JP2017133640A - Touchdown bearing and rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touchdown bearing capable of preventing a service life from shortening caused by wearing out of a plurality of balls at the time other than the time of touchdown, and to provide a rotary machine.SOLUTION: A touchdown bearing includes a position adjustment member 44 configured to deviate a position of an inner ring 46, which sections a first recess part 46B, to a position of an outer ring 48, which sections a second recess part 48A, in an axial direction of a rotary member so as to hold a ball 51 with the inner ring 46 and the outer ring 48 at the time other than a time of touchdown, in a state where the ball 51 can rotate at the time of touch down in a space formed between the first and second recess parts 46B, 48A.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a touchdown bearing that rotatably supports a rotating member at the time of touchdown, and a rotary machine including the touchdown bearing.

2. Description of the Related Art Conventionally, a rotary machine including a rotating member (for example, a rotating shaft) that rotates has a touchdown bearing together with a magnetic bearing. The touchdown bearing is provided on the outer periphery of the rotating member in a non-contact state with the rotating member. Touchdown bearings are usually arranged at both ends of the rotating member.
The touchdown bearing does not contact the rotating member when the magnetic bearing is normal, but when the magnetic bearing becomes uncontrollable due to some trouble (in other words, when the rotating member contacts a member other than the magnetic bearing (hereinafter, "At the time of touchdown")), it contacts the rotating member and functions as a bearing. Thereby, it becomes possible to protect a magnetic bearing and a rotating member from damage, such as baking.

The touch-down bearing is generally ring-shaped and includes an inner ring including a first recess in which a part of a plurality of rotating balls is accommodated, and a ring-shaped part of the plurality of rotating balls is accommodated. An outer ring including a second recessed portion, a plurality of balls disposed between the inner ring and the outer ring, and a cage disposed between the inner ring and the outer ring and rotatably holding the plurality of balls. Have.
The outer ring is disposed outside the inner ring in a state of being separated from the inner ring. The outer ring is arranged to face the inner ring so that the first recess and the second recess face each other.

  By the way, in the case of the touchdown bearing having the above-described configuration, a phenomenon in which the touchdown bearing that is not in contact with the rotating member is idle due to the influence of magnetism generated from the magnetic bearing in a normal state (in other words, a plurality of balls rotate) Phenomenon) may occur. When such a phenomenon occurs, there is a problem that a plurality of balls are worn out before the trouble of the magnetic bearing occurs, and the life of the touchdown bearing is shortened.

As a prior art aimed at solving such a problem, there is a touch-down bearing disclosed in Patent Document 1.
Patent Document 1 discloses that a rotating wheel including an inner ring and an outer ring, and a ball (rolling element) are formed of a material having a relative magnetic permeability of 1.4 or less.

JP 2002-221226 A

By the way, in a rotating machine (for example, a compressor) used in a refrigerator, the rotating shaft rotates in an atmosphere at a high pressure of atmospheric pressure or higher, sometimes about 1 MPa.
In the rotating machine used in the refrigerator, the present inventors rotate the inner ring of the touchdown bearing due to the influence of the viscosity of the gas existing in the gap formed between the rotating shaft rotating at high speed and the touchdown bearing. (Idling), and before the trouble of the magnetic bearing occurs, the knowledge that a plurality of balls are worn and the life of the touchdown bearing is shortened.
Note that the viscosity of the gas increases as the density and / or temperature of the gas increases.

The touchdown bearing disclosed in Patent Document 1 can suppress the rotation of the touchdown bearing due to the influence of magnetism in a normal state (in this case, a vacuum state).
However, it has been difficult to suppress the rotation of the touchdown bearing due to the influence of the viscosity of the gas present in the gap formed between the rotary shaft rotating at high speed and the touchdown bearing.
For this reason, there existed a problem that a some ball | bowl will wear at the time other than the time of a touchdown, a some ball | bowl will wear, and the lifetime of a touchdown bearing will become short.

  Then, this invention makes it a subject to provide the touchdown bearing and rotary machine which can suppress that a some ball | bowl wears out at the time other than the time of a touchdown, and a lifetime becomes short.

  In order to solve the above-described problem, according to the first aspect of the present invention, the outer peripheral surface of the rotating member is surrounded by the plurality of balls and the rotating member that is rotatably supported by the plurality of magnetic bearings. And an inner ring having a first recess for receiving a part of the plurality of balls in a state where the plurality of balls can be rotated on an outer peripheral portion, and an inner diameter larger than an outer diameter of the inner ring. And an outer ring having a second recess for receiving a part of the plurality of balls in a state where the plurality of balls can be rotated in an inner peripheral portion, and the first and second In the space formed between the recesses, the inner ring that defines the first recess and the outer ring that defines the second recess in a state where the ball can rotate during the touchdown, The outer ring so as to sandwich the ball Against shifting the position of the inner ring in an axial direction of said rotary member, touchdown bearing, characterized in that it comprises a position adjusting member, is provided.

  Moreover, according to the invention which concerns on Claim 2, the said position adjustment member contains the ring-shaped member which contacts the one side of the said inner ring | wheel arrange | positioned in the extension direction of the said rotation member, The said position adjustment member, The central axis of the position adjusting member is arranged so as to coincide with the central axis of the rotating member, and the inner diameter of the ring-shaped member is larger than the inner diameter of the inner ring, and the outer diameter of the ring-shaped member The touch-down bearing according to claim 1, wherein is smaller than an inner diameter of the outer ring.

  According to the invention of claim 3, the position adjusting member includes a protrusion provided on the ring-shaped member and protruding toward the inner ring side, and the inner ring is on the side where the position adjusting member is disposed. The touchdown bearing according to claim 2, further comprising a protruding portion insertion portion into which the protruding portion is inserted.

  According to a fourth aspect of the present invention, the position adjusting member includes an engaging portion that is provided on the ring-shaped member and is engaged with an outer surface of the inner ring. A touchdown bearing is provided.

  According to the invention according to claim 5, the bearing has two bearings, and the ring-shaped member has a first surface abutting on one surface of the inner ring and an opposite side of the surface. And the position adjusting member is disposed between the inner ring constituting one of the bearings and the inner ring constituting the other bearing. A touchdown bearing according to any one of claims 2 to 4 is provided.

