Manufacturing process for a high-pressure tank

Abstract

Manufacturing process for a high-pressure tank in which a reinforcing layer (30) of fiber-reinforced resin is formed on an outer surface of a lining (2) having a body (21) with a cylindrical shape and end sections (22, 23) with a dome shape formed at the respective ends of the body (21), wherein the process comprises: Preparing the lining (2) and a cylindrical element (31) as well as two dome elements (32, 33) that form the reinforcement layer (30); Shrinking of the lining (2) by cooling of the lining (2); Inserting the lining (2) into the cylindrical element (31) to cover the body (21) of the lining (2) in a shrunken state through the cylindrical element (31); Expanding the lining (2) in its shrunken state to attach the cylindrical element (31) to the body (21) by raising the temperature of the lining (2) inserted into the cylindrical element (31) to a temperature prior to the cooling of the lining (2); and Connecting circumferential edge sections (32a, 33a) of the dome elements (32, 33) with circumferential edge sections (31a) of the cylindrical element (31) attached to the body (21) to cover the end sections (22, 23) of the lining (2) with the dome elements (32, 33) and to form the reinforcement layer (30), where the cylindrical element (31) is cylindrical; When preparing the lining (2) and the cylindrical element (31) as well as the two dome elements (32, 33), the lining (2) and the cylindrical element (31) are prepared such that they satisfy a dimensional relationship in which an outer diameter of the body (21) of the lining (2) is larger than an inner diameter of the cylindrical element (31), wherein when preparing the two dome elements (32, 33), a fiber bundle (F1) is first wound onto a spindle (100) so that it covers an outer surface of the spindle (100), and then divided into two parts by a cutting tool (110) and released from the spindle (100) to form the two dome elements (32, 33), wherein the spindle (100) has a main unit (101) and a shaft section (102) which is connected to the main unit (101).wherein a nozzle (4) is pre-attached to a connecting section between the main unit (101) and the shaft section (102) of the spindle (100) and part of the nozzle (4) is wrapped with the fiber bundle (F1) together with the outer surface of the spindle (100); During the shrinking of the lining (2), the lining (2) is cooled to a temperature at which the outer diameter of the body (21) of the lining (2) is smaller than the inner diameter of the cylindrical element (31); and When the cylindrical element (31) is removed from the body (21), the temperature of the lining (2) is increased to the temperature before the lining (2) cooled, at which the dimensional relationship is satisfied.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to a method for manufacturing a high-pressure tank. 2. Description of the state of the art

[0002] Natural gas vehicles, fuel cell vehicles, etc., use high-pressure tanks to store fuel gas. These types of high-pressure tanks have an airtight lining for the fuel gas, which is coated with a reinforcing layer of fiber-reinforced resin.

[0003] The Japanese patent application JP 2017-141947A, for example, proposes a manufacturing process for such a high-pressure tank. In this manufacturing process, several rounds of a fiber-reinforced resin film are first wound onto a liner body using a film winding process, forming a cylindrical section on the liner body. Next, resin-impregnated fiber bundles are wound onto the cylindrical section and dome-shaped end sections of the liner using a filament winding process, forming a reinforcing section on the outer surface of the liner that is integral with the cylindrical section. Another manufacturing process for a lined tank is the subject of DE 10 2016 105 856 A1. This manufacturing process includes a step for winding arc-shaped or...Web-shaped fibers impregnated with a resin are wound onto a spindle that has a higher strength than the lining, and the wound web-shaped fibers are heated and hardened to form a web layer; a step is taken to withdraw the spindle from the web layer; and the lining is inserted into the web layer after this step. Further processes for manufacturing high-pressure tanks are the subject of JP 2019-148 325 A, EP 3 842 684 A1, and EP 3 851 270 A1. SUMMARY OF THE INVENTION

[0004] In the manufacturing process described in JP 2017-141947A, the cylindrical section is formed by winding several rounds of a single fiber-reinforced resin film onto the body of the lining. However, when the fiber-reinforced resin film is wound directly onto the lining, overstress can occur in the film. This overstress can lead to unexpected deformation of the lining.

[0005] The invention aims to provide a manufacturing process for a high-pressure tank in which a fiber-reinforced resin film or the like is not wound onto the body of the lining when a reinforcing layer is formed on the outer surface of the lining, thereby preventing unexpected deformation of the lining due to overstress at the time of winding. This objective is achieved by the manufacturing process for a high-pressure tank according to claim 1; advantageous embodiments are the subject of the dependent claims.

[0006] A manufacturing method according to one aspect of the invention is a manufacturing method for a high-pressure tank in which a reinforcing layer of fiber-reinforced resin is formed on an outer surface of a lining having a body with a cylindrical shape and end sections with a dome shape formed at the respective ends of the body.The method comprises at least: preparing the lining and a cylindrical element, as well as two dome elements forming the reinforcing layer; shrinking the lining by cooling it; inserting the lining into the cylindrical element to cover the body of the lining in a shrunken state; expanding the lining in the shrunken state to attach the cylindrical element to the body by raising the temperature of the lining inserted into the cylindrical element to a temperature prior to cooling the lining; and joining circumferential edge sections of the dome elements with circumferential edge sections of the cylindrical element attached to the body to cover the end sections of the lining with the dome elements and to form the reinforcing layer.

[0007] According to the invention, the cylindrical element covering the body of the lining and the two dome elements covering the end sections of the lining are prepared in advance, and a reinforcing layer is formed from the cylindrical element and the two dome elements. During the formation of the reinforcing layer, the lining is shrunk by cooling. This shrinkage of the lining also occurs in the radial direction of the body, so that the lining can be easily inserted into the cylindrical element.

