Claims:We Claim:

1. A fuel injection valve comprising:
a valve seat (12) having a valve-seat opening portion (12d) for making a fuel flow out;
a valve body (10) for opening or closing the valve-seat opening portion (12d); and
an injection hole plate (13) that is disposed at a downstream side of a flow of the fuel in such a way as to face the valve-seat opening portion (12d) and that has two or more injection hole portions (14)for injecting the fuel to the outside;
wherein injection of the fuel from the injection hole portion (14) is controlled by making the valve body (10) travel in an axial direction of the valve seat (12), based on an operation signal from an external control apparatus, so that the valve-seat opening portion (12d) is opened or closed,
wherein the injection hole plate (13) includes, in an endface thereof at an upstream side of the fuel flow,
two or more swirling chambers (13c) arranged at a radially outside of the valve-seat opening portion (12d),
a central portion (13a) to be connected with the valve-seat opening portion (12d), and

two or more introduction portions (13b) that each guide the fuel from the central portion (13a) to the respective swirling chambers (13c),
wherein the introduction portion (13b) has a first side wall portion (13b1) and a second side wall portion (13b2) that face each other across a center axis of said introduction portion (13b),
wherein a center of the injection hole portion (14) is provided in such a way as to be offset toward the first side wall portion (13b1) with respect to the center axis of the introduction portion (13b) and in such a way as to coincide with a center of the swirling chamber (13c),
wherein the swirling chamber (13c) has a curved-surface wall portion (13c1) formed of part of a virtual arc,
wherein the curved-surface wall portion (13c1) is connected with the first side wall portion (13b1) through the intermediary of a straight-surface wall portion (13c2) that extends linearly, and
wherein letting T denote a shortest distance between the center axis of the introduction portion (13b) and the center of the injection hole portion (14) and letting G denote a shortest distance between the center of the injection hole portion (14) and the straight-surface wall portion (13c2), the straight-surface wall portion (13c2) is disposed within a range that satisfies [0.8T ? G ? 1.2T].

2. The fuel injection valve according to claim 1, wherein letting w denote a shortest distance between the center axis of the introduction portion (13b) and the first side wall portion (13b1) and letting fDf denote a diameter of the injection hole portion (14), the shortest distance T between the center axis of the introduction portion (13b) and the center of the injection hole portion (14) is set to a value that satisfies [w < T ? w + fDf/2].

3. The fuel injection valve according to any one of claims 1 and 2, wherein letting L denote a length of the first side wall portion (13b1) and letting M denote a length of the second side wall portion (13b2), the first side wall portion (13b1) and the second side wall portion (13b2) are configured in such a way as to satisfy [0.1M ? L ? M - 0.18].

4. The fuel injection valve according to any one of claims 1 through 3, wherein letting M denote the length of the second side wall portion (13b2) and letting r denote a radius of a virtual circumscribing circle that circumscribes the two or more swirling chambers (13c), the radius r of the virtual circumscribing circle has a value that satisfies the following equation.

5. The fuel injection valve according to any one of claims 2 through 4, wherein the straight-surface wall portion (13c2) is provided at a position that is adjacent to or overlaps a tangential line in contact with a virtual circle that has a radius of the shortest distance between the center axis of the introduction portion (13b) and the center of the injection hole portion (14) and whose center coincides with the center of the injection hole portion (14).

Dated this 29th day of October, 2021
FOR MITSUBISHI ELECTRIC CORPORATION
By their Agent

(ANSHUL SUNILKUMAR SAURASTRI) (IN/PA 3086)
KRISHNA & SAURASTRI ASSOCIATES LLP , Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

FUEL INJECTION VALVE;

MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

BACKGROUND OF THE INVENTION
Field of the Invention
[0001]
The present disclosure relates to a fuel injection valve.

Description of the Related Art
[0002]
In recent years, the exhaust-gas regulation on an automobile internal combustion engine has been tightened; with regard to fuel spray to be injected from a fuel injection valve, it has been required that in consideration of its adhesion to an intake-pipe wall surface, fuel spray is sufficiently micronized while the spraying angle is suppressed from excessively expanding; thus, there have been made various studies related to a method in which the micronization is performed by use of a swirling flow.
[0003]
For example, Patent Document 1 discloses a fuel injection valve in which there are provided a valve seat having a valve seat opening portion through which fuel from the upstream side passes, a valve body for opening or closing the valve seat opening portion, and an injection hole plate that is provided at the downstream side of the valve seat and forms a swirling flow of fuel, in which at the upstream side of the injection hole plate, a radial recess having a branch portion, an introduction portion, a cylinder portion, and a swirling portion is formed, in which at the downstream side of the cylinder portion, an injection hole is formed, and in which the size of the flow path including the swirling portion is regulated so that further micronization of spray is realized.
