Hydrogen tank

Abstract

To allow visual inspection for foreign matter inclusion at a liner that constitutes a hydrogen tank.SOLUTION: A hydrogen tank includes a liner. The liner includes: a cylindrical part; and dome parts respectively disposed in both ends of the cylindrical part. The dome part includes: a body; and a junction part joined to the cylindrical part. The junction part of the dome part includes a part provided with a dark color. The body has light transmissivity that is higher than that of the junction part.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a hydrogen tank for storing hydrogen.

Background Art

[0002] Patent Document 1 discloses manufacturing a liner by welding three parts, namely a dome member, a body, and the dome member, at two locations.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although it is conceivable to join the dome member and the body by laser welding, since the material constituting the dome member absorbs the energy of the laser and generates heat, it is necessary to make it black. However, making it black makes it difficult to visually inspect for foreign matter contamination in terms of appearance.

[0005] In view of the above problems, an object of the present disclosure is to enable visual inspection for foreign matter contamination in a liner constituting a hydrogen tank.

Means for Solving the Problems

[0006] The present application discloses a hydrogen tank including a liner, the liner including a cylindrical portion and dome portions respectively disposed at both ends of the cylindrical portion, the dome portion having a main body and a joint portion joined to the cylindrical portion, the joint portion of the dome portion having a portion with a dark color, and the main body having higher translucency than the joint portion.

[0007] The joint may be configured such that a thin film portion, along the circumference of which a dark-colored portion extends annularly, is provided, and the thin film portion contacts the cylindrical portion and is joined to the cylindrical portion.

[0008] The joint has a first annular portion, a second annular portion provided on the cylindrical portion side of the first annular portion and having an outer diameter smaller than that of the first annular portion, and an inclined portion is provided on the first annular portion such that the diameter decreases toward the second annular portion, and the cylindrical portion and the dome portion may be configured to be joined at least at the inclined portion of the first annular portion.

Advantages of the Invention

[0009] According to the present disclosure, since the main body of the dome portion has higher translucency than the joint portion, visual inspection for foreign matter in the liner becomes possible. On the other hand, since the dome portion and the cylindrical portion are joined at the joint portion having a dark-colored portion, sufficient joint quality can be obtained even when joined by laser welding.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 9

Embodiments for Carrying Out the Invention

[0011] 1. Basic Structure of Hydrogen Tank The present disclosure is characterized by a liner included in a hydrogen tank. Before explaining the characteristics of the liner, the basic structure of the hydrogen tank including the liner as one member will be explained. The hydrogen tank 1 is a container for storing hydrogen as fuel in a liquid state or a gaseous state. Figures for explanation are shown in FIGS. 1 and 2. FIG. 1 is an external view, and FIG. 2 is a cross-sectional view along the direction of the axis O of the hydrogen tank 1. As can be seen from these figures, in this embodiment, the hydrogen tank 1 has a liner 10, a reinforcing layer 2, a base 3, and an opening / closing valve 4. Each configuration will be described below.

[0012] 1.1. Liner Here, an overview of the liner 10 is shown, and details will be described later. The liner 10 is a hollow member that partitions the internal space of the hydrogen tank 1 and is cylindrical in this embodiment. The liner 10 has a cylindrical portion 11 that is cylindrical with a generally constant diameter, and dome-shaped dome portions 12 that are arranged to cover each of the openings at both ends of the cylindrical portion 11. The side of the dome portion 12 opposite to the cylindrical portion 11 is dome-shaped, so that the diameter is narrowed, and the base 3 is arranged at the opening 12a formed at the narrowed end.

[0013] 1.2. Reinforcing Layer The reinforcing layer 2 has fibers laminated over a plurality of layers, and the fibers are impregnated with a cured resin. The layer of fibers is formed by winding fiber bundles around the outer periphery of the liner 10 over a plurality of layers to a predetermined thickness. The thickness of the reinforcing layer 2 and the number of windings of the fiber bundles are not particularly limited because they are determined by the required strength, but are about 10 mm to 30 mm.