[0008] The lining temperature is then raised to its pre-cooling temperature, causing it to expand. This expansion also occurs radially, allowing the cylindrical element to be fitted into the lining body. Thus, the cylindrical element can be integrated with the lining body.

[0009] Since the cylindrical element is integrated with the body of the lining in this way, the circumferential edge sections of the dome elements can be easily connected to the circumferential edge sections of the cylindrical element, and the reinforcing layer consisting of the cylindrical element and the two dome elements can be easily formed on the outer surface of the lining.

[0010] As described above, according to the invention, the reinforcing layer is formed on the outer surface of the lining, instead of wrapping fiber-reinforced resin films or the like onto the lining body. Thus, only one deformation is generated, taking into account the (pre-calculated) tightening clearance between the lining body and the cylindrical element within the lining, by attaching the cylindrical element to the body. Accordingly, unexpected deformation of the lining due to overstressing forces, etc., can be avoided. It should be noted that when fitting the cylindrical element into the body, the temperature of the lining is raised to its pre-cooling temperature. While this temperature increase can be achieved by heating, the lining temperature is preferably raised to reach the ambient temperature.

[0011] The cylindrical element is cylindrical. In preparing the lining and the cylindrical element, as well as the two dome elements, the lining and the cylindrical element are prepared to satisfy a dimensional relationship in which the outer diameter of the lining body is larger than the inner diameter of the cylindrical element. In preparing the two dome elements, a fiber bundle is first wound onto a spindle so that it covers an outer surface of the spindle, and then divided into two parts by a cutting tool and detached from the spindle to form the two dome elements. The spindle has a main unit and a shaft section connected to the main unit. A nozzle is pre-attached to a connecting section between the main unit and the shaft section of the spindle, and part of the nozzle is wrapped with the fiber bundle along with the outer surface of the spindle.During the shrinking process, the lining is cooled to a temperature at which the outer diameter of the lining body is smaller than the inner diameter of the cylindrical element. When the cylindrical element is attached to the body, the lining temperature is raised to its pre-cooling temperature, at which the dimensional relationship is satisfied.

[0012] It should be noted that the “temperature at which the dimensional relationship is satisfied” in this aspect is the temperature at the time of preparation of the lining, the cylindrical element and the two dome elements, i.e. the temperature of the lining immediately before the lining cools down, which is the ambient temperature of the lining and the cylindrical element.

[0013] According to the invention, the lining body and the cylindrical element are cylindrical, and accordingly, when the temperature of the lining is raised to the pre-cooling temperature that satisfies the dimensional relationship at the time the cylindrical element is fitted into the body, the outer circumferential surface of the lining can be made to conform uniformly to the inner circumferential surface of the cylindrical element. In this way, gaps do not readily form between the lining body and the cylindrical element.

[0014] According to the above aspect, when preparing the lining and the cylindrical element as well as the two dome elements, the outer diameter of the body and the inner diameter of the cylindrical element can be adjusted so that a pressure of the cylindrical element pressing against the body of the lining, after completion of the temperature increase of the lining, is less than a tensile or yield stress of a material of the lining.

[0015] According to this aspect, the pressure exerted by the cylindrical element against the lining body, after the temperature increase required to fit the cylindrical element into the body, is less than the yield stress of the lining material. Therefore, the lining can be fitted into the cylindrical element in a state of elastic deformation. Thus, the lining is not damaged by plastic deformation when the cylindrical element is fitted into the body.

[0016] Based on the above considerations, the lining can be made of thermoplastic resin. This means that the lining is made of a thermoplastic resin material that is more ductile and deformable than metal. Consequently, even during plastic deformation of the lining when the cylindrical element is fitted into the body, cracks or similar defects do not readily occur. Because the lining is made of thermoplastic resin, it more easily conforms to the reinforcement layer when filled with high-pressure gas. Furthermore, even under plastic deformation, the lining exhibits slight creep deformation, thus preventing damage to the lining.

[0017] According to the manufacturing process according to the invention for a high-pressure tank, no fiber-reinforced resin film or the like is wound onto the body of the lining when a reinforcing layer is formed on the outer surface of the lining, thereby avoiding unexpected deformation of the lining due to overtension at the time of winding. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The features and advantages as well as the technical and economic significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, showing: Fig. 1 an explanatory cross-sectional view showing the structure of a high-pressure tank produced by a manufacturing process according to an embodiment of the invention; Fig. 2 an explanatory partial cross-sectional view showing the structure of the in Fig. The high-pressure tanks shown in the illustration are shown; Fig. 3 a flowchart to describe processes of the manufacturing process for the high-pressure tank according to the embodiment of the invention; Fig. 4 An explanatory partial cross-sectional view to describe a method for forming a dome element, which is in a Fig. The preparation process is described in section 3; Fig. 5 an explanatory cross-sectional view of the dome element, which is located in the Fig. The preparation process is described in section 3; Fig. 6. A cross-sectional view to describe a method for forming a cylindrical element, which is in Fig. The preparation process is described in section 3; Fig. 7 a cross-sectional view of a lining which is in the Fig. The preparation process is described in section 3; Fig. 8 A schematic perspective view to describe a shrinkage process and an insertion process in which in Fig. 3 manufacturing processes shown; Fig. 9 A schematic perspective view to describe a fitting process in which the Fig. 3 manufacturing processes shown; Fig. 10 A schematic cross-sectional view of the lining and the cylindrical element according to the in Fig. 9 fitting process shown; Fig. 11 a schematic perspective view to describe a in Fig. 3 connection process shown; and Fig. Figure 12 is a schematic cross-sectional view of the lining and a reinforcement layer according to the [reference to figure]. Fig. 11 connection process shown. DETAILED DESCRIPTION OF EXECUTION FORMS