[0004]
Patent Document 1 describes that the terminal surface of the swirling portion in the injection hole plate is slanted by an angle of ? from the center axis of the introduction portion, that when the angle ? is in a range from 0° to 45°, a flow A that directly flows into the cylinder portion from the introduction portion and a flow B that flows into the cylinder portion by way of the swirling portion face each other, and that when letting W1 denote the width of the introduction portion and letting W2 denote the width of the swirling portion, the equation [0.3 ? W2/W1 ? 0.7] is established, the respective strengths of the flow A and the flow B become substantially equal to each other. It is argued that because as a result, a swirling flow is homogenous and hence the thickness of a fuel liquid film formed on the inner wall of the injection hole portion is uniform, the micronization degree becomes excellent.
[0005]
In contrast, in the foregoing conventional fuel injection valve, disclosed in Patent Document 1, in which a swirling flow makes fuel become a thin film and then the thin film is split so as to be micronized, although enhancement of the swirling force of the fuel facilitates expansion of the liquid film and hence the micronization is facilitated, the spraying angle is concurrently expanded.
[Prior Art Reference]
[Patent Document]
[0006]
[Patent Document 1] International Publication No. WO2017/060945

SUMMARY OF THE INVENTION
[0007]
In the conventional fuel injection valve disclosed in Patent Document 1, as described above, there has been a problem that although enhancement of swirling force facilitates expansion of a liquid film and hence micronization is facilitated, the spraying angle is concurrently and largely expanded.
[0008]
As a spray-angle adjusting method for obtaining a target spray angle, various kinds of methods are conceivable; paying attention to the length of the introduction portion, fuel that diffuses from the central portion of the injection hole plate is rectified when passing through the introduction portion, changes into a swirling flow in a swirling chamber, and then is injected from the injection hole portion. In this situation, the fuel that has been sufficiently rectified in the introduction portion becomes a uniform swirling flow in the swirling chamber; thus, the process of becoming a thin film is further facilitated and hence the fuel spray is micronized.
[0009]
Accordingly, in terms of suppressing expansion of injected spray by adjusting swirling force, the length of the introduction portion that determines the rectification degree is an importance parameter. The rectification degrees, i.e., the swirling forces of the fuel flow A and the fuel flow B can be adjusted by adjusting the length L of a first side wall portion and the length M of a second side wall portion, respectively.
[0010]
In the conventional fuel injection valve disclosed in Patent Document 1, the introduction portion is connected with the cylinder portion and the swirling portion and the swirling portion is formed in such a way as to enclose the cylinder portion; thus, a change in the length of the introduction portion concurrently changes the respective lengths of the first side wall portion and the second side wall portion and hence both of the respective swirling forces of the flow A and the flow B are changed; therefore, the change in the length of the introduction portion largely affects the micronization of the fuel, the injection flow rate, and the like. Moreover, a change in the width of the introduction portion or a change in the offset amount of the injection hole portion causes a change in the diameter of the swirling chamber, causes a large change in the swirling force, and hence causes a conspicuous change in not only the micronization performance but also the injection flow rate; thus, the designing man-hours for obtaining a target spray angle while maintaining a required flow rate becomes excessively large.
[0011]
The present disclosure has been implemented in order to solve the foregoing problems; the objective thereof is to provide a fuel injection valve that enhances the fuel-spray micronization performance and has a desired spray angle for fuel spray.
[0012]
A fuel injection valve disclosed in the present disclosure includes a valve seat having a valve-seat opening portion for making a fuel flow out, a valve body for opening or closing the valve-seat opening portion, and an injection hole plate that is disposed at a downstream side of a flow of the fuel in such a way as to face the valve-seat opening portion and that has two or more injection hole portions for injecting the fuel to the outside; injection of the fuel from the injection hole portion is controlled by making the valve body travel in an axial direction of the valve seat, based on an operation signal from an external control apparatus, so that the valve-seat opening portion is opened or closed. The fuel injection valve is characterized
in that the injection hole plate includes, in an endface thereof at an upstream side of the fuel flow,
two or more swirling chambers arranged at a radially outside of the valve-seat opening portion,
a central portion to be connected with the valve-seat opening portion, and
two or more introduction portions that each guide the fuel from the central portion to the respective swirling chambers,
in that the introduction portion has a first side wall portion and a second side wall portion that face each other across a center axis of said introduction portion,
in that a center of the injection hole portion is provided in such a way as to be offset toward the first side wall portion with respect to the center axis of the introduction portion and in such a way as to coincide with a center of the swirling chamber,
in that the swirling chamber has a curved-surface wall portion formed of part of a virtual arc,
in that the curved-surface wall portion is connected with the first side wall portion through the intermediary of a straight-surface wall portion that extends linearly, and
in that letting T denote a shortest distance between the center axis of the introduction portion and the center of the injection hole portion and letting G denote a shortest distance between the center of the injection hole portion and the straight-surface wall portion, the straight-surface wall portion is disposed within a range that satisfies [0.8T ? G ? 1.2T].
