Manufacturing method of high pressure tank

Abstract

To provide a method for manufacturing a high-pressure tank in which a matrix resin is impregnated to acquire stable strength while suppressing looseness of a reinforcement fiber that is wound around a boundary part.SOLUTION: A method for manufacturing a high-pressure tank includes the steps of: preparing a liner that includes a liner body 11A continuing to a barrel part 14 in which a storage space S is formed and including a neck part 15 extending toward an opening 13 and a metal reinforcement body 40 disposed in the neck part 15, as a liner 11; forming a reinforcement fiber base material 12A at an outer peripheral surface 11a of the liner 11 by winding a reinforcement fiber 12a around the outer peripheral surface of the liner 11; and disposing the liner 11 around which the reinforcement fiber base material 12A is wound in a shaping mold 93 and injecting a matrix resin 11B between the shaping mold 93 and the liner 11 while applying internal pressure to the storage space S to impregnate the matrix resin 11B into the reinforcement fiber base material 12A and form a reinforcement layer 12.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a high-pressure tank. [Background technology]

[0002] For example, high-pressure tanks for storing fuel gas are used in natural gas vehicles or fuel cell vehicles, etc. This type of high-pressure tank includes a liner that contains a fluid, which is a high-pressure gas, and a reinforcing layer made of fiber-reinforced resin that covers the outer periphery of the liner.

[0003] When manufacturing a high-pressure tank, first, a resin liner is prepared. The liner has a body portion in which a storage space for storing high-pressure gas is formed, and a neck portion formed continuously with the end portion of the body portion. A reinforcing layer made of fiber-reinforced resin is molded on the outer peripheral surfaces of the body portion and the neck portion of the prepared liner (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-60265 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, for example, when forming the reinforcing layer shown in Patent Document 1, it is assumed that a reinforcing fiber substrate is formed on the outer peripheral surface of the liner by winding reinforcing fibers around the outer peripheral surface of the liner, and then the reinforcing fiber substrate is impregnated with a matrix resin.

[0006] In this case, the liner wrapped with the reinforcing fiber substrate is placed in a mold, and matrix resin is injected between the mold and the liner while applying internal pressure to the storage space of the liner. At this time, a hoop stress acts on the body of the liner so as to expand in the circumferential direction of the body, so that the reinforcing fiber wound around the body of the liner is unlikely to become misaligned.

[0007] However, because the boundary between the body and the neck has a concave shape, a hoop stress acts on the boundary to shrink it in the circumferential direction due to the shape. This hoop stress causes the diameter of the boundary to shrink slightly, and the reinforcing fibers wound around the boundary are likely to slacken. In this state, even if the matrix resin is impregnated into the reinforcing fibers (reinforcing fiber substrate), it is difficult to ensure the mechanical strength of the boundary.

[0008] The present invention has been made in consideration of these points, and provides a method for manufacturing a high-pressure tank that can obtain stable strength by impregnating the matrix resin while suppressing slack in the reinforcing fibers wrapped around the boundaries. [Means for solving the problem]

[0009] In view of the above-mentioned problems, a manufacturing method of a high-pressure tank according to the present invention is a manufacturing method of a high-pressure tank having a resin liner in which a storage space for storing a fluid is formed and in which an opening is formed on at least one end side, and a reinforcing layer made of fiber reinforced resin covering an outer peripheral surface of the liner, the manufacturing method including the steps of: preparing a liner as the liner, the liner including a liner main body having a neck portion that is continuous with a body portion in which the storage space is formed and that extends toward the opening, and a metal reinforcing body that is arranged at least at a boundary portion between the neck portion and the body portion; winding reinforcing fibers around the outer peripheral surface of the liner to form a reinforcing fiber substrate on the outer peripheral surface of the liner; and placing the liner with the reinforcing fiber substrate wound thereon in a molding die, and injecting a matrix resin between the molding die and the liner while applying internal pressure to the storage space, thereby impregnating the reinforcing fiber substrate with the matrix resin and forming the reinforcing layer.

[0010] According to the present invention, when the reinforcing layer is formed, if internal pressure is applied to the storage space in which the liner is formed, the boundary portion between the neck portion and the body portion of the liner has a concave shape, so that a hoop stress acts on this boundary portion so as to shrink it in the circumferential direction. However, in the present invention, a metal reinforcing body is arranged at least in the boundary portion, so that the circumferential deformation of the boundary portion can be suppressed. This allows the matrix resin to be impregnated into the reinforcing fiber base material while suppressing slack in the reinforcing fiber wound around the boundary portion. As a result, a high-pressure tank with stable strength can be obtained.

