JPH08284779A - Forming method for fuel distribution pipe - Google Patents

Abstract

PURPOSE: To provide cost reduction by preventing burrs from occurring at the intersecting part of a fuel passage and a branch hole, opening 'the intersecting part completely and omitting a process of removing the burrs after its forming, improve straightness accuracy of the fuel passage and achieve the light weight of a fuel distribution pipe. CONSTITUTION: A fuel distribution pipe 1 for a straight four-cylinder internal combustion engine is constructed by integrally-forming, with resin, a main part 2 provided with a fuel passage 4 whose top end is closed and four injector fitting parts 3A-3D provided with injector insertion holes 5A-5D which communicate crossing a fuel passage 4 at roughly right angles. In this construction, a taper part of a core 11 for forming the fuel passage is contact-supported from the underside by three cores 12A-12C for forming the injector insertion hole, and under such a condition as a fixed diameter part 11a of the core 11 for forming the fuel passage is inserted and held by a through hole 14 in a core 12D for forming the injector insertion hole, resin material is injected into a metallic mold to form the main part 2 and the injector fitting parts 3A-3D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a resin fuel distribution pipe used in a fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art For example, in an in-line four-cylinder internal combustion engine of an automobile, a fuel distribution pipe 31 as shown in FIG. 8 is conventionally used. The distribution pipe 31 is formed by integrally molding a main body 32 connected to a fuel tank (not shown) and four injector attachment portions 33 to which injectors (fuel injection valves, not shown) are attached with a resin material. It is a thing. A fuel passage 34 having a closed tip is formed in the main body portion 32, and an injector insertion hole 35 is formed in each injector attachment portion 33 so as to communicate with the fuel passage 34 at a substantially right angle.

When molding the fuel distribution pipe 31, the mold 3 is used.
6 (see FIG. 9), an elongated round rod-shaped core 37 for forming a fuel passage, and four short stepped rod-shaped cores 38 for forming an injector insertion hole are used. The injector insertion hole molding cores 38 are substantially the same mold parts, and the upper end surfaces of the injector insertion hole molding cores 38 contact and support the lower surface of the fuel passage molding core 37. Then, a resin material is injected into the mold 36 to integrally form the main body 32 and the injector mounting portion 33.

[0004]

However, according to the conventional molding method, the fuel passage molding core 37 is only supported in contact with the upper end surface of the injector insertion hole molding core 38. As shown in FIG. 3, the fuel passage molding core 37 floated up from the injector insertion hole molding core 38 due to the flow of the resin material, and a gap was sometimes formed between the cores 37 and 38. In addition, the fuel passage molding core 3
Since 7 is formed in a slender shape, when the length is particularly long, there is a possibility that the gap bends due to the pressure and heat of the resin over the entire length including the central portion and the gap becomes large. In such a case, the resin flows into the gap between the two cores 37 and 38 to form a thin film burr 39, and this burr 39 is used as the fuel passage 34.
There was a problem of blocking the intersection of the injector insertion hole 35 with the above. Therefore, a deburring process after molding is required, which is very troublesome and the cost is high. In addition, since the bending of the fuel passage molding core 37 occurs as described above, the straightness accuracy of the molded fuel passage 34 decreases, and it is necessary to increase the resin thickness around the fuel passage 34, that is, the main body portion 32. Yes, the weight was getting bigger.

Although it is possible to insert the tip of the fuel passage molding core 37 into the mold 36 to support it, the fuel passage 34 is molded by penetrating the end wall of the main body 32. Therefore, another problem that another component for closing the through hole is needed is brought about.

Therefore, an object of the present invention is to prevent the occurrence of burrs at the intersection of the fuel passage and the injector insertion hole, and to reliably open the intersection, thereby omitting the deburring step after molding. It is an object of the present invention to provide a method for forming a fuel distribution pipe, which can reduce the cost, improve the straightness accuracy of the fuel passage, and can also reduce the weight.

[0007]

In order to solve the above-mentioned problems, a method for forming a fuel distribution pipe according to the present invention relates to a main body portion having a fuel passage whose end is closed, and a body portion which communicates by intersecting the fuel passage. In a method of molding a resin fuel distribution pipe including a plurality of injector mounting portions having injector insertion holes, the shape of at least one or more of the injector insertion hole molding cores is inserted at the time of injection molding. The fuel passage molding core has a shape capable of holding the hole molding core and the fuel passage molding core so that no gap is formed between the core and the fuel passage molding core. It is characterized in that the core is assembled with a child, the fuel passage molding core is held by the injector insertion hole molding core, and the resin material is injected into the mold.

