tank

Abstract

To provide a tank capable of appropriately securing the joint strength of a liner construction member.SOLUTION: A tank includes a liner at least part of which is constructed by joining a plurality of cylindrical construction members, and a reinforcing layer arranged on the outer periphery of the liner, the plurality of liner construction members each including a first liner construction member having a first joint part, and a second liner construction member having a second joint part, the first joint part having a plurality of resin layers, the first joint part having the lowest layer as a heat deposition layer including absorbent, the second joint part including absorbent, the first joint part being layered on the second joint part, the first joint part and the second joint part being joined to each other via the heat deposition part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This application relates to a tank.

Background Art

[0002] Regarding high-pressure gas tanks for storing hydrogen gas and the like, a tank in which a reinforcing layer is disposed on a hollow cylindrical liner is known. Such a tank is described in, for example, Patent Document 1.

[0003] Patent Document 1 discloses a gas container having a resin liner formed by joining a plurality of liner constituent members at least part of which is in a hollow cylindrical shape, and a reinforcing layer disposed on the outer periphery of the resin liner, wherein the joints of the plurality of liner constituent members are joined to each other by laser welding. Further, in this document, laser welding is performed in a state where a laser transmissive liner constituent member and a laser absorptive liner constituent member are in contact with each other, and the laser absorptive liner constituent member is heated and melted, and the laser transmissive liner constituent member is thermally melted by heat transfer from the laser absorptive liner constituent member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, the laser transmissive liner constituent member does not contain an absorbent. Therefore, the laser transmissive liner constituent member is melted only by heat transfer from the laser absorptive liner constituent member, and these liner constituent members are joined.

[0006] However, according to the inventors' findings, such welding methods may result in insufficient melting of the heat-welded area that joins the liner components, potentially failing to ensure sufficient adhesive strength. Furthermore, extending the laser welding time to ensure sufficient melting can lead to overheating of the laser-absorbing liner components, causing problems such as burning and voids due to gasification in the heat-welded area.

[0007] Therefore, the main purpose of this disclosure is to provide a tank that can appropriately ensure the bonding strength of the liner components, in light of the above circumstances. [Means for solving the problem]

[0008] This disclosure provides at least the following aspects:

[0009] The first embodiment is a tank having a liner formed by joining together a plurality of liner components that are at least partially cylindrical, and a reinforcing layer arranged on the outer circumference of the liner, wherein the plurality of liner components comprises a first liner component having a first joint and a second liner component having a second joint, the first joint having a plurality of resin layers, the bottom layer of the first joint being a heat-welded layer containing an absorbent, the second joint containing an absorbent, the first joint being laminated on the second joint, and the first joint and the second joint being joined by a heat-welded portion.

[0010] The second embodiment is a tank in which, in the first embodiment, the laser absorption rate of the bottom layer of the first joint is 0.3 or more and 0.6 or less, and the laser absorption rate of the second joint is 0.9 or more and 1.0 or less.

[0011] A third aspect is the tank described in the first or second aspect, wherein the first joint comprises a gas barrier layer, a heat-welded layer, and a bottom layer, and the heat-welded layer is positioned between the gas barrier layer and the bottom layer. [Effects of the Invention]

[0012] According to the tank of this disclosure, the bonding strength of the liner components can be appropriately ensured. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view of tank 100. [Figure 2] This is an enlarged view of the joint between the first liner component 110 and the second liner component 120. [Figure 3] This shows the relationship between the carbon black content in the resin layer and the laser absorption rate. [Modes for carrying out the invention]

[0014] The tank of this disclosure will be described using tank 1000, which is one embodiment.

[0015] [Tank 1000] Tank 1000 is capable of being filled with gas. The type of gas is not particularly limited. Examples include hydrogen and natural gas. The gas is usually filled into the tank body 100 under high pressure.

[0016] Figure 1 shows a cross-sectional view of the tank 1000. The tank 1000 has a liner 100 and a reinforcing layer 200 arranged on the outer circumference of the liner 100. The tank 1000 also has a nozzle 300 at its axial end (along the central axis O of the tank 1000).

