JP2006321309A - Automobile fuel tank and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an automobile fuel tank separately forming an upper tank and a lower tank, having sufficient stiffness, facilitating manufacturing, and having high quality, and its manufacturing method. <P>SOLUTION: In a thermoplastic synthetic resinous fuel tank 1, the fuel tank 1 is formed by combining opening peripheral edge portions 11, 21 of divided and separately formed an upper tank portion 10 and a lower tank portion 20. The upper tank portion and the lower tank portion respectively have inner surface resin layers 15, 25 structuring an inner surface of the fuel tank, outer surface resin layers 17, 27 structuring an outer surface of the fuel tank, and core resin layers 19, 29 between the inner surface resin layers and the outer surface resin layers. The inner surface resin layers and the outer surface resin layers are formed from the same material of thermoplastic resin having fuel permeation preventive performance. The core resin layers are formed from material having shock resistance, and formed between the inner surface resin layers and the outer surface layers by injecting. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel tank made of thermoplastic synthetic resin formed by combining an upper tank part and a lower tank part formed separately and a method for manufacturing the same.

Conventionally, the structure of a fuel tank for automobiles has been made of metal. However, in recent years, thermoplastic synthetic resins have been used due to the weight reduction of vehicles, the absence of rust, and the ease of molding into desired shapes. The ones made by the company have come to be used.
For the production of automobile fuel tanks made of synthetic resin, blow molding methods have been often used because of the ease of molding hollow bodies. In the blow molding method, a melted synthetic resin parison is formed into a cylindrical shape and extruded from above, and the parison is sandwiched between molds and air is blown into the parison to manufacture an automobile fuel tank.

However, this method increases the overall weight of the parison in the case of a large synthetic resin hollow product such as an automobile fuel tank, and increases the strength when the strength of the automobile fuel tank is required. Therefore, the weight of the parison also increases when manufacturing a thick automotive fuel tank, and when the molten parison is dropped from the upper part of the molding machine into the mold, the upper wall thickness is lower. In some cases, it was thinner than the wall thickness.
In addition, in the case of a product with a complicated shape such as a fuel tank for automobiles, when the parison is expanded in the mold, the rate of expansion of the parison may vary depending on the part of the product. In some cases, there was variation.

In a blow molded automobile fuel tank, it is difficult to provide ribs, beams and the like, and the rate of expansion of the parison may vary depending on the part of the product, resulting in variations in the wall thickness of the tank. Therefore, a great deal of labor has been required for wall thickness management and quality control. Furthermore, it is difficult to attach accessories such as valves in the fuel tank.
Therefore, the synthetic resin hollow body is divided into upper and lower parts and molded separately by injection molding or the like, and then the upper tank and the lower tank are joined at the butting portion to form a fuel tank.

In such a method of forming the upper tank and the lower tank, for example, as shown in FIG. 7, a material having high fuel permeation prevention performance is used for the upper tank 102 of the fuel tank 101 and the inner surface 110 of the lower tank 103, and the outer surface In some cases, a material having high rigidity is used for 120, and an upper and lower divided body formed of two layers is formed by injection, and then the upper and lower divided bodies are welded and joined (for example, see Patent Document 1). However, when molding these two layers, the outer surface 120 is first injection-molded, and then the inner surface 110 is again injection-molded, which requires a lot of molding work and high-level control for molding the inner surface. Was necessary.
Further, when a sheet-like material is used for the inner surface and the outer surface is injection-molded, wrinkles or elongation may occur in the inner surface sheet, or the adhesive strength between the inner surface and the outer surface may be insufficient.

Further, as shown in FIG. 8, in the parts such as the valve cover 108 attached to the fuel tank, in order to prevent the permeation of the fuel and strengthen the adhesion with the fuel tank, the inner surface 108a and the outer surface 108b are modified high density polyethylene. And talc mixed polyamide is used between the inner surface 108a and the outer surface 108b (see, for example, Patent Document 2). However, it has been difficult to mold the modified high-density polyethylene and the talc mixed polyamide with a large synthetic resin product such as a fuel tank.
In addition, since the modified HDPE is used on the inner surface and the outer surface, when the parts are welded and attached to the fuel tank opening, fuel permeation from the welded portion is large.

