阅读说明：本技术 模块 (Module ) 是由 中岛健一郎 小熊泰正 于 2020-09-25 设计创作，主要内容包括：本公开提供一种模块,所述模块配备有：第一构件,所述第一构件是沿着一个轴向方向产生压力变动的电池或者储气罐；第二构件,所述第二构件配置在所述第一构件的所述一个轴向方向的两端部；以及约束构件,所述约束构件对所述第一构件及所述一对第二构件加压并进行约束,其中,所述约束构件是通过环绕含有纤维及树脂的纤维强化塑料(FRP)而形成的,上述FRP具有：基底纤维层,所述基底纤维层的纤维方向沿着环绕方向；以及加强纤维层,所述加强纤维层的纤维方向与基底纤维层不同,所述加强纤维层在环绕的状态下在两端部之间具有非重叠部,所述非重叠部位于与所述第一构件相向的区域。(The present disclosure provides a module equipped with: a first member that is a battery or a gas tank that generates pressure fluctuation in one axial direction; a second member disposed at both ends of the first member in the one axial direction; and a restraining member that presses and restrains the first member and the pair of second members, wherein the restraining member is formed by surrounding a fiber-reinforced plastic (FRP) containing a fiber and a resin, and the FRP includes: a base fiber layer having a fiber direction along a hoop direction; and a reinforcing fiber layer having a fiber direction different from that of the base fiber layer, the reinforcing fiber layer having a non-overlapping portion between both end portions in a looped state, the non-overlapping portion being located in a region facing the first member.)

1. A module, provided with:

a first member that is a battery or a gas tank that generates pressure fluctuation in one axial direction;

a pair of second members disposed at both ends of the first member in the one axial direction; and

a restraining member that presses and restrains the first member and the pair of second members,

wherein the content of the first and second substances,

the restraining member is formed by surrounding a Fiber Reinforced Plastic (FRP) containing fibers and resin,

the fiber-reinforced plastic has a base fiber layer having a fiber direction along a circumferential direction and a reinforcing fiber layer having a fiber direction different from that of the base fiber layer,

the reinforcing fiber layer has a non-overlapping portion between both end portions in a surrounded state,

the non-overlapping portion is located in a region facing the first member.

2. The module of claim 1 wherein the fiber direction in the reinforcing fiber layer is in an orthogonal relationship to the fiber direction in the base fiber layer.

3. The module of claim 1 or 2, wherein the module has a plurality of the non-overlapping portions,

the non-overlapping portions are located in respective regions facing the first member.

4. The module of any one of claims 1 to 3, wherein the first member is the battery.

5. A module according to any one of claims 1 to 3, wherein the first member is the gas reservoir.

Technical Field

The present disclosure relates to an assembly equipped with a restraining member.

Background

A technique of restraining a battery that expands and contracts accompanying charge and discharge with a restraining member is known. For example, in japanese patent laid-open No. 2019-106275, there is disclosed a battery module equipped with: the battery pack includes a laminate formed by laminating a plurality of battery cells, a pair of end plates disposed at both ends of the laminate in a laminating direction, and a restraining member for applying a restraining load between the pair of end plates, wherein the restraining member includes a resin material having an elastic modulus and a strain amount within a specific range.

In addition, a technique of covering the outer periphery of the air tank with fiber reinforced plastic is known. For example, in japanese kokai 2019-507856, a component is disclosed, which is such a component: the assembly is provided with: a pressure vessel equipped with a domed end having an outer surface for containing a fluid; and a member disposed at an end of the dome shape, the member being attached to the outer surface by a plurality of ribbons wound around the end of the dome shape across at least a portion of the member.

Disclosure of Invention

In the case where the battery or the gas tank is restrained by the restraining member, the restraining member is likely to be deteriorated due to pressure fluctuations generated by the battery or the gas tank. The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide an assembly that suppresses deterioration of a restraining member caused by pressure variation.

In order to solve the above problem, in the present disclosure, there is provided a module including: a first member that is a battery or a gas tank that generates pressure fluctuation in one axial direction; a pair of second members disposed at both ends of the first member in the one axial direction; and a restraining member that presses and restrains the first member and the pair of second members, wherein the restraining member is formed by surrounding a fiber-reinforced plastic (FRP) containing fibers and a resin, the FRP has a base fiber layer having a fiber direction along a surrounding direction, and a reinforcing fiber layer having a fiber direction different from that of the base fiber layer, the reinforcing fiber layer has a non-overlapping portion between both end portions in a surrounded state, and the non-overlapping portion is located in a region facing the first member.

