阅读说明：本技术 高压罐及制造高压罐的方法 (High-pressure tank and method for manufacturing high-pressure tank ) 是由 片野刚司 于 2020-01-21 设计创作，主要内容包括：本发明涉及高压罐及制造高压罐的方法。高压罐包括：衬里,该衬里用于存储流体；以及增强层,该增强层覆盖衬里的外表面并且包括缠绕在衬里上的纤维和树脂。增强层包括螺旋层组和大角度层,其中,该螺旋层组包括层叠的螺旋层,并且该大角度层与螺旋层组相邻地并且在衬里侧上设置。螺旋层组包括最内层、最外层和中间层,其中,该最内层最靠近衬里并且是分别具有最大纤维缠绕角度和第二最大纤维缠绕角度的第一螺旋层和第二螺旋层中的一个螺旋层,并且该最外层最靠近高压罐的外表面并且是第一螺旋层和第二螺旋层中的另一个螺旋层,并且中间层被布置在最内层和最外层之间并且包括缠绕角度小于最内层和最外层的螺旋层。(The present invention relates to a high-pressure tank and a method of manufacturing the high-pressure tank. The high-pressure tank includes: a liner for storing a fluid; and a reinforcing layer covering an outer surface of the liner and including fibers and resin wound around the liner. The reinforcement layer includes a spiral layer group including stacked spiral layers and a high angle layer provided adjacent to the spiral layer group and on the liner side. The spiral layer group includes an innermost layer, an outermost layer, and an intermediate layer, wherein the innermost layer is closest to the liner and is one of a first spiral layer and a second spiral layer having a maximum filament winding angle and a second maximum filament winding angle, respectively, and the outermost layer is closest to the outer surface of the high-pressure tank and is the other of the first spiral layer and the second spiral layer, and the intermediate layer is disposed between the innermost layer and the outermost layer and includes a spiral layer having a winding angle smaller than the innermost layer and the outermost layer.)

1. A high-pressure tank, comprising:

a liner having an interior space for storing a fluid; and

a reinforcing layer disposed on an outer surface of the liner such that the outer surface of the liner is covered by the reinforcing layer, the reinforcing layer comprising fibers and a resin wound on the liner, wherein

The enhancement layer includes:

a set of spiral layers including spiral layers in each of which the fibers are helically wound, the spiral layers being stacked, an

A large angle layer provided at a position adjacent to the spiral layer group and on a side close to the liner, the large angle layer being larger in a filament winding angle that is a winding angle of the filament with respect to a direction of an axis of the high-pressure tank than any one of the spiral layers of the spiral layer group, and

the spiral layer set includes:

an innermost layer disposed closest to the liner, the innermost layer being one of a first spiral layer having a largest fiber winding angle among the spiral layers of the spiral layer group and a second spiral layer having a second largest fiber winding angle among the spiral layers of the spiral layer group,

an outermost layer disposed closest to an outer surface of the high-pressure tank, the outermost layer being the other of the first spiral layer and the second spiral layer, an

An intermediate layer disposed between the innermost layer and the outermost layer, the intermediate layer comprising a helical layer having a filament winding angle that is less than each of the filament winding angles of the innermost layer and the outermost layer.

2. The high-pressure tank according to claim 1, wherein the filament winding angles of the spiral layers arranged adjacent to each other in the spiral layer group are different from each other.

3. The high-pressure tank according to claim 1 or 2, wherein the innermost layer is the first spiral layer and the outermost layer is the second spiral layer.

4. The high-pressure tank according to any one of claims 1 to 3, wherein the spiral layers of the spiral layer group are stacked in the following order: minimizing a standard deviation in a case where a set of filament winding angle differences between the spiral layers adjacent to each other is used as a subject population.