[0013]
The present disclosure makes it possible to obtain a fuel injection valve that raises the micronization performance for fuel spray and has a desired spray angle for the fuel spray.
The foregoing and other object, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a cross-sectional view illustrating a fuel injection valve according to Embodiment 1;
FIG. 2A is an enlarged cross-sectional view illustrating the front-end portion of a valve body, a valve seat, and an injection hole plate in the fuel injection valve according to Embodiment 1;
FIG. 2B is a plan view of the injection hole plate in the fuel injection valve according to Embodiment 1, when viewed along the arrow direction Z in FIG. 2A;
FIG. 3 is an explanatory view illustrating a fuel flow in the injection hole plate of the fuel injection apparatus according to Embodiment 1;
FIG. 4 is an explanatory view illustrating a fuel flow in the injection hole plate of the fuel injection apparatus according to Embodiment 1;
FIG. 5 is an explanatory view illustrating a fuel flow in an injection hole plate of a fuel injection apparatus according to Embodiment 2;
FIG. 6 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result;
FIG. 7 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result; and
FIG. 8 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015]
Embodiment 1
FIG. 1 is a cross-sectional view illustrating a fuel injection valve according to Embodiment 1; FIG. 2A is an enlarged cross-sectional view illustrating the front-end portion of a valve body, a valve seat, and an injection hole plate in the fuel injection valve according to Embodiment 1; FIG. 2B is a plan view of the injection hole plate in the fuel injection valve according to Embodiment 1, when viewed along the arrow direction Z in FIG. 2A. In FIGS. 1, 2A, and 2B, a fuel injection valve 1 has a solenoid device 4, a housing 5, which is a yoke portion of a magnetic circuit, a core 6, which is a fixed iron-core portion of the magnetic circuit, a coil 7, an armature 8, which is a movable iron-core portion of the magnetic circuit, and a valve device 9. The valve device 9 includes a valve body 10, a valve holder 11, and a valve seat 12.
[0016]
The valve holder 11 is pressed onto the outer-diameter portion of the core 6 and then is welded and fixed on the core 6. The armature 8 is pressed onto the valve body 10 and then is welded and fixed on the valve body 10. At the downstream of the valve seat 12, an injection hole plate 13 is welded with the valve seat 12 at a welding portion 50 so as to be coupled with the valve seat 12; the valve seat 12 and the injection hole plate 13, as an integrated structure, are mounted in the valve holder 11. In the injection hole plate 13, there are provided two or more injection hole portions 14 that each penetrate the injection hole plate 13 in the plate-thickness direction thereof.
[0017]
The valve body 10 is urged by a compression spring 16 in such a way as to constantly depart from the endface portion of the core 6 toward the valve seat 12. A sliding portion 8a, which is the outer circumferential portion of the armature 8, slidably makes contact with the inner circumference portion of a guide portion 11a provided in the valve holder 11, in the axial direction of the valve body 10; along with the armature 8, the valve body 10 fixed to the armature 8 can travel in the axial direction.
[0018]
In the injection hole plate 13, there are provided a central portion 13a that communicates with a valve-seat opening portion 12d of the valve seat 12, four groove-type introduction portions 13b that each radially extend from the central portion 13a in such a way as to be spaced a 90-degree angle apart from one another, four swirling chambers 13c that are coupled with the respective corresponding end portions of the introduction portions 13b, and the four injection hole portions 14 that are provided in the respective swirling chambers 13c and each penetrate the injection hole plate 13. The bottom surface of the central portion 13a, the respective bottom surfaces of the introduction portions 13b, and the respective bottom surfaces of the swirling chambers 13c are aligned on one and the same plane. The respective swirling chambers 13c communicate with one another through the introduction portions 13b and the central portions 13a.
[0019]
Next, the operation of the fuel injection valve 1 will be explained. When an operation signal is transmitted from an internal-combustion-engine control apparatus to a driving circuit for the fuel injection valve 1, the coil 7 of the fuel injection valve 1 is energized; magnetic flux is produced in the magnetic circuit configured with the armature 8, the core 6, the housing 5, and the valve holder 11; the armature 8 is attracted toward the core 6; then, the top-surface portion 8b of the armature 8 abuts on the bottom-surface portion of the core 6. When the valve body 10 integrated with the armature 8 departs from a valve seat portion 12a and hence a gap is formed between the valve body 10 and the valve seat portion 12a, the fuel passes through a gap between the valve seat portion 12a and the valve body 10 from a chamfer portion 15a of a boll 15 welded to the front-end portion of the valve body 10 and then flows into the central portion 13a of the injection hole plate 13 through the valve-seat opening portion 12d of the valve seat 12.
