Foil bearing

Abstract

The present disclosure relates to a foil bearing. The foil bearing has a bearing case, a top foil, a wave foil, and two anti-disengagement portions. A retaining groove extending in an axial direction is formed in an inner peripheral surface of the bearing case. The top foil and the wave foil each have an insertion plate portion inserted into the retaining groove and extending in the axial direction. Each of the anti-disengagement portions has an opposing surface facing the insertion plate portion in the axial direction. In the axial direction, a distance between the opposing surfaces of the two anti-disengagement portions is longer than a length of the insertion plate portion. At least one of the insertion plate portions has a bent plate portion bent so as to abut against the opposing surface.

Description

Technical Field

[0001] This disclosure relates to foil bearings that support a rotating shaft in the radial direction. Background Technology

[0002] Japanese Patent Application Publication No. 2022-57207 discloses a centrifugal compressor that uses a foil bearing to support the rotating shaft in the radial direction.

[0003] The aforementioned foil bearing comprises a cylindrical bearing housing, a top foil, a corrugated foil, and an anti-detachment component. A rotating shaft is inserted through the bearing housing. The top foil is positioned between the rotating shaft and the bearing housing. The corrugated foil is positioned between the bearing housing and the top foil. The corrugated foil elastically supports the top foil. A retaining groove is formed on the inner circumferential surface of the bearing housing. The retaining groove opens at one end in the axial direction of the bearing housing. A portion of the top foil and a portion of the corrugated foil are inserted into the retaining groove. The anti-detachment component faces the top foil and corrugated foil in the axial direction of the bearing housing. Even if the top foil and corrugated foil move in the axial direction of the bearing housing, they will still contact the anti-detachment component. The anti-detachment component prevents the top foil and corrugated foil from falling off the bearing housing. Summary of the Invention

[0004] The problem that the invention aims to solve

[0005] When at least one of the top foil and the corrugated foil comes into contact with the anti-detachment part, sometimes at least one of the top foil and the corrugated foil is pressed against the anti-detachment part beyond what is necessary. As a result, at least one of the top foil and the corrugated foil and the anti-detachment part may wear.

[0006] Methods for solving problems

[0007] In one aspect of this disclosure, a foil bearing is provided that supports a rotating shaft radially. The foil bearing comprises: a cylindrical bearing housing through which the rotating shaft passes; a thin plate-shaped top foil disposed between the rotating shaft and the bearing housing; a thin plate-shaped corrugated foil disposed between the bearing housing and the top foil, elastically supporting the top foil; and two anti-detachment portions axially opposite to the top foil and the corrugated foil in the bearing housing, preventing the top foil and the corrugated foil from detaching from the bearing housing. A retaining groove extending axially is formed on the inner circumferential surface of the bearing housing. The top foil and the corrugated foil each have an insertion plate portion that inserts into the retaining groove and extends axially. Each of the anti-detachment portions has an opposing surface opposing the insertion plate portion axially. In the axial direction, the distance between the opposing surfaces of the two anti-detachment portions is longer than the length of the insertion plate portion. At least one of the insertion plate portion of the top foil and at least one of the insertion plate portion of the corrugated foil has a bent plate portion at at least one of its two ends in the axial direction, which is bent in a manner that abuts against the opposing surface. Attached Figure Description

[0008] Figure 1This is a schematic structural diagram showing a centrifugal compressor equipped with the foil bearing according to the first embodiment.

[0009] Figure 2 yes Figure 1 Front view of the foil bearing.

[0010] Figure 3 yes Figure 2 An exploded perspective view of a foil bearing.

[0011] Figure 4 yes Figure 2 A three-dimensional view of the bent plate section in a foil bearing.

[0012] Figure 5 It is shown Figure 2 A diagram showing the positional relationship between the anti-detachment component and the bent plate in a foil bearing.

[0013] Figure 6 It is along Figure 2 A sectional view along line 6-6.

[0014] Figure 7 This is a cross-sectional view of the foil bearing according to the second embodiment.

[0015] Figure 8 It is shown Figure 7 A cross-sectional view showing the function of a foil bearing.

[0016] Figure 9 This is a cross-sectional view of the foil bearing according to the third embodiment.

[0017] Figure 10 This is a perspective view of the bent plate portion in the foil bearing involved in the modification example.

[0018] Figure 11 This is a cross-sectional view of the foil bearing involved in the modification example.

[0019] Figure 12 This is an exploded perspective view of the foil bearing involved in the modification example.

[0020] Figure 13 This is a cross-sectional view of the foil bearing involved in the modification example.

[0021] Figure 14 This is a cross-sectional view of the foil bearing involved in the modification example. Detailed Implementation

[0022] [First Implementation]

[0023] Hereinafter, the first embodiment of the foil bearing will be described in accordance with Figures 1-6 To illustrate, the foil bearing in this embodiment is mounted on a centrifugal compressor.

[0024] Centrifugal compressor

[0025] like Figure 1 As shown, the centrifugal compressor 100 includes two foil bearings 10, a housing 101, an electric motor 102, a rotating shaft 103, and an impeller 104. The electric motor 102, rotating shaft 103, and impeller 104 are housed within the housing 101. The electric motor 102 is housed in a motor chamber 101a formed in the housing 101. The impeller 104 is housed 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 mounted on the rotating shaft 103. The impeller 104 is mounted at the end of the rotating shaft 103. Driven by the electric motor 102, the rotating shaft 103 rotates. When the rotating shaft 103 rotates, the impeller 104 rotates. When the impeller 104 rotates, fluid is introduced from outside the housing 101 into the impeller chamber 101b, and the introduced fluid is compressed within the impeller chamber 101b. The fluid compressed inside the impeller chamber 101b is discharged to the outside of the housing 101.

