Can manufacturing method

Abstract

Provided are a method and apparatus for manufacturing a tank capable of impregnating resin in a short time. Fibers (16) are radially overlapped and wound around the outer surface of an inner liner (12) in such a manner that a first fiber layer (braided layer) (17B) on the outer surface of a dome portion (12B) is sparser than a second fiber layer (spiral layer) (17A) on the outer surface of a straight body portion (12A), and a portion of the stacked layers of the sparse first fiber layer (17B) is continuously interlaced between the stacked layers of the second fiber layer (17A) from the first fiber layer (17B), thereby impregnating a fiber layer (17) including the first fiber layer (17B) and the second fiber layer (17A) with resin (18).

Description

Technical Field

[0001] The present invention relates to a method and apparatus for manufacturing a fiber-reinforced (enhanced) tank. Background Art

[0002] Patent Document 1 discloses a method for manufacturing FRP tanks (hereinafter also referred to as high-pressure tanks). This method includes a coating step in which fibers are wrapped around an inner liner, followed by an impregnation step in which the fibers are impregnated with resin. The resin-impregnated fibers are then heated to cure the resin.

[0003] Patent Document 2 discloses a method for manufacturing a high-pressure tank using the related RTM (Resin Transfer Molding) method. In this method, a preform having a fiber layer formed on the outer surface of the lining forming the interior space of the high-pressure tank is placed in a mold. Resin is injected from a gate toward the preform placed in the mold while the preform is rotated circumferentially within the mold about its central axis.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-085199

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-056415 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] In the RTM manufacturing method, the fiber winding and resin impregnation steps are performed separately during the production of high-pressure tanks. However, the amount of fiber winding in high-pressure tanks is large, and the thickness of the fiber layer (buildup) formed by the wound fibers is large. Therefore, it takes time to impregnate the fiber layer (the innermost layer) with resin.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and apparatus for manufacturing a can that can be impregnated with a resin in a short time.

[0011] Means for solving problems

[0012] In order to achieve the above-mentioned purpose, one scheme of the present invention is a method for manufacturing a tank, wherein the tank has a reinforcing layer formed on the outer surface of a hollow inner lining having a cylindrical straight body portion and a dome portion that gradually narrows as it goes from the axial end of the straight body portion to the side opposite to the straight body portion, and the reinforcing layer is formed by impregnating a fiber layer formed by radially overlapping and winding fibers with resin. The manufacturing method is characterized in that it includes the following steps: radially overlapping and winding the fibers onto the outer surface of the inner lining in a manner that makes the first fiber layer at the outer surface of the dome portion sparser than the second fiber layer at the outer surface of the straight body portion, and in a manner that continuously from the first fiber layer a part of the stacking of the sparse first fiber layer exists between a part of the stacking of the second fiber layer; and impregnating the fiber layer including the first fiber layer and the second fiber layer with the resin.

[0013] In a preferred embodiment, the resin is impregnated into the fiber layer in the axial direction and the radial direction of the liner respectively.

[0014] In another preferred embodiment, the resin is injected into the first fiber layer in the axial direction of the liner to impregnate the fiber layer with the resin, and the resin is injected into the second fiber layer in the radial direction of the liner to impregnate the fiber layer with the resin.

[0015] In another preferred embodiment, the resin is impregnated into the fiber layer in the axial direction of the liner and then in both the axial and radial directions of the liner.

[0016] In another preferred embodiment, after the resin is injected into the first fiber layer in the axial direction of the liner, the resin is injected into the first fiber layer in the axial direction of the liner, and the resin is injected into the second fiber layer in the radial direction of the liner, so that the resin impregnates the fiber layers.

[0017] In another preferred embodiment, the first fiber layer is formed by winding fibers in an interlaced weaving manner on the outer surface of the dome portion, the second fiber layer is formed by continuously winding fibers in a spiral or annular shape from the first fiber layer on the outer surface of the straight body portion, and a part of the sparse plies of the first fiber layer is present in a part between the plies of the second fiber layer by continuously winding fibers in an interlaced weaving manner from the first fiber layer.

[0018] Another embodiment of the present invention is a tank manufacturing apparatus comprising a hollow inner liner having a cylindrical straight body portion and a dome portion that gradually tapers from an axial end of the straight body portion toward a side opposite the straight body portion, wherein a reinforcement layer is formed by impregnating a fiber layer formed by radially overlapping and winding fibers with resin. The manufacturing apparatus is characterized in that it includes a mold for accommodating a preform formed by radially overlapping and winding fibers onto the outer surface of the inner liner so that a first fiber layer on the outer surface of the dome portion is sparser than a second fiber layer on the outer surface of the straight body portion, and so that a portion of the stacked layers of the sparse first fiber layer is continuously present between the stacked layers of the second fiber layer. The resin is impregnated into the fiber layers including the first and second fiber layers. In order to impregnate the fiber layers with the resin in both the axial and radial directions of the inner liner, the mold is provided with a plurality of runners through which the resin flows and which form gates opening into the mold, and at least one of the plurality of runners is provided with an opening and closing mechanism.

[0019] In a preferred embodiment, the plurality of flow channels include a first flow channel for injecting the resin into the first fiber layer in the axial direction of the liner and a second flow channel for injecting the resin into the second fiber layer in the radial direction of the liner.

