JP2002276511A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress abrasion and deformation of a valve seat of a fuel injection valve. SOLUTION: This fuel injection valve comprises a valve element 26 capable of reciprocating in the axial direction, and a body valve 6 having a bottom wall part 65 having a tapered surface like a valve seat 60 for receiving the lower end of the valve element 26, a side wall part 66 stood axially upwardly from the outer peripheral edge of the bottom wall part 65, a slidably contacting part 67 that is provided above the side wall part 66, has an inner diameter not larger than the inner diameter of the side wall part 66, and slidably contacts with the outer peripheral surface of the valve element 26. The body valve 6 has a ring-like valve seat displacement groove 62 that is coaxial to the valve seat 60 and displaces the valve seat 60 downwardly when the valve element 26 sits on the valve seat 60.

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 more particularly, to a fuel injection valve for injecting fuel into a cylinder head, an intake manifold and the like of an automobile engine.

[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. FIG. 7 is an enlarged sectional view of the vicinity of the injection hole 101 of the conventional fuel injection valve 100. In the vicinity of the injection hole 101, a hollow cylindrical body valve 102 welded to the inner peripheral side of the lower end of the housing 109, a valve body 103 provided on the inner peripheral side of the housing 109 and the body valve 102, A bottomed cylindrical injection hole plate 104 welded to the lower end is provided. The body valve 102 includes a bottom wall portion 106, a side wall portion 107, and a sliding contact portion 108.
On the inner surface of the bottom wall portion 106, a valve seat 105 whose diameter is tapered downward is formed.

The upper end of the valve body 103 is welded to a movable core (not shown), so that the valve body 103 and the movable core can reciprocate in the axial direction. The two members are urged downward by a spring (not shown), that is, toward the valve seat 105.
A fixed core (not shown) is provided above the movable core, and a coil (not shown) is provided on the outer peripheral side of the fixed core.

When an electric signal is sent to the coil, a magnetic attraction force is generated between the fixed core and the movable core, and the valve body 103 is separated from the valve seat 105 and moves upward against the urging force of the spring. . Then, the fuel passes through the gap between the valve body 103 and the valve seat 105 and the injection hole 101, and the fuel is supplied to the intake manifold (not shown).
Is injected and supplied. On the other hand, when the electric signal is cut off, the valve body 103 is seated on the valve seat 105 by the urging force of the spring. Then, the injection hole 101 is closed and the supply of fuel is shut off.

[0005]

However, according to the conventional fuel injection valve 100, the valve seat 105 is worn and deformed by the impact force when the valve body 103 is seated on the valve seat 105.

That is, when the electric signal to the coil is cut off, the magnetic attraction between the fixed core and the movable core disappears. When the magnetic attraction force disappears, the valve body 103 is lowered by the urging force of the spring and collides with the valve seat 105. In the conventional fuel injection valve 100, the impact force due to the collision is transmitted to the valve seat 1
05 only absorbed. For this reason, the valve seat 105 was worn and deformed by the impact force.

When the valve seat 105 is worn or deformed, the following problems occur. That is, even when the valve 103 is seated on the valve seat 105 and the valve is closed, the worn or deformed portion of the valve seat 105 does not abut on the surface of the valve 103. For this reason, the valve seat 105
A gap is generated between the valve body 103 and the valve body 103. When a gap is formed between the valve seat 105 and the valve body 103, the gap and the injection hole 1
The fuel may leak into the combustion chamber of the engine via the valve 01 even when the valve is closed. This leaked fuel contributes to an increase in the content of CH compounds such as CH ₄ , so-called HC, in the exhaust gas.

The fuel injection valve of the present invention has been completed in view of the above problems. That is, an object of the present invention is to provide a fuel injection valve which can suppress deterioration of liquid tightness of a valve due to wear and deformation of a valve seat, that is, deterioration of valve tightness.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a fuel injection valve according to the present invention has a valve body capable of reciprocating in an axial direction and a bottom wall having a tapered surface-shaped valve seat on which a lower end of the valve body is seated. A side wall portion which is provided upright in the axial direction from an outer peripheral edge of the portion and the bottom wall portion, and a sliding contact provided above the side wall portion and having an inner peripheral diameter equal to or less than an inner peripheral diameter of the side wall portion, and an outer peripheral surface of the valve body slidingly contacting. And a body valve comprising: a ring-shaped valve seat that is coaxial with the valve seat and displaces the valve seat downward when the valve body is seated on the valve seat. It has a displacement groove.

