Foil bearing

Abstract

To provide a foil bearing capable of suppressing uneven wear of a top foil caused by an inclination of a bump foil with respect to the top foil.SOLUTION: A bearing housing 12 has a groove 20 into which a locking portion 43 of a bump foil 14 is inserted. The groove 20 has a first opening 20a opened to a first end surface 12b of the bearing housing 12. First and second come-off prevention members 15, 16 are provided on both sides of the locking portion 43 in an axial direction X of the bearing housing 12. In the axial direction X of the bearing housing 12, a pair of bump edges 40a, 40b of a body 40 of the bump foil 14 is positioned in an inner side of a pair of top edges 30a, 30b of a cylinder 30 of a top foil 13 in the axial direction X of the bearing housing 12. The bump foil 14 has a first protrusion 44 protruding from the first bump edge 40a positioned on the first opening 20a side of the pair of the bump edges 40a, 40b.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Patent Document 1 discloses a foil bearing that rotatably supports a rotating shaft. The foil bearing includes a cylindrical bearing housing, a thin top foil, and a thin bump foil. The rotating shaft is inserted through the bearing housing. The axial direction of the rotating shaft coincides with the axial direction of the bearing housing. The top foil is disposed between the rotating shaft and the bearing housing. The bump foil is disposed between the bearing housing and the top foil.

[0003] The top foil has a tubular portion extending in the circumferential direction of the bearing housing. The bump foil has a main body portion extending in the circumferential direction of the bearing housing and elastically supporting the top foil, and a locking portion extending from a first end of the main body portion in the circumferential direction of the bearing housing toward the bearing housing. The bearing housing has a groove recessed from the inner circumferential surface and into which the locking portion of the bump foil is inserted. The groove has an opening that opens at one end face in the axial direction of the bearing housing. A pair of regulating portions are provided on both sides of the locking portion in the axial direction of the bearing housing. This regulates movement of the locking portion in the axial direction of the bearing housing.

[0004] When assembling the foil bearing, the bump foil is inserted into the bearing housing. At this time, the locking portion is inserted into the groove from the opening. Therefore, the bump foil is inserted into the bearing housing from one axial end face to the other axial end face of the bearing housing.

[0005] Fig. 7(a) is an end view of the rotating shaft 70, the tubular portion 81 of the top foil 80, and the main body portion 91 of the bump foil 90 cut along the axial direction of the rotating shaft 70. Fig. 7(b) is a diagram showing the change in fluid pressure between the rotating shaft 70 and the tubular portion 81 of the top foil 80 in the axial direction of the rotating shaft 70.

[0006] As shown in FIG. 7(b), the fluid pressure between the rotating shaft 70 and the tubular portion 81 increases from both ends toward the center in the axial direction of the rotating shaft 70. For this reason, as shown in FIG. 7(a), the tubular portion 81 is likely to warp away from the rotating shaft 70 as it moves from both ends toward the center in the axial direction of the rotating shaft 70. Therefore, both ends of the tubular portion 81 in the axial direction of the rotating shaft 70 are more likely to come into contact with the rotating shaft 70 than the center. As a result, uneven wear occurs in the top foil 80 in the axial direction of the rotating shaft 70. In order to suppress such uneven wear of the top foil 80, the bump foil 90 may be configured, for example, as follows.

[0007] FIG. 8 is a development view of the top foil 80 and the bump foil 90. The up-down direction in FIG. 8 corresponds to the axial direction of the rotating shaft 70. The left-right direction in FIG. 8 corresponds to the circumferential direction of the rotating shaft 70. As shown in FIG. 8, the dimension L91 of the main body 91 in the axial direction of the rotating shaft 70 is smaller than the dimension L81 of the tubular portion 81 in the axial direction of the rotating shaft 70. In addition, as shown by solid lines in FIG. 8, a pair of bump edges 91a, 91b located at both ends of the main body 91 in the axial direction of the rotating shaft 70 are disposed inward of a pair of top edges 81a, 81b located at both ends of the tubular portion 81 in the axial direction of the rotating shaft 70.

[0008] In this case, the main body portion 91 is not disposed on the outer periphery of the tubular portion 81 at both ends of the tubular portion 81 in the axial direction of the rotating shaft 70. Therefore, both ends of the tubular portion 81 are easily deformed away from the rotating shaft 70. This suppresses warping of the tubular portion 81. Therefore, uneven wear of the top foil 80 due to warping of the top foil 80 is suppressed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2022-57207 Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, the locking portion 92 is provided at the first end of the main body portion 91 in the circumferential direction of the rotating shaft 70. The locking portion 92 is restricted from moving in the axial direction of the rotating shaft 70 by a pair of restricting portions (not shown). Therefore, at the first end of the main body portion 91 in the circumferential direction of the rotating shaft 70, the bump foil 90 is unlikely to move in the axial direction of the rotating shaft 70. On the other hand, at the second end of the main body portion 91 in the circumferential direction of the rotating shaft 70, the bump foil 90 is not restricted from moving in the axial direction of the rotating shaft 70. Therefore, when assembling the foil bearing, as shown by the dashed line in FIG. 8, the bump foil 90 may be inclined with respect to the top foil 80. For example, a part of the bump foil 90 is in a state of protruding from the top edge portion 81a located on one end face side of the axial direction of the bearing housing, that is, the front side in the insertion direction of the bump foil 90, out of the pair of top edges 81a, 81b.

[0011] 9, the distance from the main body 91 of the bump foil 90 to the tubular portion 81 of the top foil 80 changes in the axial direction of the rotation shaft 70. For this reason, the top foil 80 is less likely to wear where the distance from the main body 91 to the tubular portion 81 is long, whereas the top foil 80 is more likely to wear where the distance from the main body 91 to the tubular portion 81 is short. In other words, when the bump foil 90 is inclined with respect to the top foil 80, uneven wear occurs in the top foil 80 in the axial direction of the rotation shaft 70.

[0012] If the portion of the main body 91 protruding from the top edge 81a is pushed in, the inclination of the bump foil 90 relative to the top foil 80 can be suppressed. However, if the dimension L91 of the main body 91 is smaller than the dimension L81 of the tubular portion 81, the following problem occurs. As shown by the two-dot chain line in FIG. 8, if the main body 91 is pushed in to a position where the portion of the bump edge 91a located at the second end of the main body 91 in the circumferential direction of the rotation shaft 70 overlaps with the top edge 81a, the main body 91 will not protrude from the top edge 81a. Therefore, even though the bump foil 90 is inclined relative to the top foil 80, it becomes difficult to push the main body 91 in any further. [Means for solving the problem]

[0013] A foil bearing for solving the above problems includes a cylindrical bearing housing through which a rotating shaft is inserted, a thin top foil arranged between the rotating shaft and the bearing housing, and a thin bump foil arranged between the bearing housing and the top foil, wherein the top foil has a cylindrical portion extending in the circumferential direction of the bearing housing, the bump foil has a main body portion extending in the circumferential direction of the bearing housing and elastically supporting the top foil, and a locking portion extending from a first end of the main body portion in the circumferential direction of the bearing housing toward the bearing housing, and the bearing housing is recessed from an inner circumferential surface thereof and The gist of the invention is that the foil bearing has a groove into which the locking portion is inserted, the groove having an opening that opens at one end face of the axial direction of the bearing housing, a pair of regulating portions are provided on both sides of the locking portion in the axial direction of the bearing housing, a pair of bump edge portions located at both ends of the main body portion in the axial direction of the bearing housing are located more inward in the axial direction of the bearing housing than a pair of top edge portions located at both ends of the tubular portion in the axial direction of the bearing housing, and the bump foil has a protruding portion that protrudes from one side bump edge portion of the pair of bump edge portions that is located on the opening side in the axial direction of the bearing housing.

