WO2015011539A1

WO2015011539A1 - Fuel injection valve

Info

Publication number: WO2015011539A1
Application number: PCT/IB2014/001337
Authority: WO
Inventors: Natsuki Sugiyama
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2013-07-25
Filing date: 2014-07-17
Publication date: 2015-01-29
Also published as: JP5812050B2; JP2015025392A

Abstract

A fuel injection valve includes an injection hole plate in which a first injection hole and a second injection hole are formed. Inlet side opening end parts of the first injection hole and the second injection hole are formed into oval shapes, each of which having a major axis and a minor axis. In a section along an axis of the first injection hole and a minor axis of the inlet side opening end part of the first injection hole, a minor axis angle of the first injection hole, formed by opposing inner wall surface parts of the first injection hole, is smaller than a minor axis angle of the second injection hole, which is formed by opposing inner wall surface parts of the second injection hole, in a section along an axis of the second injection hole and the minor axis of the inlet side opening end part of the second injection hole.

Description

FUEL INJECTION VALVE

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The invention relates to a fuel injection valve.

2. Description of Related Art

[0002] A fuel injection valve having an injection hole plate has been known (for example, Japanese Patent Application Publication No. 2013-87757 (JP 2013-87757 A)). The injection hole plate has a plurality of injection holes passing through the injection hole' plate in a plate thickness direction. The injection hole is formed so that passage sectional area gradually increases from a fuel, inlet, which is open on one side of the injection hole plate, towards an elliptical fuel outlet, which is open on the opposite side of the injection hole plate.

[0003] The injection hole has a first angle and a second angle. The first angle is formed by an inner wall surface part of the injection hole in a section along a minor axis of the fuel outlet, which includes an axis of the injection hole. The second angle is formed by the inner wall surface part of the injection hole in a section along a major axis of the fuel outlet, which includes the axis of the injection hole. The injection hole is formed so that the second angle becomes larger than the first angle.

[0004] Therefore, in the fuel injection valve, fuel injected outside through the injection holes of the injection hole plate is expanded in the major axis direction of the fuel outlet. Thus, it is possible to promote atomization of the fuel.

[0005] In the above-mentioned fuel injection valve, fuel injected outside from the injection holes is atomized. Therefore, adhesion of fuel to the inner wall surface part of an inlet port of an engine, to which the fuel injection valve is installed, is. reduced, and introduction of fuel into a combustion chamber is promoted when an inlet valve is open. Therefore, the above-mentioned fuel injection valve is able to restrain an HC emission (an HC content in exhaust gas) at a time of cold start of an engine.

[0^006] However, in the above-mentioned fuel injection valve, when fuel injected outside from the injection holes is atomized too much, the fuel is vaporized before reaching the combustion chamber, and volumetric efficiency of the fuel is reduced by an vaporization amount. Hence, there is a concern about a reduction of an engine output.

SUMMARY. OF THE INVENTION

[0007] The invention provides a fuel injection valve that reduces an HC emission at a time of cold start of an engine, and improves an engine output compared to a conventional fuel injection valve.

[0008] A fuel injection valve according to a first aspect of the invention includes a nozzle having a valve hole, a valve body provided inside the nozzle so as to open and close the valve hole, and an injection hole plate provided in the nozzle so as to cover the valve hole. The injection hole plate is provided with a first injection hole and a second injection hole that pass through the injection hole plate in a plate thickness direction. The first injection hole and the second injection hole have inlet side opening end parts, which are open towards the nozzle, and outlet side opening end parts, which are open towards an opposite side of the nozzle. In a plan view of the injection hole plate, the inlet side opening end parts of the first injection hole and the second injection hole have oval shapes, and each of the oval shapes has a major axis and a minor axis. Passage sections of the first injection hole and the second injection hole expand from the inlet side opening end parts to the outlet side opening end parts. In a section along a minor axis of the inlet side opening end part of the first injection hole, including an axis of the first injection hole, a minor axis angle of the first injection hole, which is defined by opposing inner wall surface parts of the first injection hole, is smaller than a minor axis angle of the second injection hole, which is defined by opposing inner wall surface parts of the second injection hole, in a section along the minor axis of the inlet side opening end part of the second injection hole, including an axis of the second injection hole. [0009] In the fuel, injection valve according to the first aspect of the invention, the minor axis angle of the first injection hole, which is formed by the inner wall surface parts of the first injection hole of the injection hole plate, is smaller than the minor axis angle of the second injection hole, which is formed by the inner wall surface parts of the second injection hole of the injection hole plate. Therefore, in fuel injection valve according to the first aspect of the invention, a particle size of fuel injected outside from the first injection hole is larger than a particle size of fuel injected outside from the second injection hole. In other words, in the fuel injection valve according to the first aspect of the invention, kinetic energy of fuel injected outside from the first injection hole is larger than kinetic energy of fuel injected outside form the second injection hole.