  According to the invention of claim 6, the first end insertion portion provided on the inner ring constituting the one bearing and into which one end of the position adjusting member is inserted, and the other end The touch-down bearing according to claim 5, further comprising: a second end insertion portion that is provided on the inner ring constituting the bearing and into which the other end of the position adjusting member is inserted. The

  Moreover, according to the invention which concerns on Claim 7, the said ring-shaped member has several through-holes arrange | positioned in the circumferential direction of this ring-shaped member, and in the state inserted in the said through-hole, A pin projecting at both ends from a ring-shaped member, a plurality of inner rings constituting the one bearing, a first pin insertion hole into which one end of the pin is inserted, and the other bearing The touch-down bearing according to claim 5, further comprising a second pin insertion hole provided in the inner ring, the second pin insertion hole into which the other end of the pin is inserted.

  According to the invention according to claim 8, the magnets installed in the opposing portions of the two inner rings constituting the two bearings are provided, and the magnets installed in the two inner rings have the same magnetic pole. The touchdown bearing according to claim 5, wherein the touchdown bearings are arranged so as to face each other.

  According to a ninth aspect of the invention, the touchdown bearing according to any one of the first to eighth aspects, the rotating member extending in a predetermined direction, and the rotating member being rotatable. There is provided a rotating machine including the plurality of magnetic bearings to be supported and an outer ring position regulating member for regulating the position of the outer ring.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a some ball | bowl wears at times other than the time of touchdown, and the lifetime of a touchdown bearing becomes short.

It is sectional drawing which shows schematic structure of the rotary machine which concerns on the 1st Embodiment of this invention. It is sectional drawing to which the part enclosed by the area | region A shown in FIG. 1 was expanded. It is sectional drawing of the touchdown bearing which concerns on the modification of the 1st Embodiment of this invention. It is sectional drawing of the touchdown bearing which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the touchdown bearing which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the touchdown bearing which concerns on the 4th Embodiment of this invention. It is sectional drawing of the touchdown bearing which concerns on the 5th Embodiment of this invention. It is sectional drawing of the touchdown bearing which concerns on the 6th Embodiment of this invention. It is sectional drawing to which the part enclosed by the area | region B among the touchdown bearings shown in FIG. 8 was expanded. It is sectional drawing of the touchdown bearing which concerns on the 7th Embodiment of this invention.

  Embodiments to which the present invention is applied will be described below in detail with reference to the drawings. The drawings used in the following description are for explaining the configuration of the embodiment of the present invention. The size, thickness, dimensions, etc. of the respective parts shown in the drawings are the dimensions of the actual touchdown bearing and rotating machine. The relationship may be different.

(First embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of a rotating machine according to a first embodiment of the present invention. In FIG. 1, the X direction indicates a predetermined direction (extending direction) in which the main shaft 13 extends, and the Y direction indicates a direction orthogonal to the X direction. In FIG. 1, a compressor is illustrated as an example of the rotating machine 1.

  Referring to FIG. 1, a rotary machine 1 according to a first embodiment includes a high-speed motor 2, a circulating gas compression unit 3, a pair of touchdown bearings 5, an outer ring position regulating member 6, a bolt 7, Have

  The high-speed motor 2 includes a main shaft 13, a rotor 14, a stator 16, magnetic bearings 18 and 19, a motor casing 22, an outer cooling channel 23, an inner cooling channel 24, a cooling bush 25, Have

The main shaft 13 extends in the X direction and is rotatably supported by magnetic bearings 18 and 19. A part of the main shaft 13 is accommodated in the motor casing 22.
The main shaft 13 has one end 13 </ b> A protruding from one end of the motor casing 22 and the other end 13 </ b> B protruding from the other end of the motor casing 22. An impeller 31 to be described later is provided at the end portions 13A and 13B.
Thereby, the main shaft 13 functions as a main shaft of the high-speed motor 2 and also functions as a main shaft of the circulating gas compression unit 3.

The main shaft 13 is configured such that the length in the axial direction (extending direction) is longer than the length in the axial direction of the motor casing 22. Thereby, both end portions 13 </ b> A and 13 </ b> B of the main shaft 13 protrude from the end of the motor casing 22.
As the material of the main shaft 13 having the above-described configuration, for example, an iron-based material having magnetism may be used. Further, it is preferable that the material of the main shaft 13 has substantially the same thermal expansion coefficient as that of the motor casing 22.

The rotor 14 is fixed to the central portion of the outer peripheral portion of the main shaft 13.
The stator 16 is provided so as to surround the outer periphery of the rotor 14. A field coil is attached to the stator 16. The stator 16 rotates the main shaft 13 by transmitting the magnetic field generated by the field coil to the main shaft 13.

  The magnetic bearing 18 is provided on the outer peripheral portion of the main shaft 13 located on the end portion 13A side and on the outer peripheral portion of the main shaft 13 located on the end portion 13B side. The magnetic bearing 18 is disposed at a position separated from the main shaft 13. The magnetic bearing 18 functions as a radial bearing that receives the radial load of the main shaft 13.

The magnetic bearing 19 is provided on the outer peripheral portion of the main shaft 13 located between the magnetic bearing 18 and the stator 16. The magnetic bearing 19 is disposed at a position separated from the main shaft 13. The magnetic bearing 19 has a function of adjusting the position of a thrust plate 19 </ b> A that is a part of the main shaft 13.
The magnetic bearing 19 functions as a thrust (axial) bearing that receives a load in the axial direction of the main shaft 13.

The motor casing 22 is a cylindrical member having flange portions 22A and 22B and through portions 22C and 22D arranged at both ends.
The motor casing 22 accommodates therein a part of the main shaft 13, the rotor 14, the stator 16, the magnetic bearings 18 and 19, and the cooling bush 25.
The through portion 22C is connected to a coolant supply port. The through portion 22 </ b> D is connected to the outer cooling channel 23. The through portion 22 </ b> D is connected to the cooling water discharge port via the outer cooling flow path 23.
The motor casing 22 holds the stator 16 inside thereof via a cooling bush 25. As a material of the motor casing 22, for example, iron or iron-based stainless steel can be used.

The outer cooling flow path 23 includes a groove 23A through which the coolant flows and a cap member 23B. The groove 23 </ b> A is provided in a direction from the flange 22 </ b> A side toward the flange 22 </ b> B side on the outer peripheral surface of the motor casing 22. The shape of the groove 23A is, for example, a spiral shape.
The cap member 23B is a cylindrical member whose inside is hollow. The cap member 23B is provided on the outer peripheral surface of the motor casing 22 so as to cover the formation region of the groove 23A. The inner peripheral surface of the cap member 23 </ b> B is joined while being in close contact with the outer peripheral surface of the motor casing 22.

