Gas tank and method for manufacturing the same

Abstract

To provide a technique capable of improving strength of a fiber layer formed on an outer periphery of a liner of a gas tank and capable of improving an impregnation property of a resin material with respect to the fiber layer.SOLUTION: A gas tank includes: a liner having a cylindrical trunk having a center axis and domes provided on both ends of the trunk; and a reinforcement layer covering an outer periphery of the liner. The reinforcement layer includes at least one first fiber layer having a first reinforcement in which fibers are wound in such a manner of being alternately woven, and a second reinforcement in which the fibers are wound at a predetermined angle with respect to the center axis, on an outer periphery of the trunk.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a gas tank and a method for manufacturing the same.

Background Art

[0002] There is known a gas tank in which a fiber layer having a first reinforcing portion wound so that reinforcing fibers are alternately woven and a second reinforcing portion wound helically so that the reinforcing fibers are continuous with the first reinforcing portion is laminated on the outer peripheral surface of a container body (for example, Patent Document 1). The gas tank is obtained by impregnating the laminated fiber layer with a thermosetting resin and heating and curing it.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the second reinforcing portion in which the reinforcing fibers are wound helically, since the fiber density is high, the thermosetting resin may not be sufficiently impregnated.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms. [Aspect 1] A gas tank including: a liner having a cylindrical body portion having a central axis and dome portions provided at both ends of the body portion; and a reinforcing layer covering the outer periphery of the liner, the reinforcing layer including at least one first fiber layer provided on the outer periphery of the body portion and having a first reinforcing portion wound so that fibers are alternately woven and a second reinforcing portion wound at a predetermined angle with respect to the central axis, the first fiber layer including a plurality of the first reinforcing portions and a plurality of the second reinforcing portions. [Form 2] A gas tank, comprising: a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; and a reinforcing layer covering the outer periphery of the liner. The reinforcing layer has at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing portion wound such that fibers are alternately knitted and a second reinforcing portion wound at a predetermined angle with respect to the central axis. The first reinforcing portion of the upper first fiber layer has an overlapping portion laminated at least partially on the first reinforcing portion of the lower first fiber layer. The first reinforcing portion is provided in all fiber layers included in the reinforcing layer, and the overlapping portion is provided in all first fiber layers included in the reinforcing layer. The first reinforcing portion of the upper first fiber layer is arranged offset in the axial direction of the liner with respect to the first reinforcing portion of the lower first fiber layer, and the first reinforcing portion of the upper first fiber layer is laminated on a portion other than the overlapping portion of the first reinforcing portion of the lower first fiber layer. In the reinforcing layer, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing portion included in the lamination direction is 3 layers or less. Gas tank. [Form 3] A method for manufacturing a gas tank, comprising: preparing a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; and forming a base body having a fiber layer on the outer periphery of the liner. The step of forming the base body includes forming at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing portion wound such that fibers are alternately knitted and a second reinforcing portion wound at a predetermined angle with respect to the central axis. The first fiber layer includes a plurality of the first reinforcing portions and a plurality of the second reinforcing portions. [Form 4] A method for manufacturing a gas tank, comprising: preparing a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; and Reinforcement forming a base body having a layer on the outer periphery of the liner. The step of forming the base body includes forming at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing portion wound such that fibers are alternately knitted and a second reinforcing portion wound at a predetermined angle with respect to the central axis.As at least a part of the reinforcement layer A method for manufacturing a gas tank, which has a forming step, wherein a first reinforcing part of an upper first fiber layer includes an overlapping part laminated on at least a part of a first reinforcing part of a lower first fiber layer, the first reinforcing part is provided in all fiber layers included in the reinforcing layer, the overlapping part is provided in all first fiber layers included in the reinforcing layer, the first reinforcing part of the upper first fiber layer is arranged to be shifted in the axial direction of the liner with respect to the first reinforcing part of the lower first fiber layer, the first reinforcing part of the upper first fiber layer is laminated on a part other than the overlapping part of the first reinforcing part of the lower first fiber layer, and in the reinforcing layer, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing part included in the lamination direction is 3 layers or less.

[0006] (1) According to one embodiment of the present disclosure, a gas tank is provided. The gas tank includes a liner having a cylindrical body portion having a central axis and dome portions provided at both ends of the body portion, and a reinforcing layer covering the outer periphery of the liner. The reinforcing layer has at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing part wound such that fibers are alternately knitted and a second reinforcing part wound at a predetermined angle with respect to the central axis. According to the gas tank of this embodiment, by providing the first fiber layer with the second fiber layer, the strength of the fiber layer is improved, thereby improving the strength of the gas tank. In addition, by providing the first fiber layer, the impregnation performance of the resin material with respect to the fiber layer can be improved. (2) In the gas tank of the above embodiment, the first fiber layer may include a plurality of the first reinforcing parts and a plurality of the second reinforcing parts. According to the gas tank of this embodiment, by providing a plurality of the first reinforcing parts, a plurality of flow paths of the resin material through the first reinforcing parts can be formed, and the impregnation performance of the resin material with respect to the fiber layer can be improved. (3) In the gas tank of the above embodiment, the first reinforcing part of the upper first fiber layer may include an overlapping part laminated on at least a part of the first reinforcing part of the lower first fiber layer. According to the gas tank of this form, by laminating the upper first reinforcing part and the lower first reinforcing part, the impregnation performance of the resin material with respect to the fiber layer can be improved. (4) In the gas tank of the above form, the first reinforcing part may be provided in all the fiber layers included in the reinforcing layer. The overlapping part may be provided in all the first fiber layers included in the reinforcing layer. According to the gas tank of this form, by providing the overlapping part in all the first fiber layers, the impregnation performance of the resin material with respect to the fiber layer can be further improved. (5) In the gas tank of the above form, the first reinforcing part of the upper first fiber layer may be arranged so as to be shifted in the axial direction of the liner with respect to the first reinforcing part of the lower first fiber layer. According to the gas tank of this form, by arranging the first reinforcing part with a shift in the axial direction, compared with the case where the first reinforcing parts are linearly stacked along the stacking direction, stress concentration in the reinforcing layer can be suppressed. (6) In the gas tank of the above form, the first reinforcing part of the upper first fiber layer may be laminated on a portion other than the overlapping part of the first reinforcing part of the lower first fiber layer. According to the gas tank of this form, by laminating the first reinforcing part so that no overlapping part is formed on the overlapping part, stress concentration in the reinforcing layer can be suppressed. (7) In the gas tank of the above form, in the reinforcing layer, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing parts included in the stacking direction may be 3 layers or less. According to the gas tank of this form, by making the number of layers of the first reinforcing part substantially uniform in the axial direction, a gas tank 100 can be obtained in which the strength of the fiber layer and the balance in the axial direction of suppressing insufficient impregnation of the resin material are achieved. (8) In the gas tank of the above form, the outermost layer of the reinforcing layer may include a second fiber layer that includes the first reinforcing part and does not include the second reinforcing part. According to the gas tank of this form, it is possible to suppress or prevent the disorder of the arrangement of the fiber material on the outer surface of the fiber layer. (9) In the gas tank of the above-described embodiment, the innermost layer of the reinforcing layer may include the first reinforcing portion and may not include the second reinforcing portion. According to the gas tank of this embodiment, it is possible to suppress or prevent insufficient impregnation of the resin material in the innermost layer where it is difficult for the resin material to be impregnated. (10) In the gas tank of the above-described embodiment, the first fiber layer may include the first reinforcing portion on the outer periphery of the dome portion. According to the gas tank of this embodiment, by forming the first reinforcing portion on the outer periphery of the dome portion having a curvature, it is possible to suppress the problem that the fiber material deviates from the planned arrangement position as compared with the case of forming the second reinforcing portion on the outer periphery of the dome portion. The present disclosure can also be realized in various forms other than a gas tank and a method for manufacturing a gas tank. For example, it can be realized in the form of a method for forming a fiber-reinforced resin layer, a method for manufacturing a fiber-reinforced plastic, a manufacturing apparatus for a fiber-reinforced plastic, a control method for a manufacturing apparatus for a gas tank or a manufacturing apparatus for a fiber-reinforced plastic, a computer program for realizing the control method, a non-transitory recording medium on which the computer program is recorded, and the like.

