JP2018105457A - Radial magnetic bearing and blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a radial magnetic bearing while maintaining suction force.SOLUTION: A radial magnetic bearing 10 for supporting a rotating body 2 in a non-contact manner from an outside in a radial direction comprises a plurality of electromagnets 11 provided opposite to the rotating body 2 to generate a magnetic flux for supporting the rotating body 2. Each of the plurality of electromagnets 11 comprises: back yoke parts 14 and 15; a pair of magnetic pole teeth parts 16 and 17 that constitutes a magnetic path together with the back yoke parts 14 and 15 and the rotating body 2; and coils 18 and 19 wound around the pair of magnetic pole teeth parts 16 and 17, respectively. The pair of magnetic pole teeth parts 16 and 17 each comprises: base parts 16a and 17a extending from the back yoke parts 14 and 15 toward the rotating body 2 so that a distance between the pair of magnetic pole teeth parts 16 and 17 is decreased; and leading end parts 16b and 17b extending from the base parts 16a and 17a toward the rotating body 2 so that the distance between the pair of magnetic pole teeth parts 16 and 17 is increased or kept.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radial magnetic bearing for supporting a rotating body in a non-contact manner from the outside in the radial direction, and a blower including the radial magnetic bearing.

  When ball bearings are used as bearings to support the rotating shaft in blowers (or blowers), fretting fatigue, frictional wear, etc. occur, so the rotating shaft cannot be rotated at high speed, and at least frequently maintained. Need to do. On the other hand, when using a magnetic bearing device (so-called active magnetic bearing) that floats the rotating shaft by the electromagnet's attractive force and supports the rotating shaft in a non-contact manner, fretting fatigue and frictional wear do not occur. The shaft can be rotated at high speed.

  Here, the magnetic bearing device includes a thrust magnetic bearing that supports the rotating shaft in a non-contact manner from the axial direction (rotating shaft direction, thrust direction), and a radial magnet that supports the rotating shaft in a non-contact manner from the outside in the radial direction (radial direction). Bearing. Each of the thrust magnetic bearing and the radial magnetic bearing has an electromagnet for generating a magnetic flux for supporting the rotating shaft and a displacement sensor for detecting the displacement of the rotating shaft. Further, a general magnetic bearing device is provided with a touch-down bearing that supports the rotating shaft in place of the magnetic bearing in the event of an abnormality such as when power supply is stopped, and a rotational speed sensor for detecting the rotational speed of the rotating shaft. .

  As described above, in the magnetic bearing device including the electromagnet and the displacement sensor, the touchdown bearing, the rotation speed sensor, etc., which the thrust magnetic bearing and the radial magnetic bearing have, there are many components compared to the ball bearing. As a result, there is a problem that the axial dimension of the rotating shaft increases. Since the natural frequency of the rotating shaft decreases as the axial dimension of the rotating shaft increases, the rotating shaft cannot be rotated at high speed in order to prevent resonance of the rotating shaft.

  In order to solve these problems, for example, in the radial magnetic bearing disclosed in Patent Document 1, the circumferential direction of the rotating shaft in the cross section cut along the axial direction between the detection surface of the displacement sensor and the action surface of the attractive force of the electromagnet It is disclosed that they are arranged uniformly at the same position in the axial direction. With this technology, the axial dimension of the radial magnetic bearing can be reduced.

JP-A-2005-233385

  Here, the electromagnet of the radial magnetic bearing is wound around the back yoke portion, a pair of magnetic pole teeth portions that form a magnetic path together with the magnetic portions provided on the back yoke portion and the rotating body, and each magnetic pole teeth portion. And a coil. The pair of magnetic pole teeth portions respectively extend from the back yoke portion toward the magnetic portion of the rotating body.

