JP2008240792A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease rotation by inertia or idle running of a rolling bearing used as a touchdown bearing so as to prolong the lifetime. <P>SOLUTION: The rolling bearing used as the touchdown bearing includes an outer ring 32, an inner ring 33 and a resistance applying member 50 for applying resistance to relative rotation of the outer ring 32 and the inner ring 33. The resistance applying member 50 has an urging member 52 attached to the outer ring 32 and a sliding member 51 pressed against the inner ring 33 by the urging force of the urging member 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing that is used together with a magnetic bearing and can function as a touch-down bearing.

For example, a turbo molecular pump uses a configuration in which a rotor shaft provided with rotor blades is supported in a non-contact manner by a magnetic bearing, and an alternative support component for the rotor shaft when the magnetic bearing stops functioning due to a failure or a power failure. The touchdown bearing which consists of a rolling bearing is provided (for example, refer the following patent document 1).
JP 2002-221226 A

When the function of the magnetic bearing is stopped, the touchdown bearing contacts the rotor shaft and rotates at a stroke from the stopped state to the rotational speed of the rotor shaft, and then stops rotating after continuing to rotate by inertia. Since the rotor shaft of the turbo molecular pump rotates at a very high speed, the total number of rotations from when the touchdown bearing starts rotating to when it stops is also very large.
Since the touchdown bearing cannot use lubricating oil due to its usage environment, a coating made of solid lubricant is usually formed on the contact surface between the inner and outer rings and the rolling elements. When the number of the lubricants increases, the solid lubricant film is consumed quickly, and there is a problem that the life of the touchdown bearing is shortened.

  On the other hand, the inner and outer rings and rolling elements of touchdown bearings often use bearing steel such as SUJ2 or stainless steel such as SUS440C, but the rolling elements should be made of ceramic to improve durability. There is also. In this case, when the inner ring of the touch-down bearing is magnetized by the magnetic field generated by the magnetic bearing, the inner ring rotates along with the rotor shaft, and the total number of rotations of the touch-down bearing increases. This also contributes to shortening the life of the touchdown bearing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the rotation and idling due to the inertia of a rolling bearing used as a touchdown bearing or the like, thereby extending the life.

  The present invention includes a first raceway having a first raceway surface, a second raceway having a second raceway surface, and a plurality of rolling elements disposed between the first raceway surface and the second raceway surface. And a resistance applying member that provides resistance to relative rotation between the first and second race rings.

  In addition, the present invention provides a first raceway having a first raceway surface, a second raceway having a second raceway surface, and a plurality of members disposed between the first raceway surface and the second raceway surface. A rolling bearing provided with a rolling element, which is installed together with a magnetic bearing that supports the rotating body in a non-contact manner, and does not contact the rotating body during normal operation of the magnetic bearing; The rolling bearing capable of contacting the rotating body and supporting the rotating body includes a resistance applying member that applies resistance to relative rotation between the first and second race rings.

  According to each said structure, since the rolling bearing of this invention is equipped with the resistance provision member which provides resistance to the relative rotation of a 1st, 2nd bearing ring, it consists of the conventional rolling bearing (it consists of an inner and outer ring, and a rolling element. The rolling resistance is higher than that of a general rolling bearing. Therefore, when this rolling bearing is used as a touch-down bearing, rotation and idling due to inertia can be reduced, and the life of the rolling bearing can be extended.

  The resistance applying member is slid by being pressed against the other of the first and second race rings by the biasing member attached to one of the first and second race rings and the biasing force of the biasing member. And a sliding member. In this case, resistance can be imparted to the relative rotation of the first and second race rings with a simple structure by the sliding resistance between the other of the first and second race rings and the sliding member.

  According to the present invention, it is possible to reduce the rotation and idling due to the inertia of the rolling bearing and to extend the life.

  FIG. 1 is a longitudinal sectional view of a turbo molecular pump that employs a rolling bearing according to an embodiment of the present invention. The turbo molecular pump 10 includes a casing 11, a rotor 12 disposed in the casing 11, magnetic bearings 13 and 14 and touchdown bearings 15 and 16 that rotatably support the rotor 12, and the rotor 12 that rotates at high speed. An electric motor 17 and the like.