[0010] Thus, in the . fuel injection valve according to the first aspect of the invention, a particle size of fuel injected outside from the second injection hole becomes smaller than a particle size of fuel injected outside from the first injection hole. Therefore, the fuel injection valve according to the invention is able to reduce an HC emission at a time of cold start of an engine. In the fuel injection valve according to the invention, penetration of fuel injected outside from the first injection hole becomes larger than penetration of fuel injected outside from an injection hole for promoting micronization. Hence, in the fuel injection valve according to the invention, fuel is not vaporized before reaching a combustion chamber, thereby achieving improvement of an engine output.

[0011] A fuel injection valve according to a second aspect of the invention includes nozzle having a valve hole, a valve body provided inside the nozzle so as to open and close the valve hole, and an injection hole plate provided in the nozzle so as to cover the valve hole. The injection hole plate is provided with a first injection hole and a second injection hole that pass through the injection hole plate in a plate thickness direction. The first injection hole and the second injection hole have inlet side opening end parts, which are open towards the nozzle, and outlet side opening end parts, which are open towards the opposite side of the nozzle. The first injection hole is pierced on a center side of the injection hole plate. The second injection hole is pierced on an outer side of the first injection hole in a radial direction of the injection hole plate. In a plan view of the injection hole plate, the inlet ^"side opening end parts of the first injection hole and the second injection hole have oval shapes, and each of the oval shapes has a major axis and a minor axis. Passage sections of the first injection hole and the second injection hole expand from the inlet side opening end parts to the outlet side opening end parts. In a section along the minor axis of the inlet side opening end part of the first injection hole, including an axis of the first injection hole, a minor axis angle of the first injection hole, which is defined by opposing inner wall surface parts of the first injection hole, is larger than a major axis angle of the first injection hole, which is defined by opposing inner wall surface parts of the first injection hole, in a section along the major axis of the inlet side opening end part of the first injection hole, including the axis of the first injection hole. In a section along the minor axis of the inlet side opening end part of the second injection hole, including an axis of the second injection hole, a minor axis angle of the second injection hole, which is defined by opposing inner wall surface parts - of the second injection hole, is larger than a major axis angle of the second injection hole, which is defined by opposing inner wall surface parts of the second injection hole, in a section along the major axis of the inlet side opening end part of the second injection hole, including the axis of the second injection hole. The minor axis angle of the first injection hole is smaller than the minor axis angle of the second injection hole.

[0012] In the fuel injection valve according to the second aspect of the invention, the minor axis angle of the first injection hole of the injection hole plate is larger than the major axis angle of the first injection hole. Therefore, in the fuel injection valve according to the second aspect of the invention, a fuel liquid film of fuel injected outside from the first injection hole becomes thin in the major axis direction of the inlet side opening end part. At the same time, the fuel liquid film sufficiently expands in the minor axis direction of the inlet side opening end part. Therefore, it is possible to promote atomization of fuel.

[0013] In the fuel injection valve according to the second aspect of the invention, the minor axis angle of the second injection hole of the injection hole plate is larger than the major axis angle of the second injection hole. Thus, in the fuel injection valve according to the second aspect of the invention, a fuel liquid film of fuel injected outside from the second injection hole becomes thin in the major axis direction of the inlet side opening end part. At the same time, the fuel liquid film expands sufficiently in the minor axis direction of the inlet side opening end part. Thus, it is possible to improve atomization of fuel.

