JP2010185324A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of restraining atomization irregularity among injection holes with different injection angles. <P>SOLUTION: The fuel injection valve 10 comprises a valve body 21 forming a fuel passage 26 and having a valve seat 21b formed on the inner circumferential surface with the diameter narrowed toward the fuel downstream side, including an injection hole forming part 27 provided on the fuel downstream side of the valve seat and having an inner wall surface and an outer wall surface, and a plurality of injection holes 25 formed through the inner wall surface and the outer wall surface; and a valve member 30 stored in the valve body for intermittently injecting a fuel from the injection holes by being seated on or being separated from the valve seat. The injection hole forming part 27 has a flat inner wall surface part 22a out of the inner wall surface 22 for forming an inlet part 25b of the injection holes 25, and an outer wall surface part 24a out of the outer wall surface 24 for forming an outlet part 25a of the injection holes 25, the wall surface part 24a being formed in a spherical surface 80a projecting toward the fuel downstream side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that injects fuel.

  2. Description of the Related Art Conventionally, a fuel injection valve includes a valve member and a valve body that supports the valve member in an axially movable manner and has an inner wall surface that forms a fuel passage with an outer wall surface of the valve member. ing. The valve body is formed with a valve seat part on which the valve member is seated and separated on the inner wall surface, and an injection hole forming part on the downstream side of the valve seat part, and the injection hole forming part is provided with a plurality of injection holes. (See Patent Document 1).

  In this type of fuel injection valve, an inclination angle in which the central axis of the injection hole penetrating the injection hole forming part is inclined with respect to the injection hole forming part so that the injection direction of injection from the injection hole becomes a desired direction. Is set.

  As an example of such a fuel injection valve, the device disclosed in Patent Document 1 is configured to form the injection hole forming portion in a flat plate shape. In this technique, by changing the inclination angle of the injection hole formed in the injection hole forming portion, the injection direction, that is, the injection angle of injection from the injection hole is adjusted. The fuel injected from each nozzle hole set in this way forms a fuel spray such as a conical shape or a flat fan shape.

JP-A-3-264767

  Since the characteristics of the fuel spray are determined by the required performance of the engine equipped with the fuel injection valve, each injection hole formed in the injection hole forming portion is set to a different injection angle, that is, a different inclination angle. There is a case.

  In the prior art of Patent Document 1, the end surface of the injection hole forming portion having a flat plate shape, that is, both end surfaces of the injection hole inlet side and the injection hole outlet side are flat, so that the injection hole length changes depending on the target injection angle. It will be. In other words, since the nozzle hole lengths are different between the injection holes having different injection angles, there is a concern that the degree of atomization is different between the injection holes having different injection angles with respect to atomization of the fuel injected from the injection holes. There is.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel injection valve that suppresses variation in atomization between injection holes having different injection angles.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, in the invention according to any one of claims 1 to 6, the valve body has a valve seat on an inner peripheral surface that forms a fuel passage and is reduced in diameter toward the downstream side of the fuel, the fuel downstream side of the valve seat portion. A valve body having a nozzle hole forming portion having an inner wall surface and an outer wall surface, a plurality of nozzle holes penetrating the inner wall surface and the outer wall surface, and being accommodated in the valve body and seated on and separated from the valve seat portion. In a fuel injection valve comprising: a valve member that interrupts fuel injection from an injection hole by sitting
The nozzle hole forming portion is formed such that the inner wall surface portion where the inlet portion of the nozzle hole is formed is a flat surface of the inner wall surface, and the outer wall surface portion where the outlet portion of the nozzle hole is formed is the downstream side of the fuel. It is formed in the spherical surface which exhibits convex shape.

  According to this, the nozzle hole forming portion in which the plurality of nozzle holes are formed has a flat inner wall surface portion on the inlet portion side of the nozzle hole, and an outer wall surface portion on the outlet portion side of the nozzle hole on the fuel downstream side. Since it is set as the spherical surface to exhibit, the change of the nozzle hole length by the difference in the injection angle of each nozzle hole can be suppressed. Thereby, the dispersion | variation in atomization between each nozzle hole from which an injection angle differs can be suppressed.

  The invention according to claim 2 is characterized in that the convex spherical surface is formed for each nozzle hole formed in the nozzle hole forming portion.

  Here, as a method of forming a convex spherical surface, it is conceivable that the spherical surfaces formed at the outlets of the respective nozzle holes are continuously connected to form a convex spherical shape that protrudes downstream as a whole. . In this case, the change in the injection hole length due to the difference in the injection angle of each injection hole can be suppressed as compared with the case where both the inner wall surface and the outer wall surface of the prior art are flat, but as the injection angle is increased. There is a concern that the change in the nozzle hole length becomes large.

  On the other hand, according to the second aspect of the present invention, since each of the nozzle holes has a convex spherical surface, the radius of curvature of the convex spherical surface is larger than the nozzle hole length of each nozzle hole. Can be set to the same extent as the size of each nozzle hole length. Therefore, even if the injection angle is relatively large, the change in the injection hole length due to the difference in the injection angle of each injection hole can be effectively suppressed. Therefore, since it is possible to reduce or prevent the variation in the nozzle hole length due to the difference in the injection angle of each nozzle hole, the degree of atomization between the nozzle holes having different injection angles can be made uniform.