[0019] A manufacturing process for a high-pressure tank 1 according to an embodiment of the invention is described below with reference to the drawings, whereby the aspects described here for the purpose of explaining the invention may sometimes differ from the manufacturing process according to the invention, which is defined by the features of claim 1. Before the description of the manufacturing process, an embodiment of the high-pressure tank 1 is briefly described for illustrative purposes. Although it is described below that the high-pressure tank 1 is a tank filled with high-pressure hydrogen gas and is installed in a fuel cell vehicle, the high-pressure tank 1 can also be used for other purposes. The gas with which the high-pressure tank 1 can be filled is not limited to high-pressure hydrogen gas and it can be filled with other gases, such as...different types of compressed gas, such as compressed natural gas (CNG) and so on, different types of liquefied gas, such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG), and so on. 1. High-pressure tank 1

[0020] The high-pressure tank 1 is an essentially cylindrical high-pressure gas storage container, both ends of which are dome-shaped, as shown in the Fig. 1 and Fig. Figure 2 shows the high-pressure tank 1 being provided with a lining 2 having gas barrier properties and a reinforcing section 3 made of a fiber-reinforced resin covering the outer surface of the lining 2. The reinforcing section 3 has a first reinforcing layer 30 covering the outer surface of the lining 2 and a second reinforcing layer 34 covering the outer surface of the first reinforcing layer 30. An opening is formed at one end of the high-pressure tank 1, and a nozzle 4 is attached to the circumference of the opening. It should be noted that the first reinforcing layer 30 corresponds to the “reinforcing layer” as defined in the invention.

[0021] The lining 2 is a resin or plastic element that forms a receiving chamber 5 filled with high-pressure hydrogen gas. The lining 2 is provided with a cylindrical body 21 and dome-shaped end sections 22, 23, which are formed at the respective ends of the body 21. In the present embodiment, the body 21 extends over a predetermined length in an axial direction X of the high-pressure tank 1 and has a cylindrical shape. The end sections 22, 23 are formed as extensions of the respective ends of the body 21 and have a dome-like shape. The radii of the end sections 22, 23 decrease as they move further away from the body 21, with an opening 22a provided in the middle of the section of the end section 22 where the radius is smallest. A tubular section 22b is provided in the opening 22a.

[0022] The lining material 2 is preferably a resin or metal capable of retaining high-pressure gas introduced into the receiving chamber 5, i.e., exhibiting good gas barrier properties. Examples of resins include polypropylene resins, nylon resins (e.g., nylon 6 resin, nylon 6,6 resin), polycarbonate resins, acrylic resins, acrylonitrile butadiene styrene (ABS) resins, polyamide resins, polyethylene resins, ethylene vinyl alcohol copolymer (EVOH) resin, polyester resins, and similar thermoplastic resins. Examples of metals include aluminum alloys and stainless steel.

[0023] The neck or nozzle 4 is made of a metal material, such as aluminum or an aluminum alloy, which has been formed into a predetermined shape. A valve 6 for filling hydrogen gas into the receiving chamber 5 and for releasing the hydrogen gas from it is attached to the nozzle 4. A sealing element 6a, which comes into contact with the tubular section 22b of the lining 2 and seals the receiving chamber 5 of the high-pressure tank 1, is provided on the valve 6 at a projecting section 32b of the dome element 32, which will be described later.

[0024] The reinforcement section 3 serves to improve the mechanical strength of the high-pressure tank 1, such as stiffness, pressure resistance, etc., by reinforcing the lining 2. The reinforcement section 3 consists of a fiber-reinforced resin in which reinforcing fibers (continuous filaments) are impregnated with resin. In the present embodiment, the reinforcement section 3 has the first reinforcement layer 30, which covers the outer surface of the lining 2, and the second reinforcement layer 34, which covers the outer surface of the first reinforcement layer 30, as described above. The first reinforcement layer 30 is formed integrally from a cylindrical element 31, described later, and dome elements 32, 33, which are connected at its respective ends.

[0025] The cylindrical element 31 and the dome elements 32, 33 are elements in which a plurality of layers of fiber-reinforced resin are laminated from resin-impregnated reinforcing fibers. The reinforcing fibers of the cylindrical element 31 are oriented circumferentially at an angle that is essentially orthogonal to the axial direction X of the cylindrical element 31. In other words, the reinforcing fibers of the cylindrical element 31 are oriented circumferentially. The reinforcing fibers of the dome elements 32, 33 are not oriented circumferentially of the cylindrical element 31, but extend from the vertex towards the circumferential edge sections 32a, 33a of the same in different directions that intersect the circumferential direction.

[0026] In the present embodiment, the reinforcing fibers of the cylindrical element 31 and the reinforcing fibers of the dome elements 32, 33 are not continuous (not connected). This is because the two dome elements 32, 33 are attached to the respective ends of the cylindrical element 31 after the cylindrical element 31 and the two dome elements 32, 33 have been formed separately, as will be described later.

