High-pressure tank and manufacturing process for it

Abstract

High-pressure tank (1), comprising: a lining (10) comprising a cylindrically shaped body section (11) and dome sections (12) arranged at both ends in the axial direction of the body section (11); a tire layer (21) in which a resin-impregnated fiber (15) is wound and laminated in a tire-shaped winding to cover the hull section (11); and a spiral layer (22) in which a resin-impregnated fiber (16) is wound and laminated in a spiral winding to cover at least the dome sections (12), characterized by the fact that an interfacial strength between the fiber (15) and the resin on the tire layer (21) covering the fuselage section (11) exhibits low fatigue strength and high tensile strength compared to an interfacial strength between the fiber (16) and the resin on the spiral layer (22) covering the dome sections (12).

Description

Technical area

[0001] The present invention relates to a high-pressure tank and a method for manufacturing the high-pressure tank. Technical background

[0002] As a high-pressure tank such as a hydrogen tank mounted on a fuel cell vehicle, a high-pressure tank including a liner and a reinforcement layer is known. The liner is composed of a cylindrically shaped body portion and dome portions arranged at both ends in the axial direction of the body portion. The reinforcement layer is formed by winding a resin-impregnated fiber so as to cover the liner. The reinforcement layer includes a hoop layer in which the resin-impregnated fiber is wound and laminated in a hoop-like winding on an outer periphery of the body portion, and a spiral layer in which the resin-impregnated fiber is wound and laminated in a spiral-like winding on an outer periphery of the liner including the dome portions.A high-pressure tank configured in this way must have high tensile strength and high fatigue strength to ensure safety. Various techniques have been proposed to meet these requirements.

[0003] As an example, WO 2017 / 149 817 A discloses a technique in which a fiber wrapped around the dome sections of a lining is irradiated with plasma to improve the adhesion of the resin to the fiber and thereby increase the fatigue strength of a high-pressure tank. High-pressure tanks and manufacturing methods therefor are also known in the prior art from DE 103 45 159 A1, DE 10 2016 225 194 A1, DE 10 2008 059 591 A1, and DE 10 2006 043 582 B3. Summary of the inventionTechnical problem

[0004] However, the technique described above has a limitation in improving fatigue strength, as plasma irradiation only reaches a surface layer of the resin-impregnated fiber and does not reach the inner layers of the resin-impregnated fiber. Furthermore, it is difficult to improve the tensile strength of the high-pressure tank using this plasma irradiation alone.

[0005] The present invention has been made to solve this technical problem and provides a high-pressure tank capable of simultaneously ensuring tensile strength and fatigue strength, and a method for manufacturing the high-pressure tank. Solution to the problem

[0006] A high-pressure tank according to the present invention is a high-pressure tank comprising a liner, a tire layer, and a spiral layer. The liner consists of a cylindrically shaped body portion and dome portions arranged at both ends in the axial direction of the body portion. In the tire layer, a resin-impregnated fiber is wound and laminated in a ribbon-shaped or hoop-shaped winding to cover the body portion. In the spiral layer, a resin-impregnated fiber is wound and laminated in a spiral-shaped or helical winding to cover at least the dome portions. An interfacial strength between the fiber and the resin on the tire layer covering the body portion has low fatigue strength and high tensile strength compared to an interfacial strength between the fiber and the resin on the spiral layer covering the dome portions.

[0007] In the high-pressure tank of the present invention, the interfacial strength between the fiber and the resin on the tire layer covering the body portion has low fatigue strength and high tensile strength compared to the interfacial strength between the fiber and the resin on the spiral layer covering the dome portion. Accordingly, the body portion, which has a significant influence on the tensile strength of the high-pressure tank, is reinforced with the tire layer having the interfacial strength with high tensile strength, and the dome portions, which have a significant influence on the fatigue strength of the high-pressure tank, are reinforced with the spiral layers having the interfacial strength with high fatigue strength. Consequently, the tensile strength and fatigue strength of the high-pressure tank can be simultaneously ensured.

[0008] In the high-pressure tank of the present invention, the fiber and / or resin used for the tire layer covering the body portion and the spiral layer covering the dome portions may be different.

[0009] In the high-pressure tank of the present invention, heat amounts for heating the resins of the tire layer covering the body portion and the spiral layer covering the dome portions may be different.