[0020]
The fuel that has flowed into the central portion 13a of the injection hole plate 13 through the valve-seat opening portion 12d of the valve seat 12 further flows into the swirling chambers 13c through the respective introduction portions 13b. The fuel that has flowed into each of the swirling chambers 13c further flows into the injection hole portion 14 while producing a swirling flow; the swirling flow is kept also in each of the injection hole portions 14, and a thin liquid film is formed along the injection-hole inner wall. The thin liquid film that has been formed along the injection-hole inner wall is injected from the injection hole portion 14 into an intake port of the internal combustion engine in a hollow and conical manner, so that micronization of the fuel is facilitated.
[0021]
Next, when an operation stop signal is transmitted from the internal-combustion-engine control apparatus to the drive circuit for the fuel injection valve 1, the energization of the coil 7 is stopped and hence the magnetic flux in the magnetic circuit decreases. As a result, because due to pressing force of the compression spring 16, the valve body 10 travels toward the valve seat 12 and the surface of the ball 15 is seated in the valve seat portion 12a of the valve seat 12, the gap between the ball 15 and the valve seat portion 12a is closed and hence the fuel injection ends.
[0022]
Each of FIGS. 3 and 4 is an explanatory view illustrating a fuel flow in the injection hole plate of the fuel injection apparatus according to Embodiment 1; parts of the central portions 13a of the introduction portions 13b, and the swirling chambers 13c of the injection hole plate 13 and the injection hole portion 14 are illustrated in an enlarged manner. In the following explanation, only each one of the introduction portions 13b, the swirling chambers 13c, and the injection hole portions 14 will be explained based on FIG. 3; however, the same explanations can be applied to the other introduction portions 13b, the other swirling chambers 13c, and the other injection hole portions 14.
[0023]
In FIG. 3, the introduction portion 13b has a first side wall portion 13b1 and a second side wall portion 13b2 that face each other with respect to a center axis X of the introduction portion 13b. A center 14a of the injection hole portion 14 is provided in such a way as to be offset from the center axis X of the introduction portion 13b toward the first side wall portion 13b1 and in such a way as to coincide with the center of the swirling chamber 13c. The swirling chamber 13c has a curved-surface wall portion 13c1 formed of part of a virtual arc. The curved-surface wall portion 13c1 is connected with the first side wall portion 13b1 of the introduction portion 13b by way of a straight-surface wall portion 13c2 that extends linearly.
[0024]
In this situation, letting T denote the shortest distance between the center axis X of the introduction portion 13b and the center 14a of the injection hole portion 14, the shortest distance G between the center 14a of the injection hole portion 14 and the straight-surface wall portion 13c2 is set in such a way as to satisfy the equation (1) below.
0.8T ? G ? 1.2T ????? (1)
In other words, the straight-surface wall portion 13c2 of the swirling chamber 13c is disposed at a position where the equation (1) is satisfied.
[0025]
The shortest distance T between the center axis X of the introduction portion 13b and the center 14a of the injection hole portion 14 signifies an offset amount of the center 14a of the injection hole portion 14 from the center axis X of the introduction portion 13b.
[0026]
As described above, the first side wall portion 13b1 and the straight-surface wall portion 13c2 are directly connected with each other, and the straight-surface wall portion 13c2 is disposed at the position where the foregoing equation (1) is satisfied; therefore, the difference between the flow path cross-sectional area at a time when the flow B along which the fuel flows into the injection hole portion 14 by way of the swirling chamber 13c reaches the periphery of the injection hole portion 14 by way of the swirling chamber 13c and the flow path cross-sectional area at a time when the flow A along which the fuel directly flows into the injection hole portion 14 from the introduction portion 13b reaches the periphery of the injection hole portion 14 falls within a specific range.
[0027]
As a result, it is made possible that while the balance between the respective strengths of the swirling force of the flow A and the swirling force of the flow B is suppressed from being significantly lost, the length L of the first side wall portion 13b1 that largely affects the rectification degree of the flow A is freely set; therefore, the strength of the swirling force of the flow A that directly flows into the injection hole portion 14 can be adjusted. Moreover, the angle of the straight-surface wall portion 13c2 with respect to the center axis X of the introduction portion 13b can also be adjusted; thus, the direction along which the flow B flows into the injection hole portion 14 can be adjusted.
