Method for manufacturing a high-pressure tank

Abstract

A method of manufacturing a high-pressure tank (100) having a lining (20) having gas barrier properties and a reinforcement layer (30) disposed around the lining (20), the method comprising: (a) a step of forming a reinforcing tube portion (60) made of fiber-reinforced resin, the reinforcing tube portion (60) comprising a straight tube portion (62) and reduced-diameter portions (64) arranged at respective ends of the straight tube portion (62) and whose outer diameter decreases toward end portions of the reinforcing tube portion (60); (b) a step of forming reinforcing dome portions (50) made of fiber-reinforced resin and shaped such that an outer diameter of each of the reinforcing dome portions (50) increases from one end to an opening end (51) at another end; (c) a step of forming a composite body (40) by arranging the reinforcing dome portions (50) at respective ends of the reinforcing tube portion (60) such that the opening end (51) of each of the reinforcing dome portions (50) is positioned on an outer surface of a corresponding one of the reduced-diameter portions (64) of the reinforcing tube portion (60), and connecting the reinforcing tube portion (60) and the reinforcing dome portions (50); and (d) a step of forming an outer spiral layer (70) by spirally winding a resin-impregnated fiber on an outer surface of the composite body (40), thereby forming the reinforcing layer (30) including the reinforcing tube portion (60), the reinforcing dome portions (50) and the outer spiral layer (70) characterized in that step (b) (i) comprises a step of forming a thin-walled portion whose thickness is smaller than that of other portions of each of the reinforcing dome portions (50) at the other end of each of the reinforcing dome portions (50) including the opening end (51), the step (i) is a step of forming the thin-walled portion by reducing an amount of resin at the other end of each of the reinforcing dome portions (50), step (b) includes a first step of winding the resin-impregnated fiber onto a mandrel (56), and a second step of curing the resin of the resin-impregnated fiber wound on the mandrel (56); and the step (i) is a step of performing curing of the resin in the second step in a state where a rubber band (58) is wound on an outer side of the resin-impregnated fiber at a portion serving as the other end of each of the reinforcing dome portions (50).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a method for producing a high-pressure tank according to the preamble of claim 1. 2. Description of the related art

[0002] Japanese patent application JP 2012-149739 A describes a method for manufacturing a high-pressure tank, which includes a step of forming a reinforcing layer by winding resin-impregnated fibers on an outer surface of a liner by filament winding.

[0003] A method for producing a high-pressure tank according to the preamble of claim 1 is known from DE 10 2020 135 050 A1 and DE 10 2020 126 412 A1. Regarding the prior art, reference is also made to DE 10 2016 222 674 A1, EP 2 000 288 A1, and CA 3 011 556 A1. SUMMARY OF THE INVENTION

[0004] As a new manufacturing method to replace the conventional method, the present inventor has devised a method in which a tubular portion of a reinforcement layer and dome portions are separately formed, then bonded into a composite body, and an outer spiral layer is formed on the outer surface of the composite body to form a reinforcement layer. However, the present inventor has found that this new manufacturing method is problematic in that a considerable gap exists between the tubular portion of the composite body and the outer spiral layer, and the strength of the high-pressure tank decreases due to this gap.

[0005] The present invention can be realized according to the following aspect.