  In the invention described in claim 3, the injection hole is characterized in that the inlet portion is arranged on the same virtual circle centered on the central axis of the valve body.

  According to this, by arranging the inlet part of the nozzle hole on the same virtual circle centered on the central axis of the valve body, the inlet part fixed on the virtual circle is used as a base point, The injection angle, that is, the inclination angle of the central axis of the injection hole inclined with respect to the injection hole forming part of the valve body can be changed. According to such a configuration, it is possible to further enhance the effect of suppressing the change in the nozzle hole length due to the difference in the injection angle of each nozzle hole.

In the invention according to claim 4, the central axis of the injection hole is inclined with respect to the central axis of the valve body so that the outlet portion is located on the side away from or closer to the inlet portion,
The outer wall surface portion has a convex portion on which the spherical surface is formed along opposite directions on the side where the outlet portion is located and the side where the outlet portion is located with respect to the central axis of the valve body.

  According to this, in the said outer wall surface part, it becomes possible to set it as the structure which limits the spherical surface which exhibits convex shape to the opposite direction of the side to which an exit part is located, and the side which approaches. Since the shape of the outer wall surface portion having such a convex portion can be a simple surface such as a flat surface, the shape of the other surface of the convex portion where the spherical surface is not formed can be processed. It is possible to achieve a shape configuration that is easy to do.

  Further, the invention according to claim 5 is characterized in that the convex portion is connected in an annular shape in the direction in which the injection hole is formed in the injection hole forming portion where the injection hole is formed at a plurality of locations.

  Here, when the pitch interval between the plurality of nozzle holes formed in the nozzle hole forming portion is relatively small, the gap between the convex portions of each nozzle hole may be too small. There is a concern that it will be difficult to process.

  On the other hand, according to the invention described in claim 5, since the adjacent convex portions are configured to be connected in a ring shape, the change in the injection hole length due to the difference in the injection angle of each injection hole, and the outer wall surface portion It is possible to achieve both a shape configuration that is easy to process.

  The invention according to claim 6 is characterized in that 1.25 ≦ L / d ≦ 3 is satisfied, where L is the length in the central axis direction of the nozzle hole and d is the diameter of the nozzle hole.

  According to this, according to the fuel injection valve according to any one of claims 1 to 5, the index related to the nozzle hole length while suppressing the change in the nozzle hole length due to the difference in the injection angle of each nozzle hole. The value (L / d) can be set in a range of 1.25 ≦ L / d ≦ 3.

It is sectional drawing which shows the fuel injection valve concerning 1st Embodiment of this invention. It is sectional drawing which shows the surroundings of the fuel chamber of the fuel upstream of the nozzle hole formation part in FIG. 1, and a nozzle hole formation part. It is the top view which looked at the nozzle hole formation part from the fuel chamber side of FIG. It is the top view which looked at the nozzle hole formation part from the fuel downstream side of FIG. FIG. 5A is a diagram for explaining the relationship between the nozzle hole length L and the injection angle, FIG. 5A is a characteristic diagram showing the relationship between the nozzle hole length L and the injection angle, and FIG. 5B and FIG. FIG. 5B is a diagram illustrating the specification of each characteristic line in FIG. 5B, and is a schematic diagram illustrating Comparative Example 1 and this example, respectively. FIGS. 6A and 6B are diagrams for explaining the relationship between L / d and the degree of change in the injection angle and the particle diameter. FIG. 6A is a characteristic diagram showing the relationship between L / d and the injection angle, and FIG. It is a characteristic view which shows the relationship between / d and the change degree of a particle size. It is a figure which shows the nozzle hole formation part of the fuel injection valve concerning 2nd Embodiment, Comprising: Fig.7 (a) is a VIIA-VIIA sectional view in FIG.7 (b), FIG.7 (b) is a fuel downstream side. It is the top view which looked at the nozzle hole formation part. It is a figure which shows the nozzle hole formation part of the fuel injection valve concerning 3rd Embodiment, Comprising: Fig.8 (a) is a VIIIA-VIIIA line cross section in FIG.8 (b), FIG.8 (b) is a fuel downstream side. It is the top view which looked at the nozzle hole formation part. It is a figure which shows the nozzle hole formation part of the fuel injection valve concerning 4th Embodiment, Comprising: Fig.9 (a) is the IXA-IXA line cross section in FIG.9 (b), FIG.9 (b) is from a fuel downstream side. It is the top view which looked at the nozzle hole formation part. The relationship between L / d related to Comparative Example 1 corresponding to each characteristic line of FIG. 6A and Comparative Example 2 and Comparative Example 2 and the degree of change in the injection angle and particle size will be described. FIG. 10A is a characteristic diagram showing the relationship between L / d and the injection angle, and FIG. 10B is a characteristic diagram showing the relationship between L / d and the degree of change in particle size. FIG. 11 is an example of an embodiment in which a fuel injection valve is mounted on an engine, and is a view for explaining the relationship between the fuel injection valve of FIG. 1 and a combustion chamber of the engine, in which FIG. ) Is an arrow view seen from XIB.

  Hereinafter, each embodiment according to the present invention will be described with reference to the drawings.

(First embodiment)
1 to 4 and 11 show a fuel injection valve 10 according to the present embodiment. 2 to 4 show the characteristic parts of the fuel injection valve 10, and FIG. 11 schematically shows the overall configuration of the fuel injection device equipped with the fuel injection valve 10 according to the present embodiment.

