JP2008030664A - Fuel tank and fuel tank structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel tank 10 constructed by laminating a plurality of resin layers, having a tank mounting member by heat welding, and making wall thickness thin. <P>SOLUTION: The fuel tank 10 comprises: an inner layer 21 made from polyethylene; a barrier layer 23 laminated on the inner layer 21 and having fuel permeability resistance superior to the inner layer 21; a heat insulating layer 25 imposed between the barrier layer 23 and an outer layer 26 and made by mixing minute hollow elements into polyethylene; and the outer layer 26 laminated on the barrier layer and made from polyethylene. The minute hollow elements of the heat insulating layer 25 form an air layer, and has a high heat insulating property. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel tank in which a plurality of resin layers are laminated, and a fuel tank structure in which a tank mounting member such as a joint or a fuel cutoff valve is thermally welded to an outer wall of the fuel tank.

  In recent years, resin fuel tanks have been used from the viewpoint of weight reduction and moldability of fuel tanks. A tank mounting member that forms a tank opening on the upper wall of the fuel tank and surrounds the periphery of the opening of the tank opening and connects the tank and the outside is thermally welded (Patent Document 1). In order to thermally weld the tank mounting member to the upper wall of the fuel tank, the welded portion of the tank mounting member is melted by a hot plate or the like, and at the periphery of the opening of the tank opening of the fuel tank by the hot plate along the periphery. This is done by pressing these molten parts together.

  However, it is necessary to increase the thickness of the fuel tank to ensure that it does not deform even if it is welded with a hot plate or pressed with a tank mounting member. There has been a problem of causing an increase in the weight of the. In order to solve such a problem, the peripheral edge of the tank opening is partially thickened or the rib is formed on the peripheral edge of the tank opening when the blow molding method is used for manufacturing the fuel tank. In addition, there is a problem that the shape of the mold becomes complicated when molding by injection molding.

JP 2003-48436 A

  An object of the present invention is to provide a thin resin fuel tank and a fuel tank structure capable of heat-welding a tank mounting member in view of solving the above-described problems of the prior art. .

The present invention made to solve the above problems
In a fuel tank having a tank chamber for storing fuel and laminating a plurality of resin layers,
Facing the tank chamber, an inner layer made of polyethylene,
A barrier layer that is laminated on the inner layer and has better fuel permeation resistance than the inner layer;
An outer layer made of polyethylene laminated on the barrier layer;
A heat insulating layer interposed between the barrier layer and the outer layer, in which a micro hollow body is mixed in polyethylene,
It is provided with.

  In the fuel tank of the present invention, since the barrier layer is interposed between the inner layer and the outer layer made of polyethylene, the permeation of the fuel in the tank chamber to the outside can be reduced. Moreover, since the heat insulation layer arrange | positioned between a barrier layer and an outer layer is formed from the resin material which mixed the micro hollow body in polyethylene, heat insulation becomes high with the air layer of a micro hollow body. Therefore, when the weld joint is welded to the fuel tank, the heat insulating layer hardly transmits heat to the inner layer, and the rigidity and the planar shape are maintained even if the inner layer is thin. Therefore, the thickness of the inner layer does not need to be focused on the thickness considering thermal weldability, and the fuel tank can be configured with a thin inner layer, the amount of material can be reduced, and the weight of the fuel tank can be reduced. Can be planned.

  As a preferred embodiment of the present invention, the barrier layer is an ethylene vinyl alcohol copolymer (EVOH), and an adhesive layer can be interposed between the barrier layer and the heat insulating layer. The adhesive layer can be formed of maleic acid-modified polyethylene, and adheres the barrier layer and the heat insulating layer. Since the modified polyethylene is the same polyethylene as the outer layer and the heat insulating layer, the modified polyethylene is welded to each other and bonded to the EVOH by chemical adhesion, so that the barrier layer and the heat insulating layer can be firmly bonded.

  Furthermore, as a preferred aspect of the present invention, in a fuel tank structure including a tank mounting member thermally welded to the outer surface of the outer layer of the fuel tank, a tank opening is provided on the upper wall of the fuel tank, and the tank mounting member Can comprise a welding end formed of a resin material thermally welded to the outer layer, and the welding end is thermally welded to the opening peripheral edge of the tank opening.

  In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the present invention will be described below.

(1) Schematic Configuration of Fuel Tank Structure FIG. 1 is a cross-sectional view showing a fuel tank structure of an automobile according to an embodiment of the present invention. The fuel tank 10 includes a tank body 20 having a tank chamber 12S for storing fuel, and is configured by laminating a plurality of resin layers. Tank openings 20b and 20c are formed in the upper wall 20a of the tank body 20, and tank mounting members such as a welding joint 30 and a fuel cutoff valve 40 are attached to the peripheral edges of the tank openings 20b and 20c by heat welding. Yes.

