JP2008150072A - Manufacturing process of double hull fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process of double-hull fuel tank capable of uniformly assuring a detection space and preventing a deformation or breakage of the tank caused by an external pressure and the like. <P>SOLUTION: This invention relates to a manufacturing process of double-hull fuel tank in which a detection space 3 is arranged between an inner hull 2 and an outer hull 1 enclosing the inner hull 2. This process comprises the step of preparing a resin sheet 4 molded into a shape having many protrusions 40 protruded toward the inner hull 2 and cavities 41 formed between the protrusions 40 to communicate with each other, enclosing the outer surface 21 of the inner hull 2 by the resin sheet 4 under the state in which the protruding ends 40a of the protrusions 40 in the resin sheet 4 so as to keep contact with the outer surface 21 of the inner hull 2, and forming the supporting part 11 where resin fills the cavities 43 formed at the opposite surfaces of the protrusions 40 and comes into contact with the inner hull 2 through the resin sheet 4 by forming the outer hull 1 composed of a resin layer at the outer surface 4c of the resin sheet 4 while resin coats the outer surface 4c of the resin sheet 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a double shell fuel tank.

  2. Description of the Related Art Conventionally, as a fuel tank for underground use used in a gas station or the like, a double shell fuel tank capable of detecting a fuel leak due to damage of the tank has been proposed (see Patent Documents 6 and 7). As shown in FIG. 1, the double shell fuel tank includes an inner shell 2 made of iron or resin and an outer shell 1 made of resin, and the tank is placed between the inner shell 2 and the outer shell 1. A detection space 3 for detecting oil leakage inside is formed. A detection liquid is sealed in the detection space in advance, and an abnormality in the inner shell or outer shell of the tank is detected by monitoring a volume change of the detection liquid using a sensor (not shown).

As the double shell fuel tank, a film is attached between the inner shell and the outer shell, and a detection space is formed by providing a gap of about 0.1 mm to 0.2 mm between the film and the inner shell. Conceivable.
However, in this structure, since the detection space is secured by a film, the outer shell is pressed toward the inner shell by external force (earth pressure) when the tank is installed underground. In particular, the bottom of the tank is pressed downward (foundation surface) by the load of the fuel in the inner shell tank and the load from the overburden soil. Therefore, the film and the outer surface of the inner shell may be in close contact with each other, and a uniform space detection layer cannot be provided. Therefore, if it takes time to detect leakage or if a crack or the like generated in the tank is a small hole, there is a possibility that the film is pressed by the external pressure to close the hole and delay the discovery of the tank damage.

Therefore, it is necessary to keep the detection space constant by supporting between the outer shell and the inner shell.
For example, a method has been proposed in which a plastic sheet whose surface is formed into a concavo-convex shape is attached between an inner shell and an outer shell, and a gap of about 3 to 4 mm is secured as a detection layer (see Patent Documents 1 and 2). .
In addition, a method has been proposed in which a hard insert plate is attached with an interval between an inner shell and an outer shell to ensure a gap (see Patent Document 3).
Furthermore, a method for securing a gap between the inner shell and the outer shell by attaching particles at a predetermined interval has been proposed (see Patent Document 4).

However, in each of the methods described in Patent Documents 1 to 4 described above, the sheet, insert plate, and particle support area for supporting the pressure applied to the outer shell from the outside with the inner shell is small, and the outer pressure due to the external pressure, the tank's own weight, etc. The deformation of the shell is not uniform throughout, and partial deformation occurs.
Also, when using insert plates or particles, the distance between adjacent insert plates or between particles is deformed by external pressure, and the insert plate or particles serve as a fulcrum, and the gap between the outer shell and the inner shell Uniformity cannot be maintained.
Further, for example, a polyester resin having high corrosion resistance is used for the outer shell. However, since this polyester resin is brittle, it is easily broken like glass when an impact load is applied. Therefore, when the external pressure is applied intensively, there is a risk that the outer shell may be damaged. In particular, when the external pressure is concentrated on a part of the outer shell due to rocks or other solids contained in the soil, the outer shell may be damaged by a sharp tip.