[0014] <Fiber Bundle> For example, carbon fibers are used for the fiber bundles of the reinforcing layer 13, and the fiber bundles are in a band shape in which carbon fibers are bundled and have a predetermined cross-sectional shape (for example, a rectangular cross-section). Specifically, although not particularly limited, the cross-sectional shape may be a rectangle with a width of 6 mm to 20 mm and a thickness of about 0.1 mm to 0.3 mm. The amount of carbon fibers contained in the fiber bundle is not particularly limited either, but for example, it may be composed of about 36,000 carbon fibers.

[0015] <Impregnated resin> The resin impregnated and cured in the fibers (fiber bundles) in the reinforcing layer 2 is not particularly limited as long as it can enhance the strength of the fibers. Examples of this include thermosetting resins that cure by heat, and specifically, epoxy resins, unsaturated polyester resins, etc. that contain amine-based or anhydride-based curing accelerators and rubber-based reinforcing agents. In addition, resin compositions that cure by mixing a curing agent with an epoxy resin as the main component can also be mentioned. According to this, by allowing the resin composition, which is this mixture, to reach and penetrate the fiber layer between mixing the main component and the curing agent until curing, it cures automatically.

[0016] <Protective layer> If necessary, a protective layer may be arranged on the outer periphery of the reinforcing layer. When provided, for example, glass fibers are wound and resin is impregnated therein. The resin to be impregnated can be considered in the same way as the reinforcing layer 12. Thereby, impact resistance can be imparted to the hydrogen tank 1. The thickness of the protective layer is not particularly limited, but can be about 1.0 mm to 1.5 mm.

[0017] 1.3. Base The base 3 is a member attached to each of the two openings 12a of the liner 10, and is disposed at each of the two axial ends of the liner 10 in the direction of the axis O. The base 3 functions as an opening for communicating the inside and outside of the hydrogen tank 1, and an on-off valve 4 is attached to one side thereof. Therefore, the base 3 is provided with a circular cross-section hole for disposing the on-off valve 4. The inner surface of the hole is provided with a female thread corresponding to the male thread of the on-off valve 4. By combining the male thread of the on-off valve 4 with this female thread, the on-off valve 4 is fixed to the base 3. Further, the inner surface of the hole has a sealing surface that is a smooth surface on the inner side (high-pressure side) of the tank from the female thread. A sealing member provided on the outer periphery of the on-off valve 4 contacts this sealing surface, and airtightness (sealing) of the inside of the hydrogen tank 1 is achieved.

[0018] The members constituting the base 3 are not particularly limited as long as they have the required strength, and examples include stainless steel and aluminum.

[0019] 1.4. On-Off Valve The on-off valve 4 is held in the hole of the base 3 so as to pass through the inside and outside of the hydrogen tank 1. The on-off valve 4 is disposed on one of the two bases 3 provided at both longitudinal ends of the hydrogen tank 1. A plug 3a is disposed on the other base 3 and is sealed. The on-off valve 4 has a shaft portion disposed inside the hole of the base 3, and the outer peripheral surface of the shaft portion is provided with a male thread that is combined with the female thread of the base 3, whereby the on-off valve 4 is fixed to the hole of the base 3. A sealing member (not shown) is disposed on the outer peripheral surface of the on-off valve 4, and this sealing member is disposed so as to contact the sealing surface of the inner surface of the hole of the base 3 to achieve airtightness (sealing). The on-off valve 4 is a valve that switches between allowing and restricting the extraction of hydrogen from the hydrogen tank 1. The specific form of the on-off valve is not particularly limited, and a known on-off valve can be applied.

[0020] 2. Liner The liner will be described in detail below. FIG. 3 shows the liner 10 from the same perspective as FIG. 2. Further, FIG. 4 shows the liner 10 with the cylindrical portion 11 and the dome portion 12 separated. The liner 10 has the cylindrical portion 11 and the dome portion 12 prepared separately, and the dome portion 12 is joined (laser welded) to the entire circumference of the cylindrical portion 11 so as to cover the respective openings at the ends of the cylindrical portion 11 (the dotted line W in FIG. 3 is the joining site). Therefore, in this embodiment, the joining portion of each of the following embodiments is provided at the portion where the cylindrical portion 11 is joined to the dome portion 12 on the dome portion 12 side.

