JPH09317596A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize smooth reciprocating movement of a movable core, and control a fuel injection quantity and a fuel injection timing with high accuracy. SOLUTION: A valve body 20 consists of a large diameter part 21 and a small diameter part 22, and formed integratedly with a non-magnetic substance. The outer peripheral wall of the flat plate part 31 of a movable core 30 is guided by the inner circumferential wall of the large diameter part 21 freely to carry out reciprocating motion, and the outer peripheral wall of the cylindrical part 32 of the movable core 30 is guided by the inner circumferential wall of the small diameter part 22 freely to carry out reciprocating motion. The sliding position of the cylindrical part 32 and the small diameter part 22 is positioned on an injection hole side from the axial direction center part of the movable core 30. When turning-on/off of current-carrying to a coil 12 is repeated, reciprocating motion of the movable core 30 is smoothly carried out without deflection from an axial center, and thereby, it is possible to hold the air gap between a yoke 11 and a fixed core 13 and the flat plate part 31 uniformly, and it is also possible to prevent dispersion of attracting force for attracting the movable core 30.

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 having a flat plate type movable core.

[0002]

2. Description of the Related Art Conventionally, by providing a movable core having a flat plate portion on the opposite side to a fixed core and increasing the area opposed to the fixed core, the same suction force can be realized with a small number of coil turns. As a feasible fuel injection valve
No. 43959 and U.S. Pat. No. 5,381,966.
The fuel injection valve disclosed in the specification is known.

FIG. 3 shows a conventional fuel injection valve having such a flat plate type movable core. A coil 102 wound around a spool is housed on the inner circumference of a yoke 101 as a housing of the fuel injection valve 100. A fixed core 103 is further housed inside the coil 102. The movable core 104 formed in a flat plate shape is arranged to face the fixed core 103 with a predetermined air gap. The ball valve 105, together with the movable core 104, has a spring 106.
Is urged toward the valve seat 107 by the urging force of. When the movable core 104 is attracted upward in FIG. 3 by energizing the coil 102 against the biasing force of the spring 106, the ball valve 105 separates from the valve seat 107 and fuel is injected. The maximum lift position of the movable core 104 is restricted by being locked by the spacer 108, and the fixed core 103
An air gap is maintained between the movable core 104 and the movable core 104.
The leaf spring 109 is provided on the ejection side end surface of the movable core 104 so as to suppress swinging when the movable core 104 reciprocates. The guide member 110 is made of a non-magnetic material, guides the ball valve 105, and moves the movable core 104.
By covering the outer periphery of the magnet, magnetic leakage is prevented between the outer periphery of the movable core 104 and the yoke 101, where no attractive force acts in the axial direction.

[0004]

However, in the fuel injection valve having the conventional flat plate type movable core as described above, the leaf spring is required to prevent the movable core from swinging when reciprocating. There is a problem that the number of parts increases and the structure becomes complicated. Moreover, the swinging of the movable core can be suppressed to some extent by the leaf spring, but cannot be suppressed completely.Therefore, the air gap between the fixed core and the movable core varies and smooth reciprocating movement of the movable core is hindered. May be Due to such swinging of the movable core, it is difficult to control the fuel injection amount and the fuel injection timing with high accuracy.

Further, since the outer periphery of the movable core 104 is covered with the guide member 110 in order to prevent magnetic leakage, the diameter of the fuel injection valve 100 is increased by the guide member 110.
Therefore, the effect of reducing the number of turns of the coil by the flat plate type movable core and reducing the diameter of the combustion injection valve is reduced. The present invention has been made to solve such a problem, and provides a fuel injection valve that realizes smooth reciprocating movement of a movable core and can control a fuel injection amount and a fuel injection timing with high accuracy. With the goal.

[0006]

According to the fuel injection valve of the first aspect of the present invention, the movable core is reciprocated by guiding the movable core in the axial direction at two locations of the flat plate portion and the outer periphery of the cylindrical portion. It is possible to prevent rocking at the time. Therefore, since the lift timing and the lift amount of the movable core can be controlled with high accuracy, the fuel injection amount and the fuel injection timing can be controlled with high accuracy.

According to the second aspect of the present invention, since the movable core is guided directly by the valve body made of a non-magnetic material, magnetic leakage from the outer periphery of the movable core is prevented and the diameter of the fuel injection valve is reduced. In addition, the structure of the guide member of the movable core can be simplified and the number of parts can be reduced.
According to the third aspect of the fuel injection valve of the present invention, since the movable core is directly guided by the non-magnetic member extending from the valve body to the side opposite to the injection hole, magnetic leakage from the outer periphery of the movable core is prevented and fuel injection is performed. The diameter of the valve can be reduced, the structure of the guide member of the movable core can be simplified, and the number of parts can be reduced.