According to the present disclosure, by locating the non-overlapping portion in the reinforcing fiber layer in the region facing the first member, it is possible to form a module that suppresses deterioration of the restraining member due to pressure variation.

In the above disclosure, the fiber direction in the reinforcing fiber layer may be orthogonal to the fiber direction in the base fiber layer.

In the above disclosure, the module may have a plurality of the non-overlapping portions, and the plurality of non-overlapping portions may be located in respective regions facing the first member.

In the above disclosure, the first member may be the battery.

In the above disclosure, the first member may be the air tank.

The module in the present disclosure has an effect that deterioration of the restraining member due to pressure variation can be suppressed.

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 parts, and in which:

fig. 1 is a schematic perspective view showing a module according to the present disclosure by way of example.

Fig. 2 is a schematic top view of the module of fig. 1.

Fig. 3 is a schematic front view of the module in fig. 1.

Fig. 4 is a schematic plan view showing a module according to the present disclosure by way of example.

Fig. 5 is an explanatory diagram for explaining the problem to be solved by the present disclosure.

Fig. 6A is a schematic sectional view illustrating a second member in the present disclosure by way of example.

Fig. 6B is a schematic sectional view illustrating a second member in the present disclosure by way of example.

Fig. 7A is an explanatory view for explaining FRP in the present disclosure.

Fig. 7B is an explanatory view explaining FRP in the present disclosure.

Fig. 8 is an explanatory diagram for explaining FRP in the present disclosure.

Fig. 9A is an explanatory view explaining a binding member in comparative example 1.

Fig. 9B is an explanatory view explaining a binding member in embodiment 1.

Fig. 9C is an explanatory view for explaining the binding member in embodiment 2.

Fig. 10A is an explanatory view explaining a fatigue test.

Fig. 10B is an explanatory view explaining a fatigue test.

Fig. 11 shows the results of the fatigue test for the constraining members obtained in comparative example 1 and examples 1 and 2.

Detailed Description

Hereinafter, the modules in the present disclosure will be described in detail. In the present specification, when a state where another member is disposed on a certain member is simply expressed as "upper" or "lower", unless otherwise specified, the present invention includes: a case where another member is disposed directly above or below a certain member so as to be in contact with the certain member; and a case where another member is disposed above or below a certain member with another member interposed therebetween.

Fig. 1 is a schematic perspective view illustrating a module according to the present disclosure, showing a module in which a first member is a battery. Fig. 2 is a schematic top view of the module of fig. 1. The module 10 shown in fig. 1 and 2 is provided with: the battery includes a first member as a battery that generates pressure fluctuations along one axial direction X, a pair of second members (end plates) 2 disposed at both ends of the first member 1 in the one axial direction X, and a restraining member 3 that presses and restrains the first member 1 and the pair of second members 2.

Fig. 3 is a schematic front view of the module in fig. 1. As shown in fig. 3, the constraining member 3 is formed by surrounding a Fiber Reinforced Plastic (FRP)13 containing fibers and resin, and the FRP13 includes: a base fiber layer 13a, the fiber direction of the base fiber layer 13a being along the circulating direction; and a reinforcing fiber layer 13b, the fiber direction of the reinforcing fiber layer 13b being different from that of the base fiber layer 13 a. The reinforcing fiber layer 13b has a non-overlapping portion α between both end portions in a looped state. The non-overlapping portion α is located in a region facing the first member 1.

Fig. 4 is a schematic front view showing a module according to the present disclosure, and shows a module in which the first member is an air tank. The module 10 shown in fig. 4 is equipped with: a first member 1 as an air tank that generates pressure fluctuation along one axial direction X, a pair of second members (bushings) 2 disposed at both ends of the first member 1 in the one axial direction X, and a restraining member 3 that presses and restrains the first member 1 and the pair of second members 2. The binding member 3 in fig. 4 has a specific structure as in fig. 2 described above, and the non-overlapping portion is located in a region facing the first member.