Here, as a means for holding the fuel passage molding core by the injector insertion hole molding core, the fuel passage molding core is inserted and held in the hole formed in the injector insertion hole molding core. On the contrary, the tip of the injector insertion hole molding core is inserted and held in the hole formed in the fuel passage molding core, and the male screw formed in the injector insertion hole molding core is formed in the fuel passage molding core. Examples thereof include those that are held by being screwed into the female screw holes formed in the child.

[0009]

According to the molding method of the present invention, since the injector insertion hole molding core holds the fuel passage molding core, the fuel passage molding core and the injector insertion hole molding core are formed during injection molding. The spaces are kept in close contact with each other with no gaps, burrs can be prevented from being generated during this time, and the intersection between the fuel passage and the injector insertion hole can be surely opened. Further, by the holding, the core for forming the fuel passage is less likely to bend even when subjected to the pressure and heat of the resin, so that the straightness accuracy of the formed fuel passage is improved and the resin thickness around the fuel passage, that is, the main body portion Can be reduced, and a lightweight fuel distribution pipe can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in molding a fuel distribution pipe used in an in-line four-cylinder internal combustion engine of an automobile will be described with reference to the drawings. First, FIGS. 1 to 5 show a first embodiment, and a fuel distribution pipe 1 of the present embodiment has a main body portion 2 connected to a fuel tank and four injector attachment portions 3A, 3B, 3C to which injectors are attached. , 3D are integrally molded with a resin material.

An elongated fuel passage 4 formed of a loose taper hole is formed in the main body portion 2 except for a constant diameter portion 4a at the tip,
The end surface of the constant diameter portion 4 a is closed by the end wall of the main body portion 2. The injector mounting portions 3A to 3D are provided with four injector insertion holes 5A to 5D which intersect and communicate with the fuel passage 4 at a substantially right angle, and only the injector insertion hole 5D of the most advanced injector mounting portion 3D is provided in the fuel passage. It is formed to be longer than the constant diameter portion 4a of No. 4 so as to project upward.

Next, a method of forming the fuel distribution pipe 1 having the above-mentioned structure will be described. As shown in FIGS. 1, 3, 4 and 5, when molding the fuel distribution pipe 1, a mold 10 for molding the outer surfaces of the main body 2 and the injector mounting portions 3A to 3D, and the fuel passage 4 are formed. An elongated tapered rod-shaped fuel passage molding core 11 for molding and four short stepped rod-shaped injector insertion hole molding cores 12A to 12D for molding the injector insertion holes 5A to 5D are used.

A constant diameter portion 11a is provided at the tip of the fuel passage molding core 11. A curved surface 13 that comes into contact with the outer surface of the fuel passage molding core 11 is provided on the tip surfaces of the three injector insertion hole molding cores 12A to 12C on the base end side and the intermediate portion.
Is provided. The core 12D for forming the injector insertion hole on the leading edge side is the other core 12 for forming the injector insertion hole.
A through hole 14 is formed to be longer than A to 12C, and the constant diameter portion 11a of the fuel passage molding core 11 is inserted into the upper end portion of the side surface thereof.

The fuel passage molding core 11 and the injector insertion hole molding cores 12A to 12D are assembled in the mold 10 in a state of intersecting each other at a substantially right angle. At this time, the fuel passage molding core 11 has three injector insertion hole molding cores 12A to 12C in the tapered portion.
3 is not only contact-supported from below by the curved surface 13 (see FIG. 3), but also is inserted and held in the through hole 14 of the injector insertion hole molding core 12D at the constant diameter portion 11a and is restrained in the entire radial direction. Therefore (see FIGS. 4 and 5), the fuel passage molding core 11 is the injector insertion hole molding core 1.
It is held so as not to cause a gap during injection molding with respect to 2D, and also with respect to the other injector insertion hole molding cores 12A to 12C. Then, in this state, the resin material is injected into the cavity 10a from the gate (not shown) in the upper portion of the mold 10, and the main body 2 and the injector mounting portion 3
A to 3D are integrally molded.

As described above, according to the molding method of this embodiment, since the injector insertion hole molding core 12D holds the fuel passage molding core 11, the fuel passage molding core 11 and the injector are injected during injection molding. Insert hole forming core 12A ~
12D is maintained in a close contact state with no gap, burrs can be prevented from occurring during this time, and the intersection of the fuel passage 4 and the injector insertion holes 5A to 5D can be reliably opened. Therefore, it becomes possible to omit the deburring step in this portion, and the cost can be reduced. In addition, by the bond,
Since the fuel passage molding core 11 is less likely to bend even when subjected to resin pressure and heat, the straightness accuracy of the fuel passage 4 to be molded is improved and the resin thickness around the fuel passage 4, that is, the body portion 2 is reduced. Therefore, the fuel distribution pipe 1 having a light weight can be obtained.

