JPH0617830A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To detect a bending mode of a rotation axis by arranging position sensors on both sides of an electromagnet of a bearing part in the axial direction while saving a space of a magnetic bearing device in the axial direction. CONSTITUTION:A plural number of pairs of electromagnets 6, 6,... arranged on the inner periphery of a bearing hole 3 are divided into two groups on a flat surface P passing a center OH of the bearing hole 3 and both groups 7, 7 are slipped in the axial direction, and in a space made by the slipping, position sensors 8, 8 to detect displacement of a rotation axis 1 are respectively arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing device for supporting a rotating shaft by floating it in a bearing hole by a magnetic field generated by an electromagnet, and more particularly to a displacement amount of the rotating shaft for controlling the magnetic field strength of the electromagnet. The present invention relates to an arrangement structure of a detection unit that detects

[0002]

2. Description of the Related Art A magnetic bearing device of this type has a bearing portion in which a plurality of pairs of electromagnets (electromagnetic coils) for generating a magnetic field are arranged facing each other on the inner surface of a bearing hole through which a rotary shaft is inserted. Then, the amount of displacement of the rotating shaft with respect to the center of the bearing hole is detected by an eddy current type position sensor, and the magnetic field strength of the electromagnet is controlled according to the amount of displacement of the rotating shaft detected by this position sensor. It was made to float inside.

As an example of such a magnetic bearing device, in the conventional one disclosed in Japanese Utility Model Laid-Open No. 2-91111, by disposing the position sensors on both sides in the axial direction of the electromagnet, a bending mode of the rotating shaft is obtained. Is configured to detect.

[0004]

By the way, in the magnetic bearing, in order to secure a space for accommodating a touchdown, a protective bearing, or the like, or to shift the bending resonance of the rotary shaft to a high rotational speed, the axial length of the rotary shaft is increased. In order to shorten the length, it is desirable to save space in the axial direction. However, in the above-mentioned conventional example, since the position sensors are arranged on both sides of the electromagnet, the axial space of the bearing portion is correspondingly increased,
It was difficult to meet the above requirements.

The present invention has been made in view of the above problems. An object of the present invention is to improve the structure of the bearing portion so as to save space in the axial direction and to position the position sensor in the shaft of the electromagnet. It is to be able to arrange on both sides in the direction.

[0006]

In order to achieve the above object, in the invention of claim 1, the electromagnets arranged on the inner circumference of the bearing hole are divided into two groups on a plane passing through the center of the bearing hole, and both groups are divided into two groups. It was decided to shift in the axial direction, and position sensors were arranged in the spaces created by the shift.

That is, according to the present invention, as shown in FIGS. 1 to 3, a bearing portion (2) having a bearing hole (3) through which the rotary shaft (1) is inserted and an inner surface of the bearing hole (3) are provided. A plurality of pairs of electromagnets (6), (6), ..., Which are arranged to face the center (OH) of the bearing hole (3) and generate a magnetic field, and a rotary shaft () for the center (OH) of the bearing hole (3). 1) is provided with position detecting means (8), (8), ... Detecting the amount of displacement, and according to the amount of displacement of the rotary shaft (1) detected by the position detecting means (8), (8) ,. It is premised on a magnetic bearing device in which the magnetic field strength of each electromagnet (6) is controlled so as to levitate and support the rotating shaft (1) in the bearing hole (3).

The electromagnets (6), (6), ...
Is divided into two electromagnet groups (7) and (7) with a plane (P) passing through the center (OH) of the bearing hole (3) as a boundary, and both electromagnet groups (7) and (7) are divided into one electromagnet. The groups (7) are offset from each other in the direction of the center line of the bearing hole (3) so that the groups (7) partially project from the other electromagnet group (7), and each electromagnet group (7)
The position detecting means (8), (8), ... Are respectively arranged on the opposite side to the direction of displacement with respect to the counterpart electromagnet group (7).

