JP2001323861A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately inject the predetermined quantity of the fuel from a fuel injection valve. SOLUTION: A valve element for opening and closing a fuel injection hole 3 is housed in a housing freely to be reciprocated. The fuel is injected from the fuel injection hole by reciprocating the valve element inside the housing. A one-way valve 22 is arranged in a space between the valve element and the housing. Flow of the fuel to be compressed when the valve element is driven so as to close the fuel injection hole is prevented by the one-way valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A fuel injection valve in which a valve body for opening and closing a fuel injection hole in an internal combustion engine is reciprocally housed in a housing is known. In the fuel injection valve, fuel can be injected from the fuel injection hole by reciprocating the valve body in the housing. By the way, in a fuel injection valve of the type described above, when the valve element is driven to close the fuel injection hole, the valve element collides with the valve seat of the housing, and a phenomenon called so-called bounce occurs. When this bounce occurs, the fuel injection hole is opened instantaneously, so that unnecessary fuel is injected from the fuel injection valve, and a predetermined amount of fuel cannot be accurately injected. In order to accurately inject a predetermined amount of fuel, there is a movement in the field of fuel injection valves to suppress the bounce.

A technique for suppressing bounce is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-210217. In the fuel injection valve disclosed in this publication, fuel in a space (hereinafter, referred to as a fuel compression space) between a wall surface of the valve body and a wall surface of the housing that approach each other when the valve body moves to close the fuel injection hole is removed. The valve is compressed, and the bounce of the valve body is suppressed by using the compression resistance. That is, when the valve body moves to close the fuel injection hole, the fuel in the fuel compression space is compressed by the moving valve body. The seating speed (hereinafter, valve closing speed)
Thus, the occurrence of bounce is suppressed.

[0004]

In the fuel injection valve disclosed in the above publication, the valve closing speed can be greatly reduced as the volume of the fuel compression space when the valve body fully closes the fuel injection hole is reduced. it can. In other words, the valve closing speed cannot be reduced to a desired level unless the volume of the fuel compression space is reduced to some extent. Therefore, the valve body and the housing must be manufactured so that the distance between the wall surface of the valve body and the wall surface of the housing that defines the fuel compression space when the valve body completely closes the fuel injection hole is extremely short. No.

However, when the distance between the wall surface of the valve body and the wall surface of the housing is extremely short, if there is a manufacturing error in the valve body or the housing, the wall surface of the valve body is required before the valve body completely closes the fuel injection hole. Collides with the wall surface of the housing, and as a result, the valve element cannot completely close the fuel injection hole. That is, the fuel injection valve described in the above publication cannot accurately inject a predetermined amount of fuel after all, even if the bounce is suppressed.

In view of the above problems, an object of the present invention is to accurately inject a predetermined amount of fuel from a fuel injection valve.

[0007]

According to a first aspect of the present invention, a valve element for opening and closing a fuel injection hole is reciprocally housed in a housing, and the valve element is housed in the housing. In a fuel injection valve in which fuel is injected from a fuel injection hole by reciprocating, a one-way valve is disposed in a space between a valve body and a housing, and the valve body is driven to close the fuel injection hole. The one-way valve prevents the fuel compressed when flowing from flowing. This one-way valve increases the compression resistance of the fuel.

In the second invention, in the first invention,
The one-way valve is arranged in a space between the wall surface of the housing and the wall surface of the housing extending along the reciprocating direction of the valve body in the space between the valve body and the housing. According to a third aspect, in the second aspect, a solenoid for propelling the valve body in a direction to close the fuel injection hole is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel injection valve according to the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows one embodiment of the fuel injection valve of the present invention. The illustrated fuel injection valve 1 is used, for example, to inject fuel into a combustion chamber of an internal combustion engine. The illustrated fuel injection valve 1 includes a fuel chamber 2 for temporarily storing fuel, a fuel injection hole 3 for injecting fuel into a combustion chamber (not shown) of the internal combustion engine, and a fuel injection hole 3. And a rod-shaped needle valve 4 for closing the valve. In the present embodiment, the number of fuel injection holes is one, but a plurality of fuel injection holes may be formed in the fuel injection valve as desired. An armature 5 is attached to an end of the needle valve 4 located on the opposite side of the fuel injection hole 3. The armature 5 has a substantially annular shape.

