DESCRIPTION Title of Invention: FUEL INJECTION VALVE Technical Field
[0001]
The present application relates to the field of a fuel injection valve used to supply fuel to, for example, an automobile internal-combustion engine, and particularly, to the field of a fuel injection valve intended to promote atomization in spray properties. Background Art
[0002]
In recent years, under the tighter control on exhaust emissions from automobile internal-combustion engines, it has been required to atomize the fuel spray injected from a fuel injection valve. As one of spray atomization techniques, a technology is known whereby a swirling force is imparted to fuel flowing into each injection hole, thus forming a swirling flow, and various deliberations thereon are being carried out.
[0003]
For example, PTL 1 discloses a fuel injection valve which includes swirl passages provided on the downstream side of an opening portion of a valve seat, swirl chambers which, being formed on the downstream side of the swirl passages, cause fuel to swirl thereinside, and injection holes provided one in each of the bottoms of the swirl chambers. In this prior art, two

swirl chambers are provided, adjacent to each other, in the downstream side end portion of one swirl passage, and the starting points (upstream ends) of the individual swirl chambers are on the central axis of the swirl passage. Citation List Patent Literature
[0004]
PTL 1: JP-A-2013-142323 Summary of Invention Technical Problem
[0005]
An injection hole plate of a fuel injection valve has heretofore been manufactured, for example, by pressing suitable for mass production or by electrical discharge machining, or etching, which applies relatively less stress, but there is a problem in that when to form in an injection hole plate the same number of swirl passages and swirl chambers as the number of injection holes, there also being the recent tendency of an increase in the number of injection holes, complicated and high-accuracy processing is required, leading to a higher cost.
[0006]
In the heretofore mentioned PTL 1, there is one swirl passage for two swirl chambers, and so the number of swirl passages is reduced. As the two swirl chambers are provided

so that the swirl passage is constant in width with respect to the two swirl chambers and that the starting points (upstream ends) of the two swirl chambers are on the central axis of the swirl passage, however, there is a problem in that the two swirl chambers, as well as their injection holes, are close to each other, and fuels injected from the two injection holes, being in liquid films, interfere with each other, resulting in a deterioration in spray atomization.
[0007]
The present application has been made to solve the above problems, and an object of the present application is to obtain a fuel injection valve whereby it is possible to form a swirling flow of fuel with a simple structure which is easy to process and thus possible to afford spray atomization. Solution to Problem
[0008]
A fuel injection valve disclosed in the present application includes a valve seat having an opening portion on the downstream side; a valve body which, being provided so as to be slidable, opens/closes the valve seat; and an injection hole plate which, being fixed to a downstream side end face of the valve seat, has a plurality of injection holes penetrated in the direction of plate thickness, wherein swirl portions, which cause fuel flowing into their respective injection holes to swirl, and swirl passages, an upstream side end portions

of which communicate with the opening portion of the valve seat and which lead fuel into the swirl portions, are provided inside a hollow cavity formed between the downstream side end face of the valve seat and an upstream side end face of the injection hole plate, and wherein a passage width of the swirl passages increases toward the downstream side, and two swirl portions are connected, spaced from each other, one to each of two ends of a downstream side end portion of one swirl passage. Advantageous Effects of Invention
[0009]
According to the fuel injection valve disclosed in the present application, two swirl portions are disposed one at each of two ends in the direction of passage width of the downstream side end portion of one swirl passage, and so the swirl passage and the swirl portions are of a simple structure and easy to process. Also, by increasing the passage width of the swirl passage toward the downstream side, fuel flows out, in the direction of radiation with the center of the opening portion of the valve seat as the base point, along the wall surfaces on both sides of the swirl passage, and the flow of fuel is efficiently adjusted, so that a uniform swirling flow can be produced by the swirl portions, and it is possible to afford spray atomization. Also, the distance between two injection holes can be secured, and so it does not happen that fuels, being in liquid films, interfere with each other,