[0011] In a more preferred embodiment, in the step of preparing the liner, the reinforcing member is integrally molded with the liner body.

[0012] According to this aspect, since the reinforcing member is integrally molded with the liner body, the liner body is restrained by the reinforcing member, and therefore, even if a hoop stress acts on the boundary portion so as to shrink the boundary portion in the circumferential direction, the shape of the boundary portion can be maintained.

[0013] In a more preferred embodiment, the high-pressure tank is fitted with a connecting member covering the opening, the connecting member has an insertion portion formed to be inserted into the opening, a sealing member that contacts the inner surface of the liner is attached to the insertion portion, and the reinforcing body extends to a position opposite the sealing member.

[0014] According to this aspect, the reinforcing body is extended to a position opposite the sealing member, so that the reinforcing body can ensure the sealing performance of the sealing member even when fluid is filled and discharged into the storage space when the high-pressure tank is in use. Effect of the Invention

[0015] According to the present invention, the matrix resin can be impregnated into the reinforcing fiber base material while reducing slack in the reinforcing fiber wound around the boundary portion, thereby obtaining stable strength. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view showing a structure of a tank unit including a high-pressure tank manufactured by a manufacturing method according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of the high-pressure tank taken along line AA in FIG. 1. [Diagram 3] 3 is an enlarged cross-sectional view of a main portion of the high-pressure tank on the bracket side shown in FIG. 2. [Figure 4] 4 is a cross-sectional view illustrating a step of preparing a liner in the manufacturing method of the high-pressure tank shown in FIG. 3. [Diagram 5] 2 is a view for explaining a step of forming a reinforcing fiber substrate in the method for manufacturing the high-pressure tank shown in FIG. 1. FIG. [Figure 6] 4 is a view for explaining a state in which a reinforcing fiber base material has been formed in the manufacturing method of the high-pressure tank shown in FIG. 3. FIG. [Figure 7] 4 is a cross-sectional view illustrating a step of forming a reinforcing layer in a manufacturing method of the high-pressure tank shown in FIG. 1. [Figure 8] 10A to 10C are diagrams for explaining the hoop stress acting when forming a reinforcing layer in the manufacturing method for the high-pressure tank according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1.About High Pressure Tank 10 First, an embodiment of a tank unit 1 including a high-pressure tank 10 will be described below with reference to Figures 1 to 3. As shown in Figures 1 and 2, the tank unit 1 according to this embodiment includes a plurality of high-pressure tanks 10 and a pair of connecting members 30, 30 connected to both ends of the high-pressure tanks 10.

[0018] The high-pressure tank 10 is a tank that is loaded with high-pressure hydrogen gas and is installed in a fuel cell vehicle. The gas that can be filled into the high-pressure tank 10 is not limited to high-pressure hydrogen gas, but may be various compressed gases such as CNG (compressed natural gas), various liquefied gases such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas), or other gases (fluids), and may be temporarily filled with a fluid such as a liquid for pressure testing.

[0019] The high-pressure tank 10 includes a liner 11 having a storage space S for storing hydrogen gas and openings 13 formed on both sides, and a reinforcing layer 12 laminated on the liner 11 so as to cover the outer peripheral surface 11a of the liner 11. The liner 11 includes a liner body 11A made of a resin material having gas barrier properties, and a metallic reinforcing body 40. The reinforcing layer 12 is made of fiber-reinforced resin.

[0020] The liner body 11A includes a body portion 14 in which the above-mentioned storage space S is formed, and a pair of neck portions 15, 15 that are continuous with the end portion of the body portion 14 and have an opening 13. In this embodiment, the neck portions 15, 15 are formed on both sides of the liner 11, but the high-pressure tank 10 may have a bottle-like structure in which the neck portion 15 is formed on only one side.

[0021] In this embodiment, the body portion 14 includes a cylindrical main body 14a, which is an example of a cylindrical shape, and a shoulder portion 14b whose inner and outer diameters decrease from the main body 14a toward the end of the body portion 14. The shoulder portion 14b is a cylindrical portion having a truncated cone shape, and a neck portion 15 is formed so as to be continuous with the shoulder portion 14b. The neck portion 15 is a cylindrical portion and extends in a direction along the axis CL of the high-pressure tank 10 toward the opening portion 13. Therefore, a boundary portion 16 between the body portion 14 (shoulder portion 14b) and the neck portion 15 appears to have a concave shape.

[0022] In this embodiment, a metallic reinforcing member 40 is disposed at the boundary portion 16 between the neck portion 15 and the body portion 14. The reinforcing member 40 may extend to a part of the neck portion 15 to ensure sealing performance, which will be described later.

