Method for manufacturing tank and hydrogen tank

Abstract

To provide a technology achieving both of sufficient impregnation of resin and securement of quality of a tank in manufacturing the tank.SOLUTION: A method for manufacturing a tank comprises: a preparation process for preparing a preform where a plurality of layers of fiber bundles are wounded around the outer surface of a liner partitioning the inside space of the tank and provided with a tubular trunk, a metal mold, and a sheet constituted of three-dimensional net-state fibers; a winding process for winding the sheet around the outer surface of the preform by one round or more along a peripheral direction of the trunk of the preform; an injection process for injecting resin to the inside of the metal mold in an arrangement state of arranging the sheet-wound preform in the metal mold; and an impregnation process for impregnating the resin into the sheet and the fiber bundles. In the winding process, the sheet is wound around at least a part of the trunk, the sheet-wound preform is provided with a gap extending in a direction different from a direction where the fibers of the fiber bundle extend on the outer surface of the preform.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method of manufacturing a tank and to a hydrogen tank. [Background technology]

[0002] Conventionally, as disclosed in Patent Document 1, a technique is known in which a fiber reinforced resin layer and a resin layer are formed on the outer periphery of a liner by a resin transfer molding (RTM) method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-118288 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the intermediate product formed by winding fibers around the outer surface of the liner as a tank in the middle of manufacturing, the shape is likely to vary. Therefore, when the mold and the intermediate product come into contact with each other during the resin impregnation process, the fibers at the contact area may not be sufficiently impregnated with resin.

[0005] The inventors have investigated a method of ensuring a flow path for the resin by providing irregularities on the surface of a mold. However, the resistance when releasing a tank from a mold with irregularities is greater than the resistance when releasing a tank from a mold with a flat surface. When the tank is released from the mold, it is pushed out by an ejector pin. If the resistance when releasing is large, the resin layer of the tank may be damaged by receiving an excessive load from the ejector pin. Therefore, in the manufacture of the tank, it has been an issue to achieve both sufficient resin impregnation and ensuring the quality of the tank. [Means for solving the problem]

[0006] The present disclosure can be realized in the following forms.

[0007] (1) According to one embodiment of the present disclosure, there is provided a method for manufacturing a tank, the method including: a preparation step of preparing a preform having a cylindrical body portion, the preform being formed by winding a plurality of layers of fiber bundles around an outer surface of a liner that defines an internal space of the tank, a mold, and a sheet formed of three-dimensional mesh-like fibers; a winding step of winding the sheet around the outer surface of the preform for one or more revolutions along the circumferential direction of the body portion; an injection step of injecting a resin into the mold in a state in which the preform wrapped with the sheet is placed in the mold; and an impregnation step of impregnating the sheet and the fiber bundles with the resin, the winding step including winding the sheet around at least a portion of the body portion, the preform wrapped with the sheet having voids extending in a direction different from the direction in which the fibers of the fiber bundles extend on the outer surface of the preform. By adopting such a form, in the impregnation process, the resin is impregnated through the sheet and the fiber bundle. The sheet overlaps the fiber bundle, and functions as a flow path for the resin between the mold and the fiber bundle. More specifically, the sheet defines a gap extending in a direction different from that of the fiber bundle between the preform. Therefore, the resin is easily allowed to flow between the mold and the fiber bundle, and the fiber bundle is less likely to have an unimpregnated portion. Furthermore, since the manufacturing method of the tank of the present disclosure does not require a special mold structure, impregnation can be easily performed even with an existing mold structure. That is, the manufacturing method of the tank of the present disclosure can manufacture the tank while ensuring the quality of the tank by using a mold similar to that of a conventional one. Therefore, the manufacturing method of the tank of the present disclosure can achieve both sufficient impregnation of the resin and ensuring the quality of the tank. (2) In the method for manufacturing a tank of the above aspect, in the winding step, the sheet may be wound around the entire body portion. By adopting such a configuration, when the sheet comes into contact with the mold, the load caused by the clamping of the mold is less likely to concentrate on a portion of the body. For example, when the sheet is wrapped around a portion of the body, the load caused by the clamping of the mold is likely to concentrate on a portion of the body. As a result, unimpregnated portions may occur during the impregnation process. By wrapping the sheet around the entire body, the load caused by the clamping of the mold is distributed over the entire body. Thus, the tank manufacturing method of the present disclosure can reduce the possibility of unimpregnated portions occurring in the body. (3) In the method for manufacturing a tank according to the above aspect, the impregnation step may include a step of forming a layer of the resin on the sheet. By adopting such a configuration, the tank manufacturing method of the present disclosure can protect the body portion by covering the entire body portion with a resin layer. (4) In the tank manufacturing method of the above aspect, in the winding step, the sheet may be wound a plurality of times. The outer diameter of the preform varies depending on the accuracy of winding the fiber bundle. By adopting such a configuration, the method for manufacturing a tank of the present disclosure can easily adjust the outer diameter of the preform including the sheet to match the size of the mold by adjusting the number of turns of the sheet. Therefore, the method for manufacturing a tank of the present disclosure can more appropriately impregnate the resin. (5) According to another aspect of the present disclosure, there is provided a hydrogen tank comprising a cylindrical body, the hydrogen tank comprising an outer layer including a resin and covering the body, the outer layer including a lower layer made of a plurality of fiber bundles and an upper layer including a sheet configured in a three-dimensional mesh shape and overlapping the lower layer, the sheet including voids extending in a direction different from the direction in which the fibers of the fiber bundle extend. By adopting such a configuration, when the outer layer of the hydrogen tank is manufactured by the RTM method, the hydrogen tank of the present disclosure allows the resin to flow into the fiber bundle through the sheet. Therefore, the fiber bundle and the mold do not come into contact with each other, and therefore the hydrogen tank of the present disclosure is less likely to have unimpregnated portions. Furthermore, the hydrogen tank of the present disclosure can be easily impregnated even with an existing mold structure by using the sheet. In other words, the hydrogen tank of the present disclosure can be easily manufactured while ensuring the quality of the hydrogen tank. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view showing a schematic configuration of a tank. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of a preform. [Diagram 3] FIG. 2 is a plan view showing a preform wrapped with flow media. [Figure 4] FIG. 2 is a plan view showing the structure of a flow medium. [Diagram 5] FIG. 5 is a cross-sectional view showing the VV cross section of FIG. [Figure 6] FIG. 2 is a diagram showing a schematic configuration of a tank manufacturing apparatus. [Figure 7] FIG. 4 is an explanatory diagram showing an ejector pin. [Figure 8] FIG. 8 is a cross-sectional view showing the VIII-VIII cross section of FIG. 7. [Figure 9] 1 is a flowchart showing a manufacturing method of a tank. [Figure 10] 13 is a graph showing the fluctuation range of the outer diameter of the tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A. First embodiment: A-1. Preform and tank configuration: Fig. 1 is a cross-sectional view showing a schematic configuration of a tank 100. Fig. 2 is a cross-sectional view showing a schematic configuration of a preform P100. The tank 100 shown in Fig. 1 is manufactured by processing the preform P100 shown in Fig. 2.

