Foil bearing device

Abstract

A foil bearing device that rotatably supports a rotating shaft is provided with: an annular member having an insertion hole through which the rotating shaft is inserted; a top foil having an arc-shaped cross-section and disposed between the inner peripheral surface of the annular member and the outer peripheral surface of the rotating shaft so as to surround the entire outer periphery of the rotating shaft; and a bump foil disposed so as to surround the entire outer circumference of the top foil and supported on the inner circumferential surface of the annular member, the bump foil including a plurality of wave portions protruding toward the top foil and having at least a portion thereof in contact with the top foil, the plurality of wave portions including a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, and the first wave portion and the second wave portion being disposed so as to extend in the circumferential direction of the top foil when the inner circumferential surface of the bump foil is observed. The first wave portion and the second wave portion extend in the axial direction of the rotating shaft such that the extending directions of the first wave portion and the second wave portion intersect each other.

Description

Technical Field

[0001] The present invention relates to a foil bearing device for rotatably supporting a rotating shaft. Background Art

[0002] Foil bearings consist of a top foil that forms a bearing surface for the rotating shaft of a turbo blower or turbo compressor, and a corrugated foil that elastically supports the top foil. As the shaft rotates, a fluid film (air film) forms between the top foil's bearing surface and the shaft, rotatably supporting the shaft via this air film. This foil bearing automatically forms an appropriate air film based on the shaft's rotational speed, making it particularly effective for high-speed rotating shafts.

[0003] The bearing surface of a foil bearing is sometimes formed in a plurality of arc shapes to attenuate vibrations generated when the rotating shaft rotates. For example, Patent Document 1 discloses a foil bearing in which the rotating shaft is surrounded by three top foils distributed around the rotating shaft, each of which has an arc shape. Specifically, Patent Document 1 discloses a foil bearing whose bearing surface is formed of three three-arc shapes.

[0004] Previous technical literature Patent Literature Patent Document 1: U.S. Patent Application Publication No. 2019 / 0003524 Summary of the Invention

[0005] Technical issues to be solved by the invention However, the technology described in Patent Document 1 requires multiple top foils and corresponding corrugated foils, potentially reducing the assemblability of the foil bearing. Furthermore, the structure of the corrugated foils for elastically supporting the top foils (see the corrugated foil in Patent Document 1) is complex, potentially reducing the assemblability and manufacturability of the foil bearing.

[0006] The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a foil bearing device capable of suppressing a decrease in assemblability and manufacturability and enhancing the effect of damping vibrations generated by the rotation of a rotating shaft.

[0007] Means for solving technical problems In order to achieve the above-mentioned purpose, the foil bearing device involved in the present invention is a foil bearing device that rotatably supports a rotating shaft, which comprises: an annular component having an insertion hole for inserting the rotating shaft; a top foil with an arc-shaped cross-section, which is arranged to surround the entire outer circumference of the rotating shaft between the inner circumferential surface of the annular component and the outer circumferential surface of the rotating shaft; and a wave foil, which is arranged to surround the entire outer circumference of the top foil and is supported on the inner circumferential surface of the annular component, the wave foil including a plurality of wave portions protruding toward the top foil and at least a portion of which abuts the top foil, the plurality of wave portions including a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, and when the inner circumferential surface of the wave foil is unfolded and observed, the first wave portion and the second wave portion extend along the axial direction of the rotating shaft in a manner such that their respective extension directions intersect with each other.

[0008] In order to achieve the above-mentioned purpose, the foil bearing device involved in the present invention is a foil bearing device that rotatably supports a rotating shaft, which comprises: an annular component having an insertion hole for inserting the rotating shaft; a top foil with an arc-shaped cross-section, which is arranged to surround the entire outer circumference of the rotating shaft between the inner circumferential surface of the annular component and the outer circumferential surface of the rotating shaft; and a wave foil, which is arranged to surround the entire outer circumference of the top foil and is supported on the inner circumferential surface of the annular component, the wave foil including a plurality of wave portions protruding toward the top foil and at least partially abutting the top foil, the plurality of wave portions including a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, and the first wave portion and the second wave portion having different rigidities from each other.

[0009] Effects of the Invention According to the foil bearing device of the present invention, it is possible to enhance the effect of damping vibrations generated by the rotation of the rotating shaft while suppressing a decrease in assemblability and manufacturability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The diagram schematically shows the structure of a turbo compressor including foil bearing devices according to several embodiments.

[0011] Figure 2 It is a cross-sectional view schematically showing the structure of the foil bearing device according to the first embodiment.

[0012] Figure 3 This is a developed view showing a portion of the inner peripheral surface of the bump foil according to the first embodiment in a developed manner.

[0013] Figure 4A These are diagrams for explaining the operation and effects of the foil bearing device according to the first embodiment.

[0014] Figure 4B These are diagrams for explaining the operation and effects of the foil bearing device according to the first embodiment.

[0015] Figure 5A It is a diagram schematically showing the structure of a first modified example of the bump foil according to the first embodiment.