In the invention of claim 2, as shown in FIGS. 2 to 5, the bearing portion (2) is formed of a pair of half-divided cylindrical divided portions (2a) and (2b), and each divided portion is formed. (2a), (2
b) is provided with electromagnet groups (7) and (7), respectively.

According to the third aspect of the invention, as shown in FIG. 1, the bearing portion (2) constitutes a pair, and the bearing portions (2) and (2) are arranged such that the center (OH) of each bearing hole (3) is located in the bearing hole (3). The bearings are provided apart from each other in the axial direction of the rotary shaft (1) so as to be located on the same line, and the direction of positional deviation between the electromagnet groups (7) and (7) of one bearing portion (2) is set to the other bearing portion (2). To the opposite direction.

[0011]

With the above construction, in the invention of claim 1, the two electromagnet groups (7), (7) separated by the plane (P) passing through the center (OH) of the bearing hole (3) are used as the bearings. Hole (3)
Of the respective electromagnet groups (7) are arranged on opposite sides of the respective electromagnet groups (7) with respect to the opposite electromagnet group (7). Therefore, each of the position detecting means (8) is located behind the projecting portion of the electromagnet group (7), and although the axial total length of the bearing portion (2) itself is slightly long, the position detecting means arranged on both sides of the position detecting means (8) are detected. The length including the means (8), (8), ...
The axial length of each position detecting means (8) and the distance from the electromagnet group (7) can be shortened, so that axial space can be saved. Further, since the pair of position detecting means (8) and (8) are arranged on both sides of the bearing portion (2) in the axial direction, the bending mode of the rotating shaft (1) can be detected.

According to the second aspect of the present invention, since the bearing portion (2) is composed of a pair of half-split cylindrical divided portions (2a) and (2b), the cylindrical bearing portion of an ordinary magnetic bearing is divided into half. The bearing part (2) can be formed by joining the divided parts (2a) and (2b) in a misaligned state, and the bearing part (7) in which the electromagnet groups (7) and (7) are misaligned. 2) can be easily manufactured.

As described above, when the electromagnet groups (7), (7) in the bearing portion (2) are axially displaced from each other, the rotating shaft () of the electromagnet (6) in each electromagnet group (7) ( Since the acting position of the magnetic force on 1) is also displaced, a moment about the central position between both electromagnet groups (7) and (7) is generated on the rotating shaft (1). In the invention of claim 3, the rotating shaft (1)
A pair of bearing portions (2) provided apart from each other in the axial direction of
Since the position deviation directions of the electromagnet groups (7) and (7) in (2) are opposite to each other, the bearing portions (2)
The above-mentioned moments can be canceled in the opposite directions, and the structure of the control system can be simplified.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows the overall structure of a magnetic bearing device according to Embodiment 1 of the present invention. (1) is, for example, a rotating shaft of a motor, and each rotating shaft (1) has a bearing hole ( Bearing part (2) consisting of two left and right magnetic bearings having 3),
It is rotatably supported by (2). The left and right bearing portions (2), (2) are separated from each other in the axial direction of the rotary shaft (1) so that the centers (OH) of the bearing holes (3) are located on the same line.

Both the bearings (2), (2) have the same structure, and as shown in FIGS. 4 and 5, a substantially cylindrical shape formed by stacking a large number of thin iron plates etc. in the axial direction. The bearing hole (3) for inserting the rotary shaft (1) is provided therein. On the inner surface of the bearing hole (3), there are four pairs of protrusions (4), (4), ... Which protrude toward the center (OH) of the bearing hole (3), each pair being the center of the bearing hole (3) ( O
2). As shown in FIGS. 2 and 3, electromagnetic coils (5) are wound in multiple layers around each protrusion (4). , And the four pairs of electromagnets (6), (6), having the protrusions (4) as magnetic cores by the protrusions (4) are located at the center (OH) of the bearing hole (3).
), The electromagnets (6) adjacent to each other,
(6) By energizing the electromagnetic coil (5) so as to form a magnetic path (MP) between them, a magnetic field for attracting the rotating shaft (1) is generated in each electromagnet (6). ing.

