Flywheel device and rotary electric machine

Abstract

This flywheel device has: a support body; a rotary shaft; a pair of disk members that are fixed while spaced away over the rotary shaft; a pair of inside cylindrical members that are respectively connected to the outer circumference of the disk members and are formed coaxially with the rotary shaft; a pair of outside cylindrical members that are disposed on the support body facing the outer circumferences of the inside cylindrical members, and are disposed away from the outer circumferences of the inside cylindrical members, the disk plate members and the inside cylindrical members constituting a flywheel. The inside cylindrical members are formed by disposing, in a continuous manner in the circumferential direction, inside magnets having magnetic poles on the outer circumference of the inside cylindrical members, and the outside cylindrical members have outside magnets disposed in a continuous manner in the circumferential direction, the outside magnets facing the inside magnets with the same poles. Due to the repulsive force of the inside magnets and the outside magnets, the rotary shaft is rotatably supported in a noncontact manner with respect to the support body. The center of the width in the axial direction of the inside magnets is shifted from the center of the width in the axial direction of the outside magnets.

Description

Flywheel device and rotating electric machine

[0001] The present invention relates to a flywheel device and a rotating electric machine.

[0002] Generally, generators generate electricity by rotating a rotor inside a stator fixed to a support, and the resulting induced electromotive force. The rotational motion of the rotor is driven by torque generated by, for example, hydroelectric power, thermal power, nuclear power, or an internal combustion engine such as a diesel engine.

[0003] However, when the bearing supporting the rotor is of a contact type, the rotational energy of the rotor is lost due to friction. Therefore, to suppress the energy loss, non-contact type bearings such as air dynamic bearings and magnetic bearings have been proposed (see Patent Document 1, etc.).

[0004] Among these, magnetic bearings that use permanent magnets are more effective than magnetic bearings that use electromagnets in that they can direct rotation without consuming unnecessary power.

[0005] Furthermore, the applicant has proposed using the inertial energy of a flywheel structure to sustain the rotational motion of the rotor for a longer period of time (see Patent Document 2).

[0006] JP 11-325074 A JP 2018-191507 A

[0007] However, when magnets are placed facing each other so that the repulsion between them is large, the magnetic flux lines have curves, making the repulsion points unstable and prone to misalignment in the axial direction.

[0008] In view of these issues, the present invention aims to provide a flywheel device that provides stable rotation by suppressing not only circumferential (radial) friction but also axial (axial) movement without causing friction, and that can sustain rotational energy for a longer period of time.

[0009] A flywheel device according to one embodiment of the present invention comprises: a support body; a rotating shaft; a pair of disk members fixed on the rotating shaft at a distance from each other; inner cylindrical members each connected to the outer periphery of the disk members and formed coaxially with the rotating shaft; and a pair of outer cylindrical members each arranged on the support body opposite the outer periphery of the inner cylindrical member and spaced apart from the outer periphery of the inner cylindrical member, wherein the disk members and the inner cylindrical member form a flywheel; the inner cylindrical member is formed by circumferentially consecutively arranging inner magnets having magnetic poles on their outer peripheries; the outer cylindrical member has circumferentially consecutively arranged outer magnets facing the inner magnets with the same poles facing each other; the rotating shaft is rotatably supported by the support body without contact due to the repulsive force between the inner magnets and the outer magnets; and the center of the axial width of the inner magnets is offset from the center of the axial width of the outer magnets.

[0010] Another embodiment of the present invention relates to a rotating electric machine including the above-mentioned flywheel device, a rotor fixed to the rotating shaft midway between the pair of disc members, and a stator disposed on the support body.

[0011] According to the present invention, it is possible to provide a flywheel device that does not generate friction in the circumferential direction (radial direction) and suppresses movement in the axial direction without generating friction, providing stable rotation and maintaining rotational energy for a longer period of time.

[0012] It is a front view of the flywheel device of the first embodiment of the present invention. It is a cross-sectional view of the flywheel device shown in Figure 1. It is a partial cross-sectional view of the flywheel device of the second embodiment of the present invention. It is a front view of a modified example of the flywheel device of the first embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Flywheel Device) Figures 1 and 2 are a front view and a cross-sectional view illustrating a flywheel device 100 according to a first embodiment. The flywheel device 100 includes a support body 10, a rotating shaft 20, a pair of disk members 30 fixed on the rotating shaft 20 at a distance from each other, a pair of inner cylindrical members 40 connected to the outer peripheries of the disk members 30 and formed coaxially with the rotating shaft 20, and a pair of outer cylindrical members 50 disposed on the support body 10 facing the outer peripheries of the inner cylindrical members 40 and spaced apart from each other. In this specification, the direction parallel to the rotating shaft 20 is referred to as the axial direction, and the direction perpendicular to the rotating shaft 20 and extending circumferentially around the disk members 30 is referred to as the circumferential direction or radial direction. Furthermore, the direction in which the pair of disk members 30 approach each other toward the plane of symmetry is referred to as the inward thrust direction, and the direction in which they move away from each other is referred to as the outward thrust direction.