[0026] Two foil bearings 10 support the rotating shaft 103 radially Rd. The two foil bearings 10 are arranged on both sides of the electric motor 102 in the axial direction of the rotating shaft 103. The two foil bearings 10 are fixed to the housing 101.

[0027] <Foil Bearing>

[0028] like Figure 2 and Figure 3 As shown, the foil bearing 10 includes a cylindrical bearing housing 20, a thin plate-shaped top foil 30, three thin plate-shaped corrugated foils 40, and a pair of anti-detachment members 50. The bearing housing 20 is formed of aluminum, for example.

[0029] <Bearing Housing>

[0030] like Figure 2 As shown, a rotating shaft 103 is inserted into the bearing housing 20. In the following description, the axial direction of the bearing housing 20 is sometimes abbreviated as "axial A", the circumferential direction of the bearing housing 20 is abbreviated as "circumferential B", and the radial direction of the bearing housing 20 is abbreviated as "radial C". The bearing housing 20 has an inner circumferential surface 20a. The inner circumferential surface 20a is a cylindrical surface curved in the circumferential direction B.

[0031] like Figure 3As shown, the bearing housing 20 has a first end 21 and a second end 22. The first end 21 and the second end 22 are ends of the bearing housing 20 along the axial direction A. The first end 21 is one end of the bearing housing 20 along the axial direction A. The second end 22 is the other end of the bearing housing 20 along the axial direction A. A retaining groove 20b is formed on the inner circumferential surface 20a of the bearing housing 20. Three retaining grooves 20b are provided on the inner circumferential surface 20a. The three retaining grooves 20b are arranged at predetermined intervals in the circumferential direction B. The retaining grooves 20b extend in the axial direction A. Each retaining groove 20b extends along the entire length of the inner circumferential surface 20a in the axial direction A.

[0032] Annular notches 20c are formed at the first end 21 and the second end 22, respectively. Both notches 20c open outwards in the radial direction C. The notch 20c at the first end 21 opens in the axial direction A to the side opposite to the second end 22. The notch 20c at the second end 22 opens in the axial direction A to the side opposite to the first end 21. The notch 20c has a cylindrical surface 20d extending in the axial direction A and an annular surface 20e extending in the radial direction C. Each retaining groove 20b opens at both the cylindrical surface 20d and the annular surface 20e. Furthermore, in... Figure 2 The not shown cut groove 20c formed at the second end 22 is shown in the figure.

[0033] Top foil

[0034] like Figure 2 As shown, 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.

[0035] like Figure 3 As shown, the top foil 30 is formed by bending a flexible, elongated metal sheet into a cylindrical shape. The top foil 30 has a pair of long edges 30a and a pair of short edges 30b. Sometimes one of the pair of long edges 30a is referred to as the first long edge 30a and the other as the second long edge 30a. Sometimes one of the pair of short edges 30b is referred to as the first short edge 30b and the other as the second short edge 30b. The top foil 30 is generally 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 top foil 30 is formed by bending the pair of long edges 30a into a cylindrical shape such that the pair of long edges 30a extend in the circumferential direction B and the pair of short edges 30b extend in the axial direction A. The length between the pair of long edges 30a is the same as the length of the axial direction A of the bearing housing 20. The metal sheet forming the top foil 30 is, for example, formed of stainless steel or an Inconel (registered trademark) type nickel alloy.

[0036] The top foil 30 has a fixed end 31 and a free end 32. The fixed end 31 is formed by bending one end of the metal sheet forming the top foil 30 in the long side direction radially outward. The fixed end 31 includes a first short edge 30b of the top foil 30. The free end 32 is the other end of the metal sheet forming the top foil 30 in the long side direction. The free end 32 includes a second short edge 30b of the top foil 30. The free end 32 is circumferentially separated from and opposite the base end of the fixed end 31 in the circumferential direction B. Therefore, the top foil 30 is an annular body with a portion of its circumferential direction cut off.

[0037] The fixed end portion 31 has a cutout portion 31a and an insertion plate portion 31b. The cutout portion 31a is formed by cutting off a portion of each end edge in the axial direction A of the fixed end portion 31. One cutout portion 31a is formed by cutting off a portion of the first long edge 30a and a portion of the first short edge 30b. The other cutout portion 31a is formed by cutting off a portion of the second long edge 30a and a portion of the first short edge 30b. Each cutout portion 31a has a first cutout edge 311a and a second cutout edge 312a. The first cutout edge 311a extends in the radial direction C. The second cutout edge 312a is continuous with the first cutout edge 311a. The second cutout edge 312a extends in the axial direction A. The first cutout edges 311a of the two cutout portions 31a form the two ends of the insertion plate portion 31b in the axial direction A. The insertion plate portion 31b includes a first short edge 30b obtained by cutting off the notch portion 31a.

[0038] like Figure 2 As shown, one of the insertion plate portions 31b of the top foil 30 is inserted into the holding groove 20b. The top foil 30 has an insertion plate portion 31b that is inserted into the holding groove 20b and extends in the axial direction A.

[0039] <Wave foil>

[0040] Three corrugated foils 40 are disposed between the bearing housing 20 and the top foil 30. The three corrugated foils 40 are disposed with a predetermined interval in the circumferential direction B. The thickness of the corrugated foils 40 is thinner than that of the top foil 30.