leading to a good spray atomization
The foregoing and other objects, features, aspects, and advantages of the present application will be more apparent from the following detailed descriptions of the present application with reference to the drawings. Brief Description of Drawings
[0010] [Fig. 1] Fig. 1 is a sectional view showing the overall configuration of a fuel injection valve according to the first embodiment.
[Fig. 2] Fig. 2 is a fragmentary enlarged sectional view showing the leading end portion of the fuel injection valve according to the first embodiment.
[Fig. 3] Fig. 3 is a fragmentary plan view showing the leading end portion of the fuel injection valve according to the first embodiment.
[Fig. 4] Fig. 4 is a diagram describing a configuration of the leading end portion of the fuel injection valve according to the first embodiment.
[Fig. 5] Fig. 5 is a diagram describing the flow of fuel in the leading end portion of the fuel injection valve according to the first embodiment.
[Fig. 6] Fig. 6 is a diagram describing a configuration of the leading end portion of a fuel injection valve according to the second embodiment.

[Fig. 7] Fig. 7 is a diagram describing the flow of fuel in the leading end portion of the fuel injection valve according to the second embodiment.
[Fig. 8] Fig. 8 is a diagram showing a modification example of the leading end portion of the fuel injection valve according to the second embodiment.
[Fig. 9] Fig. 9 is a plan view showing the leading end portion of a fuel injection valve according to the third embodiment. [Fig. 10] Fig. 10 is a fragmentary enlarged sectional view showing the leading end portion of the fuel injection valve according to the third embodiment.
[Fig. 11] Fig. 11 is a plan view showing a modification example of the leading end portion of the fuel injection valve according to the third embodiment.
[Fig. 12] Fig. 12 is a plan view showing the leading end portion of a fuel injection valve according to the fourth embodiment. [Fig. 13] Fig. 13 is a fragmentary enlarged sectional view showing the leading end portion of the fuel injection valve according to the fourth embodiment.
[Fig. 14] Fig. 14 is a diagram describing a configuration of the leading end portion of a fuel injection valve in a comparison example. Description of Embodiments
[0011] First Embodiment

Hereafter, a description will be given, based on the drawings, of a fuel injection valve according to the first embodiment. Fig. 1 is a sectional view showing the overall configuration of the fuel injection valve according to the first embodiment, Fig. 2 is a fragmentary enlarged sectional view showing the leading end portion of the fuel injection valve according to the first embodiment, and Fig. 3 a fragmentary-plan view of the portion shown by A-A in Fig. 2 as seen from the upstream side. In the individual drawings, identical signs are given to identical and equivalent portions.
[0012]
A fuel injection valve 1 includes a solenoid unit 2 which generates an electromagnetic force and a valve unit 7 which operates by supplying current to the solenoid unit 2. The solenoid unit 2 includes a housing 3 which is the yoke portion of a magnetic circuit, a core 4 which is the stationary core portion of the magnetic circuit, a coil 5 provided so as to surround the core 4, and an armature 6 which is the movable core portion of the magnetic circuit.
[0013]
The valve unit 7 includes a valve body 8, a valve main body 9, and a valve seat 10. The cylindrically shaped valve main body 9 is press fitted on and then welded to the outer diameter portion of the leading end of the core 4. The valve body 8, which, having connected to the upstream side thereof

a compression spring 14, is provided so as to be slidable, opens/closes the valve seat 10. The valve body 8 has a ball 13 fixed by welding to the leading end portion of a hollow rod which is press fitted against and welded to the inner surface of the armature 6. The ball 13 has a chamfered portion 13a parallel to a central axis Z of the fuel injection valve 1.
[0014]
The valve seat 10 is provided partway in the passage inside the valve main body 9 through which fuel flows, and as shown in Fig. 2, has a valve seat' s seat portion 10a which comes into abutment with the ball 13 and a valve seat opening portion 10b which is an opening portion on the downstream side of the valve seat's seat portion 10a. Furthermore, an injection hole plate 11 is connected by welding to the downstream side end face of the valve seat 10. The injection hole plate 11 has a plurality of injection holes 12 penetrated in the direction of plate thickness.
[0015]
Next, a description will be given of the operation. When an operation signal is sent to a drive circuit of the fuel injection valve 1 from an engine control device, current is supplied to the coil 5 of the fuel injection valve 1, generating magnetic fluxes in the magnetic circuit configured of the armature 6, the core 4, the housing 3, and the valve main body 9. The armature 6 thereby operates so as to be attracted to

