JP2933287B2 - Magnetic bearing device for rotating machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called two-axis control type magnetic bearing device for a rotary machine, and more particularly to a disk-shaped rotor having a shaft integrally fixed at the center and a motor for moving the rotor. It has a passive stable magnetic bearing having a rotating part and a passive stable magnetic bearing for supporting the axial direction of the rotating part and a radial control type magnetic bearing for controlling the radial position of the rotating part. The present invention relates to a magnetic bearing device.

[0002]

2. Description of the Related Art In such a two-axis control type magnetic bearing device for a rotating machine, a passive stable type magnetic bearing composed of a permanent magnet is used to maintain the axial position of the rotating portion constant while maintaining a constant position.
Radial position, in other words, XY in a predetermined plane
The position in the direction is controlled by an active magnetic bearing composed of electromagnets.

[0003] That is, by controlling the current for supplying the unstable force in the radial direction to the electromagnet while holding the rotating portion at a predetermined axial position by the magnetic action of the permanent magnet of the passive stable magnetic bearing. And the rotating body is supported in a non-contact floating state.

[0004]

However, in the prior art, it was considered that the whirling phenomenon peculiar to a long rotating body could not be suppressed, so that it was not used as a supporting device for a long, high-speed rotating body. Was.

[0005] The present invention has been proposed in view of the above-mentioned problems of the prior art, and is a so-called two-shaft that is extremely easy to disassemble and assemble and that can suppress the whirling phenomenon of the rotating body. It is intended to provide a magnetic bearing device for a controlled rotary machine.

[0006]

According to the present invention, there is provided a rotating portion comprising a disk-shaped rotor having a shaft integrally fixed at the center and a motor for moving the rotor, and the rotating portion has an axial direction. In a magnetic bearing device for a rotating machine provided with a passive stable magnetic bearing for supporting the magnetic bearing and a radial control magnetic bearing for controlling the position of the rotating part in the radial direction, the disk-shaped rotor is provided at the peripheral edge thereof at a lower position. The hanging flange is integrally fixed, the fixing portion has a cylindrical portion concentric with the shaft portion and located radially inward of the flange, and the passive stable magnetic bearing includes the cylindrical portion and the flange. The radially controlled magnetic bearing is provided on the cylindrical portion and the shaft portion, and the center of gravity of the rotating portion is a passive stable shaft comprising the passive stable magnetic bearing and the radially controlled magnetic bearing. Of magnetic bearing device with With respect to the axial direction magnetic center are biases in the rotation axis direction.

[0007]

[0008]

[Operation] Therefore, the rotating part is fixed to the cylindrical part of the fixed part.
The shaft is inside the flange and the flange is outside it, and the disk-shaped rotating part is covered by the cylinder, so if the rotating part is pulled up, it can be removed from the fixed part very easily. I can do it. In that state, a necessary maintenance operation may be performed.

When the maintenance work is completed, the assembling work is easily performed by putting the rotating part on the fixed part again.

In the present invention, since the center of gravity of the rotating part is deviated in the direction of the rotation axis with respect to the magnetic center in the radial axis direction of the magnetic bearing device having the passive stable shaft, the inclination of the shaft part of the rotating body besides the radial direction Can generate a force. That is, when the rotating body precesses, the shaft portion of the rotating body becomes unstable in the direction of falling down, but the magnetic bearing device having the passive stable shaft has the radial control type magnetic bearing, The radial control force can be used as a torque for stabilizing the tilting motion by the product of the deviated distance between the center of gravity and the radial axis on which the control force acts. That is, a force is generated that returns the inclination of the shaft of the rotating body to the neutral position, and this is suppressed and attenuated. With such a structure that is deviated axially from the center of gravity, the force generated by the bearing can act as a control force for the motion mode around the center of gravity.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a turbo-molecular pump will be described below with reference to the drawings. In order to better understand the present invention, first, referring to FIG. explain.

Referring to FIG. 1, a rotor or impeller 22 is shown.
Has a shape of a disk having a flange whose peripheral portion hangs down. The shaft portion 23 of the impeller 22 is housed concentrically with the cylindrical portion 26 of the fixed portion 25, and the cylindrical portion 26 has a cylindrical shape. The outer peripheral surface 26s of the cylindrical portion 26 and the impeller 22
The passive stable magnetic bearing 20 is provided between the inner peripheral surface 22s and the inner peripheral surface 22s.

Although not shown in FIG. 1, a motor is provided between the cylindrical portion 26 and the shaft portion 23. Further, between the cylindrical portion 26 and the shaft portion 23, the radial control electromagnet 2 is provided.
1 is provided.

In FIG. 1, a passive stable magnetic bearing 20 has a ring-shaped permanent magnet 30 with upper and lower surfaces formed of a ring-shaped magnetic body 3.
The unit sandwiched between 2 and 32 is connected to the outer peripheral surface 26 of the cylindrical portion 26.
s and the inner peripheral surface 22s of the impeller 22. However, all other types of passive bearing magnetic bearings are applicable. Similarly, the radial control electromagnet 21 is not limited to the illustrated one.

In FIG. 1, a passive stable magnetic bearing 20 holds an impeller 22 at a predetermined axial position. The displacement of the shaft portion 23 in the radial direction is suppressed by controlling the current supplied to the coil 34 of the radial control electromagnet 21.

