METHOD OF MANUFACTURING HIGH-PRESSURE TANK
20210370577 · 2021-12-02
Assignee
Inventors
Cpc classification
B29C53/56
PERFORMING OPERATIONS; TRANSPORTING
B29C53/602
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A method of manufacturing a high-pressure tank includes forming a winding layer on an outer periphery of a liner, to prepare a preform, placing the preform in a mold, and supplying a resin composition to the winding layer, and formation of the winding layer includes winding of a tow prepreg, and winding of a fiber bundle.
Claims
1. A method of manufacturing a high-pressure tank, comprising: forming a winding layer on an outer periphery of a liner, to prepare a preform; and placing the preform in a mold, and supplying a resin composition to the winding layer, wherein formation of the winding layer includes winding of a tow prepreg, and winding of a fiber bundle.
2. The method according to claim 1, wherein the winding layer is formed by winding the tow prepreg, and then winding the fiber bundle on an outer periphery of the tow prepreg.
3. The method according to claim 1, wherein the winding layer is formed, such that at least one of layers that constitute the winding layer is formed by winding a mixture of the tow prepreg and the fiber bundle.
4. The method according to claim 1, wherein the resin composition starts being supplied after a viscosity of a resin contained in the tow prepreg is reduced to be lower than that of the resin during winding.
5. The method according to claim 1, wherein a curing agent that cures a resin contained in the tow prepreg at a temperature lower than a temperature of the mold is added to the resin.
6. The method according to claim 1, wherein winding of the tow prepreg and winding of the fiber bundle are performed with a multi-supply filament winding device, or a continuous multi-supply filament winding apparatus.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:
[0020]
[0021]
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DETAILED DESCRIPTION OF EMBODIMENTS
1. Structure of High-Pressure Tank
[0037]
[0038] The liner 11 is a hollow member that defines interior space of the high-pressure tank 10. The liner 11 may be formed of any known material, provided that the material can hold a substance (such as hydrogen) contained in the interior space, without leaking it. For example, the liner 11 is formed of nylon resin, polyethene synthetic resin, or metal, such as stainless steel, or aluminum. The thickness of the liner 11 is not particularly limited, but is preferably in the range of 0.5 mm to 1.0 mm.
[0039] The reinforcement layer 12 is a laminate consisting of a plurality of fiber layers, and has resin that impregnates the fibers and is cured. The fiber layers are formed by winding fiber bundles around an outer surface of the liner 11, to provide any number of layers corresponding to a predetermined thickness. The thickness of the reinforcement layer 12 is about 10 mm to 30 mm, though it is not particularly limited since it is determined depending on the required strength. In the case where the high-pressure tank is used for a fuel cell vehicle, in particular, the reinforcement layer needs to be formed with a large thickness, so as to ensure sufficient strength, which makes it highly difficult to impregnate the fiber layer having the large thickness with resin. One half of the reinforcement layer 12 (and a winding layer 21 that will be described later) in terms of the thickness, which is closer to the liner 11, may be referred to as “inner layer side”, and the other half of the reinforcement layer 12 remote from (or on the radially outer side of) the liner 11 may be referred to as “outer layer side”.
[0040] Carbon fibers are used for the fiber bundles of the reinforcement layer 12, and each fiber bundle, which is a bundle of carbon fibers, is in the form of a belt having a given cross-sectional shape (e.g., a rectangular cross section). More specifically, the cross-sectional shape, though it is not particular limited, is a rectangle having a width of about 6 mm to 10 mm, and a thickness of about 0.1 mm to 0.15 mm. While the amount of carbon fibers included in the fiber bundle is also not particularly limited, the fiber bundle may consist of about 36000 carbon fibers.