On the other hand, a method has been proposed in which a gap between the inner shell and the outer shell is secured using a three-dimensional glass fiber, and the inner shell and the outer shell are joined by the glass fiber to achieve integration (see Patent Document 5). .
However, in this method, in the process of forming the space with the three-dimensional glass fiber, when the resin is impregnated with the glass fiber, the space cannot be made uniform, or the joint portion between the outer shell and the inner shell (corresponding to a column) The impregnation amount of the portion) is difficult to be made uniform, and a difference in thickness is likely to occur partially at the joint portion. For this reason, the strength varies, and when an external pressure or concentrated load is applied to the weak portion, the uniformity of the gap may be impaired.
Utility model registration No. 3022356 JP-A-10-35784 JP-A-8-230975 JP-A-11-193087 JP 2006-117255 A JP 63-281986 JP-A 63-203581

  Accordingly, an object of the present invention is to provide a method for manufacturing a double-shell fuel tank capable of ensuring a uniform detection space and preventing deformation or damage of the tank due to external pressure or the like.

  In order to achieve the above object, a method for manufacturing a double-shell fuel tank according to the present invention is a method for manufacturing a double-shell fuel tank in which a detection space is provided between an inner shell and an outer shell that wraps the inner shell. Preparing in advance a resin sheet molded into a shape having a number of convex portions projecting toward the inner shell side and concave grooves formed between the convex portions and connected to each other; and the convex portions of the resin sheet A step of wrapping the outer surface of the inner shell with the resin sheet in a state where the projecting end of the resin sheet is in contact with the outer surface of the inner shell, and applying a resin to the outer surface of the resin sheet to form a resin layer on the outer surface of the resin sheet Forming a support portion in contact with the inner shell through the resin sheet by filling the recess into a recess formed on the opposite surface of the convex portion. I have.

In the conventional method, when an external pressure or concentrated stress is applied when a tank is buried, a weak portion is generated, so that the force is not well distributed and the outer shell is damaged. However, according to the present invention, since the support portion is formed by filling the resin in the recess of the resin sheet, the support area of the outer shell can be increased, so that the stress due to the external pressure becomes uniform and the outer shell is removed. There is no risk of damage.
In addition, when the gap between the detection spaces is narrow, a portion where the inner shell and the outer shell are brought into close contact with each other due to pressure from the outside is generated, and the detection capability (speed) may be reduced. As a result, a gap in a certain detection space can be secured, so that the detection capability does not deteriorate.
Furthermore, in the detection method in which liquid is put into the detection space, the conventional detection space molding method causes a deformation of the outer shell to change the volume of the detection space and generate a false alarm. Since the volume of the space is stable, and the amount of the detection liquid can be reduced by increasing the support area, malfunction can be prevented.

In the present invention, before applying the resin, the method further comprises a step of winding a net-like net around the outer peripheral surface of the resin sheet to bring the convex portion of the resin sheet into close contact with the outer surface of the inner shell. preferable.
According to this aspect, by using the net-like net to bring the resin sheet into close contact with the outer surface of the inner shell, in the resin application process, the resin sheet is prevented from being displaced or distorted by the weight of the resin. Since the detection space can be ensured uniformly, the detection accuracy can be further improved.

  On the other hand, as another manufacturing method of the double shell fuel tank, the detection space is formed in the manufacturing method of the double shell fuel tank in which the detection space is provided between the inner shell and the outer shell that wraps the inner shell. As described above, preparing a resin sheet having elasticity bonded to the first surface in a state where a large number of spheres having a diameter of about 1 to 5 mm are in contact with each other, while the sphere is directed to the inner shell, A step of wrapping the inner shell with the sheet while applying tension to the resin sheet; and a step of forming an outer shell by applying a resin on the second surface of the sheet surrounding the inner shell. .

