JPH08219391A - Gas cylinder and manufacture thereof - Google Patents

Abstract

PURPOSE: To heighten the torsional strength and the like of a joint part in the inner shell end part to a boss in a gas cylinder of double layer structure formed of the inner shell and an outer shell. CONSTITUTION: A gas cylinder has an inner shell 2 with gas barrier property, a pressure tight outer shell 3 provided in such a way as to cover the inner shell 2, and a boss 6 provided at the bottom part of the inner shell 2. In this case, the bottom part of the inner shell 2 and the boss 6 are engagedly fitted to each other through the polygonal faces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various gas cylinders, particularly gas cylinders suitable for mounting on automobiles and the like, and a method for producing the same.

[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.

In such a gas cylinder, a cap is provided at one end of the inner shell for attaching a gas for filling the gas into the cylinder and for attaching a nozzle for taking out gas from the cylinder, and at the other end, a gas cylinder is provided. A metal boss, for example, may be provided for standing or for reinforcing the other end (eg, US Pat. No. 4,925).
044 publication).

On the other hand, around the inner shell, FR is formed by a known filament winding method or tape winding method.
An outer shell made of P can be formed, but at this time, the inner shell rotates as a core body, so that the inner shell has
It should preferably be supported at both ends.
As described above, when the nozzle mounting mouthpiece or the boss is joined to the end of the inner shell, these members can be used as a shaft when rotating the inner shell.

However, since the nozzle mounting die is installed in the neck portion of the inner shell and firmly joined thereto, it sufficiently functions as a rotary shaft body, but the boss provided at the other end portion of the inner shell is By simply joining the other end of the inner shell, high torsional strength and bending strength cannot be obtained at the joining portion. Particularly, when the torsional strength is low, there is a possibility that the torsional stress between the inner shell and the boss, which acts when the outer shell is formed by the filament winding method, cannot be endured. Therefore, even if the filament winding method is applied, high winding tension cannot be applied, the volume content of the reinforcing fibers is reduced, and it becomes difficult to increase the pressure resistance of the outer shell.

[0008]

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 the gas cylinder consisting of, the torsional strength and bending strength at the joint portion between the inner shell and the boss are to be increased to the strength that can sufficiently withstand the filament winding molding of the outer shell.

[0009]

A gas cylinder according to the present invention which meets the above object has an inner shell having gas barrier properties, a pressure-resistant outer shell provided to cover the inner shell, and a bottom portion of the inner shell. A gas cylinder having a boss, wherein the bottom of the inner shell and the boss are attached to each other via a polygonal surface.

Further, in the method for manufacturing a gas cylinder according to the present invention, a nozzle mounting mouthpiece is provided at the neck portion of the inner shell having gas barrier properties, and a boss attached to the bottom portion through a polygonal surface is provided, and the mouthpiece is provided. While supporting the inner shell on both sides with the boss and the boss, a pressure-resistant FRP outer shell is formed around the inner shell by a filament winding method.

1 to 4 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 outer shell 3 provided so as to cover the inner shell 2. The gas cylinder 1 has a body A as a whole and an end plate B following it.
A nozzle mounting mouthpiece 4 which is installed in a neck portion 2a formed at one end of the inner shell 2 and is integrally connected to the inner shell 2, a nozzle 5 attached to the mouthpiece 4, and an inner shell 2 And a boss 6 joined to the end opposite to the base 4.

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, it is preferable that the outer shell 3 is made of FRP from the viewpoint that it has pressure resistance and at the same time the weight of the gas cylinder 1 is reduced. Such FR
The outer shell 3 made of P is formed by forming the above-mentioned inner shell 2 as a so-called mandrel, and forming a wound layer of a reinforcing fiber yarn containing a resin around it by a well-known filament winding method or tape winding method, and molding the wound layer. can do. At this time, when the reinforcing layer 7 is present, the average height of the outer surface of the inner shell 2 including its surface is 10 to 20.
It is preferable to form a rough surface of about 0 μm because slippage of the reinforcing fiber yarn at the time of winding can be prevented and disturbance of 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.

The description will be made with reference to FIG. 1 again and FIGS. 2 to 4. A concave portion 8 is formed at an end portion of the inner shell 2 opposite to the side to which the base 4 is coupled, and the umbrella portion 6a of the boss 6 is fitted into the concave portion 8. The recess 8 is formed in a square cross section, in this embodiment, a hexagonal cross section, and the umbrella portion 6a of the boss 6 fitted to the recess 8 also has a hexagonal cross section. It is formed in a shape. Therefore, in this embodiment, the fitting contact portion between the concave portion 8 and the umbrella portion 6a is formed in the portion that is engaged via the polygonal surface in the present invention. In addition,
The polygonal shape may be a triangle, but is preferably a quadrangle or more polygonal shape, particularly a hexagonal shape as illustrated,
Alternatively, an octagon is preferable.

Further, in the present embodiment, a column 9 extending up into the boss 6 in the cylinder axial direction is erected at the center of the recess 8. The column body 9 is a solid columnar body formed integrally with the inner shell 2. On the boss 6 side, a cylindrical hole 6b
Is formed, and the column 9 is fitted into the hole 6b.
The axial length of the column 9 is preferably about 20 to 50 mm.

In the production of the gas cylinder 1 as described above, for example, when the inner shell 2 is made of plastic and the mouthpiece 4 is made of metal, the inner shell 2 and the mouthpiece 4 to be formed at the time of blow molding the inner shell 2 The bosses 6 are mounted on the opposite end of the inner shell 2 after being integrally joined and after blow molding. A pillar 9 standing upright at the end of the inner shell is fitted into a hole 6b of the boss 6, and an umbrella portion 6a of the boss 6 having a hexagonal cross section is fitted into a corresponding recess 8 of the hexagonal cross section. Therefore, the boss 6 is naturally fixed in a predetermined position and posture by simply fitting it. Therefore, the adhesive may not be provided between the boss 6 and the end portion of the inner shell 2 that abuts on the boss 6. However, in order to at least temporarily fix the boss 6 to the inner shell 2, the two may be bonded together.

