Fuel injection valve manufacturing method and fuel injection valve

Abstract

This fuel injection valve manufacturing method comprises: a nozzle plate forming step for forming a nozzle plate in which a plurality of fuel injection holes are bored; and a nozzle plate joining step for joining the nozzle plate to an end surface of a valve seat member. The nozzle plate forming step includes: a fuel injection hole forming step for forming the fuel injection holes in the plate; and a correction step for correcting a distortion of the plate caused during the fuel injection hole forming step such that the plate fits along the end surface of the valve seat member while avoiding a range in which the fuel injection holes are formed. In the nozzle plate joining step, a surface corrected during the correction step is joined to the end surface of the valve seat member.

Description

Fuel injection valve manufacturing method and fuel injection valve

[0001] The present invention relates to a method for manufacturing a fuel injection valve and a fuel injection valve.

[0002] For example, Patent Document 1 discloses an injector having a plate with a plurality of fuel injection holes formed therein. The injector disclosed in Patent Document 1 also has a valve seat against which a valve body abuts. In Patent Document 1, the plate is fixed so as to cover the opening of the valve seat from the outside.

[0003] Japanese Patent Application Laid-Open No. 2005-207274

[0004] Although the plate is formed from a flat plate, distortion may occur when forming fuel injection holes such as those disclosed in Patent Document 1 in the plate. For example, the fuel injection holes are formed using a punch press. When the plate is pressed by the punch press, distortion may occur. The fuel injection valve disclosed in Patent Document 1 includes a holder for suppressing such distortion of the plate. This holder is fixed to the body of the fuel injection valve. However, if such a holder is provided as a separate body, the number of parts increases, complicating the structure of the fuel injection valve. Furthermore, a mounting location for the holder must be provided on the body, which increases the size of the body.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a fuel injection valve that does not require a holder for suppressing distortion of a plate having fuel injection holes, and a method for manufacturing the same.

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] A first aspect of the present invention is a method for manufacturing a fuel injection valve, comprising: a nozzle plate forming step of forming a nozzle plate having a plurality of fuel injection holes perforated therein; and a nozzle plate joining step of joining the nozzle plate to an end face of a valve seat member, wherein the nozzle plate forming step comprises: a fuel injection hole forming step of forming the fuel injection holes in a plate; and a correction step of correcting distortion of the plate caused in the fuel injection hole forming step so that the plate conforms to the end face of the valve seat member, avoiding an area in which the fuel injection holes are formed; and wherein the nozzle plate joining step joins the surface corrected in the correction step to the end face of the valve seat member.

[0008] A second aspect of the present invention is a fuel injection valve including a nozzle plate having a plurality of fuel injection holes formed therein and a valve seat member having an end surface to which the nozzle plate is joined, wherein the nozzle plate has a straightening surface that is provided to avoid an area in which the fuel injection holes are formed, the straightening surface being a surface that is straightened to fit along the end surface of the valve seat member and is joined to the end surface of the valve seat member.

[0009] According to the present invention, since the distortion of the nozzle plate is corrected, it is not necessary to hold the nozzle plate joined to the valve seat member with a holder. Therefore, according to the present invention, it is possible to provide a fuel injection valve and a manufacturing method thereof that do not require a holder for suppressing distortion of the plate having the fuel injection holes.

[0010] Fig. 1 is a schematic cross-sectional view showing a general configuration of a fuel injection valve according to one embodiment of the present invention; Fig. 2 is a schematic enlarged cross-sectional view including a valve seat member and a nozzle plate provided in the fuel injection valve according to one embodiment of the present invention; Fig. 3 is a top view of a nozzle plate provided in the fuel injection valve according to one embodiment of the present invention; Fig. 4 is a flowchart for explaining a manufacturing method of a fuel injection valve according to one embodiment of the present invention; Fig. 5 is a schematic view for explaining a correction step in the manufacturing method of a fuel injection valve according to one embodiment of the present invention;

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing a fuel injection valve and a fuel injection valve according to the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a schematic cross-sectional view showing the overall configuration of a fuel injection valve 1 according to this embodiment. The fuel injection valve 1 according to this embodiment is an electromagnetic valve device that injects and supplies fuel to an internal combustion engine. The fuel injection valve of the present invention is particularly suitable for a port injection type fuel injection valve that injects fuel into an intake port. As shown in FIG. 1, the fuel injection valve 1 according to this embodiment includes a valve housing 2, a valve assembly 3, an inner collar 4, a spring 5, a filter member 6, a covering portion 7, and a coil unit 8.

