JPH07103099A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To manufacture a core without machining with the promotion of cost reduction in an electromagnetic fuel injection valve. CONSTITUTION:A magnetic circuit section (under core) 6a is manufactured by precision cold forging or machining, and a fuel passage section 6b is manufactured by drawing a pipe material. The fuel passage section 6b is press-fitted in the magnetic circuit section 6a, and these sections are seam-joined to form a core 6 having a two-piece joined structure. The core 6 is formed into a dividedly joined structure consisting of three or more members, and at least one of the members may be formed without machining. Thus since the cold forging is easy and moreover the formation of a through hole carried out by the cold forging or the machining is easy, cost reduction is possible, and since a part or the whole of the sections 6a, 6b are manufactured without machining, the trouble of valve leakage caused by chips can be prevented, and welding strain can be controlled to secure dimensional tolerance.

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 used in an electronically controlled fuel injection type internal combustion engine or the like.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an example of a conventional fuel injection valve used in an electronically controlled fuel injection type internal combustion engine. This fuel injection valve includes a valve body 1 having an opening at its tip, and a needle 2 having a conical tip is slidably mounted inside the valve body 1 so as to open and close the opening. A stopper 3 that restricts the amount of movement of the needle 2 in the opening operation direction is interposed, and a cap 4 is attached to the tip of the valve body 1. Also,
An armature 5 is connected to the rear end of the needle 2,
A core 6A is arranged on the sliding axis of the needle 2 so as to face the armature 5. A hound jig 7 is provided which forms an annular space around the core 6 and guides the armature 5 slidably. One end of the hound jig 7 holds the valve body 1 and the other end thereof. Is caulked to the flange portion of the core 6A. A spring 8 is held at the tip of the core 6A via the armature 5 to bias the needle 2 in the closing direction, and the coil bobbin 9 is held in the annular space.
A coil assembly formed by winding the electromagnetic coil 10 is disposed on the outer surface of the coil assembly, and an outer mold 11 is formed to cover the outer peripheral portion of the coil assembly. Further, O-rings 12 and 13 are inserted at both ends of the inner diameter of the coil bobbin 9. A terminal 14 is connected to the electromagnetic coil 10, and a connector mold 15 is formed so as to hold the terminal 14.

The core 6A, together with the hound jig 7 and the armature 5, constitutes a magnetic circuit around the electromagnetic coil 10. Further, the core 6A is extended so as to form a fuel passage portion, and a through hole 16A is provided in the axial direction.
A cylindrical body 17 is held at 6A, and a filter 18 is attached to the tip of the extended fuel passage portion.

By the way, the core 6A constitutes a magnetic circuit as well as a fuel passage as described above, and several methods are known as processing methods for forming a long through hole in the axial direction in the core 6A. ing.

For example, a core 6A having a structure shown in FIG. 3 is formed by cutting a cold forging material to form a through hole 16A and an external shape.

In addition, it has been tried to form the through hole of the core by precision cold forging instead of by cutting. The core 6B shown in FIG. 4 is an example of the through hole 16B formed by precision cold forging.

A core 6C having a two-divided structure as shown in FIG. 5 is also known. The core 6C is obtained by welding the flange 19 to the pipe 20.

[0008]

As shown in the example of FIG. 3, the core forming the magnetic circuit of the electromagnetic fuel injection valve and forming the fuel passage has a through hole and an external shape formed by cutting from a cold forging material. If this is the case, it is difficult to completely remove the chips after cutting the through holes, and the problem of valve leakage due to the chips becomes a problem. Further, when the through hole is formed without cutting by precision cold forging as in the example of FIG. 4, the problem of valve leakage due to chips as described above does not occur, but the through hole that is long in the axial direction is precision cooled. There is a problem of cost increase due to forging. Further, when the core of the two-divisional structure in which the flange is welded to the pipe as in the example of FIG.
Although it is possible to reduce the cost, this method has a drawback that a correction step is additionally required because the dimensional tolerance required for the magnetic circuit configuration cannot be obtained due to the distortion caused by welding.

The present invention has been made in view of the above problems, and an object thereof is to configure a magnetic circuit of an electromagnetic fuel injection valve and facilitate the formation of a core that constitutes a fuel passage. .

Another object of the present invention is to make the core non-cutting while reducing the cost.

[0011]

A fuel injection valve according to the present invention is an electromagnetic fuel injection valve having a core forming a magnetic circuit and a fuel passage, wherein the core is divided in the axial direction. It is characterized in that at least two members are joined together, and at least one of these members is formed by working without cutting, for example, precision cold forging.