The bearing portion (2) is a portion of the bearing hole (3) where the electromagnet (6) forming the magnetic path (MP) is avoided.
Is divided into a pair of half-divided cylindrical divisions (2a) and (2b) with a plane (P) passing through the center (OH) of each of them as a boundary, and these divisions (2a) and (2b) are formed into bearing holes ( 3) The parts are joined to each other at the dividing surfaces while being displaced from each other by a predetermined dimension in the direction of the center line. As a result, the eight electromagnets (6), (6), ... Inside the bearing hole (3) are located at the center (OH) of the bearing hole (3).
4 electromagnets (6) with a plane (P) passing through as a boundary,
(6), are divided into two electromagnet groups (7) and (7), respectively, and the electromagnet groups (7) and (7) are respectively provided in the divided portions (2a) and (2b). Electromagnet group (7),
In (7), one electromagnet group (7) is the other electromagnet group (7)
They are offset from each other in the direction of the center line of the bearing hole (3) so as to partially project.

As shown in FIG. 1, the electromagnet groups (7) in the left bearing portion (2) are displaced from each other by the electromagnet group (7) in the right bearing portion (2).
(7) The direction is opposite to the direction of positional displacement between the two.

Further, as shown in FIGS. 2 and 3, on both sides in the axial direction of the bearings (2), the respective electromagnet groups (7) are arranged on the opposite side to the direction of deviation from the counterpart electromagnet group (7). Two position sensors (8) and (8) are connected to the magnetic path (MP
) Is formed so as to correspond to the position between the two electromagnets (6), (6). Each of these position sensors (8)
For example, an eddy current type of detecting the displacement amount of the rotating shaft (1) with respect to the center (OH) of the bearing hole (3) by measuring the distance from the rotating shaft (1) by supplying a high frequency signal, 2) Eight are provided as a whole. As shown in FIG. 1, the output signals of these eight position sensors (8), (8), ... Are fed to a control device (10) for controlling the output of the electromagnets (6) of the electromagnet groups (7). It is input, and in the control device (10), position sensors (8), (8), ...
According to the amount of displacement of the rotating shaft (1) detected by each of the bearings (2), (2)
The magnetic field strength of each electromagnet (6) is controlled so as to coincide with the center lines of the bearing holes (3) and (3) of the rotary shaft (1) in the bearing hole (3) of each bearing portion (2). It is configured to float and support.

Therefore, in the above embodiment, the rotation shaft (1) is moved to the both bearing portions (2) and (2) by the operation of the motor.
When rotating in the bearing holes (3), (3) of the bearing part (2), the position sensor (8) causes the center (O
The amount of displacement of the rotary shaft (1) from H) is detected, and in the control device (10), the axial center (OA) of the rotary shaft (1) is determined according to the detected amount of displacement of the rotary shaft (1). The magnetic field strength of each electromagnet (6) is controlled so as to always coincide with the center lines of the bearing holes (3) and (3) of both bearing portions (2) and (2),
By this control, the rotating shaft (1) is supported in a floating state in the bearing hole (3) of each bearing portion (2).

In this case, in each bearing portion (2), two electromagnet groups (7), (7) separated by a plane (P) passing through the center (OH) of the bearing hole (3) are used as bearings. There are two position sensors (8) and (8) that are displaced from each other in the direction of the center line of the hole (3) and are on the opposite side of the displacement direction of each electromagnet group (7) with respect to the counterpart electromagnet group (7). Since they are provided, each position sensor (8) is located behind the protruding portion of the electromagnet group (7). As a result, although the overall axial length of the bearing portion (2) becomes long, the position sensors (8), (8), arranged on both sides of the bearing portion (2),
The length including ... becomes shorter by the axial length of the position sensor (8) and its distance to the electromagnet group (7) than in the case where there is no misalignment, whereby the axial direction of the magnetic bearing device is reduced. It is possible to save space. Due to this space saving, for example, the axial length of the rotary shaft (1) can be shortened and its bending resonance can be shifted to a high rotational speed region, which enables control at a high rotational speed and the axial direction of the rotary shaft (1). This is advantageous for accommodating touchdowns and protective bearings placed at the ends.