Brief Description of the Drawings

[0007]

Figure 1

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Mode for Carrying Out the Invention

[0008] A. First Embodiment: FIG. 1 is an explanatory drawing showing the configuration of a gas tank 100 as the first embodiment of the present disclosure in a cross-sectional view. The gas tank 100 is a storage container for storing a high-pressure fluid of 10 to 70 MPa. The gas tank 100 can be formed in any shape. In the example of FIG. 1, the gas tank 100 has an outer appearance shape of a substantially cylindrical shape that is long along the central axis AX.

[0009] The gas tank 100 is used, for example, to store hydrogen gas supplied to a vehicle fuel cell or a stationary fuel cell. The gas tank 100 includes a liner 10, caps 16 and 17 disposed at both ends of the liner 10, and a fiber-reinforced resin layer 20 formed on the outer peripheral surfaces of the liner 10 and the caps 16 and 17. The gas tank 100 may store various fluids such as oxygen and natural gas, not limited to hydrogen gas.

[0010] The liner 10 is a container having an internal space for sealing a fluid. The liner 10 is formed of a resin having gas barrier properties such as nylon, polyamide, ethylene vinyl alcohol copolymer (EVOH), polyethylene, polypropylene, epoxy, polystyrene, etc. The liner 10 includes a cylindrical body portion 12 and two hemispherical dome portions 14 disposed at both ends of the body portion 12 along the central axis AX. An opening is provided at the top of the dome portion 14. The boundary BD shown in FIG. 1 is the connection portion between the dome portion 14 and the body portion 12 of the liner 10, and is the position where the curvature of the outer shape of the liner 10 becomes zero. The liner 10 may be formed of metal instead of resin. The body portion 12 is not limited to a cylindrical shape, and may be any cylindrical shape having a polygonal cross-sectional shape.

[0011] The caps 16 and 17 are attached to the openings provided at the tops of the respective dome portions 14 of the liner 10. The cap 16 is used, for example, for filling gas into the gas tank 100 or discharging gas from the gas tank 100. The cap 17 is sealed and is used for centering during manufacturing.

[0012] The fiber reinforced resin layer 20 is a reinforcing layer for reinforcing the liner 10. The fiber reinforced resin layer 20 is formed to cover the outer periphery of the liner 10 using fiber reinforced plastic (FRP). In the present embodiment, the fiber reinforced resin layer 20 is formed by a so-called RTM (Resin Transfer Molding) method. Specifically, a substrate (also called a “fiber preform”) having a fiber layer formed on the outer periphery of the liner 10 is prepared and placed in a mold. The “fiber layer” means a layer formed by winding a fiber material. As will be described later, the fiber layer has a structure in which two types of fiber layers, a first fiber layer L1 and a second fiber layer L2, are laminated in a plurality in the thickness direction in a predetermined order. The fiber material may be wound around the outer surfaces of the caps 16 and 17 in addition to the liner 10.

[0013] In this embodiment, carbon fiber is used as the fiber material. As the fiber material, in addition to carbon fiber, glass fiber, aramid fiber, boron fiber, high-strength polyethylene fiber, etc. can be used, and a combination of a plurality of these types of fibers may also be used. The number of layers of the fiber layer is, for example, about 10 to 20 layers, and can be arbitrarily set according to the size and shape of the gas tank 100. In this embodiment, the number of layers of the fiber layer is 12 layers.

[0014] Close the mold with the substrate disposed therein, and by pressurizing and filling the resin material into the closed mold at high speed and high pressure, the resin material is impregnated into the fiber layer. When the resin material is impregnated, for example, nitrogen gas or the like is filled inside the substrate disposed in the mold, that is, inside the liner 10, in order to apply an internal pressure capable of withstanding the external pressure applied from the resin material during impregnation. The gas tank 100 is completed by curing the resin material impregnated into the fiber layer.

[0015] FIG. 2 is an explanatory diagram showing the appearance of a substrate provided with a first fiber layer L1 on the outer periphery of the body portion 12. The "first fiber layer" means a fiber layer provided with a first reinforcing portion 210 and a second reinforcing portion 220 in a range RG2 that becomes the outer periphery of the body portion 12. The "first reinforcing portion" is a portion formed by so-called braiding winding among the fiber layers. The "braiding winding" means a method of winding the fiber material so as to be alternately knitted. The "second reinforcing portion" is a portion formed by so-called helical winding among the fiber layers. The "helical winding" means a method of winding the fiber material around the outer periphery of the body portion 12 at a predetermined one angle with respect to the central axis AX of the liner 10, and then winding it at a predetermined other angle with respect to the central axis AX.