[0013] The valve housing 2 is a component having a fuel passage R therein that guides the fuel X. In this embodiment, the valve housing 2 includes a fuel inlet tube 2a, a fixed core 2b, a non-magnetic cylindrical body 2c, a magnetic cylindrical body 2d, a valve seat member 2e, and a nozzle plate 2f. In the following description, for convenience of explanation, the direction in which the fuel X is guided through the fuel passage R is referred to as the up-down direction, with the upstream end of the fuel passage R referred to as the upper side and the downstream end of the fuel passage R referred to as the lower side. However, the installation orientation of the fuel injection valve 1 of this embodiment is not limited to the case in which the up-down direction is parallel to the direction of gravity.

[0014] The fuel inlet tube 2a is a cylindrical member located at the top of the valve housing 2. The internal space of the fuel inlet tube 2a forms the upper part of the fuel passage R. The fuel inlet tube 2a is located above the fixed core 2b, and its lower end is fitted into the upper end of the fixed core 2b.

[0015] The fixed core 2b is a cylindrical member located between the fuel inlet tube 2a and the non-magnetic cylindrical body 2c in the vertical direction. The fixed core 2b has a through hole that penetrates in the vertical direction. This through hole forms part of the fuel passage R. The lower surface of the fixed core 2b is the abutment surface for a movable core 3c (described later) of the valve assembly 3. The upward movement of the valve assembly 3 is restricted by the movable core 3c abutting against the lower surface of the fixed core 2b from below. The movable core 3c abuts against the fixed core 2b when the valve assembly 3 is in the valve open position. The through hole of the fixed core 2b also accommodates an inner collar 4 and a spring 5.

[0016] The non-magnetic cylindrical body 2c is a cylindrical member connected to the lower part of the fixed core 2b. The non-magnetic cylindrical body 2c is made of a non-magnetic material and is disposed between a coil 8b (described later) of the coil unit 8 and the movable core 3c.

[0017] The magnetic cylinder 2d is a cylindrical member located below the non-magnetic cylinder 2c, with its upper end connected to the lower end of the non-magnetic cylinder 2c. The magnetic cylinder 2d is made of a magnetic material and has the same diameter as the non-magnetic cylinder 2c. The interior of the magnetic cylinder 2d forms part of the fuel passage R, and houses the rod 3a and movable core 3c (described later) of the valve assembly 3.

[0018] The valve seat member 2e is formed in a cylindrical shape and is fitted onto the lower end of the magnetic cylinder 2d. The internal space of the valve seat member 2e forms the lower end of the fuel passage R. FIG. 2 is a schematic enlarged cross-sectional view including the valve seat member 2e and the nozzle plate 2f. As shown in this figure, an opening 2e1 for discharging fuel is provided at the center of the bottom of the valve seat member 2e. A lower end surface 2e2 (end surface) of the valve seat member 2e is an abutment surface with the nozzle plate 2f. The lower end surface 2e2 of the valve seat member 2e is also flat.

[0019] 3 is a top view of the nozzle plate 2f. That is, FIG. 3 is a view of the nozzle plate 2f as seen from the valve seat member 2e side. As shown in this figure, the nozzle plate 2f is a disk-shaped member in which a plurality of fuel injection holes 2f1 are formed. In this embodiment, the nozzle plate 2f is formed to have the same outer diameter as the valve seat member 2e.

[0020] The plurality of fuel injection holes 2f1 are arranged at equal intervals in an annular shape surrounding the center of the nozzle plate 2f. Each fuel injection hole 2f1 is tapered so that its diameter increases from the upper surface 2f2 to the lower surface 2f3 of the nozzle plate 2f. That is, each fuel injection hole 2f1 is tapered so that its diameter increases from the inner surface (upper surface 2f2) of the nozzle plate 2f facing the valve seat member 2e to the outer surface (lower surface 2f3) on the opposite side.

[0021] Each fuel injection hole 2f1 is formed so as to extend radially outward from the center of the nozzle plate 2f as it moves from the upper surface 2f2 to the lower surface 2f3 of the nozzle plate 2f. In other words, each fuel injection hole 2f1 is formed so that its central axis is inclined relative to the vertical direction.

