JP2008223802A - Bearing device and rotary drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device capable of extending bearing life of a rotary shaft. <P>SOLUTION: The bearing device 110 is provided with a radial bearing 70 including a front side foil bearing 30 and a rear side foil bearing 40 provided to put a drive motor 20 therebetween in an axial direction of the rotary shaft 82, and an axial bearing 51 including a magnetic bearing 50 providing axial support. Part of air flowing in from an air flow in path 12 of a compression part 1 is compressed by the compressor 1, and is supplied to an inside of a compressor 91 main body from a bypass path 14 provided in a middle of an air delivery path 13 connected to the compression part 1. Consequently, higher dynamic pressure is generated between the rotary shaft 82 and the radial bearing 70 by rise of pressure in the compressor 91 main body to pressure higher than 1 atm, and frequency of contact of the rotary shaft 82 and the radial bearing 70 can be inhibited. Consequently, bearing life of the radial bearing 70 can be extended. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing device, and more particularly to a rotary drive device.

  BACKGROUND ART A rotary drive device that drives rotary equipment such as a compressor, a blower, and a turbine is provided with a bearing device that supports a rotary shaft. In particular, in a small rotating device or a rotating device that avoids the use of oil, a dynamic pressure gas bearing such as a foil bearing or a magnetic bearing is used. In such a bearing device, the rotary shaft is supported as a foil bearing as a radial bearing and a magnetic bearing as an axial bearing.

  A foil bearing is a bearing that draws in ambient gas by a wedge action or a pump action generated by relative sliding between the rotating shaft and the bearing, and increases the pressure between the rotating shaft and the bearing to obtain load capacity and bearing rigidity. The foil bearing has advantages such as low cost and oil-free. However, there is a problem in that sufficient dynamic pressure cannot be generated during low-speed rotation of the rotating shaft and when disturbance vibration occurs, resulting in friction and seizure.

  In order to eliminate the problem of friction and seizure in foil bearings when rotating at low speeds and when disturbance vibrations occur in foil bearings, it is used in combination with foil bearings so that a part of the rotating shaft is supported in the thrust direction. A bearing device including a magnetic bearing has been proposed (see, for example, Patent Document 1). FIG. 5 is a front sectional view of a bearing device 80 including an axial direction bearing having a magnetic bearing that supports a part of the rotating shaft in the thrust direction in combination with the dynamic pressure gas bearing.

  In FIG. 5, the bearing device 80 includes a rotating shaft 82 in a casing 81, and one of the rotating shafts 82 can float between the casing 81 and the rotating shaft 82 in the axial direction. A dynamic pressure gas bearing 83 is provided. The dynamic pressure gas bearing 83 is a foil bearing having foils 86 on both surfaces of a thrust disc 85 integrally formed at a position below the rotary shaft 82.

  In the bearing device 80, a rotating shaft 82 is inserted into the inner periphery of the casing 81 from above the casing 81. The inner diameter of the casing 81 is set slightly larger than the outer diameter of the rotating shaft 82. When the dynamic pressure gas bearing 83 functions, a minute gap is formed between the casing 81 and the rotating shaft 82.

  That is, when the bearing device 80 is in a steady operation, as the rotary shaft 82 rotates, the upper surface 85a of the thrust disk 85 and the fixed disk protruding from the casing 81 at a position facing the upper surface 85a. A dynamic pressure is generated by the air being drawn in at a high speed between the inner surface 81 and the lower surface 85b of the thrust disk 85 and the inner wall 81a of the casing 81 facing the lower surface 85b. Then, the rotating shaft 82 is levitated and supported in the axial direction (the direction of arrow P in the figure) by the generated dynamic pressure.

  Further, in the bearing device 80, a magnetic bearing 84 is provided on the upper inner periphery of the casing 81. At a position facing the magnetic bearing 84, a magnetic target portion 88 that is integrally formed with the rotary shaft 82 is provided. And the target part 88 is attracted | sucked by the magnetic force which the electromagnet (not shown) of the magnetic bearing 84 generate | occur | produces, and the rotating shaft 82 is levitated and supported in the axial direction.