The inner cooling flow path 24 communicates with the through portions 22 </ b> C and 22 </ b> D provided in the motor casing 22. The inner cooling flow path 24 is communicated with the outer cooling flow path 23 through the penetrating portion 22D.
As a result, the coolant is supplied to the inner cooling flow path 24 from the outside of the motor casing 22 through the through holes 22C and 22D. Further, the coolant after passing through the inner cooling flow path 24 is supplied to the outer cooling flow path 23 through the through hole 22D.
The coolant after passing through the outer cooling channel 23 is discharged from the coolant outlet to the outside of the motor casing 22 through a through hole (not shown) provided in the cap member 23B.

  Examples of the cooling liquid include water, antifreeze liquids such as ethylene glycol and propylene glycol, and oil. Furthermore, instead of the coolant, a gas such as nitrogen, helium, neon, or the like may be used as the cooling fluid.

  The cooling bush 25 has an inner cooling flow path 24. The length of the cooling bush 25 in the axial direction is not particularly limited, but is preferably equal to or slightly longer than the length of the stator 16 from the viewpoint of cooling.

The circulating gas compressor 3 is disposed at both ends of the high speed motor 2. Circulating gas (refrigerant gas) such as helium or neon is sealed inside the circulating gas compression unit 3.
The circulating gas compression unit 3 includes an impeller 31, an inducer 32, and a casing 34.
The impeller 31 is provided at the end portions 13A and 13B of the main shaft 13. The impeller 31 is fixed to the end portions 13A and 13B.
The inducer 32 is fixed to the casing 34 and is disposed so as to surround the impeller 31. One of the two circulating gas compression units 3 may be used as a circulation gas expansion unit that uses the power from the expansion unit as part of the compression power.

The casing 34 is coupled by a bolt or the like at the flange portion 22 </ b> A of the motor casing 22. As a result, the inducer 32 is coupled to the motor casing 22 via the casing 34.
The casing 34 has a fixed wall 32 a that faces the front surface 31 a of the impeller 31. The casing 34 accommodates the impeller 31 and the inducer 32 and holds the inducer 32.
A gap called a shroud clearance is provided between the front surface 31 a of the impeller 31 and the fixed wall 32 a of the inducer 32.

  Since the impeller 31 is fixed to the main shaft 13 and the inducer 32 is indirectly fixed to the motor casing 22, the axial direction of the main shaft 13 and the motor casing 22 when the high-speed motor 2 is driven. When a change occurs in the elongation amount, the shroud clearance value also changes.

  FIG. 2 is an enlarged cross-sectional view of a portion surrounded by a region A shown in FIG. 2, illustration of the main shaft 13 shown in FIG. 1 is omitted. In FIG. 2, only a part of the outer ring position restricting member 6 disposed around the touch-down bearing 5 is illustrated. 2, the same components as those in the structure shown in FIG.

Referring to FIGS. 1 and 2, the touchdown bearing 5 is provided in each of a portion facing the flange portion 22 </ b> A and a portion facing the flange portion 22 </ b> B in the outer peripheral portion of the main shaft 13.
The touchdown bearing 5 includes a first bearing 41, a second bearing 42, and a position adjustment member 44.
The first bearing 41 includes an inner ring 46, an outer ring 48, and a plurality of balls 51 (bearing balls).

The inner ring 46 is a ring-shaped member including a through portion 46A for allowing the main shaft 13 to pass through. The inner ring 46 has two surfaces 46 a and 46 b arranged in the extending direction of the main shaft 13. The surface 46b is disposed on the opposite side of the surface 46a.
The diameter of the through portion 46A is configured to be larger than the outer diameter of the main shaft 13. The inner ring 46 is disposed so as to surround the outer peripheral surface of the main shaft 13 so that the central axis thereof coincides with the central axis C of the main shaft 13. The inner ring 46 is separated from the main shaft 13 in the circumferential direction of the main shaft 13. A gap is formed between the inner ring 46 and the main shaft 13.
Thereby, when the magnetic bearings 18 and 19 are in a normal state and the main shaft 13 is rotatably supported (in other words, other than touchdown), the inner ring 46 is configured not to contact the main shaft 13. ing.

The inner ring 46 has a first recess 46B. The first recess 46 </ b> B is provided on the outer periphery of the inner ring 46. The first recess 46 </ b> B is a ring-shaped recess that accommodates a part of the plurality of balls 51.
In FIG. 2, as an example of the cross-sectional shape of the first recess 46 </ b> B, a shape obtained by cutting a part of a circle has been described as an example, but the cross-sectional shape of the first recess 46 </ b> B is the shape shown in FIG. 2. It is not limited to.

The outer ring 48 is a ring-shaped member whose inner diameter is larger than the outer diameter of the inner ring 46. The outer ring 48 is disposed outside the inner ring 46 so that the central axis thereof coincides with the central axis C of the main shaft 13.
The outer ring 48 is separated from the inner ring 46 in the circumferential direction of the inner ring 46. A space for arranging a plurality of balls 51 is formed between the outer ring 48 and the inner ring 46. A cage (not shown) may be installed in the space.

The outer ring 48 has surfaces 48a and 48b and a second recess 48A. The surface 48a is a surface on which the two outer rings 48 constituting the first and second bearings 41 and 42 face each other. A gap is formed between the surfaces 48 a of the two outer rings 48. That is, the surfaces 48a of the two outer rings 48 are not in contact with each other.
The surface 48b is a surface located on the opposite side of the surface 48a. The surface 48b is in contact with a first member 55 or a second member 56 described later.
The second recess 48 </ b> A is provided on the inner peripheral portion of the outer ring 48. The second recess 48 </ b> A is a ring-shaped recess that accommodates a part of the plurality of balls 51.
In FIG. 2, as an example of the cross-sectional shape of the second recess 48 </ b> A, a shape obtained by cutting a part of a circle has been described as an example. It is not limited to.

The plurality of balls 51 are disposed between the inner ring 46 and the outer ring 48.
The second bearing 42 has the same configuration as the first bearing 41. The second bearing 42 is disposed closer to the magnetic bearing 18 than the first bearing 41.

The position adjusting member 44 is a ring-shaped member (ring-shaped member). The position adjusting member 44 is provided between the inner ring 46 constituting the first bearing 41 and the inner ring 46 constituting the second bearing 42 so that the central axis thereof coincides with the central axis C of the main shaft 13. It has been.
The position adjusting member 44 has first and second surfaces 44 a and 44 b arranged in the extending direction of the main shaft 13.
The first surface 44 a is in contact with the surface 46 a of the inner ring 46 constituting the first bearing 41. The second surface 44 b is in contact with the surface 46 a of the inner ring 46 constituting the second bearing 42.