[0014] According to the above configuration, the bump foil has a protruding portion protruding from one of the pair of bump edges located on the opening side in the axial direction of the bearing housing. That is, the bump foil has a portion protruding from the main body to the front side in the insertion direction of the bump foil. Therefore, compared to when the bump foil does not have a protruding portion, the amount of pushing in of the bump foil when the bump foil is inclined relative to the top foil during assembly of the foil bearing can be increased. In detail, when the bump foil does not have a protruding portion, the bump foil can be pushed only to a position where the one-side bump edge portion overlaps with the one-side top edge portion located on the opening side in the axial direction of the bearing housing. In contrast, since the bump foil has a protruding portion, the bump foil can be pushed to a position where the tip of the protruding portion overlaps with the one-side top edge portion. Therefore, compared to when the bump foil does not have a protruding portion, the inclination of the bump foil relative to the top foil can be suppressed. Therefore, uneven wear of the top foil caused by the inclination of the bump foil relative to the top foil can be suppressed.

[0015] In addition, in the axial direction of the bearing housing, the pair of bump edges are located inside the pair of top edges. Therefore, as in the conventional technology, the main body is not disposed on the outer periphery of the cylindrical portion at both ends of the cylindrical portion in the axial direction of the bearing housing. Therefore, both ends of the cylindrical portion in the axial direction of the bearing housing can deform away from the rotation axis, thereby suppressing warping of the top foil. As a result, uneven wear of the top foil caused by warping of the top foil can also be suppressed.

[0016] In the above foil bearing, the opening that opens at the one end face of the bearing housing is defined as a first opening, and the protrusion that protrudes from the one-side bump edge portion is defined as a first protrusion. The groove may have a second opening that opens at the other axial end face of the bearing housing, and the bump foil may have a second protrusion that protrudes from the other-side bump edge portion of the pair of bump edge portions that is located on the second opening side in the axial direction of the bearing housing.

[0017] According to the above configuration, the groove has a second opening in addition to the first opening. In this case, the locking portion of the bump foil can be inserted into the groove not only from the first opening but also from the second opening. In other words, the insertion direction of the bump foil into the bearing housing can be not only a first direction from one axial end face to the other axial end face of the bearing housing, but also a second direction from the other axial end face to the one axial end face.

[0018] The bump foil has a second protruding portion protruding from the other side bump edge portion located on the second opening side in the axial direction of the bearing housing, among the pair of bump edges. In other words, even when the insertion direction of the bump foil is the second direction, the bump foil has a portion protruding from the main body portion to the front side in the insertion direction. Therefore, even when the insertion direction of the bump foil is the second direction, the pushing amount of the bump foil can be increased when the bump foil is tilted relative to the top foil during assembly of the foil bearing, even when the insertion direction of the bump foil is the second direction. In detail, when the bump foil does not have the second protruding portion, the bump foil can be pushed only to a position where the other side bump edge portion overlaps with the other side top edge portion located on the second opening side in the axial direction of the bearing housing, among the pair of top edges. In contrast, since the bump foil has the second protruding portion, the bump foil can be pushed to a position where the tip of the second protruding portion overlaps with the other side top edge portion. Therefore, the inclination of the bump foil relative to the top foil can be further suppressed. Therefore, uneven wear of the top foil caused by the inclination of the bump foil relative to the top foil can be suppressed.

[0019] By having both the first protruding portion and the second protruding portion in this way, uneven wear of the top foil caused by the inclination of the bump foil can be suppressed regardless of whether the bump foil is inserted in the first direction or the second direction. Also, even if the bump foil insertion direction differs for each foil bearing, the bump foil can be standardized.

[0020] In the above foil bearing, the main body portion has a plurality of ridge portions that contact the cylindrical portion and elastically deform so as to extend circumferentially of the bearing housing, and a plurality of valley portions that contact the bearing housing, the ridge portions and the valley portions being arranged alternately in the circumferential direction of the bearing housing, and the protrusion portions may protrude from the valley portions.

[0021] For example, when the protrusion protrudes from the crest, the protrusion comes into contact with the end of the cylindrical portion in the axial direction of the bearing housing. Therefore, in the portion where the protrusion is located in the circumferential direction of the bearing housing, the end of the cylindrical portion in the axial direction of the bearing housing is less likely to deform in a direction away from the rotation axis. In contrast, in the above configuration, the protrusion protrudes from the valley, and is therefore provided in a position where it is less likely to come into contact with the end of the cylindrical portion in the axial direction of the bearing housing. Therefore, even if the protrusion is provided on the bump foil, the end of the cylindrical portion in the axial direction of the bearing housing can deform in a direction away from the rotation axis. Therefore, it is possible to avoid a reduction in the effect of suppressing warping of the top foil.

[0022] In the above foil bearing, the protrusion may be provided at a second end of the main body in the circumferential direction of the bearing housing. According to the above configuration, it is possible to suppress inclination of the bump foil relative to the top foil for the entire bump foil in the circumferential direction of the bearing housing.

[0023] In the above foil bearing, a plurality of the bump foils may be provided in a circumferential direction of the bearing housing. According to the above configuration, the length of the bump foil in the circumferential direction of the bearing housing can be shortened compared to when only one bump foil is provided in the circumferential direction of the bearing housing. Therefore, the bump foil is less likely to tilt relative to the top foil. In addition, twisting of the bump foil caused by the center of the bump foil in the circumferential direction of the bearing housing being misaligned in the axial direction of the bearing housing can be suppressed. Effect of the Invention

[0024] According to the present invention, uneven wear of the top foil caused by the inclination of the bump foil with respect to the top foil can be suppressed. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of a centrifugal compressor. [Diagram 2] FIG. 2 is a cross-sectional view of a foil bearing according to an embodiment. [Diagram 3] FIG. 3 is an exploded perspective view of a foil bearing according to the embodiment. [Figure 4] FIG. 4 is a development view of a top foil and a bump foil in the embodiment. [Diagram 5] FIG. 5 is a cross-sectional view of a foil bearing in the embodiment. [Figure 6] FIG. 6 is a cross-sectional view of a foil bearing in an embodiment. [Figure 7] FIG. 7(a) is an end view of a rotating shaft, a top foil, and a bump foil in the prior art, and FIG. 7(b) is a diagram showing fluid pressure. [Figure 8] FIG. 8 is a development view of a top foil and a bump foil in the prior art. [Figure 9] FIG. 9 is a cross-sectional view of a rotating shaft, a top foil, and a bump foil in the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] An embodiment of a foil bearing will now be described with reference to Figures 1 to 6. The foil bearing of this embodiment is used in a centrifugal compressor. As shown in FIG. 1, the centrifugal compressor 100 includes two foil bearings 10, a housing 101, an electric motor 102, a rotating shaft 103, and an impeller 104.

[0027] The electric motor 102, the rotating shaft 103, and the impeller 104 are accommodated in a housing 101. The electric motor 102 is accommodated in a motor chamber 101a formed in the housing 101. The impeller 104 is accommodated in an impeller chamber 101b formed in the housing 101. The rotating shaft 103 extends from the motor chamber 101a to the impeller chamber 101b. The electric motor 102 is attached to the rotating shaft 103. The impeller 104 is attached to an end portion of the rotating shaft 103 located on one side X1 in the axial direction X.