That is, in the fuel injection valve of the present invention, a valve seat displacement groove for displacing the valve seat downward at the moment when the valve body is seated on the valve seat is provided in the body valve. As compared with a portion of the body valve having no valve seat displacement groove, a portion having the valve seat displacement groove is thinner by the depth of the valve seat displacement groove.
For this reason, when the valve element is seated on the valve seat and an impact force is applied, the portion having the valve seat displacement groove is elastically deformed preferentially. Due to this elastic deformation, the valve seat is displaced downward so as to escape from the valve body,
The impact force applied to the valve seat can be reduced. Further, wear and deformation of the valve seat can be suppressed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A valve seat displacement groove can be arranged on a bottom wall, a side wall, or a sliding contact portion of a body valve. For example, a ring-shaped groove may be formed on the inner peripheral surface of the side wall portion, and this groove may be used as a valve seat displacement groove.

Preferably, the valve seat displacement groove may be provided on the bottom wall. In this configuration, the valve seat and the valve seat displacement groove are arranged on the same bottom wall. In other words, the valve seat itself is thinned. For this reason, according to this configuration, when the valve body collides, the valve seat is easily displaced downward.

[0013] The valve seat displacement groove in this configuration may be provided on the inner surface side or the outer surface side of the bottom wall portion. When it is provided on the inner surface side, for example, a valve seat displacement groove may be provided coaxially on the outer peripheral side of the tapered valve seat. Also, when installing on the outer surface side,
For example, a valve seat displacement groove may be provided coaxially on the back surface of the valve seat.

[0014] Preferably, the valve seat displacement groove may be provided in a portion of the side wall portion adjacent to the bottom wall portion. In this configuration, a valve seat displacement groove is provided in a portion of the side wall portion adjacent to the bottom wall portion. Since the valve seat is disposed on the bottom wall, the thickness, shape, and the like are limited. On the other hand, the conditions such as the thickness and the shape of the side wall are relatively moderate. Therefore, the degree of freedom with respect to the width and the depth of the valve seat displacement groove is large. Note that the valve seat displacement groove in this configuration may be provided on the inner surface side or on the outer surface side, similarly to the case where the valve seat displacement groove is provided on the bottom wall portion.

Particularly, it is preferable to provide a valve seat displacement groove from the inner peripheral surface side in a portion of the side wall portion adjacent to the bottom wall portion. When an impact force is applied to the valve seat, a bending moment is generated to move the valve seat downward. The center of the bending moment is a portion of the side wall portion adjacent to the bottom wall portion. The bending moment increases in proportion to the radius of the bottom wall. Also, the larger the bending moment, the larger the downward displacement of the valve seat. Also, the stress applied to the portion of the side wall adjacent to the bottom wall increases.

In this configuration, a valve seat displacement groove is provided in a portion adjacent to a bottom wall portion of a side wall portion which becomes a center of a bending moment. The bottom wall of this configuration is larger in diameter than the bottom wall of the conventional fuel injection valve by the depth of the valve seat displacement groove.
When the diameter of the bottom wall portion is increased, the bending moment increases accordingly, and the downward displacement amount of the valve seat also increases. Also, the stress applied to the portion of the side wall adjacent to the bottom wall increases. That is, in this configuration, the amount of downward displacement of the valve seat and the stress applied to the portion of the side wall portion adjacent to the bottom wall portion are increased to reduce the impact force applied to the valve seat.

The valve seat displacement grooves need not be single. That is, a plurality may be arranged. For example, at the bottom and top of the side wall,
Two may be provided. Further, a continuous single valve seat displacement groove may be provided in the side wall portion and the bottom wall portion.

