Patent Application
20180306155
The present invention relates to a fuel injection valve used in an internal combustion engine such as a gasoline engine and to a fuel injection valve which prevents leakage of fuel by bringing a valve body into contact with a valve seat and which performs injection by bringing the valve body out of contact with the valve seat.
In recent years, emission control for automobiles has become strict. In correspondence with this strict emission control, atomization and accurate spraying direction are required of the spraying of a fuel injection valve mounted in an automotive internal combustion engine. Through atomization of the spraying, it is possible to enhance fuel economy. Further, by emitting the spray at aimed positions (e.g., in two directions of the intake valve, it is possible to suppress adhesion of the spray to the wall surface of an intake pipe or the like.
For example, Patent Document 1 discloses a fuel injection valve capable of forming two sprays of satisfactory penetration property. In the fuel injection valve of Patent Document 1, a plurality of fuel injection holes are divided into first and second fuel injection hole sets, with a plane including the axis of the valve hole serving as a boundary. Two spray forms are formed by the fuel ejected from the first and second fuel injection hole sets. In this fuel injection valve, all the fuel injection holes of the first and second sets are formed in the same diameter, and second center lines of the fuel injection holes situated on both outer sides of the sets are inclined toward the front side of an injector plate so as to approach the center of each set or a first center line of the fuel injection hole situated in the vicinity thereof (see the Abstract).
The main mechanism of atomization in an ordinary nozzle plate is as follows.
When the fuel flows into a fuel injection hole (hereinafter referred to as the injection hole), the fuel collides with the inner wall of the injection hole, and there is induced a flow having a large velocity component in a plane perpendicular to the center axis (center line) of the injection hole.
That is, the velocity component in the peripheral direction and the radial direction of the injection hole becomes larger. Hereinafter, this velocity component will be referred to as the in-plane velocity component. On the other hand, the velocity component in the center axis direction of the injection hole will be referred to as the axial velocity component.
Due to this in-plane velocity component, the fuel is easily expanded on the downstream side of the injection hole, and the atomization is promoted.
Thus, the magnitude of this in-plane velocity component greatly affects the atomization of the spray. That is, the larger the force with which the fuel collides with the inner wall surface of the injection hole, the larger the in-plane velocity component, and the more promoted is the atomization.
In the fuel injection valve disclosed in Patent Document 1, however, a plurality of injection holes are divided into two injection hole sets (first and second sets of fuel injection hole sets). Further, in each injection hole set, the injection holes other than both outer sides are arranged such that the extensions of the center axes are parallel and that they are inclined so as to move away from a plane passing the axis of the valve hole of the valve seat member toward the spraying direction to extend in the Y-direction (the boundary direction of the two injection hole sets). In this case, the angle made by the flowing direction of the fuel toward the inlet of the injection hole and the inclination direction of the injection hole (the direction of the center axis) is small. Thus, the collision force (pressing force) of the fuel with respect to the injection hole inner wall is diminished, which hinders the atomization of the spray.
It is an object of the present invention to provide a fuel injection valve which can increase the collision force of the fuel with respect to the injection hole inner wall surface and which can realize a sufficient atomization.
To achieve the above object, an typical example of the present invention provides a fuel injection valve including a valve body that can be displaced in a center axis line direction, a valve seat opening and closing a fuel path in cooperation with the valve body, and a plurality of injection holes provided on a downstream side of the valve seat and configured to eject a fuel having passed through the fuel path to exterior, in which the fuel ejected from the plurality of injection holes of a first injection hole set formed by a plurality of injection holes being at least a part of the plurality of injection holes forms as a whole a first fuel spray directed in a first spraying direction, in which
supposing that the plurality of injection holes constituting the first injection hole set and the first spraying direction in which the first fuel spray is directed are projected on an imaginary plane orthogonal to the center axis line direction, and that an imaginary orthogonal coordinate system which has an imaginary X-axis extending along the first spraying direction and an imaginary Y-axis orthogonal to the imaginary X-axis and which has an origin coinciding with a projection center point obtained through projection of the center axis line onto the imaginary plane is imagined in the imaginary plane, then,
in the imaginary plane, the plurality of injection holes constituting the first injection hole set are formed such that an injection hole center axis extending from an inlet surface toward an outlet surface of the injection hole is formed to extend in a direction different from that of a straight line connecting the origin of the imaginary orthogonal coordinate system and a center of the inlet surface and that a center of the outlet surface is situated close to the imaginary X-axis with respect to the center of the inlet surface.
According to the present invention, it is possible to provide a fuel injection valve which can increase the collision force of the fuel with respect to the injection hole inner wall surface and which can promote the atomization.
Objects, constructions, and effects other than those mentioned above will become apparent from the following description of embodiments.