  According to such a configuration, when sufficient dynamic pressure is not generated in the dynamic pressure gas bearing 83 when the rotation shaft 82 rotates at a low speed or when disturbance vibrations occur, the rotation shaft 82 has the magnetic bearing 84, the target unit 88, and the like. The suspension is supported by magnetic attraction acting between the two. As a result, gaps are formed between the thrust disc 85 provided in the dynamic pressure gas bearing 83 and the inner wall 81a of the casing 81, and between the thrust disc 85 and the fixed disc 87, and the rotating shaft 82 is formed in the casing. Contact with the inner wall 81a of 81 can be prevented. Further, in the bearing device 80, after the rotating shaft 82 rotates at a high speed, dynamic pressure is generated by the air in the casing 81, and there is no need to keep supplying constant air unlike a static pressure gas bearing. It is described that the cost can be reduced.

  FIG. 6 shows a compressor 90 as an example of the rotary drive device. FIG. 6 is a schematic diagram of a compressor 90 as a rotary drive device provided with a conventional axial direction bearing and a radial direction bearing.

  The compressor 90 is used in a horizontal orientation in which the rotation shaft 82 is in the horizontal direction. The compressor 90 is provided with a compression unit 1 and a drive unit 2. The compression part 1 and the drive part 2 are connected by the compression part casing 10a of the casing 10 and the drive part casing 10b.

  The compression unit 1 is located in front of the drive unit 2 (the left side in FIG. 6 is the front). The compression unit 1 is provided with an air inflow path 12 through which air flows and an impeller 11 that compresses the air that flows in through the air inflow path 12 and discharges the compressed air through the air discharge path 13.

  The drive unit 2 is provided with a drive motor 20, a rotary shaft 82 that is rotationally driven by the drive motor 20, and a bearing device 100 that supports the rotary shaft 82. The drive motor 20 includes a stator 22 fixed to the drive unit casing 10 b and a rotor 23 provided on the outer periphery of the rotary shaft 82. A target portion 24 is provided on the rear side of the rotor 23 in the axial direction of the rotation shaft 82, that is, on the opposite side of the compression portion 1 in the axial direction of the rotation shaft 82. The impeller 11 is connected to the distal end side of the rotating shaft 82, that is, the side accommodated in the compression unit 1 of the rotating shaft 82.

  The bearing device 100 includes a radial bearing 70 having a pair of foil bearings (that is, the front foil bearing 30 and the rear foil bearing 40) disposed so as to sandwich the drive motor 20 in the axial direction of the rotating shaft 82; An axial direction bearing 51 having a magnetic bearing 50 which supports the target portion 24 provided on the outer peripheral surface 82a of the rotating shaft 82 and supports in the axial direction is provided. Axial bearings 51 are paired so as to sandwich the target portion 24 in the radial direction. A position sensor 26 that detects the position of the rotating shaft 82 in the axial direction is provided at a position facing the end of the rotating shaft 82 opposite to the end where the impeller 11 is provided.

  The front foil bearing 30 includes a cylindrical front bearing housing 31 that is disposed in front of the drive motor 20 on the rotary shaft 82, that is, between the rotor 23 and the impeller 11, and is fixed to the drive unit casing 10b. On the contact surface of the front bearing housing 31 with the rotating shaft 82, a wave-shaped bump foil 32 and a sleeve-shaped top foil 33 are disposed.

  The rear foil bearing 40 is disposed behind the drive motor 20 on the rotating shaft 82, that is, between the rotor 23 and the axial bearing 51, and is configured in the same manner as the front foil bearing 30. That is, the rear foil bearing 40 includes a cylindrical rear bearing housing 41 that is fixed to the drive unit casing 10b. On the contact surface of the rear bearing housing 41 with the rotating shaft 82, a wave-shaped bump foil 42 and a sleeve-shaped top foil 43 are disposed.

Next, an operation mode of the compressor 90 configured as described above will be described.
In the compressor 90, the rotation shaft 82 is rotated by the drive motor 20 provided in the drive unit 2, and the impeller 11 of the compression unit 1 connected to the rotation shaft 82 is rotated. Thereby, the air which flowed in through the air inflow path 12 in the compression part 1 is compressed, and is discharged | emitted from the air discharge path 13 provided in the compression part casing 10a.