  As shown in FIG. 11, the fuel injection valve 10 is attached to the cylinder head 61, and is formed by a wall surface of the cylinder head 61, an inner wall surface (hereinafter referred to as cylinder wall surface) 65 of the cylinder block 62, and an upper end surface 67 of the piston 66. This is a fuel injection device for a direct injection gasoline engine (hereinafter simply referred to as an engine) that directly injects fuel into the combustion chamber 64. The fuel injection valve 10 is supplied with fuel pressurized to a fuel injection pressure by a fuel supply pump (not shown). The fuel pressure is set to a predetermined pressure in the range of 1 MPa to 40 MPa, and the fuel injection valve 10 injects fuel at a fuel injection pressure corresponding to the range into the combustion chamber 64.

  As illustrated in FIG. 6, the fuel injection valve 10 is so-called center mounted between the intake valve 68 and the exhaust valve 69, that is, on the cylinder head 61. Further, an ignition device (not shown) is mounted on the cylinder head 61, and the ignition device is disposed at a position where the fuel injected from the fuel injection valve 10 does not directly adhere and at a position where the combustible air mixed with the fuel can be ignited. ing.

  The fuel spray injected from the fuel injection valve 10 is a conical spray, and is not directly attached to both the cylinder wall surface 65 and the upper end surface 67 of the piston 66 in the fuel injection valve 10 (FIG. 6B). A length from the center axis J1) to the tip of the spray (hereinafter referred to as spray length) is set to a predetermined spray length Ls with a gap from both 65 and 67.

  The overall configuration of the fuel injection device having the fuel injection valve 10 as the main configuration has been described above. Hereinafter, the basic configuration of the fuel injection valve 10 will be described.

(Basic configuration of the fuel injection valve 10)
As shown in FIG. 1, the housing 11 of the fuel injection valve 10 is formed in a cylindrical shape. The housing 11 has a first magnetic part 12, a nonmagnetic part 13, and a second magnetic part 14. The nonmagnetic part 13 prevents a magnetic short circuit between the first magnetic part 12 and the second magnetic part 14. The 1st magnetic part 12, the nonmagnetic part 13, and the 2nd magnetic part 14 are integrally connected by laser welding etc., for example.

  An inlet member 15 is installed at one end of the housing 11 in the axial direction. The inlet member 15 is fixed to the inner peripheral side of the housing 11 by press fitting or the like. The inlet member 15 has a fuel inlet 16. The fuel inlet 16 is supplied with fuel (in this embodiment, gasoline fuel) by the fuel supply pump. The fuel supplied to the fuel inlet 16 flows into the inner peripheral side of the housing 11 through a fuel filter 17 that removes foreign matter.

  A nozzle holder 20 is installed at the other end of the housing 11. The nozzle holder 20 is formed in a cylindrical shape, and a nozzle body 21 as a “valve body” is installed inside the nozzle holder 20. The nozzle body 21 is formed in a bottomed cylindrical shape, and is fixed to the nozzle holder 20 by, for example, press fitting or welding. The nozzle body 21 has an inner peripheral surface 21b formed in a bottomed cylindrical shape, which is formed on a conical inner wall surface 22 whose inner diameter is reduced as it approaches the tip as shown in FIG. 22 has a valve seat 23. A concave nozzle hole forming portion 27 is provided at the lower end of the valve seat portion 23.

  The nozzle body 21 has a plurality of openings (in this embodiment, open to the inner wall surface 22 and the outer wall surface 24 through the nozzle body 21 in the vicinity of the end opposite to the housing 11, that is, in the nozzle hole forming portion 27. , For example, six) nozzle holes 25. The fuel supplied to the fuel inlet 16 is injected from a nozzle hole 25 into a combustion chamber (hereinafter simply referred to as “inside of the cylinder”) 64 of a cylinder of the engine.

  FIG. 3 is a plan view showing the nozzle body 21 alone, and corresponds to a view taken along the arrow III in FIG. As illustrated in FIG. 3, the inlet portions 25 b of the plurality of nozzle holes 25 are arranged on the same virtual circle (hereinafter also referred to as pitch circle) K. That is, the plurality of nozzle hole inlet portions 25b are arranged on the virtual circle K in a single annular shape. The center of the imaginary circle K coincides with the central axis of the so-called fuel injection valve 10, and the central axis J1 of the housing 11, the nozzle holder 20 and the nozzle body 21 (hereinafter simply referred to as “the central axis J1 of the nozzle body 21”). Almost matches.

  Further, the pitch between the inlet portions 25 b of the adjacent nozzle holes 25 is formed on the virtual circle K at substantially equal pitch.

  The nozzle body 21 has a tip 21 in the axial direction, that is, a nozzle hole forming portion 27, which has a bottom 21a extending perpendicularly to the central axis J1, and a nozzle hole 25 is formed in the bottom 21a. It is. The cross section perpendicular to the central axis J2 of the nozzle hole 25, that is, the cross section of the nozzle hole 25 is circular. Further, the direction through which the nozzle hole 25 penetrates, that is, the central axis J2 is inclined so that the outlet portion 25a of the nozzle hole 25 is located outside the central axis J1 with respect to the inlet portion 25b of the nozzle hole 25. As shown in FIG. 2, the bottom of the nozzle hole forming portion 27 and the valve seat portion 23 are smoothly connected with a curved surface.