[0006] According to one aspect of the present invention, a method for manufacturing a high-pressure tank is provided, which comprises a liner having gas-barrier properties and a reinforcing layer arranged around the liner. The method comprises (a) a step of forming a reinforcing tube portion made of fiber-reinforced resin, the reinforcing tube portion having a straight tube portion and reduced-diameter portions arranged at respective ends of the straight tube portion, the outer diameter of which decreases toward end portions of the reinforcing tube portion; (b) a step of forming reinforcing dome portions made of fiber-reinforced resin and shaped such that an outer diameter of each of the reinforcing dome portions increases from one end to an opening end at another end;(c) a step of forming a composite body by arranging the reinforcing dome portions at respective ends of the reinforcing tube portion such that the opening end of each of the reinforcing dome portions is positioned on an outer surface of a corresponding one of the reduced-diameter portions of the reinforcing tube portion, and bonding the reinforcing tube portion and the reinforcing dome portions; and (d) a step of forming an outer spiral layer by spirally winding a resin-impregnated fiber onto an outer surface of the composite body, thereby forming the reinforcing layer including the reinforcing tube portion, the reinforcing dome portions, and the outer spiral layer. According to this method, the opening ends of the reinforcing dome portions are arranged so thatthat they are positioned on the outer surfaces of the reduced-diameter portions of the reinforcing tube portion, and accordingly, the possibility of a large gap being formed between the reinforcing tube portion and the outer spiral layer can be reduced compared to arranging the opening ends of the reinforcing dome portions so that they are positioned on the outer surface of the straight tube portion of the reinforcing tube portion, and an excessive decrease in the strength of the high-pressure tank can be suppressed. Step (b) (i) includes a step of forming a thin-walled portion whose thickness is smaller than that of other portions of each of the reinforcing dome portions at the other end of each of the reinforcing dome portions, including the opening end. This can further reduce the gap between the reinforcing tube portion and the outer spiral layer.by forming the thin-walled portions at the end portions of the reinforcing dome portions. Step (i) is a step of forming the thin-walled portion by reducing a resin amount at the other end of each of the reinforcing dome portions. Thus, the thin-walled portions can be formed by reducing the resin amount at the end portions of the reinforcing dome portions. Step (b) includes a first step of winding the resin-impregnated fiber onto a mandrel and a second step of curing the resin of the resin-impregnated fiber wound onto the mandrel. Step (i) is a step of performing the resin curing in the second step in a state where a rubber band is wound on an outer side of the resin-impregnated fiber at a portion.which serves as the other end of each of the reinforcing dome portions. According to the method of the present invention, the thin-walled portions can be formed by reducing the amount of resin at the end portions of the reinforcing dome portions by curing the resin in a state where the rubber band is wound on the outside of the resin-impregnated fiber.

[0007] In the above-mentioned method, in step (b), the reinforcing dome portions may be formed such that a maximum outer diameter of each of the reinforcing dome portions is equal to or smaller than a maximum outer diameter of the reinforcing tube portion. According to this method, the maximum outer diameter of the reinforcing dome portion is equal to or smaller than the maximum outer diameter of the reinforcing tube portion, and accordingly, the possibility of a large gap being formed between the reinforcing tube portion and the outer spiral layer can be further reduced.

[0008] In the above-mentioned method, step (c) may include a step of applying resin to a portion that is a gap formed in step (d) below the outer spiral layer at a boundary between the reinforcing tube portion and each of the reinforcing dome portions. According to this method, resin is applied in advance to the portion that forms a gap in step (d), and accordingly, the gap can be further reduced.

[0009] It should be noted that the present invention can be implemented in various forms, and for example, can be implemented in the form of a method for producing a reinforcing layer of a high-pressure tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 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 is a sectional view showing a configuration of a high-pressure tank according to an embodiment; Fig. 2 is a sectional view showing a composite body of a reinforcing pipe portion and a reinforcing dome portion according to the embodiment; Fig. 3 is a sectional view showing a configuration of the reinforcing dome portion; Fig. 4 is a sectional view showing a composite body of a reinforcing pipe portion and a reinforcing dome portion according to a reference example; Fig. 5 is a flowchart showing a manufacturing process for the high-pressure tank; Fig. 6 is an explanatory diagram showing an example of a forming method of the reinforcing pipe portion; Fig. 7 is an explanatory diagram showing an example of a molding method of the reinforcing dome portion; Fig. 8 is an explanatory diagram showing an example of a method for reducing resin at an end portion of the reinforcing dome portion; Fig. 9 is an explanatory view showing another example of a method for reducing resin at the end portion of the reinforcing dome portion; and Fig. 10 is an explanatory view showing a method of forming an outer spiral layer. DETAILED DESCRIPTION OF EMBODIMENTS

[0011] Fig. 1 is a sectional view showing a configuration of a high-pressure tank 100 according to an embodiment. The high-pressure tank 100 is a storage container for storing a gas, such as hydrogen gas or the like, and is used for storing hydrogen to be supplied to, for example, a fuel cell for a vehicle or a stationary fuel cell. Generally, high-pressure tanks are tanks that store gas at a pressure of 200 kPa or higher in gauge pressure at 20°C. High-pressure tanks used for fuel cells typically store hydrogen at a pressure of 30 MPa or higher in gauge pressure at 20°C.

