High-pressure tank, method for manufacturing a high-pressure tank

Abstract

To provide a high-pressure tank capable of suppressing liner deformation.SOLUTION: In a fiber bundle 12a arranged in the innermost layer to contact a liner 11, the fiber bundle is wound so that the widthwise edges overlap by at least 14% at adjacent fiber bundles.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a high-pressure tank having a layer wound with a fiber bundle impregnated with resin.

Background Art

[0002] A high-pressure tank used in a fuel cell vehicle or the like has a liner that forms the internal space of the high-pressure tank, and a reinforcing layer is formed by winding a fiber bundle impregnated with resin around the outer periphery of the liner, thereby realizing high strength.

[0003] Patent Document 1 describes a method for manufacturing a tank in which a reinforcing layer is formed by hoop winding and helical winding.

[0004] Patent Document 2 describes that in a high-pressure tank, when the fiber bundle spreads due to hoop winding or helical winding, it may accidentally overlap with adjacent fibers.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a conventional high-pressure tank, the liner may be deformed, and particularly, such deformation may be remarkable due to a change in the liner material or thinning due to weight reduction.

[0007] The present disclosure has been made in view of these circumstances, and an object thereof is to provide a high-pressure tank capable of suppressing deformation of the liner. Further, a method for manufacturing a high-pressure tank for this purpose is provided.

Means for Solving the Problem

[0008] The inventor obtained the finding that in the fiber bundle arranged closest to the liner side, a force difference occurs between the central portion and the end portion in the width direction, and the liner deforms due to this difference, and then embodied the means for solving the problem.

[0009] The present application discloses a high-pressure tank in which a belt-shaped fiber bundle is wound around a liner so as to form a plurality of layers. In the fiber bundle arranged in the innermost layer so as to be in contact with the liner, the high-pressure tank is wound so that the end portions in the width direction of adjacent fiber bundles overlap by 14% or more. Note that the innermost layer of the fiber bundle may be wound in a low-angle helical manner. Also, the liner may be formed of resin.

[0010] The present application also discloses a method for manufacturing a high-pressure tank having a step of winding a belt-shaped fiber bundle around a liner so as to form a plurality of layers. When winding the fiber bundle arranged in the innermost layer so as to be in contact with the liner, it is wound so that the end portions in the width direction of adjacent fiber bundles overlap by 14% or more. Note that the innermost layer of the fiber bundle may be wound in a low-angle helical manner. Also, the liner may be formed of resin.

Advantages of the Invention

[0011] According to the present disclosure, it is possible to suppress the force difference generated in the fiber bundle due to a part of adjacent fiber bundles overlapping, and it is possible to suppress the deformation of the liner.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0013] 1. Structure of high-pressure tank FIG. 1(a) schematically shows the appearance of a high-pressure tank 10 according to one embodiment, and FIG. 1(b) schematically shows a cross-section along the axis of the high-pressure tank 10. As can be seen from these figures, in this embodiment, the high-pressure tank 10 has a liner 11, a reinforcing layer 12, a protective layer 13, and a base 14. Each component will be described below.

[0014] 1.1. Liner The liner 11 is a hollow member that partitions the internal space of the high-pressure tank 10 and is cylindrical in this embodiment. In the liner 11, the openings at both ends of the body portion 11a having a generally constant diameter are narrowed by the dome-shaped side end portions 11b, and the base 14 is disposed at the narrowed openings 11c. The liner 11 may be made of a material that can hold the substance (for example, hydrogen) contained in its internal space without leakage, and known materials can be used. Specifically, for example, it is made of nylon resin, synthetic resin of polyethylene series, metal such as stainless steel or aluminum. The thickness of the liner 11 is not particularly limited, but is preferably 0.5 mm to 3.0 mm. Among them, from the viewpoint of weight reduction of the high-pressure tank, the material constituting the liner is preferably a synthetic resin, and its thickness is preferably 2.0 mm or less in the body portion. In a high-pressure tank equipped with such a weight-reduced liner, deformation of the liner was conventionally likely to appear significantly, but according to the high-pressure tank of the present disclosure, the deformation is suppressed to be small.