Further, as another method, the mold is slightly opened, the material for forming the skin layer is injected into the mold, the material for forming the core layer is injected, and then the mold is closed to close the skin layer and the core. There is also a method in which a thin resin is sandwiched by compressing layers simultaneously (for example, see Patent Document 3). However, in the same manner as described above, it is not always easy to mold a large synthetic resin product such as a fuel tank.
JP 2004-98886 A Japanese Patent Laid-Open No. 2003-246028 JP-A-8-267506

  Thus, when the upper tank and the lower tank are formed separately, there has been a demand for a fuel tank having sufficient rigidity, easy to manufacture and excellent in quality, and a manufacturing method thereof.

The present invention of claim 1 for solving the above-mentioned problems is a fuel tank made of thermoplastic synthetic resin,
The fuel tank is formed by combining the opening peripheral portions of the upper tank portion and the lower tank portion separately formed separately, and the upper tank portion and the lower tank portion are the inner surface resin layers constituting the inner surface of the fuel tank, respectively. And an outer surface resin layer constituting the outer surface of the fuel tank, and a core resin layer between the inner surface resin layer and the outer surface resin layer. The inner surface resin layer and the outer surface resin layer are made of a thermoplastic resin having fuel permeation preventing performance. The fuel tank is formed of the same material, and the core resin layer is formed of a material having impact resistance, and is formed by injection between the inner surface resin layer and the outer surface resin layer.

  In the first aspect of the present invention, the fuel tank is formed by combining the opening peripheral portions of the upper tank portion and the lower tank portion which are separately divided and formed. For this reason, an upper tank part and a lower tank part can be separately molded by injection molding to obtain an upper tank part and a lower tank part with high dimensional accuracy and high strength. Therefore, a synthetic resin fuel tank formed by combining the upper tank portion and the lower tank portion can provide a precise and high strength product with high dimensional accuracy. Further, it is possible to easily attach a reinforcing rib, a built-in component, or the like inside the upper tank portion and the lower tank portion.

  Each of the upper tank portion and the lower tank portion has an inner surface resin layer constituting the inner surface of the fuel tank, an outer surface resin layer constituting the outer surface of the fuel tank, and a core resin layer between the inner surface resin layer and the outer surface resin layer. ing. For this reason, the same material can be used for the inner surface resin layer and the outer surface resin layer, and different resins can be used for the core resin layer. Is big.

  The inner surface resin layer and the outer surface resin layer are formed of the same thermoplastic resin material having fuel permeation prevention performance, and the core resin layer is formed of a material having impact resistance. For this reason, the resin excellent in fuel permeation prevention property can be used for the inner surface resin layer and the outer surface resin layer, and the core resin layer can be protected from the fuel. In addition, since a material having a smooth surface can be used, the surface of the fuel tank is smooth. In addition, a highly rigid resin can be used for the core resin layer regardless of the fuel permeation preventing property, and the strength of the fuel tank can be ensured.

  Since the core resin layer is formed by injection between the inner surface resin layer and the outer surface resin layer, the material constituting the core resin layer is injected into the material forming the inner surface resin layer and the outer surface resin layer, The resin layer, the outer surface resin layer, and the core resin layer can be integrally molded at the same time, and the upper tank portion and the lower tank portion can be formed by one molding, so that the molding is efficient. In addition, the inner surface resin layer and the outer surface resin layer and the core resin layer can be molded in a molten state, and the layers can be formed in close contact with each other. Can be formed.

  According to the second aspect of the present invention, the opening peripheral portions of the upper tank portion and the lower tank portion are formed with flange portions projecting outward at substantially right angles over the entire circumference, and the flange portions are fixed to each other. The fuel tank has an inner surface resin layer and an outer surface resin layer formed on the surface, and a core resin layer formed inside the flange portion.

  According to the second aspect of the present invention, the opening peripheral portions of the upper tank portion and the lower tank portion are formed with flange portions projecting outward at substantially right angles over the entire circumference, and the flange portions are fixed to each other. This is because the flanges of the upper tank portion and the lower tank portion are pressure-bonded to each other so that the open peripheral edges of the upper tank portion and the lower tank portion can be firmly adhered and fixed all around.

Since the inner surface resin layer and the outer surface resin layer are formed on the surface of the flange portion, and the core resin layer is formed inside the flange portion, the material having the fuel permeation preventing performance in the flange portion where the upper tank portion and the lower tank portion are combined. Since the inner surface resin layers composed of the above are fixed, the fuel does not permeate from the combined surface.
In addition, since the core resin layer is formed on the flange portion, the strength of the flange portion increases, the flange portions can be firmly bonded to each other, and the strength of the combined portion of the upper tank portion and the lower tank portion is increased. Can do.