[0014] Further, in the fuel injection valve according to the second aspect of the invention, the minor axis angle of the first injection hole of the injection hole plate is smaller than the minor axis angle of the second injection hole of the injection hole plate. Therefore, in the fuel injection valve according to the second aspect of the invention, a particle size of fuel injected outside from the first injection hole becomes larger than a particle size of fuel injected outside from the second injection hole. In other words, in the fuel injection valve according to the invention, kinetic energy of fuel injected outside from the first injection hole becomes larger than kinetic energy of fuel injected outside from the second injection hole.

[0015] Therefore, in the fuel injection valve according to the second aspect of the invention, a particle size of fuel injected outside from the second injection hole becomes smaller than a particle size of fuel injected outside from the first injection hole. Thus, the fuel injection valve according to the invention is able to reduce an HC emission at a time of cold start of an engine. Moreover, in the fuel injection valve according to the invention, penetration of fuel injected outside from the first injection hole becomes larger than penetration of fuel injected outside from the second injection hole. Hence, in the fuel injection valve according to the second aspect of the invention, fuel is not vaporized before reaching a combustion chamber, and it is thus possible to improve of an engine output.

[0016] In the fuel injection valve according to the first and second aspects, the injection hole plate may be configured such that a passage sectional area of the inlet side opening end part of the first injection hole is larger than a passage sectional area of the inlet side opening end part of the second injection hole.

[0017] In the foregoing fuel injection valve, the passage sectional area of the inlet side opening end part of the first injection hole is larger than the passage sectional area of the inlet side opening end part of the second injection hole. Therefore, in the fuel injection valve, a fuel liquid film inside the first injection hole becomes thicker than a fuel liquid film inside the second injection hole, and a particle size of fuel injected outside from the first injection hole becomes larger than a particle size of fuel injected outside from the second injection hole. In other words, in the fuel injection valve, kinetic energy of fuel injected outside from the first injection hole becomes larger than kinetic energy of fuel injected outside from the second injection hole.

[0018] Therefore, in the foregoing fuel injection valve, a particle size of fuel injected outside from the second injection hole is smaller than a particle size of fuel injected outside from the first injection hole. Thus, the fuel injection valve is able to reduce an HC emission at a time of cold start of an engine. Also, in the fuel injection valve, penetration of fuel injected outside from the first injection hole becomes larger than penetration of fuel injected outside of the second injection hole. Therefore, in the fuel injection valve, fuel is not vaporized before reaching a combustion chamber, thereby improving an engine output.

[0019] In the fuel injection valve according to the first and second aspects, the first injection hole and the second injection hole may be configured such that a spray area of the fuel injected from the first injection hole and a spray area of fuel injected from the second injection hole do not overlap each other.

[0020] In the fuel injection valve, directions in which the first injection hole and the second injection hole pass through the injection hole plate are set so that a spray area of fuel injected form the first injection hole and a spray area of fuel injected from the second injection hole do not overlap each other. Therefore, in the fuel injection vajve, a . phenomenon happens in which a flow of fuel injected outside from the second injection hole is drawn into a flow of fuel injected outside from the first injection hole due to viscosity of air.

[0021] Therefore, in the fuel injection valve, a particle size of fuel injected outside from the second injection hole becomes smaller than a particle size of fuel injected outside from the first injection hole. Thus, the fuel injection valve is able to reduce an HC emission at a time of cold start of an engine. Further, in the fuel injection valve, penetration of fuel injected outside from the first injection hole becomes larger than penetration of fuel injected outside from the second injection hole. Therefore, in the fuel injection valve, fuel is not vaporized before reaching a combustion chamber, thereby improving an engine output.

[0022] According to the embodiments of the invention, it is possible to provide a fuel injection valve in which an HC emission is reduced at a time of cold start of an engine and an engine output is improved compared to a conventional fuel injection valve. , BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1A, FIG. IB, and FIG. 1C are schematic views showing a structure of a fuel injection valve according to an embodiment of the invention, in which FIG. 1 A is a vertical sectional view of a distal end part of the fuel injection valve, FIG. IB is a sectional view taken along the line Bl - Bl in FIG. 1A, and FIG. 1C is a sectional view taken along the line CI - CI in FIG. 1 A;

FIG. 2 is a bottom view of an injection hole plate of the fuel injection valve according to the embodiment of the invention;