the core 4 side, and when the valve body 8 structured integral with the armature 6 separates from the valve seat' s seat portion 10a, forming a clearance, fuel, passing through the clearance between the valve seat's seat portion 10a and the ball 13 from the chamfered portion 13a of the ball 13 welded to the leading end portion of the valve body 8, is injected into an engine intake passage from the plurality of injection holes 12.
[0016]
Also, when an operation stop signal is sent to the drive circuit of the fuel injection valve 1 from the engine control device, the supply of current to the coil 5 stops, and the magnetic fluxes in the magnetic circuit decrease, causing the compression spring 14 pressing the valve body 8 in a valve closed direction to bring the relationship between the valve body 8 and the valve seat' s seat portion 10a into a closed state, thus finishing the fuel injection. The valve body 8 slides together with the armature 6 in a guide portion 6a engaging the valve main body 9, and in a valve open state, an upper surface 6b of the armature 6 abuts against the lower surface of the core 4 .
[0017]
A detailed description will be given, using Figs. 2 to 4, of a configuration of the leading end portion of the fuel injection valve 1 according to the first embodiment. The leading end portion of the fuel injection valve 1 has a hollow

cavity formed between the downstream side end face of the valve seat 10 and an upstream side end face 11a of the injection hole plate 11. In the first embodiment 1, the hollow cavity is formed as a recessed portion provided in the upstream side end face 11a of the injection hole plate 11.
[0018]
As shown in Fig. 3, swirl portions 15, which cause fuel flowing into the respective injection holes 12 to swirl and impart a swirling force to the fuel, and swirl passages 16, through which to lead the fuel into the swirl portions 15, are provided inside the hollow cavity. The injection holes 12 through which to inject fuel to the exterior (the engine intake passage) are opened one in each of the bottoms of the swirl portions 15. The upstream side end portions of the swirl passages 16 communicate with the valve seat opening portion 10b, and the downstream side end portions thereof communicate with the swirl portions 15.
[0019]
As shown in Fig. 4, a passage width W of the swirl passage 16 increases toward the downstream side, and two swirl portions 15 are connected, spaced from each other, one to each of two ends in the passage width W direction of the downstream side end portion of one swirl passage 16.
[0020]
When the two swirl portions 15 connected to the one swirl

passage 16 are described as a first swirl portion 15a and a second swirl portion 15b, the swirl passage 16 has a first wall surface 16a connected to the inner circumferential wall surface of the first swirl portion 15a, a second wall surface 16b connected to the inner circumferential wall surface of the second swirl portion 15b, and a third wall surface 16c which connects the inner circumferential wall surface of the first swirl portion 15a and the inner circumferential wall surface of the second swirl portion 15b.
[0021]
The third wall surface 16c is a wall surface provided between a point Pi on the virtual circumference of the first swirl portion 15a and a point P2 on the virtual circumference of the second swirl portion 15b, and in the first embodiment, is curved so as to be recessed inwardly of the swirl passage 16. The positions of Pi and P2 are not limited to the positions shown in Fig. 4.
[0022]
The first and second swirl portions 15a and 15b (collectively described as the swirl portions 15) are disposed so that the inner circumferential wall surfaces thereof respectively protrude partially out of the first and second wall surfaces 16a and 16b of the swirl passage 16. In the example shown in Fig. 4, the center of each of the injection holes 12 is disposed so as to coincide with the center of each

