KR101655719B1 - Fuel gas tank and manufacturing method its - Google Patents

Abstract

The present invention relates to a tank for safely storing high pressure gaseous fuel and a method of manufacturing the tank.
The present invention realizes a new type of fuel gas storage tank in which the rigidity of the liner in the circumferential direction and the radial direction is enhanced by integrally molding the metal liner body with the metal coil during the injection / extrusion molding of the polymer liner body, It is possible to prevent buckling caused by the pressurization of the permeated fuel gas while forming a porous layer such as a gas diffusion layer at the interface between the composite material and the polymer liner to temporarily permeate the permeated gas The present invention also provides a fuel gas storage tank and a method of manufacturing the fuel gas storage tank, which can eliminate the generation of explosion noise due to the instantaneous discharge, such that the permeated gas can naturally move and discharge through the bubbles in the porous layer.

Description

Technical Field [0001] The present invention relates to a fuel gas storage tank,

The present invention relates to a fuel gas storage tank and a method of manufacturing the same, and more particularly, to a tank for safely storing high-pressure gaseous fuel and a method of manufacturing the same.

Generally, the structure of a storage system differs depending on the storage method of the fuel gas in an alternative fuel gas vehicle such as a fuel cell vehicle or a compressed natural gas vehicle.

At present, compression gas type storage systems are attracting attention in consideration of the unit price, weight and simplicity of the storage system.

However, gaseous fuels have low energy storage densities and require more storage or increased storage pressure to achieve greater travel.

In the case of vehicles, since the space for installing the gas storage system is limited, there is a limit to increase the size of the storage tank. Therefore, storing the higher-pressure gas safely is the key to the tank technology.

In the case of composite fuel tanks in fuel gas storage tanks, reinforcement is made of fiber-reinforced composite materials with high strength and non-rigidity in order to withstand internal pressure due to compressed gas, and a liner do.

The fuel gas storage tank is classified into a type in which the liner material is divided, a type in which a metal liner such as aluminum is inserted, and a type in which a high-density polymer liner is inserted.

Here, in the case of a type in which a metallic material liner is inserted, the safety can be relatively increased, but it is expensive and the endothelial property is deteriorated.

FIG. 5 shows a conventional fuel gas storage tank with a high-density polymer liner inserted therein. Reference numeral 100 denotes a composite material, and reference numeral 110 denotes a polymer liner.

In the case of the type in which the high-density polymer liner is inserted, the price is relatively inexpensive and the endothelial property is excellent, but there is a problem of safety such as poor permeation resistance of hydrogen.

In particular, as shown in FIG. 5, the permeated gas stays at the interface between the polymer liner 110 and the composite material 100, separating the composite layer and the polymer liner layer when the tank pressure is lowered due to gas consumption , The instant release of the tank to the tank boss at such a separate interface may create a sense of panic to the driver or may cause gas to leak out of the tank through the flow path in the composite.

Also, there is a case where the permeation gas staying at the interface presses the polymer liner 110 inward and buckles as shown in Fig.

BACKGROUND ART [0002] Techniques that serve as the background of the present invention are disclosed in Japanese Patent Application Laid-Open Nos. 2005-273724, 2013-0032186, and 2004-347042.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a new type of fuel gas storage tank which is strengthened in the liner circumferential direction and the radial direction by integrally molding the metal liner body with the metal coil during injection / And it is an object of the present invention to provide a fuel gas storage tank and a method of manufacturing the same that can prevent a space from being generated between a composite material and a polymer liner and prevent a buckling phenomenon by pressurized permeated fuel gas.

Another object of the present invention is to provide a porous layer such as a gas diffusion layer at the interface between the composite material and the polymer liner to temporarily store the permeated gas and to allow the permeated gas to flow naturally between the bubbles in the porous layer And a method of manufacturing the fuel gas storage tank and a method of manufacturing the fuel gas storage tank that can exclude the occurrence of explosion noise due to the instantaneous discharge as in the past.

In order to achieve the above object, the fuel gas storage tank provided in the present invention has the following features.

The fuel gas storage tank includes a composite material forming a tank shell and a liner inserted into the composite material. A metallic coil is integrally formed in the liner to increase the rigidity in the circumferential direction and the radial direction .

Therefore, the fuel gas storage tank is characterized in that the rigidity with respect to the circumferential direction and the radial direction of the liner can be enhanced through the built-in metal coil integral structure.

The metal coils integrally formed with the liner may be inserted into the liner injection molding or injection molding to be integrally formed together. A metal coil integrally molded with the liner may be formed on the liner body.

The fuel gas storage tank may further include a gas diffusion layer formed at an interface between the composite material and the liner so that natural diffusion and movement of the gas can be performed and released to the outside.

In order to achieve the above object, a method of manufacturing a fuel gas storage tank according to the present invention has the following features.