[0010] A method for manufacturing a high-pressure tank according to the present invention is a method for manufacturing a high-pressure tank comprising a liner having a cylindrically shaped body portion and dome portions arranged at both ends in the axial direction of the body portion, a hoop layer in which a resin-impregnated fiber is wound and laminated in a hoop-shaped winding to cover the body portion, and a spiral layer in which a resin-impregnated fiber is wound and laminated in a spiral winding to cover at least the dome portions, the method comprising: a hoop layer laminating step of laminating the hoop layer covering the body portion to obtain low fatigue strength and high tensile strength compared to the spiral layer covering the dome portions for interfacial strength between the fiber and the resin;and a spiral layer lamination step of laminating the spiral layer covering the dome portions to obtain high fatigue strength and low tensile strength compared to the hoop layer covering the body portion for interfacial strength between the fiber and the resin.;

[0011] The method for manufacturing a high-pressure tank of the present invention includes the tire layer laminating step of laminating the tire layer covering the body portion so as to have the low fatigue strength and the high tensile strength in the interface strength between the fiber and the resin as compared with the spiral layer covering the dome portions, and the spiral layer laminating step of laminating the spiral layer covering the dome portions so as to have the high fatigue strength and the low tensile strength in the interface strength between the fiber and the resin as compared with the tire layer covering the body portion.Accordingly, the dome sections, which have a significant influence on the fatigue strength of the high-pressure tank, can be reinforced with the spiral layer, which has the interfacial strength with the high fatigue strength, while the hull section, which has a significant influence on the tensile strength of the high-pressure tank, is reinforced with the hoop layer, which has the interfacial strength with the high tensile strength. Consequently, the tensile strength and fatigue strength of the manufactured high-pressure tank can be provided simultaneously.

[0012] In the method for manufacturing a high-pressure tank according to the present invention, the fiber and / or resin used in the tire layer laminating step and the spiral layer laminating step may be different.

[0013] The method for manufacturing a high-pressure tank according to the invention further comprises a heat-curing step for thermally curing the laminated tire layer and the laminated spiral layer. In the heat-curing step, the amount of heat for heating the tire layer covering the body portion may be different from the amount of heat for heating the spiral layer covering the dome portions. Advantageous effects of the invention

[0014] The present invention can provide the tensile strength and the fatigue strength simultaneously. Short description of the drawings Fig. 1 is a cross-sectional view illustrating the structure of a high-pressure tank; Fig. 2A is a schematic diagram for describing a tire winding; Fig. Figure 2B is a schematic diagram for describing a spiral winding; Fig.3A is a diagram illustrating a relationship between the interfacial strength between a fiber and a resin and a tensile strength; Fig. 3B is a graph illustrating a relationship between the interfacial strength between the fiber and the resin and a fatigue strength; Fig. 4 is a schematic diagram illustrating a state in which a tire layer covering a body portion and a spiral layer covering dome portions are thermally cured; Fig. 5 is a schematic diagram illustrating a relationship between portions of a liner and a wind speed; Fig.6 is a diagram illustrating temperature changes of the dome portion in the case of normal thermal curing and in the case of combined use of normal thermal curing and built-in socket heat transfer by an IH heater; Fig. Fig. 7 is a diagram illustrating a temperature rise of the dome portion in the case of built-in socket heat transfer; and Fig. 8 is a graph illustrating a result of interfacial bond strength and tensile strength according to Example 1. Description of embodiments

[0015] Embodiments of a high-pressure tank and a method for manufacturing the high-pressure tank of the present invention will be described below with reference to the drawings. In the following description, a "resin-impregnated fiber" will be abbreviated as "resin-impregnated fiber," and an "interfacial strength between a fiber and a resin" will be abbreviated as "interfacial strength" unless specifically mentioned. [High-pressure tank]

[0016] First, a structure of the high-pressure tank is based on Fig. 1 described. Fig.1 is a cross-sectional view illustrating the structure of the high-pressure tank. A high-pressure tank 1 is a hydrogen tank mounted on, for example, a fuel cell vehicle, and includes a liner 10, a tire layer 21, and a spiral layer 22. The liner 10 includes a cylindrically shaped body portion 11 and dome portions 12 arranged at both ends in the axial direction of the body portion 11. In the tire layer 21, a resin-impregnated fiber is wound and laminated in a ribbon-shaped or hoop-shaped winding to cover the body portion 11. In the spiral layer 22, a resin-impregnated fiber is wound and laminated in a spiral-shaped or helical winding to cover the dome portions 12 and the body portion 11 (i.e., the entire liner 10). The tire layer 21 and the spiral layer 22 constitute a so-called reinforcement layer 20.