5. A method of manufacturing a high pressure tank, the method comprising:

preparing a liner having an interior space for storing a fluid; and

forming a reinforcing layer such that an outer surface of the liner is covered with the reinforcing layer, the reinforcing layer including fibers and a resin wound around the liner, wherein

When the reinforcing layer is formed, a spiral layer group and a large angle layer are formed,

the spiral layer group includes spiral layers in each of which the fiber is spirally wound, the spiral layers are stacked, and

the large angle layer is provided at a position adjacent to the spiral layer group and on a side close to the liner, the large angle layer being larger in a filament winding angle, which is a winding angle of the filament with respect to a direction of an axis of the high-pressure tank, than any one of the spiral layers of the spiral layer group, and

when the set of spiral layers is formed,

an innermost layer is disposed closest to the liner, the innermost layer being one of a first spiral layer having a largest fiber winding angle among the spiral layers of the spiral layer group and a second spiral layer having a second largest fiber winding angle among the spiral layers of the spiral layer group,

an outermost layer is disposed closest to an outer surface of the high-pressure tank, the outermost layer being the other of the first spiral layer and the second spiral layer, and

an intermediate layer is disposed between the innermost layer and the outermost layer, the intermediate layer including a helical layer having a fiber winding angle that is less than each of a fiber winding angle of the innermost layer and a fiber winding angle of the outermost layer.

Technical Field

The present invention relates to a high-pressure tank and a method of manufacturing a high-pressure tank.

Background

Examples of a tank configured to store high-pressure fluid in a sealed manner include a tank including: a liner defining a space in which fluid is stored; and a reinforcing layer provided such that the liner is covered with the reinforcing layer, made of Fiber Reinforced Plastic (FRP) including resin and fiber, and configured to ensure sufficient strength against the pressure in the tank. Japanese unexamined patent application publication No. 2005-106142 (JP 2005-106142A) describes a pressure vessel including a reinforcing layer including a plurality of spirally wound portions each including fibers spirally wound on a liner. In the reinforcement layer, the helical windings are arranged such that the fibre winding angle gradually increases from an inner helical winding provided close to the liner towards an outer helical winding.

Disclosure of Invention

In the reinforcement layer of the high-pressure tank, various layers including a spiral layer including fibers wound spirally and a hoop layer including fibers wound in a hoop pattern can be arranged in various orders. However, improvement of tank performance (such as durability of the entire tank) has not been sufficiently studied in consideration of the positional relationship between these layers in the reinforcing layer.

The present invention can be realized in the following aspects.

(1) One aspect of the present disclosure relates to a high-pressure tank. This high-pressure tank includes: a liner having an interior space for storing a fluid; and a reinforcing layer including fibers and resin wound on the liner and disposed on an outer surface of the liner such that the outer surface of the liner is covered with the reinforcing layer. The enhancement layer includes: a spiral layer group including stacked spiral layers in each of which a fiber is spirally wound; and a large angle layer disposed adjacent to the spiral layer group and at a position on a side close to the liner. The large-angle layer is larger in filament winding angle than any one of the spiral layers of the spiral layer group. The fiber winding angle is the winding angle of the fiber with respect to the direction of the axis of the high-pressure tank. The spiral layer group comprises an innermost layer, an outermost layer and an intermediate layer. The innermost layer is disposed closest to the liner. The innermost layer is one of a first spiral layer having a largest filament winding angle among spiral layers of the spiral layer group and a second spiral layer having a second largest filament winding angle among the spiral layers of the spiral layer group. The outermost layer is disposed closest to an outer surface of the high-pressure tank. The outermost layer is the other of the first spiral layer and the second spiral layer. The intermediate layer is disposed between the innermost layer and the outermost layer. The intermediate layer includes a spiral layer having a filament winding angle smaller than each of the filament winding angle of the innermost layer and the filament winding angle of the outermost layer. With the configuration of the high-pressure tank according to this aspect, the difference in fiber winding angle between the large-angle layer and the spiral layer group can be made smaller. Therefore, the shear stress generated between the high angle layer and the spiral layer group can be kept low, and the durability of the high-pressure tank can be improved. Further, the difference in the fiber winding angle between adjacent layers in the spiral layer group is easily set appropriately. Therefore, the occurrence of collapse of the filament winding in the spiral layer group can be restrained. Therefore, it is possible to easily suppress a decrease in strength and durability of the high-pressure tank due to collapse of the filament windings. As a result, the performance of the high-pressure tank can be improved. (2) In the high-pressure tank according to the above aspect, the filament winding angles of the spiral layers arranged adjacent to each other in the spiral layer group may be different from each other. With this configuration of the high-pressure tank, the occurrence of collapse of the filament windings in the spiral layer group can be restrained. Therefore, the effect of suppressing the decrease in strength and durability of the high-pressure tank due to the collapse of the filament windings can be enhanced. (3) In the high-pressure tank according to the above aspect, the innermost layer may be a first spiral layer, and the outermost layer may be a second spiral layer. With such a configuration of the high-pressure tank, the stress generated in the reinforcing layer can be reduced. Therefore, the effect of improving the durability of the high-pressure tank can be enhanced. (4) In the high-pressure tank according to the above aspect, the spiral layers of the spiral layer group may be stacked in the following order, that is: minimizing a standard deviation in a case where a set of filament winding angle differences between the spiral layers adjacent to each other is used as a subject population. With this configuration of the high-pressure tank, by reducing variation in the difference in fiber winding angle between adjacent spiral layers in the spiral layer group, the physical properties of the layers of the spiral layer group are made more uniform, and therefore the generation of stress in the spiral layer group can be reduced. In addition to the above aspects, the present invention may be implemented in various aspects. For example, the present invention may be realized in an aspect related to a method of manufacturing a high-pressure tank.

