JP2018141482A - Rotary machine and bearing structure for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contact between a bearing body part and a rotor shaft step part adjacent thereto without increasing a size in an axial direction in a rotary machine.SOLUTION: A rotary machine comprises a rotor shaft 11 supported by two bearing structures 30 by two outer diameter contraction parts 11a and a rotary part provided thereto. Each of the bearing structures 30 comprises a bearing body part 31, a metal part for a bearing surface 32 and a bearing body end protective metal part 33. In the bearing body part 31 formed with a lubricating oil inflow groove and a lubricating oil discharge groove 31c, an end surface radial direction inside part 31e is formed so as to be recessed closer to an inside in an axial direction than an end surface radial direction outside part 31f. The bearing body end protective metal part 33 has material quality softer than that of a material of the bearing body portion 31 and the rotor shaft 11, and is provided on a surface of the end surface radial direction inside part 31e. At least a part of the surface protrudes closer to an outside in the axial direction than the end surface radial direction outside part 31f.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a rotating machine and a bearing structure thereof.

  A rotating electrical machine as a typical example of a rotating machine includes a rotor shaft extending in the axial direction, a rotor having a rotor core attached to the outer side in the radial direction, and a fixed portion provided on the outer side in the radial direction of the rotor core. A stator core and a stator having a stator winding penetrating the radially inner portion in the axial direction.

  The rotor shaft is rotatably supported by bearings on both sides in the axial direction. The bearing is roughly classified into a sliding bearing and a rolling bearing. In general, when used in a rotating electric machine that rotates at high speed, a sliding bearing is advantageous, and many rotating electric machines use a sliding bearing.

  Further, in the case of a sliding bearing, there are an oil ring method and a forced oil supply method as a supply method of lubricating oil for forming an oil film. In the oil ring system, since there is an upper limit in the region of the rotational speed of the rotor shaft, the forced oiling system is used particularly at a high speed (see Patent Document 1).

JP 2012-237456 A

  In a vertical rotary machine having a vertical axis, a thrust bearing is provided as a bearing that receives its own weight. Further, even a horizontal rotating machine having a horizontal axis, a thrust force, that is, a moving force in the axial direction is generated. For example, in the case of a turbine, the thrust force is the amount that cannot completely cancel the axial longitudinal load due to the flow of the turbine driving fluid such as steam or gas. Thrust force is also generated when a bevel gear is used. In such a case, an axial load is received by the thrust bearing or a bearing capable of resisting the thrust force, and the axial movement of the rotor shaft is limited.

  When the thrust bearing is worn or its function is deteriorated, the rotor shaft may be displaced in the axial direction. When the axial deviation exceeds a predetermined set value, for example, a turbine protection safety device or the like is normally operated, and the rotating machine is stopped. When such an abnormality occurs, the relative position with respect to the rotor shaft changes in a normal radial bearing until the rotating machine stops.

  In the range of the portion of the rotor shaft supported by the bearing, the outer diameter of the rotor shaft may be reduced. In such a case, the diameter before and after that is larger than this, so if the relative position with the rotor shaft changes, the axial end of the bearing body will be the end of the portion with the larger diameter of the rotor shaft. There is a risk of contact.

  In consideration of this case, it is necessary to consider the protection of the bearing main body that may contact the rotor shaft. Therefore, an object of the present invention is to prevent contact between a bearing body portion and a rotor shaft step portion adjacent in the axial direction without greatly increasing the axial size in a rotary machine.

  In order to achieve the above-described object, the present invention is a rotor that extends in the axial direction and is formed at two locations in the axial direction so as to be rotatably supported at each of the two outer diameter reduction portions whose outer diameter is smaller than the front and rear in the axial direction. A shaft, a rotary part provided between the two outer diameter reducing parts in the axial direction and radially outside the rotor shaft, and coupled to the rotor shaft; and the two outer diameter reducing parts fixedly supported. Each of the two bearing structures for supporting the rotor shaft, each of the two bearing structures being arranged so as to surround a radially outer side of the rotor shaft, An inner surface radially inward is formed so as to face the outer surface of the oil, and the lubricating oil inflow groove having a lubricating oil inlet formed on the inner surface over the entire circumference in the axial center is formed on the inner surface. Two lubricating oil discharge grooves which are arranged on both sides in the axial direction of the oil inflow groove and which are formed over the entire circumference in the circumferential direction and have lubricating oil discharge ports, and are radially inner portions at both ends in the axial direction From the bearing body portion formed such that the radially inner end portion of the end surface is recessed inward in the axial direction relative to the radially outer end portion adjacent to the radially outer side, the material of the bearing body portion, and the material of the rotor shaft Is a soft material, and is a material softer than the material of the bearing surface portion and the material of the bearing body portion and the material of the rotor shaft provided in layers along the radially inner surface of the bearing body portion. The bearing body portion is provided in a layered manner along the surface of the inner end portion in the radial direction of the end surface, and at least a part of the outermost surface in the axial direction protrudes outward in the axial direction from the outer portion in the radial direction of the end surface. Characterized by comprising a bearing body end portion protective metal portion.