[0028] The electric motor 102 is driven to rotate the rotating shaft 103. When the rotating shaft 103 rotates, the impeller 104 rotates. When the impeller 104 rotates, fluid is drawn into the impeller chamber 101b from outside the housing 101, and the drawn fluid is compressed in the impeller chamber 101b. The fluid compressed in the impeller chamber 101b is discharged to the outside of the housing 101.

[0029] Each foil bearing 10 is a radial bearing that supports the rotating shaft 103 in the radial direction Y of the rotating shaft 103. Each foil bearing 10 is fixed to the housing 101. The two foil bearings 10 are provided at positions sandwiching the electric motor 102 in the axial direction X of the rotating shaft 103. When distinguishing between the two foil bearings 10, one foil bearing 10 is referred to as a first foil bearing 10a, and the other foil bearing 10 is referred to as a second foil bearing 10b. The first foil bearing 10a is located on one side X1 of the electric motor 102 in the axial direction X of the rotating shaft 103. The second foil bearing 10b is located on the other side X2 of the electric motor 102 in the axial direction X of the rotating shaft 103.

[0030] <Configuration of foil bearing> 2 and 3, the foil bearing 10 includes a cylindrical bearing housing 12, a thin top foil 13, a thin bump foil 14, a first retaining member 15, and a second retaining member 16. The foil bearing 10 of this embodiment includes three bump foils 14.

[0031] <Bearing housing> The bearing housing 12 is made of metal. The bearing housing 12 of this embodiment is made of aluminum. The bearing housing 12 of this embodiment is cylindrical. The inner peripheral surface 12a of the bearing housing 12 is a curved surface extending cylindrically. The rotating shaft 103 is inserted through the bearing housing 12. The axial direction X, radial direction Y, and circumferential direction Z of the rotating shaft 103 respectively coincide with the axial direction, radial direction, and circumferential direction of the bearing housing 12. Therefore, the axial direction X, radial direction Y, and circumferential direction Z of the rotating shaft 103 are also the axial direction X, radial direction Y, and circumferential direction Z of the bearing housing 12, respectively.

[0032] 1 and 3, the bearing housing 12 has a first end face 12b and a second end face 12c. The first end face 12b is one end face in the axial direction X of the bearing housing 12. The second end face 12c is the other end face in the axial direction X of the bearing housing 12. In this embodiment, the first end face 12b is located on one side X1 in the axial direction X of the bearing housing 12. The second end face 12c is located on the other side X2 in the axial direction X of the bearing housing 12.

[0033] As shown in Figs. 2 and 3, grooves 20 are provided in the bearing housing 12. The bearing housing 12 of this embodiment is provided with four grooves 20. Each groove 20 is recessed from the inner circumferential surface 12a of the bearing housing 12. Each groove 20 extends in the axial direction X of the bearing housing 12. Each groove 20 has a first opening 20a as an opening that opens in the first end face 12b of the bearing housing 12. Also, each groove 20 of this embodiment has a second opening 20b that opens in the second end face 12c of the bearing housing 12. That is, each groove 20 of this embodiment opens on both sides of the bearing housing 12 in the axial direction X.

[0034] When the four grooves 20 are to be distinguished, they are referred to as a first groove 21, a second groove 22, a third groove 23, and a fourth groove 24. The first groove 21, the second groove 22, the third groove 23, and the fourth groove 24 are arranged in this order in the circumferential direction Z of the bearing housing 12. The intervals between the first groove 21 and the second groove 22, the intervals between the second groove 22 and the third groove 23, and the intervals between the third groove 23 and the fourth groove 24 in the circumferential direction Z of the bearing housing 12 are all the same. The intervals between the first groove 21 and the second groove 22, the intervals between the second groove 22 and the third groove 23, and the intervals between the third groove 23 and the fourth groove 24 in the circumferential direction Z of the bearing housing 12 are all wider than the interval between the fourth groove 24 and the first groove 21 in the circumferential direction Z of the bearing housing 12. The widths of the grooves 20 in the circumferential direction Z of the bearing housing 12 are the same for the first to fourth grooves 21 to 24.

[0035] <Top foil> The top foil 13 has a tubular portion 30. The tubular portion 30 is cylindrical with a portion of the circumferential direction interrupted. A coating (not shown) is applied to the inner peripheral surface of the tubular portion 30. The top foil 13 has a free end 31 and a fixed end 32. The free end 31 protrudes from one end of the tubular portion 30 in the circumferential direction toward the radial outside of the tubular portion 30. The fixed end 32 protrudes from the other end of the tubular portion 30 in the circumferential direction toward the radial outside of the tubular portion 30. In this embodiment, the dimension of the tubular portion 30 in the axial direction of the tubular portion 30 is the same as the dimension of each of the free end 31 and the fixed end 32 in the axial direction of the tubular portion 30.

[0036] The top foil 13 is formed by bending a band-shaped metal plate having flexibility. The metal plate forming the top foil 13 is, for example, a plate made of stainless steel such as SUS301 or SUS304. The tube portion 30 is formed by bending a part of the band-shaped metal plate into a cylindrical shape. In this embodiment, the longitudinal direction of the metal plate forming the top foil 13 coincides with the circumferential direction of the tube portion 30. The short side direction of the metal plate forming the top foil 13 coincides with the axial direction of the tube portion 30. The free end 31 and the fixed end 32 are formed by bending both ends of the metal plate in the longitudinal direction toward the radial outside of the tube portion 30.

[0037] 2, the top foil 13 is disposed inside the bearing housing 12. The top foil 13 is disposed between the rotating shaft 103 and the bearing housing 12.

[0038] The cylindrical portion 30 is disposed between the outer peripheral surface of the rotating shaft 103 and the inner peripheral surface 12a of the bearing housing 12. The cylindrical portion 30 extends in the axial direction X and the circumferential direction Z of the bearing housing 12. The inner peripheral surface of the cylindrical portion 30 faces the rotating shaft 103. As described above, the inner peripheral surface of the cylindrical portion 30 is coated. Therefore, even if the rotating shaft 103 comes into contact with the inner peripheral surface of the cylindrical portion 30, friction generated between the rotating shaft 103 and the cylindrical portion 30 is suppressed.

[0039] The free end 31 and the fixed end 32 extend from both ends of the cylindrical portion 30 in the circumferential direction Z of the bearing housing 12 toward the bearing housing 12. The free end 31 is inserted into the fourth groove 24. The fixed end 32 is inserted into the first groove 21. This restricts movement of the top foil 13 in the circumferential direction Z of the bearing housing 12.

[0040] 4 and 5, the tubular portion 30 has a pair of top edge portions 30a, 30b. FIG. 4 is a developed view of the top foil 13 and the bump foil 14. The up-down direction in FIG. 4 corresponds to the axial direction X of the bearing housing 12. The left-right direction in FIG. 4 corresponds to the circumferential direction Z of the bearing housing 12.

[0041] The pair of top edges 30a, 30b are located at both ends of the tubular portion 30 in the axial direction X of the bearing housing 12. The pair of top edges 30a, 30b each extend in the circumferential direction Z of the bearing housing 12. Of the pair of top edges 30a, 30b, the top edge located on the first end face 12b side in the axial direction X of the bearing housing 12 is referred to as the first top edge 30a as one-side top edge. Also, of the pair of top edges 30a, 30b, the top edge located on the second end face 12c side in the axial direction X of the bearing housing 12 is referred to as the second top edge 30b as the other-side top edge.