Drawings

Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, and in which:

FIG. 1 is a diagrammatic sectional view of a high-pressure tank;

FIG. 2 is an enlarged diagrammatic sectional view illustrating a portion of the outer wall of the high pressure tank;

FIG. 3 is a diagram schematically illustrating a fiber winding angle;

fig. 4 is a diagram illustrating an example of a spiral layer group;

fig. 5 is a flowchart illustrating an outline of a method of manufacturing a high-pressure tank;

fig. 6 is a diagram illustrating an example of a spiral layer group;

fig. 7 is a diagram illustrating an example of a spiral layer group; and is

Fig. 8 is a diagram illustrating an example of a spiral layer group.

Detailed Description

A. First embodiment

A-1. general construction of high-pressure tank

Fig. 1 is a schematic sectional view of a high-pressure tank 100 according to a first embodiment of the invention. The high-pressure tank 100 is configured to store high-pressure fluid. In the present embodiment, the high-pressure tank 100 stores compressed hydrogen as a fluid, and is mounted in a fuel cell vehicle, which is a vehicle equipped with a hydrogen tank, for example. The high-pressure tank 100 includes a liner 10, a reinforcement layer 70, and caps 21, 22. Note that fig. 1 and other drawings (described later) schematically illustrate respective portions of the high-pressure tank 100 according to the present invention, and therefore the sizes of the respective portions illustrated in the drawings do not represent specific sizes.

A space in which high-pressure gas is stored is defined in the liner 10. The liner 10 includes a cylindrical portion 16 and two dome portions 17, 18, wherein the cylindrical portion 16 has a cylindrical shape and extends in the direction of the axis O, and the two dome portions 17, 18 have a substantially hemispherical shape and extend from opposite ends of the cylindrical portion 16, respectively. The liner 10 of the present embodiment is made of polyamide resin. Examples of polyamide resins for liner 10 include nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, and nylon 12. In this embodiment, the liner 10 is made of nylon 6.

In the present embodiment, the liner 10 is formed by coupling a plurality of components together. Specifically, the liner 10 includes liner members 11, 12, 13, and the liner members 11, 12, 13 are arranged in this order in the direction of the axis O. The liner member 11 and the liner member 12 may be coupled together, and the liner member 12 and the liner member 13 may be coupled together, by, for example, infrared welding, laser welding, hot plate welding, vibration welding, or ultrasonic welding. The number of members included in the liner 10 is not limited to three, and may be any number equal to or greater than two. The liner 10 may be formed by methods other than coupling multiple components together. For example, the liner 10 may be integrally formed by integral molding. Furthermore, at the opposite end of the liner 10, caps 21, 22 are arranged at the top of the domes 17, 18, respectively. The caps 21, 22 are coupled to the liner members 11, 13, respectively, for example, by insert molding.

The reinforcing layer 70 is disposed such that the outer surface of the liner 10 is covered by the reinforcing layer 70. The reinforcement layer 70 reinforces the liner 10, thereby improving the strength of the high-pressure tank 100 (i.e., the strength against the pressure inside the tank). The reinforcing layer 70 is made of Fiber Reinforced Plastic (FRP) including fibers wound on the outer surface of the liner 10 and a resin for impregnating the fibers as its constituent elements. Specifically, the reinforcing layer 70 is formed by winding long fibers impregnated with resin on the outer surface of the liner 10 by a filament winding method (hereinafter, referred to as "FW method") and then curing the resin. In a typical FW method, hoop winding for covering the outer surface of the cylindrical portion 16 of the liner 10 and spiral winding for covering the outer surfaces of the dome portions 17, 18 are used. The reinforcement layer 70 comprises a plurality of layers of different fiber types or fiber winding patterns.

