Foil bearing

Abstract

To provide a foil bearing which inhibits increase of manufacturing work hours of the foil bearing when a shim foil is disposed in the foil bearing while arranging the shim foil in the foil bearing to inhibit wear of a bearing housing.SOLUTION: A foil bearing 10 includes: a cylindrical metallic bearing housing 20 into which a rotary shaft 103 is inserted; a plate-like metallic top foil 30 disposed between the rotary shaft 103 and the bearing housing 20; a metallic bump foil 40 which is provided at the opposite side of the rotary shaft 103 across the top foil 30 and extends to support the top foil 30 elastically; and a metallic shim foil 60 disposed between the bearing housing 20 and the bump foil 40. The shim foil 60 is integrally molded with one of the top foil 30 and the bump foil 40.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a foil bearing. [Background technology]

[0002] The foil bearing described in Patent Document 1 includes a cylindrical bearing housing through which a rotating shaft is inserted, a top foil, and a bump foil. The top foil is disposed between the rotating shaft and the bearing housing. The bump foil elastically supports the top foil between the bearing housing and the top foil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-89384 A Summary of the Invention [Problem to be solved by the invention]

[0004] The bump foil and the bearing housing are made of metal. In this case, depending on the metal used, the hardness of the metal forming the bump foil may be greater than the hardness of the metal forming the bearing housing. In such a case, when the bump foil elastically deforms to expand and contract in the circumferential direction of the bearing housing, if the outer circumferential surface of the bump foil displaces while contacting the inner circumferential surface of the bearing housing, wear may occur in the bearing housing.

[0005] The wear of the bearing housing can be suppressed by disposing a shim foil between the bearing housing and the bump foil. However, in this case, there is a concern that the number of steps required to manufacture the foil bearing will increase when disposing the shim foil on the foil bearing. [Means for solving the problem]

[0006] A foil bearing for solving the above problem comprises a cylindrical, metallic bearing housing through which a rotating shaft is inserted, a top foil arranged between the rotating shaft and the bearing housing and constituting a bearing surface extending in a circumferential direction of the rotating shaft relative to the rotating shaft, a metallic bump foil arranged on the opposite side of the rotating shaft with the top foil between them and elastically supporting the top foil by stretching, and a metallic shim foil arranged between the bearing housing and the bump foil and extending in the circumferential direction, wherein the hardness of the shim foil is higher than the hardness of the bearing housing, and the shim foil is molded integrally with either the top foil or the bump foil.

[0007] A foil bearing for solving the above-mentioned problems includes a cylindrical, metallic bearing housing through which a rotating shaft is inserted, a top foil that is disposed between the rotating shaft and the bearing housing and constitutes a bearing surface that extends in a circumferential direction of the rotating shaft with respect to the rotating shaft, a metallic bump foil that is disposed on the opposite side of the rotating shaft with the top foil therebetween and that stretches to elastically support the top foil, and a plurality of metallic shim foils that are disposed between the bearing housing and the bump foil and are disposed in the circumferential direction, the hardness of the shim foil being higher than the hardness of the bearing housing, The bump foils are each integrally molded in one of the circumferentially adjacent bump foils, and the shim foil molded integrally with one of the bump foils extends between the other bump foil and the bearing housing, a groove is formed in the bearing housing that opens onto the inner surface of the bearing housing, one of the shim foils has a through hole that passes through it so as to face the groove, and a fixed end of the bump foil molded integrally with the other shim foil passes through the through hole and is inserted into the groove, thereby being fixed to the bearing housing.

[0008] According to the above configuration, the foil bearing includes a shim foil disposed between the bearing housing and the bump foil. Therefore, when the bump foil elastically deforms to expand and contract in the circumferential direction of the bearing housing, the outer peripheral surface of the bump foil is displaced while contacting the inner peripheral surface of the shim foil. Therefore, by disposing the shim foil in the foil bearing, wear of the bearing housing can be suppressed. In addition, the shim foil is molded integrally with either the top foil or the bump foil. Therefore, the shim foil can be disposed in the bearing housing at the same time as disposing either the top foil or the bump foil in the bearing housing. Therefore, an increase in the number of steps required for manufacturing the foil bearing when disposing the shim foil in the foil bearing can be suppressed.

[0009] In a foil bearing, the shim foil is molded integrally with the top foil, and a first bent portion is provided between the shim foil and the top foil, the first bent portion being bent so that the shim foil is positioned on the opposite side of the top foil with the bump foil sandwiched therebetween, and a groove is formed in the bearing housing, opening into an inner surface of the bearing housing, and the first bent portion may be inserted into the groove.

[0010] According to the above configuration, in the member in which the top foil, which is integrally formed with the shim foil, the shim foil, and the first bent portion are integrated, the first bent portion has a thickness greater than the other portions. By inserting the first bent portion having such a large thickness into the groove, the portion of the first bent portion located in the space between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing housing can be reduced. Therefore, it is possible to suppress the space between the rotating shaft and the inner peripheral surface of the bearing housing from being increased in consideration of the thickness of the first bent portion.

[0011] In the foil bearing, the shim foil is molded integrally with the bump foil, and a second bent portion is provided between the shim foil and the bump foil so that the shim foil and the bump foil overlap in the radial direction of the rotating shaft, and a groove is formed in the bearing housing that opens into an inner surface of the bearing housing, and the second bent portion may be inserted into the groove.

[0012] According to the above configuration, in the member in which the bump foil, which is molded integrally with the shim foil, the shim foil, and the second bent portion are integrated, the second bent portion has a thickness greater than the other portions. By inserting the second bent portion having such a large thickness into the groove, the portion of the second bent portion located in the space between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing housing can be reduced. Therefore, it is possible to suppress the space between the rotating shaft and the inner peripheral surface of the bearing housing from being increased in consideration of the thickness of the second bent portion.

[0013] In the foil bearing, both surfaces of the bump foil may be surface-treated. According to the above configuration, when the bump foil elastically deforms so as to expand and contract in the circumferential direction of the bearing housing, wear of the top foil and the shim foil that may occur when the bump foil is displaced while in contact with the top foil and the shim foil can be suppressed. Effect of the Invention

[0014] According to this invention, by arranging a shim foil on the foil bearing, wear on the bearing housing can be suppressed, while an increase in the number of manufacturing steps for the foil bearing can be suppressed when arranging the shim foil on the foil bearing. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic configuration diagram showing a centrifugal compressor. [Diagram 2] FIG. 2 is a front view showing the foil bearing in the first embodiment. [Diagram 3] FIG. 3 is an exploded perspective view showing the foil bearing in the first embodiment. [Figure 4] FIG. 4 is an enlarged front view showing a part of the foil bearing in the first embodiment. [Diagram 5] FIG. 5 is a front view showing a foil bearing in the second embodiment. [Figure 6] FIG. 6 is a front view showing a foil bearing in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [First embodiment] A first embodiment of a foil bearing will be described below with reference to the drawings. The foil bearing of this embodiment is mounted on a centrifugal compressor. The centrifugal compressor is mounted on a fuel cell vehicle. The centrifugal compressor compresses air as a fluid to be supplied to a fuel cell stack.

