JPH08219392A - Gas cylinder - Google Patents

Abstract

PURPOSE: To allow the pressure tightness of an outer shell to be maintained for a long period of time in a gas cylinder of double layer structure formed of an inner shell and an outer shell. CONSTITUTION: In a gas cylinder having an inner shell 2 with gas barrier property and a pressure tight FRP outer shell 3 provided in such a way as to cover the inner shell 2, the surface layer of the outer shell is intermixed with a foam body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various gas cylinders, and more particularly to a gas cylinder suitable for mounting on an automobile or the like.

[0002]

2. Description of the Related Art In recent years, automobiles that use natural gas as fuel have attracted attention as low-pollution vehicles in the United States and other foreign countries.
CNG tanks (Comp
A gas cylinder called a "less natural gas tank" is mounted.

Such gas cylinders for automobiles have hitherto been known.
It is made of metal such as steel or aluminum alloy, but metal is heavy and reduces fuel consumption. in addition,
The calorific value per unit weight of natural gas is only about half that of gasoline, so if you try to increase the distance that you can run without refueling like a gasoline car, you have to carry about twice as much natural gas as gasoline. This in turn increases gross vehicle weight and reduces fuel economy. Therefore, weight reduction of gas cylinders is being considered as a measure for improving fuel efficiency.

By the way, Japanese Patent Publication No. 5-88665 discloses a gas cylinder in which a plastic inner shell having a gas barrier property is covered with a pressure-resistant outer shell made of FRP (fiber reinforced plastic). This gas cylinder
Since it is essentially made of plastic, it is considerably lighter than metal, and if it is used as a natural gas cylinder for automobiles, it can be expected to improve fuel efficiency.

However, since FRP is more brittle than metal, if a local impact force is applied, that portion and the periphery of that portion are easily damaged. Especially FRP
When the reinforcing fiber inside is damaged, the breakage easily proceeds from that part. Such a problem can of course be solved by setting a high safety factor. However, in this case, the weight is increased and the weight saving effect, which is the greatest merit of using the FRP, is impaired, and the manufacturing cost is increased.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to pay attention to the above problems, and to reduce the weight while maintaining the pressure resistance, which is essentially a two-layer structure of an inner shell and an outer shell. In a gas cylinder that has, even when an external impact force is applied,
The purpose is to appropriately protect the pressure-resistant outer shell and maintain excellent pressure resistance for a long period of time.

[0007]

A gas cylinder according to the present invention which meets the above object is a gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell. A foam is mixed in the surface layer of the outer shell.

The gas cylinder according to the present invention is a gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein the surface layer of the outer shell is a gas cylinder. A non-woven fabric is arranged.

Further, the gas cylinder according to the present invention is a gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein the outer shell is made of an elastic material. And the elastic body is covered with a protective layer. As the protective layer, a heat shrinkable tube or an FRP layer can be formed.

In the structure of the gas cylinder according to the present invention as described above, the outer shell made of FRP can be appropriately protected, and its excellent pressure resistance can be maintained for a long period of time.

1 and 2 show a gas cylinder according to an embodiment of the present invention. In FIG. 1, a gas cylinder 1 has an inner shell 2 having a gas barrier property, and a pressure-resistant FRP outer shell 3 provided so as to cover the inner shell 2.
The gas cylinder 1 as a whole has a body portion A, an end plate portion B following the body portion A, a nozzle attachment mouthpiece 4 and a nozzle 5 attached thereto, and a boss 6 provided at the opposite end portion. .

In the above, the inner shell 2 has a function of preventing gas leakage. Further, as will be described later, it also acts as a core when forming a pressure resistant outer shell.

The inner shell 2 is made of a resin such as a polyethylene resin, a polypropylene resin, a polyamide resin, an ABS resin, a polybutylene terephthalate resin, a polyacetal resin or a polycarbonate resin.
ABS resin is preferable in terms of excellent impact resistance. Such a resin inner shell 2 can be manufactured by, for example, a well-known blow molding method.
Can be combined with. It is also possible to use a composite blow molding method to form a multilayer structure in which a layer of polyamide resin having excellent gas sealing property is sandwiched by layers of high density polyethylene resin having excellent rigidity. Also, the inner shell 2 is F
It may be made of RP. Such an FRP inner shell 2 can be manufactured, for example, by injection-molding a resin containing reinforcing fibers used for the outer shell 3, which are short fibers having a fiber length of about 2 to 10 mm, which will be described later. . Further, the inner shell 2 may be made of a metal, for example, a light alloy such as a thin aluminum alloy or a magnesium alloy.