[0017] The liner 10 is a hollow container containing a storage space for high-pressure hydrogen and is made of a material with a gas barrier property for hydrogen gas. The liner 10 includes the body section 11 and a pair of the above-described dome sections 12. The dome sections 12 have hemispherical shapes. The pair of dome sections 12 each has an opening at the top, and a valve-side base or mounting socket 13 is inserted inside one of these openings, while an end-side base or mounting socket 14 is inserted inside the other opening.

[0018] The liner 10 is integrally formed using a resin material such as polyethylene and nylon by a rotary blow molding method. The liner 10 may be formed from a light metal such as aluminum instead of the resin material. Furthermore, the liner 10 may be formed by joining a plurality of divided members using an injection molding / extrusion molding method, etc., instead of the manufacturing method by integral molding such as the rotary blow molding method.

[0019] As in Fig.2A, the tire layer 21 is a reinforcing layer formed by winding a resin-impregnated fiber (e.g., a resin-impregnated tire wrapping fiber 15) in a ribbon-shaped or tire-shaped winding or tire winding in a circumferential direction of the body portion 11 at a winding angle approximately perpendicular to the central axis L of the liner 10. Here, "approximately perpendicular" includes both 90° and an angle of about 90° possibly caused by a shift in the winding positions of the resin-impregnated tire wrapping fiber 15 to avoid overlap of the resin-impregnated tire wrapping fiber 15.

[0020] The spiral layer 22 is shaped to cover the entire liner 10, so that the laminated tire layer 21 and the dome sections 12 are wrapped. As shown in Fig.As shown in Fig. 2B, the spiral layer 22 is formed by winding a resin-impregnated fiber (e.g., a resin-impregnated spiral-wound fiber 16) in a spiral or helical winding or spiral winding in the circumferential direction of the body portion 11 and the dome portions 12 at a winding angle of more than 0° and less than 90° to the central axis L of the liner 10. The spiral winding is further divided into a low-angle spiral winding and a high-angle spiral winding depending on the winding angle.

[0021] Namely, the low-angle spiral winding is a spiral winding with a small winding angle (e.g., more than 0° and 30° or less), and this winding method causes the winding direction of the resin-impregnated spiral winding fiber 16 on the dome portion 12 to be reversed before the resin-impregnated spiral winding fiber 16 travels once around the central axis L. Namely, the high-angle spiral winding is a spiral winding with a large winding angle (e.g., more than 30° and less than 90°), and a winding method in which the resin-impregnated spiral winding fiber 16 travels at least once around the central axis L on the body portion 11 before the winding direction of the resin-impregnated spiral winding fiber 16 on the dome portion 12 is reversed. Fig. Figure 2B illustrates the low angle spiral winding.

[0022] The resin-impregnated tire-wrapped fiber 15 and the resin-impregnated spiral-wrapped fiber 16 are formed, for example, by impregnating a bundle of single fibers with diameters of approximately a few µm with an uncured thermosetting or thermoplastic resin. The single fiber may contain a fiber such as a glass fiber, a carbon fiber, an aramid fiber, an alumina fiber, a boron fiber, a steel fiber, a PBO fiber, a natural fiber, or a high-strength polyethylene fiber. The thermosetting resin may contain an epoxy resin, a modified epoxy resin, typified by a vinyl ester resin, a phenolic resin, a melamine resin, a urea resin, an unsaturated polyester resin, an alkyd resin, a polyurethane resin, and a thermosetting polyimide resin.For the resin-impregnated tire winding fiber 15 and the resin-impregnated spiral winding fiber 16, the same resin and the same fiber may be used, or different resins and / or different fibers may be used.

[0023] Here, a background of the present invention will be described. Fig. 3A is a diagram illustrating a relationship between an interfacial strength between a fiber and a resin and a tensile strength, and Fig. Figure 3B is a graph illustrating a relationship between the interfacial strength between the fiber and the resin and a fatigue strength. As shown in Fig.As shown in Figure 3A, the tensile strength increases with increasing interfacial strength between the fiber and the resin, but after exceeding a certain value, the tensile strength decreases even though the interfacial strength between the fiber and the resin increases. Meanwhile, as shown in Fig. As shown in Figure 3B, the fatigue strength increases as the interfacial strength between the fiber and the resin increases. Tensile strength is also referred to here as initial strength or static strength, and fatigue strength is also referred to as interlaminar shear strength. The interfacial strength between the fiber and the resin can be measured using, for example, the well-known push-out method or the drop method.