In the following, an embodiment of the present invention will be described with reference to the drawings. In the following direction, the up-down direction will be defined based on
In the following, the first embodiment of the present invention will be described with reference to
In
Provided at one end surface (upper end surface) of the casing 2 is a fuel supply port 2a, and provided at the other end surface (lower end surface) thereof is a nozzle plate 6 having a plurality of fuel injection holes (injection holes). The nozzle plate 6 is fixed to a nozzle body 5.
The nozzle plate 6 has holes 7 for ejecting fuel (hereinafter referred to as the injection holes) (see
The stationary core 15 is inserted into the casing 2, and is then arranged on the inner side of the solenoid coil 14.
The anchor 4 has a gap between itself and the distal end side end surface of the stationary core 15, and is opposite the distal end side end surface. The anchor 4 is mounted so as to be capable of displacement in the axial direction (the center axis line 1a direction) together with the valve body 3 described below. The anchor 4 is produced through injection molding such as MIM (Metal Injection Molding) using a metal powder consisting of a magnetic material.
The valve body 3 is formed integrally with the anchor 4, and has a hollow rod portion 3a extending in the center axis 102 direction (see
Nozzle body 5 is provided at the distal end side of the valve body 3 and at the proximal end side of the nozzle plate 6. The nozzle body 5 is inserted into the distal end portion of the casing 2, and is fixed to the casing 2 through welding.
There is formed a valve seat surface 5b on which the distal end (the ball valve portion 3b) of the valve body 3 is seated.
The portions of the valve seat surface 5b and the ball valve portion 3b which are in contact with each other constitute a seat portion. When the ball valve portion 3b comes into contact with the valve seat surface 5b, the fuel path is closed, and when the ball valve portion 3b is spaced away from the valve seat surface 5b, the fuel path is opened. That is, the valve body 3 and the valve seat surface (valve seat) 5b cooperate with each other to open and close the fuel path of the seat portion. In some cases, the seat portion of the valve seat surface 5b is referred to as the valve seat. In the present embodiment, there is no need in particular to distinguish the valve seat surface 5b and the seat portion from each other, and the valve seat may be either of the valve seat surface 5b and the seat portion.
The nozzle plate 6 is arranged at the distal end side end surface of the nozzle body 5. The nozzle plate 6 is provided with a plurality of injection holes 7 formed so as to extend through it in the thickness direction. The injection holes 7 are provided on the downstream side of the valve seat surface 5b, and eject the fuel having passed through the fuel path of the seat portion to the exterior. The surface of the nozzle plate 6 in contact with the nozzle body 5 is bonded through welding.
In
Further, arranged at the fuel supply port 2a is a filter 20, which removes foreign matter contained in the fuel. Further, mounted to the outer periphery of the fuel supply port 2a is an O-ring 21 for sealing the fuel supplied. In the vicinity of the fuel supply port 2a, there is provided a resin cover 22. The resin cover 22 is provided so as to cover the casing 2 and the yoke 16 by means such as resin molding. The resin cover 22 contains a connector 23 for supplying power to the solenoid coil 14.
A protector 24 is provided at the distal end portion of the fuel injection valve 1, and consists, for example, of a cylindrical member formed of a resin material or the like, covering the outer peripheral surface of the distal end side portion of the casing 2. At the upper end portion of the protector 2, there is formed a flange portion 24a protruding radially outwards from the outer peripheral surface of the casing 2. An O-ring 25 is attached to the outer periphery of the distal end side portion of the casing 2. The O-ring 25 is arranged between the yoke 16 and the flange portion 24a of the protector 24 so as to be prevented from detachment. When, for example, the distal end side portion of the casing 2 (the fuel injection valve 1) is mounted to a mounting portion (not shown) or the like provided in the intake pipe of the internal combustion engine, the O-ring 25 seals between the fuel injection valve 1 and the mounting portion.
In the fuel injection valve 1 constructed as described above, when the solenoid coil 14 is in the non-energized state, the distal end of the valve body 3 comes into close contact with the nozzle body 5 due to the pressing force of the spring 12. In this state, a gap, that is, a fuel path, is not formed between the valve body 3 and the nozzle body 5, so that the fuel having flowed in via the fuel supply port 2a remains within the casing 2.
