JPH08200470A - Flywheel device - Google Patents

Abstract

PURPOSE: To rotate a rotary shaft at a high speed by increasing a natural vibration frequency of the rotary shaft. CONSTITUTION: A flywheel device comprises a rotary shaft 1 rotated with a vertical shaft serving as the center, flywheel 2 fixedly provided in the rotary shaft 1, two sets of upper/lower 4-axis control type radial magnetic bearings 3, 4 of contactlessly supporting the rotary shaft 1 in a radial direction and a superconductive bearing 5 of contactlessly supporting the rotary shaft 1 in an axial/radial direction. At least the one set of the radial magnetic bearings 3, 4 has an electric motor drive function of driving the rotary shaft 1 rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flywheel device used for an electric power storage device for converting surplus electric power into rotational kinetic energy of a flywheel and storing it.

[0002]

2. Description of the Related Art Conventionally, as a flywheel device of this type, a rotary shaft that rotates about a vertical axis, a flywheel that is fixedly mounted on the rotary shaft, and two upper and lower sets that support the rotary shaft in a radial direction without contact. 4 axis control type radial magnetic bearing,
2. Description of the Related Art There is known one including one or more sets of superconducting bearings that support a rotating shaft in a radial direction and an axial direction in a non-contact manner, and a generator motor that rotationally drives the rotating shaft. A superconducting bearing has, for example, a plurality of annular permanent magnets on the upward or downward end face of the flywheel, the magnetic flux distribution being symmetrical with respect to the rotation axis, and the magnetic flux distribution around the rotation axis being rotated. It is arranged concentrically so that it does not change, and in the fixed portion, the superconductor is a separated position where the magnetic flux of the permanent magnet enters a predetermined amount, and the position where the distribution of the invading magnetic flux does not change due to the rotation of the rotating body, It is arranged so as to face the permanent magnet in the direction of the axis of rotation. Then, the magnetic flux generated from the permanent magnet is allowed to enter the inside of the superconductor to be restrained, and as a result, the so-called pinning force supports the rotating body in a non-contact state in the radial direction and the axial direction with respect to the fixed portion. It is like this.

[0003]

In the above flywheel device, it is necessary to dispose the generator motor around the rotary shaft in addition to the two sets of radial magnetic bearings and superconducting bearings. Is longer, the natural frequency of the rotating shaft is reduced, and it is difficult to rotate the rotating shaft at high speed.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a flywheel device capable of rotating the rotating shaft at high speed by increasing the natural frequency of the rotating shaft.

[0005]

A flywheel device according to the present invention comprises a rotary shaft that rotates about a vertical axis, a flywheel fixed to the rotary shaft, and a non-contact support for the rotary shaft in the radial direction. Two sets of upper and lower four-axis control radial magnetic bearings, and a non-contact axial bearing that non-contactly supports the rotary shaft in the axial direction,
At least one set of the radial magnetic bearings has an electric drive function of rotationally driving the rotary shaft.

For example, the non-contact axial bearing is
A superconducting bearing comprising a rotating permanent magnet provided on the rotating shaft and a superconductor provided on a fixed portion, wherein the rotating permanent magnet has a magnetic flux distribution symmetrical with respect to a rotating shaft center of the rotating shaft. And the magnetic flux distribution around the rotation axis is arranged in the rotation axis or in a portion that rotates integrally with the rotation axis so that the magnetic flux distribution does not change due to rotation, and the superconductor intrudes a predetermined amount of the magnetic flux of the rotating permanent magnet. It is arranged so as to face the rotating permanent magnet at a separated position and at a position where the distribution of the intruding magnetic flux does not change due to the rotation of the rotating body.

[0007]

Since at least one set of radial magnetic bearings has a transmission drive function for rotationally driving the rotary shaft, it is not necessary to separately provide an electric motor, and the rotary shaft can be shortened accordingly. By shortening the rotating shaft, the natural frequency of the rotating shaft is increased, and high speed rotation is possible.

When the non-contact axial bearing is a superconducting bearing, when the rotating shaft is rotating normally, the radial magnetic bearing does not support the rotating shaft in the radial direction. Can be supported in any direction.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a flywheel device in a power storage device will be described below with reference to the drawings.

FIG. 1 schematically shows the overall structure of the flywheel device, and FIG. 2 shows a part of the flywheel device in detail.