According to the present disclosure, the non-overlapping portion in the reinforcing fiber layer is located in the region facing the first member, whereby a module that suppresses deterioration of the restraining member due to pressure variation can be formed. As described above, when the battery or the gas tank is restrained by the restraining member, the restraining member is likely to be deteriorated due to the pressure fluctuation generated by the battery or the gas tank. For example, when the battery expands due to charging, a compressive stress is generated between end plates disposed at both ends of the battery and a restraining member facing the end plates. Conversely, when the battery shrinks due to discharge, the compressive stress is relieved. Therefore, when the charge and discharge of the battery are repeated, the generation and the relief of the compressive stress are also repeated, and the degradation of the restraining member due to fatigue occurs.

Next, generation of the compressive stress will be described in detail. As shown in fig. 5, in the first member 1, when pressure variation along one axial direction is generated, stress S₁Stress S is transmitted from the first member 1 to the second member 2₂From the second member 2 to the constraining member 3. At this time, in the binding member 3, as the stress S₁To generate stress S₃. Stress S₃Is equivalent to restraintTensile stress of the member 3, however, since the base fiber layer included in the constraining member 3 has a fiber direction along the surrounding direction, it is possible to cope with the stress S₃Exhibits high durability. In contrast, stress S₂Since it is generated in the thickness direction of the constraining member 3, the base fiber layer contained in the constraining member 3 is resistant to the stress S₂Has low durability. Thus, in the present disclosure, a reinforcing fiber layer in a different fiber direction than the base fiber layer is employed. By making the fiber direction in the base fiber layer different from the fiber direction in the reinforcing fiber layer, the fibers of one layer intersect with the fibers of the other layer at the boundary between the two layers. By blocking the stress S generated in the thickness direction by the crossing portion₂Can be applied to stress S₂Exhibits high durability.

On the other hand, as shown in fig. 3, the reinforcing fiber layer 13b has a non-overlapping portion α between both end portions in a looped state. In other words, the reinforcing fiber layer 13b is surrounded in a non-overlapping manner. If the reinforcing fiber layer 13b is wound so as to overlap with each other, the thickness of the reinforcing fiber layer is doubled at the overlapping portion, and stress concentration is likely to occur. Therefore, it is preferable that the Fiber Reinforced Plastic (FRP) is surrounded so as not to generate an overlapping portion as much as possible, and if the manufacturing accuracy (for example, accuracy due to shrinkage at the time of hardening the resin) is taken into consideration, a non-overlapping portion is inevitably generated.

The present inventors have conducted no investigation in the past on the installation position of such a non-overlapping portion, and as a result of extensive and intensive studies, they have found that the installation position of the non-overlapping portion α is subjected to a stress S generated in the thickness direction₂In the region of influence (region opposed to the second member) with respect to the stress S₂The durability of (2) becomes low. Therefore, it was found that the non-overlapping portion α is provided at a position not subjected to the stress S generated in the thickness direction₂The region (region facing the first member) affected by (f) with respect to the stress S₂The durability of the pressure sensor is increased, and the deterioration of the restraining member due to the pressure fluctuation can be suppressed.

The non-overlapping portion is located in a region facing the first member. The "region facing the first member" refers to a region where the first member is located when the module 10 is viewed in a plan view (when viewed along the direction P), as shown in fig. 3. The direction P is generally a direction orthogonal to the one axial direction X, and is a direction parallel to a normal line in the principal surface of the constraining member 3.

1. First member

The first component in this disclosure is a battery or a gas reservoir that produces pressure fluctuations in one axial direction. In the case of a battery, the battery expands and contracts with charge and discharge, and pressure fluctuations occur in the thickness direction of the battery. The one axial direction in the battery generally corresponds to the thickness direction of the battery. On the other hand, in the case of a gas tank in which bushings are arranged at both ends, pressure fluctuations occur in the direction connecting both ends by charging and discharging gas into and from the gas tank. The one axial direction in the air tank generally corresponds to the direction of a sleeve connecting both end portions.

The battery in the present disclosure is generally a secondary battery that can be repeatedly charged and discharged. Further, the battery in the present disclosure has at least one battery cell, and preferably has a plurality of battery cells. As shown in fig. 1, preferably, a plurality of battery cells 1a are stacked in the thickness direction (one axial direction X). The plurality of battery cells may be connected in series or in parallel.