The valve seat displacement groove may be formed simultaneously with the body valve when, for example, forging the body valve.
Alternatively, after the body valve is manufactured, the body valve may be ground to provide a valve seat displacement groove. Further, the body valve may be composed of a plurality of split bodies, a notch may be made in advance at a joint end of the split bodies, and the split bodies may be joined to form a valve seat displacement groove.

The groove width, groove depth, cross-sectional shape, etc. of the valve seat displacement groove are determined by the thickness of the body valve, the impact force when the valve body is seated on the valve seat, and other members mounted on the body valve. In consideration of the above, it may be appropriate.

The embodiment of the fuel injection valve of the present invention has been described above. However, embodiments are not particularly limited to the above embodiments. Various modifications and improvements that can be performed by those skilled in the art can also be implemented.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the fuel injection valve of the present invention will be specifically described with reference to embodiments.

<Embodiment 1> The fuel injection valve of this 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 outer shell of the fuel injection valve 1 of this embodiment includes a housing 2, a resin mold 3, a resin plate 4, a magnetic plate 5, a body valve 6, and an injection hole plate 7.

The housing 2 has a cylindrical or pipe shape extending in the axial direction. The upper end of the housing 2
A delivery pipe (not shown) for supplying fuel is inserted through an O-ring 28 at an inner peripheral side of a lower end. A fuel filter 21 is provided on the inner peripheral side of the upper end of the housing 2 to filter impurities in the fuel supplied from the delivery pipe. A hollow cylindrical fixed core 22 is press-fitted and welded below the inner peripheral side of the housing 2. Below the fixed core 22, a hollow cylindrical movable core 23 is installed so as to be able to reciprocate in the axial direction. Movable core 23
A cylindrical valve needle 26 with a bottom
(The inner peripheral surface is indicated by a dotted line in FIG. 1), and the upper end is inserted and welded. Therefore, the valve needle 26 can reciprocate in the axial direction together with the movable core 23. A fuel hole 27 is formed in the lower end portion of the side wall of the valve needle 26 so as to penetrate in the radial direction. A hollow cylindrical adjuster 24 is fixed above the inner peripheral side of the fixed core 22. A spring 25 is interposed between the lower end of the adjuster 24 and the upper end of the valve needle 26.

The upper end of a hollow cylindrical body valve 6 is press-fitted and welded to the inner peripheral side of the lower end of the housing 2.
The body valve 6 includes a bottom wall portion 65, a side wall portion 66, and a sliding contact portion 67 from the bottom in the axial direction. On the inner peripheral side of the body valve 6, the valve needle 2 is placed from above.
The lower end of 6 is inserted. The inner peripheral surface of the sliding portion 67 is in sliding contact with the outer peripheral surface of the valve needle 26. Also the bottom wall 6
5 is formed with a tapered valve seat 60 on which the lower end of the valve needle 26 is seated and separated. And this valve seat 60
A circular through hole 61 is formed through the bottom wall portion 65 on the inner peripheral side of.

A ring-shaped valve seat displacement groove 62 is formed in the side wall portion 66 adjacent to the bottom wall portion 65 from the inner peripheral side. Therefore, the diameter of the bottom wall portion 65 is increased by the depth of the valve seat displacement groove 62.

The lower end of the body valve 6 is press-fitted and welded to the inner peripheral side of the upper end of a bottomed cylindrical or cup-shaped injection hole plate 7. A plurality of injection holes 70 are formed through the bottom wall of the injection hole plate 7. These injection holes 70 are arranged in a circular shape. In addition, injection hole plate 7
Is in contact with the outer surface of the bottom wall portion 65 of the body valve 6. The through hole 61 penetrating the bottom wall 65 and the injection hole 70 are connected.

An O-ring 28 is fitted on the outer peripheral side of the upper end of the housing 2 to seal a connection portion with the delivery pipe. Also, above the O-ring 28, in order to prevent the O-ring 28 from shifting when the delivery pipe is connected,
A stopper ring 29 is inserted.

On the other hand, a ring-shaped magnetic plate 5 is mounted on the outer periphery of the lower end of the housing 2. The diameter of the magnetic plate 5 is reduced stepwise from top to bottom in the axial direction, and includes a large diameter portion 51 and a small diameter portion 50. Of these, the inner peripheral surface of the small diameter portion 50 disposed below is
And is fixed in contact with the outer peripheral surface of.