Fig. 2 is an enlarged schematic sectional view illustrating a part of an outer wall of the high-pressure tank 100. The reinforcement layer 70 includes a carbon fiber reinforced plastic layer 74 (hereinafter, also referred to as "CFRP layer 74") provided on the liner 10 and containing Carbon Fiber Reinforced Plastic (CFRP), and a glass fiber reinforced plastic layer 72 (hereinafter, also referred to as "GFRP layer 72") provided on the CFRP layer and containing Glass Fiber Reinforced Plastic (GFRP).

The CFRP layer 74 includes layers each including carbon fibers wound in a hoop pattern (hereinafter, also referred to as "hoop layer") and layers each including carbon fibers wound spirally (hereinafter, also referred to as "spiral layer"). "hoop winding" is a winding pattern in which the winding angle of the fiber (hereinafter, also referred to as "fiber winding angle") is substantially a right angle (90 degrees) with respect to the direction of the axis O of the high-pressure tank 100, and "helical winding" is a winding pattern in which the fiber winding angle of the "helical winding" is smaller than the fiber winding angle of the "hoop layer" with respect to the direction of the axis O of the high-pressure tank 100. The CFRP layer 74 of the present embodiment includes a plurality of spiral layers having different fiber winding angles.

Fig. 3 is a view schematically showing a filament winding angle. The filament winding angle is a filament winding angle with respect to the direction of the axis O of the high-pressure tank 100. Fig. 3 illustrates the high-pressure tank 100 as seen in a direction perpendicular to the axis O, and indicates that the winding angle of the fiber F is the angle θ. Each of the single spiral layer and the single hoop layer is a layer formed by continuously winding the fiber at the same fiber winding angle while gradually shifting the position of the fiber. In the single spiral layer, the intersecting portions of the fibers overlap each other in the thickness direction of the liner 10 at some points, but the fibers do not have portions that linearly overlap each other in the thickness direction in the fiber winding direction.

The "spiral winding" may be classified into "large-angle spiral winding" in which the fiber winding direction is reversed at the dome portion after the fiber makes at least one turn about the axis O and the fiber winding angle is relatively large, and "small-angle spiral winding" in which the fiber winding direction is reversed at the dome portion before the fiber makes one turn about the axis O and the fiber winding angle is relatively small. The winding angle of the fibers in the layer in which the fibers are wound in a hoop pattern (hereinafter, also referred to as "hoop layer") may be, for example, in the range of 80 ° to 90 °, and is preferably equal to or greater than 88 °. The fiber winding angle in the layer in which the fibers are spirally wound at a large fiber winding angle (hereinafter, also referred to as "large-angle spiral layer") may be, for example, equal to or greater than 70 °, and preferably equal to or greater than 78 °. The fiber winding angle in the high angle helical layer may be equal to or less than 85 °, and preferably equal to or less than 81 °. Note that the fiber wrap angle in the hoop layer is greater than the fiber wrap angle in the high angle helical layer. The filament winding angle in the layer in which the fibers are spirally wound at a small filament winding angle (hereinafter, also referred to as "small-angle spiral layer") needs to exceed 0 °, and is preferably equal to or greater than 5 °. The fiber winding angle in the small-angle spiral layer may be appropriately set based on, for example, the length of the high-pressure tank 100 and the size of each of the caps 21, 22, so that the outer surface of the liner 10 is completely covered with the small-angle spiral layer. Further, the fiber wrap angle in the low angle helical layer may be less than 70 °, may be equal to or less than 50 °, may be equal to or less than 40 °, and may be equal to or less than 35 °.

The CFRP layer 74 illustrated in fig. 2 includes a first hoop layer 73, a spiral layer group 71, a large-angle spiral layer 75, and a second hoop layer 76, which are stacked in this order from the liner 10 side. The spiral layer group 71 is formed by laminating small-angle spiral layers each including fibers spirally wound at a small winding angle. Spiral layer set 71 includes three or more small angle spiral layers. The spiral layer group 71 will be described in detail later.

