JPH0979259A - Magnetic levitation rotary device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive a radial/axial magnetic bearing over a relatively long time without using an auxiliary power source means of battery or the like, when supply of power from an external power supply is stopped. SOLUTION: A magnetic bearing device comprises two sets of radial magnetic bearings 3, 4 arranged in the periphery of a rotary unit 1, one set of axial magnetic bearing 2, AC electric motor 8 and a batteryless type inverter device for driving these magnetic bearings. The inverter device, when supply of power from an external power supply is stopped, drives the radial magnetic bearings 3, 4 and the axial magnetic bearing 2 by regenerative power from the electric motor 8. Each radial magnetic bearing 3, 4 is a three-electromagnet type radial magnetic bearing comprising three electromagnets 13a, 13b, 13c, 14a, 14b, 14c. The axial magnetic bearing 2 is a compound type axial magnetic bearing comprising a permanent magnet 12a and an electromagnet 12b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation rotating device, such as a turbo molecular pump, for rotating a rotating body, which is supported in a non-contact manner by magnetic bearings, by an AC electric motor.

[0002]

2. Description of the Related Art For example, as a magnetic levitation rotating device used in a turbo molecular pump, two sets of magnetic levitation rotating devices are provided around a rotating body and support the rotating body in a radial direction in a non-contact manner. Radial magnetic bearings,
A set of axial magnetic bearings arranged around the rotating body to support the rotating body in the axial direction in a non-contact manner; an AC electric motor arranged around the rotating body to rotate the rotating body;
It is known to have a radial magnetic bearing and an inverter device for driving the axial magnetic bearing. Around the rotating body, a protective bearing (touch-down bearing) that mechanically supports the rotating body when the support by the magnetic bearing is lost is provided. Each radial magnetic bearing includes a total of four electromagnets arranged so as to sandwich the rotating body from both sides in two radial directions orthogonal to each other. The axial magnetic bearing includes two electromagnets arranged so as to sandwich the flange portion formed on the rotating body from both sides in the axial direction. The inverter device normally drives the electric motor, radial magnetic bearings and axial magnetic bearings with the electric power supplied from the external power supply, and performs regenerative braking of the electric motor when the power supply from the external power supply is stopped due to a power failure or the like. At the same time, the radial magnetic bearing and the axial magnetic bearing are driven by the regenerative electric power from the electric motor. As a result, even if the power supply from the external power supply is stopped, the radial magnetic bearing and axial magnetic bearing support the rotating body in a non-contact state for a while, and when the rotating body decelerates to a certain extent, it is supported by the magnetic bearing. Then, the rotating body is supported by the protective bearing, further decelerates, and then stops.

In the above conventional magnetic levitation rotary device, it is necessary to drive a total of 10 electromagnets of the radial magnetic bearing and the axial magnetic bearing, so that the required power is large.
It is difficult to drive the radial magnetic bearing and axial magnetic bearing for a long time when the power supply from the external power supply is stopped, and the rotating body is supported by the protective bearing at a relatively high rotational speed. This shortens the life of the protective bearing. In order to avoid this, it is necessary to provide auxiliary power supply means such as a battery (storage battery) and drive the magnetic bearing with the auxiliary power supply means until the rotational speed of the rotating body is sufficiently reduced. There is a problem that maintenance is troublesome.

The object of the present invention is to solve the above problems,
(EN) A magnetic levitation rotating device capable of driving a radial magnetic bearing and an axial magnetic bearing for a relatively long time without using an auxiliary power supply means such as a battery when the supply of electric power from an external power supply is stopped. .