When an electric current as an injection pulse is applied to the solenoid coil 14, a magnetic flux is generated in the magnetic circuit formed by the yoke 16, the core 15, and the anchor 4 formed of a magnetic material. Due to the electromagnetic force of the solenoid coil 14, the anchor 4 moves until it comes into contact with the lower end surface of the core 15. When the valve body 3 moves to the core 15 side together with the anchor 4, a fuel path is formed between the valve portion 3b of the valve body 3 and the valve seat surface 5b of the nozzle body 5. After having flowed in from the periphery of the valve portion 3b, the fuel inside the casing 2 is ejected from the fuel injection holes 7 (see
The fuel injection amount is controlled as follows: in correspondence with the injection pulses intermittently applied to the solenoid coil 14, the valve body 3 (the valve portion 3b) is moved in the axial direction, whereby the timing of switching between the open state and the closed state is adjusted.
As shown in
Further, in the nozzle body 5, the angle of the inclined surface (the valve seat surface 5b) including the seat position coming into close contact with the valve body 3 is approximately 90° (from 80° to 100°). This inclination angle is an optimum angle for polishing the portion around the seat position and enhancing the circularity (allowing the grinding machine to be used in the best condition). This angle helps to maintain a very high level of seat property with respect to the valve body 3. The nozzle body 5 having the inclined surface including the seat position is enhanced in hardness through quenching. Further, unnecessary magnetism is removed therefrom through demagnetization processing. Due to this valve body construction, an injection amount control free from fuel leakage is possible. Further, it is possible to provide a valve body structure superior in cost performance.
To be formed in a downwardly convex configuration, the nozzle plate 6 undergoes extrusion by a punch in the manufacturing process for forming a convex surface.
When the fuel injection valve 1 is in the closed state, the valve body 3 comes into contact with the valve seat surface 5b consisting of a conical surface provided on the nozzle body (the seat member) 5 bonded to the casing 2 by welding or the like to thereby maintain the fuel in the sealed state. The contact portion on the valve body 3 side is formed by a spherical surface, and the valve seat surface consisting of a conical surface and the spherical surface are substantially brought into line contact with each other.
When the valve body 3 is raised to generate a gap between the valve body 3 and the nozzle body 5, the fuel flows out through the gap, and, at the opening 5c of the nozzle body 5, collides with the upper surface of the nozzle plate 6 from the direction of the arrow 17.
Thereafter, as indicated by the arrows 18, the fuel flows from the center of the nozzle plate 6 radially outwards along the surface of the nozzle plate 6. In this process, due to the downwardly convex configuration of the nozzle plate 6, the velocity of the fuel near the surface of the nozzle plate 6 is high. Then, after passing through the injection holes 7, the fuel forms liquid films 9, which are divided into droplets 10 due to instability because of the capillary wave and the shearing force with respect to the air, thus attaining atomization of the fuel.
In
The configuration of the injection holes 7 of the present embodiment will be described in detail with reference to
The axis passing the center O of the nozzle plate 6 and extending in the horizontal direction of
Suppose that the region where X>0 and Y>0 is the first quadrant, that the region where X<0 and Y>0 is the second quadrant, that the region where X<0 and Y<0 is the third quadrant, and that the region where X> and Y<0 is the fourth quadrant. In the present embodiment, the injection holes 7a, 7b, and 7c are arranged in the first quadrant, the injection holes 7a′, 7b′, and 7c′ are arranged in the second quadrant, the injection holes 7d′, 7e′, and 7f′ are arranged in the third quadrant, and the injection holes 7d, 7e, and 7f are arranged in the fourth quadrant.
The injection hole set formed by the injection holes 7a, 7b, 7c, 7d, 7e, and 7f will be referred to as the first injection hole set 7A, and the injection hole set formed by the injection holes 7a′, 7b′, 7c′, 7d′, 7e′, and 7f′ will be referred to as the second injection hole set 7B. The injection holes 7a, 7b, 7c, 7d, 7e, and 7f of the first injection hole set 7A eject the fuel in a direction as a whole to form a first fuel spray. The injection holes 7a′, 7b′, 7c′, 7d′, 7e′, and 7f′ of the second injection hole set 7B eject the fuel in a direction different from that of the first injection hole set 7A as a whole to form a second fuel spray.
With the X-axis being the boundary, the first injection hole set 7A is divided into a first group 7A1 consisting of the injection holes 7a, 7b, and 7c, and a second group 7A2 consisting of the injection holes 7d, 7e, and 7f. With the X-axis being the boundary, the second injection hole set 7B is divided into a first group 7B1 consisting of the injection holes 7a′, 7b′, and 7c′, and a second group 7B2 consisting of the injection holes 7e′ and 7f′.
In the case where there is no need in particular to distinguish the injection holes 7a, 7b, 7c, 7d, 7e, 7f, 7a′, 7b′, 7c′, 7d′, 7e′, and 7f′ from each other, they will be simply referred to as injection holes (fuel injection holes) 7.