[0042] <Bump foil> 2, each bump foil 14 is disposed inside the bearing housing 12. Each bump foil 14 is disposed between the top foil 13 and the bearing housing 12. The three bump foils 14 are disposed at intervals in the circumferential direction Z of the bearing housing 12. Hereinafter, when distinguishing between the three bump foils 14, they will be referred to as a first bump foil 14a, a second bump foil 14b, and a third bump foil 14c.

[0043] Each bump foil 14 has a main body portion 40. The main body portion 40 extends in the circumferential direction Z of the bearing housing 12. The main body portion 40 supports the top foil 13 elastically. 2 and 3, the main body 40 has a corrugated shape that undulates in the radial direction Y of the bearing housing 12. More specifically, the main body 40 has a plurality of peaks 41 and a plurality of valleys 42. The peaks 41 and the valleys 42 are arranged alternately in the circumferential direction Z of the bearing housing 12. In this embodiment, the valleys 42 are located at a first end 401 and a second end 402 of the main body 40 in the circumferential direction Z of the bearing housing 12.

[0044] Each valley portion 42 is curved to follow the inner circumferential surface 12a of the bearing housing 12. Each valley portion 42 is in contact with the inner circumferential surface 12a of the bearing housing 12. Each peak portion 41 bulges from the valley portion 42 toward the outer circumferential surface of the tubular portion 30. Each peak portion 41 is curved in an arc shape. Each peak portion 41 is in contact with the outer circumferential surface of the tubular portion 30. The peak portion 41 is elastically deformable to extend in the circumferential direction Z of the bearing housing 12.

[0045] As shown in Fig. 4 and Fig. 5, the main body 40 has a pair of bump edges 40a, 40b. The pair of bump edges 40a, 40b are located at both ends of the main body 40 in the axial direction X of the bearing housing 12. The pair of bump edges 40a, 40b each extend in the circumferential direction Z of the bearing housing 12. Of the pair of bump edges 40a, 40b, the bump edge located on the first end face 12b side in the axial direction X of the bearing housing 12 is referred to as the first bump edge 40a as the one-side bump edge. Also, of the pair of bump edges 40a, 40b, the bump edge located on the second end face 12c side in the axial direction X of the bearing housing 12 is referred to as the second bump edge 40b as the other-side bump edge.

[0046] As shown in FIG. 2, each bump foil 14 has a locking portion 43. The locking portion 43 extends from a first end 401 of the main body portion 40 in the circumferential direction Z of the bearing housing 12 toward the bearing housing 12. The locking portion 43 is inserted into the groove 20 of the bearing housing 12. More specifically, the locking portion 43 of the first bump foil 14a is inserted into the first groove 21. This restricts the movement of the first bump foil 14a in the circumferential direction Z of the bearing housing 12. The locking portion 43 of the second bump foil 14b is inserted into the second groove 22. This restricts the movement of the second bump foil 14b in the circumferential direction Z of the bearing housing 12. The locking portion 43 of the third bump foil 14c is inserted into the third groove 23. This restricts the movement of the third bump foil 14c in the circumferential direction Z of the bearing housing 12.

[0047] The bump foil 14 is formed by bending a band-shaped metal plate having flexibility. The metal plate forming the bump foil 14 is a plate made of stainless steel such as SUS301 or SUS304. The main body 40 is formed by forming a part of the band-shaped metal plate into a corrugated shape. In this embodiment, the longitudinal direction of the metal plate forming the bump foil 14 coincides with the circumferential direction Z of the bearing housing 12. The lateral direction of the metal plate forming the bump foil 14 coincides with the axial direction X of the bearing housing 12. The locking portion 43 is formed by bending one end of the metal plate in the circumferential direction Z of the bearing housing 12 radially outward.

[0048] 4, the dimension L40 of the main body 40 in the axial direction X of the bearing housing 12 is smaller than the dimension L43 of the locking portion 43 in the axial direction X of the bearing housing 12. The dimension L43 of the locking portion 43 in the axial direction X of the bearing housing 12 is the same as the dimension L30 of the tubular portion 30 in the axial direction X of the bearing housing 12. Therefore, the dimension L40 of the main body 40 in the axial direction X of the bearing housing 12 is smaller than the dimension L30 of the tubular portion 30 in the axial direction X of the bearing housing 12.

[0049] In the axial direction X of the bearing housing 12, the pair of bump edges 40a, 40b of the main body 40 are located inside the pair of top edges 30a, 30b of the tubular portion 30. When the bump foil 14 is not inclined with respect to the top foil 13, the pair of bump edges 40a, 40b are parallel to the pair of top edges 30a, 30b.

[0050] 3 and 4, the bump foil 14 has a first protruding portion 44 as a protruding portion protruding from the first bump edge portion 40a of the main body portion 40. The first protruding portion 44 in this embodiment is rectangular. The first protruding portion 44 in this embodiment protrudes from a valley portion 42 located at the second end portion 402 of the main body portion 40, among the multiple valley portions 42. Therefore, the first protruding portion 44 in this embodiment is provided at the second end portion 402 of the main body portion 40.

[0051] The bump foil 14 has a second protruding portion 45 protruding from the second bump edge portion 40b of the main body portion 40. The second protruding portion 45 in this embodiment is rectangular. The second protruding portion 45 in this embodiment protrudes from the valley portion 42 located at the second end portion 402 of the main body portion 40 among the multiple valley portions 42. Therefore, the second protruding portion 45 in this embodiment is provided at the second end portion 402 of the main body portion 40. The second protruding portion 45 in this embodiment is provided at the same position as the first protruding portion 44 in the circumferential direction Z of the bearing housing 12. The first protruding portion 44 and the second protruding portion 45 are provided at positions sandwiching the main body portion 40 in the axial direction X of the bearing housing 12.

[0052] In this embodiment, the dimension L44 of the first protrusion 44 in the axial direction X of the bearing housing 12 is the same as the distance La from the first bump edge 40a to the first top edge 30a. The dimension L45 of the second protrusion 45 in the axial direction X of the bearing housing 12 is the same as the distance Lb from the second bump edge 40b to the second top edge 30b. Therefore, the sum L44+L40+L45 of the dimension L44 of the first protrusion 44 in the axial direction X of the bearing housing 12, L40 of the main body 40, and the dimension L45 of the second protrusion 45 in the axial direction X of the bearing housing 12 is the same as the dimension L30 of the tubular portion 30 in the axial direction X of the bearing housing 12.

[0053] 4 and 6, in the axial direction X of the bearing housing 12, the tip 44a of the first protrusion 44 is located at the same position as the first top edge 30a of the top foil 13. The tip 44a of the first protrusion 44 extends along the first top edge 30a. In the axial direction X of the bearing housing 12, the tip 45a of the second protrusion 45 is located at the same position as the second top edge 30b of the top foil 13. The tip 45a of the second protrusion 45 extends along the second top edge 30b.

[0054] <Preventive material> 3, the first and second retaining members 15 and 16 in this embodiment are each annular. The first and second retaining members 15 and 16 are each provided on the bearing housing 12. In this embodiment, the first retaining member 15 is provided on a first end face 12b of the bearing housing 12. The second retaining member 16 is provided on a second end face 12c of the bearing housing 12. The first and second retaining members 15 and 16 are each fixed to the bearing housing 12 by fixing means such as bolts (not shown).

[0055] The first retaining member 15 of this embodiment covers the first openings 20a of the first to fourth grooves 21 to 24. The first retaining member 15 is located on one side X1 in the axial direction X of the bearing housing 12 with respect to the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14. The first retaining member 15 restricts movement of the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14 toward the one side X1 in the axial direction X of the bearing housing 12.