[0016] Figure 5B It is a diagram schematically showing the structure of a second modified example of the bump foil according to the first embodiment.

[0017] Figure 6 This is a developed view showing a portion of the inner peripheral surface of the bump foil according to the second embodiment.

[0018] Figure 7 This is a developed view showing a portion of the inner peripheral surface of the bump foil according to the third embodiment.

[0019] Figure 8 It is a diagram schematically showing the structure of a bump foil according to the third embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, a foil bearing device according to an embodiment of the present invention will be described with reference to the accompanying drawings. The above embodiment shows one aspect of the present invention and does not limit the present invention, and any changes can be made within the scope of the technical concept of the present invention.

[0021] Figure 1 Schematically shows the structure of a turbo compressor 100 including foil bearing devices 1 according to several embodiments. Figure 1 As shown, the turbo compressor 100 includes a rotating shaft 102 , an electric motor 104 that rotates the rotating shaft 102 , an impeller 106 that compresses a fluid by rotating integrally with the rotating shaft 102 , a housing 108 that accommodates the electric motor 104 and the impeller 106 , and the foil bearing device 1 .

[0022] exist Figure 1 In the illustrated embodiment, the impeller 106 includes a first impeller 106A (106) and a second impeller 106B (106). The first impeller 106A is connected to one end of the rotating shaft 102, and the second impeller 106B is connected to the other end of the rotating shaft 102. The first impeller 106A is located on the opposite side of the second impeller 106B with the electric motor 104 in the axial direction D1 of the rotating shaft 102 (hereinafter referred to as "axial direction D1"). This turbo compressor 100 further compresses the fluid compressed by the first impeller 106A by the second impeller 106B to generate a high-pressure fluid.

[0023] In the present invention, the direction from the second impeller 106B toward the first impeller 106A in the axial direction D1 is defined as one side in the axial direction D1, and the direction from the first impeller 106A toward the second impeller 106B in the axial direction D1 is defined as the other side in the axial direction D1.

[0024] The foil bearing device 1 rotatably supports the rotating shaft 102. The foil bearing device 1 supports the rotating shaft 102 in a contact state until the rotation speed of the rotating shaft 102 reaches the floating speed at which the rotating shaft 102 floats. When the rotation speed of the rotating shaft 102 reaches the floating speed, the foil bearing device 1 supports the rotating shaft 102 in a non-contact state via the fluid film (air film) formed between the bearing surface of the top foil 4 and the rotating shaft 102. Figure 1 In the illustrated embodiment, the turbo compressor 100 includes a pair of foil bearing devices 1, 1 arranged to sandwich the electric motor 104 from both sides in the axial direction D1. That is, the rotating shaft 102 is supported at both ends by the pair of foil bearing devices 1, 1.

[0025] In the present invention, the foil bearing device 1 is applied to a turbo compressor 100. However, the device to which the foil bearing device 1 is applied is not limited to the turbo compressor 100. The foil bearing device 1 according to the present invention is applied to a rotating device having a rotating shaft 102, and is particularly applied to a rotating device having a rotating shaft capable of high-speed rotation. For example, the rotating device includes a turbocharger or a turbo blower. Furthermore, the turbo compressor 100 is not limited to Figure 1 For example, the turbo compressor 100 may be configured without the second impeller 106B.

[0026] <First embodiment> (structure) The structure of the foil bearing device 1A ( 1 ) according to the first embodiment will be described. Figure 2 : is a cross-sectional view schematically showing the structure of the foil bearing device 1A according to the first embodiment, and the foil bearing device 1A is observed after being cut along a direction perpendicular to the axial direction D1. Figure 2 As illustrated, the foil bearing device 1A includes an annular member 2 , a top foil 4 , and a bump foil 6 .

[0027] The annular member 2 has an insertion hole 3 through which the rotating shaft 102 is inserted. In the first embodiment, the annular member 2 has a cylindrical shape, and the inner diameter of the annular member 2 is larger than the outer diameter of the rotating shaft 102. In some embodiments, the casing 108 of the turbo compressor 100 includes the annular member 2. In this case, the annular member 2 is a part of the casing 108.

[0028] The top foil 4 is arranged between the inner peripheral surface 8 of the annular member 2 and the outer peripheral surface 110 of the rotating shaft 102 so as to surround the entire outer periphery of the rotating shaft 102. Figure 2 As illustrated, when the top foil 4 is viewed in a cross section cut in a direction perpendicular to the axial direction D1 , the top foil 4 has an arc shape.

[0029] The top foil 4 is formed by bending a flexible metal plate made of stainless steel into a cylindrical shape, for example. Figure 2 In the illustrated embodiment, one end 10 of the top foil 4 in the circumferential direction D2 (hereinafter referred to as "circumferential direction D2") is bent outward in the radial direction D3 (hereinafter referred to as "radial direction D3") of the top foil 4. The top foil 4 is positioned within the annular member 2 with the one end 10 in the circumferential direction D2 retained by the annular member 2. The other end 12 of the top foil 4 in the circumferential direction D2 is slightly spaced apart from the one end 10 in the circumferential direction D2.

