the outer surface of the protrusion, and a spherical portion formed in the central end, the ambient of the spherical portion An annular portion to be formed, and a constricted portion formed between the annular portion and the spherical portion, and the inner surface of the protruding portion has a spherical portion located inside the spherical portion of the outer surface,
Wall thickness without the uniform spherical surface-like projections by the spherical portions of the central tip of the protrusion is the inner and outer surfaces, the said fuel injection hole in the spherical surface-shaped protrusion is formed, a part of the conical surface of the recess portion Becomes the valve seat,
And between the said hollow part in the bottom part of the said cylindrical member, and the surrounding wall of the said cylindrical member comprise the flat annular part with uniform thickness, The site | part corresponding to this flat annular part and the said valve seat, thickness than, characterized in that the formation of the wall thickness of the sphere surface shaped protrusion thin.
[0009]
By configuring in this way, the nozzle hole can be formed in a relatively thin portion of the bottomed cylindrical recess, so that the nozzle hole can be easily processed in an arbitrary direction, Since the valve seat can be formed by making the wall thickness relatively thick in the same recess as the nozzle hole, the mechanical strength of the valve seat can be secured and the impact resistance against the valve body can be enhanced.
[0010]
Furthermore, the other is to form a seat part (valve seat) in a body having a plurality of fuel injection holes, and use the gap between the valve body and the seat part as a metering part. The ratio between the fuel nozzle interval S and the nozzle hole diameter D is an element that provides a metering and multi-directional injection function with a single member, and realizes good emission of injected fuel. The ratio L / D between the fuel injection hole length L and the fuel injection hole diameter D was set to 1 or more when S / D was 0.5 or less.
[0011]
With this configuration, when the fuel injection valve is opened, the fuel is metered and the fuel flow in multiple directions is formed by the body having the nozzle hole (for example, the nozzle body), and the injection in the form of a thin rod of spray is performed. The injection fuel is sprayed in a straight line toward the intake valve, so that the wall flow in the intake manifold is prevented and good emission is obtained.
In the case of an injector having the above S / D of 0.5 or more and L / D of 1 or less, good emission cannot be obtained due to widening of the spray angle.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a longitudinal sectional view of a fuel injection valve according to an embodiment of the present invention, FIG. 2 (a) is an enlarged sectional view of a nozzle 11 used in the injection valve, and FIG. .
[0014]
In this embodiment, a fuel injection valve (hereinafter referred to as injection) used for an engine having two intake valves per cylinder is taken as an example.
[0015]
Before describing the configuration of the fuel injection valve, the usage pattern of the fuel injection valve will be described with reference to FIGS. 3 and 4.
[0016]
One end of the intake manifold 3 is attached to the engine head 4, and a fuel injection valve (hereinafter referred to as an injector) 1 is attached so that the intake port 6 faces the attachment position of the intake manifold 3.
[0017]
A fuel delivery pipe 2 is supported on the upper side of the intake manifold 3. Fuel in a fuel tank (not shown) is pumped up by a fuel pump, passed through a fuel filter, adjusted to a predetermined pressure by a pressure regulator, and supplied to the fuel delivery pipe 2.
[0018]
A number of branch pipe portions 2 a corresponding to the number of cylinders of the engine are integrally connected to the fuel delivery pipe 2, and each branch pipe portion and the upper part of each injector 1 are connected to the fuel delivery pipe 2. The supplied fuel is distributed to each injector 1.
[0019]
FIG. 4 shows that the tip 5 of the injector 1 is directed to the intake port 6 (intake valve) on the cylinder head 4 side, and fuel is injected in two directions. A nozzle hole (also referred to as a nozzle hole, an injection hole, or an injection hole) for injecting fuel in a plurality of directions is formed in the tip portion 5 of the injector 1, and an attachment structure for injecting fuel to each intake port is provided. It has become.
[0020]
Here, the configuration of the injector according to the present embodiment will be described with reference to FIGS. 1 and 2.
[0021]
The magnetic circuit of the injector 1 includes a fixed iron core (center core) 7, an outer case (yoke) 8, and a movable iron core (plunger) 9. A part of the center core 7 is located at the inner center of the yoke 8, and an outer-molded electromagnetic coil 15 is disposed between the outer periphery of the center core 7 and the inner periphery of the yoke 8.
[0022]
The fixed core 7 has a hollow inside and a fuel passage is formed. A fuel filter 25 is provided at one end of the fixed core 7 and a spring 13 for biasing the plunger 9 with the valve body 10 in the valve closing direction is inserted at the other end. A spring adjuster 14 for adjusting the spring load of the spring 13 is also provided.
[0023]
The electromagnetic coil 15 excites the magnetic circuit described above, and a coil assembly is composed of a connector 16 that transmits an external signal to the coil 15, a bobbin 17 that holds the coil 15, an outer mold 18 that encloses the coil 15, and the like. Is done.