  The inner peripheral surface 21b of the nozzle body 21 is formed with a nozzle hole forming portion 27 that is recessed toward the nozzle hole 25 between the conical inner wall surface 22 and the inlet port 25b of the nozzle hole 25. It becomes. As a result, the fuel chamber 70 facing the nozzle hole forming portion 27 always communicates with the inlet portions 25b of the plurality of nozzle holes 25, and distributes the fuel flowing into the fuel chamber 70 to the plurality of nozzle holes 25. It makes it easier.

The housing 11, the nozzle holder 20, and the nozzle body 21 constitute a valve body that forms a storage chamber therein. A needle 30 as a “valve member” is accommodated in the accommodation room. The needle 30 is accommodated on the inner peripheral side of the housing 11, the nozzle holder 20, and the nozzle body 21 so as to be capable of reciprocating in the axial direction.

  The needle 30 is disposed substantially coaxially with the nozzle body 21. The needle 30 includes a shaft portion 31, a head portion 32, a seat portion 33, and a tip portion 34. The head portion 32 is located at the end portion of the shaft portion 31 on the fuel inlet 16 side in the axial direction, and the seat portion 33 is located at the end portion of the shaft portion 31 on the nozzle hole 25 side. The seat portion 33 can be brought into contact with and separated from the valve seat portion 23 of the nozzle body 21 as shown in FIG.

  The front end portion 34 has frustoconical end surfaces 35 and 36 extending inwardly from the lower end of the seat portion 33. The end surfaces 35, 36 are a conical first end surface (hereinafter referred to as an inclined surface) 35 having an angle different from the diameter reduction angle of the seat portion 33, and a second end surface (hereinafter referred to as a bottom end 21 a) substantially parallel to the bottom portion 21 a of the nozzle hole forming portion 27. (Opposing end face) 36.

  A fuel passage 26 through which fuel flows is formed between the outer peripheral surface 30 a of the needle 30 and the inner peripheral surface 21 b of the nozzle body 21, and the fuel passage 26 is provided so as to communicate with the injection hole 25. In the fuel passage 26, the seat portion 33 and the valve seat portion 23 are separated and seated, whereby the fuel flowing through the nozzle hole 25 is blocked and allowed.

  Moreover, the fuel injection valve 10 is provided with the drive part 40 which drives the needle 30 as shown in FIG. The drive unit 40 includes a spool 41, a coil 42, a fixed core 43, a plate housing 44, and a movable core 50. The spool 41 is installed on the outer peripheral side of the housing 11. The spool 41 is formed of a resin material in a cylindrical shape, and a coil 42 is wound on the outer peripheral side. Both ends of the wound coil 42 are electrically connected to the terminal portion 46 of the connector 45. A fixed core 43 is installed on the inner peripheral side of the coil 42 with the housing 11 in between. The fixed core 43 is formed in a cylindrical shape from a magnetic material such as iron, and is fixed to the inner peripheral side of the housing 11 by, for example, press fitting. The plate housing 44 is made of a magnetic material and covers the outer peripheral side of the coil 42.

  The movable core 50 is disposed on the same axis as the fixed core 43 and can reciprocate in the axial direction on the inner peripheral side of the housing 11. The movable core 50 is formed in a cylindrical shape from a magnetic material such as iron. The movable core 50 has a cylindrical portion 51 on the side opposite to the fixed core 43, and the head portion 32 of the needle 30 is press-fitted into the cylindrical portion 51. Thereby, the needle 30 and the movable core 50 are integrally connected, for example, by welding or the like, and can cooperate with each other.

  The movable core 50 is provided with a spring 18 made of an elastic material as an “urging member” at the end on the fixed core 43 side. The spring 18 has a force in a direction extending in the axial direction (hereinafter referred to as an urging force), and is disposed so that both ends of the spring 18 are sandwiched between the movable core 50 and the adjusting pipe 19. The spring 18 presses the movable core 50 and the needle 30 in the direction in which the movable seat 50 and the needle 30 are seated on the valve seat portion 23. Further, the adjusting pipe 19 is structured to be fixed to the fixed core 43 by, for example, press-fitting, and by adjusting the press-fitting amount of the adjusting pipe 19 press-fitted to the fixed core 43, the spring 18 The biasing force (load) is adjusted.

  When the coil 42 is not energized, the movable core 50 and the needle 30 integrated with the movable core 50 are pressed toward the valve seat portion 23, and the seat portion 33 is seated on the valve seat portion 23. As a result, fuel injection from the nozzle hole 25 is blocked. When the coil 42 is energized, the movable core 50 is attracted by the fixed core 43, the needle 30 is separated from the valve seat portion 23, and fuel is injected from the injection hole 25.

  Here, the state where the needle 30 is separated from the valve seat portion 23 is referred to as when the needle 30 is lifted. The lift amount of the needle 30 is determined by the air gap between the magnetic pole surfaces of the movable core 50 and the fixed core 43.

  The basic configuration of the fuel injection valve 10 has been described above. Hereinafter, a characteristic configuration of the fuel injection valve 10 will be described.