[0041] The resin that impregnates the fibers and is cured in the reinforcement layer 12 is not particularly limited, provided that it can increase the strength of the fibers. For example, the resin may be selected from thermosetting resins that are cured by heat, such as epoxy resin, unsaturated polyester resin, etc. including an amine-based or anhydride curing accelerator, and a rubber-based reinforcing agent. The resin may also be selected from resin compositions having epoxy resin as a base compound, with which a curing agent is mixed for curing of the base compound. While the base compound is mixed with the curing agent and cured, the resin composition as the mixture of the base compound and the curing agent is caused to reach the fiber layers and penetrate through them, so that the resin is automatically cured.
[0042] The protection layer 13 is placed on the outer periphery of the reinforcement layer 12 as needed. When the protection layer 13 is provided, glass fibers are wound around the reinforcement layer 12, and are impregnated with resin. The resin impregnating the glass fibers may be selected in the same way as the reinforcement layer 12. The protection layer 13 can give impact resistance to the high-pressure tank 10. The thickness of the protection layer 13 is not particularly limited, but may be about 1.0 mm to 2.0 mm.
[0043] The caps 14 are respectively attached to two opening ends of the liner 11, and one of the caps 14 functions as an opening that communicates the interior of the high-pressure tank 10 with the exterior, and also functions as a mounting part for mounting a pipe or valve to the high-pressure tank 10. Also, the caps 14 function as mounting parts for mounting the liner 11 on a multi-supply filament winding device that will be described later, when the reinforcement layer 12 is formed. Where the liner 11 is formed of metal, there is no need to separately provide caps, but parts shaped like the caps may be formed continuously with the liner 11.
2. Structure of Preform
[0044] A preform 20 is an intermediate member that eventually provides the high-pressure tank 10, and has at least the liner 11 and a winding layer 21. Namely, the preform 20 is a member in which the winding layer 21 (or a fiber layer 23 included in the winding layer 21) has not been impregnated with resin.
[0045] The winding layer 21 is supplied with and impregnated with a resin composition, which is then cured, as described later, to provide the reinforcement layer 12 of the high-pressure tank 10. In this embodiment, the winding layer 21 includes a TPP layer 22 and a fiber layer 23, as shown in
[0046] The TPP layer 22 is formed by winding fiber bundles (tow prepreg, which will be denoted as “TPP”) impregnated in advance with resin that is in a partially cured state. The fiber bundle that provides the TPP is not particularly limited, but may be considered as the same fiber bundle as the one described above, and may be in the form of a belt as a bundle of carbon fibers, which has a given cross-sectional shape (e.g., a rectangular cross section).
[0047] The resin contained in the TPP is not particularly limited, but is preferably of the same type as the resin with which the fiber layer 23 is impregnated as will be described later. In this case, the resin of the TPP is likely to be integrated with the resin impregnating the fiber layer 23, which makes it less likely or unlikely to cause a problem in terms of homogeneity or peel-off. Thus, the resin contained in the TPP may be selected from thermosetting resins that are cured by heat, such as epoxy resin, unsaturated polyester resin, etc. including an amine-based or anhydride curing accelerator, and a rubber-based reinforcing agent. The resin may also be selected from resin compositions having epoxy resin as a base compound, with which a curing agent is mixed for curing of the base compound. Also, a low-temperature curing agent may be added to the resin contained in the TPP layer. The low-temperature curing agent starts curing the resin at a relatively low temperature (specifically, a temperature lower than the temperature of a mold 40), and provides high reactivity. High-temperature heat generated at this time can be used for heating the resin composition supplied, from the inner layer side, thus achieving both high-speed impregnation and high-speed curing. The low-temperature curing agent is not limited to any particular agent, but may be selected from, for example, xylenediamide, diethylene triamine, and triethylenetetramine.
[0048] In this embodiment, the TPP layer 22 is placed (wound) on the inner layer side of the winding layer 21. Thus, even when the thickness of the winding layer 21 needs to be increased so as to increase the thickness of the reinforcement layer 12, the resin included on the inner layer side can be supplemented by the resin of the TPP, and the winding layer 21 can ensure homogenous resin distribution, and high performance as the reinforcement layer. Also, since the resin is placed in advance in a portion that is hard to be impregnated with resin, the fiber layer 23 can be promptly impregnated with resin, and efficient impregnation can be achieved, namely, the productivity of the high-pressure tank can be improved. The TPP layer 22 on the inner layer side preferably includes at least the innermost layer that contacts with the liner 11, and only the one layer that contacts with the liner 11 may be provided by the TPP layer.