FIG. 3 A, FIG. 3B, and FIG. 3C are schematic views showing fuel spray areas of the fuel injection valve according to the embodiment of the invention, in which FIG. 3 A is a front view of a distal end part of the fuel injection valve, FIG. 3B is a side view of the distal end part of the fuel injection valve, and FIG. 3C is a view on arrow C - C in FIG. 3 A;

FIG. 4 is a graph comparing distributions of average fuel particle sizes in the fuel injection valve according to the embodiment of the invention and a fuel injection valve according to a comparative example; FIG. 5 is a graph comparing average fuel particle sizes at outer edge parts of fuel spray areas in the fuel injection valve according to the embodiment of the invention and the fuel injection valve according to the comparative example; and

FIG. 6 is a graph comparing fuel spray lengths in the fuel injection valve according to the embodiment of the invention and the fuel injection valve according to the comparative example.

DETAILED DESCRIPTION OF EMBODIMENTS

[0024] An embodiment of a fuel injection valve according to the invention is explained below by using the drawings.

[0025] As shown in FIG. 1A, FIG. IB, and FIG. 1 C, a fuel injection valve 1 according to this embodiment is provided with a nozzle 10, a valve body 20, and an injection hole plate 30.

[0026] The nozzle 10 is a hollow structure and has a fuel supply passage 1 1 extending upwardly and downwardly in the drawings, and a valve hole 12 that is communicated with a lower end part of the fuel supply passage 1 1 and open downwardly. Fuel pressurized by a pump (not shown) is supplied into the fuel supply passage 1 1. An inner peripheral surface part of the valve hole 12 is tapered so that an inner diameter of the valve hole 12 is reduced downwardly, and forms a valve seat 13.

[0027] The valve body 20 is a bar-like body extending in an upper-lower direction, and is arranged inside the nozzle 10 concentrically with the nozzle 10. A lower end part of the valve body 20 is tapered so that an outer diameter of the valve body 20 is reduced downwardly. The whole circumference of a portion of the tapered part with the largest outer diameter comes into contact with the valve seat 13 of the nozzle 10 as a seal part 21 having a larger diameter than the smallest inner diameter of the valve seat 13.

[0028] The valve body 20 is moved in the upper-lower direction by a valve driving device structured by a spring, a solenoidal coil, and so on (not shown), and closes the valve hole 12 of the nozzle 10 when the seal part 21 comes into contact with the valve seat 13. , [0029] The spring presses the valve body 20 downwardly with respect to the nozzle 10. In other words, the valve body 20 is pressed downwardly by restoring force of the spring unless the solenoidal coil is excited, and the seal part 21 is in contact with the valve seal 13 of the nozzle 10. Thus, communication between the fuel supply passage 1 1 and the valve hole 12 is blocked.

[0030] The solenoidal coil pulls up the valve body 20 against the restoring force of the spring. In other words, when the solenoidal coil is excited, the valve body 20 is pulled up by magnetic attractive force, and the seal part 21 is separated from the valve seat 13 of the nozzle 10. Thus, the fuel supply passage 1 1 and the valve hole 12 are communicated with each other.

[0031] As shown in FIG. 2, the injection hole plate 30 has first injection holes 31 and second injection holes 32 passing through the injection hole plate 30 in a plate thickness direction. The injection hole plate 30 is mounted on a lower end part of the nozzle 10 by welding or the like so as to cover the valve hole 12.

[0032] The first injection hole 31 has an inlet side opening end part 31a, which is open towards the nozzle 10, and an outlet side opening end part 31b, which is open towards the opposite side of the nozzle 10. The second injection hole 32 has an inlet side opening end part 32a, which is open towards the nozzle 10, and an outlet side opening end part 32b, which is open towards the opposite side of the nozzle 10. There are two first injection holes 31 pierced on a center side in the injection hole plate 30, and eight second injection holes 32 pierced on a radially outer side of the first injection holes 31 in the injection hole plate 30 (see FIG. 2).