[0021] 2.1. Embodiment 1 2.1.1. Cylindrical portion The cylindrical portion 11 is a main part of the liner 10 for storing hydrogen inside, and is a cylindrical member having a substantially constant diameter. The material constituting the cylindrical portion 11 is not particularly limited as long as it can be joined to the dome portion 12 by laser welding. For example, a material in which polyamide resin is laminated on each of both sides of an ethylene vinyl alcohol copolymer resin and which consists of three layers can be mentioned. The thickness of the cylindrical portion 11 is not particularly limited, but is typically 0.5 mm to 3.0 mm. Such a cylindrical portion 11 can be produced, for example, by extrusion molding.

[0022] 2.1.2. Dome portion The dome portion 12 is a member that is disposed at each of the open ends of the cylindrical portion 11, is disposed so as to cover the opening, and is joined to the entire circumference of the cylindrical portion 11. The diameter of the side of the dome portion 12 opposite to the side joined to the cylindrical portion 11 is narrowed, and an opening 12a is formed at the narrowed end. The base 3 is disposed at this opening 12a. Here, the material constituting the dome portion 12 is not particularly limited as long as it can be joined to the cylindrical portion 11 by laser welding. For example, it can be formed of polyamide resin and can be manufactured by injection molding.

[0023] As described above, the dome portion 12 has a joint portion 14 which is a portion joined to the cylindrical portion 11. That is, the dome portion 12 has a main body 13 which is a main portion of the dome portion 12 (a portion other than the joint portion 14), and a joint portion 14 disposed at an end portion on the cylindrical portion 11 side of the main body 13.

[0024] Fig. 5 shows an enlarged view of the end portion of the main body 13 and the joint portion 14 continuous therewith at the portion indicated by I in Fig. 3. Although Figs. 5 and the following figures are cross-sections, hatching is omitted for ease of viewing.

[0025] In this embodiment, the joint portion 14 has a base portion 14a and a dark-colored portion 14b. The base portion 14a is a portion provided in an annular shape along the end face of the main body 13, and is formed continuously and integrally with the main body 13. Therefore, the base portion 14a is formed of the same material as the main body 13.

[0026] In this embodiment, the inner diameter of the base portion 14a is flush with that of the main body 13 without a step, and the outer diameter is smaller than that of the main body 13. Thereby, a step 13a is formed with the main body 13. The outer diameter of the base portion 14a is not particularly limited, but it is preferably about the same as or slightly smaller than the inner diameter of the cylindrical portion 11. And the depth of the step 13a is not particularly limited, but it is preferably about the same as the wall thickness of the cylindrical portion 11. Thereby, when the cylindrical portion 11 is fitted into the step 13a, the outer diameter of the main body 13 and the outer diameter of the cylindrical portion 11 are substantially flush.

[0027] The dark-colored portion 14b is a layer with a dark color provided along the outer peripheral surface of the base portion 14a. The meaning of "dark color" will be described later. The thickness of the dark-colored portion 14b is not particularly limited, but it may be a thickness that can absorb laser energy, generate heat, and be appropriately welded, and is typically 10 μm or more and 100 μm or less.

[0028] Regarding the dark color in the dark-colored portion 14b, it is considered as follows. When comparing the base portion 14a and the dark-colored portion 14b, the base portion 14a is configured to have a higher light transmittance (transparency) than the dark-colored portion 14b. The light transmittance can be determined, for example, by comparing the total light transmittance. This is the ratio of the amount of light that has passed through the object to the amount of light that has passed through the space when there is no object, with the latter being set as 100%. According to this, with respect to the base portion 14a, light can easily pass through, enabling visual inspection for foreign objects in the liner. As a result, expensive equipment such as X-rays or destructive inspections can be omitted or reduced. Also, since inspection can be performed non-destructively, it becomes possible to conduct a full inspection of all products. During inspection, because of the good light transmittance, using a light source to transmit light makes the inspection even easier.

