JP2006097659A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of improving atomization of injected fuel. <P>SOLUTION: This fuel injection valve 1 for a fuel injection device for an internal combustion engine is provided with an electromagnetic coil 18 energized to generate magnetic force, a stator 21 to which the magnetic force generated by the electromagnetic coil 18 is provided to be an electromagnet, a body 2 to house the electromagnetic coil 18 and the stator 21, a mover 25 having a stator side end surface 26 to be attracted by the stator 21 having magnetic force and a counter-stator side end surface 27, a needle 10 supported to penetrate the mover 25, and be axially movable, a first large diameter part 11 formed in the needle 10 to face the stator side end surface 26, and a first energization means 16 to energize the mover 25 in a separating direction from the stator. When the valve is closed, a gap is formed between the stator side end surface 26 and the first large diameter part 11 by the first energization means 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve used in a fuel injection device.

  Conventionally, a fuel injection valve as disclosed in JP-T-2002-528672 has been known (Patent Document 1).

  This prior art fuel injection valve includes an electromagnetic coil 100, a stator 110, an armature 120, a spring 130 that presses the armature 120 toward the stator 110, a needle 150 having a valve element 140, and a spring 170 that presses the needle 150 toward the injection hole 160. Consists of. In the needle 150, the armature 120 is disposed so as to be able to reciprocate between a first stopper 180 and a second stopper 190 formed on the needle 150 (see FIG. 4).

In this fuel injection valve, the armature 120 is in contact with the first stopper 180 by the urging force of the spring 130 when the electromagnetic coil 100 is not energized. When the electromagnetic coil 100 is energized, the needle 150 moves toward the stator 110 while maintaining the contact between the armature 120 and the first stopper 180. Then, the valve body 140 is separated from the valve seat body 200, the injection hole 160 formed in the valve seat body 200 is opened, and fuel is injected.
Japanese translation of PCT publication No. 2002-528672

  In the fuel injection valve of the type in which the needle 150 is moved to separate the valve body 140 from the valve seat body 200 and the injection hole 160 is opened to inject fuel as in the conventional fuel injection valve, the valve body 140 A period during which the area of the gap between the valve body 140 and the valve seat body 200 formed when separating from the valve seat body 200 is smaller than the passage area of the nozzle hole 160 (hereinafter referred to as the initial valve opening) is sufficient. Since the fuel having a large pressure cannot reach the nozzle hole 160, the actual injection pressure becomes low, and the injection speed of the fuel from the nozzle hole 160 becomes slow. Then, the particle size of the injected fuel during this period becomes relatively large. A gap between the valve body 140 and the valve seat body 200 formed when the valve body 140 in this state is separated from the valve seat body 200 is referred to as a seat restriction.

  Therefore, the longer the initial valve opening period, the smaller the area of the seat restriction is in the passage area of the nozzle hole 160, and the longer the period in which injected fuel with a relatively large particle size is injected, There has been a problem that the average particle size of the injected fuel becomes large.

  This invention is made | formed in view of the said problem, and it aims at providing the fuel injection valve which improves atomization of the injection fuel of a fuel injection valve.

  In order to achieve the above object, in claim 1, a fuel injection valve for a fuel injection device of an internal combustion engine, an electromagnetic coil that generates a magnetic force when energized, and an electromagnet provided with the magnetic force generated by the electromagnetic coil A movable body having a stator-side end face and an anti-stator-side end face that are supported so as to be movable in the axial direction and are attracted to the stator to which magnetic force is applied. A needle, a needle that penetrates the mover and is supported so as to be movable in the axial direction, a first enlarged-diameter portion formed on the needle so as to face the stator side end surface, and a direction away from the stator And a first urging means for urging the mover, and when the valve is closed, the first urging means forms a gap between the stator side end surface of the mover and the first enlarged diameter portion. And

  As a result, when the valve is opened, the kinetic energy stored in the mover and the magnetic force generated by the electromagnetic coil are transmitted to the needle by moving the distance corresponding to the gap. The speed of the needle of the fuel injection valve can be made faster, and the time during which the seat restriction is formed can be shortened than before. Since the time during which the sheet restriction is formed is shortened, the period during which the injected fuel having a relatively large particle diameter is injected is shortened, and the atomization of the injected fuel can be improved.

  According to a second aspect of the present invention, the needle is formed with a second enlarged diameter portion at a position facing the end surface on the side opposite to the stator of the mover.

  Thereby, when the fuel injection valve is closed, the gap between the stator side end face and the stator can be kept at an appropriate distance.

  According to a third aspect of the present invention, the surface of the first enlarged diameter portion that faces the stator side end surface is a surface that is substantially perpendicular to the moving direction of the needle.