[0022] 3, the nozzle plate 2f has an annular fuel injection hole forming region R1 including a plurality of fuel injection holes 2f1. The nozzle plate 2f also has a circular central region R2 surrounded by the fuel injection hole forming region R1. The nozzle plate 2f also has an annular outer region R3 located outside the fuel injection hole forming region R1.

[0023] In this embodiment, the upper surface 2f2 of the nozzle plate 2f in the central region R2 and the upper surface 2f2 of the nozzle plate 2f in the outer region R3 are flattened surfaces. The upper surface 2f2 of the nozzle plate 2f in the central region R2 and the upper surface 2f2 of the nozzle plate 2f in the outer region R3 are flattened to fit the lower end surface 2e2 of the valve seat member 2e. Specifically, the upper surface 2f2 of the nozzle plate 2f in the central region R2 and the upper surface 2f2 of the nozzle plate 2f in the outer region R3 are flattened to a degree that prevents the formation of a gap through which the fuel X can pass when the outer region R3 and the lower end surface 2e2 of the valve seat member 2e are in contact with each other.

[0024] In this embodiment, these corrected surfaces are formed by irradiating the upper surface 2f2 of the nozzle plate 2f with a laser beam and flattening it due to residual stress generated after the irradiation. As a result, laser irradiation marks are formed on the upper surface 2f2 of the nozzle plate 2f in the central region R2 and the upper surface 2f2 of the nozzle plate 2f in the outer region R3.

[0025] 2, an upper surface 2f2 of the nozzle plate 2f in the outer region R3 is an abutment surface that comes into contact with a lower surface 2f3 of the valve seat member 2e. The nozzle plate 2f is joined to the valve seat member 2e by an annular welded portion 2f4 provided in the outer region R3.

[0026] 1 , the valve assembly 3 is a member that is moved vertically inside the fuel passage R. The valve assembly 3 is movable between a valve-closed position where a valve element 3b (described later) closes an opening 2e1 of a valve seat member 2e, and a valve-open position where the valve element 3b is moved above the valve-closed position to open the opening 2e1. The valve assembly 3 includes a rod 3a, a valve element 3b, and a movable core 3c.

[0027] The rod 3a is a hollow rod member that is housed in the fuel passage R and extends linearly in the vertical direction. The interior of the rod 3a also forms part of the fuel passage R. A through-hole that penetrates the rod 3a in the radial direction when viewed from above is formed in the middle of the rod 3a. Fuel X flows from the inside to the outside of the rod 3a through this through-hole.

[0028] The valve element 3b is a spherical member fixed to the lower end of the rod 3a. The valve element 3b is welded to the lower end of the rod 3a. In the valve closed position, the valve element 3b abuts against a valve seat formed inside the valve seat member 2e, closing the opening 2e1. In the valve open position, the valve element 3b moves away from the valve seat of the valve seat member 2e, opening the opening 2e1. When the valve element 3b moves away from the valve seat, fuel X is supplied from the opening 2e1 to the nozzle plate 2f and injected to the outside from the fuel injection holes 2f1 of the nozzle plate 2f.

[0029] The movable core 3c is a cylindrical member that is moved within the fuel passage R when current is applied to the coil 8b. The movable core 3c is moved upward by a magnetic force generated by applying current to the coil 8b. The movable core 3c is disposed so as to straddle the interior of the non-magnetic cylindrical body 2c and the interior of the upper part of the magnetic cylindrical body 2d.

[0030] When the coil 8b is not energized, the movable core 3c is biased to a downward position by the spring 5. When the movable core 3c is biased to a downward position by the spring 5, the valve element 3b closes the opening 2e1. When the coil 8b is energized, the movable core 3c is biased to an upward position where it abuts against the lower end of the fixed core 2b by the magnetic force of the coil 8b. When the movable core 3c is biased to an upward position where it abuts against the lower end of the fixed core 2b, the valve element 3b opens the opening 2e1.

[0031] The inner collar 4 is a cylindrical member fitted inside the fixed core 2b. The inner collar 4 is disposed above the spring 5. The lower surface of the inner collar 4 is the contact surface with the spring 5. The inner collar 4 is press-fitted into the through-hole of the fixed core 2b, and the compression amount of the spring 5 can be adjusted.