[0024] It is known that the tensile strength of the high-pressure tank 1 is significantly influenced by the hoop layer 21 covering the body portion 11 of the liner 10, and the fatigue strength of the high-pressure tank 1 is significantly influenced by the spiral layer 22 covering the dome portions 12 of the liner 10.

[0025] Therefore, the inventor found that the tensile strength and the fatigue strength of the high-pressure tank 1 can be simultaneously achieved by respectively optimizing the interface strength on the hoop layer 21 covering the body portion 11 of the liner 10 and the interface strength on the spiral layer 22 covering the dome portions 12 by making the interface strength on the hoop layer 21 covering the body portion 11 an interface strength in which the tensile strength becomes as high as possible, while making the interface strength on the spiral layer 22 covering the dome portions 12 an interface strength in which the fatigue strength becomes as high as possible (see the regions in Fig. 3A and Fig. 3B, which are surrounded by dashed lines). In this case, as in Fig. 3A and Fig.3B, the interfacial strength on the tire layer 21 covering the body portion 11 is smaller than the interfacial strength on the spiral layer 22 covering the dome portions 12.

[0026] Furthermore, the inventor continued his serious studies and consequently found that the optimization of the interface strength on the tire layer 21 covering the body portion 11 and the interface strength on the spiral layer 22 covering the dome portions 12 is ensured, respectively, by using, for example, different resins and / or fibers for the resin-impregnated tire wrapping fiber 15 and the resin-impregnated spiral wrapping fiber 16 or by making a physical property of the tire layer 21 covering the body portion 11 different from a physical property of the spiral layer 22 covering the dome portions 12 by heating.

[0027] As a method of using different resins and / or fibers for the resin-impregnated tire winding fiber 15 and the resin-impregnated spiral winding fiber 16, for example, a material having the interface strength in which the fatigue strength is low and the tensile strength is high compared to the interface strength on the spiral layer is used for the tire layer, while a material having the interface strength in which the fatigue strength is high and the tensile strength is low compared to the interface strength on the tire layer is used for the spiral layer.

[0028] As the method for making the physical property of the tire layer 21 covering the body portion 11 different from the physical property of the spiral layer 22 covering the dome portions 12 by heating, for example, an amount of heat for heating the spiral layer 22 covering the dome portions 12 is increased compared to an amount of heat for heating the tire layer 21 covering the body portion 11.

[0029] Accordingly, in the high-pressure tank 1 of the embodiment, the interface strength on the hoop layer 21 covering the body portion 11 has the low fatigue strength and the high tensile strength compared with the interface strength on the spiral layer 22 covering the dome portions 12.

[0030] In the high-pressure tank 1 thus configured, the interfacial strength of the tire layer 21 covering the body portion 11 has low fatigue strength and high tensile strength compared to the interfacial strength of the spiral layer 22 covering the dome portions 12. Therefore, the body portion 11, which has a significant influence on the tensile strength of the high-pressure tank 1, is reinforced with the tire layer 21 having interfacial strength with high tensile strength, and the dome portions 12, which have a significant influence on the fatigue strength of the high-pressure tank 1, are reinforced with the spiral layer 22 having interfacial strength with high fatigue strength. Thus, the tensile strength and fatigue strength of the high-pressure tank 1 can be simultaneously ensured.

[0031] In the high-pressure tank 1 of the embodiment, the fiber and / or resin to be used for the tire layer 21 covering the body portion 11 and the spiral layer 22 covering the dome portions 12 may be different, or the amount of heat for heating the resin impregnated in the fiber may be different. Accordingly, the interfacial strength on the tire layer 21 covering the body portion 11 has the low fatigue strength and the high tensile strength compared to the interfacial strength on the spiral layer 22 covering the dome portions 12, and the tensile strength and fatigue strength of the high-pressure tank 1 can be easily provided simultaneously. [Method for manufacturing the high-pressure tank]

[0032] Embodiments of a method for manufacturing the high-pressure tank 1 will be described below. In a first embodiment, the method for manufacturing the high-pressure tank will be described in which the type of resin-impregnated fiber to be used is different for the tire layer 21 covering the body portion 11 and the spiral layer 22 covering the dome portions 12, and in a second embodiment, the method for manufacturing the high-pressure tank will be described in which the amount of heat for heating the resin is different for the tire layer 21 covering the body portion 11 and the spiral layer 22 covering the dome portions 12. [First embodiment]

