JP2016050626A - Flywheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flywheel capable of reducing stress generated in an inside during rotation of the flywheel, and thereby, capable of achieving high speed rotation.SOLUTION: A flywheel 1 includes: a wheel ring 3 having a large diameter part 5, and a small diameter part 6 projecting from the large diameter part 5 to an axial direction z of a rotation axis 2 and having a diameter smaller than that of the large diameter part 5; and a band 4 externally fitted to the small diameter part 6. Rigidity of the wheel ring 3 in a circumferential direction θ is set to be lower than rigidity of the band 4 in the circumferential direction θ.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flywheel that is mounted on a flywheel battery device or the like and rotates to store inertial energy.

2. Description of the Related Art Conventionally, flywheel battery devices that convert electric energy into rotational inertial energy of a flywheel and store it are known.
In order to withstand the centrifugal force generated during high-speed rotation of the flywheel, a material with a high specific strength (a value obtained by dividing the material strength by the density) is required as the material of the flywheel, and in order to achieve a high weight energy density Therefore, it is desirable to remove a portion of the flywheel that has a small contribution to energy.

  Therefore, conventionally, a flywheel that has a hollow cylindrical body and is formed using a fiber-reinforced plastic such as carbon-fiber-reinforced plastic (CFRP) has been proposed (see Patent Document 1 below). ). In the flywheel described in Patent Literature 1, the flywheel is configured as an integral member, and the reinforcing fibers of the fiber-reinforced plastic are oriented in the circumferential direction (that is, the rotational direction of the flywheel).

JP-A-9-267402

The weight energy density of the flywheel battery device depends on the outermost peripheral speed of the flywheel. Therefore, in order to increase the energy density of the flywheel, it is desirable to rotate the flywheel as fast as possible.
However, when the rotational speed of the flywheel is increased, the flywheel expands to the outer peripheral side due to the centrifugal force generated by the rotation of the flywheel, and accordingly, a large distortion may occur inside the flywheel. As a result, a large stress may be generated inside the flywheel.

  The inventors of the present application have studied to further increase the speed of the flywheel (for example, to increase the outermost peripheral speed of the flywheel from about 800 (m / sec) to 1500 (m / sec) or more). Yes. However, when a flywheel made of an integral member of a hollow cylindrical body as shown in Patent Document 1 is rotated at such a high speed, the magnitude of the stress generated in the flywheel exceeds the material strength. However, there is a problem that such high speed cannot be realized. Therefore, the inventors of the present application are considering devising the structure of the flywheel to reduce the stress generated inside during the rotation of the flywheel.

  Accordingly, an object of the present invention is to provide a flywheel capable of reducing the stress generated inside during the rotation of the flywheel, thereby realizing a higher speed rotation.

  The invention according to claim 1 for achieving the above object is a flywheel (1; 31; 41) for storing inertia energy by rotating about a predetermined rotation axis (2). A first ring having a portion (5; 45) and a small-diameter portion (6; 46, 47) having a smaller diameter than the large-diameter portion protruding from the large-diameter portion in the axial direction (z) of the rotation axis A member (3; 23; 33; 43) and a second ring member (4; 44) externally fitted to the small-diameter portion, and the rigidity in the circumferential direction (θ) of the first ring member is Provided is a flywheel that is set lower than the rigidity in the circumferential direction (θ) of the second ring member.

According to a second aspect of the present invention, the first ring member has a plurality of divided bodies (7; 27) divided in the circumferential direction (θ) by a dividing surface (7A; 27A) perpendicular to the circumferential direction (θ). 2), and the plurality of divided bodies are the flywheel according to claim 1, which are bundled by the second ring member.
According to a third aspect of the present invention, the first ring member is formed using fiber reinforced plastic, and the orientation direction of the reinforced fiber of the fiber reinforced plastic is the radial direction of the first ring member ( The flywheel according to claim 1 or 2, wherein r).

According to a fourth aspect of the present invention, the second ring member is formed using fiber reinforced plastic, and the fiber orientation direction of the fiber reinforced plastic is the circumferential direction of the second ring member (θ It is a flywheel as described in any one of Claims 1-3 which are these.
In the following description, “the circumferential component of stress” is referred to as “circumferential stress”, and “stress radial component” is referred to as “radial stress”.

