Method for manufacturing a high-pressure tank and high-pressure tank

Abstract

Method for manufacturing a high-pressure tank, comprising: Forming a preform (30) by winding a carbon fiber (13a) around a lining (11) to form a fiber layer (13) on an outer circumference of the lining (11); and Impregnating the fiber layer (13) of the preform (30) with a curable resin and curing the curable resin, wherein when winding the carbon fiber (13a) around the lining (11) a metal wire (13b) is wound together with the carbon fiber (13a) around the lining (11) before a thickness of the fiber layer (13) reaches half of the total thickness of the fiber layer (13).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to high-pressure tanks reinforced with a resin-impregnated fiber layer and methods for manufacturing a high-pressure tank. 2. Description of the state of the art

[0002] High-pressure tanks for fuel cell vehicles have a liner that forms the interior of the high-pressure tank. A resin-impregnated fiber layer covers the outer surface of the liner and serves as a reinforcement layer, providing high strength. For example, Japanese patent applications JP 2008-132717 A, JP 2012-148544 A, JP 2018-012235 A, JP 2019-056415 A, and JP 2019-059176 A disclose a method for manufacturing such a high-pressure tank.

[0003] JP 2008-132717 A discloses a process for producing fiber-reinforced plastic. In this process, a metal core is covered with fibers, and the fibers covering the metal core are impregnated with a matrix resin, or the metal core is covered with fibers impregnated with the matrix resin. The matrix resin is then precured by heating and subsequently postcured by heating at a temperature higher than the precuring temperature. The metal core consists of a metal with a melting point higher than the precuring temperature and equal to or lower than the postcuring temperature.

[0004] JP 2012-148544 A discloses a method for manufacturing a high-pressure tank with a stack of fiber layers pre-impregnated with a thermosetting resin. In this method, a coil of copper wire, etc., is wound around both the inside and outside of the resin layer, and a current is applied to the copper wire to heat a thermosetting resin.

[0005] JP 2018-012235 A discloses a method for manufacturing a high-pressure tank with a stack of fiber layers pre-impregnated with a thermosetting resin. In this method, a thin plate of stainless steel or copper is placed in the fiber layer at a position at the end of the resin fiber winding. This thin plate is heated to cure the resin.

[0006] JP 2019-056415 A discloses a method for manufacturing a high-pressure tank. In this method, a preform consisting of a liner defining the interior of the high-pressure tank and a fiber layer formed on the outer surface of the liner is placed in a mold. The fiber layer is impregnated with a resin by rotating the preform circumferentially around the center axis of the preform within the mold while injecting the resin toward the preform placed in the mold.

[0007] JP 2019-059176 A discloses a method for impregnating a molded fiber layer with a resin. This technique uses fiber bundles of varying thicknesses to form a fiber layer, creating voids in the fiber layer. A resin passing through these voids facilitates the permeation of the resin into the fiber layer.

[0008] Finally, DE 10 2018 122 890 A1 discloses a method for manufacturing a high-pressure tank, comprising: a preform manufacturing step comprising winding dry fiber bundles of different thicknesses onto a liner in a state where the dry fiber bundles of different thicknesses are arranged adjacent to each other; and a molding step comprising placing the preform manufactured in the preform manufacturing step in a mold and injecting resin. SUMMARY OF THE INVENTION

[0009] In resin transfer molding (RTM), a fiber layer of a preform (a component consisting of a liner and a fiber layer formed thereon) is impregnated with a resin composition and then cured to form a reinforcement layer. In RTM, uniform resin impregnation is sometimes difficult depending on the thickness and shape of the fiber layer. This issue is particularly significant for high-pressure tanks for fuel cell vehicles, as a fiber layer for such high-pressure tanks is thick and has a cylindrical shape that is long in the axial direction to ensure sufficient strength.

[0010] Injecting a resin into a preform for such high-pressure tanks under high pressure can deform a lining, etc., due to the pressure or requires extensive equipment. Impregnating the fiber layer with the resin in a highly fluid state reduces productivity because the resin takes time to cure.

[0011] The present invention provides a method for manufacturing a high-pressure tank that can achieve high-quality impregnation while limiting the reduction in productivity when impregnating a fiber layer with a resin. The present invention also provides a high-pressure tank manufactured by the manufacturing method.