The flywheel device has a vertical rotation axis (1).
, A flywheel (2) fixed to the rotating shaft (1), two sets of upper and lower 4-axis control radial magnetic bearings (3) (4) that support the rotating shaft (1) in the radial direction in a non-contact manner, the rotating shaft ( Superconducting bearing (non-contact axial bearing) (5) that non-contactly supports 1) in axial direction (vertical direction) and radial direction (5), and initial positioning device (6) for positioning the rotating shaft (1) at startup. And a vacuum chamber surrounded by a housing (fixed part) (7) consisting of multiple members.
It is located in (8).

The flywheel (2) is made of a non-magnetic material such as an aluminum alloy and has a disk shape.
An annular reinforcing member (9) made of CFRP (composite fiber reinforced plastic) is integrally fixed to the outer periphery thereof. The flywheel (2) is concentrically fixed to the upper shaft of the rotating shaft (1), and the rotating shaft (1) moves slightly up and down (moves in the axial direction) in the center of the housing (7). It is arranged so that it can be moved in the radial direction.

Details of the superconducting bearing (5) are shown in FIG.

The superconducting bearing (5) includes a plurality of annular rotary permanent magnets (10) concentrically provided on the rotary shaft (1) side and a housing (7) side so as to face the rotary permanent magnets. It has a circular superconductor (11).

A disk-shaped rotating member (12) made of a non-magnetic material is fixed to the rotating shaft (1) so as to be in close contact with the lower surface of the flywheel (2). The rotating member (12) is made of a non-magnetic material such as an aluminum alloy or non-magnetic stainless steel in a disc shape, and an annular CFRP reinforcing member (13) is integrally fixed to the outer periphery thereof. In addition, the rotating member (12) itself is C
It may be made of FRP. A plurality of annular grooves (15) partitioned by a circular partition wall (14) are concentrically formed on the lower end surface of the rotating member (12), and a rotating permanent magnet (10) is provided in each groove (15). 1
They are fitted and fixed one by one. The outer peripheral portion of the permanent magnet (10) is a wall on the outer peripheral side of the groove (15) or a partition wall (14).
It is press-fitted into the inner peripheral part. The inner peripheral portion of the permanent magnet (10) is loosely fitted to the outer peripheral portion of the partition wall (14) or the inner wall of the groove (15), and there is little or no gap between them. It is open. The permanent magnet (10) has magnetic poles at both ends in the axial direction, and each permanent magnet (1
The magnetic poles at the same end in (0) are arranged so as to have the same polarity. That is, in this embodiment, each permanent magnet (1
The lower end side of 0) is the N pole and the upper end side is the S pole. Since the permanent magnet (10) has an annular shape and is arranged concentrically with respect to the rotation axis of the rotation shaft (1), the magnetic flux distribution of the permanent magnet (10) becomes symmetric with respect to the rotation axis. Moreover, the magnetic flux distribution around the rotation axis does not change due to rotation.

The housing is such that the annular cooling case (16) faces the lower surface of the rotating member (12) at a predetermined interval.
It is fixed to (7). The cooling case (16) is made of a non-magnetic material such as copper alloy or non-magnetic stainless steel, and the annular superconductor (11) is fixedly arranged in the space therein. Although illustration is omitted, the space in the cooling case (16) is connected to the cooling device via the cooling fluid supply pipe and the discharge pipe, and by this cooling device, a cooling fluid such as liquid nitrogen is supplied to the cooling pipe. The superconductor (11) is circulated through the space in the cooling case (16) and the discharge pipe, whereby the superconductor (11) is cooled. The superconductor (11) is a type 2 superconductor, and a normal conductor (Y ₂ Ba ₁ Cu ₁ ) is contained inside a bulk of yttrium-based high temperature superconductor, for example, YBa ₂ Cu ₃ O _7-x. In a temperature environment where the second-class superconducting state appears,
It has the property of internally restraining the magnetic flux generated from the permanent magnet (10). And the superconductor (11) is a permanent magnet
The permanent magnet (10) is arranged so as to face the permanent magnet (10) at a separated position where the magnetic flux of (10) penetrates a predetermined amount and at a position where the distribution of the magnetic flux of penetration does not change due to the rotation of the rotating shaft (1).