  Further, when the compressor 90 is in steady operation, dynamic pressure is generated between the outer peripheral surface 82 a of the rotary shaft 82 and the inner peripheral surfaces 33 a and 43 a of the top foils 33 and 43 as the rotary shaft 82 rotates. appear. Then, the rotary shaft 82 is supported in a non-contact state with the front foil bearing 30 and the rear foil bearing 40 by the air lubrication action by the dynamic pressure. Further, as the impeller 11 rotates, a force (thrust force) acting in the axial direction of the rotating shaft 82 is generated on the rotating shaft 82 as indicated by an outlined arrow.

However, the rotating shaft 82 is supported by the front foil bearing 30 and the rear foil bearing 40 in a state where sufficient dynamic pressure is not generated when the rotating shaft 82 rotates at a low speed or when disturbance vibrations occur.
Japanese Patent Laid-Open No. 10-292818

  Here, in the bearing device 100, when the vibration of the rotating shaft 82 exceeding the bearing rigidity is generated in the front foil bearing 30 and the rear foil bearing 40 when the rotating shaft 82 rotates at a low speed or due to disturbance vibration, the bearing device 100 The rotating shaft 82 is supported in contact with the front foil bearing 30 and the rear foil bearing 40 due to a lack of dynamic pressure inside 100. As a result, there is a problem that the bearing life is reduced.

  The present invention has been made in view of such circumstances, and the object thereof is to provide a rotating shaft and a bearing device even when vibration of the rotating shaft exceeding the bearing rigidity occurs due to low-speed rotation of the rotating shaft and disturbance vibration. It is providing the bearing apparatus which can aim at the increase in a bearing life by suppressing the contact frequency with.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to the first aspect of the present invention, there is provided a drive motor including a rotor integrally provided on the rotation shaft and a stator fixed to the casing, and a pair of foils disposed so as to sandwich the drive motor in the axial direction of the rotation shaft. A radial bearing having a bearing, an axial bearing having a magnetic bearing facing the target portion provided on the outer peripheral surface of the rotating shaft and supporting in the axial direction, and connected to the casing and fixed to the end of the rotating shaft In the bearing device, the impeller rotated by a drive motor and provided with an air discharge path for discharging compressed air is connected in the middle of the path of the air discharge path. A bypass path is provided for supplying to the battery.

  According to this configuration, a bypass path is provided between the air discharge path and the rotary drive device, and a part of the compressed air discharged from the air discharge path is supplied to the inside of the bearing apparatus through the bypass path. Since a pressure higher than 1 atm can be generated inside, a higher dynamic pressure can be generated without increasing the number of rotations of the rotating shaft, and a radial bearing having a pair of foil bearings and the rotating shaft can be generated. The contact frequency can be suppressed. As a result, the burden on the rotating shaft and the bearing device can be reduced and the durability life can be improved.

  According to a second aspect of the present invention, there is provided a drive motor comprising a rotor integrally provided on the rotary shaft and a stator fixed to the casing, and a pair of foils disposed so as to sandwich the drive motor in the axial direction of the rotary shaft. A radial bearing having a bearing, an axial bearing having a magnetic bearing facing the target portion provided on the outer peripheral surface of the rotating shaft and supporting in the axial direction, and connected to the casing and fixed to the end of the rotating shaft The rotary impeller rotated by a drive motor and provided with a bearing device including an air discharge path for discharging compressed air is connected to the middle of the path of the air discharge path, and a part of the compressed air is A bypass path for supplying the inside of the bearing device is formed.

  According to this configuration, a bypass path is provided between the air discharge path and the rotary drive device, and a part of the compressed air discharged from the air discharge path is supplied to the inside of the bearing apparatus through the bypass path. Since a pressure higher than 1 atm can be generated inside, a higher dynamic pressure can be generated without increasing the number of rotations of the rotating shaft, and a radial bearing having a pair of foil bearings and the rotating shaft can be generated. The contact frequency can be suppressed. As a result, the burden on the rotating shaft and the bearing device can be reduced and the durability life can be improved.

  According to a third aspect of the present invention, in the rotary drive device according to the second aspect, an adjustment valve for adjusting the amount of compressed air supplied into the bearing device is formed in the middle of the bypass path. It is characterized by.

  According to this configuration, it is possible to adjust the amount of air supplied from the bypass path to the inside of the compressor body to an arbitrary amount, and when the radial bearing having a pair of foil bearings is sufficiently acting Since it is not necessary to supply air from the bypass path to the inside of the compressor body, the compressed air can be used efficiently. As a result, cost reduction can be achieved.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the rotational drive apparatus provided with the bearing apparatus and bearing apparatus with which durable life is aimed at by suppressing the contact frequency with the rotating shaft of a radial direction bearing.