[0010] 1 and 2 show cross-sectional views perpendicular to the central axis O of the preform P100 and the tank 100, respectively. In FIG. 1 and FIG. 2, the X-axis, Y-axis, and Z-axis are depicted as mutually orthogonal axes. The directions in which the arrows of the X-axis, Y-axis, and Z-axis point indicate the positive directions along the X-axis, Y-axis, and Z-axis, respectively. The positive directions along the X-axis, Y-axis, and Z-axis are respectively the +X direction, +Y direction, and +Z direction. The directions opposite to the directions in which the arrows of the X-axis, Y-axis, and Z-axis point are the negative directions along the X-axis, Y-axis, and Z-axis. The negative directions along the X-axis, Y-axis, and Z-axis are respectively the -X direction, -Y direction, and -Z direction. The directions along the X-axis, Y-axis, and Z-axis, regardless of whether they are positive or negative, are called the X direction, Y direction, and Z direction, respectively.

[0011] In this embodiment, the X direction is a direction along the central axis O of the tank 100. A direction parallel to the central axis O is also referred to as an axial direction OD. The Y direction is a direction along the direction of gravity in the arrangement posture of the tank 100 described below. The -Y direction coincides with the direction of gravity in the arrangement posture. Furthermore, a direction perpendicular to the central axis O is referred to as a radial direction CD. A direction parallel to the circumference of a circle whose center is the central axis O is referred to as a circumferential direction LD. Furthermore, in the radial direction CD of the tank 100, the side approaching the central axis O is referred to as the inner side, and the side away from the central axis O is referred to as the outer side.

[0012] The tank 100 is, for example, a hydrogen tank. The hydrogen tank as the tank 100 is mounted on a fuel cell vehicle and is used to store hydrogen gas at high pressure to be supplied to the fuel cell. The tank 100 includes a liner 110, a reinforcing layer 120, a cap 130, and a flow medium 140.

[0013] In the manufacturing process of the tank 100, the tank 100 is manufactured by impregnating a fiber layer P121, which will be described later, with a resin. The tank 100 before impregnation is called a preform P100. That is, the preform P100 is an intermediate product in the manufacturing process of the tank 100. The preform P100 will be described later. In this specification, impregnation refers to soaking a fiber bundle in a resin to soak it in the resin.

[0014] The liner 110 is a hollow container that defines an internal space 110p of the tank 100 to store a fluid. The liner 110 is formed of a resin having gas barrier properties, such as a polyamide resin. The central axis O of the liner 110 is the same as the central axis O of the tank 100.

[0015] The nozzles 130 are provided at both ends of the tank 100. One of the nozzles 130, the nozzle 130 at the right end in FIG. 1, communicates the space inside the liner 110 with the outside space. That is, one of the nozzles 130 has a cylindrical through-hole. The other nozzle 130, the nozzle 130 at the left end in FIG. 1, has a cylindrical external shape but does not have a through-hole.

[0016] The reinforcing layer 120 is a layer for reinforcing the liner 110. The reinforcing layer 120 covers the outer periphery of the liner 110. The reinforcing layer 120 includes a fiber reinforced resin layer 121 and a resin layer 122.

[0017] The fiber reinforced resin layer 121 covers the outer surface 110o of the liner 110. The material constituting the fiber reinforced resin layer 121 is, for example, fiber reinforced resin such as CFRP (Carbon Fiber Reinforced Plastics). CFRP is formed by impregnating carbon fiber with a thermosetting resin such as epoxy resin and then thermally curing the resin. Therefore, the fiber reinforced resin layer 121 includes multiple layers of fiber bundles wound around the outer surface 110o of the liner 110. That is, the fiber reinforced resin layer 121 is formed on the outer surface 110o of the liner 110 by impregnating multiple layers of fiber bundles with resin. The layer of fiber bundles before being impregnated with resin is called a fiber layer P121.

[0018] The resin layer 122 covers an outer surface 121o of the fiber reinforced resin layer 121. The resin layer 122 is formed of the same resin as that impregnated into the fibers in the process of forming the fiber reinforced resin layer 121. More specifically, the resin layer 122 is a layer formed by thermal curing on the outer side of the fiber bundles in the fiber reinforced resin layer 121. In this embodiment, the fiber reinforced resin layer 121 and the resin layer 122 are formed by a resin transfer molding (RTM) method using a tank manufacturing mold 21 in FIG. 6 shown later. In the following description, the resin transfer molding method is called the RTM method, and the tank manufacturing mold 21 is simply called the mold 21. Details of the method of forming the fiber reinforced resin layer 121 and the resin layer 122 by the RTM method will be described later.