[0028]
Accordingly, it is made possible that the parameters such as the diameter of the swirling chamber 13c, the shortest distance T between the center axis X of the introduction portion 13b and the center 14a of the injection hole portion 14, which is the foregoing offset amount of the injection hole, and the length M of the second side wall portion 13b2 are not changed so that the effects thereof to the flow rate of the fuel, the micronization performance, and the like are minimized, and it is also made possible that while the balance between the respective strengths of the swirling forces of the flow A and the flow B that face each other at the injection hole portion 14 is maintained in such a way as to be not significantly lost, the strength of the swirling force of the flow A and the direction along which the flow B flows into the injection hole portion 14 are adjusted. That is to say, because the spraying angle for the fuel can be adjusted, the man-hours for adjusting the spraying angle for the fuel can be reduced in comparison with the conventional fuel injection valve.
[0029]
A cavity surrounded by the front-end portion of the ball 15 in the valve body 10, the valve seat 12, and the injection hole plate 13 forms a fuel cavity; the volume of the fuel cavity is largely affected by a dynamic flow rate, which is a change in the fuel flow rate at a time when the temperature, the atmosphere of a space into which the fuel is injected, or the like changes. That is to say, for example, at a time of fuel injection into a negative-pressure atmosphere, after the fuel injection valve 1 has been closed, part of the fuel existing in the fuel cavity is sucked out through the injection hole portion 14 into the engine intake pipe, due to the negative pressure; therefore, the change in the fuel flow rate becomes large. Then, because the flow speed of the fuel that has been sucked out from the inside of the fuel cavity into the engine intake pipe is slow, an inferior fuel having a large particle diameter is injected into the engine intake pipe immediately after the fuel injection valve 1 is closed.
[0030]
Thus, when the shapes of the valve seat 12 and the injection hole plate 13 are reviewed, it is one of the important elements to consider the volume of the fuel cavity, in terms of enhancement of the characteristics of the fuel injection valve 1. In consideration of the foregoing point, it may be allowed that a connection portion b between the curved-surface wall portion 13c1 and the straight-surface wall portion 13c2 of the swirling chamber 13c is made to be a curved surface Rb (unillustrated). When the connection portion b is made to be the curved surface Rb, the volume of the swirling chamber 13c formed of the curved-surface wall portion 13c1 and the straight-surface wall portion 13c2 is reduced; thus, the micronization of fuel spray is facilitated and hence a change in the flow rate, caused by the foregoing change in the temperature, the atmosphere, or the like, is suppressed.
[0031]
Moreover, when the connection portion b is made to be the curved surface Rb, the flow B that has arrived by way of the swirling chamber 13c smoothly turns its direction toward the straight-surface wall portion 13c2, due to the foregoing curved surface Rb, at a time when it reaches the straight-surface wall portion 13c2; therefore, the pressure loss in the flow B is reduced and hence the micronization performance is raised. Furthermore, when the connection portion b is made to be the curved surface Rb, the workability of the swirling chamber 13c in the injection hole plate 13 is raised; in addition, when the connection portion b is made to be the curved surface Rb, there can be raised the durability of the die at a time when the swirling chamber 13c, the introduction portion 13b, and the central portion 13a are formed in the injection hole plate 13 through press working.
[0032]
It may be allowed that while the foregoing connection portion b is made to be the curved surface Rb, the connection portion between the straight-surface wall portion 13c2 of the swirling chamber 13c and the first side wall portion 13b1 of the introduction portion 13b is made to be a curved surface. In this case, the workability of each of the swirling chamber 13c and the introduction portion 13b is raised, and the durability of the die for the foregoing press working can further be enhanced.
[0033]
FIG. 6 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result; the ordinate denotes the particle diameter, and the abscissa denotes G/T. In this situation, G/T denotes the proportion of the shortest distance T between the center axis X of the introduction portion 13b and the center of the injection hole portion 14 to the shortest distance G between the center of the injection hole portion 14 and the straight-surface wall portion 13c2. As evident from FIG. 6, it is learned that in a range where the shortest distance T between the center axis X of the introduction portion 13b and the center of the injection hole portion 14 and the shortest distance G between the center of the injection hole portion 14 and the straight-surface wall portion 13c2 satisfy the relationship [0.8T ? G ?1.2T], which is the foregoing equation (1), i.e., in the case where G/T is in the range [0.8 ? G/T ? 1.2], there can be obtained excellent fuel injection in which the minute particles of fuel spray are relatively small and a change in the particle diameter is small.
[0034]
Furthermore, as illustrated in FIG. 4, in the case where letting W denote the shortest distance between the center axis X of the introduction portion 13b and the first side wall portion 13b1 and letting fDf denote the diameter of the injection hole, the injection hole portion 14 is disposed in a range where the shortest distance T between the center axis X of the introduction portion 13b and the center 14a of the injection hole portion 14 satisfies the equation (2) below, i.e., in the case where the injection hole portion 14 is disposed at a position where the injection hole portion 14 intersects an virtual extended line obtained by extending the first side wall portion 13b1 toward the injection hole portion 14, the offset amount of the injection hole portion 14 is set within a range where excessive expansion of spray is suppressed and a flow component, out of the flow A directly flowing into the injection hole portion 14, that does not swirl but directly flows out from the injection hole portion 14 is suppressed, so that the micronization performance is maintained.
