JP2002192963A - Structure of the joint part of the child parts to the synthetic resin fuel tank - Google Patents

Abstract

(57) [Problem] To provide a structure of a joint part of a child part of a synthetic resin tank configured to ensure a sufficient welding strength. SOLUTION: At least a surface layer of a synthetic resin fuel tank made of an easily weldable material is welded to a fuel tank at a portion where a child part having a main part made of an easily welded material and a covering part made of a gasoline barrier material is joined. In order to bring the main part into contact with the heater before the covering part during the step of heating the child component with the heater, a step is provided between the main part and the end face of the covering part facing the heater. As a result, the welding of the easily welded material portion does not have to be hindered by the gasoline barrier material portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a part for connecting a child component to an outer surface of a synthetic resin fuel tank by heat welding.

[0002]

2. Description of the Related Art Since rust prevention and weight reduction are easy and high productivity is obtained, the tendency to use a fuel tank formed by blow molding a synthetic resin material has recently been increasing.

Incidentally, high-density polyethylene (hereinafter, HDPE) generally used for blow molding is a hydrocarbon (H
Since C) has low impermeability (gasoline barrier property), it is not suitable for use in a gasoline tank as it is from the viewpoint of preventing air pollution.

In order to suppress the permeation of HC, it is preferable to use a material having a high gasoline barrier property such as an ethylene vinyl alcohol copolymer (hereinafter referred to as EVOH), but such a so-called gasoline barrier material is relatively expensive. In addition, since the impact resistance is insufficient, it is difficult to say that forming the entire tank with a gasoline barrier material is realistic in terms of manufacturing cost and strength.

On the other hand, a blow-molded fuel tank includes:
Generally, a separately molded child part such as a filler neck or a vent valve is heat-welded.However, since the gasoline barrier material as described above has low adhesion by heat welding, if the child part is formed of a gasoline barrier material, , Mounting on the fuel tank tends to be troublesome.

In order to deal with such inconveniences, HD
The fuel tank is formed of a film-like gasoline barrier sandwiched with a material that is relatively easy to weld (easily weldable) such as PE, and only the welded parts of the child parts formed of the gasoline barrier Have already been proposed in which two-color molding is performed with an easily weldable material, or a child component formed of the easily weldable material is covered with a gasoline barrier material.

[0007]

However, according to the structure in which the child parts formed of the easily welded material are covered with the gasoline barrier material, only the welding surface of the easily welded material in the child parts before welding is simply exposed. In this case, the end face of the easily welded material and the end face of the gasoline barrier material are aligned on the joint surface of the child component to the fuel tank, so that the gasoline barrier material layer that does not fuse with the fuel tank during heat welding interferes, and Bond strength may be insufficient.

The present invention has been devised to solve such problems of the prior art, and its main object is to provide a sufficient welding strength to a synthetic resin fuel tank without impairing gasoline barrier properties. It is an object of the present invention to provide a child component configured to ensure the above.

[0009]

In order to achieve such an object, the invention according to claim 1 of the present application is directed to a fuel tank made of synthetic resin whose surface layer is made of an easily welded material. And at the part where the child part having the coating part made of gasoline barrier material is joined, in order to bring the main part into contact with the heater prior to the coating part during the step of heating the child part with the heater for welding to the fuel tank, A step is provided between the end portions of the main portion and the coating portion facing the heater.

In this case, since the easily welded materials are welded to each other, a sufficient bonding strength can be ensured, and the easily weldable portions can be fused together without being hindered by the gasoline barrier material layer. .

In the invention of claim 2 of the present application, the size of the step is determined in accordance with the melting allowance at the time of welding the main part. Thus, the end surface of the coating portion of the gasoline barrier material comes into contact with the outer surface of the fuel tank when the portion of the easily welded material is welded to the fuel tank.

According to the invention of claim 3 of the present application, a child component having a main portion made of an easily welded material and a covering portion made of a gasoline barrier material is connected to a synthetic resin fuel tank having at least a surface layer made of an easily welded material. The structure of the portion to be formed is such that guide means for preventing the softened coating portion from flowing into the main portion during welding is provided at a portion of the main portion in contact with the fuel tank adjacent to the coating portion.

With this configuration, the gasoline barrier material layer is prevented from flowing into the welded portion between the easily welded materials, so that sufficient bonding strength can be ensured.

Further, according to the invention of claim 4 of the present application, the child component is formed of an anchor base of a fastener means that can be repeatedly attached and detached. Thereby, the functional part of the child component connected to the synthetic resin fuel tank can be configured to be repeatedly detachable, so that the maintainability can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a mounting portion of a vent valve 1 to a fuel tank 2 as one application example of the present invention. The fuel tank 2 has, for example, HDP
It is formed by blow molding using an easily weldable material such as E, and a mounting hole 3 of the vent valve 1 is formed on an upper wall thereof.