  Radial magnetic bearings are required to reduce the radial dimension in addition to the axial dimension. In the case where the displacement sensors are uniformly arranged in the circumferential direction of the rotating shaft, as one method for reducing the radial dimension of the radial magnetic bearing, the adjacent magnetic teeth portions without interposing the displacement sensor are mutually connected. It can be considered to approach. Thereby, the radial dimension of the radial magnetic bearing can be reduced without increasing the number of turns of the coil. However, in this case, the magnetic teeth portions are close to each other at the position on the rotating body side, thereby increasing the magnetic flux (leakage magnetic flux) bypassing between the pair of magnetic teeth portions without passing through the magnetic portion of the rotating body, and attracting force. May decrease. In order to maintain the attractive force, it is necessary to increase the number of turns of the coil, but in this case, the radial magnetic bearing is also enlarged in the radial direction or the axial direction.

  The present invention has been made to solve the above-described problems, and an object thereof is to reduce the size of a radial magnetic bearing while maintaining an attractive force.

The present invention
A radial magnetic bearing for supporting a rotating body from the radially outer side in a non-contact manner,
A plurality of electromagnets provided to face the rotating body and generate magnetic flux for supporting the rotating body,
The plurality of electromagnets are respectively wound around a back yoke portion, a pair of magnetic teeth portions that form a magnetic path in combination with the back yoke portion and the rotating body, and a pair of magnetic teeth portions. And
Each of the pair of magnetic teeth portions extends from the back yoke portion so that the distance between the pair of magnetic teeth portions decreases, and the distance between the pair of magnetic teeth portions increases from the base toward the rotating body. Or a tip that extends to be maintained,
The present invention relates to a radial magnetic bearing.

  According to the present invention, the tip portions of the pair of magnetic teeth portions provided in the electromagnet extend from the base portion toward the rotating body so that the interval between the magnetic teeth portions is increased or maintained. It is possible to reduce the size of the radial magnetic bearing while maintaining it.

It is sectional drawing which shows the blower provided with the radial magnetic bearing which concerns on Embodiment 1 of this invention. It is sectional drawing which looked at the radial magnetic bearing which concerns on Embodiment 1 of this invention from the axial direction. It is a figure which shows the direction of the magnetic flux formed in the electromagnet of the radial magnetic bearing which concerns on Embodiment 1 of this invention. It is a figure which shows the direction of the magnetic flux formed in the electromagnet of the radial magnetic bearing which concerns on the comparative example of this invention. It is sectional drawing which looked at the radial magnetic bearing which concerns on Embodiment 2 of this invention from the axial direction. It is sectional drawing which looked at the radial magnetic bearing which concerns on other embodiment of this invention from the axial direction. It is sectional drawing which looked at the radial magnetic bearing which concerns on other embodiment of this invention from the axial direction.

  Embodiments of the present invention will be specifically described below with reference to the drawings. In the following description, terms indicating a specific direction are used as necessary, but these terms are used for facilitating the understanding of the present invention. It should not be understood as limited.

Embodiment 1. FIG.
(1. Overall structure of blower)
As shown in FIG. 1, the blower 1 includes a cylindrical rotating shaft 2. In the following description, the axial direction (thrust direction) of the rotating shaft 2 is referred to as the Z direction, and the radial direction (radial direction) of the rotating shaft 2 is referred to as the R direction.

  The blower 1 further includes a motor 3 that rotates the rotating shaft 2, blades 4 that are fixed to both ends of the rotating shaft 2 in the axial direction Z, and a magnetic bearing device that supports the rotating shaft 2 in a non-contact manner. Prepare. The rotating shaft 2 and the magnetic bearing device are accommodated in the casing 5. The motor 3 has a stator 6 fixed to the casing 5 and a rotor 7 fixed to the rotating shaft 2.

(2. Magnetic bearing device)
The magnetic bearing device includes radial magnetic bearings (hereinafter referred to as radial bearings) 10 and 10 provided at both ends of the rotary shaft 2 in the axial direction Z, and one thrust magnetic bearing (hereinafter referred to as thrust bearing) 20. And a touchdown bearing 30 and a rotation speed sensor 40.

