Method for manufacturing high-pressure tank

Abstract

Provided is a method for manufacturing a high-pressure tank, whereby the breaking strength of a reinforcing layer can be improved more reliably than in the prior art. The present invention relates to a method for manufacturing a high-pressure tank having a reinforcing layer (4) on the outer surface of a hollow liner (2), the method being characterized by comprising: a winding step for winding a fiber bundle containing a curable resin and having a prescribed tension around the outer surface of the liner (2); and a reinforcing layer forming step in which the reinforcing layer (4) is formed by curing the curable resin contained in the fiber bundle wound around the outer surface. The winding step is performed so that the tension of the fiber bundle decreases toward the outer peripheral side of the reinforcing layer (4).

Description

Technical Field

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

[0002] Conventionally, a high-pressure tank having a reinforcement layer formed by winding fibers containing a curable resin around the outside of a roughly cylindrical inner liner having domes at both ends is known as a high-pressure tank (for example, refer to Patent Document 1). The reinforcement layer of the high-pressure tank has a helical layer formed by spirally winding fibers, and a hoop layer formed by hoop winding fibers around the outside of the helical layer. In addition, in the manufacturing method of the high-pressure tank, the tension of the fibers is set so that the tension of the fibers when forming the hoop layer in the outer layer is greater than the tension of the fibers when forming the helical layer in the inner layer. According to the high-pressure tank manufactured by this method, even if the filling and release of gas are repeated many times in a high-temperature and high-humidity environment, the peeling at the interface between the helical layer (inner layer) and the hoop layer (outer layer) can be suppressed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-30873 Summary of the invention

[0006] However, in the conventional method for manufacturing a high-pressure tank (see, for example, Patent Document 1), it is believed that if the tension of the fibers in the outer layer is greater than that in the inner layer, the fibers in the inner layer will relax, which may reduce the breaking strength of the reinforcing layer.

[0007] An object of the present invention is to provide a method for manufacturing a high-pressure tank capable of more reliably improving the breaking strength of a reinforcement layer than conventional methods.

[0008] In the manufacturing method of the high-pressure tank of the present invention that achieves the above-mentioned problem, the high-pressure tank has a reinforcement layer on the outer surface of the hollow inner liner, and the manufacturing method of the high-pressure tank is characterized in that it has: a winding process of winding a fiber bundle with a specified tension containing a curable resin on the outer surface of the inner liner; and a reinforcement layer forming process of curing the curable resin contained in the fiber bundle wound on the outer surface to form the reinforcement layer, and the winding process is performed in a manner that the tension of the fiber bundle decreases as it approaches the outer peripheral side of the reinforcement layer.

[0009] Effects of the Invention

[0010] According to the method for manufacturing a high-pressure tank of the present invention, the breaking strength of the reinforcing layer can be more reliably improved than before. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a longitudinal sectional view of a high-pressure tank obtained by the manufacturing method according to the embodiment of the present invention.

[0012] Figure 2 is a partially enlarged transverse view of a high-pressure tank obtained by the manufacturing method according to an embodiment of the present invention.

[0013] Figure 3 It is a diagram for explaining the structure of a high-pressure tank manufacturing apparatus used in the manufacturing method according to the embodiment of the present invention.

[0014] Figure 4 It is an explanatory diagram of hoop winding of a fiber bundle performed in the production method according to the embodiment of the present invention.

[0015] Figure 5 It is an explanatory diagram of a fiber bundle winding step performed in the production method according to the embodiment of the present invention.

[0016] Figure 6 This is a graph showing the steps of reducing the tension of the fiber bundle (prepreg material) in the winding process.

[0017] Figure 7 It is an explanatory diagram of high helical winding of a fiber bundle performed in the production method according to the embodiment of the present invention.

[0018] Figure 8 It is an explanatory diagram of low spiral winding of a fiber bundle performed in the production method according to the embodiment of the present invention.

[0019] Fig. 9 This is a graph showing the relationship between the tension reduction range of the fiber bundle (prepreg material) and the breaking strength of the reinforcing layer.

