JP2003194280A - Connecting structure between fuel tube and tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure between a fuel tube and a tank, capable of directly welding a resinous tube and a tank without using another member for welding. <P>SOLUTION: In this connecting structure between a fuel tube and a tank, a multi-layer resinous fuel tube 12A, and a multi-layer resinous fuel tank 16A having an outermost layer 26a formed by same resinous material as an outermost layer of the fuel tube 12A are directly welded with each other. A welding side end portion of the fuel tube is gradually increased in diameter toward a tube tip end, and formed in a flange shape. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure between a fuel tube and a tank. More specifically, the present invention relates to a fuel tube-tank connection structure in which a fuel tube and a fuel tank are directly welded to each other.

In the present invention, examples of the fuel applicable to fill the fuel tank include various vehicle fuels such as gasoline, alcohol-added gasoline (gasohol), light oil, and LPG.

[0003]

2. Description of the Related Art In connection between a resin fuel tube and a resin fuel tank, characteristics such as securing joint strength and preventing fuel leakage are required.

As a conventional connection structure between a fuel tube and a tank, for example, as described in Japanese Patent Laid-Open No. 6-270701, the fuel tube 12 is provided with a welding part 14a,
14b (resin joint or the like) is press-fitted to attach the welding component 14
The structure in which a and 14b and the wall surface of the fuel tank 16 are joined by welding is common (see FIG. 1).

In FIG. 1, reference numeral 13 is a retaining rib for securing the joint strength between the fuel tube 12 and the welding component 14a.

However, since the conventional connecting structure uses the welding parts 14a and 14b, the space between the fuel tube 12 and the welding part 14a and the welding part 14b-the fuel tank 1 are used.
Between 6 and 2, there will be two joints. Therefore, there is a problem in that the reliability of the connecting portion is lower than in the case where there is only one joining portion, and the manufacturing process is complicated and the cost is high.

Further, the fuel tube 12-the welding component 14
The portions a were connected by press fitting as described above. Generally, press-fitting is inferior to welding in terms of joint strength,
Further, since the press-fitting work requires labor, it has been desired to provide a joining method that does not require the press-fitting work.

[0008]

SUMMARY OF THE INVENTION In view of the above, the present invention is capable of directly welding between a resin tube and a tank without using a separate member for welding. It is an object of the present invention to provide a fuel tube-tank connection structure that is also highly expensive.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present inventors have
Focusing on the shape of the resin fuel tube, the inventors conceived a connection structure between the fuel tube and the tank having the following configuration.

The fuel tube-tank connection structure of the present invention has a multilayer resin fuel tube having a multilayer resin fuel tube and an outermost layer formed of a resin material of the same quality as the outermost layer of the fuel tube. It is characterized in that it is directly welded to a tank, and the welding side end portion of the fuel tube has a flange shape that expands in diameter as it approaches the tip of the tube. Since the welding surfaces on the tube side and the tank side are made of the same resin material, the welding strength is high.

Further, by adopting the above-mentioned flange shape, the bending rigidity of the welding side end portion of the fuel tube is improved.
Therefore, the welded end of the fuel tube is less likely to be deformed, and the reliability of connection is increased.

In the above construction, it is desirable that the tank-side welding surface in welding and the vicinity thereof be thick-walled. This is because, during welding, pressure is usually applied in a direction perpendicular to the welding surface. By forming the welding surface on the tank side and the vicinity thereof with a thick wall, the rigidity of the thick wall portion is improved and the outer wall portion of the fuel tank is less likely to be deformed during welding.

In the above structure, a two-layer fuel tube having a barrier layer and an outermost layer can be preferably used as the fuel tube. In particular, the barrier layer is E
It is desirable that the VOH and the outermost layer are formed of a material mainly containing HDPE from the viewpoint of fuel permeation resistance, moldability, and the like.