The inner diameter of the position adjusting member 44 is larger than the inner diameter of the inner ring 46. Thereby, it is possible to suppress contact between the main shaft 13 and the position adjusting member 44 that are arranged in the inner ring 46 and supported in a rotatable state by the magnetic bearings 18 and 19.
The outer diameter of the position adjusting member 44 is configured to be smaller than the inner diameter of the outer ring 48. Thereby, only the inner ring | wheel 46 can be shifted to a X direction, and the play of the some ball | bowl 51 can be suppressed.

  The position adjusting member 44 shifts the position of the inner ring 46 relative to the outer ring 48 constituting each bearing (the first bearing 41 and the second bearing 42) in the axial direction (X direction) of the main shaft 13, thereby The position of the first recess 46B with respect to 48A is shifted in the X direction (reverse direction), and the ball is formed by the inner ring 46 that defines the first recess 46B and the outer ring 48 that defines the second recess 48A. 51, the position of the ball 51 is regulated, and when a touchdown occurs (when a torque of a certain level or more is applied to the touchdown bearing 5), the plurality of balls 51 can be rotated. It is a member.

The thickness of the position adjusting member 44 in the X direction can be appropriately set according to the configuration (for example, shape and size) of the first and second bearings 41 and 42.
Increasing the thickness of the position adjusting member 44 in the X direction increases the amount of movement of the two inner rings 46 in the X direction. Further, when the thickness of the position adjusting member 44 in the X direction is reduced, the movement amount of the two inner rings 46 in the X direction is reduced.

By having the position adjusting member 44 configured as described above, the influence of the viscosity of the gas existing in the gap formed between the main shaft 13 rotating at high speed and the touchdown bearing 5 causes the touchdown bearing 5. It is possible to suppress wear of the plurality of balls 51 when the inner ring 46 rotates (idling) and is not touchdown (when the magnetic bearings 18 and 19 support the rotating main shaft 13 in a normal state). It becomes.
Thereby, shortening of the life of the touch-down bearing 5 due to the influence of the viscosity of the gas present in the gap formed between the main shaft 13 rotating at high speed and the touch-down bearing 5 can be suppressed.

  As the position adjusting member 44, for example, a metal shim can be used. As the material (metal material) of the position adjusting member 44, for example, stainless steel, aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, or the like can be used.

The outer ring position restricting member 6 includes a first member 55 and a second member 56. The first member 55 is a ring-shaped member, and is disposed outside the first and second bearings 41 and 42.
The first member 55 includes an accommodating portion 55 </ b> A that accommodates a part of the outer peripheral portion of the first bearing 41 and the outer peripheral portion of the second bearing 42. The accommodating portion 55A is a ring-shaped notch. A portion of the outer peripheral portion of the first bearing 41 that is not accommodated in the accommodating portion 55 </ b> A protrudes from the first member 55.

The second member 56 is a ring-shaped member and is provided outside the first bearing 41. The second member 56 is between the first member 55 and the end portions 13A and 13B in a state where a gap is interposed between the second member 56 and the first member 55 (a state where the second member 56 is not in contact with the first member 55). Is provided.
The second member 56 includes an accommodating portion 56 </ b> A that accommodates the first bearing 41 protruding from the first member 55. The accommodating portion 56A is a ring-shaped portion processed into a countersink shape.
The outer ring position restricting member 6 configured as described above restricts the position in the X direction and the position in the Y direction of the outer ring 48 constituting the first and second bearings 41 and 42.

  The bolt 7 is for fixing the second member 56 to the first member 55, and a plurality of bolts 7 are provided.

Here, a method for assembling the touchdown bearing 5 to the rotating machine 1 will be described.
First, the touchdown bearing 5 is fitted and attached to the housing portion 55A (fitting portion) of the first member 55 of the rotary machine 1. Specifically, the second bearing 42 is fitted into the accommodating portion 55 </ b> A of the first member 55, and then the first bearing 41 is fitted via the position adjusting member 44.

At this time, the first and second bearings 41 and 42 are fitted into the accommodating portion 55A of the first member 55, so that the center is removed (in other words, the central axis coincides with the central axis C of the main shaft 13). State).
At this stage, the position adjusting member 44 may be in a position shifted with respect to the first and second bearings 41 and 42. In such a case, the position adjustment member 44 is pushed in so that the position adjustment member 44 does not protrude inside the inner ring 46 of the first and second bearings 41 and 42.

  Next, it is confirmed that the position adjusting member 44 does not protrude, and then the second member 56 (a member that presses the outer ring 48 of the first bearing 41) is attached to the touchdown bearing 5. At this time, torque management at the time of attachment is performed in order to make the state in which the ball 51 is sandwiched between the inner ring 46 and the outer ring 48 an optimum state.

  Specifically, when it is confirmed that the ball 51 is sandwiched between the inner ring 46 and the outer ring 48 and is not guided, a measurement jig (for example, inner ring fixing) is attached to the inner ring 46 of the first and second bearings 41 and 42. A jig and a torque wrench), and measure the torque when the inner ring does not rotate and the torque when the inner ring 46 rotates, and confirm whether or not a predetermined condition is satisfied. A position adjusting member 44 having a thickness that satisfies the conditions is used.

The following two points can be exemplified as the confirmation items. As a first point, for example, it is confirmed that the measured torque is the first predetermined torque (for example, 1.0 N · m or less) and the inner ring 46 does not rotate. As a second point, for example, it is confirmed that the inner ring 46 rotates at a second predetermined torque (for example, 2.0 N · m) or more.
By satisfying such conditions, the first and second bearings 41 and 42 rotatably support the main shaft 13 when the function of supporting the main shaft 13 of the magnetic bearings 18 and 19 is reduced or removed. be able to.
At the time of touchdown, a torque larger than the second predetermined torque (for example, 2.0 N · m) is applied to the first and second bearings 41 and 42, so the first and second bearings 41 and 42 rotate.

When the torque when the first and second bearings 41 and 42 rotate is smaller than a desired value, the position adjustment member 44 is replaced with a thicker thickness and the touchdown bearing 5 is reassembled. Then, the torque is measured again to check whether the above two conditions are satisfied.
On the other hand, when the torque when the first and second bearings 41 and 42 rotate is larger than a desired value, the position adjustment member 44 is replaced with a thin thickness, and the touchdown bearing 5 is reassembled. After that, the torque is measured again, and it is confirmed whether or not the above two conditions are satisfied. The replacement of the position adjusting member 44 is performed until the above two conditions are satisfied.