[0016] In this embodiment, the first fiber layer L1 includes a plurality of first reinforcing portions 210 and a plurality of second reinforcing portions 220, and has a so-called striped appearance. The arrangement positions, numbers, and widths of the plurality of first reinforcing portions 210 and the plurality of second reinforcing portions 220 in the range RG2 of the first fiber layer L1 differ depending on the number of layers laminated on the liner 10, as will be described later. In the example of FIG. 2, six first reinforcing portions 210 and seven second reinforcing portions 220 are alternately arranged. Each first reinforcing portion 210 and each second reinforcing portion 220 have a predetermined width along the axial direction and are wound around the outer periphery of the body portion 12 in the circumferential direction. Note that in FIG. 2, for ease of understanding of the technology, the first reinforcing portion 210 and the second reinforcing portion 220 are schematically shown and do not accurately show the dimensions of each part.

[0017] As shown in FIG. 2, in this embodiment, the first fiber layer L1 includes first reinforcing portions 210 in the range RG1 that is the outer periphery of the dome portion 14. According to the gas tank 100 of this embodiment, by forming the first reinforcing portions 210 on the outer periphery of the dome portion 14 having a curvature, it is possible to suppress the problem of the fiber material slipping compared to helical winding. Note that on the premise that a gas tank 100 with sufficient strength can be obtained, in the first fiber layer L1, second reinforcing portions 220 may be formed in the range RG1, or the fiber layer in the range RG1 may be omitted and only the first reinforcing portions 210 may be formed on the outer periphery of the body portion 12.

[0018] In the first fiber layer L1, the first reinforcing portions 210 in the range RG1, the first reinforcing portions 210 and the second reinforcing portions 220 in the range RG2 are continuously formed. Specifically, after forming the first reinforcing portions 210 in one range RG1, the first reinforcing portions 210 and the second reinforcing portions 220 in the range RG2 are continuously formed. In the range RG2, the second reinforcing portions 220 and the first reinforcing portions 210 are alternately formed while switching the winding method of the fiber material. After forming the fiber layer in the range RG2, the first fiber layer L1 is completed by forming the first reinforcing portions 210 in the other range RG1.

[0019] In FIG. 2, the boundary portion BR is schematically shown in the first fiber layer L1. In the example of FIG. 2, it is the position where, after forming the first reinforcing portion 210 in one range RG1, the formation is switched to the second reinforcing portion 220. The boundary portion BR includes the boundary BD between the dome portion 14 and the body portion 12 of the liner 10 and has a predetermined width. Specifically, the boundary portion BR is a range having a predetermined width for allowing a distance LW of two halves of the width WF of the fiber material as an error in the front and rear in the axial direction from the boundary BD.

[0020] FIG. 3 is an explanatory view showing an enlarged partial range AR1 of the first reinforcing portion 210. FIG. 4 is a cross-sectional view showing the position IV-IV of FIG. 3. As shown in FIGS. 3 and 4, the fiber material has a strip-like appearance shape having a predetermined width WF of, for example, about several millimeters. However, the fiber material may have an arbitrary shape such as a filament shape or a flat plate shape. The thickness per sheet of the fiber material can be set to an arbitrary thickness of, for example, 0.5 millimeter or less. In the present embodiment, the thickness per sheet of the fiber material is 0.3 millimeter.

[0021] As shown in FIG. 3, the fiber material 211 is wound at an elevation angle θ1 with respect to the central axis AX of the liner 10. The fiber materials 212 to 215 are wound at a depression angle θ2 with respect to the central axis AX of the liner 10. The angles θ1 and θ2 can be arbitrarily set. The angles θ1 and θ2 are preferably set in consideration of, for example, the stress acting on the body portion 12 of the liner 10. In the present embodiment, in order to obtain a gas tank 100 with sufficient strength, the angle θ1 is set, for example, in the vicinity of +54.7 degrees with respect to the central axis AX, and the angle θ2 is set, for example, at -54.7 degrees with respect to the central axis AX.

[0022] As shown in FIG. 4, the first reinforcing portion 210 is formed by alternately arranging the fiber materials 211 and 212 to 215 inside and outside in the stacking direction and interlacing them. In the present embodiment, the fiber materials 211 are alternately arranged in pairs of two fiber materials. The first reinforcing portion 210 includes a layer L11 having a thickness of one fiber material disposed outside the gas tank 100 and a layer L12 having a thickness of one fiber material disposed inside the gas tank 100. The thickness of each layer of the first reinforcing portion 210 is the thickness of two fiber materials.

[0023] As shown in FIG. 3, since the first reinforcing portion 210 is formed by interlacing a plurality of fiber materials, the binding force between the fiber materials is higher than that in the case of helical winding. Therefore, for example, the first reinforcing portion 210 can suppress problems such as the arrangement of the fiber materials being disordered and the fiber materials slipping when winding the fiber materials, thereby deviating from the planned arrangement position, as compared with the second reinforcing portion 220.

[0024] As shown in FIG. 3, in the first reinforcing portion 210, gaps GP may occur between the woven fiber materials due to the interlacing of the plurality of fiber materials. Therefore, in the first reinforcing portion 210, the resin material can be more easily impregnated than in the case of a fiber layer formed by the fiber materials being in close contact with each other as in helical winding.

[0025] FIG. 5 is an explanatory diagram showing an enlarged view of the appearance of the second reinforcing portion 220. In FIG. 5, a partial range AR2 of FIG. 4 is shown enlarged. As shown in FIG. 5, the fiber material 221 is wound at an elevation angle θ3 with respect to the central axis AX of the liner 10. The fiber materials 222 to 225 are wound parallel to each other at a depression angle θ4 with respect to the central axis AX. The angles θ3 and θ4 can be arbitrarily set in consideration of, for example, the stress acting on the body portion 12 of the liner 10. In the present embodiment, the angles θ3 and θ4 are configured in the same manner as the above-described angles θ1 and θ2.