[0020] Fig.10 This is a graph showing the relationship between the breaking strength of the reinforcing layer and the fluctuation in the breaking strength.

[0021] Description of Reference Numerals

[0022] 1 High pressure tank

[0023] 2 liner

[0024] 4 Strengthening layer

[0025] 5 Main body

[0026] 6 Dome

[0027] 7 unit layer

[0028] 8 composite layers DETAILED DESCRIPTION

[0029] Next, the mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings as appropriate. First, the structure of a high-pressure tank obtained by the manufacturing method of the present embodiment will be described.

[0030] Figure 1 It is a longitudinal sectional view of the high-pressure tank 1 . Figure 2 It is a partially enlarged transverse view of the high-pressure tank 1.

[0031] The high-pressure tank 1 of this embodiment is assumed to be a high-pressure tank installed in a fuel cell vehicle, for example, and stores hydrogen gas to be supplied to a fuel cell system. However, the high-pressure tank 1 is not limited thereto, and may be used for other high-pressure gases.

[0032] like Figure 1 As shown, the high-pressure tank 1 includes an inner liner 2 , a tank mouth metal fitting 3 connected to the inner liner 2 , and a reinforcing layer 4 covering the outer sides of the inner liner 2 and the tank mouth metal fitting 3 .

[0033] The mouth metal fitting 3 is assumed to be formed of a metal material such as aluminum alloy, etc. The mouth metal fitting 3 has a cylindrical mouth metal fitting body 3a having a supply and discharge hole inside, and a flange portion 3b formed on one axial end side of the mouth metal fitting body 3a.

[0034] The liner 2 is a hollow body made of a thermoplastic resin. Examples of the thermoplastic resin include polyamide resin and polyethylene resin, but are not limited thereto.

[0035] The inner container 2 of the present embodiment includes a cylindrical main body 5 and dome portions 6 formed integrally with both ends of the main body 5 .

[0036] like Figure 1 As shown, the dome portion 6 is a flat bowl-shaped body that converges so as to gradually reduce in diameter as it moves away from the main body portion 5 toward the outside in the axis Ax direction.

[0037] The radial center portion of the dome portion 6 is recessed so as to correspond to the shape of the flange portion 3 b of the can mouth metal fitting 3 .

[0038] like Figure 1 As shown, the reinforcement layer 4 is formed in the range from the outer surface of the inner liner 2 to the outer surface of the tank mouth metal member 3 .

[0039] As will be described in detail later, the reinforcing layer 4 is formed by curing a curable resin contained in a tow prepreg material wound in a range from the liner 2 to the tank mouth metal fitting 3 .

[0040] Furthermore, the tow prepreg material in the present embodiment is composed of a fiber bundle (tow) of reinforcing fibers containing a curable resin and has adhesiveness.

[0041] As the curable resin of the tow prepreg material, for example, thermosetting resins such as epoxy resin, phenol resin, unsaturated polyester resin, and polyimide resin are conceivable, but the present invention is not limited to these.

[0042] Examples of the reinforcing fibers include carbon fibers, glass fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers, and the like, but the reinforcing fibers are not limited thereto.

[0043] like Figure 2 As shown, the reinforcing layer 4 is composed of a plurality of unit layers 7 stacked on the outer surface of the inner liner 2. The reinforcing layer 4 in this embodiment is assumed to be composed of nine unit layers 7 in the main body 5 of the inner liner 2, but the number of unit layers 7 is not limited thereto.

[0044] The unit layer 7 is formed by using a manufacturing apparatus 10 (see Figure 3 ) in the strip delivery head 13b, that is, the strip B (refer to Figure 3 ) in the axial direction of the inner tank 2 (with Figure 2 It is formed by arranging in a direction perpendicular to the paper surface).

[0045] These unit layers 7 are integrated in a reinforcement layer forming step described later in which the curable resin of the tow prepreg material is cured.

[0046] Next, a manufacturing apparatus for the high-pressure tank 1 will be described.

