Foil bearing device

Abstract

A foil bearing device for rotatably supporting a rotating shaft, the foil bearing device comprising: an annular member having an insertion hole into which the rotating shaft is inserted; a top foil having an arcuate cross section and disposed around the entire outer periphery of the rotating shaft between the inner circumferential surface of the annular member and the outer circumferential surface of the rotating shaft; and a bump foil disposed around the entire outer periphery of the top foil and supported on the inner circumferential surface of the annular member, wherein the bump foil includes a plurality of bump parts that protrude toward the top foil and at least some of which abut the top foil, the plurality of bump parts include a first bump part and a second bump part that are adjacent to each other in the circumferential direction of the top foil, and when the inner circumferential surface of the bump foil is viewed in an exploded view, each of the first bump part and the second bump part extends along the axial direction of the rotating shaft such that the respective extending directions intersect with each other.

Description

Technical Field

[0004] , , , , , , , ,

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[0001] The present disclosure relates to a foil bearing device that rotatably supports a rotating shaft.

Background Art

[0002] A foil bearing includes a top foil that constitutes a bearing surface for a rotating shaft of a turbo blower or a turbo compressor, etc., and a bump foil that elastically supports the top foil. When the rotating shaft rotates, a fluid film (air film) is formed between the bearing surface of the top foil and the rotating shaft, and the rotating shaft is rotatably supported through this air film. Such a foil bearing is effective particularly for a rotating shaft that rotates at high speed because an appropriate air film is automatically formed according to the rotation speed of the rotating shaft.

[0003] The bearing surface of a foil bearing may be formed in a plurality of arc shapes in order to attenuate vibrations generated when the rotating shaft rotates. For example, Patent Document 1 discloses a foil bearing that surrounds a rotating shaft with three top foils distributed around the rotating shaft, and each of the three top foils has an arc shape. That is, Patent Document 1 discloses a foil bearing in which the bearing surface is formed in three arc shapes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technology described in Patent Document 1 requires multiple top foils and bump foils corresponding to each of the multiple top foils, which may reduce the ease of assembly of the foil bearing. Furthermore, the structure for the bump foils to elastically support the top foils (see the corrugated foil in Patent Document 1) becomes complex, which may reduce the ease of assembly and manufacture of the foil bearing.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide a foil bearing device that can improve the damping effect of vibrations generated by the rotation of a rotating shaft while suppressing a decrease in ease of assembly and manufacturability. [Means for solving the problem]

[0007] To achieve the above objective, the foil bearing device according to the present disclosure is a foil bearing device for rotatably supporting a rotating shaft, comprising: an annular member having an insertion hole through which the rotating shaft is inserted; a top foil with a circular arc cross-section arranged to surround the entire outer circumference of the rotating shaft between the inner circumferential surface of the annular member and the outer circumferential surface of the rotating shaft; and a bump foil arranged to surround the entire outer circumference of the top foil, the bump foil being supported by the inner circumferential surface of the annular member, wherein the bump foil includes a plurality of bump portions that protrude toward the top foil and at least a portion of which abuts the top foil, the plurality of bump portions having first bump portions and second bump portions adjacent to each other in the circumferential direction of the top foil, and when the inner circumferential surface of the bump foil is unfolded and viewed, each of the first bump portions and the second bump portions extends along the axial direction of the rotating shaft such that their respective extending directions intersect each other.

[0008] To achieve the above objective, the foil bearing device according to the present disclosure is a foil bearing device for rotatably supporting a rotating shaft, comprising: an annular member having an insertion hole through which the rotating shaft is inserted; a top foil with a circular arc cross-section arranged to surround the entire outer circumference of the rotating shaft between the inner circumferential surface of the annular member and the outer circumferential surface of the rotating shaft; and a bump foil arranged to surround the entire outer circumference of the top foil, the bump foil being supported by the inner circumferential surface of the annular member, wherein the bump foil includes a plurality of bump portions that protrude toward the top foil and at least a portion of which abuts the top foil, the plurality of bump portions having first bump portions and second bump portions adjacent to each other in the circumferential direction of the top foil, and the first bump portions and second bump portions having different rigidities from each other. [Effects of the Invention]