The inner diameter of the large diameter portion 51 is larger than the outer diameter of the housing 2. Therefore, a ring-shaped gap is formed between the inner peripheral surface of the large diameter portion 51 and the outer peripheral surface of the housing 2. The ring-shaped lower end of the resin mold 3 is inserted into this gap. The resin mold 3 includes a coil part 30 and a connector part 31. Of these, the ring-shaped coil portion 30 is inserted into the gap between the inner peripheral surface of the large diameter portion 51 and the outer peripheral surface of the housing 2. That is, the lower end surface and the outer peripheral surface of the coil portion 30 are covered by the large diameter portion 51 of the magnetic plate 5. Note that a ring-shaped coil 32 is wound and housed inside the coil unit 30 coaxially with the coil unit 30.

A magnetic ring 52 is provided on the upper end of the large diameter portion 51.
Is installed. The magnetic ring 52 has a ring shape with a cutout, that is, a C-shape. The lower end 53 of the magnetic ring 52 is expanded in a flange shape. The outer peripheral edge of the flange-shaped lower end portion 53 is inserted and fixed to the inner peripheral side of the upper end of the large diameter portion 51 of the magnetic plate 5. Further, the lower end surface of the lower end portion 53 is in contact with the upper end surface of the coil portion 30. That is, the upper end surface of the coil portion 30 is covered by the lower end portion 53 of the magnetic ring 52.

The connector section 31 includes an extension section 33 and a branch section 3.
4 The extension portion 33 is formed to extend upward from the coil portion 30 along the outer peripheral surface of the housing 2. The portion of the extension 33 close to the coil 30 is disposed within a notch of the C-shaped magnetic ring 52. The branch portion 34 is formed so as to protrude and branch diagonally upward in the radial direction from the extension portion 33. This branch 34
A concave portion 35 is formed at the upper end of the. A terminal 36 for sending an electric signal from an electronic control unit (not shown) to the coil 32 is provided on the bottom surface of the concave portion 35.

Both side surfaces of the extension portion 33 are sandwiched and fixed in the circumferential direction by the end surfaces of the pair of semicircular resin plates 4. The diameter of the resin plate 4 is increased stepwise from top to bottom in the axial direction.
1 and a large diameter portion 42. The inner peripheral surface of the small diameter portion 40 is in contact with the outer peripheral surface of the housing 2. Since the inner diameter of the middle diameter portion 41 is larger than the outer diameter of the housing 2,
There is a ring-shaped gap between the inner peripheral surface of the housing 2 and the outer peripheral surface of the housing 2. The magnetic ring 52 described above is arranged in this gap. There is also a ring-shaped gap between the inner peripheral surface of the large diameter portion 42 and the outer peripheral surface of the housing 2. In the gap, the coil portion 30 and the magnetic plate 5
Is disposed. The lower end of the large diameter portion 42 of the resin plate 4 is slightly reduced in diameter.
Is an enlarged diameter portion 5 on the outer peripheral surface of the large diameter portion 51 of the magnetic plate 5.
By engaging with 7, the vertical movement of the resin plate 4 is locked.

Next, a method of assembling the fuel injection valve 1 of the present embodiment will be described. First, a method of assembling members arranged on the inner peripheral side of the housing 2 will be described. First, the fuel filter 21 is inserted above the inner peripheral side of the housing 2 and welded. Next, the fixed core 22 is press-fitted and welded below the inner peripheral side of the housing 2. An adjuster 24 is already fixed above the inner peripheral side of the fixed core 22. Next, a spring 25 is placed below the inner peripheral side of the fixed core 22.
Insert Then, the movable core 23 already integrated with the valve needle 26 is inserted below the fixed core 22. Thereafter, the upper end of the body valve 6 is press-fitted into the inner peripheral side of the lower end of the housing 2 and welded. Then, the lower end of the body valve 6 is inserted into the inner peripheral side of the upper end of the injection hole plate 7 and welded.

