Manufacturing method for high-pressure tanks

Abstract

To make it possible to suppress an occurrence of a low strength part when laminating low helical layers having different winding angles for each layer.SOLUTION: A fiber reinforced plastic layer is formed by winding fiber tows 30 impregnated with a binder resin around a liner 20. The fiber reinforced plastic layer includes a low helical layer. In this manufacturing method, when forming a plurality of low helical layers, a winding angle θ of the fiber tows 30 is made different for each layer. Furthermore, in this manufacturing method, a switching point position of the winding angle on the liner 20, which is a winding end point {L(s),Pe(k-1)} of a given low helical layer and a winding start point {L(s+1),Ps(1)} of a next low helical layer, is made different for each low helical layer.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This specification discloses a method for manufacturing a high-pressure tank.

Background Art

[0002] A high-pressure tank has a multi-layer structure. For example, as disclosed in Patent Documents 1-3, a high-pressure tank includes a liner and a fiber-reinforced plastic layer.

[0003] The liner is the innermost component of the high-pressure tank. The liner includes a cylindrical part that is the central component and a pair of dome parts connected to both ends of the cylindrical part in the central axis direction. A fluid such as hydrogen gas is enclosed in the liner.

[0004] A fiber-reinforced plastic layer is laminated on the liner. The fiber-reinforced plastic layer is formed, for example, by winding fiber tow, which is a fiber bundle, around the liner.

[0005] Regarding the means of winding the fiber tow around the liner, so-called low-angle helical winding is performed. In low-angle helical winding, the winding angle of the fiber tow is set to an angle close to parallel to the central axis of the liner. The layer of fiber-reinforced plastic wound by low-angle helical winding is also called a low-helical layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] Incidentally, low-helical layers can sometimes be formed across multiple layers. In such cases, the multilayer low-helical layers are configured such that the winding angle of the fiber tow differs in each layer.

[0008] For example, as illustrated in Figure 5, in a predetermined layer of the low-helical layer, the fiber tow 102 is wound around the liner 100 at a winding angle θ101. In the layer above that, the fiber tow 102 is wound around the liner 100 at a winding angle θ102 (≠θ101). In the layer further above that, the fiber tow 102 is wound around the liner 100 at a winding angle θ103 (≠θ102).

[0009] When the winding angle is changed, if the fiber tow 102 is changed from the winding angle θ101 to θ102, the fiber tow 102 slides upward in the upper part of Figure 5 at the switching point P100. In other words, the fiber tow 102 near the switching point P100 moves away from the position where it was originally intended to be wound. Similarly, as shown in the middle and lower parts of Figure 5, slippage (displacement) of the fiber tow 102 occurs at the switching point P100 in other layers as well. Because the slippage of the fiber tow 102 at the switching point P100 occurs across other layers, the strength of the switching point P10 may be lower than that of other parts.

[0010] Therefore, this specification discloses a method for manufacturing a high-pressure tank that can suppress the occurrence of low-strength areas when stacking low-helical layers with different winding angles for each layer. [Means for solving the problem]

[0011] This specification discloses a method for manufacturing a high-pressure tank. This manufacturing method includes a step of forming a liner and a lamination step. The liner comprises a cylindrical portion and a pair of dome portions provided at both ends of the cylindrical portion in the axial direction. In the lamination step, a fiber-reinforced plastic layer is formed on the liner. In the lamination step, a fiber-reinforced plastic layer is formed by winding a fiber tow impregnated with a binder resin around the liner. The fiber-reinforced plastic layer includes a low-helical layer. The low-helical layer is formed by winding the fiber tow around the liner multiple times in a low-angle helical winding, where the winding angle with respect to the liner's central axis is acute. Multiple low-helical layers are formed in the fiber-reinforced plastic layer. In this manufacturing method, when forming multiple low-helical layers, the winding angle of the fiber tow is made different for each layer. Furthermore, in this manufacturing method, the position of the switching point of the winding angle on the liner, which is the winding end point of a predetermined low-helical layer and the winding start point of the next low-helical layer, is made different for each low-helical layer.

