JP2002357173A - Fuel injection valve manufacturing method and fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in a conventional fuel injection valve manufacturing method wherein the welding strength between a movable core and a valve needle is high and a fuel injection valve with small strain and residual stress is difficult to be manufactured quickly. SOLUTION: This injection fuel valve comprises a movable core 40 having a lower opening 42, and a valve needle 41 having an insertion end 43 inserted and joined in the lower opening 42. The fuel injection valve manufacturing method comprises an abutting portion forming process forming an abutting portion 90 by inserting the insertion end 43 of the valve needle 41 in the lower opening 42 of the movable core 40 and making an inner peripheral surface of the lower opening 42 and an outer peripheral surface of the insertion end 43 abut on each other; and a welding strip forming process forming welding strips 48 extending in a circumferential direction in plural lines in a vertical direction by welding the abutting portion 90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve and a method for manufacturing the same, and more particularly, to a fuel injection valve for injecting fuel into an intake manifold or a cylinder head of an automobile engine and a method for manufacturing the same.

[0002]

2. Description of the Related Art A fuel injection valve is a device that injects and supplies fuel such as gasoline or light oil to a cylinder head or the like of an engine. This fuel injection valve has a coil, a fixed core, a movable member, and a valve seat. The movable member includes a movable core and a valve needle. When an electric signal is sent to the coil, a magnetic attractive force is generated between the fixed core and the movable core. In the fuel injection valve, the movable member is reciprocated by the magnetic attraction force. In conjunction with the reciprocating movement, the valve needle separates and seats with respect to the valve seat to inject and seal fuel.

Here, in order to secure magnetic attraction, the movable core is preferably formed of a material having excellent magnetic properties. On the other hand, since the valve needle repeatedly separates and separates from the valve seat, it is preferable to form the valve needle from a material having excellent sliding characteristics.
For this reason, when manufacturing a fuel injection valve, the movable core and the valve needle are often manufactured as separate bodies and then welded in many cases.

[0004]

As described above, the movable member repeatedly reciprocates in the fuel injection valve. Therefore, the welding strength between the movable core and the valve needle is preferably higher. Then, in order to increase the welding strength, it is only necessary to input thermal energy to a wide range at the time of welding to increase the area of the welded portion.

However, when thermal energy is applied to a wide range at a time, a large amount of distortion or residual stress may be generated in a welded portion. On the other hand, it is necessary for the movable member to secure the fuel sealing property when sitting on the valve seat. Further, it is necessary to maintain good slidability with other members. Therefore, it is necessary to minimize the distortion and residual stress generated at the weld between the movable core and the valve needle. For this reason, it is difficult to adopt a method in which thermal energy is applied to a wide range at once to increase the welding strength.

The fuel injection valve and the method of manufacturing the same according to the present invention have been completed in view of the above-mentioned problems. That is, an object of the present invention is to provide a fuel injection valve having a movable member having as small a distortion and residual stress as possible and having a high welding strength, and an appropriate and quick manufacturing method thereof.

[0007]

(1) In order to solve the above-mentioned problems, a method for manufacturing a fuel injection valve according to the present invention comprises a movable core having a lower opening and a valve needle having an insertion end inserted and joined to the lower opening. Forming a contact portion by inserting the insertion end of the valve needle into the lower opening of the movable core, and bringing the inner peripheral surface of the lower end opening into contact with the outer peripheral surface of the insertion end. And a welding band forming step of forming a plurality of rows of welding bands extending in the circumferential direction in the vertical direction by welding the contact portions.

That is, the method for manufacturing a fuel injection valve according to the present invention comprises a contact portion forming step and a welding band forming step. In the welding body forming step, a plurality of rows of circumferentially extending welding bands are formed in the vertical direction.

[0009] In the manufacturing method of the present invention, the area of one line of the welding band is small. The welding zone is formed by intensively applying heat energy to the width of the welding zone during welding. Therefore, generation of distortion and residual stress due to welding can be suppressed.

Further, in the manufacturing method of the present invention, the welding bands are arranged in a plurality of rows. For this reason, a large welding area can be ensured even if the area of one line of the welding band is small. Thereby, the welding strength between the movable core and the valve needle can be improved.

Here, the width, the number of rows, and the interval of the welding band may be set to appropriate values within a range in which generation of distortion and residual stress can be suppressed and a desired welding strength can be secured. Further, the welding zones may be formed one by one. Also, a plurality of welding zones may be formed simultaneously. For welding, for example, laser, electron beam, T
It can be performed using an IG arc, a plasma arc, or the like.