[0017] <Schematic configuration of centrifugal compressor> As shown in FIG. 1, the centrifugal compressor 100 includes two foil bearings 10, a housing 101, a motor 102, a rotating shaft 103, and an impeller 104. The motor 102, the rotating shaft 103, and the impeller 104 are accommodated in the housing 101. A motor chamber 101a and an impeller chamber 101b are formed in the housing 101. The motor 102 is accommodated in the motor chamber 101a. The impeller 104 is accommodated in the impeller chamber 101b. The rotating shaft 103 extends from the motor chamber 101a to the impeller chamber 101b. The motor 102 is attached to the rotating shaft 103. The impeller 104 is attached to an end of the rotating shaft 103. The rotating shaft 103 rotates when the motor 102 is driven. The impeller 104 rotates integrally with the rotating shaft 103 as the rotating shaft 103 rotates. As the impeller 104 rotates, air is drawn into the impeller chamber 101b from outside the housing 101, and the air drawn into the impeller chamber 101b is compressed by the rotation of the impeller 104. The air compressed by the rotation of the impeller 104 is discharged to the outside of the housing 101.

[0018] <Foil bearings> The two foil bearings 10 support the rotating shaft 103 in a radial direction Rd. The radial direction Rd is the radial direction of the rotating shaft 103. The two foil bearings 10 are provided at positions sandwiching the motor 102 in the axial direction of the rotating shaft 103. The two foil bearings 10 are fixed to a housing 101.

[0019] 2 and 3, the foil bearing 10 includes a cylindrical metallic bearing housing 20, a top foil 30, a metallic bump foil 40, and a metallic shim foil 60. The foil bearing 10 further includes a pair of retaining members 50.

[0020] <Bearing housing> As shown in FIG. 2, the rotating shaft 103 is inserted through the bearing housing 20. In the following description, the axial direction of the bearing housing 20 may be simply referred to as the "axial direction A", the circumferential direction of the bearing housing 20 may be simply referred to as the "circumferential direction B", and the radial direction of the bearing housing 20 may be simply referred to as the "radial direction C". The axial direction A coincides with the direction in which the axis of the rotating shaft 103 extends. The circumferential direction B coincides with the direction in which the outer peripheral surface of the rotating shaft 103 extends. The radial direction C coincides with the direction in which the outer diameter of the rotating shaft 103 extends. The bearing housing 20 in this embodiment is formed of, for example, aluminum.

[0021] 3, the inner circumferential surface 20a of the bearing housing 20 is a cylindrical surface extending in the circumferential direction B. The bearing housing 20 has a first end 21 and a second end 22. The first end 21 is an end of the bearing housing 20 located on one side in the axial direction A. The second end 22 is an end of the bearing housing 20 located on the other side in the axial direction A.

[0022] The bearing housing 20 is formed with grooves 20b that open to the inner circumferential surface 20a of the bearing housing 20. In this embodiment, four grooves 20b are provided in the bearing housing 20. The grooves 20b are located apart from each other in the circumferential direction B on the inner circumferential surface 20a of the bearing housing 20.

[0023] The four grooves 20b are also referred to as a first groove 120, a second groove 220, a third groove 320, and a fourth groove 420. The first groove 120, the second groove 220, the third groove 320, and the fourth groove 420 are arranged in this order in the circumferential direction B. The distance between the first groove 120 and the fourth groove 420 in the circumferential direction B is closer than the distance between the other grooves 20b in the circumferential direction B.

[0024] Each groove 20b extends in the axial direction A. Each groove 20b is provided over the entire length of the inner circumferential surface 20a of the bearing housing 20 in the axial direction A. A first end of each groove 20b in the axial direction A opens into an end face of the first end 21 of the bearing housing 20. A second end of each groove 20b in the axial direction A opens into an end face of the second end 22 of the bearing housing 20.

[0025] An annular notched groove 20c is formed in an end face of the first end 21 in the axial direction A and an end face of the second end 22 in the axial direction A. Each notched groove 20c is defined by a cylindrical surface 20d extending in the axial direction A and an annular surface 20e extending perpendicular to the axial direction A. Each groove 20b opens to the cylindrical surface 20d and the annular surface 20e.

[0026] <Top foil> 2, the top foil 30 is disposed inside the bearing housing 20. The top foil 30 is disposed between the rotating shaft 103 and the bearing housing 20.

[0027] As shown in Fig. 3, the top foil 30 is formed by bending a long, flexible metal plate into a cylindrical shape. The top foil 30 is approximately cylindrical. The axial direction of the top foil 30 coincides with the axial direction A of the bearing housing 20. The circumferential direction of the top foil 30 coincides with the circumferential direction B of the bearing housing 20. The radial direction of the top foil 30 coincides with the radial direction C of the bearing housing 20. The length of the top foil 30 in the axial direction A is, for example, the same as the length of the bearing housing 20 in the axial direction A.

[0028] The top foil 30 in this embodiment is made of, for example, stainless steel or an Inconel (registered trademark) type nickel alloy, and therefore has a higher hardness than the bearing housing 20 made of aluminum.

[0029] The top foil 30 has a first insertion portion 31. The first insertion portion 31 is provided at both ends of the top foil 30 in the circumferential direction B. The first insertion portion 31 is formed by bending one end and the other end of the top foil 30 in the circumferential direction B toward the outside of the top foil 30 in the radial direction C. The first insertion portion 31 is a plate extending perpendicular to the circumferential direction B. The length in the axial direction A of the first insertion portion 31 is shorter than the length in the axial direction A of a portion of the top foil 30 other than the first insertion portion 31 and formed in a substantially cylindrical shape, for example. The first insertion portion 31 located at one end of the top foil 30 in the circumferential direction B is inserted into the first groove 120. The first insertion portion 31 located at the other end of the top foil 30 in the circumferential direction B is inserted into the fourth groove 420.

[0030] The inner circumferential surface of the portion of the top foil 30 other than the first insertion portion 31 that is formed into a substantially cylindrical shape serves as a bearing surface 30a. The bearing surface 30a is a surface that supports the rotating shaft 103. Therefore, the top foil 30 constitutes the bearing surface 30a that extends in the circumferential direction B of the rotating shaft 103 with respect to the rotating shaft 103.