[0032] The spring 5 is housed in a through hole in the fixed core 2b and is located between the inner collar 4 and the movable core 3c. The upper end of the spring 5 abuts against the inner collar 4 from below, and the lower end of the spring 5 abuts against the movable core 3c from above. The spring 5 urges the valve element 3b toward the valve-closed position.

[0033] The filter member 6 is disposed at the upper end of the fuel inlet tube 2a and is housed inside the fuel passage R. This filter member 6 is a member for removing foreign matter contained in the fuel X. The filter member 6 is press-fitted into the fuel inlet tube 2a via a filter collar.

[0034] The covering portion 7 is provided so as to surround the valve housing 2 and the coil unit 8 from the radial outside. The covering portion 7 is formed of an insulator and holds the wiring connected to the coil 8b. The covering portion 7 also has a connector 7b for connecting a terminal 7a, which is the end of the wiring connected to the coil 8b, to an external terminal.

[0035] The coil unit 8 includes a bobbin 8a, a coil 8b, and a coil housing 8c. The bobbin 8a is a member around which the coil 8b is wound and is disposed so as to surround the fixed core 2b from the radial outside. The coil 8b is wound around the bobbin 8a and is electrically connected to the terminal 7a. When current is applied from the outside, the coil 8b generates a magnetic force, which moves the movable core 3c upward. The coil housing 8c is a magnetic body disposed so as to surround the coil 8b from the radial outside.

[0036] In the fuel injection valve 1 of this embodiment, when the coil 8b is energized, the movable core 3c moves upward and abuts against the lower end of the fixed core 2b. As the movable core 3c rises, the valve assembly 3 moves to the valve open position. When the valve assembly 3 moves to the valve open position in this manner, the opening 2e1 of the valve seat member 2e is opened, and fuel X is injected from the fuel injection hole 2f1 of the nozzle plate 2f.

[0037] On the other hand, when the coil 8b is de-energized, the movable core 3c is moved downward by the biasing force of the spring 5. This moves the valve assembly 3 to the valve-closed position, and the opening 2e1 of the valve seat member 2e is closed, thereby stopping the injection of the fuel X.

[0038] Next, a method for manufacturing the fuel injection valve 1 of this embodiment will be described. In the following description, the method for manufacturing the fuel injection valve 1 will be described from forming the nozzle plate 2 f to joining the formed nozzle plate 2 f to the valve seat member 2 e.

[0039] 4 is a flowchart illustrating the steps of forming the nozzle plate 2 f and joining the formed nozzle plate 2 f to the valve seat member 2 e. As shown in Fig. 4, the manufacturing method of the fuel injection valve 1 of this embodiment includes a nozzle plate forming step S10 of forming the nozzle plate 2 f from a strip-shaped hoop material (plate 10 shown in Fig. 5) and a nozzle plate joining step S20 of joining the nozzle plate 2 f to the valve seat member 2 e.

[0040] As shown in FIG. 4, the nozzle plate forming process S10 includes a fuel injection hole forming process S11, a large burr removing process S12, a correction process S13, a small burr removing process S14, and a punching process S15.

[0041] The fuel injection hole forming step S11 is a step of forming the fuel injection holes 2f1 in the plate 10. For example, the fuel injection holes 2f1 are formed in the plate 10 by a punch press. At this time, distortion occurs in the plate 10 due to the pressure during the press working. The large burr removing step S12 is a step of removing large burrs that have formed in the fuel injection hole forming step S11. For example, in the large burr removing step S12, the burrs are removed using ultrasonic waves.

[0042] The straightening step S13 is a step of straightening the distortion of the plate 10 caused in the fuel injection hole forming step S11 so that the distortion is aligned with the lower end surface 2e2 of the valve seat member 2e. Fig. 5 is a schematic diagram for explaining the straightening step S13. In this straightening step S13, the surface of the plate 10 is straightened while avoiding the region where the fuel injection holes 2f1 are formed (i.e., the fuel injection hole forming region R1). That is, in the straightening step S13, the surface of the plate 10 is straightened in the central region R2 and the outer region R3.