[0033] In a plan view of the injection hole plate 30, in the first injection hole 31, the inlet side opening end part 3 la is formed into an oval shape having a major axis XI and a minor axis Yl, and the outlet side opening end part 31b is formed into an oval shape having a major axis X2 and a minor axis Y2. In the first injection hole 31, the center of the outlet side opening end part 31b is positioned on an outer side of the center of the inlet side opening end part 3 la in a radial direction of the injection hole plate 30. [0034] In the fuel injection valve 1 according to this embodiment, in the plan view of the injection hole plate 30, the shapes of the inlet side opening end part 31a and the outlet side opening end part 31b of the first injection hole 31 are ellipses that are an example of an oval shape. The oval shape is not limited to closed curve that is line symmetric with respect to at least a single axis, such as an ellipse, an egg shape, and an oblong, but includes a closed curve that is not line symmetric.

[0035] In the first injection hole 31 , the major axis XI of the inlet side opening end part 31a extends from the center side to a radially outer side of the injection hole plate 30, and the minor axis Y2 of the outlet side opening end part 31b extends from the center side of to the radially outer side the injection hole plate 30. The first injection hole 31 is formed so that a passage section is tapered and expands from the inlet side opening end part 31a to the outlet side opening end part 31b, and has a first angle (a first injection hole major axis angle) Θ1 and a second angle Θ2 (a first injection hole minor axis angle) (see FIG. 1 A and FIG. IB).

[0036] The first angle 01 is an angle formed by opposing inner wall surface parts of the first injection hole 31 in a section along an axis Zl of the first injection hole 31 and the major axis XI of the inlet side opening end part 31a of the first injection hole 31. The second angle, Θ2 is an angle formed by the opposing inner wall surface parts of the first injection hole 31 in a section along the axis Zl of the first injection hole 31 and the minor axis Yl of the inlet side opening end part 31 a of the first injection hole 31.

[0037] In the second injection hole 32, in a plan view of the injection hole plate 30, the inlet side opening end part 32a is formed into an oval shape having a major axis X3 and a minor axis Y3, and the outlet side opening end part 32b is formed into an oval shape having a major axis X4 and a minor axis Y4. In the second injection hole 32, the center of the outlet side opening end part 32b is positioned on an outer side of the center of the inlet side opening end part 32a in a radial direction of the injection hole plate 30.

[0038] In the fuel injection valve 1 according to this embodiment, in the plan view of the injection hole plate 30, the shapes of the inlet side opening end part 32a and the outlet side opening end part 32b of the second injection hole 32 are ellipses that are an example of an oval shape. The oval shape is not limited to closed curve that is line symmetric with respect to at least a single axis, such as an ellipse, an egg shape, and an oblong, but includes a closed curve that is not line symmetric.

[0039] In the second injection hole 32, the major axis X3 of the inlet side opening end part 32a extends from the center side to the radially outer side of the injection hole plate 30, and the minor axis Y4 of the outlet side opening end part 32b extends from the center side to the radially outer side of the injection hole plate 30. The second injection hole 32 is formed so that the passage section is tapered and expands from the inlet side opening end part 32a to the outlet side opening end part 32b, and has a third angle Θ3 (a second injection hole major axis angle) and a fourth angle Θ4 (a second injection hole minor axis angle) (see FIG. 1 A and FIG. 1C).

[0040] The third angle Θ3 is an angle formed by opposing inner wall surface parts of the second injection hole 32 in a section along an axis Z2 of the second injection hole 32 and the major axis X3 of the inlet side opening end part 32a of the second injection hole 32. , The fourth angle 04 is an angle formed by opposing inner wall surface parts of the second injection hole 32, in a section along the axis Z2 of the second injection hole 32 and the minor axis Y3 of the inlet side opening end part 32a of the second injection hole 32.

[0041] The injection hole plate 30 is structured so that the second angle Θ2 is larger than the first angle Θ1 in the first injection hole 31 , and the fourth angle Θ4 is larger than the third angle Θ3 in the second injection hole 32. The injection hole plate 30 is also structured so that the second angle 02 of the first injection hole 31 is smaller than the fourth angle Θ4 of the second injection hole 32. The injection hole plate 30 is structured so that the first angle Θ1 of the first injection hole 31 and the third angle Θ3 of the second injection hole 32 are generally the same.