[0030] In the present invention, the circumferential direction D2 is the circumferential direction centered on the center line O1 of the top foil 4. Figure 2 On the paper, the direction from the other end 12 of the top foil 4 toward the one end 10 (in the counterclockwise direction) is defined as one side in the circumferential direction D2, and the direction from the one end 10 of the top foil 4 toward the other end 12 (in the clockwise direction) is defined as the other side in the circumferential direction D2. The radial direction D3 is a direction perpendicular to the centerline O1. The direction closer to the centerline O1 is defined as the inner side in the radial direction D3, and the direction farther from the centerline O1 is defined as the outer side in the radial direction D3.

[0031] In the first embodiment, as Figure 2 In this example, the angular position of an imaginary line passing through the center line O1 and one end 10 of the top foil 4 (hereinafter referred to as the first imaginary line L1) is set to 0 degrees. The angular position of the first imaginary line L1, which increases as the angular position increases toward the other side (counterclockwise) in the circumferential direction D2 about the center line O1 of the top foil 4, is defined as 360 degrees. The other end 12 of the top foil 4 is located at an angular position of at least 350 degrees but less than 360 degrees. Furthermore, the first imaginary line L1 extends from the center line O1 in the direction opposite to the direction of gravity (upward in the vertical direction).

[0032] The bump foil 6 is arranged to surround the entire outer circumference of the top foil 4. The bump foil 6 is supported by the inner circumferential surface 8 of the annular member 2. The bump foil 6 is formed by bending a flexible metal plate made of stainless steel into a cylindrical shape. Figure 2 In the illustrated embodiment, the bump foil 6 extends throughout the entire circumferential direction D2 and contacts the inner circumferential surface 8 of the annular member 2. The bump foil 6 is configured to allow one end 10 of the top foil 4 to pass through. Although not shown, in some embodiments, the plurality of bump foils 6 are separate bodies and are continuously arranged along the circumferential direction D2.

[0033] The bump foil 6 includes multiple undulations 14 that protrude toward the top foil 4 and at least partially abut against the top foil 4. Each of the undulations 14 protrudes in a direction away from the inner circumferential surface 8 of the annular member 2 (i.e., inward in radial direction D3) and is curved in an arc shape. The tops 15 of each of the undulations 14 abut against the top foil 4. The undulations 14 are spaced apart along the circumferential direction D2, giving the bump foil 6 a wavy shape. This bump foil 6 elastically supports the top foil 4.

[0034] The plurality of wave portions 14 include a first wave portion 14A ( 14 ) and a second wave portion 14B ( 14 ) adjacent to each other in the circumferential direction D2 . Figure 3 , the structures of the first wave portion 14A and the second wave portion 14B are described. Figure 3 FIG. 1 is a development view showing a portion of the inner peripheral surface 9 of the bump foil 6 according to the first embodiment. Figure 3 In the illustrated embodiment, the first wave portion 14A is located closer to the side of the second wave portion 14B in the circumferential direction D2. Furthermore, the plurality of wave portions 14 further include a third wave portion 14C (14) located on the opposite side of the first wave portion 14A across the second wave portion 14B in the circumferential direction D2 and adjacent to the second wave portion 14B.

[0035] In the first embodiment, as Figure 3 As shown, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C each extend continuously from one end 16 to the other end 18 of the bump foil 6 in the axial direction D1. The first wave portion 14A and the third wave portion 14C each extend linearly parallel to the axial direction D1. The second wave portion 14B extends linearly at an angle relative to the axial direction D1. In the first embodiment, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C each extend with a constant width (in a direction perpendicular to the respective extension directions D5A, D5B, and D5C).

[0036] In the first embodiment, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C have the same or the same degree of rigidity. Specifically, when the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C are cut from one end 16 to the other end 18 of the corrugated foil 6 and observed along a direction perpendicular to the respective extension directions D5A, D5B, and D5C, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C have the same cross-sectional shape. Figure 2 As shown, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C each have a semicircular arc shape. Furthermore, the extension direction D5A of the first wave portion 14A and the extension direction D5C of the third wave portion 14C are both the same direction as the axial direction D1. The extension direction D5B of the second wave portion 14B is inclined relative to the axial direction D1.

[0037] The first wave portion 14A and the second wave portion 14B extend along the axial direction D1 of the rotating shaft 102 so as to intersect with the respective extension directions D5A and D5B. Specifically, when the first wave portion 14A and the second wave portion 14B extend to one side in the axial direction D1 beyond the one end 16 of the bump foil 6 (see FIG. Figure 3 ), the first wave portion 14A and the second wave portion 14B intersect with each other.

[0038] In the first embodiment, as Figure 3 As illustrated, the distance in the circumferential direction D2 between the first point P1 of the first wave portion 14A, which is located on the one side most closely in the circumferential direction D2, and the second point P2 of the first wave portion 14A, which is located on the other side most closely in the circumferential direction D2, is set to X1, and the distance in the circumferential direction D2 between the third point P3 of the second wave portion 14B, which is located on the one side most closely in the circumferential direction D2, and the fourth point P4 of the second wave portion 14B, which is located on the other side most closely in the circumferential direction D2, is set to X2. 1.05X1<X2<1.5X1 is satisfied. In some embodiments, if the inclination of the extension direction D5B of the second wave portion 14B relative to the extension direction D5A of the first wave portion 14A is set to an inclination angle θ, then 1 degree<θ<11 degrees is satisfied.