[0012] It is particularly preferable that the welding band forming step is performed by arranging a plurality of laser emitters with a predetermined height difference outside the outer peripheral surface of the movable core having the abutting portion on the inner peripheral side. And a step of irradiating the laser beam from the laser emitter and rotating the movable core once in the circumferential direction to simultaneously form a plurality of rows of weld bands extending in the circumferential direction in the vertical direction. Good.

In other words, the manufacturing method of this configuration uses a laser for welding. The welding band forming step in the manufacturing method of the present configuration includes a laser ejector arranging step and a welding band attaching step. The manufacturing method of this configuration is to form a plurality of welding zones at the same time by arranging a plurality of laser injectors having different altitudes around the contact portion and rotating the contact portion while emitting a laser beam. It is characterized by.

When forming a plurality of welding zones at the same time, it is necessary to consider the influence of the welding heat of the adjacent welding zones. That is, the smaller the heat transfer from the adjacent welding zone, the better.
In this regard, if a laser is used for welding, it is possible to relatively easily concentrate heat energy on a narrow portion.

Therefore, according to the manufacturing method of this configuration, a plurality of welding zones can be simultaneously formed without being affected by the welding heat of the adjacent welding zones. Therefore, distortion and residual stress generated in the weld zone can be suppressed.

In the manufacturing method of the present invention, a plurality of welding zones are formed at one time. For this reason, compared with the case where a plurality of welding zones are formed one by one, the formation of the welding zones can be performed quickly, and the workability is excellent.

The size of the spot differs depending on the type of laser. Therefore, a carbon dioxide gas laser, a YAG laser, an excimer laser, or the like may be appropriately selected and used according to the width, the interval, the number of rows, or the like of the welding band.

(2) In order to solve the above-mentioned problem, the fuel injection valve of the present invention has a contact portion between a movable core having a lower opening and an inner peripheral surface of the lower opening coaxially inserted into the lower opening. A movable member comprising: an insertion end having an arcuate outer circumferential surface forming a diagonally spaced apart diagonal position; and a valve needle having a shoulder portion arranged below the insertion end. A housing pipe having a guide surface on the inner periphery of which the outer peripheral surface of the movable core slides and a stopper ring against which the shoulder of the valve needle collides from below, and a valve needle fixed to the lower end of the housing pipe And a valve body having a valve seat whose lower end collides from above, wherein the vertical axis of the stopper ring and the vertical axis of the valve seat are reduced when the valve needle collides. In order to reduce the shear stress generated in the abutting portion due to one of them being inclined with respect to the vertical axis of the movable member, the abutting portion has a plurality of circumferentially extending welding bands in a vertical direction. .

That is, the fuel injection valve of this configuration is characterized by having a plurality of vertically extending welding bands extending in the circumferential direction at the contact portion between the movable core and the valve needle. As described above, the movable member reciprocates vertically. The bottom dead center of the movable member in this reciprocation is the position where the lower end of the valve needle collides with the valve seat. On the other hand, the top dead center is a position where the upper end surface of the shoulder portion of the valve needle collides with the lower end surface of the stopper ring of the housing pipe.

Here, depending on the mounting accuracy of the member or the dimensional accuracy of the member itself, the vertical axis of the movable member is
At least one of the vertical axis of the stopper ring and the vertical axis of the valve seat may be inclined.

A certain clearance is secured between the outer peripheral surface of the movable core and the guide surface of the housing pipe. Therefore, the movable member slightly swings in the axial direction while moving in the axial direction. This swinging may cause the valve needle to collide with the housing pipe tilting against the stopper ring and the valve seat.

In these cases, the collision may cause a shearing stress perpendicular to the vertical axis direction at the contact portion of the movable member.

According to the fuel injection valve of this configuration, a plurality of rows of welding bands extending in the circumferential direction are formed in the contact portion in the vertical direction. Therefore, the welding area is large. Therefore, the unit area (m
² ) The shear stress (P), which is the shear force (N) applied around
a) can be reduced.