[2-1. Radial bearing]
The radial bearing 10 supports the rotating shaft 2 from the outside in the radial direction R in a non-contact manner. In the present invention, the rotating shaft 2 is an example of a rotating body supported by the radial bearing 10. The radial bearing 10 detects a plurality of electromagnets 11 that generate magnetic flux for supporting the rotating shaft 2, a magnetic portion 12 fixed to the peripheral surface of the rotating shaft 2, and a displacement in the radial direction R of the rotating shaft 2. Displacement sensor 13.

  The electromagnet 11 is fixed to the casing 5. As shown in FIG. 2, in the first embodiment, the four electromagnets 11A, 11B, 11C, and 11D are uniformly arranged in the circumferential direction at an angle of 90 ° in the cross section cut along the axial direction Z. ing. For example, the electromagnet 11 </ b> A and the electromagnet 11 </ b> B are arranged in the circumferential direction R with the displacement sensor 13 (specifically, a detection unit 13 a described later) interposed therebetween. The electromagnet 11A and the electromagnet 11D are disposed adjacent to each other. The four electromagnets have the same shape. The electromagnet 11 includes back yoke portions 14 and 15, a pair of magnetic pole teeth portions 16 and 17, and coils 18 and 19 wound around the magnetic pole teeth portions 16 and 17, respectively. The back yoke portions 14 and 15 and the magnetic pole teeth portions 16 and 17 may be made of laminated steel plates. The back yoke portions 14 and 15 and the magnetic teeth portions 16 and 17 may be collectively referred to as the core of the electromagnet 11.

  The magnetic teeth portions 16 and 17 of the electromagnet 11 extend from the back yoke portions 14 and 15 toward the magnetic portion 12 provided on the rotating shaft 2, respectively. In the cross section cut along the axial direction Z, the magnetic teeth portions of the electromagnet 11 are non-uniformly arranged in the circumferential direction so as to avoid the displacement sensors 13 (specifically, detection portions 13a described later). The electromagnets 11 (11A to 11D) are uniformly arranged in the circumferential direction in a cross section cut along the axial direction Z. In the embodiment, the back yoke portions 14 and 15 are divided for each magnetic pole tooth portion.

  A minute gap is provided between the magnetic teeth 16 and 17 and the magnetic part 12. The magnetic pole tooth portion 16 has a base portion 16a on the back yoke portion 14 side and a tip portion 16b on the magnetic portion 12 side. Similarly, the magnetic pole teeth portion 17 has a base portion 17a on the back yoke portion 15 side and a tip portion 17b on the rotating shaft 2 side.

  As shown in the drawing, the distance L1 between the base portions 16a and 17a of the magnetic teeth portions 16 and 17 decreases from the back yoke portions 14 and 15 toward the tip portions 16b and 17b. In this manner, the base portions 16a and 17a extend from the back yoke portions 14 and 15 toward the tip portions 16b and 17b so that the interval between the magnetic pole teeth portions 16 and 17 is narrowed.

  In the first embodiment, the tip end portions 16b and 17b of the magnetic pole teeth portions 16 and 17 are moved away from each other, that is, the distance L2 between them increases from the base portions 16a and 17a toward the magnetic portion 12 of the rotating shaft 2. It is bent with respect to the base portions 16a and 17a. As described above, the tip portions 16b and 17b extend from the base portions 16a and 17a toward the magnetic portion 12 so that the gap between the magnetic pole teeth portions 16 and 17 increases.

  In the embodiment, the coils 18 and 19 are wound only around the base portions 16a and 17a of the magnetic pole teeth portions 16 and 17, and are not wound around the tip portions 16b and 17b. In order to increase the occupying area of the coils 18 and 19 and increase the attractive force of the electromagnet 11, the coils 18 and 19 are preferably close to each other in the adjacent electromagnets 11 and 11.

