JP7533399B2 - Tank and manufacturing method thereof - Google Patents

Description

The present invention relates to a tank reinforced (strengthened) with fibers and a method for manufacturing the same.

Patent Document 1 discloses a method for manufacturing an FRP tank (hereinafter also referred to as a high-pressure tank). In this manufacturing method, a coating process is carried out in which fibers are wrapped around the liner to cover it, followed by an impregnation process in which the fibers are impregnated with resin, and then the resin-impregnated fibers are heated to harden the resin.

Patent Document 2 also discloses a high-pressure tank (pressure vessel) manufactured using such an RTM (Resin Transfer Molding) method. This high-pressure tank (pressure vessel) includes a vessel body having a cylindrical straight body and a dome portion including hemispherical hemispherical portions integrally formed at both ends of the straight body, a first reinforcing portion configured by winding reinforcing fibers in a staggered weave around the outer circumferential surface of one of the domes, a second reinforcing portion configured by winding the reinforcing fibers in a helical fashion continuing from the first reinforcing portion around the outer circumferential surface of the straight body, and a third reinforcing portion configured by winding the reinforcing fibers in a staggered weave around the outer circumferential surface of the other dome, continuing from the second reinforcing portion.

JP 2020-085199 A JP 2020-026817 A

In the manufacturing method using the RTM method, the fiber winding process and the resin impregnation process are carried out separately when manufacturing high-pressure tanks. However, there is a risk that the fibers in the straight body part will shift when the resin is injected, reducing the strength.

The present invention was made in consideration of the above circumstances, and aims to provide a tank and a manufacturing method thereof that can prevent fiber displacement during resin injection and suppress a decrease in strength.

In order to achieve the above object, one aspect of the present invention is a tank in which a reinforcing layer is formed on the outer surface of a hollow liner having a cylindrical straight body portion and a dome portion that gradually narrows from the axial end of the straight body portion toward the opposite side of the straight body portion, the reinforcing layer being formed by impregnating a resin with a fiber layer formed by wrapping fibers in a radial overlapping manner, the reinforcing layer being formed by wrapping the fibers in a helical or hoop shape on the outer surface of the liner, the outermost layer being a helical layer or hoop layer, the outermost layer being a braiding layer formed by wrapping the fibers in a staggered weave and with a larger fiber spacing than the helical layer or hoop layer, the fiber layer being impregnated with the resin.

In a preferred embodiment, the fiber layer is composed of a first braiding layer formed by winding the fibers in a staggered manner around the outer surface of the dome portion, a helical layer or hoop layer formed by winding the fibers in a helical or hoop shape continuing from the first braiding layer around the outer surface of the straight body portion, and a second braiding layer formed by winding the fibers in a staggered manner continuing from the first braiding layer around the outermost layer of the helical layer or hoop layer so that the fiber spacing is greater than that of the helical layer or hoop layer, and is impregnated with the resin.

Another aspect of the present invention is a manufacturing method for a tank in which a reinforcing layer is formed by impregnating a resin in a fiber layer formed by radially wrapping fibers on the outer surface of a hollow liner having a cylindrical straight body portion and a dome portion that gradually narrows from the axial end of the straight body portion toward the opposite side of the straight body portion, and the manufacturing method includes the steps of: forming the fiber layer by wrapping a braiding layer on the outermost layer of a helical layer or hoop layer formed by wrapping the fibers in a helical or hoop shape on the outer surface of the liner, and forming the fiber layer by wrapping the fibers in a staggered manner and with a larger fiber spacing than the helical layer or hoop layer; and impregnating the fiber layer formed by wrapping the braiding layer on the outermost layer of the helical layer or hoop layer with the resin.

In a preferred embodiment, the method includes the steps of forming the fiber layer with a first braiding layer formed by winding the fibers around the outer surface of the dome portion in a staggered manner, a helical layer or a hoop layer formed by winding the fibers around the outer surface of the straight body portion in a helical or hoop manner continuing from the first braiding layer, and a second braiding layer formed by winding the fibers around the outermost layer of the helical layer or the hoop layer in a staggered manner continuing from the first braiding layer and with a larger fiber spacing than the helical layer or the hoop layer, and impregnating the fiber layer formed of the first braiding layer and the helical layer or the hoop layer and the second braiding layer with the resin.