  According to the third aspect of the present invention, the opening peripheral portions of the upper tank portion and the lower tank portion are respectively provided with protruding portions facing each other on the inner surface resin layer of the flange portion, and the protruding portions are welded to each other. Fuel tank.

  In the third aspect of the present invention, the opening peripheral portions of the upper tank portion and the lower tank portion are respectively formed with opposing protrusions on the inner surface resin layer of the flange portion over the entire periphery, and the protrusions are welded to each other. It was. For this reason, when the protrusions are welded to each other, the welded portion of the flange portion is determined, and both the protrusions are surely opposed and welded, so that the upper tank portion and the lower tank portion can be securely fixed.

  In the fourth aspect of the present invention, a plurality of inner ribs are integrally formed from the inner surface resin layer toward the inside of the tank, and a plurality of outer ribs are integrally formed from the outer surface resin layer toward the outer direction of the fuel tank. This is a fuel tank that is formed automatically.

In the present invention of claim 4, since a plurality of inner ribs are integrally formed from the inner surface resin layer toward the inside of the tank, parts such as a partition plate and a fuel pump are mounted inside the fuel tank. This makes it easy to increase the strength of the fuel tank.
Since the plurality of outer ribs are integrally formed from the outer surface resin layer toward the outside of the fuel tank, the strength of the fuel tank can be increased and components such as a hose clamp can be attached.

  The present invention according to claim 5 is a fuel tank in which the protruding portion and the inner rib toward the inside of the tank are formed only of the synthetic resin constituting the inner surface resin layer.

  In the present invention of claim 5, since the inner rib is formed only by the synthetic resin constituting the inner surface resin layer toward the projecting portion and the tank inward direction, the combined portion of the upper tank portion and the lower tank portion has the fuel permeation preventing performance. It is formed only with synthetic resin, and even with long-term use, the protrusion part completely melts with the coalesced part and can prevent the permeation of fuel from the coalesced part, and the inner rib has a reinforcing effect on the fuel tank, It can prevent changing with fuel.

  In the present invention of claim 6, the core resin layer is formed of high density polyethylene (HDPE), and the inner surface resin layer and the outer surface resin layer are made of polyethylene sulfide (PPS) rubber alloy, ethylene vinyl alcohol copolymer (EVOH), polyacetal. , A fuel tank formed from at least one material selected from nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfide.

In the present invention of claim 6, the core resin layer is formed of high density polyethylene (HDPE). For this reason, the strength is high, the strength of the fuel tank can be maintained without thickening the tank wall, and the weight of the fuel tank can be reduced. Furthermore, it is an olefinic thermoplastic synthetic resin and can be easily recycled.
The inner surface resin layer and the outer surface resin layer are layers made of at least one material selected from the group consisting of polyethylene sulfide (PPS) rubber alloy, ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfide. It is formed from the material which contains. For this reason, it is excellent in fuel permeation prevention property and can prevent permeation of fuel from the fuel tank.

The present invention of claim 7 is a thermoplastic synthetic resin formed by molding the upper tank part and the lower tank part separately with a mold, and combining the upper peripheral part of the upper tank part and the lower tank part and integrally joining them. In the manufacturing method of the fuel tank made of
The upper tank portion and the lower tank portion each have a structure having a core resin layer between the inner surface resin layer and the outer surface resin layer, and the inner surface resin layer and the outer surface resin layer, respectively.
Molding of the upper tank portion and the lower tank portion is performed by injecting an amount for filling a part of the cavity of the mold with respect to the synthetic resin constituting the inner surface resin layer and the outer surface resin layer with the mold closed. The synthetic resin constituting the core resin layer and the synthetic resin constituting the inner surface resin layer and the outer surface resin layer were injected at the same time to fill the cavity completely, and the core resin layer was formed between the inner surface resin layer and the outer surface resin layer. This is a method for manufacturing a fuel tank.

  In the seventh aspect of the present invention, the upper tank portion and the lower tank portion are configured to have an inner surface resin layer and an outer surface resin layer and a core resin layer between the inner surface resin layer and the outer surface resin layer, respectively. For this reason, the same material can be used for the inner surface resin layer and the outer surface resin layer, and different resins can be used for the core resin layer. Is big. The inner resin layer and the outer resin layer are made of the same material of thermoplastic resin having fuel permeation prevention performance, and the core resin layer is made of material having impact resistance. A high fuel tank can be obtained.