[0012] The high-pressure tank 100 is provided with a liner 20 having gas barrier properties, a reinforcement layer 30 arranged around the liner 20, and two necks 81, 82 arranged at respective end portions of the high-pressure tank 100. A first neck 81 has a communication opening 81h for communication between the space inside the liner 20 and the outside. A communication device with a valve is provided in this communication opening 81h. A second neck 82 has no communication opening communicating with the outside, but may be provided with a communication opening. Alternatively, the second neck 82 may be omitted.

[0013] The liner 20 is configured from a resin with gas barrier properties to suppress the transmission of gas to the outside. Examples of resins that can be used to form the liner 20 include polyamide, polyethylene, ethylene-vinyl alcohol copolymer resin (EVOH), polyester, and similar thermoplastic resins, as well as epoxy and similar thermosetting resins.

[0014] The reinforcement layer 30 is a fiber-reinforced resin layer that reinforces the liner 20 and includes a composite body 40 with reinforcement dome portions 50 and a reinforcement tube portion 60, as well as an outer spiral layer 70. The reinforcement layer 30 may also be referred to as a "reinforcement member." The reinforcement dome portions 50 have a so-called dome shape. More specifically, the reinforcement dome portions 50 have a shape in which the outer diameter gradually increases from one end to an opening end 51 at the other end. The opening ends 51 are, of the two ends of the reinforcement dome portions 50, the end portions located closer to the center of the high-pressure tank 100 in the axial direction of the high-pressure tank 100. The ends of the reinforcing dome sections 50 on the sides opposite the opening ends 51 are in contact with the necks 81, 82, respectively. Although the reinforcing dome sections 50 in the Fig. 1 have shapes obtained by cutting away part of a substantially spherical shape that is hollow, various other shapes may also be used. The reinforcing tube portion 60 has a straight tube portion 62 and reduced-diameter portions 64 provided at the respective ends of the straight tube portion 62. The reduced-diameter portions 64 are shaped so that the outer diameter decreases toward the end portions of the reinforcing tube portion 60. Note that the inner diameter of the straight tube portion 62 and the inner diameter of the reduced-diameter portions 64 are preferably the same. The method for manufacturing the reinforcing dome portions 50 and the reinforcing tube portion 60 will be described later. The reinforcing dome portions 50 are arranged at the respective ends of the reinforcing tube portion 60.The reinforcing dome portions 50 are arranged so that their inner surfaces come into contact with the outer surface of the reinforcing tube portion 60. Furthermore, in the present embodiment, the reinforcing dome portions 50 are arranged so that the opening ends 51 of the reinforcing dome portions 50 are located on the outer surfaces of the reduced-diameter portions 64 of the reinforcing tube portion 60. The outer spiral layer 70 is a layer formed by spirally winding resin-impregnated fibers on the outer surface of the composite body 40 including the reinforcing dome portions 50 and the reinforcing tube portion 60. The main function of the outer spiral layer 70 is to prevent the reinforcing dome portions 50 from detaching from the reinforcing tube portion 60 when the internal pressure of the high-pressure tank 100 is increased.The hatching of the outer spiral layer 70 and the liner 20 is shown in . Fig. 1 omitted for simplicity.

[0015] Examples of resins that can be used to form the reinforcing layer 30 include thermosetting resins such as phenolic resins, melamine resins, urea-formaldehyde resins, epoxy resins, and so on. In particular, epoxy resins are preferred from the viewpoint of mechanical strength, etc. Examples of fibers that can be used to form the reinforcing layer 30 include glass fibers, aramid fibers, boron fibers, and carbon fibers. In particular, carbon fibers are preferred from the viewpoint of lightness, mechanical strength, and so on.

[0016] Fig. Fig. 2 is a sectional view showing the composite body 40 according to the present embodiment. For the sake of simplicity, Fig. 2, only the left half of the composite body 40 is shown. The composite body 40 includes the reinforcing tube section 60 and the reinforcing dome sections 50, each arranged at one of its ends. In the present embodiment, the composite body 40 further includes the necks 81, 82 connected to the reinforcing dome sections 50.