According to the fuel injection valve of the fourth aspect of the present invention, it is easy to join the yoke and the guide member.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG.
A coil 12 as an electromagnetic drive unit is housed in the inner circumference of a yoke 11 of the fuel injection valve 10, and a fixed core 13 is fitted in the inner circumference of the coil 12. The yoke 11 and the fixed core 13 are made of a magnetic material. The upper portion of the fixed core 13 in FIG. 2 is covered with a resin housing 15 and a cover 14. The resin housing 15 covers the fixed core 13 and houses the terminal 15a.
The minal 15a and the coil 12 are electrically connected. A suction pipe 16 is fitted to the end of the fixed core 13 on the side opposite to the injection hole, and a filter 17 is housed inside the suction pipe 16. The fuel that has flowed in from the suction pipe 16 has foreign matter removed by the filter 17, and the fuel passage 1 formed in the fixed core 13
3a. A valve body 20 as a guide member is fixed to the end portion of the yoke 11 on the injection hole side by welding or the like.
A movable core 30 is housed inside the valve body 20 so as to face the yoke 11 and the fixed core 13 in the axial direction.

Next, the structure of the fuel injection valve 10 on the injection hole side will be described in detail with reference to FIG. The valve body 20 includes a large-diameter portion 21 and a small-diameter portion 22 having an inner diameter smaller than that of the large-diameter portion 21 from the non-injection hole side, and is integrally formed of a non-magnetic material. A valve portion 33, which will be described later, is provided on the inner peripheral wall of the small diameter portion 22.
Is formed with a valve seat 22a. Large diameter part 21
The outer diameter of the yoke 1 is almost the same as the outer diameter of the yoke 11.
When 1 and the large diameter portion 21 are fixed by welding or the like, a cylindrical body having substantially the same outer diameter from the yoke 11 to the large diameter portion 21 is formed. A cup member 40 having a nozzle hole 41 is fixed to the tip of the valve body 20 by welding or the like.

A taper diameter portion 23 is provided between the small diameter portion 22 and the large diameter portion 21. This taper diameter portion 23
Has a taper inner wall surface 23a whose diameter becomes smaller toward the tip side.
Are formed. A space portion 30b is formed by the taper inner wall surface 23a and a cylindrical portion 32 described later. The movable core 30 includes a flat plate portion 31 facing the yoke 11 and the fixed core 13, a cylindrical portion 32 formed to extend from the flat plate portion 31 toward the injection hole side, and a valve portion formed on the injection hole side of the cylindrical portion 32. It is composed of 33 and is integrally formed. Movable core 3
A fuel passage 30a is formed in the filter 0, and the filter 1
The fuel flowing into the fuel passage 30a from the fuel passage 13a via 7 is supplied from the fuel passage 30a to the injection hole side. Valve 3
3 can be seated on the valve seat 22a, and the valve portion 33 is
By sitting on a, the communication between the fuel passage 30a and the injection hole 41 is cut off.

The spring 34 is housed in the fuel passage 30a. One end of the spring 34 has a movable core 30.
Of the fixed core 13 and the other end of the fixed core 13 is locked in a recess 13b formed in the end of the fixed core 13 on the injection hole side.
The movable core 30 is moved to the valve seat 22 by the urging force of the spring 34.
It is biased toward a. An annular stopper 50 is fitted between the inner peripheral wall of the end of the yoke 11 on the injection hole side and the outer peripheral wall of the end of the fixed core 13 on the injection hole side, and the end surface of the stopper 50 is closer to the injection hole than the end surface of the yoke 11. Overhangs. The stopper 50 restricts the maximum lift position of the movable core 30 by locking the flat plate portion 31, and the fuel passage 1
The fuel flowing into the fuel passage 30a from the coil 3a
Are prevented from entering. The stopper 50 may be made of a non-magnetic metal or rubber having excellent fuel resistance.

The outer peripheral wall of the flat plate portion 31 of the movable core 30 is directly guided by the inner peripheral wall of the large diameter portion 21 of the valve body 20 so as to be capable of reciprocating, and the outer peripheral wall of the cylindrical portion 32 of the movable core 30 is the valve body 20. It is directly guided by the inner peripheral wall of the small diameter portion 22 so as to be capable of reciprocating. The sliding position between the cylindrical portion 32 and the small diameter portion 22 is located closer to the injection hole than the axial center of the movable core 30. In the cylindrical portion 32, the fuel passage 30
A communication passage 32a is formed which communicates a with the space portion 30b.

Next, the operation of the fuel injection valve 10 will be described. (1) When the coil 12 is de-energized, the valve portion 3 of the movable core 30
3 is seated on the valve seat 22a by the biasing force of the coil 34. Therefore, the fuel introduced to the injection hole side via the filter 17, the fuel passage 13a, and the fuel passage 30a does not flow into the injection hole 4
Injection from 1 is blocked.