[0047] Figure 3 It is a diagram for explaining the structure of the manufacturing device 10.

[0048] like Figure 3 As shown, the manufacturing device 10 is mainly composed of a feeding mechanism 11 for the yarn prepreg material P, a guiding mechanism 12 for guiding the yarn prepreg material P fed from the feeding mechanism 11 to the winding mechanism 13, and a winding mechanism 13 for winding the yarn prepreg material P guided by the guiding mechanism 12 into the inner liner 2.

[0049] The delivery mechanism 11 includes a plurality of bobbins 11a on which the tow prepreg material P is intertwined and wound, and a bobbin motor (not shown) that assists the rotation of the bobbins 11a so that the tow prepreg material P is drawn out from each bobbin 11a at a predetermined tension. In addition, it is assumed that the number of bobbins 11a of the delivery mechanism 11 in this embodiment is five. However, the number of bobbins 11a is not limited thereto and can be appropriately changed as needed.

[0050] The guide mechanism 12 has a plurality of guide rollers 12a on which the tow prepreg material P is mounted. The guide rollers 12a have a plurality of guide circumferential grooves (not shown) so as to guide the plurality of tow prepreg materials P fed out from the feeding mechanism 11 individually. These guide circumferential grooves have a flat bottom surface with a predetermined width. The tow prepreg material P moves from the feeding mechanism 11 on the upstream side to the winding mechanism 13 on the downstream side while contacting the bottom surfaces of these guide circumferential grooves. As a result, the cross-sectional shape of the tow prepreg material P is gradually flattened.

[0051] It is assumed that the guide rollers 12a in this embodiment cooperate to guide the plurality of (five) tow prepreg materials P fed out from the feeding mechanism 11. However, the guide rollers 12a may also be composed of separate rollers that independently guide the respective tow prepreg materials P. In addition, the guide mechanism 12 in this embodiment has seven guide rollers 12a, but the number of guide rollers 12a is not limited thereto.

[0052] The winding mechanism 13 includes a driving unit 13 a (rotating motor) for rotating the inner container 2 around the axis Ax, and a tape delivery head 13 b for delivering the tape B to the rotating inner container 2 .

[0053] The strip delivery head 13b arranges and integrates the plurality of (five) tow prepreg materials P flattened by the guide mechanism 12 in the width direction. Thus, the strip delivery head 13b forms the strip B of the tow prepreg material P in a band shape.

[0054] The strip delivery head 13b is composed of a pair of pressing rollers 13b1, 13b1 arranged with a predetermined gap. A plurality of (five) strands of prepreg P ​​are arranged and gathered laterally on the upstream side of the strip delivery head 13b and are pressed and formed into a strip B with a larger width when passing between the pair of pressing rollers 13b1, 13b1.

[0055] In addition, the strip delivery head 13b can move along the axis Ax direction of the inner liner 2 while delivering the strip B to the rotating inner liner 2. Specifically, the strip delivery head 13b moves along the axis Ax direction corresponding to the rotation of the inner liner 2, so as to form the above-mentioned unit layer 7 on the outer peripheral side of the inner liner 2 (see Figure 2 ) In the present embodiment, a direct-acting actuator 13c such as an air cylinder or a linear motor is envisioned as a moving mechanism for the tape delivery head 13b, but the present invention is not limited thereto.

[0056] In addition, the strip delivery head 13b is configured to adjust the tension of the strip B supplied to the inner liner 2. Specifically, the strip delivery head 13b adjusts the load applied to the tow prepreg material P in a direction intersecting the travel direction of the tow prepreg material P. As a tension adjustment moving mechanism for the strip B in this embodiment, a spacing adjustment actuator 13d provided between the direct-acting actuator 13c and the strip delivery head 13b is envisioned. As the spacing adjustment actuator 13d, a rack and pinion mechanism driven by a rotary motor and a cylinder can be cited, but it is not limited to this.

