JP2021025531A - Bearing device - Google Patents

Abstract

To provide a bearing device capable of achieving improvement in durability performance.SOLUTION: A rotary shaft 21 includes a hollow part 25 which has a cylindrical shape and which deforms so as to bulge outwardly during rotation. A rolling bearing 11 is arranged in a state of having a gap between an outer peripheral surface of the rotary shaft 21 and itself. At the rotation stop time of the rotary shaft 21, a lower part of the rolling bearing 11 comes into contact with the rotary shaft 21, and an upper part of the rolling bearing 11 does not come into contact with the rotary shaft 21. A foil bearing 12 includes: a top foil 40 which has a shape along an outside surface of the hollow part 25 when the hollow part 25 deforms at the rotation time of the rotary shaft 21, and which is oppositely arranged on the outer peripheral surface in such a manner that it does not come into contact with the outer peripheral surface of the hollow part 25; and a bump foil 41 for energizing the top foil 40 to the rotary shaft 21 side. The foil bearing 12 has a housing 43 for supporting the outer peripheral side of the bump foil 41.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bearing device having a foil bearing that supports a rotating shaft in the radial direction by utilizing air pressure.

The foil bearing described in Patent Document 1 has a tubular top foil arranged on the outer circumference of a rotating shaft and a mountain portion extending along the outer peripheral surface of the top foil and protruding toward the top foil in the circumferential direction. It has a wavy bump foil that is lined up at intervals and a housing that supports the outer peripheral surface of the bump foil.

In the foil bearing, when the rotation of the rotating shaft is stopped, the outer peripheral surface of the rotating shaft and the inner peripheral surface of the top foil are in contact with each other. Then, when the rotation of the rotating shaft is started, air invades between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the top foil to form an air film. At this time, the top foil is deformed to the outer peripheral side in a manner in which the diameter is expanded, so that the rotating shaft rises from the top foil. In this way, the rotating shaft is supported in a non-contact state.

Further, in the foil bearing, the outer peripheral surface of the top foil is elastically supported by the bump foil. When the rotation speed of the rotating shaft increases, the air pressure in the gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the top foil increases, so that the amount of elastic deformation of the bump foil in the compression direction increases, and the top foil The amount of deformation to the outer peripheral side also increases. In this way, in the foil bearing, the clearance is automatically adjusted so that the clearance between the rotating shaft and the top foil increases as the rotational speed of the rotating shaft increases.

JP-A-2002-61645

Due to the structure of the foil bearing, the rotating shaft and the top foil are slid at the start of rotation of the rotating shaft or at a low speed. This causes wear of the top foil and the rotating shaft, which in turn causes deterioration of the durability performance of the bearing device.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a bearing device capable of improving durability performance.

The bearing device for solving the above problems is a bearing device that supports the rotating shaft in the radial direction by a rolling bearing and a foil bearing, and the rotating shaft has a tubular shape and bulges outward during rotation. The rolling bearing has a hollow portion having a deformable structure, and the rolling bearing is arranged around a portion of the rotating shaft other than the hollow portion with a gap between the rotating shaft and the outer peripheral surface of the rotating shaft. The structure is such that the lower part of the rolling bearing comes into contact with the rotating shaft and the upper part of the rolling bearing does not come into contact with the rotating shaft when the rotation of the shaft is stopped, and the foil bearing has the structure when the rotating shaft is rotated. A facing portion that has a shape along the outer surface of the hollow portion when the hollow portion is deformed and is arranged to face the outer peripheral surface of the hollow portion so as not to contact the outer peripheral surface of the hollow portion, and the facing portion on the rotation shaft side. It has a spring portion for urging the spring portion and a housing for supporting a portion on the outer peripheral side of the spring portion.

In the above configuration, when the rotation of the rotating shaft is stopped or at a low speed, the hollow portion is not deformed, or the amount of deformation of the hollow portion is small, so that the outer peripheral surface of the rotating shaft and the facing portion of the foil bearing The gap becomes large. At this time, the foil bearing does not function as a bearing for supporting the rotating shaft in the radial direction. However, at this time, since the rotating shaft moves downward to a position where it comes into contact with the rolling bearing due to its own weight and is eccentric, the rotating shaft is rotatably supported by the rolling bearing in that state. As described above, according to the above configuration, when the rotating shaft is stopped or rotated at a low speed, the rotating shaft is rotatably supported by a rolling bearing so that the rotating shaft and the facing portion of the foil shaft are in a non-contact state. Therefore, it is possible to suppress wear of the facing portion of the foil bearing and the rotating shaft.