[0056] The second retaining member 16 of this embodiment covers the second openings 20b of the first to fourth grooves 21 to 24. The second retaining member 16 is located on the other side X2 of the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14 in the axial direction X of the bearing housing 12. The second retaining member 16 restricts movement of the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14 toward the other side X2 in the axial direction X of the bearing housing 12.

[0057] In this embodiment, the first and second retaining members 15 and 16 are provided as a pair of restricting members on both sides of the locking portion 43 in the axial direction X of the bearing housing 12. This restricts movement of the locking portion 43 of the bump foil 14 in the axial direction X of the bearing housing 12.

[0058] <Foil bearing operation> 2, when the rotating shaft 103 rotates in the rotation direction R, air is drawn between the outer circumferential surface of the rotating shaft 103 and the inner circumferential surface of the tubular portion 30 of the top foil 13. The air flows between the rotating shaft 103 and the tubular portion 30 in the rotation direction R of the rotating shaft 103. The fixed end 32 of the top foil 13 is pressed against a surface that precedes the rotation direction R of the rotating shaft 103, i.e., a surface that is closer to the fourth groove 24, among the surfaces that define the first groove 21, by the air flow that flows between the rotating shaft 103 and the tubular portion 30.

[0059] When the rotation speed of the rotating shaft 103 reaches a predetermined rotation speed, a fluid film 17 is formed by the air drawn between the rotating shaft 103 and the cylindrical portion 30. The rotating shaft 103 floats relative to the top foil 13 due to the dynamic pressure of the fluid film 17. The rotating shaft 103 is supported in the radial direction Y by the fluid film 17 without contacting the top foil 13.

[0060] When the fluid film 17 is formed, the top foil 13 is elastically deformed such that the tubular portion 30 bulges outward in the radial direction Y. At this time, the free end 31 of the top foil 13 moves inside the fourth groove 24 in the rotational direction R. The width of the fourth groove 24 in the circumferential direction Z of the bearing housing 12 is set to a width such that the free end 31 does not come into contact with the surface that defines the fourth groove 24 even if the tubular portion 30 is elastically deformed. As a result, when the tubular portion 30 is elastically deformed, the movement of the free end 31 in the rotational direction R inside the fourth groove 24 is not restricted. Therefore, the elastic deformation of the tubular portion 30 is permitted.

[0061] When the tubular portion 30 elastically deforms, a load is input from the tubular portion 30 to each ridge portion 41 of the bump foil 14. Each ridge portion 41 elastically deforms so as to extend in the circumferential direction Z due to the load input from the tubular portion 30. As a result, the top foil 13 is elastically supported by the main body portion 40 of the bump foil 14.

[0062] [Operation of this embodiment] The operation of this embodiment will now be described. The dimension L40 of the main body 40 in the axial direction X of the bearing housing 12 is smaller than the dimension L30 of the tubular portion 30 in the axial direction X of the bearing housing 12. In the axial direction X of the bearing housing 12, the pair of bump edges 40a, 40b of the main body 40 are located inside the pair of top edges 30a, 30b of the tubular portion 30. As a result, the main body 40 is not disposed on the outer periphery of the tubular portion 30 at both ends of the tubular portion 30 in the axial direction X of the bearing housing 12. Therefore, both ends of the tubular portion 30 in the axial direction X of the bearing housing 12 can be deformed away from the rotation axis 103. Therefore, the warping of the top foil 13 is suppressed. As a result, uneven wear of the top foil 13 caused by the warping of the top foil 13 can be suppressed.

[0063] When assembling the foil bearing 10, the bump foil 14 is inserted inside the bearing housing 12. More specifically, the body portion 40 of the bump foil 14 is inserted between the inner circumferential surface 12a of the bearing housing 12 and the cylindrical portion 30 of the top foil 13. The locking portion 43 of the bump foil 14 is inserted into the groove 20 of the bearing housing 12.

[0064] The groove 20 of the bearing housing 12 in this embodiment has a first opening 20a that opens at the first end face 12b of the bearing housing 12 and a second opening 20b that opens at the second end face 12c of the bearing housing 12. Therefore, the locking portion 43 of the bump foil 14 is inserted into the groove 20 from the first opening 20a or the second opening 20b. When the locking portion 43 is inserted into the groove 20 from the first opening 20a, the insertion direction of the bump foil 14 into the bearing housing 12 is a first direction A1 from the first end face 12b side toward the second end face 12c side of the bearing housing 12. On the other hand, when the locking portion 43 is inserted into the groove 20 from the second opening 20b, the insertion direction of the bump foil 14 into the bearing housing 12 is a second direction A2 from the second end face 12c side toward the first end face 12b side of the bearing housing 12. In other words, when the groove 20 is open on both sides of the bearing housing 12 in the axial direction X as in this embodiment, the bump foil 14 can be inserted into the bearing housing 12 in both the first direction A1 and the second direction A2.

[0065] In this embodiment, the locking portion 43 of the bump foil 14 of the first foil bearing 10a is inserted into the groove 20 from the first opening 20a of the groove 20. That is, in the first foil bearing 10a, the insertion direction of the bump foil 14 into the bearing housing 12 is the first direction A1. On the other hand, the locking portion 43 of the bump foil 14 of the second foil bearing 10b is inserted into the groove 20 from the second opening 20b of the groove 20. That is, in the second foil bearing 10b, the insertion direction of the bump foil 14 into the bearing housing 12 is the second direction A2. In this embodiment, the insertion direction of the bump foil 14 of the first foil bearing 10a and the insertion direction of the bump foil 14 of the second foil bearing 10b are opposite to each other.

[0066] When assembling the first foil bearing 10a, the bump foil 14 may tilt with respect to the top foil 13. When the insertion direction of the bump foil 14 is the first direction A1, the bump foil 14 tilts so as to protrude from the first top edge 30a, of the pair of top edges 30a, 30b, which is located on the first opening 20a side, i.e., the front side in the insertion direction. In this case, in order to suppress the tilt of the bump foil 14 with respect to the top foil 13, the portion of the main body 40 protruding from the first top edge 30a is pushed toward the back side in the insertion direction.

[0067] The bump foil 14 has a first protruding portion 44 that protrudes from the first bump edge portion 40a, which is located on the first opening 20a side in the axial direction X of the bearing housing 12, among the pair of bump edges 40a, 40b. That is, the bump foil 14 has a portion that protrudes from the main body portion 40 to the front side in the insertion direction of the bump foil 14. Therefore, the pushing amount of the bump foil 14 can be increased compared to when the bump foil 14 does not have the first protruding portion 44. In detail, when the bump foil 14 does not have the first protruding portion 44, the bump foil 14 can be pushed only to the position where the first bump edge portion 40a overlaps with the first top edge portion 30a. In contrast, since the bump foil 14 has the first protruding portion 44, the bump foil 14 can be pushed to the position where the tip 44a of the first protruding portion 44 overlaps with the first top edge portion 30a. Therefore, the inclination of the bump foil 14 relative to the top foil 13 can be further suppressed compared to a case where the bump foil 14 does not have the first protruding portion 44. Therefore, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 relative to the top foil 13 can be suppressed.

[0068] When assembling the second foil bearing 10b, the bump foil 14 may tilt with respect to the top foil 13. When the insertion direction of the bump foil 14 is the second direction A2, the bump foil 14 tilts so as to protrude from the second top edge 30b, which is located on the second opening 20b side, i.e., the front side in the insertion direction, of the pair of top edges 30a, 30b. In this case, in order to suppress the tilt of the bump foil 14 with respect to the top foil 13, the portion of the main body 40 protruding from the second top edge 30b is pushed toward the back side in the insertion direction.