  Hereinafter, an embodiment in which a bearing device according to the present invention is embodied in a compressor 91 as a rotational drive device will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the configuration of the compressor 91. In the configuration of the compressor 91, the same configuration as that of the conventional compressor 90 will be described with the same reference numerals.

  The compressor 91 is used in a horizontal orientation in which the rotary shaft 82 is in the horizontal direction. The compressor 91 is provided with a compression unit 1 and a drive unit 2. The compression part 1 and the drive part 2 are connected by the compression part casing 10a of the casing 10 and the drive part casing 10b.

  The compression unit 1 is located in front of the drive unit 2, that is, on the left side in FIG. The compression unit 1 is provided with an air inflow path 12 through which air flows in and an impeller 11 that compresses the air flowing in through the air inflow path 12 and discharges it through the air discharge path 13. Then, in the middle of the path of the air discharge path 13 for discharging the air compressed by the rotation of the rotary shaft 82 and connected to one outer wall of the compression section casing 10a, the exhaust air is placed inside the compressor 91 main body. A bypass path 14 is provided for supplying the air supply unit. One end portion 14a of the bypass path 14 is connected to the outer wall 91a of the compressor 91, and a part of the compressed air is passed through the bypass path 14 through the compressor. 91 is configured to be supplied to the inside of the main body. In FIG. 1, a state in which the air discharged from the air discharge path 13 is supplied into the compressor 91 main body via the bypass path 14 is indicated by an arrow.

  The drive unit 2 is provided with a drive motor 20, a rotary shaft 82 that is rotationally driven by the drive motor 20, and a bearing device 110 that supports the rotary shaft 82. The drive motor 20 includes a stator 22 that is fixed to the drive unit casing 10 b and a rotor 23 that is provided integrally with the rotary shaft 82. The target portion 24 is provided on the rear side of the rotor 23 in the axial direction of the rotating shaft 82, that is, on the outer peripheral surface 82 a of the rotating shaft 82. Further, the distal end side of the rotation shaft 82 is accommodated in the compression unit 1.

  The bearing device 110 includes a radial bearing 70 having a pair of foil bearings (that is, the front foil bearing 30 and the rear foil bearing 40) disposed so as to sandwich the drive motor 20 in the axial direction of the rotary shaft 82; An axial direction bearing 51 having a magnetic bearing that supports in the axial direction is provided opposite to the target portion 24 provided on the outer peripheral surface 82a of the rotating shaft 82. Axial bearings 51 are paired so as to sandwich the target portion 24 in the radial direction. A position sensor 26 that detects the position of the rotating shaft 82 in the axial direction is provided at a position facing the end of the rotating shaft 82 opposite to the end where the impeller 11 is provided.

  The front foil bearing 30 includes a cylindrical front bearing housing 31 that is disposed in front of the drive motor 20 on the rotary shaft 82, that is, between the rotor 23 and the impeller 11, and is fixed to the drive unit casing 10b. On the contact surface of the front bearing housing 31 with the rotating shaft 82, a wave-shaped bump foil 32 and a sleeve-shaped top foil 33 are disposed.

  The rear foil bearing 40 is disposed behind the drive motor 20 on the rotating shaft 82, that is, between the rotor 23 and the axial bearing 51, and is configured in the same manner as the front foil bearing 30. That is, the rear foil bearing 40 includes a cylindrical rear bearing housing 41 that is fixed to the drive unit casing 10 b, and a corrugated bump foil 42 is provided on a contact surface of the rear bearing housing 41 with the rotating shaft 82. And the sleeve-like top foil 43 is arrange | positioned.

Next, the operation | movement aspect of the compressor 91 comprised as mentioned above is demonstrated.
In the compressor 91, the rotation shaft 82 is rotated by the drive motor 20 provided in the drive unit 2, and the impeller 11 of the compression unit 1 connected to the rotation shaft 82 is rotated. Thereby, the air which flowed in through the air inflow path 12 in the compression part 1 is compressed, and is discharged | emitted from the air discharge path 13 provided in the compression part casing 10a.