  In the above description, numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

According to the structure of Claim 1, the flywheel is comprised by the assembly which assembled the 1st ring member and the 2nd ring member.
The circumferential rigidity of the first ring member constituting the flywheel is low. Therefore, it is possible to reduce the circumferential stress generated inside the flywheel during rotation. On the other hand, by reducing the rigidity in the circumferential direction of the first ring member, the centrifugal force caused by the rotation of the flywheel can be reduced during rotation of the flywheel as compared with the case where the rigidity in the circumferential direction of the first ring member is high. It is susceptible to damage and may therefore swell significantly radially outward. When the amount of expansion of the flywheel is large, the distortion inside the flywheel increases, and there is a risk that circumferential and radial stresses generated inside the flywheel in a rotating state will increase.

  In Claim 1, the 2nd ring member with higher rigidity of the circumferential direction than the 1st ring member is externally fitted by the small diameter part of the 1st ring member. Thereby, the expansion | swelling to the outward of the radial direction of a 1st ring member can be suppressed, As a result, reduction of the stress of the circumferential direction and radial direction which generate | occur | produce inside when the flywheel 1 rotates can be aimed at. Moreover, even if it is a case where the rigidity of the circumferential direction of a 1st ring member is provided low by externally fitting a 2nd ring member to a small diameter part, the rigidity of the circumferential direction of the whole flywheel can be improved.

Furthermore, since the second ring member fitted around the small diameter portion has a smaller diameter than the large diameter portion, the centrifugal force acting on the second ring member during rotation of the flywheel can be suppressed. Thereby, expansion of the 2nd ring member can be controlled, and as a result, it can prevent that the stress of the peripheral direction generated in the inside of a flywheel resulting from the 2nd ring member increases.
As described above, it is possible to reduce the stress generated inside during the rotation of the flywheel, and thus it is possible to provide a flywheel capable of realizing higher-speed rotation.

According to the structure of Claim 2, the 1st ring member is comprised by the some division body. By dividing the first ring member in the circumferential direction, the circumferential rigidity of the entire first ring member can be further reduced. As a result, the first ring member with reduced circumferential rigidity can be realized with a relatively simple configuration.
Moreover, the some division body is bundled by the 2nd ring member. Therefore, it can prevent that the several division body which comprises a 1st ring member disperses mutually.

  According to the configuration of the third aspect, since the orientation direction of the reinforcing fibers of the first ring member is the radial direction of the flywheel, the first ring member has high radial rigidity and strength, but the circumferential direction Stiffness and strength are low. Accordingly, the circumferential rigidity of the first ring member can be reduced. As a result, the first ring member with reduced circumferential rigidity can be realized with a relatively simple configuration.

  According to the structure of Claim 4, since the orientation direction of the reinforcing fiber of the second ring member is the circumferential direction of the flywheel, the circumferential rigidity and strength of the second ring member are high. Therefore, when the flywheel rotates at high speed, expansion of the first ring member at the time of high speed rotation of the flywheel can be effectively suppressed.

It is a disassembled perspective view which shows the structure of the flywheel which concerns on the 1st Embodiment of this invention. It is sectional drawing of the said flywheel. It is a perspective view which shows the structure of the division body contained in the said flywheel. It is a figure which shows the structure of the carbon fiber prepreg contained in the said division body. It is a perspective view which shows the structure of the division body contained in the wheel ring which concerns on the 2nd Embodiment of this invention. It is a disassembled perspective view which shows the structure of the flywheel which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the flywheel which concerns on the 4th Embodiment of this invention. It is a graph which expands and shows the principal part of the result of a 1st test. It is a graph which shows the result of a 1st test. 10 is an enlarged graph showing a main part of FIG. 9. It is a graph which shows the result of the 2nd test. It is a graph which shows the result of the 2nd test.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view showing a configuration of a flywheel 1 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the flywheel 1. FIG. 3 is a perspective view showing a configuration of the divided body 7 included in the flywheel 1. FIG. 4 is a view showing a configuration of the carbon fiber prepreg 8 included in the divided body 7.