W < T ? w + fDf/2 ????? (2)
[0035]
In this situation, because the respective rectification degrees of the flow A and the flow B are largely affected by the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2, the respective values of the length L and the length M are set to the ones that satisfy the equation (3) below; as a result, the difference between the respective rectification degrees of the flow A and the flow B, i.e., the balance between the respective swirling-force strengths of the flow A and the flow B is suppressed from significantly changing.
0.1M ? L ????? (3)
[0036]
FIG. 7 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result; the ordinate denotes the particle diameter, and the abscissa denotes the ratio L/M of the length L of the first side wall portion 13b1 to the length M of the second side wall portion 13b2. As evident from FIG. 7, in a range where the relationship between the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2 satisfies the relationship [0.1 ? L/M], i.e., [0.1M ? L], the balance between the respective swirling-force strengths of the flow A and the flow B is suppressed from significantly changing and hence the particle diameter of the fuel spray becomes an excellent value.
[0037]
The proportion of the shortest distance G between the center 14a of the injection hole portion 14 and the straight-surface wall portion 13c2 to the shortest distance T between the center axis X of the introduction portion 13b and the center of the injection hole portion 14, i.e., T as the offset amount of the center 14a of the injection hole portion 14 with respect to the center axis X of the introduction portion 13b is set in the range [0.8 ? G/T ? 1.2], as described above, and the relationship between the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2 is set in such a way as to satisfy [0.1 ? L/M], i.e., [0.1M ? L]. In this case, when the angle s between the first side wall portion 13b1 and the straight-surface wall portion 13c2 decreases, the difference [M - L] between the length M of the second side wall portion 13b2 and the length L of the first side wall portion 13b1 also decreases.
[0038]
When the shortest distance T between the center axis X of the introduction portion 13b and the center of the injection hole portion 14, i.e., T as the offset amount of the center 14a of the injection hole portion 14 with respect to the center axis X of the introduction portion 13b decreases, the flow component, out of the flow A directly flowing into the injection hole portion 14, that does not swirl but directly flows out from the injection hole portion 14 increases. Thus, when the respective values of the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2 satisfy the range [M - L ? 0.18], i.e., [L ? M - 0.18], the micronization of the flow A can be suppressed from being largely deteriorated.
[0039]
FIG. 8 is an explanatory graph for explaining the fuel injection valve according to Embodiment 1, based on an experimental result; the ordinate denotes the particle diameter, and the abscissa denotes the difference [M -L] between the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2. As illustrated in FIG. 8, when the respective values of the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2 satisfy the range [0.18 ? M -L], i.e., [L ? M - 0.18], the micronization of the flow A that directly flows into the injection hole portion 14 can be suppressed from being largely deteriorated and hence the state where the particle diameter is excellent is maintained.
[0040]
As described above, when the length L of the first side wall portion 13b1 and the length M of the second side wall portion 13b2 are set in such a way that the range [0.1M ? L ? M - 0.18] is established, the spray particle diameter of the fuel can be prevented from being largely deteriorated.
[0041]
In addition, as illustrated in FIG. 4, when a virtual circumscribing circle Y that circumscribes the four swirling chambers 13c is considered in Embodiment 1, the shortest distance T between the center axis X of the introduction portion 13b and the center of the injection hole portion 14, i.e., T as the offset amount of the center 14a of the injection hole portion 14 with respect to the center axis X of the introduction portion 13b, the length M of the second side wall portion 13b2, and the shortest distance w between the center axis X of the introduction portion 13b and the first side wall portion 13b1 are set in such a way that a radius r of the virtual circumscribing circle Y of the swirling chamber 13c satisfies the equation (4) below.
(4)
[0042]
The radius r of the virtual circumscribing circle Y is a function having, as the parameters, T as the offset amount of the center 14a of the injection hole portion 14, the shortest distance w between the center axis X of the introduction portion 13b and the first side wall portion 13b1, and the length M of the second side wall portion 13b2; An increase in the radius r of the virtual circumscribing circle Y causes the whole of the introduction portion 13b to expand, i.e., the working volume of the introduction portion 13b is caused to increase. For example, in the case where when the introduction portion 13b is formed through press molding, a shape that does not protrude to the side opposite to the molding surface is considered, a large increase in the working volume makes it difficult to satisfy a desired dimensional accuracy of the introduction portion 13b. A deterioration in the dimensional accuracy of the introduction portion 13b is an element that adversely affects the desired evenness levels in the flow rate, the fuel spray characteristics, and the like; therefore, it is desirable to set the radius r of the virtual circumscribing circle Y to a value that satisfies the range [r ? 1.315], in order to raise the desired accuracies of the flow rate, the fuel spray characteristics, and the like.