[0033] The method for manufacturing the high-pressure tank 1 according to the first embodiment includes a tire layer lamination step for laminating the tire layer 21 covering the body portion 11 to obtain the low fatigue strength and the high tensile strength compared to the spiral layer 22 covering the dome portions 12 for the interfacial strength between the fiber and the resin; a spiral layer lamination step for laminating the spiral layer 22 covering the dome portions 12 to obtain the high fatigue strength and the low tensile strength compared to the tire layer 21 covering the body portion 11 for the interfacial strength between the fiber and the resin; and a heat-curing step for thermally curing the laminated tire layer 21 and the laminated spiral layer 22.

[0034] Specifically, first, in the tire layer laminating step, the resin-impregnated tire wrapping fiber 15 is wound around the body portion 11 of the liner 10 to laminate a plurality of tire layers 21. At this time, the resin of the resin-impregnated tire wrapping fiber 15 is a resin containing an acid anhydride as a curing agent and has an interfacial strength between the fiber and the resin of about 20 MPa. Here, the main active ingredient of the resin may be changed instead of the curing agent. Alternatively, the O / C value (i.e., an oxygen concentration of the carbon fiber surface) of a carbon fiber sizing agent of the resin-impregnated tire wrapping fiber 15 may be changed, or the fiber surface roughness may be changed, or a sizing agent applied over the fiber may be changed.

[0035] In the spiral layer lamination step following the tire layer lamination step, the resin-impregnated spiral wound fiber 16 is wound around the liner 10 to laminate a plurality of spiral layers 22, so that the laminated tire layers 21 and the dome portions 12 are wrapped. At this time, the resin of the resin-impregnated spiral wound fiber 16 contains an aromatic amine as a curing agent and has an interfacial strength between the fiber and the resin of about 76 MPa. Here, the main active ingredient of the resin can be changed instead of the curing agent. Alternatively, the O / C value (i.e., an oxygen concentration of the carbon fiber surface) of a carbon fiber sizing agent of the resin-impregnated spiral wound fiber 16 can be changed, or the fiber surface roughness can be changed, or a sizing agent applied over the fiber can be changed.

[0036] Next, as needed, the above-described laminating step of the tire layer 21 and the laminating step of the spiral layer 22 are repeatedly performed to form the uncured reinforcing layer 20 on an outer periphery of the liner 10.

[0037] Meanwhile, in the heat-curing step, the liner 10 comprising the laminated tire layer 21 and the laminated spiral layer 22 is placed in a heat-curing oven and heated to a temperature of, for example, about 85°C, and the resins in the resin-impregnated tire wrap fiber 15 and the resin-impregnated spiral wrap fiber 16 are thermally cured. Thus, the high-pressure tank 1 is manufactured.

[0038] The method for manufacturing the high-pressure tank 1 of the embodiment includes the tire layer lamination step of laminating the tire layer 21 covering the body portion 11 to obtain the low fatigue strength and the high tensile strength compared to the spiral layer 22 covering the dome portions 12 for the interface strength between the fiber and the resin, and the spiral layer lamination step of laminating the spiral layer 22 covering the dome portions 12 to obtain the high fatigue strength and the low tensile strength compared to the tire layer 21 covering the body portion 11 for the interface strength between the fiber and the resin.Accordingly, the dome portions 12, which have a significant influence on the fatigue strength of the high-pressure tank 1, can be reinforced with the spiral layer 22, which has the interfacial strength with high fatigue strength, while the body portion 11, which has a significant influence on the tensile strength of the high-pressure tank 1, can be reinforced with the hoop layer 21, which has the interfacial strength with high tensile strength. Thus, the tensile strength and fatigue strength of the manufactured high-pressure tank 1 can be simultaneously achieved.