  The flywheel 1 has a substantially hollow disk shape and is mounted on a flywheel battery device (not shown). In the flywheel battery device, the flywheel 1 is provided in a horizontal posture so as to be rotatable around, for example, a vertical rotation axis 2. A hollow portion of the flywheel 1 accommodates a rotating shaft (not shown) extending along the rotation axis 2 and components such as electrical components. Since the components are accommodated in the hollow portion of the flywheel 1, the flywheel battery device is made compact.

In the following description, the axial direction of the rotation axis 2 is referred to as an axial direction z. Moreover, let the radial direction of the flywheel 1 be the radial direction r. The radial direction r coincides with the rotational radius direction of the flywheel 1. Furthermore, let the circumferential direction of the flywheel 1 be the circumferential direction θ. The circumferential direction θ coincides with the rotational direction of the flywheel 1 around the rotation axis 2.
The flywheel 1 includes an assembly of one wheel ring (first ring member) 3 and two bands (second ring members) 4 that are separate from the wheel ring 3. The wheel ring 3 is provided integrally with each of the disk-shaped large-diameter portion 5 held in a posture (horizontal posture) perpendicular to the rotation axis 2 and both main surfaces (upper and lower surfaces) of the large-diameter portion 5. A total of two cylindrical small-diameter portions 6 are included. The outer diameter of the large diameter portion 5 is set to about 600 (mm), for example, and is set to a size about 2.5 times the outer diameter of the small diameter portion 6 (for example, about 240 (mm)). The large-diameter portion 5 and the two small-diameter portions 6 are coaxial and have the same inner diameter (for example, about 150 (mm)). One band 4 is fitted on each small diameter portion 6 one by one.

  The wheel ring 3 is formed using CFRP which is an example of fiber reinforced plastic. The orientation direction of the carbon fibers of the wheel ring 3 is mainly the radial direction r. That is, the carbon fibers of the wheel ring 3 are not oriented in the axial direction z or the circumferential direction θ. Therefore, the wheel ring 3 has high rigidity and high strength in the radial direction r, and low rigidity and low strength in the circumferential direction θ.

  The wheel ring 3 is divided into a plurality of equal parts (for example, 24 equal parts in FIG. 1) in the circumferential direction θ. In other words, the wheel ring 3 is divided in the circumferential direction θ by the dividing surface 7A (see FIG. 3) perpendicular to the circumferential direction θ, and as a result, is constituted by a plurality of (for example, 24 in FIG. 1) divided bodies 7. ing. By dividing the wheel ring 3 in the circumferential direction θ, the rigidity of the entire wheel ring 3 in the circumferential direction θ can be further reduced. Thereby, the wheel ring 3 with reduced rigidity in the circumferential direction θ can be realized with a relatively simple configuration.

  As shown in FIGS. 3 and 4, each divided body 7 is formed using a prepreg method. Specifically, the divided body 7 is formed by laminating carbon fiber prepregs 8 in the circumferential direction θ. Each carbon fiber prepreg 8 is a sheet-like material in which a carbon fiber is impregnated with a matrix resin (for example, epoxy resin), and has a convex shape that matches the cross-sectional shape along the radial direction r of the divided body 7. . The orientation direction of the carbon fiber of each carbon fiber prepreg 8 is only the longitudinal direction of the carbon fiber prepreg 8 as shown in FIG. After the carbon fiber prepreg 8 is unidirectionally laminated in the circumferential direction θ, the divided body 7 shown in FIG. 3 is obtained by curing with a matrix resin (for example, epoxy resin). Thereby, the division body 7 made of CFRP in which the carbon fibers are oriented only in the radial direction r can be obtained with a relatively simple configuration.

As shown in FIG. 1, each band 4 has a cylindrical shape. The length of the band 4 in the axial direction z is set to be equal to the length of the small diameter portion 6 in the axial direction z. The inner diameter of the band 4 is set substantially equal to that of the small diameter portion 6.
Each band 4 is formed using CFRP. The orientation direction of the carbon fibers of the band 4 is mainly the circumferential direction θ. That is, the carbon fibers of the band 4 are hardly oriented in the axial direction z or the radial direction r. Therefore, the band 4 has high rigidity and high strength in the circumferential direction θ, and low rigidity and low strength in the radial direction r. The band 4 uses a so-called filament winding method in which a tow impregnated with resin (a long fiber bundle composed of a large number of filaments and untwisted) is wound around a cylinder or a pressure vessel mold and then cured. Is formed.