In
The arrows 11 indicate the inclination directions of the injection holes 7. That is, when the center axis 71 of each injection hole 7 (see
The center axes 71 of the injection holes 7a, 7b, and 7c are inclined such that the X-coordinate of the injection hole outlet surface center is larger than the X-coordinate of the injection hole inlet surface center, and that the Y-coordinate of the injection hole outlet surface center is smaller than the Y-coordinate of the injection hole inlet surface center. The center axes 71 of the injection holes 7d, 7e, and 7f are inclined such that the X-coordinate of the injection hole outlet surface center is larger than the X-coordinate of the injection hole inlet surface center, and that the Y-coordinate of the injection hole outlet surface center is smaller than the Y-coordinate of the injection hole inlet surface center.
That is, in the present embodiment, in the imaginary plane of
In the present embodiment, the injection holes 7a, 7b, and 7c of the first injection hole set 7A are arranged such that the interval of the adjacent injection holes (the distance between the centers of the inlet surfaces) 1 is equal. Further, the injection holes 7a, 7b, and 7c are arranged in the circumference of an arrangement circle 80 the center of which is the center O of the nozzle plate 6 (the origin of the imaginary orthogonal coordinate system). Thus, the injection holes 7a, 7b, and 7c are arranged at equal angular intervals around the point O. The injection holes 7d, 7e, and 7f of the first injection hole set 7A are arranged such that the interval of the adjacent injection holes (the distance between the centers of the inlet surfaces) 1 is equal. Further, the injection holes 7d, 7e, and 7f are arranged in the circumference of the arrangement circle 80 the center of which is the center O of the nozzle plate 6 (the origin of the imaginary orthogonal coordinate system). Thus, the injection holes 7d, 7e, and 7f are arranged at equal angular intervals around the point O.
On the front side in the fuel injection direction, the injection holes 7a, 7b, and 7c of the first group 7A1 and the injection holes 7d, 7e, and 7f of the second group 7A2 are inclined such that the farther from the nozzle plate 6, the closer the center axes 71 of the injection holes (the arrows 11).
Of the injection holes 7a, 7b, and 7c of the first group 7A1, the injection hole 7c is arranged closest to the X-axis, and closest to the second group 7A2. Of the injection holes 7d, 7e, and 7f of the second group 7A2, the injection hole 7d is arranged closest to the X-axis, and closest to the first group 7A1. The interval L between the injection holes 7c and 7d adjacent to each other with the X-axis therebetween is larger than the interval 1 between the injection holes 7a, 7b, and 7c and the interval 1 between the injection holes 7f, 7e, and 7d of the first injection hole set 7A.
The interval L is the minimum of the distances between the centers of the inlet surfaces (inlet opening surfaces) of the injection holes 7a, 7b, and 7c of the first group 7A1 and the distances between the centers of the inlet surfaces (inlet opening surfaces) of the injection holes 7d, 7e, and 7f of the second group 7A2.
That is, in the present embodiment, the inter-group inter-hole distance L, which is the minimum of the inter-group inter-hole distances formed between the inlet surface centers of the injection holes of the plurality of injection holes 7a, 7b, 7c (7a′, 7b′, 7c′) constituting the first group 7A1 (7B1) and the plurality of injection holes 7d, 7e, 7f (7d′, 7e′, 7f′) constituting the second group 7A2 (7B2) is set to be larger than the maximum in-group inter-hole distance 1 of the in-group inter-hole distance 1 within the plurality of injection holes 7a, 7b, 7c (7a′, 7b′, 7c′) constituting the first group 7A1 (7B1) formed between the inlet surface centers of the plurality of injection holes 7a, 7b, 7c (7a′, 7b′, 7c′) and the in-group inter-hole distances 1 within the plurality of injection holes 7d, 7e, 7f (7d′, 7e′, 7f′) constituting the second group 7A2 (7B2) formed between the inlet surface centers of the plurality of injection holes 7d, 7e, 7f (7d′, 7e′, 7f′).
From a different point of view, the injection holes are arranged such that the inter-group distance in the injection hole sets 7A and 7B (the distance between the first group 7A1, 7B1 and the second group 7A2, 7B2) is larger than the maximum inter-hole distance (the maximum value of the inter-center distance of the injection hole inlet surface) of the injection holes 7a through 7c, 7d through 7f, 7a′ through 7c′, and 7d′ through 7f′ constituting the groups 7A1, 7B1, 7A2, and 7B2 in the injection hole sets 7A and 7B. Here, the distance between the first group 7A1, 7B1 and the second group 7A2, 7B2 is the inter-center distance between the inlet surfaces of the two injection holes arranged closest to each other between the groups.