In a preferred embodiment, tow prepregs in which fibers are impregnated with a thermoplastic resin are used as part or all of the fibers that make up the braiding layer.

In another preferred embodiment, the resin is a thermosetting resin, and the melting temperature of the thermoplastic resin is equal to or lower than the hardening temperature of the thermosetting resin.

In another preferred embodiment, the thermoplastic resin is composed of a thermoplastic resin that is compatible with the resin.

In another preferred embodiment, the thermoplastic resin is composed of the same type of thermoplastic resin as the resin.

According to one aspect of the present invention, by changing the way the fibers are wound depending on the position, it is possible to prevent the fibers from shifting during resin injection and suppress a decrease in strength.

FIG. 2 is a side view showing a schematic diagram of a high-pressure tank (a liner wound with fibers) according to the present embodiment. FIG. 2 is a cross-sectional view showing a schematic structure of a high-pressure tank (a liner wound with fibers) according to the present embodiment. FIG. 2 is a schematic diagram showing a manufacturing device (braiding machine) that winds fibers around a liner that constitutes the high-pressure tank according to the present embodiment. 5 is a schematic diagram showing the payout position of the fiber when winding it around the dome portion of the high-pressure tank according to the embodiment. FIG. 4 is a schematic diagram showing the payout position of the fiber when winding it around the straight body portion of the high-pressure tank according to the embodiment. FIG. 1A to 1C are vertical cross-sectional views showing the state of a preform arrangement step and a vacuum degassing step of a high-pressure tank manufacturing apparatus (a resin impregnation molding die) according to this embodiment. 1 is a vertical cross-sectional view showing a resin injection process of a high-pressure tank manufacturing apparatus (a resin impregnation molding die) according to an embodiment of the present invention. FIG. FIG. 2 is a side view showing a schematic diagram of another example of a high-pressure tank (a liner wound with fibers) according to the present embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

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 applicable is not limited to high-pressure tanks for fuel cell vehicles, and the shape and material of the liner or preform that constitutes the tank are not limited to the illustrated example.

In the RTM method, a preform is created in which a fiber layer is formed on the outer surface of the liner by wrapping (wrapping) carbon fiber around the liner in multiple layers, and the fiber layer of the preform is impregnated with epoxy resin and cured to produce a high-pressure tank for fuel cell vehicles in which a fiber-reinforced resin layer containing carbon fiber and epoxy resin is formed on the outer periphery of the liner. The liner is a hollow container made of resin (e.g., nylon resin) that forms the internal space of the high-pressure tank.

High-pressure tanks for fuel cell vehicles require filling and impregnating large, thick-walled laminated tanks (thickly wound carbon fiber) with epoxy resin at high speed and high pressure, which can lead to fiber misalignment. In particular, the straight body of the liner requires the reinforcing effect of carbon fiber (see Patent Document 2), and therefore the carbon fiber needs to be wound tightly (without gaps), which can lead to fiber misalignment during RTM resin impregnation, resulting in reduced performance and poor quality.

Therefore, this embodiment adopts the following configuration:

(High pressure tank configuration)
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. FIG. 1 and FIG. 2 are a side view and a cross-sectional view, respectively, that show the high-pressure tank 10 (a liner wound with fibers) according to the present embodiment. The right half of FIG. 1 shows a state in which the braiding layer of the outermost layer (outer surface) has been removed. For convenience of explanation, the arrow D shown appropriately in each figure is the axial direction of the high-pressure tank 10, and the arrow R is the radial direction of the high-pressure tank 10. In addition, in the axial direction of the central axis CL of the high-pressure tank 10, the side away from the center of the high-pressure tank 10 (liner 12) is referred to as the "axial end side". Conversely, the side approaching the center of the high-pressure tank 10 (liner 12) is referred to as the "axial center side". In addition, the high-pressure tank 10 according to the present embodiment is filled with, for example, hydrogen as a fuel, and is mounted on a fuel cell vehicle (not shown) or the like.

As shown in Figures 1 and 2, the high-pressure tank 10 has a liner 12 as a container body. As an example, the liner 12 is blow molded from a liquid crystal resin material that has excellent gas barrier properties and dimensional stability, and has a cylindrical straight body portion 12A and a roughly hemispherical dome portion 12B formed integrally with both ends (end openings) of the straight body portion 12A. More specifically, the liner 12 has a cylindrical straight body portion 12A with constant inner and outer diameters in the middle part in the longitudinal direction (axial direction), and dome portions 12B that form both sides in the longitudinal direction (axial direction) and gradually narrow (reduced in diameter) toward the opposite side (axial end side) from the straight body portion 12A.