[0019] The flow medium 140 is a sheet made of three-dimensional mesh-like fibers. The flow medium 140 is provided inside the resin layer 122. The flow medium 140 will be described in detail later. The flow medium 140 is also called the sheet 140.

[0020] The preform P100 as an intermediate product in the manufacturing process of the tank 100 will be described. As shown in Fig. 2, the preform P100 is composed of a liner 110, a fiber layer P121, and a die 130. In Fig. 2, a flow medium 140 is illustrated to facilitate understanding of the technology. The configurations of the liner 110 and the die 130 are the same as those of the tank 100. The fiber layer P121 will be described later.

[0021] The shape of the preform P100 will be described below. The preform P100 has a cylindrical body portion 100b and hemispherical spherical portions 100e on both ends of the body portion 100b.

[0022] More specifically, the body portion 100b is a range in the axial direction OD defined by a portion of the outer surface 110o of the liner 110 parallel to the axial direction OD. The body portion 100b is similarly defined even in a state in which a fiber layer P121, a resin layer 122, etc. are laminated on the surface of the liner 110, such as in the tank 100 or the preform P100.

[0023] The spherical portion 100e is a portion of the liner 110 that does not include the body portion 100b. As with the body portion 100b, the spherical portion 100e is defined in the same manner even when the fiber layer P121, the resin layer 122, etc. are laminated on the surface of the liner 110. The spherical portion 100e is provided on both ends of the body portion 100b. More specifically, the spherical portion 100e is provided continuously with the end portion 100be in the axial direction OD of the body portion 100b. The shape of the spherical portion 100e is a hemisphere that protrudes from the end portion 100be of the body portion 100b toward the base 130. The diameter of the spherical portion 100e decreases as it moves away from the body portion 100b.

[0024] The reinforcing layer 120 covering the body 100b is also referred to as the "outer layer." Furthermore, in the outer layer, the fiber reinforced resin layer 121 composed of multiple layers of fiber bundles is also referred to as the "lower layer," and the resin layer 122 overlapping the lower layer and including the flow media 140 is also referred to as the "upper layer."

[0025] The fiber layer P121 will be described. The fiber layer P121 is the fiber-reinforced resin layer 121 before being impregnated with resin, and is composed of fiber bundles of carbon fibers. The fiber bundles are formed by winding multiple layers of the fiber bundles, for example, by helical winding and hoop winding, so as to cover the outer surface 110o of the liner 110. The "fiber bundles" referred to here refer to an assembly of fibers in which a large number of single fibers with a diameter of about several micrometers are bundled together. The fiber layer P121 is impregnated with a thermosetting resin, and then thermally cured to form the fiber-reinforced resin layer 121.

[0026] "Helical winding" refers to a method of winding a fiber bundle around the liner 110 such that the winding angle of the fiber bundle with respect to the central axis O is greater than 0 degrees and less than 90 degrees. In the helical winding, for example, the fiber bundle is wound from one spherical portion 100e of the liner 110 through the trunk portion 100b to the other spherical portion 100e. In addition, "hoop winding" refers to a method of winding a fiber bundle around the liner 110 such that the winding angle of the fiber bundle with respect to the central axis O is approximately 90 degrees. In the hoop winding, the fiber bundle is wound around the trunk portion 100b while moving the winding position parallel to the central axis O. That is, the innermost layer P121i of the fiber layer P121 and the outer surface 110o of the liner 110 are in contact with each other. The outermost layer P121o of the fiber layer P121 forms the outer surface of the preform P100. For this reason, in this specification, the outermost layer P121o of the fiber layer P121 is also referred to as the outer surface P121o of the preform P100.

[0027] That is, the preform P100 has multiple layers of fiber bundles wound around the outer surface 110o of the liner 110 that defines the interior space 110p of the tank 100.

[0028] In addition, due to the formation of the fiber layer P121, the outer diameter P100r of the preform P100 in the radial direction CD may vary at each portion of the preform P100 in the axial direction OD. As a result, when the preform P100 is placed in the mold 21 described later, the gap S2 between the preform P100 and the mold 21 varies. The gap S2 will be described later.

[0029] A-2. About Flow Media: The flow medium 140 is provided in the preform P100 to function as a flow path for the resin. As described above, the flow medium 140 is a sheet made of three-dimensional mesh-like fibers. More specifically, the flow medium 140 is a sheet formed in a mesh shape by weaving fibers made of, for example, nylon as a resin.

[0030] 3 is a plan view showing a preform P100 around which a flow medium 140 is wound. The flow medium 140 is wound around the preform P100 in a winding step S110 in the manufacture of the tank 100, which will be described later. More specifically, the flow medium 140 is wound around the entire body portion 100b. The flow medium 140 in FIGS. 1 to 3 is shown in a state in which it is wound around the body portion 100b of the preform P100. Therefore, the flow medium 140 is impregnated with resin together with the preform P100, and is disposed inside the resin layer 122, as in the tank 100 shown in FIG. 1.

[0031] 4 is a plan view showing the structure of the flow medium 140. More specifically, the flow medium 140 is wound around the outer surface P121o of the preform P100 multiple times along the circumferential direction LD of the body portion 100b of the preform P100. That is, the flow medium 140 spreads in a direction perpendicular to the radial direction CD. FIG. 4 shows the structure of the flow medium 140 as it can be seen when looking at the flow medium 140 from the outside of the preform P100 along the radial direction CD.