[0057] In addition, it is assumed that the interval adjustment actuator 13d in the present embodiment displaces the strip delivery head 13b in such a manner that the detected tension becomes a preset target tension based on the detected tension of the tow prepreg material P or the strip B. In addition, as a mechanism for detecting the tension of the tow prepreg material P or the strip B, a sensor for detecting the reaction force received by the strip delivery head 13b from the tow prepreg material P or the strip B can be cited, but it is not limited to this.

[0058] The displacement control mechanism of the strip delivery head 13b can be constructed to have a program for instructing the spacing adjustment actuator 13d in such a way that the detected tension of the filament prepreg material P or the strip B becomes the target tension, a ROM (read-only memory) for storing such a program, a RAM (random access memory) for reading the program stored in the ROM and expanding it, and a CPU (central processing unit) for executing the expanded program and outputting instructions to the spacing adjustment actuator 13d.

[0059] Next, a method for manufacturing the high-pressure tank 1 according to the present embodiment will be described.

[0060] The manufacturing method of this embodiment comprises: preparing a tow prepreg material P (see Figure 3 ) into a strip B (refer to Figure 3 ) to the inner tank 2 (refer to Figure 3 and the tow prepreg material P wound on the outer surface of the liner 2 contained in the curable resin is cured to form a reinforcing layer 4 (reference Figure 2 ) reinforcement layer forming step.

[0061] Here, strip B (refer to Figure 3 ) in a hoop-winding manner to the inner liner 2 (refer to Figure 3 ) of the main body 5 (refer to Figure 3 ) winding method as an example to specifically illustrate the manufacturing method of this embodiment.

[0062] Figure 4 It is an explanatory diagram of the hoop-shaped winding of the strip B relative to the inner liner 2.

[0063] like Figure 4 As shown in FIG. 1 , the circumferential winding is that the strip B is wound in a hoop shape (circular shape) relative to the main body 5 of the liner 2. That is, in the circumferential winding, the angle θ1 formed by the extension direction D of the strip B relative to the axis Ax direction is set to an angle close to 90 degrees, so that the strip B is arranged along the axis Ax direction. As a result, the strip B forms a unit layer 7 having a thickness substantially the same as that of the strip B on the outer peripheral surface of the main body 5 of the liner 2 (see FIG. 1 ). Figure 2 ).

[0064] Figure 5 This is an explanatory diagram of the winding process of the strip B based on hoop winding.

[0065] In the winding process, Figure 5 As shown, a plurality of unit layers 7 are formed on the outer peripheral surface of the main body 5 of the inner container 2. Figure 3 As shown, the strip delivery head 13b is moved back and forth relative to the rotating inner liner 2 by a distance corresponding to the length of the main body 5 of the inner liner 2, thereby forming the unit layer 7 in the hoop winding. Figure 3 ) is formed on the way forward with odd-numbered unit layers 7 (refer to Figure 5 ), an even-numbered unit layer 7 is formed on the return path (refer to Figure 5 ).

[0066] Such a winding process is to make the tension of the fiber bundle in the strip B increase as it moves toward the reinforcing layer 4 (refer to Figure 2 ) is performed in a manner that the tension of the strip B is reduced on the outer peripheral side of the reinforcing layer 4 (refer to Figure 2 ) in the layer thickness direction according to the specified tension reduction amplitude stepwise reduction. In addition, in order to facilitate drawing, Figure 5 In the middle, band B (refer to Figure 3 ) are represented by hollow arrows pointing downward on the paper.

[0067] In addition, if Figure 5 As shown, at least two unit layers 7 overlap each other along the layer thickness direction of the reinforcing layer 4 to form a composite layer 8, and the winding process is preferably performed in a manner that reduces the tension of the strip B for each composite layer 8. In addition, the composite layer 8 in this embodiment is assumed to be composed of two unit layers 7, but it can also be composed of three or more unit layers 7.