[0027] The second reinforcing layer 34 is a layer into which a layer of fiber-reinforced resin made of resin-impregnated reinforcing fibers is laminated. The second reinforcing layer 34 is intended to cover the outer surface of the first reinforcing layer 30. That is, the second reinforcing layer 34 is a layer that covers the outer surface of the cylindrical element 31 and the dome elements 32, 33. More precisely, the second reinforcing layer 34 is a layer of fiber-reinforced resin whose fibers are oriented such that they extend from one of the two dome elements 32, 33 to the other. The reinforcing fibers of the second reinforcing layer 34 are oriented by helically winding resin-impregnated fiber bundles so that they are inclined with respect to the axial direction X of the cylindrical element 31. The reinforcing fibers press the dome elements 32, 33 against the cylindrical element 31. 2. Manufacturing process for the high-pressure tank 1

[0028] Next, a manufacturing process for the high-pressure tank 1 according to the embodiment of the invention will be described. Fig. Figure 3 is a flowchart describing the processes of the manufacturing process for high-pressure tank 1. The manufacturing process for high-pressure tank 1 comprises a preparation process S1, a shrinking process S2, an insertion process S3, a fitting process S4, a joining process S5, and a process S6 for forming the second reinforcing layer, as shown in Figure 3. Fig. 3 shown. 2-1. Preparation process S1

[0029] In preparation process S1, the lining 2, the cylindrical element 31, and the two dome elements 32 and 33, which form the first reinforcement layer 30, are prepared. Note that the lining 2 and the cylindrical element 31, which satisfy a dimensional relationship such that the outer diameter D1 of the body 21 of the lining 2 is larger than the inner diameter D2 of the cylindrical element 31, are prepared in preparation process S1, as will be described later. First, the procedure for forming the two dome elements 32 and 33 to be prepared is described below. Method for forming the dome elements 32, 33

[0030] At the in Fig. In the method for forming the dome elements 32, 33 shown in Figure 5, for example, a resin-impregnated fiber bundle F1 is wound onto an outer surface of a spindle 100 by a filament winding process (FW process), as shown in Figure 5. Fig. Figure 4 shows. Specifically, the spindle 100 has a main unit 101 and a shaft section 102 that extends from one end of the main unit 101 to the outside.

[0031] The main unit 101, viewed from the axial direction of the shaft section 102, is circular in shape. A groove section 101a is provided in the center of the outer circumferential surface of the main unit 101, extending circumferentially over its entire circumference. The outer surface of the spindle 100 has a shape in which the domed end sections 22, 23 are connected without the body 21 of the lining 2 prepared in preparation process S1, with the groove section 101a positioned corresponding to the seam of the lining. The shaft section 102 is rotatably mounted by a rotary mechanism (omitted in the figure).

[0032] In the formation of the dome elements 32, 33, the fiber bundle F1 is first wound onto the spindle 100 so that it covers its outer surface by rotating the spindle 100. At this point, the cylindrical, projecting section 32b with a through-hole 32c is also formed by winding the fiber bundle F1 onto the outer surface of the shaft section 102, as shown in Fig. Figure 5 illustrates this. The fiber bundle F1 is wound at an angle that intersects the axial direction of the shaft section 102 by, for example, 30 to 50 degrees. It should be noted that while the material of the spindle 100 is not particularly restricted, metal is preferred to ensure sufficient strength so that it does not deform during the winding of the fiber bundle F1.

[0033] Although the resin with which the fiber bundle F1 is impregnated is not particularly restricted, a thermosetting resin, for example, can be used. Preferred examples of thermosetting resins that can be used are phenolic resins, melamine resins, urea-formaldehyde resins, and epoxy resins. In this arrangement, the fiber bundle F1 is wound onto the spindle 100 in a state where the thermosetting resin has not yet cured and is then heated. Epoxy resins are particularly preferred due to their mechanical strength properties. Epoxy resins are flowable in their uncured state and, once cured, form a strong cross-linked structure.

[0034] It should also be noted that thermoplastic resins can be used as the resin with which the fiber bundle F1 is impregnated. Examples of thermoplastic resins that can be used are polyetheretherketone, polyphenylene sulfide, polyacrylate esters, polyimide, and polyamide. In this arrangement, the fiber bundle F1 is wound onto the spindle 100 in a state where the thermoplastic resin is heated and softened, after which the thermoplastic resin is cooled and cured. It should be noted that in this description, both the thermal curing of the thermosetting resin and the curing of the softened thermoplastic resin by cooling are collectively referred to as curing the resin.

[0035] Examples of fibers that can be used to form the fiber bundle F1 include glass fibers, aramid fibers, boron fibers, and carbon fibers. Carbon fibers are particularly preferred due to their lightness, mechanical strength, and other properties.

[0036] Next, the wound article (fiber bundle F1), which is wound onto the outer surface of the spindle 100, is divided into two parts using a cutting tool 110 (see Fig. 4) The divided wound article is then released from the spindle 100, creating the two coupling elements 32, 33, as shown in Fig. 5 shown.

[0037] In particular, the nozzle 4 is attached to the outer surface of the preceding section 32b in the Fig. The cutting tool is attached to the state shown in Figure 4. In a state where the resin impregnating the fiber bundle F1 of the wound article has cured, the blade tip of the cutting tool 110 is inserted into the groove section 101a of the spindle 100 while the spindle 100 is rotated. In this way, the fiber bundle F1 can be cut by the cutting tool 110, and the wound article is divided into two parts. The wound article is then released from the spindle 100 in a state where the resin of the wound article (fiber bundle F1) remains cured, thus forming the two coupling elements 32, 33.It should be noted that the cutting tool 110 is not particularly limited, and examples that can be used include arrangements in which a blade is provided on a circumferential surface of a rotating disk, arrangements in which a blade is formed on a side surface of a thin plate, and arrangements in which the fiber bundle F1 is cut using a laser beam.

[0038] The cutting is performed by the cutting tool 110 in a state where the resin with which the fiber bundle F1 is impregnated has hardened. Therefore, deformation of the fiber bundle F1 during cutting can be suppressed, and deformation of the two dome elements 32, 33 when removed from the spindle 100 can be suppressed.