When the rotating shaft rotates at high speed, the centrifugal force acting on the hollow portion deforms the hollow portion so as to bulge outward, and the gap between the outer peripheral surface of the rotating shaft and the facing portion of the foil bearing becomes moderately small. .. At this time, a dynamic pressure (air film) is generated in the gap between the facing portion of the foil bearing and the outer peripheral surface of the rotating shaft, and the foil bearing operates in a non-contact state.

Moreover, since the dynamic pressure generated in the gap at this time causes the rotating shaft to move to a regular position where the rotating shaft is not eccentric, there is a gap in the entire portion where the outer peripheral surface of the rotating shaft and the inner surface of the rolling bearing face each other. It will be formed. As a result, the rolling bearing does not function as a bearing for supporting the rotating shaft in the radial direction.

As described above, according to the above configuration, when the rotating shaft rotates at high speed, the rotating shaft is rotatably supported by the foil bearing, so that the rotating shaft and the rolling bearing are brought into a non-contact state and the rolling bearing is put into a non-operating state. Therefore, it is possible to improve the durability performance of the rolling bearing.

According to the present invention, the durability performance of the bearing device can be improved.

The front end view of the bearing device of one embodiment. A cross-sectional view of the bearing device along line 2-2 of FIG. A front sectional view of the hollow portion of the rotating shaft and its periphery during high-speed rotation. A side sectional view showing a state of a rolling bearing at the time of rotation stop and at low speed rotation. A side sectional view showing a state of a rolling bearing at the time of high-speed rotation. An exploded perspective view of a foil bearing. The side end view which shows the state of the foil bearing at the time of a rotation stop and a low speed rotation. Side end view showing the state of the foil bearing at the time of high-speed rotation.

Hereinafter, an embodiment of the bearing device will be described.
As shown in FIGS. 1 and 2, the bearing device of the present embodiment includes a rolling bearing 11 and a foil bearing 12. The rotating shaft 21 of the electric motor 20 to be supported by the rolling bearing 11 and the foil bearing 12 is supported in the radial direction. In the present embodiment, a bearing portion 13 including a rolling bearing 11 and a foil bearing 12 is provided in the case 22 of the electric motor 20. The bearing portions 13 are separately provided at positions spaced apart from each other in the axial direction of the rotating shaft 21, specifically, at positions sandwiching the stator 23 and rotor 24 of the electric motor 20.

Hereinafter, the specific structure of the bearing portion 13 will be described. Since the basic structures of the two bearing portions 13 are the same, each portion of the bearing portion 13 is designated by the same reference numeral. In the following, only the basic structure of one bearing portion 13 will be described and the other bearing portion will be described. The description of the basic structure of 13 will be omitted.

The rotating shaft 21 of the electric motor 20 has a columnar shape whose outer surface extends with the same diameter. The rotor 24 of the electric motor 20 is integrated with the central portion of the rotating shaft 21 in the axial direction. Specifically, the central portion of the rotating shaft 21 includes a central shaft portion 24A formed of a magnetic material such as an iron alloy, and a cylindrical intermediate layer 24B composed of permanent magnets arranged so as to cover the outer periphery of the central shaft portion. It has a three-layer structure composed of a cylindrical outer layer 24C made of carbon fiber resin arranged so as to cover the outer periphery of the intermediate layer 24B.

Further, both end portions of the rotating shaft 21 in the axial direction are hollow portions 25 having a hollow structure. The hollow portion 25 is composed of a cylindrical peripheral wall 25A and a lid wall 25B that closes both openings in the cylindrical shape. The hollow portion 25 and the peripheral portion thereof in the rotating shaft 21 are formed of an aluminum alloy. In the present embodiment, the hollow portion 25 corresponds to a portion of each portion of the rotating shaft 21 supported by the foil bearing 12.

As shown in FIG. 3, the hollow portion 25 is deformed into a barrel shape by the centrifugal force acting on the peripheral wall 25A during high-speed rotation of the rotating shaft 21 so that the central portion of the peripheral wall 25A in the axial direction bulges outward. It has a structure of In FIG. 3, in order to facilitate understanding of the deformation mode of the peripheral wall 25A of the hollow portion 25, the deformation amount of the peripheral wall 25A is exaggerated from the actual deformation amount (for example, 100 μm).