  At the time of producing the flywheel 1, all the divided bodies 7 are arranged in the circumferential direction θ to form a ring body. Thereby, the large diameter part 5 and the two small diameter parts 6 of the wheel ring 3 are formed. Thereafter, the band 4 is fitted around the two small diameter portions 6 respectively. In this state, the outer peripheral surface 10 of the small-diameter portion 6 abuts on the inner peripheral surface 9 of the band 4 or faces the inner peripheral surface 9 with a minute gap.

  In a flywheel battery device (not shown), the flywheel 1 is extremely fast around the rotation axis 2 (for example, the outermost peripheral speed of the flywheel 1 is 1200 (m / sec) or more (for example, about 1500 (m / sec))). Rotate with The weight energy density of the flywheel 1 at this time is about 200 (Wh / kg). In such a high-speed rotation state, the small-diameter portion 6 of the wheel ring 3 is expanded outward in the radial direction r under the centrifugal force accompanying the rotation of the flywheel 1, and the outer peripheral surface 10 of the small-diameter portion 6 is the small-diameter portion. 6 is in pressure contact with the inner peripheral surface 9 of the band 4 that is fitted on the outer periphery. Then, further expansion of the wheel ring 3 is suppressed or prevented by the band 4. When the outer peripheral surface 10 of the small diameter portion 6 is pressed against the inner peripheral surface 9 of the band 4, the band 4 bundles the plurality of divided bodies 7. Therefore, the plurality of divided bodies 7 constituting the wheel ring 3 are prevented from being separated from each other.

As described above, according to the first embodiment, the flywheel 1 is constituted by an assembly in which the wheel ring 3 and the band 4 are assembled. The wheel ring 3 has low rigidity in the circumferential direction θ and high rigidity in the radial direction r.
The circumferential rigidity of the wheel ring 3 constituting the flywheel 1 is low. Therefore, it is possible to reduce the stress in the circumferential direction θ generated inside the flywheel 1 during rotation. On the other hand, by reducing the rigidity in the circumferential direction θ of the wheel ring 3, the centrifugal force due to the rotation of the flywheel 1 is rotated during the rotation of the flywheel 1 compared to the case where the rigidity in the circumferential direction θ of the wheel ring 3 is high. It is easily affected, and therefore may expand greatly outward in the radial direction r. When the expansion amount of the flywheel 1 is large, the distortion inside the flywheel 1 increases, and there is a risk that stress in the circumferential direction θ and the radial direction r generated inside the flywheel 1 in a rotating state increases.

  In this embodiment, a band 4 having higher rigidity in the circumferential direction θ than that of the wheel ring 3 is externally fitted to the small diameter portion 6 of the wheel ring 3. Thereby, the outward expansion of the wheel ring 3 in the radial direction r can be suppressed, and as a result, the stress in the circumferential direction θ and the radial direction r generated inside the flywheel 1 in a rotating state can be reduced. it can. Further, by externally fitting the band 4 to the small-diameter portion 6, even when the rigidity of the wheel ring 3 in the circumferential direction θ is provided low, the rigidity of the entire flywheel 1 in the circumferential direction θ can be increased.

Furthermore, since the band 4 fitted around the small diameter portion 6 has a smaller diameter than the large diameter portion 5, the centrifugal force acting on the band 4 when the flywheel 1 rotates can be suppressed. Thereby, the expansion of the band 4 can be suppressed, and as a result, it is possible to prevent an increase in the stress in the circumferential direction θ generated inside the flywheel 1 due to the band 4.
Moreover, since the wheel ring 3 is comprised by the some division body 7 divided | segmented by the circumferential direction (theta), reduction of the rigidity of the circumferential direction (theta) of the wheel ring 3 whole can be aimed at. Thereby, the rigidity of the circumferential direction (theta) of the wheel ring 3 whole can be reduced.

As described above, it is possible to reduce the stress generated inside when the flywheel 1 rotates, and thus it is possible to provide the flywheel 1 capable of realizing higher speed rotation.
Further, since the orientation direction of the carbon fibers in the band 4 is the circumferential direction θ, the rigidity and strength in the circumferential direction θ of the band 4 are high, and therefore the expansion of the wheel ring 3 during the high-speed rotation of the flywheel 1 Can be effectively suppressed.