[0017] The reinforcing dome portions 50 are arranged such that the opening ends 51 of the reinforcing dome portions 50 are positioned on the outer surfaces of the reduced-diameter portions 64. Adopting such an arrangement makes it possible to reduce the possibility of a large gap forming between the reinforcing pipe portion 60 and the outer spiral layer 70, compared to arranging the opening ends 51 of the reinforcing dome portions 50 such that they are positioned on the outer surface of the straight pipe portion 62, and to suppress an excessive decrease in the strength of the high-pressure tank 100.

[0018] Another feature of the reinforcing dome portions 50 in the present embodiment is that, with respect to each reinforcing dome portion 50, a maximum outer diameter D50max of the reinforcing dome portion 50 is equal to or smaller than a maximum outer diameter D60max of the reinforcing tube portion 60. The maximum outer diameter D50max of the reinforcing dome portion 50 is the outer diameter of the reinforcing dome portion 50 at the end portion having the opening end 51. By employing this feature, the possibility of a large gap forming between the reinforcing tube portion 60 and the outer spiral layer 70 can be further reduced. However, it should be noted that the maximum outer diameter D50max of the reinforcing dome portion 50 may exceed the maximum outer diameter D60max of the reinforcing tube portion 60.

[0019] Furthermore, in the present embodiment, a resin-filled portion 32 is formed by coating a gap portion formed below the outer spiral layer 70 at a boundary BR between the reinforcing tube portion 60 and the reinforcing dome portion 50 with resin. The resin forming the resin-filled portion 32 is preferably the same as the resin used to form the reinforcing layer 30. By forming the resin-filled portion 32, the gap between the reinforcing tube portion 60 and the outer spiral layer 70 can be further reduced.

[0020] Fig. 3 is a sectional view showing the configuration of the reinforcement dome portion 50. The reinforcement dome portion 50 includes a dome main unit portion 52 and a thin-walled portion 54. The thin-walled portion 54 is formed at the end portion of the reinforcement dome portion 50 having the opening end 51 and is a portion whose thickness is smaller than that of the dome main unit portion 52, which is a portion other than the thin-walled portion 54. The thin-walled portion 54 can be formed as a portion in which the amount of resin or the amount of fiber per unit surface area is smaller than that of the dome main unit portion 52. By forming the thin-walled portion 54 at the end portion of the reinforcement dome portion 50, the gap between the reinforcement tube portion 60 and the outer spiral layer 70 can be further reduced.Note that in the present embodiment, the thin-walled portion 54 has a tapered shape in which the thickness gradually decreases as it approaches the axial center of the high-pressure tank 100. This configuration makes it possible to further reduce the gap between the reinforcing tube portion 60 and the outer spiral layer 70.

[0021] Fig. 4 is a sectional view showing a composite body 41 of the reinforcement tube portion 60 and the reinforcement dome portion 50 according to a reference example. In this composite body 41, the reinforcement dome portion 50 is arranged so that the opening end 51 of the reinforcement dome portion 50 is positioned on the outer surface of the straight tube portion 62 of the reinforcement tube portion 60. As a result, the maximum outer diameter D50max of the reinforcement dome portion 50 is larger than the maximum outer diameter D60max of the reinforcement tube portion 60. In this reference example, there is a possibility that a considerable gap GP is formed between the reinforcement tube portion 60 and the outer spiral layer 70.Accordingly, the reinforcing dome portion 50 is preferably arranged such that the opening end 51 of the reinforcing dome portion 50 is positioned on the outer surface of the reduced diameter portion 64 of the reinforcing tube portion 60, as described with reference to FIG. Fig. 2. Furthermore, the maximum outer diameter D50max of the reinforcing dome portion 50 is particularly preferably equal to or smaller than the maximum outer diameter D60max of the reinforcing tube portion 60.

[0022] Fig. 5 is a flowchart showing a method for manufacturing the high-pressure tank 100. Examples of methods used in the following steps will be described later. In step S10, the reinforcement tube portion 60 is formed. In step S20, the reinforcement dome portions 50 are formed. In step S30, the necks 81, 82 are connected to the reinforcement dome portions 50. In step S40, the two reinforcement dome portions 50 are connected to the respective end portions of the reinforcement tube portion 60 to form the composite body 40. In step S45, resin for filling gaps is applied to the boundaries between the reinforcement dome portions 50 and the reinforcement tube portion 60, thereby forming the resin-filled portions 32 described with reference to FIG. Fig. 2. Step S45 may be considered part of step S40. Alternatively, step S45 may be omitted. In step S50, the outer spiral layer 70 is formed on the outer surface of the composite body 40. In step S60, the uncured resin of the reinforcement layer 30 is cured. In step S70, the liner 20 is formed on the inside of the reinforcement layer 30.