[0015] 1.2. Reinforcing layer The reinforcing layer 12 has fibers laminated over a plurality of layers, and the fibers are impregnated with a cured resin. The layer formed by the fibers is formed by winding fiber bundles 12a around the outer periphery of the liner 11 over a plurality of layers to a predetermined thickness. The thickness of the reinforcing layer 12 and the number of windings of the fiber bundles are not particularly limited as they are determined by the required strength, but the thickness is about 10 mm to 30 mm.

[0016] <Fiber bundle> For example, carbon fibers are used for the fiber bundles 12a of the reinforcing layer 12, 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 0.5 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.

[0017] <Impregnated resin> The resin impregnated and cured in the fibers (fiber bundles) in the reinforcing layer 12 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.

[0018] <Winding mode of fiber bundle> Next, the winding mode of the fiber bundle 12a around the liner 11 in the high-pressure tank 10 will be described. A diagram for explanation is shown in FIG. 2. FIG. 2 shows a part of the wound fiber bundle 12a for clarity. As described above, in the reinforcing layer 12, the fiber bundle 12a is wound around the outer periphery of the liner 11.

[0019] The winding modes of the fiber bundle 12a include hoop winding and helical winding, and the helical winding further includes low-angle helical winding and high-angle helical winding. The hoop winding is mainly applied to the body part as shown by A in FIG. 2, and is wound at an inclination angle α of 80° or more and 90° or less with respect to the axis L of the high-pressure tank 10. The hoop winding acts to wind up the relevant part and counteract the force that causes the liner 11 to expand radially outward due to gas pressure. On the other hand, the helical winding is mainly a winding method aimed at winding and tightening the side end part inward in the axial direction of the high-pressure tank. By winding the fiber bundle 12a around the liner 11 so as to catch on the side end part, the strength of the side end part is improved. The low-angle helical winding is mainly wound and applied so as to cross two side end parts existing on the opposite side as shown by B in FIG. 2, and is wound at an inclination angle α of 5° or more and 30° or less with respect to the axis L of the high-pressure tank 10. The high-angle helical winding is mainly wound and applied so as to cross the body part and the side end part as shown by C in FIG. 2, and is wound at an inclination angle α of 70° or more and less than 80° with respect to the axis L of the high-pressure tank 10.

[0020] In this embodiment, one layer of low-angle helical winding is wound in contact with the outer peripheral surface of the liner 11 (that is, the innermost layer of the reinforcing layer 12), and high-angle helical winding and hoop winding are repeated on the outside thereof. However, the low-angle helical winding may also be applied as appropriate.

[0021] Furthermore, in this embodiment, among the wound fiber bundles 12a, in the low-angle helically wound fiber bundle 12a that forms the innermost layer and contacts the outer peripheral surface of the liner 11, the fiber bundles 12a adjacent to each other in the width direction (the direction perpendicular to the direction in which the strip-shaped fiber bundle 12a extends) are wound such that a part of the width-direction end portions overlaps in the thickness direction. A conceptual diagram for explanation is shown in FIG. 3. FIG. 3 shows a part of the cross-section of the low-angle helically wound fiber bundle 12a and the liner 11 arranged in the innermost layer, and this cross-section is a cross-section perpendicular to the direction in which the fiber bundle 12a extends.

[0022] As can be seen from FIG. 3, the fiber bundles 12a at this part have an overlapping portion 12b where the width-direction end portions of adjacent fiber bundles overlap in the thickness direction. Here, when the width of the fiber bundle 12a is w and the amount of overlap (the size in the direction parallel to the width direction) of adjacent fiber bundles 12a is v, the overlap rate represented by v / w×100% is 14% or more on average for all the fiber bundles 12a that are low-angle helically wound and contact the outer peripheral surface of the liner 11 in the innermost layer included in the high-pressure tank 10. It is preferable that the overlap rate is 14% or more for all the overlapping portions 12b, but it is not necessarily required that the overlap rate is 14% or more for all the overlapping portions 12b, and it may be an average value as described above. By providing such an overlapping portion, the deformation of the liner 11 can be more reliably suppressed. If the overlap rate is less than 14%, the possibility that the suppression of the liner deformation is insufficient increases. The upper limit of the overlap rate is not particularly limited, and if the overlap rate is increased, the deformation of the liner 11 can be suppressed. However, as the overlapping portion becomes larger, the amount of fiber bundles 12a used increases. From this perspective, the overlap rate is preferably 50% or less. Note that such deformation of the liner occurs during the production of the high-pressure tank, and it is considered that the deformation generated here remains in the final product, the high-pressure tank. The manufacturing method is not particularly limited, and an example will be described later.