[0039] If the resin of the fiber bundle F1 (i.e., the two dome elements 32, 33) consists of a thermosetting resin, the method for curing the fiber bundle F1 is not particularly restricted, and the fiber bundle F1 is cured under curing conditions (heating temperature and heating time) that correspond to the type of resin. On the other hand, if the resin of the fiber bundle F1 consists of a thermoplastic resin, the resin of the fiber bundle F1 is cured by cooling the fiber bundle F1 from a state in which the resin is fluid, as in a method for curing the fiber bundle F1. The dome elements 32, 33 thus formed are shaped into forms that cover the outer surfaces of the end sections 22, 23 of the lining 2.

[0040] Although an example of winding the resin-impregnated fiber bundle F1 onto the outer surface of the spindle 100 has been described here, an arrangement can be chosen in which a fiber bundle not impregnated with resin is wound onto the outer surface of the spindle 100 to form a wound article which is then impregnated with resin and cured.

[0041] Although an example of cutting fiber bundle F1 with a cutting tool 110 in a state where the resin is cured has been described here, fiber bundle F1 can also be cut with the cutting tool 110 without the resin of fiber bundle F1 being cured. In this arrangement, fiber bundle F1 can be cured after being cut by the cutting tool 110.

[0042] It should be noted, however, that if the resin of the fiber bundle F1 is not cured, the resin will have a viscosity and the fiber bundle F1 cannot be easily removed from the spindle 100 (the fiber bundle F1 will be easily deformed). Accordingly, the deformation of the fiber bundle F1 is preferably suppressed, for example, by coating the surface of the spindle 100 with a mold release agent before winding the fiber bundle F1, or by reducing the rate at which the two coupling elements 32, 33 detach from the spindle 100.

[0043] Although an example has been described here in which the nozzle 4 is attached to the outer surface of the preceding section 32b after the fiber bundle F1 has been wound onto the outer surface of the spindle 100, in the invention the nozzle is attached in advance to a connecting section between the main unit 101 and the shaft section 102 of the spindle 100, and a portion of the nozzle is wound with the fiber bundle F1 together with the outer surface of the spindle 100 in this state. In this arrangement, a portion of the nozzle is covered and held in place by the fiber bundle F1, thereby enabling the nozzle to be firmly fixed by the fiber bundle F1. Method for forming the cylindrical element 31

[0044] The cylindrical element 31 is formed, for example, by winding a fiber web F2 onto an outer surface of a cylindrical spindle 200, as in Fig. Figure 6 shows that the outer diameter of the spindle 200 corresponds to the inner diameter D2 of the cylindrical element 31. While the material of the spindle 200 is not particularly restricted, metal is preferred to ensure sufficient strength so that it does not deform when the fiber web F2 is applied.

[0045] In forming the cylindrical element 31, the fiber web F2, which is unwound from a roll, etc., is wound several times onto the spindle 200 while the spindle 200 is rotated circumferentially by a rotary mechanism (omitted in the figure). The fiber web F2 is a web or film of reinforcing fibers drawn in one direction and impregnated with resin. The fiber web F2 is wound onto the spindle 200, with the reinforcing fibers following the circumferential direction of the spindle 200. Accordingly, the reinforcing fibers are aligned circumferentially, and the cylindrical element 31 with the inner diameter D2 is formed.

[0046] Although a so-called unidirectional (UD) film or web is used for the fiber web F2, in which, for example, a plurality of fiber bundles oriented in the same direction are woven in by binding strands, a fiber web can be used in which a plurality of fiber bundles oriented in the same direction and a plurality of fiber bundles that, for example, cut orthogonally into the plurality of fiber bundles are woven, or the like.

[0047] It should be noted that examples of the reinforcing fibers for the fiber web F2 may be the same as the materials described for the fiber bundle F1, and examples of the resin with which the reinforcing fibers are impregnated may be the same as the materials described for the fiber bundle F1.

[0048] The cylindrical element 31 is shaped such that the thicknesses of the circumferential edge sections 31a gradually decrease towards the ends in the axial direction X, as shown in Fig. Figure 6 shows that, according to this shape, when the circumferential edge sections 31a of the cylindrical element 31 and the circumferential edge sections 32a, 33a of the dome elements 32, 33 are placed on top of each other, as shown in the Fig. 1 and Fig. 2 shown, less easily a stepped section is formed at the connecting sections of the outer surface of the cylindrical element 31 and the outer surfaces of the two dome elements 32, 33.

[0049] To reduce the thickness at both ends of the cylindrical element 31 in the axial direction X, the fiber bundles can be woven such that the thickness of the fiber bundles at the end section of the fiber web F2 gradually decreases in the axial direction X (latitudinal direction), or the winding width of the fiber web F2 can be gradually reduced. Alternatively, the thickness of both ends of the cylindrical element 31 can be gradually reduced in the axial direction X by pressing them through a roller or similar device. It should be noted that the thickness of the circumferential edge sections 32a, 33a of the dome elements 32, 33 can also be reduced compared to other sections by pressing with a roller or similar device.

[0050] If the resin of fiber web F2 is a thermosetting resin, fiber web F2 can be cured under predetermined curing conditions (heating temperature and heating time) in a state where fiber web F2 is wound onto spindle 200, in the same way as fiber bundle F1. Conversely, if the resin of fiber web F2 is a thermoplastic resin, it can be cured by cooling in a state where fiber web F2 is wound onto spindle 200, in the same way as fiber bundle F1.

[0051] After the resin has cured, the cylindrical element 31 is removed from the spindle 200. The curing of the resin improves the dimensional stability of the cylindrical element 31. Consequently, the cylindrical element 31 can be easily detached from the spindle 200, and deformation of the cylindrical element 31 during removal from the spindle 200 is prevented.