Preferably, the insertion end of the valve needle is
It is preferable that a concave groove be provided between the arc-shaped outer peripheral surfaces so as to be depressed in a diameter-reducing direction rather than a straight line connecting the arc ends of the arc-shaped outer peripheral surface. In order to increase the welding strength between the movable core and the valve needle, the welding area may be increased. In order to increase the welding area, the length of the welding band may be increased. In other words, the arc length of the arc-shaped outer peripheral surface of the insertion end may be increased.
However, a fuel passage through which fuel flows is secured between the arc-shaped outer peripheral surfaces. Specifically, the fuel passage is formed such that both ends in the radial direction of the insertion end are cut off. Therefore, if the arc length of the arc-shaped outer peripheral surface is increased,
The cross-sectional area of the fuel passage is reduced accordingly. For this reason, the vapor generated in the fuel at high temperature passes through the fuel passage,
It becomes difficult to fall from the downstream side to the upstream side. When the vapor hardly comes off, the fuel injection amount becomes unstable.

Here, in order to increase the welding strength between the movable core and the valve needle while securing the passage cross-sectional area of the fuel passage, it is sufficient to increase the heat energy input during welding. However, when a large amount of thermal energy is input, a large amount of distortion or residual stress may be generated in the welding zone. That is, the quality of the weld zone may be deteriorated.

Therefore, in this configuration, a concave groove is formed between the arc-shaped outer peripheral surfaces. The concave groove is not formed in a cut-off shape as described above, but is formed so as to be depressed in the diameter reducing direction. For this reason, according to this configuration, the arc length of the arc-shaped outer peripheral surface can be increased, and a desired passage cross-sectional area can be ensured. That is, both high welding strength and a wide passage cross-sectional area can be achieved.

Here, the shape of the concave groove is not particularly limited.
It is sufficient that the recessed groove has a portion that is depressed in a direction smaller in diameter than a straight line connecting the arc ends of the arc-shaped outer peripheral surface. Therefore, the shape of the concave groove can be, for example, a U shape, a U shape, a V shape, a trapezoidal shape, or the like.

Preferably, the fuel injection valve is formed in a circular shape which forms a contact portion over the entire circumference between a movable core having a lower opening and an inner peripheral surface of the lower opening which is coaxially inserted into the lower opening. The valve needle includes an insertion end having an outer peripheral surface, a through hole that penetrates in the axial direction on the inner peripheral side of the circular outer peripheral surface, and a shoulder portion that is mounted below the insertion end. A movable member, a housing pipe having a movable surface into which the movable member is inserted so as to be able to reciprocate in the vertical direction, a guide surface on which the outer peripheral surface of the movable core slides on the inner peripheral side, and a stopper ring against which the shoulder of the valve needle collides from below; A valve body fixed to the lower end of the housing pipe and having a valve seat against which the lower end of the valve needle collides from above, the fuel injection valve comprising: In order to reduce the shear stress generated at the contact portion due to at least one of the vertical axis of the valve seat being inclined with respect to the vertical axis of the movable member, the contact portion is formed by extending a welding band extending over the entire circumference in the vertical direction. It is better to have a configuration characterized by having a plurality of columns.

The insertion end of the valve needle of the fuel injection valve of this configuration has a circular outer peripheral surface and a through hole. The circular outer surface is
It is in full contact with the inner peripheral surface of the lower opening of the movable core. For this reason, a contact portion is formed over the entire circumference between the circular outer peripheral surface and the inner peripheral surface of the lower opening. The through hole is formed on the inner peripheral side of the circular outer peripheral surface. The through hole secures the fuel passage.

According to the fuel injection valve of this configuration, the welding zone is arranged all around. For this reason, welding strength becomes higher. In addition, it is possible to suppress the deviation of the welding strength in the circumferential direction. The fuel passage is secured by a through hole. For this reason, a desired passage cross-sectional area can be secured. That is, according to the fuel injection valve of this configuration, it is possible to achieve both higher and uniform welding strength and a wider passage cross-sectional area.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (1) First, the fuel injection valve of the present embodiment will be described. The fuel injection valve according to the present embodiment is installed in an intake manifold of an automobile engine.

First, the configuration of the fuel injection valve of the present embodiment will be described. FIG. 1 shows an axial sectional view of the fuel injection valve 1 of the present embodiment. The fuel injection valve 1 of the present embodiment mainly includes a housing pipe 2, a resin mold 3, a valve body 6, and an injection hole plate 7.

The housing pipe 2 has a cylindrical shape extending in the axial direction, that is, a pipe shape. The housing pipe 2 includes a fixed core portion 20, a non-magnetic portion 21, and a magnetic portion 22. These three parts are arranged in the above order from above in the axial direction. The inner diameters of the non-magnetic portion 21 and the magnetic portion 22 are smaller than the inner diameter of the fixed core portion 20. Therefore, a step 23 is formed at the interface between the fixed core section 20 and the non-magnetic section 21. A stopper ring 28 having a fuel hole 280 penetrating in the up-down direction is provided on the lower inner peripheral side of the magnetic portion 22.