As shown in FIGS. 2, 4 and 5, the rolling bearing 11 is composed of three bearing portions 30. Each bearing portion 30 is composed of a support shaft 31 erected in the case 22 so as to extend in the axial direction, and an annular ball bearing 32 rotatably supported by the support shaft 31. The bearing portions 30 are arranged so as to be arranged at equal intervals around a portion of the rotating shaft 21 sandwiched between the rotor 24 and the hollow portion 25.

Each bearing portion 30 is arranged in such a manner that a gap is formed between the outer peripheral surface of at least one of the three ball bearings 32 and the outer peripheral surface of the rotating shaft 21. Specifically, as shown in FIG. 4, when the rotation of the rotating shaft 21 is stopped, the two ball bearings 32 arranged below are in contact with the outer peripheral surface of the rotating shaft 21 and are arranged above. The remaining one ball bearing 32 is not in contact with the rotating shaft 21. Further, as shown in FIG. 5, at the time of high-speed rotation of the rotating shaft 21, all the ball bearings 32 are in a state of not contacting the outer peripheral surface of the rotating shaft 21. In FIGS. 4 and 5, in order to facilitate understanding of the support state of the rotating shaft 21 by the rolling bearing 11, the gap between each bearing portion 30 and the rotating shaft 21 is larger than the actual gap (for example, 100 μm). Exaggerated.

As shown in FIGS. 1 and 6, the foil bearing 12 is arranged around the hollow portion 25 of the rotating shaft 21.
The foil bearing 12 has a top foil 40 as an opposing portion arranged to face the outer peripheral surface of the hollow portion 25 of the rotating shaft 21, and a spring portion arranged on the outer periphery of the top foil 40 to elastically support the top foil 40. It is equipped with a bump foil 41 as a. Further, the foil bearing 12 includes a cylindrical housing 43 that is arranged on the outer periphery of the bump foil 41 and supports the outer peripheral surface of the bump foil 41. An annular ring portion 45 is provided on the inner edges of both openings of the housing 43. The housing 43 is fixed inside the case 22 so as to extend in the axial direction. The foil bearing 12 has a structure in which a top foil 40 and a bump foil 41 are arranged between the outer peripheral surface of the rotating shaft 21 and the inner peripheral surface of the housing 43.

The top foil 40 is formed by rolling a flexible metal plate material such as stainless steel into a tubular shape. One end 40A in the circumferential direction of the top foil 40 is a holding end, and the other end 40B in the circumferential direction is a free end. The one end portion 40A projects outward in the radial direction and is inserted into the concave groove 44 formed on the inner peripheral surface of the housing 43. The other end 40B has a gap between it and the one end 40A in the circumferential direction. In the present embodiment, when the rotation of the rotating shaft 21 is stopped, the outer peripheral surface of the rotating shaft 21 and the inner peripheral surface of the top foil 40 do not come into contact with each other.

The bump foil 41 is formed by rolling a flexible metal plate material such as stainless steel into a tubular shape. The bump foil 41 extends along the outer peripheral surface of the top foil 40. The bump foil 41 has a wavy shape in which mountain portions protruding toward the top foil 40 are arranged at intervals in the circumferential direction. In the foil bearing 12, each mountain portion of the bump foil 41 is supported on the inner peripheral surface of the housing 43, and each mountain portion of the bump foil 41 is supported on the outer peripheral surface of the top foil 40. The top foil 40 is elastically supported by abutting against the surface.

One end 41A of the bump foil 41 in the circumferential direction is a holding end, and the other end 41B in the circumferential direction is a free end. The one end portion 41A projects outward in the radial direction and is inserted into the concave groove 44 of the housing 43 in a state of being overlapped with the one end portion 40A of the top foil 40. Therefore, one end 40A of the top foil 40 and one end 41A of the bump foil 41 are inserted in the concave groove 44 in a superposed state. As a result, the top foil 40 and the bump foil 41 are held in the housing 43 in a detented state. A gap in the circumferential direction is formed between one end 41A and the other end 41B of the bump foil 41.

In the present embodiment, as shown in FIG. 3, the hollow portion 25 of the rotating shaft 21 is deformed in a barrel shape during rotation. In the present embodiment, the inner peripheral surfaces of the top foil 40, the bump foil 41, and the housing 43 are all along the outer surface of the hollow portion 25 when the hollow portion 25 is deformed during high-speed rotation of the rotating shaft 21. The shape, specifically, the central portion in the axial direction is a barrel shape that bulges outward.