The vent valve 1 is normally opened to allow the evaporative gas on the liquid surface to escape to a canister (not shown) provided outside, and that the fuel in the tank rises to a predetermined liquid level when the liquid surface swings. This is to prevent the fuel from flowing out to the passage to the canister when it is closed, and is fixed to the upper wall of the fuel tank 2 with a part thereof inserted into the tank. The structure is not different from that of a known vent valve, and the description is omitted here.

The vent valve 1 has a valve function section 4 made of a material having high oil resistance such as polyacetal.
And a support member 5 formed of an easily weldable material such as HDPE capable of being welded to the fuel tank 2.

A flange 6 is formed on the upper part of the valve function part 4 to be in contact with the outer surface of the upper wall of the fuel tank 2.

The support 5 has a disk shape in contact with the outer surface of the upper wall of the fuel tank 2 and has a hose port 7 connected to the canister on the upper surface thereof. This support part 5
Is almost completely exposed to the atmosphere outside the tank.
Coating layer 5s made of gasoline barrier material such as VOH
Are integrally formed by, for example, two-color molding. A recess 8 is formed on the surface facing the fuel tank 2 so as to be able to receive the portion of the valve function portion 4 above the flange 6 in a substantially tight manner, and the outer peripheral edge 9 of the recess 8 is formed on the outer surface of the fuel tank 2. It is designed to be welded by heating.

According to this, the support 5 and the fuel tank 2
In a state where the flange 6 of the valve function part 4 is sandwiched between the opposing surfaces with the upper wall, the lower surface of the outer peripheral edge 9 protruding so as to surround the recess 8 is heated and melted and pressed against the fuel tank 2. A known heating welding method (Japanese Patent Application No. 11-1266)
No. 39), the support portion 5
Are welded to the fuel tank 2, and the valve function unit 4 is fixed to the fuel tank 2 via the support 5.

Here, the lower end surface of the outer peripheral edge 9 of the support 5 before welding to the fuel tank 2 and the coating layer 5s
A step is provided between the lower end surface of FIG. The step size A is such that the lower surface of the outer peripheral edge 9 is
It is set so as to conform to the melting margin of the lower surface of the outer peripheral edge portion 9 when heated and pressed against the fuel tank 2, and when the dimension A is increased, the bonding strength can be satisfied. Since a gap is formed between the lower end surface of the coating layer 5s and the outer surface of the fuel tank 2 and the gasoline barrier property is reduced, the outer peripheral edge 9 made of an easily welded material is welded to the outer surface of the fuel tank 2 and then the fuel is removed. It is most preferable to set the dimension A so that the lower end surface of the coating layer 5s abuts on the outer surface of the tank 2. As a matter of fact, considering the manufacturing error and the variation of the melting allowance,
It is difficult to match the welding of the outer peripheral edge 9 with the close contact of the end face of the coating layer 5s, but a step is provided such that the outer peripheral edge 9 contacts the heater H slightly earlier than the lower end face of the coating layer 5s. It has been experimentally confirmed that the interference of the coating layer 5s with the welding interface does not affect the welding strength.

The structure in which the outer peripheral edge 9 protrudes from the end face of the coating layer 5s is, in short, when the support member 5 before welding is set on the heater H, the outer peripheral edge 9 is located ahead of the coating layer 5s. It suffices to contact the heater H. For example, as shown in FIG. 3, the end face of the outer peripheral edge 9 is formed in a round shape in which the center is convex, or as shown in FIG. Is also good.

In this way, by forming the coating layer 5s provided on the support portion 5 from a gasoline barrier material and by retracting the coating layer 5s so as not to interfere with the welding of the outer peripheral edge 9, the required bonding strength is obtained. Is satisfied, and after welding, the portion made of the gasoline barrier material reaches the welding interface with the fuel tank 2 so that the contact area of the easily welded material portion in the support portion 5 with the atmosphere outside the tank is substantially eliminated, The gasoline barrier property (HC permeation suppression property) required for the child component is satisfied.

FIG. 5 shows a second embodiment of the present invention. In this case, the covering portion 5 on the contact surface of the outer peripheral edge 9 of the support portion 5 made of an easily weldable material with the heater H
An annular groove 11 into which the molten easy-to-weld material portion flows is provided in a portion near s. The effective welding width dimension B of the outer peripheral edge portion 9 is determined so as to have a sufficient area for securing the welding strength.

