JPS6146695B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to flywheels for use in storing energy in the form of rotational energy. BACKGROUND ART Conventionally, it has been considered to store surplus power at night, or store exhaust energy that would have been released into the atmosphere, and take it out and use it when necessary. As a form of energy storage for this purpose, a method of storing energy in the form of flywheel rotational energy has recently been developed, and because of its advantages such as high efficiency and high storage energy density, It is viewed as extremely promising. However, there are still points to be developed in the flywheel used here. That is, the flywheel is formed into a disk shape, and the rotational energy (E) is: E=πh/4r ₂ (r ₂ ⁴ − _{r 1} ⁴ )σθ r ₁ : Inner diameter of the rotating body r ₂ : Outer diameter of the rotating body h: Width of the rotating body, σθ: Strength of the rotating body in the circumferential direction.The energy density (e) per weight of the flywheel is e=E/W=(r ₂ ⁴ − r ₁ ⁴ )/ 4r ₂ ² (r ₂ ²
−r ₁ ² )・σθ/ρ=(r ₂ ² +r ₁ ² )/4r ₂ ²
・σθ/ρ W: Weight of the rotating body (W=ρπh(r ₂ ² − r ₁ ² )) ρ: Density of the rotating body. Therefore, the energy density e is proportional to the specific intensity (σθ/ρ), and the specific intensity (σθ/ρ) is proportional to the specific intensity (σθ/ρ).
It can be said that a material with a larger value of ρ) is more suitable for a flywheel. Materials that meet these requirements include fiber reinforced plastics (FRP), maraging steel, etc., and the fracture strength σB, density ρ, and specific strength σB/ρ of these materials are as follows.