The upper end of the fixed core section 20 is inserted through the O-ring 24 into the inner periphery of the lower end of a delivery pipe (not shown) for supplying fuel. Further, a fuel filter 25 is provided on the inner peripheral side of the upper end of the fixed core portion 20 to filter impurities in the fuel supplied from the delivery pipe.
Further, an adjusting pipe 26 is press-fitted and caulked and fixed to the center inner peripheral side of the fixed core portion 20.

Below the fixed core section 20, a non-magnetic section 21 is disposed. And the step 23 at the interface between these two members
A movable member 4 is installed below the space so that it can reciprocate in the axial direction. The movable member 4 includes a movable core 40 and a valve needle 41. The valve needle 41 includes an insertion end 43, a rod part 44, a shoulder part 45, and a valve part 46.

The movable core 40 has a hollow cylindrical shape.
It is in sliding contact with a guide surface 29 on the inner peripheral surface of the housing pipe 2. A step is formed in the upper opening of the movable core 40. The lower end of the spring 27 is in elastic contact with this step. The upper end of the spring 27 is in elastic contact with the lower end of the adjusting pipe 26. That is, the spring 27 is interposed between the adjusting pipe 26 and the movable core 40. The spring 27 urges the movable core 40 downward.

On the other hand, the insertion end 43 of the valve needle 41 is inserted into the lower opening 42 of the movable core 40 and welded. FIG. 2 shows a radial sectional view of the lower opening 42 in a state where the insertion end 43 is welded. Lower opening 4 as shown
2 has a circular cross section. On the other hand, the cross section of the insertion end 43 has a circular shape in which both ends in the radial direction are cut off.
That is, the insertion end 43 has an arc-shaped outer peripheral surface 47 (shown by a dotted line in the figure) arranged diagonally in the long side direction. The arc-shaped outer peripheral surface 47 and the inner peripheral surface of the lower opening are brought into contact with each other and welded, so that welding bands 48 (shown by hatching in the figure) extending in the circumferential direction are formed in two rows in the vertical direction.
The portion that is not welded is hollow, and the fuel passage 49 is arranged.

As shown in FIG. 1 again, a rod portion 44 extends downward from the lower surface of the insertion end 43. A cylindrical shoulder portion 45 is mounted below the rod portion 44. Note that the stopper ring 28 is disposed above the shoulder portion 45. On the other hand, below the shoulder portion 45, a valve portion 46 whose lower end portion is tapered in diameter is provided.
Is arranged.

Around the shoulder part 45 and the valve part 46, a valve body 6 welded to the lower end of the magnetic part 22 of the housing pipe 2 is installed. The valve body 6 has a hollow cylindrical shape, and is tapered downward in a tapered shape. In this tapered portion, a ring-shaped valve seat 60 is provided.
Are formed.

At the lower end of the valve body 6, a cup-shaped injection hole plate 7 is welded. An injection hole 70 is formed on the bottom surface of the injection hole plate 7 and is connected to the lower opening of the valve body 6.

On the other hand, a resin mold 3 is mounted around the outer peripheral surface of the housing pipe 2. This resin mold 3
Are formed in a coaxial ring shape from the inner peripheral side, and the spool 30 and the coil portion 3
1 and a magnetic plate 32. In addition, resin mold 3
Is provided with a connector portion 33 protruding in the radial direction. A terminal 34 for sending an electric signal from an electronic control unit (not shown) to the coil unit 31 is attached to the connector unit 33.

Next, the operation of the fuel injection valve 1 of the present embodiment will be described. The fuel supplied from the delivery pipe is first filtered by the fuel filter 25, and then the fixed core part 20, the adjusting pipe 26 and the spring 2
7 on the inner circumference side. Then, it passes through a fuel passage 49 between the lower opening 42 and the insertion end 43. Then, it passes through the fuel hole 280 of the stopper ring 28 and flows into the gap between the outer peripheral surface of the valve portion 46 of the valve needle 41 and the inner peripheral surface of the valve body 6.