  Thereby, when a needle | mover contact | abuts to a 1st enlarged diameter part and the energy which a needle | mover has transmits to a needle, energy can be transmitted efficiently.

  According to a fourth aspect of the present invention, the surfaces facing the stator side end surface and the anti-stator side end surface of the first enlarged diameter portion and the second enlarged diameter portion are curved surfaces or inclined surfaces, respectively.

  As a result, the stress applied to the boundary between the first diameter-expanded portion and the second diameter-expanded portion and the needle when the mover contacts the first diameter-expanded portion and the second diameter-expanded portion can be dispersed. The life of the needle can be maintained for a long time.

  According to a fifth aspect of the present invention, the second urging means for urging the needle in a direction away from the stator is provided, and the urging force of the first urging means is weaker than the urging force of the second urging means. .

  Since the urging force of the first urging means may be such that the movable element does not move due to vibration of the internal combustion engine when the valve is closed, the kinetic energy generated by the urging force of the first urging means when the movable element moves. Loss can be suppressed as much as possible.

(One embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the present embodiment, a fuel injection valve for directly injecting fuel, particularly gasoline, into a combustion chamber of an internal combustion engine (hereinafter referred to as an engine) will be described. However, the fuel injection valve according to the present invention can also be applied to a gasoline engine for so-called port injection.

  FIG. 1 is a sectional view showing a fuel injection valve according to an embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view of a region I in FIG.

  In FIG. 1, fuel stored in a fuel tank (not shown) is sucked into a supply pump by a feed pump (not shown) built in a supply pump (not shown) and compressed to a high pressure by the supply pump. And then supplied to a delivery pipe (not shown). This delivery pipe is connected with one fuel injection valve 1 for each cylinder of the engine, and each fuel injection valve 1 is in accordance with a drive signal from an electronic control unit (hereinafter referred to as ECU: not shown). Perform the injection operation.

  Hereinafter, the configuration of the fuel injection valve 1 will be described in detail.

  The casing of the fuel injection valve 1 is composed of a body 2 and a valve body 3 each formed in a cylindrical shape, which are integrated by fastening a retaining nut 6 via a ring 8. Inside the casing, a long needle 10 having a valve closing body 13 formed at the tip is accommodated. The ring 8 is for adjusting the stroke amount of the needle 10, and the adjustment can be performed by changing the thickness of the ring 8. A seal ring 9 is provided between the inner wall of the body 2 and the outer wall of the valve body 3.

  A valve seat body 4 formed in a bottomed cylindrical shape is provided at the tip of the valve body 3. A nozzle hole 5 is formed at the bottom of the valve seat body 4. The fuel passes through the casing of the fuel injection valve 1 and is injected from the injection hole 5. The nozzle hole 5 is closed by seating the valve closing body 13 on the valve seat surface formed in the valve seat body 4, and the nozzle hole 5 is opened by separating the valve closing body 13 from the valve seat surface. It has become.

  The body 2 is provided with an electromagnetic actuator that reciprocates the needle 10 in the axial direction. The electromagnetic actuator includes an electromagnetic coil 18, a stator 21 (hereinafter referred to as a stator), and a mover 25 (hereinafter referred to as an armature). The electromagnetic coil 18 has a cylindrical shape around which a thin enamel wire is wound. The electromagnetic coil 18 is arranged on the outer wall of the body 2 while being molded in the resin member 20, and is fixed to the body 2 by the cylindrical nut 7. A terminal 19 connected to the coil end of the electromagnetic coil 18 is molded on the resin member 20, and a magnetic force is generated in the electromagnetic coil 18 when energized by the ECU.

  The stator 21 includes a main stator 22 and a sub-stator 23, and the sub-stator 23 is inserted and fixed in a through hole formed in the main stator 22 as shown in FIG. 1. The sub-stator 23 has a fuel passage 24 for passing fuel through substantially the center, a needle 10 and an armature 25 as first urging means for urging the nozzle 10 and the armature 25 in the direction of the nozzle hole 5 (the direction away from the stator 21). A surface for holding the one coil spring 16 and the second coil spring 17 as the second urging means is formed.

  The armature 25 has a stator side end face 26 (hereinafter referred to as a stator side end face) and an anti-stator side end face 27 (hereinafter referred to as an anti-stator side end face). When a magnetic force is generated in the electromagnetic coil 18, the stator 21 becomes an electromagnet, and the armature 25 is pulled until the stator side end surface 26 comes into contact with the opposite end surface of the stator 21.