respective swirl portion 15, but the center of each of the injection holes 12 may be disposed off the center of each respective swirl portion 15.
[0023]
The swirl passage 16 is disposed so that the width thereof increases toward the downstream side. The angle formed by the first and second wall surfaces 16a and 16b of the swirl passage 16 is determined in the following way. As shown in Fig. 4, in the region covered by one swirl passage 16 and the swirl portions 15, a tangent line T parallel to a wall surface of the swirl passage 16 on the side close to each of the swirl portions 15 is drawn to the virtual circumference of each swirl portion 15. That is, a tangent line Tl parallel to the first wall surface 16a is drawn to the first swirl portion 15a, and a tangent line T2 parallel to the second wall surface 16b is drawn to the second swirl portion 15b. By so doing, two virtual swirl passages 161, 162 are drawn.
[0024]
Furthermore, the angle formed by the first and second wall surfaces 16a and 16b of the swirl passage 16 is adjusted so that a centerline Ll (or a centerline L2) , which halves the area between the first wall surface 16a (or the second wall surface 16b) of the swirl passage 16 and the tangent line Tl (or the tangent line T2), passes through the center Z of the valve seat opening portion 10b. This kind of angle adjustment

enables the direction of radiation from the center Z of the valve seat opening portion 10b to coincide with the direction of the virtually drawn centerline Ll (or centerline L2) of the swirl passage 161 (or the swirl passage 162), realizing such fuel flows as shown in Fig. 5.
[0025]
In Fig. 5, arrows f show the flows of fuel in the leading end portion of the fuel injection valve 1. Fuel flows out, in the direction of radiation with the center Z of the valve seat opening portion 10b as the base point, along the first and second wall surfaces 16a and 16b of the swirl passage 16. Because of this, the fuel flows f are efficiently adjusted and thus prevented from heading directly toward the injection holes 12, and uniform swirling flows are produced by the swirl portions 15.
[0026]
Furthermore, in the first embodiment, the curved third wall surface 16c is provided between the two swirl portions 15, thereby prompting the branching of the fuel flows f heading toward the two swirl portions 15 and also affording a reduction in dead volume. The swirling flows in the swirl portions 15 are maintained inside the injection holes 12 as well, thus forming a thin liquid film following the inner wall of each of the injection holes 12. The thin liquid film is injected from each injection hole 12, forming a hollow conical spray.

[0027]
Fig. 14 shows a configuration of the leading end portion of a fuel injection valve in a comparison example of the first embodiment. In the comparison example, a first swirl portion 25a and a second swirl portion 25b are provided in the downstream side end portion of one swirl passage 26, but the swirl passage 26 is large and constant in width. In order to efficiently adjust fuel flows f in the heretofore described way, when the swirl passage 26 is virtually divided into two by the central axis Z, it is ideal that respective centerlines Ll, L2 of the two swirl passages 26 extend radially from a center Z of a valve seat opening portion 20b, but in the comparison example shown in Fig. 14, the respective centerlines Ll, L2 of the swirl passages do not cross the center Z of the valve seat opening portion 20b.
[0028]
In the comparison example, the fuel flows f do not follow a first and a second wall surface 26a and 26b on both sides of the swirl passage 26 and so are difficult to adjust. Because of this, fuel does not produce a swirling flow and easily flows directly into each injection hole 22, and spray atomization is inhibited due to a deficiency in swirling force.
[0029]
As above, according to the fuel injection valve 1 according to the first embodiment, two swirl portions 15 are

disposed, spaced from each other, one at each of two ends in the passage width W direction of the downstream side end portion of one swirl passage 16, and so it is possible to reduce the number of swirl passages as compared with when providing swirl passages and swirl portions on a one-to-one basis. For this reason, the swirl passage 16 and the swirl portions 15 are of a simple structure, allowing a high design freedom, and are easy to process.
[0030]
Also, by increasing the passage width W of the swirl passage 16 toward the downstream side, fuel flows out, in the direction of radiation with the center Z of the valve seat opening portion 10b as the base point, along the first and second wall surfaces 16a and 16b on both sides of the swirl passage 16, and so the flow of fuel is efficiently adjusted. By so doing, a uniform swirling flow can be produced by each of the swirl portions 15, and it is possible to afford the atomization of spray injected from the injection holes 12. Furthermore, as it is possible to secure the distance between two injection holes 12, it does not happen that fuels, being in liquid films, interfere with each other, allowing a good spray atomization.
[0031] Second Embodiment
A description will be given, using Figs. 6 and 7, of a