FIG. 5 is a perspective view showing a configuration of the divided body 27 included in the wheel ring (first ring member) 23 according to the second embodiment of the present invention.
The wheel ring 23 is divided into a plurality of equal parts (for example, 24 equal parts) in the circumferential direction θ. In other words, the wheel ring 23 is divided in the circumferential direction θ by the dividing surface 27A perpendicular to the circumferential direction θ, and as a result, is constituted by a plurality of (for example, 24) divided bodies 27.

The difference between the divided body 27 according to the second embodiment and the divided body 7 according to the first embodiment (see FIG. 1 and the like) is that the divided body is not formed by the prepreg method, It is a point that the division body is formed using the technique.
The division body 27 is comprised from the three-dimensional carbon fiber fabric. Specifically, the divided body 27 is formed by converging carbon fibers (covering process), laminating a plurality of carbon fiber fabrics woven with the yarns, stitching them with in-plane yarns by an image processing stitching method, and then scouring them. Can be obtained.

Like the divided body 7, the divided body 27 formed of a three-dimensional carbon fiber fabric is provided so that the orientation direction of the carbon fibers is the radial direction r. The divided body 27 is obtained by converging a carbon fiber (covering process), laminating a plurality of carbon fiber fabrics woven with the yarn, stitching with an in-plane thread by an image processing stitching method, and then performing a scouring process. .
According to 2nd Embodiment, there exists an effect equivalent to the effect described in relation to 1st Embodiment.

Further, in the first and second embodiments, the divided bodies 7 and 27 are exemplified by the configuration in which the ring body is divided into 24 equal parts in the circumferential direction θ, but the number of equal parts is not limited to “24”. For example, other numbers such as “2”, “3”, “4”, “6”, “12” may be used. Further, the divided body may be formed by dividing the ring body into equal parts instead of equally dividing.
FIG. 6 is an exploded perspective view showing the configuration of the flywheel 31 according to the third embodiment of the present invention. In the third embodiment, portions common to the first embodiment are denoted by the same reference numerals as in FIG. 1 and description thereof is omitted.

  The flywheel 31 according to the third embodiment differs from the flywheel 1 according to the first and second embodiments in that instead of the wheel rings 3 and 23 (see FIG. 1 and FIG. 5 etc.), a wheel This is a point provided with a ring 33. The wheel ring 33 is not composed of a plurality of divided bodies, but is composed of an integral member. Similarly to the wheel rings 3 and 23, the wheel ring 33 is also provided so that the orientation direction of the carbon fibers becomes the radial direction r. The wheel ring 33 is made of a three-dimensional carbon fiber woven fabric, like the divided body 27 included in the wheel ring 23. Specifically, the wheel ring 33 is formed by converging carbon fibers (covering process), laminating a plurality of carbon fiber fabrics woven with the yarns, stitching them with in-plane yarns by an image processing stitching method, and then scouring them. Can be obtained.

According to 3rd Embodiment, except the effect relevant to the division body 7, there exists an effect equivalent to the effect described in relation to 1st Embodiment.
FIG. 7 is a cross-sectional view of a flywheel 41 according to the fourth embodiment of the present invention.
The flywheel 41 according to the fourth embodiment is different from the flywheel 1 according to the first to third embodiments (see FIG. 1 and the like) in that a plurality of (in this embodiment, two) large diameters. It is a point provided with a part.