[0023] Fig. 6 is an explanatory diagram showing an example of a method for forming the reinforcing pipe portion 60 in step S10 of Fig. 5 shows. The reinforcing tube section 60 can be formed by filament winding by winding a fiber bundle FB onto a substantially cylindrical mandrel 66. During filament winding, the fiber bundle FB is wound onto the mandrel 66 by moving a fiber bundle guide 210 while the mandrel 66 rotates. The example in Fig. Figure 6 shows how the fiber bundle FB is wound by ring winding, but spiral winding can also be used. For the filament winding (FW) method, one of the wet FW methods and dry FW methods described below can be used.

[0024] In general, the following processes are typical methods for forming fiber-reinforced resin objects. Wet FW process

[0025] The wet FW process is a process in which the fiber bundle FB is impregnated with liquefied resin whose viscosity has been reduced immediately before winding the fiber bundle FB and the resin-impregnated fiber bundle is wound onto a mandrel. Dry FW process

[0026] The dry FW process is a process in which a tow prepreg, which is made by impregnating a fiber bundle with resin and then drying it in advance, is prepared and the tow prepreg is wound on a mandrel. Resin Transfer Molding (RTM)

[0027] The RTM process is a molding process in which the fibers are placed into a pair of male and female molds, the mold is closed, and then resin is poured in from a resin inlet, impregnating the fibers. Centrifugal winding (CW process)

[0028] The CW process is a method in which a cylindrical element is formed by applying a fiber web to the inside of a rotating cylindrical mold. The fiber web can be either a fiber web that has been previously impregnated with resin or a fiber web that has not been impregnated with resin. In the latter case, the resin is poured into the mold after the fiber web has been cylindrically wound, thus impregnating the fiber web with the resin.

[0029] Although in the example described above in Fig. 6, fiber winding is used to form the reinforcement tube portion 60, the reinforcement tube portion 60 may also be formed using other methods, such as RTM or the like. Curing of the resin of the reinforcement tube portion 60 may be performed in step S10 or in step S60.

[0030] When curing the resin of the reinforcing tube portion 60 in step S10, main curing may be performed, in which curing is fully performed until the viscosity of the resin is in a stable state at a target value or higher. Alternatively, pre-curing may be performed, in which the main curing is not achieved. Generally, uncured thermosetting resin initially has a lower viscosity upon heating, and as heating is continued thereafter, the viscosity increases. If heating is continued for a sufficient time, the viscosity of the resin is in a stable state at its target value or higher.Assuming such a process, the processing in which curing continues even when the viscosity drops and then increases again and returns to the initial viscosity, and curing is stopped at any point before reaching the end point of the main curing, is referred to as "pre-curing." By performing the pre-curing in step S10 and then performing the main curing in step S60 described later, the reinforcing tube portion 60 can be more firmly bonded to the reinforcing dome portions 50 and the outer spiral layer 70.

[0031] Note that to facilitate the separation of the mandrel 66 and the reinforcement tube portion 60, the mandrel 66 may be divisible. If the separation of the mandrel 66 and the reinforcement tube portion 60 is difficult even though the mandrel 66 is divisible, two split members in which the entire reinforcement tube portion 60 is split into two parts substantially in the middle may be individually formed, and the two split members may be joined together to form the reinforcement tube portion 60.

[0032] Fig. Fig. 7 is an explanatory diagram showing an example of a method for forming the reinforcing dome portions 50 in step S20 in Fig. 5. The reinforcing dome sections 50 can be formed by winding the fiber bundle FB onto a mandrel 56 using filament winding. The mandrel 56 preferably has the outer shape of two assembled reinforcing dome sections 50. During filament winding, the fiber bundle FB is wound onto the mandrel 56 by moving the fiber bundle guide 210 while the mandrel 56 rotates. In the example in Fig. 7, the fiber bundle FB is wound by spiral winding. Both the wet FW method described above and the dry FW method can be used for winding the fiber bundle. After the winding of the fiber bundle FB is completed, the two reinforcing dome parts 50 can be obtained by cutting along a cutting line CL. It should be noted that the reinforcing dome sections 50 can also be formed using other methods, such as RTM.