(2) Structure of Fuel Tank Structure Next, the structure of each part of the fuel tank structure will be described.
(2) -1 Configuration of Fuel Tank 10 FIG. 2 is an enlarged cross-sectional view of the vicinity of the weld joint 30, and FIG. 3 is an enlarged cross-sectional view of a connection location between the upper wall 20 a of the fuel tank 10 and the weld joint 30 in FIG. is there. In FIG. 3, the tank body 20 of the fuel tank 10 is formed of six layers including a heat-resistant layer formed of a resin material excellent in heat insulation and a barrier layer formed of a resin material excellent in fuel permeability. Yes. That is, the tank body 20 includes an inner layer 21, an adhesive layer 22, a barrier layer 23, an adhesive layer 24, a heat insulating layer 25, and an outer layer 26, and is manufactured by a blow molding method that shapes a parison.

The inner layer 21 is mainly intended for the structural material that ensures the mechanical strength of the fuel tank and the resistance to the fuel, and high-density polyethylene (HDPE) is selected.
The barrier layer 23 is mainly intended for fuel permeation resistance, and ethylene vinyl alcohol copolymer (EVOH) or polyamide (PA) can be selected.
The heat insulation layer 25 is mainly intended to insulate the fuel tank, and is a material in which high density polyethylene is the main material and a micro hollow body is mixed. The micro hollow body has a configuration in which air excellent in heat insulation is sealed in a ball body made of glass, resin, ceramic, metal, or the like. Here, it is preferable that 5 to 30% by weight of the micro hollow body is mixed. If the amount is less than 5% by weight, the heat insulating effect cannot be obtained. On the other hand, if it exceeds 30% by weight, the adhesiveness and formability with the outer layer 26 are impaired. As the fine hollow sphere, for example, a scotchlite glass bubbles (manufactured by Sumitomo 3M, particle size range 15 to 135 μm, average particle size 30 to 70 μm) can be used. In addition, it is not necessary to restrict to Scotchlite glass bubbles, and it is good also as other glass micro hollow spheres, and it is good also as other micro hollow spheres, such as a ceramic sphere other than a glass sphere. Further, the micro hollow body is not limited to a spherical shape, and may be a hollow tubular body as long as it is configured to seal air.
The high-density polyethylene may be a recycled resin material in addition to the same material as the inner layer 21.

The outer layer 26 is mainly intended for mechanical strength, and high density polyethylene (HDPE) similar to the inner layer 21 is selected.
The adhesive layers 22 and 24 are bonded to the inner layer 21 and the barrier layer 23 or both the barrier layer 23 and the heat insulating layer 25 to bond these layers. A maleic acid-modified modified polyethylene (m-PE) as a polar functional group is selected as a resin material that performs such an action. Since the modified polyethylene is a similar polyethylene, it is welded to the HDPE of the inner layer 21 and the heat insulating layer 25, and is bonded to EVOH by chemical adhesion, and thus has an action of adhering these layers.

  The thickness of each layer of the fuel tank 10 is 2 mm for the inner layer 21, 0.1 to 0.3 mm for the barrier layer, 2 mm for the heat insulating layer 25, and 1.5 mm for the outer layer 26, as an example for achieving the above-described action. The adhesive layers 22 and 24 can be 0.5 mm.

(2) -2 Configuration of Weld Joint 30 In FIG. 2, the weld joint 30 is a joint for closing the tank opening 20b of the upper wall 20a and connecting it to the hose H. The welded joint 30 includes a closing plate 32, a flange portion 34 formed on the outer periphery of the closing plate 32, a connection passage 36 a that connects the inside and outside of the fuel tank 10, and a tube body 36 for connecting the hose H. And. An annular welding end 34 a that is welded to the upper wall 20 a of the fuel tank 10 is formed at the lower end of the flange portion 34. The resin material forming the welded joint 30 is determined in consideration of the weldability with the fuel tank 10 and the fuel permeation resistance. For example, high-density polyethylene, medium-density polyethylene, or the like can be used.

(3) Welding Operation of Fuel Tank Structure Next, an operation of attaching the welding joint 30 to the upper wall 20a of the fuel tank 10 will be described. In FIG. 4, the lower end of the weld end 34a of the weld joint 30 is melted by the hot plate HP and is melted by the hot plate HP along the peripheral edge of the tank opening 20b of the upper wall 20a to form the weld portion 20d. The welding end 34a is pressed against the welding part 20d. Thereby, since both the welding end 34a and the welding part 20d are formed of polyethylene, they are welded to each other when cooled and solidified. In this state, as shown in FIG. 2, when the hose H is press-fitted into the pipe body 36 of the welded joint 30 and tightened with the clamp CP, the hose H is connected into the fuel tank 10 via the connection passage 36a. .