(Characteristic configuration of the fuel injection valve 10)
The fuel passage 26 is formed between the inner peripheral surface of the valve bodies 11, 20, and 21 and the outer peripheral surface of the needle 30, and refers to a passage through which fuel flows, and will be described with reference to FIGS. 2 and 3 below. The term “fuel passage 26” simply means a passage formed between the inner peripheral surface 21 b of the nozzle body 21 and the outer peripheral surface 30 a of the needle 30.

  As shown in FIG. 2, in the fuel passage 26, a fuel passage portion that is formed between the inner peripheral surface 21 b of the nozzle body 21 and the outer peripheral surface 30 a of the needle 30 and extends in the axial direction of the fuel injection valve 10 is the first. A fuel passage portion formed between the conical inner wall surface 22 and the injection hole forming portion 27 and the seat portion 33 and the tip end portion 34 of the needle 30 is referred to as a second fuel passage 26b.

  The first fuel passage 26 a is formed as an annular passage extending in the axial direction, and the second fuel passage 26 b extends inward from the downstream end of the first fuel passage 26 a and communicates with the plurality of injection holes 25. Formed.

  The second fuel passage 26b is formed of a concave injection hole forming portion 27 and a tip portion 34 on the downstream side of the valve seat portion 23 and the seat portion 33 that block and allow the fuel flowing through the fuel passage 26. A fuel chamber 70 is provided. When the seat portion 33 is separated from the valve seat portion 23, the main flow direction of the flow of the fuel flowing out to the fuel chamber 70 is the reduced diameter of the valve seat portion 23 in the inner wall surface 22 that is reduced in diameter toward the fuel downstream side. Almost determined by direction.

Here, the structure of the seat part 33 and the valve seat part 23 is set as follows. That is, the needle 30 has a seat angle β, which is a sandwiching angle of the seat surface 33a of the seat portion 33, set in a range of 80 ° to 130 °. Further, the nozzle body 21 is formed such that the sandwiching angle of the valve seat portion 23 on which the seat portion is seated and separated is substantially the same as or slightly smaller than the seat angle β.
(Characteristic configuration related to the nozzle hole forming portion 27)
Here, since the injection angle αs of the fuel spray shown in FIG. 2 is determined by the required performance of the engine on which the fuel injection valve 10 is mounted, each injection hole 25 formed in the injection hole forming portion 27 has a different injection. There is a concern that the angle αs is set. Since the injection hole length L varies depending on the target injection angle αs, the degree of atomization differs between the injection holes 25 having different injection angles αs. 2 to 4 show an example of the injection holes 25 set at different injection angles αs.

  The injection angle αs represents an injection main flow direction J3 of the injected fuel (spray) actually injected from the injection hole 25 indicated by a two-dot chain line in FIG. 2 as an inclination with respect to the central axis J1 of the nozzle body 21. In addition, the inclination angle αh of the nozzle hole 25 represents the central axis J2 of the inlet portion 25b and the outlet portion 25a as an inclination with respect to the central axis J1 of the nozzle body 21.

  Here, although the injection angle αs may slightly deviate from the inclination angle αh of the injection hole 25, the injection angle αs is substantially the same as the inclination angle αh.

  The configuration of the inclination angle αh of the injection hole 25 shown in FIGS. 3 and 4 shows one injection hole having a first inclination angle, and the other injection holes having a second inclination angle. That is, the two inclination angles αh are the first inclination angle by the injection hole 25 (the injection hole located on the left side in FIG. 2) indicated by the inlet 25b (1) and the outlet 25a (1) in the drawing. The second inclination angle by the nozzle hole 25 (the nozzle hole located on the right side in FIG. 2) indicated by the inlet 25b (2) and outlet 25a (1) in the figure.

  Here, the injection angle αs related to the injection hole 25, that is, the inclination angle αh is set as follows. Is set in the range of −10 ° to 40 °. In addition, Preferably, the range of inclination-angle (alpha) h is 0 degrees-40 degrees.

  Therefore, in this embodiment, the characteristic configuration related to the nozzle hole forming portion 27 is set as follows. That is, the nozzle hole forming part 27 that is recessed with respect to the valve seat part 23 has a flat inner surface part 22a where the inlet part 25b is formed among the inner wall surface 22 and the outer wall surface 24 through which the nozzle hole 25 passes, and the outlet part 25a. The outer wall surface portion 24a is formed as a spherical surface 80a having a convex shape on the fuel downstream side.

  By configuring in this way, compared with the prior art in which both the inner wall surface and the outer wall surface are flat (see Comparative Example 1 in FIG. 5B), the injection due to the difference in the inclination angle αh of each nozzle hole 25. The change in the hole length L can be suppressed.

  The convex spherical surface 80 a is formed for each nozzle hole 25. And as for the outer wall surface part 24a, the convex part 80 which has the spherical surface 80a for every nozzle hole 25 protrudes from the bottom part 21a to the fuel downstream side.

  The convex portion 80 is disposed so as to be located immediately below the inlet portion 25b located on the virtual circle K in the bottom portion 21a. According to this, by setting the inlet portion 25b on the virtual circle K, the inclination angle αh of the injection hole 25, that is, the injection angle αs is changed with the inlet portion 25b fixed on the virtual circle K as a base point. You can do it. According to such a configuration, it is possible to further enhance the action of suppressing the change in the nozzle hole length L due to the difference in the injection angle αs of each nozzle hole 25.