[0039] (Function and Effect) The operation and effects of the foil bearing device 1A according to the first embodiment will be described. Figure 4A and Figure 4B Each of these is a diagram for explaining the operation and effects of the foil bearing device 1A according to the first embodiment. Figure 4A It is along Figure 3 Observation after sectioning along the A1-A1 line. Figure 4B It is along Figure 3 The A2-A2 line of the observation diagram. Figure 4A and Figure 4B In FIG, a part of the top foil 4 is also shown.

[0040] like Figure 4A As shown in the example, when the position in the axial direction D1 is the position where the line A1-A1 passes, the position where the top 15 of the first wave portion 14A contacts the top foil 4 is set as the first contact point 17A on one side, the position where the top 15 of the second wave portion 14B contacts the top foil 4 is set as the second contact point 17B on one side, and the position where the top 15 of the third wave portion 14C contacts the top foil 4 is set as the third contact point 17C on one side. Similarly, Figure 4BAs shown in the example, when the position in the axial direction D1 is the position where the A2-A2 line passes, the position where the top 15 of the first wave portion 14A abuts the top foil 4 is set as the first abutting point 19A on the other side, the position where the top 15 of the second wave portion 14B abuts the top foil 4 is set as the second abutting point 19B on the other side, and the position where the top 15 of the third wave portion 14C abuts the top foil 4 is set as the third abutting point 19C on the other side.

[0041] According to the first embodiment, Figure 3 As shown, the distance d in the circumferential direction D2 between the top 15 of the first wave portion 14A and the top 15 of the second wave portion 14B changes depending on the position in the axial direction D1. Therefore, the second contact point 19B on the other side is located inward in the radial direction D3 compared to the second contact point 17B on the one side. Therefore, the curvature of the top foil 4 from the first contact point 17A on the one side to the second contact point 17B on the one side (refer to Figure 4B The bending degrees of the top foil 4 from the first contact point 19A on the other side to the second contact point 19B on the other side are different from each other. In the first embodiment, when the air film presses the top foil 4, as shown in FIG. Figure 4B As shown, a gap can be formed between the portion where the first wave portion 14A of the top foil 4 abuts and the portion where the second wave portion 14B abuts. Figure 4A A new arc shape protrudes further outward in the radial direction D3. Specifically, by simply extending the first wave portion 14A and the second wave portion 14B along the axial direction D1 so that their respective extension directions D5A and D5B intersect with each other, the top foil 4 can be formed into multiple arc shapes (the top foil 4 is multi-arcified) during the rotation of the rotating shaft 102. This improves the damping effect of vibrations generated by the rotation of the rotating shaft 102. This can suppress degradation of assembly and manufacturability while improving the damping effect of vibrations generated by the rotation of the rotating shaft 102.

[0042] According to the first embodiment, as compared to a case where at least one of the first wave portion 14A and the second wave portion 14B extends discontinuously from one end 16 to the other end 18 of the bump foil 6 in the axial direction D1 , degradation of assemblability and manufacturability can be suppressed.

[0043] If X2 is less than 1.05X1, the top foil 4 may not have a multi-arc shape that is advantageous against surface undulations caused by manufacturing variations. On the other hand, if X2 exceeds 1.5X1, at least one of the first wave portion 14A and the second wave portion 14B may protrude excessively, deteriorating the floating characteristics of the rotating shaft 102. According to the first embodiment, the condition 1.05X1<X2<1.5X1 is satisfied, thereby enabling the top foil 4 to have an arc shape that is advantageous against surface undulations caused by manufacturing variations while suppressing degradation of the floating characteristics of the rotating shaft 102.

[0044] In the first embodiment, the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C have the same rigidity or a degree of rigidity to each other, but the present invention is not limited to this embodiment. Figure 5A It is a diagram schematically showing the structure of a first modified example of the bump foil 6 according to the first embodiment. Figure 5B It is a diagram schematically showing the structure of a second modified example of the bump foil 6 according to the first embodiment.

[0045] exist Figure 5A and Figure 5B In the illustrated embodiments, the first wave portion 14A and the second wave portion 14B have different rigidities. Specifically, when cut along a direction perpendicular to the respective extending directions D5A and D5B, the cross-sectional shapes of the first wave portion 14A and the second wave portion 14B are different from each other. Figure 5A In the illustrated embodiment, the first wave portion 14A and the third wave portion 14C are semicircular and have the same shape. The second contact point 19B of the second wave portion 14B extends along the circumferential direction D2, and the second wave portion 14B is substantially U-shaped. Figure 5B In the illustrated embodiment, the first wave portion 14A and the third wave portion 14C each have a semicircular arc shape and have the same shape. The second wave portion 14B also has a semicircular arc shape but is thicker than the first wave portion 14A. This type of bump foil 6 can be a structure in which a second bump foil portion 22, which does not have the first wave portion 14A but has the second wave portion 14B, is superimposed on a first bump foil 20 formed with the first wave portion 14A and the second wave portion 14B.