[0012] A first aspect of the present invention provides a method for manufacturing a high-pressure tank. The method comprises: forming a preform by winding a carbon fiber around a liner to form a fiber layer on an outer periphery of the liner; and impregnating the fiber layer of the preform with a curable resin and curing the curable resin. When winding the carbon fiber around the liner, a metal wire is wound around the liner together with the carbon fiber before a thickness of the fiber layer reaches half the total thickness of the fiber layer.

[0013] In the above aspect, the carbon fiber and the metal wire can be wound using a single multi-filament winding machine.

[0014] In the above aspect, the carbon fiber and the metal wire can be wound by passing the liner sequentially through a plurality of multi-filament winding machines.

[0015] In the above aspect, a current may be applied to the metal wire after the fiber layer of the preform is impregnated with the curable resin.

[0016] In the above aspect, the current may be applied to the metal wire when the curable resin reaches a maximum exothermic curing temperature.

[0017] A second aspect of the present invention provides a high-pressure tank. The high-pressure tank comprises: a hollow liner; and a reinforcing layer comprising a fiber layer and a resin impregnated into the fiber layer, wherein the fiber layer comprises a carbon fiber and a metal wire, both wound around the liner. The metal wire is disposed at only one position in the fiber layer, the position being closer to the liner than a central position of the fiber layer in a thickness direction.

[0018] In the above aspect, the metal wire may be made of a metal having a volume resistivity of 5.0 µΩcm or less.

[0019] In the above aspect, the metal wire may be made of a metal having a volume resistivity of more than 5.0 µΩcm.

[0020] According to the present invention, high-quality impregnation is achieved while limiting the reduction in productivity, and a high-quality high-pressure tank can be manufactured while reducing the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The features and advantages as well as the technical and economic significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals designate like elements, in which: Fig. 1 schematically shows the appearance of a high-pressure tank 10; Fig. 2A a sectional view of the high pressure tank 10; Fig. 2B is an enlarged partial view of the Fig. 2A shown section of the high pressure tank 10; Fig. 3A is a diagram illustrating the arrangement of a metal wire 13b; Fig. 3B is a further diagram illustrating the arrangement of the metal wire 13b; Fig. 4 how the metal wire 13b is wound; Fig. 5 is a flowchart of a high pressure tank manufacturing process S10; Fig. 6A is a diagram illustrating step S11 of forming a fiber layer; Fig. 6B is a further diagram illustrating step S11 of forming a fiber layer; Fig. 7A is a diagram illustrating a form 45; Fig. 7B is a further illustration of the form 45; Fig. 8 shows the step S13 of supplying or stopping the supply of a resin composition; Fig. 9 the step S14 of applying a current; Fig. 10 is a graph showing an example of the timing of the start of current application; and Fig. 11 the step S21 of forming a fiber layer. DETAILED DESCRIPTION OF EMBODIMENTS 1. First Embodiment 1.1. Structure of a High-Pressure Tank

[0022] Fig. Fig. 1 shows schematically the appearance of a high-pressure tank 10 according to a first embodiment, and Fig. 2A shows schematically a section through the high-pressure tank 10 along an axis. Fig. Figure 2B shows part of the section of Fig. 2A, which illustrates the layered structure of the high-pressure tank 10. As can be seen from these figures, the high-pressure tank 10 comprises a liner 11, a reinforcement layer 12, a protective layer 15, and caps 16. The structure of these components is described below. lining

[0023] The liner 11 is a hollow body that defines the interior of the high-pressure tank 10. The liner can be made of any material that can absorb the contents (e.g., hydrogen) of the interior without leaking, and any known material can be used. Examples of the material include nylon resins, polyethylene resins, and metals such as stainless steel and aluminum. The thickness of the liner 11 is not particularly limited, but is preferably 0.5 mm to 1.0 mm. Reinforcing layer

[0024] The reinforcement layer 12 comprises a fiber layer 13 and a resin with which the fiber layer 13 has been impregnated and cured. The fiber layer 13 consists of a fiber bundle 13a wound in multiple layers to a predetermined thickness around the liner 11, and a metal wire 13b wound around a portion of the fiber bundle 13a layer. The thickness of the reinforcement layer 12 is approximately 10 mm to 30 mm, but is determined by the required strength and is not particularly limited. Especially in high-pressure tanks for fuel cell vehicles, a thick reinforcement layer is required for sufficient strength. Therefore, high-pressure tanks for fuel cell vehicles have a thick fiber layer, and it is difficult to impregnate the fiber layer with a resin.One half of the thickness of the fiber layer 13 on the side of the lining 11 is also called the “inner layer side”, and the opposite (outer) half of the thickness of the fiber layer 13 from the lining 11 is also called the “outer layer side”.

