JPH11117832A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weld the body and the nozzle-hole member of a fuel injection valve together at sufficient strength so that the injection valve produces a well-atomized fuel spray even from a nozzle hole of a reduced diameter. SOLUTION: A nozzle plate 61 that has the form of a bottomed cylinder or a cup comprises a substantially disklike bottom 61a and a cylinder part 61b extending from the bottom 61a toward a magnetic pipe 23. The plate 61 is pressed in the fuel-downstream end of a valve body 26. The bottom 61a is thinned at its middle to have a thin-plate portion 61c thinner than the bottom 61a and the cylinder part 61b, which thin-plate portion is formed therethrough with a nozzle hole 61d. Even if the nozzle hole 61d is decreased in diameter and the thin-plate portion 61c is made thinner for a well-atomized fuel spray, the cylinder part 61b is allowed to have a necessary thickness as before irrespective of the thickness of the thin-plate portion 61c, such that the valve body 26 and the nozzle plate 61 are welded together at sufficient strength.

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 structure of an injection hole member provided with an injection hole.

[0002]

2. Description of the Related Art In recent years, emission regulations for automobiles have been tightened, and therefore, atomization of injected fuel (spray) is required for fuel injection valves used in automobile engines. Therefore, there is known a fuel injection valve in which an injection hole member having a plate-shaped plate portion is disposed on the fuel downstream side of a valve body having a valve seat, and the plate portion is provided with an injection hole adapted to atomization of spray. Have been. The injection hole member as described above is formed by forming an injection hole in a metal plate having a uniform thickness, or by processing a metal plate having a uniform thickness into a bottomed cylindrical shape to form an injection hole in the bottom surface thereof, It is joined to the body by welding.

[0003]

However, in a conventional fuel injection valve using an injection hole member formed of a metal plate having a uniform thickness as described above, the number of injection holes is reduced in order to further atomize the spray. When the injection hole diameter is reduced to increase or reduce the injection amount, the length of the injection hole in the injection direction relative to the injection hole diameter becomes relatively long, and there is a problem that atomization of the spray is deteriorated. Therefore, it is desirable that the ratio between the diameter of the injection hole and the thickness be constant. However, if the thickness of the injection hole member is reduced, the thickness of the joint with the valve body is also reduced, resulting in poor press-fitting and perforation due to over welding. There is a possibility that poor welding may occur, and there is a problem that the valve body and the injection hole member cannot be joined with sufficient strength.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a stable spray state even if the diameter of the injection hole is reduced, and to provide a sufficient strength between the valve body and the injection hole member. An object of the present invention is to provide a fuel injection valve that can be joined by using a fuel injection valve.

[0005]

According to the fuel injection valve of the present invention, the injection hole member has a joint portion joined to the valve body and a thin plate portion thinner than the joint portion. The injection hole formed in the thin plate portion covers the opening so that the fuel passage can communicate with the outside, so that the injection hole is formed while sufficiently maintaining the strength of the joint between the valve body and the injection hole member. Since the thin plate portion can be made thin, even when the diameter of the injection hole is reduced, the accumulation of fuel in the injection hole can be prevented, and the fuel spray amount and the fuel spray shape can be stabilized.

According to the fuel injection valve of the second aspect of the present invention, since the injection hole member is formed in a cylindrical shape with a bottom, by providing a joint on the side surface of the injection hole member, a flat injection is provided. The distance between the valve seat and the welding position can be made longer than when the hole member is used. Therefore, it is possible to prevent the valve seat from being deformed by heat when the joint is joined to the valve body by welding.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an example in which a fuel injection valve according to an embodiment of the present invention is applied to a fuel supply device for a gasoline engine. As shown in FIG. 2, a fixed iron core 21, a spool 51, an electromagnetic coil 32, metal plates 53 and 54 are integrally accommodated in a resin casing 11 of the fuel injection valve 10. Pressurized fuel is introduced into the fixed core 21 from above.

[0008] The fixed iron core 21 made of a ferromagnetic material has a fuel passage 21a therein so that pressurized fuel can flow through the fuel passage 21a. Also, the fuel passage 21
An adjusting pipe 29 having a fuel passage (not shown) that can communicate with the fuel passage 21a is accommodated in the a. The adjusting pipe 29 is fixed in the fixed iron core 21 by press-fitting means or the like and is movable in the axial direction.