  The direction of the magnetic flux formed in the electromagnet 11 when the coils 18 and 19 are energized is indicated by arrows in FIG. In the embodiment, the winding direction and the current direction of the coils 18 and 19 are selected so that the magnetic pole teeth 16 and 17 of the electromagnets 11 and 11 adjacent in the circumferential direction are the same. As shown in the figure, the magnetic teeth 16 and 17 together with the back yokes 14 and 15 and the magnetic part 12 constitute a magnetic path. In this way, an attractive force is generated between the magnetic part 12 provided on the rotating shaft 2 and the magnetic pole teeth parts 16 and 17. In the first embodiment, since the electromagnets 11 (11A to 11D) are uniformly arranged in the circumferential direction in a cross section cut along the axial direction Z, the attractive force acts uniformly in the circumferential direction.

  Here, as described above, the magnetic teeth portions 16 and 17 form a magnetic path in combination with the back yoke portions 14 and 15 and the magnetic portion 12, and when the magnetic teeth portions 16 and 17 come close to each other, the magnetic portion 12 Magnetic flux (leakage magnetic flux) that bypasses between the magnetic teeth portions 16 and 17 increases without being interposed (details will be described later). Therefore, it is preferable that the minimum value of the interval L1 between the base portions 16a and 17a of the magnetic pole tooth portions 16 and 17 and the minimum value of the interval L2 between the distal end portions 16a and 17a are large enough to ignore the leakage magnetic flux.

  As described above, the tip portions 16b and 17b of the magnetic teeth portions 16 and 17 extend from the base portions 16a and 17a toward the magnetic portion 12 so that the interval between the magnetic pole teeth portions 16 and 17 increases. If the minimum value is such a size that the leakage magnetic flux can be ignored, the tip portions 16b and 17b maintain the spacing between the magnetic pole teeth portions 16 and 17 from the base portions 16a and 17a toward the magnetic portion 12 (that is, It may extend so that the interval is constant or substantially constant.

  The magnetic part 12 has a cylindrical shape and is provided coaxially with the rotating shaft 2. The magnetic part 12 may be comprised with the laminated steel plate in order to suppress an iron loss. The laminated steel sheet of the magnetic part 12 may be fixed to the rotating shaft 2 directly by shrink fitting. As described above, the magnetic unit 12 has a function of generating an attractive force between the magnetic pole teeth 16 and 17. Instead of providing the magnetic part 12 on the rotating shaft 2, at least a part of the rotating shaft 2 may be made of a magnetic material.

  The displacement sensor 13 includes a detection unit 13a and a detected unit 13b that are arranged to face each other. In the embodiment, an eddy current sensor that is not easily affected by the surface state of the detection target is used as the displacement sensor 13. The detection unit 13a is disposed in a space between two adjacent electromagnets 11 and 11. In the embodiment, in the cross section cut along the axial direction Z, the four detection units 13a are uniformly arranged in the circumferential direction with an angle of 90 °.

  As shown in FIG. 1, the detection unit 13 a of the displacement sensor 13 is disposed at a position overlapping the electromagnet 11 in the radial direction. In the embodiment, the detected part 13 b of the displacement sensor 13 is provided on the outer peripheral surface of the magnetic part 12. The detected part 13b may be provided on the rotating shaft 2. Of the four detection units 13a, the pair of displacement sensors 13 and 13 are configured by the two detection units 13a and the detected unit 13b that are opposed to each other with the rotating shaft 2 interposed therebetween. Two pairs of displacement sensors 13 and 13 are configured by the four detection units 13a and the detection target portion 13b.

  The displacement in the radial direction R of the rotating shaft 2 detected by the displacement sensor 13 is coordinate-converted into a displacement in the electromagnet 11 by a control device (not shown). Based on the coordinate-transformed displacement, the current flowing through the coils 18 and 19 of the electromagnet 11 is fed back. As a result, the magnetic attractive force acting between the electromagnet 11 and the magnetic part 12 is controlled, and the size of the gap between the electromagnet 11 and the magnetic part 12 is controlled so as to support the rotating shaft 2 in a non-contact manner. .