[0068] like Figure 5 As shown, in the winding process of this embodiment, the strip B of the composite layer 8 composed of the first layer unit layer 7a and the second layer unit layer 7b (see Figure 3) is set as the first tension Ts1. In addition, the strip B of the composite layer 8 composed of the third unit layer 7c and the fourth unit layer 7d (see Figure 3 ) is set as the second tension Ts2. In addition, regarding the plurality of unit layers 7 ( Figure 5 Although not shown in the figure, the two unit layers 7 also form a composite layer. Figure 3 ) A different tension Ts is set for each of these composite layers.

[0069] Figure 6 1 is a diagram showing the steps of reducing the tension of the strip B in the winding process.

[0070] like Figure 6 As shown, the tension of strip B ( Figure 6 The prepreg tension (N) is reduced stepwise from the first tension Ts1 to the second tension Ts2.

[0071] That is, the winding process in this embodiment includes: winding the strip B (first layer and second layer) in the form of strip B (refer to Figure 3 ) is relative to the first tension Ts1 (basic tension) at the beginning of winding of the inner liner 2 (reference Figure 3 ) in a basic tension winding process for winding the strip B (the 3rd layer and the 4th layer) at a second tension Ts2 which is reduced compared to the first tension Ts1 (basic tension) relative to the strip B (the 1st layer and the 2nd layer) wound at the first tension Ts1 (basic tension).

[0072] Although not shown in the figure, for the unit layers 7 above the 5th layer (see Figure 5 ), and can also make the tension of strip B ( Figure 6 The prepreg tension (N) is reduced stepwise for each composite layer.

[0073] As will be described in detail later, the tension reduction width of the second tension Ts2 relative to the first tension Ts1 (base tension) is preferably set within a range of 1.00 N to 4.50 N.

[0074] As described in detail later, it is preferable that the first tension Ts1 (base tension) is set so that the reinforcing layer 4 (see Figure 1 ) reaches its peak value within the range of 1.00N or more and 4.50N or less set by the tension reduction amplitude.

[0075] The manufacturing method of this embodiment envisions the following situation: Figure 4As shown, only the main body 5 of the liner 2 is subjected to the basic tension winding process and the tension reduction winding process, and then the strip B (refer to Figure 3 ) to the inner tank 2 (refer to Figure 3 Specifically, the manufacturing method assumes the following structure: the strip B is wound in a high spiral manner relative to the strip B wound in a hoop-wound manner on the main body 5 (refer to Figure 4 ) is wound, and then strip B is wound by low helical winding relative to strip B which is wound in a high helical winding manner.

[0076] Figure 7 It is strip B (refer to Figure 3 ) is an illustration of high helical winding. Figure 8 It is strip B (refer to Figure 3 ) is an illustration of low helical winding.

[0077] like Figure 7 As shown, in the high helical winding, strip B (refer to Figure 3 ) is set so that the angle θ2 formed by the extension direction D of the strip B relative to the axis Ax direction is approximately 75 degrees. Thus, the strip B is wound within the range of the main body 5 of the inner liner 2 and the peripheral edge of the dome portion 6 adjacent to the main body 5.

[0078] like Figure 8 As shown, in the low helical winding, strip B (refer to Figure 3 ) is set so that the angle θ3 formed by the extension direction D of the strip B relative to the axis Ax direction is approximately 10 degrees. Thus, the strip B is wound in the entire range from the main body 5 to the dome 6 of the inner liner 2 that has been subjected to hoop winding and high helical winding.

[0079] In addition, the highly helically wound strip B (see Figure 3 ) and low helically wound ribbon B (refer to Figure 3 ) is set to the same tension as the final hoop-wound strip B in the tension-reducing winding process (refer to Figure 3 ) has the same tension. However, the highly helically wound ribbon B (refer to Figure 3 ) tension and low spirally wound ribbon B (refer to Figure 3 ) can also be set so that the tension is gradually increased as the reinforcement layer 4 (see Figure 1 ) and decreases toward the outer peripheral side.

[0080] In the reinforcement layer forming step, the inner liner 2 (refer to Figure 3 ) from the winding mechanism 13 (refer to Figure 3 ) and heated at a specified temperature in a heating furnace (not shown).