Further, only the injector insertion hole forming core 12D and the fuel passage forming core 11 on the side where the tip is closed are assembled, and the other injector insertion hole forming cores 1 are assembled.
Since 2A to 12C and the fuel passage molding core 11 only contact and support them, burrs can be prevented from occurring and the assembling work can be easily performed.

It should be noted that any one of the injector insertion hole forming cores 12A to 12C other than the above 12D or two or more of the injector insertion hole forming cores 12A to 12D are lengthened upward as described above. It is also possible to form the through hole 14 and to hold the fuel passage molding core 11 by the injector insertion hole molding core. in this case,
Any one of the injector insertion holes 5A to 5C other than the 5D or two or more of the injector insertion holes 5A to 5D are formed to be elongated upward as described above.

Next, FIG. 6 shows a second embodiment. This embodiment differs from the first embodiment only in the holding means for the fuel passage molding core 11 by the injector insertion hole molding core 12D. Is. Here, the fuel passage molding core 1
1, a projection 16 thinner than the core 11 is provided, and a hole 17 into which the projection 16 is fitted is recessed at the upper end portion of the side surface of the injector insertion hole molding core 12D. Hold the service core 11. The injector insertion hole 5D is formed longer than the fuel passage 4 as in the first embodiment. Also in this embodiment, the same effect as that of the first embodiment can be obtained.

Next, FIG. 7 shows a third embodiment. This embodiment also differs from the first embodiment only in the holding means for the fuel passage molding core 11 by the injector insertion hole molding core 12D. Is. Here, the fuel passage molding core 1
1 has a hole 18 recessed in the lower surface of the tip end thereof, and a projection 1 fitted in the hole 18 at the upper end of the injector insertion hole molding core 12D.
9 is provided, and by this fitting, the fuel passage molding core 1 is provided.
Holds 1. According to the present embodiment, even if the fuel passage molding core 11 is slightly lifted up, no gap is formed in the connection portion with the injector insertion hole molding core 12D, so that it is substantially the same as in the first embodiment. The effect is obtained. In addition,
In this third embodiment, the protrusion 19 is provided with a male screw and the hole 18
It is also possible to provide female threads on each of them and screw the injector insertion hole forming core 12D into the fuel passage forming core 11 to more firmly connect both cores 11 and 12D.

[0020]

As described in detail above, according to the method for forming a fuel distribution pipe of the present invention, burrs are prevented from being generated at the intersection between the fuel passage and the injector insertion hole, and the intersection is ensured. It has an excellent effect that it can be opened, the burr removing step after molding can be omitted, the cost can be reduced, the straightness accuracy of the fuel passage can be improved, and the weight can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fuel distribution pipe and a molding method thereof according to a first embodiment of the present invention.

FIG. 2 is a plan view of the fuel distribution pipe.

FIG. 3 is a cross-sectional view showing the same molding method.

FIG. 4 is a cross-sectional view showing the same molding method.

5 is a V- of FIG. 4 showing an example of holding a fuel passage molding core;
It is a V line sectional view.

FIG. 6 is a cross-sectional view showing the molding method of the second embodiment.

FIG. 7 is a cross-sectional view showing the molding method of the third embodiment.

FIG. 8 is a cross-sectional view of a fuel distribution pipe molded by a conventional molding method.

FIG. 9 is a cross-sectional view showing the same molding method.

[Explanation of symbols]

 1 Fuel Distribution Pipe 2 Main Body 3A to 3D Injector Mounting Part 4 Fuel Passage 5A to 5D Injector Insertion Hole 10 Mold 11 Fuel Passage Molding Core 12A to 12D Injector Insertion Hole Molding Core 14 Through Hole 16 Projection 17 Hole 18 Hole 19 protrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keisou Takeda 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Susumu Kojima 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (1)

[Claims] 1. A method of molding a fuel distribution pipe made of resin, comprising: a main body portion having a fuel passage with a closed end; and a plurality of injector mounting portions having injector insertion holes that intersect and communicate with the fuel passage. In at least one or more of the injector insertion hole forming cores, the shape of the fuel passage forming core is formed so that no gap is formed between the injector inserting hole forming core and the fuel passage forming core during injection molding. A shape capable of holding a core for injection molding, by assembling the injector insertion hole forming core and the fuel passage forming core in a mold, and holding the fuel passage forming core by the injector insertion hole forming core, A method for molding a fuel distribution pipe, which comprises injecting a resin material into the mold.