The injection holes 7a′, 7b′, 7c′, 7d′, 7e′, and 7f′ are in plane symmetry with respect to a plane passing the injection holes 7a, 7b, 7c, 7d, 7e, and 7f, and the Y-axis and perpendicular to the plane of
Due to the above arrangement of the injection holes and the inclination direction of the injection holes, when seen from the −Y-direction, the spray ejected from the nozzle plate 6 form sprays 31 and 32 in two directions. That is, the fuel having passed the injection holes 7a, 7b, 7c, 7d, 7e, and 7f forms the spray 31, and the fuel having passed the injection holes 7a′, 7b′, 7c′, 7d′, 7e′, and 7f′ forms the spray 32. Further, when seen from the +X-direction, there is formed a spray in one direction. In this way, in the present construction, it is possible to form sprays in two directions, which is to be aimed at.
Further, in the above construction, it is possible to promote atomization of the fuel. In the following, the atomization mechanism in the present embodiment will be described.
In the following, a comparative example related to the present invention will be described. The components that are the same as those of the first embodiment will be indicated by the same reference numerals, and a description thereof will be left out.
As in the first embodiment, also in the present comparative example, all the injection holes 7′ are arranged in the circumference of the arrangement circle 80′ the center of which is the center O′ of the nozzle plate 6′.
In the case where projection is made onto a plane similar to the section A-A of
In this case, the fuel 17 having passed the opening 5c of the fuel path portion collides with the upper surface of the nozzle plate 6′, and forms a flow 18 at high speed along the wall surface of the nozzle plate 6′. Then, it flows into the injection hole 7′. At this time, the injection hole 7′ is inclined so as to be opposite the flow 18, so that the fuel 103a having flowed into the injection hole 7′ collides with the wall surface 72 of the injection hole 7′, and there is induced within a plane perpendicular to the center axis 73 of the injection hole 7′ a flow 103b having a large velocity component. That is, the flow 103b has a large velocity component in the peripheral direction and the radial direction of the injection hole 7′.
As a result, when the fuel forms the liquid film 9′ under the injection hole, it is likely to be divided into droplets 10′, thus promoting atomization. It should be noted, however, that while the injection hole arrangement and the injection hole inclination direction shown in
Next, the nozzle plate 6″ of the second comparative example of the present invention will be described with reference to FIGS. 8 and 9.
In the second comparative example, in order to form sprays in two directions, from the inlet surface toward the outlet surface of the injection hole 7″, the injection hole 7″ is inclined so as to be spaced away from the center of the nozzle plate 6″. In this case, as shown in
Thus, to promote the atomization, it is desirable for the injection hole to be inclined as much as possible so as to be opposite the flow of the fuel flowing into the injection hole. However, when the injection hole is inclined so as to be completely opposite the liquid flow flowing into the injection hole, it is difficult to form sprays in two directions. On the other hand, when the injection hole is inclined in the same direction as the fuel flow flowing into the injection hole in the inclination direction, that is, outwardly with respect to the center of the nozzle plate, it is easy to form sprays in two directions. The atomization, however, is hard to realize.
In the nozzle plate 6 of the present embodiment, the injection holes 7a through 7f and 7a′ through 7f′ are arranged such that the distance between the first injection hole set and the second injection hole set, that is, the distance between the injection hole 7c (7c′) and 7d (7d′), is larger than the maximum inter-hole distance, of the maximum inter-hole distance between the injection holes 7a through 7c in the first group and the maximum inter-hole distance between the injection holes 7e and 7f in the second group. Further, in the nozzle plate 6 of the present embodiment, the injection holes 7a through 7f and 7a′ through 7f′ are inclined such that the outlet surfaces approach a plane including the center axis 102 of the nozzle plate 6 with respect to the inlet surfaces. This plane is a plane including the center axis 102 and the X-axis. Due to this construction, it is possible to realize spraying in two directions, and further, to promote atomization.
The injection hole inclination direction will be described more specifically.
The injection holes 7a and 7b are of the same concept as the injection hole 7c described below. The injection holes 7d, 7e, and 7f are in plane symmetry with the injection holes 7a, 7b, and 7c with respect to a plane passing the X-axis and perpendicular to the plane of the drawing (a plane passing the X-axis and perpendicular to the Y-axis).
The axis passing the center 7cio of the inlet surface 7ci of the injection hole 7c and parallel to the X-axis will be referred to as the X′-axis, and the axis passing the center 7cio of the inlet surface 7ci of the injection hole 7c and parallel to the Y-axis will be referred to as the Y′-axis. The circle passing the center 7cio of the inlet surface 7ci of the injection hole 7c and having the origin O of the X-axis and the Y-axis as its center will be referred to as the arrangement circle 80.