[0026] FIG. 6 is a cross-sectional view showing the position VI-VI of FIG. 5. As shown in FIG. 6, the second reinforcing part 220 has a layer L21 disposed outside the gas tank 100 such as a fiber material 221, and a layer L22 disposed inside the gas tank 100 such as fiber materials 222 to 225. Note that the layer L21 and the layer L22 are continuous with the fiber materials forming the above-described layer L11 and layer L12. In the following description, the number of layers of the first fiber layer L1 counts the state in which the layers L21 and L22 are combined as "one layer", and similarly, the state in which the layers L11 and L12 are combined is counted as "one layer". Note that in the present embodiment, the thickness of the second reinforcing part 220 is 0.6 millimeters.

[0027] As shown in FIGS. 5 and 6, the second reinforcing part 220 is wound in a state where a plurality of fiber materials are in close contact with each other by being arranged parallel to each other by helical winding. Therefore, the density of the fiber material becomes higher than that of the braiding winding, and the strength of the gas tank 100 becomes higher. In the second reinforcing part 220, since the fiber materials are in close contact with each other, for example, when a resin material is pressure-filled by the RTM method, the resin material may be less likely to be impregnated than in the first reinforcing part 210.

[0028] FIG. 7 is an explanatory view showing a schematic configuration of a manufacturing apparatus 300 for the gas tank 100. The manufacturing apparatus 300 is an apparatus for winding a fiber material around a liner 10. The manufacturing apparatus 300 includes a first supply unit 42 and a second supply unit 44 for supplying a fiber material, and a moving mechanism (not shown) for moving the liner 10 in the direction DRT. Note that in FIG. 7, two first supply units 42 and two second supply units 44 are shown for convenience of illustration, but actually, the number is provided corresponding to the number of fiber materials to be wound.

[0029] The manufacturing apparatus 300 rotates a first supply unit 42 that feeds out the fiber material 22A and a second supply unit 44 that feeds out the fiber material 22B along movement paths OR1 and OR2 around the liner 10, respectively. While moving the liner 10 in the direction DRT along the axial direction, the manufacturing apparatus 300 winds the fiber materials 22A and 22B around the outer periphery of one dome portion 14 of the liner 10, the outer periphery of the body portion 12, and the outer periphery of the other dome portion 14 in this order.

[0030] The manufacturing apparatus 300 can switch the movement paths OR1 and OR2 to different paths depending on whether helical winding or braiding winding is performed. In the example of FIG. 7, the movement paths OR1 and OR2 for helical winding are shown.

[0031] FIG. 8 is an explanatory diagram showing the movement paths OR1 and OR2 of the first supply unit 42 and the second supply unit 44 when helical winding is performed. The movement path OR1 of the first supply unit 42 is shown by a solid line, and the movement path OR2 of the second supply unit 44 is shown by a dashed line. The first supply unit 42 and the second supply unit 44 are arranged, for example, on two concentric movement paths OR1 and OR2 surrounding the central axis AX. The movement path OR1 is arranged at a position farther from the central axis AX than the movement path OR2, that is, on the outer side in the radial direction. Note that the movement paths OR1 and OR2 are not limited to concentric circles and may be orbits of any shape that can rotate around the central axis AX.

[0032] As shown in FIG. 8, the movement direction DR1 of the first supply unit 42 on the movement path OR1 and the movement direction DR2 of the second supply unit 44 on the movement path OR2 are opposite to each other. As shown in FIG. 7, a plurality of fiber materials 22B are wound around the outer periphery of the liner 10 at an angle θ4 that is a depression angle with respect to the central axis AX by the second supply unit 44 rotating in the movement direction DR2. A plurality of fiber materials 22A are wound around the outside of the fiber material 22B at an angle θ3 that is an elevation angle with respect to the central axis AX by the first supply unit 42 rotating in the movement direction DR1. As a result, a second reinforcing portion 220 having a layer L21 on the outside and a layer L22 on the inside is formed on the outer periphery of the body portion 12.

[0033] FIG. 9 is an explanatory diagram showing the movement paths OR1b and OR2b of the first supply unit 42 and the second supply unit 44 when performing braiding winding. For ease of understanding of the technology, in FIG. 9, the movement path OR1b of the first supply unit 42 is shown by a solid line, and the movement path OR2b of the second supply unit 44 is shown by a dashed line.

[0034] As shown in FIG. 9, the moving direction DR1 of the first supply unit 42 on the movement path OR1b and the moving direction DR2 of the second supply unit 44 on the movement path OR2b are opposite to each other. In the movement paths OR1b and OR2b, a state where the first supply unit 42 is on the inner side in the radial direction and the second supply unit 44 is on the outer side in the radial direction, and a state where the second supply unit 44 is on the inner side in the radial direction and the first supply unit 42 is on the outer side in the radial direction alternate. As a result, the fiber material 22B supplied at an angle θ2 that is a depression angle with respect to the central axis AX and the fiber material 22A supplied at an angle θ1 that is an elevation angle with respect to the central axis AX are wound around the outer periphery of the liner 10 so as to be alternately braided. As a result, the first reinforcing portion 210 having the layer L11 on the outside and the layer L12 on the inside is formed on the outer periphery of the body portion 12.

[0035] The manufacturing apparatus 300 can switch between the movement paths OR1, OR2 and the movement paths OR1b, OR2b at any timing with respect to the liner 10 moving in the direction DRT. When forming the first fiber layer L1 shown in FIG. 2, for example, the manufacturing apparatus 300 performs braiding winding along the movement paths OR1b, OR2b around the outer periphery of one of the dome portions 14, and then, at the boundary portion BR, switches the movement paths OR1b, OR2b to the movement paths OR1, OR2 and performs helical winding around the body portion 12. On the outer periphery of the body portion 12, the manufacturing apparatus 300 forms the fiber layer in the range RG2 while alternately switching between helical winding and braiding winding by switching the movement path at the switching position between the first reinforcing portion 210 and the second reinforcing portion 220. When finishing forming the fiber layer around the outer periphery of the body portion 12, the manufacturing apparatus 300 switches from the movement paths OR1, OR2 to the movement paths OR1b, OR2b at the boundary portion BR between the body portion 12 and the other dome portion 14 and performs braiding winding around the other dome portion 14. When forming the first fiber layer L1, the manufacturing apparatus 300 performs braiding winding on the entire liner 10 without switching the movement paths OR1, OR2.