[0014] The support body 10 is provided with an outer cylindrical member 50 (described later) and is a structure that supports other members of the flywheel device 100 in a non-contact manner. The support body 10 may further be provided with a stator 80 of a rotating electric machine 300 (described later).

[0015] The support 10 may have any shape and may be made of any material as long as it has the strength to withstand the repulsive force of the magnet acting on the outer cylindrical member 50. For example, soft magnetic materials such as iron, silicon steel, permalloy, and sendust, and non-magnetic materials such as carbon and wood can be used.

[0016] The rotating shaft 20 is a central axis of rotation for the pair of disk members 30. The rotating shaft 20 is also provided with a rotor 70 of the rotating electric machine 300, as will be described later, and the rotor 70 can be rotated in conjunction with the rotation of the rotating shaft 20.

[0017] The disk members 30 are a pair of circular members spaced apart from each other on the rotary shaft 20, with the rotary shaft 20 as their center. The disk members 30 have an area larger than the cross-sectional area of ​​the rotary shaft 20.

[0018] As will be described later, the disk member 30 is preferably lightweight and hollow. It is also preferably smaller in axial width than the inner cylindrical member 40.

[0019] The inner cylindrical members 40 are connected to the outer peripheries of the disk members 30 and are formed coaxially with the rotation shaft 20. The inner cylindrical member 40 is formed by circumferentially arranging inner magnets 45, each having a magnetic pole on its outer periphery, in a continuous manner. The inner magnets 45 preferably have a cylindrical shape. The inner magnet 45 may be formed as a single cylindrical magnet (see FIG. 1), or may be formed by dividing the magnets into multiple magnets arranged in a cylindrical shape so that the magnetic poles on their outer peripheries are the same (see FIG. 4).

[0020] The magnet used for the inner magnet 45 is preferably a permanent magnet with strong magnetic force, and for example, a rare earth magnet such as a neodymium magnet or a samarlite cobalt magnet, or a ferrite magnet can be used.

[0021] The inner cylindrical member 40 and the disk member 30 constitute a flywheel 60, and the moment of inertia can sustain the rotational energy for a longer period of time.

[0022] Here, the moment of inertia J of a disk-shaped flywheel having a diameter D is ｄ and the moment of inertia J of the cylindrical flywheel ｃ can be calculated as follows:

[0023] J ｄ = 1 / 2WD ２ J ｃ = 1 / 2W(D ２ +d ２ ) (W is the weight of the flywheel, and d is the diameter of the hollow part of the cylindrical flywheel.)

[0024] As described above, since the cylindrical flywheel has a larger moment of inertia, it is preferable that the mass of the inner cylindrical member 40 be larger and the disk member 30 be lighter.

[0025] The outer cylindrical members 50 are disposed on the support body 10 facing the outer periphery of the inner cylindrical member 40, and are spaced apart from the outer periphery of the inner cylindrical member 40. The outer cylindrical member 50 has outer magnets 55 disposed continuously in the circumferential direction, with the outer magnets 55 facing the inner magnets 45 with the same poles facing each other. The outer magnets 55 preferably have a cylindrical shape. The outer magnet 55 may be formed as a one-piece cylindrical magnet, like the inner magnet 45 (see FIG. 1), or may be formed by dividing the magnets into segments and arranging them in a cylindrical shape so that the magnetic poles of their outer peripheries are the same (see FIG. 4).

[0026] The magnet used for the outer magnet 55 is preferably a permanent magnet with strong magnetic force, similar to the inner magnet 45, and for example, a rare earth magnet such as a neodymium magnet or a samarlite cobalt magnet, or a ferrite magnet can be used.

[0027] Due to the repulsive force between the inner magnet 45 and the outer magnet 55, the rotating shaft 20 and the inner cylindrical member 40 and inner magnet 45 provided thereon are rotatably supported without contact with the support 10.

[0028] Furthermore, in flywheel device 100 of the present invention, axial width centers 46 of inner magnets 45 are offset from axial width centers 56 of outer magnets 55. Preferably, width centers 46 of inner magnets 45 are offset inward in the thrust direction (directions moving closer to each other in the axial direction) or outward in the thrust direction (directions moving away from each other) with respect to width centers 56 of outer magnets 55.