In the above construction, it is desirable that the tube-side welding surface in welding is composed of only the outermost layer of the fuel tube, and the tank-side welding surface is composed of only the outermost layer of the fuel tank. The welded interface is melted and integrated to further secure the bonding strength.

Further, it is desirable that the outermost layer of the fuel tank is formed of a material mainly containing HDPE, like the above fuel tube.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the present specification, “%”, “parts” and the like indicating the blending amount are based on mass unless otherwise specified.

First, FIG. 2 shows a schematic view of a half section of a connecting portion between the fuel tube and the tank of the present invention. In the following description, a resin tube having a two-layer structure as the fuel tube and a resin tank having a six-layer structure as the fuel tank will be described as an example, but the fuel tube and the fuel tank of the present invention are The present invention is not limited to the structure only, and can be applied to other general multi-layer resin fuel tubes and resin fuel tanks.

The connection structure between the fuel tube and the tank of the present invention is a multilayer structure having a resin fuel tube 12A having a multilayer structure and an outermost layer 26a made of the same resin material as the outermost layer 22a of the fuel tube 12A. The basic feature is that the resin fuel tank 16A is directly welded.

In the above description, the outermost layer 22a of the fuel tube 12A and the outermost layer 26a of the fuel tank 16A are formed of the same resin material so that the fuel tube 12A and the fuel tank 16A, the welding parts 14a, 14b, etc. This is to secure the welding strength when directly welding without using. That is, as will be described later, since the welding interface W is made of the same resin material, the welding strength can be improved.

Here, the same resin material means that the outermost layer 22a of the fuel tube 12A is made of a polyolefin (P
When it is O), it means that the outermost layer 26a of the fuel tank 16A is also made of polyolefin. of course,
Outermost layer 22a of fuel tube 12A and fuel tank 16A
The resin forming the outermost layer 26a may be the same.
Usually, the outermost layer of the fuel tube and the fuel tank is a protective layer, and therefore, polyolefin type, polyamide type, etc. are often used.

Further, the welding side end of the fuel tube 12A is characterized in that the diameter is increased toward the tip of the tube to form a flange shape. By forming the tube tip into a flange shape, the bending rigidity of the welding side end portion of the fuel tube 12A is improved, so that the welding side end portion of the fuel tube 12A is less likely to be deformed, and the reliability of the connection portion is increased.

The flange shape of the welding side end of the fuel tube 12A is not particularly limited as long as it can be directly welded to the fuel tank 16A. For example, the shape conventionally used as a welding part can be used. Can be applied.

FIG. 3 shows an example of the connecting structure between the fuel tube and the tank of the present invention. FIG. 3 is an enlarged cross-sectional view showing the welding interface W in FIG. 2, in which both the outer diameter and the inner diameter are R ₃ and r ₃ as the welding-side end of the fuel tube 12A approaches the tube tip (left in the figure). It is a flange shape in which the diameter is gradually increased to the position of, and the tube tip is made thicker and bent inward.

Here, as the fuel tube 12A, a two-layer fuel tube is illustrated. In the fuel tube 12A having the above structure, the inner layer 22b is generally a barrier layer and the outermost layer 22a is a protective layer.

Barrier layer 22b of the fuel tube 12A
Is formed to give the fuel tube a fuel permeation resistance. Resin materials that can be used include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (CTFE), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-polychlorotrifluoroethylene. Fluoroethylene copolymer (ECTFE), hexafluoropropylene-tetrafluoroethylene copolymer (F
EP), fluorine-based resins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-vinyl alcohol copolymer (EVO)
H), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and others, THV (Sumitomo 3M: fluorine elastomer), PBN (Advance: boron nitride plastic), and their blends and copolymers. , Modified products and the like can be used.

The protective layer 2 for the fuel tube 12A is also provided.
2a is formed to give durability to the fuel tube. Resin materials that can be used include nylon 6, nylon 66, nylon 610, nylon 61
2, aliphatic polyamides such as nylon 11 and nylon 12, high density polyethylene (HDPE), polyolefins such as polypropylene, and blends, copolymers and modified products thereof can be used.