The order of stacking illustrated in fig. 2 is merely an example. The number of layers and the stacking order of the CFRP layers 74 may be changed as needed as long as a large-angle layer including fibers wound at a fiber winding angle larger than that in any one of the spiral layers of the spiral layer group 71 is arranged at a position adjacent to the spiral layer group 71 and on the side close to the liner 10. In this embodiment, as illustrated in fig. 2, the high angle layer is a hoop layer (first hoop layer 73). However, the high angle layer may be a high angle helical layer.

There is a winding angle changing portion where the fiber winding angle is changed between the layers of the CFRP layer 74. Specifically, for example, between the first hoop layer 73 and the spiral layer group 71 and between the spiral layer group 71 and the large-angle spiral layer 75, there are winding angle changing portions in which the fiber winding angle significantly changes, respectively. In each winding angle changing section in which the filament winding angle is changed as described above, the filament is wound while the filament winding angle is changed differently and the winding position of the filament is shifted to the winding start position of the next layer.

The GFRP layer 72 is primarily used to protect the interior of the can from physical or chemical stimuli applied to the can surface from the outside. Similar to the CFRP layer 74, the GFRP layer 72 may be formed by stacking any given number of hoop layers, each comprising glass fibers impregnated with resin and wound in a hoop pattern, and any given number of helical layers, each comprising glass fibers impregnated with resin and wound helically, in any given order. The GFRP layer 72 is positioned such that the outer surface of the liner 10 is completely covered by the GFRP layer 72.

Examples of the resin included in each of the CFRP layer 74 and the GFRP layer 72 include thermosetting resins (such as epoxy resins) and thermoplastic resins (such as polyester resins and polyamide resins). The resin included in the CFRP layer 74 and the resin included in the GFRP layer 72 may be of the same type or different types.

A-2 spiral layer group

As described above, the spiral layer group 71 is formed by stacking small-angle spiral layers each including spirally wound fibers. As illustrated in fig. 2, the spiral layer group 71 includes an innermost layer 71a arranged closest to the liner 10 among the layers of the spiral layer group 71. The innermost layer 71a is one of a layer having the largest filament winding angle (hereinafter, also referred to as "first spiral layer") and a layer having the second largest filament winding angle (hereinafter, also referred to as "second spiral layer") among the spiral layers of the spiral layer group 71. Further, the spiral layer group 71 includes an outermost layer 71b that is arranged closest to the outer surface of the high-pressure tank 100 among the layers of the spiral layer group 71. The outermost layer 71b is the other of the first spiral layer and the second spiral layer. Further, the spiral layer group 71 includes spiral layers arranged between the innermost layer 71a and the outermost layer 71b and including an intermediate layer 71c having a filament winding angle smaller than those of the innermost layer 71a and the outermost layer 71 b. Hereinafter, specific examples will be described in more detail.

Fig. 4 is a diagram illustrating an example of a spiral layer group 71 formed by stacking eleven small-angle spiral layers. The "layer number" illustrated in fig. 4 indicates the number assigned to the spiral layers of the spiral layer group 71 in ascending order from the spiral layer closest to the liner 10 to the spiral layer closest to the outer surface of the high-pressure tank 100. The 1 st layer is the innermost layer 71a, and the 11 th layer is the outermost layer 71 b. The 2 nd to 10 th layers are included in the intermediate layer 71 c. Fig. 4 illustrates the fiber winding angle of each of the spiral layers of the spiral layer group 71. Fig. 4 also illustrates the difference in filament wind angle between adjacent layers.

The spiral layer group 71 illustrated in fig. 4 includes two spiral layers having a filament winding angle of 8 °, two spiral layers having a filament winding angle of 10 °, two spiral layers having a filament winding angle of 15 °, two spiral layers having a filament winding angle of 17 °, and two spiral layers having a filament winding angle of 20 °. In addition, the spiral layer group 71 includes one spiral layer having a fiber winding angle of 19 °.