In addition, the dome portion 12B includes a cylindrical portion 12C at its axial center that protrudes toward the axial end side (outside) of the center axis CL of the liner 12. The cylindrical portion 12C has a smaller inner diameter and an outer diameter that are approximately constant than those of the straight body portion 12A.

The high-pressure tank 10 is constructed by wrapping tape-like fibers (also called fiber bundles) 16 having a predetermined width in layers around the outer circumferential surface of the straight body portion 12A and the outer circumferential surface of the dome portion 12B of the liner 12. The fibers 16 are made of fiber reinforced plastics (FRP) containing glass fiber, carbon fiber, aramid fiber, or the like, and form a fiber reinforced plastic layer (FRP layer) as a reinforcing layer on the outer circumferential surface (outer surface) of the liner 12.

To be more specific, fibers 16 are wound around the outer peripheral surface (outer surface) of the dome portion 12B in a staggered weave (hereinafter sometimes referred to as "braiding winding"), and the braided fibers 16 form a braiding layer 17B as a first fiber layer. Then, a thermosetting resin 18 (Figure 7) is impregnated into this braiding layer (first fiber layer) 17B and hardens to form a reinforcing layer.

On the other hand, the fiber 16 is helically wound around the outer peripheral surface (outer surface) of the straight body portion 12A (hereinafter sometimes referred to as "helically wound"), and the helically wound fiber 16 forms a helical layer 17A as a second fiber layer. Then, this helical layer (second fiber layer) 17A is impregnated with a thermosetting resin 18 (Figure 7) and hardened to form a reinforcing layer.

Helical winding refers to winding the fiber 16 around the entire outer circumferential surface of the straight body portion 12A at a predetermined winding angle +θ with respect to the central axis CL of the liner 12, and then winding it again at a predetermined winding angle -θ with respect to the central axis CL of the liner 12 (crossing over the fiber 16 wound at angle +θ). In other words, the helical layer (second fiber layer) 17A is formed by winding at least two layers of the fiber 16 around the outer circumferential surface of the straight body portion 12A at a predetermined winding angle +θ and a winding angle -θ. Depending on the internal pressure of the straight body portion 12A and the number of fibers in the fiber (bundle) 16, the fiber (bundle) 16 is actually wound in, for example, several to several tens of layers (overlapped or stacked in the radial direction).

As mentioned above, braiding winding refers to winding the fibers 16 in a staggered pattern, and in this case refers to winding the fibers 16 around the entire outer circumferential surface of the dome portion 12B at a predetermined winding angle +θ and a winding angle -θ relative to the central axis CL of the liner 12.

In other words, here, both the braiding winding and the helical winding are wound at the same winding angle θ, and the winding angle θ is within the range of θ = 54.7 degrees ± 10 degrees, including the tolerance, preferably within the range of θ = 54.7 degrees ± 5 degrees, and more preferably within the range of θ = 54.7 degrees ± 1 degree.

This winding angle θ is an angle derived from the stress (axial stress and circumferential stress) in the straight body portion 12A when a predetermined internal pressure is applied, and is an angle resulting from the fact that the circumferential stress is twice as large as the axial stress. That is, although a detailed calculation formula is omitted, when the winding angle θ according to the stress is calculated according to the netting theory, tan ² θ=2, and therefore θ=54.7 degrees (balance angle) is derived.

Here, the dome portion 12B is subjected to less stress when internal pressure is applied than the straight body portion 12A, and therefore requires less reinforcement than the straight body portion 12A. Therefore, as a basic structure, the dome portion 12B is a braided winding (braiding layer 17B) with larger fiber spacing and coarser fibers (density) and lower strength than the helical winding (helical layer 17A), while the straight body portion 12A is a helical winding (helical layer 17A) with smaller fiber spacing and denser fibers (density) and higher strength than the braided winding (braiding layer 17B) (see the right half of Figure 1).

