High pressure tank and method of manufacturing the same

Abstract

The present invention relates to a high-pressure tank and a manufacturing method thereof. The technology disclosed in the present specification is embodied by a high-pressure tank having a shape in which dome portions are provided at both ends of a cylindrical portion that stores a high-pressure fluid. The high-pressure tank is provided with: an inner FRP layer composed of a fiber-reinforced material; an outer FRP layer located outside the inner FRP layer, composed of a fiber-reinforced material; and a bonding layer provided at least at the cylindrical portion between the inner FRP layer and the outer FRP layer. The bonding layer has: an inner bonding layer in contact with the inner FRP layer; an outer bonding layer in contact with the outer FRP layer; and a barrier layer located between the inner bonding layer and the outer bonding layer, and having higher barrier properties than the inner FRP layer and the outer FRP layer.

Description

Technical Field

[0001] The technology disclosed in this specification relates to high-pressure tanks for storing high-pressure fluids and methods for manufacturing the same. Background Technology

[0002] Japanese Patent Application Publication No. 2021-119034 discloses a high-pressure vessel with dome-shaped openings at both ends of a cylindrical portion. The high-pressure vessel comprises an inner FRP layer made of fiber-reinforced resin (referred to as a reinforcing body in Japanese Patent Application Publication No. 2021-119034) and an outer FRP layer made of fiber-reinforced resin located outside the inner FRP layer (referred to as a further reinforcing layer in Japanese Patent Application Publication No. 2021-119034).

[0003] When a high-pressure vessel is filled with or released from a high-pressure fluid, the internal pressure of the vessel changes significantly. This significant pressure change can cause deformation of the vessel. In particular, the cylindrical portion of a planar high-pressure vessel is more prone to deformation than the dome-shaped portion during filling and releasing of the high-pressure fluid. In the high-pressure vessel disclosed in Japanese Patent Application Publication No. 2021-119034, the movement of the fibers in the outer FRP layer is constrained by the adhesive force of the resin in the inner FRP layer. In such a high-pressure vessel structure, there is a concern that the inner and outer FRP layers may shift in the cylindrical portion when the vessel deforms during filling and releasing of the high-pressure fluid. This specification discloses a technique that can securely bond the inner and outer FRP layers in the cylindrical portion. Summary of the Invention

[0004] The technology disclosed in this specification is embodied in a high-pressure tank having dome-shaped ends on a cylindrical portion for storing high-pressure fluid. The high-pressure tank comprises: an inner FRP layer made of fiber-reinforced material; an outer FRP layer located outside the inner FRP layer and also made of fiber-reinforced material; and an adhesive layer disposed at least in the cylindrical portion between the inner and outer FRP layers, the adhesive layer comprising: an inner adhesive layer in contact with the inner FRP layer; an outer adhesive layer in contact with the outer FRP layer; and a barrier layer located between the inner and outer adhesive layers, having a barrier effect higher than that of both the inner and outer FRP layers.

[0005] According to the aforementioned high-pressure vessel, an adhesive layer is provided at least in the cylindrical portion between the inner and outer FRP layers to securely bond the inner and outer FRP layers. This prevents the inner and outer FRP layers from shifting when the cylindrical portion deforms due to changes in the internal pressure of the high-pressure vessel. Furthermore, the adhesive layer comprises: an inner adhesive layer in contact with the inner FRP layer; an outer adhesive layer in contact with the outer FRP layer; and a barrier layer located between the two FRP layers, having a higher barrier effect than both the inner and outer FRP layers. Therefore, for example, it is not necessary to provide a separate barrier layer, different from the adhesive layer, inside the inner FRP layer. The high-pressure vessel disclosed in this specification simplifies its manufacturing process.