  As shown in FIG. 1 and FIG. 2, a first stopper 11 as a first diameter-expanded portion that can come into contact with the stator-side end face 26 of the armature 25 is provided at the opposite end of the valve closing body 13 of the needle 10. A second stopper 12 is formed as a second diameter-expanded portion that can come into contact with the non-stator side end surface 27. The armature 25 is provided so as to be movable in the axial direction between the first and second stoppers 11 and 12. The armature 25 is pressed in the direction of the nozzle hole 5 with a predetermined biasing force by the first coil spring 16, and the needle 10 is pressed in the direction of the nozzle hole 5 with a predetermined biasing force by the second coil spring 17.

  When the electromagnetic coil 18 is not energized, the urging force of the first and second coil springs 16 and 17 causes the non-stator side end surface 27 to abut against the second stopper 12, and the valve closing body 13 Sitting on body 4 At this time, a gap 30 is formed between the stator side end face 26 and the first stopper 11.

  The second stopper 12 is formed at a position where the distance between the stator side end surface 26 and the stator 21 is a predetermined distance when the non-stator side end surface 27 is in contact with the second stopper 12. The distance is larger than the gap 30 and is a distance at which the stator 21 can draw the armature 25 by the magnetic force generated when the electromagnetic coil 18 is energized. Note that the second stopper 12 may not be formed on the needle 10. For example, it may be a protrusion protruding from the inner wall of the body 2 toward the center.

  Next, the operation of the fuel injection valve 1 will be described.

(When the valve is opened)
When the electromagnetic coil 18 is energized by a drive signal given from the ECU, a magnetic force is generated in the electromagnetic coil 18, and the stator 21 becomes an electromagnet by this magnetic force, and the armature 25 is made to resist the urging force of the first coil spring 16. Draw. At an initial stage when the armature 25 is attracted to the stator 21, a gap 30 is formed between the stator side end face 26 and the first stopper 11, and therefore the armature 25 has the stator side end face 26 at the first stopper 11. It moves alone until it touches. At this time, the armature 25 stores kinetic energy corresponding to the magnetic force generated by the electromagnetic coil 18, the distance between the stator side end face 26 and the first stopper 11, and the mass of the armature 25.

  When the stator side end face 26 comes into contact with the first stopper 11, the armature 25 continues to move toward the stator 21 together with the needle 10. At the moment when the stator-side end face 26 comes into contact with the first stopper 11, the force that the armature 25 is attracted to the needle 10 by the magnetic force generated in the electromagnetic coil 18 and the kinetic energy stored in the initial stage of the movement of the armature 25 Is transmitted, and the needle 10 moves toward the stator 21.

  In the present embodiment, the surface of the first stopper 11 that faces the stator-side end surface 26 is formed substantially perpendicular to the moving direction of the needle 10, whereby the stator-side end surface 26 contacts the first stopper 11. When contacting, the force attracted by the kinetic energy and the magnetic force can be efficiently transmitted.

  Thereafter, the armature 25 that moves integrally with the needle 10 moves until it abuts against the end face of the stator 21. When the armature 25 abuts against the stator 21, the valve opening operation ends, and thereafter the valve opening state is maintained. Is done. When both the armature 25 and the needle 10 move toward the stator 21, the valve closing body 13 is separated from the valve seat surface of the valve seat body 4, the injection hole 5 is opened, and fuel is injected from the injection hole 5. .

  In the present embodiment, the urging force of the first coil spring 16 is weaker than the urging force of the second coil spring 17. The first coil spring 16 is for preventing the armature 25 from moving due to engine vibration when the valve is closed, and the role of the first coil spring 16 is different from that of the second coil spring 17 that presses the valve closing body 13 against the valve seat body 4. . By making the biasing force of the first coil spring 16 weaker than the biasing force of the second coil spring 17, the loss of the kinetic energy caused by the biasing force of the first coil spring 16 can be suppressed as much as possible.

(When valve is closed)
When the energization of the electromagnetic coil 18 is stopped by the drive signal given from the ECU, the force that attracts the armature 25 by the stator 21 is lost, and the armature 25 and the needle 10 are ejected by the urging force of the first and second coil springs 16 and 17. Move in the direction of the hole 5. When the valve closing body 13 comes into contact with the valve seat surface of the valve seat body 4, the valve closing operation ends, and thereafter the valve closed state is maintained. Then, the non-stator side end face 27 of the armature 25 is brought into contact with the second stopper 12. Thus, the needle 10 moves in the direction of the nozzle hole 5 and the valve closing body 13 is seated on the valve seat surface of the valve seat body 4, whereby the nozzle hole 5 is closed and fuel injection is stopped.

  Next, the effect of the fuel injection valve 1 will be described.

  In the conventional fuel injection valve, when the electromagnetic coil 100 is energized by a drive signal given from the ECU, the needle 150 is attracted to the stator 110 integrally with the armature 120 from the initial stage of valve opening. At this time, only the magnetic force generated by the electromagnetic coil 100 acts on the needle 150 in the direction of the stator 110.