[0032] The flow medium 140 is composed of first fibers 140OD extending in the axial direction OD and second fibers 140LD extending in the circumferential direction LD. More specifically, the flow medium 140 is formed by weaving the first fibers 140OD and the second fibers 140LD while providing a gap between adjacent fibers facing the same direction. Therefore, the flow medium 140 is defined with a void S1 penetrating in the radial direction CD. The gap between adjacent fibers of the flow medium 140 is wider than the gap between the carbon fibers of the fiber layer P121 of the preform P100.

[0033] FIG. 5 is a cross-sectional view showing the VV cross section of FIG. 4. In FIG. 5, the mold 21 described later and the fiber layer P121 of the preform P100 are shown to facilitate understanding of the technology. As shown in FIG. 5, the fibers are woven to define a gap S1 when the cross section of the flow medium 140 is viewed along the circumferential direction LD. As shown in FIG. 4, the first fiber 140OD and the second fiber 140LD intersect at an angle of 90 degrees. Therefore, the gap S1 is also defined when the cross section of the flow medium 140 is viewed along the axial direction OD. The preform P100 is placed in the mold 21 with the flow medium 140 wound around it. Therefore, the preform P100 with the flow medium 140 wound around it has a gap S1 between the mold 21 and the fiber layer P121 even when the flow medium 140 comes into contact with the mold 21.

[0034] Therefore, the preform P100 around which the flow medium 140 is wound has voids S1 extending in the circumferential direction LD, the axial direction OD, and the radial direction CD on the outer surface P121o of the preform P100. That is, the preform P100 around which the flow medium 140 is wound has voids S1 extending in a direction different from the direction in which the fibers of the fiber bundle extend on the outer surface P121o. With this configuration, the flow medium 140 overlaps the fiber bundle of the preform P100, and functions as a flow path for the resin between the mold 21 and the fiber bundle in the impregnation step S150 of the tank 100 described later. Therefore, the resin easily flows between the mold 21 and the fiber bundle, and the fiber bundle is less likely to be left unimpregnated.

[0035] Moreover, the flow media 140 can reduce warping of the tank 100. The resin layer 122 may have a biased thickness due to stagnation of the flow of the resin. For example, in FIG. 1, when the resin layer 122 on the -Y direction side is thicker than the resin layer 122 on the +Y direction side, the resin hardens and the resin layer 122 on the -Y direction side shrinks significantly. For this reason, the tank 100 may have a warp with the -Y direction side facing inward. The flow media 140 can reduce warping of the tank 100 by preventing the thickness of the resin layer 122 from being biased. That is, the flow media 140 reduces the bias of the resin layer 122, making it easier to form a thinner resin layer 122 than in a configuration without the flow media 140.

[0036] A-3. Tank manufacturing equipment configuration: FIG. 6 is a diagram showing a schematic configuration of a manufacturing apparatus 2 for the tank 100. FIG. 6 shows a state in which the preform P100 is arranged in a mold 21. The manufacturing apparatus 2 is an apparatus for manufacturing the tank 100 of FIG. 1 from the preform P100 of FIG. 2 by the RTM method. Specifically, the manufacturing apparatus 2 impregnates the fiber layer P121 of the preform P100 with a resin by the RTM method, and then hardens the resin to manufacture the tank 100 in which the reinforcing layer 120 is formed on the outer periphery side of the liner 110. In this embodiment, a thermosetting resin is used to form the reinforcing layer 120.

[0037] The manufacturing apparatus 2 includes a mold 21, a support mechanism 22, a temperature control device 23, a vacuum pump 24, a resin reservoir 25, a pressurizing device 26, a valve 27, a control device 28, a drive mechanism 29, and an ejector pin 30. The ejector pin 30 is illustrated in Figs. 7 and 8, which will be described later.

[0038] The support mechanism 22 supports the preform P100 from both ends where the die 130 is located when the preform P100 is in an arranged state.

[0039] The temperature adjustment device 23 controls the temperature of the mold 21. The temperature adjustment device 23 is illustrated in the center left side of Fig. 6. In response to a command from the control device 28, the temperature adjustment device 23 sets the temperature of the mold 21 to a temperature lower than the curing temperature of the resin, for example, until the impregnation of the fiber layer P121 with the resin is completed. Then, after the impregnation of the fiber layer P121 with the resin is completed, the temperature adjustment device 23 sets the temperature of the mold 21 to a temperature equal to or higher than the curing temperature of the resin.

[0040] The vacuum pump 24 is a degassing device for degassing the placement chamber 210 by creating a vacuum in the placement state of the preform P100 and the mold clamping state of the die 21. The vacuum pump 24 is illustrated in the lower left part of Fig. 6. The placement state and the mold clamping state will be described later.

[0041] The resin reservoir 25 is a reservoir that stores the resin to be supplied to the placement chamber 210. The resin reservoir 25 is illustrated in the upper right portion of Fig. 6. The resin reservoir 25 is connected to the second mold pipe portion 212c via a valve 27. The resin reservoir 25 is also connected to a pressurizing device 26.

[0042] The pressurizing device 26 pressurizes the resin stored in the resin reservoir 25, thereby causing the resin to flow from the resin reservoir 25 to the placement chamber 210. The pressurizing device 26 is illustrated in the upper right part of Fig. 6. The pressurizing device 26 is disposed upstream of the resin reservoir 25 in the flow direction indicated by the arrow.

[0043] The valve 27 is an opening / closing valve for switching between a flow state in which the resin flows from the resin reservoir 25 to the second mold pipe portion 212c and a non-flow state in which the resin does not flow from the resin reservoir 25 to the second mold pipe portion 212c. The valve 27 is illustrated in the center left of Fig. 6. The valve 27 is disposed downstream of the resin reservoir 25 in the flow direction indicated by the arrow. The opening and closing of the valve 27 is controlled by a control device 28.