[0052] It should be noted that this is an example where the fiber web F2 is wound onto the outer surface of the spindle 200 to form the cylindrical element 31. However, the cylindrical element 31 can also be formed by winding resin-impregnated fiber bundles onto the outer surface of the spindle 200 using the FW process. Alternatively, the cylindrical element 31 can be formed using a so-called centrifugal winding process (CW process), in which fiber webs are applied to the inner surface of the rotating spindle 200. Procedure for forming the lining 2

[0053] The lining 2 is designed such that the outer diameter D1 of the body 21 of the lining 2 is larger than the inner diameter D2 of the cylindrical element 31, as shown in Fig. Figure 7 illustrates this. Specifically, a body element (omitted in the figure), corresponding to body 21, and two end elements (omitted in the figure), corresponding to end sections 22 and 23, are prepared. The opening 22a is formed at the apex of the dome-shaped end section corresponding to end section 22, and the tubular section 22b is formed within the opening 22a.

[0054] Next, the end elements are connected to the respective ends of the prepared body part by welding, thermal fusion, or the like. In this way, the lining 2 can be formed with the cylindrical body 21 and the dome-shaped end sections 22, 23, which are continuously formed at the respective ends of the body 21, as shown in Fig. 7 shown.

[0055] In the present embodiment, the lining 2 is fitted to / into the cylindrical element 31, the fitting process described below being carried out using a shrink fit by cooling (compression shrink fit). Accordingly, in the pre-cooling state, the outer diameter D1 of the body 21 is larger than the inner diameter D2 of the cylindrical element 31 under the same temperature conditions (especially at room temperature). This pre-cooling state is a state in which the inner surface of the lining 2 is permanently open at ambient temperature (especially at room temperature).

[0056] Furthermore, in the present embodiment, the material of the body element and the two end elements (i.e., the material of the lining 2) consists of resin or metal, as described above. These materials are materials that shrink at low temperatures, and in particular, of the various types of resin, the thermoplastic resin is a material that exhibits higher shrinkage properties at low temperatures compared to the fiber-reinforced resin from which the cylindrical element 31 is made. Accordingly, the lining 2, when cooled to a lower temperature (e.g., a temperature lower than normal temperature), can shrink (thermal contraction) so that the reduced outer diameter D1 can be smaller than the inner diameter D2 of the cylindrical element 31. 2-2. Shrinkage process S2

[0057] In the shrinking process S2, the lining 2 is shrunk by cooling it. Specifically, in the shrinking process S2, the lining 2 is cooled to a temperature at which the outer diameter D1 of the lining body 21 is smaller than the inner diameter D2 of the cylindrical element 31 (in particular, a temperature lower than room temperature), as shown in Fig. 8 shown.

[0058] The cooling method is not particularly limited as long as the lining 2 can be cooled. For example, the lining 2 can be cooled by storing it in a freezer or cold storage chamber or the like; by blowing wind colder than room temperature onto the surface of the lining 2, thus cooling it; or by bringing the lining 2 into contact with a substance colder than room temperature (water, dry ice, etc.). Alternatively, the receiving chamber 5 can be filled with a refrigerant cooler than room temperature through the tubular section 22b and the opening 22a of the lining 2, and thus cooled.

[0059] It should be noted that the cooling temperature of the lining 2 is not limited, particularly as long as the temperature is lower than the temperature of the cylindrical element 31 and the outer diameter D1 of the body 21 of the lining 2 is smaller than the inner diameter D2 of the cylindrical element 31. For example, the cooling temperature is in a range of about -30°C to 10°C, and the lining 2 is preferably cooled in a temperature range in which the material of the lining 2 does not exhibit low-temperature brittleness. 2-3. Insertion process S3

[0060] In insertion process S3, the lining 2 is inserted into the cylindrical element 31, so that the cylindrical element 31 covers the body 21 of the lining 2 in the shrunken state from shrinking process S2, as shown in Fig. Figure 8 shows that the lining 2 is shrunk during the shrinking process S2 such that the outer diameter D1 of the body 21 of the lining 2 is smaller than the inner diameter D2 of the cylindrical element 31, and accordingly the lining 2 can be easily inserted into the cylindrical part 31. 2-4. Fitting process S4

[0061] In the fitting process S4, the temperature of the lining 2 inserted into the cylindrical element 31 is reduced to the temperature before cooling in the shrinking process S2, causing the shrunken lining 2 to expand and the cylindrical element 31 to fit the body 21, as described in the Fig. 9 and Fig. 10 shown.

[0062] The "pre-cooling temperature" is a temperature that satisfies the dimensional relationship at which the outer diameter D1 of the lining body 21 is larger than the inner diameter D2 of the cylindrical element 31. Accordingly, the temperature increase of the lining 2 causes it to expand, and this expansion also occurs radially, allowing the cylindrical element 31 to be adapted to the lining body 21. Thus, the cylindrical element 31 can be integrated with the lining body 21.

[0063] The temperature of the lining 2 can be increased by a heating device or the like, but in the present embodiment, the temperature of the lining 2 is gradually increased to ambient temperature (room temperature) immediately before cooling. That is, the cooled lining 2 is left to stand under so-called ordinary temperature and normal pressure conditions. Ordinary temperature and normal pressure conditions here are, for example, a temperature range of 15°C to 25°C for ordinary temperature and atmospheric pressure for normal pressure. By increasing the temperature in this way, the lining 2 can be fitted into the cylindrical element 31, with the outer surface of the body 21 of the lining 2 following the inner surface of the cylindrical element 31, while thermal shock to the lining 2 due to the temperature increase is suppressed.