  By obtaining the differential of the outputs of the pair of displacement sensors 13, 13 facing each other across the rotating shaft 2, measurement errors due to drift of sensor coils, cables, and amplifiers (all not shown) resulting from environmental temperature changes are reduced. ing.

  As described above, the back yoke portions 14 and 15 of the electromagnet 11 are divided for each magnetic pole tooth portion. Therefore, the entire radial bearing 10 is assembled after the coils 18 and 19 are wound around the magnetic pole teeth 16 and 17, respectively.

[2-2. Thrust bearing]
The thrust bearing 20 supports the rotary shaft 2 in the axial direction Z. The thrust bearing 20 includes a disk-shaped thrust disk 21, a pair of annular electromagnets 22, and a displacement sensor 23. The thrust disk 21 is made of a ferromagnetic material. The thrust disk 21 is attached coaxially and perpendicularly to the rotating shaft 2. The thrust disk 21 has circular main surfaces 21a and 21b.

  The electromagnet 22 includes electromagnets 22 a and 22 b provided so as to sandwich the thrust disk 21 from the axial direction Z. An annular groove is formed in the electromagnets 22a and 22b. Coils 24a and 24b wound in an annular shape are arranged in the groove. The electromagnets 22a and 22b are provided with minute predetermined gaps between the main surfaces 21a and 21b of the thrust disk 21, and the coils 24a and 24b are opposed to the main surfaces 21a and 21b of the thrust disk 21, respectively. Are attached to the casing 5. By energizing the coils 24 a and 24 b, an attractive force is generated between the electromagnets 22 a and 22 b and the main surfaces 21 a and 21 b of the thrust disk 21.

  In the embodiment, as the displacement sensor 23, an eddy current sensor that is not easily affected by the surface state of the detection target is used. Based on the displacement in the axial direction R of the thrust disk 21 detected by the displacement sensor 23, the current flowing through the electromagnets 22a and 22b is feedback-controlled to act between the electromagnet 22 and the main surfaces 21a and 21b of the thrust disk 21. The magnetic attraction force is controlled, and the axial gap between the thrust disk 21 and the electromagnet 22 is controlled such that the thrust disk 21 is separated from the electromagnet 22 in the axial direction Z and supported in a non-contact manner.

[2-3. Touchdown bearing]
The touch-down bearing 30 is used when the radial bearing 10 and the thrust bearing 20 stop and cannot support the rotary shaft 2 when the power supply to the electromagnet 11 of the radial bearing 10 and the electromagnet 22 of the thrust bearing 20 is stopped. Instead, the rotating shaft 2 is supported. The touchdown bearing 30 regulates the movable range of the rotating shaft 2 in the axial direction Z and the radial direction R, and mechanically supports the rotating shaft 2 at the extreme position of the movable range of the rotating shaft 2.

  The touchdown bearing 30 is attached to the casing 5. In the embodiment, the touchdown bearing 30 includes a deep groove ball bearing 31 that supports the rotary shaft 2 from the outside in the radial direction R, and two angular ball bearings 32 that support the rotary shaft 2 in both the radial direction R and the axial direction Z. Including. The two angular ball bearings 32 are face-to-face aligned. It should be understood that the cross-section of the touchdown bearing 30 shown in FIG. 1 is only an outline.

[2-4. Speed sensor]
The rotation speed sensor 40 is an optical encoder that detects the rotation speed or rotation amount of the rotary shaft 2. However, the present invention is not limited to this, and the rotation speed sensor 40 may use, for example, a sensor having a Hall element as the detecting unit 41 and a permanent magnet as the detected unit 42. Alternatively, an optical sensor or the like having a light projecting unit and a light receiving unit as the detection unit and a reflection unit and a non-reflection unit as the detection unit may be used. The rotation speed sensor 40 includes a detection unit 41 that generates a pulse corresponding to the rotation speed of the rotation shaft 2 and a gear serving as a detection unit 42 attached to the rotation shaft 2. The detection unit 41 is attached to the casing 5.