The inner shell 2 has a function of preventing gas leakage as described above. In order to improve such action, it is also preferable to form a gas barrier layer on the inner surface and / or the outer surface. For example, when nitrogen gas containing fluorine is used as a blowing gas during blow molding, a gas barrier layer made of a fluororesin coating can be formed on the inner surface of the inner shell 2. Alternatively, a gas barrier layer may be formed by forming a plating film of a metal such as copper, nickel or chromium on the outer surface. The metal plating film can be formed by an electrolytic plating method or an electroless plating method. When the inner shell 2 is manufactured by the composite blow molding method, a layer of polyamide resin or the like having excellent gas barrier properties is arranged on the inner side, and a layer of easily-platable, for example, ABS resin is arranged on the outer side to form a metal plating film. It can also facilitate molding.

The inner shell also has 2.5 to 5c on its inner surface.
It is possible to provide ring-shaped ribs extending in the circumferential direction at intervals of about m. Such an inner shell can be obtained, for example, by making a half-divided inner shell made of a plastic with ribs, and joining and integrating them. This rib is
The strength of the inner shell is improved, the inner shell is prevented from being deformed at the time of forming the outer shell of the FRP described later, and the strength of the outer shell is reduced due to meandering or uneven distribution of the reinforcing fibers of the FRP layer forming the outer shell, and variations in strength, As a result, it helps prevent the deterioration of pressure resistance.

Referring again to FIG. 1, in this embodiment,
On the body portion A of the inner shell 2, there is formed a reinforcing layer 7 made of FRP, which is formed by hoop-winding a reinforcing fiber yarn described later or by combining a woven fabric of such a reinforcing fiber yarn and a resin. The reinforcing layer 7 may extend to a part of the end plate portion B. However, in the present invention, it is not essential to have the reinforcing layer 7.

On the other hand, the outer shell 3 is made of FRP from the standpoint of providing pressure resistance and at the same time reducing the weight of the gas cylinder 1 as a whole. The FRP outer shell 3 is formed by forming the above-described inner shell 2 as a so-called mandrel, around which a winding layer of a reinforcing fiber yarn containing a resin is formed by a well-known filament winding method or tape winding method. It can be configured by At this time, when the reinforcing layer 7 is present, the average height of the outer surface of the inner shell 2 including the surface thereof is 10 to 200 μm.
It is preferable to form a rough surface to some extent because slippage of the reinforcing fiber yarn at the time of winding can be prevented and disturbance of the distribution of the reinforcing fiber can be reduced.

As the reinforcing fiber yarn, at least one kind of high-strength and high-modulus fiber yarn such as carbon fiber yarn, glass fiber yarn, and organic high elastic modulus fiber (for example, polyaramid fiber) can be used. It is preferable that these reinforcing fiber yarns are non-twisted fiber yarns having excellent openability in the sense that stress concentration due to bending can be reduced and generation of voids can be reduced. And, even among such reinforcing fiber yarns, it has excellent specific strength and specific elastic modulus, there is almost no occurrence of yarn breakage or fluff during winding, and not only the improvement of productivity but also the strength due to mixing of yarn seams and fluff. A carbon fiber yarn is preferred because it can prevent deterioration of properties and impact resistance.

As the resin, thermosetting resins such as epoxy resin, unsaturated polyester resin, vinyl ester resin and phenol resin, polyamide resin, polyethylene terephthalate resin, ABS resin, polyetherketone resin, polyphenylene sulfide resin, Poly-4-
A thermoplastic resin such as methylpentene-1 resin or polypropylene resin can be used.

In this embodiment, as shown in FIG. 2, the foam 8 is mixed in the surface layer of the outer shell 3. This foamed body 8 is formed by mixing a foamed material in the form of powder or granules into the surface layer forming material when the surface layer of the outer shell 3 is formed, and foaming the foamed material during molding of the outer shell 3, for example, during heat molding. It can be present in the surface layer of the shell 3. For example, when the outer shell 3 is made of FRP composed of a reinforcing fiber thread and a resin, when the reinforcing fiber thread forming the surface layer of the outer shell 3 is impregnated with the resin,
A predetermined foam may be mixed in the resin. When the resin is a thermosetting resin, the foam can be foamed simultaneously with the curing of the resin in the heat curing step.

The foam 8 is not particularly limited, but for example, a thermally expansible vinylidene chloride-based, silica-based, phenol-based, shirasu-based, or carbon-based foam having a particle size of 10 to 30 μm can be used. For example, as the vinylidene chloride-based foam, "Matsumoto Microsphere" manufactured by Matsumoto Yushi Co., Ltd., as the silica-based foam, "Silica balloon" manufactured by British Ferrite Co., and as the phenol-based foam in the U.S.A. C. C. "Phenol Micro Balloon" manufactured by Shirasu Co., Ltd. and "Silas Balloon" manufactured by Sanki Industry Co., Ltd. can be cited as examples of the Shirasu foam.