[0041] like Figure 3 As shown, each corrugated foil 40 is formed by bending a flexible, elongated metal sheet into a generally arc shape. Each corrugated foil 40 has a pair of long edges 40a and a pair of short edges 40b. The direction of the short edges of each corrugated foil 40 is aligned with the axial direction A of the bearing housing 20. The length between the pair of long edges 40a is shorter than the length of the axial direction A of the bearing housing 20. The length between the pair of long edges 40a is shorter than the length between the pair of long edges 30a of the top foil 30. The metal sheet forming each corrugated foil 40 is, for example, made of stainless steel or an Inconel-type nickel alloy.

[0042] Each corrugated foil 40 has a fixed end 41 and a free end 42. The fixed end 41 is one end of the metal sheet forming the corrugated foil 40 along its long side. The fixed end 41 includes a short edge 40b of one side of the corrugated foil 40. The free end 42 is the other end of the metal sheet forming the corrugated foil 40 along its long side. The free end 42 includes a short edge 40b of the other side of the corrugated foil 40.

[0043] like Figure 2 As shown, each corrugated foil 40 has multiple valleys 43 that contact the inner circumferential surface 20a of the bearing housing 20. Each valley 43 extends along the inner circumferential surface 20a of the bearing housing 20. Each corrugated foil 40 has multiple peaks 44 that contact the outer circumferential surface of the top foil 30. Each peak 44 protrudes in a direction away from the inner circumferential surface 20a of the bearing housing 20. Each peak 44 is curved in an arc shape, bulging toward the outer circumferential surface of the top foil 30. Each corrugated foil 40 is corrugated in a wave shape by the alternating arrangement of valleys 43 and peaks 44 in the circumferential direction B. Each corrugated foil 40 has a structure in which valleys 43 and peaks 44 are arranged alternately from the fixed end 41 toward the free end 42. The peaks 44 are continuous with the fixed end 41 and the free end 42.

[0044] like Figure 4 As shown, each corrugated foil 40 has an insertion plate portion 41a at its fixed end 41. The insertion plate portion 41a extends in the axial direction A. The insertion plate portion 41a has a first portion 411a, a second portion 412a, and a bending plate portion 41b. The bending plate portion 41b is provided at both ends of the insertion plate portion 41a in the axial direction A. The portion including the first portion 411a and the second portion 412a has an L-shaped shape when viewed in the axial direction A. The first portion 411a is continuous with the peak portion 44. The first portion 411a has a thickness in the radial direction C. The first portion 411a extends in the axial direction A.

[0045] The second portion 412a extends outward from the end edge of the first portion 411a on the side opposite to the peak 44, toward the radial direction C. The second portion 412a extends in the axial direction A. The second portion 412a includes a short edge 40b of one side of the corrugated foil 40.

[0046] like Figure 3 and Figure 4As shown, a bent plate portion 41b is provided at both ends of the second portion 412a along the axial direction A. A cutout portion 413a is formed at both ends of the second portion 412a along the axial direction A. The cutout portion 413a is formed near the first portion 411a in the second portion 412a. The bent plate portion 41b is bent relative to the second portion 421a in a manner extending circumferentially from both ends of the second portion 412a along the axial direction A. The bent plate portion 41b is integrally formed in the second portion 412a. The bent plate portion 41b is bent relative to a portion of the insert plate portion 41a other than the bent plate portion 41b. The bent plate portion 41b extends circumferentially from both ends of the insert plate portion 41a toward the same side. Additionally, the bent plate portion 41b extends radially C. The bent plate portion 41b can also be fixed to the second portion 412a by welding or the like.

[0047] like Figure 4 As shown, the bent plate portion 41b has an end face 411b extending radially C. The end face 411b is coplanar with the long edge 40a of the corrugated foil 40. That is, the length between the two end faces 411b of the corrugated foil 40 is the same as the length between the pair of long edges 40a of the corrugated foil 40. The extension of the end face 411b from the second portion 412a in the circumferential direction B is at least greater than the thickness of the corrugated foil 40. In a direction orthogonal to both the direction in which the end face 411b extends from the second portion 412a and the thickness direction of the bent plate portion 41b, the length of the end face 411b is greater than the thickness of the corrugated foil 40. The bent plate portion 41b is sized to allow it to be inserted into the holding groove 20b.

[0048] like Figure 2 and Figure 4 As shown, the insertion plate portion 41a of each corrugated foil 40 is inserted into the corresponding retaining groove 20b. The second portion 412a and the two bent plate portions 41b of each corrugated foil 40 are inserted into the corresponding retaining groove 20b. The corrugated foil 40 has an insertion plate portion 41a that is inserted into the retaining groove 20b and extends in the axial direction A. The insertion plate portion 41a of one of the three corrugated foils 40 is inserted into one retaining groove 20b together with the insertion plate portion 31b of the top foil 30. The insertion plate portions 41a of the remaining two corrugated foils 40 are respectively inserted into the remaining two retaining grooves 20b. Regarding corrugated foils 40 adjacent in the circumferential direction B, the free end 42 of one corrugated foil 40 and the fixed end 41 of the other corrugated foil 40 are arranged with a predetermined gap. The three corrugated foils 40 are arranged radially outward from the top foil 30. The three corrugated foils 40 elastically support the top foil 30 between the bearing housing 20 and the top foil 30.