  Here, FIG. 5 shows the relationship between the nozzle hole length L and the injection angle αs (inclination angle αh). In Comparative Example 1 in which the surface on the outlet portion 25a side is a flat surface, a variation width (variation width) of about 2 mm is generated in the setting range of the injection angle αs of −10 ° to 40 °. On the other hand, in this embodiment, the fluctuation range can be suppressed to a slight amount.

  Furthermore, since the spherical surface 80a having a convex shape is formed individually for each nozzle hole 25, the radius of curvature at the convex portion 80 having the convex spherical surface 80a is set to the nozzle hole length L of each nozzle hole 25. It is possible to set the nozzle hole length L to the same level as the size of each nozzle hole length L. Therefore, even when the injection angle αs is relatively large, the change in the injection hole length L due to the difference in the injection angle αs of each injection hole 25 can be effectively suppressed.

  Therefore, it is possible to reduce or prevent the variation in the injection hole length L due to the difference in the injection angle αs of each injection hole 25, so that the degree of atomization can be made uniform between the injection holes 25 having different injection angles αs. .

  Here, FIG. 6A shows the relationship between the index value (L / d) and the injection angle αs (inclination angle αh), and FIG. 6B shows the degree of change in the index value (L / d) and the particle size. It shows the relationship. The index value (L / d) is an index value related to the nozzle hole length L and is a ratio of the nozzle hole length L to the diameter of the nozzle hole 25. Note that the variation in particle size in FIG. 6B indicates the degree of change in particle size based on the particle size when L / d = 1.5.

  In Comparative Example 1, that is, when both surfaces of the bottom portion 21a are flat, the value of L / d varies in the range of about 1.5 to 2 and 1 with respect to the setting range of the injection angle αs. As a result, the particle size varies by about 0 to 5.7%. On the other hand, in this embodiment, it is possible to prevent the variation in the injection hole length L due to the difference in the injection angle αs of each injection hole 25. Therefore, the degree of atomization between the nozzle holes 25 having different injection angles αs can be made uniform.

  In addition, the inventor is the case where the spherical surface 80a formed in the exit part 25a of each nozzle hole 25 is continuously connected as a method of forming the convex spherical surface 80a, and the bottom part 21a is downstream of the fuel as a whole. The case of forming a convex spherical shape protruding to the side (see Comparative Example 2 in FIG. 10) was also examined. FIG. 10 shows Comparative Example 2 in comparison with Comparative Example 1. FIG. 10A shows the relationship between the index value (L / d) and the injection angle αs (tilt angle αh). (B) shows the relationship between the index value (L / d) and the degree of change in particle size.

  Although the comparative example 2 can reduce the variation in the injection hole length L due to the difference in the injection angle αs as compared with the comparative example 1, the change in the injection hole length L increases as the injection angle αs (inclination angle αh) increases. There are concerns. Therefore, in this embodiment, the convex spherical surface 80a is formed for each nozzle hole 25, so that the variation in the nozzle hole length L can be effectively reduced as compared with Comparative Example 2. As a result, in this embodiment, it is possible to provide an excellent configuration that makes the degree of atomization uniform between the injection holes 25 having different injection angles αs.

(Characteristic configuration related to the fuel passage 26)
The inventor has obtained the following knowledge. That is, if a fuel flow velocity gradient (hereinafter simply referred to as “velocity gradient”) at the outlet 25a of the nozzle hole 25 is formed large, the fuel portion on the high speed side of the mass of injected fuel (hereinafter referred to as “fuel mass”) The fuel portion on the low speed side can be easily pulled off, and the division of the fuel mass can be promoted. Injected fuel having such an effectively enhanced velocity gradient promotes atomization due to shearing with the surrounding air for each fissured part of the fuel mass. The atomization is promoted without making it.

  However, in the conventional fuel injection valve disclosed in JP-A-3-264767 (Patent Document 1), even when the main flow of fuel flows into the fuel chamber when the seat portion is separated from the valve seat portion, There is a concern that it does not flow straight into the inlet of the nozzle hole and bending loss occurs.

  If bending loss occurs in the "fuel flow including the main flow" until it flows into the inlet 25b, the flow energy decreases and the flow velocity flowing into the inlet 25b decreases. The fuel injection speed is reduced. This means that in addition to the injection speed reduction factor due to the formation of the velocity gradient, other injection speed reduction factors increase.

  Therefore, in the fuel passage 26, the configuration of the second fuel passage 26b, which is a passage extending from the downstream end of the first fuel passage 26a to the inside of the ring and communicating with the plurality of injection holes 25, is set as follows.

  That is, the nozzle body 21 is on the virtual extension line ms with respect to the virtual extension line ms extending in the direction of diameter reduction of the valve seat portion 23 on the virtual plane (the paper surface of FIG. 2) including the central axis J2 of the nozzle hole 25. The inlet 25b of the nozzle hole 25 is positioned.

  Further, the inlet portion 25b is arranged at a position where the virtual extension line ms intersects the injection hole inner peripheral surface 25c on the inlet portion 25b side. In other words, each nozzle hole 25 arranged on the virtual circle K can form the intersection mc of the virtual extension line ms on the inner peripheral surface 25c of the nozzle hole by the virtual extension line ms.

  Thereby, since the main flow direction of the fuel can be controlled to a flow that flows straight into the inlet portion 25b, the fuel flows even after the main flow of the fuel passes through the valve seat portion 23 when the needle 30 is separated from the valve seat portion 23. Suppresses flow bending loss. Therefore, it is possible to cause the fuel to flow into the inlet 25b while suppressing a decrease in the fuel flow energy.