The flywheel 41 has a configuration equivalent to that of two flywheels 1 (see FIG. 1) juxtaposed in the axial direction z and joined together. Specifically, the flywheel 41 is configured by an assembly of one wheel ring (first ring member) 43 and three bands (second ring members) 44 that are separate from the wheel ring 43. ing.
The wheel ring 43 includes two disk-shaped large-diameter portions 45 arranged at a predetermined interval in the axial direction z, and a cylinder provided integrally with the large-diameter portion 45 between the two large-diameter portions 45. The cylindrical first small-diameter portion 46 and two second cylindrical portions provided integrally with the large-diameter portion 45 on the upper side of the upper large-diameter portion 45 and on the lower side of the lower large-diameter portion 45. And a small-diameter portion 47. The two large diameter portions 45 are held in a posture (horizontal posture) perpendicular to the rotation axis 2 and have the same specifications. The two second small diameter portions 46 have the same specifications. The first and second small diameter portions 46 and 47 have the same outer diameter. The outer diameter of each large diameter portion 45 is set to about 600 (mm), for example, and is set to a size about 2.5 times the outer diameter (about 240 (mm)) of the small diameter portions 46 and 47. Yes. The large-diameter portion 45 and the small-diameter portions 46 and 47 are coaxial and have substantially the same inner diameter (about 150 (mm)). In FIG. 7, the dimension in the axial direction z of the first small diameter portion 46 is set to about twice the dimension in the axial direction z of the second small diameter portion 47.

  The band 44 includes an intermediate band 51 that is externally fitted to the first small diameter portion 46, and a total of two end bands 52 that are externally fitted to each second small diameter portion 47. The lengths of the intermediate band 51 and the end band 52 in the axial direction z are set to be equal to the lengths of the first and second small diameter portions 46 and 47, respectively. The inner diameters of the intermediate band 51 and the end band 52 are set to be equal to the outer diameters of the first and second small diameter portions 46 and 47, respectively. Therefore, in a state where the intermediate band 51 and the end band 52 are externally fitted to the first and second small diameter portions 46 and 47, respectively, the outer peripheral surfaces of the small diameter portions 46 and 47 are respectively the intermediate band 51 and the end band 52. Or are opposed to these inner peripheral surfaces with a small gap.

  In this case, the bands 51 and 52 (the intermediate band 51 and the end band 52) are formed using CFRP. The bands 51 and 52, like the band 4 (see FIG. 1 and the like), have a carbon fiber orientation direction mainly mainly in the circumferential direction θ, and therefore the band 4 has high rigidity and high strength in the circumferential direction θ. In addition, it has low rigidity and low strength in the circumferential direction θ in the radial direction r. The bands 51 and 52 are formed by using a so-called filament winding method. Among these, the intermediate band 51 is formed by directly winding a tow impregnated with resin around the outer peripheral surface of the first small diameter portion 46. ing.

According to 4th Embodiment, there exists an effect equivalent to the effect described in relation to 1st Embodiment.
Next, the first and second tests will be described.
<First test>
In the first test, the stress generated inside when the flywheel 1 of the first embodiment was rotated at high speed around the rotation axis 2 was determined by analysis by a finite element method (FEM). In the first test, the flywheel 1 having the wheel ring 3 equally divided into “2”, “3”, “4”, “6”, “12”, and “24” was set as a calculation target. Further, the flywheel 31 having a wheel ring that is not divided (that is, the wheel ring 33) is also subject to calculation. In the first test, the inner diameter dimension of each wheel ring 3, 33 was 150 (mm), the outer diameter dimension was 500 (mm), and the dimension in the axial direction z was 200 (mm). The rotational speed of each flywheel 1, 31 was set to 60000 (rpm) (in this case, the outermost peripheral speed was 1570 (m / sec)).

  Under the above conditions, the in-plane distribution of stress at the center position in the axial direction z in the wheel rings 3 and 33 was obtained by calculation. The in-plane distribution of stress in the radial direction r in the wheel rings 3 and 33 is shown in FIGS. 8 and 9, and the in-plane distribution of stress in the circumferential direction θ in the wheel rings 3 and 33 is shown in FIG. 8 to 10, the reference for the radial position (that is, “zero”) is the rotation axis 2. Note that the calculation result for the flywheel 31 is represented by “no division” in FIGS. 8 to 10.