According to the touchdown bearing 5 of the first embodiment, when the function of the magnetic bearings 18 and 19 stops, the ball 51 rotates in the space formed between the first and second recesses 46B and 48A. In a possible state, the position of the inner ring 46 relative to the outer ring 48 is set so that the plurality of balls 51 are sandwiched between the inner ring 46 that defines the first recess 46B and the outer ring 48 that defines the second recess 48A. By having the position adjusting member 44 shifted in the axial direction (X direction), the touch-down bearing is affected by the influence of the viscosity of the gas existing in the gap formed between the main shaft 13 rotating at high speed and the touch-down bearing 5. 5 in the stage before the trouble of the magnetic bearings 18 and 19 occurs (the stage where the magnetic bearings 18 and 19 support the rotating main shaft 13 in a normal state). Ball 51 It is possible to suppress the wear.
Thereby, shortening of the life of the touch-down bearing 5 due to the influence of the viscosity of the gas present in the gap formed between the main shaft 13 rotating at high speed and the touch-down bearing 5 can be suppressed.

  Moreover, the rotary machine 1 of the first embodiment including the touchdown bearing 5 can obtain the same effects as the touchdown bearing 5 described above.

  In FIG. 1, the compressor is taken as an example of the rotary machine 1, but the touchdown bearing 5 is used for an expansion turbine or a liquid feed pump that is the rotary machine 1 other than the compressor, for example. Even when the touchdown bearing 5 is applied to such a rotating machine 1, the same effects as those of the rotating machine 1 and the touchdown bearing 5 of the first embodiment can be obtained.

  Further, in the first embodiment, the case where the touch-down bearing 5 is configured by the first bearing 41, the second bearing 42, and the position adjusting member 44 has been described as an example, but the first bearing 41 is described. The position adjustment member 44 may constitute a touch-down bearing. In this case, the same effect as that of the touchdown bearing 5 of the first embodiment can be obtained.

Note that it is possible to bond the position adjusting member 44 to the first and second bearings 41 and 42 using an adhesive, but in this case, it is necessary to manage the thickness of the adhesive layer at a micron level. However, it is very difficult to manage at this level.
In addition, when the adhesive layer receives heat, the adhesive layer is denatured or burnt, and the pressing load value of the outer ring 48 changes, which is not preferable.

Although it is possible to adjust the outer ring 48 by shaving the first and second bearings 41 and 42 by more than the backlash without using the position adjusting member 44, all the first and second bearings 41, Measuring 42 backlashes and machining all outer rings 48 is very cumbersome and impractical.
“Backlash” as used herein refers to the dimensional tolerance that is caused by the manufacturing dimensions of the bearing and the mechanical manufacturing tolerances that occur when manufacturing the bearing with respect to the target dimensions for constituting the bearing. Say.

  FIG. 3 is a cross-sectional view of a touch-down bearing according to a modification of the first embodiment of the present invention. In FIG. 3, the same components as those of the touchdown bearing 5 of the first embodiment shown in FIG.

  Referring to FIG. 3, a touchdown bearing 60 according to a modification of the first embodiment replaces the position adjustment member 44 that constitutes the touchdown bearing 5 of the first embodiment with a position adjustment member 61. The effect similar to the touchdown bearing 5 can be acquired except having provided.

The position adjusting member 61 is a ring-shaped member, and is positioned between the first bearing 41 and the second bearing 42 so that the central axis thereof coincides with the central axis C (the central axis of the main shaft 13 shown in FIG. 1). Is arranged.
The position adjustment member 61 is configured in the same manner as the position adjustment member 44 except that the thickness in the Y direction is thinner than that of the position adjustment member 44 and the outer diameter is smaller than that of the position adjustment member 44. The outer diameter of the position adjusting member 61 is set to be smaller than the outer diameter of the inner ring 46.

The touchdown bearing 60 according to the modification of the first embodiment provided with the position adjusting member 61 configured as described above can obtain the same effect as the touchdown bearing 5 of the first embodiment. it can.
(Second Embodiment)
FIG. 4 is a sectional view of a touch-down bearing according to the second embodiment of the present invention. In FIG. 4, the same components as those of the touchdown bearing 5 of the first embodiment shown in FIG.

  Referring to FIG. 4, the touchdown bearing 65 of the second embodiment is provided with a position adjustment member 66 instead of the position adjustment member 44 constituting the touchdown bearing 5 of the first embodiment. The configuration is the same as that of the touch-down bearing 5 except that the inner ring 46 constituting the first bearing 1 is provided with the protruding portion insertion portion 46C.

The position adjustment member 66 is disposed between the first bearing 41 and the second bearing 42. The position adjusting member 66 includes a ring-shaped member 68 and a protruding portion 69.
The ring-shaped member 68 is a member similar to the position adjusting member 44 described in the first embodiment. The ring-shaped member 68 has a first surface 68a and a second surface 68b. The first surface 68 a is in contact with the surface 46 a of the inner ring 46 constituting the first bearing 41. The second surface 68 b is in contact with the surface 46 a of the inner ring 46 constituting the second bearing 42.

The protruding portion 69 is provided on the ring-shaped member 68 so as to protrude in the direction (X direction) from the first surface 68 a of the ring-shaped member 68 toward the inner ring 46 of the first bearing 41. The protrusion 69 is disposed on the inner peripheral side of the inner ring 46.
The protruding portion 69 may be, for example, a ring-shaped protruding portion that continuously protrudes in the circumferential direction of the position adjusting member 66, or a plurality of protruding portions that are disposed in the circumferential direction of the position adjusting member 66 and are discontinuous. But you can.
As a protrusion amount of the protrusion part 69, it can select suitably within the range of 0.1-0.2 mm, for example. The thickness of the protrusion 69 in the Y direction can be selected as appropriate within a range of 0.5 to 1.0 mm, for example.

The protruding portion insertion portion 46C is provided for striking a portion facing the protruding portion 69 (specifically, a corner portion of the inner wall of the inner ring 46 shown in FIG. 4) of the inner ring 46 constituting the first bearing 41. It has been.
The protrusion insertion part 46 </ b> C accommodates the protrusion 69. The shape of the protruding portion insertion portion 46 </ b> C can be appropriately selected according to the shape of the protruding portion 69.

According to the touchdown bearing 65 of the second embodiment, the position adjustment with respect to the first bearing 41 is achieved by including the inner ring 46 including the protrusion insertion portion 46C and the position adjustment member 66 including the protrusion 69. The position shift of the member 66 can be suppressed, and the touchdown bearing 65 can be easily attached to the rotating machine 1 shown in FIG.
Moreover, the touchdown bearing 65 of 2nd Embodiment can acquire the effect similar to the touchdown bearing 5 of 1st Embodiment.

In the second embodiment, the case where the protruding portion 69 and the protruding portion insertion portion 46C are provided inside the inner ring 46 has been described as an example. However, the protruding portion 69 and the protruding portion insertion portion 46C are the inner ring 46. It may be provided on the outer side of the inner ring 46 or between the inner surface and the outer surface of the inner ring 46.
When providing the protrusion insertion part 46C between the inner surface and the outer surface of the inner ring 46, the protrusion insertion part 46C is not a notch but a recess.