[0017] <Lina 100> The liner 100 is made of a resin having gas barrier properties. The liner 100 is made by joining together a plurality of liner components that are at least partially cylindrical. Liner components that are at least partially (one end) cylindrical include, for example, those in which the liner component as a whole has a cylindrical, annular, bowl-shaped, dome-shaped, or the like.

[0018] As shown in Fig. 1, the liner 100 has a first liner component 110 and second liner components 120, 120. The first liner component 110 has a cylindrical shape and is the so-called body portion of the liner 100. The second liner component 120 has a dome portion 121 and a small-diameter end portion 122. The dome portion 121 has a dome shape and a shape that tapers toward the outside in the axial direction. The small-diameter end portion 122 has a cylindrical shape with a smaller diameter than the second liner component 120. The small-diameter end portion 122 has an opening on the outer surface in the axial direction, and the opening communicates with the inside of the liner 100. Through this opening, gas filling and discharging are carried out. As shown in Fig. 1, the second liner components 120 are respectively arranged at both axial ends of the first liner component 110.

[0019] Using Fig. 2, the configurations of the first liner component 110 and the second liner component 120 will be further described. Fig. 2 shows an enlarged view of the joint portion between the first liner component 110 and the second liner component 120.

[0020] (The first liner component 110) The first liner component 110 has laser transmissivity. "Laser transmissivity" means the property of transmitting a part of the irradiated laser. For example, the laser absorption rate of the first liner component 110 may be 0.2 or more and less than 0.8. From the viewpoint of transmitting the laser and ensuring the melting amount, the laser absorption rate of the first liner component 110 may be 0.3 or more and 0.6 or less. The laser absorption rate indicates the ratio of the laser absorbed by the material to the laser input. The laser absorption rate can be calculated by irradiating the laser light on the target material and measuring the transmitted part with a detector. Such measurement can be carried out with known measuring equipment.

[0021] As shown in Fig. 2, the first liner component 110 includes four resin layers (the first resin layer 111 to the fourth resin layer 114). The thickness of the first liner component 110 is not particularly limited, but from the viewpoint of ensuring laser transmissivity, for example, it may be 400 μm or more and 2 mm or less, and may be 500 μm or more and 1 mm or less.

[0022] The first resin layer 111 is the outermost resin layer (the uppermost layer) and is a protective layer. The material of the first resin layer 111 is not particularly limited, and examples thereof include thermoplastic resins such as polyethylene, polypropylene, and polyamide. The thickness of the first resin layer 111 is not particularly limited, but may be, for example, 80 μm or more and 500 μm or less. The laser absorption rate of the first resin layer 111 is not particularly limited, but may be, for example, 0.2 or less, 0.1 or less, 0.05 or less, or even 0.

[0023] The second resin layer 112 is a gas barrier layer disposed inside the first resin layer 111. The material of the second resin layer 112 is not particularly limited as long as it is a resin having gas barrier properties. Examples thereof include biaxially stretched polyethylene, polypropylene, polyvinylidene chloride, ethylene vinyl alcohol copolymer resin, and the like. The thickness of the second resin layer 112 is not particularly limited, but from the viewpoint of ensuring sufficient gas barrier properties, it may be 80 μm or more and 500 μm or less, or 150 μm or more and 300 μm or less. The laser absorption rate of the second resin layer 112 is not particularly limited, but may be, for example, 0.2 or less, 0.1 or less, 0.05 or less, or even 0.

[0024] The third resin layer 113 is a resin layer disposed inside the second resin layer 112 and is a heat-sealing layer having a role of protecting the second resin layer 112 from the melting of the fourth resin layer 114. Therefore, the third resin layer 113 is disposed between the second resin layer 112 and the fourth resin layer 114. The material of the third resin layer 111 is not particularly limited, and examples thereof include thermoplastic resins such as polyethylene, polypropylene, and polyamide. The thickness of the third resin layer 113 is not particularly limited, but may be, for example, 80 μm or more and 500 μm or less. The laser absorption rate of the third resin layer 113 is not particularly limited, but may be, for example, 0.2 or less, 0.1 or less, 0.05 or less, or even 0.