(3. Effects)
As described above, the magnetic pole teeth portions 16 and 17 of the electromagnet 11 extend from the back yoke portions 14 and 15 toward the magnetic portion 12 provided on the rotating shaft 2. In the embodiment, tip portions 16 b and 17 b are provided on the magnetic portion 12 side of the magnetic teeth portions 16 and 17. Here, as a comparative example, a configuration in which the tip portions 16b and 17b are not provided on the magnetic portion 12 side of the magnetic pole teeth portions 16 and 17 is considered. In the comparative example, the direction of the magnetic flux formed in the electromagnet 11 is shown in FIG.

  In order to reduce the size of the radial bearing 10 in the radial direction R, let us consider bringing the magnetic pole teeth 16 and 17 close to each other. In the comparative example in which the tip portions 16b and 17b are not provided in the magnetic pole teeth portions 16 and 17, the end portions on the magnetic portion 12 side of the magnetic pole teeth portions 16 and 17 are close to each other. At this time, the magnetic flux 201 passing through the magnetic path constituted by the back yoke portions 14 and 15, the magnetic pole teeth portions 16 and 17, and the magnetic portion 12 is reduced, while the pair of magnetic pole teeth portions 16 and 16 are not passed through the magnetic portion 12. The magnetic flux (leakage magnetic flux) 202 that bypasses 17 increases. When the leakage magnetic flux increases, the attractive force of the electromagnet 11 decreases. Therefore, in order to maintain the attractive force, it is necessary to take measures such as increasing the number of turns of the coils 18 and 19, but the radial direction R or the axial direction Z (coil There is a problem that the radial bearing 10 increases in size.

  In the first embodiment, since the tip end portions 16b and 17b extend from the base portions 16a and 17a toward the magnetic portion 12 so that the interval between the magnetic pole teeth portions 16 and 17 is increased, the magnetic portion 12 of the magnetic pole teeth portions 16 and 17 is provided. A configuration in which the side ends are not close to each other is realized. As a result, the generation of the leakage magnetic flux is suppressed, the magnetic flux 101 passing through the magnetic path constituted by the magnetic pole tooth portions 16 and 17, the back yoke portions 14 and 15 and the magnetic portion 12 is maintained, and the attractive force of the electromagnet 11 is reduced. Is suppressed or prevented. In this way, the radial bearing 10 can be downsized in the radial direction R while maintaining the attractive force of the electromagnet 11.

  Moreover, if the shape of the coils 18 and 19 is changed (if the shape of the coils 18 and 19 is reduced in the axial direction Z), the radial bearing 10 is moved in the axial direction Z while maintaining the radial dimension R of the radial bearing 10. It is also possible to reduce the size. Thereby, the natural frequency of the rotating shaft 2 becomes high, and the rotating shaft 2 can be rotated at higher speed.

  In the first embodiment, the back yoke portions 14 and 15 of the electromagnet 11 are divided for each magnetic pole tooth portion. Accordingly, for example, the coils 18 and 19 can be easily wound as compared with the case where the back yoke portion is not divided, and the area occupied by the coils 18 and 19 in the cross section cut along the axial direction Z is increased. 11 suction force can be increased. In other words, the shape of the coils 18 and 19 can be reduced in the axial direction Z while maintaining the attractive force of the electromagnet 11, and the rotating shaft 2 can be rotated at a higher speed as described above.

  The detected portion 13b of the displacement sensor 13 is provided on the outer peripheral surface of the magnetic portion 12 or the rotating shaft 2, and the detecting portion 13a is opposed to the detected portion 8b at a position overlapping the electromagnet 11 in the radial direction R. Since it is arranged, the radial bearing 10 can be reduced in size in the axial direction Z by the amount that the detection unit 13a and the electromagnet 11 overlap, and the rotating shaft 2 can be rotated at a higher speed as described above.