[0006] Furthermore, this specification also discloses a method for manufacturing a high-pressure tank having dome-shaped ends at both ends of a cylindrical portion for storing high-pressure fluid. The high-pressure tank comprises: an inner FRP layer made of fiber-reinforced material; an outer FRP layer located outside the inner FRP layer and also made of the fiber-reinforced material; and an adhesive layer disposed at least in the cylindrical portion between the inner and outer FRP layers. The adhesive layer comprises: an inner adhesive layer in contact with the inner FRP layer; an outer adhesive layer in contact with the outer FRP layer; and a barrier layer located between the inner and outer adhesive layers, having a barrier effect higher than that of both the inner and outer FRP layers. The inner FRP layer comprises a first inner FRP layer located in the cylindrical portion and a second inner FRP layer located in the dome-shaped ends. Between the first and second inner FRP layers, the fiber material of the fiber-reinforced material is discontinuous. The manufacturing method described above includes the following steps: a first forming step, in which the first inner FRP layer is formed using the fiber-reinforcing material; a second forming step, in which the second inner FRP layer is formed using the fiber-reinforcing material; a bonding step, in which the formed first inner FRP layer and the second inner FRP layer are bonded together; an adhesive layer forming step, in which an adhesive layer is provided at least on the outer side of the first inner FRP layer before or after the bonding step; and a third forming step, in which an outer FRP layer is formed using the fiber-reinforcing material on the outer side of the bonded first inner FRP layer and the second inner FRP layer.

[0007] According to the manufacturing method described above, in the adhesive layer forming process performed before or after the bonding process, an adhesive layer is provided at least on the outer side of the first inner FRP layer. The adhesive layer has a barrier layer. Therefore, for example, compared to a structure in which the inner FRP layer is disposed on the outer peripheral surface of a barrier layer different from the adhesive layer and the adhesive layer is disposed on the outer side of the inner FRP layer, the barrier layer can be provided together with the inner and outer adhesive layers in the same process, thereby simplifying the process.

[0008] The detailed description of the technology disclosed in this specification and further improvements are described in the following "Detailed Description". Attached Figure Description

[0009] Hereinafter, the features, advantages, technical and industrial importance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same constituent elements, wherein:

[0010] Figure 1 A perspective view of the high-pressure tank 2 in the embodiment.

[0011] Figure 2 Indicates along Figure 1 Sectional view of line II-II.

[0012] Figure 3 This refers to the first forming step in the manufacturing method of the embodiment.

[0013] Figure 4 This refers to the second forming step in the manufacturing method of the embodiment.

[0014] Figure 5 The assembly step in the manufacturing method of the embodiment is shown.

[0015] Figure 6 The adhesive layer forming step and the third forming step are shown in the manufacturing method of the embodiment. Detailed Implementation

[0016] In one embodiment of this technology, the inner FRP layer may have a first inner FRP layer located in the cylindrical portion and a second inner FRP layer located in the dome. In this case, the fiber material of the fiber reinforcement material may be discontinuous between the first inner FRP layer and the second inner FRP layer. According to this structure, the first inner FRP layer and the second inner FRP layer can be formed independently. Therefore, for example, different amounts of fiber reinforcement material can be configured for each FRP layer in such a way that the fiber reinforcement material of the second inner FRP layer is more than that of the first inner FRP layer. Thus, appropriate amounts of fiber reinforcement material can be configured for the cylindrical portion and the dome, respectively. Furthermore, the first inner FRP layer and the second inner FRP layer can be securely connected by an outer FRP layer located outside the inner FRP layer.

[0017] In one embodiment of this technology, a portion of the adhesive layer may extend to the dome and be located between the second inner FRP layer and the outer FRP layer. With this structure, the first inner FRP layer and the second inner FRP layer of the inner FRP layer can be securely connected using the adhesive layer.

[0018] In one embodiment of this technology, a portion of the adhesive layer may extend to the dome and be located between the first inner FRP layer and the second inner FRP layer, where the boundaries of the cylindrical portion and the dome overlap. With this structure, the first inner FRP layer and the second inner FRP layer can be securely connected using the adhesive layer.

[0019] (Example)

[0020] Figure 1 This is a perspective view of the high-pressure tank 2 in an embodiment. The high-pressure tank 2 is, for example, mounted on a fuel cell vehicle (illustration omitted). The high-pressure tank 2 stores high-pressure hydrogen gas used by the fuel cell vehicle for power generation. That is, the high-pressure tank 2 is a tank for storing high-pressure fluid. Furthermore, the high-pressure fluid stored in the high-pressure tank 2 is not limited to hydrogen gas; for example, it could be a high-pressure liquid.

