Manufacturing method of high pressure tank

Abstract

To provide a method of manufacturing a high pressure tank capable of enhancing the orientation of a fiber bundle.SOLUTION: The method of manufacturing the high pressure tank includes a step of winding the fiber bundle so as to provide a plurality of hoop winding layers on the outer periphery of a liner while applying inner pressure to the liner. The tension of the fiber bundle and the inner pressure of the liner are adjusted so that the second and succeeding hoop winding layers each have greater strain even at any peripheral position than the hoop winding layer arranged nearest the liner side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a high pressure tank having a layer of wound fiber bundles impregnated with resin. [Background technology]

[0002] High-pressure tanks used in fuel cell vehicles, etc. have a liner that forms the internal space of the high-pressure tank, and a reinforcing layer is formed by wrapping a resin-impregnated fiber bundle around the outer periphery of this liner, thereby achieving high strength.

[0003] Patent Document 1 describes a method for manufacturing a tank in which a fiber bundle is wound around a liner while applying internal pressure to the liner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-127968 A Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional high-pressure tanks, localized compression fields can occur in some areas during hoop winding, resulting in tight winding (a problem in which the degree of alignment of the fiber bundles (orientation of the fiber bundles) is reduced), which can lead to deformation of the liner and reduced rigidity. This tends to become more pronounced as high-pressure tanks are made thinner to reduce their weight.

[0006] The present disclosure has been made in consideration of these circumstances, and an object of the present disclosure is to provide a method for manufacturing a high-pressure tank that can improve the orientation of fiber bundles. [Means for solving the problem]

[0007] The present application discloses a method for manufacturing a high-pressure tank, which includes a step of winding a fiber bundle around the outer periphery of the liner while applying internal pressure to the liner to provide multiple hoop winding layers, and adjusts the tension of the fiber bundle and the internal pressure of the liner so that the second and subsequent hoop winding layers have greater strain at any circumferential position than the hoop winding layer positioned closest to the liner. Effect of the Invention

[0008] According to the present disclosure, by adjusting the internal pressure and fiber tension when winding the fiber bundle, the strain state on the outer surface of the liner is improved, thereby improving the orientation of the fiber bundle. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1(a) is an external view of a high-pressure tank 10, and FIG. 1(b) is a cross-sectional view. [Diagram 2] FIG. 2 is a diagram for explaining how the fiber bundle 12a is wound in the high-pressure tank 10. As shown in FIG. [Diagram 3] FIG. 3 is a diagram showing the strain at each circumferential position in each layer of the hoop group. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1. High-pressure tank structure Fig. 1(a) shows a schematic view of the appearance of a high-pressure tank 10 according to one embodiment, and Fig. 1(b) shows a schematic cross section taken 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 cap 14. Each component will be described below.

[0011] 1.1. Raina The liner 11 is a hollow member that defines the internal space of the high-pressure tank 10 and is cylindrical in this embodiment. The liner 11 has a body portion 11a with a generally constant diameter, and openings at both ends of the body portion 11a are narrowed by dome-shaped side ends 11b, and a nozzle 14 is disposed in the narrowed opening 11c. The liner 11 may be made of any material that can hold what is contained in its internal space (e.g., hydrogen) without leaking, and any known material can be used for the material, such as nylon resin, polyethylene-based synthetic resin, or 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 these, from the viewpoint of reducing the weight of the high-pressure tank, it is preferable that the material constituting the liner is a synthetic resin, and the thickness of the liner is preferably 2.0 mm or less in the body portion. In high-pressure tanks equipped with such a lightweight liner, problems tend to occur in the orientation of the fiber bundles as described above, but the present disclosure has made it possible to improve the orientation.

[0012] 1.2. Reinforcement layer The reinforcing layer 12 is made of multiple layers of laminated fibers, and the fibers are impregnated with hardened resin. The fiber layers are formed by wrapping fiber bundles around the outer periphery of the liner 11 in multiple layers to a predetermined thickness. The thickness of the reinforcing layer 12 and the number of turns of the fiber bundle are determined by the required strength and are not particularly limited, but the thickness is about 10 mm to 30 mm.

[0013] <Fiber bundle> The fiber bundle of the reinforcing layer 12 is made of, for example, carbon fiber, and the fiber bundle is a band-like bundle of carbon fibers having a predetermined cross-sectional shape (for example, a rectangular cross-section). Although there is no particular limitation on the specific cross-sectional shape, an example of the cross-sectional shape is a rectangle with a width of about 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 also not particularly limited, but an example of the fiber bundle is about 24,000 carbon fibers.