[0081] Thus, the strip B (refer to Figure 3 ) is cured. The overlapping plurality of unit layers 7 (see Figure 5 ) is integrated during the curing process of the curable resin and is in close contact with the outer surface of the liner 2. Thus, a reinforcing layer 4 is formed (refer to Figure 1 ), a series of manufacturing processes of the high-pressure tank 1 are completed.

[0082] Effects

[0083] Next, the effects of the method for manufacturing the high-pressure tank 1 according to the present embodiment will be described.

[0084] In the manufacturing method of this embodiment, the step of winding the strip B (fiber bundle) around the outer surface of the liner 2 is performed so that the tension of the strip B (fiber bundle) decreases toward the outer peripheral side of the reinforcing layer 4 .

[0085] According to this manufacturing method, the tension of the strip B (fiber bundle) wound on the outer layer side of the liner 2 can prevent the strip B (fiber bundle) on the inner layer side from loosening. According to this manufacturing method, the breaking strength of the reinforcing layer 4 can be more reliably improved compared with the previous manufacturing method (for example, refer to Patent Document 1).

[0086] Furthermore, according to this production method, as verified in the examples described below, it is possible to improve the breaking strength of the reinforcing layer 4 and reduce the variation in the breaking strength of the reinforcing layer 4 .

[0087] In addition, in such a manufacturing method, it is preferable that the above-mentioned winding step of adjusting the tension of the strip B (fiber bundle) is performed only on the main body 5 of the liner 2.

[0088] According to this manufacturing method, the strip B (fiber bundle) is wound around the main body 5 more emphatically than the dome portion 6 having higher strength against the internal pressure of the high-pressure tank 1, thereby enabling the reinforcement layer 4 as a whole of the high-pressure tank 1 to be strengthened more efficiently.

[0089] In addition, in such a manufacturing method, the winding step is preferably performed by winding the strip B (fiber bundle) around the main body 5 of the liner 2 in the hoop direction.

[0090] According to this manufacturing method, the strip B (fiber bundle) is wound around the main body 5 of the inner liner 2 in a manner that is approximately at right angles to the axis Ax of the inner liner 2. Therefore, the tension of the strip B (fiber bundle) can more effectively help improve the breaking strength of the reinforcing layer 4.

[0091] In such a manufacturing method, it is preferred that the unit layers 7 overlap each other in the layer thickness direction of the reinforcing layer 4 to form the composite layer 8, and the winding step is performed in such a way that the tension of the strip B (fiber bundle) is reduced for each composite layer 8.

[0092] According to this manufacturing method, the tension reduction range of the strip B (fiber bundle) that changes stepwise toward the outer circumference can be adjusted more reliably than the method of reducing the tension of the strip B (fiber bundle) for each unit layer 7. According to this manufacturing method, the fluctuation of the breaking strength of the reinforcing layer 4 can be further reduced.

[0093] In addition, in such a manufacturing method, it is preferred that the tension reduction amplitude of the strip B (fiber bundle) is set within a range of greater than 1.00N and less than 4.50N compared to the tension (basic tension) at the start of winding the strip B (fiber bundle) relative to the inner liner 2.

[0094] According to this production method, as verified in the examples described later, the breaking strength of the reinforcing layer 4 can be effectively improved.

[0095] In such a manufacturing method, it is preferable to set the tension (basic tension) at the start of winding of the strip B (fiber bundle) so that the breaking strength of the reinforcing layer 4 reaches a peak within the range of the tension reduction amplitude of 1.00N to 4.50N.

[0096] According to this production method, as verified in the examples described later, the breaking strength of the reinforcing layer 4 can be further effectively improved.

[0097] In addition, the winding step of such a manufacturing method can also be configured to combine hoop winding and helical winding in the layer thickness direction of the reinforcement layer 4 .

[0098] According to this manufacturing method, the arrangement directions of the fiber bundles in the reinforcing layer 4 of the liner 2 can be intersected by hoop winding and spiral winding, and thus the breaking strength of the reinforcing layer 4 can be further increased.

[0099] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It can be implemented in various forms.