[0036] FIG. 10 is an explanatory view showing the appearance of a base body provided with a second fiber layer L2 on the outer periphery of the body portion 12. The "second fiber layer" means a fiber layer provided with a first reinforcing portion 210 in a range RG2 that is the outer periphery of the body portion 12 and not provided with a second reinforcing portion 220 in the range RG2. The second fiber layer L2 differs from the first fiber layer L1 in that it does not include the second reinforcing portion 220. In the present embodiment, the second fiber layer L2 is provided with the first reinforcing portion 210 not only in the range RG2 but also in a range RG1 that is the outer periphery of the dome portion 14 of the liner 10. That is, the first fiber layer L1 is provided with the first reinforcing portion 210 on the entire outer periphery of the liner 10 by continuously forming only the first reinforcing portion 210 across the ranges RG1 and RG2. When forming the second fiber layer L2, the manufacturing apparatus 300 performs braiding winding on the entire liner 10 without switching the movement paths OR1 and OR2. Since the second fiber layer L2 is formed by braiding winding on the entire outer periphery of the liner 10, it is also called a "braiding winding layer". In the following description, the number of layers of the second fiber layer L2, similar to the first fiber layer L1, counts the state where the layers L21 and L22 are combined as "one layer". In the present embodiment, the thickness of the first reinforcing portion 210 is 0.6 millimeters. Also, on the premise that a gas tank 100 with sufficient strength can be obtained, a second reinforcing portion 220 may be formed in the range RG1 in the second fiber layer L2, or the fiber layer in the range RG1 may be omitted and only the first reinforcing portion 210 may be formed on the outer periphery of the body portion 12.

[0037] FIG. 11 is an explanatory view schematically showing the configuration of the fiber-reinforced resin layer 20 of the gas tank 100 according to the first embodiment of the present disclosure. The table TB1 shown in FIG. 11 corresponds to a cross-sectional view of the fiber-reinforced resin layer 20 in the range RG2. The table TB1 schematically shows the arrangement relationship between the first fiber layer L1 and the second fiber layer L2 in the stacking direction and the arrangement relationship between the first reinforcing portion 210 and the second reinforcing portion 220 in the axial direction. For the sake of illustration, only a part of the fiber layers in the range RG2 is shown in the table TB1, but actually, fiber layers having the same configuration as the table TB1 are repeatedly formed on the right side of the right end of the table TB1.

[0038] The horizontal axis CL1 of Table TB1 indicates the axial distance starting from the boundary BD at the left end, with the unit being centimeters. The vertical axis RW indicates the number of fiber layers included in the fiber-reinforced resin layer 20 on the liner 10. The lowermost part of the vertical axis RW is the liner 10, and the part below it indicates the inside of the gas tank 100. The uppermost part of the vertical axis RW is the 12th fiber layer, which is the outermost layer of the fiber-reinforced resin layer 20. The first fiber layer laminated on the outer surface of the liner 10 is also called the "innermost layer", and the part between the innermost layer and the outermost layer (the 2nd layer to the 11th layer in this embodiment) is also called the "inner layer". In Table TB1 and subsequent Tables TB2 to TB5, for the convenience of illustration, the first reinforcing part 210 and the second reinforcing part 220 are shown with a width of 1 centimeter × the height of one fiber layer as one block. To facilitate the understanding of the technology, hatching is applied to the first reinforcing part 210.

[0039] As shown in FIG. 11, in the gas tank 100 of this embodiment, the inner layer of the fiber-reinforced resin layer 20 is provided with a first reinforcing part 210 formed by braiding winding and a second reinforcing part 220 formed by helical winding on the outer periphery of the body part 12 in the first fiber layer L1. By the first fiber layer L1 including the second reinforcing part 220, the strength of the gas tank 100 can be improved, and by including the first reinforcing part 210, the impregnation performance of the resin material with respect to the fiber layer can be improved. Therefore, a gas tank 100 can be obtained in which the balance between suppressing insufficient impregnation of the resin material and improving the strength is achieved. By providing both the first reinforcing part 210 and the second reinforcing part 220 in one layer of the fiber layer, a gas tank 100 with a better balance of shape, strength, and impregnation performance per fiber layer can be obtained compared to the case where the first reinforcing part 210 and the second reinforcing part 220 are separately provided in different layers.

[0040] In the gas tank 100 of the present embodiment, a second fiber layer L2 is disposed on the outermost layer of the fiber reinforced resin layer 20. When the resin material is pressure-filled into the mold by the RTM method, the resin material at high speed and high pressure may collide with the fiber layer, resulting in problems such as disorder of the arrangement of the fiber material, peeling or floating of the fiber material. By disposing the second fiber layer L2 having only the first reinforcing portion 210 with a high binding force between the fiber materials on the outermost layer, when the resin material is impregnated into the fiber layer, the disorder of the arrangement of the fiber materials on the outer surface of the fiber layer due to the collision of the resin material and the peeling of the fiber materials can be suppressed or prevented.

[0041] In the gas tank 100 of the present embodiment, a second fiber layer L2 is disposed on the innermost layer of the fiber reinforced resin layer 20. The innermost layer of the fiber reinforced resin layer 20 is easily affected by the deformation of the liner 10, and the density of the fiber material tends to be higher than that of the inner layer fiber layer and the like. Therefore, the innermost layer of the fiber reinforced resin layer 20 may be less impregnated with the resin material than other layers. This feature becomes particularly prominent when the liner 10 is made of resin that is easily deformed. In the present embodiment, by disposing the second fiber layer L2 having only the first reinforcing portion 210 that is easily impregnated with the resin material on the innermost layer of the fiber reinforced resin layer 20, insufficient impregnation of the resin material in the innermost layer can be suppressed or prevented.

[0042] In the gas tank 100 of the present embodiment, the inner layer of the fiber reinforced resin layer 20 is entirely formed of the first fiber layer L1, and both the first reinforcing portion 210 and the second reinforcing portion 220 are included in each layer of the inner layer. According to the gas tank 100 configured in this way, a gas tank 100 in which the shape, strength, and impregnation performance of all layers of the fiber layer are balanced can be obtained.