[0014] <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 increase the strength of the fibers. For example, a thermosetting resin that cures by heat can be used, specifically an epoxy resin containing an amine-based or anhydride-based curing accelerator and a rubber-based reinforcing agent, an unsaturated polyester resin, etc. In addition, a resin composition that uses an epoxy resin as a base agent and cures by mixing it with a curing agent can be used. In this case, the resin composition, which is a mixture of the base agent and the curing agent, reaches and penetrates the fiber bundles between the time of mixing and curing, and the time of curing, and automatically cures.

[0015] <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. An explanatory diagram is shown in Fig. 2. For ease of understanding, Fig. 2 shows only a portion of the wound fiber bundle 12a. As described above, the reinforcing layer 12 is configured by winding the fiber bundle 12a around the outer periphery of the liner 11.

[0016] The winding manner of the fiber bundle 12a includes hoop winding and helical winding, and the helical winding further includes low-angle helical winding and high-angle helical winding. Hoop winding is mainly applied to the body part as shown by A in Fig. 2, and is wound with an inclination angle α of 80° to 90° with respect to the axis L of the high-pressure tank 10. Hoop winding tightens the part in question, and applies a force that counters the force of the liner 11 expanding radially outward due to gas pressure. On the other hand, the helical winding is a winding method mainly for winding and tightening the side end inward in the axial direction of the high-pressure tank, and the fiber bundle 12a is entirely wound around the liner 11 so as to be hooked onto the side end, thereby improving the strength of the side end. As shown by B in Fig. 2, the low-angle helical winding is mainly wound so as to cross two side ends that are on opposite sides, with an inclination angle α of 5° to 30° with respect to the axis L of the high-pressure tank 10. As shown by C in Fig. 2, the high-angle helical winding is mainly wound so as to cross the body and the side end, with an inclination angle α of 70° to 80° with respect to the axis L of the high-pressure tank 10.

[0017] In this embodiment, one layer of low-angle helical winding is wound in contact with the outer peripheral surface of the liner 11 (i.e., the innermost layer of the reinforcing layer 12), and on the outside of that is wound a group of hoops consisting of high-angle helical winding and hoop winding, and this group of hoops is repeated over multiple layers.

[0018] In addition, in the multiple hoop groups, the layers formed by the hoop windings of the second and subsequent hoop groups are wound so that the strain is larger at any position in the circumferential direction than the layers formed by the hoop windings of the hoop group arranged on the innermost side (liner side). More preferably, in the multiple hoop groups, the layers formed by the hoop windings of a certain hoop group are wound so that the strain is larger at any position in the circumferential direction than the layers formed by the hoop windings of the hoop group arranged one hoop group inside (liner side) of the hoop group. This can increase the orientation of the fiber bundles and suppress a decrease in the strength of the liner. Such control of the strain is adjusted when the high-pressure tank is manufactured. The manufacturing method for this will be described later.

[0019] 1.3.Protective layer The protective layer 13 is a layer that is arranged on the outer periphery of the reinforcing layer 12 as necessary, and is formed by, for example, winding glass fiber and impregnating it with resin. The impregnated resin can be considered to be the same as that of the reinforcing layer 12. This makes it possible to impart impact resistance 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.

[0020] 1.4. Base The mouthpiece 14 is a member disposed in the two openings 11c of the liner 11, one of which functions as an opening that communicates between the inside and outside of the high-pressure tank 10 and also functions as an attachment part for attaching piping and valves. The mouthpiece 14 also functions as an attachment part for attaching the liner 11 to a multiple-feed filament winding device when the reinforcing layer 12 is formed.

[0021] 2. Manufacturing method The above-mentioned high-pressure tank 10 includes, as one of its manufacturing methods S10, a step S11 of forming a layer with a fiber bundle, a step S12 of placing in a mold and degassing, a step S13 of supplying and stopping the resin composition, and a step S14 of releasing from the mold. Each step will be described below.

[0022] 2.1. Step S11 of forming layers with fiber bundles In step S11 of forming a layer with fiber bundles, the fiber bundles 12a are wound around the outer periphery of the liner 11. In this step, the pressure inside the liner 11 is increased, and then a first layer of low-angle helical winding is formed in contact with the outer surface of the liner 11, and a group of hoops is repeatedly wound around the outside of this first layer to form multiple layers. At this time, in the multiple hoop groups, the layers formed by the hoop windings of the second and subsequent hoop groups are wound so that the strain is larger at any position in the circumferential direction than the layers formed by the hoop windings of the hoop group arranged on the innermost side (liner side). Preferably, in the multiple hoop groups, the layers formed by the hoop windings of a certain hoop group are wound so that the strain is larger at any position in the circumferential direction than the layers formed by the hoop windings of the hoop group arranged one hoop group inside (liner side) of the hoop group. This can increase the orientation of the fiber bundles and suppress deformation and strength reduction of the liner. The inventors found that such strain is related to the orientation of the fiber bundles, and made it possible to suppress deformation and strength reduction of the liner by controlling the strain.