Preferably, the battery in the present disclosure has at least a positive electrode, an electrolyte layer, and a negative electrode. The electrolyte layer may be a layer containing an electrolytic solution, a layer containing a polymer electrolyte, or a layer containing an inorganic solid electrolyte. In particular, the battery in the present disclosure is preferably an all-solid battery in which the electrolyte layer is a layer containing an inorganic solid electrolyte. In order to achieve sufficient performance of an all-solid battery, a high confining pressure is necessary in many cases, but when a high confining pressure is applied, deterioration of the confining member due to pressure fluctuation is likely to occur. In contrast, in the present disclosure, by disposing the non-overlapping portion at a specific position, it is possible to effectively suppress deterioration of the restraining member due to pressure variation. The restraint pressure applied to the all-solid battery is not particularly limited, and may be, for example, 1.0MPa or more, or 2.0MPa or more. On the other hand, the restraint pressure applied to the all-solid battery is, for example, 50MPa or less. In addition, the battery in the present disclosure may be a fuel cell.

The gas storage tank in the present disclosure has a liner with a space for sealing gas inside the liner. Examples of the material of the liner include resins such as nylon-based resins (polyamide-based resins) and polyethylene-based resins. Preferably, the air tank further has a reinforcing layer covering the outer circumferential surface of the liner. Preferably, the reinforcing layer is a layer having fiber-reinforced plastic (FRP) containing fibers and resin. Examples of the fibers include carbon fibers, glass fibers, and aramid fibers. On the other hand, examples of the resin include thermosetting resins such as epoxy resin, polyester resin, and polyamide resin. As a method for forming the reinforcing layer, for example, a method of winding a fiber impregnated with a resin around the surface of the liner by a filament winding method and then hardening the resin is exemplified.

Further, preferably, the gas tank is a high pressure gas tank. In the case of a high-pressure gas tank, pressure fluctuations tend to increase, and degradation of the restraining member due to the pressure fluctuations tends to occur. In contrast, in the present disclosure, by disposing the non-overlapping portion at a specific position, it is possible to effectively suppress deterioration of the restraining member due to pressure variation. The high-pressure gas is a gas that satisfies the definition of the global unified System for chemical classification and expression (GHS global unified System: global chemical unified classification and labeling System). In addition, in the present disclosure, preferably, the gas storage tank is a hydrogen gas storage tank.

2. Second member

The second member in the present disclosure is a member disposed at both end portions in one axial direction of the first member. In the case where the first member is a battery, the second member corresponds to an end plate. On the other hand, in the case where the first member is an air tank, the second member corresponds to a sleeve. Preferably, the rigidity of the second member is high. Examples of the material of the second member include metals such as carbon steel and aluminum, and resins. The sleeve connects the inside and the outside of the gas tank, and therefore, is the most easily subjected to the pressure load of the gas.

Preferably, in the second member, a region opposed to the constraining member has a curved surface shape. By having a curved surface shape, stress concentration due to pressure fluctuation can be suppressed. In order to suppress the stress concentration, the region of the second member facing the constraining member may have no planar shape or a planar shape. For example, the second member 2 shown in fig. 6A does not have a planar shape in the region facing the constraining member, and only has a curved surface shape R. On the other hand, the second member 2 shown in fig. 6B has a curved surface shape R and a planar shape P in a region facing the constraining member. As shown in fig. 6B, it is preferable that curved surface shapes R are formed at both ends of the planar shape P. On the other hand, the second member and the first member are preferably in surface contact. By the surface contact, the stress concentration caused by the confining pressure can be suppressed. As the shape of the second member, for example, there is a shape obtained by cutting a cylindrical or elliptic cylinder in a plane parallel to the height direction. For example, the second member 2 in fig. 1 has a shape in which the center of a circle in a cylinder is cut off in a plane parallel to the height direction.

3. Restraining member

The constraining member in the present disclosure is a member that pressurizes and constrains a first member and a pair of second members. The constraining member is generally a hoop-like member that covers the outer peripheral surfaces of the first member and the pair of second members. The restraining member is formed by surrounding (winding) fiber-reinforced plastic (FRP) containing fibers and resin. Specifically, as shown by way of example in fig. 3, the FRP13 is wound around the outer peripheral surfaces of the first member 1 and the pair of second members 2 to form the constraining member 3.

The fiber-reinforced plastic (FRP) contains fibers and a resin. Examples of the fibers include carbon fibers, glass fibers, and aramid fibers, and among them, carbon fibers are preferable. Examples of the carbon fibers include Polyacrylonitrile (PAN) carbon fibers, rayon carbon fibers, and pitch carbon fibers. On the other hand, examples of the resin include thermosetting resins such as epoxy resin, polyester resin, and polyamide resin.