[0023] In this embodiment, an annular base 20 is attached to the outer peripheral surface 12b of the reinforcing layer 12 that covers the neck portion 15. A plurality of protrusions are formed on the inner peripheral surface 22 of the base 20, and the reinforcing layer 12 is formed to bite into the inner peripheral surface 22 (specifically, to bite between the protrusions). This allows the base 20 to be engaged with the reinforcing layer 12. A male thread is formed on the outer peripheral surface 21 of the base 20, and this male thread can be screwed into a female thread on an inner wall surface 34 formed on a connecting member 30 described later.

[0024] In this embodiment, the resin constituting the liner body 11A is preferably a resin with good gas barrier properties. Examples of such resins include thermoplastic resins such as polypropylene resins, nylon resins (e.g., 6-nylon resin or 6,6-nylon resin), polycarbonate resins, acrylic resins, ABS resins, polyamide resins, polyethylene resins, ethylene-vinyl alcohol copolymer resins (EVOH), and polyester resins.

[0025] The reinforcing layer 12 is a reinforcing fiber (reinforced fiber substrate) impregnated with a thermoplastic resin or a thermosetting resin as a matrix resin. In this embodiment, the reinforcing fiber is a fiber bundle. As the reinforcing fiber, glass fiber, aramid fiber, boron fiber, carbon fiber, and other reinforcing fibers can be used, and in particular, carbon fiber is preferably used from the viewpoints of light weight, mechanical strength, and the like. As the matrix resin, a thermosetting resin is preferable, and as the thermosetting resin, a phenol-based resin, a melamine-based resin, a urea-based resin, or an epoxy-based resin is preferable, and from the viewpoint of mechanical strength, and the like, an epoxy-based resin precursor is preferably used. The epoxy-based resin has fluidity in an uncured state, and becomes an epoxy-based resin that forms a tough crosslinked structure after thermal curing.

[0026] The reinforcing layer 12 is formed by winding reinforcing fibers (reinforcing fiber bundles) impregnated with a matrix resin around the outer peripheral surface 11a of the liner 11 by a filament winding method or a sheet winding method. The reinforcing layer 12 may be a helically wound layer in which the fiber bundles are wound so as to be inclined with respect to the axis CL of the high-pressure tank 10, or may be, for example, a layer in which the fiber bundles are woven so as to be inclined with respect to the axis CL of the high-pressure tank 10 (braider winding), or may be a combination of these layers laminated together.

[0027] The pair of connecting members 30, 30 are made of metal such as aluminum or steel, and are composed of a bracket 30A and a manifold 30B. The bracket 30A is a member for integrally restraining the multiple high-pressure tanks 10, 10, ... and attaching them to the vehicle.

[0028] The manifold 30B is a member in which a gas flow path is formed, which introduces hydrogen gas into the storage space S of the high-pressure tank 10 and releases the hydrogen gas from this storage space S. As shown in Fig. 2, the bracket 30A and the manifold 30B differ mainly in whether or not a gas flow path is formed, so the structure of the manifold 30B as the connection member 30 will be described with reference to Fig. 3.

[0029] The manifold 30B is formed so as to cover the opening 13 formed at the end of the high-pressure tank 10 in the direction of the axis CL, and includes an insertion portion 31 and a cap portion 32. The cap portion 32 is screwed onto the nozzle 20 at the outer circumferential surface 21 of the nozzle 20, and is a portion that covers the end face of the high-pressure tank 10. The insertion portion 31 is formed in the center of the cap portion 32.

[0030] The insertion portion 31 is a plug-shaped portion that is inserted into the neck portion 15 from the opening 13 along the inner peripheral surface 15a of the neck portion 15. An annular groove 35 is formed in the outer peripheral surface 31a of the insertion portion 31 along its circumferential direction, and annular seal members 61, 62 that seal the storage space S are disposed in the annular groove 35. Specifically, the seal members 61, 62 are in contact with the inner peripheral surface 11b of the liner 11 (specifically, the inner peripheral surface 15a of the neck portion 15), and abut against the inner peripheral surface 11b in a state of being slightly elastically deformed in the radial direction in order to ensure sealing in the storage space S. The seal members 61, 62 are made of an elastic material such as a resin material or a rubber material having gas barrier properties.