From the results shown in FIG. 8, the radial direction stress generated in the wheel ring 33 is less than the upper limit of strength at all radial positions regardless of the number of divisions of the wheel rings 3 and 33. I understand.
On the other hand, the results shown in FIG. 9 indicate that the stress in the circumferential direction θ generated in the wheel rings 3 and 33 is reduced as the number of divisions of the wheel rings 3 and 33 is increased. It is considered that this is because the stress in the circumferential direction θ generated in the wheel rings 3 and 33 is reduced as the number of divisions is increased. In particular, it was found that when the number of divisions was “12” and “24”, a low stress in the circumferential direction θ could be realized, and the strength was lower than the upper limit at all radial positions. It should be noted that since stress in the circumferential direction θ is generated in the band 4, even if the number of divisions is increased from “24”, the stress in the circumferential direction θ cannot be further reduced.
<Second test>
In the second test, the stress generated in the flywheel 31 when the flywheel 31 of the third embodiment is rotated around the rotation axis 2 at high speed is obtained by analysis using a finite element method (FEM). It was. In the first test, the inner diameter of the wheel ring 33 was 150 (mm), the outer diameter was 600 (mm), and the dimension in the axial direction z was 200 (mm). The rotational speed of the flywheel 31 was set to 50000 (rpm) (in this case, the outermost peripheral speed was about 1570 (m / sec)).

Under the above conditions, the in-plane distribution of stress at the center position in the axial direction z in the wheel ring 33 was obtained by calculation. The in-plane distribution of stress in the radial direction r in the wheel ring 33 is shown in FIG. 11, and the in-plane distribution of stress in the circumferential direction θ in the wheel ring 33 is shown in FIG. In FIG. 11 and FIG. 12, the reference for the radial position (that is, “zero”) is the rotation axis 2.
From the results shown in FIG. 11, it is understood that the stress in the radial direction r generated in the wheel ring 33 is lower than the upper limit of strength at all radial positions regardless of the number of divisions of the wheel ring 33. .

On the other hand, from the results shown in FIG. 12, it was found that although the stress in the circumferential direction θ can be realized, there are places where the value of the stress in the circumferential direction θ increases depending on the radial position.
As mentioned above, although four embodiment of this invention was described, this invention can also be implemented with another form.
For example, in the fourth embodiment, the configuration including two large-diameter portions 45 has been described as an example, but a configuration including three or more large-diameter portions 45 may be used.

Moreover, CFRP is suitable as the fiber reinforced plastic. However, fiber reinforced plastics containing fibers other than carbon fibers, such as glass fibers, boron fibers, and aramid fibers, as reinforcing fibers are used as the base material for the wheel rings 3, 23, 33, 43 and / or the bands 4, 44 of the present application. It may be used.
As the matrix resin for fiber reinforced plastics, epoxy resin was used as an example, but in addition, unsaturated polyester resin, vinyl ester resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, furan resin, maleimide resin, acrylic resin, etc. It can be used as a matrix resin.

  In addition, various modifications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 ... Flywheel, 2 ... Rotation axis, 3 ... Wheel ring (1st ring member), 4 ... Band (2nd ring member), 5 ... Large diameter part, 6 ... Small diameter part, 7 ... Divided body, 23 ... wheel ring (first ring member), 27 ... divided body, 31 ... flywheel, 33 ... wheel ring (first ring member), 41 ... flywheel, 43 ... wheel ring (first ring member), 44 ... band (second ring member), 45 ... large diameter part, 46 ... first small diameter part (small diameter part), 47 ... second small diameter part (small diameter part), r ... radial direction, z ... axial direction , Θ ... Circumferential direction

Claims (4)

A flywheel for storing inertia energy by rotating about a predetermined rotation axis,
A first ring member having a large-diameter portion and a small-diameter portion projecting in the axial direction of the rotation axis from the large-diameter portion and having a smaller diameter than the large-diameter portion;
A second ring member externally fitted to the small diameter portion,
A flywheel in which a circumferential rigidity of the first ring member is set to be lower than a circumferential rigidity of the second ring member. The first ring member is configured by a plurality of divided bodies divided in the circumferential direction by a dividing surface perpendicular to the circumferential direction,
The flywheel according to claim 1, wherein the plurality of divided bodies are bundled by the second ring member at least during rotation of the flywheel.   The said 1st ring member is formed using the fiber reinforced plastic, The orientation direction of the reinforced fiber of the said fiber reinforced plastic is a radial direction of the said 1st ring member, The Claim 1 or 2 Flywheel.   The said 2nd ring member is formed using the fiber reinforced plastic, The orientation direction of the reinforced fiber of the said fiber reinforced plastic is the circumferential direction of the said 2nd ring member, Any of Claims 1-3 A flywheel according to claim 1.

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