[0043] In this embodiment, the first reinforcing part 210 and the second reinforcing part 220 are arranged according to a predetermined rule and are arranged at different positions for each layer of the first fiber layer L1. FIG. 11 shows a region T1 surrounded by a broken line. The region T1 is a region with a height of 5 layers and a width of 15 centimeters. In the example of FIG. 11, the inner layer is divided into 4 regions T1. In the region T1 shown at the lower left of FIG. 11, a first reinforcing part 210 with an axial width of 5 centimeters is arranged at the left end of the 6th layer, and a second reinforcing part 220 with a width of 10 centimeters is arranged adjacent to the first reinforcing part 210. In contrast, in the 5th layer, the first reinforcing part 210 is arranged at a position axially shifted by 3 centimeters with respect to the arrangement position of the 6th layer. Similarly, in the 4th layer, 3rd layer, and 2nd layer, they are arranged stepwise axially shifted by 3 centimeters each with respect to the upper layer. In the region T1, when the first reinforcing part 210 and the second reinforcing part 220 reach the right end of the region T1 by repeating the shift, they may be arranged at the repeated position from the left end. In the inner layer of the fiber-reinforced resin layer 20, further, the region T1 is repeatedly arranged in the axial direction and the stacking direction, so that the first reinforcing part 210 and the second reinforcing part 220 are regularly arranged. Note that FIG. 2 described above shows an example of the appearance of the base body in a state where the 4th first fiber layer L1 is formed.

[0044] As shown in FIG. 11, the first reinforcing portion 210 includes an overlapping portion OL. The overlapping portion OL is a portion where at least a part of the first reinforcing portion 210 of the lower first fiber layer L1 is overlapped and laminated with the first reinforcing portion 210 of the upper first fiber layer L1. The "upper layer" means a single layer of fiber layer laminated above the target fiber layer. Similarly, the "lower layer" means a single layer of fiber layer on the lower side. In the example of FIG. 11, the overlapping portion OL is a region of the right end 2 cm of the upper first reinforcing portion 210, and is a region overlapped and laminated with respect to the region of the left end 2 cm of the lower first reinforcing portion 210. According to the gas tank 100 of the present embodiment, by overlapping and laminating the upper first reinforcing portion 210 and the lower first reinforcing portion 210, a flow path for smoothly flowing the resin material can be formed between the layers of the fiber layer, and the impregnation performance of the resin material with respect to the fiber layer can be improved. Note that the width of the overlapping portion OL is preferably 0.1 cm or more in order for the resin material to smoothly flow between the layers of the first reinforcing portion 210. In the present embodiment, the width of the overlapping portion OL is set to 2 cm in consideration of the improvement of the impregnation performance of the resin material and the mechanical error of the switching position of the winding method of the fiber material by the manufacturing apparatus 300.

[0045] FIG. 12 is an explanatory diagram schematically showing a flow path of the resin material when the fiber layer of the gas tank 100 of the present embodiment is impregnated with the resin material. The table TB2 shown in FIG. 12 is obtained by adding arrows D1 to D4 for indicating the flow direction of the resin material to the table TB1 shown in FIG. 11. In the RTM method, a high-speed and high-pressure resin material is filled into the mold in a state where the base body is disposed inside and the mold is closed. As shown by the arrow D1, the high-speed and high-pressure resin material collides with the outermost layer of the fiber layer in the mold and is impregnated into the fiber layer.

[0046] In the gas tank 100 of the present embodiment, the first reinforcing part 210 is provided in all the fiber layers included in the fiber-reinforced resin layer 20, and the overlapping part OL is provided in all the first fiber layers L1 included in the fiber-reinforced resin layer 20. By providing the overlapping part OL between each layer from the outermost layer to the innermost layer of the fiber-reinforced resin layer 20, as shown by the arrow D2, a flow path through which the resin material can smoothly flow between the layers of the fiber layer can be formed across all layers. As a result, the impregnation performance of the resin material with respect to the fiber layer can be improved. As shown by the arrow D3, in the second reinforcing part 220 of each layer, while the resin material is being supplied from the first reinforcing part 210 and the second reinforcing part 220 of the upper layer and the lower layer, more resin material is impregnated axially from the first reinforcing part 210 of each layer. The resin material that has reached the innermost layer is impregnated over the entire area of the second fiber layer L2 along the outer surface of the liner 10, as shown by the arrow D4.

[0047] In the gas tank 100 of the present embodiment, the first fiber layer L1 includes a plurality of first reinforcing parts 210 and a plurality of second reinforcing parts 220. By providing a plurality of first reinforcing parts 210, a plurality of flow paths for the resin material through the first reinforcing parts 210 can be formed, and the impregnation performance of the resin material with respect to the fiber layer can be further improved. Further, by dispersing and arranging the first reinforcing parts 210 at a plurality of positions in the axial direction, a gas tank 100 can be obtained in which the strength of the fiber layer in the axial direction and the suppression of insufficient impregnation of the resin material are balanced.

[0048] As shown in FIG. 11, in the gas tank 100 of the present embodiment, the first reinforcing part 210 of the upper first fiber layer L1 is arranged with an axial shift of 3 centimeters with respect to the first reinforcing part 210 of the lower first fiber layer L1. By arranging the first reinforcing parts 210 with an axial shift, stress concentration within the fiber-reinforced resin layer 20 can be suppressed as compared with the case where the first reinforcing parts 210 are linearly overlapped and arranged along the lamination direction.

[0049] In the gas tank 100 of the present embodiment, the first reinforcing portion 210 included in the upper first fiber layer L1 is laminated on a portion of the first reinforcing portion 210 included in the lower first fiber layer L1 other than the overlapping portion OL. That is, the upper first reinforcing portion 210 is laminated so as not to be formed on the overlapping portion OL formed in the lower layer, and the overlapping portion OL is not formed on the overlapping portion OL. By laminating so that the overlapping portion OL is not overlapped in three or more layers, stress concentration in the fiber reinforced resin layer 20 can be suppressed.

[0050] As shown in FIG. 11, on the horizontal axis CL2 of the table TB1, the total value of the number of layers of the first reinforcing portion 210 included in the lamination direction at a specific position is shown, and the total value is shown for each distance from the boundary BD. The horizontal axis CL3 shows the occupancy rate (unit: %) of the number of layers of the first reinforcing portion 210 in the fiber layer for each distance from the boundary BD. For example, at a position where the distance from the boundary BD is 1-2 cm in the range RG2, the first reinforcing portion 210 exists in each of the innermost layer, the first layer, the sixth-seventh layers, the eleventh layer, and the outermost layer, and the total value of the number of layers of the first reinforcing portion 210 is 6 layers. In the present embodiment, the number of layers of the fiber reinforced resin layer 20 is 12 layers, and the occupancy rate of the first reinforcing portion 210 at this position is 50%.