Particularly, of the above, the barrier layer 22b is the EVO.
It is desirable that H and the outermost layer 22a are formed of a material mainly containing HDPE from the viewpoint of fuel permeation resistance, moldability, adhesion between both layers, and the like.

The EVOH is a crystalline polymer obtained by saponifying and hydrolyzing an ethylene-vinyl acetate copolymer (EVAC) obtained by copolymerizing ethylene and vinyl acetate. The gas barrier property shows the highest level among various plastics. The ethylene copolymerization ratio is usually 30 to 40.
%, The higher the ethylene content, the lower the melting point,
The gas barrier property is lowered and the flexural modulus is reduced.

In particular, it has excellent barrier properties against alcohol-added gasoline, so-called "gasohol", and is widely used as a material for fuel tubes.

A specific EVOH material is available from Kuraray Co., Ltd. in "Eval EP-F101 / H101".
・ The products on the market such as "E105" can be used.

The above HDPE is also a material widely used in the field of fuel system parts. Good impact resistance, heat resistance, fuel resistance, inexpensive and easy to mold,
It is useful as a protective layer.

By using the above HDPE modified with a dicarboxylic acid or the like, the melt adhesion with the barrier layer 22b made of the EVOH is remarkably improved. Also,
The outermost layer 22a and the barrier layer 22b may each contain a general-purpose additive or other polymer.

When the above EVOH and HDPE are used, the wall thickness of the fuel tube 12A is, for example, the outermost layer 22a: about 0.7 to 0.8 mm, and the barrier layer 22b: about 0.2 to 0.3 mm. be able to. Barrier layer 22
If b is too thick, the flexibility of the fuel tube 12A tends to occur, and if it is too thin, the barrier property is deteriorated.

In the present embodiment, the tube-side welding surface in welding is composed of only the outermost layer 22a of the fuel tube 12A, and the tank-side welding surface is composed of only the outermost layer 26a of the fuel tank 16A. . This configuration is desirable in terms of strength because the welding interface W is melted and integrated to further improve the welding strength.

The fuel tube 12A has an outermost layer 22a.
And the barrier layer 22b can be co-extruded and directly melt-bonded to be molded. The molding can be performed by corrugation (concavo-convex) molding using a general-purpose extrusion molding machine. The thick portion at the tip of the fuel tube 12A can be formed by controlling the amount of resin discharged from the extruder. The tube tip may be bent inward so that the barrier layer 22b does not contribute to the welding surface.

In addition, when the barrier layer 22b and the outermost layer 22a are formed by combining the resins having high adhesion (welding) strength with each other, the welding strength of both layers increases, and delamination hardly occurs. It is also possible to form the fuel tube 12A into a bellows (see FIG. 2). The bellows shape improves the flexibility of the fuel tube 12A in terms of shape. The bellows-shaped fuel tube 12A can be manufactured by general-purpose continuous bellows molding extrusion.

On the other hand, as the fuel tank 16A, a resin tank having a six-layer structure is illustrated. In the fuel tank having the structure, the outer surface protective layer 26 is provided from the outermost layer side (right side in the figure).
a, regrind layer 26b (protective layer using recycled material), adhesive layer 26c, barrier layer 26d, adhesive layer 26c,
The inner protective layer 26e laminated in this order is currently used.

Protective layers for the fuel tank 16A (outer surface protective layer 26a, regrind layer 26b, inner surface protective layer 26e)
Is formed for the same purpose as the protective layer 22a of the fuel tube 12A, and usable materials and the like are similar to those of the fuel tube. However, the material of the outermost layer 26a is selected from the same resin as the material of the outermost layer 22a of the fuel tube 12A.