[0025] The fiber bundle 13a of the fiber layer 13 is made of carbon fibers. The fiber bundle 13a is a carbon fiber strip formed by bundling carbon fibers and has a predetermined cross-sectional shape (e.g., a rectangular cross-section). Specifically, the cross-sectional shape is a rectangle with a width of approximately 6 mm to 9 mm and a thickness of approximately 0.1 mm to 0.15 mm, but not limited thereto. The number of carbon fibers in the fiber bundle 13a is, for example, approximately 36,000, but not limited thereto. Such a carbon fiber bundle 13a is wound around the liner 11 to form the fiber layer 13.

[0026] The metal wire 13b of the fiber layer 13 is made of a conductive metal, particularly a metal with low electrical resistance, since in the present embodiment, a current is applied to the metal wire 13b to inductively heat the carbon fibers of the fiber bundle 13a, as described later. Specifically, the metal for the metal wire 13b is preferably a material commonly used for conductive wires and has a volume resistivity of 5.0 μΩcm or less at 100°C, such as copper.

[0027] The metal wire 13b is arranged on the inner layer side of the fiber layer 13 and is preferably arranged in the layer closest to the liner 11 (the first layer, a layer in contact with the liner 11). Fig. 3A and Fig. 3B schematically show, by hidden outlines, the metal wire 13b wound around the lining 11. Since the metal wire 13b is arranged in the inner layer side of the fiber layer 13, as described above, the metal wire 13b is not visible from the outside. However, for the sake of simplicity, the metal wire 13b is indicated by dashed lines in Fig. 3A and Fig. 3B. Fig. 3A shows the appearance of the high pressure tank 10, and Fig. 3B shows a section through the high-pressure tank 10. Fig. Figure 4 is a plan view of the metal wire 13b wound together with the fiber bundle 13a, viewed from the outside. As can be seen from these figures, the metal wire 13b is wound spirally or helically around the liner 11. The carbon fibers of the fiber layer 13 can therefore be inductively heated by applying a current thereto, as will be described later. As can be seen from Fig. As can be seen in Figure 4, the metal wire 13b is wound so that it alternately passes over and under adjacent fiber bundles 13a, as in weaving. The cross-sectional shape of the metal wire 13b is not particularly limited and can be the same as or different from that of the fiber bundle 13a. Preferably, the winding angle of the fiber bundle 13a and the winding angle of the metal wire 13b are the same (in phase). This allows the carbon fibers to be heated more effectively by the metal wire.

[0028] The metal wire 13b only needs to be placed at least on the inner layer side. The metal wire 13b can be placed only on the inner layer side. This configuration facilitates resin curing because the outer layer side of the resin-impregnated fiber layer 13 is efficiently heated by a mold, and the inner layer side thereof is efficiently heated by applying current to the metal wire 13b, as described later.

[0029] The resin with which the fiber layer 13 in the reinforcing layer 12 has been impregnated and cured is not particularly limited, as long as the resin can first penetrate the fiber layer 13 while in a liquid state and then be cured by any method to increase the strength of the fiber layer 13. Examples of the resin include thermosetting resins that are cured by heat, such as epoxy resins, unsaturated polyester resins, etc., containing an amine- or anhydride-based curing accelerator and a rubber-based reinforcing agent. Other examples of the resin are resin compositions that contain an epoxy resin as a base resin and are cured by adding a curing agent. In this case, the resin composition is automatically cured by mixing the base resin and the curing agent and the mixture, that is,the resin composition that reaches and penetrates the fiber layer when the mixture is cured. protective layer

[0030] The protective layer 15 is arranged on the outer periphery of the reinforcement layer 12. The protective layer 15 is a layer formed by wrapping glass fibers around the reinforcement layer 12 and impregnating the resulting glass fiber layer with a resin. The resin used to impregnate the protective layer 15 can be the same as that used for the reinforcement layer 12. This allows the high-pressure tank 10 to be impact-resistant. The thickness of the protective layer 15 is not particularly limited but can be approximately 1.0 mm to 1.5 mm. cap