At this time, the terminal 34 connects the coil 3
1, an electric signal for fuel injection control is transmitted. By this electric signal, the magnetic plate 32
→ The fixed core part 20 → the movable core 40 → the magnetic part 22 → the magnetic circuit connected to the magnetic plate 32 again is formed. This magnetic circuit generates a magnetic attraction between the fixed core section 20 and the movable core 40. Then, due to the magnetic attraction force, the movable core 40 resists the urging force of the spring 27 and the fixed core 2
Aspirated to zero. Thus, the valve portion 4 of the valve needle 41
6 moves upward away from the valve seat 60. Thereafter, the valve needle 41 stops at a position where the shoulder portion 45 collides with the stopper ring 28.

FIG. 3 is a sectional view of the vicinity of the movable member 4 as viewed from the direction A in FIG. As shown in the figure, the upper end surface of the shoulder portion 45 of the valve needle 41 collides with the lower end surface of the stopper ring 28.

At this time, the vertical axis of the stopper ring 28 may be inclined with respect to the vertical axis of the movable member 4.
In other words, the lower end surface of the stopper ring 28 and the upper end surface of the shoulder portion 45 may not be parallel. In this case, the stopper ring 28 is fixed to the inner peripheral surface of the magnetic part 22, but the shoulder part is movable and not fixed. For this reason, the shoulder portion 45 is inclined along the lower end surface of the stopper ring 28. Accordingly, a bending moment is applied to the contact portion between the movable core 40 and the valve needle 41, and a shear stress is generated in the welding band 48 (shown by hatching in the drawing). FIG. 4 shows a schematic sectional view of FIG. A bending moment is generated in a direction indicated by a white arrow in the drawing. However, the fuel injection valve of the present embodiment has a large welding area because the welding bands 48 extending in the circumferential direction are vertically arranged in two rows. Therefore, the shear stress generated in the welding zone 48 is reduced, and the welding strength is improved.

(2) Next, a method for manufacturing the fuel injection valve of the present embodiment will be described. This manufacturing method includes a contact portion forming step, a laser emitting device arranging step, a welding band joining step, and a member assembling step.

First, in the contact portion forming step, the insertion end of the valve needle is inserted into the lower opening of the movable core, and the inner peripheral surface of the lower end opening is brought into contact with the outer peripheral surface of the insertion end to form a contact portion. That is, in this step, the insertion end is inserted into the lower end opening. Then, the inner peripheral surface of the lower end opening and the arc-shaped outer peripheral surface of the insertion end are brought into surface contact to form a contact portion. Since the arc-shaped outer peripheral surface is arranged at a diagonal position, the contact portion is also arranged at a diagonal position.

Next, in the laser emitting device arranging step, two laser emitting devices are arranged with a predetermined difference in altitude outside the outer peripheral surface of the movable core having the contact portion arranged on the inner peripheral side. FIG. 5 shows an outline of the laser welding apparatus 8. The laser welding device 8 mainly includes a pair of YAG laser transmitters 80 and a pair of laser
1 and a jig 87. Here, the laser emitting device 81 includes a mirror 82 and a focusing lens 83. The YAG laser transmitter 80 and the laser emitter 81 are connected by an optical fiber cable 84. A rotating table 86 is provided on the upper surface of the jig 87. The rotation of the table 86 is controlled by the NC device 85 connected to the jig 87.

In this step, first, the table 86 of the jig 87
In the contact portion forming step, the insertion end 4 of the valve needle 41
The movable core 40 into which 3 is inserted is arranged. In the present step, next, a pair of laser
1 is arranged. At this time, the laser emitting device 81 is
Is arranged on the outer peripheral side. Therefore, the laser emitting device 81 is also arranged at the diagonal position. Further, the pair of laser emitting devices 81 are arranged with a predetermined height difference.

Next, in the welding band attaching step, the laser emitting device 8 is used.
By emitting a laser beam from 1 and rotating the movable core 40 once in the circumferential direction, welding bands extending in the circumferential direction are simultaneously arranged in two rows in the vertical direction.

In this step, first, a laser beam is emitted from a laser emitting device. The laser beam generated and amplified by the YAG laser transmitter 80 is supplied to an optical fiber cable 84.
And enters the laser ejector 81. The laser beam is reflected by a mirror 82 at a predetermined angle in the laser emitting device 81. The reflected laser beam is focused by the focusing lens 83 and emitted toward the outer peripheral surface of the movable core 40.

The table 86 of the jig 87 is rotated by the NC unit 85 in synchronization with the emission of the laser beam. By this rotation, the movable core 4 on the table 86
0 also rotates in the circumferential direction. The rotation width at this time is made equal to the circumferential width of the contact portion 90 between the movable core 40 and the valve needle 41. FIG. 6 shows the state after the rotation. As shown in the figure, after rotation, the welding band 48
a (shown by knitting in the figure) is formed. The contact part 9
A welding band 48b (shown by a dotted line in the figure) is formed at the lower stage of 0b.