[0012] According to the above configuration, the switching point position of the fiber tow winding angle differs in each layer of the low-helical layer. By dispersing the switching point position on the liner, it is possible to suppress the occurrence of low-strength regions where the fiber tow is excessively thin compared to the surrounding area. [Effects of the Invention]

[0013] According to the method for manufacturing a high-pressure tank disclosed herein, when stacking low-helical layers with different winding angles for each layer, the occurrence of low-strength areas can be suppressed. [Brief explanation of the drawing]

[0014] [Figure 1] This is a front view illustrating the configuration of a high-pressure tank manufactured by the manufacturing method according to this embodiment. [Figure 2] This diagram illustrates the filament winding process, which is part of the manufacturing process for high-pressure tanks. [Figure 3] This is a perspective view explaining the definition of a circuit in low-angle helical winding. [Figure 4] This is a diagram for explaining the process of laminating a plurality of low helical layers by the manufacturing method according to the present embodiment. [Figure 5] This is a diagram for explaining the process of laminating a plurality of low helical layers by the manufacturing method according to the prior art.

Mode for Carrying Out the Invention

[0015] Hereinafter, a method for manufacturing a high-pressure tank according to an embodiment will be described with reference to the drawings. The shapes, materials, numbers, and numerical values described below are examples for explanation and can be appropriately changed according to the specifications of the high-pressure tank. Also, in all the drawings below, the same reference numerals are assigned to equivalent elements.

[0016] FIG. 1 illustrates a high-pressure tank 10 which is the object of manufacture by the manufacturing method according to the present embodiment. For example, the high-pressure tank 10 is a hydrogen tank in which hydrogen gas is enclosed. For example, the high-pressure tank 10 is mounted on a fuel cell electric vehicle (FCEV).

[0017] The manufacturing method of the high-pressure tank 10 according to the present embodiment includes a liner forming step, a filament winding step, and an inspection step. In the liner forming step, a liner 20 is formed from a plurality of parts. In the filament winding step, a fiber reinforced plastic is laminated on the liner 20. The filament winding step is also called a lamination step. Further, in the inspection step, a hydraulic test and a leak test are performed on the high-pressure tank 10.

[0018] The high-pressure tank 10 has a laminated structure. For example, the high-pressure tank 10 includes a liner 20 and a fiber reinforced plastic layer.

[0019] The liner 20 is a hollow body in which hydrogen gas is enclosed. The liner 20 includes a cylindrical portion 22 and dome portions 24, 26. A pair of dome portions 24, 26 are arranged at both ends in the direction of the central axis C1 of the cylindrical portion 22. For example, in the liner forming process, the dome portions 24, 26 and the cylindrical portion 22 are welded.

[0020] The liner 20 is required to have gas barrier properties. For this reason, the liner 20 is made of a resin material such as a nylon-based resin. Also, bases 25, 27 are attached to both ends of the dome portions 24, 26 along the central axis C1.

[0021] The fiber reinforced plastic layer is laminated on the liner 20. The fiber reinforced plastic layer is formed by winding a so-called towpreg (also called a tow prepregg), in which a binder resin is impregnated into fiber tows that are bundles of fibers.

[0022] The fibers of the towpreg are made of fiber reinforced plastic (FRP). For example, carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP) is used as the fibers of the towpreg.

[0023] The fiber reinforced plastic layer has a laminated structure. The laminated structure includes a plurality of low helical layers. The low helical layer is formed by winding fiber tow 30 on the liner 20 in a low angle helical winding.

[0024] The low angle helical winding refers to a winding mode in which the winding angle θ with respect to the central axis C1 of the liner 20 is an acute angle. For example, in the low angle helical winding, the winding angle θ is set to a winding angle of 10° or more and 80° or less.

[0025] FIG. 2 illustrates a filament winding process. In this process, fiber tow 30 is wound around the liner 20. The liner 20 is coupled to a motor 50 via a base 25. By the motor 50, the liner 20 is rotationally driven around the central axis C1.

[0026] Furthermore, the guide 52 is positioned radially away from the central axis C1 of the liner 20. The guide 52 functions as a creel (warping tool) for the fiber tow 30. That is, the fiber tow 30 impregnated with binder resin is supplied from the guide 52 and wound around the liner 20.

[0027] For example, the guide 52 is movable in the X-axis direction parallel to the central axis C1, in the Y-axis direction parallel to the radial direction of the liner 20, and in the Z-axis direction which is the height direction. For example, the guide 52 is equipped with an XYZ stage mechanism. Furthermore, the guide 52 is capable of twisting the fiber tow 30 being supplied. For example, the feeder (not shown) of the guide 52 is equipped with a servo motor that can rotate the feeder around the feed axis of the fiber tow 30.