[0023] In order to control the strain generated in the fiber bundle of the hoop group as described above, in step S11 of forming layers with fiber bundles, the internal pressure of the liner and the tension of the fiber bundle during winding are controlled for each layer of the hoop group. The specific internal pressure of the liner and the tension of the fiber bundle are controlled based on a relationship with the strain obtained in advance for each type of high-pressure tank to be manufactured. The method of measuring the strain is not particularly limited, but an example of this is to measure the strain at each circumferential position using a method (distributed optical fiber sensing) in which an optical fiber is wound around the outer periphery and pulsed light is passed through it and the strain is measured by receiving the backscattered light each time a layer of a hoop group is formed.

[0024] As an example, the layers were laminated as follows: <LINER> Material: Polyamide 6 (nylon 6) and polyamide 66 (nylon 66), Young's modulus 2400 MPa Body thickness: 2mm ·Inner diameter: 265mm Axial length: 1200mm <Fiber bundle> Fiber: Carbon fiber - Fiber bundle size: width 16mm x thickness 0.3mm <How to wind fiber bundles> 1st layer: Low angle helical winding Second layer (innermost layer of hoop group): Liner internal pressure 0.05MPa, fiber bundle tension 240N - 3rd layer (2nd layer of hoop group): Liner internal pressure 0.2MPa, fiber bundle tension 235N - 4th layer (3rd layer of hoop group): Liner internal pressure 0.4MPa, fiber bundle tension 230N 5th layer (4th hoop layer, outermost layer): Liner internal pressure 0.55MPa, fiber bundle tension 220N <Impregnating resin> Resin: Epoxy resin

[0025] Each time each layer of the hoop group was formed, optical fiber was wound around the outer circumference of the high-pressure tank, and the strain generated in the high-pressure tank was measured at each circumferential position using distributed optical fiber sensing, and the strain distribution along the circumferential direction was obtained. As a result, the strain distribution was as shown in Figure 3. As can be seen from Figure 3, in multiple hoop groups, the layers of the second and subsequent hoop groups are wound so that the strain is larger at any circumferential position than the layer of the innermost hoop group. In this example, the strain was also larger at any circumferential position than the layer of the hoop group arranged one layer inside (liner side) in the adjacent hoop group. This allowed for sufficient orientation of the fiber bundles to suppress deformation and strength reduction of the liner.

[0026] In this embodiment, the fiber bundle 12a is wound by a filament winding method. For example, the fiber bundle 12a is wound using a multi-yarn filament winding device in which multiple bobbins, on which the fiber bundle 12a is wound, are arranged so as to surround the liner 11 along the outer periphery of the liner 11. There is no particular limit to the number of bobbins that can be installed at the same time, but some devices can install, for example, 48 bobbins.

[0027] 2.2. Installation in mold and degassing process S12 In the step S12 of setting in a mold and degassing, the preform (a member in which the fiber bundle is wound around a liner) produced in the step S11 of forming a layer with the fiber bundle is placed inside the mold, and the inside of the mold is evacuated to perform degassing. This degassing makes it easier for the resin composition to permeate the fiber bundle, and the impregnation is carried out more smoothly.

[0028] 2.3. Step S13 for stopping supply of resin composition In step S13 of supplying and stopping the resin composition, the resin composition before curing is supplied through a flow path to the layer of fiber bundles of the preform arranged in the mold, and the supply is stopped when the required amount of resin composition has been supplied, thereby impregnating the fiber bundles with the resin composition.

[0029] 2.4. Demolding process S14 In the demolding step S14, it is determined that the supplied and impregnated resin composition has hardened, and the preform impregnated with the resin is removed from the mold. [Explanation of symbols]

[0030] 10...high pressure tank, 11...liner, 12...reinforcing layer, 13...protective layer, 14...ferrule

Claims

[Claim 1] A method for manufacturing a high-pressure tank, comprising the steps of: a step of winding a fiber bundle around an outer periphery of the liner to provide a plurality of hoop-wound layers while applying an internal pressure to the liner; The tension of the fiber bundle and the internal pressure of the liner are adjusted so that the second and subsequent hoop winding layers have a larger strain at any position in the circumferential direction than the hoop winding layer disposed closest to the liner. A method for manufacturing high-pressure tanks.

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