[0012]

In the present invention, the core of the fuel injection valve is formed by joining at least two members divided in the axial direction, and at least one of these members is accompanied by cutting such as precision cold forging. The one formed by no processing is used.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an electromagnetic fuel injection valve according to an embodiment of the present invention. Further, FIG. 2 is a structural explanatory view of the core of the electromagnetic fuel injection valve. The fuel injection valve of this embodiment includes a valve body 1 having an opening at the tip thereof, and a needle 2 having a conical tip is slidably mounted inside the valve body 1 so as to open and close the opening. In addition, a stopper 3 for restricting the amount of movement of the needle 2 in the opening operation direction is provided, and a cap 4 is attached to the tip of the valve body 1. An armature 5 is connected to the rear end of the needle 2, and a core 6 having a two-piece joint structure is arranged on the sliding axis of the needle 2 so as to face the armature 5. And, a hound jig 7 configured to form an annular space around the core 6 and guide the armature 5 slidably is provided,
One end of the hound jig 7 holds the valve body 1, and the other end is caulked to the flange of the core 6. A spring 8 is attached to the tip of the core 6 to bias the needle 2 in the closing direction via the armature 5.
Is held, and a coil assembly formed by winding the electromagnetic coil 10 around the coil bobbin 9 is disposed in the annular space,
Exterior mold 1 so as to cover the outer peripheral portion of this coil assembly.
1 is formed. Further, O-rings 12 and 13 are inserted at both ends of the inner diameter of the coil bobbin 9. A terminal 14 is connected to the electromagnetic coil 10, and a connector mold 15 is formed so as to hold the terminal 14.

The core 6 together with the hound jig 7 and the armature 5 constitutes a magnetic circuit around the electromagnetic coil 10 and is extended so as to constitute a fuel passage, and the through hole 16 is formed in the axial direction. , The through hole 16
A cylindrical body 17 is held in the cylinder, and a filter 18 is attached to the tip of the extended fuel passage portion.

The core 6 has a two-divided joint structure as described above, and the magnetic circuit portion (under core) 6a shown in FIG. 2 (a) is manufactured by precision cold forging or cutting. The fuel passage portion 6b shown in b) is manufactured by drawing a pipe material, and the fuel passage portion 6b is press-fitted into the magnetic circuit portion 6a.
It is formed by seam bonding. FIG. 2C shows the joint structure of the core 6. Where the seam joint is
It is performed by fillet laser welding, brazing, pressure bonding, etc.

In the case of this embodiment, the magnetic circuit portion 6a is shown in FIG.
Since the through hole length is reduced to about 1/3 as compared with the conventional example, processing by precision cold forging or cutting becomes easy. Further, by forming the magnetic circuit portion 6a by precision cold forging, dimensional control of the external shape and the like can be performed without cutting. Also,
The magnetic circuit portion 6a has a shape that facilitates cold forging, and the commercially available pipe can be used for the fuel passage portion 6b, so that the cost can be reduced.

In the above embodiment, the core has a two-piece joint structure, one member (magnetic circuit portion 6a) is formed without cutting (precision forging) or cutting, and the other member (fuel passage portion 6b). ) Was achieved by cutting (drawing) to achieve partial non-cutting or complete non-cutting. However, the core has a split joining structure of three or more members, and at least one of them is used. The two members may be formed without cutting.

[0019]

The present invention is configured as described above, and since the core has the joining structure of at least two members divided in the axial direction, each member is small and the axial direction is small. Since the length is short, precision cold forging is facilitated, and through-hole formation by cutting without precision cold forging or the like is facilitated, which enables cost reduction.

Also, since some or all of the members are formed by machining such as precision cold forging without cutting, it is possible to reduce or eliminate chips, and thus to prevent valve leakage trouble. It can be prevented.

Further, since the structure is such that a plurality of members are joined to each other in the axial direction, welding distortion is less likely to occur, so that the dimensional tolerance can be secured without correction.

[Brief description of drawings]

FIG. 1 is a sectional view of an electromagnetic fuel injection valve according to an embodiment of the present invention.

FIG. 2 is a structural explanatory view of a core in the electromagnetic fuel injection valve according to the embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a conventional electromagnetic fuel injection valve.

FIG. 4 is a sectional view showing the core structure of another conventional electromagnetic fuel injection valve.

FIG. 5 is a sectional view showing the core structure of still another conventional electromagnetic fuel injection valve.

[Explanation of symbols]

 6 core 6a magnetic circuit part 6b fuel passage part 16 through hole

Claims (1)

[Claims] 1. An electromagnetic fuel injection valve having a core forming a magnetic circuit and forming a fuel passage, wherein the core has a joining structure of at least two members divided in the axial direction. A fuel injection valve, characterized in that at least one of the above is formed by machining without cutting.