JP3655905B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve used for in-cylinder injection, for example, and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, the disk-shaped nozzle plate has a tapered shape in which the area on the fuel outlet side is larger than the area on the fuel inlet side, and the center on the fuel outlet side is located on the outer peripheral side with respect to the center on the fuel inlet side. There is known a fuel injection valve provided with a plurality of nozzle holes with inclined nozzle axes connecting both centers (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-221128 (FIG. 2C)
[0004]
[Problems to be solved by the invention]
In this fuel injection valve, a disc-shaped nozzle hole plate having a uniform thickness is provided with a nozzle hole having a tapered shape and an inclined nozzle axis, and the nozzle angle formed by the nozzle axis and the nozzle inlet end surface is different for each nozzle. As well as being different, the nozzle length is also different.
Therefore, if the nozzle angles differ greatly, the liquid film state of the fuel on the inner wall of each nozzle will differ greatly, and the spray state of the fuel injected from each nozzle will differ at each nozzle, resulting in uniform atomization in the cylinder. There was a problem that could not be achieved.
[0005]
An object of the present invention is to provide a fuel injection valve capable of achieving uniform atomization of a spray in a cylinder with a simple configuration. It is.
[0007]
[Means for Solving the Problems]
In the fuel injection valve according to the present invention, the injection hole plate has the same injection hole angle formed by the injection hole axis line connecting the center on the fuel inlet side of the injection hole and the center on the fuel outlet side at each injection hole and the injection hole end face. has a protrusion protruding on the valve seat side, and Ri uniform thickness Sadea,
Further, a tip-shaped cavity is formed at the tip of the valve body toward the nozzle plate side,
Furthermore, the angle (δ) on the nozzle plate side at which the central axis of the valve body and the cavity extension line extending toward the central axis of the surface of the cavity intersect is determined from the central axis and the surface of the protrusion. It is further smaller than the minimum angle (η) of the angles on the nozzle plate side at which the projecting extension lines extending toward the central axis intersect.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described, but the same, equivalent members, and parts will be described with the same reference numerals.
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the overall configuration of an in-cylinder fuel injection valve 1 (hereinafter abbreviated as a fuel injection valve) of the present invention, and FIG. 2 is an enlarged view of a main part of the valve device 3 of FIG.
The fuel injection valve 1 includes a housing 2, a valve device 3 provided at an inner end of the housing 2, and a solenoid device 4 provided at an inner intermediate portion of the housing 2.
[0010]
The valve device 3 has a stepped cylindrical shape with a valve body 5 having a hole 6 and a cavity 7 formed in a valve seat 19, a nozzle plate 9 having a plurality of nozzle holes 8 welded to the cavity 7, and a valve body 5. A valve body 11 that moves up and down on the central axis I of the valve body 11 to open and close the hole 6, a stopper plate 10 that defines the upper limit of movement of the valve body 11, and a movable iron core 12 that is welded and joined at the upper end of the valve body 11; It has.
[0011]
The housing 2 includes a yoke 13 having a flange 13 a for attaching the fuel injection valve 1 to a cylinder head (not shown), and a housing portion 14 connected to one end of the yoke 13. A caulking portion 13b is formed at the tip of the yoke 13, and the valve main body 5 and the yoke 13 are coupled to each other by the caulking portion 13b.
[0012]
The solenoid device 4 includes a coil 15 around which a conductive wire is wound, a bobbin 16 on which the coil 15 is mounted, a cylindrical fixed iron core 17 attached to an inner peripheral portion of the bobbin 16, and the fixed iron core 17. A sleeve 18 fixed inside, a compression spring 20 which is contracted between the end of the sleeve 18 and the end of the valve body 11 and urges the valve body 11 against the valve seat 19, and a conductor of the coil 15. Are connected to the terminal 21. A fuel passage is formed by a passage 18 a in the sleeve 18 and a gap formed between the valve body 5 and the valve body 11.