[0024]
A spherical valve body (ball valve) 10 is integrally attached to the distal end of the plunger 9 via a shoulder portion 24, and a guide ring 19 is attached to the rear end of the plunger 9. The guide ring 19 is guided along the inner periphery of the core 7 when the plunger 9 moves.
[0025]
A cylindrical nozzle body 11 is mounted below the yoke 8.
[0026]
The nozzle body 11 is formed of a metal having corrosion resistance into a cylindrical shape, and the center portion of the raised bottom-shaped bottom portion 11B is extruded into a substantially hemispherical shape (partial spherical surface), and two fuel injection holes in two directions are formed in the extruded portion. (It may be called a nozzle hole, an injection hole, and an injection hole) 22 is provided. A valve seat (seat) 12 is formed on the inner surface of the extruded portion.
[0027]
The configuration of the nozzle body 11 will be described in more detail.
[0028]
As shown in FIG. 2A, the nozzle body 11 is formed as a bottomed cylindrical member 11A. The cylindrical member 11A is formed by extruding a hollow portion 11C having a seat 12 at the center of the bottom portion 11B. The seat 12 opens and closes in cooperation with the ball valve 10 (or a needle valve). .
[0029]
The fuel injection port (injection hole) 22 described above is perforated at the bottom of the recess 11C. There may be one nozzle hole 22. The recess 11C is formed of a partial spherical surface or a conical surface. The two injection holes 22 in the embodiment shown in FIG. 2 are arranged with a predetermined spread angle so that the central axis faces the two intake ports of the cylinder when the fuel injection valve is attached to the wall surface of the intake passage. It is installed.
[0030]
Further, as another aspect of the fuel injection valve applied to the present embodiment, the fuel injection valve is used as a fuel injection valve attached to the surge tank. In this case, the two injection holes 22 are connected to the cylinder from the surge tank. It may be formed such that the spray axis has a predetermined spread angle toward the opening of the independent intake pipe connected to the intake port.
[0031]
In another aspect, the fuel injection valve may be of the type that is mounted in the cylinder as desired, in which case it has one injection hole.
[0032]
The thickness T of the member in the hollow portion 11C of the bottom portion 11B of the bottomed cylindrical member 11A is the thickness T1 of the portion corresponding to the valve seat 12 (the portion that contacts when the valve is closed) of the portion where the injection hole 22 is formed. The wall thickness T2 is formed thinner.
[0033]
Further, the bottom portion 11B is provided with a flat plate-like annular portion 11F having a uniform thickness between the hollow portion 11C and the cylindrical peripheral wall 11D.
[0034]
In addition, an annular protrusion 11G that protrudes from the outer surface of the bottom 11B is formed in a specific range from the starting portion of the recess 11C toward the center, and an injection hole 22 is provided in the center of the recess 11C. 11H is formed, and a constricted portion 11K is formed between the annular protrusion 11G and the spherical portion 11H.
[0035]
This ensures the ease of processing of the nozzle hole 22 while ensuring the mechanical strength at the valve seat 12 against the collision of the valve body.
[0036]
Inside the nozzle body 11, a guide 20 for guiding the movement of the ball valve 10 to the upstream position of the seat is provided. The guide 20 has a disk-shaped chip shape, and an inner periphery thereof serves as a guide surface that receives the ball valve 10, and a plurality of fuel passage grooves 21 are formed on the outer periphery and the outer bottom surface of the chip.
[0037]
A stopper 23 for determining the stroke of the valve body is interposed between the nozzle 11 and the yoke 8.
[0038]
When the coil 15 is energized, the core 7, the yoke 8, and the plunger 9 are excited, and the plunger 9 is attracted toward the core 7 against the force of the spring 13. As the plunger 9 moves, the ball valve 10 also moves to move away from the seat portion 12 of the nozzle 11 and open. Here, the plunger 9 moves until the shoulder portion 24 hits the stopper 23, and the plunger 9 and the core 7 do not come into direct contact. The fuel is supplied from the filter 25 side, and is supplied from between the yoke 8 and the plunger 9 to the nozzle 11 part. Further, the fuel passes through a groove 21 formed between the guide member 20 and the nozzle 11 and is injected through an annular gap formed between the seat portion 12 and the ball valve 10 and the two injection holes 22.
[0039]
The fuel is metered in the portion of the fuel passage having the smallest cross-sectional area. In this embodiment, the fuel is metered by the annular gap between the ball valve 10 and the seat portion 12. The weighing unit may be set according to the total area.
[0040]
In the above configuration, as shown in FIG. 2 (b), the ratio S / D between the interval S between the fuel injection holes 22 and the injection hole diameter D is 0.5 or less, and the fuel injection hole length L and the fuel injection hole diameter D are as follows. The ratio L / D is set to be 1 or more.
[0041]
An example of numerical values is as follows.