A solenoid coil (hereinafter referred to as a valve closing solenoid coil) 6 is disposed closer to the fuel injection hole 3 than the armature 5. The valve closing solenoid coil 6 has a substantially annular shape and surrounds the needle valve 4. When a voltage is applied, the valve closing solenoid coil 6 generates a magnetic field. This magnetic field provides a driving force to the needle valve 4 for driving the armature 5 toward the fuel injection hole 3, that is, in a direction to close the fuel injection hole 3. The needle valve 4 is urged by a coil spring 7 via an armature 5. The coil spring 7 provides an urging force to the needle valve 4 for urging the needle valve 4 toward the fuel injection hole 3, that is, in a direction to close the fuel injection hole 3.

On the other hand, a solenoid coil (hereinafter referred to as a valve opening solenoid coil) 8 is disposed on the fuel chamber 2 side of the armature 5 separately from the valve closing solenoid coil 6. The valve opening solenoid coil 8 has a substantially annular shape and surrounds the needle valve 4. The valve opening solenoid coil 8 generates a magnetic field when a voltage is applied in the same manner as the valve closing solenoid coil 6. This magnetic field is different from the valve closing solenoid coil 6 in the direction in which the armature 5 is separated from the fuel injection hole 3,
That is, a driving force for driving the needle valve 4 in a direction in which the fuel injection hole 3 is opened is provided to the needle valve 4.

In this embodiment, when the fuel injection hole 3 is to be opened, a voltage is applied only to the valve opening solenoid coil 8.
That is, no voltage is applied to the valve closing solenoid coil 6. Thus, the valve opening solenoid coil 8 drives the needle valve 4 in a direction to open the fuel injection hole 3 against the urging force of the coil spring 7. Thus, the fuel injection hole 3 is opened,
Fuel is injected from the fuel injection valve 1.

On the other hand, when the fuel injection hole 3 is to be closed, the voltage applied to the valve opening solenoid coil 8 is set to zero, and a voltage is applied to the valve closing solenoid coil 6. Thus, the valve closing solenoid coil 6 drives the needle valve 4 in the direction to close the fuel injection hole 3 with the help of the urging force of the coil spring 7. Thus, the fuel injection hole 3 is closed, and the fuel injection from the fuel injection valve 1 is stopped.

The needle valve 4 is surrounded by a guide wall (hereinafter, referred to as a first guide wall) 9 for guiding its reciprocating motion. The first guide wall 9 has a substantially cylindrical shape and is arranged very close to the needle valve 4. The first guide wall 9 is housed in a substantially cylindrical sleeve 10. Further, the coil spring 7 is a guide wall for guiding its expansion and contraction (hereinafter, a second guide wall).
11 surrounding. The second guide wall 11 has a substantially cylindrical shape and is disposed very close to the coil spring 7. The second guide wall 11 is also housed in the sleeve 10 like the first guide wall 9.

The valve closing solenoid coil 6 and the armature 5
A non-magnetic material (hereinafter, a first non-magnetic material) 12 is disposed between the two. On the other hand, a non-magnetic material (hereinafter, a second non-magnetic material) 13 is also arranged between the valve opening solenoid coil 8 and the armature 5. These non-magnetic members 12 and 13 have an annular shape and function to reliably apply the magnetic field generated by each of the solenoid coils 6 and 8 to the armature 5. Further, the valve closing solenoid coil 6 is surrounded by a housing portion (hereinafter, first housing portion) 14. First housing portion 14 is mounted on sleeve 10. On the other hand, the valve opening solenoid coil 8 is surrounded by a housing portion (hereinafter, a second housing portion) 15 different from the first housing portion 14. The second housing part 15 is mounted on the sleeve 10 similarly to the first housing part 14.
The housing parts 14, 15 are spaced apart from each other, and an insulating space 16 is formed between the housing parts 14, 15. The insulating space 16 also functions to reliably apply the magnetic field generated by each of the solenoid coils 6 and 8 to the armature 5 similarly to the above-described non-magnetic members 12 and 13.

Further, a non-magnetic member 17 is disposed between the first housing part 14 and the second housing part 15.
The non-magnetic material 1 is also provided between the non-magnetic material 17 and the armature 5.
Another non-magnetic body 17a is arranged so as to be in contact with. These non-magnetic members 17 and 17a have a substantially annular shape,
It functions to prevent the magnetic fields generated by the solenoid coils 6, 8 from overlapping each other.