[0023] 1.3. Protective layer The protective layer 13 is a layer disposed on the outer periphery of the reinforcing layer 12 as needed. When provided, for example, glass fibers are wound and impregnated with resin herein. 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 high-pressure tank 10. The thickness of the protective layer 13 is not particularly limited, but can be about 1.0 mm to 1.5 mm.

[0024] 1.4. Base The base 14 is a member attached to each of the two openings 11c of the liner 11. One of them functions as an opening for communicating the inside and outside of the high-pressure tank 10 and also functions as an attachment portion for attaching piping and valves to the high-pressure tank 10. Further, the base 14 also functions as an attachment portion for attaching the liner 11 to a multi-end filament winding device when forming the reinforcing layer 12.

[0025] 2. Manufacturing method The manufacturing of the above-described high-pressure tank 10 can be performed by a known method except for the formation of the overlapping portion 12b. For example, as a manufacturing method of a high-pressure tank, it includes a step of forming a layer with a fiber bundle, a step of installing and degassing in a mold, a step of supplying and stopping a resin composition, and a step of demolding. The following steps will be described.

[0026] 2.1. Step of forming a layer with a fiber bundle In the step of forming a layer with a fiber bundle, the fiber bundle 12a is wound around the outer periphery of the liner 11. That is, in this step, after increasing the pressure inside the liner 11, a first layer of low-angle helical winding in contact with the outer surface of the liner 11 and a plurality of layers wound outside this first layer are wound by high-angle helical winding or hoop winding to form a layer. At this time, the first layer by low-angle helical winding is wound so that an overlapping portion of 14% or more occurs between the widthwise ends of the fiber layers 12a arranged at adjacent positions as described above. At this time, glass fibers for the protective layer 13 may be continuously wound as needed.

[0027] As shown in FIG. 4, when the inventors observed the force applied to the fiber bundle by the force F from the inside of the pressurized liner when winding the fiber bundle, if there is no overlapping portion in adjacent fiber bundles or the degree of the overlapping portion is insufficient, while a compressive force that presses the liner at the center in the width direction of the fiber bundle is generated, a tensile force acting on the opposite side is generated at the end in the width direction of the fiber bundle, and they obtained the knowledge that a large distribution occurs in the force that presses the liner in the width direction of the fiber bundle (the force applied in the direction to suppress the swelling of the liner). Considering that this force distribution greatly deforms the liner, as described above, by providing an overlapping portion, this force distribution can be suppressed to a low level, making it possible to suppress the deformation of the liner.

[0028] In this embodiment, the winding of such a fiber bundle 12a is performed by the filament winding method. For example, a plurality of bobbins around which the fiber bundle 12a is wound are arranged so as to surround the liner 11 along the outer periphery of the liner 11, and the fiber bundle 12a is wound using a multi-feed filament winding device. The number of bobbins that can be installed in the multi-feed filament winding device is not particularly limited, but for example, some can install 48 bobbins.

[0029] 2.2. Process of installation and degassing into the mold In the process of installation and degassing into the mold, a preform (a member in which a fiber bundle is wound around a liner) produced in the process of forming a layer by the fiber bundle is installed inside the mold, and the inside of the mold is evacuated to perform degassing. By this degassing, the resin composition to be impregnated easily penetrates into the fiber bundle, and the impregnation is performed more smoothly.

[0030] 2.3. Process of supplying and stopping the resin composition In the process of supplying and stopping the resin composition, the uncured resin composition is supplied through a flow path to the layer formed by the fiber bundle of the preform disposed in the mold, and the supply is stopped by supplying a required amount of the resin composition. Thereby, the resin composition impregnates the fiber bundle.