The method of manufacturing the fuel gas storage tank includes the steps of: forming a liner having a metal coil integral type in which a metal coil is embedded using an injection or extrusion mold; molding the composite material on the liner surface of a metal coil integral type using filament winding equipment Step < / RTI >

Here, in the step before the step of forming the composite material on the surface of the liner with the metal coil integrated body, a process of foaming and forming the porous layer material on the surface of the liner integrated with the metal coil using the foam mold to form the gas diffusion layer have.

The step of forming the liner with the metal coil integrated type may include a process of forming a liner body part of a metal coil integrated type in which a metal coil is embedded using an injection or extrusion mold and a liner dome part having a metal boss- And laminating the liner body portion and the liner dome portion to each other.

In addition, it is preferable to carry out a process of forming a residual stress between the composite material and the liner through autofrettage in the step of forming the composite material on the surface of the liner with the metal coil integrated body, It is preferable that the step of forming the composite material on the surface of the liner of the liner does not completely cover the bosses on both ends of the liner when the composite material is molded.

The fuel gas storage tank and the manufacturing method provided by the present invention have the following effects.

1) Increasing the rigidity of the liner

- It is possible to prevent trapping of the fuel gas that permeates the liner and remains in the peeling space by removing the peeling space between the liner and composites which is a conventional problem by the mutual residual stress between the metal coil and the composite layer.

- circumferential rigid reinforcement of the liner can prevent liner buckling by the trapped gas in the liner-composite release area.

2) Emission of permeated fuel gas

- By forming a gas diffusion layer composed of a porous layer material at the liner-composite interface, the fuel gas permeating through the liner wall can naturally move to both end bosses of the tank through the flow path between the pores and the pores in the gas diffusion layer, have.

- The permeate gas remaining in the liner-composite separating space is instantly discharged to the boss to generate an explosive sound, or it can be prevented from leaking to the tank surface while being discharged through the composite flow path.

1 is a cross-sectional view showing a fuel gas storage tank according to an embodiment of the present invention;
2 is a schematic view showing a stress curve and a close contact structure between a composite material layer and a polymer liner in a fuel gas storage tank according to an embodiment of the present invention;
3 is a cross-sectional view showing a state of permeated gas discharge in a fuel gas storage tank according to an embodiment of the present invention
4 is a schematic view showing a method of manufacturing a fuel gas storage tank according to an embodiment of the present invention.
5 is a cross-sectional view showing a conventional fuel gas storage tank
6 is a photograph showing a buckling phenomenon of a conventional fuel gas storage tank

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a fuel gas storage tank according to an embodiment of the present invention.

As shown in FIG. 1, the fuel gas storage tank is constructed by integrally incorporating a coil-shaped metal reinforcement member in the body of the polymer liner to strengthen the rigidity, thereby preventing peeling between different kinds of material interfaces such as a tube shape .

For this purpose, the fuel gas storage tank includes a composite material 10 constituting the outer surface of the tank and a liner 11 made of a polymer material inserted into the composite material 10.

The composite material 10 and the liner 11 are joined to each other in two layers on the outer side and the inner side to form a single tank shape, thereby providing a space for safely storing high-pressure fuel gas.

Particularly, the metal coil 12, for example, a metal coil 12 made of a metal coil spring is embedded in the liner 11 to increase the rigidity of the liner 11 in the circumferential direction and the radial direction You can give.

At this time, the metal coil 12 can be made of various materials such as aluminum and stainless steel considering elongation and yield strength.

The metal coil 12 is integrally formed with the metal coil 12 by injection molding or injection molding of the liner 11. The metal coil 12 is integrally formed and inserted into the liner body 11 of the liner 11 11a in a concentric circle, and can be integrally embedded in the body without being exposed to the outside.

In the case of the liner 11, the liner body 11a and the liner dome 11b are integrally formed. In this case, the liner body 11a and the liner dome 11b are formed by injection molding or extrusion molding It is possible to form an integral liner in the form of fusion bonding with each other.

Since the metal coil 12 is integrated in the liner 11, the rigidity in the circumferential direction and the radial direction of the liner 11 can be improved.

In place of the metal coil 12, a thin metal film in the form of a tube may be inserted to form a sandwich. In this case, peeling between the polymer and the metal layer may occur due to the difference in permeability between the materials.

However, in the case of the metal coil 12 according to the present invention, it is possible to induce the permeated hydrogen to smoothly escape between the coils, that is, between the polymer base material (base material) while the rigidity is complemented.

Thus, large-scale peeling between the interfaces of dissimilar materials such as the tube shape does not occur.

A gas diffusion layer 13 is formed at an interface between the composite material 10 and the liner 11. The gas diffusion layer 13 is formed in such a manner that the gas permeated through the liner 11 is diffused and moved So that it can be discharged to the outside.