  The present invention also includes a rotor shaft that extends in the axial direction and is formed at two axial positions, and is rotatably supported at each of two outer diameter reduction portions whose outer diameter is smaller than the front and rear in the axial direction. A rotating part provided between the two outer diameter reducing parts and radially outside the rotor shaft and coupled to the rotor shaft, and the two outer diameter reducing parts are fixedly supported. Each of the bearing structure for supporting the rotor shaft, and arranged so as to surround a radially outer side of the rotor shaft, and an inner surface on a radially inner side is formed so as to face an outer surface of the rotor shaft, On the inner surface, a lubricating oil inflow groove having a lubricating oil inflow port formed at the central portion in the axial direction over the entire circumferential direction, and disposed on both sides in the axial direction of the lubricating oil inflow groove and extending over the entire circumferential direction. And two lubricating oil discharge grooves having a lubricating oil discharge port, and an end surface radial outer side that is an inner radial end portion of both ends in the axial direction and that is adjacent to the radial outer side. A bearing main body formed so as to be recessed inward in the axial direction from the portion, a material softer than the material of the bearing main body and the material of the rotor shaft, and on the radially inner surface of the bearing main body A bearing surface metal portion provided in layers along the surface of the bearing main body portion and the rotor shaft material, and a material softer than the material of the rotor shaft, A bearing body end protecting metal portion provided in a layered manner and having at least a part of the outermost surface in the axial direction projecting outward in the axial direction from the outer end portion in the radial direction of the end surface. To.

  ADVANTAGE OF THE INVENTION According to this invention, in a rotary machine, the contact between a bearing main-body part and the rotor shaft level | step-difference part adjacent to an axial direction can be prevented, without increasing the size of an axial direction largely.

It is an elevation sectional view showing the composition of the rotary electric machine concerning a 1st embodiment. It is sectional drawing along the axial direction which shows the shape of the bearing main-body part which is a main-body part of the bearing structure which concerns on 1st Embodiment, Comprising: It is a figure which shows the state before attaching a rotor shaft. It is sectional drawing along the axial direction which shows the state which combined the bearing structure and rotor shaft which concern on 1st Embodiment. It is sectional drawing which shows the detail of the A section of FIG. It is sectional drawing along the axial direction which shows the comparative example of a structure of a bearing structure. It is sectional drawing along the axial direction which shows the detail of the edge part of the bearing structure which concerns on 2nd Embodiment. It is sectional drawing along the axial direction which shows the detail of the edge part of the modification of the bearing structure which concerns on 2nd Embodiment. It is a perspective view which shows the edge part of the bearing structure which concerns on 3rd Embodiment. It is a front view which shows the edge part of the bearing structure which concerns on 3rd Embodiment. FIG. 9 is a cross-sectional view taken along line XX of FIG. 8 showing an end portion of a bearing structure according to a third embodiment.

  Hereinafter, a rotating machine and a bearing structure thereof according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted. In the following embodiments, a rotating electrical machine is illustrated as an example of a rotating machine, but the present invention is also applicable to other rotating machines.

[First Embodiment]
FIG. 1 is an elevational sectional view showing the configuration of the rotating electrical machine according to the first embodiment. The rotating electrical machine 100 includes a rotor 10 and a stator 20.

  The rotor 10 includes a rotor shaft 11 that extends in the direction of the rotation axis, and a rotor core 12 that is provided on the radially outer side of the rotor shaft 11. The rotor shaft 11 is rotatably supported by the bearing structure 30 at two locations sandwiching the rotor core 12 in the axial direction. A portion of the rotor shaft 11 supported by the bearing structure 30 is formed with an outer diameter reduced portion 11a whose outer diameter is smaller than that of the normal outer diameter portion 11b before and after the axial direction.