[0042] The injection hole plate 30 is structured so that the passage sectional area of the inlet side opening end part 3 la of the first injection hole 31 is larger than the passage sectional area of the inlet side opening end part 32a of the second injection hole 32. Further, as shown in FIG. 3A, FIG. 3B, and FIG. 3C, the injection hole plate 30 is structured so that a spray area Fl of fuel injected from the first injection hole 31 and a spray area F2 of fuel injected from the second injection hole 32 do not overlap each other in a plan view. This is achieved by appropriately setting directions in which the first injection holes 31 and the second injection holes 32 pass through.

[0043] Next, operations of the fuel injection valve 1 according to this embodiment are explained.

[0044] The fuel injection valve 1 is assembled to a gasoline inlet port, and injects fuel in a state where the fuel is supplied from a pump (not shown) to the fuel supply passage 1 1 of the nozzle 10.

[0045] In the fuel injection valve 1 , once the valve body 20 is pulled up by the valve driving device (not shown), fuel in the fuel supply passage 1 1 flows into a gap between the valve seat 13 and an outer peripheral surface part of the lower end part of the valve body 20, and into the first injection holes 31 and the second injection holes 32 through the valve hole 12. Thus, the fuel injection valve 1 injects fuel towards the inlet port from the first injection holes 31 and the second injection holes 32.

[0046] Once the valve body 20 is pushed up by the valve driving device (not shown), the fuel injection valve 1 blocks communication between the fuel supply passage 1 1 and the valve hole 12. Thus, the fuel injection valve 1 suspends injection of fuel to the inlet port.

[0047] In the fuel injection valve 1 , the second angle Θ2 is larger than the first angle ,91 in the first injection hole 31 of the injection hole plate 30. Therefore, in the fuel injection valve 1 , a fuel liquid film of fuel injected outside from the first injection holes 31 becomes thinner in a direction of the major axis XI of the inlet side opening end part 31a. At the same time, the fuel liquid film expands in a direction of the minor axis Yl of the inlet side opening end part 31 a, thereby improving atomization of the fuel.

[0048] In the fuel injection valve 1 , the fourth angle 04 is larger than the third angle 03 in the second injection hole 32 of the injection hole plate 30. Therefore, in the fuel injection valve 1, a fuel liquid film of fuel injected outside from the second injection holes 32 becomes thinner in a direction of the major axis X3 of the inlet side opening end part 32a. At the same time, the fuel liquid film expands in a direction of the minor axis Y3 of the inlet side opening end part 32a, thereby improving atomization of the fuel.

[0049] Further, in the fuel injection valve 1 , the second angle Θ2 of the first injection hole 31 of the injection hole plate 30 is smaller than the fourth angle Θ4 of the second injection hole 32 of the injection hole plate 30. Therefore, in the fuel injection valve 1, a particle size of fuel injected outside from the first injection hole 31 becomes larger than a particle size of fuel injected outside from the second injection hole 32. In other words, in the fuel injection valve 1, kinetic energy of fuel injected outside from the first injection hole 31 becomes larger than kinetic energy of fuel injected outside from the second injection hole 32.

[0050] Thus, in the fuel injection valve 1 , penetration of fuel injected outside from the first injection hole 31 becomes larger than penetration of fuel injected outside from the second injection hole 32. In the fuel injection valve 1 , the particle size of fuel injected outside from the second injection hole 32 becomes smaller than the particle size of fuel injected outside from the first injection hole 31.

[0051] In the fuel injection valve 1 , the passage sectional area of the inlet side opening end part 31a of the first injection hole 31 is larger than the passage sectional area of the inlet side opening end part 32a of the second injection hole 32. Therefore, in the fuel injection valve 1, a fuel liquid film inside the first injection hole 31 becomes thicker than a fuel liquid film inside the second injection hole 32, and the particle size of fuel injected outside from the first injection hole 31 becomes larger than the particle size of the fuel injected outside from the second injection hole 32. In other words, in the fuel injection valve 1, kinetic energy of fuel injected outside from the first injection hole 31 becomes larger than kinetic energy of fuel injected outside from the second injection hole 32.

[0052] Hence, in the fuel injection valve 1, penetration of fuel injected outside from the first injection hole 31 becomes larger than penetration of fuel injected outside from the second injection hole 32. Also, in the fuel injection valve 1 , the particle size of fuel injected outside from the second injection hole 32 becomes smaller than the particle size of fuel injected outside from the first injection hole 31.