[0049] <Anti-detachment components>

[0050] like Figure 3As shown, the anti-detachment member 50 is annular. The inner diameter of the anti-detachment member 50 is the same as the outer diameter of the cylindrical surface 20d of the bearing housing 20. In the axial direction A, one anti-detachment member 50 is embedded in a notch 20c formed at the first end 21 of the bearing housing 20. In the axial direction A, the other anti-detachment member 50 is embedded in a notch 20c formed at the second end 22 of the bearing housing 20. The anti-detachment member 50 abuts against the annular surface 20e. The anti-detachment member 50 faces the retaining groove 20b that opens in the annular surface 20e in the axial direction A. The anti-detachment member 50 is fixed to the bearing housing 20 by a fixing means not shown.

[0051] like Figure 3 and Figure 5 As shown, the anti-detachment member 50 faces the insertion plate portion 31b of the top foil 30 and the insertion plate portion 41a of each corrugated foil 40 in the axial direction A. The anti-detachment member 50 also faces a portion of the bending plate portion 41b in the axial direction A. The anti-detachment member 50 is an anti-detachment part that faces the top foil 30 and the corrugated foil 40 in the axial direction A and prevents the top foil 30 and the corrugated foil 40 from falling off the bearing housing 20.

[0052] like Figure 6 As shown, each anti-detachment member 50 has a facing surface 50a that faces the insertion plate portions 31b and 41a in the axial direction A. The facing surface 50a is a surface that extends in the radial direction C. The facing surface 50a extends in a direction orthogonal to the axis of the bearing housing 20. In the axial direction A, the interval L1 between a pair of facing surfaces 50a is longer than the length L2 between the end faces 411b of the two bent plate portions 41b. That is, in the axial direction A, the interval L1 between a pair of facing surfaces 50a is longer than the length L2 of the insertion plate portion 41a. The facing surface 50a of the anti-detachment member 50 is parallel to the end face 411b of the bent plate portion 41b. As a result, the bent plate portion 41b extends along the facing surface 50a.

[0053] [The function of this implementation method]

[0054] Explain the function of this implementation method.

[0055] like Figure 2 As shown, if the rotating shaft 103 is rotating in the rotation direction D and the rotational speed of the rotating shaft 103 reaches a predetermined speed, an air film 105 is formed between the rotating shaft 103 and the top foil 30. As a result, the rotating shaft 103 floats up from the top foil 30. Furthermore, the rotating shaft 103 is supported in the radial direction Rd by the air film 105 in a non-contact state relative to the top foil 30.

[0056] While the rotating shaft 103 is rotating, it may tilt relative to the axis of the bearing housing 20. If the rotating shaft 103 tilts relative to the axis of the bearing housing 20, the thickness of the air film 105 becomes uneven in the axial direction A. Consequently, in the axial direction A, regions with low dynamic pressure and regions with high dynamic pressure are formed based on the radial direction Rd of the air film 105. As a result, a force acting on at least one of the top foil 30 and the corrugated foil 40 moves in the axial direction A. Consequently, at least one of the top foil 30 and the corrugated foil 40 may be pressed against the anti-detachment member 50 beyond what is necessary.

[0057] Furthermore, in this embodiment, the thickness of the corrugated foil 40 is thinner than that of the top foil 30. When there is no bending plate portion 41b in the corrugated foil 40 and the thickness of the corrugated foil 40 is thinner than that of the top foil 30, the wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 may be greater than the wear caused by the contact between the top foil 30 and the anti-detachment member 50.

[0058] In this embodiment, since the bent plate portion 41b is in contact with the opposing surface 50a, the contact area between the corrugated foil 40 and the anti-detachment member 50 can be ensured. This reduces the contact pressure between the corrugated foil 40 and the anti-detachment member 50. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 can be suppressed.

[0059] [Effects of this implementation method]

[0060] Explain the effects of this implementation method.

[0061] (1-1) Since the bent plate portion 41b is in contact with the opposing surface 50a, the contact area between the corrugated foil 40 and the anti-detachment member 50 can be ensured. As a result, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be reduced. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, wear on the corrugated foil 40 and the anti-detachment member 50 can be suppressed.

[0062] (1-2) In the case that there is no bending plate portion 41b in the corrugated foil 40 and the thickness of the corrugated foil 40 is thinner than the thickness of the top foil 30, the wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 may be greater than the wear caused by the contact between the top foil 30 and the anti-detachment member 50.

[0063] In this respect, according to this embodiment, since a bending plate portion 41b is provided in the insertion plate portion 41a of the corrugated foil 40, the effect of suppressing wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 can be more significant.

[0064] (1-3) The bent plate portion 41b extends in the circumferential direction B from both ends of the insertion plate portion 41a toward the same side. Therefore, compared to the case where the bent plate portion 41b extends from the insertion plate portion 41a toward opposite sides, the width of the retaining groove 20b in the circumferential direction B can be reduced. As a result, the amount of machining required for the bearing housing 20 can be reduced, and thus the decrease in strength of the foil bearing 10 can be suppressed.

[0065] [Second Implementation]

[0066] Hereinafter, the second embodiment of the foil bearing will be described according to... Figure 7 and Figure 8 To illustrate. Furthermore, for structures identical to those in the first embodiment, the same reference numerals are used, and detailed descriptions are omitted.

[0067] <Bent-down plate section>

[0068] like Figure 7 As shown, the angle θ1 between the bent plate portion 41b and the second portion 412a is an obtuse angle. The bent plate portion 41b is connected to the second portion 412a at an obtuse angle. The second portion 412a is a main plate portion extending in the axial direction A inside the retaining groove 20b. The insertion plate portion 41a has the main plate portion, namely the second portion 412a, extending in the axial direction A inside the retaining groove 20b.