[0031] <Bump foil> As shown in FIG. 2, the bump foil 40 is disposed between the bearing housing 20 and the top foil 30. The bump foil 40 is provided on the opposite side of the rotating shaft 103 with the top foil 30 sandwiched therebetween. The bump foil 40 elastically supports the top foil 30 between the bearing housing 20 and the top foil 30. The bump foil 40 elastically supports the top foil 30 by stretching. The length of the bump foil 40 in the axial direction A is, for example, shorter than the length of the axial direction A of the bearing housing 20. The plate thickness of the bump foil 40 may be the same as or different from the plate thickness of the top foil 30. For example, the plate thickness of the bump foil 40 may be thinner than the plate thickness of the top foil 30.

[0032] The foil bearing 10 includes a plurality of bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20. The plurality of bump foils 40 are spaced apart from each other in the circumferential direction B. The foil bearing 10 in this embodiment includes three bump foils 40. The three bump foils 40 are also referred to as a first bump foil 140, a second bump foil 240, and a third bump foil 340. The first bump foil 140, the second bump foil 240, and the third bump foil 340 are arranged in this order in the circumferential direction B.

[0033] Both sides of the bump foil 40 are surface-treated. On both sides of the bump foil 40, a surface treatment layer 40a such as a diamond-like carbon (DLC) coating, Ni plating, Cr plating, etc. is formed. In addition, for example, PTFE, MoS2, etc. may be added as a solid lubricant. In this embodiment, the bump foil 40 is formed of, for example, stainless steel or an Inconel (registered trademark) type nickel alloy. Therefore, the bump foil 40 has a hardness higher than that of the bearing housing 20. The metal forming the bump foil 40 may be the same as or different from the metal forming the top foil 30.

[0034] Each bump foil 40 has a plurality of valleys 43 and a plurality of peaks 44. Each valley 43 extends in the circumferential direction B. Each peak 44 contacts the outer peripheral surface of the top foil 30. In detail, each peak 44 contacts the outer peripheral surface of the top foil 30 via a surface treatment layer 40a provided on each peak 44.

[0035] Each peak 44 protrudes in a direction away from the inner peripheral surface 20a of the bearing housing 20. Each peak 44 is curved in an arc shape so as to bulge toward the outer peripheral surface of the top foil 30. Each bump foil 40 has a wave shape in which a plurality of valleys 43 and peaks 44 are alternately provided in the circumferential direction B. The valleys 43 are located at both ends of each bump foil 40 in the circumferential direction B.

[0036] Each bump foil 40 has a second insertion portion 41. The second insertion portion 41 is formed by bending a part of the valley portion 43 located at the end of the bump foil 40 in the circumferential direction B, including one end of the bump foil 40 in the circumferential direction B, toward the opposite side to the peak portion 44. The second insertion portion 41 is in the shape of a plate extending perpendicular to the circumferential direction B. The length in the axial direction A of the second insertion portion 41 is, for example, the same as the length in the axial direction A of the part of the bump foil 40 other than the second insertion portion 41. Of both ends of each bump foil 40 in the circumferential direction B, the end where the second insertion portion 41 is not provided is a free end.

[0037] The second insertion portion 41 of each bump foil 40 is inserted into the groove 20b. In detail, the second insertion portion 41 of the first bump foil 140 is inserted into the first groove 120. The second insertion portion 41 of the second bump foil 240 is inserted into the second groove 220. The second insertion portion 41 of the third bump foil 340 is inserted into the third groove 320. The first insertion portion 31 and the second insertion portion 41 inserted into the first groove 120 are adjacent to each other in the circumferential direction B inside the first groove 120. Inside the first groove 120, the first insertion portion 31 and the second insertion portion 41 may be in contact with each other in the circumferential direction B or may be separated from each other.

[0038] <Simfoil> The shim foil 60 is disposed inside the bearing housing 20. The shim foil 60 is disposed between the bearing housing 20 and the bump foil 40. The length of the shim foil 60 in the axial direction A is, for example, shorter than the length of the bearing housing 20 in the axial direction A. The plate thickness of the shim foil 60 may be the same as or different from the plate thickness of the top foil 30. For example, the plate thickness of the shim foil 60 may be thinner than the plate thickness of the top foil 30.

[0039] The shim foil 60 extends in the circumferential direction B. The shim foil 60 in this embodiment is a plurality of shim foils 60 provided in the circumferential direction B. That is, the foil bearing 10 includes a plurality of shim foils 60 adjacent to each other in the circumferential direction B of the bearing housing 20. The plurality of shim foils 60 are located apart from each other in the circumferential direction B. The foil bearing 10 in this embodiment includes three shim foils 60. That is, the foil bearing 10 includes the same number of shim foils 60 as the bump foils 40. The three shim foils 60 are also referred to as a first shim foil 160, a second shim foil 260, and a third shim foil 360. The first shim foil 160, the second shim foil 260, and the third shim foil 360 are arranged in this order in the circumferential direction B.

[0040] In this embodiment, each shim foil 60 is formed of, for example, stainless steel or an Inconel (registered trademark) type nickel alloy. Therefore, each shim foil 60 has a hardness higher than that of the bearing housing 20. The metal forming each shim foil 60 in this embodiment is the same as the metal forming the bump foil 40. The metal forming each shim foil 60 may be the same as the metal forming the top foil 30 or may be different.

[0041] The shim foils 60 extend in the circumferential direction B. The outer peripheral surface of each shim foil 60 contacts the inner peripheral surface 20a of the bearing housing 20. The inner peripheral surface of the shim foil 60 contacts the outer peripheral surface of the valley portion 43 of the bump foil 40. In detail, the inner peripheral surface of the shim foil 60 contacts the valley portion 43 via the surface treatment layer 40a provided in each valley portion 43. The inner peripheral surface of the first shim foil 160 contacts the outer peripheral surface of the valley portion 43 of the first bump foil 140. The inner peripheral surface of the second shim foil 260 contacts the outer peripheral surface of the valley portion 43 of the second bump foil 240. The inner peripheral surface of the third shim foil 360 contacts the outer peripheral surface of the valley portion 43 of the third bump foil 340. Thus, the first shim foil 160 is disposed between the bearing housing 20 and the first bump foil 140. The second shim foil 260 is disposed between the bearing housing 20 and the second bump foil 240. The third shim foil 360 is disposed between the bearing housing 20 and the third bump foil 340.

[0042] Each shim foil 60 has a third insertion portion 61. The third insertion portion 61 is formed by bending a part of the shim foil 60 including one end of the shim foil 60 in the circumferential direction B outward in the radial direction C. The third insertion portion 61 is plate-shaped extending perpendicular to the circumferential direction B. The length in the axial direction A of the third insertion portion 61 is, for example, the same as the length in the axial direction A of the portion of the shim foil 60 other than the third insertion portion 61. Of both ends of each shim foil 60 in the circumferential direction, the end where the third insertion portion 61 is not provided is a free end.