  Molding of the upper tank portion and the lower tank portion is performed by injecting an amount for filling a part of the cavity of the mold with respect to the synthetic resin constituting the inner surface resin layer and the outer surface resin layer with the mold closed. The synthetic resin constituting the core resin layer and the synthetic resin constituting the inner surface resin layer and the outer surface resin layer were injected at the same time, filling the entire cavity, and forming the core resin layer between the inner surface resin layer and the outer surface resin layer. For this reason, the core resin layer can be integrally and closely formed in the melted state inside the inner surface resin layer and the outer surface resin layer, and the inner surface resin layer, the outer surface resin layer, and the core resin layer are simultaneously formed once. Can be molded with high efficiency.

  According to the eighth aspect of the present invention, flange portions projecting outward are formed on the opening peripheral edge portions of the upper tank portion and the lower tank portion in the cavities of the molds for forming the upper tank portion and the lower tank portion, and are opposed to the flange portions, respectively. Provided with recesses that form protrusions that protrude in the direction of the inner surface, and a plurality of recesses that form inner ribs that protrude inward from the inner surface resin layer over the entire circumference in the width direction of the inner surfaces of the upper tank portion and the lower tank portion It is a manufacturing method of a tank.

  According to the eighth aspect of the present invention, flanges projecting outward are formed at the opening peripheral edge portions of the upper tank portion and the lower tank portion in the cavity of the mold for molding the upper tank portion and the lower tank portion, and are opposed to the flange portions, respectively. A concave portion that forms a protruding portion that protrudes in the direction to be formed is provided, and a plurality of concave portions that form inner ribs that protrude inward from the inner surface resin layer are provided over the entire circumference in the width direction of the inner surfaces of the upper tank portion and the lower tank portion. For this reason, the upper tank part and the lower tank part can be formed by one injection molding, and at the same time, the flange part, the inner rib and the protrusion part can be formed, respectively, which is efficient.

In the upper tank portion and the lower tank portion, the inner surface resin layer and the outer surface resin layer are formed from the same material of thermoplastic resin having fuel permeation prevention performance, and the core resin layer is formed from a material having impact resistance. For this reason, the resin excellent in fuel permeation prevention property can be used for the inner surface resin layer and the outer surface resin layer, and a material having a smooth surface can be used. Further, a highly rigid resin can be used for the core resin layer, and the strength of the fuel tank can be ensured.
Since the core resin layer is formed by injection between the inner surface resin layer and the outer surface resin layer, the material constituting the core resin layer is injected into the material forming the inner surface resin layer and the outer surface resin layer, The resin layer, the outer surface resin layer, and the core resin layer can be formed in close contact with each other at the same time, and can be formed by a single injection molding, so that the molding is efficient.

In the fuel tank manufacturing method of the present invention, the inner surface resin layer and the outer surface resin layer are formed of the same material of a thermoplastic resin having fuel permeation prevention performance, and the core resin layer is formed of a material having impact resistance. In addition, it is possible to obtain a highly rigid fuel tank having excellent fuel permeation preventive properties.
Molding of the upper tank part and the lower tank part is performed by injecting an amount that fills a part of the cavity of the mold for the synthetic resin constituting the inner surface resin layer and the outer surface resin layer, and then forming the core resin layer in the cavity. The resin, the inner resin layer, and the synthetic resin constituting the outer resin layer are injected at the same time to fill the entire cavity, and the core resin layer is formed between the layers, so that the core resin layer is integrally adhered inside the layer. The inner surface resin layer and the outer surface resin layer and the core resin layer can be simultaneously molded in a single molding step, which is efficient.

A fuel tank 1 according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of the fuel tank 1 as viewed obliquely from above. FIG. 2 is a sectional view taken along line XX in FIG.
3-6 is a figure which shows the manufacturing method of the fuel tank 1 mentioned later.

The fuel tank 1 includes an upper tank portion 10 and a lower tank portion 20 that are separately formed. The upper tank portion 10 and the lower tank portion 20 are each formed of three layers of inner resin layers 15 and 25, outer resin layers 17 and 27, and core resin layers 19 and 29 formed therebetween. The fuel tank 1 can be divided into not only two but also three or more.
A plurality of inner ribs 16 and 26 are integrally formed on the inner surfaces of the upper tank portion 10 and the lower tank portion 20 toward the inner direction of the fuel tank 1.
On the outer surfaces of the upper tank portion 10 and the lower tank portion 20, a plurality of outer ribs 18 and 28 are integrally formed outwardly on the outer surfaces of the outer surface resin layers 17 and 27 of the fuel tank 1.
The strength of the fuel tank 1 can be improved by the inner ribs 16 and 26 and the outer ribs 18 and 28, and attachment parts and the like can be easily attached.