[0031] In this embodiment, the reinforcing body 40 is cylindrical, and the inner peripheral surface 15a of the neck portion 15 is a member that restricts radial deformation. The reinforcing body 40 is disposed at the boundary portion 16 between the neck portion 15 and the body portion 14 of the liner body 11A. The reinforcing body 40 restricts radial deformation of at least the boundary portion 16, and is formed to go around the outer peripheral surface 15d of the neck portion 15. In this embodiment, the reinforcing body 40 is molded integrally with the liner body 11A.

[0032] Furthermore, in this embodiment, the reinforcing body 40 extends to a position facing the sealing members 61, 62 so as to go around the outer circumferential surface 15d of the liner 11. Since the reinforcing body 40 extends to a position facing the sealing members 61, 62, the reinforcing body 40 can ensure the sealing performance of the sealing members 61, 62 even when the storage space S is filled with and discharged with fluid during use of the high-pressure tank 10.

[0033] The material of the reinforcing body 40 is a metal material such as stainless steel or aluminum, and the material is not particularly limited as long as it can limit the deformation of the inner surface 15a of the neck portion 15 that extends radially.

[0034] Here, "radial deformation of the inner surface 15a of the neck portion 15" refers to deformation that occurs when hoop stress is generated in the neck portion 15 due to the pressure of hydrogen gas, and refers to deformation that expands radially in the liner 11 that forms the neck portion 15 (more specifically, the portion of the liner 11 that abuts against the sealing members 61, 62).

[0035] Furthermore, the inner peripheral surface (opposing surface) of the reinforcement body 40 abuts against the outer peripheral surface 15d of the neck portion 15. In this embodiment, the reinforcement body 40 extends from the end face of the high-pressure tank 10 to a part of the shoulder portion 14b of the body portion 14. Of both ends of the reinforcement body 40, the end on the opening 13 side has a shape that expands in the radial direction of the reinforcement body 40, and the end on the body portion 14 side is formed along the shape of the boundary portion 16. This makes it easier for the reinforcement body 40 to engage with the reinforcing layer 12, and makes it possible to prevent the reinforcement body 40 from slipping out in the direction along the axis CL.

[0036] 2. Manufacturing method of high pressure tanks A method for manufacturing the high-pressure tank 10 of this embodiment will be described below with reference to FIGS.

[0037] (Process of preparing liner 11) First, as shown in Fig. 4, a liner 11 including a resin liner body 11A and a metal reinforcing body 40 is prepared. In this embodiment, the reinforcing body 40 is placed in an injection molding machine (not shown), and the liner body 11A is integrally molded together with the reinforcing body 40. When molding the liner body 11A, the liner body 11A may be divided into two divided bodies at a dividing surface that is perpendicular to the axis CL and located at the center of the liner body 11A, and then these divided bodies may be molded and joined to manufacture the liner body 11A. Alternatively, the liner body 11A may be placed at the boundary portion 16 between the neck portion 15 and the body portion 14 after molding.

[0038] (Step of forming reinforcing fiber substrate) As shown in Fig. 5 and Fig. 6, the reinforcing fiber substrate 12A is formed on the outer peripheral surface 11a of the liner 11 by winding the reinforcing fiber 12a on the outer peripheral surface 11a of the liner 11. In this way, the preform 10A is formed. Continuous reinforcing fiber 12a is fed out in sequence from a plurality of bobbins 82, 82 of a braider (braiding machine) 80, and the reinforcing fiber 12a is braided and wound on the outer peripheral surface of one of the neck portions 15 to form the reinforcing fiber substrate 12A from the neck portion 15 on one side of the liner 11 to the body portion 14 and the neck portion 15 on the other side. This method may be repeated to form the reinforcing fiber substrate 12A, or the reinforcing fiber substrate 12A may be formed by combining helical winding and braiding winding, or the reinforcing fiber substrate 12A may be formed by helical winding alone.

[0039] (Step of forming reinforcing layer 12) As described above, the preform 10A (FIGS. 6 and 7) in which the reinforcing fiber substrate 12A is formed in the hollow liner 11 is placed in a molding die 93 (between a lower die 93A and an upper die 93B, also called a cavity). Next, the reinforcing layer 12 is molded using an RTM impregnation technique.

[0040] Specifically, while applying internal pressure with gas to the storage space S of the liner 11 via a gas supply pipe 95 embedded in the molding die 93, matrix resin 11B is injected between the molding die 93 and the liner 11 (specifically, within the cavity), thereby impregnating the reinforcing fiber base material 12A with the matrix resin 11B and forming the reinforcing layer 12.