A non-magnetic pipe 2 is provided between the fixed iron core 21 and the magnetic pipe 23 located on the anti-fuel introduction side of the fixed iron core 21.
4 are located. The fixed iron core 21, the non-magnetic pipe 24 and the magnetic pipe 23 are joined to each other by laser welding. The needle 25 is positioned on the anti-fuel introduction side of the adjusting pipe 29.
A compression coil spring 28 biasing to the side is located and is also housed in the fixed iron core 21. And
The urging force on the needle 25 contacting the other end of the compression coil spring 28 is adjusted by the axial movement of the adjusting pipe 29 described above.

A movable iron core 22 is accommodated in the magnetic pipe 23 and the non-magnetic pipe 24 so as to be slidable in the axial direction while straddling both of them, and a compression coil spring 28 is further provided in the movable iron core 22. One end of the needle 25 biased toward the non-fixed iron core 21 is housed. When the needle 25 moves toward the fixed core 21, the movable core 22 also moves toward the fixed core 21. When the movable core 22 moves toward the fixed core 21, the needle 25 also moves toward the fixed core 21. The movable iron core 22 and one end of the needle 25 are formed.

The electromagnetic coil 32 is located in the casing 11 so as to cover the ends of the fixed iron core 21 and the magnetic pipe 23 which sandwich the nonmagnetic pipe 24 and the periphery of the nonmagnetic pipe 24. . The metal plates 53 and 54 are positioned so as to cover the periphery of the spool 51 around which the wire is wound, and constitute the electromagnetic coil 32. Each end of the wire wound around the electromagnetic coil 32 is electrically connected to a plurality of terminals 34 so that a voltage applied to the terminal 34 can be supplied to the electromagnetic coil 32.

As a result, when the electromagnetic coil 32 is energized, a magnetic flux is generated, and the magnetic flux is generated by the fixed core 21, the metal plate 53, the magnetic pipe 23, the movable core 22, and the magnetic pipe 23.
And a magnetic path formed by the metal plate 54,
An electromagnetic attraction force capable of attracting the movable iron core 22 is generated in the electromagnetic coil 32 on the fixed iron core 21 side. Therefore, when the movable iron core 22 is attracted to the fixed iron core 21 side by this electromagnetic attraction force, the needle 25 also moves to the fixed iron core 21 side, and the energization of the electromagnetic coil 32 is interrupted and when the electromagnetic attraction force disappears, the compression coil spring 28 The movable iron core 22 and the needle 25 move toward the non-fixed iron core 21 side by the urging force.

As shown in FIG. 1, a valve body 26 as a valve body located at an end of the fuel injection valve 10 is welded to an end of the magnetic pipe 23 on the side of the non-magnetic pipe 24 at a welding position 91.
The fuel passages 27a and 27b are formed inside the fuel passage 27a and the fuel passage 21a of the fixed iron core 21 via a fuel passage (not shown). The fuel passage 27b is open at an end of the valve body 26.

The needle 25 slidable in the axial direction in the magnetic pipe 23 has a valve member 25a formed in a substantially frustoconical shape at the end of the non-movable iron core 22 side. This valve member 25a
Are housed in the fuel passages 27a and 27b, and are configured to be able to cut off communication between the fuel passage 27a and the fuel passage 27b when abutting against a valve seat 26b formed on the inner wall of the valve body 26. Thus, when the valve member 25a is seated on the valve seat 26b, the communication between the fuel passage 27a and the fuel passage 27b is interrupted, and when the valve member 25a is separated from the valve seat 25b, the communication between the fuel passage 27a and the fuel passage 27b is made conductive. Accordingly, as described above, the energization of the electromagnetic coil 32 controls the axial movement of the needle 25 to control the seating or unseating of the valve member 25a, thereby interrupting or establishing communication between the fuel passage 27a and the fuel passage 27b. Or let it. That is, the pressurized fuel introduced into the fuel passage 27b is controlled by energizing the electromagnetic coil 32.

A nozzle plate 61 as an injection hole member is
For example, it is formed of a stainless steel plate, is formed in a so-called cup shape having a bottomed cylindrical shape, and has a substantially disk-shaped bottom portion 61a and a cylindrical portion 61b as a joining portion extending from the bottom portion 61a to the magnetic pipe 23 side. 1, and is press-fitted into the fuel downstream end of the valve body 26. At the center of the bottom portion 61a, a thin plate portion 61c having a smaller thickness than the bottom portion 61a and the cylindrical portion 61b is formed. Fuel passage 27 as opening of valve body 26
The end face b is covered with the thin plate portion 61c. As a method for forming the nozzle plate 61, a method in which a stainless steel plate is formed into a cup shape having a uniform thickness and then the bottom portion 61 a is partially thinned by face pressing of a press to form a thin plate portion, Either method may be used in which a flat stainless steel plate is pressed to form a thin plate portion and then processed into a cup shape.