[0009] The foil bearing device of this disclosure can improve the damping effect of vibrations generated by the rotation of the rotating shaft while suppressing a decrease in assembly and manufacturability. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram schematically shows the configuration of a turbo compressor equipped with a foil bearing device according to several embodiments. [Figure 2] This is a schematic cross-sectional view showing the configuration of a foil bearing device according to the first embodiment. [Figure 3] This is an unfolded view of a portion of the inner surface of the bump foil according to the first embodiment. [Figure 4A] This is a diagram illustrating the operation and effects of the foil bearing device according to the first embodiment. [Figure 4B] This is a diagram illustrating the operation and effects of the foil bearing device according to the first embodiment. [Figure 5A] This figure schematically shows the configuration of a first modified example of the bump foil according to the first embodiment. [Figure 5B]This figure schematically shows the configuration of a second modified example of the bump foil according to the first embodiment. [Figure 6] This is an unfolded view of a portion of the inner surface of the bump foil according to the second embodiment. [Figure 7] This is an unfolded view of a portion of the inner surface of the bump foil according to the third embodiment. [Figure 8] This diagram schematically shows the configuration of the bump foil according to the third embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, a foil bearing device according to an embodiment of the present disclosure will be described with reference to the drawings. Such an embodiment represents one aspect of the present disclosure and is not limiting, and can be modified at will within the scope of the technical idea of ​​the present disclosure.

[0012] Figure 1 is a schematic diagram showing the configuration of a turbocompressor 100 equipped with a foil bearing device 1 according to several embodiments. As illustrated in Figure 1, the turbocompressor 100 includes a rotating shaft 102, an electric motor 104 that rotates the rotating shaft 102, an impeller 106 that compresses fluid by rotating integrally with the rotating shaft 102, a housing 108 that houses the electric motor 104 and the impeller 106, and the foil bearing device 1.

[0013] In the configuration illustrated in Figure 1, 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 electric motor 104 from the second impeller 106B in the axial direction D1 of the rotating shaft 102 (hereinafter referred to as "axial direction D1"). In such a turbo compressor 100, the fluid compressed by the first impeller 106A is further compressed by the second impeller 106B to generate a high-pressure fluid.

[0014] In the present disclosure, the direction from the second impeller 106B to the first impeller 106A in the axial direction D1 is taken as one side of the axial direction D1, and the direction from the first impeller 106A to the second impeller 106B in the axial direction D1 is taken as the other side of the axial direction D1.

[0015] The foil bearing device 1 rotatably supports the rotating shaft 102. The foil bearing device 1 supports the rotating shaft 102 in a state of contact with the rotating shaft 102 until the rotational speed of the rotating shaft 102 reaches the floating rotational speed that causes the rotating shaft 102 to float. When the rotational speed of the rotating shaft 102 reaches the floating rotational speed, the foil bearing device 1 supports the rotating shaft 102 in a non-contact state via a fluid film (air film) formed between the bearing surface of the top foil 4 and the rotating shaft 102. In the form illustrated in FIG. 1, the turbo compressor 100 includes a pair of foil bearing devices 1, 1 arranged so as to sandwich the electric motor 104 from both sides in the axial direction D1. That is, the rotating shaft 102 is supported in a two-bearing manner by the pair of foil bearing devices 1, 1.

[0016] In the present disclosure, although the case where the foil bearing device 1 is applied to the turbo compressor 100 is exemplified, 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 disclosure is applied to a rotating device including a rotating shaft 102, particularly a rotating device including a rotating shaft that can rotate at high speed. For example, the rotating device includes a turbocharger and a turbo blower. Further, the turbo compressor 100 is not limited to the configuration illustrated in FIG. 1. For example, the turbo compressor 100 may have a configuration that does not include the second impeller 106B.

[0017] <First Embodiment> (Configuration) The configuration of the foil bearing device 1A (1) according to the first embodiment will be described. FIG. 2 is a cross-sectional view schematically showing the configuration of the foil bearing device 1A according to the first embodiment, and is viewed by cutting the foil bearing device 1A in a direction orthogonal to the axial direction D1. As illustrated in FIG. 2, the foil bearing device 1A includes an annular member 2, a top foil 4, and a bump foil 6.

[0018] The annular member 2 has an insertion hole 3 through which the rotation 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 rotation shaft 102. In some embodiments, the housing of the turbo compressor 100 described above includes the annular member 2. In this case, the annular member 2 is a part of the housing 108.