Then, the emission of the laser beam is stopped and the table 86 is rotated. And the contact part 9 on the left side in FIG.
When 0a reaches the laser beam emission position on the right side in FIG. 6, the rotation is stopped.

Finally, the laser beam is again emitted, and the table 86 of the jig 87 is rotated by the NC device 85 in synchronization with the emission of the laser beam. Due to this rotation, the movable core 40 on the table 86 also rotates in the circumferential direction. The rotation width at this time is determined by the contact portions 90a and 90a.
b. FIG. 7 shows the state after the rotation. As shown in the figure, after the rotation, the welding band 48c is placed below the already formed welding band 48a of the contact portion 90a.
(Shown by a dotted line in the figure) is formed. Also, the contact portion 90b
Above the already formed welding band 48b, the welding band 48d
(Shown by hatching in the figure).

Here, the previously formed welding bands 48a and 48b have already begun to cool naturally. Therefore, there is little possibility that distortion or residual stress is generated in the adjacent welding band 48c due to residual welding heat of the welding band 48a. Similarly, due to the residual welding heat of the welding band 48b, the adjacent welding band 48d
The possibility that distortion or residual stress is generated is small.

In this step, a total of four welding zones can be formed at one time while the movable core makes one round. Therefore, the movable core and the valve needle can be quickly welded.

Finally, in the member assembling step, the members of the fuel injection valve including the movable member obtained in the above steps are assembled to produce a fuel injection valve. In this step, first, the injection hole plate 7 shown in FIG. 1 is welded to the lower end of the valve body 6. Next, the adjusting pipe 26 is pressed into the inner peripheral surface of the housing pipe 2 and fixed by caulking. Then, a spring 27 is arranged below the adjusting pipe 26. Then, the movable member 4 is arranged below the spring 27. The stopper ring 28 is welded to the lower end of the housing pipe 2 above the shoulder 45 of the movable member 4. The stopper ring 28 has a notch formed from the center hole to the periphery. Using this notch, the stopper ring 28 is mounted on the lower end of the housing pipe 2 from the radial direction. Then, the valve body 6 is welded to the lower end of the stopper ring 28. Thereafter, the resin mold 3 is mounted on the outer peripheral surface of the housing pipe 2. Then, a fuel filter 2 is provided above the inner peripheral side of the housing pipe 2.
5 is attached. Further, an O-ring 24 is mounted above the outer peripheral side of the housing pipe 2.

<Second Embodiment> The difference between this embodiment and the first embodiment is that a concave groove is arranged between the arc-shaped outer peripheral surfaces of the insertion end. Therefore, only the differences will be described here.

FIG. 8 is a radial sectional view of the lower opening of the movable core of the fuel injection valve of this embodiment. Parts corresponding to those in FIG. 2 are indicated by the same symbols. As shown in the figure,
A concave portion 430 is formed between the arc-shaped outer peripheral surfaces 47 of the insertion end 43. The concave portion 430 has a U-shape that is depressed in the diameter-reducing direction from a straight line (indicated by a dashed line in the figure) connecting the arc ends of the arc-shaped outer peripheral surface 47.

Both ends of the U-shaped portion of the concave portion 430 are curved in a radially increasing direction in a quadratic curve. For this reason, the arc length of the arc-shaped outer peripheral surface 47 of the fuel injection valve of the present embodiment is relatively long. That is, the circumferential length of the welding band 48 is relatively long. Therefore, the welding strength of the fuel injection valve of the present embodiment is high. Further, the U-shaped bottom of the concave portion 430 is depressed in the diameter reducing direction. For this reason, the passage sectional area of the fuel passage 49 of the fuel injection valve of the present embodiment is substantially equal to the passage sectional area of the fuel passage of the first embodiment. That is, the fuel injection valve of the present embodiment achieves both high welding strength and a wide fuel passage.

<Third Embodiment> A difference between the present embodiment and the second embodiment is that a concave groove is formed in a U-shape. Therefore, only the differences will be described here.

FIG. 9 is a radial sectional view of the lower opening of the movable core of the fuel injection valve of this embodiment. Parts corresponding to those in FIG. 8 are indicated by the same symbols. As shown in the figure,
The concave portion 430 has a U-shape that is depressed in the diameter-reducing direction from a straight line (shown by a dashed line in the figure) connecting the arc ends of the arc-shaped outer peripheral surface 47. Like the fuel injection valve of the second embodiment, the fuel injection valve of the present embodiment has both high welding strength and a wide fuel passage.