[0042]
In the present embodiment, the fuel injection holes 22 are arranged so that their center lines intersect with each other. Therefore, the interval between the fuel injection holes 22 is narrow on the upstream side and wide on the downstream side. The narrowest interval among them is used as a reference, and as an example, the interval S is set to (0.2 ± 0.02) mm. Incidentally, the larger distance S ′ between the nozzle holes 22 is 0.39 mm, the diameter D of each nozzle hole 22 is φ (0.41 ± 0.005) mm, and the length L of the nozzle holes 22 is (0.5). ± 0.01) mm, and the spread arrangement angle between the nozzle holes 22 is 7 ° ± 0.5 °.
[0043]
5 and 6, the ratio S / D between the interval S between the nozzle holes 22 and the nozzle hole diameter D is 0.5 or less, and the ratio L / D between the fuel nozzle hole length L and the fuel nozzle hole diameter D is 1 or more. The grounds (experimental data) are shown.
[0044]
The experimental data shown in FIG. 5 is obtained by examining data using a distribution measuring method for quantitatively evaluating the spray shape. In the case of an injector having S / D of 0.5 or less and L / D of 1 or more. As shown in FIG. 6, when the ball valve is opened and closed, the fuel flow is rectified, and the spray distribution shows that about 80% of the spray is rod-shaped as shown in FIG.
[0045]
On the other hand, in the case of an injector having S / D of 0.5 or more and L / D of 1 or less, the nozzle hole position is away from the center, so that the fuel flow is disturbed and spreads outward when the ball valve is opened and closed. Since it is injected in the direction, it can be seen that the spray distribution is about 50% and the spray is wide-angled.
[0046]
According to the present embodiment, the nozzle hole 22 can be formed at a relatively thin portion in the bottomed cylindrical recess 11C, so even if a plurality of nozzle holes are arranged in an arbitrary direction. Since the valve seat 12 can be formed by making the wall thickness relatively thick in the recess 11C that is the same as the nozzle hole, the mechanical strength of the valve seat can be ensured and the impact resistance against the valve body 10 is improved. be able to. In addition, even when the thickness of the hollow portion 11C is changed, the molding can be easily performed by extruding the annular projection portion 11G and the spherical surface portion (partial spherical surface portion) 11H.
[0047]
In addition, fuel metering and optimal injection that is rod-shaped in multiple directions can be realized with a single member (for example, a single nozzle), and the number of parts and assembly of the injection valve can be simplified, and good fuel emission can be obtained.
[0048]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the nozzle which has a nozzle hole and a valve seat can be made easy, and also the impact resistance (mechanical strength) with respect to a valve body can be improved. In addition, fuel metering and optimal injection that is rod-shaped in multiple directions can be realized by a single member (for example, a single nozzle), and the number of parts and assembly of the injection valve can be simplified, and good fuel emission can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an injector according to an embodiment of the present invention.
FIG. 2A is an enlarged sectional view of a nozzle 11 used in the injection valve, and FIG.
FIG. 3 is a cross-sectional view showing an installation example of the injector.
FIG. 4 is an explanatory view showing a usage pattern of the injector.
FIG. 5 is an explanatory diagram showing experimental data of the example.
FIG. 6 is a diagram showing experimental data of the example.
[Explanation of symbols]
Injector (fuel injection valve), 10 ... ball valve, 11 ... nozzle, 11G ... annular protrusion, 12 ... valve seat (seat), 22 ... fuel injection hole.

Claims (3)

A fuel injection valve having a bottomed cylindrical member attached to the tip, the bottomed cylindrical member having a recess with a valve seat that cooperates with the valve body at the center of the bottom. In one having at least one fuel injection hole in the recess,
Said protrusion inner surface in the central portion of the bottom portion of the bottomed cylindrical member is put into the dent portion is provided, the outer surface of the protrusion, and a spherical portion formed in the central end, the ambient of the spherical portion An annular portion to be formed, and a constricted portion formed between the annular portion and the spherical portion, and the inner surface of the protruding portion has a spherical portion located inside the spherical portion of the outer surface,
Wall thickness without the uniform spherical surface-like projections by the spherical portions of the central tip of the protrusion is the inner and outer surfaces, the said fuel injection hole in the spherical surface-shaped protrusion is formed, a part of the conical surface of the recess portion Becomes the valve seat,
And between the said hollow part in the bottom part of the said cylindrical member, and the surrounding wall of the said cylindrical member comprise the flat annular part with uniform thickness, The site | part corresponding to this flat annular part and the said valve seat, fuel injection valve thickness than, characterized in that the formation of the wall thickness of the sphere surface shaped protrusion thin. The ball planar projection, the fuel injection valve according to claim 1, wherein a plurality of fuel injection holes are provided.   The ratio S / D between the interval S between the fuel injection holes and the injection hole diameter D is 0.5 or less, and the ratio L / D between the fuel injection hole length L and the fuel injection hole diameter D is 1 or more. The fuel injection valve as described.

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