As described above, in the spiral layer group 71, one spiral layer of the first spiral layer having the largest filament winding angle and the second spiral layer having the second largest filament winding angle is the innermost layer 71a, and the other spiral layer of the first spiral layer and the second spiral layer is the outermost layer 71 b. When the spiral layers are arranged in descending order of filament winding angle, spiral layers having the same filament winding angle are arranged as different spiral layers. Specifically, when the spiral layer group 71 includes two or more layers having the largest filament winding angles, the filament winding angle of the first spiral layer having the largest filament winding angle and the filament winding angle of the second spiral layer having the second largest filament winding angle are considered to be the same, and in this case, the filament winding angle of the innermost layer 71a and the filament winding angle of the outermost layer 71b are the same. In the example in fig. 4, the filament winding angle of the No.1 layer as the innermost layer 71a and the filament winding angle of the 11 th layer as the outermost layer 71b are both 20 °. When the spiral layer group 71 includes three or more layers having the largest filament winding angle, any layer other than the innermost layer 71a and the outermost layer 71b among the spiral layers having the largest filament winding angle is included in the intermediate layer 71 c.

The number of small-angle spiral layers of the spiral layer group 71 illustrated in fig. 4 is only an example, and may be appropriately changed. Further, the filament winding angle of each of the small-angle helical layers illustrated in fig. 4 is only an example, and may be appropriately changed. The filament winding angle of each of the layers of the spiral layer group 71 and the number of spiral layers each having its own filament winding angle may be appropriately set based on the tank strength to be achieved for the high-pressure tank 100. In this case, for example, when the filament winding angle of the first spiral layer having the maximum filament winding angle and the filament winding angle of the second spiral layer having the second maximum filament winding angle are different from each other, one of the first spiral layer and the second spiral layer may be used as the innermost layer 71a, and the other of the first spiral layer and the second spiral layer may be used as the outermost layer 71 b.

In the high-pressure tank 100, the fiber winding angle in each of the layers of the spiral layer group 71 can be measured after the high-pressure tank 100 is dry distilled to volatilize the resin component included in the reinforcing layer 70 and to cause the fibers to remain.

A-3. method for producing high-pressure tank

Fig. 5 is a flowchart illustrating an outline of a method of manufacturing the high-pressure tank 100. To manufacture the high-pressure tank 100, first, the liner 10 is prepared (step S100). Step S100 includes the insert molding process of coupling the caps 21, 22 to the liner members 11, 13, respectively, and the process of coupling the liner members 11, 12, 13 together, as described above. Then, the resin-impregnated fiber is wound on the liner 10 prepared in step S100 to form a resin-impregnated fiber layer (the reinforcing layer 70 before curing) (step S110). In step S110, the reinforcing layer 70 is formed. As illustrated in fig. 2, the reinforcing layer 70 includes a high angle layer (first hoop layer 73) and a spiral layer group 71 stacked in this order from the liner 10 side. Then, the resin in the resin-impregnated fiber layer is cured (step S120), thereby completing the high-pressure tank 100. The resin may be cured by, for example, heating using a heating furnace or an induction heating method using an induction heating coil that induces high-frequency induction heating.

In the spiral layer group 71 of the high-pressure tank 100 of the present embodiment thus configured, the innermost layer 71a adjacent to the first hoop layer 73, which is a high angle layer, is either a first spiral layer having the largest fiber winding angle or a second spiral layer having the second largest fiber winding angle. Therefore, the difference in the filament winding angle between the large angle layer and the spiral layer group 71 can be made smaller. When the difference in the filament winding angle between adjacent layers is small, for example, even if the filling of the fluid into the high-pressure tank 100 and the discharge of the fluid from the high-pressure tank 100 are repeatedly performed, the shear stress generated between the adjacent layers can be kept low. When the filament winding angles of the layers are different, the physical properties of the layers are different from each other, and the stretching directions of the layers are different. Therefore, as the difference in the filament winding angle between adjacent layers is larger, the shear stress generated at the boundary between the layers is higher. Since the shear stress can be kept low, the durability of the reinforcing layer 70 can be improved, and as a result, the durability of the entire high-pressure tank 100 can be improved.

Further, in the spiral layer group 71 of the high-pressure tank 100 of the present embodiment, the outermost layer 71b disposed closest to the outer surface of the high-pressure tank 100 is the first spiral layer having the largest filament winding angle or the second spiral layer having the second largest filament winding angle. By setting the filament winding angles of both the innermost layer 71a and the outermost layer 71b to be large, the difference in filament winding angle between adjacent layers in the spiral layer group 71 is easily set appropriately.