[0069] The bump foil 14 has a second protruding portion 45 protruding from the second bump edge portion 40b located on the second opening 20b side in the axial direction X of the bearing housing 12, out of the pair of bump edge portions 40a, 40b. That is, the bump foil 14 has a portion protruding from the main body portion 40 to the front side in the insertion direction of the bump foil 14. Therefore, the pushing amount of the bump foil 14 can be increased compared to when the bump foil 14 does not have the second protruding portion 45. In detail, when the bump foil 14 does not have the second protruding portion 45, the bump foil 14 can be pushed only to the position where the second bump edge portion 40b overlaps the second top edge portion 30b. In contrast, since the bump foil 14 has the second protruding portion 45, the bump foil 14 can be pushed to the position where the tip 45a of the second protruding portion 45 overlaps the second top edge portion 30b. Therefore, the inclination of the bump foil 14 relative to the top foil 13 can be further suppressed compared to a case where the bump foil 14 does not have the second protruding portion 45. Therefore, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 relative to the top foil 13 can be suppressed.

[0070] [Effects of this embodiment] The effects of this embodiment will be described. (1) The bearing housing 12 has a groove 20 into which the locking portion 43 of the bump foil 14 is inserted. The groove 20 has a first opening 20a that opens at a first end face 12b in the axial direction X of the bearing housing 12. The locking portion 43 can be inserted into the groove 20 from the first opening 20a. In this case, the insertion direction of the bump foil 14 into the bearing housing 12 is a first direction A1 from the first end face 12b toward the second end face 12c of the bearing housing 12.

[0071] The bump foil 14 has a first protruding portion 44 protruding from the first bump edge portion 40a located on the first opening 20a side of the pair of bump edges 40a, 40b of the main body 40. That is, the bump foil 14 has a portion protruding from the main body 40 to the front side in the insertion direction of the bump foil 14. Therefore, compared with the case where the bump foil 14 does not have the first protruding portion 44, the pushing amount of the bump foil 14 when the bump foil 14 is inclined relative to the top foil 13 during assembly of the foil bearing 10 can be increased. Therefore, the inclination of the bump foil 14 relative to the top foil 13 can be suppressed. As a result, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 can be suppressed.

[0072] In addition, in the axial direction X of the bearing housing 12, the pair of bump edges 40a, 40b of the main body 40 are located inside the pair of top edges 30a, 30b of the tubular portion 30. Therefore, as in the conventional technology, the main body 40 is not disposed on the outer periphery of the tubular portion 30 at both ends of the tubular portion 30 in the axial direction X of the bearing housing 12. Therefore, both ends of the tubular portion 30 in the axial direction X of the bearing housing 12 can deform away from the rotation axis 103, thereby suppressing warping of the top foil 13. As a result, uneven wear of the top foil 13 caused by warping of the top foil 13 can also be suppressed.

[0073] (2) In this embodiment, the groove 20 has a second opening 20b in addition to the first opening 20a. Therefore, the locking portion 43 of the bump foil 14 can be inserted into the groove 20 not only from the first opening 20a but also from the second opening 20b. In other words, the insertion direction of the bump foil 14 into the bearing housing 12 can be not only the first direction A1 from the first end face 12b to the second end face 12c of the bearing housing 12, but also the second direction A2 from the second end face 12c to the first end face 12b of the bearing housing 12.

[0074] In this embodiment, the bump foil 14 has a second protruding portion 45 protruding from the second bump edge portion 40b located on the second opening 20b side in the axial direction X of the bearing housing 12, out of the pair of bump edge portions 40a, 40b. That is, even when the insertion direction of the bump foil 14 is the second direction A2, the bump foil 14 has a portion protruding from the main body portion 40 to the front side in the insertion direction. Therefore, even when the insertion direction of the bump foil 14 is the second direction A2, the pushing amount of the bump foil 14 when the bump foil 14 is inclined relative to the top foil 13 during assembly of the foil bearing 10 can be increased. Therefore, the inclination of the bump foil 14 relative to the top foil 13 can be suppressed. As a result, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 can be suppressed.

[0075] In this way, since the bump foil 14 has both the first protruding portion 44 and the second protruding portion 45, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 can be suppressed regardless of whether the insertion direction of the bump foil 14 is the first direction A1 or the second direction A2. Also, even if the insertion direction of the bump foil 14 differs between the first foil bearing 10a and the second foil bearing 10b as in this embodiment, the bump foil 14 can be made common.

[0076] (3) For example, when the first protrusion 44 protrudes from the crest 41 of the main body 40, the first protrusion 44 contacts the end of the tubular portion 30 on the first top edge 30a side. Therefore, in the portion where the first protrusion 44 is located in the circumferential direction Z of the bearing housing 12, the end of the tubular portion 30 on the first top edge 30a side is less likely to deform in a direction away from the rotation shaft 103. In contrast, in this embodiment, the first protrusion 44 protrudes from the valley 42 of the main body 40, so that the first protrusion 44 is provided at a position where it is less likely to contact the end of the tubular portion 30 on the first top edge 30a side. Therefore, even if the first protrusion 44 is provided on the bump foil 14, the end of the tubular portion 30 on the first top edge 30a side can deform in a direction away from the rotation shaft 103. Therefore, it is possible to avoid a reduction in the effect of suppressing the warping of the top foil 13.

[0077] Similarly, for example, when the second protrusion 45 protrudes from the crest 41 of the main body 40, the second protrusion 45 contacts the end of the tubular portion 30 on the second top edge 30b side. Therefore, in the portion where the second protrusion 45 is located in the circumferential direction Z of the bearing housing 12, the end of the tubular portion 30 on the second top edge 30b side is less likely to deform in a direction away from the rotation shaft 103. In contrast, in this embodiment, the second protrusion 45 protrudes from the valley 42 of the main body 40, so that the second protrusion 45 is provided at a position where it is less likely to contact the end of the tubular portion 30 on the second top edge 30b side. Therefore, even if the second protrusion 45 is provided on the bump foil 14, the end of the tubular portion 30 on the second top edge 30b side can deform in a direction away from the rotation shaft 103. Therefore, it is possible to avoid a reduction in the effect of suppressing the warping of the top foil 13.

[0078] (4) The first protrusion 44 is provided at the second end 402 of the main body 40 in the circumferential direction Z of the bearing housing 12. This makes it possible to suppress inclination of the bump foil 14 relative to the top foil 13 for the entire bump foil 14 in the circumferential direction Z of the bearing housing 12. Similarly, the second protrusion 45 is provided at the second end 402 of the main body 40 in the circumferential direction Z of the bearing housing 12. This makes it possible to suppress inclination of the bump foil 14 relative to the top foil 13 for the entire bump foil 14 in the circumferential direction Z of the bearing housing 12.

[0079] (5) A plurality of bump foils 14 are provided in the circumferential direction Z of the bearing housing 12. Therefore, the length of the bump foil 14 in the circumferential direction Z of the bearing housing 12 can be shortened compared to a case in which only one bump foil 14 is provided in the circumferential direction Z of the bearing housing 12. Therefore, the bump foil 14 is less likely to tilt relative to the top foil 13. In addition, twisting of the bump foil 14 caused by the center of the bump foil 14 in the circumferential direction Z of the bearing housing 12 being shifted in the axial direction X of the bearing housing 12 can be suppressed.