[0020] In another preferred embodiment, the opening and closing mechanism opens and closes at least one of the plurality of flow channels in such a manner that the impregnation of the fiber layer with the resin is performed in the axial direction of the liner and then in both the axial and radial directions of the liner.

[0021] In another preferred embodiment, the multiple flow channels are configured to include a first flow channel for injecting the resin into the first fiber layer in the axial direction of the liner and a second flow channel for injecting the resin into the second fiber layer in the radial direction of the liner. The opening and closing mechanism is at least arranged in the second flow channel. When the second flow channel is closed by the opening and closing mechanism, the resin is injected into the first fiber layer in the axial direction of the liner via the first flow channel. When the second flow channel is opened by the opening and closing mechanism, the resin is injected into the first fiber layer in the axial direction of the liner via the first flow channel, and the resin is injected into the second fiber layer in the radial direction of the liner via the second flow channel.

[0022] Effects of the Invention

[0023] According to one aspect of the present invention, by providing areas with sparse fibers (fiber density) in both the dome portion and the straight body portion during fiber winding, resistance during resin injection is reduced, thereby facilitating resin impregnation and enabling resin impregnation to be achieved in a short time.

[0024] Furthermore, since the injection pressures of the resin in each direction (axial direction or lamination extension direction, radial direction or plate thickness direction) do not interfere with each other during resin injection, resin impregnation up to the inner layer can be achieved in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a side view schematically showing the high-pressure tank (liner wound with fibers) according to the present embodiment.

[0026] Figure 2 It is a cross-sectional view schematically showing the structure of a high-pressure tank (liner wound with fibers) according to the present embodiment.

[0027] Figure 3 This is a schematic diagram showing a manufacturing device (braiding machine) for winding fibers around a liner constituting a high-pressure tank according to the present embodiment.

[0028] Figure 4 This is a schematic diagram showing the feeding position of the fiber when it is wound around the dome portion of the high-pressure tank according to the present embodiment.

[0029] Figure 5 This is a schematic diagram showing the feeding position of the fiber when it is wound around the straight body portion of the high-pressure tank according to the present embodiment.

[0030] Figure 6 This is a side view schematically showing a laminated portion of the high-pressure tank (liner wound with fibers) according to the present embodiment, in which a laminated portion of a braided layer is interposed between laminated portions of a spiral layer.

[0031] Figure 7 It is a longitudinal sectional view showing states of a preform placement step and a vacuum degassing step of the high-pressure tank manufacturing apparatus (resin impregnation molding die) according to the present embodiment.

[0032] Figure 8 It is a longitudinal sectional view showing a state of a resin injection process of the high-pressure tank manufacturing apparatus (resin impregnation molding die) according to the present embodiment.

[0033] Figure 9 This is a plan view of the lower mold with the upper mold removed, illustrating a resin injection process when the opening and closing mechanism of the high-pressure tank manufacturing apparatus (resin impregnation molding mold) according to the present embodiment is in a closed state.

[0034] Figure 10 This is a plan view of the lower mold with the upper mold removed, illustrating a resin injection process when the opening and closing mechanism of the high-pressure tank manufacturing apparatus (resin impregnation molding mold) according to the present embodiment is in the open state. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0036] The following description uses a high-pressure tank for a fuel cell vehicle as an example of a tank. However, the tank to which the present invention is applied is not limited to high-pressure tanks for fuel cell vehicles, and the shape and material of the liner or preform constituting the tank are not limited to those shown in the illustrations.

[0037] In the RTM method, a preform is prepared by wrapping (winding) carbon fibers around an inner liner in multiple layers, forming a fiber layer on the outer surface of the inner liner. The fiber layer of the preform is then impregnated with epoxy resin and cured to produce a high-pressure tank for fuel cell vehicles with a fiber-reinforced resin layer composed of carbon fibers and epoxy resin formed on the outer periphery of the inner liner. The inner liner is a hollow container made of resin (e.g., nylon resin) that forms the interior space of the high-pressure tank.

[0038] In high-pressure tanks for fuel cell vehicles, the carbon fibers are stacked thickly, so the resin doesn't penetrate the inner layers of the carbon fibers. If the resin is injected at high pressure to achieve this, the tank itself deforms, leading to a decrease in quality and performance. Furthermore, the cylindrical shape of the tank makes it difficult to evenly fill the entire tank with resin, resulting in uneven resin impregnation. Furthermore, pressure tends to concentrate near the gate, creating high pressure there and creating a large pressure difference between the gate and the end of the resin flow (the side opposite the gate).

[0039] That is, the stacked thickness of the carbon fiber of the high-pressure tank for fuel cell vehicles is very thick (about 10 times that of a conventional RTM-molded main body part) to ensure strength, making resin impregnation difficult. When the tank is rotated as in Patent Document 2, the resin impregnation effect up to the inner layer of the carbon fiber is small. In addition, if the resin is injected at high pressure in order to impregnate the inner layer of the carbon fiber, the pressure distribution is uneven, and deformation of the resin lining inside the tank occurs at the local high-pressure portion, resulting in a decrease in quality and performance. In addition, since the gap between the mold and the tank is narrow, it is not easy for the resin to flow to the opposite side of the gate. Therefore, in order to make the resin flow to the entire body before the resin solidifies, it is necessary to rotate the tank at high speed in the mold as in Patent Document 2. However, there is little space in the mold, and there is a possibility of damaging the carbon fiber.