[0043] Specifically, in the correction step S13, the laser beam L is irradiated only onto one surface 10a of the plate 10, which becomes the upper surface 2f2 of the nozzle plate 2f. As shown in Fig. 5, the laser beam L scans the one surface 10a of the plate 10 so as to avoid the fuel injection hole formation region R1. Here, the laser beam L is operated at a constant speed, and irradiation of the laser beam L is stopped when the laser beam L reaches the fuel injection hole formation region R1.

[0044] When the laser beam L is irradiated onto only one surface 10a of the plate 10, the irradiated portion melts, and the residual stress generated when the plate 10 is subsequently cooled flattens the plate 10. As a result, the surface shape of the plate 10 is corrected to be flat in the central region R2 and the outer region R3.

[0045] The minute burr removal step S14 is a step of removing small burrs that could not be removed in the large burr removal step S12. For example, the minute burr removal step S14 removes the burrs using a laser beam. The punching step S15 is a step of punching out the nozzle plate 2f from the plate 10 and removing it.

[0046] The nozzle plate bonding process S20 is a process of bonding the upper surface 2f2 of the nozzle plate 2f in the outer region R3, which is the surface corrected in the correction process S13, to the lower end surface 2e2 of the valve seat member 2e. Here, the nozzle plate 2f and the valve seat member 2e are bonded together by forming a weld 2f4 by welding using, for example, laser light.

[0047] The manufacturing method of the fuel injection valve 1 of this embodiment as described above includes a nozzle plate forming step S10 and a nozzle plate joining step S20. In the nozzle plate forming step S10, a nozzle plate 2f having a plurality of fuel injection holes 2f1 formed therein is formed. In the nozzle plate joining step S20, the nozzle plate 2f is joined to the lower end surface 2e2 of the valve seat member 2e. The nozzle plate forming step S10 also includes a fuel injection hole forming step S11 and a correction step S13. The fuel injection hole forming step S11 is a step of forming the fuel injection holes 2f1 in the plate 10. The correction step S13 is a step of correcting distortion of the plate 10 caused in the fuel injection hole forming step S11 so that the distortion conforms to the lower end surface 2e2 of the valve seat member 2e, avoiding the area where the fuel injection holes 2f1 are formed. In the nozzle plate joining step S20, the surface corrected in the correction step S13 is joined to the lower end surface 2e2 of the valve seat member 2e.

[0048] According to the manufacturing method of the fuel injection valve 1 of this embodiment, since the distortion of the nozzle plate 2 f is corrected, it is not necessary to hold the nozzle plate 2 f joined to the valve seat member 2 e with a holder. Therefore, according to the manufacturing method of the fuel injection valve 1 of this embodiment, a holder for suppressing distortion of the plate 10 having the fuel injection holes 2 f 1 is not required.

[0049] In the manufacturing method of the fuel injection valve 1 of this embodiment, the plate 10 has a fuel injection hole forming region R1, a central region R2, and an outer region R3. The fuel injection hole forming region R1 is an annular region in which the fuel injection holes 2f1 are formed. The central region R2 is a region surrounded by the fuel injection hole forming region R1. The outer region R3 is located outside the injection hole forming region. In a straightening step S13, the central region R2 and the outer region R3 are straightened so as to conform to the lower end surface 2e2 of the valve seat member 2e.

[0050] According to the manufacturing method of the fuel injection valve 1 of this embodiment, the central region R2 and the outer region R3, which are arranged radially on either side of the fuel injection hole formation region R1, are corrected, making it possible to make the entire nozzle plate 2f closer to a flat plate.

[0051] In the manufacturing method of the fuel injection valve 1 of this embodiment, the distortion of the plate 10 is corrected by irradiating the laser light L only onto one surface 10a of both surfaces of the plate 10 in the correcting step S13.

[0052] According to the manufacturing method of the fuel injection valve 1 of this embodiment, the nozzle plate 2 f can be corrected by the residual stress generated in the nozzle plate 2 f by irradiating it with the laser light L. Therefore, according to the manufacturing method of the fuel injection valve 1 of this embodiment, the nozzle plate 2 f can be corrected by a simple process.

[0053] In the manufacturing method of the fuel injection valve 1 of this embodiment, in the correction step S13, while the laser light L is scanned along one surface 10a of the plate 10, irradiation of the laser light L is stopped in the fuel injection hole forming region R1.