[0033] Fig. Fig. 8 is an explanatory diagram showing an example of a method for reducing the amount of resin at the end portion of each reinforcing dome portion 50. The thin-walled portion 54 is preferably formed at the end portion including the opening end 51 of the reinforcing dome portion 50, as described with reference to Fig. Fig. 3. In this case, uncured resin at the portions to become the thin-walled portion 54 can be removed by suction with a suction device 220 to form the thin-walled portion 54. In this way, the thin-walled portion 54 can be formed by reducing the amount of resin at the end portions of the reinforcing dome portion 50. Note that, for the resin removal tools, rollers, doctor blades, or other such removal tools may be used instead of the suction device 220. When reducing the amount of resin from the portions to become the thin-walled portion 54, the wet FW method described above is preferably used. Alternatively, in the dry FW method described above, the tow prepreg wound on the mandrel 56 may be heated, and the removal of the uncured resin may be performed in a state where the viscosity of the resin is lowered.

[0034] Fig. 9 is an explanatory diagram showing the method of reducing the resin amount at the end portion of the reinforcing dome portion 50 according to the present invention. In this method, after a first step of winding the resin-impregnated fiber onto the mandrel 56, a second step of curing the resin of the resin-impregnated fiber wound onto the mandrel 56 is performed. In this second step, the resin curing is performed in a state where a rubber band 58 is wound onto the outside of the resin-impregnated fiber at the portion to become the thin-walled portion 54 at the end portion of the reinforcing dome portion 50, as shown in Fig. 9. At this time, the rubber band 58 is wound under tension. With this process, the resin under the rubber band 58 is squeezed out, and accordingly, the amount of resin at the end portion of the reinforcing dome portion 50 can be reduced, and the thin-walled portion 54 can be formed. In this process, either the wet FW method described above or the dry FW method can be used. In addition, the main curing for curing the resin can be performed in the second step, or pre-curing can be performed.

[0035] It should also be noted that the curing of the resin of the reinforcing dome portions 50 may be performed in step S20 or in step S60. When the curing of the reinforcing dome portions 50 in step S20 is performed in Fig. 5, the curing can be carried out sequentially from the middle section of the Fig. 7 toward both ends. Accordingly, the amount of resin at the end portions of the two reinforcing dome portions 50 is less than at the other portions, and the thin-walled portions 54 can be formed without removing the resin, as shown in FIGS. Fig. 8 and Fig. 9. For curing the resin at this time, either primary curing or precuring may be performed. Performing precuring in step S20 and performing primary curing in step S60 described later enables a stronger bond between the reinforcing dome portions 50, the reinforcing tube portion 60, and the outer spiral layer 70.

[0036] In step S30 in Fig. 5, the reinforcing dome sections 50 and the necks 81, 82 are connected. In step S40, the reinforcing tube section 60 is further connected to the composite bodies formed in step S30, whereby the Fig. 2 is formed. The joining in steps S30 and S40 can be carried out, for example, with an adhesion promoter or pressure-sensitive adhesive. The composite body 40 shown with reference to Fig. 2 is in step S45 in Fig. 5 formed.

[0037] Fig. Fig. 10 is an explanatory diagram showing a method of forming the outer spiral layer 70 in step S50 in Fig. 5 shows. The outer spiral layer 70 can be formed by winding the fiber bundle FB onto the outer surface of the composite body 40 by filament winding. In filament winding, the fiber bundle FB is wound onto the composite body 40 by moving the fiber bundle guide 210 while rotating the bonded body 40 around a central axis AX. Either a wet FW method or a dry FW method can be used for filament winding. As described above, the main function of the outer spiral layer 70 is to prevent the reinforcing dome portions 50 from detaching from the reinforcing tube portion 60 when the internal pressure of the high-pressure tank 100 is increased. To achieve this function, a winding angle α of the fiber bundle FB is preferably not greater than 45 degrees. The winding angle α is the angle of the fiber bundle FB with respect to the central axis AX of the composite body 40.