Fig. 6 is a diagram illustrating an example of the configuration of the spiral layer group 71 of the high-pressure tank in the comparative example in a similar manner to that in fig. 4. In the spiral layer group 71, the spiral layers may be arranged, for example, such that the filament winding angle gradually decreases or gradually increases from the innermost layer 71a to the outermost layer 71 b. Fig. 6 illustrates a state in which the spiral layers are arranged such that the filament winding angle is gradually reduced from the innermost layer 71a to the outermost layer 71 b. In this case, for example, when the spiral layer group 71 includes two or more spiral layers having the same fiber winding angle as schematically in fig. 6, the layers are arranged one after another. Even when the spiral layer group 71 does not include spiral layers having the same fiber winding angle, the difference in fiber winding angle between adjacent layers tends to be considerably small. When the filament winding angle of one layer and the filament winding angle of a layer adjacent to the one layer (hereinafter, referred to as "adjacent layer") are relatively close to each other, the fibers in the one layer and the fibers in the adjacent layer overlap each other in the thickness direction of the liner 10 such that the fibers in the one layer and the fibers in the adjacent layer are substantially linearly aligned with each other along the filament winding direction. The inventors of the present application have obtained a new finding that, in this case, after the resin-impregnated fiber is wound on the liner 10 and before the resin is cured, the fiber winding collapse tends to occur. The resin-impregnated fibers to be wound on the liner 10 generally comprise fiber bundles formed by bundling tow prepregs comprising about 20,000 to about 50,000 individual fibers together. Therefore, when the fiber bundles overlap each other in the thickness direction of the liner 10 such that the fiber bundles are substantially linearly aligned with each other along the fiber winding direction, the bundle structure of the fiber bundles easily collapses and the fibers easily become misaligned. When such fiber winding collapse occurs, a desired fiber tension cannot be obtained, and the strength and durability of the cured reinforcing layer 70 may be low.

According to the present embodiment, it is possible to restrain the difference in fiber winding angle between adjacent layers in the entire spiral layer group 71 to be excessively small, thereby making it easy to appropriately set the difference in fiber winding angle between adjacent layers. Therefore, the occurrence of the filament winding collapse can be restrained. As a result, a decrease in strength and durability of the high-pressure tank 100 due to collapse of the filament windings can be suppressed.

In the present embodiment, the large-angle helical layer 75 is provided as a layer arranged at a position adjacent to the helical layer group 71 and on the side close to the outer surface of the high-pressure tank 100, but another configuration may be adopted. For example, the second circumferential layer 76 may be disposed adjacent to the set of helical layers 71 without a high angle helical layer 75 disposed between the second circumferential layer 76 and the set of helical layers 71. Alternatively, a configuration may be adopted in which such a large-angle layer is not provided at a position adjacent to the spiral layer group 71 and on the side close to the outer surface of the high-pressure tank 100.

When the high angle layer is arranged at a position adjacent to the spiral layer group 71 and on the side close to the outer surface of the high-pressure tank 100, it is possible to make the fiber winding angle difference between the high angle layer arranged at a position adjacent to the spiral layer group 71 and on the side close to the outer surface of the high-pressure tank 100 and the outermost layer 71b of the spiral layer group 71 small because the outermost layer 71b is the first spiral layer or the second spiral layer, and thus the fiber winding angle of the outermost layer 71b is large. As a result, the shear stress can be kept low because the difference in filament winding angle between adjacent layers is no longer large. Further, when the required number of hoop layers necessary to ensure the strength of the high-pressure tank 100 are provided, the spiral layer group 71 is interposed between the hoop layers as in the present embodiment. In this way, since the number of hoop layers sequentially stacked is no longer an excessive number, it is possible to restrain the occurrence of collapse of the filament winding in the hoop layers. When the spiral layer group 71 is interposed between the hoop layers, as in the present embodiment, it is possible to prevent a sharp change in the fiber winding angle by providing a large-angle spiral layer between the spiral layer group 71 and the hoop layers.