[0013]
A plurality of nozzle holes 8 are formed in the nozzle plate 9. The nozzle hole 8 has a taper shape in which the area on the fuel outlet side is larger than the area on the fuel inlet side. Further, as shown in FIG. 3A, the angle α formed by the nozzle axis A connecting the center of the fuel inlet side of the nozzle hole 8 and the center of the fuel outlet side and the nozzle inlet end surface B is the same for each nozzle hole 8. Thus, the nozzle hole plate 9 has a protruding portion 9a protruding toward the hole 6 side. Moreover, in order to make the length of each nozzle hole 8 along the nozzle axis A the same for each nozzle hole 8, the thickness of the nozzle plate 9 is uniform.
[0014]
The nozzle plate 9 is easily manufactured by forming the nozzle holes 8 in a disk plate having a uniform thickness, and then bending the plate to form the protrusions 9a.
[0015]
Next, the operation of the fuel injection valve 1 configured as described above will be described.
When an operation signal is sent to the drive circuit of the fuel injection valve 1 by the microcomputer of the engine, the coil 15 of the solenoid device 4 is energized from the outside through the terminal 21, and magnetic flux is generated in the magnetic path formed by the movable iron core 12, the fixed iron core 17 and the yoke 13. As a result, the movable iron core 12 is attracted toward the fixed iron core 17 against the elastic force of the compression spring 20. Then, the valve body 11 integrated with the movable iron core 12 moves up to a position where the flange upper surface 11 a of the valve body 11 contacts the stopper plate 10.
[0016]
With the upward movement of the valve body 11, the distal end portion of the valve body 11 is separated from the valve seat 19, and a gap is formed between the distal end portion and the valve seat 19. As a result, the high pressure fuel of 2 MPa or more in the housing 2 passes through the passage 18a in the sleeve 18, the gap formed between the valve body 5 and the valve body 11, the hole 6 and the cavity 7, and the nozzle hole of the nozzle plate 9 8 is injected into the cylinder.
[0017]
Next, when an operation stop signal is sent from the microcomputer of the engine to the drive circuit of the fuel injection valve 1, the energization of the coil 15 is stopped, the magnetic flux in the magnetic circuit disappears, and the valve body 11 is closed. The gap at the valve seat 19 is closed by the compression spring 20 that is pushed to the end, and the fuel injection ends.
[0018]
Hereinafter, the operation of the nozzle plate 9 which is a feature of the present invention will be described in comparison with the above-described conventional fuel injection valve.
As shown in FIG. 4 (a), the conventional one is provided with nozzle holes 51, 52 having tapered shapes in which the area on the fuel outlet side is larger than the area on the fuel inlet side, on the nozzle plate 50 of uniform thickness. In each of the nozzle holes 51 and 52, the nozzle angles β and γ formed by the nozzle axis axes C and D connecting the center of the fuel inlet side of the nozzle holes 51 and 52 and the center of the fuel outlet side and the nozzle inlet end face E are different. Therefore, the lengths of the nozzle holes 51 and 52 along the nozzle axis axes C and D are also different.
[0019]
In this case, the fuel collides vertically with the nozzle plate 50, but the nozzle axes C and D are inclined, so that the fuel flows toward one side of the inner wall surface of the nozzles 51 and 52. Since the inclination angles of the axes C and D and the lengths of the nozzle holes 51 and 52 are different, as shown in FIG. 4B, the nozzle holes 51 and 52 whose area on the fuel outlet side is larger than the area on the fuel inlet side. Then, the cross-sectional shape of the fuel becomes a crescent shape at the fuel outlet, and the shape and the liquid film thickness are greatly different at the nozzle holes 51 and 52 respectively. As a result, uniform atomization in the cylinder cannot be achieved.
[0020]
On the other hand, in the nozzle hole plate 9 of this embodiment, the nozzle hole plate 9 has a projecting portion 9a that is curved and deformed, and the angle α formed between the nozzle hole axis A and the nozzle hole inlet end surface B is the same for each nozzle hole 8, and The thickness of the nozzle hole plate 9 is uniform, and the length of each nozzle hole 8 along the nozzle axis A is the same for each nozzle hole 8.