[0019] The top foil 4 is disposed to surround the entire outer periphery of the rotation shaft 102 between the inner peripheral surface 8 of the annular member 2 and the outer peripheral surface 110 of the rotation shaft 102. As illustrated in FIG. 2, the top foil 4 has an arc shape in a cross-sectional view taken in a direction perpendicular to the axial direction D1 of the top foil 4.

[0020] The top foil 4 is formed, for example, by bending a flexible metal plate made of stainless steel into a cylindrical shape. In the form illustrated in FIG. 2, one end portion 10 in the circumferential direction D2 (hereinafter referred to as "circumferential direction D2") of the top foil 4 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 disposed inside the annular member 2 in a state where one end portion 10 in the circumferential direction D2 is held by the annular member 2. The other end portion 12 of the top foil 4 in the circumferential direction D2 is slightly separated from the one end portion 10 in the circumferential direction D2.

[0021] In the present disclosure, the circumferential direction D2 is a circumferential direction centered on the center line O1 of the top foil 4. In the plane of FIG. 2, the direction from the other end portion 12 to the one end portion 10 of the top foil 4 (the counterclockwise direction) is taken as one side of the circumferential direction D2, and the direction from the one end portion 10 to the other end portion 12 of the top foil 4 (the clockwise direction) is taken as the other side of the circumferential direction D2. The radial direction D3 is a direction perpendicular to the center line O1, the direction approaching the center line O1 is taken as the inner side of the radial direction D3, and the direction away from the center line O1 is taken as the outer side of the radial direction D3. <​In the first embodiment, as illustrated in Figure 2, the angular position of the imaginary line (hereinafter referred to as the first imaginary line L1) passing through the center line O1 of the top foil 4 and one end 10 is set to 0 degrees. This angular position increases as the top foil 4 rotates in the other direction D2 (counterclockwise) with the center line O1 as the rotation center, and the angular position when the first imaginary line L1 completes one rotation is defined as 360 degrees. The other end 12 of the top foil 4 is located at an angular position of 350 degrees or more and less than 360 degrees. The first imaginary line L1 extends from the center line O1 in the opposite direction to the direction of gravity (upward in the vertical direction).

[0023] The bump foil 6 is arranged to surround the entire outer circumference of the top foil 4. This bump foil 6 is supported by the inner circumferential surface 8 of the annular member 2. The bump foil 6 is formed, for example, by curving a flexible metal sheet material made of stainless steel into a cylindrical shape. In the embodiment illustrated in Figure 2, the bump foil 6 extends over the entire circumferential direction D2 and is in contact with the inner circumferential surface 8 of the annular member 2. The bump foil 6 is configured so that one end 10 of the top foil 4 passes through it. Although not shown, in some embodiments, each of the multiple bump foils 6 is separate from each other and arranged continuously along the circumferential direction D2.

[0024] The bump foil 6 includes a plurality of bump portions 14 that project toward the top foil 4 and at least a portion of which abuts the top foil 4. Each of the plurality of bump portions 14 projects in a direction away from the inner circumferential surface 8 of the annular member 2 (i.e., inward in the radial direction D3) and is curved in an arc shape. The top 15 of each of the plurality of bump portions 14 abuts the top foil 4. Each of the plurality of bump portions 14 is spaced apart from one another along the circumferential direction D2, and the bump foil 6 has a wave shape. Such a bump foil 6 is designed to elastically support the top foil 4.

[0025] The multiple bump portions 14 include first bump portions 14A(14) and second bump portions 14B(14) that are adjacent to each other in the circumferential direction D2. The configuration of the first bump portions 14A and the second bump portions 14B will be described with reference to Figure 3. Figure 3 is an unfolded view of a part of the inner circumferential surface 9 of the bump foil 6 according to the first embodiment. In the embodiment illustrated in Figure 3, the first bump portion 14A is located on one side of the circumferential direction D2 than the second bump portion 14B. Furthermore, the multiple bump portions 14 also include a third bump portion 14C(14) that is located on the opposite side of the second bump portion 14B from the first bump portion 14A in the circumferential direction D2, and is adjacent to the second bump portion 14B.

[0026] In the first embodiment, as illustrated in Figure 3, the first bump portion 14A, the second bump portion 14B, and the third bump 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 bump portion 14A and the third bump portion 14C each extend linearly parallel to the axial direction D1. The second bump portion 14B extends linearly at an inclination with respect to the axial direction D1. In the first embodiment, the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C each extend such that the width (the width in the direction perpendicular to their respective extending directions D5A, D5B, and D5C) is constant.