Further, each bearing portion (2) is divided by a plane (P) passing through the center (OH) of the bearing hole (3) as a boundary.
Since it is composed of a pair of divided parts (2a) and (2b), it is used in a normal magnetic bearing when the bearing part (2) in which the electromagnet groups (7) and (7) are displaced is produced. Cylindrical bearing part is divided in half and its divided parts (2a), (2b)
It suffices to bond the two in a positionally displaced state, which facilitates the manufacture of the bearing portion (2).

When the electromagnet groups (7) and (7) in each bearing portion (2) are axially displaced as described above, the rotating shaft of the electromagnet (6) in each electromagnet group (7) is displaced. Since the acting position of the magnetic force on (1) is also displaced in the axial direction, a moment is generated on the rotating shaft (1) about the center between both electromagnet groups (7) and (7). However, as shown in FIG. 1, the electromagnet group (7) in each of the pair of bearings (2), (2) provided apart from each other in the axial direction of the rotating shaft (1),
(7) Since the displacement directions of the two are opposite to each other,
In the bearing (2) on the left side of the rotating shaft (1), a moment (M) in the clockwise direction in the figure is generated, and on the right side of the bearing (2)
Then, a counterclockwise moment (M) opposite to that on the left side is generated, and both moments (M) and (M) cancel each other out.
The control system in can be simplified.

Further, a pair of position sensors (8), (8)
Are arranged on both sides in the axial direction of each bearing (2),
The position of the rotary shaft (1) at the axial center of the bearing portion (2) can be accurately detected, and the bending mode of the rotary shaft (1) can be detected.

In the first embodiment, the cylindrical bearing portion is divided in half and the divided portions (2a) and (2b) are joined together in a positionally displaced manner, whereby the electromagnet groups (7) and (7) are joined. The bearing part (2) is manufactured by shifting the position of the sheet metal. However, in addition to this split type, when, for example, a large number of thin iron plates are laminated in the axial direction, the thin iron plates are circular at the axial middle part. An annular bearing is laminated at both ends, and half-circular annular ones are laminated at both ends at the center (OH) of the bearing hole (3) so as to face each other to form an integral bearing (2). Good.

(Second Embodiment) FIGS. 6 and 7 show a second embodiment (note that the same parts as those in FIGS. 2 and 3 are designated by the same reference numerals and detailed description thereof will be omitted).

In this embodiment, each of the above position sensors (8)
A plate-shaped magnetic member (12) made of an iron material or the like is arranged between the two electromagnets (6) and (6) facing each other in the axial direction. This magnetic member (12) is fixedly supported by a motor housing (not shown) at the end portion on the outer peripheral side (the side opposite to the rotating shaft (1)), and the inner end portion (rotating shaft (1) side) is on the electromagnet (6) side. It is bent parallel to the axis of rotation (1).

Therefore, in this embodiment, even if a part of the magnetic flux (indicated by the broken line in the figure) generated in the electromagnetic coil (5) of each electromagnet (6) leaks from the magnetic core, the leaked magnetic flux has a magnetic permeability. The magnetic shield effect can be obtained by concentrating on the high magnetic member (12), and the leakage magnetic flux can be prevented from acting on the position sensor (8). As a result, the position sensor (8) is moved away from the electromagnet (6) to a position where the magnetic flux is weakened (this causes a problem that the space in the axial direction becomes large), the current to the electromagnet (6) is reduced, and the magnetic circuit Without decreasing the magnetic flux density in the magnetic circuit due to increase in size or the like (reducing control force and size problems), the influence of the leakage magnetic flux of the position sensor (8) is suppressed, and the rotating shaft (1) There is an advantage that it is possible to effectively prevent position detection failure and control instability, and to improve reliability.