[0043] The third insertion portion 61 of each shim foil 60 is inserted into the groove 20b. In particular, the third insertion portion 61 of the first shim foil 160 is inserted into the first groove 120. The third insertion portion 61 of the second shim foil 260 is inserted into the second groove 220. The third insertion portion 61 of the third shim foil 360 is inserted into the third groove 320.

[0044] The third insertion portion 61 is inserted into the groove 20b together with the second insertion portion 41. Inside the groove 20b, the second insertion portion 41 and the third insertion portion 61 are spaced apart from each other in the circumferential direction B. <Preventive material> 3, each of the pair of retaining members 50 is annular. Each retaining member 50 is made of, for example, stainless steel. The hardness of each retaining member 50 is lower than the hardness of the top foil 30 and the bump foil 40, for example.

[0045] The inner diameter of the retaining members 50 is the same as the outer diameter of the bearing housing 20. One of the pair of retaining members 50 is fitted into a notched groove 20c formed in the first end 21 of the bearing housing 20. The other of the pair of retaining members 50 is fitted into a notched groove 20c formed in the second end 22 of the bearing housing 20.

[0046] The pair of retaining members 50 are fixed to the bearing housing 20 by fixing means (not shown). Each retaining member 50 abuts against the annular surface 20e. Each retaining member 50 faces the opening of the groove 20b in the annular surface 20e in the axial direction A. The pair of retaining members 50 cover the groove 20b.

[0047] Each of the retaining members 50 faces the first insertion portion 31, the second insertion portion 41, and the third insertion portion 61 in the axial direction A. In detail, the portion of the pair of retaining members 50 that covers the first groove 120 faces the first insertion portion 31, the second insertion portion 41, and the third insertion portion 61 inserted into the first groove 120 in the axial direction A. The portion of the pair of retaining members 50 that covers the second groove 220 faces the second insertion portion 41 and the third insertion portion 61 inserted into the second groove 220 in the axial direction A. The portion of the pair of retaining members 50 that covers the third groove 320 faces the second insertion portion 41 and the third insertion portion 61 inserted into the third groove 320 in the axial direction A. The portion of the pair of retaining members 50 that covers the fourth groove 420 faces the first insertion portion 31 inserted into the fourth groove 420 in the axial direction A. In this manner, the pair of retaining members 50 face the first insertion portion 31, the second insertion portion 41, and the third insertion portion 61 in the axial direction A, and thus the pair of retaining members 50 prevent the top foil 30, the bump foil 40, and the shim foil 60 from coming off the bearing housing 20. As a result, the first insertion portion 31 functions as a fixed end of the top foil 30 for fixing the top foil 30 to the bearing housing 20. The second insertion portion 41 functions as a fixed end of the bump foil 40 for fixing the bump foil 40 to the bearing housing 20. The third insertion portion 61 functions as a fixed end of the shim foil 60 for fixing the shim foil 60 to the bearing housing 20.

[0048] <Details of Bump Foil and Shim Foil> The shim foil 60 is molded integrally with either the top foil 30 or the bump foil 40. The shim foil 60 in this embodiment is molded integrally with the bump foil 40. Therefore, the hardness of the shim foil 60 is higher than the hardness of the bearing housing 20.

[0049] Each of the multiple shim foils 60 is integral with each of the multiple bump foils 40. In particular, the first shim foil 160 is integral with the first bump foil 140. The second shim foil 260 is integral with the second bump foil 240. The third shim foil 360 is integral with the third bump foil 340. A member including the first shim foil 160 and the first bump foil 140 is also referred to as a first foil 71. A member including the second shim foil 260 and the second bump foil 240 is also referred to as a second foil 72. A member including the third shim foil 360 and the third bump foil 340 is also referred to as a third foil 73.

[0050] Each of the first foil 71, the second foil 72, and the third foil 73 is formed from a long, flexible metal plate. Of the first foil 71, the second foil 72, and the third foil 73, the bump foil 40 is formed by curving a part of the metal plate in the longitudinal direction, including one end of the metal plate in the longitudinal direction, into a substantially arc shape, and curving the part to form a valley portion 43 and a peak portion 44. Of the first foil 71, the second foil 72, and the third foil 73, the shim foil 60 is formed by curving a part of the metal plate in the longitudinal direction, including the other end of the metal plate in the longitudinal direction, into a substantially arc shape.

[0051] The metal plate is bent between the bump foil 40 and the shim foil 60 in the longitudinal direction of the metal plate. As a result, each of the first foil 71, the second foil 72, and the third foil 73 is formed such that the inner peripheral surface of the shim foil 60 extends along the outer peripheral surface of the valley portion 43 of the bump foil 40. In other words, the foil bearing 10 includes a bent portion 80 that is bent between the shim foil 60 and the bump foil 40 that is integral with the shim foil 60.

[0052] <Bending part> As shown in FIG. 4, the bent portion 80 is composed of the second insertion portion 41, the third insertion portion 61, and a connecting portion 81. The bent portion 80 in this embodiment corresponds to the second bent portion. The bent portion 80 as the second bent portion is provided between the shim foil 60 and the bump foil 40. Furthermore, the bent portion 80 as the second bent portion is bent so that the shim foil 60 and the bump foil 40 overlap in the radial direction C of the rotation shaft 103. The connecting portion 81 connects the end portion in the radial direction C of the second insertion portion 41 constituting the end portion of the bump foil 40 and the end portion in the radial direction C of the third insertion portion 61 constituting the end portion of the shim foil 60. The end portion in the radial direction C of the second insertion portion 41 connected by the connecting portion 81 corresponds to the longitudinal end portion of the bump foil 40. The end portion in the radial direction C of the third insertion portion 61 to which the connecting portion 81 is connected corresponds to the end portion of the shim foil 60 in the longitudinal direction.

[0053] The connecting portion 81 is a flat plate extending perpendicular to the radial direction C. The bent portion 80 is bent at the boundary between the second insertion portion 41 and the connecting portion 81, and is bent at the boundary between the third insertion portion 61 and the connecting portion 81. The outer side of the bent portion 80 in the radial direction C is closed by the connecting portion 81. The inner side of the bent portion 80 in the radial direction C is open. Both ends of the bent portion 80 in the axial direction A are open. In the bent portion 80, the space partitioned by the second insertion portion 41, the third insertion portion 61, and the connecting portion 81 communicates with the outside of the bent portion 80 on the inner side in the radial direction C and on both sides in the axial direction A.

[0054] 2, the bent portion 80 is provided in each of the first foil 71, the second foil 72, and the third foil 73. Therefore, in each of the first foil 71, the second foil 72, and the third foil 73, the connecting portion 81 connects the second insertion portion 41 and the third insertion portion 61.