(4) Operation and effect of embodiment The following operation and effect are exhibited by the fuel tank structure according to this embodiment.
(4) -1 Since the heat insulation layer 25 arranged outside the inner layer 21 is mixed with a minute hollow body, the heat insulation is enhanced by the air layer of the minute hollow body. Since the heat insulating layer 25 hardly transfers heat to the inner layer 21 when the weld joint 30 is welded to the fuel tank 10, the heat insulating layer 25 maintains the rigidity and the planar shape even if the inner layer 21 is thin. Therefore, the thickness of the inner layer 21 does not need to be a thickness that particularly takes heat weldability into consideration, and the fuel tank 10 can be formed with the thin inner layer 21, and the amount of material can be reduced, and the fuel tank 10 Can be reduced in weight.

(4) -2 The heat insulating layer 25 increases the heat insulating property of the fuel tank 10 itself, so that the flame resistance can be improved.

(4) -3 The heat insulating layer 25 reduces heat transfer from the outside air to the tank chamber 12S, and therefore can prevent an increase in gasoline temperature. Therefore, generation | occurrence | production of the gasoline vapor | steam which generate | occur | produces many at the time of parking under a hot sun can be suppressed, and the vapor | steam amount which flows into a canister can be reduced.

(4) -4 When the fuel tank 10 forms a parison in the blow molding process, it is only necessary to take a process of mixing a micro hollow body into polyethylene as a resin material for forming the heat insulating layer 25, thereby reducing molding costs. can do.

(4) -5 Since the fuel tank 10 does not need to be formed with ribs on the peripheral edge of the opening or partially thickened to increase the rigidity in order to heat-weld the welded joint 30, that is, the opening The peripheral part may be a flat mold structure and can be easily manufactured by blow molding.

(4) -6 Since the heat insulation layer 25 uses the same polyethylene as the outer layer 26, both are firmly joined. Moreover, since the outer layer 26 is made of polyethylene in which a minute hollow body is not mixed, the thermal weldability with the welded joint 30 is not impaired.

(5) Other Embodiments The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(5) -1 Although the said Example demonstrated the structure which adhere | attaches the inner layer 21, the barrier layer 23, and the barrier layer 23, and the heat insulation layer 25 using the adhesive layers 22 and 24, not only this but the inner layer 21 In addition, by using modified PE as a resin material for the heat insulating layer 25 and imparting adhesiveness to the barrier layer 23, the adhesive layer can be eliminated and a simple structure of four layers can be obtained.

(5) -2 As long as the fuel tank is connected to the outside, it can be applied to various joints, for example, a fuel cutoff valve for ventilating the fuel tank and the outside.

It is sectional drawing which shows the structure of the fuel tank of the motor vehicle concerning one Example of this invention. It is sectional drawing to which the vicinity of the welding joint was expanded. It is sectional drawing to which the connection location of the upper wall of the fuel tank of FIG. 2, and a welding joint was expanded. It is explanatory drawing explaining the operation | work which heat-welds a welding joint to a fuel tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel tank 12S ... Tank chamber 15 ... Particle size range 20 ... Tank main body 20a ... Upper wall 20b, 20c ... Tank opening 21 ... Inner layer 22 ... Adhesive layer 23 ... Barrier layer 24 ... Adhesive layer 25 ... Heat insulation layer 26 ... Outer layer 30 ... Weld joint 32 ... Closing plate 34 ... Flange 34a ... Weld end 36 .. .Tube 36a ... Connection passage H ... Hose CP ... Clamp

Claims (3)

In a fuel tank having a tank chamber (12S) for storing fuel and laminating a plurality of resin layers,
Facing the tank chamber (12S), an inner layer made of polyethylene,
A barrier layer (23) laminated on the inner layer (21) and having better fuel permeation resistance than the inner layer (21);
An outer layer (26) made of polyethylene laminated on the barrier layer (23);
A heat insulating layer (25) interposed between the barrier layer (23) and the outer layer (26), in which a micro hollow body is mixed in polyethylene;
A fuel tank comprising: The fuel tank according to claim 1, wherein
The barrier layer 23 is an ethylene vinyl alcohol copolymer (EVOH),
Between the said barrier layer (23) and the said heat insulation layer (25), it forms with the maleic acid modified polyethylene, and the contact bonding layer (24) which adhere | attaches the said barrier layer (23) and the said heat insulation layer (25). ) Fuel tank equipped with. A fuel tank structure comprising a tank mounting member thermally welded to the outer surface of the outer layer (26) of the fuel tank according to claim 1 or 2,
A tank opening (20b) is provided on the upper wall (20a) of the fuel tank,
The tank mounting member includes a welding end (34a) formed of a resin material thermally welded to the outer layer (26), and the welding end (34a) is thermally welded to the peripheral edge of the opening of the tank opening (20b). Fuel tank structure.

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