  The bearing structure 30 can be divided into a plurality of partial structures in order to be attached to the outer diameter reduced portion 11a, and can be assembled together after the respective partial structures are attached to the outer diameter reduced portion 11a. Usually, in many cases, the bearing structure 30 has a structure that can be divided into two upper and lower partial structures.

  Inner fans 15 are attached to the rotor shaft 11 between the rotor core 12 and the bearing structures 30 on both sides of the rotor core 12 sandwiched in the axial direction.

  The stator 20 has a stator core 21 and a stator winding 22. The stator core 21 is provided on the radially outer side of the rotor core 12 via the gap 18 and has a cylindrical shape. The stator winding 22 passes through a slot (not shown) formed in the radial inner surface of the stator core 21 at intervals in the circumferential direction and extending in the rotation axis direction.

  The rotor core 12 and the stator 20 are surrounded by a frame 40 disposed on the radially outer side. Bearing brackets 45 are attached to both ends of the frame 40 in the rotation axis direction. The two bearing structures 30 that rotatably support both ends of the rotor shaft 11 are fixedly supported by bearing brackets 45, respectively.

  A cooler 60 is provided above the frame 40 and is connected to the frame 40. The cooler 60 includes a cooling unit 61 and a cooler cover 62 that houses the cooling unit 61.

  The frame 40, the two bearing brackets 45, and the cooler cover 62 combine with each other to form a closed space 40a. The space in the frame 40 and the space in the cooler cover 62 communicate with each other through one cooler inlet opening 63 and two cooler outlet openings 64. The cooler inlet opening 63 is provided above the stator 20 in the axial direction, and the two cooler outlet openings 64 are respectively provided above the two inner fans 15. The closed space 40a is filled with a cooling gas such as air. The cooling gas is driven by the inner fan 15 and circulates in the closed space 40a.

  FIG. 2 is a cross-sectional view along the axial direction showing the shape of the bearing main body which is the main body portion of the bearing structure, and shows a state before the rotor shaft is attached. In FIG. 2, the case where the bearing structure 30 is a forced oil supply system is shown.

  The bearing structure 30 includes a bearing body portion 31, a bearing surface metal portion 32 (FIG. 4), and a bearing body end portion protecting metal portion 33 (FIG. 4). The bearing surface metal portion 32 and the bearing body end portion protection metal portion 33 will be described later.

  The bearing main body 31 of the bearing structure 30 has a substantially cylindrical shape. The radially outer side of the bearing body 31 protrudes radially outward so that the bearing body 45 is supported stationary by the bearing bracket 45.

  A rotor shaft through-hole 31 h for allowing the rotor shaft 11 to pass therethrough is formed at the shaft center of the bearing body 31. Two types of grooves are formed on the inner surface of the rotor shaft through hole 31h.

  The first groove is a lubricating oil inflow groove 31b. The lubricating oil inflow groove 31b is formed over the entire circumference in the circumferential direction substantially at the center in the axial direction of the inner surface of the rotor shaft through hole 31h. The lubricating oil inflow groove 31b communicates with the external forced oil supply device 51 through the lubricating oil inlet 31a.

  The second groove is two lubricating oil discharge grooves 31c. The lubricating oil discharge groove 31c is formed over the entire circumference in the circumferential direction on both sides of the lubricating oil inflow groove 31b in the axial direction of the inner surface of the rotor shaft through hole 31h. Each lubricating oil discharge groove 31c communicates with an external discharge path (not shown) via a lubricating oil discharge port 31d.

  With the configuration as described above, in a state where the rotor shaft 11 rotates, the lubricating oil supplied from the forced oil supply device 51 first flows into the lubricating oil inflow groove 31b via the lubricating oil inlet 31a, and the bearing structure 30. An oil film is formed in the gap between the rotor shaft 11 and the rotor shaft 11. The extruded lubricating oil flows into the lubricating oil discharge grooves 31c on both sides, and is discharged to the external discharge path through the lubricating oil discharge port 31d. By forming such a flow of lubricating oil, the frictional heat between the bearing structure 30 and the rotor shaft 11 due to the rotation of the rotor shaft 11 is removed and transferred to the outside. As a result, the temperature in the bearing structure 30 is maintained within a predetermined range.

  FIG. 3 is a cross-sectional view along the axial direction showing a state in which the bearing structure and the rotor shaft are combined. FIG. 4 is a cross-sectional view showing details of a portion A in FIG.