Although detailed structural description is omitted, the switching from the braiding winding (braiding layer 17B) in the dome portion 12B to the helical winding (helical layer 17A) in the straight body portion 12A, and conversely, the switching from the helical winding (helical layer 17A) in the straight body portion 12A to the braiding winding (braiding layer 17B) in the dome portion 12B, is performed 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 when viewed from a direction perpendicular to the axial direction of the central axis CL of the liner 12.

Although not shown in the figure, as an example, a sealing plug is fitted into one cylindrical portion 12C, and a base plug is fitted into the other cylindrical portion 12C, and a valve is attached to the base plug.

As shown in Fig. 3, the fibers 16 are wound around the outer circumferential surface of the liner 12 by a known manufacturing device (also called a braiding machine) 40. As shown in Figs. 4 and 5, the manufacturing device 40 has a plurality of bobbins 42, 44 arranged in two circumferential rows, and the fibers 16 unwound from the plurality of bobbins 42, 44 in each row are wound in sequence around the outer circumferential surface of one dome portion 12B, the outer circumferential surface of the straight body portion 12A, and the outer circumferential surface of the other dome portion 12B of the liner 12 moving in the axial direction of the central axis CL (leftward in Fig. 3).

When the fibers 16 are braided around one and the other dome portions 12B, as shown in FIG. 4, the multiple bobbins 42 connected by solid lines and the multiple bobbins 44 connected by virtual lines are arranged in the circumferential direction and alternately radially inward and outward. The manufacturing device 40 is driven so that the multiple bobbins 42 connected by solid lines and the multiple bobbins 44 connected by virtual lines move in opposite directions, and the bobbins 42, 44 are sequentially switched from the radially inward to the radially outward and from the radially outward to the radially inward.

When helically winding the fiber 16 around the straight body portion 12A, as shown in FIG. 5, the multiple bobbins 42 connected by solid lines and the multiple bobbins 44 connected by virtual lines are arranged in the circumferential direction, radially outward and radially inward. The manufacturing device 40 is then driven so that the multiple bobbins 42 connected by solid lines and the multiple bobbins 44 connected by virtual lines move in opposite directions.

As described above, in this embodiment, the basic structure is a braided winding (braiding layer 17B) in the dome portion 12B, which has large fiber spacing and coarse fibers (density), resulting in low strength, and a helical winding (helical layer 17A) in the straight body portion 12A, which has small fiber spacing and dense fibers (density), resulting in high strength (see the right half of Figure 1). However, in order to prevent the fibers 16 (particularly the fibers 16 of the helical layer 17A in the straight body portion 12A) from shifting during resin injection, the following configuration is added.

That is, as shown in Figures 1 and 2, the braiding layer 17E is formed by winding the fibers 16 in a staggered manner around the outermost layer of the helical layer 17A (for example, composed of several to several tens of layers) in succession to the braiding layer 17B.

Specifically, the fibers 16 are wound in a staggered weave on the outermost layer of the braiding layer 17B on the outer peripheral surface (outer surface) of the dome portion 12B (after braiding winding), and then the fibers 16 are continuously (in other words, without switching from braiding winding to helical winding) wound in a staggered weave on the helical layer 17A (helical layer 17A adjacent to the braiding layer 17B) on the outer peripheral surface (outer surface) of the straight body portion 12A (part 17E in Figure 2). The fibers 16 are wound in a staggered weave on the helical layer 17A on the outer circumferential surface (outer surface) of the straight body portion 12A, and then the fibers 16 are wound in a staggered weave (braid winding) on the braiding layer 17B (the braiding layer 17B adjacent to the helical layer 17A) on the outer circumferential surface (outer surface) of the other dome portion 12B, thereby forming a further braiding layer 17B on the outer circumferential surface (outer surface) of the other dome portion 12B.

In other words, the braiding layer (17B, 17E, 17B) is formed by winding the fibers 16 in a staggered manner in the outermost layer of the fiber layer (over the entire axial length of the liner 12), including the braiding layer 17B on the outer peripheral surface of one dome portion 12B of the liner 12, the helical layer 17A on the outer peripheral surface of the straight body portion 12A, and the braiding layer 17B on the outer peripheral surface of the other dome portion 12B. The braiding layer 17E formed by layering or stacking on the outermost layer of the helical layer 17A may be a single layer or multiple layers (e.g., several layers). Figure 2 shows an example in which only a single layer of the braiding layer 17E is formed.