[0044] The drive mechanism 29 is a device that moves the first mold 211 and the second mold 212. The drive mechanism 29 is illustrated in the upper center of FIG. 6. The drive mechanism 29 is a lifting device that lifts and lowers the first mold 211 and the second mold 212 to open and close the mold 21. When closing the mold 21, the drive mechanism 29 moves the second mold 212 and the first mold 211 closer to each other in the Y direction in response to a command from the control device 28. When releasing the mold, the drive mechanism 29 moves the second mold 212 and the first mold 211 away from each other in the Y direction in response to a command from the control device 28. In this specification, "mold clamping" refers to closing the mold 21.

[0045] The control device 28 controls the manufacturing apparatus 2. The control device 28 includes a processor, a ROM, and a RAM (not shown) and performs processing required for controlling each component of the manufacturing apparatus 2. In Fig. 6, the electrical connections of each component of the manufacturing apparatus 2 that is electrically connected to and controlled by the control device 28 are diagrammatically illustrated by dashed lines.

[0046] The mold 21 includes a pair of a first die 211 and a second die 212, and a placement chamber 210 in which the preform P100 is placed.

[0047] The first die 211 and the second die 212 face each other. The first die 211 is disposed on the −Y direction side of the second die 212 in the direction of gravity.

[0048] The first mold 211 has a first mold facing wall 211a, a first mold recess 211b, a first mold tube portion 211c, and a first gate 211d. The first mold facing wall 211a is a wall surface facing the second mold 212. The first mold recess 211b is a recess in which a part of the first mold facing wall 211a is recessed inwardly of the first mold 211. The first mold recess 211b has a first mold bottom surface 211bb and a first mold connection surface 211be, and has a shape in which the +Y direction side where the second mold 212 is located is open. The first mold connection surface 211be is located on both ends of the first mold bottom surface 211bb. The first mold tube portion 211c is a gas flow path formed inside the first mold 211 to degas the placement chamber 210 by the vacuum pump 24. The first gate 211d is an opening formed in the first mold bottom surface 211bb of the first mold recess 211b. That is, degassing is performed by the vacuum pump 24 from the first gate 211d through the first mold pipe portion 211c.

[0049] The second mold 212 has a second mold opposing wall 212a, a second mold recess 212b, a second mold tube portion 212c, and a second gate 212d. The second mold opposing wall 212a is a wall surface facing the first mold opposing wall 211a. The second mold recess 212b is a recess in which a part of the second mold opposing wall 212a is recessed inwardly of the second mold 212. The second mold recess 212b has a second mold top surface 212bb and a second mold connection surface 212be, and is shaped so that the -Y direction side where the first mold 211 is located is open. The second type connection surfaces 212be are located on both end sides of the second mold top surface 212bb. That is, the inner surface 21a of the mold 21 is formed by the first mold bottom surface 211bb and the first mold connection surface 211be of the first mold recess 211b, and the second mold top surface 212bb and the second mold connection surface 212be of the second mold recess 212b. The second mold pipe portion 212c is a flow path formed inside the second mold 212 to allow the resin supplied from the resin reservoir 25 to flow to the placement chamber 210. The second gate 212d is an opening formed in the second mold top surface 212bb of the second mold recess 212b. That is, the second mold pipe portion 212c communicates the valve 27 and the resin reservoir 25 side with the placement chamber 210 side via the second gate 212d. In FIG. 6, the direction in which the resin flows is indicated by an arrow.

[0050] The placement chamber 210 is a space for placing the preform P100 between the first mold 211 and the second mold 212. The placement chamber 210 is an internal space 110p of the mold 21 defined by the first mold recess 211b and the second mold recess 212b when the first mold 211 and the second mold 212 are clamped together. The clamped state is referred to as a clamped state. That is, the placement chamber 210 is defined within the mold 21 when the mold 21 is clamped.

[0051] More specifically, the placement chamber 210 is an internal space 110p that is larger than the outer shape of the preform P100 and matches the outer shape of the tank 100. As described above, the preform P100 is supported at both ends by the support mechanism 22. For this reason, the above-mentioned gap S2 is generated between the preform P100 placed in the placement chamber 210 and the inner surface 21a of the placement chamber 210.

[0052] The first mold recess 211b and the second mold recess 212b are each formed to have a shape that matches the shape of the preform P100. Specifically, the mold 21 includes a cylindrical mold body 210b and two mold spherical portions 210e that are provided on both ends of the mold body 210b and have shapes that decrease with increasing distance from the mold body 210b.

[0053] The mold body 210b accommodates the body 100b of the preform P100. The mold body 210b is a portion of the mold 21 that includes the first mold bottom surface 211bb and the second mold top surface 212bb. Therefore, when the preform P100 is placed in the placement chamber 210 and the mold 21 is in a clamped state, both the first mold bottom surface 211bb and the second mold top surface 212bb face the body 100b of the preform P100. The state in which the preform P100 is placed in the placement chamber 210 is referred to as the placement state.

[0054] The mold spherical portion 210e accommodates the spherical portion 100e of the preform P100. The mold spherical portion 210e is a portion of the mold 21 that includes the first mold connection surface 211be and the second mold connection surface 212be. Therefore, when the preform P100 is arranged and the mold 21 is clamped, both the first mold connection surface 211be and the second mold connection surface 212be face the spherical portion 100e of the preform P100.

[0055] Fig. 7 is an explanatory diagram showing the ejector pin 30. Fig. 7 shows the arrangement state of the preform P100 and the clamped state of the mold 21. The ejector pin 30 separates the tank 100 adhered to the mold 21 from the mold 21. The ejector pin 30 is a cylindrical pin provided inside each of the first mold 211 and the second mold 212.

[0056] Fig. 8 is a cross-sectional view showing a cross section taken along line VIII-VIII in Fig. 7. When the mold 21 is in a clamped state, the ejector pin 30 is arranged so that the surface of one end is aligned with the first mold bottom surface 211bb or the second mold top surface 212bb. The other end is supported outside the mold 21 (not shown), and does not move even when the first mold 211 and the second mold 212 are raised and lowered by the drive mechanism 29.