According to this method, since the spheres can be arranged densely by contacting the inner shell in a state where a large number of spheres are in contact with each other, the stress applied to the outer shell is uniformly distributed, and the deformation of the tank And damage can be prevented.
Here, since the resin sheet has elasticity, when the resin sheet is wound along the circumference of the inner shell in a state where a large number of balls are in close contact with each other, the resin sheet is stretched, so that the resin sheet is wound around the inner shell. It becomes possible.
In addition, since the detection space is formed between the spheres, the accuracy and reliability of leakage detection are improved.

  In this manufacturing method, it is preferable that the method further includes a step of winding a net-like net around the outer peripheral surface of the resin sheet to press the sphere against the outer surface of the inner shell before applying the resin.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment.
As shown in FIG. 1, the double-shell fuel tank has a detection space 3 between an inner shell 2 and an outer shell 1 that encloses the inner shell 2.
In the inner shell 2, gasoline, light oil, kerosene and the like are stored. When the detection liquid is sealed in the detection space 3, an abnormality such as damage to the outer shell 1 and / or the inner shell 2 of the tank is detected by monitoring the volume change of the detection liquid by a sensor (not shown). is doing.

As shown in FIG. 2B, the tank is formed by laminating the inner shell 2, the resin sheet 4, and the outer shell 1 in this order. A net-like net 5 is embedded in the outer shell 1.
The resin sheet 4 has a convex portion 40 that contacts the outer surface 21 of the inner shell 2 and a concave groove 41 that forms a detection space 3 between the inner shell 2 and the outer shell 1. As shown in FIG. 2A, the concave grooves 41 of the resin sheet 4 are formed in a lattice pattern between adjacent convex portions 40 (halftone dot portions in FIG. 2A).
The resin constituting the outer shell 1 is filled in the convex portion (concave portion) 40 of the resin sheet 4 and constitutes the support portion 11.

Production method:
First, the resin sheet 4 is molded into a shape having a large number of convex portions 40 projecting toward the inner shell 2 side and concave grooves 41 formed between the convex portions 40 and continuous with each other.

  The resin sheet 4 is made of a resin that does not dissolve in the resin solvent and does not penetrate the resin. As the resin sheet 4, for example, a known thermoplastic resin such as polystyrene, polyvinyl chloride, or polymethacrylic resin is used. be able to.

Next, in the inner shell 2 made of, for example, steel shown in FIG. 3A, the resin sheet 4 in a state where the protruding end 40 a of the convex portion 40 of the resin sheet 4 is in contact with the outer surface 21 of the inner shell 2 as shown in FIG. 3B. Wraps the outer surface 21 of the inner shell 2. That is, the resin sheet 4 is wound so as to wrap the inner shell 2 while applying tension to the protruding end 40 a of the convex portion 40 of the resin sheet 4 so as to contact the outer surface 21 of the inner shell 2. The overlapping portions of the resin sheet 4 and the resin sheet 4 are attached to each other with an adhesive tape or the like.
Accordingly, the convex portion 40 of the resin sheet 4 is in contact with the outer surface 21 of the inner shell 2, and the inner shell 2 is wrapped with the resin sheet 4 in a state where the concave groove 41 is not in contact with the inner shell 2.

  Thereafter, as shown in FIG. 3C, a net-like net 5 made of, for example, resin is wound around the outer peripheral surface 4 b constituting a part of the groove 41 of the resin sheet 4, and the resin sheet 4 is pressed toward the inner shell 2. By winding the net 5 around the resin sheet 4, the convex portion 40 of the resin sheet 4 is in close contact with the outer surface 21 of the inner shell 2.

Thereafter, resin is applied to the outer surface 4 c of the resin sheet 4 to form the outer shell 1 made of a resin layer on the outer surface 4 c of the resin sheet 4. By application of this resin, the resin 43 is filled through the net 5 into the recess 43 formed on the surface of the resin sheet 4 opposite to the convex portion 40. By filling the recess 43 with the resin, the support portion 11 in contact with the inner shell 2 through the resin sheet 4 is formed, and the detection space 3 is formed by the concave groove 41.
Here, since the resin sheet 4 is pressed toward the inner shell 2 by the net 5 and the resin sheet 4 is in close contact with the inner shell 2, the resin sheet 4 and the inner shell 2 are displaced due to the weight of the resin, Problems such as deformation of the resin sheet 4 and wrinkles can be prevented.