As a result, the outermost layer of the helical layer 17A, which has small fiber spacing and dense fibers (density) that are prone to fiber slippage, is woven alternately (continuously from the braiding layer 17B) to form the braiding layer 17E, which has large fiber spacing and coarse fibers (density) that are less likely to cause fiber slippage (in other words, the outermost layer of the helical layer 17A, which is prone to fiber slippage, is covered with the braiding layer 17E, which is less likely to cause fiber slippage), preventing fiber 16 from slipping during resin injection, as described below.

The high-pressure tank 10 is formed by impregnating the fiber layer 17, which includes the braiding layer 17B, the helical layer 17A, and the braiding layer 17E, formed by wrapping the fiber 16 in layers around the liner 12 as described above, with a fluid, uncured thermosetting resin 18 (e.g., a resin made of a mixture of epoxy resin and a curing agent; sometimes simply referred to as "resin" in this specification), heating it, and curing it.

(Manufacturing method of high pressure tank)
A method for manufacturing the high-pressure tank 10 having the above-mentioned configuration will be described in detail with reference to the drawings.

(Fiber winding process)
The high-pressure tank 10 according to this embodiment is constructed by first winding the fibers 16 around the outer peripheral surface of the liner 12. That is, as shown in Figures 3 to 5, the fibers 16 are sequentially unwound from a plurality of bobbins 42, 44 of the manufacturing device 40, and the fibers 16 are first braid-wound around the outer peripheral surface of one of the dome sections 12B to form the braiding layer 17B (first step). More specifically, the fibers 16 are sequentially braid-wound from the end of the dome section 12B opposite the straight body section 12A side to the end on the straight body section 12A side to form the braiding layer 17B.

After the braiding winding of the fiber 16 on the outer peripheral surface of one dome portion 12B is completed, the fiber 16 is then helically wound on the outer peripheral surface of the straight body portion 12A to form a helical layer 17A (step 2). In detail, the fiber 16 is helically wound in sequence from the end of the straight body portion 12A on one dome portion 12B side to the end of the straight body portion 12A on the other dome portion 12B side to form the helical layer 17A. The switching from the braiding winding in the dome portion 12B to the helical winding in the straight body portion 12A is performed 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 by switching the arrangement of the multiple bobbins 42, 44 of the manufacturing device 40 (Figures 4 and 5) at a predetermined time interval. Here, within the above region, the fiber 16 can be smoothly switched from the braiding winding to the helical winding at the same winding angle θ.

After the helical winding of the fiber 16 on the outer peripheral surface of the straight body portion 12A is completed, the fiber 16 is then braided around the outer peripheral surface of the other dome portion 12B to form the braiding layer 17B (step 3). In detail, the fiber 16 is braided from the end of the dome portion 12B on the straight body portion 12A side to the end on the opposite side of the straight body portion 12A side to form the braiding layer 17B. The helical winding in the straight body portion 12A is also switched to the braiding winding in the dome portion 12B in a region of a predetermined length in the axial direction near the boundary between the straight body portion 12A and the dome portion 12B by switching the arrangement of the multiple bobbins 42, 44 of the manufacturing device 40 (Figures 4 and 5) at a predetermined time interval. Here, in the above region, the fiber 16 can be smoothly switched from the helical winding to the braiding winding at the same winding angle θ.

The winding angle θ of the fibers 16 wound around the one and other dome portions 12B and the straight body portion 12A is set within a range of 54.7 degrees ±10 degrees, for example.

In this embodiment, when the braiding winding of the fiber 16 is completed in the outermost layer of the braiding layer 17B, the above-mentioned switching from the braiding winding in the dome portion 12B to the helical winding in the straight body portion 12A is not performed, and the fiber 16 is then braided around the outer peripheral surface of the straight body portion 12A (more specifically, the outer peripheral surface of the helical layer 17A on the outer peripheral surface of the straight body portion 12A) to form the braiding layer 17E. Also, when the braiding winding of the fiber 16 is completed on the outer peripheral surface of the straight body portion 12A (more specifically, the outer peripheral surface of the helical layer 17A on the outer peripheral surface of the straight body portion 12A) (without switching from the helical winding in the straight body portion 12A to the braiding winding in the dome portion 12B as described above), the fiber 16 is then braided around the outer peripheral surface of the other dome portion 12B to form the braiding layer 17B.