  Further, when the compressor 91 is in steady operation, dynamic pressure is generated between the outer peripheral surface 82 a of the rotary shaft 82 and the inner peripheral surfaces 33 a and 43 a of the top foils 33 and 43 as the rotary shaft 82 rotates. appear. Then, the rotary shaft 82 is supported in a non-contact state with the front foil bearing 30 and the rear foil bearing 40 by the air lubrication action by the dynamic pressure. Further, as the impeller 11 rotates, a force (thrust force) acting in the axial direction of the rotating shaft 82 is generated on the rotating shaft 82 as indicated by an outlined arrow. However, the rotating shaft 82 is supported in a non-contact manner in the gap between the axial direction bearing 51 facing the target portion 24 by the magnetic attractive force acting between the axial direction bearing 51 and the target portion 24.

  In the present embodiment, even when vibration of the rotating shaft 82 exceeding the bearing rigidity occurs due to low-speed operation of the rotating shaft 82 or generation of disturbance vibration, the position of the rotating shaft 82 detected by the position sensor 26 is maintained. Accordingly, a part of the air discharged from the air discharge path 13 is supplied from the bypass path 14 connected in the middle of the path of the air discharge path 13 to the inside of the main body of the compressor 91. With this configuration, the air pressure inside the compressor 91 main body becomes higher than 1 atm, and a stronger dynamic pressure is generated between the rotary shaft 82 and the front foil bearing 30 and the rear foil bearing 40. 82, the front foil bearing 30 and the rear foil bearing 40 are in a non-contact state.

  FIG. 2 is a diagram showing the number of rotations (rpm) of the rotating shaft 82 and the distance (μm) between the rotating shaft 82 and the front foil bearing 30 and the rear foil bearing 40. A broken line indicates the distance between the rotary shaft 82 and the front foil bearing 30 and the rear foil bearing 40 under one atmospheric pressure, and a solid line indicates the rotary shaft 82, the front foil bearing 30 and the rear foil bearing under an atmospheric pressure higher than one atmospheric pressure. The distance (clearance) with respect to 40 is shown. If the rotational speed of the rotating shaft 82 is greater than about 15000 rpm under 1 atmosphere, the rotating shaft 82 and the front foil bearing 30 and the rear foil bearing 40 are not in contact with each other, whereas the pressure is higher than 1 atmosphere. Then, the rotation speed of the rotating shaft 82 is about 8000 rpm, and the rotating shaft 82 and the front foil bearing 30 and the rear foil bearing 40 are in a non-contact state. That is, when air having a pressure higher than 1 atm flows from the bypass path 14, the rotary shaft 82 is levitated and supported at a lower rotational speed. Therefore, in the compressor 91 in which the internal pressure is higher than 1 atm, the rotary shaft 82, the front foil bearing 30 and the rear foil bearing 40 can maintain a non-contact state at a lower rotational speed. As a result, the contact frequency between the rotating shaft 82 and the front foil bearing 30 and the rear foil bearing 40 can be suppressed.

According to the compressor 91 according to the above embodiment, the following effects can be obtained.
(1) A bypass path 14 for supplying a part of the air compressed in the compression section casing 10a to the inside of the main body of the compressor 91 is provided in the middle of the path of the air discharge path 13 connected to the compression section casing 10a. Then, a part of the air is supplied from the bypass passage 14 to the inside of the main body of the compressor 91. With such a configuration, the air pressure inside the compressor 91 main body is increased to a pressure higher than 1 atm, and sufficient for the front foil bearing 30 and the rear foil bearing 40 to operate in a non-contact state with the rotary shaft 82. Dynamic pressure can be obtained. As a result, the bearing life can be improved by suppressing the contact frequency between the rotating shaft 82 and the front foil bearing 30 and the rear foil bearing 40. Further, when the compressor 91 is in a steady operation, the air pressure inside the compressor 91 main body can be maintained at 1 atm or more, so that it serves as an air seal and avoids the ingress of water into the compressor 91 main body. be able to.

In addition, you may change the said embodiment as follows.
In the above embodiment, the bypass path 14 for supplying a part of the air compressed in the compression section casing 10a to the inside of the main body of the compressor 91 is in the course of the air discharge path 13 connected to the compression section casing 10a. However, as shown in FIG. 3, a plurality of air discharge passages 13 may be provided in the compression section casing 10a. FIG. 3 is a schematic diagram illustrating another configuration of the compressor 92. With this configuration, in order to supply a part of the air from the plurality of bypass paths 14 to the inside of the main body of the compressor 92, the air pressure inside the main body of the compressor 92 is further increased to 1 atm. The contact frequency with the bearing 30 and the rear foil bearing 40 can be further suppressed.