Although not shown in detail in the radial magnetic bearings (3) and (4), the rotary shaft (1) is sucked from both sides in two radial directions (X-axis and Y-axis directions) orthogonal to each other. It has an electromagnet for controlling the position of the rotating shaft (1) in the same direction, and a displacement sensor for detecting the displacement of the rotating shaft (1) in the X-axis and Y-axis directions. It is connected to the control device. Then, the magnetic bearing control device controls the current value of the electromagnet, that is, the attraction force, based on the output of the displacement sensor, and as a result, the rotating shaft (1)
The radial position of is controlled.
Since the radial magnetic bearing device and its control device are publicly known, detailed description thereof will be omitted. At least one set of radial magnetic bearings (3) (4) is
In addition to the position control function of (1), it has an electric drive function of rotationally driving the rotating shaft (1). In this embodiment, the lower radial magnetic bearing (4) has an electric drive function. Four-axis control radial magnetic bearings with electric drive function are used for levitating rotary motors or bearingless
Since it is known as a motor or the like, detailed description is omitted.

Although not shown in detail, the initial positioning device (6) is provided with an elevating body for elevating and lowering a portion of the housing (7) below the rotary shaft (1), and the rotary shaft (1) is set at a predetermined position. It is designed to be lifted up to.

Touchdown bearings (17) and (18), which are rolling bearings, are provided on the upper and lower portions of the housing (7) to support the upper and lower ends of the rotary shaft (1) in an emergency.

When starting rotation of the rotary shaft (1), first, the vacuum chamber (8) is evacuated, and the stopped rotary shaft (1) is moved to a predetermined position by the initial positioning device (6). Lift up to the initial position of the rotary shaft (1) in the axial direction. Also, with the electric drive function of the lower magnetic bearing (4) stopped, only the position control function of the upper and lower magnetic bearings (3) (4) is activated to perform the initial radial positioning of the rotary shaft (1). I do. And the superconducting bearing (5) by the cooling device
The cooling fluid is circulated in the cooling case (16) of the
Cool 1) and keep it in the type 2 superconducting state. Then, most of the magnetic flux generated from the permanent magnet (10) enters the inside of the superconductor (11) and is restricted (pinning phenomenon). Here, since the normal conductor particles are uniformly mixed in the superconductor (11), the distribution of the magnetic flux penetrating into the superconductor (11) becomes constant, and therefore the superconductor (11) ), The rotating shaft (1) is constrained together with the permanent magnet (10).
Therefore, the rotary shaft (1) is in a very stable state,
It will be supported in the axial and radial directions. At this time, the magnetic flux penetrating the superconductor (11) does not become a resistance that hinders rotation as long as the magnetic flux distribution is uniform and unchanged with respect to the rotation axis. If the rotating shaft (1) is thus supported by the superconducting bearing (5) and the magnetic bearings (3) (4), the supporting of the rotating shaft (1) by the initial positioning device (6) is eliminated. When there is no support by the initial positioning device (6), the rotating shaft (1) slightly descends due to its own weight, but it stops at a position where the downward force due to its own weight and the axial supporting force of the superconducting bearing (5) balance each other. To do. This allows the rotating shaft (1)
Are non-contact supported by the superconducting bearing (5) and the magnetic bearings (3), (4). When the rotating shaft (1) is supported in a non-contact manner, the electric drive function of the lower radial magnetic bearing (4) is activated to rotate the rotating shaft (1) and accelerate it to the operating rotating range. Even if resonance occurs until the rotating shaft (1) reaches the operating rotation range, the magnetic bearings (3) and (4) prevent the occurrence of runout. When the rotating shaft (1) reaches the operating rotation range, it is held at a predetermined rotation speed, the position control function of the magnetic bearings (3) (4) is stopped, and the magnetic bearings (3) (4) There is no support in the radial direction. Even if the radial bearings of the magnetic bearings (3) (4) are lost, the rotating shaft (1) still has the superconducting bearing (5).
It is supported in the axial direction and the radial direction by the pinning force of the magnetic flux penetrating the superconductor (11), and continues stable rotation. Then, while the rotating shaft (1) is rotating in the operation rotating region, electric energy is converted into rotational kinetic energy and stored in the flywheel (2).