[0025] The fourth resin layer 114 is the innermost resin layer (bottom layer) and is a heat-welded layer containing an absorbent. The fourth resin layer 114 has a thermoplastic resin and an absorbent. The fourth resin layer 114 may consist of a thermoplastic resin and an absorbent. Thus, of the resin layers constituting the first liner component 110, only the bottom layer, the fourth resin layer 114, contains an absorbent. The thermoplastic resin constituting the fourth resin layer 114 is not particularly limited. Examples include polyethylene, polypropylene, and polyamide. The absorbent can be any material capable of absorbing lasers. For example, carbon materials such as carbon black can be used. The content of the absorbent in the fourth resin layer 114 may be adjusted as appropriate to achieve the desired laser absorption rate. The laser absorption rate of the fourth resin layer 114 is not particularly limited, but for example, it is 0.3 or more and 0.6 or less. From the viewpoint of adjusting the amount of melting, the laser absorption rate of the fourth resin layer 114 may be 0.4 or more and 0.5 or less. The thickness of the fourth resin layer 114 is not particularly limited, but from the viewpoint of ensuring a sufficient amount of melted resin, it may be 80 μm to 500 μm, or 150 μm to 300 μm.

[0026] Figure 3 shows, as an example, the relationship between the carbon black content (weight %) and the laser absorptivity in a resin layer in which carbon black is mixed with polyamide resin. According to Figure 3, when carbon materials such as carbon black are used as absorbents, the carbon material content in the fourth resin layer 114 may be 0.006% by weight or more and 0.023% by weight or less. From the viewpoint of adjusting the amount of melting, the carbon material content in the fourth resin layer 114 may be 0.011% by weight or more and 0.017% by weight or less.

[0027] Here, as shown in Figure 2, the first liner component 110 is laminated on the second liner component 120. Specifically, the first liner component 110 is laminated so as to be positioned outside the second liner component 120. Laser welding is performed on this laminated portion. Therefore, the portion of the first liner component 110 that comes into contact with the second liner component 120 (the second joint portion 120a described later) is designated as the first joint portion 110a. That is, the first liner component 110 has a first joint portion 110a for joining with the second liner component 120 (the second joint portion 120a). The first joint portion 120a extends circumferentially.

[0028] (Second liner component 120) The second liner component 120 has laser-absorbing properties. "Laser-absorbing properties" means the property of absorbing almost all or all of the irradiated laser. For example, the laser absorption rate of the second liner component 120 may be 0.8 or more and 1.0 or less. From the viewpoint of absorbing more laser, the laser absorption rate of the second liner component 120 may be 0.9 or more and 1.0 or less.

[0029] The second liner component 120 is a heat-welded layer containing an absorbent material. It comprises a thermoplastic resin and an absorbent material. The second resin layer 120 may consist of a thermoplastic resin and an absorbent material. The thermoplastic resin constituting the second liner component 120 is not particularly limited. Examples include polyethylene, polypropylene, and polyamide. The absorbent material can be any material capable of absorbing lasers. Examples include carbon materials such as carbon black. The content of the absorbent material in the second liner component 120 may be adjusted as appropriate to achieve the desired laser absorption rate. The thickness of the second liner component 120 is not particularly limited, but from the viewpoint of ensuring sufficient melting amount and gas barrier properties, it may be 500 μm or more and 5 mm or less, or 800 μm or more and 3 mm or less.

[0030] Furthermore, as shown in Figure 3, when carbon materials such as carbon black are used as absorbents, the carbon material content in the second liner component 120 may be 0.034% by weight or more. From the viewpoint of adjusting the amount of melting, the carbon material content in the second liner component 120 may be 0.039% by weight or more.