[0064] Furthermore, in the present embodiment, the body 21 of the lining 2 and the cylindrical element 31 are cylindrical, and accordingly, when the temperature of the lining 2 rises to its pre-cooling temperature during the fitting process, the outer circumferential surface of the lining 2 can be caused to conform uniformly to the inner circumferential surface of the cylindrical element 31. In this way, the formation of a gap between the body 21 of the lining 2 and the cylindrical element 31 is less likely.

[0065] Referring again to preparation process S1, the relationship between the lining body 21 and the cylindrical element 31 is described in detail below. For the outer diameter D1 of the lining body 21 and the inner diameter D2 of the cylindrical element 31 in preparation process S1, the following conditions hold: (1) outer diameter D1 < inner diameter D2 at the cooling temperature in shrinkage process S2, and (2) outer diameter D1 > inner diameter D2 at the temperature after expansion in fitting process S4 (specifically, the temperature in preparation process S1). The lining body 21 can be fitted into the cylindrical element 31 under either of the aforementioned conditions (1) and (2).

[0066] In addition, the outer diameter D1 of the body 21 and the inner diameter D2 of the cylindrical element 31 are preferably adjusted so that, after the temperature rise of the lining 2 has ceased, the pressure of the cylindrical element 31 pressing against the body 21 of the lining 2 is less than the yield stress of the lining material 2.

[0067] According to these settings, the expansion force of the lining 2 is calculated using E × α × dT, where E represents the elastic modulus of the lining 2 material, α represents the linear coefficient of thermal expansion of the material, and dT represents the temperature change from the cooled state to full expansion. The pressure of the cylindrical element 31 pressing against the lining body 21 can be calculated using standard material mechanics calculations, etc., taking into account the outer diameter D1 of the lining body 21 before cooling and the inner diameter D2 of the cylindrical element 31, along with this expansion force.

[0068] By carrying out the adjustments in this manner, the pressure of the cylindrical element 31 pressing against the body 21 of the lining 2 is less than the yield stress of the lining 2 material, and consequently, the lining 2 can be fitted into the cylindrical element 31 in a state where the lining 2 is elastically deformed. Therefore, the lining 2 is not damaged by plastic deformation during the fitting process S4.

[0069] As described above, in the present embodiment, the first reinforcement layer 30 is formed on the outer surface of the lining 2, instead of wrapping fiber-reinforced resin sheets or films, fiber bundles, or the like onto the body 21 of the lining 2. Thus, only one deformation, taking into account the tightening clearance between the body 21 of the lining 2 and the cylindrical element 31 (calculated in advance) in the lining 2, is generated by the fitting process S4, and accordingly, unexpected deformation of the lining 2 due to overstressing forces, etc., can be avoided.

[0070] It should be noted that if the lining 2 is made of a thermoplastic resin, cracks and the like will not readily occur in the lining 2, even if there is plastic deformation of the lining 2 during the fitting process S4, since thermoplastic resin materials are more ductile than metal. 2-5. Connection process S5

[0071] In the joining process S5, the circumferential edge sections 32a, 33a of the dome elements 32, 33 are joined to the circumferential edge sections 31a of the cylindrical element 31 into which the body 21 is fitted, so that the dome elements 32, 33 cover the end sections 22, 23 of the lining 2, as shown in the Fig. 11 and Fig. 12 is shown, which forms the first reinforcement layer 30.

[0072] In particular, the circumferential edge sections 31a of the cylindrical element 31 and the circumferential edge sections 32a, 33a of the dome elements 32, 33 are joined together, one being on the inside and the other on the outside. This allows the cylindrical element 31 and the dome elements 32, 33 to be more strongly connected to each other. Fig. Figure 12 shows an example of this fit, in which the circumferential edge sections 31a of the cylindrical element 31 are located on the inside and the circumferential edge sections 32a, 33a of the dome elements 32, 33 are located on the outside. In the present embodiment, the cylindrical element 31 is integrated with the body 21 of the lining during the fitting process S4. Accordingly, the circumferential edge sections 32a, 33a of the dome elements 32, 33 can be easily connected to the circumferential edge sections 31a of the cylindrical element 31, and the first reinforcing layer 30, consisting of the cylindrical element 31 and the two dome elements 32, 33, can be easily formed on the outside of the lining 2.

[0073] When the cylindrical element 31 and the dome elements 32, 33 are joined together, an adhesive can be applied to the mating surfaces of the cylindrical element 31 and the dome elements 32, 33. This arrangement can more reliably prevent subsequent detachment of the cylindrical element 31 and the dome elements 32, 33. The material of the adhesive is not particularly restricted, but the use of a thermosetting resin, such as epoxy resin or the like, is preferred. A resin of the same composition as that of the cylindrical element 31 or the dome elements 32, 33 can also be used as an adhesive.

[0074] Although an example of joining the circumferential edge sections 31a of the cylindrical element 31 and the circumferential edge sections 32a, 33a of the dome elements 32, 33 has been described here, an arrangement can be chosen in which the circumferential edge sections 31a of the cylindrical element 31 and the circumferential edge sections 32a, 33a of the dome elements 32, 33 abut each other and are joined by an adhesive. 2-6. Process S6 for forming the second reinforcement layer

[0075] In process S6 for forming the second reinforcement layer, the second reinforcement layer 34 is formed from fiber-reinforced resin in such a way that it covers the outer surface of the first reinforcement layer 30, as shown in Fig. Figure 1 shows that the reinforcement section 3 can be formed with the first reinforcement layer 30 and the second reinforcement layer 34.