[0057] As shown in Figures 7 and 8, a gap S2 exists between the preform P100 and the inner surface 21a of the mold 21. In order to impregnate the preform P100 with resin, a resin layer 122 is formed in the tank 100 up to the inner surface 21a of the mold 21 so as to fill the gap S2 by a manufacturing method described later. At this time, the resin layer 122 is in a state of being adhered to the inner surface 21a of the mold 21. Even when the first mold 211 and the second mold 212 are raised and lowered due to demolding, the ejector pin 30 stops at the inner surface 21a of the mold 21, and thus the tank 100 adhered to the inner surface 21a of the mold 21 is separated from the inner surface 21a.

[0058] As described above, the gap S2 is not constant due to variations in the outer diameter P100r of the preform P100. For this reason, the body portion 100b on which the flow medium 140 is provided may come into contact with the inner surface 21a of the mold 21. When the flow medium 140 comes into contact with the inner surface 21a, the preform P100 receives a load in the Y direction toward the preform P100 due to the clamping of the mold 21.

[0059] A-4. Tank manufacturing method: 9 is a flowchart showing a manufacturing method of the tank 100. The manufacturing of the tank 100 starts in step S100 with an operator preparing materials necessary for the tank 100. In the following description, each process will be named with a step number.

[0060] 9, an operator prepares a preform P100, a mold 21, and a flow medium 140. After the preparation step S100, a winding step S110 is performed.

[0061] In the winding step S110 shown in FIG. 9, the worker winds the flow medium 140 around the outer surface P121o of the preform P100 shown in FIG. 2 in the circumferential direction LD of the body 100b of the preform P100. The worker determines the number of turns of the flow medium 140 according to the variation in the outer diameter P100r of the preform P100 so that the outer diameter of the preform P100 including the flow medium 140 fits within the space of the placement chamber 210. The worker fixes the wound flow medium 140 to the fiber layer P121 with a heat-resistant tape. This prevents the flow medium 140 from shifting during the manufacture of the tank 100. After the winding step S110, the placement step S120 is performed.

[0062] 9, an operator places the preform P100 in the placement chamber 210 of the metal mold 21, and clamps the first mold 211 and the second mold 212 by the manufacturing apparatus 2. That is, as shown in FIG 6, the first mold 211 and the second mold 212 are clamped, and the preform P100 is accommodated in the placement chamber 210. After the placement process S120, a deaeration process S130 is executed.

[0063] 9, the manufacturing apparatus 2 degass the placement chamber 210. Specifically, the vacuum pump 24 starts degassing in accordance with a command from the control device 28. Then, the vacuum pump 24 continues the degassing until the injection of the resin is completed in the injection step S140.

[0064] 9, the manufacturing apparatus 2 injects the resin stored in the resin reservoir 25 into the placement chamber 210 in order to impregnate the fiber layer P121 of the preform P100 with the resin. Specifically, the valve 27 is opened and the pressurizing device 26 starts pressurizing the resin reservoir 25 in accordance with a command from the control device 28. This causes the resin to flow through the second mold pipe 212c provided in the second mold 212, and the resin is injected from the second gate 212d toward the preform P100. At this time, the temperature of the mold 21 is adjusted by the temperature adjustment device 23 so that the temperature of the mold 21 is lower than the curing temperature of the resin.

[0065] In the injection step S140, the manufacturing apparatus 2 injects resin into the mold 21 in a state in which the preform P100 wrapped with the flow medium 140 is placed in the mold 21. More specifically, the manufacturing apparatus 2 injects resin up to the flow medium 140 by filling the resin up to the inner surface 21a of the mold 21. In other words, the gap S2 between the preform P100 and the mold 21 is filled with resin. After the injection step S140, the impregnation step S150 is performed.

[0066] In the impregnation step S150 shown in FIG. 9, the manufacturing apparatus 2 impregnates the flow media 140 and the fiber bundle forming the fiber layer P121 of the preform P100 with resin. The resin injected toward the preform P100 by the impregnation step S150 flows through the gap S2 between the preform P100 and the inner surface 21a of the mold 21. Furthermore, in the body portion 100b, the resin is impregnated toward the circumferential direction LD, the axial direction OD, and the radial direction CD through the gap S1 of the flow media 140. Therefore, even if the gap S2 is small, the resin can spread throughout the body portion 100b through the flow media 140 shown in FIG. 2. Furthermore, the resin is impregnated from the outermost layer P121o side of the fiber layer P121 toward the innermost layer P121i side. As a result, the fiber reinforced resin layer 121 is formed through the subsequent curing step S160. It should be noted that a part of the impregnation step S150 is performed in parallel with the injection step S140 at a time point after the injection step S140 is started.

[0067] In the impregnation step S150, a part of the resin is impregnated into the fiber layer P121, while the remaining resin flows through the gap S2 between the preform P100 and the inner surface 21a of the mold 21. Therefore, in the subsequent curing step S160, the resin that has not been impregnated into the fiber layer P121 is cured on the outside of the fiber reinforced resin layer 121. More specifically, as shown in FIG. 1, a resin layer 122 made of resin that does not contain fiber bundles is formed on the outside of the fiber reinforced resin layer 121 in the radial direction CD. That is, in the body portion 100b, a resin layer 122 containing the flow media 140 is formed, and a resin layer is formed on the flow media 140. After the impregnation step S150, the curing step S160 is performed.