  A pipe mounting hole 2 and a pump unit mounting hole 3 are formed in the upper tank portion 10. The pump unit mounting hole 3 is a hole for mounting and removing a pump unit (not shown) in the fuel tank 1, and the pipe mounting hole 2 is a hole for mounting a fuel injection pipe (not shown). . Note that a hose clamp 4 that holds various hoses such as a fuel transfer hose may be provided on the upper surface of the upper tank portion 10.

  The upper tank portion 10 and the lower tank portion 20 are respectively composed of inner surface resin layers 15 and 25 constituting the inner surface of the fuel tank 1, outer surface resin layers 17 and 27 constituting the outer surface of the fuel tank 1, and inner surface resin layers 15 and 25 and the outer surface. This is a three-layer structure having core resin layers 19 and 29 between the resin layers 17 and 27. Since the core resin layers 19 and 29 are injected between the inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27, the inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27 are integrally formed from the same material. The core resin layer 19 is formed. Since the core resin layers 19 and 29 can use a resin different from the above materials, two kinds of synthetic resins can be combined and selected, and there is a large room for material selection.

  The inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27 are made of a thermoplastic resin having fuel permeation prevention performance, and the core resin layers 19 and 29 are made of a material having impact resistance. For this reason, the inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27 are excellent in fuel permeation preventing property, and can prevent the fuel from permeating from the inside of the fuel tank 1. Moreover, the surface of the fuel tank 1 can be made smooth by using a material having a smooth surface for this material. Further, the core resin layers 19 and 29 can use a highly rigid resin, and can ensure the strength of the fuel tank. Moreover, since the core resin layers 19 and 29 do not appear on the surface of the fuel tank 1, a recycled material having a non-smooth product surface after molding can be used, which can contribute to recycling.

As shown in FIG. 2, flange portions 12 and 22 are formed on the opening peripheral edge portion 11 of the upper tank portion 10 and the opening peripheral edge portion 21 of the lower tank portion 20 so as to project outward from the outer surface at substantially right angles over the entire circumference. The flange portions 12 and 22 are fixed to face each other.
The flange portions 12 and 22 are formed in a substantially L-shaped cross section as shown in FIG. 2 and FIG. Projections 13 and 23 are formed over the entire area. The protrusions 13 and 23 are formed at positions facing each other, and the protrusions 13 and 23 are welded to each other as will be described later, whereby the welded portions of the flange parts 12 and 22 are determined, and both protrusions Thus, the upper tank part 10 and the lower tank part 20 can be securely fixed.

Flange recesses 12b and 22b are provided on the outer surfaces of the flange portions 12 and 22 having a substantially L-shaped cross section, and when the upper tank portion 10 and the lower tank portion 20 are combined, as will be described later in the manufacturing method, A jig for crimping 22 is inserted. For this reason, the upper tank part 10 and the lower tank part 20 can be firmly pressure-bonded.
Inner surface resin layers 15 and 25 and outer surface resin layers 17 and 27 that are continuous from the main body of the upper tank portion 10 and the lower tank portion 20 are formed on the surfaces of the flange portions 12 and 22, and the inner surface resin layers 15 and 25 and the outer surface resin layer 17 are formed. , 27, the core resin layers 19, 29 are continuously formed from the main body in the same manner as described above.

  Since the inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27 are formed on the surfaces of the flange portions 12 and 22, fuel permeation prevention performance is provided in the flange portions 12 and 22 where the upper tank portion 10 and the lower tank portion 20 are combined. The protrusions 13 and 23 of the inner surface resin layers 15 and 25 made of the material having the materials are fixed to each other so that fuel does not permeate from the combined surface. Further, since the core resin layers 19 and 29 are formed up to the tips of the flange portions 12 and 22, the strength of the core resin layers 19 and 29 is increased, and a jig is inserted into the flange recess portions 12b and 22b as described above. In addition, the flange portions can be firmly bonded to each other. For this reason, the intensity | strength of the united part of the upper tank part 10 and the lower tank part 20 can be increased, and the adhesiveness of the united part can be improved.