In this case, the fuel collides perpendicularly with the nozzle plate 9 but flows toward one side of the inner wall surface of the nozzle 8 because the nozzle axis A is inclined. Since the nozzle angle α formed with the inlet end face B and the length of the nozzle 8 are the same, as shown in FIG. 3B, the cross-sectional shape of the fuel at the fuel outlet of each nozzle 8 is substantially the same crescent shape. Therefore, there is no great difference in the thickness of the liquid film, and as a result, the fuel is atomized more uniformly in the cylinder as compared with the conventional one.
[0021]
Embodiment 2. FIG.
FIG. 5 is a cross-sectional view of the main part of the fuel injection valve 1 according to Embodiment 2 of the present invention.
In the second embodiment, a cavity 31 having a diverging shape toward the nozzle hole plate 9 is formed at the tip of the valve body 30.
Further, the angle (δ) on the nozzle plate 9 side where the central axis I of the valve body 11 intersects with the cavity extension line extending toward the central axis I of the surface of the cavity 31 is the surface of the central axis I and the protruding portion 9a. Is smaller than the minimum angle (η) of the angles on the side of the nozzle hole plate 9 at which the respective projecting extension lines extending toward the central axis I intersect.
The projecting extension line is a tangent line of the projecting portion 9a, but in the case of the second embodiment, the minimum angle (η) is a tolerance between the tangent line from the rising point of the projecting portion 9a protruding in a curved shape and the central axis I. It is an angle.
Other configurations are the same as those in the first embodiment.
[0022]
In the first embodiment, the internal space of the cavity 7 has the same diameter, and when the fuel is injected into the cavity 7 from the hole 6, the flow path cross-sectional area of the fuel changes drastically and the inside of the cavity 7 A vortex or the like is generated in the upstream corner, and fluid energy is lost accordingly.
On the other hand, in the case of the second embodiment, when the fuel is injected from the hole 6 into the cavity 7, the flow passage cross-sectional area of the fuel gradually expands. Is less likely to occur and fuel atomization is improved accordingly.
[0023]
Further, the angle (δ) at which the central axis I of the valve body 11 intersects with the cavity extension line is further smaller than the minimum angle (η) of the angles at which the central axis I intersects with the respective projecting extension lines. Therefore, the flow path cross-sectional area in the cavity 31 is prevented from rapidly increasing, and fluid energy such as vortex generation and fuel stagnation is generated at the portion where the cross-sectional area increases rapidly on the downstream side of the cavity 31. It is possible to suppress the occurrence of inconveniences that adversely affect the loss and consequently the atomization of the fuel.
[0024]
Embodiment 3 FIG.
FIG. 6 is a partial cross-sectional view of the nozzle plate 40 according to Embodiment 3 of the present invention. In this embodiment, the nozzle plate 40 has a protruding portion 40a that protrudes linearly and obliquely upward.
Other configurations are the same as those of the second embodiment.
[0025]
Also in this embodiment, the angle (δ) on the nozzle plate 40 side where the central axis I of the valve body 11 intersects the cavity extension line extends from the surface of the central axis I and the protrusion 40a toward the central axis I. Since the angle is smaller than the angle (η) on the nozzle hole plate 40 side where the projecting extension line intersects, it is possible to suppress a rapid increase in the cross-sectional area of the fuel flow path in the downstream in the cavity 31, and as a result The effect similar to the form 2 of this can be acquired.
[0026]
Embodiment 4 FIG.
FIG. 7 is a partial cross-sectional view of a nozzle plate 41 according to Embodiment 4 of the present invention. In this embodiment, the nozzle plate 41 has a protruding portion 42 bent at an intermediate portion. The projecting portion 42 includes a first projecting element 42a and a second projecting element 42b. The angle (η) on the nozzle plate 41 side where the central axis I intersects with the projecting extension line extending from the surface of the first projecting element 42a toward the central axis I is such that the central axis I and the second projecting element 42b The angle is smaller than the angle on the nozzle plate 41 side where the projecting extension line extending toward the central axis I intersects. Further, the angle (δ) at which the central axis I of the valve body 11 and the cavity extension line intersect is smaller than this angle (η).
Other configurations are the same as those of the third embodiment.