[0054] According to the manufacturing method of the fuel injection valve 1 of this embodiment, it is possible to selectively correct the central region R2 and the outer region R3 while scanning with the laser light L. That is, in the manufacturing method of the fuel injection valve 1 of this embodiment, by scanning with the laser light L, it is possible to easily irradiate the laser light L while avoiding the fuel injection hole formation region R1.

[0055] Furthermore, in the manufacturing method of the fuel injection valve 1 of this embodiment, in the fuel injection hole forming step S11, a tapered fuel injection hole 2f1 is formed whose diameter increases from the inner surface facing the valve seat member 2e of the plate 10 toward the outer surface on the opposite side.

[0056] According to the manufacturing method of the fuel injection valve 1 of this embodiment, a fuel injection hole 2f1 is formed whose flow path cross section widens in the injection direction of the fuel X. The fuel X injected from such a fuel injection hole 2f1 is atomized. Therefore, according to the manufacturing method of the fuel injection valve 1 of this embodiment, it is possible to manufacture a fuel injection valve 1 in which the injected fuel X is atomized.

[0057] In the manufacturing method of the fuel injection valve 1 of this embodiment, the outer region R3 is joined to the lower end surface 2e2 of the valve seat member 2e by welding in the nozzle plate joining step S20. According to this manufacturing method of the fuel injection valve 1 of this embodiment, it is possible to firmly fix the nozzle plate 2f to the valve seat member 2e.

[0058] The fuel injection valve 1 of this embodiment also includes a nozzle plate 2f and a valve seat member 2e. The nozzle plate 2f has a plurality of fuel injection holes 2f1 formed therein. The nozzle plate 2f is joined to a lower end surface 2e2 of the valve seat member 2e. The nozzle plate 2f also has a straightening surface (an upper surface 2f2 of the nozzle plate 2f located in the outer region R3) that is provided to avoid the area where the fuel injection holes 2f1 are formed. The straightening surface is a surface that is straightened to fit along the lower end surface 2e2 of the valve seat member 2e, and is joined to the lower end surface 2e2 of the valve seat member 2e.

[0059] According to the fuel injection valve 1 of this embodiment, since the distortion of the nozzle plate 2 f is corrected, it is not necessary to hold the nozzle plate 2 f joined to the valve seat member 2 e with a holder. Therefore, according to the fuel injection valve 1 of this embodiment, a holder for suppressing distortion of the plate 10 having the fuel injection holes 2 f 1 is not required.

[0060] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0061] For example, in the above embodiment, the configuration in which the laser light L is irradiated to both the central region R2 and the outer region R3 in the correction step S13 has been described. However, the present invention is not limited to this. For example, it is also possible to adopt a configuration in which the laser light L is irradiated only to the outer region R3.

[0062] In the above embodiment, the nozzle plate 2 f and the valve seat member 2 e are joined by welding. However, the present invention is not limited to this. For example, the nozzle plate 2 f and the valve seat member 2 e may be joined by other joining methods, such as by using an adhesive.

[0063] The above embodiment can also be described as follows, for example:

[0064] (Supplementary Note 1) A method for manufacturing a fuel injection valve, comprising: a nozzle plate forming step of forming a nozzle plate having a plurality of fuel injection holes formed therein; and a nozzle plate joining step of joining the nozzle plate to an end face of a valve seat member, wherein the nozzle plate forming step comprises: a fuel injection hole forming step of forming the fuel injection holes in a plate; and a correction step of correcting distortion of the plate caused in the fuel injection hole forming step so that the distortion conforms to the end face of the valve seat member, avoiding an area in which the fuel injection holes are formed; and wherein in the nozzle plate joining step, the surface corrected in the correction step is joined to the end face of the valve seat member.

[0065] (Supplementary Note 2) The method for manufacturing a fuel injection valve according to Supplementary Note 1, wherein the plate has an annular fuel injection hole formation region in which the fuel injection holes are formed, a central region surrounded by the fuel injection hole formation region, and an outer region located outside the fuel injection hole formation region, and in the straightening step, the central region and the outer region are straightened so as to fit along the end face of the valve seat member.

[0066] (Supplementary Note 3) The method for manufacturing a fuel injection valve according to Supplementary Note 2, wherein in the correcting step, the distortion of the plate is corrected by irradiating laser light onto only one of both surfaces of the plate.