[0043]
As a result, because the suppression of an excessive increase in the working volume of the introduction portion 13b makes it possible to maintain an excellent dimensional accuracy of the introduction portion 13b, the desired evenness levels of the flow rate, the fuel spray characteristics, and the like can be satisfied. Moreover, the suppression of an excessive increase in the volume of the introduction portion 13b makes it possible to suppress a change in the flow rate at a time of when the temperature, the atmosphere, or the like changes; thus, also in this point of view, it is desirable to set the radius r of the virtual circumscribing circle Y to a value that satisfies the range [r ? 1.315].
[0044]
In the foregoing fuel injection valve according to Embodiment 1, the curved-surface wall portion is connected with the first side wall portion through the intermediary of the straight-surface wall portion that extends linearly; letting T denote the shortest distance between the center axis of the introduction portion and the center of the injection hole portion and letting G denote the shortest distance between the center of the injection hole portion and the straight-surface wall portion, the straight-surface wall portion is disposed within a range that satisfies [0.8T ? G ? 1.2T]; thus, in the case where when the flow A along which the fuel directly flows into the injection hole portion from the introduction portion and the flow B along which the fuel flows into the injection hole by way of the swirling chamber are considered, the difference between the flow path cross-sectional area at a time when the flow B reaches the periphery of the injection hole portion by way of the swirling chamber and the flow path cross-sectional area at a time when the flow A reaches the periphery of the injection hole is set to be within a specific range, it is made possible that while the balance between the respective swirling-force strengths of the flow A and the flow B is suppressed from being significantly lost, the length of the first side wall portion, which largely affects the rectification degree of the flow A, is freely set, and hence the swirling-force strength of the flow A that directly flows into the injection hole can be adjusted.
[0045]
Moreover, because the angle of the straight-surface wall portion can also be adjusted, the direction along which the flow B flows into the injection hole portion can be adjusted. Accordingly, it is made possible that the parameters such as the diameter of the swirling chamber, the offset amount of the center of the injection hole, and the length of the second side wall portion are not changed so that the effects thereof to the flow rate and the micronization performance are minimized, and it is made possible that while the balance between the respective strengths of the swirling forces of the flow A and the flow B that face each other at the injection hole portion is maintained in such a way as to be not significantly lost, the strength of the swirling force of the flow A and the direction along which the flow B flows into the injection hole portion are adjusted; thus, because the spraying angle can be adjusted, the man-hours for adjusting the spraying angle can be reduced in comparison with the conventional fuel injection valve.
[0046]
Moreover, in the fuel injection valve according to Embodiment 1, because letting W denote the shortest distance between the center axis of the introduction portion and the first side wall portion and letting fDf denote the diameter of the injection hole portion, the shortest distance T between the center axis of the introduction portion and the center of the injection hole portion is set to a value that satisfies [w < T ? w + fDf/2], excessive expansion of injection spray is suppressed and a flow component, out of the flow A directly flowing into the injection hole, that does not swirl but directly flows out from the injection hole portion is suppressed, so that the micronization performance is maintained.
[0047]
Furthermore, in the fuel injection valve according to Embodiment 1, when L denotes the length of the first side wall portion and M denotes the length of the second side wall portion, the first side wall portion and the second side wall portion are configured in such a way as to satisfy [0.1M ? L ? M - 0.18]. In this situation, at first, with regard to [0.1M ? L], because the respective rectification degrees of the fuel flow A and the fuel flow B are largely affected by the length L of the first side wall portion and the length M of the second side wall portion, the respective values of the length L and the length M are set to the ones that satisfy [0.1M ? L]; as a result, the difference between the respective rectification degrees of the flow A and the flow B, i.e., the balance between the respective swirling-force strengths of the flow A and the flow B is suppressed from significantly changing.
[0048]
Next, with regard to [L ? M - 0.18], the difference [M - L] between the length M of the second side wall portion and the length L of the first side wall portion is a function of the angle of the straight-surface wall portion from the side wall portion, the shortest distance G between the center of the injection hole portion and the straight-surface wall portion, and T as the offset amount of the center of the injection hole portion; when T as the offset amount decreases, the difference between the length M of the second side wall portion and the length L of the first side wall portion also decreases. A decrease in T as the offset amount increases the flow component, out of the flow A directly flowing into the injection hole portion, that does not swirl but directly flows out from the injection hole; therefore, when the length L of the first side wall portion and the length M of the second side wall portion satisfy [M - L ? 0.18], i.e., [L ? M - 0.18], the micronization of the flow A can be suppressed from being largely deteriorated.