  The casing 11 includes an upper casing 20 and a lower casing 21. The upper casing 20 has a cylindrical shape having a vertical axis, and the lower end of the upper casing 20 is closed by a lower casing 21. An intake port 22 is formed at the upper end of the upper casing 20, and an exhaust port 23 is formed at the side. The intake port 22 is covered with a protective net 24. A housing 25 is provided in the upper casing 20, and a magnetic bearing 13, a touchdown bearing 15, and an electric motor 17 are attached to the housing 25.

  The rotor 12 includes a rotor shaft 27 and a blade portion 28. The rotor shaft 27 is disposed in the casing 11 with its axis oriented in the vertical direction. The blade portion 28 includes a plurality of rotor blades 28a spaced in the axial direction, and a stator blade 29 fixed to the casing 11 is disposed in a groove between the upper and lower portions of the rotor blade 28a. A flange disc 30 is provided at the lower end of the rotor shaft 27 so as to be integrally rotatable.

  The magnetic bearings 13 and 14 include two sets of radial magnetic bearings 13 and 13 and a set of axial magnetic bearings 14. The radial magnetic bearing 13 is attached to the housing 25 in the casing 11, and is disposed with a gap on the radially outer side of the rotor shaft 27. The axial magnetic bearing 14 is attached to a housing 39 provided at the lower part of the casing 11 and is disposed so as to sandwich the flange disk 30 of the rotor shaft 27 from both sides in the axial direction with a gap. The rotor shaft 27 is supported by the radial magnetic bearing 13 and the axial magnetic bearing 14 so as to be rotatable in the radial direction and the axial direction in a non-contact state.

  The touchdown bearings 15 and 16 include a deep groove ball bearing 15 disposed on the upper portion of the rotor shaft 27 and an angular ball bearing 16 disposed on the lower portion of the rotor shaft 27. FIG. 2 is an enlarged view of part II in FIG. The deep groove ball bearing 15 is disposed on the inner side in the radial direction of the outer ring 32 having a raceway surface (first raceway surface) 32a on the inner periphery, and on the outer periphery, the raceway surface (second raceway surface). ) 33a and an inner ring (second raceway ring) 33, and a plurality of balls (rolling elements) 34 that are arranged between the inner and outer races 33 and 32 and roll on the raceway surfaces 33a and 32a. . The outer ring 32 is a fixed ring that is fixed to the housing 25, and the inner ring 33 is a rotatable rotating ring, and is disposed with a gap on the outer peripheral side of the rotor shaft 27.

  FIG. 3 is an enlarged view of part III of FIG. As shown in FIG. 3, two angular ball bearings 16 are provided in a front combination arrangement, and can bear an axial load. Each angular ball bearing 16 is disposed on the inner side in the radial direction of an outer ring (first raceway ring) 36 having a raceway surface (first raceway surface) 36a on the inner circumference, and on the outer circumference, the raceway surface (second raceway). Surface) 37a having an inner ring (second raceway ring) 37 and a plurality of balls (rolling elements) 38 which are arranged between the inner and outer rings 37 and 36 and roll on the raceway surfaces 37a and 36a. Yes. The outer ring 36 is a fixed ring fixed to a housing 39 to which the axial magnetic bearing 14 is attached, and the inner ring 37 is a rotatable rotating ring, and is disposed with a gap on the outer peripheral side of the rotor shaft 27. Yes.

  The materials used for the inner and outer rings 33, 32, 37, 36 and the balls 34, 38 of the deep groove ball bearing 15 and the angular ball bearing 16 are bearing steels such as JIS standard SUJ2 and martensitic stainless steels such as JIS standard SUS440C. And precipitation hardening type stainless steel such as JIS standard SUS630. The balls 34 and 38 may be made of a ceramic material such as silicon nitride, silicon carbide, zirconia, or alumina. A coating 40 of a solid lubricant such as molybdenum disulfide or graphite is provided on the surfaces of the raceway surfaces 33a, 32a, 37a, 36a and balls 34, 38 of the inner and outer rings 33, 32, 37, 36.