Further, in the second embodiment, the case where the protruding portion insertion portion 46C is provided in the inner ring 46 constituting the first bearing 41 has been described as an example, but the inner ring 46 constituting the second bearing 42 is provided with the inner ring 46. Further, the protrusion insertion portion 46C may be provided.
Furthermore, the protrusion insertion portion 46C may be provided for each of the two inner rings, and the protrusion 69 may be provided on the second surface 68b of the position adjusting member 66.

In the second embodiment, the case where the touch-down bearing 65 is configured by the first bearing 41, the second bearing 42, and the position adjusting member 66 is described as an example. The position adjustment member 65 may constitute a touch-down bearing. In this case, the same effect as that of the touchdown bearing 5 of the first embodiment can be obtained.
In consideration of the workability of the position adjusting member 66 and the first bearing 41, it is effective when a large bearing is used.

(Third embodiment)
FIG. 5 is a cross-sectional view of a touch-down bearing according to a third embodiment of the present invention. In FIG. 5, the same components as those shown in FIGS. 2 and 4 are denoted by the same reference numerals.

  Referring to FIG. 5, the touchdown bearing 70 of the third embodiment is provided with a position adjustment member 71 instead of the position adjustment member 44 constituting the touchdown bearing 5 of the first embodiment. Other than that, the configuration is the same as that of the touchdown bearing 5.

The position adjusting member 66 includes the ring-shaped member 68 described in the second embodiment and a plurality of engaging portions 72.
The plurality of engaging portions 72 protrude from the portion located at the outer peripheral portion of the first surface 68 a of the ring-shaped member 68 so as to be engageable with the outer peripheral side surface of the inner ring 46. The plurality of engaging portions 72 are arranged at predetermined intervals in the circumferential direction of the ring-shaped member 68. The plurality of engaging portions 72 are configured integrally with the ring-shaped member 68.

According to the touchdown bearing 70 of the third embodiment, by having the plurality of engaging portions 72 configured as described above, it is possible to suppress the positional deviation of the position adjusting member 71 with respect to the first bearing 41, and FIG. The touchdown bearing 70 can be easily attached to the rotating machine 1 shown in FIG.
Moreover, the touchdown bearing 70 of 3rd Embodiment can acquire the effect similar to the touchdown bearing 5 of 1st Embodiment.

In the third embodiment, the case where the engaging portion 72 that is in contact with the outer peripheral surface of the inner ring 46 of the first bearing 41 is provided is described as an example. You may make it contact | abut on the outer peripheral surface of the inner ring | wheel 46 of the 2nd bearing 42. FIG.
Further, the engaging portions 72 may be provided on the first and second surfaces 68a of the ring-shaped member 68, respectively.
Further, the engaging portion 72 may be combined with the protruding portion 69 and the protruding portion insertion portion 46C described above.

  In the third embodiment, the case where the touch-down bearing 70 is configured by the first bearing 41, the second bearing 42, and the position adjusting member 71 has been described as an example. The position adjustment member 71 may constitute a touchdown bearing. In this case, the same effect as that of the touchdown bearing 5 of the first embodiment can be obtained.

  In FIG. 5, the thickness of the ring-shaped member 68 in the X direction is considerably thicker than the thickness of the engaging portion 72 in the Y direction, but when the two thicknesses are substantially equal, By pressing the plate-shaped member, the engagement portion 72 in an unfolded state and the ring-shaped member 68 are collectively formed, and then the engagement with the ring-shaped member 68 is at a right angle. The position adjustment member 71 may be manufactured by bending the joint portion 72.

(Fourth embodiment)
FIG. 6 is a sectional view of a touch-down bearing according to the fourth embodiment of the present invention. In FIG. 6, the same components as those in the structure shown in FIG.

  Referring to FIG. 6, the touchdown bearing 75 of the fourth embodiment is provided with a position adjustment member 76 instead of the position adjustment member 44 constituting the touchdown bearing 5 of the first embodiment, Similar to the touchdown bearing 5 except that the first end insertion portion 46D is provided on the inner ring 46 of the first bearing 41 and the second end insertion portion 46E is provided on the inner ring 46 of the second bearing 41. It is configured.

The position adjusting member 76 is a ring-shaped member, and is configured such that the thickness in the Y direction is thinner than the thickness of the inner ring 46 in the Y direction.
The first and second end insertion portions 46D and 46E are ring-shaped recesses. One end 76A of the position adjustment member 76 is inserted into the first end insertion portion 46D. The other end 76B of the position adjustment member 76 is inserted into the second end insertion portion 46E.
Thereby, the position of the position adjustment member 76 is regulated with respect to the inner ring 46 constituting the first and second bearings 41 and 42.

According to the touchdown bearing 75 of the fourth embodiment, the ring-shaped position adjusting member 76 and the inner ring 46 of the first bearing 41 are provided, and one end 76A of the position adjusting member 76 is inserted. A first end insertion portion 46D, and a second end insertion portion 46E provided in the inner ring 46 of the second bearing 41 and into which the other end 76B of the position adjusting member 76 is inserted. Thereby, while being able to suppress the position shift of the position adjustment member 76 with respect to the 1st and 2nd bearings 41 and 42, the touchdown bearing 75 can be easily mounted | worn with respect to the rotary machine 1 shown in FIG.
Moreover, the touchdown bearing 75 of 4th Embodiment can acquire the effect similar to the touchdown bearing 5 of 1st Embodiment.

(Fifth embodiment)
FIG. 7 is a sectional view of a touch-down bearing according to the fifth embodiment of the present invention. In FIG. 7, the same components as those in the structure shown in FIG.

  Referring to FIG. 7, the touchdown bearing 85 of the fifth embodiment is provided with a position adjustment member 86 instead of the position adjustment member 44 constituting the touchdown bearing 5 of the first embodiment. Further, a plurality of pins 88, a plurality of first pin insertion holes 46F provided in the inner ring 46 of the first bearing 41, and a plurality of second pin insertions provided in the inner ring 46 of the second bearing 42. Except having the hole 46G, it is comprised similarly to the touchdown bearing 5. FIG.

The position adjustment member 86 is a ring-shaped member and has a plurality of through holes 86A that penetrate in the X direction. The plurality of through holes 86 </ b> A are arranged in the circumferential direction of the position adjusting member 86. The inner diameters of the plurality of through holes 86A are sized such that the pins 88 can be inserted.
Both ends of the plurality of pins 88 protrude from the position adjusting member 86 in the X direction while being inserted into the through holes 86A.