In other words, in the outermost layer such as the braiding layer 17B, the fibers 16 are sequentially braid-wound from the end of one dome portion 12B opposite the straight body portion 12A to the end of the other dome portion 12B opposite the straight body portion 12A (over the entire axial length of the liner 12) to form the braiding layers (17B, 17E, 17B).

By winding the fibers 16 as described above, the braiding layer 17E is layered (laminated) on the outermost layer of the helical layer 17A, continuing from the braiding layer 17B.

As described above, the fibers 16 are eventually wound, for example, in several to several tens of layers (overlapping or stacking in the radial direction), to form a preform 11 (Figures 6 and 7) as an intermediate body in which fiber layers 17 (braiding layer 17B, helical layer 17A, braiding layer 17E) formed by wrapping the fibers 16 are formed on the outer peripheral surface (outer surface) of the hollow liner 12.

(Resin injection (resin impregnation molding) process)
The preform 11 (FIGS. 6 and 7) in which the fiber 16 is wound around the hollow liner 12 to form the fiber layer 17 as described above is placed in a resin impregnation molding die 50 (between the lower die 60 and the upper die 80, also called the cavity) as a manufacturing device, and thermosetting resin 18 is injected into the die 50 to impregnate the fiber layer 17 (the fibers 16 constituting the fiber layer 17) with the thermosetting resin 18, which is then heated and hardened.

Specifically, as shown in Figures 6 and 7, a vacuum degassing pipe 62 connected to a vacuum pump 61 is embedded in the mold 50 (lower mold 60 in the illustrated example).

In addition, a resin injection pipe (also called a resin injection gate) 82 to which a resin injector 81 is connected is embedded in the mold 50 (upper mold 80 in the illustrated example).

When impregnating the fiber layer 17 (fibers 16 constituting the fiber layer 17) of the preform 11 with the thermosetting resin 18, first, the preform 11 is placed in the mold 50 (between the lower mold 60 and the upper mold 80) having the above-described configuration and kept at a predetermined temperature (a temperature equal to or higher than the curing temperature of the thermosetting resin 18) (in other words, after the mold is clamped), and the inside of the mold 50 is evacuated and degassed by controlling the vacuum pump 61 (Figure 6).

After the above vacuum degassing is stopped (completed), the resin injector 81 is driven to inject thermosetting resin 18 into the mold 50 (Figure 7).

As a result, the (uncured) resin 18 that flows through the resin injection pipe 82 and is injected (discharged) into the mold 50 (cavity) passes through the braiding layer 17E and impregnates the helical layer 17A and the braiding layer 17B (i.e., the entire fiber layer 17). At this time, the outermost layer of the preform 11 (fiber layer 17) is provided with the braiding layer 17E, which is less likely to cause fiber displacement (in other words, it is covered with the braiding layer 17E, which is less likely to cause fiber displacement), so that the displacement of the fibers 16 (especially the fibers 16 of the helical layer 17A in the straight body portion 12A) when the resin 18 is injected (impregnated) is suppressed. In addition, the braiding layer 17E (braiding winding) has a larger fiber spacing and a coarser fiber (density) than the helical layer 17A (helical winding), so it does not hinder the injection (impregnation) of the resin 18 into the inner helical layer 17A.

After the resin 18 has completely impregnated the laminated fiber layers 17, the resin injection is stopped and the resin is heated and hardened to form a fiber-reinforced resin layer as a reinforcing layer on the outer periphery of the liner 12. This results in a high-pressure tank 10 that is highly corrosion-resistant, lightweight, low-cost, and easy to transport and handle.

As explained above, when manufacturing high-pressure tanks for fuel cell vehicles using RTM impregnation technology, epoxy resin must be filled and impregnated into large, thick-walled laminated tanks (thickly wound with carbon fiber) at high speed and high pressure. During this process, the carbon fiber wound around the preform can shift or the fiber width can shrink, leading to reduced productivity and reduced tank performance.

In this embodiment, for the purpose of reinforcing effect, fiber bundles such as braided windings are woven into the outermost layer of a preform in which fiber bundles are densely wound, such as highly helical windings with small gaps between the carbon fiber bundles, making it difficult for the fiber bundles to shift, and a fiber laminate (braiding layer 17E) with large gaps between the fiber bundles is set.