In this state, as shown in FIG.
The base 4 is joined to one end of the molded inner shell 2 and the boss 6 is fixed to the other end. Since the die 4 is integrally connected to the inner shell 2 during blow molding of the inner shell 2 as described above, both the torsional strength and the bending strength are sufficiently high at the joint between the two. On the other hand, the other end of the inner shell 2 and the boss 6
At the joint portion with, first, the umbrella portion 6a having a hexagonal cross section
Due to the fitting between the concave portion 8 and the concave portion 8, extremely high strength is exerted in the torsion direction. Further, due to the fitting structure of the pillar 9 and the hole 6b, extremely high strength is exerted also in the bending direction.

Therefore, when the inner shell 2 is supported on both sides through the base 4 and the boss 6 and the outer shell 3 is formed around the inner shell 2 by the filament winding method, the inner shell 2 is wound around the inner shell 2. Even if the tension of the resin impregnated reinforcing fiber yarn is increased,
It becomes possible to sufficiently withstand the torsional stress and bending stress acting on the end portion of the inner shell 2. As a result, the volume content of the reinforcing fibers in the outer shell 3 can be increased, and the outer shell 3 having even higher pressure resistance can be formed. Further, the work of the filament winding process can be facilitated and facilitated.

In the above embodiment, the pillar 9 is erected in the center of the recess 8 at the end of the inner shell 2, but, for example, as shown in FIG. It is also possible to adopt a structure in which nothing is formed, and the umbrella portion 6a of the boss 6 having a corresponding hexagonal cross-sectional shape is simply fitted (attached). Even with such a configuration, at least the torsional strength at the joint between the boss and the inner shell can be significantly improved. However, in this structure, the bending strength may be insufficient, so it is preferable to bond the boss 6 and the end of the inner shell 21 with an adhesive. Thereby, a sufficiently high bending strength can be secured at the same time.

Further, as shown in FIG. 6, the end concave portion 32 of the inner shell 31 has a circular cross-sectional shape, and the central portion of the concave portion 32 has a square cross-sectional shape extending in the axial direction (for example, as shown in FIG. It is also possible to erect the columnar body 33 and provide a hole having a cross-sectional shape corresponding to the columnar body 33 on the boss side, and fit the columnar body 33 into the hole. In such a structure, both the torsional strength and the bending strength are greatly increased at the same time by the fitting structure of the column body 33 and the hole of the boss.

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

[0028]

As described above, when the gas cylinder of the present invention is used, the torsional strength and the bending strength at the joint between the inner shell and the boss can be significantly increased, so that the outer shell is not attached to the outer shell. Even when the shell is formed by the filament winding method, sufficiently high strength can be exerted at the above-mentioned joint. As a result, it is possible to increase the tension of the resin-impregnated reinforcing fiber yarn wound around the inner shell, increase the fiber volume content of the FRP outer shell to be formed, and improve the pressure resistance.

In addition, according to the method for producing a gas cylinder of the present invention, since both ends of the inner shell can be reliably and firmly supported at the time of molding the outer shell by filament winding, the outer shell molding conditions can be set in a wider range. The desired gas cylinder can be manufactured easily and at low cost.

[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 a vertical cross-sectional view showing a state before forming an outer shell of the gas cylinder of FIG.

3 is an end view of the inner shell of the gas cylinder of FIG. 1. FIG.

4 is an enlarged perspective view of a boss of the gas cylinder of FIG.

FIG. 5 is an end view of the inner shell of the gas cylinder according to another embodiment of the present invention.

FIG. 6 is an end view of an inner shell of a gas cylinder according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Gas Cylinder 2, 21, 31 Inner Shell 2a Neck of Inner Shell 3 Outer Shell 4 Nozzle Mounting Base 5 Nozzle 6 Boss 6a Umbrella 6b Hole 7 Reinforcing Layer 8, 22, 32 Concave 9, 33 Column

Claims (8)

[Claims] 1. A gas cylinder having an inner shell having a gas barrier property, a pressure-resistant outer shell provided so as to cover the inner shell, and a boss provided at the bottom of the inner shell. The gas cylinder, wherein the bottom portion and the boss are attached to each other via a polygonal surface. 2. The gas cylinder according to claim 1, wherein the boss is engaged with a recess formed in a bottom portion of the inner shell. 3. The gas cylinder according to claim 1, wherein the boss is attached to a column body that is erected on the bottom of the inner shell. 4. The gas cylinder according to claim 1, wherein a concave portion is formed in a bottom portion of the inner shell, and a column body extending in the axial direction of the cylinder into the boss is provided upright in the concave portion. 5. The cross-sectional shape of the recess is polygonal.
The gas cylinder according to claim 2 or 4. 6. The cross-sectional shape of the columnar body is polygonal.
The gas cylinder according to claim 3 or 4. 7. The gas cylinder according to claim 1, wherein the inner shell is made of plastic and the outer shell is made of FRP. 8. A nozzle mounting mouthpiece is provided on a neck portion of an inner shell having gas barrier properties, and a boss attached to the bottom portion through a polygonal surface is provided, and the inner shell is supported on both sides by the mouthpiece and the boss. However, a method of manufacturing a gas cylinder, characterized in that a pressure-resistant FRP outer shell is formed around the inner shell by a filament winding method.