[0046] According to the configurations of the first and second modified examples, a new arc shape can be easily formed between the portion where the top 15 of the first corrugated portion 14A contacts the portion where the top 15 of the second corrugated portion 14B contacts. Furthermore, because the first corrugated portion 14A and the second corrugated portion 14B have different rigidities, the bump foil 6 can be manufactured more easily than when the first corrugated portion 14A and the second corrugated portion 14B are formed of different materials.

[0047] <Second embodiment> A foil bearing device 1B (1) according to a second embodiment of the present invention will be described. The foil bearing device 1B according to the second embodiment differs from the first embodiment in that the second wave portion 14B includes a side portion 24 and a side portion 26. In the second embodiment, components identical to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0048] (structure) Figure 61 is a development view showing a portion of the inner peripheral surface 9 of the bump foil 6 according to the second embodiment. Figure 6 As shown in the example, the second wave portion 14B includes a one side portion 24 and another side portion 26 .

[0049] The side portion 24 extends from one end 16 of the bump foil 6 to between the one end 16 and the other end 18 of the bump foil 6 along the axial direction D1. The other side portion 26 extends from the other end 18 of the bump foil 6 toward the side portion 24 along the axial direction D1. Figure 6 In the illustrated embodiment, the other side portion 26 forms a gap 27 with the one side portion 24 in the axial direction D1. Although not shown, in some embodiments, the other side portion 26 abuts against the one side portion 24 and the gap 27 is not formed.

[0050] In the second embodiment, as Figure 6 As shown, an imaginary line (hereinafter referred to as the second imaginary line L2) extending parallel to the axial direction D1 is set downstream of the second wave portion 14B in the rotation direction D4 of the rotating shaft 102. The distance X3 between the one side portion 24 and the second imaginary line L2 decreases as it moves toward the other side in the axial direction D1. The distance X4 between the other side portion 26 and the second imaginary line L2 decreases as it moves toward the one side in the axial direction D1.

[0051] exist Figure 6 In the illustrated embodiment, the gap 27 is located at the center of the bump foil 6 in the axial direction D1. The one end 16 of the bump foil 6 is defined as the position of 0% of the length of the bump foil 6 in the axial direction D1. Furthermore, the other end 18 of the bump foil 6, which increases as it moves from the one end 16 toward the other end 18 of the bump foil 6, is defined as the position of 100% of the length of the bump foil 6 in the axial direction D1. The gap 27 is located within a range of 40% to 60% of the length of the bump foil 6 in the axial direction D1.

[0052] exist Figure 6 In the illustrated embodiment, one side portion 24 and the other side portion 26 each overlap at least partially in the circumferential direction D2. The one side portion 24 and the other side portion 26 are line-symmetrical with respect to a centerline O2 passing through the center of the bump foil 6 in the axial direction D1. In other words, the second wave portion 14B has an "eight" shape. Although not shown, in some embodiments, a slit passing through the centerline O2 of the bump foil 6 may be formed in the bump foil 6. This structure facilitates the manufacture of the bump foil 6 including the second wave portion 14B.

[0053] (Function and Effect) The function and effect of the foil bearing device 1B according to the second embodiment will be described. Figure 3As illustrated, if the second wave portion 14B extends obliquely with respect to the axial direction D1, a force acting along one side in the axial direction D1 may be generated in the second wave portion 14B when the bump foil 6 is pressed by the top foil 4 and deforms. This generated force may cause the second wave portion 14B to protrude along the axial direction D1 (bulge out from the bump foil 6).

[0054] According to the second embodiment, the second wave portion 14B has an "eight" shape. Therefore, forces generated along the axial direction D1 on one side portion 24 and the other side portion 26 cancel each other out, thereby suppressing protrusion of the second wave portion 14B along the axial direction D1. Furthermore, the fluid is guided toward the area where the gap 27 (the "eight"-shaped Δ-shaped space) is formed in the axial direction D1, thereby increasing the gas pressure of the fluid. Furthermore, by increasing the gas pressure of the fluid, the attenuation performance can be improved. In particular, in the second embodiment, the gap 27 is located at the center of the corrugated foil 6 in the axial direction D1, so the fluid is guided toward the center, which can enhance the fluid pressure-increasing effect.

[0055] According to the second embodiment, compared with the case where the gap 27 is not formed, the bump foil 6 can be manufactured more easily.

[0056] Furthermore, the second embodiment is not limited to the first wave portion 14A, the second wave portion 14B, and the third wave portion 14C having the same or the same degree of rigidity. In a modified example of the second embodiment, the first wave portion 14A and the second wave portion 14B have different rigidities. Although not shown, in the modified example of the second embodiment, when cut along a direction orthogonal to the respective extension directions D5A and D5B, the cross-sectional shapes of the first wave portion 14A and the second wave portion 14B are different.