[0005]

A magnetic levitation rotating device according to the present invention includes two sets of radial magnetic bearings which are respectively arranged around a rotating body and support the rotating body in a non-contact manner in a radial direction, and the rotating body. A set of axial magnetic bearings arranged around the body to support the rotating body in the axial direction in a non-contact manner, an AC electric motor arranged around the rotating body to rotate the rotating body, and usually from an external power source. The AC electric motor, the radial magnetic bearing and the axial magnetic bearing are driven by the supplied electric power, and the radial magnetic bearing and the axial magnetic bearing are regenerated by the AC electric motor when the supply of the electric power from the external power source is stopped. In a magnetic levitation rotating device including a batteryless inverter device that drives a bearing, each of the radial magnetic bearings has a circumferential surface of a rotating body. A three electromagnet type radial magnetic bearing in which three electromagnets are disposed, wherein the axial magnetic bearing is disposed so as to face one end face in the axial direction of the flange portion formed on the rotating body, and A composite axial magnetic bearing comprising an electromagnet arranged so as to face the other axial end surface of the flange portion.

Since the total number of the electromagnets of the radial magnetic bearing and the axial magnetic bearing is 7, the power consumption of the electromagnet is smaller than that of the conventional one, and therefore, when the power supply from the external power supply is stopped, The batteryless inverter device can drive the radial magnetic bearing and the axial magnetic bearing for a relatively long time without using a battery. Therefore, when the rotating body is received by the protective bearing, the rotational speed of the rotating body is sufficiently small, and the life of the protective bearing is extended. Since the magnetic bearing can be operated by the electric power supplied from the inverter device until the rotational speed of the rotating body becomes sufficiently small, it is not necessary to provide an auxiliary electric power means such as a battery, and troublesome maintenance therefor is required. It is unnecessary.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a magnetic levitation rotating device using a shaft-shaped rotating body (1), and FIG. 2 shows an example of its electrical configuration. In the following description, the control axis in the axial direction of the rotating body (1) is the Z axis, and one control axis in the radial direction orthogonal to the Z axis is the X axis, and the other control direction is the Z axis and the other radial direction orthogonal to the X axis. The control axis of is the Y axis. The Z-axis direction is the front-rear direction, the X-axis direction is the up-down direction, and the Y-axis direction is the left-right direction.

The magnetic levitation rotating device is a set of axial magnetic bearings for supporting the rotating body (1) in the axial direction in a non-contact manner.
(2) Two sets of radial magnetic bearings (3) (4) that support the rotating body (1) in the radial direction in a non-contact manner, and one axial position sensor (which detects the displacement of the rotating body (1) in the axial direction ( Five) ,
Two sets of radial position sensor units (6) (7) for detecting the radial displacement of the rotating body (1), a high frequency AC electric motor (8) for rotating the rotating body (1) at high speed, an electric motor (8) and a magnetic bearing. (2) (3) (4) drive device (9) and rotating body
By limiting the movable range in the axial direction and the radial direction of (1), two sets of mechanically supporting the rotating body (1) when it cannot be supported by the magnetic bearings (2), (3) and (4). Protective bearing
It has (10) and (11).

The axial magnetic bearing (2) is arranged so as to face one end face (front end face) in the Z-axis direction of the flange portion (1a) integrally formed on the front portion of the rotating body (1). Permanent magnet (1
The composite axial magnetic bearing comprises 2a) and an axial electromagnet (12b) arranged so as to face the other end surface (rear end surface). Permanent magnet (12a) and axial electromagnet (1
2b) sucks the flange portions (1a) in opposite axial directions to support the rotating body (1) in a non-contact manner at a predetermined position in the axial direction.

The axial position sensor (5) is a rotating body (1).
Is arranged so as to oppose the front end face of the rotating body (1) and outputs a distance signal proportional to the distance (gap) from the front end face of the rotating body (1).