[0049] The fiber layer 23 consists of layers other than the TPP layer 22, in the winding layer 21, and the layers are formed by winding fiber bundles that are not impregnated with resin. Thus, in this embodiment, the fiber layer 23 is placed (wound) on the radially outer side of the TPP layer 22. Preferably, one layer that contact with the liner 11, or two or more layers laminated on the liner 11, on the inner layer side, provide the TPP layer 22, and the outer side of the TPP layer 22 provides the fiber layer 23, as shown in
[0050] In this embodiment, the TPP layer 22 and the fiber layer 23 are formed by helically winding TPP 22a and fiber bundles 23a as shown in
3. Manufacturing Method 1
[0051]
[0052] Step S11 of Forming the TPP Layer
[0053] In step S11 of forming the TPP layer (which may be referred to as “step S11”), the TPP 22a is wound on the outer periphery of the liner 11.
[0054] In step S11, the TPP 22a is wound around the liner 11, to form the TPP layer 22. Namely, in this embodiment, one layer that contacts with the liner 11, or two or more layer wound outside the one layer, is/are formed of the TPP 22a, to provide the TPP layer 22.
[0055] In this embodiment, the winding of the TPP 22a is conducted by a filament winding method, as is understood from
[0056] More specifically, in the multi-supply FW device in which a plurality of bobbins can be installed around the liner 11, all of the bobbins are used as the TPP bobbins 30 in step S11. Then, the TPP 22a is reeled out from the TPP bobbins 30, and wound around the outer periphery of the liner 11. Then, the winding of the TPP 22a is performed until a desired TPP layer 22 is formed.
[0057] The number of the bobbins that can be installed at the same time in the multi-supply FW device is not particularly limited, but 48 bobbins, for example, may be installed. In this case, when the TPP layer 22 is formed, all of the 48 bobbins may serve as the TPP bobbins 30.
[0058] Step S12 of Forming Fiber Layer
[0059] In step S12 of forming the fiber layer (which may be referred to as “step S12”), the fiber bundles 23a are wound on the outer periphery of the TPP layer 22 formed in step S11.
[0060] In step S12, the fiber bundles 23a are wound on the outer periphery of the TPP layer 22, to form the fiber layer 23. Namely, in step S12 of this embodiment, a plurality of layers is formed from the fiber bundles 23a wound on the outer periphery of the TPP layer 22, to provide the fiber layer 23.
[0061] The lamination of the fiber bundles 23a as described above is carried out by a filament winding method in this embodiment, as is understood from
[0062] More specifically, in the multi-supply FW device in which a plurality of bobbins can be installed around the liner 11, all of the bobbins are used as the fiber-bundle bobbins 31 in step S12. Then, the fiber bundles 23a are reeled out from the fiber-bundle bobbins 31, and wound on the outer periphery of the TPP layer 22 that is wound around the liner 11. Then, the winding of the fiber bundles 23a is conducted until they form the fiber layer 23. When the multi-supply FW device used in step S12 is the same as the multi-supply FW device used in step S11, the TPP bobbins 30 may be replaced with the fiber-bundle bobbins 31.
[0063] Then, step S12 is combined with step S11 to provide a step of forming the winding layer, so that the preform 20 is prepared. Also, glass fibers for the protection layer 13 may be further wound as needed.
[0064] Step S13 of Placing Preform in Mold and Deaerating Mold
[0065] In step S13 of placing the preform in the mold and deaerating the mold (which may be referred to as “step S13”), the preform 20 prepared in step S12 is placed in the mold, and the air is evacuated from the mold by vacuuming. With the mold thus deaerated, the resin composition used for impregnation is more likely to permeate the winding layer 21 (mainly, the fiber layer 23), and the winding layer 21 (or fiber layer 23) is more smoothly impregnated with the resin composition.