[0027] In the first embodiment, the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C each have the same or similar rigidity. Specifically, when the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C are cut from one end 16 to the other end 18 of the bump foil 6 in a direction perpendicular to their respective extending directions D5A, D5B, and D5C, they have the same cross-sectional shape. As illustrated in Figure 2, the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C each have a semi-circular shape. The extending direction D5A of the first bump portion 14A and the extending direction D5C of the third bump portion 14C are in the same direction as the axial direction D1. The extending direction D5B of the second bump portion 14B is inclined with respect to the axial direction D1.

[0028] Each of the first bump portion 14A and the second bump portion 14B extends along the axial direction D1 of the rotation shaft 102 such that their respective extending directions D5A and D5B intersect each other. Specifically, when each of the first bump portion 14A and the second bump portion 14B is extended to one side in the axial direction D1 beyond one end 16 of the bump foil 6 (see the dotted line portion in FIG. 3), the first bump portion 14A and the second bump portion 14B intersect each other.

[0029] In the first embodiment, as illustrated in FIG. 3, the distance in the circumferential direction D2 between a first point P1 located on the outermost one side in the circumferential direction D2 of the first bump portion 14A and a second point P2 located on the outermost other side in the circumferential direction D2 of the first bump portion 14A is defined as X1, and the distance in the circumferential direction D2 between a third point P3 located on the outermost one side in the circumferential direction D2 of the second bump portion 14B and a fourth point P4 located on the outermost other side in the circumferential direction D2 of the second bump portion 14B is defined as X2. 1.05X1 < X2 < 1.5X1 is satisfied. In some embodiments, when the inclination of the extending direction D5B of the second bump portion 14B with respect to the extending direction D5A of the first bump portion 14A is defined as the inclination angle θ, 1 degree < θ < 11 degrees is satisfied.

[0030] (Function and Effect) The function and effect of the foil bearing device 1A according to the first embodiment will be described. FIGS. 4A and 4B are diagrams for explaining the function and effect of the foil bearing device 1A according to the first embodiment. FIG. 4A is a view taken by cutting along the line A1 - A1 in FIG. 3. FIG. 4B is a view taken by cutting along the line A2 - A2 in FIG. 3. A part of the top foil 4 is also shown in each of FIGS. 4A and 4B.

[0031] As illustrated in Figure 4A, when the position in the axial direction D1 is the position through which the A1-A1 line passes, the position where the top 15 of the first bump portion 14A contacts the top foil 4 is the first contact point 17A on one side, the position where the top 15 of the second bump portion 14B contacts the top foil 4 is the second contact point 17B on one side, and the position where the top 15 of the third bump portion 14C contacts the top foil 4 is the third contact point 17C on one side. Similarly, as illustrated in Figure 4B, if the position in the axial direction D1 is the position through which the A2-A2 line passes, the position where the top 15 of the first bump portion 14A contacts the top foil 4 is the first contact point 19A on the other side, the position where the top 15 of the second bump portion 14B contacts the top foil 4 is the second contact point 19B on the other side, and the position where the top 15 of the third bump portion 14C contacts the top foil 4 is the third contact point 19C on the other side.

[0032] According to the first embodiment, as shown in Figure 3, the circumferential distance d in the circumferential direction D2 between the top 15 of the first bump portion 14A and the top 15 of the second bump 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. Thus, the curvature of the top foil 4 from the first contact point 17A on one side to the second contact point 17B on the other side (see the dotted line in Figure 4B), and the curvature 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 against the top foil 4, as shown in Figure 4B, a new arc shape can be formed between the portion of the top foil 4 that contacts the first bump portion 14A and the portion that contacts the second bump portion 14B, which protrudes outward in the radial direction D3 compared to Figure 4A. In other words, by simply extending the first bump section 14A and the second bump section 14B along the axial direction D1 such that their respective extension directions D5A and D5B intersect each other, the top foil 4 is formed in multiple arc shapes during the rotation of the rotating shaft 102 (making the top foil 4 multi-arc), thereby increasing the vibration damping effect when the rotating shaft 102 rotates. Therefore, it is possible to improve the vibration damping effect generated by the rotation of the rotating shaft 102 while suppressing a decrease in assembly and manufacturability.