[0039] In the method for manufacturing the high-pressure tank 1 according to the embodiment, by using two different types of resin-impregnated fibers, the resin-impregnated tire-wound fiber 15 and the resin-impregnated spiral-wound fiber 16, the tensile strength and the fatigue strength of the high-pressure tank 1 are easily ensured at the same time. [Second embodiment]

[0040] A method for manufacturing the high-pressure tank 1 according to the second embodiment includes the tire layer lamination step, the spiral layer lamination step, and the heat-setting step, similar to the first embodiment described above. However, the method differs from that of the first embodiment in that the resin-impregnated tire wrapping fiber 15 for tire wrapping is the same as the resin-impregnated spiral wrapping fiber 16 for spiral wrapping, and the amount of heat for heating the tire layer 21 covering the body portion 11 is different from the amount of heat for heating the spiral layer 22 covering the dome portions 12 in the heat-setting step. Only the difference will be described below.

[0041] That is, the fiber and resin of the resin-impregnated tire wrap fiber 15 used in the tire layer lamination step are completely identical to those of the resin-impregnated spiral wrap fiber 16 used in the spiral layer lamination step. In addition, in the heat-setting step, the amount of heat for heating the spiral layer 22 covering the dome portions 12 is increased compared to the amount of heat for heating the tire layer 21 covering the body portion 11.

[0042] More specifically, during the heat curing step, as shown in Fig.4, hot air is blown onto the tire layer 21 covering the body portion 11 and the spiral layer 22 covering the dome portions 12 to thermally cure the resin of the resin-impregnated tire winding fiber 15 and the resin of the resin-impregnated spiral winding fiber 16. At this time, an air flow blown onto the tire layer 21 covering the body portion 11 is relatively reduced, while an air flow blown onto the spiral layer 22 covering the dome portions 12 is relatively increased.

[0043] In addition, at this time, as in Fig. 5, the amount of heat for heating the spiral layer 22 covering the dome sections 12 is increased by increasing the wind speed blowing onto the dome sections 12 compared to the wind speed blowing onto the fuselage section 11. For comparison, in Fig.5 also shows a relationship between the sections of the lining and the wind speed during normal thermal curing. Fig. 5 that the wind speed blowing onto the dome sections 12 is significantly increased in the embodiment compared to the case of normal thermal curing.

[0044] The heat-setting step in the embodiment is, unlike the thermal curing of the resin of the resin-impregnated fiber described in the first embodiment, heating to change the physical property of the spiral layer 22 to improve the interface strength on the spiral layer 22 covering the dome portions 12.

[0045] In order to increase the amount of heat for heating the spiral layer 22 covering the dome portions 12 compared to the amount of heat for heating the tire layer 21 covering the fuselage portion 11, instead of the above-described method of changing the wind speed and air flow, it may be considered that the spiral layer 22 is heated from an inside of the dome portions 12 using base heat transfer while performing normal heat curing.

[0046] Specifically, metal jigs are connected to the valve-side mounting socket 13 and the end-side mounting socket 14 of the liner 10, respectively, and an IH heater or an IR heater is used to heat the jigs simultaneously with normal heat curing or thermal curing, respectively. In this way, heat is transferred to the valve-side mounting socket 13 and the end-side mounting socket 14 via the jigs, and the spiral layer 22 covering the dome sections 12 can also be heated from the inside of the dome section 12.

[0047] Fig. Figure 6 is a diagram illustrating temperature changes of the dome section in the case of normal thermal curing (hot air alone) and in the case of combined use of normal thermal curing and built-in socket heat transfer by the IH heater (hot air + IH). As shown in Fig.As shown, in the case of normal thermal curing, the temperature of the dome section is gradually increased by the heater, while in the case of the combined use of normal thermal curing and built-in socket heat transfer, the temperature of the dome section can be quickly increased by the IH heater.

[0048] Fig. Figure 7 is a graph illustrating the temperature rise of the dome section in the case of built-in socket heat transfer. As shown in Fig.As shown in Figure 7, in the case of conventional thermal curing, since the spiral layer covering the dome portions is thick and heat also escapes to the valve-side mounting socket and the end mounting socket, the temperature rise of the dome portion is slow compared to that of the body portion, and the temperature of the dome portion is lower than that of the body portion. However, when the base or mounting socket heat transfer by the IH heater is utilized, the temperature rise of the dome portion accelerates compared to that of the body portion, and thus the temperature of the dome portion becomes higher than that of the body portion. It can be seen that in the case of mounting socket heat transfer by the IH heater, the temperature rise increases with increasing heating temperature (160°C to 180°C).