[0068] In the curing step S160 shown in FIG. 9, the manufacturing apparatus 2 cures the resin impregnated into the fiber bundle. In this embodiment, a thermosetting resin is used as the resin forming the reinforcing layer 120. Therefore, in the curing step S160, the manufacturing apparatus 2 cures the resin by heating. Specifically, the temperature adjustment device 23 adjusts the temperature of the mold 21 to be equal to or higher than the curing temperature of the resin. This cures the resin to form the fiber reinforced resin layer 121. After the curing step S160, the demolding step S170 is performed.

[0069] In the demolding step S170 shown in FIG. 9, the manufacturing device 2 demolds the tank 100 from the mold 21 by releasing the first mold 211 and the second mold 212. Specifically, the driving mechanism 29 lowers the first mold 211 in the -Y direction from the second mold 212 and raises the second mold 212 in the +Y direction from the first mold 211 in accordance with a command from the control device 28. As a result, only the ejector pin 30 is in contact with the tank 100. After the curing step S160, the tank 100 is attached to the inner surface 21a, so it is pulled to both sides in the Y-axis direction by the demolding. In the demolding step S170, the ejector pin 30 remains at the position of the inner surface 21a of the mold 21 in the curing step S160, so that the tank 100 is released from the inner surface 21a. 1 becomes removable from the metal mold 21. By performing each process up to the demolding process S170 shown in FIG. 8, the production of the tank 100 is completed.

[0070] FIG. 10 is a graph showing the variation of the outer diameter 100r of the tank 100. FIG. 10 shows the variation of the outer diameter 100r of the tank 100 manufactured under different conditions for the flow medium 140. The outer diameter 100r of the tank 100 is the outer diameter 100r in the radial direction CD of the body 100b as shown in FIG. 1. The variation of the outer diameter 100r represents the difference between the design value and the measured value of the outer diameter 100r for each condition. FIG. 10 shows the average value, maximum value, and minimum value of the outer diameter 100r measured at multiple points on the body 100b. The conditions of the tank 100 are divided into condition A, in which the flow medium 140 is not wound around the body 100b, condition B, in which the flow medium 140 is wound around the entire body 100b, and condition C, in which the flow medium 140 is wound around a part of the body 100b. The tank 100 used in the embodiment of Figure 10, when described with reference to Figure 3, has a total length 100s of 1270 mm and a body portion 100b of 800 mm. The width of the flow medium 140 in condition A is 800 mm, the same as that of the body portion 100b. The width of the flow medium 140 in condition B is 100 mm, which is shorter than that of the body portion 100b.

[0071] 10, the fluctuation of the outer diameter 100r is reduced by wrapping the flow media 140. In other words, unevenness in the thickness of the resin layer 122 and warping of the tank 100 caused by stagnation of the resin flow are reduced by the flow media 140. A comparison between conditions B and C will be described in B. Other embodiments.

[0072] As described above, by adopting such a configuration, in the impregnation step S150, the resin is impregnated through the flow media 140 and the fiber bundle. The flow media 140 overlaps the fiber bundle, and functions as a flow path for the resin between the mold 21 and the fiber bundle. More specifically, the flow media 140 defines a gap S1 extending in a direction different from the fiber bundle between the preform P100. Therefore, the resin is easily allowed to flow between the mold 21 and the fiber bundle, and the fiber bundle is less likely to have an unimpregnated portion. Furthermore, since the manufacturing method of the tank 100 of the present disclosure does not require a special mold structure, the impregnation can be easily performed even with an existing mold structure. That is, the manufacturing method of the tank 100 of the present disclosure can manufacture the tank 100 while ensuring the quality of the tank 100 by using the same mold 21 as in the past. Therefore, the manufacturing method of the tank 100 of the present disclosure can achieve both sufficient impregnation of the resin and ensuring the quality of the tank 100.

[0073] In the manufacturing method of the tank 100 of the present disclosure, by using the flow media 140, the resistance when releasing the tank 100 from the mold 21 can be made the same as that when the flow media 140 is not used. Therefore, for example, the strength of the resin layer 122 against the load of the ejector pin 30 and the strength against scratches on the surface of the resin layer 122 are not deteriorated.

[0074] Furthermore, by using flow media 140, uneven thickness of resin layer 122 and warping of tank 100 caused by stagnation of the flow of resin are reduced. By reducing unevenness of resin layer 122, it becomes easier to form a thin resin layer 122 compared to a configuration in which flow media 140 is not provided.

[0075] Furthermore, in the winding step S110, the flow media 140 is wound around the entire body 100b. With this configuration, when the flow media 140 comes into contact with the mold 21, the load caused by the clamping of the mold 21 is unlikely to concentrate on a part of the body 100b. For example, when the flow media 140 is wound around a part of the body 100b, the load caused by the clamping of the mold 21 is likely to concentrate on a part of the body 100b. For this reason, in the impregnation step S150, an unimpregnated portion may occur. By wrapping the sheet around the entire body 100b, the load caused by the clamping of the mold 21 is distributed over the entire body 100b. Therefore, the manufacturing method of the tank 100 of the present disclosure can reduce the possibility of an unimpregnated portion occurring in the body 100b.

[0076] Moreover, the impregnation step S150 includes a step of forming a resin layer on the flow media 140. By adopting such a configuration, the manufacturing method of the tank 100 of the present disclosure can protect the body portion 100b by covering the entire body portion 100b with a resin layer.

[0077] Furthermore, in the winding step S110, the winding of the flow medium 140 is performed multiple times. As described above, the outer diameter P100r of the preform P100 varies depending on the precision of winding the fiber bundle. By adopting such a configuration, the manufacturing method of the tank 100 of the present disclosure can easily adjust the outer diameter of the preform P100 including the flow medium 140 to match the size of the mold 21 by adjusting the number of turns of the flow medium 140. Therefore, the manufacturing method of the tank 100 of the present disclosure can more appropriately impregnate the resin.