Next, a bounce suppressing mechanism according to this embodiment will be described with reference to FIGS. In the following description, the needle valve 4 and the armature 5 are collectively referred to as a valve body, and the first guide wall 9, the second guide wall 11, the first non-magnetic body 12, and the second non-magnetic body 13 , And the sleeve 10 are collectively referred to as a housing. In the following description, the “front wall surface” is a wall surface facing downstream in the axial direction of the fuel injection valve 1, the “rear wall surface” is a wall surface facing upstream in the axial direction of the fuel injection valve 1, The “outer wall surface” is a wall surface facing outward in the radial direction of the fuel injection valve 1, and the “inner wall surface”
Is a wall surface facing inward in the radial direction of the fuel injection valve 1.

FIG. 2 shows a state where the fuel injection valve 1 is fully opened.
FIG. 3 shows a state in which the fuel injection valve 1 is fully closed. Referring now to FIG. 2, a space (hereinafter, a first space) 18 is formed between the front wall surface 5 f of the armature 5 of the valve body and the rear wall surface 9 b of the first guide wall 9. The volume of the first space 18 changes according to the reciprocating motion of the valve body. As shown in FIG. 2, when the fuel injection valve 1 is fully closed, the volume of the first space 18 is not zero. Referring to FIG. 3, a space (hereinafter, a second space) 19 is formed between the rear wall surface 5 b of the armature 5 of the valve element and the front wall surface 11 f of the second guide wall 11. The volume of the second space 19 also changes according to the reciprocating motion of the valve element, as in the first space 18. As shown in FIG. 3, when the fuel injection valve 1 is fully opened, the volume of the second space 19 is zero.

Referring to FIG. 2, a space (hereinafter referred to as a first fuel passage) 20 is formed between the outer wall surface 4s of the needle valve 4 and the inner wall surface 9s of the first guide wall 9. The width of the first fuel passage 20 is substantially constant regardless of the reciprocating motion of the valve element.
Referring to FIG. 2, the outer wall surface 5 of the armature 5 of the valve element is provided.
A space (hereinafter, referred to as a second fuel passage) 21 is also formed between the first non-magnetic member 12, the sleeve 10, and the inner wall surface s of the second non-magnetic member of the housing. Similarly to the first fuel passage 20, the width of the second fuel passage 21 is substantially constant irrespective of the reciprocating motion of the valve element.

Further, the bounce suppressing mechanism of this embodiment has a fuel flow suppressing means. The fuel flow suppressing means of this embodiment is an elastic body, specifically, the inner wall surface 9 of the first guide wall 9.
s is a seal 22 having a substantially cylindrical shape. The seal 22 extends from the inner wall surface 9s of the first guide wall 9 to the outer wall surface 4s of the needle valve 4, and fuel flows from the first fuel passage 20 downstream of the seal 22 to the first fuel passage 20 upstream of the seal 22, and Allow fuel to flow into one space 18, but allow fuel to flow into first space 18 and seal 2
(2) Inflow from the first fuel passage 20 on the upstream side into the first fuel passage 20 on the downstream side of the seal 22 is prevented. That is, the seal 22 acts as a one-way valve that allows only one fuel flow.

Next, the operation of the bounce suppressing mechanism of this embodiment will be described with reference to FIGS. 4 and 5 schematically show each component of the fuel injection valve for easy understanding. FIG. 4 shows the operation of the bounce suppression mechanism when the fuel injection valve 1 is opened, and FIG. 5 shows the operation of the bounce suppression mechanism when the fuel injection valve 1 is closed. 4 and 5, V is a valve body, and H is a housing.

As shown by the arrow in FIG. 4A, when the valve body V starts to be driven downstream with respect to the housing H, the volume of the first space 18 increases and the volume of the second space 19 decreases. Become. At this time, the fuel in the second space 19 flows from the second space 19 into the fuel chamber 2 and the second fuel passage 21
Through the first space 18. Further, at this time, fuel flows from the first fuel passage 20 downstream of the seal 22 into the first space 18 over the seal 22. FIG. 4B shows a stage in which the valve body V is being driven downstream with respect to the housing H, and the form of fuel flow is the form described above with reference to FIG. Is the same as Finally, as shown in FIG. 4C, when the rear wall surface 5b of the valve body V comes into contact with the front wall surface 11f of the housing H, the driving of the valve body V ends.

As described above, when the fuel injection valve 1 is opened, the valve body V is connected to the housing by the resistance when compressing the fuel in the second space 19 and the flow resistance when the fluid flows through the narrow second fuel passage 21. Bounce on H is suppressed. However, when the fuel injection valve 1 is opened, fuel flows past the seal 22 into the first space 18, which becomes large, so that the degree of suppression is relatively small.