[0069] Along axis A, the distance L1 between a pair of opposing surfaces 50a is longer than the length L3 between the top ends of the two bent plate portions 41b. That is, along axis A, the distance L1 between a pair of opposing surfaces 50a is longer than the length L3 of the insertion plate portion 41a.

[0070] A bend 45 is formed at the junction of the second part 412a and the bend plate part 41b. The bend 45 is a spring structure. Figure 7 The angle θ1 shown is the angle before the corrugated foil 40 and the anti-detachment component 50 come into contact.

[0071] like Figure 8 As shown, in this embodiment, if the bent plate portion 41b is pressed against the anti-detachment member 50, the angle θ2 formed by the bent plate portion 41b and the second portion 412a becomes smaller than the angle θ1. If the corrugated foil 40 is continuously pressed against the anti-detachment member 50, the bent plate portion 41b continues to flex in a manner that increases the area of ​​the bent plate portion 41b in contact with the opposing surface 52a of the anti-detachment member 50.

[0072] exist Figure 8The diagram shows a state where a portion of the bent plate portion 41b is in contact with the opposing surface 50a of the anti-detachment member 50. If the corrugated foil 40 is continuously pressed against the anti-detachment member 50 from this state, it will deform by extending the bent plate portion 41b along the opposing surface 50a of the anti-detachment member 50, and the angle θ2 may become 90 degrees. In this embodiment, the material forming the corrugated foil 40, the thickness of the corrugated foil 40, the rigidity of the bent plate portion 41b, and the angle θ1 are adjusted in such a way that the contact area between the bent plate portion 41b and the opposing surface 50a of the anti-detachment member 50 increases as the corrugated foil 40 is pressed against the opposing surface 50a of the anti-detachment member 50. Alternatively, even if the corrugated foil 40 is continuously pressed against the anti-detachment member 50, the bent plate portion 41b may not bend to extend along the opposing surface 50a.

[0073] [The function of this implementation method]

[0074] Explain the function of this implementation method.

[0075] According to this embodiment, the bend 45 between the bend plate portion 41b and the second portion 412a forms a spring structure. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the load applied to the corrugated foil 40 and the anti-detachment member 50 is absorbed by the elasticity of the bend 45. As a result, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 decreases, and thus wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 is suppressed.

[0076] [Effects of this implementation method]

[0077] Explain the effects of this implementation method.

[0078] (2-1) The bend 45 between the bend plate portion 41b and the second portion 412a forms a spring structure. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the load applied to the corrugated foil 40 and the anti-detachment member 50 is absorbed by the elasticity of the bend 45. As a result, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 decreases, thereby suppressing wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50.

[0079] (2-2) If the corrugated foil 40 is continuously pressed against the anti-detachment member 50, the bending plate portion 41b continuously flexes in a manner that increases the contact area with the opposing surface 50a of the anti-detachment member 50. Therefore, the contact area between the corrugated foil 40 and the anti-detachment member 50 can be ensured. Consequently, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be reduced by increasing the contact area between the bending plate portion 41b and the opposing surface 50a. Therefore, wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 can be further suppressed.

[0080] <Third Implementation Method>

[0081] The third embodiment of the foil bearing will be described below. Figure 9 To illustrate. Furthermore, for structures identical to those in the first embodiment, the same reference numerals are used, and detailed descriptions are omitted.

[0082] <Buffer Section>

[0083] like Figure 9 As shown, the insert plate portion 41a of the corrugated foil 40 has a buffer portion 41c. The buffer portion 41c is a plate-shaped portion connected to the second portion 412a and the bending plate portion 41b. The second portion 412a is a main plate portion extending in the axial direction A inside the holding groove 20b. The insert plate portion 41a has the bending plate portion 41b, the second portion 412a, and the buffer portion 41c. The angle θ3 formed by the buffer portion 41c and the second portion 412a is an obtuse angle. The angle θ4 formed by the bending plate portion 41b and the buffer portion 41c is an obtuse angle. Figure 9 The angles θ3 and θ4 shown are the angles before the corrugated foil 40 and the anti-detachment member 50 come into contact. A bent portion 47 is formed at the junction of the buffer portion 41c and the second portion 412a. The bent portion 47 is a spring structure. A bent portion 48 is formed at the junction of the bent plate portion 41b and the buffer portion 41c. The bent portion 48 is a spring structure. Furthermore, the bent plate portion 41b extends along the opposing surface 50a in the same manner as in the first embodiment.

[0084] Along the axial direction A, the distance L1 between a pair of opposing surfaces 50a is longer than the length L4 between the end faces 411b of the two bent plate portions 41b. In other words, along the axial direction A, the distance L1 between a pair of opposing surfaces 50a is longer than the length L4 of the insertion plate portion 41a. Furthermore, the buffer portion 41c moves away from the opposing surface 50a. Thus, a predetermined gap S is formed between the buffer portion 41c and the opposing surface 50a.

[0085] [The function of this implementation method]

[0086] Explain the function of this implementation method.

[0087] When the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the end face 411b of the bent plate portion 41b abuts against the opposing surface 50a. If the bent plate portion 41b is pressed further against the opposing surface 50a, the angles θ3 and θ4 increase. The buffer portion 41c is provided between the second portion 412a and the bent plate portion 41b such that the angles θ3 and θ4 change due to the abutment between the opposing surface 50a and the bent plate portion 41b.