[0031] As shown in Figure 2, the second liner component 120 has a projection (second joint 120a) that protrudes axially inward from below its axially inward surface. The second joint 120a is the part for joining with the first joint 110a. The second joint 120a exists circumferentially. The axial length of the second joint 120a is not particularly limited as long as it is long enough to form a sufficient heat-welded portion. For example, it may be 5 mm or more and 20 mm or less. The thickness of the second joint 120a is not particularly limited, but from the viewpoint of ensuring a sufficient amount of melting, it may be 80 μm or more and 5 mm or less, or 150 μm or more and 3 mm or less.

[0032] (Joining of the first joint 110a and the second joint 120a) As shown in Figure 2, the first liner component 110 is positioned abutting against the second liner component 120 such that the inner surface (bottom surface) of the first joint 110a in the stacking direction contacts the outer surface (top surface) of the second joint 120a in the stacking direction. At this time, the outer surface (top surface) of the first liner component 110 in the stacking direction and the outer surface (top surface) of the second liner component 120 in the stacking direction may be flush. This is to facilitate the placement of the reinforcing layer 200. However, there may be a step between the outer surface of the first liner component 110 and the outer surface of the second liner component 120.

[0033] Furthermore, the first joint 110a is laminated onto the second joint 120a, and these are joined by a heat-welded portion 130. The heat-welded portion 130 is formed in the circumferential direction. In Figure 2, there is one heat-welded portion 130, but there may be multiple. In that case, the multiple heat-welded portions 130 may be formed side by side in the axial direction. The axial length of the heat-welded portion 130 is not particularly limited, but from the viewpoint of ensuring gas barrier properties and joint strength, it may be 1 mm to 5 mm, or 2 mm to 4 mm.

[0034] (Formation of heat-welded portion 130) An enlarged view of the heat-welded portion 130 is shown at the bottom of Figure 2. The heat-welded portion 130 is formed by laser welding. Since the laser L is irradiated from the outside of the liner 100, the laser-transparent first joint portion 110a is laminated on the laser-absorbing second joint portion 120a. When the laser L is irradiated, the laser L passes through the first joint portion 110a and reaches the second joint portion 120a. The laser L that reaches the second joint portion 120a melts a part of the second joint portion 120a (the irradiated part). This melted part is designated as the second joint side heat-welded portion 132. In addition, since the fourth resin layer 114 of the first joint portion 110a contains an absorbent material, the fourth resin layer 114 absorbs a part of the laser L, and a part of the fourth resin layer 114 (the irradiated part) melts. This melted part is designated as the first joint side heat-welded portion 131. Then, the heat-welded portion 131 on the first joint side and the heat-welded portion 132 on the second joint side are joined together, forming the heat-welded portion 130.

[0035] The bonding strength of the heat-welded portion 130 is influenced by the amount of melting of the first joint-side heat-welded portion 131 and the second joint-side heat-welded portion 132. The amount of melting refers to the depth of the heat-welded portion. The amount of melting of the first joint-side heat-welded portion 131 and the second joint-side heat-welded portion 132 is set considering the bonding strength of the heat-welded portion 130 and the number of heat-welded portions 130. For example, from the viewpoint of increasing bonding strength, the amount of melting of the first joint-side heat-welded portion 131 may be 40 μm or more and 300 μm or less, or 60 μm or more and 150 μm or less. Similarly, the amount of melting of the second joint-side heat-welded portion 132 may be 40 μm or more and 300 μm or less, or 60 μm or more and 150 μm or less. If the amount of melting is less than 40 μm, there is a risk that the bonding strength will not be sufficient. However, even if the amount of melting is less than 40 μm, sufficient bonding strength can be obtained by increasing the number of heat-welded portions 130. If the amount of melting exceeds 300 μm, the amount of melting becomes excessive and may affect other layers. For example, if the heat-welded portion 130 reaches the second resin layer 112, the thickness of the second resin layer 112 may change or the material state may change, potentially reducing the gas barrier properties. The amount of melting in the heat-welded portion 131 on the first joint side and the amount of melting in the heat-welded portion 132 on the second joint side may be the same or different.