[0067] (Appendix 4) The method for manufacturing a fuel injection valve according to appendix 3, wherein in the correction step, the laser light is scanned along one side surface of the plate, while the irradiation of the laser light is stopped in the fuel injection hole formation region.

[0068] (Appendix 5) The method for manufacturing a fuel injection valve according to any one of Appendices 2 to 4, wherein in the fuel injection hole forming step, the fuel injection hole is formed to have a tapered shape in which the diameter increases from an inner surface of the plate that is disposed facing the valve seat member toward an outer surface on the opposite side.

[0069] (Supplementary Note 6) The method for manufacturing a fuel injection valve according to any one of Supplementary Notes 2 to 5, wherein in the nozzle plate joining step, the outer region is joined to the end surface of the valve seat member by welding.

[0070] (Supplementary Note 7) A fuel injection valve comprising a nozzle plate having a plurality of fuel injection holes formed therein and a valve seat member having an end surface to which the nozzle plate is joined, wherein the nozzle plate has a straightening surface provided so as to avoid an area in which the fuel injection holes are formed, and the straightening surface is a surface straightened to fit along the end surface of the valve seat member and is joined to the end surface of the valve seat member.

[0071] REFERENCE SIGNS LIST 1 fuel injection valve 2 valve housing 2a fuel inlet tube 2b fixed core 2c non-magnetic cylinder 2d magnetic cylinder 2e valve seat member 2e1 opening 2e2 lower end surface 2f nozzle plate 2f1 fuel injection hole 2f2 upper surface 2f3 lower surface 2f4 welded portion 3 valve assembly 3a rod 3b valve body 3c movable core 4 inner collar 5 spring 6 filter member 7 covering portion 7a terminal 7b connector 8 coil unit 8a bobbin 8b coil 8c coil housing 10 plate 10a surface L laser light R fuel passage R1 fuel injection hole forming region R2 central region R3 outer region S10 nozzle plate forming process S11 fuel injection hole forming process S12 large burr removal process S13 Correction process S14 Micro-burr removal process S15 Process S20 Nozzle plate joining process X Fuel

Claims

1. A method for manufacturing a fuel injection valve, comprising: a nozzle plate forming step of forming a nozzle plate with a plurality of fuel injection holes perforated therein; and a nozzle plate joining step of joining the nozzle plate to an end face of a valve seat member, wherein the nozzle plate forming step comprises: a fuel injection hole forming step of forming the fuel injection holes in the plate; and a correction step of correcting distortion of the plate caused in the fuel injection hole forming step so that it conforms to the end face of the valve seat member, avoiding the area in which the fuel injection holes are formed; and wherein in the nozzle plate joining step, the surface corrected in the correction step is joined to the end face of the valve seat member.

2. A method for manufacturing a fuel injection valve as set forth in claim 1, characterized in that the plate has an annular fuel injection hole forming region in which the fuel injection holes are formed, a central region surrounded by the fuel injection hole forming region, and an outer region located outside the fuel injection hole forming region, and in the straightening step, the central region and the outer region are straightened so as to fit along the end face of the valve seat member.

3. The method for manufacturing a fuel injection valve according to claim 2, wherein in the correction step, the distortion of the plate is corrected by irradiating laser light onto only one of both surfaces of the plate.

4. A method for manufacturing a fuel injection valve according to claim 3, characterized in that in the correction step, the laser light is scanned along one side of the plate, while the irradiation of the laser light is stopped in the fuel injection hole formation region.

5. A method for manufacturing a fuel injection valve as described in any one of claims 2 to 4, characterized in that in the fuel injection hole forming step, the fuel injection hole is formed to have a tapered shape in which the diameter increases from the inner surface of the plate facing the valve seat member toward the outer surface on the opposite side.

6. The method for manufacturing a fuel injection valve according to any one of claims 2 to 4, characterized in that in the nozzle plate joining step, the outer region is joined to the end face of the valve seat member by welding.

7. A fuel injection valve comprising a nozzle plate having a plurality of fuel injection holes formed therein and a valve seat member having an end surface to which the nozzle plate is joined, wherein the nozzle plate has a straightening surface provided to avoid the area in which the fuel injection holes are formed, and the straightening surface is a surface straightened to fit along the end surface of the valve seat member and is joined to the end surface of the valve seat member.

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