Next, a method of assembling members arranged on the outer peripheral side of the housing 2 will be described. First, the magnetic plate 5 is mounted and welded below the outer peripheral surface of the housing 2. Next, the resin mold 3 is mounted around the outer peripheral surface of the housing 2. At this time, the coil part 30 is arranged on the inner peripheral side of the large diameter part 51 of the magnetic plate 5. then,
The magnetic ring 52 is welded to the upper end of the large diameter portion 51 of the magnetic plate 5. At this time, in the notch of the magnetic ring 52,
The extension 33 of the resin mold 3 is arranged.
Thereafter, a pair of resin plates 4 are installed adjacent to the extension 33 of the resin mold 3 in the circumferential direction. Finally, the O-ring 28 and the stopper ring 29 are fitted above the resin plate 4.

Next, the operation of the fuel injection valve 1 of this embodiment will be described. The fuel supplied from the delivery pipe is
The fuel is filtered by the fuel filter 21, passes through the housing 2, the adjuster 24, the spring 25, and the inner circumference of the valve needle 26, and passes through the fuel hole 27 of the valve needle 26, and the outer circumference of the valve needle 26 and the inner circumference of the body valve 6. Flows into the gap with the surface.

At this time, the terminal 32 is connected to the coil 32
An electric signal for fuel injection control is transmitted to the engine. By this electric signal, the magnetic plate 5 → the magnetic ring 52 → the housing 2 → the fixed core 22 → the movable core 2 around the coil 32.
3 → a housing 2 → a magnetic circuit connected to the magnetic plate 5 again is formed. This magnetic circuit generates a magnetic attraction between the fixed core 22 and the movable core 23. And
The movable core 23 is attracted to the fixed core 22 by the magnetic attraction force against the urging force of the spring 25, and the valve needle 2
6 moves upward away from the valve seat 60. Thus, the fuel flows into the through-hole 61 and is injected from the injection hole 70 into an intake manifold (not shown).

On the other hand, when the electric signal from the terminal 36 to the coil 32 is cut off, the magnetic attraction between the fixed core 22 and the movable core 23 also disappears. Therefore, the spring 2
The urging force of 5 moves the valve needle 26 downward,
The collision with the valve seat 60 causes the through hole 61 to close. As a result, the fuel flowing into the injection hole 70 is cut off, and the injection of the fuel to the intake manifold is stopped.

FIG. 2 is an enlarged view of the vicinity of the injection hole of the fuel injection valve of this embodiment. As shown by a dotted line in FIG. 2, the valve seat displacement groove 62 in the fuel injection valve of the present embodiment
6 is formed in a portion adjacent to the bottom wall 65. When the valve needle 26 collides with the valve seat 60, the valve seat displacement groove 6
The valve seat 60 is displaced downward with the portion provided with 2 as a fulcrum. This displacement alleviates the impact force applied to the valve seat 60.

In the magnetic circuit, the housing 2
If the entirety of the valve needle has magnetism, the magnetic circuit is short-circuited in the housing 2, and no magnetic flux passes through the movable core 23 and the valve needle 26
May not be sucked. That is, the magnetic circuit may be formed as the magnetic plate 5 → the magnetic ring 52 → the housing 2 → the fixed core 22 → the housing 2 → the magnetic plate 5 again. Therefore, in order to prevent a short circuit of the magnetic circuit, the housing 2 of the fuel injection valve 1 of the present embodiment
Only the part around the contact surface of the movable core 23 (the part partitioned by the dotted line in FIG. 1) is demagnetized, and the other parts are magnetized. This housing 2 is made of C-Cr-Ni-Mn-Nb
-It is formed of a Fe-based composite magnetic material. And
First, the entire housing 2 is magnetized (made to be martensite) by performing a strain applying process under a predetermined temperature condition.
Next, only the intermediate portion of the housing 2 is heated and melted within a predetermined time to make it non-magnetic (austenite), thereby giving the housing 2 the above-mentioned magnetic characteristics.

Embodiment 2 The fuel injection valve of Embodiment 2 has a valve seat displacement groove provided on the bottom wall of the body valve.
Other configurations, assembling methods, and the like are the same as those of the fuel injection valve of the first embodiment.