[0036] (Method of manufacturing Liner 100) The method for manufacturing the liner 100 is not particularly limited, but for example, it can be manufactured as follows. First, the first liner component 110 and the second liner components 120, 120 are manufactured. The method for manufacturing the first liner component 110 is not particularly limited, but from the viewpoint of easily manufacturing the first liner component 110 having multiple resin layers, extrusion molding may be used. The method for manufacturing the first liner component 110 is not particularly limited, but from the viewpoint of easily manufacturing the dome portion 121 and the small diameter end portion 122, injection molding may be used. Next, one opening of the obtained first liner component 110 and the opening on the dome portion 121 side of the second liner component 120 are placed facing each other and butted together as shown in Figure 2. Then, laser welding is performed. This allows the liner 100 to be manufactured.

[0037] <Reinforcement layer 200> The reinforcing layer 200 covers the entire outer surface of the liner 10 and is a component that ensures the strength of the tank 1000. The reinforcing layer 200 is formed from a fiber-reinforced resin such as carbon fiber. Typically, the reinforcing layer 200 is formed by weaving a fiber bundle, which is made by bundling multiple fiber-reinforced resin strands together, onto the surface of the liner 100. The reinforcing layer 200 can be formed, for example, using a braiding method.

[0038] <300 nozzle> The nozzle 300 is a cylindrical member positioned at the small-diameter end of the tank 1000 (corresponding to the small-diameter end 122), and serves to connect the tank 1000 to other components (e.g., manifolds and valve components). The nozzle 300 is made of a metal such as stainless steel. Such nozzles 300 are well known.

[0039] <Supplement> The tank of this disclosure has been described above using one embodiment. Further details about the tank of this disclosure are provided below.

[0040] In one embodiment, the liner 100 is composed of a cylindrical first liner component 110 and second liner components 120, 120 having dome portions. However, the tank of this disclosure is not limited thereto. For example, the liner may be composed of two liner components having dome portions. In this case, one liner component may be designated as the first liner component and the other as the second liner component.

[0041] In one embodiment, both second liner components 120, 120 are provided with small-diameter ends 122. However, the tank of this disclosure is not limited thereto. For example, only one second liner component may have a small-diameter end, while the other second liner component does not.

[0042] In one embodiment, the first liner component 110 has four resin layers. However, the tank of this disclosure is not limited to this. The first liner component 110 may have multiple resin layers. For example, the first liner component may be composed of three resin layers. In this case, the first liner component may have a protective layer, a gas barrier layer, and a bottom layer (a heat-sealed layer including an absorbent material) in this order. However, in this case, since there is no heat-sealed layer between the gas barrier layer and the bottom layer, the outer part of the bottom layer may be heated, potentially degrading the gas barrier layer. Also, in the case of a three-layer configuration, the bottom layer may be formed relatively thickly, which may reduce the energy of the laser reaching the second joint. In that case, it is necessary to increase the laser output. On the other hand, when the first liner component has a three-layer configuration, the manufacturing equipment and the like can be simplified compared to when it has a four-layer configuration.

[0043] In one embodiment, the first liner component 110 had a plurality of resin layers as a whole. However, the tank of this disclosure is not limited thereto. For example, the first liner component only needs to have a plurality of resin layers at the first joint, and the configuration of the other parts is not particularly limited. However, from the viewpoint of ease of manufacture, the first liner component may be composed of a plurality of resin layers as a whole.

[0044] In one embodiment, the second liner component 120 as a whole is composed of an absorbent material formed from a heat-welded layer. However, the tank of this disclosure is not limited thereto. For example, the second liner component may be composed of a thermoplastic resin layer containing an absorbent material only at the second joint, and the composition of the other parts is not particularly limited. However, from the viewpoint of ease of manufacture, the second liner component may be composed of a thermoplastic resin layer containing an absorbent material as a whole. [Examples]

[0045] The tank described herein will be further explained using examples.