The resin for forming the outer shell 1 is not particularly limited as long as it is a known thermosetting resin, but preferably, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, or the like is used. Of these, isophthalic acid-based and bisphenol-based unsaturated polyester resins are used from the viewpoint of corrosion resistance.
In addition, it is preferable to mix reinforcing fibers into the resin, and known reinforcing fibers such as glass fibers, carbon fibers, and aramid fibers are used as the reinforcing fibers. Among them, glass fiber is preferable, and the glass content in the resin is not particularly limited, but for example, a range of 30 to 60% by weight is preferable. The glass fiber may be used in combination with the chopped strand method.

  As a molding method of the outer shell 1, a known molding method such as a filament winding method, a hand lay-up method, a spray-up method, or a resin injection method can be used, and preferably a spray-up method.

  After filling the resin, the resin is naturally dried for a predetermined time to cure the resin. Due to the hardening of the outer shell 1, a gap of 0.1 mm to 0.2 mm is generated between the convex portion 40 of the resin sheet 4 constituting the support portion 11 and the inner shell 2, and the entire periphery of the inner shell 2 is detected. The space 3 can be configured. As a result, a uniform detection space 3 can be formed in the entire tank, the change in the spatial volume of the detection space 3 due to external pressure is reduced, and the detection liquid can be reduced because the spatial volume of the detection liquid is small. Leak detection with few malfunctions can be performed.

Since the double-shell fuel tank manufactured by the method described above is filled with the resin in the recess 43 of the resin sheet 4, unlike the conventional case, there is no possibility that the resin sheet 4 is crushed by external pressure. The space 3 can be provided reliably. Moreover, since the support area of the support part 11 and the inner shell 2 can be set large, the concentrated load of the external pressure can be received in a distributed manner.
Moreover, the volume of the detection space 3 can be arbitrarily set by changing the size of the convex portion 40 of the resin sheet 4. Furthermore, the detection space 3 can be created uniformly by creating the projections 40 uniformly. Moreover, the accuracy of the detection sensor can be increased by making the convex portion 40 large and making the space in which the detection liquid is enclosed smaller than before, thereby reducing the volume change of the detection liquid.

Variation:
As the shape of the resin sheet, it is sufficient that the concave grooves 41 of the resin sheet 4 are formed to be continuous with each other, and various shapes can be adopted. For example, as shown in FIGS. 4A and 4B, You may employ | adopt resin sheet 4A in which the hemispherical convex part 40 was formed. In this case, it arrange | positions so that the hemispherical convex part 40 of 4 A of resin sheets may contact the outer surface 21 of the inner shell 2. As shown in FIG. A detection space 3 is formed by the concave groove 41 between the hemispherical convex portions 40.

5 and 6 show the second embodiment.
As shown in FIG. 5B, the double-shell fuel tank of the second embodiment is formed by laminating the inner shell 2, the sphere 6, the resin sheet 4B, and the outer shell 1 in this order. A net-like net 5 is embedded in the outer shell 1.
As shown in FIG. 5A, the sphere 6 is provided in a state where a large number of spheres 6 are in contact with each other, and a detection space 3 is formed between the spheres 6. The spheres 6 having the same diameter between 1 mm and 5 mm are used.
Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

Production method:
First, a resin sheet 4B is produced in which a large number of spheres 6 are bonded to the first surface S1 (FIG. 6B). In order to produce the resin sheet 4B, for example, a method described in JP-A-11-193087 can be used.

  Next, as shown in FIG. 6B, the resin sheet 4B in which a large number of balls 6 are bonded to the inner shell 2 made of steel, for example, shown in FIG. Wrap. The winding is performed so as to wrap the inner shell 2 while applying tension to the resin sheet 4B.