The two sets of radial magnetic bearings (3) and (4) are arranged on the rear side of the axial magnetic bearing (1) at predetermined intervals in the front-rear direction, and the electric motor (8) is arranged between them. Is provided. The first radial magnetic bearing (3) on the front side is
A three-electromagnetic radial magnetic bearing consisting of three radial electromagnets (13a) (13b) (13c) arranged at equal intervals around the rotating body (1). These radial electromagnets have the sign (1
When they are collectively referred to in 3) and need to be distinguished, they will be referred to as a first radial electromagnet (13a), a second radial electromagnet (13b) and a third radial electromagnet (13c), respectively. First
The radial electromagnets (13a) are disposed below the rotating body (1) so as to face each other, and the second and third radial electromagnets (13b) (13c) are disposed so as to face diagonally above the rotating body (1). ing. XY
On a cross section parallel to the plane, the first radial electromagnet (1
3a) is arranged on the X-axis, and the second radial electromagnet (13b) and the third radial electromagnet (13c) are arranged symmetrically with respect to the X-axis so as to be separated from the X-axis by the same angle in the opposite direction. There is. The radial electromagnet (13) generates a magnetic attraction force by an exciting current supplied from a magnetic bearing control device (18) described later, and supports the rotating body (1) in a predetermined radial direction in a non-contact manner. Similarly, the second radial magnetic bearing (4) on the rear side also has the rotating body (1).
First radial electromagnets arranged at equal intervals around the circumference
(14a) is a three-electromagnet type radial magnetic bearing including a second radial electromagnet (14b) and a third radial electromagnet (14c). These radial electromagnets (14a) (14b) (14c) also have a code
Collectively referred to in (14).

Front side first radial position sensor unit
(6) is arranged in the vicinity of the first radial magnetic bearing (3), and a pair of radial position sensors (15a) are arranged so as to sandwich the rotating body (1) from both sides in the X-axis direction. ) (15b), and a pair of radial position sensors (15c) (15d) arranged so as to sandwich the rotating body (1) from both sides in the Y-axis direction. These radial position sensors are collectively referred to by the reference numeral (15). When it is necessary to distinguish them, one sensor (15a) in the X-axis direction is referred to as the first X
The axis sensor, the other sensor (15b) will be called the second X-axis sensor, the one sensor (15c) in the Y-axis direction will be called the first Y-axis sensor, and the other sensor (15d) will be called the second Y-axis sensor. Similarly, the second radial position sensor unit (7) on the rear side also
It is located near the second radial magnetic bearing (4),
First X-axis sensor (16a), second X-axis sensor (16b), first Y-axis
An axis sensor (16c) and a second Y-axis sensor (16d) are provided. These radial position sensors (16a) (16b) (16c) (16d)
Are also collectively referred to by reference numeral (16). Each radial position sensor (15) (1
6) outputs a distance signal proportional to the distance from the outer peripheral surface of the rotating body (1).

The first protective bearing (10) on the front side is, for example,
It is a combination of two angular contact ball bearings and is designed to be able to receive both axial and radial loads. The outer ring of the bearing (10) is fixed to the casing of the magnetic bearing device (not shown), and the inner ring is formed in the circumferential groove (17) formed on the outer peripheral surface of the rotating body (1) with an appropriate gap in the axial and radial directions. Is opened.
The second protective bearing (11) on the rear side is, for example, a deep groove ball bearing, and can receive a radial load. The outer ring of the bearing (11) is fixed to the casing, and the inner ring is arranged so as to face the outer peripheral surface of the rotating body (1) with an appropriate gap. The axial movable range of the rotating body (1) is restricted by the size of the axial gap between the inner ring of the first bearing (10) and the rotating body (1), and each bearing (10) The radial movable range of the rotating body (1) is restricted by the size of the radial gap between the inner ring of (11) and the rotating body (1).

The drive device (9) includes a magnetic bearing control device (18) for driving the magnetic bearings (2), (3) and (4) and a batteryless drive for driving the electric motor (8) and the magnetic bearing control device (18). Type inverter device (19), and the inverter device (19) is connected to an external power supply (20) such as a commercial power supply.