[0080] (6) In this embodiment, the dimension L44 of the first protrusion 44 in the axial direction X of the bearing housing 12 is the same as the distance La from the first bump edge 40a to the first top edge 30a. Therefore, when the insertion direction of the bump foil 14 is the first direction A1, by pushing the bump foil 14 so that the tip 44a of the first protrusion 44 overlaps the first top edge 30a, the pair of bump edges 40a, 40b become parallel to the pair of top edges 30a, 30b. In other words, the bump foil 14 is not inclined with respect to the top foil 13.

[0081] Similarly, the dimension L45 of the second protrusion 45 in the axial direction X of the bearing housing 12 is the same as the distance Lb from the second bump edge 40b to the second top edge 30b. Therefore, when the insertion direction of the bump foil 14 is the second direction A2, the pair of bump edges 40a, 40b can be made parallel to the pair of top edges 30a, 30b by pushing the bump foil 14 so that the tip 45a of the second protrusion 45 overlaps the second top edge 30b. In other words, the bump foil 14 is not inclined with respect to the top foil 13.

[0082] (7) Both the fixed end 32 of the top foil 13 and the locking portion 43 of the first bump foil 14a are inserted into the first groove 21. Therefore, the configuration of the bearing housing 12 can be simplified compared to a case in which the groove 20 into which the fixed end 32 of the top foil 13 is inserted and the groove 20 into which the locking portion 43 of the first bump foil 14a is inserted are provided separately.

[0083] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0084] The number of bump foils 14 included in the foil bearing 10 may be changed as appropriate. The groove 20 may have only the first opening 20a. In other words, the groove 20 may be closed at the second end surface 12c of the bearing housing 12 without being open.

[0085] In this case, the portion of the bearing housing 12 located closer to the second end face 12c than the groove 20 is located on the other side X2 of the free end 31, the fixed end 32, and the locking portions 43 of the bump foils 14 in the axial direction X of the bearing housing 12. This restricts the movement of the free end 31, the fixed end 32, and the locking portions 43 of the bump foils 14 of the top foil 13 toward the other side X2 in the axial direction X of the bearing housing 12. For this reason, the second retaining member 16 is not necessary. In this case, one of the pair of restricting portions is the first retaining member 15, and the other restricting portion is the bearing housing 12.

[0086] In addition, since the insertion direction of the bump foil 14 into the bearing housing 12 is limited to the first direction A1, the bump foil 14 does not need to have the second protruding portion 45. The groove 20 may have only the second opening 20b. In other words, the groove 20 may be closed at the first end surface 12b of the bearing housing 12 without being open.

[0087] In this case, the portion of the bearing housing 12 located closer to the first end face 12b than the groove 20 is located on one side X1 of the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14 in the axial direction X of the bearing housing 12. This restricts the movement of the free end 31 and fixed end 32 of the top foil 13 and the locking portions 43 of each bump foil 14 to one side X1 in the axial direction X of the bearing housing 12. For this reason, the first retaining member 15 is not necessary. In this case, one of the pair of restricting portions is the bearing housing 12, and the other restricting portion is the second retaining member 16.

[0088] In addition, since the insertion direction of the bump foil 14 into the bearing housing 12 is limited to the second direction A2, the bump foil 14 does not need to have the first protrusion 44. In the above configuration, the second end surface 12c and the second opening 20b of the bearing housing 12 correspond to the "one end surface" and the "opening" in the claims, respectively. Also, the second bump edge portion 40b and the second protruding portion 45 of the bump foil 14 correspond to the "one side bump edge portion" and the "protruding portion" in the claims, respectively.

[0089] The groove 20 of the first foil bearing 10a may have only the first opening 20a, and the groove 20 of the second foil bearing 10b may have only the second opening 20b. In this configuration, the bump foils 14 of the first foil bearing 10a and the second foil bearing 10b may each have both the first protruding portion 44 and the second protruding portion 45. In the first foil bearing 10a, the first protruding portion 44 corresponds to the "protruding portion" in the claims. In the second foil bearing 10b, the second protruding portion 45 corresponds to the "protruding portion" in the claims. In this case, even if the insertion direction of the bump foil 14 differs between the first foil bearing 10a and the second foil bearing 10b, the bump foil 14 can be made common.

[0090] The groove 20 of the first foil bearing 10a may have only the second opening 20b, and the groove 20 of the second foil bearing 10b may have only the first opening 20a. In this configuration, the bump foils 14 of the first foil bearing 10a and the second foil bearing 10b may each have both the first protruding portion 44 and the second protruding portion 45. In the first foil bearing 10a, the second protruding portion 45 corresponds to the "protruding portion" in the claims. In the second foil bearing 10b, the first protruding portion 44 corresponds to the "protruding portion" in the claims. In this case, even if the insertion direction of the bump foil 14 differs between the first foil bearing 10a and the second foil bearing 10b, the bump foil 14 can be made common.

[0091] When the groove 20 has the first opening 20a and the second opening 20b, the bump foil 14 does not need to have the second protrusion 45. In this case, by setting the insertion direction of the bump foil 14 into the bearing housing 12 to the first direction A1, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 can be suppressed.

[0092] When the groove 20 has the first opening 20a and the second opening 20b, the bump foil 14 does not need to have the first protrusion 44. In this case, by setting the insertion direction of the bump foil 14 into the bearing housing 12 to the second direction A2, uneven wear of the top foil 13 caused by the inclination of the bump foil 14 can be suppressed.

[0093] In the above configuration, the second end surface 12c and the second opening 20b of the bearing housing 12 correspond to the "one end surface" and the "opening" in the claims, respectively. Also, the second bump edge portion 40b and the second protruding portion 45 of the bump foil 14 correspond to the "one side bump edge portion" and the "protruding portion" in the claims, respectively.

[0094] The insertion direction of the bump foil 14 of the first foil bearing 10a may be the second direction A2. The insertion direction of the bump foil 14 of the second foil bearing 10b may be the first direction A1.

[0095] The insertion direction of the bump foil 14 of the first foil bearing 10a may be the second direction A2, and the insertion direction of the bump foil 14 of the second foil bearing 10b may be the first direction A1. In this case, as in the above embodiment, the insertion direction of the bump foil 14 of the first foil bearing 10a and the insertion direction of the bump foil 14 of the second foil bearing 10b are opposite to each other.

[0096] The insertion direction of the bump foil 14 of the first foil bearing 10a and the insertion direction of the bump foil 14 of the second foil bearing 10b may be the same. Specifically, the insertion direction of the bump foil 14 of the first foil bearing 10a and the insertion direction of the bump foil 14 of the second foil bearing 10b may each be the first direction A1.

[0097] The insertion direction of the bump foil 14 of the first foil bearing 10a and the insertion direction of the bump foil 14 of the second foil bearing 10b may each be the second direction A2. The first protrusion 44 and the second protrusion 45 may each protrude from the peak portion 41 of the main body 40 .

[0098] The first protrusion 44 and the second protrusion 45 do not necessarily have to be provided at the second end 402 of the main body 40 in the circumferential direction Z of the bearing housing 12 . The dimension L30 of the cylindrical portion 30 in the axial direction X of the bearing housing 12 may be different from the dimensions of each of the fixed end 32 and the free end 31 in the axial direction X of the bearing housing 12.

[0099] ○ The dimension L40 of the main body portion 40 in the axial direction X of the bearing housing 12 may be the same as or larger than the dimension L43 of the locking portion 43 in the axial direction X of the bearing housing 12, as long as it is smaller than the dimension L30 of the tubular portion 30 in the axial direction X of the bearing housing 12.