  -Furthermore, you may make it provide the bypass path 14 in two or more places in the middle of the path | route of the air exhaust path 13. As shown in FIG. With such a configuration, the air pressure inside the main body of the compressor 91 can be made higher than 1 atm, and the contact frequency between the rotary shaft 82 and the front foil bearing 30 and the rear foil bearing 40 can be further suppressed.

  -Moreover, you may make it provide the structure for adjusting the air quantity sent to the inside of the compressor 91 main body from the bypass path 14. FIG. FIG. 4 is a schematic configuration diagram illustrating another configuration of the compressor 93. That is, an adjustment valve 15 for adjusting the amount of air supplied from the bypass path 14 into the compressor 93 main body is provided in the bypass path 14. According to such a configuration, it is possible to adjust the amount of air supplied from the bypass path 14 to the inside of the main body of the compressor 93 to an arbitrary amount, and the front foil bearing 30 and the rear foil bearing 40 are fully functional. In this case, since it is not necessary to supply air from the bypass path 14 to the inside of the main body of the compressor 93, the compressed air can be used efficiently. As a result, cost reduction can be achieved.

In the above embodiment, the configuration of the rotary drive device is as shown in FIG. 1, but the configuration of the rotary drive device is not limited to this, and a rotary drive device having another configuration may be used. .
In the above-described embodiment, the rotary drive device is embodied as a compressor, but may be applied to a rotary drive device that drives a rotary device such as a blower or a turbine.

It is a schematic block diagram which shows the structure of a compressor. It is a figure which shows the relationship between the rotation speed of a rotating shaft, and the distance (clearance) of a rotating shaft and a foil bearing. It is a schematic diagram which shows the other structure of a compressor. It is a schematic block diagram which shows the other structure of a compressor. It is front sectional drawing of the conventional bearing apparatus provided with the magnetic bearing as an axial direction bearing which uses a dynamic pressure gas bearing together and supports a part of rotating shaft to a thrust direction. It is a schematic diagram of a compressor as a conventional rotary drive device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Casing, 11 ... Impeller, 13 ... Air discharge path, 14 ... Bypass path, 15 ... Control valve, 20 ... Drive motor, 22 ... Stator, 23 ... Rotor, 24 ... Target part, 30 ... Front foil bearing, 40 DESCRIPTION OF SYMBOLS ... Rear foil bearing, 50 ... Magnetic bearing, 51 ... Axial direction bearing, 70 ... Radial direction bearing, 80, 110 ... Bearing apparatus, 82 ... Rotating shaft, 82a ... Outer peripheral surface, 91 ... Compressor as a rotational drive apparatus.

Claims (3)

A drive motor comprising a rotor provided integrally with the rotary shaft and a stator fixed to the casing;
A radial bearing having a pair of foil bearings arranged so as to sandwich the drive motor in the axial direction of the rotating shaft;
Axial direction bearing having a magnetic bearing facing the target portion provided on the outer peripheral surface of the rotating shaft and supporting in the axial direction;
In a bearing device comprising an air discharge path for discharging compressed air, wherein an impeller connected to the casing and fixed to an end of the rotating shaft is rotated by the drive motor,
A bearing device that is connected in the middle of the route of the air discharge passage and that forms a bypass route for supplying a part of the compressed air to the inside of the bearing device. A drive motor comprising a rotor provided integrally with the rotary shaft and a stator fixed to the casing;
A radial bearing having a pair of foil bearings arranged so as to sandwich the drive motor in the axial direction of the rotating shaft;
Axial direction bearing having a magnetic bearing facing the target portion provided on the outer peripheral surface of the rotating shaft and supporting in the axial direction;
In a rotary drive device comprising a bearing device comprising an air discharge path for discharging compressed air, wherein an impeller connected to the casing and fixed to an end of the rotary shaft is rotated by the drive motor,
A rotary drive device that is connected in the middle of the route of the air discharge passage and that forms a bypass route for supplying a part of the compressed air to the inside of the bearing device. The rotary drive device according to claim 2, wherein
An adjusting valve for adjusting the amount of the compressed air supplied to the inside of the bearing device is formed in the middle of the bypass route.

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