[0055] The bent portion 80 as the second bent portion is inserted into the groove 20b. That is, the connecting portion 81 is inserted into the groove 20b together with the second insertion portion 41 and the third insertion portion 61. The bent portion 80 of the first foil 71 is inserted into the first groove 120. The bent portion 80 of the second foil 72 is inserted into the second groove 220. The bent portion 80 of the third foil 73 is inserted into the third groove 320. In each of the first foil 71, the second foil 72, and the third foil 73, the bent portion 80 including the connecting portion 81 faces each of the anti-dislodgement members 50 in the axial direction A.

[0056] [Operation of the first embodiment] Next, the operation of the first embodiment will be described. 2, when the rotating shaft 103 rotates in a rotation direction D and the rotation speed of the rotating shaft 103 reaches a predetermined rotation speed, an air film is formed between the rotating shaft 103 and the top foil 30. As a result, the rotating shaft 103 floats above the top foil 30. Then, the rotating shaft 103 is supported in the radial direction Rd by the air film in a non-contact state with the top foil 30.

[0057] When the air film is formed as described above, the top foil 30 is displaced outward in the radial direction C. As the top foil 30 is displaced in this manner, a load is input from the top foil 30 to each peak portion 44 of the bump foil 40. The load input from the top foil 30 to each peak portion 44 causes the bump foil 40 to elastically deform so as to expand and contract in the circumferential direction B. As a result, the top foil 30 is elastically supported by the bump foil 40.

[0058] The outer peripheral surface of the valley portion 43 of the bump foil 40 is in contact with the inner peripheral surface of the shim foil 60. Therefore, as the bump foil 40 expands and contracts in the circumferential direction B, the outer peripheral surface of the valley portion 43 of the bump foil 40 is displaced while in contact with the inner peripheral surface of the shim foil 60.

[0059] Furthermore, when assembling the foil bearing 10, the top foil 30 and the bump foil 40 are sequentially arranged inside the bearing housing 20. At this time, the shim foil 60 is integrally formed with the bump foil 40. In detail, the first shim foil 160 is integral with the first bump foil 140. The second shim foil 260 is integral with the second bump foil 240. The third shim foil 360 is integral with the third bump foil 340. Therefore, the shim foil 60 can be arranged in the bearing housing 20 at the same time that the bump foil 40 is arranged in the bearing housing 20.

[0060] [Effects of the first embodiment] According to the first embodiment, the following effects can be obtained. (1-1) The foil bearing 10 includes a shim foil 60 disposed between the bearing housing 20 and the bump foil 40. Therefore, when the bump foil 40 elastically deforms to expand and contract in the circumferential direction B of the bearing housing 20, the outer peripheral surface of the bump foil 40 is displaced while contacting the inner peripheral surface of the shim foil 60. Therefore, by disposing the shim foil 60 in the foil bearing 10, wear of the bearing housing 20 can be suppressed. In addition, the shim foil 60 is molded integrally with the bump foil 40. Therefore, the shim foil 60 can be disposed in the bearing housing 20 at the same time as disposing the bump foil 40 in the bearing housing 20. Therefore, an increase in the number of manufacturing steps of the foil bearing 10 when disposing the shim foil 60 in the foil bearing 10 can be suppressed.

[0061] (1-2) The shim foil 60 is molded integrally with the bump foil 40. Between the shim foil 60 and the bump foil 40, a bent portion 80 is provided as a second bent portion where the shim foil 60 and the bump foil 40 are bent so as to overlap in the radial direction C of the rotating shaft 103. A groove 20b that opens to the inner peripheral surface 20a of the bearing housing 20 is formed in the bearing housing 20. The bent portion 80 as the second bent portion is inserted into the groove 20b. In the member in which the bump foil 40, the shim foil 60, and the bent portion 80 as the second bent portion are integrated, which are molded integrally with the shim foil 60, are integrated, the bent portion 80 is thicker than the portions other than the bent portion 80. By inserting the bent portion 80 having such a large thickness into the groove 20b, the portion of the bent portion 80 located in the space between the outer peripheral surface of the rotating shaft 103 and the inner peripheral surface 20a of the bearing housing 20 can be reduced. Therefore, the space between the rotating shaft 103 and the inner circumferential surface 20a of the bearing housing 20 can be prevented from becoming large in consideration of the thickness of the bent portion 80.

[0062] (1-3) Both sides of the bump foil 40 are surface-treated. Therefore, when the bump foil 40 elastically deforms to expand and contract, wear of the top foil 30 and the shim foil 60 that may occur when the bump foil 40 is displaced while in contact with the top foil 30 and the shim foil 60 can be suppressed.

[0063] (1-4) The foil bearing 10 includes a plurality of bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20. The foil bearing 10 includes shim foils 60 in the same number as the bump foils 40. Each of the plurality of shim foils 60 is integrated with each of the plurality of bump foils 40. It is considered that the number of shim foils 60 included in the foil bearing 10 is less than the number of bump foils 40. In this case, it is considered that the shim foil 60 having a length in the circumferential direction B longer than the length in the circumferential direction B of the bump foil 40 is integrated with the bump foil 40 so that it can be positioned between the plurality of bump foils 40 and the inner peripheral surface 20a of the bearing housing 20. In such a case, when a member in which the bump foil 40 and the shim foil 60 are integrated is disposed inside the bearing housing 20, it is necessary to dispose the shim foil 60 so as to be positioned along the bump foil 40 of the member and the other bump foil 40 adjacent thereto. According to the above embodiment, each of the multiple shim foils 60 is integrated with each of the multiple bump foils 40. Therefore, by arranging the shim foil 60 together with the bump foil 40 inside the bearing housing 20, the shim foil 60 is positioned along the bump foil 40. Therefore, since it is not necessary to arrange the shim foil 60 so as to be positioned along the bump foil 40 as described above, the foil bearing 10 can be manufactured easily.

[0064] [Second embodiment] A second embodiment of the foil bearing will be described below with reference to the drawings. The foil bearing in the second embodiment differs from the foil bearing in the first embodiment in the shapes of the bump foil 40 and the shim foil 60. The following description will focus on the configurations that differ from the first embodiment. Descriptions of the same configurations as the first embodiment will be omitted as appropriate.

[0065] <Bump foil> As shown in FIG. 5, the bump foil 40 in the second embodiment elastically supports the top foil 30 between the bearing housing 20 and the top foil 30, similar to the bump foil 40 in the first embodiment. The bump foil 40 is provided on the opposite side of the rotating shaft 103 with the top foil 30 sandwiched therebetween. The bump foil 40 elastically supports the top foil 30 by stretching. The foil bearing 10 includes a plurality of bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20. The foil bearing 10 in this embodiment includes three bump foils 40. Both sides of the bump foil 40 are surface-treated. That is, a surface treatment layer 40a is formed on both sides of the bump foil 40. The bump foil 40 in this embodiment is formed of, for example, stainless steel or an Inconel (registered trademark) type nickel alloy. Therefore, the bump foil 40 has a hardness higher than that of the bearing housing 20.