[0041] Here, when the matrix resin 11B is a thermosetting resin, the impregnated matrix resin may be thermally cured at a heating temperature equal to or higher than the curing start temperature after impregnation with the matrix resin 11B. Alternatively, the molding die 93 may be heated in advance at a heating temperature equal to or higher than the curing start temperature, and the matrix resin may be thermally cured simultaneously with the impregnation. On the other hand, when the matrix resin 11B is a thermoplastic resin, the matrix resin 11B may be impregnated in a state in which the matrix resin 11B is heated to a temperature equal to or higher than the softening point, and then cooled and solidified.

[0042] When the matrix resin 11B is injected between the molding die 93 and the liner 11 (specifically, in the cavity), the matrix resin 11B is injected through a resin injection pipe (also called a resin injection gate) 92 connected to a resin injector 91. At the same time, air is degassed between the molding die 93 and the liner 11 (specifically, in the cavity) through a vacuum degassing pipe 97 connected to a vacuum pump 98.

[0043] Incidentally, when matrix resin 11B is injected between the molding die 93 and the liner 11 while applying internal pressure to the storage space S of the liner 11, the following phenomenon occurs. Specifically, as shown in part A of Fig. 8, a hoop stress T acts on the body portion 14 of the liner 11 so as to expand in the circumferential direction of the body portion 14, so that the reinforcing fibers wound around the body portion 14 of the liner 11 are unlikely to slip.

[0044] However, as shown in part B of Fig. 8, the boundary portion 16 between the body portion 14 and the neck portion 15 has a concave shape, and due to this shape, a hoop stress T acts on the boundary portion 16 so as to shrink it in the circumferential direction. This hoop stress T causes the diameter of the boundary portion 16 to shrink slightly, and the reinforcing fibers 12a of the reinforcing fiber substrate 12A wound around the boundary portion 16 tend to slacken. In particular, when degassing is performed using a vacuum pump 98, this phenomenon becomes even more pronounced. In this state, even if the matrix resin 11B is impregnated into the reinforcing fiber substrate 12A, it is difficult to ensure the mechanical strength of the boundary portion 16.

[0045] In this embodiment, a metal reinforcing member 40 is disposed at the boundary portion 16 between the neck portion 15 and the body portion 14 of the liner 11, thereby suppressing circumferential deformation of the boundary portion 16. This allows the matrix resin 11B to be impregnated into the reinforcing fiber base material 12A while suppressing slack in the reinforcing fibers wound around the boundary portion 16. As a result, a high-pressure tank 10 with stable strength can be obtained.

[0046] In particular, in this embodiment, the reinforcing body 40 is integrally molded with the liner body 11A, so that the liner body 11A is restrained by the reinforcing body 40. Therefore, even if a hoop stress T acts on the boundary portion 16 so as to shrink it in the circumferential direction, the shape of the boundary portion 16 can be maintained.

[0047] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as described in the claims. [Explanation of symbols]

[0048] 10: high pressure tank, 11: liner, 11A: liner body, 11B: matrix resin, 12: reinforcing layer, 12A: reinforced fiber base material, 14: body portion, 15: neck portion, 16: boundary portion, 30: connecting member, 31: insertion portion, 40: reinforcing body, 93: molding die, S: storage space

Claims

1. A method for manufacturing a high-pressure tank having a resin liner having a storage space for storing a fluid and an opening formed on at least one end side thereof, and a reinforcing layer made of a fiber-reinforced resin covering an outer peripheral surface of the liner, comprising: preparing a liner including a liner body having a neck portion continuous with a body portion in which the storage space is formed and extending toward the opening, and a metal reinforcing member disposed at least at a boundary portion between the neck portion and the body portion; forming a reinforcing fiber substrate on the outer peripheral surface of the liner by winding reinforcing fibers around the outer peripheral surface of the liner; The liner around which the reinforcing fiber substrate is wound is placed in a mold, and while applying internal pressure to the accommodation space, a matrix resin is injected between the mold and the liner to impregnate the reinforcing fiber substrate with the matrix resin, thereby forming the reinforcing layer. A method for manufacturing a high-pressure tank, characterized in that in the process of preparing the liner, the reinforcement body is integrally molded with the liner body, the reinforcement body abuts against the outer peripheral surface of the neck portion so as to circumferentially surround the outer peripheral surface of the neck portion, and of both ends of the reinforcement body, the end on the opening side has a shape that expands radially of the reinforcement body.

2. The high-pressure tank is provided with a connecting member that covers the opening, The connection member has an insertion portion that is inserted into the opening, a seal member that contacts an inner peripheral surface of the liner is attached to the insertion portion, The method for manufacturing a high-pressure tank according to claim 1, wherein the reinforcing member extends to a position facing the sealing member.

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