The carbon fiber layers are less likely to shift and the carbon fiber width does not shrink, so performance degradation can be suppressed, and even if such fiber shift prevention measures are woven in, the braiding winding (braiding layer 17E) has large gaps between the carbon fibers, so measures can be taken without reducing resin impregnation.

This prevents the carbon fibers from shifting or reducing in fiber width when the epoxy resin is injected, improving the resin impregnation and tank performance of the high-pressure tank 10 and providing good surface quality.

In this way, according to this embodiment, by changing the way the fibers 16 are wound depending on the position, it is possible to prevent the fibers 16 from shifting and the fiber width from shrinking when the resin is injected, and to suppress a decrease in strength.

In addition, to more reliably prevent fiber displacement during resin injection, for example, as shown in FIG. 8, a tow prepreg 19 in which a fiber (e.g., carbon fiber) is impregnated with a thermoplastic resin (e.g., epoxy resin) may be used as part or all of the fiber 16 (constituting braiding layer 17E) to be braided around the outermost layer of fiber layer 17. In other words, the outermost layer of fiber layer 17 may be formed by replacing part or all of the above-mentioned fiber 16 with tow prepreg 19 and braiding it.

In this case, when winding the outermost layer in the manufacturing device 40, some or all of the multiple bobbins 42, 44 can be replaced with bobbins loaded with the tow prepreg 19, and the outermost layer can be wound.

When the preform 11 formed by braiding the tow prepreg 19 on the outermost layer of the fiber layer 17 is placed in the mold 50 kept at a predetermined temperature (a temperature equal to or higher than the curing temperature of the thermosetting resin 18), if the melting temperature of the thermoplastic resin constituting the tow prepreg 19 is equal to or lower than the curing temperature of the thermosetting resin 18, the thermoplastic resin constituting the tow prepreg 19 melts and bonds the fibers constituting the tow prepreg 19 (i.e., the fibers constituting the braiding layer 17E) to the fibers 16 constituting the inner helical layer 17A, and the fibers 16 constituting the helical layer 17A are also bonded to each other, so that fiber displacement during resin injection can be more effectively prevented. Also, the thermoplastic resin constituting the innermost layer of the tow prepreg 19 is bonded to the liner 12, so that fiber displacement can be more effectively prevented.

The thermoplastic resin constituting the tow prepreg 19 is preferably a thermoplastic resin that is compatible with the thermosetting resin 18 and has high adhesiveness, since it constitutes the reinforcing layer (fiber-reinforced resin layer) together with the thermosetting resin 18 (resin impregnated into the fiber layer 17). For example, the thermoplastic resin constituting the tow prepreg 19 is preferably a thermoplastic epoxy resin of the same type as the epoxy resin constituting the thermosetting resin 18. In other words, it is preferable to use an epoxy resin that has both thermosetting and thermoplastic properties (melting temperature is below the curing temperature).

In other words, in this embodiment, when winding several dozen carbon fibers in a multi-yarn filament winding (FW) such as braiding winding, part or all of the carbon fiber bobbin is replaced with a tow prepreg (TPP) containing a thermoplastic epoxy resin that is highly compatible with the epoxy resin impregnated in the fiber layer and has high adhesiveness, and the outermost layer is wound, thereby preventing fiber displacement during resin injection during RTM molding.

As a result, similar to the embodiment described based on Figures 1 and 2, etc., it is possible to prevent the carbon fibers from shifting or the fiber width from shrinking when the epoxy resin is injected, and therefore it is possible to obtain resin impregnation and improved tank performance and good surface quality in the high-pressure tank 10.

In the above embodiment, the braiding layer 17E is formed over the entire surface of the outermost layer of the fiber layer 17 (helical layer 17A) (so as to cover the entire outer peripheral surface of the helical layer 17A), but it goes without saying that the braiding layer 17E may be formed over only a portion of the surface of the outermost layer of the fiber layer 17 (helical layer 17A).

In addition, the helical layer is formed by helically winding the fibers around the outer peripheral surface of the straight body portion 12A, but the fibers may also be wound in a hoop shape around the outer peripheral surface of the straight body portion 12A to form a hoop layer, for example by appropriately adjusting the winding angle θ.