[Table] Steel As shown above, Kevlar 49 has the highest specific strength,
Even with E-glass, it is 2.4 times that of maraging steel.
Therefore, it is clear that fiber reinforced plastic (FRP) is an excellent material for flywheels. On the other hand, when molding a flywheel using such excellent FRP, there is a filament winding method that utilizes the strength of reinforcing fibers as is. In this method, reinforcing fibers are sequentially wound to form a disk shape, and the fibers are bonded by resin, so the strength in the circumferential direction (fiber direction) is extremely high. However, during its rotation, the flywheel has a radial stress σr at a position of radius r (approximately when the flywheel is made of isotropic material) σr=ρr ₂ ² ω ² /g3+μ/8{ 1+(r ₁ /r
₂ ) ² - (r/r ² ) ² - (r ₁ /r) ² } ω: angular velocity μ: Poisson's ratio acts, and this affects the bonding strength of the resin, so The strength in the radial direction (direction perpendicular to the fibers) is extremely small compared to the strength in the radial direction (direction perpendicular to the fibers). For example, in the case of a rotating plate using E glass, the breaking strength in the circumferential direction σ〓 _B = 120Kg/mm ² , while the breaking strength in the radial direction σ _rB is approximately σ _rB = 2.0
Kg/ ^mm2 . Therefore, even though the strength in the circumferential direction is sufficient, the flywheel may be damaged in the radial direction, and the advantages of FRP cannot be fully utilized. Therefore, an optimal design is desired in which the breaking strength of the flywheel is determined by the breaking strength in the circumferential direction. In view of the above circumstances, it is an object of the present invention to provide a flywheel having a structure that enables such optimal design. Corresponding to this purpose, the spoked energy storage flywheel of the present invention includes an annular or cylindrical outer ring that constitutes at least a portion of a rotational energy storage section, and spokes that connect the outer ring to a rotating or boss section. The spokes are characterized in that, when subjected to centrifugal force, the spokes are configured to expand and follow the radial deformation of the outer ring, or to press against the outer ring. The details of this invention will be explained below with reference to the drawings showing one embodiment. In the figure, 1 is a flywheel. The flywheel 1 includes an inner ring 2 at the center and an outer ring 3 concentrically outside the inner ring 2, and the inner ring 2 and the outer ring 3 are arranged by a plurality of spokes 4 equally divided in the circumferential direction. combined. The inner ring 2 also constitutes a boss part, and there are no particular restrictions on its constituent material, but as mentioned above, it is advantageous to use a material with a large specific strength σθ/ρ, such as FRP, for storing rotational energy. It is. The outer ring 3 is located outside the inner ring 2 at a distance and forms the main storage area for rotational energy in the flywheel, and is made of a material with a high specific strength σθ/ρ, such as FRP. It is desirable to configure the Spoke 4 divides the circumference equally into 6
The cross section included in the plane perpendicular to the center of rotation 5 has a hexagonal ring shape, one side 6 of which is fixed to the inside of the outer ring 3 with adhesive or the like, and the opposite side 7 to the inner ring 2. The outer ring 3 is fixed to the inner ring 2 by adhesive or the like, thereby supporting the outer ring 3 with respect to the inner ring 2. The two sides 8, 9 and 10, 11 between both sides 6 and 7 are continuous through the bent portions 12, 12', and when a centrifugal force acts on them, side 8 (same as side 10) As shown by the medium phantom line 8', the spoke 4 is deformed into a pantograph shape, and the radial length of the spoke 4 increases in cooperation with the elongation of the material. The material constituting the spokes 4 has a higher specific elastic modulus than the material constituting the outer ring 3.
Select a material with a small Et/ρ (Et: longitudinal elastic modulus, ρ...density), so that the radial elongation when centrifugal force is applied is equal to the radial elongation of the outer ring 3, or the outer ring 3 The radial elongation should be slightly larger than the radial elongation. Adjacent spokes are in contact at sides 9 and 11, but they do not necessarily need to be fixed together. In the flywheel configured in this way, the main storage part of the rotational energy is formed in the annular shape as the outer ring 3, so even if the flywheel is rotated at the same number of rotations, it will not change when the flywheel is formed into a disk shape. In comparison, the maximum radial stress acting on the outer ring 3 is small, and therefore the possibility that the flywheel will be destroyed by the radial stress is reduced. Not only that, when the flywheel rotates and centrifugal force acts on it, the spokes 4 elongate due to elongation of the material and mechanical deformation of the sides 8 and 10, and the amount of elongation is the amount of elongation of the outer ring 3. The outer ring 3 is equal to or slightly larger than the radial elongation amount, so the outer ring 3 receives a pressing force from the spokes 4, and it is also possible to reduce the radial stress generated within the outer ring 3. Furthermore, if the amount of extension of the spokes 4 is insufficient relative to the outer ring 3, the amount of extension of the spokes 4 can be adjusted by bonding weights 13 to the inner surface of the side 6 of the spokes 4. Moreover, the balance adjustment of the entire rotating body, which was conventionally performed by providing a notch or the like, can be easily performed by attaching adjustment weights 14 to the inner surface of the spokes 4 as necessary. In addition, when manufacturing the flywheel, outer ring 3, spokes 4
Since the inner ring 2 and the inner ring 2 can be manufactured in separate processes and assembled later, the scale of each molding equipment can be small, and it is suitable for mass production, which is particularly advantageous when aiming for a large flywheel. As is clear from the above description, according to the present invention, the main rotational energy storage section is configured with an annular outer ring, and the deformation of the spokes caused by the shape and material of the spokes follows the elongation of the outer ring. By doing so, it is possible to obtain an energy storage flywheel with spokes that can be optimally designed to have the breaking strength of the flywheel equal to the breaking strength of the reinforcing fibers constituting the outer ring.

[Brief explanation of the drawing]

The figure is a partial cross-sectional view showing a spoked energy storage flywheel according to an embodiment of the present invention. 1...Flywheel, 2...Inner ring, 3...Outer ring, 4
... Spoke, 12, 12'... Bent part, 13... Weight, 14... Adjustment weight.

Claims (1)

[Scope of Claims] 1. An annular or cylindrical outer ring constituting the main part of the rotational energy storage unit, and spokes that connect the outer ring to a rotating shaft or a boss, the spokes having a specific elastic modulus higher than that of the outer ring. (The spokes are made of a material with a small elastic modulus/density, and are configured so that when subjected to centrifugal force, the spokes either expand and follow the radial deformation of the outer ring, or press the outer ring. An energy storage flywheel with spokes, characterized in that: 2. The spokes have a hexagonal annular cross-sectional shape, one side is fixed to the inner side of the outer ring, and the opposite side is fixed to the boss portion or the rotating shaft. A spoked energy storage flywheel according to claim 1, characterized in that the spokes are provided with bent portions near the outer ring portion,
The energy storage flywheel with spokes according to claim 1 or 2, characterized in that the degree of freedom against deformation in the radial direction is thereby increased. 4. Claim 1, wherein the flywheel is provided with a weight for promoting the elongation of the spokes under the action of centrifugal force.
The spoked energy storage flywheel according to item 1, 2, or 3.