[0088] Even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be reduced by the contact between the bent plate portion 41b and the opposing surface 50a.

[0089] Furthermore, the bend 47 between the second part 412a and the buffer part 41c, and the bend 48 between the buffer part 41c and the bend plate part 41b, form a spring structure. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the load applied to the corrugated foil 40 and the anti-detachment member 50 is elastically absorbed by the two bends 47 and 48. Thus, in addition to the surface contact between the bend plate part 41b and the opposing surface 50a, the elastic deformation of the two bends 47 and 48 further suppresses wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50.

[0090] [Effects of this implementation method]

[0091] Explain the effects of this implementation method.

[0092] (3-1) Even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be reduced by the contact between the bent plate portion 41b and the opposing surface 50a.

[0093] Furthermore, the bend 47 between the second part 412a and the buffer part 41c, and the bend 48 between the buffer part 41c and the bending plate part 41b, form a spring structure. Therefore, even if the corrugated foil 40 is pressed against the anti-detachment member 50 beyond what is necessary, the load applied to the corrugated foil 40 and the anti-detachment member 50 is elastically absorbed by the two bends 47 and 48. Thus, in addition to the surface contact between the bending plate part 41b and the opposing surface 50a, the elastic deformation of the two bends 47 and 48 can further suppress wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50.

[0094] [Example of Change]

[0095] Furthermore, the above embodiments can be modified as follows. The above embodiments and the following modifications can be combined with each other within the scope of technical non-contradiction.

[0096] The bent plate portion 41b may also extend in the circumferential direction B from both ends of the insertion plate portion 41a toward opposite sides.

[0097] ○ For example Figure 10 As shown, the bent plate portion 41b may also be integrally formed on the first portion 411a of the insertion plate portion 41a. The bent plate portion 41b is bent relative to the first portion 411a in a radially C-directed manner. The radial extension of the end face 411b from the first portion 411a is at least greater than the thickness of the corrugated foil 40. In a direction orthogonal to both the extension direction of the end face 411b from the first portion 411a and the thickness direction of the bent plate portion 41b, the length of the end face 411b is greater than the thickness of the corrugated foil 40. Furthermore, the bent plate portion 41b may also be fixed to the first portion 411a by welding or the like.

[0098] ○ For example Figure 11 As shown, the insertion plate portion 31b of the top foil 30 may also have a bent plate portion 31c extending along the opposing surface 50a of the anti-detachment member 50. The bent plate portion 31c may also be provided in the insertion plate portion 31b. In this modified example, the bent plate portions 31c are provided at both ends of the insertion plate portion 31b along the axial direction A. The bent plate portion 31c has an end face 311c. The end face 311c extends parallel to the opposing surface 50a of the anti-detachment member 50. In this modified case, the bent plate portions 31c and 41b may not overlap each other along the axial direction A.

[0099] Along axis A, the length between the end faces 311c of the two bent plate portions 31c can be the same as the length L2. That is, along axis A, the interval L1 between a pair of opposing surfaces 50a is longer than the length L2 of the insert plate portion 31b. Furthermore, the length of the insert plate portion 31b can also be different from the length L2. As long as the interval L1 is longer than the length of the insert plate portion 31b, the length of the insert plate portion 31b can also be appropriately changed.

[0100] ○ in Figure 11 In the above-described modified example, when the insertion plate portion 31b has a bent plate portion 31c, the portion of the insertion plate portion 31b that extends axially in the direction A inside the retaining groove 20b is the main plate portion of the insertion plate portion 31b. Furthermore, the bent plate portion 31c may also be connected to the main plate portion of the insertion plate portion 31b at an obtuse angle.

[0101] ○ in Figure 11 In the above-described modified example, the insertion plate portion 31b may also have the same structure as the buffer portion 41c described in the third embodiment.

[0102] Alternatively, the bending plate portion 41b of the corrugated foil 40 can be omitted, and the top foil 30 can have a bending plate portion 31c. That is, bending plate portions 31c and 41b can be provided on at least one of the insertion plate portion 31b of the top foil 30 and the insertion plate portion 41a of the corrugated foil 40. If at least one of the bending plate portions 31c and 41b is present, wear caused by contact between at least one of the top foil 30 and the corrugated foil 40 and the anti-detachment member 50 can be suppressed.

[0103] The thickness of the corrugated foil 40 and the top foil 30 can be the same. The thickness of the top foil 30 can also be thinner than that of the corrugated foil 40.

[0104] The fixed end 31 of the top foil 30 may also not have a cutout 31a.

[0105] Alternatively, when a pair of anti-detachment components 50 are fixed to the bearing housing 20, the bent plate portion 41b is already in contact with the opposing surface 50a of the anti-detachment component 50.

[0106] ○ The position of the notch groove 20c can also be appropriately changed in the radial direction C. The notch groove 20c only needs to be a structure that can accommodate the anti-detachment component 50.

[0107] ○ The pair of anti-detachment components 50 can also be modified as follows. Furthermore, the explanation is based on the premise that the notch 20c of the bearing housing 20 is omitted.

[0108] like Figure 12 As shown, the anti-detachment component 50 has a main body 51 and three fixing parts 52. The main body 51 is annular. The outer diameter of the main body 51 is slightly smaller than the inner diameter of the bearing housing 20. The inner diameter of the main body 51 is larger than the outer diameter of the top foil 30.