Further, the reason why the regrind layer 26b is provided is from the viewpoint of recent environmental problems and cost reduction.
Examples of the reclaimed material forming the regrind layer 26b include defective molding products generated by injection molding, extrusion, blow molding, and the like.
Crushed or crushed scraps such as runners, nozzles and parisons can be used. These can be used by being mixed with an unmolded raw material or compound in an appropriate amount.

The barrier layer 26d of the fuel tank 16A is also formed for the same purpose as the barrier layer 22b of the fuel tube 12A, and the usable materials and the like are similar to those of the fuel tube.

The adhesive layer 26c is formed between the regrind layer 26b and the barrier layer 26d and between the barrier layer 26d and the inner surface protective layer 26e, and is for the purpose of adhering both layers. Examples of usable materials include thermoplastic resins in which an adhesive functional group is introduced into polyethylene.

If the resins having high welding strength are combined to form the barrier layer and the protective layer, it is not necessary to provide the adhesive layer 26c.

Particularly, of the above, the barrier layer 26d is the EVO.
H, protective layer (external protective layer 26a, regrind layer 26b
It is desirable that the inner protective layer 26e) is made of a material mainly composed of HDPE in terms of fuel permeation resistance, moldability, and the like.

In the above construction, it is desirable that the tank-side welding surface in welding and the vicinity thereof be thick-walled. This is because, during welding, pressure is normally applied to the welding interface W in the vertical direction. By forming the welding surface on the tank side and its vicinity thickly, the rigidity of the thick portion is improved and the outer wall portion of the fuel tank 16A is less likely to be deformed during welding.

The fuel tank 16A can be molded by a general blow molding method (hollow molding method).

The welding conditions for the fuel tube 12A and the fuel tank 16A differ depending on the resin material used, but when the outermost fuel tube layer 22a and the outermost fuel tank layer 26a are formed of HDPE, the temperature is usually:
About 140-190 ℃, desirably about 160 ℃, about 1mi
It can be n. For the welding, a general internal heating means such as a high-frequency welder and ultrasonic waves can be used.

Next, an example in which the welding side end of the fuel tube is formed into another shape will be described. 4 is an enlarged cross-sectional view showing the welding interface W, like FIG. The difference from FIG. 3 is that the barrier layer 22b of the fuel tube 12B is projected beyond the welding interface W to the fuel tank 16B side (in the figure, the left side of the welding interface W). With the above configuration, the fuel tube 1
The fuel permeation resistance at the welding side end of 2B becomes more reliable.

At this time, the outermost layer 26a of the fuel tank 16B
In addition, a cutout portion K through which the barrier layer 22b of the fuel tube 12B can project is provided. This is configured such that the fuel tube 12B and the outermost layer 26a of the fuel tank 16B are easily welded to each other at the welding interface W, but the notch is not essential.

With the above structure, the outermost layers between the tube and the tank can be welded to each other, and good welding strength can be maintained.

Next, another example in which the welding side end of the fuel tube is formed into another shape will be shown. 5 is the same as FIG.
It is an expanded sectional view which shows the welding interface W. The difference from Fig. 4 is that
As the welding side end of the fuel tube 12C is gradually expanded to the position of R ₅ as it approaches the tube tip (left direction in the figure), the inner diameter is r ₅ and the flange shape is constant. , The barrier layer 22b of the fuel tube 12C
That is, the end is on the welding interface W.

Even with the above structure, good joint strength with the fuel tank 16A can be secured as in the fuel tube shown in FIGS. Further, the welding interface at the end portion of the fuel tube 12C can be formed only by cutting in the direction perpendicular to the tube axis, so that the welding surface can be formed more easily than bending or the like.

Next, another example in which the welding side end of the fuel tube is formed into another shape will be shown. FIG. 6 shows FIG.
It is an expanded sectional view which shows the welding interface W like 4 and 5.
3 and 4, the fuel tube 12D is bellows-formed to near the tube tip (in the figure, leftward) to form a diametrically expanded portion, and the tube tip is connected to the fuel tank 16
That is, it was inserted into the tube insertion hole of A.