Hereinafter, the operation of the bearing device of this embodiment will be described.
When the rotation of the rotating shaft 21 is stopped, no dynamic pressure (air film) is generated inside the foil bearing 12. Further, at the time of low-speed rotation of the rotating shaft 21, although dynamic pressure is generated inside the foil bearing 12, the dynamic pressure is low. Therefore, when the rotation of the rotating shaft 21 is stopped or at a low speed, the foil bearing 12 does not function as a bearing for supporting the rotating shaft 21 in the radial direction.

As shown in FIGS. 1 and 7, when the rotation of the rotating shaft 21 is stopped, the centrifugal force does not act on the peripheral wall 25A of the hollow portion 25 of the rotating shaft 21, so that the peripheral wall 25A of the hollow portion 25 is not deformed. Further, when the rotating shaft 21 is rotating at a low speed, the centrifugal force acting on the peripheral wall 25A of the hollow portion 25 of the rotating shaft 21 is small, so that the amount of deformation of the peripheral wall 25A of the hollow portion 25 is small. When the rotation of the rotating shaft 21 is stopped or at a low speed, the gap between the outer peripheral surface of the rotating shaft 21 and the top foil 40 of the foil bearing 12 becomes large. In FIG. 7, the gap between the top foil 40 and the rotating shaft 21 is exaggerated from the actual gap in order to facilitate understanding of the support state of the rotating shaft 21 by the foil bearing 12.

At this time, the rotating shaft 21 moves downward to a position where it comes into contact with the two ball bearings 32 below the rolling bearing 11 due to its own weight and is eccentric, and in that state, it is rotatably supported by the rolling bearing 11. .. As described above, according to the present embodiment, when the rotating shaft 21 is stopped or rotated at a low speed, the rotating shaft 21 is rotatably supported by the rolling bearing 11 so that the rotating shaft 21 and the top foil 40 of the foil bearing 12 are rotatably supported. Can be in a non-contact state. As a result, wear of the top foil 40 and the rotating shaft 21 can be suppressed.

In the present embodiment, since the hollow portion 25 of the rotating shaft 21 bulges outward as the rotating shaft 21 rotates, the rotating shaft 21 of the rotating shaft 21 when the rotation is stopped or at a low speed. The gap between the hollow portion 25 and the top foil 40 of the foil bearing 12 can be increased. As a result, the rotating shaft 21 moves from the normal rotation center while maintaining the above-mentioned structure when the rotating shaft 21 stops rotating or rotating at a low speed, that is, the outer peripheral surface of the rotating shaft 21 does not contact the top foil 40 of the foil bearing 12. A structure in which the rolling bearing 11 is supported in an eccentric state can be easily realized.

On the other hand, as shown in FIG. 3, when the rotating shaft 21 is rotating at high speed, the peripheral wall 25A of the hollow portion 25 of the rotating shaft 21 is deformed so as to bulge outward due to the centrifugal force acting on the peripheral wall 25A of the hollow portion 25. To do. Along with this, as shown in FIGS. 1 and 8, the gap between the outer peripheral surface of the rotating shaft 21 and the top foil 40 of the foil bearing 12 is such that a dynamic pressure (air film) can be formed between them. It becomes smaller. Then, at this time, the dynamic pressure generated in the gap between the top foil 40 of the foil bearing 12 and the outer peripheral surface of the rotating shaft 21 causes the foil bearing 12 to operate in a non-contact state. In FIG. 8, in order to facilitate understanding of the support state of the rotating shaft 21 by the foil bearing 12, the amount of deformation of the hollow portion 25 and the gap between the top foil 40 and the rotating shaft 21 are exaggerated from the actual values. Is shown.

Moreover, as shown in FIG. 5, the dynamic pressure generated in the gap at this time causes the rotating shaft 21 to move to a regular position where it is not eccentric. Therefore, the outer peripheral surface of the rotating shaft 21 and the rolling bearing 11 are three. A gap is formed between each of the ball bearings 32. Therefore, at this time, the rolling bearing 11 does not function as a bearing for supporting the rotating shaft 21 in the radial direction. As described above, according to the present embodiment, when the rotating shaft 21 rotates at high speed, the rotating shaft 21 is rotatably supported by the foil bearing 12 so that the rotating shaft 21 and the rolling bearing 11 are brought into a non-contact state and rolled in the same manner. The bearing 11 can be inactive. Therefore, the durability performance of the rolling bearing 11 can be improved.