[0040] Therefore, this embodiment adopts the following structure.

[0041] (Structure of high-pressure tank)

[0042] First, the structure of the high-pressure tank 10 according to the embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 、 Figure 2The figures are a side view and a cross-sectional view schematically showing the high-pressure tank 10 (the fiber-wound liner) of the present embodiment, respectively. It should be noted that, for the convenience of explanation, the arrow D shown appropriately in each figure is set as the axial direction of the high-pressure tank 10, and the arrow R is set as the radial direction of the high-pressure tank 10. In addition, the side that is away from the center of the high-pressure tank 10 (liner 12) in the axial direction of the central axis CL of the high-pressure tank 10 is set as the "axial end side". In addition, the side that is opposite thereto and close to the center of the high-pressure tank 10 (liner 12) is set as the "axial center side". In addition, the high-pressure tank 10 of the present embodiment is filled with hydrogen as a fuel, for example, in its interior, and is mounted on a fuel cell vehicle (not shown) or the like.

[0043] like Figure 1 、 Figure 2 As shown, the high-pressure tank 10 includes a liner 12 serving as the container body. The liner 12 is blow-molded, for example, from a liquid crystal resin material having excellent gas barrier properties and dimensional stability. It comprises a cylindrical straight body 12A and generally hemispherical dome portions 12B integrally formed at both ends (open ends) of the straight body 12A. More specifically, the liner 12 comprises a cylindrical straight body 12A having a constant inner and outer diameter at the middle portion in its longitudinal direction (axial direction), and dome portions 12B forming both sides of the liner in the longitudinal direction (axial direction) and gradually narrowing (reducing in diameter) as it moves toward the opposite side (axial end side) of the straight body 12A.

[0044] The dome portion 12B includes a cylindrical portion 12C at its axial center portion that protrudes toward the axial end side (outward) of the central axis CL of the liner 12. The inner and outer diameters of the cylindrical portion 12C are smaller than those of the straight portion 12A and are substantially constant.

[0045] The high-pressure tank 10 is constructed by winding ribbon-shaped fibers (also called fiber bundles) 16 of a predetermined width in layers around the outer circumference of the straight body portion 12A and the outer circumference of the dome portion 12B of the liner 12. The fibers 16 are made of fiber-reinforced plastics (FRP) containing glass fibers, carbon fibers, aramid fibers, or the like, forming a fiber-reinforced plastic layer (FRP layer) serving as a reinforcement layer on the outer circumference (external surface) of the liner 12.

[0046] Specifically, the fibers 16 are wound in a staggered braided manner (hereinafter sometimes referred to as "braided winding") on the outer peripheral surface (outer surface) of the dome portion 12B, and the braided layer 17B as the first fiber layer is formed by the braided and wound fibers 16. Figure 8 etc.) is impregnated / cured into the braided layer (first fiber layer) 17B to form a reinforcement layer.

[0047] On the other hand, the fibers 16 are spirally wound on the outer peripheral surface (outer surface) of the straight body portion 12A (hereinafter sometimes referred to as "spirally wound"), and the spirally wound fibers 16 form a spiral layer 17A as a second fiber layer. Figure 8 etc.) is impregnated / cured into the spiral layer (second fiber layer) 17A to form a reinforcement layer.

[0048] Helical winding refers to the process of winding the fibers 16 around the entire outer circumference of the straight body portion 12A at a predetermined winding angle of +θ relative to the central axis CL of the liner 12, and then further winding the fibers 16 from above at a predetermined winding angle of -θ relative to the central axis CL of the liner 12 (crossing the fibers 16 wound at the angle +θ). In other words, the helical layer (second fiber layer) 17A is composed of at least two layers of fibers 16 wound around the outer circumference of the straight body portion 12A at predetermined winding angles of +θ and -θ. It should be noted that, depending on the internal pressure of the straight body portion 12A and the number of fibers in the fibers (bundles) 16, the fibers (bundles) 16 are actually wound (overlapped or stacked in the radial direction) in, for example, several to several dozen layers.

[0049] As described above, the braided winding is winding the fibers 16 in a zigzag braided manner, and here means winding the fibers 16 around the entire outer peripheral surface of the dome portion 12B at predetermined winding angles +θ and −θ relative to the central axis CL of the liner 12 .

[0050] That is, here, both the braided winding and the spiral winding are wound at the same winding angle θ, which includes a tolerance and is within the range of θ=54.7 degrees±10 degrees, preferably within the range of θ=54.7 degrees±5 degrees, and more preferably within the range of θ=54.7 degrees±1 degree.

[0051] The winding angle θ is an angle derived from the stress (axial stress and circumferential stress) at the straight body portion 12A when a predetermined internal pressure is applied, and is an angle at which the stress caused by the circumferential direction is twice the stress caused by the axial direction. That is, although the detailed calculation formula is omitted, when the winding angle θ corresponding to the stress is calculated using the netting theory, tan 2 θ=2, so θ=54.7 degrees (equilibrium angle) is derived.