[0049] The method for manufacturing the high-pressure tank 1 according to the embodiment includes: a tire layer lamination step of laminating the tire layer 21 covering the body portion 11 to obtain the low fatigue strength and the high tensile strength compared to the spiral layer 22 covering the dome portions 12 for the interfacial strength between the fiber and the resin; a spiral layer lamination step of laminating the spiral layer 22 covering the dome portions 12 to obtain the high fatigue strength and the low tensile strength compared to the tire layer 21 covering the body portion 11 for the interfacial strength between the fiber and the resin; and a heat-curing step of thermally curing the laminated tire layer 21 and the laminated spiral layer 22.Accordingly, the dome portions 12, which have a significant influence on the fatigue strength of the high-pressure tank 1, can be reinforced with the spiral layer 22, which has the interfacial strength with the high fatigue strength, while the body portion 11, which has a significant influence on the tensile strength of the high-pressure tank 1, can be reinforced with the hoop layer 21, which has the interfacial strength with the high tensile strength. Thus, the tensile strength and fatigue strength of the manufactured high-pressure tank 1 can be provided simultaneously.

[0050] In addition, in the heat-setting step, by increasing the amount of heat applied to the spiral layer 22 covering the dome portions 12 compared to the amount of heat applied to the hoop layer 21 covering the body portion 11, the interfacial strength of the spiral layer 22 covering the dome portions 12 can be improved. Accordingly, the tensile strength and fatigue strength of the high-pressure tank 1 can be easily provided simultaneously.

[0051] In the following, the present invention will be described with examples, but the present invention is not limited to the scope of the examples. [Example 1]

[0052] In Example 1, a relationship between an interfacial bond strength as interfacial strength and the tensile strength was investigated for a case where the sizing agent applied to the carbon fiber was changed (Method A), a case where the main agent of the resin impregnated into the fiber was changed from bisphenol F to bisphenol A (Method B1), a case where the curing agent of the resin impregnated into the fiber was changed from an aromatic amine to an acid anhydride (Method B2), and a case where the amount of heat was changed (Method C). In Method A, only the sizing agent of the carbon fiber was different, the O / C ratio was reduced by 75%, and the conditions such as the heat curing condition were the same.

[0053] Fig. Figure 8 is a graph illustrating the result of interfacial bond strength and tensile strength according to Example 1. As indicated by stars in Fig.As illustrated in Figure 8, in the case of Method A, the interfacial bond strength was reduced from 58 MPa to 34 MPa, and an interlaminar shear strength effective for fatigue performance was reduced by 10% (not shown).

[0054] Meanwhile, in the case of Process B1, changing the main resin component resulted in a reduction in interfacial bond strength from approximately 75 MPa to approximately 58 MPa. In contrast, in the case of Process B2, changing the resin curing agent from aromatic amine to acid anhydride resulted in a significant decrease in interfacial bond strength from approximately 75 MPa to approximately 22 MPa.

[0055] Method C resulted in the high heat amount increasing the interfacial bond strength, in other words, the low heat amount decreasing the interfacial bond strength. [Example 2]

[0056] In Example 2, the high-pressure tank was manufactured using a curing agent for the resin impregnated into the fiber that differs between the hoop layer covering the hull portion and the spiral layer covering the dome portions as shown in Table 1, and the tensile strength was examined and a fatigue test was conducted at normal temperature at 90 MPa for the manufactured high-pressure tank. [Comparative Example 1 and Comparative Example 2]

[0057] For comparison, the high-pressure tank was manufactured under the same conditions as in Example 2, provided that the curing agent of the fiber-impregnated resin was not changed. That is, the same curing agent was used for the tire layer and the spiral layer. Tensile and fatigue tests were performed similarly to those in Example 2 for the manufactured high-pressure tank. The type of curing agent or resin was different between Comparative Example 1 and Comparative Example 2. Table 1 shows the results. [Table 1] Hardener High-pressure tank strength Tire layer covering the fuselage section Spiral layer covering dome sections Tensile strength Fatigue test at normal temperature and 90 MPa Example 2 Acid anhydride aromatic amine excellent (200 Mpa) awarded (100,000 times or more) Comparison example 1 Acid anhydride Acid anhydride excellent (200 Mpa) bad (22,000 times) Comparison example 2 aromatic amine aromatic amine good (190 MPa) awarded (100,000 times or more)

[0058] From Table 1, it was found that in the case of Example 2, the tensile strength and fatigue strength of the high-pressure tank could be provided simultaneously. In both cases of Comparative Example 1 and Comparative Example 2, the tensile strength and fatigue strength of the high-pressure tank could not be provided simultaneously. [Example 3]