[0078] B. Other embodiments: In the above embodiment, the flow medium 140 is wound around the entire body portion 100b of the preform P100, but it may be wound around a part of the body portion 100b. For example, the flow medium 140 may be wound around only the center portion in the axial direction OD inside the body portion 100b. That is, the flow medium 140 only needs to be wound around at least a part of the body portion 100b.

[0079] FIG. 10 shows the result of condition C as the deviation of the outer diameter 100r of the tank 100 when the flow media 140 is wrapped around only a part of the body 100b. Condition C has a larger deviation compared to condition B, but a smaller average value and deviation compared to condition A. Therefore, the tank manufacturing method of the present disclosure allows the flow media 140 to easily impregnate the resin compared to a configuration in which the flow media 140 is not provided. Furthermore, the manufacturing method of the tank 100 of the present disclosure allows the amount of flow media 140 to be reduced compared to a configuration in which the flow media 140 is wrapped around the entire body 100b as in the first embodiment, thereby reducing the cost required for manufacturing the tank 100.

[0080] C. Other embodiments: (1) In the above embodiment, the flow medium 140 is a sheet formed in a mesh shape and is composed of first fibers 140OD extending in the axial direction OD and second fibers 140LD extending in the circumferential direction LD. However, the direction in which the first fibers 140OD extend may be inclined with respect to the central axis O. In this case, the flow medium 140 is formed in a mesh shape by the second fibers 140LD extending in a direction perpendicular to the direction in which the first fibers 140OD extend. (2) In the above embodiment, the flow medium 140 is a sheet formed in a mesh shape. However, the flow medium 140 may be a sheet composed of three-dimensional mesh-like fibers. For example, the flow medium 140 may have a structure in which the fibers extend irregularly, rather than a structure in which the fibers extend regularly, such as a mesh. (3) In the above embodiment, the flow medium 140 is wound around the preform P100 multiple times. However, the flow medium 140 may be wound around the preform P100 only one turn. It is sufficient that the flow medium 140 is wound around the preform P100 one or more turns. (4) In the above embodiment, the impregnation step S150 forms a resin layer on the flow medium 140. However, the impregnation step S150 may be formed to coincide with the surface of the flow medium 140 facing the outside of the tank 100. (5) In the above embodiment, the material of the fiber bundle of the fiber layer P121 is carbon fiber. The material of the fiber bundle of the fiber layer P121 is not limited to carbon fiber. For example, the material of the fiber bundle of the fiber layer P121 may be glass fiber, or a combination of glass fiber and carbon fiber. (6) In the above embodiment, nylon is used as the material of the fibers constituting the flow medium 140. However, the material of the fibers constituting the flow medium 140 is not limited to nylon. The material constituting the flow medium 140 may be, for example, glass fiber.

[0081] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above problems or to achieve some or all of the above effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0082] 2... manufacturing device, 21... tank manufacturing mold, 21a... inner surface, 22... support mechanism, 23... temperature control device, 24... vacuum pump, 26... pressure device, 27... valve, 28... control device, 29... drive mechanism, 30... ejector pin, 100... tank, 100b... body, 100be... end, 100e... spherical portion, 100r... outer diameter, 100s... total length, 110... liner, 110o... outer surface, 110p... internal space, 120... reinforcement layer, 121... fiber reinforced resin layer, 121o... outer surface, 122... resin layer, 130... nozzle, 140... flow media, 140LD... second fiber, 140OD... first fiber, 210... placement chamber, 210b... mold body, 21 0e...spherical portion of mold, 211...first mold, 211a...first mold opposing wall, 211b...first mold recess, 211bb...first mold bottom surface, 211be...first mold connection surface, 211c...first mold tube portion, 211d...first gate, 212a...second mold opposing wall, 212...second mold, 212c...second mold tube portion, 212b...second mold recess, 212be...second mold connection surface, 212bb...second mold top surface, 212d...second gate, A,B,C...conditions, CD...radial direction, LD...circumferential direction, O...center axis, OD...axial direction, P100...preform, P100o...outer surface, P100r...outer diameter, P121...fiber layer, P121i...innermost layer, P121o...outermost layer, S1...void, S2...gap

Claims

1. A method for manufacturing a tank, comprising the steps of: A preparation process for preparing a preform having a cylindrical body, the preform being formed by winding a plurality of layers of fiber bundles around an outer surface of a liner that defines an internal space of the tank, a mold, and a sheet made of three-dimensional mesh-like fibers; a winding step of winding the sheet around an outer surface of the preform in a circumferential direction of the body portion for one or more revolutions; an injection step of injecting a resin into the mold in a state in which the preform around which the sheet is wrapped is placed in the mold; an impregnation step of impregnating the sheet and the fiber bundle with the resin, In the winding step, The sheet is wrapped around at least a portion of the body portion, A method for manufacturing a tank, wherein the preform around which the sheet is wrapped has voids on the outer surface of the preform that extend in a direction different from the direction in which the fibers of the fiber bundle extend.

2. A method for manufacturing the tank according to claim 1, comprising the steps of: A method for manufacturing a tank, wherein in the winding step, the sheet is wrapped around the entire body portion.

3. A method for manufacturing the tank according to claim 2, comprising the steps of: The method for manufacturing a tank, wherein the impregnation step includes a step of forming a layer of the resin on the sheet.

4. A method for manufacturing the tank according to claim 3, comprising the steps of: A method for manufacturing a tank, wherein in the winding step, the sheet is wound a plurality of times.

5. A hydrogen tank, It has a cylindrical body, the hydrogen tank includes an outer layer including a resin and covering the body portion; The outer layer is A lower layer composed of a plurality of layers of fiber bundles; An upper layer including a sheet configured in a three-dimensional mesh shape and overlapping the lower layer; A hydrogen tank, wherein the sheet has voids extending in a direction different from the direction in which the fibers of the fiber bundles extend.

Images