[0028] Here, low-angle helical winding is controlled using a total of five parameters: the torsion angle φ of the fiber tow 30 during feeding, the movement axes X, Y, and Z of the guide 52, and the rotation angle α of the liner 20. For example, the winding control unit (not shown) of the filament winding device controls the rotation speed of the liner 20 and the movement speed of the guide 52 in the X-axis direction to wind the fiber tow 30 onto the liner 20 while keeping the winding angle θ constant.

[0029] In low-angle helical winding, the fiber tow 30 is wound multiple times on the liner 20 to form one layer of the low-helical layer. The parameter "circuit lap count" is used to indicate the number of windings in low-angle helical winding.

[0030] Referring to Figure 3, in low-angle helical winding, for example, when an arbitrary point on the cylindrical portion 22 is used as the winding starting point, the winding route is taken such that the fiber tow 30 is wound around one end cap 27, then moved again on the cylindrical portion 22, and the fiber tow 30 is wound around the other end cap 25.

[0031] Considering the periodicity of the winding, the number of circuit laps is determined as follows. In Figure 3, the winding start point Ps(k) of the s-th low helical layer L(s), i.e., the winding start point {L(s),Ps(k)}, is positioned on the liner 20.

[0032] The fiber tow 30 is wound onto the cylindrical portion 22 starting from the winding starting point {L(s), Ps(k)}. The fiber tow 30 is then wound around the nozzle 27. Using the nozzle 27 as a turning point, the fiber tow 30 is wound onto the cylindrical portion 22 again. The fiber tow 30 is then wound around the other nozzle 25. After that, the fiber tow 30 is wound onto the cylindrical portion 22.

[0033] In this winding process, the guide 52 (see Figure 2) moves in the direction of the central axis C1 and folds back when its axial position coincides with the nozzle 27. The guide 52 then moves further in the direction of the central axis C1 and folds back again when its axial position coincides with the nozzle 25. Finally, the guide 52's axial position coincides with the winding start point {L(s), Ps(k)}. At this point, the position of the fiber tow 30 becomes the winding end point {L(s), Pe(k)} of the k-th turn circuit.

[0034] Figure 3 shows a dashed control line CL indicating the positions of the winding start and end points. The control line CL is drawn on the liner 20 along the circumference of the cylindrical section 22, passing through the winding start point {L(s), Ps(k)}. The intersection of the fiber tow 30 returning from the nozzle 25 to the cylindrical section 22 and the control line CL becomes the winding end point {L(s), Pe(k)} of the kth circuit. This winding end point {L(s), Pe(k)} of the kth circuit becomes the winding start point {L(s), Ps(k+1)} of the next circuit k+1.

[0035] In the high-pressure tank 10 according to this embodiment, multiple low-helical layers are formed as a fiber-reinforced plastic layer. Furthermore, the multiple low-helical layers are set to have different winding angles θ of the fiber tow 30 for each layer.

[0036] As described above, if the switching point position of the winding angle θ is fixed in every layer, the switching point position may become a low-strength area where the fiber tow 30 layer is thinner than the surrounding area. Therefore, in the manufacturing method of the high-pressure tank according to this embodiment, winding is performed such that the switching point position of the winding angle θ on the liner 20 differs in each layer.

[0037] <Process for forming the low helical layer> Figure 4 illustrates the filament winding process, one of the manufacturing steps for the high-pressure tank 10 according to this embodiment. This process is also called the lamination process because it involves forming a fiber-reinforced plastic layer on the liner 20.

[0038] For example, the computer (not shown) of a filament winding apparatus includes a winding setting unit. The winding setting unit sets the winding path of the fiber tow 30 in each layer of the low helical layer. In setting the winding path, the so-called liner phase is intentionally shifted, as described below.

[0039] The upper part of Figure 4 illustrates the process of forming the first layer L(1) low helical layer on the liner 20. First, the starting point {L(1), Ps(1)} (not shown) for the first layer and the first turn of the circuit is set at an arbitrary position on the cylindrical portion 22.

[0040] The winding setting section is configured with the number of circuit laps for each layer of the multiple low-helical layers. Based on the number of circuit laps and the winding angle θ1 in the first layer, the winding setting section calculates the pitch between circuits.