FIG. 3 is an enlarged view of the vicinity of the injection hole of the fuel injection valve of this embodiment. Note that the same symbols are used for members corresponding to FIG. Valve seat displacement groove 6 of the fuel injection valve of the present embodiment
2 is formed on the bottom wall 65 of the body valve 6.
When the valve needle 26 collides with the valve seat 60, the valve seat 60
Is displaced downward. This displacement alleviates the impact force applied to the valve seat 60.

<Embodiment 3> The fuel injection valve of Embodiment 3 has an injection hole formed directly on the body valve. The fuel injection valve according to the present embodiment is installed in a cylinder head for a so-called direct injection engine that directly injects fuel into a combustion chamber.

First, the configuration of the fuel injection valve of the present embodiment will be described. FIG. 4 shows an axial sectional view of the fuel injection valve 1 of the present embodiment. The same symbols are used for members having the same functions as those in FIG. The outer shell of the fuel injection valve 1 of this embodiment includes a fuel junction 8, a housing 2, a resin mold 3, a magnetic plate 5, and a valve holder 9.

The upper end of the fuel junction 8 is inserted through an O-ring 28 on the inner peripheral side of the lower end of a delivery pipe (not shown) for supplying fuel. The fuel junction 8 has a hollow cylindrical shape. A fuel filter 21 is provided above the inner peripheral side of the fuel junction 8.
On the other hand, above the outer peripheral surface of the fuel junction 8, an O-ring 28 made of resin for sealing a connection portion with the delivery pipe is fitted. A stopper ring 29 is fitted above the O-ring 28.

The lower end of the fuel junction 8 is inserted and welded to the inner peripheral side of the pipe-shaped housing 2. A hollow cylindrical fixed core 2 is provided on the inner peripheral side of the housing 2.
2 are press-fitted and welded. Below the fixed core 22, a hollow cylindrical movable core 23 is installed so as to be able to reciprocate in the axial direction. In addition, above the inner peripheral side of the fixed core 22,
A hollow cylindrical adjuster 24 is inserted and installed. A spring 25 is interposed between the adjuster 24 and the upper end on the inner peripheral side of the movable core 23.

A resin mold 3 is provided on the outer peripheral side of the housing 2.
Is installed. The resin mold 3 includes a coil part 30 and a connector part 31. The coil part 30 has a ring shape. A ring-shaped coil 32 covered with resin is housed inside the coil unit 30. On the outer peripheral surface of the coil part 30, a convex part 37 extending in the axial direction is provided upright. The connector portion 31 is formed to protrude radially outward from the upper end of the convex portion 37. The connector unit 31 includes an electronic control unit (not shown) connected to the coil 32.
A terminal 36 for sending an electric signal from the terminal is provided.

On the outer periphery of the coil portion 30 of the resin mold 3, a pair of semi-circular magnetic plates 5 are provided so as to sandwich the convex portion 37. The upper end 55 of the magnetic plate 5 is welded to the outer peripheral side surface of the housing 2.
The lower end 56 of the magnetic plate 5 is welded to the upper end 90 of the valve holder 9 described later. Magnetic plate 5
The inner peripheral wall 54 has a shape in which an upper end portion and a lower end portion in the axial direction are reduced in diameter and only the central portion is increased in diameter. Therefore, a ring-shaped space is formed on the inner peripheral side of the magnetic plate 5 by the inner peripheral wall 54. The coil portion 30 of the resin mold 3 is housed in the ring-shaped space.

The lower end of the housing 2 is inserted and welded to the inner peripheral side of the upper end of a hollow cylindrical valve holder 9.
At the center on the inner peripheral side of the valve holder 9, a valve needle 26 is installed extending in the axial direction. The upper end of the valve needle 26 is inserted and welded to the lower end on the inner peripheral side of the movable core 23. As described above, since the valve needle 26 is integrated with the movable core 23, the valve needle 26 can also reciprocate in the axial direction.