[0053] In the fuel injection valve 1 , the center of the outlet side opening end part 31b of the first injection hole 31 is positioned on the outer side of the center of the inlet side opening end part 31a in the radial direction of the injection hole plate 30. Therefore, in the fuel injection valve 1 , a diffusion range of fuel sprayed outside from the first injection hole 31 expands. In the fuel injection valve 1 , the center of the outlet side opening end part 32b of the second injection hole 32 is positioned on the outer side of the center of the inlet side opening end part 32a in the radial direction of the injection hole plate 30. Therefore, in the fuel injection valve 1 , a diffusion range of fuel sprayed outside from the second injection hole 32 expands.

[0054] In the fuel injection valve 1 , the directions in which the first injection hole 31 and the second injection hole 32 pass through the injection hole plate 30 are set so that the spray area Fl of fuel injected from the first injection hole 31 and the spray area F2 of fuel injected from the second injection hole 3,2 do not overlap each other. Therefore, a phenomenon happens in the fuel injection valve 1 , in which a flow of fuel injected outside from the second injection hole 32 is drawn into a flow of fuel injected outside from the first injection hole 31 due to viscosity of air.

[0055] Therefore, in the fuel injection valve 1, penetration of fuel injected outside from the first injection hole 31 becomes larger than penetration of fuel injected outside from the second injection hole 32. In the fuel injection valve 1, a particle size of fuel injected outside from the second injection hole 32 becomes smaller than a particle size of fuel injected outside from the first injection hole 31.

[0056] The inventors compared the fuel injection valve 1 according to this embodiment and the fuel injection valve according to a comparative example, and obtained knowledge stated below. The fuel injection valve according to the comparative example has a structure in which only eight second injection holes 32 pierce through the foregoing injection hole plate 30, and the first injection holes 31 are omitted. The fuel flow is under the same condition as that of the fuel injection valve 1 according to this embodiment. [0057] In FIG. 4, the solid line represents distribution of average particle sizes of fuel injected from the fuel injection valve 1 according to this embodiment, and the broken line represents distribution of average particle sizes of fuel injected from the_. fuel injection valve according to the comparative example. In the fuel injection valve 1 according to this embodiment, since the first injection holes 31 pierce through the injection hole plate 30, an average particle size of fuel in a center part of a fuel spray region is larger than that of the fuel injection valve according to the comparative example. Thus, penetration of fuel injected from the fuel injection valve 1 according to this embodiment becomes larger than that of the fuel injection valve according to the comparative example.

[0058] In the fuel injection valve 1 according to this embodiment, the condition of the fuel flow is the same as that of the fuel injection valve according to the comparative example. Therefore, the passage sectional area of the second injection hole 32 is smaller than a passage sectional area of the second injection hole of the fuel injection valve according to the comparative example, by an area obtained by subtracting the passage sectional area of the first injection hole 31. Thus, in the fuel injection valve 1 according to this embodiment, the particle size of fuel injected outside from the second injection hole 32 is smaller than a particle size of fuel injected outside from the second injection hole of the fuel injection valve according to the comparative example.

[0059] EIG. 5 and FIG. 6 are based on an observation result using the fuel injection valve 1 according to this embodiment and the fuel injection valve according to the comparative example. As shown in FIG. 5, in the fuel injection valve 1 according to this embodiment, an average particle size of fuel at an outer edge of a fuel spray region was generally equal to that of the , fuel injection valve according to the comparative example. As shown in FIG. 6, in the fuel injection valve 1 according to this embodiment, penetration of fuel is large because of the first injection hole 31 pierced through the injection hole plate 30. Therefore, a spray length of fuel was longer than that of the fuel injection valve according to the comparative example.

[0060] As stated above, in the fuel injection valve 1 according to this embodiment, the particle size of fuel injected outside from the second injection hole 32 is smaller than ! 6

the particle size of fuel injected outside from the first injection hole 31. In other words, in the fuel injection valve 1 according to this embodiment, atomization of fuel injected outside from the second injection hole 32 is achieved. Therefore, an amount of fuel adhered to an inner wall surface part of an inlet port is reduced, and introduction of fuel into a combustion chamber is promoted when an inlet valve is opened. Hence, it is possible to restrain an HC emission at a time of cold start of an engine.