[0109] Each fixing part 52 protrudes radially outward from the outer peripheral surface of the main body part 51. The fixing parts 52 are provided in the main body part 51 with predetermined intervals in the circumferential direction. Each fixing part 52 is provided in the main body part 51 in a manner corresponding to each retaining groove 20b of the bearing housing 20.

[0110] A pair of anti-detachment members 50 are disposed on the inner side of the bearing housing 20. Each fixing part 52 is disposed in a corresponding retaining groove 20b. Each fixing part 52 is pressed into the corresponding retaining groove 20b. Thus, the anti-detachment members 50 are fixed to the bearing housing 20. The outer peripheral surface of the main body 51 extends along the inner peripheral surface 20a of the bearing housing 20. The main body 51 faces a portion of the fixing end 31 of the top foil 30 and a portion of the fixing end 41 of the corrugated foil 40 in the axial direction A. The main body 51 faces each valley 43 of the corrugated foil 40 and a portion of each peak 44 in the axial direction A. That is, the pair of anti-detachment members 50 face the top foil 30 and the corrugated foil 40 in the axial direction A.

[0111] One anti-detachment member 50's fixing portion 52 is pressed into the retaining groove 20b from the first end 21 of the bearing housing 20. The remaining anti-detachment member 50's fixing portion 52 is pressed into the retaining groove 20b from the second end 22 of the bearing housing 20. The fixing portions 52 of the pair of anti-detachment members 50 clamp the insertion plate portion 41a of the corrugated foil 40 in the axial direction A. In one retaining groove 20b, the fixing portions 52 of the pair of anti-detachment members 50 also clamp the insertion plate portion 31b of the top foil 30 in the axial direction A. In summary, the two anti-detachment members 50 prevent the top foil 30 and the corrugated foil 40 from falling off the bearing housing 20. The fixing portion 52 preferably has a opposing surface 52a facing the insertion plate portions 31b, 41a in the axial direction A. The opposing surface 52a is a surface extending in the radial direction C.

[0112] ○ For example Figure 13As shown, for example, a bent plate portion 41b may be provided only at one end of the insertion plate portion 41a along the axial direction A. Therefore, it is sufficient that the bent plate portion 41b is provided at least one of the two ends of the insertion plate portion 41a along the axial direction A. Furthermore, the anti-detachment member 50 facing the other end of the insertion plate portion 41a may also have an anti-detachment main body portion 55 and an elastic portion 56. The anti-detachment main body portion 55 may be, for example, annular. The elastic portion 56 is provided on the portion of the anti-detachment main body portion 55 facing the insertion plate portion 41a along the axial direction A. Therefore, the elastic portion 56 is provided on the anti-detachment main body portion 55. The elastic portion 56 may be, for example, a rubber member. The elastic portion 56 is configured to be elastically deformable. In addition, the elastic portion 56 may be, for example, a resin coating formed by coating the portion of the anti-detachment main body portion 55 facing the insertion plate portion 41a along the axial direction A with resin. In short, the elastic portion 56 is sufficient as long as it is provided on the anti-detachment main body portion 55 and configured to be elastically deformable. The side of the elastic part 56 opposite to the anti-detachment main body part 55 is the opposing surface 50a, which faces the insertion plate part 41a. Therefore, the elastic part 56 includes the opposing surface 50a.

[0113] According to the above structure, since the elastic portion 56 includes the opposing surface 50a, even if, for example, the end of the insert plate portion 41a without the bending plate portion 41b is pressed against the anti-detachment member 50 beyond what is necessary, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be mitigated by the elastic portion 56. Therefore, even if the bending plate portion 41b is not provided at one of the two ends of the axial direction A of the insert plate portion 41a, wear on the corrugated foil 40 and the anti-detachment member 50 can be suppressed.

[0114] ○ For example Figure 14 As shown, for example, a bent plate portion 41b may be provided only at one of the two ends of the insertion plate portion 41a along the axial direction A. Therefore, it is sufficient to provide a bent plate portion 41b at at least one of the two ends of the insertion plate portion 41a along the axial direction A. Furthermore, the anti-detachment member 50 facing the bent plate portion 41b in the axial direction A of the pair of anti-detachment members 50 may also be formed of a non-magnetic material. Examples of non-magnetic materials are stainless steel and aluminum. Moreover, the anti-detachment member 50 facing the end of the insertion plate portion 41a that does not have a bent plate portion 41b may also be formed of a magnetic material. Examples of magnetic materials are stainless steel and iron.

[0115] The anti-detachment member 50 made of magnetic material has higher wear resistance than the anti-detachment member 50 made of non-magnetic material. Therefore, even if, for example, the end of the insertion plate portion 41a without the bending plate portion 41b is pressed against the anti-detachment member 50 beyond what is necessary, wear on the anti-detachment member 50 can be suppressed. Thus, even if one of the two axial ends of the insertion plate portion 41a is not provided with the bending plate portion 41b, wear on the anti-detachment member 50 can be suppressed.

[0116] Therefore, considering wear resistance, the anti-detachment member 50 is preferably formed of a magnetic material. On the other hand, if the anti-detachment member 50 is formed of a magnetic material, the coil of the electric motor 102 may be heated by the magnetic flux generated from the anti-detachment member 50. Therefore, it is conceivable that the anti-detachment member 50 closer to the electric motor 102 in a pair of anti-detachment members 50 is formed of a non-magnetic material. However, if the anti-detachment member 50 is formed of a non-magnetic material, its wear resistance is lower compared to the anti-detachment member 50 formed of a magnetic material. Therefore, the anti-detachment member 50 formed of a non-magnetic material faces the bent plate portion 41b in the axial direction A. Thus, even if the anti-detachment member 50 closer to the electric motor 102 is formed of a non-magnetic material, the contact pressure between the corrugated foil 40 and the anti-detachment member 50 can be reduced through the surface contact between the bent plate portion 41b and the opposing surface 50a. Therefore, wear caused by the contact between the corrugated foil 40 and the anti-detachment member 50 can be suppressed.