  As described above, the upper tank portion 10 and the lower tank portion 20 can be separately formed by a mold by injection molding or the like, and the strong and strong upper tank portion 10 and the lower tank portion 20 can be obtained. . For this reason, the precision of the united part of the upper tank part 10 and the lower tank part 20 is good, and the fuel tank 1 united closely can be obtained. Further, the inner ribs 16 and 26 can be integrally provided in the upper tank portion and the lower tank portion, or a built-in component or the like can be easily attached.

  The outer ribs 18 and 28 provided on the outer surfaces of the outer surface resin layers 17 and 27 of the upper tank portion 10 and the lower tank portion 20 are integrally formed from the outer surface resin layers 17 and 27, and the longitudinal direction and the width direction of the fuel tank 1. A plurality of each is provided. The outer ribs 18 and 28 can improve the strength of the fuel tank 1. Similarly, the hose clamp 4 is integrally formed from the outer surface resin layers 17 and 27, and a plurality of hose clamps 4 are formed on the surface of the fuel tank 1. A fuel pipe (not shown) and a fuel evaporative gas transfer pipe (not shown) are fixed to the hose clamp 4.

  The inner surface resin layers 15 and 25 and the outer surface resin layers 17 and 27 of the upper tank portion 10 and the lower tank portion 20 are made of, for example, polyethylene sulfide (PPS) using a thermoplastic synthetic resin excellent in fuel permeation prevention. , Ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfide can be used. In this case, the inner surface resin layers 15 and 25 are excellent in fuel permeation preventive properties and can prevent permeation of fuel from the fuel tank 1.

  The core resin layers 19 and 29 can be formed from high-density polyethylene (HDPE). Other than the high-density polyethylene (HDPE), a thermoplastic synthetic resin that has fuel oil resistance and impact resistance and has excellent strength is used. be able to. When high-density polyethylene (HDPE) is used, the strength is high, the walls of the outer resin layer 20 and the inner resin layer 10 do not need to be thickened, and the weight of the fuel tank 1 can be reduced. Moreover, since it is excellent in heat-resistant deterioration, its strength can be maintained for a long period of time, and it is an olefinic thermoplastic synthetic resin that can be easily recycled.

Next, the manufacturing method of this fuel tank 1 is demonstrated based on FIGS.
The fuel tank 1 is manufactured by separately molding the upper tank portion 10 and the lower tank portion 20 with a mold, and then welding the opening peripheral portions 11 and 21 of the upper tank portion 10 and the lower tank portion 20. Although the manufacturing method of the upper tank part 10 and the lower tank part 20 is shape | molded by a respectively different metal mold, it is substantially the same, and it demonstrates taking the case of the manufacturing method of the upper tank part 10 as an example.

As shown in FIG. 3, the upper tank portion 10 is molded by injection molding using an upper tank molding die 30.
First, the synthetic resin for forming the inner surface resin layer 15 and the outer surface resin layer 17 from the spool 34 in the cavity 33 of the upper tank molding die 30 is smaller than the capacity of the cavity 33, for example, 1/4 to 1/1 of the total amount. An amount of about 2 is injected.

  Next, as shown in FIG. 4, the synthetic resin that forms the core resin layer 19 from the spool 34 is centered on the spool 34, and the synthetic resin that forms the inner surface resin layer 15 and the outer surface resin layer 17 is outward. To ejaculate simultaneously. Thereby, the synthetic resin forming the inner surface resin layer 15 and the outer surface resin layer 17 flows on the surface of the cavity 33, the inner surface resin layer 15 is formed on the surface of the fixed mold 31, and the outer surface of the movable mold 32 is formed on the outer surface. The resin layer 17 is formed, and the core resin layer 19 is formed between the inner surface resin layer 15 and the outer surface resin layer 17 inside the cavity 33, and flows toward the end of the cavity 33.

Further, if the synthetic resin forming the core resin layer 19 and the synthetic resin forming the inner surface resin layer 15 and the outer surface resin layer 17 are continuously injected, the synthetic resin is injected to the end of the cavity 33 as shown in FIG. The
At this time, the core resin layer 19 is injected up to the flange portion 12 formed on the opening peripheral edge portion 11 which is the end portion of the upper tank portion 10. Thereby, the strength of the flange portion 12 is improved.