[0052] Here, dome portion 12B experiences less stress when internal pressure acts than straight body portion 12A, and therefore can be reinforced less than straight body portion 12A. Therefore, as a basic structure, dome portion 12B is provided with a braided winding (braided layer 17B) having larger fiber spacing and a coarser fiber density than the helical winding (helical layer 17A), resulting in a lower strength, while straight body portion 12A is provided with a helical winding (helical layer 17A) having smaller fiber spacing and a denser fiber density than the braided winding (braided layer 17B), resulting in a higher strength.

[0053] It should be noted that, although detailed structural description is omitted, the switching from the braided winding (braided layer 17B) at the dome portion 12B to the spiral winding (spiral layer 17A) at the straight body portion 12A, and conversely, the switching from the spiral winding (spiral layer 17A) in the straight body portion 12A to the braided winding (braided layer 17B) in the dome portion 12B is carried out in an area of ​​a prescribed length in the axial direction near the boundary between the straight body portion 12A and the dome portion 12B when viewed from a direction orthogonal to the axial direction of the center axis CL of the liner 12.

[0054] Although not shown in the drawings, as an example, a sealing plug is fitted into one cylindrical portion 12C, a joint plug is fitted into the other cylindrical portion 12C, and a valve is mounted on the joint plug.

[0055] In addition, if Figure 3 As shown, the fiber 16 is wound around the outer peripheral surface of the liner 12 by a known manufacturing device (also called a braiding machine) 40. Figure 4 、 Figure 5 As shown, the manufacturing apparatus 40 includes a plurality of bobbins 42 and 44 arranged in two rows on the circumference, and the fibers 16 fed from the plurality of bobbins 42 and 44 in each row are axially directed toward the central axis CL ( Figure 3 The outer peripheral surface of the dome portion 12B on one side of the liner 12 moving (in the left direction), the outer peripheral surface of the straight body portion 12A, and the outer peripheral surface of the dome portion 12B on the other side are wound in sequence.

[0056] It should be noted that when the fiber 16 is braided and wound around the dome portion 12B on one side and the other side, Figure 4 As shown, multiple bobbins 42 connected by solid lines and multiple bobbins 44 connected by imaginary lines are arranged alternately radially inward and radially outward in the circumferential direction. Furthermore, the manufacturing apparatus 40 is driven so that the bobbins 42, 44 are sequentially switched from the radially inner side to the radially outer side and from the radially outer side to the radially inner side while the bobbins 42, 44 connected by solid lines and the imaginary lines move in opposite directions.

[0057] In addition, when the fiber 16 is spirally wound around the straight body portion 12A, as shown in FIG. Figure 5As shown, a plurality of bobbins 42 connected by solid lines and a plurality of bobbins 44 connected by imaginary lines are arranged radially outward and radially inward in the circumferential direction. Furthermore, the manufacturing apparatus 40 is driven so that the plurality of bobbins 42 connected by solid lines and the plurality of bobbins 44 connected by imaginary lines move in opposite directions.

[0058] As described above, the basic structure of this embodiment is that the fiber spacing at the dome portion 12B is large and the fiber (density) is sparse, resulting in a low-strength woven winding (woven layer 17B), and the fiber spacing at the straight body portion 12A is small and the fiber (density) is dense, resulting in a high-strength spiral winding (spiral layer 17A). However, in order to facilitate the impregnation of the resin 18 and to impregnate the resin 18 in a short time, the following structure is added.

[0059] That is, Figure 2 As shown, the fibers 16 are wound in layers around the outer peripheral surfaces of the straight body portion 12A and the dome portion 12B of the lining 12 in a manner such that a portion (17D) of the laminated layers of the woven layer 17B is continuously present in a portion of the laminated spaces (including the inner side of the innermost layer and the outer side of the outermost layer) of the spiral layer 17A (for example, composed of several to dozens of layers).

[0060] Specifically, after the fibers 16 are wound in a staggered braided manner (after braiding and winding) at a predetermined stacked portion of the braided layer 17B on the outer peripheral surface (outer surface) of the dome portion 12B, the fibers 16 are continuously (in other words, without switching from braiding and winding to helical winding) wound in a staggered braided manner on the helical layer 17A (the helical layer 17A adjacent to the braided layer 17B) on the outer peripheral surface (outer surface) of the straight body portion 12A (in the case of the innermost layer, the outer peripheral surface of the straight body portion 12A) ( Figure 2 It should be noted that after the fibers 16 are wound in an interlaced braided manner on the spiral layer 17A at the outer peripheral surface (outer surface) of the straight body portion 12A, the fibers 16 are continuously wound in an interlaced braided manner (braided winding) on ​​the braided layer 17B at the outer peripheral surface (outer surface) of the other dome portion 12B (the braided layer 17B adjacent to the spiral layer 17A), thereby further forming a braided layer 17B on the outer peripheral surface (outer surface) of the other dome portion 12B (see also Figure 6 ).