[0021] The high-pressure tank 2 has the following shape: a cylindrical portion 21 extending along the central axis CL, and dome-shaped tops 22 and 26 provided at both ends of the cylindrical portion 21. Hereinafter, the direction parallel to the central axis CL of the cylindrical portion 21 (i.e., the positive and negative directions of the Z-axis in the coordinate system of the figure) will be referred to as the axial direction.

[0022] The high-pressure vessel 2 comprises an inner FRP (Fiber Reinforced Plastics) layer 4, an outer FRP layer 6, and a metal inlet 8. Each FRP layer 4 and 6 is constructed by impregnating long carbon fiber filaments with a thermosetting resin (e.g., epoxy resin). That is, each FRP layer 4 and 6 is made of fiber-reinforced resin. The outer FRP layer 6 is located outside the inner FRP layer 4, covering the outer surface of the inner FRP layer 4. Furthermore, in a modified embodiment, a thermoplastic resin may be used instead of a thermosetting resin to impregnate the long carbon fiber filaments.

[0023] The metal opening 8 is a protrusion made of metal, located at one end of the dome 22 along its axial direction (i.e., Figure 1 (The right end of the vessel). The metal port 8 has a through hole that connects the interior of the high-pressure vessel 2 with the exterior. Hydrogen gas inside the high-pressure vessel 2 is released to the exterior through the through hole of the metal port 8, and hydrogen gas is supplied to the high-pressure vessel 2 from the exterior through the through hole of the metal port 8.

[0024] Reference Figure 2 The detailed structure of high-pressure tank 2 will be explained. Figure 2 It is along Figure 1 The cross-sectional view is shown in line II-II. The inner FRP layer 4 has a first inner FRP layer 41 and a second inner FRP layer 42. The first inner FRP layer 41 is located in the cylindrical portion 21 of the high-pressure tank 2 (see reference). Figure 1The second inner FRP layer 42 is located at the dome 22 of the high-pressure tank 2 (see reference). Figure 1 Details will be described later, but each inner FRP layer 41, 42 is formed in a separate filament winding process. Therefore, the filaments (i.e., fiber material) of each inner FRP layer 41, 42 are discontinuous.

[0025] The axial end of the first inner FRP layer 41 is located inside the second inner FRP layer 42 (i.e., on the side closest to the central axis CL). That is, the first inner FRP layer 41 extends axially to the dome 22. In other words, at the boundary B1 between the cylindrical portion 21 and the dome 22 of the high-pressure tank 2, the inner FRP layers 41 and 42 overlap each other.

[0026] An adhesive layer 10 is disposed between the inner FRP layer 4 and the outer FRP layer 6, covering a portion of the dome 22 and the cylindrical portion 21. The adhesive layer 10 bonds the inner FRP layer 4 and the outer FRP layer 6 together. The adhesive layer 10 is composed of a flat sheet.

[0027] like Figure 2 As shown in the enlarged view, the adhesive layer 10 has an inner adhesive layer 14, an outer adhesive layer 16, and a first barrier layer 15. Layers 14, 15, and 16 are stacked to form a sheet-like adhesive layer 10. In this embodiment, the inner adhesive layer 14 and the outer adhesive layer 16 are made of PP (polypropylene). The first barrier layer 15 in this embodiment is made of EVOH (ethylene-vinyl alcohol copolymer). The gas barrier properties of the first barrier layer 15 are higher than those of the FRP layers 4 and 6. Therefore, the first barrier layer 15 prevents hydrogen gas inside the high-pressure tank 2 from leaking to the outside.

[0028] In this embodiment, the high-pressure tank 2 securely bonds the inner FRP layer 4 and the outer FRP layer 6 together using the adhesive layer 10 at a portion of the dome 22 and the cylindrical portion 21. This prevents the inner FRP layer 4 and the outer FRP layer 6 from shifting relative to each other in the event of deformation of the cylindrical portion 21 due to changes in the internal pressure of the high-pressure tank 2. Furthermore, as previously described, the adhesive layer 10 includes a first barrier layer 15. Therefore, the high-pressure tank 2 does not require additional barrier layers located inside the inner FRP layer 4, such as conventional liner layers. Thus, compared to the existing process of forming additional barrier layers like liner layers and winding the inner FRP layer 4 around the outer periphery of the liner, the high-pressure tank 2 of this embodiment simplifies the manufacturing process.