  On the other hand, in the fuel injection valve 1 of the present embodiment, a gap 30 is formed between the stator side end face 26 of the armature 25 and the first stopper 11 when the valve is closed. For this reason, when the electromagnetic coil 18 is energized by the drive signal given from the ECU, first, only the armature 25 moves in the direction of the stator 21 by the magnetic force generated by the electromagnetic coil 18. At this time, kinetic energy corresponding to the distance of the gap 30 is stored in the armature 25. Next, when the armature 25 having kinetic energy comes into contact with the first stopper 11, the force at which the armature 25 is attracted to the needle 10 by the magnetic force generated in the electromagnetic coil 18, and the kinetic energy stored in the armature 25. Is transmitted, and the needle 10 moves toward the stator 21.

  In the fuel injection valve 1 of the present embodiment, the needle 10 is moved by the force that attracts the armature 25 by the magnetic force generated in the electromagnetic coil 18 and the kinetic energy stored in the armature 25, so that the initial opening speed of the needle 10 is increased. It becomes possible to make it faster than the speed of the needle 150 of the conventional fuel injection valve, and it is possible to shorten the time during which the seat restriction is formed as compared with the conventional case. Since the time during which the sheet restriction is formed is shortened, the period during which the injected fuel having a relatively large particle diameter is injected is shortened, and the atomization of the injected fuel can be improved.

(Modification 1)
Next, the fuel injection valve 1 according to the first modification of the present invention will be described with reference to FIG. FIG. 3 is an enlarged partial sectional view of a main part of the fuel injection valve 1 according to the first modification of the present invention. In addition, the same function thing as one Embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.

  As shown in FIG. 3, the first modification is characterized in that the boundary portion between the first stopper 11 and the needle 10 is a curved surface 14, and the portion of the stator side end surface 26 that faces the curved surface 14 has the same curvature as the curved surface 14. The curved surface 28 is used. A boundary portion between the second stopper 12 and the needle 10 is also a curved surface 15, and a portion of the non-stator side end surface 27 facing the curved surface 15 is a curved surface 29 having the same curvature as the curved surface 15.

  As a result, the stress applied to the boundary between the first stopper 11 and the second stopper 12 and the needle 10 when the armature 25 contacts the first stopper 11 and the second stopper 12 can be dispersed. It is possible to maintain a long life.

  The curved surfaces 14 and 15 formed on the first and second stoppers 11 and 12 may be inclined surfaces.

It is sectional drawing which shows the fuel injection valve by one Embodiment of this invention. It is the fragmentary sectional view which expanded the part of the range I of FIG. It is the fragmentary sectional view which expanded the principal part of the fuel injection valve by the modification 1 of this invention. It is sectional drawing which shows the conventional fuel injection valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Body 3 Valve body 4 Valve seat body 5 Injection hole 10 Needle 11 1st stopper 12 2nd stopper 13 Valve closing body 16 1st coil spring (1st biasing means)
17 Second coil spring (second biasing means)
18 Electromagnetic coil 21 Stator 25 Armature 26 Stator side end face 27 Anti-stator side end face 30 Gap

Claims (5)

A fuel injection valve for a fuel injection device of an internal combustion engine,
An electromagnetic coil that generates a magnetic force when energized;
A stator that is provided with a magnetic force generated by the electromagnetic coil and becomes an electromagnet;
A body that houses the electromagnetic coil and the stator;
A mover having a stator-side end surface and an anti-stator-side end surface that are supported so as to be movable in the axial direction and attracted to the stator to which magnetic force is applied;
A needle that penetrates the mover and is supported so as to be movable in the axial direction;
A first enlarged diameter portion formed on the needle so as to face the stator side end surface;
First biasing means for biasing the mover in a direction away from the stator,
A fuel injection valve characterized in that when the valve is closed, a gap is formed between the stator-side end surface of the mover and the first diameter-expanded portion by the first urging means.   2. The fuel injection valve according to claim 1, wherein the needle is formed with a second enlarged diameter portion at a position facing the end face on the side opposite to the stator of the mover.   2. The fuel injection valve according to claim 1, wherein a surface of the first enlarged diameter portion facing the stator side end surface is a surface substantially perpendicular to a moving direction of the needle.   The surface facing the stator side end surface and the anti-stator side end surface of each of the first enlarged diameter portion and the second enlarged diameter portion is a curved surface or an inclined surface. 2. The fuel injection valve according to 2. Second urging means for urging the needle in a direction away from the stator;
5. The fuel injection valve according to claim 1, wherein a biasing force of the first biasing unit is weaker than a biasing force of the second biasing unit.

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