In addition, for example, the liner 12 is not limited to being made of liquid crystal resin. The liner 12 may be made of other synthetic resins that have gas barrier properties, such as high-density polyethylene, or may be made of lightweight metals, such as aluminum alloys. In addition, the liner 12 is not limited to being manufactured by blow molding, and may be manufactured by injection molding, etc.

The above describes the embodiment of the present invention in detail using the drawings, but the specific configuration is not limited to this embodiment, and even if there are design changes, etc., within the scope of the gist of the present invention, they are included in the present invention.

10. High pressure tank (tank)
REFERENCE SIGNS LIST 11 Preform 12 Liner 12A Straight body portion 12B Dome portion 12C Cylindrical portion 16 Fiber 17 Fiber layer 17A Helical layer 17B Braiding layer (first braiding layer)
17E Braiding layer (second braiding layer)
18 Thermosetting resin (resin)
19 Tow prepreg 50 Mold 60 Lower mold 80 Upper mold CL Central axis

Claims (8)

A tank in which a hollow liner has a cylindrical straight body portion and a dome portion that gradually narrows from an axial end of the straight body portion toward the opposite side to the straight body portion, and a reinforcing layer is formed on the outer surface of the liner by impregnating a resin with a fiber layer formed by winding fibers in a radial overlapping manner,
A tank characterized in that the tank is constructed by overlapping a braiding layer formed by winding the fibers in a staggered manner and with larger fiber spacing than the helical layer or hoop layer, on the outermost layer of a helical layer or hoop layer formed by winding the fibers in a helical or hoop shape around the outer surface of the liner, and impregnating the fiber layer with the resin. 2. The tank according to claim 1,
a helical layer or hoop layer formed by winding the fibers in a helical or hoop shape continuing from the first braiding layer around the outer surface of the straight body portion; and a second braid layer formed by winding the fibers in a helical or hoop shape continuing from the first braiding layer around the outermost layer of the helical layer or hoop layer so that the fibers are woven in a staggered manner and have larger fiber spacing than the helical layer or hoop layer, the second braiding layer being impregnated with the resin. A method for manufacturing a tank, comprising the steps of: forming a reinforcing layer on an outer surface of a hollow liner having a cylindrical straight body portion and a dome portion that gradually narrows from an axial end of the straight body portion toward an opposite side to the straight body portion; and forming the reinforcing layer by impregnating a resin on a fiber layer formed by winding fibers in a radial overlapping manner, the method comprising the steps of:
a step of forming the fiber layer by overlapping an outermost layer of a helical layer or a hoop layer formed by winding the fiber in a helical or hoop shape around the outer surface of the liner with a braiding layer formed by winding the fiber in a staggered manner and with a larger fiber spacing than the helical layer or the hoop layer;
and impregnating the fiber layer, which is formed by overlapping the braiding layer on the helical layer or the outermost layer of the hoop layer, with the resin. The method for manufacturing a tank according to claim 3,
a step of forming the fiber layer with a first braiding layer formed by winding the fibers in a staggered manner around the outer surface of the dome portion, a helical layer or a hoop layer formed by winding the fibers in a helical or hoop manner continuing from the first braiding layer around the outer surface of the straight body portion, and a second braiding layer formed by winding the fibers in a staggered manner around the outermost layer of the helical layer or the hoop layer continuing from the first braiding layer and with a larger fiber spacing than the helical layer or the hoop layer;
and impregnating the fiber layer composed of the first braiding layer and the helical layer or the hoop layer and the second braiding layer with the resin. 4. The method for manufacturing a tank according to claim 3,
A method for manufacturing a tank, comprising the steps of: (a) forming a braided layer by using a tow prepreg having fibers impregnated with a thermoplastic resin as a part or all of the fibers constituting the braided layer; 6. The method for manufacturing a tank according to claim 5,
The resin is a thermosetting resin,
A method for manufacturing a tank, wherein the melting temperature of the thermoplastic resin is lower than or equal to the hardening temperature of the thermosetting resin. 6. The method for manufacturing a tank according to claim 5,
A method for manufacturing a tank, wherein the thermoplastic resin is made of a thermoplastic resin that is compatible with the resin. 6. The method for manufacturing a tank according to claim 5,
A method for manufacturing a tank, characterized in that the thermoplastic resin is made of the same type of thermoplastic resin as the resin.