[0029] Here, the required shape stiffness differs between the cylindrical portion 21 and the dome 22 of the high-pressure tank 2. For example, compared to the cylindrical portion 21, the dome 22, located around the metal inlet 8, is more prone to experiencing large axial loads during hydrogen release and filling. Furthermore, the cylindrical portion 21 is formed of a flat surface, thus the filaments do not overlap and can be easily wound uniformly around the entire outer circumference of the cylindrical portion 21. In contrast, the dome 22 is formed of a curved surface, so when filaments are wound around the entire surface of the dome 22, the filaments tend to overlap.

[0030] Here, for example, we assume a comparative example where the first inner FRP layer 41 and the second inner FRP layer 42 are integrally formed by filament winding. In this comparative example, if the required amount of filaments is wound around the entire surface of the second inner FRP layer 42 forming the dome 22 with filaments overlapping each other, the filaments wound around the first inner FRP layer 41 forming the cylindrical portion 21 also overlap each other. As a result, in this comparative example, there is a situation where the amount of filaments disposed in the first inner FRP layer 41 is excessively increased. In the high-pressure tank 2 of this embodiment, as previously described, each inner FRP layer 41, 42 is formed in a separate filament winding process. Therefore, the amount of carbon fiber filaments in each inner FRP layer 41, 42 can be set separately. As in the comparative example, the amount of filaments in the first inner FRP layer 41 forming the cylindrical portion 21 does not increase due to filament winding around the entire surface of the second inner FRP layer 42 forming the dome 22. It can wind an appropriate amount of filaments for each inner FRP layer 41, 42.

[0031] Furthermore, the outer FRP layer 6 is wrapped with carbon fiber filaments throughout the cylindrical portion 21 and the dome 22. Therefore, the high-pressure tank 2 can use the outer FRP layer 6 to firmly connect the independently constructed first inner FRP layer 41 and second inner FRP layer 42 together.

[0032] A second barrier layer 44 is provided on the inner side of the second inner FRP layer 42. The second barrier layer 44, like the first barrier layer 15, is made of EVOH sheet. In a modified example, the second barrier layer 44 can be formed, for example, by coating polyethylene on the inner side of the second inner FRP layer 42.

[0033] The axial end of the adhesive layer 10 extends beyond boundary B1 and lies on the outer surface of the second inner FRP layer 42. That is, a portion of the adhesive layer 10 extends to the dome 22 of the high-pressure tank 2. As a result, the adhesive layer 10 bonds the first inner FRP layer 41 and the second inner FRP layer 42 together. Thus, the separate first inner FRP layer 41 and second inner FRP layer 42 can be securely connected together.

[0034] Next, refer to Figures 3-6The manufacturing method of high-pressure tank 2 will now be explained. First, refer to... Figure 3 The first forming process will now be described. In the first forming process, filament F1 is wound onto the outer circumferential surface of a cylindrical first spool M1 using a so-called circumferential winding method called filament winding. For example... Figure 3 As shown in the left figure, in the first forming process, while the first spool M1 is rotated about the central axis CL in the rotational direction R1, the nozzle N1 reciprocates along the direction G1 parallel to the axial direction. This winds the filament F1 onto the outer circumferential surface of the first spool M1. The nozzle N1 repeatedly reciprocates along direction G1, thereby stacking multiple layers of filament F1 on the outer circumferential surface of the first spool M1.

[0035] After the fiber F1 is wound onto the outer circumference of the first spool M1, the fiber F1 is heated. This heating cures the thermosetting resin impregnated with the fiber F1. Then, the first spool M1 is removed from the cured fiber F1. Thus, as... Figure 3 As shown in the right figure, the first inner FRP layer 41 is formed.

[0036] Reference Figure 4 The second forming process will now be described. In the second forming process, filament F2 is wound onto the outer circumference of the second spool M2 using a so-called spiral winding method. The second spool M2 has an oblong shape when viewed from the side. The two ends of the second spool M2 are curved into dome shapes along the axial direction. A metal opening 8 is fixed at one end of the second spool M2 along the axial direction.