[0029] On the other hand, the cylindrical portion 11 is fitted so that the inner peripheral surface at its end overlaps with the outer peripheral surface (i.e., the dark-colored portion 14b) of the joint portion 14 of the dome portion 12. Then, as indicated by the arrow L in FIG. 5, the dark-colored portion 14b is irradiated with a laser from the outside. At this time, since it is difficult for light to pass through the dark-colored portion 14b, if the dark-colored portion 14b is irradiated with laser light, the laser energy is easily absorbed by the dark-colored portion 14b, generating heat and melting the surrounding resin, enabling efficient welding. Thus, according to this embodiment, it is possible to achieve both easy inspection and high-quality welding.

[0030] However, in order to make this effect more prominent, the base portion 14a is preferably a light color such as transparent or milky white (a color with low lightness, for example, 7 or more out of 0 to 10 in the Munsell color system). Transparent means that in the property of a substance through which light passes, the light transmittance is high, and objects existing on the other side can be seen faintly through the substance. According to this, the ease of visual inspection can be enhanced. If it is not transparent, it becomes possible to further facilitate visual inspection by shining light from the back side.

[0031] On the other hand, in order to make the effect of the dark-colored portion 14b more prominent, it is preferably a color with low lightness, more preferably black. For example, it can be 5 or less out of 0 to 10 in the Munsell color system. As the specific dark-colored portion 14b, for example, a material obtained by adding a black pigment such as carbon black to a resin (such as a polyamide resin) can be formed by applying it to the base portion 14a.

[0032] FIG. 6 shows a diagram for explaining a modified example of the above-described embodiment 1. FIG. 6 is a diagram from the same viewpoint as FIG. 5. In this example, a dark-colored portion 14'b is used instead of the above-described dark-colored portion 14b. Since other parts can be considered in the same way as above, the same reference numerals are given and the description is omitted.

[0033] The dark-colored portion 14'b is arranged so as to wind a thin annular member around the outer periphery of the base portion 14a. The color of the annular member constituting the dark-colored portion 14'b can be considered in the same way as the above-described dark-colored portion 14b. The annular member may be formed by molding a strip-shaped material obtained by adding a black pigment such as carbon black to a resin (such as a polyamide resin), and then winding this around the base portion 14a.

[0034] By providing such a dark-colored portion 14'b, the same effects as above can be achieved.

[0035] 2.2. Embodiment 2 FIGS. 7 to 9 show diagrams for explaining Embodiment 2. FIGS. 7 to 9 are all diagrams from the same viewpoint as FIG. 5. FIG. 8 is a modified example of FIG. 7, and FIG. 9 is another modified example of FIG. 8. In Embodiment 2, the shape of the joint portion is different from that in Embodiment 1, but other parts can be considered in the same way as in Embodiment 1, so the description is omitted here. Hereinafter, the joint portion will be described.

[0036] As shown in FIG. 7, in this embodiment, the joint portion 24 has a base portion 24a and a dark-colored portion 24b. The base portion 24a is a portion provided in an annular shape along the end face of the main body 13, and is formed continuously and integrally with the main body 13. Therefore, the base portion 24a is formed of the same material as the main body 13.

[0037] In this embodiment, the base portion 24a has a first annular portion 241a disposed at a position on the main body 13 side and a second annular portion 242a disposed on the side opposite to the main body 13 side of the first annular portion 241a. The inner diameters of both the first annular portion 241a and the second annular portion 242a are flush with the main body 13 without a step. On the other hand, regarding the outer diameter, the first annular portion 241a has the same outer diameter as the main body 13 on the main body 13 side, but has an inclined surface such that the outer diameter decreases toward the second annular portion 242a. And on the second annular portion 242a side of the first annular portion 241a, it is made the same as the outer diameter of the second annular portion 242a. The inclination angle of the inclined surface is preferably 15 degrees or more and 75 degrees or less with respect to the axis O. More preferably, it is 30 degrees or more and 60 degrees or less. If the inclination angle is larger than 75 degrees, the force required for fitting the cylindrical portion 11 and the dome portion 12 tends to become too large. On the other hand, if the inclination angle is smaller than 15 degrees, the length for press-fitting during the fitting tends to become long, leading to an extension of the processing time and an increase in the amount of material. On the other hand, the outer diameter of the second annular portion 242a is not particularly limited, but it is preferably approximately the same as or slightly smaller than the inner diameter of the cylindrical portion 11. And the difference between the outer diameter of the second annular portion 242a and the outer diameter of the main body 13 is not particularly limited, but it is preferably approximately the same as the wall thickness of the cylindrical portion 11. Thereby, when the cylindrical portion 11 is fitted into the joint portion 24, the outer diameter of the main body 13 and the outer diameter of the cylindrical portion 11 are substantially flush.