According to this, when the support portion 5 is pressed against the fuel tank 2 in a state where the coating portion 5s is softened by contact with the heater H, the welding interface between the easily welded material portion and the fuel tank 2 is softened. The penetration of the covered portion 5 s is prevented by the pressure at which the molten easily welded portion flows into the annular groove 11. This prevents the gasoline barrier material layer from interfering with the welding of the easily welded material layer to the fuel tank 2.

FIG. 6 shows a third embodiment of the present invention. In this case, the support portion 5 as a child component directly welded to the fuel tank 2 has an annular shape, and a nut 12 is inserted on a common circumference. A coating layer 5s of a gasoline barrier material is formed on the inner peripheral surface.

Also in this case, by providing the steps shown in FIGS. 2 to 4 on the welding surface with the fuel tank 2 or by providing the annular groove 11 shown in FIG. The strength is not hindered by the gasoline barrier material layer.

In this case, the valve function part 4 is made of a gasoline barrier material, and the bolt 13 is screwed to the insert nut 12 through the flange part 6 so that the valve function part 4 is attached to the support part 5. Since it is fixed, the valve function unit 4 can be freely attached and detached.

The coating layer 5s is only required to be able to prevent the vaporized gasoline from leaking into the atmosphere. Therefore, the coating layer 5s is in contact with the atmosphere as shown in FIG. 1 and the fuel tank as shown in FIG. It may be provided on any side of the surface in contact with the inside atmosphere, and may be formed on the surface where the highest gasoline barrier effect is obtained according to the form of the child component.

[0031]

As described above, according to the first aspect of the present invention,
According to the configuration of the above, the position of the end face of the portion formed of the gasoline barrier material in the child component facing the heater is retracted from the protruding end of the portion formed of the easily welded material, so that the welding of the easily welded material portion is prevented. , Without being hindered by the gasoline barrier material layer. Therefore, according to the present invention, a great effect can be obtained in sufficiently welding the easy-to-weld material layer to the fuel tank to secure high bonding strength.

According to the second aspect of the present invention, the size of the step is determined in accordance with the melting allowance at the time of welding of the easily welded material portion, so that the gasoline barrier material is formed when the easily welded material portion is welded to the fuel tank. Since the end surface of the coating layer comes into contact with the outer surface of the fuel tank, a great effect can be obtained in achieving higher levels of welding strength and gasoline barrier properties.

According to the third aspect of the present invention, the gasoline barrier material layer flows into the welding interface between the easily welded materials by the guide means for preventing the coating layer softened during heating from flowing into the easily welded material side. Therefore, a great effect can be obtained in securing sufficient bonding strength.

According to the fourth aspect of the present invention, the child component is formed of the anchor base of the fastener means that can be repeatedly attached and detached, so that the functional part of the child component connected to the synthetic resin fuel tank can be repeatedly attached and detached. It becomes possible, and it is effective in improving the maintainability.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state in which a vent valve is fixed to an upper wall of a fuel tank of an automobile.

FIG. 2 is a partially enlarged cross-sectional view showing the first embodiment of the present invention.

FIG. 3 is a partially enlarged cross-sectional view showing an example of a variation.

FIG. 4 is a partially enlarged sectional view showing another variation.

FIG. 5 is a partially enlarged sectional view showing a second embodiment.

FIG. 6 is a partially enlarged sectional view showing a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vent valve 2 Fuel tank 3 Mounting hole 4 Valve function part 5 Support part 5s Coating layer 6 Flange 7 Hose port 8 Depression 9 Outer peripheral edge 11 Annular groove 12 Insert nut 13 Bolt

Claims (4)

[Claims] At least the surface layer has a structure in which a child part having a main portion made of an easily welded material and a covering portion made of a gasoline barrier material is connected to a synthetic resin fuel tank made of an easily welded material. In order to contact the main part with the heater prior to the covering part in the step of heating the child part with a heater for welding to the fuel tank, an end face of the main part and the covering part facing the heater. A structure of a connecting part of a child part to a synthetic resin fuel tank, wherein a step is provided between the parts. 2. The structure of the connecting part of the synthetic resin fuel tank according to claim 1, wherein the size of the step is determined in accordance with a margin for melting the main part at the time of welding. . 3. A structure in which at least a surface layer portion is a portion connecting a child part having a main portion made of an easily welded material and a covering portion made of a gasoline barrier material to a synthetic resin fuel tank made of an easily welded material. Guide means for preventing the cladding portion from softening during welding and flowing into the main portion side is provided on a portion of the main portion abutting on the fuel tank adjacent to the cladding portion. Characteristic structure of the joint part of the child parts to the synthetic resin fuel tank. 4. The structure according to claim 1, wherein the child part comprises an anchor base of a fastener means that can be repeatedly attached and detached.