[0057] <Third embodiment> A foil bearing device 1C (1) according to a third embodiment of the present invention will be described. The foil bearing device 1C according to the third embodiment differs from the first embodiment in that the first wave portion 14A and the second wave portion 14B have different rigidities in that their respective extension directions D5A and D5B do not intersect with each other. In the third embodiment, the same reference numerals are used for the same components as those of the first embodiment, and detailed description thereof will be omitted.

[0058] (structure) Figure 7 This is a developed view showing a portion of the inner peripheral surface 9 of the bump foil 6 according to the third embodiment in a developed manner. Figure 8 : is a diagram schematically showing the structure of the bump foil 6 according to the third embodiment. In the third embodiment, the foil bearing device 1C (1) includes an annular member 2, a top foil 4, and a bump foil 6 having a plurality of wave portions 14. Figure 7 As shown in FIG, the extending directions D5A and D5B of the first wave portion 14A and the second wave portion 14B do not intersect with each other. Figure 7 In the illustrated embodiment, the first wave portion 14A and the second wave portion 14B each extend linearly in parallel with the axial direction D1 .

[0059] In the third embodiment, the first wave portion 14A and the second wave portion 14B have different rigidities. Specifically, when cut along a direction perpendicular to the respective extending directions D5A and D5B, the cross-sectional shapes of the first wave portion 14A and the second wave portion 14B are different from each other. Figure 8 In the illustrated embodiment, the first wave portion 14A has a semicircular arc shape. The second contact point 19B of the second wave portion 14B extends along the circumferential direction D2, and the second wave portion 14B has a substantially U-shape.

[0060] (Function and Effect) The functions and effects of the foil bearing device 1C according to the third embodiment will be described. According to the third embodiment, when the air film presses against the top foil 4, a new arc shape can be formed between the portion of the top foil 4 abutting the first wave portion 14A and the portion abutting the second wave portion 14B. In other words, simply by giving the first wave portion 14A and the second wave portion 14B different rigidities, the top foil 4 can be formed into multiple arc shapes (multi-arc top foil 4) as the rotating shaft 102 rotates. This improves the ability to damp vibrations generated by the rotation of the rotating shaft 102. This can prevent degradation in assembly and manufacturability while improving the ability to damp vibrations generated by the rotation of the rotating shaft 102.

[0061] According to the third embodiment, the bump foil 6 can be manufactured more easily than when the first wave portion 14A and the second wave portion 14B are formed of different materials. Figure 8 The embodiment shown has an arbitrary cross-sectional shape. Although not shown, the second wave portion 14B has a cross-sectional shape similar to that of the first wave portion 14A, but is thicker than the first wave portion 14A.

[0062] The contents described in each of the above embodiments can be understood, for example, as follows.

[0063] [1] The foil bearing devices 1A and 1B according to the present invention are foil bearing devices that rotatably support a rotating shaft 102 and include: The annular member 2 has an insertion hole 3 for the rotating shaft to be inserted through; a top foil 4 having an arcuate cross section, arranged between the inner peripheral surface 8 of the annular member and the outer peripheral surface 110 of the rotating shaft so as to surround the entire outer periphery of the rotating shaft; and The top foil 6 is arranged to surround the entire outer periphery of the top foil and is supported on the inner peripheral surface of the annular member. The corrugated foil includes a plurality of corrugated portions 14 protruding toward the top foil and at least a portion thereof abutting against the top foil. The plurality of wave portions include first wave portions 14A and 14B and a second wave portion adjacent to each other in the circumferential direction D2 of the top foil. When the inner peripheral surface 9 of the bump foil is expanded and viewed, the first and second bump portions extend along the axial direction D1 of the rotation shaft so that their extending directions intersect with each other.

[0064] According to the structure described in [1] above, the distance between the first wave portion and the second wave portion changes depending on the position in the axial direction of the rotating shaft. Therefore, when the air film between the rotating shaft and the top foil presses the top foil 4, a new arc shape can be formed between the portion of the top foil abutted by the first wave portion and the portion of the top foil abutted by the second wave portion. In other words, by simply extending the first wave portion and the second wave portion along the axial direction of the rotating shaft so that their respective extension directions intersect with each other, the top foil can be formed in multiple arc shapes during the rotation of the rotating shaft (the top foil is multi-arcified), thereby improving the attenuation effect of the vibration generated when the rotating shaft rotates. Therefore, it is possible to suppress the reduction in assembly and manufacturability and improve the attenuation effect of the vibration generated by the rotation of the rotating shaft.

[0065] [2] In some embodiments, in the structure described in [1] above, when the inner peripheral surface of the bump foil is unfolded and observed, the first wave portion and the second wave portion respectively extend continuously from one end 16 to the other end 18 of the bump foil in the axial direction.

[0066] According to the structure described in [2] above, it is possible to suppress a decrease in assemblability and manufacturability compared to a case where at least one of the first wave portion and the second wave portion does not extend continuously from one end to the other end of the corrugated foil in the axial direction.