[0031] The caps 16 are members attached to two open ends of the liner 11. One of the caps 16 functions as an opening for communication between the inside and outside of the high-pressure tank 10 and acts as a fastening part for attaching a pipe or a valve to the high-pressure tank 10. The caps 16 also function as fastening sections for attaching the liner 11 to a multi-filament winder, which will be described later, when the reinforcing layer 12 is formed. 1.2. Structure of the preform

[0032] A preform 30 is an intermediate member that ultimately becomes the high-pressure tank 10. The preform 30 consists of at least the liner 11 and the fiber layer 13. The preform 30 is therefore a structural member before the fiber layer 13 of the reinforcing layer 12 is impregnated with the resin. Therefore, the configurations included in the preform 30 are similar to those described above, and their description will be omitted here. Although the preform 30 described here is the liner 11 with the fiber layer 13 disposed thereon, the preform 30 may be the liner 11 with the glass fibers for the protective layer 15 further disposed on the fiber layer 13. 1.3. First manufacturing process

[0033] Fig. 5 is a flowchart of a high-pressure tank manufacturing method S10 according to an embodiment. As can be seen from Fig. As can be seen from Figure 5, the high-pressure tank manufacturing method S10 includes step S11 of forming a fiber layer, step S12 of placing a preform in a mold and evacuating a mold cavity, step S13 of supplying and stopping the supply of a resin composition, step S14 of applying a current, and step S15 of releasing the preform. These steps are described below. Step S11 of forming a fiber layer

[0034] In step S11 of forming a fiber layer (hereinafter also referred to as “step S11”), the fiber layer 13 is formed on the outer periphery of the liner 11 to manufacture the preform 30. Fig. 6A and Fig. 6B illustrates step S11. Fig. Fig. 6A schematically shows how the fiber bundle 13a and the metal wire 13b are wound to form a layer with the metal wire 13b, and Fig. 6B schematically shows how the fiber bundle 13a is wound to form a layer without the metal wire 13b.

[0035] As can be seen from the Fig. 6A and Fig. As can be seen from Fig. 6B, in the present embodiment, the fiber layer 13 is formed by a filament winding method. In the present embodiment, the fiber layer 13 is formed using a single multi-filament winding machine (hereinafter also referred to as a "multi-filament winding machine") having a plurality of fiber bundle bobbins 40 arranged around the outer periphery of the liner 11. The fiber bundle bobbins 40 are bobbins on which the fiber bundle 13a is wound.

[0036] More precisely, as in Fig. As shown in FIG. 6A, when forming a layer containing the metal wire 13b by the multi-FW machine in which the fiber bundle coils 40 are arranged around the liner 11, at least one of the fiber bundle coils 40 is replaced with a metal wire coil 41, which is a coil with the metal wire 13b wound thereon. The fiber bundle 13a and the metal wire 13b are sequentially fed from the fiber bundle coils 40 and the metal wire coil 41 and wound around the liner 11. The winding method is a known method, but at least the metal wire 13b is wound into a spiral coil shape as described above.Since the metal wire 13b is placed in the inner layer side of the fiber layer 13, which is close to the liner 11, as described above, the winding with the coils including the metal wire coil 41 is performed in the early stage of the winding process (at the beginning of the winding process when the innermost layer is the layer containing the metal wire 13b).

[0037] As in Fig. As shown in Figure 6B, when forming a layer that does not contain the metal wire 13b, all the reels of the multi-FW machine are the fiber bundle reels 40, and the fiber bundle 13a is sequentially fed from the fiber bundle reels 40 and wound around the liner 11. The winding method is a known method. The multi-FW machine can be operated from the state of Fig. 6A in the state of Fig. 6B by simply replacing the metal wire coil 41 with the fiber bundle coil 40.

[0038] The number of coils that can be mounted simultaneously on the multi-FW machine is not particularly limited. For example, 48 coils can be mounted on a multi-FW machine. When forming a layer with the metal wire 13b using such a multi-FW machine, winding can be performed with 47 fiber bundle coils 40 and a single metal wire coil 41 arranged around the liner 11.

[0039] The glass fibers for the protective layer 15 can then be wound around the fiber layer 13.