  In this injection molding, the synthetic resin constituting the inner surface resin layer 15 and the outer surface resin layer 17 has a low solidification temperature, and therefore solidifies when it touches the surfaces of the fixed mold 31 and the movable mold 32 in the cavity 33, respectively. While forming the resin layer 15 and the outer surface resin layer 17, the resin penetrates into the back of the cavity 33, and the synthetic resin constituting the new inner surface resin layer 15 and the outer surface resin layer 17 is supplied to the surfaces of the fixed mold 31 and the movable mold 32. Then, the inner resin layer 15 and the outer resin layer 17 are formed one after another. Then, the synthetic resin enters the concave portion provided in the fixed mold 31 to form the inner rib 16 of the inner surface resin layer 15, and the synthetic resin enters the concave portion provided in the movable die 32, and the outer side of the outer surface resin layer 17. Ribs 18 are formed.

At this time, the synthetic resin constituting the core resin layer 19 has lower fluidity than the synthetic resin constituting the inner surface resin layer 15 and the outer surface resin layer 17, and therefore, a cavity is formed between the inner surface resin layer 15 and the outer surface resin layer 17. It penetrates to the end of 33. As described above, the core resin layer 19 reaches the flange portion 12.
At this time, the flange portion 12 is provided with a concave portion that forms the protruding portion 13 in the cavity 33 of the portion corresponding to the flange portion 12 in the fixed mold 31. For this reason, this recessed part is filled with the synthetic resin which comprises the inner surface resin layer 15, and forms a protrusion part.

In this way, the shape of the upper tank portion 10 can be accurately formed by injection molding. Therefore, the fuel tank 1 with high dimensional accuracy can be obtained as described above.
Similarly, the lower tank portion 20 is molded by injection molding using a lower tank molding die. In the lower tank portion 20, as shown in FIG. 5, the protruding portion 23, the inner rib 27 and the outer rib 28 are integrally formed at the same time.

Next, the upper tank part 10 and the lower tank part 20 are joined. As shown in FIG. 6, the heat plate 40 is formed on the flanges 12 of the opening peripheral edge 11 of the upper tank 10 and the protrusions 13 and 23 provided on the inner surface of the flange 22 of the opening peripheral 21 of the lower tank 20. Then, a jig is inserted into the flange recesses 12b and 22b of the opening peripheral edge portions 11 and 21, and the flange portions 12 and 22 are pressure-bonded to be melted and joined.
Before joining the upper tank portion 10 and the lower tank portion 20, a valve (not shown), a fuel pump, and the like mounted inside the fuel tank 1 are attached to the upper tank 11 and the lower tank portion 20.
The joined upper tank portion 10 and lower tank portion 20 form a hollow fuel tank 1 as shown in FIG.

  When a thermoplastic synthetic resin excellent in fuel permeation prevention is used for molding the inner surface resin layer 10 and the outer surface resin layer 17, as described above, polyethylene sulfide (PPS) rubber alloy, ethylene vinyl alcohol copolymer (EVOH) Etc., the core resin layer 19 is molded using a biaxial injection molding machine using high density polyethylene (HDPE) or the like. As a result, the inner resin layer 10, the outer resin layer 17 and the core resin layer 19 can be reliably joined.

  Since the core resin layer 19 is formed by injection between the inner surface resin layer 15 and the outer surface resin layer 17, the material constituting the core resin layer 19 in the material forming the inner surface resin layer 15 and the outer surface resin layer 17. The inner surface resin layer 15, the outer surface resin layer 17, and the core resin layer 19 can be integrally molded at the same time, and can be formed by one molding, so that the molding is efficient. Therefore, the inner resin layer 15 and the outer resin layer 17 can be formed in close contact with the core resin layer 19, and the core resin layer 19 can be reliably formed up to the end portion even in a complicated shape of the fuel tank. it can.