If a power failure occurs while the rotating shaft (1) is rotating in the operating rotating region, the electric drive function of the lower magnetic bearing (4) is stopped, but the flywheel (2) causes the rotating shaft ( 1) is decelerated slightly, but is continuously rotated. As a result, the lower magnetic bearing (4) operates as a generator, and the rotational kinetic energy stored in the flywheel (2) is taken out as electric energy and stored in a storage battery (not shown). The electric power stored in the storage battery is sent to an external power consumer goods and a superconducting bearing (5) cooling device (not shown), and the power consumer goods and the superconducting bearing (5) continue to operate. Part of the electric power stored in the storage battery is sent to the magnetic bearing control device, which activates the position control function of the magnetic bearing devices (3) and (4). Then, until the rotational kinetic energy stored in the flywheel (2) decreases and the rotating shaft (1) stops, the rotating shaft (1) keeps the superconducting bearing (5) and the magnetic bearing (3) ( The rotation shaft (1) is supported by 4) in a non-contact state and occurs at the resonance point.
Reduced by magnetic bearings (3) (4).

When the electric drive function of the lower magnetic bearing (4) is stopped even during a power failure, the rotary kinetic energy stored in the flywheel (2) can be taken out as electric energy, as in the case of a power failure. it can.

In the above flywheel device, the CFRP constituting the reinforcing member (9) fixed to the outer periphery of the flywheel (2) is lightweight and has a large Young's modulus. Since it is lightweight, centrifugal force acting on the reinforcing member (9) at high speed is small, and since Young's modulus is large, deformation (centrifugal expansion) of the reinforcing member (9) due to centrifugal force is small. Therefore, the centrifugal expansion of the flywheel (2) fitted inside the reinforcing member (9) is suppressed to a small level, and the centrifugal destruction of the flywheel (2) is prevented. Superconducting bearing
The same applies to the rotating member (12) of (5). Then, one permanent magnet (10) is incorporated in the annular groove (15) of the rotating member (12), and each permanent magnet (10) has a wall or partition wall (partition wall) of the rotating member (12) with small centrifugal expansion. Since they are pressed into the inner peripheral part of 14), the tightening margin can be reduced, and the dimensional control and assembly of the permanent magnet (10) are easy.
Moreover, the centrifugal expansion of the permanent magnet (10) is suppressed to a small level, and the centrifugal destruction of the permanent magnet (10) is prevented.

As the non-contact axial bearing for supporting the rotary shaft (1) in the axial direction in a non-contact manner, the superconducting bearing (5) is used in the above embodiment, but the rotary shaft (1) side and the housing (7) are used. Other types of bearings may be used, such as a permanent magnet bearing that non-contactly supports the rotating shaft (1) in the axial direction by the magnetic repulsive force of the permanent magnet provided on the side.

[0025]

As described above, according to the flywheel device of the present invention, the rotating shaft can be shortened and the natural frequency of the rotating shaft can be increased, thus enabling high speed rotation.

Since the non-contact axial bearing is a superconducting bearing, when the rotating shaft normally rotates, the radial magnetic bearing does not support the rotating shaft in the radial direction. It can be supported in the axial direction.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a flywheel device showing an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a portion of the superconducting bearing of FIG.

[Explanation of symbols]

(1) Rotating shaft (2) Flywheel (3) (4) 4-axis control radial magnetic bearing (5) Superconducting bearing (non-contact axial bearing) (7) Housing (fixed part) (10) Rotating permanent magnet ( 11) Superconductor

Claims (2)

[Claims] 1. A rotary shaft that rotates about a vertical shaft, a flywheel fixedly mounted on the rotary shaft, and two sets of upper and lower four-axis control radial magnetic bearings that support the rotary shaft in a non-contact manner in the radial direction. And a non-contact axial bearing that non-contactly supports the rotary shaft in the axial direction, and at least one set of the radial magnetic bearings has an electric drive function of rotationally driving the rotary shaft. Wheel device. 2. The non-contact axial bearing is a superconducting bearing provided with a rotating permanent magnet provided on the rotating shaft and a superconductor provided on a fixed portion, and the rotating permanent magnet has a magnetic flux distribution. The superconductor is arranged symmetrically with respect to the rotation axis of the rotation axis, and is arranged in the rotation axis or a portion that rotates integrally with the rotation axis so that the magnetic flux distribution around the rotation axis does not change due to rotation. Is arranged so as to face the rotating permanent magnet at a separated position where the magnetic flux of the rotating permanent magnet enters a predetermined amount and at a position where the distribution of the entering magnetic flux does not change due to the rotation of the rotating body. The flywheel device according to claim 1.