configuration of the leading end portion of a fuel injection valve according to the second embodiment. The overall configuration of a fuel injection valve 1 according to the second embodiment is the same as in the heretofore mentioned first embodiment, and so the description of the individual portions will be omitted by borrowing Fig. 1. In the heretofore mentioned first embodiment, the third wall surface 16c between the first and second swirl portions 15a and 15b is curved so as to be recessed inwardly of the swirl passage 16, but a third wall surface 16d of the fuel injection valve 1 according to the second embodiment is a plane surface overlapping a tangent line common to the first and second swirl portion 15a and 15b.
[0032]
As shown in Fig. 6, the third wall surface 16d linearly connects a point P3 on the virtual circumference of the first swirl portion 15a and a point P4 on the virtual circumference of the second swirl portion 15b. Because of this, the inner circumferential wall surfaces of the first and second swirl portions 15a and 15b shown in Fig. 6 are shorter by Dl and D2, respectively, than in the heretofore mentioned first embodiment (Fig. 4) . In the second embodiment, too, the angle formed by the first and second wall surfaces 16a and 16b of the swirl passage 16 is determined in the same way as in the heretofore mentioned first embodiment.
[0033]

A description will be given, using Fig. 7, of the flow of fuel in the leading end portion of the fuel injection valve 1 according to the second embodiment. A fuel stagnation portion 163 shown hatched in Fig. 7 is a region, in which a fuel flow f stagnates, between two virtually drawn swirl passages 161, 162. Even without forming the third wall surface 16d in a curved shape, the fuel flow f is divided by the fuel stagnation portion 163, and the divided fuel flows f head forward two respective swirl portions 15, producing swirling flows.
[0034]
Fig. 8 shows a modification example of the leading end portion of the fuel injection valve according to the second embodiment. Figs. 6 and 7 show an example in which the number of injection holes 12 is four, but the number of injection holes 12 can also be eight, as shown in Fig. 8. The number of injection holes 12 is not limited to four or eight.
[0035]
According to the second embodiment, in addition to the same advantageous effects as in the heretofore mentioned first embodiment, by forming the third wall surface 16d in a plane surface, processability and layout properties are still better than in the heretofore described first embodiment. Because of this, it is easy to increase the number of injection holes, enabling a large flow of injection quantity which has been

difficult in the heretofore known configuration.
[0036] Third Embodiment
Fig. 9 is a plan view showing the leading end portion of a fuel injection valve according to the third embodiment, Fig. 10 is a fragmentary enlarged sectional view of the portion shown by B-B as seen in the direction of the arrows in Fig. 9, and Fig. 11 is a plan view showing a modification example of the leading end portion of the fuel injection valve according to the third embodiment. The overall configuration of a fuel injection valve 1 according to the third embodiment is the same as in the heretofore mentioned first embodiment, and so the description of the individual portions will be omitted by borrowing Fig. 1.
[0037]
In the third embodiment, fuel branching blocks 19 which control the flow of fuel are disposed inside a cylindrical cavity 18, thereby forming swirl portions 15 and swirl passages 16. In the example shown in Fig. 9, four fuel branching blocks 19 are radially disposed, with respect to eight injection holes 12, on the outer circumferential side of a valve seat opening portion 10b in the cavity 18.
[0038]
As shown in Fig. 10, the cavity 18 is formed as a recessed portion provided in an upstream side end face 11a of an

injection hole plate 11, and the fuel branching blocks 19 are formed integral with the injection hole plate 11. The fuel branching blocks 19 each have swirl passage forming surfaces 19a, each of which forms the wall surface of the adjacent swirl passage 16, and swirl portion forming surfaces 19b, each of which forms the wall surface of the adjacent swirl portion 15. Also, the fuel branching blocks 19 are each symmetrically shaped about one of the straight lines radially drawn from a center Z of the valve seat opening portion 10b.
[0039]
The swirl passages 16 are each configured by the opposing swirl passage forming surfaces 19a of two adjacent fuel branching blocks 19. A passage width W of the swirl passages 16 increases toward the downstream side (Wl