[0051] From the viewpoint of improving the impregnation performance of the resin material, the occupancy rate of the first reinforcing portion 210 included in the lamination direction is preferably 30% or more. Further, from the viewpoint of improving the strength in the fiber reinforced resin layer 20, the occupancy rate of the second reinforcing portion 220 is preferably 30% or more, and the occupancy rate of the first reinforcing portion 210 is preferably less than 70%. The occupancy rate of the first reinforcing portion 210 included in the lamination direction is from 33% to 50%, and the balance between the improvement of the strength in the gas tank 100 and the impregnation performance of the resin material can be improved.

[0052] In the gas tank 100 of the present embodiment, as indicated by each value on the horizontal axis CL2, the total number of layers of the first reinforcing portions 210 included in the stacking direction is from 4 to 6 layers. That is, in the fiber-reinforced resin layer 20, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing portions 210 included in the stacking direction is 3 layers. By making the number of layers of the first reinforcing portions 210 included in the stacking direction of the fiber-reinforced resin layer 20 substantially uniform in the axial direction, it is possible to obtain a gas tank 100 in which the balance between the strength of the fiber layer and the suppression of insufficient impregnation of the resin material is achieved in the axial direction. Note that the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing portions 210 included in the stacking direction is preferably a small number of 3 layers or less, and may be, for example, zero, 1 layer, or 2 layers.

[0053] B. Second Embodiment: FIG. 13 is an explanatory diagram schematically showing the configuration of the fiber-reinforced resin layer 20 of the gas tank 100 according to the second embodiment of the present disclosure. The table TB3 shown in FIG. 13 corresponds to a cross-sectional view of the fiber-reinforced resin layer 20 in the range RG2. The gas tank 100 of the second embodiment is different from the gas tank 100 of the first embodiment in the arrangement positions of the first reinforcing portion 210 and the second reinforcing portion 220 in the fiber-reinforced resin layer 20, and the other configurations are the same as those of the gas tank 100 of the first embodiment.

[0054] As shown in Table TB3, in the fiber-reinforced resin layer 20, the first reinforcing portions 210 are arranged according to the first arrangement CS1 and the second arrangement CS2. In the first arrangement CS1, the first reinforcing portions 210 arranged at the end portion on the boundary BD side in the 11th layer are arranged while being gradually axially shifted away from the boundary BD as they go to the lower layer. The second arrangement CS2 is an arrangement in which the first reinforcing portions 210 arranged at a position 30 centimeters away from the boundary BD in the 11th layer are arranged while being gradually axially shifted closer to the boundary BD as they go to the lower layer. Further, by arranging the first arrangement CS1 and the second arrangement CS2 so as to cross each other, the first reinforcing portions 210 are arranged in a so-called cross shape so as to be line-symmetric with respect to the lamination direction at the position 15 centimeters from the boundary BD as the axis of symmetry. According to the gas tank 100 of the present embodiment, by arranging the first reinforcing portions 210 in line symmetry and adopting a truss structure arranged in a plurality of substantially triangular shapes in a cross-sectional view, the strength of the fiber-reinforced resin layer 20 can be improved.

[0055] C. Third Embodiment: FIG. 14 is an explanatory diagram schematically showing the configuration of the fiber-reinforced resin layer 20 of the gas tank 100 according to the third embodiment of the present disclosure. Table TB4 shown in FIG. 14 corresponds to a cross-sectional view of the fiber-reinforced resin layer 20 in the range RG2. The gas tank 100 of the third embodiment is different from the gas tank 100 of the first embodiment in the arrangement positions of the first reinforcing portion 210 and the second reinforcing portion 220 in the fiber-reinforced resin layer 20, and the other configurations are the same as those of the gas tank 100 of the first embodiment.

[0056] As shown in FIG. 14, in the gas tank 100 of the present embodiment, the first reinforcing portions 210 included in the upper first fiber layer L1 are stacked and laminated in a so-called stack shape with respect to the first reinforcing portions 210 provided in the lower first fiber layer L1. By arranging the first reinforcing portions 210 linearly along the lamination direction, it becomes easy to impregnate the resin material to the innermost layer of the fiber-reinforced resin layer 20, and it is possible to suppress or prevent insufficient impregnation of the resin material at the innermost layer.

[0057] D. Fourth Embodiment: FIG. 15 is an explanatory diagram schematically showing the configuration of the fiber reinforced resin layer 20 of the gas tank 100 according to the fourth embodiment of the present disclosure. Table TB5 shown in FIG. 15 corresponds to a cross-sectional view of the fiber reinforced resin layer 20 in the range RG2. The gas tank 100 of the fourth embodiment is different from the gas tank 100 of the first embodiment in the arrangement positions of the first reinforcing portion 210 and the second reinforcing portion 220 in the fiber reinforced resin layer 20, and the other configurations are the same as those of the gas tank 100 of the first embodiment.

[0058] In the gas tank 100 of the first embodiment, an example is shown in which the first reinforcing portion 210 is arranged while being gradually shifted by 3 centimeters in the direction away from the boundary BD step by step as it goes toward the lower layer. On the other hand, in the gas tank 100 of the fourth embodiment, the first reinforcing portion 210 is arranged while being gradually shifted by 1 centimeter in the direction away from the boundary BD step by step as it goes toward the lower layer. Thus, the displacement amount between the first reinforcing portion 210 in the upper layer and the first reinforcing portion 210 in the lower layer is not limited to 3 centimeters and may be set to any distance. Further, the displacement amount is not limited to the distance and may be set by the number of sheets of the fiber material or the like.

[0059] In the gas tank 100 of the first embodiment, an example is shown in which the first reinforcing portion 210 in the upper layer is laminated on a portion other than the overlapping portion OL of the first reinforcing portion 210 in the lower layer. On the other hand, as shown in FIG. 15, the overlapping portions OL may be stacked in three or more layers.