In the present embodiment, the inclination angle of the injection hole 7c is set to the range θa of
By inclining the injection hole 7c as described above, the center of the outlet surface of the injection hole 7c is situated in the range of the X′-axis where X′>0 and in the range of the Y′-axis where Y′<0. As a result, it is possible to form spraying in two directions and to promote the atomization. In this setting of the inclination angle, the X′-axis and the Y′-axis are not included in the setting range of the center position of the outlet surface of the injection hole 7c.
When the synthetic (total) ejecting direction of the spray ejected from the injection holes 7a through 7f arranged in the first injection hole set 7A is projected onto
On the other hand, when the Y′-axis is included in the setting range of the center position of the outlet surface of the injection hole 7c (that is, when the Y′-axis is included in the inclination direction of the injection hole 7c), the ejecting direction of the injection hole 7c is a direction parallel to a plane passing the Y-axis of
However, for example, the synthetic (total) ejecting direction of the spray ejected from the injection holes 7a through 7f arranged in the first injection hole set 7A is set as a direction parallel to the Y-axis of
Further, it is advisable to set the inclination angle of the injection hole 7c restrictively to the range of θb. That is, the injection hole 7c is inclined so as to be directed to the angle range made by the tangent 80a at the injection hole center position of the arrangement circle 80 and the portion of the Y′-axis where Y′<0. This angle range is an angle range configured within a range where Y′<0. At this time, the center of the outlet surface of the injection hole 7c is situated in the range where Y′<0 and in the range between the tangent 80a and the portion of the Y′-axis where Y′<0. As a result, it is possible to further promote the atomization. In this case, the injection hole 7c may be inclined along the tangent 80a. At this time, the center of the outlet surface of the injection hole 7c is arranged on the tangent 80a.
The angle range θb made by the tangent 80a and the portion of the Y′-axis where Y′<0 substantially coincides with the range where X′>0 and the range on the inner side of the arrangement circle 80. Thus, the injection hole 7c may be inclined in the range where X′>0 and the range on the inner side of the arrangement circle 80. In this case, the center of the outlet surface of the injection hole 7c is situated in the range where X′>0 and the range on the inner side of the arrangement circle 80.
When the spray ejected from the injection hole 7c of the first group 7A1 and the spray ejected from the injection hole 7d of the second group 7A2 interfere with each other directly below the injection holes, there is the possibility of the atomization performance being deteriorated.
In the present embodiment, there are formed combinations of injection holes in which the mutual center axes 71 are arranged so as to cross each other between the injection holes 7a through 7c of the first group 7A1 and the injection holes 7d through 7f of the second group 7A2. Of the injection hole combinations in which the mutual center axes 71 cross each other, the combination of the injection hole 7c and the injection hole 7d is the combination in which the inter-center distance L is minimum.
Assuming that the inclination of the injection hole 7c in the section B-B in the horizontal direction is a, that the inclination of the injection hole 7d with respect to the horizontal direction is 3, that the inter-center distance of the injection hole 7c and the injection hole 7d is L, the point at which the center axis 7ca of the injection hole 7c and the center axis 7da of the injection hole 7d intersect with each other is Q, and that the distance in the height direction between the straight line (segment) 150 connecting the center 7cio of the inlet surface 7ci of the injection hole 7c and the center 7dio of the inlet surface 7di of the injection hole 7d (the length of the normal extending to the straight line 150) is X, X is expressed by equation (1).
At this time, when a and 3 are set such that X is 2 mm or more, it is possible to suppress the influence of the spray interference and to promote the atomization. More preferably, X is 5 mm or more, and, most preferably, X is 7 mm or more.
In the case where the construction of the fuel injection valve of Patent Document 1 is applied to the present embodiment, the distance (inlet surface inter-center distance) between the injection hole 7a (7f) situated at the end of the first injection hole set 7A in the circumference of the arrangement circle 80 and the injection hole 7a′ (7f′) situated at the end of the second injection hole set in the circumference of the arrangement circle 80 is larger than the interval (inlet surface inter-center distance) of the injection holes 7a through 7f in the first injection hole set 7A and the interval (inlet surface inter-center distance) of the injection holes 7a′ through 7f′ in the second injection hole set 7B.
On the other hand, in the present embodiment, the inter-center distance of the inlet surfaces of the injection holes is set such that the inter-group inter-hole distance L that is the minimum of the first injection hole set 7A and the inter-group inter-hole distance L that is the minimum of the second injection hole set 7B are larger than the inter-center distance of the inlet surfaces of the two injection holes 7a (7f) and the 7a′ (7f′) closest to each other between the plurality of injection holes 7a through 7f constituting the first injection hole set 7A and the plurality of injection holes 7a′ through 7f′ constituting the second injection hole set 7B.