  The bearing structure 30 is provided on the outer side in the radial direction of the outer diameter reducing portion 11 a of the rotor shaft 11. A main body end surface 31 g that is an end surface in the axial direction of the bearing main body 31 of the bearing structure 30 faces the end surface 11 c of the normal outer diameter portion 11 b of the rotor shaft 11.

  A bearing surface metal portion 32 is disposed on the radially inner surface of the bearing body portion 31. Therefore, the bearing structure 30 is in contact with the outer diameter reduced portion 11a of the rotor shaft 11 in the bearing surface metal portion 32, and direct contact with the outer diameter reduced portion 11a of the rotor shaft 11 of the bearing body portion 31 is avoided. ing.

  The material of the bearing surface metal portion 32 is a slide bearing alloy (hereinafter referred to as white metal) mainly composed of a low melting point alloy such as lead, tin, antimony, or zinc. As for the bearing metal portion 32, for example, a method is used in which a mold is attached to the bearing main body 31 and a material of the bearing metal is poured into the mold, and then molded by machining. For this reason, a bearing metal layer is also formed on the radially inner side of the surfaces such as the lubricating oil inflow groove 31b and the lubricating oil discharge groove 31c.

  Here, from the viewpoint of machining, it is desirable that the thickness of the bearing metal layer has a minimum thickness on the order of several millimeters, for example.

  A step is formed in the radial direction on the end surface 31 g of the main body portion of the bearing main body portion 31. The step is formed so that the end surface radial inner portion 31e, which is the radially inner portion, is more inward in the axial direction than the end surface radial outer portion 31f, which is the radially outer portion of the main body end surface 31g. Has been. That is, the end surface radial direction inner portion 31e is recessed from the end surface radial direction outer portion 31f.

  A bearing metal layer is also provided in the end surface radial direction inner portion 31e, and a bearing main body end protecting metal portion 33 is formed. Therefore, the axial surface of the bearing body end protecting metal portion 33 faces the end surface 11 c of the normal outer diameter portion 11 b of the rotor shaft 11. The material of the bearing body end protecting metal portion 33 is white metal which is an alloy for a sliding bearing mainly composed of a low melting point alloy such as lead, tin, antimony or zinc. The material of the bearing body end protecting metal portion 33 may be the same as the material of the bearing surface metal portion 32 or may have a different composition.

  Here, as described above, the thickness t of the bearing body end protecting metal portion 33 is equal to or greater than the minimum thickness of, for example, several millimeters. The thickness t is larger than the dimension of the width of the step in the axial direction between the end surface radial direction outer portion 31f and the end surface radial direction inner portion 31e. Accordingly, the surface of the bearing body end protecting metal portion 33 protrudes in the axial direction from the end surface radial direction outer portion 31f to the end surface side of the normal outer diameter portion 11b. The protruding width d is a dimension obtained by subtracting the step between the end surface radial direction outer portion 31f and the end surface radial direction inner portion 31e from the thickness t of the bearing body end protecting metal portion 33.

  For this reason, if the bearing main body 31 and the end surface of the normal outer diameter portion 11b come close to each other, first, the bearing main body end protecting metal portion 33 and the end surface of the normal outer diameter portion 11b come into contact with each other. Direct contact between the main body 31 and the normal outer diameter portion 11b can be avoided.

  FIG. 5 is a cross-sectional view along the axial direction showing a comparative example of the structure of the bearing structure. In this comparative example, no step is formed on the axial end surface of the bearing body 31. Accordingly, when forming the bearing body end protecting metal portion 34 here, the thickness t1 equal to or greater than the aforementioned minimum thickness is required. As a result, in order to ensure a conventional value for the distance between the bearing structure 30 and the end surface of the normal outer diameter portion 11b, the length of the axial rotor shaft must be increased by t1, that is, several millimeters. .

  On the other hand, in the present embodiment, the width d protruding from the end surface radial direction outer portion 31f in the axial direction is the length to which the rotor shaft 11 should be extended. Here, d is 1 mm or less, for example, about 0.5 mm because there is no limitation on the minimum thickness in machining.

  As described above, according to the present embodiment, in the rotating machine, it is possible to prevent contact between the bearing main body portion and the rotor shaft without greatly increasing the axial size.

[Second Embodiment]
FIG. 6 is a cross-sectional view showing details of an end portion of the bearing structure according to the second embodiment. This embodiment is a modification of the first embodiment.