[0060] E. Other Embodiments: (E1) In the above first embodiment, an example is shown in which the inner layer is provided with 10 layers of the first fiber layer L1. However, the first fiber layer L1 in the inner layer is not limited to 10 layers and may be a single layer number or any number of layers of 2 or more.

[0061] (E2) In the above first embodiment, an example is shown in which the outermost layer and the innermost layer are the second fiber layer L2. In contrast, the outermost layer may be the first fiber layer L1, the innermost layer may be the first fiber layer L1, or both the outermost layer and the innermost layer may be the first fiber layer L1.

[0062] (E3) In the first embodiment described above, an example was shown in which the overlapping portion OL is an area of 2 centimeters at the right end of the upper first reinforcing portion 210 and is laminated on top of an area of 2 centimeters at the left end of the lower first reinforcing portion 210. In contrast, the size of the range in which the upper first reinforcing portion 210 is laminated on the lower first reinforcing portion 210 for the overlapping portion OL may be arbitrarily set. For example, it may be formed by laminating the upper first reinforcing portion 210 over the entire area of the lower first reinforcing portion 210, or it may be formed by laminating it so that the entire area of the upper first reinforcing portion 210 is included in the lower first reinforcing portion 210. Further, when the impregnation performance of the resin material of the fiber layer is sufficient, the first reinforcing portion 210 included in the upper first fiber layer L1 and the first reinforcing portion 210 included in the lower first fiber layer L1 do not have to be laminated on top of each other, and the overlapping portion OL may be omitted. Also, the overlapping portion OL does not have to be provided in all the fiber layers of the fiber reinforced resin layer 20, and may be provided only in some of the fiber layers included in the fiber reinforced resin layer 20.

[0063] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each of the forms described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Description of Reference Numerals

[0064] 10...liner, 12...barrel part, 14...dome part, 16, 17...base, 20...fiber reinforced resin layer, 22A, 22B...fiber material, 42...first supply part, 44...second supply part, 100...gas tank, 210...first reinforcement part, 211~215, 221~225...fiber material, 220...second reinforcement part, 300...manufacturing apparatus, AX...central axis, BD...boundary, BR...boundary part, GP...gap, L1...first fiber layer, L11, L12, L21, L22...layer, L2...second fiber layer, OL...overlap part, T1...region, TB1~TB5...surface

Claims

1. A gas tank, comprising: a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; and a reinforcing layer covering the outer periphery of the liner, wherein the reinforcing layer has at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing portion wound such that fibers are alternately woven and a second reinforcing portion wound at a predetermined angle with respect to the central axis; the first fiber layer includes a plurality of the first reinforcing portions and a plurality of the second reinforcing portions; a gas tank.

2. A gas tank, comprising: a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; and a reinforcing layer covering the outer periphery of the liner, wherein the reinforcing layer has at least one first fiber layer provided on the outer periphery of the body portion, the first fiber layer including a first reinforcing portion wound such that fibers are alternately woven and a second reinforcing portion wound at a predetermined angle with respect to the central axis; the first reinforcing portion of the upper first fiber layer has an overlapping portion laminated at least partially on the first reinforcing portion of the lower first fiber layer; the first reinforcing portion is provided in all fiber layers included in the reinforcing layer; the overlapping portion is provided in all first fiber layers included in the reinforcing layer; the first reinforcing portion of the upper first fiber layer is arranged shifted in the axial direction of the liner with respect to the first reinforcing portion of the lower first fiber layer; the first reinforcing portion of the upper first fiber layer is laminated on a portion other than the overlapping portion of the first reinforcing portion of the lower first fiber layer; in the reinforcing layer, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing portions included in the lamination direction is 3 layers or less; a gas tank.

3. The gas tank according to claim 1 or claim 2, wherein the outermost layer of the reinforcing layer includes a second fiber layer including the first reinforcing portion and not including the second reinforcing portion.

4. The gas tank according to claim 1 or claim 2, wherein the innermost layer of the reinforcing layer includes a second fiber layer including the first reinforcing portion and not including the second reinforcing portion.

5. The gas tank according to claim 1 or claim 2, wherein the first fiber layer includes the first reinforcing portion on the outer periphery of the dome portion; a gas tank.

6. A method for manufacturing a gas tank, comprising: a step of preparing a liner having a cylindrical body portion with a central axis and dome portions provided at both ends of the body portion; A step of forming a base body having a fiber layer on the outer periphery of the liner, The step of forming the base body is, A step of forming at least one first fiber layer provided on the outer periphery of the body portion with a first reinforcing portion wound so that the fibers are alternately woven and a second reinforcing portion wound with the fibers at a predetermined angle with respect to the central axis, The first fiber layer includes a plurality of the first reinforcing portions and a plurality of the second reinforcing portions. A method for manufacturing a gas tank.

7. A method for manufacturing a gas tank, comprising: A step of preparing a liner having a cylindrical body portion having a central axis and dome portions provided at both ends of the body portion, A step of forming a base body having a reinforcing layer on the outer periphery of the liner, The step of forming the base body is, A step of forming at least one first fiber layer provided on the outer periphery of the body portion with a first reinforcing portion wound so that the fibers are alternately woven and a second reinforcing portion wound with the fibers at a predetermined angle with respect to the central axis as at least a part of the reinforcing layer, The first reinforcing portion of the upper first fiber layer includes an overlapping portion laminated at least partially on the first reinforcing portion of the lower first fiber layer, The first reinforcing portion is provided in all fiber layers included in the reinforcing layer, The overlapping portion is provided in all first fiber layers included in the reinforcing layer, The first reinforcing portion of the upper first fiber layer is arranged shifted in the axial direction of the liner with respect to the first reinforcing portion of the lower first fiber layer, The first reinforcing portion of the upper first fiber layer is laminated on a portion other than the overlapping portion of the first reinforcing portion of the lower first fiber layer, In the reinforcing layer, the difference between the maximum value and the minimum value of the total number of layers of the first reinforcing portions included in the lamination direction is 3 layers or less. A method for manufacturing a gas tank.

8. The method for manufacturing a gas tank according to claim 6 or claim 7, further comprising: A step of disposing the formed base body inside a mold and closing the mold, A step of filling the closed mold with a resin material and impregnating the fiber layer of the base body with the resin material. A method for manufacturing a gas tank.

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