<Fourth Embodiment> The difference between this embodiment and the second embodiment is that the concave groove is formed in a V-shape. Therefore, only the differences will be described here.

FIG. 10 is a radial sectional view of the lower opening of the movable core of the fuel injection valve of this embodiment. Parts corresponding to those in FIG. 8 are indicated by the same symbols. As shown in the figure, the concave portion 430 has a V-shape that is depressed in the diameter-reducing direction from a straight line (indicated by a dashed line in the figure) connecting the arc ends of the arc-shaped outer peripheral surface 47. Like the fuel injection valve of the second embodiment, the fuel injection valve of the present embodiment has both high welding strength and a wide fuel passage.

<Fifth Embodiment> The fifth embodiment is different from the second embodiment in that the concave groove is formed in a trapezoidal shape. Therefore, only the differences will be described here.

FIG. 11 is a radial sectional view of the lower opening of the movable core of the fuel injection valve of this embodiment. Parts corresponding to those in FIG. 8 are indicated by the same symbols. As shown in the figure, the concave portion 430 has a trapezoidal shape that is depressed in a diameter-reducing direction from a straight line (indicated by a dashed line in the figure) connecting the arc ends of the arc-shaped outer peripheral surface 47. Like the fuel injection valve of the second embodiment, the fuel injection valve of the present embodiment has both high welding strength and a wide fuel passage.

<Sixth Embodiment> The sixth embodiment is different from the first embodiment in that a circular outer peripheral surface is arranged at the insertion end instead of the arcuate outer peripheral surface. Another difference is that a through hole is arranged at the insertion end instead of the concave groove. Therefore, only the differences will be described here.

FIG. 12 is a radial sectional view of the lower opening of the movable core of the fuel injection valve of this embodiment. Parts corresponding to those in FIG. 2 are indicated by the same symbols. As shown in the figure, a circular outer peripheral surface 470 is arranged at the insertion end 43. The circular outer peripheral surface 470 is in contact with the inner peripheral surface of the lower opening 42 over the entire circumference. And, the welding zone 4
8 are formed. Further, an arc-shaped through hole 431 is formed on the inner peripheral side of the circular outer peripheral surface 470. Through hole 4
3 penetrates the upper and lower surfaces of the insertion end 43. Through hole 43
A fuel passage 49 is defined on the inner peripheral side of the fuel cell.

The welding zone 48 of the fuel injection valve of this embodiment is
It is formed over the entire circumference of the circular outer peripheral surface 470. Therefore, the welding strength of the fuel injection valve of the present embodiment is high. Also, the deviation of the welding strength in the circumferential direction is small. Further, a through hole 431 is arranged on the inner peripheral side of the circular outer peripheral surface 470. For this reason, the passage sectional area of the fuel passage 49 of the fuel injection valve of the present embodiment is substantially equal to the passage sectional area of the fuel passage of the first embodiment. That is, the fuel injection valve of the present embodiment has both high and uniform welding strength and a wide fuel passage.

[0070]

According to the fuel injection valve and the method of manufacturing the same according to the present invention, a fuel injection valve having a movable member having as small a distortion and residual stress as possible and having a high welding strength, and an appropriate and quick method for manufacturing the same are provided. be able to.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a fuel injection valve according to a first embodiment.

FIG. 2 is a radial cross-sectional view of a lower opening of a movable core of the fuel injection valve of the first embodiment.

FIG. 3 is a cross-sectional view of the vicinity of a movable member viewed from a direction A in FIG.

FIG. 4 is a schematic view of the vicinity of a movable member in FIG.

FIG. 5 is a schematic view of a laser welding apparatus used in the method for manufacturing a fuel injection valve according to the first embodiment.

FIG. 6 is a view showing a state after a movable core has rotated half a turn in a step of attaching a welding band in the method for manufacturing a fuel injection valve according to the first embodiment.

FIG. 7 is a view showing a state after one rotation of a movable core in a step of attaching a welding band in the method of manufacturing a fuel injection valve of the first embodiment.

FIG. 8 is a radial cross-sectional view of a lower opening of a movable core of a fuel injection valve according to a second embodiment.

FIG. 9 is a radial cross-sectional view of a lower opening of a movable core of a fuel injection valve according to a third embodiment.