As described above, the impeller 22 has a disk-like shape in which the edge thereof forms a flange-like portion extending downward, and the fixed portion 25 has a cylindrical tubular portion 26. Have. Therefore, when the impeller 22 is pulled up (in the direction of the reference symbol U), the impeller 22 and the shaft 23 are easily detached from the cylindrical portion 26. When performing maintenance, the impeller 2
Since it is sufficient to remove the shaft 2 and the shaft portion 23, the work becomes very easy and labor can be reduced.

After the maintenance is completed, the impeller 22 and the shaft 23 are inserted into the cylindrical portion 26 of the fixing portion 25 again, so that the assembly is easily performed. However, the one shown in FIG. 1 has a problem that a so-called razor motion easily occurs due to the inclination of the rotating shaft.

FIG. 2 shows an embodiment of the present invention which provides a magnetic bearing device for a rotating machine which does not have the above-mentioned problems of the present invention. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 2, the rotor or impeller 22
The shaft part 23 is concentrically housed in the cylindrical part 26 of the fixed part 25, and the upper and lower parts of the cylindrical part 26 are respectively provided with the emergency bearing 2.
8a, 28b are always provided on the opposite side in a non-contact manner,
A motor 24 is provided between the cylinder 26 and the shaft 23.

A passive stable magnetic bearing 20 is provided above the motor 24 between the impeller 22 and the cylinder 26, and above the motor 24 between the cylinder 26 and the shaft 23. , A radial control electromagnet 21 is provided. The axial magnetic center of the passive stable magnetic bearing 20, that is, the center of the axial lamination thickness, and the axial magnetic center of the radial control electromagnet 21, that is, the center of the axial thickness of the magnetic pole, are:
At the center C, the center of gravity G of the impeller 22 is offset from the center C by an amount E in the axial direction.

Further, below the upper emergency bearing 28a,
The cylindrical portion 26 above the lower emergency bearing 28b is provided with radial and tilt position detectors 27a and 27b each formed of a non-contact sensor.
It is connected to the. The control device 40 is connected to a plurality of coils 21a which are arranged on the radial control electromagnet 21 at equal circumferential intervals.

Therefore, when the precession movement occurs in the impeller 22 as described above, the center of gravity of the impeller 22 is displaced axially upward from the center C by the amount of displacement E, so that the shaft portion 23 is tilted further in the direction in which it falls. In an unstable state.

At this time, the passive stable type magnetic bearing 20 is of a suction type and is arranged at a position away from the center of the shaft portion 23 as shown in the drawing, so that the inclination of the shaft portion 23 is set to the neutral position. Generates the force to pull back.

Further, the position detectors 27a and 27b are
When the controller detects the inclination of 3, the controller 40 controls the exciting current of the coil 21a on the side facing the inclination based on the signals from the position detectors 27a and 27b, increases the magnetic attraction force, and controls the shaft portion 23. Return to neutral position.

In FIG. 2, the center of gravity G of the impeller 22 is shown.
Is deviated axially above the center C, but the center of gravity G
Can be arranged so as to be displaced axially below the center C.

[0026]

As described above, the two-axis control type magnetic bearing device for a rotary machine according to the present invention can be extremely easily disassembled and assembled. Therefore, labor required for maintenance and the like can be significantly reduced.

Further, according to the present invention, the force of returning the inclination of the rotating shaft to the neutral position is generated by displacing the center of gravity of the rotating portion in the axial direction with respect to the axial magnetic center of the passive magnetic bearing. The inclination can be suppressed and attenuated.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an entire configuration of an apparatus in a process leading to the present invention.

FIG. 2 is a side sectional view showing the entire configuration of the embodiment of the present invention.

Continuing from the front page (72) Inventor Hiroyuki Shinozaki 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Within Ebara Research Institute, Ltd. (72) Inventor Yuji 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Co., Ltd. Inside EBARA Research Institute (72) Inventor Yoichi Kanemitsu 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Inside EBARA Research Institute Co., Ltd. (56) References JP-A-62-177314 (JP, A) 185526 (JP, A) Japanese Utility Model 63-171724 (JP, U) Japanese Utility Model 60-143925 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16C 32/04

Claims (1)

(57) [Claims] 1. A passive stable magnetic bearing having a rotating part comprising a disk-shaped rotor having a shaft part integrally fixed at the center thereof and a motor for moving the rotor, and supporting the rotating part in the axial direction. In a magnetic bearing device for a rotating machine provided with a radial control type magnetic bearing for controlling a radial position of a rotating part, the disk-shaped rotor is integrally fixed with a flange hanging downward at a peripheral edge thereof. The fixing portion has a cylindrical portion concentric with the shaft portion and located radially inward of the flange, and the passive stable magnetic bearing is provided on the cylindrical portion and the flange, and includes the radial control type. A magnetic bearing is provided on the cylindrical portion and the shaft portion, and a center of gravity of the rotating portion is provided in a radial axial magnetic field of a magnetic bearing device having a passive stable shaft including the passive stable magnetic bearing and the radial control type magnetic bearing. Rotation axis direction to center A magnetic bearing device for a rotating machine, characterized in that the magnetic bearing device is biased toward a rotating machine.