[0040] Step S12 of placing the preform in a mold and evacuating a mold cavity

[0041] In step S12 of placing the preform 30 in a mold and evacuating a mold cavity (hereinafter also referred to as "step S12"), the preform 30 produced in step S11 is placed in a mold, and a mold cavity is evacuated. This evacuation facilitates the penetration or permeation of a resin composition into the fiber layer 13. The fiber layer 13 is thereby more uniformly impregnated with the resin composition.

[0042] Fig. 7A and Fig. 7B show a form 45. Fig. Figure 7A is a schematic exploded section of the mold 45 shown together with the preform 30, and Fig. 7B is a schematic cross-sectional view of the mold 45 with the preform 30 disposed therein. The mold 45 is a mold for impregnating the fiber layer 13 of the preform 30 with a resin. In the present embodiment, the mold 45 has an upper mold 46 and a lower mold 47. By closing the upper mold 46 and the lower mold 47, a cavity corresponding to the shape of the preform 30 is formed inside the mold 45. This cavity can be evacuated to form a sealed space.

[0043] The upper mold 46 can move relative to the lower mold 47 as indicated by a straight arrow in Fig. 7B. Accordingly, the preform 30 can be inserted into the mold 45 and removed (released) from the mold 45.

[0044] The upper mold 46 has a flow path 46a extending from the outside to the fiber layer 13 of the preform 30 placed in the mold 45. The resin composition is introduced into the flow path 46a to supply the resin composition to the fiber layer 13 and impregnate the fiber layer 13 with the resin composition. The mold 45 further has an air flow channel (not shown) for evacuating the cavity of the mold 45.

[0045] The mold 45 is provided with current application terminals 45a so that a current can be applied to the metal wire 13b in the fiber layer 13 of the preform 30.

[0046] The mold 45 is configured to maintain the temperature of the mold 45 at a desired temperature by a temperature control device, not shown.

[0047] Although the material for the mold 45 is not particularly limited, the mold 45 is preferably made of a metal like typical molds, and the mold 45 is a metal mold.

[0048] In step S12, the mold 45 is opened by separating the upper mold 46 from the lower mold 47. The preform 30 is placed on the lower mold 47 with its upper surface largely exposed. Then, the upper mold 46 is placed over the lower mold 47 and the preform 30 placed thereon, and the mold 45 is closed. The cavity of the mold 45 is then evacuated with a vacuum pump. The evacuation is completed before the resin composition is supplied to the fiber layer 13 in the following step.

[0049] Step S13 of supplying and stopping the supply of a resin composition

[0050] In step S13 of supplying and stopping the supply of a resin composition (hereinafter also referred to as "step S13"), the resin composition is supplied to the fiber layer 13 of the preform 30 arranged in the mold 45 before curing, and the supply is stopped once a required amount of the resin composition has been supplied. The fiber layer 13 is thus impregnated with the resin composition.

[0051] The resin composition is not particularly limited as long as it can reach and penetrate the fiber layer while in a liquid state and then be cured by any method to increase the strength of the fiber layer. Examples of the resin composition include thermosetting resins that are cured by heat, such as epoxy resins, unsaturated polyester resins, etc., which contain an amine- or anhydride-based curing accelerator and a rubber-based reinforcing agent. Other examples of the resin composition are resin compositions that contain an epoxy resin as a base resin and that are cured by adding a curing agent. In this case, the resin composition is automatically cured by mixing the base resin and the curing agent, and the mixture, that is, the resin composition, reaches and penetrates the fiber layer 13 when the mixture is cured.

[0052] As described later, in the present invention, a current is applied to the metal wire 13b to inductively heat the carbon fibers of the fiber layer 13. This accelerates the curing of the resin composition. Accordingly, in step S13, the resin composition is supplied to the fiber layer 13 in a highly liquid state, so that the fiber layer 13 can be impregnated with the resin composition more quickly and reliably (rapid impregnation up to the layer in contact with the liner 11). Step S14 of applying a current

[0053] In step S14 of applying a current, as in Fig. As shown in Figure 9, a current is applied to the metal wire 13b in the fiber layer 13 using the current application terminals 45a. As a result, the metal wire 13b, which acts as a heating coil, inductively heats the carbon fibers, which are an inductive material constituting the fiber bundle 13a, thereby accelerating curing.