  As shown in FIG. 2, the deep groove ball bearing 15 includes a resistance applying member 50 that provides resistance to relative rotation between the outer ring 32 and the inner ring 33 in addition to the inner and outer rings 33 and 32 and the ball 34. The resistance imparting member 50 is disposed below the ball 34 of the deep groove ball bearing 15, and is slidable in contact with the outer circumferential surface of the inner ring 33, and the sliding member 51 is disposed on the outer circumferential surface of the inner ring 33. And a biasing member 52 that presses against the outer peripheral surface. The sliding member 51 is formed of a substantially rectangular parallelepiped block, and is formed of a self-lubricating material such as carbon. Moreover, what formed the film of solid lubricants, such as molybdenum disulfide, on the surface of carbon blocks or metal blocks can also be used. A synthetic resin material can also be used as the sliding member 51.

  4 is a perspective view showing a part of the resistance applying member 50, and FIG. 5 is a view taken in the direction of arrow V in FIG. FIG. 6 is a schematic front view of the resistance applying member 50. The urging member 52 includes a ring-shaped attachment ring (attachment member) 54 attached to the outer ring 32 and a plurality of (eight in the example of FIG. 6) provided on the radial inner side of the attachment ring 54 in the circumferential direction. ) And a fixing tool 56 for fixing the sliding member 51 to each spring body 55. The mounting ring 54 is formed of a metal material such as spring steel, and as shown in FIG. 2, the fitting portion 54a fitted to the inner peripheral surface of the outer ring 32, and radially outward from one end of the fitting portion 54a. The flange portion 54b extends and contacts the lower end surface of the outer ring 32, and is formed in an L-shaped cross section. The attachment ring 54 is fixed to the outer ring 32 by being fitted to the outer ring 32 or fixed by welding or the like.

  As shown in FIG. 4, the spring body 55 is configured by a front-view mountain-shaped plate spring whose inner side in the radial direction is the top, one end of which is connected to the fitting portion 54 a of the mounting ring 54, and the other end. It is a free end. More specifically, as shown in FIGS. 4 and 5, the spring body 55 is formed by raising the fitting portion 54 a of the attachment ring 54 in a band shape. The top of the spring body 55 constitutes a fixing tool 56 and is provided with four support columns 56a projecting radially inward in a square arrangement, and the sliding member 51 is fitted and fixed to the support columns 56a. Has been.

  As shown in FIG. 3, the angular ball bearing 16 also includes a resistance applying member 50 having a similar configuration. Specifically, the resistance imparting member 50 is provided below the ball 38 of the angular ball bearing 16 disposed on the lower side of the two angular ball bearings 16.

  As shown in FIG. 1, the turbo molecular pump 10 rotates the rotor 12 at a high speed by operating the electric motor 17 with the rotor 12 supported in a non-contact manner by magnetic bearings 13 and 14. When the magnetic bearings 13 and 14 become uncontrollable due to a failure or the like, the inner rings 33 and 37 of the touchdown bearings 15 and 16 come into contact with the rotor shaft (rotating body) 27 and function as bearings. The bearings 13 and 14 are protected. When the rotor shaft 27 that rotates at high speed comes into contact with the inner rings 33 and 37 of the touchdown bearings 15 and 16, the inner rings 33 and 37 follow the rotor shaft 27 and rotate at a high speed, and then inertia (inertia) until natural stop. ) Continue to rotate.

  In the present embodiment, since the sliding member 51 of the resistance applying member 50 is pressed against the inner rings 33 and 37, the sliding member 51 slides on the inner rings 33 and 37, and the inner ring 33 is caused by the sliding resistance of both. , 37 and the outer rings 32, 36 are resisted by relative rotation. Therefore, the rotation due to the inertia of the touchdown bearings 15 and 16 can be reduced, and the wear of the coating film 40 of the solid lubricant provided on the inner and outer rings 33, 32, 37, 36 and the balls 34, 38 is reduced as much as possible. The life of the touchdown bearings 15 and 16 can be extended (that is, the number of times that the touchdown can be performed is increased). When the ceramic balls 34 and 38 are used, the inner rings 33 and 37 may rotate along with the rotor shaft 27 due to the magnetic field generated by the magnetic bearings 13 and 14, but the resistance applying member 50 may Such idling can also be prevented.