It is the perspective view which looked at the fuel tank which is embodiment of this invention from diagonally upward. It is sectional drawing along the XX line of FIG. It is sectional drawing of the metal mold | die which shape | molds the upper tank part of the inner surface resin layer which is embodiment of this invention, and shows the state which injected the synthetic resin which comprises an inner surface resin layer and an outer surface resin layer into a cavity a little. FIG. 3 is a cross-sectional view of a mold for molding the upper tank portion of the inner surface resin layer according to the embodiment of the present invention, and cavities more than half the synthetic resin constituting the inner surface resin layer and the outer surface resin layer and the synthetic resin constituting the core resin layer Shows the injected state. FIG. 4 is a cross-sectional view of a mold for molding the upper tank portion of the inner surface resin layer according to the embodiment of the present invention, and completely cavities the synthetic resin constituting the inner surface resin layer, the outer surface resin layer, and the synthetic resin constituting the core resin layer. Shows the injected state. It is a cross-sectional schematic diagram of the state which fuse | melts the upper peripheral part of the fuel tank which is embodiment of this invention, and the opening peripheral part of a lower tank part with a hot platen. It is sectional drawing of the conventional fuel tank. It is sectional drawing of the valve cover attached to the conventional fuel tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 10 Upper tank part 11, 21 Opening peripheral part 12, 22 Flange part 13, 23 Protrusion part 15, 25 Inner surface resin layer 17, 27 Outer surface resin layer 19, 29 Core resin layer 20 Lower tank part 30 Mold 40 Heating Molten plate

Claims (8)

In a fuel tank made of thermoplastic synthetic resin,
The fuel tank is formed by combining the respective opening peripheral portions of the upper tank portion and the lower tank portion which are separately molded separately.
Each of the upper tank portion and the lower tank portion includes an inner surface resin layer constituting the inner surface of the fuel tank, an outer surface resin layer constituting the outer surface of the fuel tank, and a core resin layer between the inner surface resin layer and the outer surface resin layer. The inner surface resin layer and the outer surface resin layer are formed from the same material of a thermoplastic resin having fuel permeation prevention performance, the core resin layer is formed from a material having impact resistance, and the inner surface resin layer And a fuel tank formed by injection between the outer resin layers.   Opening peripheral edge portions of the upper tank portion and the lower tank portion are formed with flange portions projecting outward at substantially right angles over the entire circumference, the flange portions are fixed to each other, and the surface of the flange portion is the inner surface. The fuel tank according to claim 1, wherein a resin layer and an outer surface resin layer are formed, and the core resin layer is formed inside the flange portion.   The opening peripheral portions of the upper tank portion and the lower tank portion are respectively formed with protruding portions facing each other on the inner surface resin layer side of the flange portion, and the protruding portions are welded to each other. Or the fuel tank of Claim 2.   A plurality of inner ribs are integrally formed from the inner surface resin layer toward the inner side of the tank, and a plurality of outer ribs are integrally formed from the outer surface resin layer toward the outer direction of the tank. The fuel tank according to any one of claims 1 to 3.   The fuel tank according to any one of claims 1 to 4, wherein the protruding portion and the inner rib toward the inside of the tank are formed only of a synthetic resin constituting an inner surface resin layer.   The core resin layer is made of high density polyethylene (HDPE), and the inner surface resin layer and outer surface resin layer are made of polyethylene sulfide (PPS) rubber alloy, ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate. The fuel tank according to any one of claims 1 to 5, wherein the fuel tank is formed of at least one material selected from the group consisting of polyethylene terephthalate and polyphenylene sulfide. A method for producing a fuel tank made of a thermoplastic synthetic resin, wherein the upper tank portion and the lower tank portion are separately molded with a mold, and the opening peripheral edge portions of the upper tank portion and the lower tank portion are combined and integrally joined. In
The upper tank portion and the lower tank portion each have a configuration having an inner surface resin layer and an outer surface resin layer, and a core resin layer between the inner surface resin layer and the outer surface resin layer,
The molding of the upper tank portion and the lower tank portion is performed by injecting an amount for filling a part of the cavity of the mold for the synthetic resin constituting the inner surface resin layer and the outer surface resin layer with the mold closed. Thereafter, the synthetic resin constituting the core resin layer and the synthetic resin constituting the inner surface resin layer and the outer surface resin layer are injected into the cavity at the same time, and the cavity is completely filled between the inner surface resin layer and the outer surface resin layer. A method for producing a fuel tank, wherein a core resin layer is formed on the fuel tank.   Formed in the cavity of the mold for molding the upper tank portion and the lower tank portion is a flange portion that protrudes outward from the opening peripheral edge portion of the upper tank portion and the lower tank portion, and protrudes in the opposite direction from the flange portion. 8. The recess according to claim 7, wherein a recess that forms a protrusion is provided, and a plurality of recesses that form inner ribs protruding inward from the inner surface resin layer are provided over the entire circumference in the width direction of the inner surfaces of the upper tank portion and the lower tank portion. Fuel tank manufacturing method.

Images