(2) When the coil 12 is energized, the coil 1
The magnetic flux generated in 2 causes the yoke 11 and the fixed core 13 to
When the movable core 30 is sucked toward the fixed core side against the urging force of the spring 34 by the air gap formed between the end surface of the flat hole portion 31 and the end surface of the flat plate portion 31 opposite to the injection hole side, the valve portion 33
Moves away from the valve seat 22a. When the valve portion 33 is separated from the valve seat 22a, the fuel flowing from the fuel passage 30a is injected into the injection hole 41.
Injected from. While energizing the coil 12, the flat plate portion 3
1 holds the state of being locked by the stopper 50.

By repeatedly turning the coil 12 on and off, the movable core 30 is guided by the valve body 20 and repeats reciprocating movement. At this time, the outer peripheral wall of the flat plate portion 31 and the outer peripheral wall of the cylindrical portion 32 are reciprocally supported by the inner peripheral wall of the valve body 20. Further, since the sliding position between the cylindrical portion 32 and the valve body 20 is located closer to the injection hole side than the central portion in the axial direction of the movable core 30, the sliding position of the flat plate portion 31 and the sliding position of the cylindrical portion 32 are different from each other. Are separated from each other in the axial direction of the movable core 30. Therefore, the movable core 30 smoothly reciprocates without shaking from the axial center. In addition, the movable core 30 does not move from the axis center and the yoke 11 and the fixed core 1
Since the air gap formed between the coil 3 and the flat plate portion 31 can be kept uniform, it is possible to prevent the suction force for sucking the movable core 30 from being varied when the coil 12 is energized. Therefore, the lift timing of the movable core 30 can be controlled with high accuracy, so that the fuel injection amount and the fuel injection timing of the fuel injection valve 10 can be controlled with high accuracy.

In the above-described embodiment of the present invention described above, since the large-diameter portion 21 of the valve body 20 made of a non-magnetic material guides the flat plate portion 31 so as to directly reciprocate, the flat plate portion 3
The magnetism can be prevented from leaking from the outer periphery of No. 1 and the attraction force can be prevented from decreasing, and the diameter of the fuel injection valve 10 around the movable core 30 can be reduced. In addition, the movable core 30 is reciprocally supported at two locations of the outer peripheral wall of the flat plate portion 32 and the outer peripheral wall of the cylindrical portion 32, and the space portion 30b is provided between the supported portions at these two locations.
A communication passage 32a is formed that communicates with the. As a result, the cylindrical portion 32 can be formed to be long in the axial direction,
The inclination of the cylindrical portion 32 when the movable core 30 reciprocates can be prevented. Further, when the movable core 30 reciprocates, the cylindrical portion 3
Since the fuel between the 2 and the tapered diameter portion 23 can escape to the fuel passage 30a through the communication passage 32a, the movable core 30 can be smoothly reciprocated.

Further, in this embodiment, the stopper 50 regulates the lift amount of the movable core 30 and also functions as a seal member for preventing fuel from entering the coil 12.
The number of parts can be reduced. Although the movable core 30 is integrally formed in this embodiment, the flat plate portion and the cylindrical portion of the movable core may be integrally formed, and the valve portion may be formed separately from the movable core. Further, although the valve body 20 is integrally formed of a non-magnetic material and the valve body 20 guides the movable core 30 so as to be reciprocally movable, the valve body 20 is made of a non-magnetic material that guides at least the flat plate portion of the movable core so as to be reciprocally movable. It is also possible to separately form the guide member and the valve body provided with the valve seat. In this case, the valve body may be made of a magnetic material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a fuel injection valve according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a fuel injection valve according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional fuel injection valve.

[Explanation of symbols]

 10 Fuel injection valve 11 Yoke 12 Coil 13 Fixed core 20 Valve body (guide member) 21 Large diameter part 22 Small diameter part 22a Valve seat 30 Movable core 31 Flat plate part 32 Cylindrical part 33 Valve part 41 Injection hole

Claims (4)

[Claims] 1. A flat plate portion axially opposed to the fixed core,
A movable core having a cylindrical portion formed to extend from the flat plate portion toward the injection hole side is provided, and the movable core is guided so as to be capable of reciprocating at two locations of the flat plate portion outer periphery and the cylindrical portion outer periphery. A fuel injection valve characterized by the above. 2. The guide member for guiding the outer periphery of the flat plate portion in a reciprocating manner is a valve body made of a non-magnetic material having a valve seat on which a valve portion for opening and closing an injection hole can be seated. The fuel injection valve according to claim 1. 3. A non-magnetic member extending from a valve body having a valve seat on which a valve portion for opening and closing the injection hole can be seated, to the injection hole side, the guide member reciprocatingly guiding the outer periphery of the flat plate portion. The fuel injection valve according to claim 1, wherein 4. The fuel injection valve according to claim 2, wherein an outer diameter of the guide member is substantially the same as a yoke that accommodates the fixed core.