[0031] 2.4. Demolding process In the release process, after ensuring that the supplied and impregnated resin composition has hardened, the preform impregnated with the resin is removed from the mold.

[0032] 3. Examples In the examples, the overlap ratio of the overlapping parts in the low-angle helically wound fiber bundles that form the innermost layer of the high-pressure tank and are in contact with the outer peripheral surface of the liner was changed to examine the deformation of the liner. Also, as a comparative example, an example without an overlapping part (an example with an overlap ratio of 0%) was examined together.

[0033] 3.1. High-Pressure Tank for Testing The specifications of the high-pressure tank used in the test are as follows. Note that no protective layer was provided in this test. <Liner> · Material: Polyamide 6 (Nylon 6) and Polyamide 66 (Nylon 66), Young's modulus 2400 MPa · Thickness in the body part: 2 mm · Inner diameter: 256 mm · Axial length: 1200 mm <Fiber Bundle> · Fiber: Carbon fiber · Size of the fiber bundle: Width 16 mm × Thickness 0.3 mm · Number of windings: 45 windings or more · Overlap ratio: 14% (Example 1), 33% (Example 2), 45% (Example 3), and 0% (Comparative Example 1). Here, the overlap ratio is the average value of the overlap ratios of all overlapping parts in the low-angle helically wound fiber bundles that form the innermost layer of the high-pressure tank and are in contact with the outer peripheral surface of the liner. <Impregnated Resin> · Resin: Epoxy resin

[0034] 3.2. Test Method and Evaluation Method When manufacturing the test high-pressure tank, nitrogen was filled inside the liner to increase the pressure inside the liner to 0.7 MPa, and the fiber bundle was wound by the filament winding method. The test was conducted by measuring the strain generated in the high-pressure tank for each circumferential position using a method of measuring strain (distributed optical fiber sensing) by winding an optical fiber around the outer circumference of the manufactured high-pressure tank, passing pulsed light, and receiving the backscattered light. Then, a strain waveform, which is the strain distribution along the circumferential direction, was obtained and evaluated based on the magnitude of its amplitude. The amplitude of the strain is the average value of the amplitudes in the obtained strain waveform, and the greater the amplitude of the strain, the greater the deformation of the liner accordingly.

[0035] 3.3. Results Figures 5(a) and 5(b) show examples of the obtained strain waveforms (the upper graphs in each figure, horizontal axis: circumferential position, vertical axis: strain) and a part of the cross-section of the high-pressure tank (the lower figures in each figure, CT image). Figure 5(a) is an example when the overlap ratio is 14%, and Figure 5(b) is an example when the overlap ratio is 0%. As can be seen from Figure 5, by setting the overlap ratio to 14%, the amplitude of the strain waveform becomes smaller, indicating that the deformation of the liner is suppressed.

[0036] Figure 6 shows a graph representing the magnitude of the strain amplitude at each overlap ratio. As can be seen from Figure 6, when the overlap ratio is 14% or more, it is possible to reliably suppress the strain amplitude, and the deformation of the liner can be suppressed.

Description of Symbols

[0037] 10… High-pressure tank, 11… Liner, 12… Reinforcing layer, 13… Protective layer, 14… Base

Claims

**Claim 1** A high-pressure tank in which a plurality of layers of strip-shaped fiber bundles are wound around a liner, wherein only the fiber bundles, which are low-angle helical windings arranged in the innermost layer so as to be in contact with the liner, are wound such that the widthwise end portions of adjacent fiber bundles overlap by 14% or more. High-pressure tank. **Claim 2** The high-pressure tank according to claim 1, wherein the liner is made of resin. **Claim 3** A method for manufacturing a high-pressure tank, the method having a step of winding a strip-shaped fiber bundle around a liner in a plurality of layers, wherein when winding the fiber bundle as a low-angle helical winding arranged in the innermost layer so as to be in contact with the liner, the fiber bundle is wound such that the widthwise end portions of adjacent fiber bundles overlap by 14% or more. Method for manufacturing a high-pressure tank. **Claim 4** The method for manufacturing a high-pressure tank according to claim 3, wherein the liner is made of resin.

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