[0066] <Simfoil> The shim foil 60 in this embodiment is disposed between the bearing housing 20 and the bump foil 40, similarly to the shim foil 60 in the first embodiment. The shim foil 60 is a plurality of shim foils 60 arranged in the circumferential direction B. As in the first embodiment, the foil bearing 10 in this embodiment includes three shim foils 60. That is, the foil bearing 10 includes the same number of shim foils 60 as the bump foils 40. As in the first embodiment, each shim foil 60 in this embodiment is formed of, for example, stainless steel or an Inconel (registered trademark) type nickel alloy. As in the first embodiment, the metal forming each shim foil 60 in this embodiment is the same as the metal forming the bump foil 40.

[0067] As in the first embodiment, each shim foil 60 in this embodiment extends in the circumferential direction B. The outer peripheral surface of each shim foil 60 contacts the inner peripheral surface 20a of the bearing housing 20. The inner peripheral surface of the shim foil 60 contacts the outer peripheral surface of the valley portion 43 of the bump foil 40. In detail, the inner peripheral surface of the shim foil 60 contacts the valley portion 43 via the surface treatment layer 40a provided in each valley portion 43.

[0068] In this embodiment, the inner peripheral surface of the first shim foil 160 contacts the outer peripheral surface of the valley portion 43 of the second bump foil 240. The inner peripheral surface of the second shim foil 260 contacts the outer peripheral surface of the valley portion 43 of the third bump foil 340. The inner peripheral surface of the third shim foil 360 contacts the outer peripheral surface of the valley portion 43 of the first bump foil 140. Therefore, the first shim foil 160 is disposed between the bearing housing 20 and the second bump foil 240. The second shim foil 260 is disposed between the bearing housing 20 and the third bump foil 340. The third shim foil 360 is disposed between the bearing housing 20 and the first bump foil 140.

[0069] In this embodiment, each shim foil 60 does not have a third insertion portion 61 as in the first embodiment. Therefore, in this embodiment, a part of each shim foil 60 is not inserted into the groove 20b. As a result, the shim foil 60 in this embodiment does not face each of the retaining members 50 in the axial direction A.

[0070] <Details of Bump Foil and Shim Foil> The shim foil 60 is integrally formed with either the top foil 30 or the bump foil 40. As in the first embodiment, the plurality of shim foils 60 in this embodiment are each integrally formed with the bump foil 40. Therefore, the hardness of the shim foil 60 is higher than the hardness of the bearing housing 20.

[0071] As in the first embodiment, the first shim foil 160 is integrally formed with the first bump foil 140. The second shim foil 260 is integrally formed with the second bump foil 240. The third shim foil 360 is integrally formed with the third bump foil 340. As in the first embodiment, a member including the first shim foil 160 and the first bump foil 140 is also referred to as a first foil 71. A member including the second shim foil 260 and the second bump foil 240 is also referred to as a second foil 72. A member including the third shim foil 360 and the third bump foil 340 is also referred to as a third foil 73.

[0072] Each of the first foil 71, the second foil 72, and the third foil 73 is formed from a long, flexible metal plate. Of the first foil 71, the second foil 72, and the third foil 73, the bump foil 40 is formed by curving a part of the metal plate in the longitudinal direction, including one end of the metal plate in the longitudinal direction, into a substantially arc shape, and curving to form a valley portion 43 and a peak portion 44. Of the first foil 71, the second foil 72, and the third foil 73, the shim foil 60 is formed by curving a part of the metal plate in the longitudinal direction, including the other end of the metal plate in the longitudinal direction, into a substantially arc shape, as in the first embodiment.

[0073] In this embodiment, the metal plate is not bent between the bump foil 40 and the shim foil 60 in the longitudinal direction of the metal plate. Therefore, in each of the first foil 71, the second foil 72, and the third foil 73, the shim foil 60 extends in the same direction as the extension direction of the bump foil 40.

[0074] In this embodiment, of both ends of each bump foil 40 in the circumferential direction B, a second insertion portion 41 that functions as a fixed end of the bump foil 40 is provided at one end as in the first embodiment, and a shim foil 60 extends from the other end. In detail, the first shim foil 160 extends from an end of the first bump foil 140 in the circumferential direction B. The second shim foil 260 extends from an end of the second bump foil 240 in the circumferential direction B. The third shim foil 360 extends from an end of the third bump foil 340 in the circumferential direction B. Also, of both ends of each shim foil 60 in the circumferential direction B, the end opposite to the end connected to the bump foil 40 is a free end.

[0075] A through hole 60h is provided in each shim foil 60. The through hole 60h penetrates the shim foil 60 in the thickness direction. One through hole 60h is formed in each of the first shim foil 160 and the second shim foil 260. Two through holes 60h are formed in the third shim foil 360.

[0076] Of the bump foils 40 adjacent in the circumferential direction B, the shim foil 60 molded integrally with one of the bump foils 40 extends between the other bump foil 40 and the bearing housing 20. In detail, the combination of two adjacent bump foils 40 in the circumferential direction B of the bearing housing 20 includes the combination of the first bump foil 140 and the second bump foil 240, and the combination of the second bump foil 240 and the third bump foil 340. Furthermore, the combination of two adjacent bump foils 40 in the circumferential direction B of the bearing housing 20 includes the combination of the third bump foil 340 and the first bump foil 140.

[0077] The first shim foil 160 extends from an end portion of the first bump foil 140 adjacent to the second bump foil 240 in the circumferential direction B between the second bump foil 240 and the bearing housing 20. The second shim foil 260 extends from an end portion of the second bump foil 240 adjacent to the third bump foil 340 in the circumferential direction B between the third bump foil 340 and the bearing housing 20. The third shim foil 360 extends from an end portion of the third bump foil 340 adjacent to the first bump foil 140 in the circumferential direction B between the first bump foil 140 and the bearing housing 20.

[0078] The shim foil 60 is disposed such that the through hole 60h formed in the shim foil 60 faces the groove 20b in the radial direction C. The through hole 60h formed in the first shim foil 160 faces the second groove 220 in the radial direction C. The through hole 60h formed in the second shim foil 260 faces the third groove 320 in the radial direction C. Of the two through holes 60h formed in the third shim foil 360, one through hole 60h faces the fourth groove 420 in the radial direction C, and the other through hole 60h faces the first groove 120 in the radial direction C.