  In the bearing structure according to the second embodiment, the portion close to the end surface radial direction outer portion 31f of the bearing body end portion protection metal portion 33 does not protrude from the end surface radial direction outer portion 31f, and the end surface radial direction outer portion 31f. The range of the more protruding portion is smaller than that in the case of the first embodiment.

  Specifically, in the mold when injecting the white metal, a mold that does not protrude from the end surface radial direction outer portion 31f of the portion close to the end surface radial direction outer portion 31f of the bearing body end protection metal portion 33 To do. By doing so, when machining, it is not necessary to machine a portion having different hardness such as a boundary portion between the end surface radial direction outer portion 31f and the bearing main body end protecting metal portion 33, so that machining is easy. In addition, the accuracy of machining is improved.

  FIG. 7 is a cross-sectional view along the axial direction showing details of an end of a modified example of the bearing structure according to the second embodiment. In this modification, a taper is formed in the portion protruding in the axial direction from the end surface radial direction outer portion 31f of the bearing body end portion protecting metal portion 33 so that the protruding dimension decreases as it goes radially inward. . The taper may be a direction in which the protruding dimension increases as it becomes radially inward.

  The bearing body end protecting metal portion 33 formed in this way has a small contact area at the time of initial contact when it comes into contact with the end surface of the normal outer diameter portion 11b of the rotor shaft 11. For this reason, a load is not applied to the bearing body end protecting metal portion 33 in an impact. Further, as the distance between the bearing main body 31 and the end face of the normal outer diameter portion 11b becomes smaller, the contact area increases and the effect of avoiding direct contact between the bearing main body 31 and the normal outer diameter portion 11b increases. To do.

[Third Embodiment]
FIG. 8 is a perspective view showing a part of an end portion of the bearing structure according to the third embodiment. FIG. 9 is a front view. 10 is a cross-sectional view taken along line XX in FIG. However, in FIG. 10, some are not omitted.

  In addition, in FIG. 8, in order to clarify the shape of the end surface radial direction inner portion 31e, the bearing main body end protecting metal portion 33 is not shown. Further, the lubricating oil discharge groove 31c and the lubricating oil inflow groove 31b and the inside thereof are not shown, as viewed from the axial end portion side of the bearing structure 30.

  This embodiment is a modification of the first embodiment. In the third embodiment, the surface of the inner end portion 31e in the end surface radial direction is not flat, and is a combination of the inclined surface 33b and the step surface 33a. The inclination is formed so that the stepped surface 33a can be seen when viewed from the rotation direction of the rotor shaft 11.

  When the bearing body end protecting metal portion 33 comes into contact with the end surface of the normal outer diameter portion 11 b of the rotor shaft 11, both frictional forces are generated in the rotation direction of the rotor shaft 11. As a result, a torsional force in the rotational direction is applied to the bearing body end protecting metal portion 33.

  This torsional force is transmitted inside the bearing body end protecting metal portion 33, and most of the torsional force is converted into a load on the step surface 33a. Therefore, the bearing body end protecting metal portion 33 is securely held by the step surface 33a without sliding or peeling off the surface of the end surface radial direction inner portion 31e.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, embodiment is shown as an example and is not intending limiting the range of invention.

  As described above, in the embodiment, the rotating electric machine is illustrated as an example of the rotating machine, but the present invention can be applied to other rotating machines. In this case, the rotating machine includes a rotor shaft and a rotating portion that is provided on the radially outer side of the rotor shaft and coupled to the rotor shaft. For example, in the case of a rotating electrical machine, a rotor core or the like corresponds to the rotating portion. In the case of a blower or a pump, a blade or the like corresponds to the rotating part.

  Furthermore, the embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and the modifications thereof are included in the scope of the invention and the scope of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Rotor, 11 ... Rotor shaft, 11a ... Outer diameter reduction part, 11b ... Normal outer diameter part, 11c ... End surface, 12 ... Rotor core (rotation part), 15 ... Inner fan, 18 ... Gap, 20 ... Fixed Substrate, 21 ... stator core, 22 ... stator winding, 30 ... bearing structure, 31 ... bearing body, 31a ... lubricating oil inlet, 31b ... lubricating oil inflow groove, 31c ... lubricating oil discharge groove, 31d ... lubrication Oil discharge port, 31e ... end face radial inner part, 31f ... end face radial outer part, 31g ... main body end face, 31h ... rotor shaft through hole, 32 ... bearing surface metal part, 33 ... bearing main body end part protection metal 33a ... Stepped surface 33b ... Inclined surface 34 ... Metal part for protecting bearing body end, 40 ... Frame, 40a ... Closed space, 45 ... Bearing bracket, 51 ... Forced oil supply device, 60 ... Cooler, 61 ... Cooling section, 62 ... Cooler cover , 63 ... cooler inlet opening, 64 ... cooler outlet opening, 100 ... rotary electric machine (rotating machine)