Embodiment 2. FIG.
FIG. 5 is a cross-sectional view of the radial bearing 10 according to the second embodiment of the present invention viewed from the axial direction Z. The second embodiment has the same or corresponding configuration as the first embodiment except for the points described below. In the description of the second embodiment, the same or corresponding components as those in the first embodiment are denoted by the same reference numerals.

  In the second embodiment, eight electromagnets 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H are arranged side by side in the circumferential direction. The eight electromagnets have the same shape. As for the sensor 13, as in FIG. 2, the four detectors 13a are uniformly arranged in the circumferential direction with an angular interval of 90 °. In the second embodiment, reference numerals 14, 16, and 18 are assigned to the back yoke portion, the magnetic teeth portion, and the coil on the side close to the detection portion 13a of the sensor 13 (hereinafter referred to as the detection portion side), respectively, and the detection portion 13a of the sensor 13 is provided. Reference numerals 15, 17 and 19 are assigned to the back yoke portion and the magnetic teeth portion on the side far from the back (hereinafter referred to as the counter-detecting portion side), respectively.

  In the second embodiment, the circumferential length of the back yoke portion 14 on the detection unit side is larger than the circumferential length of the back yoke portion 15 on the counter detection unit side. Further, in the second embodiment, the tip portions 16b and 17b of the magnetic teeth portions 16 and 17 are maintained so that the distance between them is from the base portions 16a and 17a toward the magnetic portion 12 of the rotating shaft 2 (that is, the distance is constant). It is bent with respect to the base portions 16a and 17a. In FIG. 5, the bending angle with respect to the base portion 16a of the tip portion 16b of the magnetic pole tooth portion 16 on the detection portion side is larger than the bending angle with respect to the base portion 17a of the tip portion 17b of the magnetic pole tooth portion 17 on the counter detection portion side. As described above, the tip portions 16b and 17b extend from the base portions 16a and 17a toward the magnetic portion 12 of the rotary shaft 2 so that the distance between the magnetic pole teeth portions 16 and 17 is maintained constant.

  In the second embodiment, if the arrangement in the cross section cut along the axial direction Z of the radial bearing 10 permits, the tip end portions 16b and 17b of the magnetic pole teeth portions 16 and 17 are directed from the base portions 16a and 17a toward the magnetic portion 12. You may extend so that a space | interval may be maintained (that is, the space | interval of both is constant or substantially constant).

  According to the second embodiment, even when five or more electromagnets 11 are provided on the radial bearing 10, the effects described in the first embodiment can be obtained.

Other embodiments.
As mentioned above, although this invention was demonstrated using embodiment, it should be understood that this invention is not limited to the above-mentioned embodiment. The features described in each embodiment may be freely combined. In addition, various improvements, design changes, and deletions may be added to the above-described embodiments.

  For example, in the above-described embodiment, the tip portions 16b and 17b of the magnetic pole tooth portions 16 and 17 of one electromagnet 11 are bent with respect to the base portions 16a and 17a, so that the distance between the two portions is different from the base portions 16a and 17a. The example which spreads toward the 2 magnetic part 12 or was maintained was demonstrated. The present invention is not limited to this, and the tip portions 16b and 17b of the magnetic pole tooth portions 16 and 17 of one electromagnet 11 can be separated from the base portions 16a and 17a by, for example, notching the surface portions facing each other. You may make it expand toward the magnetic part 12, or may be maintained.

  In the above-described embodiment, the example in which the back yoke portions 14 and 15 of the electromagnet 11 are divided into the magnetic teeth portions 16 and 17 has been described. The present invention is not limited to this, and for example, the back yoke portion may be divided for each electromagnet 11 as shown in FIG. 6, or 2 that sandwich the detection portion 13 a of the sensor 13 as shown in FIG. 7. One back yoke portion may be divided as one unit. Further, the back yoke portions 14 and 15 are not divided and may be integrated over the entire circumference of the radial bearing 10.