B. Second embodiment

Fig. 7 is a diagram illustrating an example of the configuration of the spiral layer group 71 of the high-pressure tank 100 according to the second embodiment in a similar manner to that in fig. 4. The high-pressure tank 100 of the second embodiment has the same structure as the high-pressure tank 100 of the first embodiment, except for the configuration of the spiral layer group 71. Fig. 7 illustrates an example in which eleven small-angle spiral layers are provided as in the spiral layer group 71 illustrated in fig. 4. In the second embodiment, the spiral layers of the spiral layer group 71 are laminated in the following order, that is: the standard deviation of the case where the set of differences in the filament winding angles between adjacent spiral layers is used as the subject population is made smaller (more specifically, the standard deviation is made minimized). For example, in the example illustrated in fig. 7, the standard deviation is 1.6. In contrast, in the example illustrated in fig. 4, the standard deviation is about 2.154.

With this configuration, by reducing variations in the difference in fiber winding angles between adjacent spiral layers in the spiral layer group 71, the physical properties of the layers of the spiral layer group 71 are made more uniform, and thus the generation of stress in the spiral layer group 71 can be reduced. As a result, the durability of the high-pressure tank 100 can be further improved.

C. Third embodiment

Fig. 8 is a diagram illustrating an example of the configuration of the spiral layer group 71 of the high-pressure tank 100 according to the third embodiment in a similar manner to that in fig. 4. The high-pressure tank 100 of the third embodiment has the same structure as the high-pressure tank 100 of the first embodiment, except for the configuration of the spiral layer group 71. Fig. 8 illustrates an example of a spiral layer group 71 that differs from the second embodiment of fig. 7 only in the fiber winding angle of the innermost layer 71 a. In the spiral layer group 71 of the third embodiment, the innermost layer 71a is the first spiral layer having the largest filament winding angle.

With this configuration, the effect of reducing the stress generated in the reinforcing layer 70 can be enhanced as compared with the case where the outermost layer 71b is the first spiral layer and the innermost layer 71a is the second spiral layer. In the reinforcing layer 70 in which the large-angle layers are provided with the spiral layer group interposed therebetween, the large-angle layer (the first circumferential layer 73) disposed on the liner 10 side has higher load sharing for ensuring the strength of the high-pressure tank 100 than the large-angle layers (the large-angle spiral layer 75 and the second circumferential layer 76) disposed on the side close to the outer surface of the high-pressure tank 100. Presumably, this is because the spiral layer group 71 interposed between the large angle layers is softer than the large angle layers, and thus the load sharing of the large angle layers provided on the spiral layer group 71 is reduced. Stress is more easily generated in the interface between the large-angle layer and the small-angle spiral layer having higher load sharing than in the interface between the large-angle layer and the small-angle spiral layer having lower load sharing. Therefore, the filament winding angle of the innermost layer 71a that is in contact with the high angle layer on the liner 10 side having higher load sharing is set to a larger filament winding angle to reduce the filament winding angle difference between the innermost layer 71a and the high angle layer. In this way, the stress generated in the reinforcement layer 70 can be reduced, thereby enhancing the effect of increasing the durability of the high-pressure tank 100.

D. Other embodiments

(D1) In the foregoing embodiments illustrated in fig. 4, 7, and 8, the filament winding angles of adjacent spiral layers in the spiral layer group 71 are different from each other. Alternatively, there may be portions where the spiral layers having the same fiber winding angle are arranged one after another. Even in this case, the above-described effect can be obtained by setting the innermost layer 71a and the outermost layer 71b adjacent to the high angle layer as the layer having the maximum filament winding angle and the layer having the second maximum filament winding angle. That is, in the entire spiral layer group, it is easier to restrain the difference in filament winding angle between the innermost layer 71a and the large-angle layer on the liner 10 side, and to appropriately ensure the difference in filament winding angle between the adjacent layers.

(D2) In the foregoing embodiment, the spiral layer group 71 is a part of the CFRP layer 74 made of carbon fiber reinforced plastic. However, another configuration may be adopted. For example, even in the case where the reinforcing layer 70 is formed using fibers other than carbon fibers, the same effects as those of the foregoing embodiments can be obtained when the same configuration as that of any of the above embodiments with respect to the fiber winding angle is adopted in the spiral layer group in which the spiral layers are laminated.

The invention is not limited to the embodiments described above and may be implemented in various other embodiments within the scope of the appended claims. For example, technical features of the foregoing embodiments corresponding to technical features in the aspects described in the summary of the invention may be replaced or combined with each other to partially or completely solve the technical problems or to partially or completely exhibit advantageous effects. In addition, any technical features which are not described as essential technical features in the specification may be deleted where appropriate.