[0061] By winding the fiber 16 as described above at one place (one layer) or multiple places (multiple layers) between the layers (including the inner side of the innermost layer and the outer side of the outermost layer) of the spiral layer 17A (for example, composed of several to dozens of layers), a portion (17D) of the layers of the woven layer 17B is present between the layers of the spiral layer 17A in a continuous manner from the woven layer 17B. It should be noted that between the layers of the spiral layer 17A, the layers of the woven layer 17B can be present one by one, or they can be present in multiple layers. Figure 2 , an example is shown in which the braided layer 17B is stacked one layer at a time.

[0062] As a result, a portion of the stacked layers of the woven layer 17B having large fiber spacing and sparse fiber (density) exists (in a continuous manner from the woven layer 17B) between the stacked layers of the spiral layer 17A having small fiber spacing and dense fiber (density), so that the resin 18 is easily impregnated during the resin injection described later (especially, the spiral layer 17A portion at the outer peripheral surface of the straight body portion 12A), and the resin 18 can be impregnated in a short time.

[0063] The high-pressure tank 10 is formed by impregnating a fiber layer 17 including a braided layer 17B and a spiral layer 17A (including a portion 17D of the braided layer 17B between the layers of the spiral layer 17A) formed by winding fibers 16 in layers around the liner 12 as described above with a fluid uncured thermosetting resin (for example, a resin obtained by mixing an epoxy resin and a curing agent. In this specification, it is sometimes referred to as "resin") 18 and heating it to cure it.

[0064] (Method for manufacturing high-pressure tank)

[0065] A method for manufacturing the high-pressure tank 10 having the above-described structure will be described in detail with reference to the drawings.

[0066] (Fiber Winding Process)

[0067] The high-pressure tank 10 of this embodiment is first constructed by winding the fiber 16 around the outer peripheral surface of the liner 12. Figures 3 to 5 As shown, fibers 16 are sequentially fed from multiple bobbins 42 and 44 of a manufacturing apparatus 40. These fibers 16 are first braided and wound around the outer circumference of one dome portion 12B to form a braided layer 17B (a first step). Specifically, fibers 16 are sequentially braided and wound from the end of the dome portion 12B opposite the straight body portion 12A to the end on the straight body portion 12A side to form the braided layer 17B.

[0068] After the braiding and winding of the fiber 16 with respect to the outer peripheral surface of the dome portion 12B on one side is completed, the fiber 16 is subsequently spirally wound on the outer peripheral surface of the straight body portion 12A to form the spiral layer 17A (second process). Specifically, the fiber 16 is spirally wound in sequence from the end portion on the dome portion 12B side of one side of the straight body portion 12A to the end portion on the dome portion 12B side of the other side to form the spiral layer 17A. It should be noted that the switching from the braiding and winding at the dome portion 12B to the spiral winding at the straight body portion 12A is achieved by adjusting the configuration of the multiple winding tubes 42, 44 of the manufacturing device 40 ( Figure 4 、 Figure 5 ) is switched at a predetermined time width within a region of a predetermined length in the axial direction near the boundary between the dome portion 12B and the straight body portion 12A. Within this region, the fiber 16 can smoothly switch from braided winding to helical winding at the same winding angle θ.

[0069] After the spiral winding of the fiber 16 with respect to the outer peripheral surface of the straight body portion 12A is completed, the fiber 16 is then braided and wound on the outer peripheral surface of the other dome portion 12B to form the braided layer 17B (third step). Specifically, the fiber 16 is braided and wound in sequence from the end portion of the dome portion 12B on the straight body portion 12A side to the end portion on the opposite side of the straight body portion 12A side to form the braided layer 17B. It should be noted that the switching from the spiral winding at the straight body portion 12A to the braided winding at the dome portion 12B is also achieved by adjusting the configuration of the multiple bobbins 42, 44 of the manufacturing device 40 ( Figure 4 、 Figure 5 ) is switched at a predetermined time width within a region of a predetermined length in the axial direction near the boundary between the straight body portion 12A and the dome portion 12B. Within this region, the fiber 16 can smoothly switch from helical winding to braided winding at the same winding angle θ.

[0070] Note that the winding angle θ of the fiber 16 wound around the dome portion 12B and the straight body portion 12A is set to be within the range of 54.7 degrees ± 10 degrees, for example.

[0071] In addition, in this embodiment, after the braiding and winding of the fibers 16 at the stacked portion of the predetermined braided layer 17B is completed, the braiding and winding at the dome portion 12B is not switched to the spiral winding at the straight body portion 12A as described above. Subsequently, the fibers 16 are braided and wound around the outer peripheral surface of the straight body portion 12A (specifically, the outer peripheral surface of the stacked portion of the spiral layer 17A at the outer peripheral surface of the straight body portion 12A) to form a braided layer (equivalent to Figure 2Furthermore, after the braiding and winding of the fiber 16 with respect to the outer peripheral surface of the straight body portion 12A (specifically, the outer peripheral surface of the laminated portion of the spiral layer 17A at the outer peripheral surface of the straight body portion 12A) is completed (without switching from the spiral winding at the straight body portion 12A to the braiding and winding at the dome portion 12B as described above), the fiber 16 is subsequently braided and wound on the outer peripheral surface of the other dome portion 12B to form the braided layer 17B ( Figure 6 ).