In the present embodiment, the rotation speed of the rotating shaft 21 that switches from the state in which the rolling bearing 11 functions as a bearing to the state in which it does not function, that is, only the foil bearing 12 of the foil bearing 12 and the rolling bearing 11 is a bearing. The shape and deformation characteristics of each part of the bearing device are adjusted so that the rotational speed of the rotating shaft 21 that switches to the functioning state is a value in the speed range in which the ball bearing 32 of the rolling bearing 11 is maintained with high reliability. It is fixed. As a result, although the rolling bearing 11 is provided to rotatably support the rotating shaft 21 at low speed rotation in which the foil bearing 12 does not function as a bearing, the rotating shaft 21 allows the foil bearing 12 to function sufficiently. It becomes possible to suppress a decrease in reliability of the rolling bearing 11 at the time of high-speed rotation.

As described above, according to the present embodiment, it is possible to improve the durability performance of the bearing device having the foil bearing 12.
In the present embodiment, when the rotating shaft 21 is rotated at high speed, the hollow portion 25 is deformed in a barrel shape. Further, the top foil 40 of the foil bearing 12 has a barrel shape. Therefore, when the rotating shaft 21 is rotating at high speed, as shown in FIG. 8, the peripheral wall 25A of the hollow portion 25 of the rotating shaft 21 having an outwardly convex shape is also an outwardly convex foil bearing 12. It will fit in the top foil 40. As a result, the axial position of the hollow portion 25 of the rotating shaft 21 with respect to the top foil 40 of the foil bearing 12 is regulated, so that the positional deviation of the rotating shaft 21 in the axial direction can be suppressed.

Here, in the present embodiment, when the rotating shaft 21 is rotating at a low speed, the rotating shaft 21 has a rolling bearing 11 with a gap between the outer peripheral surface of the rotating shaft 21 and the inner surface of the ball bearing 32 of the rolling bearing 11. Rotatably supported by. Therefore, in the bearing device of the present embodiment, the rotating state of the rotating shaft 21 is unstable as compared with the bearing device having a structure in which the rotating shaft is supported by the rolling bearing in a state where there is no gap between the rotating shaft and the rolling bearing. It can be said that it is easy to become.

In this regard, in the present embodiment, as shown in FIG. 1, the bearing portions 13 including the rolling bearing 11 and the foil bearing 12 are located at positions spaced apart from each other in the axial direction of the rotating shaft 21, specifically, the rotor 24 of the electric motor 20. Each is separately provided at a position sandwiched between them. As a result, the bearing device can have a double-sided structure in which the rotating shaft 21 is supported by two bearing portions 13, so that the rotating shaft has a cantilever structure in which the rotating shaft is supported by one bearing portion. 21 can be supported in a stable state.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) When the rotating shaft 21 stops rotating or rotates at a low speed, the rotating shaft 21 is rotatably supported by the rolling bearing 11 so that the rotating shaft 21 and the top foil 40 of the foil bearing 12 are in a non-contact state. Therefore, wear of the top foil 40 and the rotating shaft 21 can be suppressed. Moreover, when the rotating shaft 21 rotates at high speed, the rotating shaft 21 is rotatably supported by the foil bearing 12 so that the rotating shaft 21 and the rolling bearing 11 are brought into a non-contact state and the rolling bearing 11 is put into a non-operating state. Therefore, it is possible to improve the durability performance of the rolling bearing 11. Therefore, according to the present embodiment, it is possible to improve the durability performance of the bearing device having the foil bearing 12.

(2) The hollow portion 25 has a structure that deforms in a barrel shape when the rotating shaft 21 rotates at high speed. As a result, when the rotating shaft 21 is rotating at high speed, the peripheral wall 25A of the hollow portion 25 of the rotating shaft 21 which is convex outward is fitted into the top foil 40 of the foil bearing 12 which is also convex outward. Therefore, the positional deviation of the rotating shaft 21 in the axial direction can be suppressed.

(3) Bearing portions 13 including rolling bearings 11 and foil bearings 12 are separately provided at positions sandwiching the rotor 24 of the electric motor 20. Therefore, the rotating shaft 21 can be supported by the two bearing portions 13 in a stable state.

The above embodiment can be modified and implemented as follows. The above embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

The hollow portion 25 of the rotating shaft 21 may be formed of a synthetic resin material.
-Instead of the ball bearing 32, another rolling bearing such as a roller bearing can be adopted.

The shape of the bump foil 41 and the shape of the inner peripheral surface of the housing 43 can be arbitrarily changed as long as the top foil 40 can be supported in a state of being urged toward the rotating shaft 21 side.