The method of molding FRP is not particularly limited, and examples thereof include a vacuum high-pressure bag method, an autoclave method, a sheet winding method, a manual laying method, and a filament winding method.

The FRP includes: a base fiber layer having a fiber direction along a hoop direction; and a reinforcing fiber layer having a fiber direction different from that of the base fiber layer. Fig. 7A is a schematic plan view illustrating an FRP according to the present disclosure, and fig. 7B is a sectional view taken along line a-a of fig. 7A. As shown in fig. 7A, B, FRP13 has: a base fiber layer 13a, a fiber direction D of the base fiber layer 13a_aAlong the circumferential direction D₁(ii) a And a reinforcing fiber layer 13b, the fiber direction D of the reinforcing fiber layer 13b_bUnlike the base fiber layer 13 a.

The base fiber layer is typically an elongated sheet having a fiber direction along the circumferential direction. By "fiber direction along the circulating direction" is meant that the fiber direction in the base fiber layer has a parallel relationship with the circulating direction. The "parallel relationship" means not only strictly parallel but also an angle (acute angle side) formed by two directions of 10 ° or less. In addition, the surrounding direction D₁Generally aligned with the length of the base fibrous layer.

The length of the base fiber layer varies depending on the number of turns around the outer peripheral surfaces of the first member and the pair of second members, but may be, for example, 10 times or more, or 20 times or more, with respect to the length of the outer peripheral surfaces. On the other hand, the length of the base fiber layer is, for example, 100 times or less as long as the length of the outer peripheral surface. The thickness of the base fiber layer may be, for example, 0.05mm or more, or 0.08mm or more. On the other hand, the thickness of the base fiber layer is, for example, 0.5mm or less. The width of the base fiber layer (width W in fig. 7A) is appropriately set according to the use.

The reinforcing fiber layer has a different fiber direction than the base fiber layer. The term "different fiber directions" means that an angle (acute angle side) formed by the fiber direction in the reinforcing fiber layer and the fiber direction in the base fiber layer is 1 ° or more. The angle may be 30 ° or more, 45 ° or more, or 60 ° or more.

In particular, in the present disclosure, the fiber direction D in the reinforcing fiber layer 13b_bAnd the fiber direction D in the base fiber layer 13a_aPreferably orthogonal. The "orthogonal relationship" is not only strictly orthogonal but also means that an angle (acute angle side) formed by two directions is 80 ° or more and 90 ° or less.

The length of the reinforcing fiber layer is a length resulting from a non-overlapping portion described later. As shown in FIG. 7A, the length of the reinforcing fiber layer 13b is set to L_bIn the case of (1), L_bSubstantially the same length as the outer peripheral surfaces of the first member and the pair of second members. As shown in fig. 7B, the reinforcing fiber layer 13B is preferably formed on one surface side of the base fiber layer 13 a. The thickness of the reinforcing fiber layer may be, for example, 0.05mm or more, or 0.08mm or more. On the other hand, the thickness of the reinforcing fiber layer is, for example, 0.5mm or less.

The ratio of the thickness of the reinforcing fiber layer to the total thickness of the base fiber layer and the reinforcing fiber layer may be, for example, 10% or more and 30% or more. When the proportion of the thickness of the reinforcing fiber layer is too small, there is a possibility that the durability against the compressive stress generated in the thickness direction becomes low. On the other hand, the ratio of the thickness of the reinforcing fiber layer to the total thickness of the base fiber layer and the reinforcing fiber layer may be, for example, 90% or less, or 70% or less. When the proportion of the thickness of the reinforcing fiber layer is too large, there is a possibility that the durability against tensile stress in the hoop direction becomes low.

As shown in fig. 3, the reinforcing fiber layer 13b has a non-overlapping portion α between both end portions in a looped state. The length of the non-overlapping part alpha is set as L_αIn the case of (1), L_αThe value of (A) is, for example, 50mm or less, or may be 10mm or less. On the other hand, L_αThe value of (B) is, for example, 1mm or more, or 1mm or more5 mm. The length of the outer peripheral surfaces of the first member and the pair of second members is set to L_βIn case of L_αRelative to L_βRatio of (L)_α/L_β) For example, 3.0% or less, preferably 2.3% or less. On the other hand, L_αRelative to L_βRatio of (L)_α/L_β) For example, 0.1% or more, or 0.2% or more may be used.