[0041] The pitch between circuits refers to the distance between the winding starting point Ps(k) for each lap of the circuit and the control line CL. In other words, with each lap of the circuit, the fiber tow 30 is wound onto the liner 20, shifting by 1 pitch along the central axis C1.

[0042] In determining the pitch between circuits, the winding setting unit determines a temporary winding endpoint for the circuit. For example, if the set number of circuit laps is n, the temporary winding endpoint {L(1), Pe(n)} will be the same point on the control line CL as the winding start point {L(1), Ps(1)}.

[0043] Next, the winding setting unit sets the winding endpoint {L(1),Pe(n-1)}, which is one circuit turn before the temporary winding endpoint {L(1),Pe(n)}, as the true winding endpoint. In other words, in the first low helical layer, the winding endpoint of the fiber tow 30 is set to a position shifted by one pitch in the circumferential direction from the winding start point {L(1),Ps(1)} of the first circuit turn.

[0044] The end point of the first low-helical layer's winding at the final lap of the circuit {L(1), Pe(n-1)} becomes the starting point of the second low-helical layer's winding at the first lap of the circuit {L(2), Ps(1)}. As illustrated in the upper and middle sections of Figure 4, the winding angle θ2 in the second low-helical layer is different from the winding angle θ1 in the first low-helical layer.

[0045] In forming the second low-helical layer, the winding setting section is configured in the same way as for the first layer, setting the winding endpoint {L(2),Pe(n-1)}, which is one circuit turn before the temporary winding endpoint {L(2),Pe(n)}, as the true winding endpoint. In other words, in the second low-helical layer, the winding endpoint of the fiber tow 30 is set at a position shifted by one pitch in the circumferential direction from the winding start point {L(2),Ps(1)} of the second circuit turn.

[0046] The end point of the winding of the second low-helical layer at the final lap of the circuit {L(2), Pe(n-1)} becomes the starting point of the winding of the third low-helical layer at the first lap of the circuit {L(3), Ps(1)}. As illustrated in the middle and lower sections of Figure 4, the winding angle θ3 of the third low-helical layer is different from the winding angle θ2 of the second low-helical layer.

[0047] In forming the third low-helical layer, as with the first and second layers, the winding setting section sets the winding endpoint {L(3),Pe(n-1)}, which is one circuit turn before the temporary winding endpoint {L(3),Pe(n)}, as the true winding endpoint. In other words, in the third low-helical layer, the winding endpoint of the fiber tow 30 is set at a position shifted by one pitch in the circumferential direction from the winding start point {L(3),Ps(1)} of the third circuit turn.

[0048] In this way, the fiber tow 30 is wound in a low helical layer of a predetermined layer (e.g., layer k) such that the winding start point {L(k), Ps(1)} for the first lap of the circuit and the winding end point (L(k), Pe(n-1)) for the final lap of the circuit are located at different positions on the liner 20. This makes it possible to change the switching point position of the winding angle θ across each layer. By changing the switching point position of the winding angle θ on the liner 20, the occurrence of low-strength areas where the fiber tow 30 is locally thinned is suppressed. [Explanation of Symbols]

[0049] 10 High-pressure tank, 20 Liner, 22 Cylindrical section, 24, 26 Dome section, 30 Fiber tow.

Claims

[Claim 1] A step of forming a liner comprising a cylindrical portion and a pair of dome portions provided at both ends of the cylindrical portion in the axial direction, A lamination step of forming a fiber-reinforced plastic layer on the liner, Includes, In the lamination process, the fiber-reinforced plastic layer is formed by wrapping a fiber tow impregnated with binder resin around the liner. The fiber-reinforced plastic layer includes a low-helical layer formed by winding the fiber tow around the liner multiple times in a low-angle helical winding, where the winding angle with respect to the central axis of the liner is acute. In the aforementioned fiber-reinforced plastic layer, the low-helical layer is formed across multiple layers, When forming the low helical layer over multiple layers, the winding angle of the fiber tow is made different for each layer. The switching point position of the winding angle on the liner, which is the winding endpoint of the low helical layer of a predetermined layer and the winding starting point of the low helical layer of the next layer, is made different for each layer of the low helical layer. A method for manufacturing a high-pressure tank.

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