[0027]
Also in this embodiment, the angle (δ) at which the central axis I of the valve body 11 intersects the cavity extension line is the central axis I and the protruding extension line extending toward the central axis I of the first protrusion 42a. Is smaller than the crossing angle (η), it is possible to suppress a rapid increase in the cross-sectional area of the fuel flow path in the downstream in the cavity 31, and as a result, the same effect as in the second embodiment can be obtained. be able to.
In addition, although this protrusion part is bent in one place on the way, it may be bent in multiple numbers.
[0028]
In each of the above embodiments, the fuel injection valve for in-cylinder injection has been described. However, the present invention is of course not limited to this, and is attached so as to protrude into the intake pipe, and the fuel is injected into the intake pipe. It is applicable also to the fuel injection valve which injects and produces | generates the air-fuel mixture with air.
[0029]
【The invention's effect】
As described above, according to the fuel injection valve of the present invention, the nozzle plate is formed by the nozzle axis connecting the fuel inlet side center of the nozzle hole and the fuel outlet side center of each nozzle hole and the nozzle inlet end surface. Since it has a protrusion that protrudes toward the valve seat so that the nozzle angles are the same, and has a uniform thickness, the cross-sectional shape of the fuel at the fuel outlet of each nozzle is almost the same. There is no great difference in the thickness of the liquid film, and uniform atomization of the fuel can be achieved.
Further, the angle (δ) at which the central axis of the valve body and the cavity extension line intersect is further smaller than the minimum angle (η) of the angles at which the center axis and each projecting extension line intersect. The flow cross-sectional area in the cavity is prevented from abruptly increasing, and the loss of fluid energy such as vortex generation and fuel stagnation in the area where the cross-sectional area increases rapidly on the downstream side of the cavity. The occurrence of inconvenience that adversely affects atomization can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a fuel injection valve for in-cylinder injection according to Embodiment 1 of the present invention.
2 is an enlarged view of a main part of the in-cylinder fuel injection valve of FIG. 1. FIG.
FIG. 3 is a view showing fuel distribution in the nozzle hole of the nozzle plate of FIG. 1;
FIG. 4 is a view showing a fuel distribution in a nozzle hole of a conventional nozzle plate.
FIG. 5 is a cross-sectional view of a main part of a fuel injection valve for in-cylinder injection according to Embodiment 2 of the present invention.
FIG. 6 is a cross-sectional view of a main part of a fuel injection valve for in-cylinder injection according to Embodiment 3 of the present invention.
FIG. 7 is a cross-sectional view of a main part of a fuel injection valve for in-cylinder injection according to Embodiment 4 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel injection valve for cylinder injection, 5,30 Valve main body, 6 holes, 7,31 cavity, 8 injection hole, 9,40,41 injection hole plate, 9a, 40a, 42 protrusion part, 11 valve body, 19 valve seat, 42a 1st protrusion, 42b 2nd protrusion, A nozzle hole axis line, B nozzle inlet end surface.

Claims (1)

A valve body having a fuel passage therein and having a valve seat formed at an end thereof, the fuel passage is closed by being seated on the valve seat, and the fuel passage is released by being separated from the valve seat. A valve body and a taper shape provided at the tip of the valve body and injecting fuel flowing out of the fuel passage when the valve body is opened, having a fuel outlet side area larger than a fuel inlet side area A fuel injection valve comprising a nozzle plate having a plurality of nozzle holes,
The nozzle plate protrudes toward the valve seat so that the nozzle angle formed by the nozzle axis connecting the fuel inlet side center of the nozzle and the fuel outlet side center and the nozzle inlet end surface is the same at each nozzle hole. has a protruding portion that, and Ri uniform thickness Sadea,
Further, a tip-shaped cavity is formed at the tip of the valve body toward the nozzle plate side,
Furthermore, the angle (δ) on the nozzle plate side at which the central axis of the valve body and the cavity extension line extending toward the central axis of the surface of the cavity intersect is determined from the central axis and the surface of the protrusion. A fuel injection valve that is smaller than a minimum angle (η) of angles on the nozzle plate side at which the respective projecting extension lines extending toward the central axis intersect .

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