(Embodiment 3) FIGS. 8 and 9 show Embodiment 3 in which the magnetic member (12) as in Embodiment 2 is replaced with a position sensor (8) on the side opposite to the electromagnet (6). The permanent magnet (13) is arranged and supported, and the magnetic flux from this magnet (13) acts in the opposite direction to the leakage magnetic flux from the electromagnet (6) at the position of the position sensor (8) to cancel the leakage magnetic flux. It is a thing. Therefore, also in this embodiment, the same effect as that of the second embodiment can be obtained.

(Embodiment 4) FIG. 10 shows Embodiment 4 in which the magnetic member (12) having the same function as that of Embodiment 2 is applied to a magnetic damper for suppressing the axial movement of the rotary shaft (1). It was done. That is, a magnetic circuit forming member (15) is attached to a predetermined position on the outer circumference of the rotary shaft (1) so as to rotate integrally, and a groove portion (16) is formed on the outer peripheral surface of the member (15). On both side surfaces, annular permanent magnets (17) and (18) are attached and fixed so as to face each other at intervals in the axial direction of the rotating shaft (1). A ring-shaped guide plate (1) is provided between the magnets (17) and (18).
The inner peripheral portion of 9) is arranged with a gap between the magnets (17) and (18), and the guide plate (19) is fixedly supported by the housing (not shown) at the outer peripheral portion. Both magnets (1
The magnetic flux from 7) and (18) is applied to the magnetic circuit forming member (15).
By acting on the conducting plate (19) via the
7) and (18) are levitated in a non-contact state with respect to the guide plate (19) to regulate the axial movement of the rotating shaft (1). (2
0) is the rotor of the motor.

Between the magnetic circuit forming member (15) and the motor rotor (20), a hall sensor (21) for controlling the motor for detecting the operating state of the motor based on the magnetism generated by the motor. Are mounted and supported on the housing. In this embodiment, the magnetic circuit forming member (1
A dish-shaped magnetic member (12) is arranged between the magnetic circuit forming member (15) and the hall sensor (21) in order to shield a leakage magnetic flux leaking from the hole sensor (21) to the hall sensor (21). The member (12) is fixedly supported on the motor housing at the outer peripheral edge portion.

Therefore, in the case of this embodiment, the magnet (1
The magnetic circuit forming member (1) formed by (7) and (18).
Even if part of the magnetic flux passing through 5) leaks to the Hall sensor (21) side, the leak magnetic flux can be shielded by the magnetic member (12), and the influence of the leak magnetic flux on the Hall sensor (21) can be reduced to reduce the motor The operating state can be accurately detected, and the reliability of motor control can be improved.

(Fifth Embodiment) FIG. 11 shows a fifth embodiment of the present invention, which is different from the magnetic damper in the fourth embodiment in the same manner as in the third embodiment.
Is arranged and supported, and the magnetic flux from the permanent magnet (13) and the leakage magnetic flux leaking from the magnetic circuit forming member (15) are canceled by the Hall sensor (21). Therefore, also in this embodiment, the same effect as that of the fourth embodiment can be obtained.

[0034]

As described above, according to the invention of claim 1,
A plurality of pairs of electromagnets arranged on the inner circumference of the bearing hole of the magnetic bearing are divided into two groups on a plane passing through the center of the bearing hole, and both groups are axially displaced, and the displacement of the rotary shaft is respectively caused in the spaces generated by the displacement. By arranging the position detecting means for detecting, each position detecting means is arranged behind the protruding portion of the electromagnet group, and the axial length including the bearing portion and the position detecting means on both sides thereof can be shortened. It is possible to save space in the direction. Therefore, the axial length of the rotary shaft can be shortened, the bending resonance can be shifted to a high rotational speed region, and control at high rotational speed becomes possible. Further, the bending mode of the rotating shaft can be detected by detecting the displacement of the rotating shaft by the pair of position detecting means arranged on both sides of the electromagnet in the axial direction.