On the other hand, as shown by the arrow in FIG. 5A, when the valve element V starts to be driven to the upstream side with respect to the housing H, the volume of the second space 19 increases, and the volume of the first space 18 increases.
Has a smaller volume. At this time, the fuel in the first space 18 flows from the first space 18 through the second fuel passage 21 to the second space 1.
9 flows into. However, at this time, the fuel in the first space 18 cannot flow into the first fuel passage 20 on the downstream side beyond the seal 22. FIG. 5B shows a stage in which the valve body V is being driven to the upstream side with respect to the housing H, and the flow form of the fuel is described above with reference to FIG. Same as the form. Finally, as shown in FIG. 5C, the driving of the valve body V is completed before the front wall surface 5f of the valve body V contacts the rear wall surface 9b of the housing H.

When the fuel injection valve 1 is closed as described above, the valve body V is moved to the housing by the resistance when compressing the fuel in the first space 18 and the flow resistance when the fluid flows through the narrow second fuel passage 21. Bounce on H is suppressed. Further, since the fuel in the first space 18 is prevented from flowing through the seal 22 and flowing to the first fuel passage 20 on the downstream side, the resistance when the valve body V compresses the fuel in the first space 18 is reduced. Is relatively large.

Thus, according to the present embodiment, as described above, the bounce of the valve body when the fuel injection valve 1 opens or closes can be suppressed. According to this, the minimum injection amount that can be injected from the fuel injection valve 1 can be made as small as possible. Further, in the present embodiment, even when a relatively large space remains between the front wall surface of the valve element forming the first space 18 and the rear wall surface of the housing when the fuel injection valve 1 is fully closed, the seal 22 is used. The seating speed of the valve body can be sufficiently reduced by the resistance increasing action. In other words, according to the present embodiment, even when the space between the front wall surface of the valve body and the rear wall surface of the housing H is large when the fuel injection valve 1 is fully closed, the seating speed of the valve body is sufficiently reduced. Can be done. That is, it is not necessary to reduce the distance between the front wall surface of the valve body and the rear wall surface of the housing when the fuel injection valve 1 is fully closed. Therefore, even if there is a manufacturing error in the valve body or the housing, the fuel injection valve 1 can be completely closed.

In the above embodiment, the valve is closed not only by the coil spring but also by the valve closing solenoid coil, so that the time from when the valve closing command is issued until the valve actually closes the fuel injection hole is short. . That is, the valve closing response of the fuel injection valve is high. In the above embodiment, the seal is attached to the inner wall surface of the first guide wall. However, the seal may be attached to another position as long as the seal functions as a one-way valve.

[0028]

According to the present invention, the compression resistance of the fuel is increased by the one-way valve. Therefore, the seating speed when the valve body is seated on the housing is reduced by the compression resistance, and the bounce of the valve body is suppressed. Thus, a predetermined amount of fuel can be accurately injected from the fuel injection valve.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel injection valve of the present invention.

FIG. 2 is a partial cross-sectional view of the fuel injection valve of the present invention in a valve open state.

FIG. 3 is a partial sectional view of the fuel injection valve of the present invention in a closed state.

FIG. 4 is a diagram for explaining an operation of a bounce suppression mechanism when a fuel injection valve is opened.

FIG. 5 is a diagram illustrating the operation of a bounce suppression mechanism when the fuel injection valve is closed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection hole 4 ... Needle valve 5 ... Armature 6 ... Solenoid coil for valve closing 9 ... First guide wall 18 ... First space 22 ... Seal

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 61/16 F02M 61/16 D

Claims (3)

[Claims] A valve body for opening and closing a fuel injection hole is reciprocally accommodated in a housing, and fuel is injected from the fuel injection hole by reciprocating the valve body in the housing. In the fuel injection valve, a one-way valve is arranged in a space between the valve body and the housing, and the fuel compressed when the valve body is driven to close the fuel injection hole flows by the one-way valve. A fuel injection valve characterized in that it is prevented. 2. The method according to claim 1, wherein the one-way valve is disposed in a space between a wall surface of the valve body extending along a reciprocating direction of the valve body and a wall surface of the housing in a space between the valve body and the housing. The fuel injection valve according to claim 1, wherein: 3. The fuel injection valve according to claim 2, further comprising a solenoid for propelling the valve body in a direction to close the fuel injection hole.