[0061] In the fuel injection valve 1 according to this embodiment, penetration of fuel injected outside from the first injection hole 31 is larger than penetration of fuel injected outside from the second injection hole 32. In other words, in the fuel injection valve 1 according to this embodiment, fuel is not vaporized before reaching the combustion chamber, thereby improving an engine output. ^"

[0062] A technical scope of the fuel injection valve according to the invention is not limited to the foregoing embodiment, and may include various changes of the respective components stated in the claims without departing from the scope of the invention.

[0063] As stated so far, the fuel injection valve according to the invention has effects of reducing an HC emission at a time of cold start of an engine, and thus improving an engine output, and is useful for an gasoline engine that employs a port injection system.

Claims

CLAIMS:

1. A fuel injection valve comprising:

a nozzle having a valve hole;

a valve body provided inside the nozzle so as to open and close the valve hole; and an injection hole plate provided in the nozzle so as to cover the valve hole,

the injection hole plate being provided with a first injection hole and a second injection hole that pass through the injection hole plate in a plate thickness direction, the first injection hole and the second injection hole having inlet side opening end parts which are open towards the nozzle, and outlet side opening end parts which are open towards an opposite side of the nozzle,

the inlet side opening end parts of the first injection hole and the second injection hole having oval shapes in a plan view of the injection hole plate, each of the oval shapes having a major axis and a minor axis,

passage sections of the first injection hole and the second injection hole expanding from the inlet side opening end parts to the outlet side opening end parts, and,

a minor axis angle of the first injection hole being smaller than a minor axis angle of the second injection hole, the minor axis angle of the first injection hole being defined by opposing inner wall surface parts of the first injection hole in a section along the minor axis of the inlet side opening end part of the first injection hole including an axis of the first injection hole, the minor axis angle of the second injection hole being defined by opposing inner wall surface parts of the second injection hole in a section along the minor axis of the inlet side opening end part of the second injection hole including an axis of the second injection hole.

2. A fuel injection valve, comprising:

a nozzle having a valve hole;

a valve body provided inside the nozzle so as to open and close the valve hole; and an injection hole plate provided in the nozzle so as to cover the valve hole^

.the injection hole plate being provided with a first injection hole and a second injection hole that pass through the injection hole plate in a plate thickness direction, the first injection hole and the second injection hole having inlet side opening end parts which are open towards the nozzle, and outlet side opening end parts which are open towards an opposite side of the nozzle,

the first injection hole being pierced on a center side of the injection hole plate, the second injection hole being pierced on an outer side of the first injection hole in a radial direction of the injection hole plate,

inlet side opening end parts of the first injection hole and the second injection hole having oval shapes in a plan view of the injection hole plate, each of the oval shapes having a major axis and a minor axis,

passage sections of the first injection hole and the second injection hole expanding from the inlet side opening end parts to the outlet side opening end parts, a minor axis angle of the first injection hole being larger than a major axis angle of the first injection hole, the minor axis angle of the first injection hole being defined by opposing inner wall surface parts of the first injection hole in a section along the minor axis of the inlet side opening end part of the first injection hole including an axis of the first injection hole, the major axis angle of the first injection hole being defined by opposing inner wall surface parts of the first injection hole in a section along the major axis of the inlet side opening end part of the first injection hole including the axis of the first injection hole,

a minor axis angle of the second injection hole being larger than a major axis angle of the second injection hole, the minor axis angle of the second injection hole being defined by opposing inner wall surface parts of the second injection hole in a section along the minor axis of the inlet side opening end part of the second injection hole including an axis of the second injection hole, the major axis angle of the second injection hole being defined by opposing inner wall surface parts of the second injection hole in a section along the major axis of the inlet side opening end part of the second injection hole including the axis of the second injection hole, and

the minor axis angle of the first injection hole being smaller than the minor axis angle of the second injection hole.

3. The fuel injection valve according to claim 1 or 2, wherein, the injection hole plate is configured such that a passage sectional area of the inlet side opening end part of the first injection hole is larger than a passage sectional area of the inlet side opening end part of the second injection hole.

4. The fuel injection valve according to any one of claims 1 to 3, wherein the first injection hole and the second injection hole are configured such that a spray area of fuel injected from the first injection hole and a spray area of fuel injected from the second injection hole do not overlap each other.