[0100] The top foil 13 does not have to have the free end 31. In this case, the fourth groove 24 of the bearing housing 12 is not necessary. Although both the fixed end 32 of the top foil 13 and the locking portion 43 of the first bump foil 14a are inserted into the first groove 21, this is not limiting. The groove 20 into which the fixed end 32 of the top foil 13 is inserted and the groove 20 into which the locking portion 43 of the first bump foil 14a is inserted may be provided separately.

[0101] The peaks 41 may be located at the first end 401 and the second end 402 of the main body 40 in the circumferential direction Z of the bearing housing 12. In this case, it is preferable that the first protrusion 44 and the second protrusion 45 are each provided at the valley portion 42 that is closest to the second end 402 of the main body 40 among the multiple valley portions 42.

[0102] The number of first protrusions 44 on the bump foil 14 is not limited to one. The bump foil 14 may have a plurality of first protrusions 44 in the circumferential direction Z of the bearing housing 12. Similarly, the number of second protrusions 45 on the bump foil 14 is not limited to one. The bump foil 14 may have a plurality of second protrusions 45 in the circumferential direction Z of the bearing housing 12.

[0103] The position of the first protrusion 44 and the position of the second protrusion 45 in the circumferential direction Z of the bearing housing 12 may be different. The dimension L44 of the first protrusion 44 does not have to be the same as the distance La from the first bump edge 40a to the first top edge 30a. Similarly, the dimension L45 of the second protrusion 45 does not have to be the same as the distance Lb from the second bump edge 40b to the second top edge 30b.

[0104] In the above embodiment, the first retaining member 15 is provided on the first end surface 12b of the bearing housing 12. However, this is not limited to this. For example, the first retaining member 15 may be inserted into the groove 20 from the inner circumferential surface 12a of the bearing housing 12 to close the first opening 20a of the groove 20.

[0105] Similarly, in the above embodiment, the second retaining member 16 is provided on the second end surface 12c of the bearing housing 12, but this is not limited to this. For example, the second retaining member 16 may be inserted into the groove 20 from the inner circumferential surface 12a of the bearing housing 12 to close the second opening 20b of the groove 20.

[0106] The first and second retaining members 15 and 16 do not have to be annular. For example, the first and second retaining members 15 and 16 may be provided only at positions corresponding to the grooves 20 in the circumferential direction Z of the bearing housing 12.

[0107] The application of the foil bearing 10 is not limited to the centrifugal compressor 100 . [Note] The technical ideas that can be understood from the above-described embodiment and modified examples will be described below.

[0108] [1] A bearing housing having a cylindrical shape and a rotating shaft inserted therethrough, a thin-plate-shaped top foil disposed between the rotating shaft and the bearing housing, and a thin-plate-shaped bump foil disposed between the bearing housing and the top foil, wherein the top foil has a cylindrical portion extending in a circumferential direction of the bearing housing, the bump foil has a main body portion extending in the circumferential direction of the bearing housing and elastically supporting the top foil, and a locking portion extending from a first end of the main body portion in the circumferential direction of the bearing housing toward the bearing housing, and the bearing housing has a groove recessed from an inner circumferential surface and into which the locking portion is inserted. the groove has an opening that opens at one end face in the axial direction of the bearing housing, a pair of regulating portions are provided on both sides of the locking portion in the axial direction of the bearing housing, and a pair of bump edge portions located at both ends of the main body portion in the axial direction of the bearing housing are located more inward in the axial direction of the bearing housing than a pair of top edge portions located at both ends of the cylindrical portion in the axial direction of the bearing housing, and the bump foil has a protruding portion that protrudes from one side bump edge portion of the pair of bump edge portions that is located on the opening side in the axial direction of the bearing housing.

[0109] [2] The opening that opens at the one end face of the bearing housing is defined as a first opening, and the protrusion that protrudes from the one-side bump edge portion is defined as a first protrusion. The groove has a second opening that opens at the other axial end face of the bearing housing, and the bump foil has a second protrusion that protrudes from the other-side bump edge portion of the pair of bump edges that is located on the second opening side in the axial direction of the bearing housing. A foil bearing as described in [1].

[0110] [3] A foil bearing as described in [1] or [2], wherein the main body portion has a plurality of ridge portions that contact the cylindrical portion and elastically deform so as to extend in the circumferential direction of the bearing housing, and a plurality of valley portions that contact the bearing housing, the ridge portions and the valley portions are arranged alternately in the circumferential direction of the bearing housing, and the protrusion portions protrude from the valley portions.

[0111] [4] The foil bearing according to any one of [1] to [3], wherein the protrusion is provided at a second end of the main body in the circumferential direction of the bearing housing. [5] The foil bearing according to any one of [1] to [4], wherein a plurality of the bump foils are provided in the circumferential direction of the bearing housing. [Explanation of symbols]

[0112] 10... foil bearing, 12... bearing housing, 12a... inner peripheral surface, 12b... first end face as one end face, 12c... second end face as the other end face, 13... top foil, 14... bump foil, 15... first retaining member as a restricting portion, 16... second retaining member as a restricting portion, 20... groove, 20a... first opening as an opening, 20b... second opening, 30... cylindrical portion, 30a... top edge portion, first top edge portion as a top edge portion, 30b...second top edge portion as a top edge portion, 40...main body portion, 40a...first bump edge portion as one side bump edge portion, 40b...second bump edge portion as the other side bump edge portion, 41...peak portion, 42...valley portion, 43...engagement portion, 44...first protrusion portion as protrusion portion, 45...second protrusion portion, 103...rotation axis, 401...first end portion, 402...second end portion, X...axial direction, Z...circumferential direction.

Claims

1. a cylindrical bearing housing through which a rotating shaft is inserted; A thin top foil disposed between the rotating shaft and the bearing housing; a thin-plate-shaped bump foil disposed between the bearing housing and the top foil; Equipped with The top foil has a cylindrical portion extending in a circumferential direction of the bearing housing, the bump foil has a main body portion that extends in a circumferential direction of the bearing housing and elastically supports the top foil, and a locking portion that extends from a first end of the main body portion in the circumferential direction of the bearing housing toward the bearing housing, the bearing housing has a groove recessed from an inner circumferential surface and into which the locking portion is inserted, The groove has an opening that opens at one axial end face of the bearing housing, a pair of restricting portions are provided on both sides of the locking portion in the axial direction of the bearing housing, a pair of bump edge portions located at both ends of the main body in the axial direction of the bearing housing are located more inward in the axial direction of the bearing housing than a pair of top edge portions located at both ends of the cylindrical portion in the axial direction of the bearing housing, The foil bearing is characterized in that the bump foil has a protruding portion that protrudes from one of the pair of bump edge portions that is located on the opening side in the axial direction of the bearing housing.

2. When the opening that opens at the one end surface of the bearing housing is defined as a first opening, and the protruding portion that protrudes from the one side bump edge portion is defined as a first protruding portion, the groove has a second opening that opens at the other axial end surface of the bearing housing, The foil bearing according to claim 1 , wherein the bump foil has a second protruding portion protruding from the other bump edge portion of the pair of bump edge portions that is located on the second opening side in the axial direction of the bearing housing.

3. the main body portion has a plurality of peaks that contact the cylindrical portion and elastically deform so as to extend in a circumferential direction of the bearing housing, and a plurality of valleys that contact the bearing housing, the peaks and the valleys being arranged alternately in the circumferential direction of the bearing housing, The foil bearing according to claim 1 , wherein the protrusion protrudes from the valley.

4. The foil bearing according to claim 1 , wherein the protrusion is provided at a second end of the main body in a circumferential direction of the bearing housing.

5. The foil bearing according to claim 1 , wherein a plurality of the bump foils are provided in the circumferential direction of the bearing housing.

Images