[0054] The inner layer side of the fiber layer 13, which is located near the liner 11, tends to be cured slowly because it takes time for heat to be conducted from the mold 45 to the inner layer side of the fiber layer 13. However, since the metal wire 13b is arranged in the inner layer side of the fiber layer 13, the inner layer side of the fiber layer 13 is heated by applying a current to the metal wire 13b. Curing is thereby accelerated. Although the resin composition is supplied in a highly liquid state to more uniformly impregnate the fiber layer 13 with the resin composition in step S13, curing is facilitated by applying a current in step S14. Accordingly, both the impregnation rate and the curing rate are increased, improving the productivity of the high-pressure tank. Furthermore, the quality of the high-pressure tank is sufficiently high because more reliable impregnation and curing are achieved.

[0055] The time of applying a current to the metal wire 13b for heating is not particularly limited, but the application of the current can be started when the resin composition reaches its maximum exothermic curing temperature. Specifically, a temperature sensor is placed in advance on the liner 11 to obtain the relationship between time and temperature, as shown in Fig. 10. The power supply (heating) can be started when the resin composition reaches the maximum temperature P in Fig. 10 is reached. Curing can therefore be started after confirming that the fiber layer 13 has been sufficiently impregnated with the resin composition, allowing heat to be conducted to the lining 11 side. Impregnation is thus carried out more reliably. Step S15 of releasing the preform

[0056] In step S14, the resin composition is cured. Specifically, the resin composition impregnated into the fiber layer 13 is cured. In the subsequent preform 30 releasing step S15 (hereinafter also referred to as "step S15"), the resin-impregnated preform 30 is released from the mold 45. In the present embodiment, the preform 30 is released from the mold 45 by opening the mold 45 by separating the upper mold 46 from the lower mold 47. Impacts etc.

[0057] The resin-impregnated preform 30 is manufactured by the manufacturing process with the steps described above. A high-pressure tank is manufactured by further forming a resin-impregnated glass fiber layer on the resin-impregnated preform 30, and so on.

[0058] According to the present invention, to impregnate the fiber layer with a resin by the RTM impregnation method, the metal wire, such as a copper wire, is wound around a part of the carbon fiber layer in the inner layer side of the fiber layer by the multiple FW machine to form a heating coil. Accordingly, the fiber layer can also be heated from the inner layer side during impregnation with the resin. Thus, both rapid impregnation and rapid curing can be achieved. That is, the fiber layer is impregnated with the resin by flowing the resin composition into the fiber layer at a low temperature (low viscosity), and the resin composition on the outer layer side is cured by the heat from the mold, and the resin composition on the inner layer side is cured by the heat from the inductively heated fiber layer.In this way, both rapid curing and reliable impregnation are achieved, and a powerful, high-quality high-pressure tank can be produced at reduced costs.

[0059] In the present embodiment, since the heating coil formed by the metal wire is an induction heating coil, the entire fiber layer can be heated. 1.4. Second manufacturing process

[0060] A high-pressure tank manufacturing method S20 according to a further embodiment is described. The high-pressure tank manufacturing method S20 differs from the one described above with reference to Fig. 5 in that the high-pressure tank manufacturing method S20 includes the step of forming a fiber layer (referred to herein as "fiber layer forming step S21" for convenience), which differs from step S11. Since the subsequent steps S12 to S15 are identical to the high-pressure tank manufacturing method S10, their description will be omitted. Step S21 will be described. Step S21 of forming a fiber layer

[0061] In step S21 of forming a fiber layer (hereinafter also referred to as “step S21”), the fiber layer 13 is formed on the outer periphery of the liner 11 to manufacture the preform 30. Fig. 11 shows step S21.

[0062] Although the fiber layer 13 is also formed by the filament winding method in the present embodiment, the fiber layer 13 in the present embodiment is formed using a successive multi-FW machine in which a plurality of multi-FW machines are arranged. In the present embodiment, a plurality of multi-FW machines 50a to 50f are arranged as shown in Fig. 11. The individual multiple FW machines are the same as the multiple FW machine described with reference to Fig. 6A and Fig. 6B is described.

[0063] In the present embodiment, the plurality of multiple FW machines are arranged so that each multiple FW machine winds a corresponding layer of the fiber layer 13. Accordingly, as shown in Fig. 11, while the liner 11 moves from right to left in the figure and passes through the multiple FW machines 50a to 50f, the first layer, the second layer, the third layer, etc., of the fiber layer 13 are sequentially wound by the multiple FW machine 50a, the multiple FW machine 50b, the multiple FW machine 50c, etc. Thus, all layers of the fiber layer 13 are wound by the multiple FW machines 50a to 50f.

