JPH0222497Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a stator structure for an attraction-controlled thrust magnetic bearing that levitates a rotating body along the axial direction in a non-contact manner.

[Conventional technology]

As a method of supporting a rotating body rotating at high speed,
Magnetic bearings that utilize magnetic force are well known.
Among these, as suction control thrust magnetic bearings,
For example, a configuration as shown in FIG. 6 is widely used.

In this suction control thrust magnetic bearing, a thrust magnetic bearing 2 is provided at the right end of the shaft 1, and a radial magnetic shaft 3 and a motor (not shown) are provided on the left side. The thrust magnetic bearing 2 is attached to a rotor yoke 2 fixed to the shaft 1.
3, stators 21 and 22, and a displacement sensor 24. The stators 21 and 22 are stator yokes 211 and 221 and excitation coil 21, respectively.
2, 222, and each magnetic pole surface 213, 223 faces the rotor yoke 23 in parallel with a gap therebetween. in this way,
The purpose of the annular configuration is to reduce the eddy current generated in the rotor yoke 23, and this has the effect of reducing the drag torque caused by the eddy current.

On the other hand, the radial magnetic bearing 3 consists of a rotor 32 fixed to the shaft 1, a stator 31 disposed outside of the rotor 32 so as to surround the rotor 32 with a gap in between, and a displacement sensor 33 that detects displacement in the radial direction. . All of these are housed in the casing 4, and the stators 21, 22, 31 and displacement sensors 24, 33 are fixed to the casing 4, respectively. The principle of operation of the thrust magnetic bearing 2 or the radial magnetic bearing 3 is that a magnetic bearing control device (not shown) operates in response to a signal from the displacement sensor 24 or 33, and the stator 21, 22 or 3
The rotor yoke 23 or the rotor 32 is levitated in a non-contact state by supplying current to the rotor 1 to generate magnetic attraction force.

In such a configuration, the thrust magnetic bearing 2
Since the inner diameter of the stator 22 can be reduced to nearly the inner diameter of the rotor yoke 23, the magnetic pole area can be increased. As a result, the suction force can be increased. However, the inner diameter of the stator 21 needs to be larger than the outer diameter of the rotor 32 of the radial magnetic bearing 3 in terms of disassembly, assembly, and manufacturing. Therefore, it has been impossible to reduce the inner diameter of the stator 21 to the outer diameter of the shaft 1, and it has been impossible to increase the suction force that attracts the shaft to the left.

In order to solve this problem, a structure in which the stator yoke 211 is divided into a plurality of parts as shown in FIG. 7 has been proposed (see Japanese Patent Laid-Open No. 57-61813).

According to this structure, the inner diameter of the stator yoke 211 can be reduced to be close to the outer diameter of the shaft 1, but there is a drawback that eddy currents are generated in the rotating rotor yoke 23 near the divided portions, increasing drag torque. Occur.

[Problem that the invention attempts to solve]

In view of these shortcomings in the prior art, it is an object of the present invention to easily disassemble and assemble the stator of a thrust magnetic bearing, and to increase the magnetic attraction force while suppressing the generation of eddy currents as much as possible.

[Means for solving problems]

In order to achieve this objective, the present invention divides an annular stator armature with an E-shaped cross section into a plurality of parts along the diameter direction, and connects the inner groove at both ends of each divided part to the back surface of the intermediate magnetic pole. It is characterized in that a communication groove communicating with the outer groove is provided, and the excitation coil is wound so as to pass through the outer groove and the inner groove via the communication groove.

〔Example〕

Next, the features of the present invention will be specifically explained using examples.

FIG. 1 is a perspective view of a stator according to the present invention, showing an end face portion divided into two in the radial direction.
211 is a stator yoke, and 212 is an exciting coil. An example of the procedure for manufacturing the stator yoke 211 will be shown to make it easier to understand the shape of this end face portion. First, an annular stator yoke with an E-shaped cross section is divided into two in the radial direction to obtain a shape as shown in FIG. Next, as shown by the broken line, a part of the end face except for the magnetic pole part is removed to provide a communication groove 10, and a third
Get the shape of the figure. Inner groove 9 created in this way
An excitation coil is wound in a space extending from the magnetic pole to the outer groove 8 through the communication groove 10 on the back side of the magnetic pole on the end face. The result obtained in this way is shown in FIG. Then, two of these are joined to form one stator as shown in FIG.

According to this method, one of the magnetic poles formed by the excitation coil 212 appears on both the inner and outer magnetic pole surfaces 7 and 6, and the other magnetic pole appears on the intermediate magnetic pole surface 5.
appears in Since each of these magnetic poles extends to the divided end face, the reduction in magnetic flux at the end face portion can be suppressed to a negligible level. The rotor yoke facing the stator configured in this manner receives only a small change in magnetic flux as it rotates, and almost no drag torque due to eddy currents occurs. Furthermore, since the stator is configured to be separable, even if the stator inner diameter is made smaller than the radial or motor rotor outer diameter, there will be no problem in disassembly and assembly operations. Moreover, the attractive force can also be increased by increasing the magnetic pole area.

In the above embodiment, the stator yoke is divided into two parts, but it goes without saying that the same effect can be achieved even if the stator yoke is divided into three or more parts. That is, it is preferable to freely select the number of divisions in consideration of manufacturing workability.
Also, as shown in Figure 5, the cross section is C-shaped or H-shaped.
The same effect can be obtained by using a shaped stator yoke in which the magnetic poles of the radially divided end face portion extend to the end face.

[Effect of idea]

As described above, according to the present invention, the stator yoke of the thrust magnetic bearing is divided into a plurality of parts along the radial direction, so that assembly is easy. Considering that the inner diameter of the rotating rotor yoke can be reduced to near the outer diameter of the shaft without increasing the eddy current generated in the rotating rotor yoke,
It becomes possible to increase the suction force in the axial direction without increasing the drag torque.

[Brief explanation of drawings]

FIG. 1 shows the divided pieces of the stator in the first embodiment of the present invention, FIGS. 2 and 3 explain the manufacturing method of the divided pieces, and FIG. 4 shows the two divided pieces. The stator is shown assembled into an annular shape. FIG. 5 shows a stator according to a second embodiment of the present invention. Furthermore, FIG. 6 shows an example of the configuration of an excitation bearing in a conventional method, and FIG. 7 is a side view thereof. 211: Stator armature, 21: Excitation coil, 8: Outer groove, 9: Outer groove, 10: Communication groove.

Claims (1)

[Claims for Utility Model Registration] 1. An annular stator armature with an E-shaped cross section is divided into a plurality of parts along the diameter direction, and an outer groove is formed at both ends of each divided part from the inner groove through the back surface of the intermediate magnetic pole. 1. A stator for an attraction-controlled thrust magnetic bearing, characterized in that a communication groove is provided that communicates with the outer groove, and an excitation coil is wound so as to pass through the outer groove and the inner groove through the communication groove. 2. A stator for a thrust magnetic bearing according to claim 1, in which two stator armatures each having a divided excitation coil wound thereon are fixed with their end faces facing each other so as to form an annular shape before division. 3. A stator for a thrust magnetic bearing according to claim 1 or 2 of the utility model registration claim, which has three or more divisions. 4. A stator for a thrust magnetic bearing according to claim 1., 2. or 3., characterized in that the cross-sectional shape is C-shaped or H-shaped.