The plurality of first pin insertion holes 46 </ b> F are arranged in the circumferential direction of the inner ring 46 of the first bearing 41. One end of the pin 88 is inserted into the first pin insertion hole 46F.
The plurality of second pin insertion holes 46 </ b> G are arranged in the circumferential direction of the inner ring 46 of the second bearing 42. The other end of the pin 88 is inserted into the second pin insertion hole 46G.

According to the touch-down bearing 85 of the fifth embodiment, the position adjustment member 86 has a ring shape and includes a plurality of through holes 86A, and the both ends of the position adjustment member 86 are inserted into the through holes 86A. A plurality of pins 88 projecting from the inner ring 46 of the first bearing 41, and a plurality of second pins provided in the inner ring 46 of the second bearing 42. With the insertion hole 46G, it is possible to suppress the displacement of the position adjustment member 86 with respect to the first and second bearings 41 and 42, and to facilitate the touchdown bearing 85 with respect to the rotating machine 1 shown in FIG. Can be attached to.
Further, the touchdown bearing 85 of the fifth embodiment can obtain the same effects as the touchdown bearing 5 of the first embodiment.
The touchdown bearing 85 is effective when large bearings that are easily affected by gas are used as the first and second bearings 41 and 42.

(Sixth embodiment)
FIG. 8 is a cross-sectional view of a touchdown bearing according to a sixth embodiment of the present invention. In FIG. 8, the same components as those of the structure shown in FIG.
FIG. 9 is an enlarged cross-sectional view of a portion surrounded by the region A in the touch-down bearing shown in FIG. In FIG. 9, the same components as those of the structure shown in FIG.

  Referring to FIGS. 8 and 9, a touchdown bearing 90 of the sixth embodiment is replaced with a plurality of first and second positions adjusting members 44 constituting the touchdown bearing 5 of the first embodiment. The configuration is the same as that of the touchdown bearing 5 except that the second magnets 91 and 92 are provided and the two inner rings 46 are arranged in contact with each other.

  The plurality of first magnets 91 are provided on the surface 46 b side of the inner ring 46. The plurality of first magnets 91 are arranged at a predetermined interval with respect to the circumferential direction of the inner ring 46. The plurality of first magnets 91 includes a first S pole 94 and a first N pole 95.

The plurality of first magnets 92 are provided on the surface 48 b side of the outer ring 48. The plurality of first magnets 92 includes a second N pole 96 disposed to face the first S pole 94 and a second S pole 97 disposed to face the first N pole 95.
The magnetic force attracted by the first magnet 91 and the second magnet 92 is such that the first and second bearings 41 and 42 can rotate at the time of touchdown, and the first and second bearings 41 at times other than the touchdown. , 42 is a strength that does not rotate.

  In FIG. 8, a case where the touch-down bearing 90 is configured by the first bearing 41, the second bearing 42, and the plurality of first and second magnets 91 and 92 is illustrated as an example. However, a touch-down bearing may be configured by one bearing (the first bearing 41 or the second bearing 42) and the plurality of first and second magnets 91 and 92.

That is, referring to FIG. 1, FIG. 8, and FIG. 9, the touchdown bearing 90 of the sixth embodiment is a main shaft that is rotatably supported by a plurality of balls 51 and a plurality of magnetic bearings 18 and 19. 13 is provided so as to surround the outer peripheral surface of the main shaft 13 in a state of being separated from the rotating member 13, and a first part that accommodates a part of the plurality of balls 51 in a state in which the plurality of balls 51 can rotate on the outer peripheral portion. An inner ring 46 having a concave portion 46B, and a second concave portion 48A that accommodates a part of the plurality of balls 51 in a state in which the plurality of balls 51 can be rotated on the inner peripheral portion. A bearing (a first bearing 41 or a second bearing 42) having an outer ring 48 that is configured to be large and that is opposed to the outside of the inner ring 46, and a first S pole that is provided in the inner ring 46 94 and the first N pole 95 A plurality of first magnets 91, a second N pole 96 provided in the outer ring 48 and disposed opposite to the first S pole 94 and a second N pole 96 disposed opposite to the first N pole 95. A plurality of second magnets 92 including an S pole 97, and the magnetic force attracted by the first magnet 91 and the second magnet 92 allows the bearing to rotate at the time of touchdown, and other than at the time of touchdown. Sometimes the bearing is strong enough not to rotate.
A structure in which a cage (not shown) that holds the plurality of balls 51 in a rotatable state may be installed between the inner ring 46 and the outer ring 48.

  The touch-down bearing 90 according to the sixth embodiment has two bearings (the first bearing 41 or the second bearing 42), and the two inner rings 46 constituting the two bearings are two inner rings. The two outer rings 48 constituting the two bearings are in contact with one surface 48a of the two outer rings 48, and the first recess 46B and the second surface 48a are in contact with each other. The plurality of first magnets 91 are arranged on the other surface 46b side of the inner ring 46, and the plurality of second magnets 92 are arranged on the other side of the outer ring 48. It is arranged on the surface 48b side.

According to the touchdown bearing 90 of the sixth embodiment, the first S pole 94 and the first N pole 95 are provided on the surface 46 b side of the inner ring 46 of the first and second bearings 41 and 42. And a second N pole 96 which is provided on the surface 48b side of the outer ring 48 of the first and second bearings 41 and 42 and is disposed opposite to the first S pole 94. , And a plurality of second magnets 92 including a second S pole 97 disposed opposite to the first N pole 95, and the magnetic force attracted by the first magnet 91 and the second magnet 92 is The first and second bearings 41 and 42 can be rotated at the time of touchdown, and the first and second bearings 41 and 42 are not rotated at times other than the touchdown. The effect similar to the touchdown bearing 5 of a form can be acquired.
It should be noted that the same effect can be obtained when the touch-down bearing is configured by only one of the first and second bearings 41 and 42.

(Seventh embodiment)
FIG. 10 is a cross-sectional view of a touch-down bearing according to the seventh embodiment of the present invention. 10, the same components as those shown in FIGS. 6, 8, and 9 are denoted by the same reference numerals.

  Referring to FIG. 10, the touch-down bearing 100 according to the seventh embodiment has a plurality of functions that function as position restriction members instead of the position adjustment member 76 that constitutes the touch-down bearing 75 according to the fourth embodiment. The structure is the same as that of the touch-down bearing 75 except that the magnets 101 and 102 are provided.

The magnet 101 is installed on the surface 46 a side of one of the two inner rings 46. A plurality of magnets 101 are arranged at a predetermined interval with respect to the circumferential direction of the inner ring 46. The plurality of magnets 101 includes a first S pole 94 and a first N pole 95.
The plurality of magnets 101 are arranged such that the first S pole 94 is positioned on the surface 46a side.