[0038] In this embodiment, the dark-colored portion 24b is a dark-colored layer provided along the outer peripheral surface of the base portion 24a. The mode and effect of the dark-colored portion 24b can be considered in the same way as the above-described dark-colored portion 14b.

[0039] According to such a joint portion 24, in addition to the effects described in the above-described Embodiment 1, the fitting between the cylindrical portion 11 and the dome portion 12 can be firmly performed. For example, when there is no first annular portion, it becomes a form as shown in FIG. 5 described in Embodiment 1, but an arcuate portion (R shape) is formed at the corner portion of the step 13a to prevent stress concentration. Due to the presence of this R shape, a gap is formed between the opposing end surfaces of the main body 13 and the cylindrical portion 11 as shown in FIG. 5. In contrast, according to the second embodiment, since the gap can be eliminated and the cylindrical portion 11 and the dome portion 12 can be fitted together, it is possible to improve the strength during deformation and prevent the impregnating resin of the reinforcing layer 2 from entering. Further, since a load can be applied in the direction along the axis O as indicated by the arrow F during joining, it becomes easier to control the surface pressure when welding the inclined surface, and the welding quality can be stabilized. Also, when there is a gap, the liner becomes thin at that portion, so the hydrogen permeation amount can also be reduced by eliminating the gap.

[0040] The example shown in FIG. 8 is a modified example of the example shown in FIG. 7, and is an example in which the dark-colored portion 24'b is arranged only in the first annular portion 241a. From the viewpoint of joining strength, it is preferable that the dark-colored portion 24b is arranged and joined to both the first annular portion 241a and the second annular portion 242a as shown in FIG. 7. However, if sufficient strength can be ensured, from the viewpoint of productivity, the dark-colored portion 24'b may be provided only in the first annular portion 241a in this way.

[0041] The example shown in FIG. 9 is a modified example of the example shown in FIG. 8. In the example shown in FIG. 9, the end portion of the cylindrical portion 11 is not subjected to end processing along the inclination of the first annular portion 241a. Even in such a form, the above-described effects can be obtained. According to this example, since the end processing of the cylindrical portion 11 is not required, the number of steps can be reduced.

Explanation of Reference Numerals

[0042] 1... hydrogen tank, 2... reinforcing layer, 3... base, 4... on-off valve, 10... liner, 11... cylindrical portion, 12... dome portion, 13... main body, 14, 24... joint portion, 14a, 24a... base portion, 14b, 24b... dark-colored portion, 241a... first annular portion, 242a... second annular portion

Claims

1. A hydrogen tank comprising a liner, wherein the liner comprises a cylindrical portion, and dome portions disposed at both ends of the cylindrical portion, the dome portion having a main body and a joint portion joined to the cylindrical portion, the joint portion of the dome portion having a portion with a dark color, and the main body being more translucent than the joint portion, a hydrogen tank.

2. The joint portion is provided with a thin film portion along its circumference, in which the portion with the dark color extends annularly, the thin film portion being in contact with the cylindrical portion and joined to the cylindrical portion, The hydrogen tank according to Claim 1.

3. The joint portion has a first annular portion, and a second annular portion provided on the cylindrical portion side of the first annular portion and having an outer diameter smaller than that of the first annular portion, the first annular portion being provided with an inclined portion whose diameter becomes smaller toward the second annular portion, the cylindrical portion and the dome portion being joined at least at the inclined portion of the first annular portion, The hydrogen tank according to Claim 1 or 2.

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