By mixing the foam 8 into the surface layer of the outer shell 3, the foaming of the foam 8 thickens the outermost resin layer of the outer shell 3 and functions as a protective layer for the inner layer side. . Therefore, even if an impact force is applied to the surface of the outer shell 3 and even if the surface is damaged, a large impact force is prevented from propagating to the inner layer side, and damage to the reinforcing fiber on the inner layer side is prevented. To be done. As a result, the desired excellent pressure resistance can be maintained as the entire outer shell 3.

Further, since the foam 8 itself has elasticity, the surface layer portion of the outer shell 3 in which the foam 8 is mixed functions as an energy absorbing layer, and the inner layer side of the outer shell 3 is appropriately protected also from this surface, Prevents major damage.

FIG. 3 shows a layer structure around an outer shell 11 of a gas cylinder according to another embodiment of the present invention. In this embodiment, a layer of the non-woven fabric 12 is arranged on the surface layer of the outer shell 11, and substantially the entire surface of the outer shell 11 is covered with the non-woven fabric 12. When the outer shell 11 is formed of FRP, the resin of the FRP is covered with a non-woven fabric 12 before being cured, and in some cases, the outer periphery of the non-woven fabric 12 is tightened with an appropriate pressing force, so that a part of the resin before curing is non-woven. It can be impregnated in 12. In this molding method, the nonwoven fabric 1
The 2 can be combined with the outer shell 11 substantially integrally.

Even in such a structure, the impact force from the outside is properly absorbed by the layer having the nonwoven fabric 12 and the large force is prevented from propagating to the inner layer side of the outer shell 11. Therefore, damage to the reinforcing fibers of the outer shell 11 is prevented, and the desired excellent pressure resistance of the entire outer shell 11 can be maintained.

FIG. 4 shows a layer structure around the outer shell 21 of the gas cylinder according to another embodiment of the present invention.
In this embodiment, the outer surface of the outer shell 21 is covered with the elastic body 22, and the outer surface of the elastic body 22 is further covered with the protective layer 23. As the elastic body 22, various kinds of rubber or foam (foamed elastomer) can be used, and as the protective layer 23, a heat shrinkable tube or FRP can be applied. Examples of the heat-shrinkable tube include a heat-shrinkable tube made of polyethylene, polyvinyl chloride, or fluororesin.

In such a structure, the impact force from the outside is absorbed by the excellent elasticity of the elastic body 22, and the surface of the relatively soft elastic body 22 is protected by the protective layer 23. Therefore, the outer shell 21 is appropriately protected and the excellent pressure resistance of the outer shell 21 itself is maintained while preventing the elastic body 22 from being scratched or deteriorated.

In particular, if the protective layer 23 is composed of a heat-shrinkable tube, even if the protective layer 23 is damaged, it can be easily replaced and a new tube can be easily covered. .

The kind of gas filled in the gas cylinder according to the present invention is not particularly limited, and may be nitrogen gas, oxygen gas, helium gas, etc. in addition to the above-mentioned natural gas.

[0030]

As described above, in the case of the gas cylinder of the present invention, the impact force absorbing layer is formed or provided on the surface layer portion of the FRP outer shell, and the impact force from the outside is properly absorbed in this portion. Since a large force is not applied to the inner layer side of the outer shell, the excellent pressure resistance of the outer shell itself can be stably maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a gas cylinder according to an embodiment of the present invention.

FIG. 2 is an enlarged partial sectional view of the gas cylinder of FIG.

FIG. 3 is a partial cross-sectional view of a gas cylinder according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a gas cylinder according to yet another embodiment of the present invention.

[Explanation of symbols]

 1 Gas Cylinder 2 Inner Shell 3, 11, 21 Outer Shell 4 Nozzle Mounting Base 5 Nozzle 6 Boss 7 Reinforcing Layer 8 Foam 12 Nonwoven 22 Elastic 23 Protective Layer

Claims (4)

[Claims] 1. A gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein a foam is mixed in a surface layer of the outer shell. A gas cylinder characterized by that. 2. A gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein a nonwoven fabric is arranged on a surface layer of the outer shell. Gas cylinder characterized by. 3. A gas cylinder having an inner shell having a gas barrier property and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein the outer shell is covered with an elastic body, A gas cylinder characterized in that an elastic body is covered with a protective layer. 4. The gas cylinder according to claim 1, wherein the inner shell is made of plastic.