[0100] Example

[0101] The effects of the method for manufacturing the high-pressure tank 1 of the present invention were verified.

[0102] Fig. 9 It indicates the reinforcement layer 4 (refer to Figure 1 ) and the breaking strength [Mpa] of strip B (refer to Figure 3) is a graph showing the relationship between the tension reduction amplitude [N] and the tension reduction amplitude [N]. In addition, the tension reduction amplitude [N] here refers to, for example Figure 6 As shown, from strip B (refer to Figure 3 ) relative to the main body 5 of the inner container 2 (refer to Figure 5 ) is the tension difference obtained by subtracting the second tension Ts2 (reduced tension) from the first tension Ts1 (basic tension) at the start of winding.

[0103] like Fig. 9 As shown, here, three high-pressure tanks of test materials a1 to a3 having a basic tension of 70N and four high-pressure tanks of test materials b1 to b4 having a basic tension of 50N were manufactured.

[0104] Specifically, in the high-pressure tank of the test material a1, when the tension reduction amplitude [N] is 0 and the basic tension set to 70N is maintained, the main body 5 of the inner liner 2 (refer to Figure 5 ) is formed by hoop winding to form a pre-cured reinforcement layer consisting of a total of four layers from the 1st layer to the 4th layer.

[0105] In the high-pressure tanks of the test materials a2 and a3, the first and second layers were hoop-wound at a basic tension of 70 N, and the third and fourth layers were wound at a corresponding tension reduction amplitude [N] ( Fig. 9 The steel sheet is hoop-wound at the second tension Ts2 of 67.5 N and 65 N, respectively (-2.5 N and -5.0 N) as shown, thereby forming a reinforcing layer before curing.

[0106] In addition, in the high-pressure tank of the test material b1, when the tension reduction amplitude [N] is 0 and the basic tension set to 50N is maintained, the main body 5 of the inner liner 2 (refer to Figure 5 ) is formed by hoop winding to form a pre-cured reinforcement layer consisting of a total of four layers from the 1st layer to the 4th layer.

[0107] In addition, in the high-pressure tanks of test materials b2 to b4, the first and second layers were hoop-wound at a basic tension of 50 N, and the third and fourth layers were wound at a corresponding tension reduction amplitude [N] ( Fig. 9 The steel sheet is hoop-wound at the second tension Ts2 of 47.5 N, 45.0 N and 40 N, respectively (-2.5 N, -5.0 N and -10 N as shown), thereby forming a reinforcing layer before curing.

[0108] The inner container 2 after the winding process is completed is heated in a heating furnace to make the wound strip B (refer to Figure 3 ) is cured, thereby obtaining Fig. 9The high-pressure tanks a1 to a3 and the high-pressure tanks b1 to b4 are shown. The breaking strength [Mpa] of the reinforcing layer was measured for these high-pressure tanks a1 to a3 and the high-pressure tanks b1 to b4. Fig. 9 The results are shown in . In addition, Fig. 9 The breaking strength [Mpa] is in the range of ±2σ (95.5%).

[0109] like Fig. 9 As shown, the high-pressure tanks a2 and b2 among the high-pressure tanks a1 to a3 and the high-pressure tanks b1 to b4 obtain the peak value of the fracture strength [Mpa] of the reinforcement layer.

[0110] Specifically, it was verified that the high-pressure tanks a2 and b2 can further improve the breaking strength [Mpa] of the reinforcing layer by reducing the tension of the outer strip B compared to the tension of the inner strip B, compared with the high-pressure tanks a1 and b1 obtained by conventional circumferential winding with fixed tension.

[0111] In addition, it was verified that: Fig. 9 As shown, the breaking strength [Mpa] of the reinforcing layer is further improved by setting the tension reduction range [N] of the strip B in the range of -1.0 [N] to -4.5 [N].

[0112] In addition, it was verified that: Fig. 9 As shown, by setting the basic tension in a manner such that the breaking strength [Mpa] of the reinforcement layer reaches a peak value within the range where the basic tension exceeds 50N and the tension reduction amplitude [N] is greater than 1.00N and less than 4.50N, a more abrupt peak value of the breaking strength [Mpa] can be obtained, that is, a greater breaking strength [Mpa] can be obtained.