[0066]
[0067] Also, the upper mold 41 can be moved relative to the lower mold 42, as indicated by a straight arrow in
[0068] Also, the upper mold 41 is provided with a channel 41a that extends from the outside to the outer periphery (the winding layer 21) of the preform 20 thus placed. By causing the resin composition to flow through the channel 41a, the winding layer 21 (the fiber layer 23) is supplied with and impregnated with the resin composition. Further, the mold 40 is provided with an air flow passage (not shown) used for vacuuming (vacuum deaeration) of the interior space formed in the mold 40.
[0069] Also, temperature sensors 43 are installed in the mold 40, for measuring the temperature of the preform 20, so that the temperature of the preform 20 can be obtained, and a temperature controller (not shown) is provided for changing the mold temperature to a desired temperature and keeping the temperature.
[0070] The material used for the mold 40 is not particularly limited, but metal is preferably used as usual. Thus, the mold 40 is a so-called metallic mold.
[0071] In step S13, the upper mold 41 of the mold 40 is separated from the lower mold 42 so that the mold 40 is placed in an open state, and the preform 20 is mounted on the lower mold 42 of which the upper surface is largely exposed. Then, the upper mold 41 is placed on and fastened to the lower mold 42 and the preform 20 placed in the lower mold 42 so as to cover the preform 20. Then, the mold 40 is subjected to vacuum-deaeration by use of a vacuum pump. The vacuum deaeration is completed before the resin composition is supplied to the winding layer 21 in the next step.
[0072] Step S14 of Supplying and Stopping Resin Composition
[0073] In step S14 of supplying and stopping the resin composition (which may be referred to as “step S14”), the resin composition that has not been cured is supplied to the winding layer 21 of the preform 20 placed in the mold 40 through the channel 41a, as shown in
[0074] The time of supply of the resin composition is not particularly limited, but the resin composition is preferably supplied in the following manner. Specifically, the mold 40 is heated, so as to heat the resin contained in the TPP layer 22, and reduce the viscosity of the resin to be lower than that at the time of winding of the TPP 22a, and the resin composition starts being supplied at this time. In this manner, the resin contained in the TPP layer 22 and having the reduced viscosity can be mixed to an increased extent with the resin composition supplied in step S14, and the homogeneity of the resin distribution in the reinforcement layer and the degree of adhesion of the TPP resin with the resin composition used for impregnation are increased, so that peel-off and local reduction in the strength can be avoided. In a more specific example, the temperature of the preform 20 is measured by the temperature sensors 43, for example, and the resin composition for impregnation can be supplied to the winding layer 21 of the preform 20 when the temperature becomes temporarily constant while it is increasing, as in a portion indicated by arrow “B” in
[0075] As indicated in
[0076] The resin composition thus supplied is not particularly limited provided that the resin composition reaches and penetrates the winding layer in a condition where the resin has fluidity, and it is then cured by any method to increase the strength of the fiber layer. For example, the resin may be selected from thermosetting resins that are cured by heat, such as epoxy resin, unsaturated polyester resin, etc. including an amine-based or anhydride curing accelerator, and a rubber-based reinforcing agent. The resin may also be selected from resin compositions having epoxy resin as a base compound, with which a curing agent is mixed for curing of the base compound. While the base compound is mixed with the curing agent and cured, the resin composition as the mixture of the base compound and the curing agent is caused to reach and penetrate the fiber layer, so that the resin is automatically cured.
[0077] Step S15 of Releasing Preform from Mold
[0078] In step S15 of releasing the preform 20 from the mold 40 (which may be referred to as “step S15”), after it is confirmed in step S14 that the resin contained in the TPP and the resin composition supplied to and impregnating the fiber layer have been cured, the preform 20 impregnated with the resin is released from the mold 40. In this embodiment, the upper mold 41 of the mold 40 is separated from the lower mold 42, to bring the mold 40 into an open state, in which demolding is conducted.