FIG. 10 is a radial cross-sectional view of a lower opening of a movable core of a fuel injection valve according to a fourth embodiment.

FIG. 11 is a radial cross-sectional view of a lower opening of a movable core of a fuel injection valve according to a fifth embodiment.

FIG. 12 is a radial sectional view of a lower opening of a movable core of a fuel injection valve according to a sixth embodiment.

[Explanation of symbols]

1: fuel injection valve, 2: housing pipe, 3: resin mold, 4: movable member, 6: valve body, 7: injection hole plate, 8: laser welding device, 20: fixed core portion, 21: non-magnetic portion, 22: magnetic part, 23: step, 24: O-ring,
25: fuel filter, 26: adjusting pipe,
27: spring, 28: stopper ring, 29: guide surface, 30: spool, 31: coil, 32: magnetic plate, 33: connector, 34: terminal, 4
0: movable core, 41: valve needle, 42: downward opening, 43: insertion end, 44: rod portion, 45: shoulder portion, 46: valve portion, 47: arc-shaped outer peripheral surface, 48: welding band, 4
9: fuel passage, 60: valve seat, 70: injection hole, 80: YAG
Laser transmitter, 81: laser emitter, 82: mirror, 8
3: Focusing lens, 84: Optical fiber cable, 85:
NC device, 86: table, 87: jig, 90: contact portion, 280: fuel hole, 430: concave groove, 431: through hole, 470: circular outer peripheral surface.

Claims (5)

[Claims] 1. A method of manufacturing a fuel injection valve comprising: a movable core having a lower opening; and a valve needle having an insertion end inserted and joined to the lower opening. A contact portion forming step of inserting the insertion end of the valve needle, making an inner peripheral surface of the lower end opening and an outer peripheral surface of the insertion end to form a contact portion, and welding the corresponding contact portion to form a contact portion; Forming a plurality of rows of weld bands extending in the vertical direction in the vertical direction. 2. The laser beam emitting device according to claim 1, wherein the welding band forming step includes a step of arranging a plurality of laser emitting devices with a predetermined height difference outside an outer peripheral surface of the movable core having the contact portion disposed on an inner peripheral side. An arrangement step, and a welding band juxtaposition step of emitting a laser beam from the laser emitter and rotating the movable core once in the circumferential direction to simultaneously arrange a plurality of rows of welding zones extending in the circumferential direction in the vertical direction. A method for manufacturing a fuel injection valve according to claim 1. 3. A movable core having a lower opening, and an arcuate outer peripheral surface which is coaxially inserted into the lower opening and forms a contact portion between the movable core and an inner peripheral surface of the lower opening, is separated at a diagonal position. A movable member comprising a valve needle having an insertion end to be arranged and a shoulder portion circulated below the insertion end, and the movable member is inserted so as to be able to reciprocate up and down, and A housing pipe having a guide surface against which the outer peripheral surface of the movable core slides and a stopper ring against which the shoulder of the valve needle collides from below; a lower end of the valve needle fixed to the lower end of the housing pipe and colliding from above A valve body having a valve seat, wherein at least one of a vertical axis of the stopper ring and a vertical axis of the valve seat is vertically A fuel injection valve characterized in that the contact portion has a plurality of rows of circumferentially extending welding bands in the vertical direction in order to reduce shear stress generated at the contact portion due to inclination with respect to the axis. 4. The fuel injection valve according to claim 3, wherein the insertion end has a concave groove between the arc-shaped outer peripheral surfaces, the concave groove being depressed in a direction smaller in diameter than a straight line connecting the arc ends of the arc-shaped outer peripheral surface. 5. A movable core having a lower opening, a circular outer peripheral surface which is coaxially inserted into the lower opening and forms an abutting portion over the entire periphery with an inner peripheral surface of the lower opening, A through-hole penetrating in the axial direction on the inner peripheral side of the circular outer peripheral surface,
A movable member comprising: an insertion end having a valve needle; and a shoulder portion disposed below the insertion end. The movable member is inserted into the inner peripheral side so as to be vertically reciprocable. A housing pipe having a guide surface on which the outer peripheral surface of the movable core slides and a stopper ring against which the shoulder portion of the valve needle collides from below; And a valve body having a valve seat that moves when at least one of the vertical axis of the stopper ring and the vertical axis of the valve seat collides with the vertical axis of the movable member when the valve needle collides. In order to reduce the shear stress generated at the corresponding contact due to the inclination, the contact has a plurality of vertical rows of welding bands extending over the entire circumference. Fuel injection valve for.