[0067] [3] In some embodiments, in the structure described in [2] above, When the inner circumferential surface of the wave foil is unfolded and observed, the circumferential distance between the first point P1 of the first wave portion located on the one side most in the circumferential direction and the second point P2 of the first wave portion located on the other side most in the circumferential direction is set as X1, and the circumferential distance between the third point P3 of the second wave portion located on the one side most in the circumferential direction and the fourth point P4 located on the other side most in the circumferential direction of the second wave portion is set as X2. Then 1.05X1 is satisfied <X2<1.5X1。

[0068] If X2 is less than 1.05X1, the top foil may not have a multi-arc shape that is advantageous over the undulations of the surface caused by manufacturing variations. On the other hand, if X2 exceeds 1.5X1, the wave portion may protrude excessively, and the floating characteristics of the rotating shaft may deteriorate. According to the structure described in [3] above, the top foil can be made into a multi-arc shape that is advantageous over the undulations of the surface caused by manufacturing variations while suppressing the deterioration of the floating characteristics of the rotating shaft.

[0069] [4] In some embodiments, in the structure described in [1] above, When the inner circumferential surface of the bump foil is expanded and observed, at least one of the first wave portion and the second wave portion includes: a side portion 24 extending from one end of the corrugated foil in the axial direction to between the one end and the other end of the corrugated foil in the axial direction; and The other side portion 26 extends from the other end of the corrugated foil in the axial direction toward the one side portion. If an imaginary line L2 extending parallel to the axial direction is set on the downstream side of the second wave portion in the rotation direction D4 closer to the rotation axis, the distance X3 between the one side portion and the imaginary line decreases as it moves toward the other side in the axial direction. A distance X4 between the other side portion and the imaginary line decreases as it moves toward one side in the axial direction.

[0070] When the inner peripheral surface of the bump foil is unfolded and observed, if the first wave portion or the second wave portion extends obliquely relative to the axial direction of the rotating shaft, when the bump foil pressed by the top foil is deformed, a force acting in the axial direction is generated in the first wave portion or the second wave portion. In addition, the first wave portion or the second wave portion may protrude in the axial direction (spit out from the bump foil) due to the generated force. According to the structure described in [4] above, forces in the axial direction are generated on one side and the other side respectively, and the forces cancel each other out, so that the protrusion of the first wave portion or the second wave portion is suppressed. In addition, the fluid (air) flowing between the rotating shaft and the top foil is guided toward the center side in the axial direction, thereby increasing the gas pressure of the fluid.

[0071] [5] In some embodiments, in the structure described in [4] above, The other side portion extends from the other end of the bump foil toward the one side portion so as to form a gap 27 between the other side portion and the one side portion in the axial direction.

[0072] According to the structure described in [5] above, the bump foil can be manufactured more easily than when no gap is formed.

[0073] [6] In some embodiments, in the structure described in [4] or [5] above, The gap is located at the center of the corrugated foil in the axial direction.

[0074] According to the structure described in [6] above, the fluid (air) flowing between the rotating shaft and the top foil is guided toward the center of the corrugated foil in the axial direction. The pressurizing effect of the fluid by the second wave portion can be enhanced.

[0075] [7] In some embodiments, in the structure described in any one of [1] to [6] above, The first wave portion and the second wave portion have different rigidities from each other.

[0076] According to the structure described in [7] above, a new arc shape can be easily formed between the portion of the top foil abutted by the first wave portion and the portion of the top foil abutted by the second wave portion.

[0077] [8] In some embodiments, in the structure described in [7] above, The first wave portion and the second wave portion have different cross-sectional shapes.

[0078] According to the structure described in the above [8], the bump foil can be manufactured more easily than in the case where the first wave portion and the second wave portion are formed of materials different from each other.

[0079] [9] A foil bearing device 1C according to the present invention is a foil bearing device that rotatably supports a rotating shaft and includes: an annular member having an insertion hole for the rotating shaft to be inserted through; a top foil having an arcuate cross section, arranged between the inner peripheral surface of the annular member and the outer peripheral surface of the rotating shaft so as to surround the entire outer periphery of the rotating shaft; and a corrugated foil arranged to surround the entire outer periphery of the top foil and supported on the inner peripheral surface of the annular member; The corrugated foil includes a plurality of corrugated portions protruding toward the top foil and at least a portion of which abuts against the top foil. The plurality of wave portions include a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, The first wave portion and the second wave portion have different rigidities from each other.

[0080] According to the structure described in [9] above, when the air film presses the top foil, a new arc shape can be formed between the portion of the top foil abutted by the first wave portion and the portion of the top foil abutted by the second wave portion. In other words, by simply giving the first wave portion and the second wave portion different rigidities, the top foil can be formed into multiple arc shapes during the rotation of the rotating shaft (the top foil is multi-arcified), thereby improving the damping effect of vibration generated by the rotation of the rotating shaft. Therefore, it is possible to suppress the reduction of assembly and manufacturability and improve the damping effect of vibration generated by the rotation of the rotating shaft.