In FIG. 6, the tip of the fuel tube 12D is deeply inserted into the tube insertion hole beyond the inner protective layer 26e of the fuel tank 16A (to the left in the figure), but the length of the insertion portion is long. Need not reach the inner surface protective layer 26e. That is, the tip of the fuel tube may be between the outer surface protective layer 26a and the inner surface protective layer 26e.

Further, although the fuel tube 12D is formed in a bellows shape with a constant thickness up to the tube tip, the tube tip side is made thicker in order to reduce deformation on the tube end side. Good.

Even with the above structure, good joint strength with the fuel tank 16A can be ensured as in the fuel tube shown in FIGS. Further, since the structure can be formed only by the continuous bellows molding extrusion including the expanded diameter portion, the cost is low. Further, not only the outer surface of the fuel tank 16A is welded but also the resin protruding by the welding is welded not only on the inner peripheral side of the mounting hole, but the fuel tube 12D is firmly fixed to the fuel tank 16A.

As described above, the present invention makes it possible to directly weld the fuel tube and the fuel tank, which has been difficult in the conventional structure because the fuel tube has the illustrated shape. .

[0057]

According to the present invention, the fuel tube is directly welded to the fuel tank by forming the shape of the fuel tube as described above. Therefore, the number of parts can be reduced as compared with the conventional one.

Furthermore, the joining by press-fitting, which has been used conventionally, is unnecessary, the joining strength is improved, and the manufacturing process is reduced and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a connection portion between a conventional fuel tube and a tank.

FIG. 2 is a schematic view of a half section of a connection portion between a fuel tube and a tank of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a welding surface in FIG.

FIG. 4 is an enlarged cross-sectional view showing a welding surface when the fuel tube has another shape.

FIG. 5 is an enlarged cross-sectional view showing a welding surface when the fuel tube has another shape.

FIG. 6 is an enlarged cross-sectional view showing a welding surface when the fuel tube has another shape.

[Explanation of symbols]

12, 12A, 12B, 12C, 12D: Fuel tube 16: Fuel tank 22a: Outermost layer of fuel tube (protective layer) 22b: Inner layer of fuel tube (barrier layer) 26a: Outermost layer of fuel tank (outer surface protective layer) 26d: Fuel tank barrier layer

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29L 23:00 F16L 41/02 Z (72) Inventor Mitsutaka Kondo 1 Ochiai, Nagahata, Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi prefecture Toyoda Gosei Co., Ltd. (72) Inventor Daisuke Tsutsumi No. 1 Nagahata, Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture F-term (Reference) 3D038 CA05 CA15 CB01 CC17 CC20 3H019 DA07 4F211 AD05 AD12 AD20 AD25 AG24 AH55 TA01 TC08 TD07 TD20 TH18 TN14

Claims (6)

[Claims] 1. A fuel obtained by directly welding a multilayer resin fuel tube and a multilayer resin fuel tank having an outermost layer formed of the same resin material as the outermost layer of the fuel tube. In the tube-tank connection structure, the welding side end of the fuel tube has a flange shape that expands in diameter toward the tip of the tube, and has a flange shape. 2. The tank-side welding surface and the vicinity thereof in the welding are thick-walled.
Connection structure between the fuel tube and tank described. 3. The fuel tube-tank connection structure according to claim 1, wherein the fuel tube has a two-layer structure including a barrier layer and an outermost layer. 4. The connection structure between a fuel tube and a tank according to claim 3, wherein the barrier layer is made of EVOH and the outermost layer is made of a material mainly containing HDPE. 5. The tube-side welding surface in the welding,
The fuel tube-tank according to claim 1, 2, 3 or 4, wherein only the outermost layer of the fuel tube is formed, and the tank-side welding surface is formed only by the outermost layer of the fuel tank. Connection structure between. 6. The connection structure between a fuel tube and a tank according to claim 1, wherein the outermost layer of the fuel tank is formed of a material mainly containing HDPE. .