[0072] In other words, at the predetermined lamination portion of the braided layer 17B, the fibers 16 are braided and wound in sequence from the end of the dome portion 12B on the side opposite to the straight body portion 12A to the end of the other dome portion 12B on the side opposite to the straight body portion 12A (over the entire axial length of the liner 12) to form the braided layers (17B, 17D, 17B) ( Figure 6 ).

[0073] By winding the fiber 16 as described above at one place (one layer) or multiple places (multiple layers) between the layers (including the inner side of the innermost layer and the outer side of the outermost layer) of the spiral layer 17A (for example, composed of several layers to dozens of layers), a part of the layers (17D) of the woven layer 17B is continuously made to exist between the layers of the spiral layer 17A from the woven layer 17B.

[0074] As described above, the fibers 16 are finally wound (overlapped or stacked in the radial direction) for example in several to several dozen layers, thereby forming a preform 11 (an intermediate body) in which the fiber layer 17 (the braided layer 17B and the spiral layer 17A (including a portion 17D of the stacked braided layer 17B between the stacked layers of the spiral layer 17A)) formed by winding the fibers 16 is formed on the outer peripheral surface (outer surface) of the hollow liner 12. Figures 7 to 10 ).

[0075] (Resin Injection (Resin Impregnation Molding) Process)

[0076] As described above, the preform 11 ( Figures 7 to 10 ) is arranged in a resin impregnation molding mold 50 (between a lower mold 60 and an upper mold 80, also called a cavity) as a manufacturing device, and a thermosetting resin 18 is injected into the mold 50, so that the thermosetting resin 18 is impregnated into the fiber layer 17 (the fibers 16 constituting the fiber layer 17) and heated to solidify it.

[0077] Specifically, if Figure 7 、 Figure 8 As shown, a vacuum degassing pipe 62 connected to a vacuum pump 61 is embedded in the mold 50 (the lower mold 60 in the illustrated example).

[0078] Furthermore, a resin injection pipe (also referred to as a resin injection gate) 82 connected to a resin injector 81 is embedded in the mold 50 (in the illustrated example, the upper mold 80 ).

[0079] In addition, if Figure 9 、 Figure 10 As shown, the mold 50 (in the illustrated example, the lower mold 60) is formed with multiple runners (72A, 72B) connected to the resin injection pipe 82, allowing the resin 18 to flow and forming gates (resin injection ports) that open into the cavity. The runner 72A extends from the resin injection pipe 82 in the radial direction of the preform 11 at the axial center of the preform 11 (i.e., near the center of the straight body portion 12A). The gate 74A formed by the runner 72A opens in the radial direction of the preform 11 at the axial center of the preform 11 (i.e., near the center of the straight body portion 12A). Therefore, resin 18 can be injected from the gate 74A into the spiral layer (second fiber layer) 17A on the outer peripheral surface of the straight body portion 12A within the mold 50 (the cavity) in the radial direction of the preform 11 (in other words, in the thickness direction or lamination direction of the spiral layer 17A). Furthermore, runner 72B branches off from runner 72A to either side in the axial direction of preform 11, and runner 72A extends from resin injection pipe 82 in the radial direction of preform 11. Gates 74B formed by runner 72B open in the axial direction of preform 11 at both axial ends of preform 11 (i.e., near the center of dome portions 12B at both ends). Therefore, resin 18 can be injected from gate 74B into braided layer (first fiber layer) 17B on the outer circumference of dome portion 12B within mold 50 (cavity) in the axial direction of preform 11 (in other words, in the direction in which spiral layer 17A extends).

[0080] It should be noted that in Figure 9 、 Figure 10 In the example shown, the flow channel 72A located in the axial center portion of the preform 11 and the flow channels 72B located at both axial ends of the preform 11 are respectively formed at positions opposite to the central axis CL of the preform 11 (in other words, they are formed in pairs at the front and rear of the preform 11).

[0081] In this embodiment, an opening / closing mechanism 76 such as an opening / closing valve is provided in the runner 72A located in the axial center of the preform 11 in order to open and close the runner 72A at predetermined timings. For example, closing the runner 72A by the opening / closing mechanism 76 can cut off the injection of the resin 18 from the gate 74A into the mold 50 (cavity).

[0082] When impregnating the fiber layer 17 (the fibers 16 constituting the fiber layer 17) of the preform 11 with the thermosetting resin 18, first, with the preform 11 arranged in the mold 50 having the above structure (between the lower mold 60 and the upper mold 80) and maintained at a predetermined temperature (a temperature higher than the curing temperature of the thermosetting resin 18) (in other words, after the mold is closed), the mold 50 is vacuum degassed by controlling the vacuum pump 61. Figure 7 ).

[0083] After the vacuum degassing is stopped (completed), the thermosetting resin 18 ( Figure 8 Here, the injection (impregnation) of the thermosetting resin 18 into the fiber layer 17 of the preform 11 arranged in the mold 50 is performed separately in the axial direction (lamination extension direction) and radial direction (plate thickness direction or lamination direction) of the preform 11 (liner 12).

[0084] Specifically, first, when the opening and closing mechanism 76 is closed (i.e., the runner 72A is closed and the injection of the resin 18 from the gate 74A into the mold 50 is cut off), the (uncured) resin 18 flows in the resin injection pipe 82, and is injected (ejected) from the gate 74B into the braided layer (first fiber layer) 17B on the outer peripheral surface of the dome portion 12B in the mold 50 (cavity) in the axial direction of the preform 11 ( Figure 9 ).