The magnetic bearing control device (18) obtains the axial position, that is, the displacement of the rotating body (1) from the distance signal of the axial position sensor (5). Also, the first unit
The position of the rotating body (1) in the X-axis direction in the vicinity of the first radial magnetic bearing (3) is calculated by calculating the difference between the distance signals of the pair of X-axis sensors (15a) and (15b) in (6). That is, the displacement is calculated and the difference between the distance signals of the pair of Y-axis sensors (15c) and (15d) of the unit (6) is calculated to obtain the position of the rotating body (1) in the Y-axis direction, that is, the displacement. Ask for. Similarly, a pair of X-axis sensors (16a) (16b) of the second unit (7)
From the difference in the distance signals between the pair of Y-axis sensors (16c) and the pair of Y-axis sensors (16d), the X-axis direction and the Y-axis direction of the rotating body (1) near the second radial magnetic bearing (4). The position or displacement of is calculated. Then, the magnitude of the exciting current flowing through the electromagnet (12b) of the axial magnetic bearing (2) is controlled by a well-known method based on the displacement of the rotating body (1) in the Z-axis direction obtained as described above. Set of radial magnetic bearings
(3) Flow to each electromagnet (12) (13) (14) of radial magnetic bearing (3) (4) based on displacement of rotating body (1) in the X-axis direction and Y-axis direction near (4) The magnitude of the exciting current is controlled to hold the rotating body (1) at a predetermined position. The control of the three electromagnet type radial magnetic bearings (2) and (3) in the magnetic bearing control device (18) is performed by a method described in, for example, Japanese Patent Laid-Open No. 6-249238.

The inverter device (9) is usually an external power source.
The electric power supplied from (20) drives the electric motor (8) and the magnetic bearings (2) (3) via the magnetic bearing control device (18).
By driving (4), the rotating body (1) is held in place by the magnetic bearings (2), (3) and (4) as described above,
Rotate at high speed.

When the power supply from the external power source (20) is stopped due to a power failure or the like, the inverter device (19) regeneratively brakes the electric motor (8) by a known method and
The magnetic bearings (2), (3) and (4) are driven by the regenerative power from (8) via the magnetic bearing control device (18). This allows the external power supply
Even if the power supply from (20) is stopped, for a while,
When the rotating body (1) is supported in a non-contact manner by the magnetic bearings (2) (3) (4) and the rotating body (1) is decelerated to some extent, the magnetic bearings (2) (3)
Rotor (1) is no longer supported by (4) and protective bearing (1
It is supported by 0) and (11), further decelerates, and eventually stops.
At this time, the electromagnets (12b) (13) (14) of the magnetic bearings (2) (3) (4)
Since the total number is 7, the power consumption of the electromagnets (12b), (13), (14) is smaller than that of the conventional 10, and therefore the batteryless inverter device (19)
It is possible to drive the magnetic bearings (2) (3) (4) for a relatively long time.

The structure of each part of the magnetic levitation rotating device is not limited to that of the above-mentioned embodiment, but can be changed appropriately. In the above embodiment, the control axis in the axial direction (Z axis) is arranged horizontally. However, the present invention is applicable to other types of magnetic levitation devices such as the one in which the control axis in the axial direction is arranged vertically. Can also be applied.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a magnetic levitation rotation device showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of an electrical configuration of the magnetic levitation rotation device of FIG.

[Explanation of symbols]

 (1) Rotating body (1a) Flange section (2) Axial magnetic bearing (3) (4) Radial magnetic bearing (8) AC motor (12a) Permanent magnet (12b) Axial electromagnet (13a) (13b) (13c) Radial Electromagnet (14a) (14b) (14c) Radial electromagnet (19) Battery-less inverter device (20) External power supply

Claims (1)

[Claims] 1. Two sets of radial magnetic bearings, which are respectively arranged around a rotating body and support the rotating body in a radial direction in a non-contact manner, and a pair of radial magnetic bearings arranged around the rotating body so that the rotating body is not axially moved. A set of axial magnetic bearings that are in contact with each other, an AC motor that is arranged around the rotating body and rotates the rotating body, and the AC motor, the radial magnetic bearing, and the A magnetic drive device that drives an axial magnetic bearing and includes a batteryless inverter device that drives the radial magnetic bearing and the axial magnetic bearing with regenerative power from an AC electric motor when supply of electric power from the external power supply is stopped. In the levitation rotation device, each of the radial magnetic bearings is a three-electromagnet type radial magnetic bearing in which three electromagnets are arranged around a rotating body. The axial magnetic bearing is arranged so as to face the one end face in the axial direction of the flange portion formed on the rotor and the other end face in the axial direction of the flange portion. A magnetic levitation rotation device, which is a composite axial magnetic bearing including an electromagnet.