[0064] According to such a successive multi-FW machine, the multi-FW machine using the metal wire 13b can be fixed, and it is not necessary to change the bobbin during winding. The fiber layer 13 containing the fiber bundle 13a and the metal wire 13b can thus be efficiently formed. For example, if the first layer (layer in contact with the liner 11) is to be a layer containing the metal wire 13b, the multi-FW machine 50a of Fig. 11 the metal wire coil 41, as in Fig. 6A, and all the coils of the multiple FW machines 50b to 50f are the fiber bundle coils 40 as shown in Fig. 6B. In this case, it is not necessary to change the coil type, and the fiber bundle 13a and the metal wire 13b can be wound efficiently. 2. Second embodiment

[0065] A high-pressure tank and a method for manufacturing a high-pressure tank according to a second embodiment differ from the first embodiment in that a metal wire (hereinafter referred to simply as "metal wire 63b") different from the metal wire 13b of the first embodiment is used instead of the metal wire 13b. Since the other configurations and the manufacturing method are the same as in the first embodiment, only the metal wire 63b will be described.

[0066] As described above, the metal wire 13b of the first embodiment is a metal wire to which a current is applied to inductively heat the carbon fibers of the fiber bundle 13a. On the other hand, the metal wire 63b of the second embodiment is a metal wire that generates heat and heats its surroundings when a current is applied to it. Therefore, the metal wire 63b is made of a conductive metal, particularly a metal with high electrical resistance. In particular, the metal for the metal wire 63b is preferably a material commonly used for heating wires for heaters, etc., and which has a volume resistivity of more than 5.0 µΩcm at 100°C, such as iron or stainless steel.

[0067] The cross-sectional shape and position of the metal wire 63b can be the same as those of the metal wire 13b. However, since the metal wire 63b generates heat and heats its surroundings, the metal wire 63b does not necessarily have a helical (coil) shape and can have a different shape as needed. For example, the metal wire 63b enables local heating compared to the metal wire 13b, which performs induction heating. Accordingly, the position of the metal wire 63b can be selected as needed. For example, in the case where heating around the caps 16 is to be avoided, the metal wire 63b is not placed in the areas where heating is to be avoided. Since the metal wires 63b can be arranged to cross each other, the amount of heat generation can be easily adjusted.

[0068] The high-pressure tank and its manufacturing method according to the second embodiment have similar effects to those of the first embodiment.

Claims

[1] A method for producing a high-pressure tank, comprising: Forming a preform (30) by winding a carbon fiber (13a) around a liner (11) to form a fiber layer (13) on an outer periphery of the liner (11); and Impregnating the fiber layer (13) of the preform (30) with a curable resin and curing the curable resin, wherein, when winding the carbon fiber (13a) around the lining (11), a metal wire (13b) is wound around the lining (11) together with the carbon fiber (13a) before a thickness of the fiber layer (13) reaches half the total thickness of the fiber layer (13). [2] The method according to claim 1, wherein the carbon fiber (13a) and the metal wire (13b) are wound using a single multi-filament winding machine. [3] The method according to claim 1, wherein the carbon fiber (13a) and the metal wire (13b) are wound by passing the liner (11) sequentially through a plurality of multi-filament winding machines. [4] A method according to any one of claims 1 to 3, wherein a current is applied to the metal wire (13b) after the fiber layer (13) of the preform (30) has been impregnated with the curable resin. [5] The method according to claim 4, wherein the current is applied to the metal wire (13b) when the curable resin reaches a maximum exothermic curing temperature. [6] High-pressure tank (10), comprising: a hollow lining (11); and a reinforcing layer (12) comprising a fiber layer (13) and a resin with which the fiber layer (13) has been impregnated, the fiber layer (13) comprising a carbon fiber (13a) and a metal wire (13b), both wound around the lining (11), wherein the metal wire (13b) is arranged only at one position in the fiber layer (13), the position being closer to the liner (11) than a central position of the fiber layer (13) in a thickness direction. [7] High-pressure tank (10) according to claim 6, wherein the metal wire (13b) is made of a metal having a volume resistivity of 5.0 µΩcm or less. [8] High-pressure tank (10) according to claim 6, wherein the metal wire (13b) is made of a metal having a volume resistivity of more than 5.0 µΩcm.

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