[0117] ○ in Figure 12 In the above-described modified example, the main body 51 may be omitted, and only the fixing part 52 pressed into the retaining groove 20b may be used as the anti-detachment part.

[0118] Alternatively, the notch 20c of the bearing housing 20 can be omitted, and a pair of anti-detachment members 50 can be fixed to the two end faces of the bearing housing 20 along the axial direction A. The anti-detachment member 50 may also have a facing surface that covers the retaining groove 20b along the axial direction A and faces the insertion plate portions 31b and 41a. In this modified example, the means of fixing the anti-detachment member 50 to the bearing housing 20 may be, for example, bolts or adhesive. In short, anything that can fix the anti-detachment member 50 to the bearing housing 20 is acceptable. Furthermore, the anti-detachment member 50 may also be an elastic retaining ring.

[0119] ○ Alternatively, one of the pair of anti-disengagement members 50 may be omitted. In this case, it is preferable to block the portion of the retaining groove 20b that opens at the first end 21 or the second end 22 of the bearing housing 20. The opening portion of the retaining groove 20b may also be blocked by a portion of the bearing housing 20. In this case, the portion of the bearing housing 20 that blocks the opening portion of the retaining groove 20b may also serve as the anti-disengagement part. In short, the bearing housing 20 may also have an anti-disengagement part. The anti-disengagement part of the bearing housing 20 has a facing surface that faces the insertion plate portions 31b and 41a in the axial direction A.

[0120] The opposing surface 50a may not extend in a direction orthogonal to the axis of the bearing housing 20. The opposing surface 50a may also be inclined relative to the axis of the bearing housing 20. The opposing surface 50a may extend radially C.

[0121] Although three corrugated foils 40 are used, a single, generally cylindrical corrugated foil 40 can also be used. In this case, the retaining groove 20b of the bearing housing 20 can be only one.

[0122] The foil bearing 10 is not limited to supporting the rotating shaft 103 of the centrifugal compressor 100 in the radial direction Rd. The application of the foil bearing 10 can also be appropriately changed.

Claims

1. A foil bearing, which supports a rotating shaft radially, wherein, have: A cylindrical bearing housing through which the rotating shaft is inserted; A thin plate-shaped top foil is disposed between the rotating shaft and the bearing housing; A thin, plate-shaped corrugated foil is disposed between the bearing housing and the top foil, elastically supporting the top foil; and Two anti-detachment parts are positioned axially opposite the top foil and the corrugated foil of the bearing housing to prevent the top foil and the corrugated foil from detaching from the bearing housing. A retaining groove extending in the axial direction is formed on the inner circumferential surface of the bearing housing. The top foil and the corrugated foil each have an insertion plate portion that is inserted into the retaining groove and extends in the axial direction. Each of the anti-detachment portions has a facing surface that faces the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil in the axial direction. In the axial direction, the distance between the opposing surfaces of the two anti-detachment portions is longer than the length of each of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil. At least one of the insertion plate portion of the top foil and at least one of the insertion plate portion of the corrugated foil has a bent plate portion at at least one of its two ends in the axial direction, which is bent in a manner that abuts against the opposing surface.

2. The foil bearing according to claim 1, The bent plate extends along the opposite surface.

3. The foil bearing according to claim 1, The opposing surface extends in a direction orthogonal to the axis of the bearing housing. The insertion plate portion of the top foil and the insertion plate portion of the corrugated foil each have a main body plate portion extending in the axial direction inside the retaining groove. The bent plate portion is connected to the main plate portion at an obtuse angle.

4. The foil bearing according to claim 2, At least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil has: The bent plate portion; The main body plate extends axially within the retaining groove; and The buffer section is a plate-shaped portion connected to the main body plate and the bent plate. The buffer portion is disposed between the main body plate and the bent plate portion in such a way that the angle between the buffer portion and the main body plate portion and the angle between the buffer portion and the bent plate portion changes due to the contact between the opposing surface and the bent plate portion.

5. The foil bearing according to claim 4, A gap is formed between the buffer section and the opposing surface.

6. The foil bearing according to any one of claims 1 to 5, The thickness of the corrugated foil is thinner than that of the top foil. The bending plate portion is disposed on the insertion plate portion of the corrugated foil.

7. The foil bearing according to any one of claims 1 to 5, The bending plate portion is provided at both ends of at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil. The bending plate portion extends circumferentially from at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil toward the same side.

8. The foil bearing according to any one of claims 1 to 5, The bending plate portion is provided only at one of the two ends of at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil. The anti-detachment portion, which faces the other end of at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil, has an anti-detachment main body and an elastic portion disposed on the anti-detachment main body and capable of elastic deformation. The elastic portion includes the opposing surface.

9. The foil bearing according to any one of claims 1 to 5, The bending plate portion is provided only at one of the two ends of at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil. The anti-detachment part opposite to the bent plate part is made of a non-magnetic material. The anti-detachment portion, which faces the other end of at least one of the insertion plate portion of the top foil and the insertion plate portion of the corrugated foil, is formed of magnetic material.

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