A cup-shaped body valve 6 is inserted and welded to the inner peripheral side of the lower end of the valve holder 9. The body valve 6 includes a bottom wall portion 65, a side wall portion 66, and a sliding contact portion 67 from the lower side in the axial direction. In the fuel injection valve 1 of the present embodiment, the inner peripheral diameters of the side wall portion 66 and the sliding contact portion 67 are equal. Therefore, the side wall portion 66 and the sliding contact portion 6
The outer peripheral surface of the valve needle 26 slides on the inner peripheral surface of the valve needle 7.
Further, a tapered valve seat 60 on which the conical lower end of the valve needle 26 is seated is formed on the inner surface of the bottom wall portion 65. A circular through hole 61 is formed on the inner peripheral side of the valve seat 60, and an injection hole 70 is formed at the center of the through hole 61.

A ring-shaped valve seat displacement groove 62 is formed in a portion of the side wall 66 adjacent to the bottom wall 65 from the outer peripheral side. For this reason, the portion of the side wall portion 66 adjacent to the bottom wall portion 65 corresponds to the depth of the valve seat displacement groove 62 by the body valve 6.
Is formed to be thinner than other portions.

Next, a method for assembling the fuel injection valve 1 of the present embodiment will be described. First, an O-ring 28 and a stopper ring 29 are fitted around the outer periphery of the fuel junction 8. Next, the fuel filter 21 is installed above the inside of the fuel junction 8.

Next, the upper end of the valve needle 26 is inserted into the inner peripheral side of the movable core 23 from below and welded, and the lower end of the valve needle 26 is inserted into the inner peripheral side of the body valve 6.
Then, these members are inserted into the inner peripheral side of the housing 2 from above. Then, the fixed core 22 is further press-fitted from above these members and welded. Therefore, the valve needle 26 and the body valve 6 protrude from below the housing 2. Thereafter, the spring 2 is moved to the inner peripheral side of the fixed core 22 until the lower end contacts the upper end of the inner peripheral side of the movable core 23.
Insert 5 Then, the adjuster 24 is inserted from above.

Then, the coil portion 30 of the resin mold 3 is mounted around the outer periphery of the housing 2. Then, the lower end of the fuel junction 8 is inserted into the inner peripheral side of the upper end of the housing 2 and welded. Further, the lower end of the housing 2 is inserted into the inner peripheral side of the upper end of the valve holder 9 and welded. Thereafter, the body valve 6 protruding from the lower end of the housing 2 is passed through the inner peripheral side of the valve holder 9 and welded to the inner peripheral side of the lower end of the valve holder 9.

Finally, at the end faces of the pair of magnetic plates 5,
Both sides of the convex portion 37 of the resin mold 3 are sandwiched. Then, the upper end portion 55 of the magnetic plate 5 is welded to the outer peripheral surface of the housing 2 and the lower end portion 56 is welded to the upper end portion 90 of the valve holder 9 while being held therebetween.

Next, the operation of the fuel injection valve 1 of this embodiment will be described. The fuel supplied from the delivery pipe is
The fuel passes through the fuel filter 21 from above the fuel junction 8, and passes through the fuel junction 8, the adjuster 24, the spring 25, and the inner peripheral side of the movable core 23. Then, the fuel flows into a gap between the valve needle 26 and the body valve 6 through a fuel groove (not shown) formed in the outer peripheral surface of the valve needle 26 in the axial direction.

At this time, the terminal 32 connects the coil 32
An electric signal for injection control is transmitted to the engine. Then, the electric signal causes the magnetic plate 5 around the coil 32 →
A magnetic circuit is formed which connects the housing 2 → the fixed core 22 → the movable core 23 → the housing 2 → the valve holder 9 → to the magnetic plate 5 again. This magnetic circuit generates a magnetic attraction between the fixed core 22 and the movable core 23. Then, the movable core 23 is moved to the spring 25 by the magnetic attraction.
Is attracted by the fixed core 22 against the urging force of the valve needle 26, and the valve needle 26 moves away from the valve seat 60 upward. The injection hole 70 is thus opened.

On the other hand, when the electric signal from the terminal 36 to the coil 32 is cut off, the magnetic attraction between the fixed core 22 and the movable core 23 also disappears. Therefore, the spring 2
The urging force of 5 moves the valve needle 26 downward,
It collides with the valve seat 60.