For example, a gas diffusion layer 13 made of a porous layer material such as polyurethane foam is formed at the interface between the composite material 10 and the liner 11, and a gas introduced into the gas diffusion layer 13 at this time, that is, 11 is temporarily stored in the porous layer of the gas diffusion layer 12, and is diffused and moved naturally through the pores in the porous layer, so that the gas can be discharged to the outside.

2 is a schematic view showing a stress curve and a close contact structure between a composite material layer and a polymer liner in a fuel gas storage tank according to an embodiment of the present invention.

2, the metal coil 12 is integrally formed on the body 11a of the polymer liner 11 during injection / extrusion to increase the rigidity with respect to the liner circumferential direction and the radial direction, The residual stress between the composite material 10 and the liner 11 is reduced through autofrettage after the filament winding of the front surface of the composite material 10, that is, the liner 11 and the composite material 10 are formed as inner and outer layers. Respectively.

As a result, tensile stress is generated in the composite material 10, compressive stress is generated in the liner 11, and mutual repulsive stress acts on the two layers, so that no space is generated in the interface.

In addition, even when the metal coil 12 in the compressive stress state is elongated during charging, the stress is increased in the negative (-) state, so that the maximum stress can be controlled within the yield strength, thereby increasing the durability.

In the case of the coil to be inserted at this time, it is possible to use various metal materials in consideration of elongation and yield strength.

3 is a cross-sectional view illustrating a state of permeated gas discharge in a fuel gas storage tank according to an embodiment of the present invention.

As shown in FIG. 3, the structure of the fuel gas storage tank is shown here, and the structure in which the polymer liner layer, the gas diffusion layer, and the composite material layer are disposed from the inside to the outside is shown.

The fuel gas permeates through the polymer liner layer and flows into the gas diffusion layer by the internal pressure of the fuel gas. The fuel gas thus temporarily collected in the gas diffusion layer passes through the space between the bubbles in the porous layer of the gas diffusion layer and diffuses, (Direction of the boss in the liner dome portion) and can be discharged to the outside.

As the permeated fuel gas is continuously discharged, the explosion noise due to the instantaneous discharge is not generated, and the composite material layer is not discharged to the outside of the tank, thereby avoiding the misunderstanding of gas leakage.

4 is a schematic view showing a method of manufacturing a fuel gas storage tank according to an embodiment of the present invention.

As shown in Fig. 4, here, a method of molding a metal coil integral liner and a composite material constituting a fuel gas storage tank is shown.

The gas diffusion layer 13 may be formed by a foaming method and the composite material 10 may be formed by a filament winding method. In this case, the liner 11 may be formed by injection molding or extrusion, Extruder 15, foaming mold 17 and filament winding equipment 16 used in the extrusion, extrusion, extrusion, extrusion, extrusion, extrusion, extrusion, extrusion, The detailed description thereof will be omitted.

First, a step of molding a metal coil integral liner 11 having a metal coil 12 therein is carried out by using an injection or extrusion mold 14 and an injection / extruder 15.

That is, when the liner 11 is molded, the metal coil 12 is inserted into the mold together with the metal coil 12 to form an integral liner 11 having the metal coil 12 embedded therein.

At this time, the step of forming the liner with the metal coil integral type is performed by molding the liner body portion 11a of the metal coil integrated type in which the metal coil 12 is embedded using the injection or extrusion mold 14, A metal boss-integrated liner dome portion 11b in which a metal boss (not shown) is embedded is molded using the mold 14 and then a liner dome portion 11b is formed at both ends of the thus formed liner body portion 11a And fusing and joining them.

Next, the porous layer material is foam-molded on the surface of the liner of the metal coil integrated type using the foam mold 17 as a (pre) step before the step of molding the composite material 10 on the liner surface of the metallic coil integrated body to be described later Thereby forming a gas diffusion layer 13.

That is, after forming the liner, the porous layer material may be applied to the entire outer surface to temporarily store the gas in the porous layer. In order to naturally diffuse and move through the pores in the porous layer, a space corresponding to the thickness of the gas diffusion layer 13 A liner is placed in a foam mold and the material such as a polyurethane foam is foamed.

Since the gas diffusion layer is compressed by the filament winding tension during the forming of the composite material, the gas flow path can be clogged. Therefore, rigidity can be reinforced by incorporating an appropriate reinforcing material such as glass fiber into the porous layer material in consideration of the winding tension.

In this step, it is possible to prevent the bosses on both ends of the liner from being completely covered when the composite material is molded.

That is, the gas diffusion layer must be completely foamed to the boss portions at both ends of the tank, and the transferred gas may be released to the outer surface of the gas diffusion layer so that the resin does not completely cover both boss portions when the composite material is molded.