  When the balls 34 and 38 are ferromagnetic materials such as bearing steel, the balls 34 and 38 themselves are magnetized by the magnetic field generated by the magnetic bearings 13 and 14 and magnetically attract the inner rings 33 and 37. , 37 are reduced in idling. Therefore, the resistance imparting member 50 according to the present embodiment is a rolling bearing using balls 34, 38 such as ceramics which are non-magnetic materials, and the rolling bearing in which the inner rings 33, 37 are easy to idle due to magnetization. It is more effective. The resistance applying member 50 is also useful for preventing play between the inner and outer rings 33, 32, 37, 36.

When self-lubricating carbon is used as the material of the sliding member 51 of the resistance applying member 50, wear of the inner rings 33, 37 due to contact (sliding) between the sliding member 51 and the inner rings 33, 37 is prevented. be able to. Further, the same effect can be obtained by providing a solid lubricant film on the surface of the sliding member 51.
The spring body 55 can be easily formed by cutting and raising a part of the attachment ring 54. However, the spring body 55 may be formed by a member different from the attachment ring 54 and fixed to the attachment ring 54 by welding or the like.

The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate. In the above embodiment, the spring body 55 of the urging member 52 is configured by a metal leaf spring, but may be configured by a coil spring or the like. It can also be constituted by an elastic body such as rubber or synthetic resin. Further, the shapes and materials of the biasing member 52 and the sliding member 51 are not limited to the above embodiment.
The resistance applying member 50 can be provided on the upper side of the ball 34 in FIG. 2, or can be provided on the upper angular ball bearing 16 in FIG. 3. In the above-described embodiment, the urging member 52 is attached to the outer rings 32 and 36 that are fixed wheels, and the sliding member 51 is brought into contact with the inner rings 33 and 37 that are rotating wheels, but the reverse is also possible. . Further, the rolling bearings 15 and 16 may be ones in which the outer rings 32 and 36 are rotating wheels and the inner rings 33 and 37 are fixed rings.

The number of sliding members 51 and urging members 52 constituting the resistance applying member 50 can be changed as appropriate, and can be one each. However, it is preferable to arrange a plurality of sliding members 51 and urging members 52 at equal intervals in the circumferential direction.
The rolling bearing of the present invention is not limited to the touchdown bearing used together with the magnetic bearings 13 and 14, but can be used for other purposes, for example, when it is desired to increase the torque of the rolling bearing. Further, the rolling bearing of the present invention is not limited to a deep groove ball bearing and an angular ball bearing, and can be configured as other ball bearings or roller bearings.

It is a longitudinal cross-sectional view of the turbo-molecular pump to which the rolling bearing concerning embodiment of this invention is applied. It is the II section enlarged view of FIG. It is the III section enlarged view of FIG. It is a one part perspective view of a resistance provision member. FIG. 3 is a view taken in the direction of arrow V in FIG. 2. It is a schematic front view of a resistance provision member.

Explanation of symbols

13 Radial magnetic bearing 14 Axial magnetic bearing 15 Touchdown bearing (deep groove ball bearing)
16 Touchdown bearings (angular ball bearings)
32, 36 Outer ring 33, 37 Inner ring 34, 38 Ball (rolling element)
50 Resistance imparting member 51 Sliding member 52 Biasing member

Claims (3)

A first raceway having a first raceway surface; a second raceway having a second raceway surface; and a plurality of rolling elements disposed between the first raceway surface and the second raceway surface. In rolling bearings
A rolling bearing comprising a resistance imparting member that imparts resistance to relative rotation between the first race and the second race. A first raceway having a first raceway surface; a second raceway having a second raceway surface; and a plurality of rolling elements disposed between the first raceway surface and the second raceway surface. The rolling bearing is installed together with a magnetic bearing that supports the rotating body in a non-contact manner, and does not contact the rotating body during normal operation of the magnetic bearing, and contacts the rotating body when the magnetic bearing is not operating. In a rolling bearing capable of supporting the rotating body,
A rolling bearing comprising a resistance imparting member that imparts resistance to relative rotation between the first race and the second race.   An urging member attached to one of the first and second race rings, and a sliding slide that is pressed against the other of the first and second race rings by the urging force of the urging member. The rolling bearing according to claim 1, further comprising a moving member.

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