FIG. 5 is an enlarged view of the vicinity of the injection hole of the fuel injection valve of this embodiment. As shown by the dotted line in FIG. 5, the valve seat displacement groove 62 in the fuel injection valve of the present embodiment
6 is formed from the outer peripheral side in a portion adjacent to the bottom wall portion 65. When the valve needle 26 collides with the valve seat 60, the valve seat 60 is displaced downward with the portion having the valve seat displacement groove 62 as a fulcrum. This displacement alleviates the impact force applied to the valve seat 60.

If the entire housing 2 is magnetized, the magnetic circuit may be short-circuited and the valve needle 26 may not be sucked, as in the fuel injection valve shown in FIG. Therefore, the housing 2 of the fuel injection valve according to the present embodiment is also made non-magnetic only at a portion around the contact surface between the lower end surface of the fixed core 22 and the upper end surface of the movable core 23 (a portion separated by a dotted line in FIG. 4).

Fourth Embodiment A fuel injection valve according to a fourth embodiment has a valve seat displacement groove provided on the bottom wall of the body valve.
Other configurations, assembling methods, and the like are the same as those of the fuel injection valve of the third embodiment.

FIG. 6 is an enlarged view of the vicinity of the injection hole of the fuel injection valve of this embodiment. The same symbols are used for members corresponding to FIG. Valve seat displacement groove 6 of the fuel injection valve of the present embodiment
2 is formed on the bottom wall 65 of the body valve 6.
When the valve needle 26 collides with the valve seat 60, the valve seat 60
Is displaced downward. This displacement alleviates the impact force applied to the valve seat 60.

[0063]

According to the fuel injection valve of the present invention, the deterioration of the valve tightness due to the wear of the valve seat can be suppressed.

[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 an enlarged view of the vicinity of an injection hole of the fuel injection valve according to the first embodiment.

FIG. 3 is an enlarged view of the vicinity of an injection hole of a fuel injection valve according to a second embodiment.

FIG. 4 is an axial sectional view of a fuel injection valve according to a third embodiment.

FIG. 5 is an enlarged view of the vicinity of an injection hole of a fuel injection valve according to a third embodiment.

FIG. 6 is an enlarged view of the vicinity of an injection hole of a fuel injection valve according to a fourth embodiment.

FIG. 7 is an enlarged view of the vicinity of an injection hole of a conventional fuel injection valve.

[Explanation of symbols]

1: fuel injection valve 2: housing 3: resin mold
4: resin plate 5: magnetic plate 6: body valve 7: injection hole plate 8: fuel junction 9: valve holder 21:
Fuel filter 22: Fixed core 23: Movable core 24: Adjuster
25: Spring 26: Valve needle 27: Fuel hole 28: O-ring 29: Stopper ring 30: Coil part 31: Connector part 32: Coil 33: Extension part 34: Branch part 35: Recess 36: Terminal 37: Convex part 40 : Small diameter portion 41: medium diameter portion 42: large diameter portion 43: reduced diameter portion 50: small diameter portion 51: large diameter portion 52: magnetic ring 53: lower end portion 5
4: inner peripheral wall 55: upper end portion 56: lower end portion 57: enlarged diameter portion 60:
Valve seat 61: Through hole 62: Valve seat displacement groove 65: Bottom wall 66: Side wall 6
7: sliding part 70: injection hole 90: upper end

Claims (3)

[Claims] 1. A valve body capable of reciprocating in an axial direction, a bottom wall having a tapered valve seat on which a lower end of the valve body is seated, and an erect axially rising from an outer peripheral edge of the bottom wall. And a body valve provided above the side wall portion and provided with a sliding contact portion having an inner peripheral diameter equal to or less than the inner peripheral diameter of the side wall portion and having an outer peripheral surface of the valve body in sliding contact therewith. In the above, the body valve has a ring-shaped valve seat displacement groove which is coaxial with the valve seat and displaces the valve seat downward when the valve body is seated on the valve seat. Fuel injection valve. 2. The fuel injection valve according to claim 1, wherein the valve seat displacement groove is provided in a portion of the side wall portion adjacent to the bottom wall portion. 3. The fuel injection valve according to claim 1, wherein the valve seat displacement groove is provided in the bottom wall portion.