[0079] The first insertion portion 31 and the second insertion portion 41 are inserted into the groove 20b through a through hole 60h formed in the shim foil 60. In detail, the second insertion portion 41 of the second bump foil 240 is inserted into the second groove 220 through a through hole 60h formed in the first shim foil 160. The second insertion portion 41 of the third bump foil 340 is inserted into the third groove 320 through a through hole 60h formed in the second shim foil 260. Of the two through holes 60h formed in the third shim foil 360, the second insertion portion 41 of the first bump foil 140 is inserted into the first groove 120 together with the first insertion portion 31 through one of the through holes 60h, and the first insertion portion 31 is inserted into the fourth groove 420 through the other through hole 60h. Therefore, of the shim foils 60 adjacent to each other in the circumferential direction B, one of the shim foils 60 is provided with a through hole 60h penetrating therethrough so as to face the groove 20b. The second insertion portion 41 serving as a fixed end of the bump foil 40 integrally formed with the other shim foil 60 penetrates the through hole 60h and is fixed to the bearing housing 20 by being inserted into the groove 20b.

[0080] [Actions and Effects of the Second Embodiment] According to the second embodiment, in addition to the same action as in the first embodiment and the effects (1-1) and (1-3) in the first embodiment, the following effects can be obtained.

[0081] (2-1) The foil bearing 10 includes a plurality of bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20. The shim foil 60 extends from one of the two bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20 to between the other bump foil 40 and the bearing housing 20. Furthermore, a surface treatment layer 40a is formed on both sides of the bump foil 40. If the bump foil 40 is bent at the boundary between the bump foil 40 and the shim foil 60, it is difficult to apply masking to the shim foil 60 because the gap between the bump foil 40 and the shim foil 60 is small. Therefore, in such a case, it is preferable to perform a process of forming a surface treatment layer 40a on the bump foil 40 before bending the bump foil 40 at the boundary between the bump foil 40 and the shim foil 60. However, in this case, the process of forming the bump foil 40 and the shim foil 60 from the metal plate material and the process of bending at the boundary between the bump foil 40 and the shim foil 60 are performed separately, and the process of forming the surface treatment layer 40a is performed between these processes. Therefore, the manufacturing cost of the member in which the bump foil 40 and the shim foil 60 are integrated increases. According to this embodiment, the shim foil 60 extends from one of the two bump foils 40 adjacent to each other in the circumferential direction B of the bearing housing 20 to between the other bump foil 40 and the bearing housing 20. Therefore, after completing the manufacturing of the member in which the bump foil 40 and the shim foil 60 are integrated, the surface treatment layer 40a can be applied to the bump foil 40. Therefore, the increase in the cost of manufacturing the member in which the bump foil 40 and the shim foil 60 are integrated can be suppressed.

[0082] [Example of change] The embodiment can be modified as follows: The embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction.

[0083] As shown in FIG. 6, the shim foil 60 may be integrally formed with the top foil 30. In this case, for example, as shown in FIG. 6, the foil bearing 10 includes one shim foil 60. The shim foil 60 extends in the circumferential direction B. The shim foil 60 in this modification is substantially cylindrical with both ends in the circumferential direction B spaced apart from each other. The outer peripheral surface of the shim foil 60 contacts the inner peripheral surface 20a of the bearing housing 20. The inner peripheral surface of the shim foil 60 contacts the outer peripheral surfaces of the valley portions 43 of all the bump foils 40 provided in the foil bearing 10. The shim foil 60 is disposed between all the bump foils 40 provided in the foil bearing 10 and the bearing housing 20. Of both ends of the shim foil 60 in the circumferential direction B, one end is provided with a third insertion portion 61, and the other end is a free end. The third insertion portion 61 is inserted into the groove 20b. In detail, the third insertion portion 61 is inserted into the first groove 120. The third insertion portion 61 is inserted into the first groove 120 together with the first insertion portion 31 and the second insertion portion 41. A member including the top foil 30 and the shim foil 60 is also referred to as a foil 74. The foil 74 is formed from a long, flexible metal plate. Of the foil 74, the top foil 30 is formed by curving a part of the metal plate in the longitudinal direction, including one end of the metal plate in the longitudinal direction, into a substantially arc shape. Of the foil 74, the shim foil 60 is formed by curving a part of the metal plate in the longitudinal direction, including the other end of the metal plate in the longitudinal direction, into a substantially arc shape. The metal plate is bent between the top foil 30 and the shim foil 60 in the longitudinal direction of the metal plate. As a result, the foil 74 is formed such that the inner peripheral surface of the shim foil 60 extends along the outer peripheral surface of the valley portion 43 of the bump foil 40. In other words, a bent portion 80 is provided between the shim foil 60 and the top foil 30 as a first bent portion, which bends so that the shim foil 60 is disposed on the opposite side to the top foil 30 with the bump foil 40 sandwiched therebetween. The bent portion 80 as the first bent portion bends between the shim foil 60 and the top foil 30 which is integrally formed with the shim foil 60.The bent portion 80 as the first bent portion is composed of the first insertion portion 31, the third insertion portion 61, and the connecting portion 81. The connecting portion 81 connects the end portion in the radial direction C of the first insertion portion 31 constituting the end portion of the top foil 30 and the end portion in the radial direction C of the third insertion portion 61 constituting the end portion of the shim foil 60. The connecting portion 81 is a flat plate extending perpendicular to the radial direction C. The bent portion 80 is bent at the boundary between the first insertion portion 31 and the connecting portion 81, and is bent at the boundary between the third insertion portion 61 and the connecting portion 81. The bent portion 80 as the first bent portion is inserted into the groove 20b. That is, the connecting portion 81 is inserted into the groove 20b together with the first insertion portion 31 and the third insertion portion 61. The bent portion 80 is inserted into the first groove 120. The bent portion 80 including the connecting portion 81 faces each of the retaining members 50 in the axial direction A. A through hole 60h is formed in the shim foil 60. In this modified example, two through holes 60h are formed in the shim foil 60. The shim foil 60 is disposed such that the through hole 60h formed in the shim foil 60 faces the groove 20b in the radial direction C. Of the two through holes 60h formed in the shim foil 60, one through hole 60h faces the second groove 220 in the radial direction C, and the other through hole 60h faces the third groove 320 in the radial direction C. The second insertion portion 41 is inserted into the groove 20b via the through hole 60h formed in the shim foil 60. Of the two through holes 60h formed in the shim foil 60, the second insertion portion 41 of the second bump foil 240 is inserted into the second groove 220 through one of the through holes 60h, and the second insertion portion 41 of the third bump foil 340 is inserted into the third groove 320 through the other through hole 60h.