A plurality of injection holes 61d are formed in the thin plate portion 61c of the nozzle plate 61. The formation position of the injection hole 61d is set to a position where the nozzle plate 61 can be connected to the fuel passage 27b of the valve body 26 when the nozzle plate 61 is attached to the valve body 26. Thereby, the valve member 25
Pressurized fuel flowing into the fuel passage 27b due to the unseated position a is injected from the injection hole 61d to the outside of the fuel injection valve 10. The formation of the injection hole 61d is performed by electric discharge, press working, or the like.
Its inner diameter is adjusted to obtain a desired fuel flow rate. When the inner diameter of the injection hole 61d is made small, the length of the injection direction of the injection hole 61d becomes relatively long, so that there is a problem that the spray particle diameter is deteriorated. Since the thickness of the thin plate-shaped portion 61c can be reduced so as to maintain a constant value, good atomized spray can be obtained.

After the cylindrical portion 61b of the nozzle plate 61 is press-fitted into the nozzle body 26, the cylindrical portion 61b is welded and fixed at the welding position 92 over the entire outer wall of the valve body 26. By welding with the cylindrical portion 61b, the distance between the valve seat and the welding position can be made longer than when a flat nozzle plate is used. Therefore, when the nozzle plate 61 and the valve body 26 are joined by welding, the deformation of the valve seat 26b due to heat can be prevented.
Further, since the thickness of the cylindrical portion 61b can be set to a required thickness regardless of the thickness of the thin plate-shaped portion 61c, poor welding such as poor press-fitting or over-welding does not occur.
The valve body 26 and the nozzle plate 61 can be joined with sufficient strength.

A resin protective cap 71 having a cylindrical side wall is fixed to the end of the nozzle plate 61. This protection cap 71 is
When attaching the fuel injection valve to the intake pipe, the inner wall of the intake pipe and the fuel injection valve 1
This is for preventing the nozzle hole 16d from contacting and damaging the injection hole 16d. The inner diameter is set to be substantially equal to the outer diameter of the nozzle plate 61.

Next, the operation of the fuel injection valve 10 will be described. (1) When the power to the electromagnetic coil 32 is turned off, the needle 2
5 is urged downward in FIG. 1 by the urging force of the spring 28 together with the movable iron core 22, and the valve member 25a is seated on the valve seat 26b. Thereby, the fuel injection from the injection hole 16d is shut off. (2) When energization to the electromagnetic coil 32 is turned on, the movable iron core 2
2 is attracted to the fixed iron core 21 side against the urging force of the spring 28, so that the needle 25 is lifted. As a result, when the valve member 25a separates from the valve seat 26b, the injection hole 16d
The fuel is injected from.

In the above embodiment, the cylindrical portion of the cup-shaped nozzle plate is press-fitted into the valve body and then directly welded to the outer wall of the valve body, but the cylindrical portion of the cup-shaped nozzle plate is directed toward the fuel downstream. The present invention is also applicable to a case where the valve body is arranged and joined to the valve body via a support member welded to the cylindrical portion of the nozzle plate, or a case where a flat nozzle plate is directly welded to the fuel downstream end surface of the valve body. be able to.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 Reference Signs List 10 fuel injection valve 25a valve member 26 valve body (valve body) 26b valve seat 27a fuel passage 27b fuel passage (opening) 61 nozzle plate (injection hole member) 61a bottom 61b cylindrical portion (joining portion) 61c thin plate portion 61d injection Hole

Claims (2)

[Claims] 1. A reciprocating valve member, a fuel passage through which pressurized fuel can flow, an opening for communicating the fuel passage with the outside at an outlet side of the fuel passage, and the valve member abutting. A valve body having a valve seat for blocking conduction between the fuel passage and the opening, a joining portion joined to the valve body, and a thin plate portion thinner than the joining portion. A fuel injection valve that covers the opening so that the fuel passage and the outside can communicate with each other by a fuel injection hole formed in the fuel injection valve. 2. The fuel injection valve according to claim 1, wherein said injection hole member is formed in a bottomed cylindrical shape.