  According to the above configuration, the main flow direction of the fuel can be controlled to the direction of flowing straight into the inlet portion 25b of the nozzle hole 25. Therefore, the main flow of fuel flows into the inlet portion 25b while suppressing a decrease in flow energy. Can be made.

  Moreover, since the main flow of the fuel collides with the inner peripheral surface 25c of the nozzle hole when flowing into the inlet 25b, the fuel moves from the inlet 25b side to the outlet 25a along the inner peripheral surface 25c of the collided nozzle hole. In the meantime, the fuel can be disturbed, and as a result, the velocity gradient at the outlet 25a can be greatly increased.

  Here, regarding the configuration in which the inlet portion 25b is arranged on the virtual circle K, the relationship between the inlet portion 25b and the sheet portion 33 is preferably set to the following configuration.

  That is, if the diameter of the virtual circle K is Dp and the sheet diameter of the sheet portion 33 is Ds, the ratio (Ds / Dp) of the virtual circle K diameter Dp to the sheet diameter Ds is 1.5 ≦ Ds / Dp ≦ 3. It is set to satisfy. With such a configuration, the velocity gradient can be further increased.

(Second Embodiment)
A second embodiment is shown in FIG. The second embodiment is a modification of the first embodiment. FIG. 7 shows a part of the fuel injection valve, and shows the periphery of the injection hole forming portion 27 and the fuel chamber 70.

  The outer wall surface portion 24a of the nozzle hole forming portion 27 is configured as follows. That is, as shown in FIG. 7B, the spherical surface 80a of the convex portion 80 has a spherical surface 80a over the range in which the outlet portion 25a is located in the setting range of the injection angle αs (range of αs = −10 ° to 40 °). Is formed. And the surface of the convex part 80 is formed as a simple flat surface other than the spherical surface 80a.

  In other words, in the outer wall surface portion 24a, the convex spherical surface 80a can be limited to the opposite directions on the side where the outlet 25a is located and the side where the outlet 25a is located. Since the shape of the outer wall surface portion 24a having such a convex portion 80 can be a simple surface such as a flat surface, the shape of the other surface of the convex portion 80 where the spherical surface 80a is not formed can be formed. The wall surface portion 24a can be easily shaped.

(Third embodiment)
A third embodiment is shown in FIG. The third embodiment is a modification of the first embodiment. FIG. 8 shows a part of the fuel injection valve, and shows the periphery of the injection hole forming portion 27 and the fuel chamber 70.

  Here, when the pitch interval between the plurality of nozzle holes 25 formed in the nozzle hole forming portion 27 is relatively small, the gap between the convex portions 80 of each nozzle hole 25 may be too small. Therefore, there is a concern that it is difficult to process the outer wall surface portion 24a.

  On the other hand, in this embodiment, as shown in FIG.8 (b), it is set as the structure which connects the adjacent convex parts 80 cyclically | annularly. Thereby, it is possible to achieve both the suppression of the change in the nozzle hole length L due to the difference in the injection angle αs of each nozzle hole 25 and the securing of a shape and shape that allows easy processing of the outer wall surface portion 24a.

(Fourth embodiment)
A fourth embodiment is shown in FIG. The fourth embodiment is a modification of the third embodiment. FIG. 9 shows a part of the fuel injection valve, and shows the periphery of the injection hole forming portion 27 and the fuel chamber 70.

  In the present embodiment, the convex portions 80 described in the third embodiment that connect adjacent members in an annular shape are formed in an annular body having a semicircular cross section. Thereby, it can be set as the shape of a further simple outer wall surface part, and, by extension, the outer wall surface part 24a can be made into the shape structure excellent in workability.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is limited to this embodiment and is not interpreted and can be applied to various embodiment within the range which does not deviate from the summary.
(1) In the present embodiment described above, the shape of the fuel chamber 70 according to the second invention is such that the valve seat portion 23 and the outer peripheral side of the bottom portion 21a of the concave nozzle hole forming portion 27 are connected by a smooth curved surface. However, a curved surface may not be formed.