-The shape of the hollow portion 25 when the rotation is stopped may be a barrel shape. Even with this configuration, the gap between the outer peripheral surface of the rotating shaft 21 and the top foil 40 of the foil bearing 12 can be increased when the rotating shaft 21 is stopped or at low speed, and when the rotating shaft 21 is rotating at high speed. In, the gap between the outer peripheral surface of the rotating shaft 21 and the top foil 40 of the foil bearing 12 can be made small enough to form an air film between them.

-The shape of the hollow portion when the rotation is stopped may be a drum shape with a concave center in the axial direction. In this case, the top foil of the foil bearing may have a shape along the outer surface of the hollow portion of the rotating shaft when the hollow portion of the rotating shaft is deformed, such as a drum shape or a cylindrical shape extending with the same diameter. ..

The hollow portion 25 may be formed in a cylindrical shape in which one of both ends of the rotating shaft 21 in the axial direction is open. In the same configuration, the hollow portion of the rotating shaft 21 does not have a barrel shape at the time of high-speed rotation, but has a shape in which the diameter increases toward the end in the axial direction, that is, a so-called funnel shape. In such a configuration, the shape of the top foil of the foil bearing may be a shape along the outer surface of the hollow portion of the rotating shaft when the hollow portion is deformed, specifically, a funnel shape.

-Only one bearing portion 13 including the rolling bearing 11 and the foil bearing 12 may be provided.
-The bearing device of the above embodiment is not limited to a bearing device having a foil bearing provided with a bump foil as a spring member, but also a bearing device having a foil bearing provided with a spring portion such as a leaf spring member or a metal mesh member. Can be applied.

-The bearing device of the above embodiment can also be applied to a bearing device having a leaf type foil, that is, a foil bearing provided with a plurality of so-called leaf foils. In the same configuration, the free end of each leaf foil, that is, the portion facing the outer peripheral surface of the rotating shaft corresponds to the facing portion, and the portion on the fixed end side of each leaf foil, that is, the portion on the housing side corresponds to the spring portion. ..

-The structure of the stator and rotor 24 of the electric motor 20 can be arbitrarily changed.
-The bearing device of the above embodiment can also be applied to a bearing device whose axis is a rotating shaft other than the rotating shaft of the electric motor.

11 ... Rolling bearing, 12 ... Foil bearing, 13 ... Bearing part, 20 ... Electric motor, 21 ... Rotating shaft, 22 ... Case, 23 ... Stator, 24 ... Rotor, 24A ... Central shaft part, 24B ... Intermediate layer, 24C ... Outer layer , 25 ... hollow part, 25A ... peripheral wall, 25B ... lid wall, 30 ... bearing part, 31 ... support shaft, 32 ... ball bearing, 40 ... top foil, 40A ... one end, 40B ... other end, 41 ... bump foil , 41A ... one end, 41B ... the other end, 43 ... housing, 44 ... concave groove, 45 ... ring part.

Claims (4)

A bearing device that supports the rotating shaft in the radial direction by rolling bearings and foil bearings.
The rotating shaft has a hollow portion having a tubular shape and a structure that deforms so as to bulge outward during rotation.
The rolling bearing is arranged in a state where there is a gap between the rolling bearing and the outer peripheral surface of the rotating shaft around a portion other than the hollow portion of the rotating shaft, and when the rotation of the rotating shaft is stopped, the lower portion of the rolling bearing is placed. The structure is such that the upper part of the rolling bearing does not come into contact with the rotating shaft while in contact with the rotating shaft.
The foil bearing has a shape along the outer surface of the hollow portion when the hollow portion is deformed during rotation of the rotating shaft, and is arranged so as to face the outer peripheral surface of the hollow portion so as not to contact the outer peripheral surface of the hollow portion. A bearing device having a facing portion, a spring portion that urges the facing portion toward the rotating shaft side, and a housing that supports a portion on the outer peripheral side of the spring portion. The bearing device according to claim 1, wherein the hollow portion has a structure that deforms in a barrel shape when rotating. The facing portion is a barrel-shaped top foil arranged on the outer circumference of the rotating shaft.
The second aspect of claim 2, wherein the spring portion is a bump foil having a wave shape extending along the outer peripheral surface of the top foil and having mountain portions protruding toward the top foil side at intervals in the circumferential direction. Bearing equipment. The bearing device according to any one of claims 1 to 3, wherein bearing portions including the rolling bearing and the foil bearing are separately provided at positions spaced apart from each other in the axial direction of the rotating shaft.