[0049]
In consideration of the above facts, in terms of preventing the injection-spray micronization from being largely deteriorated, it is desirable to set the respective values of the length L of the first side wall portion and the length M of the second side wall portion to the ones that satisfy [0.1M ? L ? M - 0.18].
[0050]
Moreover, in the fuel injection valve according to Embodiment 1, when the virtual circumscribing circle that circumscribes the two or more swirling chambers is considered, the radius r of the virtual circumscribing circle has a value that satisfies the following equation, letting M denote the length of the second side wall portion.

The radius r of the virtual circumscribing circle is a function hving, as the parameters, the offset amount of the center of the injection hole portion, the width of the introduction portion, and the length M of the second side wall portion; an increase in the radius r of the virtual circumscribing circle causes the whole of the introduction portion to expand, i.e., the working volume of the introduction portion is caused to increase. For example, in the case where when the introduction portion is formed through press molding, a shape that does not protrude to the side opposite to the molding surface is considered, a large increase in the working volume makes it difficult to satisfy a desired dimensional accuracy of the introduction portion. A deterioration in the dimensional accuracy of the introduction portion is an element that adversely affects the desired evenness levels in the flow rate, the fuel spray characteristics, and the like; therefore, it is desirable to set the radius r of the virtual circumscribing circle to a value that satisfies the range [r ? 1.315], in order to obtain the desired accuracies of the flow rate and the fuel spray characteristics.
[0051]
That is to say, because the suppression of an excessive increase in the working volume of the introduction portion makes it possible to maintain an excellent dimensional accuracy of the introduction portion, the desired evenness levels of the flow rate and the fuel spray characteristics can be satisfied. Moreover, the suppression of an excessive increase in the volume of the groove portion makes it possible to suppress a change in the flow rate at a time of when the temperature, the atmosphere, or the like changes; thus, also in this point of view, it is desirable to set the radius r of the virtual circumscribing circle to a value that satisfies the range [r ? 1.315].
[0052]
Embodiment 2
Next, a fuel injection valve according to Embodiment 2 will be explained. FIG. 5 is an explanatory view illustrating a fuel flow in an injection hole plate of the fuel injection apparatus according to Embodiment 2. As illustrated in FIG. 5, the straight-surface wall portion 13c2 of the swirling chamber 13c is provided at a position that is adjacent to or overlaps a tangential line in contact with a virtual circle Z that has a radius of the shortest distance T between the center axis X of the introduction portion 13b and the center 14a of the injection hole portion 14 and whose center coincides with the center 14a of the injection hole portion 14. The other configurations are the same as those of the fuel injection valve according to Embodiment 1.
[0053]
In the fuel injection valve according to Embodiment 2, the first side wall portion 13b1 of the introduction portion 13b and the straight-surface wall portion 13c2 of the swirling chamber 13c are directly connected with each other and the straight-surface wall portion 13c2 is provided at a position that is adjacent to or overlaps a tangential line in contact with the virtual circle Z, so that the difference between the flow path cross-sectional area at a time when the flow B reaches the periphery of the injection hole portion 14 by way of the swirling chamber 13c and the flow path cross-sectional area at a time when the flow A reaches the periphery of the injection hole portion 14 further decreases; therefore, the balance between the respective swirling-force strengths of the flow A and the flow B is further raised, the homogeneity of the liquid-film thickness in the injection hole portion 14 is enhanced, and the micronization of fuel spray is facilitated.
[0054]
On top of that, the angle of the straight-surface wall portion 13c2 from the center axis X of the introduction portion 13b is adjusted, so that the direction along which the flow B flows into the injection hole portion 14 can be adjusted and the length L of the first side wall portion 13b1 can also be adjusted; thus, the parameters such as the diameter of the swirling chamber 13c, T as the offset amount of the center 14a of the injection hole portion 14, and the length M of the second side wall portion 13b2 are not changed and hence the effects thereof to the fuel flow rate, the micronization performance, and the like are minimized, so that the balance between the respective strengths of the flow A and the flow B that face each other at the injection hole portion 14 can be adjusted; as a result, the spraying angle can be adjusted, and the man-hours for adjusting the spraying angle can be reduced in comparison with the conventional fuel injection valve.
[0055]
Although the present application is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functions described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments. Therefore, an infinite number of unexemplified variant examples are conceivable within the range of the technology disclosed in the present application. For example, there are included the case where at least one constituent element is modified, added, or omitted and the case where at least one constituent element is extracted and then combined with constituent elements of other embodiments. In addition, the units of all the lengths are [mm]; however, in order to prevent the notation from becoming complex, the notation of the unit is omitted.