[0037] like Figure 4 As shown in the left figure, in the second forming process, while the second spool M2 is rotated about the central axis CL in the rotational direction R2, the nozzle N1 moves along a direction G2 that is inclined at an angle θ2 relative to the central axis CL. As a result, the filament F2 is wound around the outer peripheral surface of the second spool M2, which is bent into a dome shape. Here, the angle θ2 is set according to the shape of the curved surface of the second spool M2, the diameter of the filament F2, etc. The nozzle N2 repeatedly moves back and forth along direction G2, thereby stacking multiple layers of filament F2 on the outer peripheral surface of the second spool M2.

[0038] After the fiber F2 is wound onto the outer circumference of the second spool M2, the fiber F2 is heated to cure the thermosetting resin impregnated within it. Next, the cured fiber F2 is cut along the cutting line C1. The cut fiber F2 is then removed from the second spool M2. At this time, the metal nozzle 8 is also removed from the second spool M2 along with the fiber F2. Thus, as... Figure 4 As shown in the right figure, second inner FRP layers 42 and 46 are formed, curved into a dome shape. Then, sheet-like second barrier layers 44 and 48 are respectively attached to the inner peripheral surfaces of the formed second inner FRP layers 42 and 46.

[0039] Reference Figure 5 The joining process will now be explained. In the joining process, the second inner FRP layers 42 and 46 are assembled in direction J1 relative to both ends of the first inner FRP layer 41. At this time, as... Figure 5 As shown in the enlarged view above, the second inner FRP layer 42 is configured to cover the outer peripheral surface of the first inner FRP layer 41. In other words, during the bonding process, the first inner FRP layer 41 is inserted into the second inner FRP layer 42. Thus, at the end of the first inner FRP layer 41, the first inner FRP layer 41 overlaps with the second inner FRP layer 42.

[0040] Reference Figure 6 The adhesive layer forming process and the third forming process will be described below. In the adhesive layer forming process, a sheet-like adhesive layer 10 is wound around the outer peripheral surfaces of the first inner FRP layer 41 and the second inner FRP layers 42 and 46, which were assembled in the bonding process. (Refer to...) Figure 2 As explained, the adhesive layer 10 has an inner adhesive layer 14, an outer adhesive layer 16, and a first barrier layer 15.

[0041] Next, in the third forming process, filaments F3 are wound onto the outer peripheral surfaces of the first inner FRP layer 41, the second inner FRP layers 42 and 46, and the adhesive layer 10 (hereinafter referred to as the joint) using circumferential winding and helical winding methods. During the helical winding in the third forming process, while the joint is rotated about the central axis CL in the axial rotation direction R3, the nozzle N3 moves along a direction G3 inclined at a predetermined angle θ3 relative to the central axis CL. Here, the angle θ3 is set according to the shape of the joint, the diameter of the filaments F3, etc. Furthermore, in a modified example, in the third forming process, filaments F3 can be wound onto the outer peripheral surface of the joint solely by helical winding.

[0042] After the filament F3 is wound around the outer periphery of the joint in the third forming process, the filament F3 is heated. This heating cures the thermosetting resin impregnated with the filament F3. Thus, the high-pressure vessel 2 (see reference) is manufactured. Figure 1 ).

[0043] Furthermore, an adhesive layer 10 is provided between the inner FRP layer 4 and the outer FRP layer 6 in a portion of the domes 22 and 26 and the cylindrical portion 21, thus, particularly in the cylindrical portion 21, the FRP layers 4 and 6 can be firmly fixed. Moreover, although the adhesive layer 10 is only provided in a portion of the domes 22 and 26, the domes 22 and 26 have a curved shape and higher rigidity than the cylindrical portion 21. Therefore, even with changes in the internal pressure of the high-pressure tank 2, the domes 22 and 26 are less prone to deformation than the cylindrical portion 21. Therefore, the area of ​​the adhesive layer 10 can be reduced for the domes 22 and 26 compared to the cylindrical portion 21. This allows for a reduction in the size of the adhesive layer 10.

[0044] The specific examples of the technology disclosed in this specification have been described in detail above, but these are merely illustrative and do not limit the scope of protection claimed in this application. The technology described in the scope of protection claimed in this application includes technologies obtained through various modifications and variations of the specific examples illustrated above. The following are examples of variations of the above embodiments.