[0038] In step S60 in Fig. 5, the uncured resin of the reinforcement layer 30 is cured. This curing is the one with reference to Fig. 6 described main curing. In step S70, after curing, the lining 20 is formed on the inside of the reinforcement layer 30. The formation of the lining in step S70 can be carried out, for example, by introducing a liquid lining material into the necked reinforcement layer 30 and curing the lining material while rotating the reinforcement layer 30. When the formation of the lining 20 ends, the Fig. 1 is thus completed.

[0039] It should be noted that the lining 20 is formed in a step other than step S70 in Fig.5 can be formed. For example, the liner 20 may be formed separately from the reinforcing dome portions 50 and the reinforcing tube portion 60, and the liner 20 and the two reinforcing dome portions 50 and necks 81, 82 are then joined in step S30 described above. In this case, the formation of the liner 20 can be performed, for example, by injection molding. At this time, two divided members in which the entire liner 20 is divided into two parts substantially in the middle can be molded separately by injection molding, and the two divided parts removed from the injection molds can be joined to form the liner 20. In this molding, the necks 81, 82 can be inserted into the injection molds, and the necks 81, 82 and the divided members of the liner 20 can be joined by insert molding.Alternatively, the necks 81, 82 may be connected to the two respective split elements of the liner 20 after the split elements have been removed from the molds.

[0040] As described above, in the present embodiment, the opening ends 51 of the reinforcing dome portions 50 are arranged to be placed on the outer surfaces of the reduced-diameter portions 64 of the reinforcing pipe portion 60. As a result, the possibility of a large gap forming between the reinforcing pipe portion 60 and the outer spiral layer 70 can be reduced compared to the arrangement of the opening ends 51 of the reinforcing dome portions 50 on the outer surface of the straight pipe portion 62 of the reinforcing pipe portion 60, and an excessive decrease in the strength of the high-pressure tank 100 can be suppressed.

Claims

[1] A method of manufacturing a high-pressure tank (100) having a lining (20) having gas barrier properties and a reinforcement layer (30) disposed around the lining (20), the method comprising: (a) a step of forming a reinforcing tube portion (60) made of fiber-reinforced resin, the reinforcing tube portion (60) comprising a straight tube portion (62) and reduced-diameter portions (64) arranged at respective ends of the straight tube portion (62) and whose outer diameter decreases toward end portions of the reinforcing tube portion (60); (b) a step of forming reinforcing dome portions (50) made of fiber-reinforced resin and shaped such that an outer diameter of each of the reinforcing dome portions (50) increases from one end to an opening end (51) at another end; (c) a step of forming a composite body (40) by arranging the reinforcing dome portions (50) at respective ends of the reinforcing tube portion (60) such that the opening end (51) of each of the reinforcing dome portions (50) is positioned on an outer surface of a corresponding one of the reduced diameter portions (64) of the reinforcing tube portion (60), and connecting the reinforcing tube portion (60) and the reinforcing dome portions (50); and (d) a step of forming an outer spiral layer (70) by spirally winding a resin-impregnated fiber on an outer surface of the composite body (40), thereby forming the reinforcing layer (30) including the reinforcing tube portion (60), the reinforcing dome portions (50) and the outer spiral layer (70) characterized by , that the step (b) (i) comprises a step of forming a thin-walled portion whose thickness is smaller than that of other portions of each of the reinforcing dome portions (50) at the other end of each of the reinforcing dome portions (50) including the opening end (51), the step (i) is a step of forming the thin-walled portion by reducing an amount of resin at the other end of each of the reinforcing dome portions (50), step (b) includes a first step of winding the resin-impregnated fiber onto a mandrel (56), and a second step of curing the resin of the resin-impregnated fiber wound on the mandrel (56); and the step (i) is a step of performing curing of the resin in the second step in a state where a rubber band (58) is wound on an outer side of the resin-impregnated fiber at a portion serving as the other end of each of the reinforcing dome portions (50). [2] The method according to claim 1, wherein in step (b), the reinforcing dome portions (50) are formed such that a maximum outer diameter of each of the reinforcing dome portions (50) is equal to or smaller than a maximum outer diameter of the reinforcing tube portion (60). [3] The method according to claim 1 or 2, wherein step (c) comprises a step of applying resin to a portion which is a gap formed in step (d) below the outer spiral layer (70) at a boundary between the reinforcing tube portion (60) and each of the reinforcing dome portions (50).

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