[0059] In Example 3, the high-pressure tank was manufactured as shown in Table 2 by using the normal thermal aging and the base heat transfer by the IH heater in combination to heat the spiral layer covering the dome sections, and the tensile strength was examined and the fatigue test was conducted at normal temperature at 90 MPa for the manufactured high-pressure tank. [Comparative Example 3 and Comparative Example 4]

[0060] For comparison, the high-pressure tank was manufactured by heating the spiral layer covering the dome sections only with normal thermal aging. The tensile strength was examined and the fatigue test was conducted similarly to Example 3 for the manufactured high-pressure tank. The furnace temperature of the heat-curing furnace was different between Comparative Example 3 and Comparative Example 4. Table 2 shows the result. [Table 2] Heating process High-pressure tank strength Oven temperature IH heating P or N / P Tensile strength Fatigue test at normal temperature and 90 MPa Example 3 140°C P excellent (200 Mpa) excellent Comparison example 3 165°C N / P good (190 MPa) excellent Comparison example 4 140°C N / P excellent (200 Mpa) bad P: IH heating occurs N / P IH heating not done

[0061] From Table 2, it was found that in the case of Example 3, the tensile strength and fatigue strength of the high-pressure tank could be provided simultaneously. In both cases of Comparative Example 3 and Comparative Example 4, the tensile strength and fatigue strength of the high-pressure tank could not be provided simultaneously.

[0062] While the embodiments of the present invention have been described in detail above, the present invention is not limited thereto and may be subjected to various kinds of design changes without departing from the spirit and scope of the present invention as described in the claims. List of reference symbols 1 high-pressure tank 10 lining 11 fuselage section 12 dome section 13 Valve-side mounting socket 14 End-mounted socket 15 resin-impregnated tire wrapping fiber 16 resin-impregnated spiral wound fibers 20 reinforcement layer 21 tire layer 22 spiral layer

Claims

[1] High-pressure tank (1), comprising: a liner (10) having a cylindrically shaped body portion (11) and dome portions (12) arranged at both ends in the axial direction of the body portion (11); a tire layer (21) in which a resin-impregnated fiber (15) is wound and laminated in a tire-shaped winding to cover the body portion (11); and a spiral layer (22) in which a resin-impregnated fiber (16) is wound and laminated in a spiral winding to cover at least the dome portions (12), characterized by , that an interface strength between the fiber (15) and the resin on the tire layer (21) covering the body portion (11) has a low fatigue strength and a high tensile strength compared to an interface strength between the fiber (16) and the resin on the spiral layer (22) covering the dome portions (12). [2] The high-pressure tank (1) according to claim 1, wherein the fiber and / or resin used for the tire layer (21) covering the body portion (11) and the spiral layer (22) covering the dome portions (12) are different. [3] High-pressure tank (1) according to claim 1, wherein heat amounts for heating the resins of the tire layer (21) covering the body portion (11) and the spiral layer (22) covering the dome portions (12) are different. [4] A method for manufacturing a high-pressure tank (1), the high-pressure tank (1) comprising a liner (10) having a cylindrically shaped body portion (11) and dome portions (12) arranged at both ends in the axial direction of the body portion (11), a tire layer (21) in which a resin-impregnated fiber (15) is wound and laminated in a tire-shaped winding to cover the body portion (11), and a spiral layer (22) in which a resin-impregnated fiber (16) is wound and laminated in a spiral winding to cover at least the dome portions (12), the method comprising: a tire layer laminating step for laminating the tire layer (21) covering the body portion (11) to obtain a low fatigue strength and a high tensile strength compared to the spiral layer (22) covering the dome portions (12) for interfacial strength between the fiber (15) and the resin; and a spiral layer lamination step for laminating the spiral layer (22) covering the dome portions (12) to obtain high fatigue strength and low tensile strength compared to the hoop layer (21) covering the body portion (11) for interfacial strength between the fiber (16) and the resin. [5] A method for manufacturing a high-pressure tank (1) according to claim 4, wherein the fiber and / or the resin used in the tire layer laminating step and the spiral layer laminating step are different. [6] A method for producing a high-pressure tank (1) according to claim 4, further comprising a heat-curing step for thermally curing the laminated tire layer (21) and the laminated spiral layer (22), wherein, in the heat-setting step, an amount of heat for heating the tire layer (21) covering the body portion (11) is different from an amount of heat for heating the spiral layer (22) covering the dome portions (12).

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