[0045] (Modification 1) The adhesive layer forming process can be performed before the bonding process. In this case, a portion of the adhesive layer 10 can be located between the first inner FRP layer 41 and the second inner FRP layer 42, which overlap at the boundary B1 of the cylindrical portion 21 and the dome 22. With this structure, the second barrier layer 44 is fixed to the outer adhesive layer 16, thereby enabling the first inner FRP layer 41 and the second inner FRP layer 42 to be securely bonded together.

[0046] (Modification 2) The inner adhesive layer 14 and the outer adhesive layer 16 can be made of epoxy resin instead of PP. In a further modification, the inner adhesive layer 14 and the outer adhesive layer 16 can be made of polyimide or thermoplastic polyester.

[0047] (Modification 3) Each barrier layer 15, 44, and 48 can also be made of nylon sheet instead of EVOH sheet. In a further modification, each barrier layer 15, 44, and 48 can be made of PET (Poly Ethylene Terephthalate) sheet. Additionally, the second barrier layer 44 can use the same sheet as the adhesive layer 10. That is, the second barrier layers 44 and 48 can have an inner adhesive layer 14 and an outer adhesive layer 16. With this structure, the first inner FRP layer 41 and the second inner FRP layer 42 can be further and more securely bonded together using the adhesive layers 14 and 16 of the second barrier layers 44 and 48.

[0048] The technical elements described in this specification or accompanying drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the technical solution at the time of application. Furthermore, the technologies illustrated in this specification or accompanying drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives is itself technically useful.

Claims

1. A high-pressure tank, having domed tops at both ends of a cylindrical section for storing high-pressure fluid, wherein, The high-pressure tank includes: The inner FRP layer is made of fiber-reinforced material; An outer FRP layer, located outside the inner FRP layer, is composed of the fiber-reinforced material; and An adhesive layer is disposed at least in the cylindrical portion between the inner FRP layer and the outer FRP layer. The adhesive layer has: An inner adhesive layer that contacts the inner FRP layer; An outer adhesive layer that is in contact with the outer FRP layer; A barrier layer is located between the inner adhesive layer and the outer adhesive layer, and has a higher barrier effect than both the inner and outer FRP layers. The inner FRP layer has a first inner FRP layer located in the cylindrical portion and a second inner FRP layer located in the dome. Between the first inner FRP layer and the second inner FRP layer, the fiber material of the fiber reinforcement material is discontinuous. The adhesive layer extends to the dome in a manner that does not cover the entire second inner FRP layer, and is located between the first inner FRP layer and the second inner FRP layer, where the boundaries of the cylindrical portion and the dome overlap.

2. A manufacturing method for producing a high-pressure tank having domed tops at both ends of a cylindrical portion for storing high-pressure fluid, wherein, The high-pressure tank includes: The inner FRP layer is made of fiber-reinforced material; An outer FRP layer, located outside the inner FRP layer, is composed of the fiber-reinforced material; and An adhesive layer is disposed at least in the cylindrical portion between the inner FRP layer and the outer FRP layer. The adhesive layer has: An inner adhesive layer that contacts the inner FRP layer; An outer adhesive layer that contacts the outer FRP layer; and A barrier layer is located between the inner adhesive layer and the outer adhesive layer, and has a higher barrier effect than both the inner and outer FRP layers. The inner FRP layer has a first inner FRP layer located in the cylindrical portion and a second inner FRP layer located in the dome. Between the first inner FRP layer and the second inner FRP layer, the fiber material of the fiber reinforcement material is discontinuous. The adhesive layer extends to the dome in a manner that does not cover the entire second inner FRP layer, and is located between the first inner FRP layer and the second inner FRP layer, where the boundaries of the cylindrical portion and the dome overlap. The manufacturing method comprises the following steps: The first forming process involves forming the first inner FRP layer using the fiber-reinforced material. The second forming process involves forming the second inner FRP layer using the fiber-reinforced material. The bonding process involves bonding the already formed first inner FRP layer and the second inner FRP layer together. In the adhesive layer forming process, before or after the bonding process, the adhesive layer is provided at least on the outer side of the first inner FRP layer; and In the third forming process, an outer FRP layer is formed on the outside of the already bonded first inner FRP layer and second inner FRP layer using the fiber-reinforcing material.

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