That is, in the present embodiment, the two injection holes the inlet surface inter-center distance (L) of which set large exist in the same injection hole set. As described above, this is due to the fact that the center axes of the injection holes of the same injection hole set are inclined so as to approach each other on the front side of the ejecting direction. This construction is adopted in order to prevent a plurality of sprays from colliding each other at a position close to the injection holes.
Also in the fuel injection valve 1 of the present embodiment, the inter-center distance between the inlet surface of the injection hole 7a situated at the end of the first injection hole set 7A in the circumference of the arrangement circle 80 and the inlet surface of the injection hole 7a′ situated at the end of the second injection hole set 7B in the circumference of the arrangement circle 80 may be larger than the inter-center distance 1 of the inlet surfaces of the other injection holes. The inter-center distance between the inlet surface of the injection hole 7f situated at the end of the first injection hole set 7A in the circumference of the arrangement circle 80 and the inlet surface of the injection hole 7f′ situated at the end of the second injection hole set 7B in the circumference of the arrangement circle 80 may be larger than the inter-center distance 1 of the inlet surfaces of the other injection holes.
However, to make the inter-center distance L between the inlet surface of the injection hole 7c, 7c′ and the inlet surface of the injection hole 7d, 7d′, there is limitation to the space for the arrangement of the injection holes 7 in the circumference of the arrangement circle 80. Thus, it is desirable that that the inter-center distance between the inlet surface of the injection hole 7a and the inlet surface of the injection hole 7a′ and the inter-center distance between the inlet surface of the injection hole 7f and the inlet surface of the injection hole 7f′ be smaller than the inter-center distance L.
Next, the second embodiment of the present invention will be described with reference to
The difference of the present embodiment from the first embodiment is that the injection holes 7c and 7c′ are arranged in the X-axis and that the inclination direction of the injection holes 7c and 7c′ is directed radially outwards with respect to the center of the nozzle plate 6. In this case, the injection holes are arranged such that the distance between the injection hole 7b and the injection hole 7d (the inter-center distance between the inlet surface of the injection hole 7b and the inlet surface of the injection hole 7d) L is larger than the distance between the injection hole 7a and the injection hole 7b (the inter-center distance between the inlet surface of the injection hole 7a and the inlet surface of the injection hole 7b) 1.
The injection holes 7a′, 7b′, 7c′, 7d′, and 7e′ are in plane symmetry with the injection holes 7a, 7b, 7c, 7d, and 7e with respect to a plane passing the Y-axis and perpendicular to the plane of
In the case of the present embodiment, the center axis (ejecting direction) of the injection hole 7c exhibits the maximum X coordinate value of the first injection hole set 7A. Further, the center axis (ejecting direction) of the injection hole 7c exists in a plane passing the X-axis and perpendicular to the Y-axis, so that it does not cross the center axes of the other injection holes 7a, 7b, 7d, and 7e of the first injection hole set 7A. Like the injection hole 7c of the first injection hole set 7A, the center axis (ejecting direction) of the injection hole 7c′ of the second injection hole set 7B does not cross the center axes of the other injection holes 7a′, 7b′, 7d′, and 7e′ of the second injection hole set 7B. Thus, there is no need in particular for the injection hole 7c and the injection hole 7c′ to take into consideration the distance to the other injection holes.
The center axis (ejecting direction) of the injection hole 7c of the first injection hole set 7A may cross the center axes of the other injection holes 7a, 7b, 7d, and 7e of the first injection hole set 7A. In this case, however, it is necessary to take into account the inter-hole distance or the injection hole inclination angle so that the positions where the center axis of the injection hole 7c crosses the center axes of the other injection holes 7a, 7b, 7d, and 7e may be spaced away to some degree from the outlets of the injection holes. The center axis (ejecting direction) of the injection hole 7c′ of the second injection hole set 7B may cross the center axes of the other injection holes 7a′, 7b′, 7d′, and 7e′ of the second injection hole set 7B. In this case, however, it is necessary to take into account the inter-hole distance or the injection hole inclination angle so that the positions where the center axis of the injection hole 7c′ crosses the center axes of the other injection holes 7a′, 7b′, 7d′, and 7e′ may be spaced away to some degree from the outlets of the injection holes.
The injection holes 7a, 7b, 7d, and 7e and the injection holes 7a′, 7b′, 7d′, and 7e′ are injection holes arranged in plane symmetry with respect to a plane passing the Y-axis and perpendicular to the X-axis. With respect to the injection holes thus arranged with the X-axis therebetween, the inlet surface inter-center distance must be set as described above.