According to the second aspect of the present invention, the bearing portion is made up of a pair of half-divided cylindrical divided portions, and each divided portion is provided with an electromagnet group. The bearing part can be formed only by joining the divided parts that are divided in half in a misaligned state, and the bearing part in which the electromagnet group is misaligned can be easily manufactured.

According to the third aspect of the present invention, the bearing portions are provided as a pair, and both bearing portions are provided apart from each other in the axial direction of the rotary shaft so that the centers of the respective bearing holes are located on the same line. By setting the direction of displacement of the electromagnet groups in the opposite direction to that of the other bearing, a moment around the center between the electromagnet groups is generated on the rotating shaft due to the displacement of the electromagnet groups in the bearing. Even in this case, the moments can be offset in the respective bearing portions in opposite directions to cancel each other, and the configuration of the control system can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a side view of each bearing portion in the first embodiment.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a side view of a magnetic core of each bearing portion in the first embodiment.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a cross-sectional view of essential parts in a second embodiment.

FIG. 7 is a development view taken along the line VII-VII in FIG.

FIG. 8 is a view corresponding to FIG. 6 showing a third embodiment.

9 is a development view taken along the line IX-IX in FIG.

FIG. 10 is a cross-sectional view of essential parts in a fourth embodiment.

FIG. 11 is a view corresponding to FIG. 10 showing the fifth embodiment.

[Explanation of symbols]

 (1) Rotating shaft (2) Bearing part (2a), (2b) Divided part (3) Bearing hole (OH) Center (6) Electromagnet (7) Electromagnet group (8) Position sensor (position detection means) (10) Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromichi Ueno 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Kanaoka Factory, Sakai Manufacturing Co., Ltd. (72) Hiroshi Sugawara, 3-12, Chikko Shinmachi, Sakai City, Osaka Prefecture Daikin Industries Sakai Seisakusho Co., Ltd.

Claims (3)

[Claims] 1. A bearing hole (3) through which a rotary shaft (1) is inserted.
And a plurality of pairs of electromagnets (6), (6) arranged to face the center (OH) of the bearing hole (3) on the inner surface of the bearing hole (3) and generating a magnetic field. , And position detecting means (8), (8), for detecting the amount of displacement of the rotating shaft (1) with respect to the center (OH) of the bearing hole (3), and the position detecting means (8), ( 8), ... The magnetic field strength of each electromagnet (6) is controlled according to the displacement amount of the rotating shaft (1) detected so that the rotating shaft (1) is levitated and supported in the bearing hole (3). In the above magnetic bearing device, the electromagnets (6), (6), ... Are divided into two electromagnet groups (7), (7) with a plane (P) passing through the center (OH) of the bearing hole (3) as a boundary. Separated, both electromagnet groups (7),
In (7), one electromagnet group (7) is the other electromagnet group (7)
Are offset from each other in the direction of the center line of the bearing hole (3) so as to project more partially than each other, and the position detection means is provided on the side opposite to the direction in which each electromagnet group (7) is displaced with respect to the mating electromagnet group (7). (8),
(8), ... Are provided in the magnetic bearing device. 2. The magnetic bearing device according to claim 1, wherein the bearing portion (2) is a pair of half split cylindrical split portions (2a),
A magnetic bearing device comprising (2b), wherein electromagnet groups (7) and (7) are provided in each of the divided portions (2a) and (2b). 3. The magnetic bearing device according to claim 1 or 2, wherein the pair of bearing portions (2), (2) locate the center (OH) of each bearing hole (3) on the same line. Rotating shaft (1)
Of the electromagnet groups (7), (7) of one bearing portion (2) are opposite to the other bearing portion (2). Magnetic bearing device characterized by.