Thereafter, as shown in FIG. 6C, a net-like net 5 is wound around a second surface (outer peripheral surface) S2 opposite to the first surface S1 of the resin sheet 4B, and the ball 6 is attached to the outer surface of the inner shell 2. 21.
After winding the net 5, as shown in FIG. 6D, the outer shell 1 made of a reinforced plastic such as a resin is formed on the second surface S2 of the resin sheet 4B enclosing the inner shell 2. The outer shell 1 is molded by the same method using the same resin as that of the outer shell 1 of Example 1 described above, the sheet method of winding a resin sheet, or the like.

In the double-shell fuel tank manufactured by the method described above, since the spheres 6 are in contact with each other, the adjacent spheres 6 are in contact at a single point, so that a uniform detection space 3 is reliably formed between the spheres 6. Can be formed.
In addition, since the adjacent spheres 6 are in contact with each other, even when an external force such as earth pressure is applied, there are many points that receive the external force. Can be prevented.

  In both the above-described embodiments, the inner shell is made of steel, but the inner shell may be made of the same resin as the outer shell.

  The present invention can be applied to, for example, a fuel tank buried underground such as a gas station.

1 is a schematic cross-sectional view showing a double shell fuel tank according to an embodiment of the present invention. FIG. 2A is a schematic plan view of a resin sheet according to Example 1 of the present invention, and FIG. 2B is a schematic longitudinal sectional view of a double shell fuel tank. It is process drawing which shows the manufacturing method of a double shell fuel tank. FIG. 4A is a schematic plan view of a resin sheet showing a modification, and FIG. 4B is a schematic longitudinal sectional view of the double-shell fuel tank. FIG. 5A is a schematic plan view of a resin sheet according to Example 2 of the present invention, and FIG. 5B is a schematic longitudinal sectional view of the double-shell fuel tank. It is process drawing which shows the manufacturing method of a double shell fuel tank.

Explanation of symbols

1: Outer shell 2: Inner shell 3: Detection space 4, 4A, 4B: Resin sheet 4c: Outer surface (of resin sheet) 5: Net 6: Ball 11: Support portion 21: Outer surface of (inner shell) 40: Convex Portion 40a: protruding end 41: recessed groove 43: recessed portion S1: first surface

Claims (4)

In the method of manufacturing a double-shell fuel tank in which a detection space is provided between the inner shell and the outer shell that wraps the inner shell,
Preparing in advance a resin sheet molded into a shape having a number of convex portions projecting toward the inner shell side and concave grooves formed between the convex portions and connected to each other;
Wrapping the outer surface of the inner shell with the resin sheet in a state where the protruding end of the convex portion of the resin sheet is in contact with the outer surface of the inner shell;
By applying a resin to the outer surface of the resin sheet to form an outer shell made of a resin layer on the outer surface of the resin sheet, the resin is placed in a recess formed on the surface opposite to the convex portion. And a step of forming a support portion in contact with the inner shell through the resin sheet. In claim 1,
Manufacturing a double-shell fuel tank further comprising a step of winding a net-like net around the outer peripheral surface of the resin sheet and bringing the convex portion of the resin sheet into close contact with the outer surface of the inner shell before applying the resin. Method. In the method of manufacturing a double shell fuel tank in which a detection space is provided between the inner shell and the outer shell that wraps the inner shell,
In order to form the detection space, an elastic resin sheet bonded to the first surface in a state where a large number of spheres having a diameter of about 1 to 5 mm are in contact with each other is prepared. Wrapping the inner shell with the sheet while applying tension to the resin sheet,
And a step of forming an outer shell by applying a resin on the second surface of the sheet enclosing the inner shell. In claim 3,
A method for manufacturing a double-shell fuel tank, further comprising a step of winding a net-like net around the outer peripheral surface of the resin sheet and press-contacting the sphere against the outer surface of the inner shell before applying the resin.

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