The magnet 102 is installed on the surface 46 a side of the other inner ring 46 of the two inner rings 46. A plurality of magnets 102 are arranged at a predetermined interval so as to face the first S pole 94 in the circumferential direction of the inner ring 46. The plurality of magnets 102 includes a first S pole 94 and a first N pole 95.
The plurality of magnets 101 includes a second south pole 97 disposed on the surface 46 a side and disposed opposite to the first south pole 94, and a second north pole 96.
Thereby, the two inner rings 46 are in a state of being separated from each other in the extending direction of the central axis C by the magnetic force separating the magnet 101 and the magnet 102.
That is, the position of the inner ring 46 relative to the outer ring 48 is shifted in the axial direction of the rotating member due to the magnetic force separating the magnet 101 and the magnet 102. Therefore, a plurality of balls 51 can be sandwiched between the inner ring 46 and the outer ring 48.

According to the touchdown bearing 100 of the seventh embodiment, the first and second bearings 41 and 42 are adjusted by adjusting the number of magnets 101 and 102 to be installed and the strength of the magnetic force of the magnets 101 and 102. It is possible to adjust the torque at which the motor rotates. Thereby, the effect similar to the touchdown bearing 5 of 1st Embodiment can be acquired.
A structure in which a cage (not shown) that holds the plurality of balls 51 in a rotatable state may be installed between the inner ring 46 and the outer ring 48.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

  The present invention can be applied to a touchdown bearing that rotatably supports a main shaft at the time of touchdown, and a rotary machine including the touchdown bearing.

  DESCRIPTION OF SYMBOLS 1 ... Rotary machine, 2 ... High-speed motor, 3 ... Circulating gas compression part, 5, 60, 65, 70, 75, 85, 90, 100 ... Touchdown bearing, 6 ... Outer ring position control member, 7 ... Bolt, 13 ... Main shaft, 13A, 13B, 76A, 76B ... end, 14 ... rotor, 16 ... stator, 18, 19 ... magnetic bearing, 19A ... thrust plate, 22 ... motor casing, 22A, 22B ... flange, 22C, 22D , 46A ... penetrating part, 23 ... outer cooling channel, 23A ... groove, 23B ... cap member, 24 ... inner cooling channel, 25 ... cooling bush, 31 ... impeller, 31a ... front, 32 ... inducer 32, 32a ... Fixed wall, 34 ... casing, 41 ... first bearing, 42 ... second bearing, 44, 61, 66, 71, 76, 86 ... position adjusting member, 44a, 68a ... first surface, 44 , 68b ... second surface, 46 ... inner ring, 46a, 46b, 48a, 48b ... surface, 46B ... first recess, 46C ... projection insertion portion, 46D ... first end insertion portion, 46E ... second 46F ... first pin insertion hole, 46G ... second pin insertion hole, 48 ... outer ring, 48A ... second recess, 51 ... ball 55 ... first member, 55A, 56A ... accommodating Part 56 ... second member 68 ... ring-like member 69 ... projection part 72 ... engagement part 76A, 76B ... end part 86A ... through hole 88 ... pin 91 ... first magnet 92 ... Second magnet 94 ... first S pole, 95 ... first N pole, 96 ... second N pole, 97 ... second S pole, 101,102 ... magnet, A, B ... region, C ... Center axis

Claims (9)

With multiple balls,
It is provided so as to surround the outer peripheral surface of the rotating member in a state of being separated from the rotating member that is rotatably supported by a plurality of magnetic bearings, and the plurality of balls can be rotated on the outer peripheral portion. An inner ring having a first recess for accommodating a part of the ball;
An outer ring configured to have an inner diameter larger than an outer diameter of the inner ring, and having a second recess that accommodates a part of the plurality of balls in an inner circumferential part in a state where the plurality of balls can be rotated; ,
A bearing having
In the space formed between the first and second recesses, the inner ring that defines the first recess and the second recess are defined in a state where the ball can rotate during the touchdown. A position adjusting member that shifts the position of the inner ring with respect to the outer ring in the axial direction of the rotating member so as to sandwich the ball with the outer ring;
A touch-down bearing comprising: The position adjustment member includes a ring-shaped member that contacts one side of the inner ring disposed in the extending direction of the rotating member,
The position adjusting member is arranged so that a central axis of the position adjusting member coincides with a central axis of the rotating member,
The inner diameter of the ring-shaped member is not less than the inner diameter of the inner ring,
The touch-down bearing according to claim 1, wherein an outer diameter of the ring-shaped member is smaller than an inner diameter of the outer ring. The position adjustment member is provided on the ring-shaped member, and includes a protruding portion protruding toward the inner ring side,
The touchdown bearing according to claim 2, wherein the inner ring includes a protruding portion insertion portion into which the protruding portion is inserted on a side where the position adjusting member is disposed.   The touch-down bearing according to claim 2, wherein the position adjusting member includes an engaging portion that is provided on the ring-shaped member and is engaged with an outer surface of the inner ring. Two bearings,
The ring-shaped member includes a first surface that is in contact with one surface of the inner ring, and a second surface that is disposed on the opposite side of the surface.
The said position adjustment member is arrange | positioned between the inner ring | wheel which comprises one said bearing, and the inner ring | wheel which comprises the other said bearing, The any one of Claim 2 thru | or 4 characterized by the above-mentioned. Touchdown bearing. A first end insertion portion provided on the inner ring constituting the one bearing and into which one end of the position adjusting member is inserted;
A second end insertion portion provided on the inner ring constituting the other bearing, into which the other end of the position adjusting member is inserted;
The touchdown bearing according to claim 5, further comprising: The ring-shaped member has a plurality of through holes arranged in the circumferential direction of the ring-shaped member,
In a state where it is inserted into the through hole, a pin whose both ends protrude from the ring-shaped member,
A plurality of inner rings constituting the one bearing, a first pin insertion hole into which one end of the pin is inserted;
A second pin insertion hole provided in the inner ring constituting the other bearing, into which the other end of the pin is inserted;
The touchdown bearing according to claim 5, further comprising: Provided with magnets respectively installed in opposing portions of the two inner rings constituting the two bearings,
The touchdown bearing according to claim 5, wherein the magnets installed in the two inner rings are arranged so that the same magnetic poles face each other. The touchdown bearing according to any one of claims 1 to 8,
The rotating member extending in a predetermined direction;
The plurality of magnetic bearings rotatably supporting the rotating member;
An outer ring position regulating member for regulating the position of the outer ring;
A rotating machine comprising:

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