[0084] According to the above modification, in addition to the same action as in the first embodiment and the effects (1-1) and (1-3) in the first embodiment, the following effects can be obtained. (3-1) The shim foil 60 is molded integrally with the top foil 30. Between the shim foil 60 and the top foil 30, a bent portion 80 is provided as a first bent portion that is bent so that the shim foil 60 is disposed on the opposite side to the top foil 30 with the bump foil 40 sandwiched therebetween. A groove 20b that opens to the inner peripheral surface 20a of the bearing housing 20 is formed in the bearing housing 20. The bent portion 80 as the first bent portion is inserted into the groove 20b. In the member in which the top foil 30, the shim foil 60, and the bent portion 80 as the first bent portion are integrated, which are molded integrally with the shim foil 60, are integrated, the bent portion 80 is thicker than the portions other than the bent portion 80. By inserting the bent portion 80 having such a large thickness into the groove 20b, the portion of the bent portion 80 located in the space between the outer peripheral surface of the rotating shaft 103 and the inner peripheral surface 20a of the bearing housing 20 can be reduced. Therefore, the space between the rotating shaft 103 and the inner circumferential surface 20a of the bearing housing 20 can be prevented from becoming large in consideration of the thickness of the bent portion 80.

[0085] In the above modified example, the foil bearing 10 may include a plurality of shim foils 60. In this case, for example, each of the plurality of shim foils 60 may be integrally formed with the top foil 30. In the above modified example, the number of bump foils 40 may be two or less, or four or more.

[0086] In the first embodiment, the bent portion 80 does not have to be inserted into the groove 20b. In this case, the bent portion 80 may be disposed, for example, outside the groove 20b and in the space inside the bearing housing 20.

[0087] In the first and second embodiments, the foil bearing 10 may include four or more bump foils 40. The foil bearing 10 may include two or less bump foils 40. In these modified examples, the number of shim foils 60 included in the foil bearing 10 may be changed to the same number as the number of bump foils 40. Furthermore, in these modified examples, the number of grooves 20b formed in the bearing housing 20 may be changed according to the number of bump foils 40 included in the foil bearing 10.

[0088] In the first embodiment, the foil bearing 10 may include shim foils 60 in a number different from the number of bump foils 40. For example, the number of shim foils 60 may be one or more, which is less than the number of bump foils 40. In this case, one shim foil 60 may be provided between multiple bump foils 40 and the bearing housing 20 by lengthening the dimension of one shim foil 60 in the circumferential direction B. Also, for example, the number of shim foils 60 may be more than the number of bump foils 40. In this case, multiple shim foils 60 may be provided between one bump foil 40 and the bearing housing 20 by shortening the dimension of one shim foil 60 in the circumferential direction B.

[0089] The surface treatment layer 40 a may be formed only on the surface of the bump foil 40 that faces the top foil 30 or only on the surface that faces the shim foil 60 .

[0090] The surface treatment layer 40a may be formed on at least one of the two surfaces of the shim foil 60, in addition to the bump foil 40. In a member in which the bump foil 40 and the shim foil 60 are integrated, the surface treatment layer 40a may be formed on the entire surface of this member.

[0091] The formation of the surface treatment layer 40a on the bump foil 40 may be omitted. In other words, neither of the two surfaces of the bump foil 40 may be surface treated. The fourth groove 420 may be omitted from the bearing housing 20. In this case, the first insertion portion 31 is provided at one end of the top foil 30 in the circumferential direction B, and the other end is a free end.

[0092] All of the grooves 20b may be omitted from the bearing housing 20. In this case, the top foil 30 may be supported inside the bearing housing 20 by means other than the insertion of the first insertion portion 31 into the groove 20b. The bump foil 40 may be supported inside the bearing housing 20 by means other than the insertion of the second insertion portion 41 into the groove 20b.

[0093] The application of the foil bearing 10 is not limited to the centrifugal compressor 100 . [Explanation of symbols]

[0094] B... circumferential direction, C... radial direction, 10... foil bearing, 20... bearing housing, 20a... inner surface, 20b... groove, 30... top foil, 30a... bearing surface, 40... bump foil, 60... shim foil, 60h... through hole, 80... bent portion (as first bent portion and second bent portion), 103... rotating shaft.

Claims

1. a cylindrical metal bearing housing through which a rotating shaft is inserted; a top foil disposed between the rotating shaft and the bearing housing and constituting a bearing surface extending in a circumferential direction of the rotating shaft with respect to the rotating shaft; a metallic bump foil that is provided on the opposite side of the rotation shaft with the top foil therebetween and that elastically supports the top foil by stretching; a metallic shim foil disposed between the bearing housing and the bump foil and extending in the circumferential direction; the hardness of the shim foil is greater than the hardness of the bearing housing; A foil bearing, wherein the shim foil is integrally formed with either the top foil or the bump foil.

2. The shim foil is integrally formed with the top foil, a first bent portion is provided between the shim foil and the top foil, the first bent portion being bent so that the shim foil is disposed on an opposite side to the top foil with the bump foil interposed therebetween; The bearing housing has a groove formed therein, the groove opening into an inner peripheral surface of the bearing housing, The foil bearing according to claim 1 , wherein the first bent portion is inserted into the groove.

3. the shim foil is integrally formed with the bump foil; a second bent portion is provided between the shim foil and the bump foil, the second bent portion being bent so that the shim foil and the bump foil overlap in a radial direction of the rotation shaft; The bearing housing has a groove formed therein, the groove opening into an inner peripheral surface of the bearing housing, The foil bearing according to claim 1 , wherein the second bent portion is inserted into the groove.

4. The foil bearing according to any one of claims 1 to 3, wherein both sides of the bump foil are surface-treated.

5. a cylindrical metal bearing housing through which a rotating shaft is inserted; a top foil disposed between the rotating shaft and the bearing housing and constituting a bearing surface extending in a circumferential direction of the rotating shaft with respect to the rotating shaft; a metallic bump foil that is provided on the opposite side of the rotation shaft with the top foil therebetween and that elastically supports the top foil by stretching; a plurality of metallic shim foils disposed between the bearing housing and the bump foil and arranged in the circumferential direction; the hardness of the shim foil is greater than the hardness of the bearing housing; The bump foil is integrally formed with each of the plurality of shim foils, the shim foil, which is integrally formed with one of the bump foils adjacent in the circumferential direction, extends between the other bump foil and the bearing housing; The bearing housing has a groove formed therein, the groove opening into an inner peripheral surface of the bearing housing, One of the shim foils is provided with a through hole penetrating the shim foil so as to face the groove, A foil bearing, characterized in that a fixed end of the bump foil, which is molded integrally with the other shim foil, passes through the through hole and is inserted into the groove, thereby fixing the bump foil to the bearing housing.

6. The foil bearing according to claim 5 , wherein both sides of the bump foil are surface treated.

Images