Claims (7)

A rotor shaft that extends in the axial direction and is formed at two locations in the axial direction and is rotatably supported at each of the two outer diameter reduction portions whose outer diameter is smaller than the front and rear in the axial direction;
A rotating part provided between the two outer diameter reducing parts in the axial direction and radially outside the rotor shaft and coupled to the rotor shaft;
Two bearing structures that are fixedly supported and support the rotor shaft in each of the two outer diameter reduction portions;
A rotating machine comprising:
Each of the two bearing structures is
The inner surface of the rotor shaft is arranged so as to surround the outer surface of the rotor shaft in the radial direction so as to face the outer surface of the rotor shaft. A lubricating oil inflow groove formed and having a lubricating oil inlet, and two lubricating oil discharge grooves having a lubricating oil outlet formed on both sides in the axial direction of the lubricating oil inflow groove and formed over the entire circumference. The bearing main body is formed such that the radially inner portion of the end surface, which is the radially inner portion of both ends in the axial direction, is recessed inward in the axial direction relative to the radially outer end portion adjacent to the radially outer side. When,
A material for the bearing surface, which is softer than the material of the bearing body and the material of the rotor shaft, and is provided in layers along the radially inner surface of the bearing body,
A material softer than the material of the bearing main body and the material of the rotor shaft, provided in layers along the surface of the radially inner end portion of the bearing main body, and the outermost axially outer surface. At least a part of the bearing body end protection metal portion that protrudes outward in the axial direction from the end surface radial direction outer portion; and
A rotating machine comprising:   A plurality of inclined surfaces that are inclined in the same direction in the circumferential direction are formed on the surface of the inner portion in the end surface radial direction, and step surfaces are formed between the inclined surfaces adjacent to each other. The rotating machine according to claim 1, wherein the rotating machine is formed.   3. The rotating machine according to claim 1, wherein a surface of the bearing body end protecting metal portion has a planar shape parallel to a surface of the end surface radial direction outer portion.   3. The rotating machine according to claim 1, wherein a surface of the bearing main body end protecting metal portion is inclined in a radial direction.   The surface of the area | region adjacent to the said end surface radial direction outer side part of the said bearing main body edge part protection metal part exists in the same position as the said end surface radial direction outer side part in the axial direction. A rotating machine according to any one of the above. The rotating part is a rotor core attached to the outer side in the radial direction of the rotor shaft,
A cylindrical stator core disposed with a gap on the radially outer side of the rotor core, and a plurality of stator windings penetrating through a plurality of slots formed on a radially inner surface of the stator core. A stator having
A frame for housing the rotor core and the stator;
The rotating machine according to any one of claims 1 to 5, further comprising: A rotor shaft that extends in the axial direction and is formed at two locations in the axial direction and is rotatably supported in each of the two outer diameter reduction portions whose outer diameter is smaller than the front and rear in the axial direction, and the two outer diameter reductions in the axial direction A rotary part provided between the two parts and provided outside the rotor shaft in the radial direction and coupled to the rotor shaft. The rotary shaft is fixedly supported and the rotor shaft in each of the two outer diameter reduction parts Bearing structure for supporting
The inner surface of the rotor shaft is arranged so as to surround the outer surface of the rotor shaft in the radial direction so as to face the outer surface of the rotor shaft. A lubricating oil inflow groove formed and having a lubricating oil inlet, and two lubricating oil discharge grooves having a lubricating oil outlet formed on both sides in the axial direction of the lubricating oil inflow groove and formed over the entire circumference. The bearing main body is formed such that the radially inner portion of the end surface, which is the radially inner portion of both ends in the axial direction, is recessed inward in the axial direction relative to the radially outer end portion adjacent to the radially outer side. When,
A material for the bearing surface, which is softer than the material of the bearing body and the material of the rotor shaft, and is provided in layers along the radially inner surface of the bearing body,
A material softer than the material of the bearing main body and the material of the rotor shaft, provided in layers along the surface of the radially inner end portion of the bearing main body, and the outermost axially outer surface. At least a part of the bearing body end protection metal portion that protrudes outward in the axial direction from the end surface radial direction outer portion; and
A bearing structure comprising:

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