[0113] Next, for a high-pressure tank in which the 1st to 4th layers are formed by circumferential winding of the strip B based on a fixed tension (comparison example) and a high-pressure tank in which the 3rd and 4th layers are formed by circumferential winding in which the tension of the strip B is reduced compared to the 1st and 2nd layers (implementation example), the breaking strength [Mpa] of the reinforcing layer is measured, and the fluctuation of the breaking strength is calculated.

[0114] In addition, the basic tension of the strip B in the high-pressure tank of the comparative example is set in the range of 10N to 70N. In addition, the basic tension of the strip B in the high-pressure tank of the embodiment is set in the range of 50N to 70N, and the tension reduction width [N] from the first and second layers to the third and fourth layers is set to 2.5N.

[0115] Fig.10 This is a graph showing the relationship between the breaking strength and the fluctuation of the breaking strength of the reinforcement layer of the high-pressure tanks produced in Examples and Comparative Examples.

[0116] like Fig.10 As shown, the data group represented by the 0 mark of the high-pressure tank of the present embodiment is shifted toward the coordinate position of the preferred corner represented by the hollow arrow, where the fracture strength is high and the fluctuation of the fracture strength is small, compared with the data group represented by the × mark of the high-pressure tank of the comparative example. Specifically, it was verified that the high-pressure tank of the present embodiment increases the base tension compared with the high-pressure tank of the comparative example, and reduces the tension of the strip B as it moves toward the outer peripheral side, thereby increasing the fracture strength of the reinforcement layer by 9.5% and reducing the fluctuation of the fracture strength by 9.3%.

Claims

1. A method for manufacturing a high-pressure tank, wherein the high-pressure tank has a reinforcement layer on the outer surface of a hollow inner liner, wherein the method for manufacturing the high-pressure tank is characterized by: A winding step of winding a fiber bundle having a predetermined tension and containing a curable resin around the outer surface of the liner; and a reinforcing layer forming step of curing the curable resin contained in the fiber bundle wound around the outer surface to form the reinforcing layer, The winding step is performed so that the tension of the fiber bundle decreases toward the outer peripheral side of the reinforcing layer.

2. The method for manufacturing a high pressure tank according to claim 1, wherein: The inner container has a cylindrical main body and domes at both ends of the main body. The winding step of reducing the tension of the fiber bundle is performed only on the main body portion of the liner.

3. The method for manufacturing a high-pressure tank according to claim 2, characterized in that: The winding step is performed by winding the fiber bundle in a hoop direction around the main body of the liner.

4. The method for manufacturing a high pressure tank according to claim 1, wherein: The reinforcing layer is composed of a plurality of unit layers stacked on the outer surface of the inner liner, and the unit layers are formed by arranging the ribbon-shaped fiber bundles along the axial direction of the inner liner. At least two unit layers are overlapped with each other in a layer thickness direction of the reinforcing layer to form a composite layer, and the winding step is performed so that the tension of the fiber bundle is reduced for each of the composite layers.

5. The method for manufacturing a high-pressure tank according to claim 1, wherein: The winding process comprises a basic tension winding process of winding the fiber bundle relative to the inner liner at a basic tension at the start of winding of the fiber bundle, and a reduced tension winding process of winding the fiber bundle relative to the fiber bundle wound at the basic tension at a tension reduced compared to the basic tension. The tension reduction width of the fiber bundle relative to the basic tension is set within a range of 1.00 N to 4.50 N.

6. The method for manufacturing a high-pressure tank according to claim 5, characterized in that: The basic tension is set so that the breaking strength of the reinforcing layer reaches a peak value within a range of the tension reduction width of 1.00 N to 4.50 N.

7. The method for manufacturing a high pressure tank according to claim 1, wherein: In the winding step, hoop winding and helical winding are performed in combination in the thickness direction of the reinforcement layer.

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