[0081]

[10] In some embodiments, in the structure described in [9] above, The first wave portion and the second wave portion have different cross-sectional shapes.

[0082] According to the structure described in

[10] above, the bump foil can be manufactured more easily than in the case where the first and second bump portions are formed of materials different from each other.

[0083] Explanation of symbols 1A-Foil bearing device (first embodiment), 1B-Foil bearing device (second embodiment), 1C-Foil bearing device (third embodiment), 2-Annular member, 3-Insert hole, 4-Top foil, 6-Corrugated foil, 8-Inner circumferential surface of annular member, 9-Inner circumferential surface of corrugated foil, 14-Corrugated portion, 14A-First corrugated portion, 14B-Second corrugated portion, 14C-Third corrugated portion, 16-One end of corrugated foil, 17A-First contact point, 17B-Second contact point, 17C-Third contact point, 18-Other end of corrugated foil, 19A-First contact point, 19B-Second contact point, 19C-Third contact point, 20 -1st corrugated foil portion, 22-2nd corrugated foil portion, 24-one side portion, 26-other side portion, 27-gap, 100-turbo compressor, 102-rotating shaft, 104-electric motor, 106-impeller, 106A-1st impeller, 106B-2nd impeller, 108-casing, 110-outer peripheral surface of rotating shaft, D1-axial direction, D2-circumferential direction, D3-radial direction, D4-rotational direction, L1-1st imaginary line, L2-2nd imaginary line, O1-center line of top foil, O2-center line of corrugated foil, P1-1st point, P2-2nd point, P3-3rd point, P4-4th point, d-distance.

Claims

1. A foil bearing device that rotatably supports a rotating shaft, comprising: an annular member having an insertion hole for the rotating shaft to be inserted through; a top foil having an arcuate cross section, arranged between the inner peripheral surface of the annular member and the outer peripheral surface of the rotating shaft so as to surround the entire outer periphery of the rotating shaft; and a corrugated foil arranged to surround the entire outer periphery of the top foil and supported on the inner peripheral surface of the annular member; The corrugated foil includes a plurality of corrugated portions protruding toward the top foil and at least a portion of which abuts against the top foil. The plurality of wave portions include a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, When the inner peripheral surface of the bump foil is expanded and viewed, the first and second bump portions extend along the axial direction of the rotation shaft so that their extending directions intersect with each other.

2. The foil bearing device according to claim 1, wherein When the inner peripheral surface of the bump foil is expanded and viewed, the first wave portion and the second wave portion each continuously extend from one end to the other end of the bump foil in the axial direction.

3. The foil bearing device according to claim 2, wherein: When the inner circumferential surface of the wave foil is unfolded and observed, if the circumferential distance between the first point of the first wave portion located on the one side most in the circumferential direction and the second point of the first wave portion located on the other side most in the circumferential direction is set as X1, and the circumferential distance between the third point of the second wave portion located on the one side most in the circumferential direction and the fourth point of the second wave portion located on the other side most in the circumferential direction is set as X2, Then 1.05X1<X2<1.5X1 is satisfied.

4. The foil bearing device according to claim 1, wherein When the inner circumferential surface of the bump foil is expanded and observed, at least one of the first wave portion and the second wave portion includes: a side portion extending from one end of the corrugated foil in the axial direction to between the one end and the other end of the corrugated foil in the axial direction; and another side portion, extending from the other end of the corrugated foil in the axial direction toward the one side portion, When a virtual line extending parallel to the axial direction is set on the downstream side of the second wave portion in the rotation direction of the rotation shaft, The distance between the one side portion and the imaginary line decreases as it moves toward the other side in the axial direction. The distance between the other side portion and the imaginary line decreases as it moves toward one side in the axial direction.

5. The foil bearing device according to claim 4, wherein: The other side portion extends from the other end of the bump foil toward the one side portion so as to form a gap therebetween with the one side portion in the axial direction.

6. The foil bearing device according to claim 4 or 5, wherein: The gap is located at the center of the corrugated foil in the axial direction.

7. The foil bearing device according to any one of claims 1 to 5, wherein: The first wave portion and the second wave portion have different rigidities from each other.

8. The foil bearing device according to claim 7, wherein: The first wave portion and the second wave portion have different cross-sectional shapes.

9. A foil bearing device for rotatably supporting a rotating shaft, comprising: an annular member having an insertion hole for the rotating shaft to be inserted through; a top foil having an arcuate cross section, arranged between the inner peripheral surface of the annular member and the outer peripheral surface of the rotating shaft so as to surround the entire outer periphery of the rotating shaft; and a corrugated foil arranged to surround the entire outer periphery of the top foil and supported on the inner peripheral surface of the annular member; The corrugated foil includes a plurality of corrugated portions protruding toward the top foil and at least a portion of which abuts against the top foil. The plurality of wave portions include a first wave portion and a second wave portion adjacent to each other in the circumferential direction of the top foil, The first wave portion and the second wave portion have different rigidities from each other.

10. The foil bearing device according to claim 9, wherein The first wave portion and the second wave portion have different cross-sectional shapes.

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