  In the above-described embodiment, a radial magnetic bearing of a type (heteropolar type) in which a magnetic path is formed in a plane perpendicular to the rotating shaft 2 is used. The present invention is not limited to this, and may be, for example, a radial magnetic bearing of a type (homopolar type) in which a magnetic path is formed in a plane parallel to the rotating shaft 2.

  Further, in the above-described embodiment, eddy current type sensors are used as the displacement sensor 13 of the radial bearing 10 and the displacement sensor 23 of the thrust bearing 20. The present invention is not limited to this. For example, a capacitive sensor may be used.

  In the above-described embodiment, the radial bearing 10 is provided with the pair of displacement sensors 13 and 13 so as to face each other with the rotary shaft 2 interposed therebetween, and the differential of the outputs of both displacement sensors is obtained. The present invention is not limited to this, and only one of the pair of displacement sensors 13, 13 may be provided.

  In the above-described embodiment, an example in which four (Embodiment 1) or eight (Embodiment 2) electromagnets 11 are used for one radial bearing 10 has been described. The present invention is not limited to this, and one to three, five to seven, or nine or more electromagnets 11 may be used.

1 Blower, 2 Rotating shaft, 3 Motor, 4 Blade, 5 Casing, 6 Stator, 7 Rotor, 10 Radial magnetic bearing, 11 Electromagnet, 12 Magnetic part, 13 Displacement sensor, 13a Detection part, 13b Detected part, 14, 15 Back yoke part, 16, 17 Magnetic teeth part, 16a, 17a Base part, 16b, 17b Tip part, 18, 19 Coil, 20 Thrust magnetic bearing, 21 Thrust disk, 22 (22a, 22b) Electromagnet, 23 Displacement sensor, 24a, 24b Coil, 30 (31, 32) Touchdown bearing, 40 Speed sensor

Claims (6)

A radial magnetic bearing for supporting a rotating body from the radially outer side in a non-contact manner,
A plurality of electromagnets provided to face the rotating body and generate magnetic flux for supporting the rotating body,
The plurality of electromagnets are respectively wound around a back yoke portion, a pair of magnetic teeth portions that form a magnetic path in combination with the back yoke portion and the rotating body, and a pair of magnetic teeth portions. And
Each of the pair of magnetic teeth portions extends from the back yoke portion so that the distance between the pair of magnetic teeth portions decreases, and the distance between the pair of magnetic teeth portions increases from the base toward the rotating body. Or a tip that extends to be maintained,
Radial magnetic bearing. The tip portions of the pair of magnetic teeth portions are bent with respect to the base so that the distance between the base and the pair of magnetic teeth is widened or maintained.
The radial magnetic bearing according to claim 1. A plurality of displacement sensors arranged uniformly in the circumferential direction of the rotating body, for detecting a radial displacement of the rotating body;
The plurality of electromagnets includes a first electromagnet and a second electromagnet arranged with the displacement sensor interposed therebetween in the circumferential direction of the rotating body,
The radial magnetic bearing according to claim 1 or 2. The plurality of electromagnets includes a third electromagnet disposed adjacent to the first electromagnet,
A first magnetic pole teeth portion of the first electromagnet and a second magnetic pole teeth portion of the third electromagnet are adjacent to each other;
The first and second magnetic pole tooth portions are respectively a base portion extending from the back yoke portion so that a distance between the first and second magnetic pole tooth portions is narrowed, and the first and second magnetic pole tooth portions from the base portion toward the rotating body. A tip portion that is bent with respect to the base so that the interval between the second magnetic pole teeth portions is widened or maintained.
The radial magnetic bearing according to claim 3. The back yoke portion of each electromagnet is divided for each magnetic tooth portion,
The radial magnetic bearing of any one of Claim 1 to 4. A rotating shaft of a motor as the rotating body;
The radial magnetic bearing according to any one of claims 1 to 5,
A blade fixed to the rotating shaft;
Blower equipped with.

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