[0076] In the formation of the second reinforcing layer 34, a resin-impregnated fiber bundle is wound in layers by helical winding on the surface of the first reinforcing layer 30 using the FW process. Helical winding is a winding method in which the winding proceeds obliquely (within a range of not less than 10° and not more than 60°) to the axial direction X of the cylindrical element 31 over the dome elements 32, 33. The number of layers of the fiber bundle to be wound is not particularly limited as long as the strength of the second reinforcing layer 34 is ensured, but is, for example, between two and ten layers.

[0077] It should be noted that examples of the reinforcing fiber material for the fiber bundle may be the same as the materials described by way of example with respect to fiber bundle F1, and examples of the resin with which the reinforcing fibers are impregnated may be the same as the resin materials described by way of example with respect to fiber bundle F1.

[0078] After the fiber bundle has been wound onto the outer surface of the first reinforcement layer 30, the second reinforcement layer 34 is thermally cured if the resin impregnated with the fiber bundle is a thermosetting resin. If the resin impregnated with the fiber bundle is a thermoplastic resin, the second reinforcement layer 34 is cured by cooling, either by cooling in still air or by forced cooling. After the second reinforcement layer 34 has been formed in this way, the valve 6 is attached to the nozzle 4, thereby opening the high-pressure tank 1 as shown in Fig. 1 shown, will be completed.

[0079] According to the present embodiment, no fiber-reinforced resin web or film or similar is wound onto the body 21 of the lining 2 when the first reinforcement layer 30 is formed on the outer surface of the lining 2, thereby avoiding unexpected deformation of the lining 2 due to overstress at the time of winding.

[0080] The embodiment disclosed here is to be understood in all respects as exemplary and not limiting. The scope of the invention is not defined by the embodiment described above, but by the claims.

[0081] For example, in the present embodiment, the shape of the lining body was described as cylindrical, and the shape of the cylindrical element was also described as cylindrical. However, the shape is not particularly limited as long as the cylindrical element can be adapted to the lining body and can be a flattened shape (elliptical shape), a polygonal shape, or the like.

[0082] In the present embodiment, an example of forming the two dome elements using the FW method has also been described, but the invention is not limited thereto. For example, the two dome elements can be formed by applying fiber bundles to the surface of dome-shaped forms under pressure by a roller using a belt arrangement process.

[0083] Although the present embodiment describes an example of a first reinforcing layer consisting of three elements (cylindrical elements and dome elements), the invention is not limited to this. For example, the first reinforcing layer can be formed from four or more elements (two or more cylindrical elements and dome elements). In this arrangement, the two or more cylindrical elements can be joined together, and then the dome elements can be connected to their ends. Alternatively, a dome element and a cylindrical element can each be joined together, and then these can be connected to each other.

Claims

[1] Manufacturing process for a high-pressure tank in which a reinforcing layer (30) of fiber-reinforced resin is formed on an outer surface of a lining (2) having a body (21) with a cylindrical shape and end sections (22, 23) with a dome shape formed at the respective ends of the body (21), wherein the process comprises: Preparing the lining (2) and a cylindrical element (31) as well as two dome elements (32, 33) that form the reinforcement layer (30); Shrinking of the lining (2) by cooling of the lining (2); Inserting the lining (2) into the cylindrical element (31) to cover the body (21) of the lining (2) in a shrunken state through the cylindrical element (31); Expanding the lining (2) in its shrunken state to attach the cylindrical element (31) to the body (21) by raising the temperature of the lining (2) inserted into the cylindrical element (31) to a temperature prior to the cooling of the lining (2); and Connecting circumferential edge sections (32a, 33a) of the dome elements (32, 33) with circumferential edge sections (31a) of the cylindrical element (31) attached to the body (21) to cover the end sections (22, 23) of the lining (2) with the dome elements (32, 33) and to form the reinforcement layer (30), where the cylindrical element (31) is cylindrical; When preparing the lining (2) and the cylindrical element (31) as well as the two dome elements (32, 33), the lining (2) and the cylindrical element (31) are prepared such that they satisfy a dimensional relationship in which an outer diameter of the body (21) of the lining (2) is larger than an inner diameter of the cylindrical element (31), wherein when preparing the two dome elements (32, 33), a fiber bundle (F1) is first wound onto a spindle (100) so that it covers an outer surface of the spindle (100), and then divided into two parts by a cutting tool (110) and released from the spindle (100) to form the two dome elements (32, 33), wherein the spindle (100) has a main unit (101) and a shaft section (102) which is connected to the main unit (101).wherein a nozzle (4) is pre-attached to a connecting section between the main unit (101) and the shaft section (102) of the spindle (100) and part of the nozzle (4) is wrapped with the fiber bundle (F1) together with the outer surface of the spindle (100); During the shrinking of the lining (2), the lining (2) is cooled to a temperature at which the outer diameter of the body (21) of the lining (2) is smaller than the inner diameter of the cylindrical element (31); and When the cylindrical element (31) is removed from the body (21), the temperature of the lining (2) is increased to the temperature before the lining (2) cooled, at which the dimensional relationship is satisfied. [2] Manufacturing method according to claim 1, wherein, during the preparation of the lining (2) and the cylindrical element (31) and the two dome elements (32, 33), the outer diameter of the body (21) and the inner diameter of the cylindrical element (31) are adjusted such that a pressure of the cylindrical element (31) pressing against the body (21) of the lining (2) is less than a yield stress of a material of the lining (2) after the temperature increase of the lining (2) has been completed. [3] Manufacturing method according to claim 1 or 2, wherein the lining (2) is made of thermoplastic resin.

Images