[0085] Thus, the resin 18 is injected (sprayed) in the axial direction of the preform 11 into the braided layer (first fiber layer) 17B having a large fiber spacing and a sparse fiber (density), and the resin 18 is impregnated into the fiber layer 17. At this time, a portion (17D) of the stacked layers of the braided layer 17B exists between the stacked layers of the spiral layer 17A in a continuous manner from the braided layer 17B (see Figure 2 ), the resin 18 is also impregnated (through the braided layer 17B) between the laminated layers of the helical layer 17A where the fiber spacing is small and the fiber (density) is dense.

[0086] Thereafter, the opening and closing mechanism 76 is controlled to be opened. When the opening and closing mechanism 76 is in the opened state (the runner 72A is in the opened state), the (uncured) resin 18 flows in the resin injection pipe 82, and the resin 18 is injected (ejected) in the axial direction of the preform 11 from the gate 74B to the braided layer (first fiber layer) 17B on the outer peripheral surface of the dome portion 12B in the mold 50 (the cavity). Furthermore, the resin 18 is injected (ejected) in the radial direction of the preform 11 from the gate 74A to the spiral layer (second fiber layer) 17A on the outer peripheral surface of the straight body portion 12A in the mold 50 (the cavity). Figure 10 ).

[0087] Thus, the resin 18 is injected (ejected) into the woven layer (first fiber layer) 17B having a large fiber spacing and sparse fiber (density) in the axial direction of the preform 11, and the resin 18 is injected (ejected) into the helical layer (second fiber layer) 17A having a small fiber spacing and dense fiber (density) in the radial direction of the preform 11 (in other words, the resin 18 is injected in both the axial and radial directions of the preform 11), and the resin 18 impregnates the entire fiber layer 17.

[0088] It should be noted that the timing of opening the opening and closing mechanism 76 (i.e., the timing of injecting the resin 18 from the gate 74A via the runner 72A) can be determined based on the measured value obtained from the pressure sensor that detects the pressure of the flowing resin 18, or can be determined based on the timing obtained in advance through experiments, etc.

[0089] After the resin 18 is completely impregnated into the stack of fiber layers 17, the resin injection is stopped and the resin is heated and cured, thereby forming a fiber-reinforced resin layer as a reinforcement layer around the outer periphery of the liner 12. This results in a high-pressure tank 10 that exhibits excellent corrosion resistance, is lightweight and cost-effective, and is easy to transport and handle.

[0090] As described above, in fuel cell vehicle high-pressure tanks manufactured using RTM impregnation technology, it is difficult to uniformly apply resin pressure to fill, impregnate, and cure the epoxy resin throughout the large, thickly layered (thickly wound) tank. This results in reduced productivity and tank performance. Furthermore, because the tanks have thickly layered carbon fibers, impregnation into the innermost carbon fiber layer is not possible without high-pressure resin filling. Consequently, excessive pressure can occur directly below the gate, leading to deformation of the resin liner within the tank and fiber misalignment, a significant quality issue that reduces productivity and tank performance.

[0091] This embodiment aims to achieve a revolutionary improvement in the resin fluidity of a laminated tank and is a method for manufacturing a tank having a dome portion and a straight body portion. The method comprises the steps of preparing a lining, winding fibers around the prepared lining, injecting resin into the wound fibers, and curing the injected resin. In the winding step, the dome portion is wound so as to be sparser than the straight body portion. In the injecting step, resin is injected from the dome portion, and in order to further improve the impregnation in the direction in which the laminations extend, sparse laminations are added between the laminations of the straight body portion (the spiral layer) (continuously from the braided layer).

[0092] In addition, during resin impregnation, there are both a process of injecting resin in the direction of lamination extension and a process of injecting resin in the direction of plate thickness or lamination, and the resin injection in the direction of lamination extension and the resin injection in the direction of plate thickness or lamination are performed separately, and the resin injection in the direction of lamination extension is performed first to control the impregnation and improve the impregnation of the entire tank.

[0093] In addition, the mold 50 has an opening and closing mechanism 76 for the flow path of the resin flow in the RTM mold. The resin is first injected into the dome portion of the tank structure that flows in the direction of the laminate extension and has sparse fibers and good impregnation. After the resin is impregnated in the direction of the laminate extension, the resin is injected in the direction of the plate thickness with a time difference. In this way, the impregnation is controlled without damaging the mutual impregnation, and the pressure of the resin flow can be observed to achieve feedback automatic control of the resin fluidity.

[0094] Because resin injection can be performed along the laminate extension direction, impregnation can reach the inner layers of the carbon fibers, and even further inward. Furthermore, even when the tank is axially elongated, resin impregnation can be achieved uniformly. Furthermore, because the injection pressures of the resin in each direction (laminate extension direction and plate thickness direction) do not interfere with each other, resin impregnation can be further achieved into the inner layers of the carbon fibers. Furthermore, by injecting the resin in the laminate extension direction, where resistance is minimal, fiber movement is suppressed by the resin's viscosity, thus preventing fiber shifting even during resin injection in the plate thickness direction.