Here, the temperature of the tank, which is raised at the time of filling by the effect of the tank warming due to the application of the gas diffusion layer, can be reduced by pre-cooling charging.

Next, the step of molding the composite material 10 on the liner surface of the metal coil integral type is performed using the filament winding equipment 16.

That is, the composite material can be formed by winding the resin impregnated reinforcing fiber on the outer circumferential surface of the gas diffusion layer 13 using the filament winding equipment 16.

After the step of forming the composite material on the surface of the liner having the metal coil integrated body, a process of autofrettage is performed to form a residual stress between the composite material and the liner.

Accordingly, the fuel gas storage tank manufactured by the above-described manufacturing method can compensate the liner rigidity through the integral metal coil, and natural gas discharge can be achieved through the liner outer surface diffusion layer.

For example, in the past, a liner was made of only one material such as a metal material and a polymer. However, the present invention provides a hybrid liner combining the advantages of a metal material and a polymer.

That is, by using a polymer as a base material and using a metal coil as a reinforcing material, the endurance characteristics of the deficient metal liner can be complemented by the polymer base material, and the rigidity of the relatively inadequate polymer liner can be supplemented by the metal coil.

In addition, in the case of a liner having a conventional polymer liner inserted therein, attempts were made to bond both layers to prevent peeling between the liner and the composite material. However, the adhesive layer separation due to fatigue and the fuel gas penetrate into the separated interface, There was a problem that it spread rapidly.

In order to prevent the problems of the conventional technology, it is possible to prevent the interface peeling by integrally forming the metal coil with the liner and introducing a self-treatment technique.

In the case of the inserted metal reinforcement, the fuel gas is permeated through the polymer layer serving as the base material in a coil shape different from the shape of the metal tube, so that large-scale separation between the different materials due to the gas can be avoided.

In the case of a tank having an existing polymer liner, the interface between the polymer liner and the composite material is usually peeled off due to the problem of bonding between the different materials. The fuel gas permeated in the thickness direction of the polymer liner stays in this separation space, , Making explosive noises or escaping through the composite flowpaths and being mistaken for gas leaks.

In order to prevent this, an adhesive is applied to the surface of the liner during molding to prevent trapping of the fuel gas by attempting to bond with the composite material, or locally releasing material is inserted between the liner and the composite material layer, There is a method in which the generated flow path is led to be discharged toward both bosses. However, in the case of the adhesive treatment, there is a disadvantage in that the adhesive layer is easily broken by fatigue due to charge and discharge. There is a disadvantage that it is possible to provide a starting point of peeling at the time of destruction.

In the present invention, a gas diffusion layer is formed between the liner and the composite material so that the permeated gas is rapidly diffused through the pores and pores in the diffusion layer, and the diffused gas is allowed to escape to both end bosses of the tank.

In this case, since the permeated gas does not remain between the interfaces and continuously escapes through the pores in the diffusion layer, explosion noise is not generated and the gas is discharged through the diffusion layer before the gas is discharged into the composite composite flow path, It can be prevented from being mistaken as leakage of the tank due to leakage.

As described above, according to the present invention, by forming the gas diffusion layer at the interface between the metallic coil and the composite material in the liner, the removal of the release layer and the buckling can be prevented by reinforcing the liner rigidity, So that it can be discharged naturally to the outside.

10: Composite
11: Liner
11a: liner body part
11b: liner dome portion
12: Metal coil
13: gas diffusion layer
14: injection / extrusion mold
15: Injection / Extruder
16: Filament winding equipment
17: foam mold

Claims (5)

Molding a metal coil integral liner in which a metal coil is embedded using an injection or extrusion mold;
A method of manufacturing a fuel gas storage tank, comprising: forming a composite material on a liner surface of a metal coil integral type using filament winding equipment,
A step of forming a gas diffusion layer by foaming and forming a porous layer material on the surface of a liner of a metal coil integral type using a foam mold in a step before a step of molding a composite material on the surface of the liner of the metal coil integrated type,
Wherein a porous layer material in which a reinforcing material for retaining the porous layer structure is injected is inserted into the foamed mold against the winding tension of the composite material.
The method according to claim 1,
The step of forming the liner with the metal coil integral type may include a process of forming a liner body part of a metal coil integral type in which a metal coil is embedded by using an injection or extrusion mold and a process of molding a liner dome part of a metal boss- And fusing and bonding the liner body and the liner dome.
The method according to claim 1,
And a step of forming a residual stress between the composite material and the liner through autofrettage in the step of forming the composite material on the surface of the liner of the metal-coil integrated type, .
The method according to claim 1,
Wherein the step of forming the composite material on the surface of the liner of the metal-coil integrated type is performed so that the bosses on both ends of the liner are not completely covered when the composite material is molded.
The method according to claim 1,
Wherein the reinforcing material is glass fiber.

Images