That is, the nozzle body 21 as the valve body is configured to form the concave nozzle hole forming portion 27 and the nozzle hole 25, but the nozzle hole forming member as the nozzle hole forming portion separate from the nozzle body is provided, It is good also as a structure which forms a nozzle hole in the said nozzle hole formation member.
(2) In the present embodiment described above, the inner wall surface portion 22a on the bottom portion 21a side of the injection hole forming portion 27 is configured to be planar throughout the bottom portion 21a. Not only this but a structure which provides a level | step-difference part in the radial direction inner side area | region, for example from the inlet part 25b among the inner wall surface part 22a, and the inner wall surface part in which the inlet part 25b is formed should just be a plane.
(3) In the present embodiment described above, the six injection holes 25 are arranged on the virtual circle K in a single annular shape. However, the number of the nozzle holes 25 is not limited to this, and may be two, four, eight, or the like. In addition, when the number of the nozzle holes 25 is two, instead of defining the diameter (pitch diameter) of the virtual circle K as Dp, the pitch between the nozzle holes 25 may be defined as Dp.
(4) When the spray shape from the fuel injection valve 10 is formed in a flat fan shape, the flat fan-shaped spray is not limited to one formed by the injection from the fuel injection valve 10, A plurality may be formed.
(5) Further, in the present embodiment described above, the direction of the central axis J2 of the nozzle hole 25 is located on the side where the outlet portion 25a of the nozzle hole 25 is farther from the central axis J1 of the nozzle body 21 than the inlet portion 25b. It was set as the structure which inclined like this. With such a configuration, when the needle 30 is lifted, when the main flow of fuel flows into the inlet portion 25b of the nozzle hole 25, the central axis of the nozzle body 21 on the inner peripheral surface of the nozzle hole 25 on the inlet portion 25b side. The mainstream can be effectively pressed against the inner peripheral surface portion of the nozzle hole closer to J1. Therefore, a speed gradient that is effectively and effectively increased is formed between the inner peripheral surface portion far from the inner peripheral surface portion closer to the central axis J1 in the outlet portion 25a.
(6) In the present embodiment described above, the fuel injection valve 10 according to the present embodiment has a characteristic configuration (A) related to the nozzle hole forming portion 27 and a characteristic configuration (B) related to the fuel passage 26. It was set as the structure which has. It is not necessary to have the characteristic configuration (A) and the characteristic configuration (B) at the same time, as long as the fuel injection valve has at least the characteristic configuration (A).
(7) In the present embodiment described above, the value of the inclination angle αh of the nozzle hole 25 is set to −10 ° ≦ αh ≦ 45. In this case, the value of αh is not −0 ° ≦ αh ≦ 45 but −10 ° ≦ αh ≦ 45, so that the degree of freedom in setting the spray shape is improved and the fuel adheres to spark plugs other than the wall surfaces 65 and 67. Prevention can be achieved. For example, among the nozzle holes 25 formed in the nozzle hole forming part 27, the value of the inclination angle αh of the injection hole in the injection main flow direction J3 that is injected toward the spark plug side is the inclination αh of the other injection holes. It becomes easy to make the values greatly different.
(8) In the present embodiment described above, the nozzle hole length L is set so that the index value (L / d) related to the nozzle hole length L satisfies the range of 1.25 ≦ L / d ≦ 3. May be set. According to this, while setting the index value (L / d) related to the nozzle hole length in the range of 1.25 ≦ L / d ≦ 3, the change in the nozzle hole length due to the difference in the injection angle of the nozzle hole is suppressed. can do.

10 Fuel Injection Valve 11 Housing (Valve Body)
20 Nozzle holder (valve body)
21 Nozzle body (valve body)
21a Bottom part 21b Inner peripheral surface 22 Inner wall surface (a part of inner peripheral surface to be reduced in diameter)
22a Inner wall surface portion 23 Valve seat portion 24 Outer wall surface 24a Outer wall surface portion 25 Injection hole 25a Outlet portion 25b Inlet portion 25c Inner peripheral surface 26 Fuel passage 26a First fuel passage 26b Second fuel passage 27 Injection hole forming portion 30 Needle (Valve member)
33 Seat portion 33a Seat surface 34 Tip portion 70 Fuel chamber 80 Convex portion 80a Spherical surface Dp Diameter of virtual circle d Diameter of injection hole Ds Seat diameter of seat part αh Inclination angle (target injection angle) of injection hole
αs Spray angle of fuel actually injected (injection angle)
J1 Center axis of nozzle body J2 Center axis of nozzle hole J3 Main injection direction of spray (injected fuel) K Virtual circle ms Virtual extension line mc Intersection

Claims (6)

A valve body that forms a fuel passage and has a valve seat portion on an inner peripheral surface that decreases in diameter toward the fuel downstream side, and is provided on the fuel downstream side of the valve seat portion and has an inner wall surface and an outer wall surface. A valve body having a hole forming portion and a plurality of injection holes penetrating the inner wall surface and the outer wall surface;
A valve member that is accommodated in the valve body and that interrupts fuel injection from the nozzle hole by being seated and separated from the valve seat portion;
In a fuel injection valve comprising:
The nozzle hole forming part is
Of the inner wall surface, the inner wall surface portion where the inlet of the nozzle hole is formed is formed in a plane,
The fuel injection valve characterized in that, of the outer wall surface, an outer wall surface portion where the outlet portion of the nozzle hole is formed is formed in a spherical surface having a convex shape on the fuel downstream side.   2. The fuel injection valve according to claim 1, wherein the spherical surface having the convex shape is formed for each of the injection holes formed in the injection hole forming portion.   3. The fuel injection valve according to claim 1, wherein the inlet of the injection hole is arranged on the same virtual circle centered on a central axis of the valve body. The central axis of the nozzle hole is inclined with respect to the central axis of the valve body so that the outlet portion is located on the side away from or closer to the inlet portion,
The outer wall surface portion has a convex portion in which the spherical surface is formed along opposite directions on the side where the outlet portion is located and the side where the outlet portion is located with respect to the central axis of the valve body. The fuel injection valve according to any one of claims 1 to 3.   5. The fuel injection valve according to claim 4, wherein the convex portion is connected in an annular shape in a direction in which the injection hole is formed in the injection hole forming portion where the injection hole is formed at a plurality of locations. When the length in the central axis direction of the nozzle hole is L and the diameter of the nozzle hole is d,
1.25 ≦ L / d ≦ 3
The fuel injection valve according to any one of claims 1 to 5, wherein:

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