In the present disclosure, the FRP preferably has a plurality of reinforcing fiber layers. As shown in fig. 8, a plurality of reinforcing fiber layers 13b are preferably arranged along the circulating direction D₁And (4) forming. The number of the reinforcing fiber layers in the FRP may be 1, 2 or more, 4 or more, or 8 or more. On the other hand, the number of reinforcing fiber layers in the FRP is, for example, 30 or less.

4. Module

The module in this disclosure has the above-described first member, second member, and restraining member. In addition, it is preferable that the module in the present disclosure has a plurality of non-overlapping portions. This is because the deterioration of the restraining member due to the pressure variation can be further suppressed. Preferably, the plurality of non-overlapping portions are located in respective regions facing the first member. The number of the non-overlapping portions located in the region facing the first member may be 1, 2 or more, 4 or more, or 8 or more. The number of the non-overlapping portions located in the region facing the first member is, for example, 30 or less.

The use of the module in the present disclosure is not particularly limited, and for example, a module for vehicle use is exemplified. In addition, in the present disclosure, a vehicle having the above module may also be provided.

The present disclosure is not limited to the above-described embodiments. The above-described embodiments are examples, and any form thereof having substantially the same configuration as the technical idea described in the claims of the present disclosure and having the same operation and effect is included in the technical scope of the present disclosure.

Comparative example 1

As shown in fig. 9A, a prepreg of carbon fiber reinforced resin (CFRP) having a base fiber layer and a reinforcing fiber layer is placed around the outer peripheral surface of a mold M corresponding to the shapes of the first member and the second member, and the preform is molded in an autoclave together with the mold M. Thereafter, the mold M is removed, and the constraining member 3 is obtained. The base fibre layer is a 0 ° fibre layer parallel to the direction of wrap around. On the other hand, the reinforcing fiber layer is a 90 ° fiber layer formed on one surface side of the base fiber layer and orthogonal to the circulating direction. In addition, the number of the base fiber layers was 34, and 4 reinforcing fiber layers were provided for every 4 base fiber layers. The resulting restraining member was 3.06mm thick and 15mm wide. In addition, as shown in fig. 9A, the positions of the reinforcing fiber layers with respect to the base fiber layer are adjusted so that the non-overlapping portions a to D in the 4 reinforcing fiber layers are all located at the rounded portions (R portions) of the second member 2.

[ example 1]

As shown in fig. 9B, a constraining member was obtained in the same manner as in comparative example 1, except that the position of the innermost non-overlapping portion a among the non-overlapping portions a to D was changed to a region facing the first member.

[ example 2]

As shown in fig. 9C, a restraining member was obtained in the same manner as in comparative example 1, except that the positions of all the non-overlapping portions a to D were changed to the regions facing the first member.

[ evaluation ]

Fatigue tests were performed using the constraining members obtained in examples 1 and 2 and comparative example 1. Specifically, as shown in fig. 10A, B, the restraining member 3 was attached to a pair of jigs 20, pulsation (stress ratio 0.1) was performed by vibrating only one of the jigs 20, and the number of cycles until breakage was measured. As the load conditions, condition I (100.4kN) and condition II (122.4kN) were used. The results are shown in table 1, table 2 and fig. 11.

[ TABLE 1]

Condition I	Comparative example 1	Example 1	Example 2
				Load [ kN]	100.4	100.4	100.4
Stress [ MPa ]]	1094	1094	1094
				Period (times)]	19300	30215	38830

[ TABLE 2]

Condition II	Comparative example 1	Example 1	Example 2
				Load [ kN]	122.4	122.4	122.4
Stress [ MPa ]]	1333	1333	1333
				Period (times)]	5972	6756	16782

As shown in tables 1 and 2 and fig. 11, it was confirmed that examples 1 and 2 were less likely to break and had good durability as compared with comparative example 1. That is, it was confirmed that the position of the non-overlapping portion in the reinforcing fiber layer has a large influence on the durability. In particular, in example 2, a significantly excellent effect was obtained. Specifically, under condition I, example 2 increased the number of cycles until breakage by 2.0 times as compared to comparative example 1. In addition, in condition II, the cycle number until fracture of example 2 was increased by 2.8 times as compared to comparative example 1.