In the structure of the present embodiment, the injection holes 7c and 7c′ can easily form a two-way spray, and, as in the first embodiment, the injection holes 7a, 7b, 7d, 7e, 7a′, 7b′, 7d′, and 7e′ can promote the atomization. That is, the role allotment is established as follows: the injection holes 7c and 7c′ form a two-way spray, and the injection holes 7a, 7b, 7d, 7e, 7a′, 7b′, 7d′, and 7e′ promote the atomization. Due to this arrangement, it is advantageously possible to facilitate the control of the spraying angle.
The third embodiment of the present invention will be described with reference to
In the first embodiment described above, the nozzle plate 6 has the downwardly convex configuration 6a. In the present embodiment, the portion of the nozzle plate 6 near the center thereof (the portion in the vicinity of the center axis 102 and opposite the opening 5c) exhibits a downwardly convex configuration 6a, whereas the portion where the injection holes 7 are formed of a planar structure. Otherwise, this embodiment is of the same construction as the first embodiment and the second embodiment.
In this structure, the fuel having passed between the valve seat surface 5b and the distal end portion 3b of the valve body 3 passes through the opening 5c, and collides with the upper surface of the nozzle plate 6 from the direction of the arrow 17. After this, as indicated by the arrow 18, the fuel flows from the center of the nozzle plate 6 radially outwards along the surface of the nozzle plate 6. Since the portion of the nozzle plate 6 near the center is of a downwardly convex configuration 6a, the velocity of the fuel near the surface of the nozzle plate is high. After passing the injection holes 7, the fuel forms the liquid films 9, which are divided into the droplets 10 due to instability because of the capillary wave and the shearing force with respect to the air, thus attaining atomization of the fuel.
By thus providing the downwardly convex configuration 6a, it is possible to increase the velocity in the vicinity of the surface of the nozzle plate 6 and to promote the atomization. By forming the portion where the injection holes 7 are installed in a planar structure, the machining accuracy of the injection holes 7 is improved, and the control of the fuel spraying direction is facilitated. At the same time, it is possible to diminish the interval between the nozzle plate 6 and the seal member 5a, and to diminish the volume of the space surrounded by the nozzle plate 6, the valve seat surface 5b, and the valve body 3. By thus diminishing the volume, it is possible to accurately spray the fuel in the target amount.
The fourth embodiment of the present invention will be described with reference to
As shown in
Otherwise, this embodiment is of the same construction as the first through third embodiments.
In this case, the control of the fuel spraying direction is facilitated, and the machining is very easy to perform.
The fourth embodiment of the present invention will be described with reference to
In embodiment 1 described above, all the injection holes 7 are arranged in the same arrangement circles. In the present embodiment, the injection holes 7 are arranged in a plurality of arrangement circles 80, 81.
As the first group 7A1 of the first injection hole set 7A, there are provided the injection holes 7a, 7b, and 7c. As the second group 7A2 of the first injection hole set 7A, there are provided the injection holes 7d, 7e, and 7f. As the first group 7B1 of the second injection hole set 7B, there are provided the injection holes 7a′, 7b′, and 7c′. As the second group 7B2 of the second injection hole set 7B, there are provided the injection holes 7d′, 7e′, and 7f′.
In this case, the inter-group distance in the injection hole set is the distance L between the injection holes 7b, 7b′ and the injection holes 7e, 7e′, and the injection holes 7 are arranged such that L is larger than the maximum inter-hole distance (the inter-center distance of the injection hole inlet surfaces) of the injection holes 7a through 7c, 7d through 7f, 7a′ through 7c′, and 7d′ through 7f′ constituting the groups in the injection hole sets.
Due to this construction, it is possible to attain the same effect as that of embodiment 1, and the control of the spraying angle is facilitated.
Further, by enlarging the inter-group distance L, the injection hole arrangement space in one arrangement circle 80 is diminished. Thus, a plurality of injection holes 7 are arranged in the plurality of arrangement circles 80 and 81 in a dispersed fashion, whereby it is possible to arrange a large number of injection holes. Or, it is possible to prevent concentration of a large number of injection holes in a small space, so that the strength of the nozzle plate 6 is not lowered.
Also in the present embodiment, with respect to the inclination direction of the injection holes 7, it is advisable to apply the angle ranges ea and 8b described with reference to
The present invention is not restricted to the embodiments described above but includes various modifications. For example, while the above embodiments are described in detail in order to facilitate the understanding of the present invention, the present invention is not always restricted to a construction equipped with all the components described above. Further, it is possible to replace a part of the construction of a certain embodiment by the construction of another embodiment, and it is also possible to add the construction of another embodiment to the construction of a certain embodiment. Further, with respect to a part of the construction of each embodiment, addition, deletion, and replacement of another construction are possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-230559 | Nov 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/077839 | 9/21/2016 | WO | 00 |