[0079] The preform 20 impregnated with the resin is obtained by the manufacturing method including the above steps. A layer made of glass fibers impregnated with resin is further formed as needed, on the preform 20 impregnated with the resin, so that the high-pressure tank 10 is produced.
4. Effects, etc.
[0080] According to this disclosure, in the case where the process of forming the reinforcement layer includes impregnating the fiber layer formed in the preform with resin through RTM (Resin Transfer Molding), the TPP that has already been impregnated with resin is placed in at least a part of the reinforcement layer, preferably on the inner layer side where resin impregnation is difficult to accomplish, so that the placement of the resin in the layer can be assured in advance. Thus, even when the reinforcement layer needs to have a large thickness, as in the high-pressure tank, for example, the homogeneity of the resin in the reinforcement layer can be enhanced, and the high-pressure tank having high performance can be provided. This also makes it possible to reduce the impregnation time, and improve the productivity.
[0081] The resin composition is supplied to the fiber layer formed in the preform, at substantially the same time that the resin contained in the TPP layer is in a low-viscosity state, so that the resin composition thus supplied is more likely to be mixed with the resin contained in the TPP layer, for integration of the resin in both layers, resulting in highly efficient impregnation and improved performance of the high-pressure tank.
[0082] The low-temperature curing agent, which is added to the resin contained in the TPP layer, starts curing at an early time while providing high reactivity, so that the resin composition impregnating the fiber layer can be heated from the inner layer side, with heat generated by curing, and efficient impregnation and prompt curing can be both achieved.
[0083] According to this disclosure, the winding layer 21 of the preform 20 includes the TPP layer 22, but has the fiber layer 23 formed by winding pre-impregnated fiber bundles 23a; therefore, even when the fluidity is given to the resin of the TPP layer 22 in the mold 40, and the resin moves, to give rise to a change in the winding state of the TPP layer 22, the change in the TPP layer 22 is curbed by the fiber layer 23, and a large change is unlikely to occur in the winding layer in the course of curing of the resin. Consequently, the high-pressure tank having a stable quality can be obtained.
5. Other Embodiments
[0084] In the method of manufacturing the preform, and the high-pressure tank, the fiber layer 23 is provided on the outer side of the TPP layer 22 that is in contact with the liner 11, as typically illustrated in
[0085]
6. Manufacturing Method 2
[0086] Here, a method S20 of manufacturing a high-pressure tank according to another embodiment will be described. The method S20 of manufacturing the high-pressure tank is different from the method S10 of manufacturing the high-pressure tank as described above with reference to
[0087] The winding of the TPP 22a in step S11 and winding of the fiber bundles 23a in step S12 in this embodiment will be described with reference to
[0088] In this embodiment, the TPP 22a and the fiber bundles 23a are wound around the liner 11 by the filament winding method, by means of a continuous multi-supply FW apparatus in which two or more multi-supply FW devices are arranged in line. In this embodiment, a multi-supply FW device 50a through a multi-supply FW device 50f are arranged in line, as shown in
[0089] In this embodiment, the two or more multi-supply FW devices are positioned, such that the respective multi-supply FW devices are in charge of different layers for which winding is conducted. Accordingly, as shown in
[0090] Thus, in the continuous multi-supply FW apparatus, a multi-supply FW device for winding the TPP 22a, multi-supply FW device for winding the fiber bundles 23a, or multi-supply FW device for winding a mixture of the TPP 22a and the fiber bundles 23a, depending on the case, can be fixed, and the fibers can be wound with high efficiency, without requiring bobbins to be changed during winding. For example, when the first layer (layer that contacts with the liner 11) is requested to be a layer (TPP layer 22) formed of the TPP 22a, the multi-supply FW device 50a of