[0046] Following the above description, liners for Examples 1 and 2 and the Comparative Example were fabricated. Laser welding was performed using a commercially available semiconductor laser welding machine. The welding conditions were: output 180W, laser wavelength 940nm, and focal diameter 3mm.

[0047] Table 1 shows the liner configurations of Examples 1 and 2 and the Comparative Example. As shown in Table 1, the first liner component of Example 1 has four resin layers. The first liner component of Example 2 has three resin layers. The first liner component of the Comparative Example also has three resin layers. As shown in Table 1, Examples 1 and 2 have an absorbent material (CB) in the bottom layer of the first liner component. In contrast, the Comparative Example does not have an absorbent material in the bottom layer of the first liner component.

[0048] Here, we will explain the materials shown in Table 1. PA stands for polyamide. EVOH stands for ethylene vinyl alcohol copolymer resin. PA with CB stands for a mixture of polyamide resin and carbon black. The numbers in parentheses are the laser absorptivity.

[0049] Table 1 also shows the amount of melting in the heat-welded areas formed by laser welding (the amount of melting in the heat-welded area on the first joint side and the amount of melting in the heat-welded area on the second joint side). The amount of melting was measured from a microscopic image of the cross-section after cutting the heat-welded area of ​​each test example.

[0050] Furthermore, the bonding strength (peel strength) of the liners in Examples 1 and 2 and the Comparative Example was tested. The bonding strength test was carried out as follows: First, strip-shaped test pieces including the heat-welded portion were cut from each test example in which the first liner component and the second liner component were welded together. Next, the unwelded portions of the first liner component and the second liner component were grasped using a strength testing device, and the heat-welded portion was peeled off by pulling each component in a 90-degree direction. The load per unit length of the heat-welded portion at that time was measured and defined as the bonding strength (N / mm). The results are shown in Table 1.

[0051] [Table 1]

[0052] Table 1 shows that the joint strength of Examples 1 and 2 was sufficiently secured. This is thought to be because the bottom layer of the first liner component of Examples 1 and 2 contained CB, an absorbent material, and therefore the amount of melting in the heat-welded portion on the first joint side was sufficiently deep. On the other hand, the joint strength of the Comparative Example was low. This is thought to be because the bottom layer of the first liner component of the Comparative Example did not contain CB, an absorbent material, and therefore the amount of melting in the heat-welded portion on the first joint side was not sufficiently deep. [Explanation of Symbols]

[0053] 100 Raina 110 First liner component 110a 1st joint 111 1st resin layer (protective layer) 112 Second resin layer (gas barrier layer) 113 Third resin layer (thermal welding layer) 114. Fourth resin layer (bottom layer: heat-sealed layer containing absorbent material) 120 Second liner component 120a Second joint 121 Dome section 122 Small diameter end 130 Heat welding part 131 First joint side heat welding part 132 2nd joint side heat welding part 200 reinforcement layers 300 nozzle 1000 tanks

Claims

1. A liner that is constructed by joining together multiple liner components, at least in part, which are cylindrical. The liner has a reinforcing layer disposed on its outer circumference, The multiple liner components are, A first liner component having a first joint, A second liner component having a second joint portion, The first joint portion has a plurality of resin layers, The bottom layer of the first joint is a heat-welded layer containing an absorbent, The second joint contains an absorbent, The first joint is laminated onto the second joint, The first joint and the second joint are joined by a heat-welded joint. Of the plurality of resin layers constituting the first joint, only the bottom layer contains the absorbent. The laser absorption rate of the bottommost layer of the first joint is 0.3 or more and 0.6 or less. The laser absorption rate of the second junction is 0.9 or more and 1.0 or less. tank.

2. The first joint comprises a gas barrier layer, a heat-welded layer, and the bottom layer. The heat-welded layer is positioned between the gas barrier layer and the bottom layer. The tank according to claim 1.

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