[0029] 2 shows a structure in which the width centers 46 of the inner magnets 45 are offset inward in the thrust direction relative to the width centers 56 of the outer magnets 55. In this case, a radial repulsive force (arrow R) and a thrust repulsive force (arrow S) are generated between the width centers 46 of the inner magnets 45 and the width centers 56 of the outer magnets 55. Therefore, the flywheel 60 is indirectly clamped inward in the thrust direction by the outer magnets 55.

[0030] As described above, in the flywheel device 100 of the first embodiment of the present invention, the flywheel 60 can be maintained in a non-contact state in both the radial and axial directions by the external magnets 55, and in addition to its original function as a flywheel, it can also function as a magnetic bearing that levitates and supports the rotating shaft 20 including the rotor 70 using magnetic repulsion, thereby reducing friction that occurs during rotation. In other words, because the force acting on the bearing of one embodiment of the present invention is a repulsive force, it can hold the rotating shaft 20 in a position where the magnetic forces are balanced without requiring complex control. In addition, because the flywheel function and magnetic bearing function are integrated in this embodiment, the device can be made smaller.

[0031] 3 shows a flywheel device 200 according to a second embodiment of the present invention. The flywheel device 200 has a structure in which the width centers 46 of the inner magnets 45 are offset outward in the thrust direction relative to the width centers 56 of the outer magnets 55. In this case, too, a radial repulsive force (arrow R) and a thrust repulsive force (arrow S) are generated between the width centers 46 of the inner magnets 45 and the width centers 56 of the outer magnets 55. When one flywheel 60 attempts to move outward in the strut direction, the strut repulsive force between the other flywheel 60 and the opposing outer magnet 55 increases, suppressing movement in the strut direction.

[0032] In this way, in the flywheel device 200 of the second embodiment, the flywheel 60 can maintain a stable position in a non-contact state in both the radial and axial directions due to the external magnets 55, providing stable rotation without generating friction and enabling the rotational energy to be sustained for a longer period of time.

[0033] A third embodiment of the present invention relates to a rotating electric machine 300 including the above-described flywheel device. The rotating electric machine 300 includes the above-described flywheel device 100 or 200 of the present invention, and has a rotor 70 fixed to the rotating shaft 20 midway between the pair of disk members 30, and a stator 80 disposed on the support body 10.

[0034] The rotating electric machine 300 can be used as a generator or a motor. In the rotating electric machine 300, a portion of the rotor 70 may be in direct contact with an external terminal such as a brush, or a terminal portion (not shown) electrically connected to the rotor 70 may be in contact with an external terminal such as a brush.

[0035] Although various embodiments and modifications have been described above, the present invention is not limited to these. The number and shapes of various parts in the embodiments are merely examples, and any other number and shape may be used.

[0036] Furthermore, each embodiment and modification may be applied alone or in combination. Other aspects that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0037] REFERENCE SIGNS LIST 10 Support 20 Rotating shaft 30 Disk member 40 Inner cylindrical member 45 Inner magnet 46 Center of axial width of inner magnet 50 Outer cylindrical member 55 Outer magnet 56 Center of axial width of outer magnet 60 Flywheel 70 Rotor 80 Stator 100 Flywheel device 200 Flywheel device 300 Rotating electric machine R Radial repulsive force S Strass repulsive force

Claims

1. A support; A rotation axis; A pair of disk members fixed on the rotating shaft at a distance from each other; a pair of inner cylindrical members each connected to an outer periphery of the disk member and formed coaxially with the rotation shaft; A pair of outer cylindrical members each disposed on the support member facing an outer periphery of the inner cylindrical member and spaced apart from the outer periphery of the inner cylindrical member. There was, a flywheel is formed by the disk member and the inner cylindrical member; The inner cylindrical member is formed by arranging inner magnets having magnetic poles on their outer circumferential surfaces in a continuous manner in the circumferential direction, The outer cylindrical member has outer magnets arranged continuously in a circumferential direction, the outer magnets facing the inner magnets with the same poles facing each other, The rotating shaft is rotatably supported without contact with the support by the repulsive force between the inner magnet and the outer magnet, a center of the axial width of the inner magnet in each of the two sets of the inner cylindrical member and the outer cylindrical member that face each other, the center of the axial width of the inner magnet being shifted by the same axial distance from the center of the axial width of the outer magnet in a direction away from the midpoint of the rotation axis between the inner cylindrical member and the outer cylindrical member of the two sets.

2. 2. The flywheel device according to claim 1, wherein the inner magnet and the outer magnet are formed into a cylindrical shape.

3. 3. The flywheel device according to claim 1, wherein an axial width of the inner cylindrical member is greater than an axial thickness of the disk member and smaller than an axial width of the outer cylindrical member.

4. A flywheel device according to any one of claims 1 to 3 is provided, A rotating electric machine comprising: a rotor fixed to the rotating shaft intermediate the pair of disk members; and a stator disposed on the support body.