[0095] Therefore, when epoxy resin is impregnated through RTM impregnation technology, the entire tank can be evenly impregnated with epoxy resin in the lamination extension direction and the plate thickness direction at low pressure, thereby achieving improved performance and stabilized quality of the high-pressure tank, and also achieving high-speed filling of the resin and significantly shortening the molding cycle.

[0096] Thus, according to this embodiment, by providing areas with sparse fibers (fiber density) in both the dome portion 12B and the straight body portion 12A during fiber winding, the resistance during resin injection is reduced, making it easier to impregnate the resin 18, and resin impregnation can be achieved in a short time.

[0097] Furthermore, since the injection pressures of the resin 18 in each direction (axial direction or lamination extension direction, radial direction or plate thickness direction) do not interfere with each other during resin injection, resin impregnation up to the inner layer can be achieved in a short time.

[0098] In the above embodiment, a portion of the laminated layers of the braided layer 17B is present on the entire surface (so as to cover the entire outer peripheral surface of the helical layer 17A) between the laminated layers of the helical layer 17A (see FIG. Figure 6 ), but of course, a part of the laminated layers of the braided layer 17B may be present only on a part of the surface between the laminated layers of the helical layer 17A.

[0099] Furthermore, the fibers are helically wound (spirally wound) around the outer circumference of the straight body portion 12A to form a helical layer. However, for example, the fibers may be annularly wound (hoop-wound) around the outer circumference of the straight body portion 12A to form a hoop-wound layer by appropriately adjusting the winding angle θ. Furthermore, the fiber winding method itself is not limited to the above-described method, as long as the first fiber layer (fiber density) formed by winding the fibers around the outer circumference of the dome portion 12B is coarser than the second fiber layer (fiber density) formed by winding the fibers around the outer circumference of the straight body portion 12A. This need not be described in detail.

[0100] Furthermore, for example, the liner 12 is not limited to being made of liquid crystal resin. The liner 12 may also be made of other synthetic resins with gas barrier properties, such as high-density polyethylene, or lightweight metals such as aluminum alloy. Furthermore, the liner 12 is not limited to being manufactured by blow molding and may also be manufactured by injection molding or the like.

[0101] While the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments, and any design changes that do not depart from the spirit of the present invention are also encompassed by the present invention.

[0102] Description of Reference Numerals

[0103] 10 High-pressure tanks (tanks)

[0104] 11 Prefabricated Parts

[0105] 12 lining

[0106] 12A straight body

[0107] 12B dome top

[0108] 12C cylindrical part

[0109] 16 fibers

[0110] 17 fiber layers

[0111] 17A spiral layer (second fiber layer)

[0112] 17B braided layer (first fiber layer)

[0113] 18 Thermosetting resin (resin)

[0114] 50 molds

[0115] 60 lower die

[0116] 72A, 72B flow channels

[0117] 74A, 74B gate

[0118] 76 opening and closing mechanism

[0119] 80 upper mold

[0120] CL center axis.

Claims

1. A method for manufacturing a tank, wherein a reinforcement layer is formed on the outer surface of a hollow inner liner having a cylindrical straight body portion and a dome portion that gradually narrows from an axial end of the straight body portion toward a side opposite to the straight body portion, the reinforcement layer being formed by impregnating a fiber layer formed by radially overlapping and winding fibers with a resin. It is characterized in that The process includes the following steps: A step of forming a preform by overlapping and winding the fibers in a radial direction toward the outer surface of the liner so that the first fiber layer on the outer surface of the dome portion is sparser than the second fiber layer on the outer surface of the straight body portion, and so that a portion of the accumulated layers of the sparse first fiber layer is continuously present in a portion between the accumulated layers of the second fiber layer from the first fiber layer; and The preform is accommodated in a mold, and the resin is injected into the mold so that the resin is impregnated into the fiber layer including the first fiber layer and the second fiber layer. In the mold, in order to impregnate the fiber layer with the resin in the axial and radial directions of the liner, a plurality of runners are provided for the resin to flow and form gates opening into the mold, and at least one of the plurality of runners is provided with an opening and closing mechanism. The plurality of runners are configured to include a first runner and a second runner, wherein the first runner extends in the axial direction of the liner and is formed with a gate opening in the axial direction of the liner, and the second runner extends in the radial direction of the liner and is formed with a gate opening in the radial direction of the liner. The resin is injected into the first fiber layer in the mold in the axial direction of the liner from the gate of the first runner that opens in the axial direction of the liner, so that the resin is impregnated into the fiber layer. The resin is injected into the second fiber layer in the mold in the radial direction of the liner from the gate of the second runner that opens in the radial direction of the liner, so that the fiber layer is impregnated with the resin.

2. The method for manufacturing a tank according to claim 1, wherein: The resin is impregnated into the fiber layer in the axial direction and the radial direction of the liner.

3. The method for manufacturing a tank according to claim 1, wherein: The first fiber layer is formed by winding fibers toward the outer surface of the dome portion in an interlaced weaving manner, The second fiber layer is formed by continuously winding fibers from the first fiber layer onto the outer surface of the straight body portion in a spiral or annular shape. By continuously winding fibers from the first fiber layer in a staggered weave, a portion of the sparse plies of the first fiber layer is present in a portion between the plies of the second fiber layer.

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