[0033] According to the first embodiment, it is possible to suppress a decrease in the assemblability and manufacturability as compared with the case where at least one of the first bump portion 14A and the second bump portion 14B extends discontinuously from one end 16 to the other end 18 of the bump foil 6 in the axial direction D1.

[0034] When X2 is less than 1.05X1, the top foil 4 may not have an advantageous multi-arc shape with respect to the undulations of the surface caused by manufacturing variations. On the other hand, when X2 exceeds 1.5X1, at least one of the first bump portion 14A and the second bump portion 14B may protrude too much, and there is a risk that the floating characteristics of the rotating shaft 102 deteriorate. According to the first embodiment, since 1.05X1 < X2 < 1.5X1 is satisfied, it is possible to suppress the deterioration of the floating characteristics of the rotating shaft 102 while making the top foil 4 have an advantageous multi-arc shape with respect to the undulations of the surface caused by manufacturing variations.

[0035] In the first embodiment, each of the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C has the same or comparable rigidity to each other, but the present disclosure is not limited to this form. FIG. 5A is a diagram schematically showing the configuration of a first modification of the bump foil 6 according to the first embodiment. FIG. 5B is a diagram schematically showing the configuration of a second modification of the bump foil 6 according to the first embodiment.

[0036] In the embodiments illustrated in Figures 5A and 5B, the first bump portion 14A and the second bump portion 14B have different rigidities. Specifically, when the first bump portion 14A and the second bump portion 14B are cut in a direction perpendicular to their respective extending directions D5A and D5B, their cross-sectional shapes are different. In the embodiment illustrated in Figure 5A, the first bump portion 14A and the third bump portion 14C each have a semi-circular shape and are identical in shape. The second bump portion 14B has a second contact point 19B that widens along the circumferential direction D2, and is roughly U-shaped. In the embodiment illustrated in Figure 5B, the first bump portion 14A and the third bump portion 14C each have a semi-circular shape and are identical in shape. The second bump portion 14B also has a semi-circular shape, but is thicker than the first bump portion 14A. Such a bump foil 6 may be configured by superimposing a second bump foil portion 22, which has the first bump portion 14A but not the second bump portion, onto a first bump foil portion 20, which has the first bump portion 14A and the second bump portion 14B formed on it.

[0037] According to the configurations of the first and second modified examples, a new arc shape can be easily formed between the portion of the top 15 of the first bump portion 14A of the top foil 4 that abuts against the portion of the top 15 of the second bump portion 14B that abuts against the top 15 of the top foil 4. Furthermore, because the first bump portion 14A and the second bump portion 14B have different rigidities, the bump foil 6 can be manufactured more easily compared to the case where the first bump portion 14A and the second bump portion 14B are each made of different materials.

[0038] <Second Embodiment> A foil bearing device 1B(1) according to a second embodiment of this disclosure will now be described. The foil bearing device 1B according to the second embodiment differs from the first embodiment in that the second bump portion 14B includes one side portion 24 and the other side portion 26. In the second embodiment, components that are the same as those of the first embodiment are denoted by the same reference numerals, and their detailed description is omitted.

[0039] (composition) Figure 6 is an unfolded view of a portion of the inner circumferential surface 9 of the bump foil 6 according to the second embodiment. In the second embodiment, as illustrated in Figure 6, the second bump portion 14B includes one side portion 24 and the other side portion 26.

[0040] One side portion 24 extends along the axial direction D1 from one end 16 of the bump foil 6 to the space between the one end 16 and the other end 18 of the bump foil 6. The other side portion 26 extends along the axial direction D1 from the other end 18 of the bump foil 6 toward the one side portion 24. In the embodiment illustrated in Figure 6, a gap 27 is formed between the other side portion 26 and the one side portion 24 in the axial direction D1. Although not shown, in some embodiments, the other side portion 26 is in contact with the one side portion 24, and no gap 27 is formed.

[0041] In the second embodiment, as shown in Figure 6, a virtual line (hereinafter referred to as the second virtual line L2) is set parallel to the axial direction D1 on the downstream side of the rotation direction D4 of the rotation axis 102 from the second bump portion 14B. On one side portion 24, the distance X3 from the second virtual line L2 decreases as it moves toward the other side of the axial direction D1. On the other side portion 26, the distance X4 from the second virtual line L2 decreases as it moves toward the other side of the axial direction D1.

[0042] In the embodiment illustrated in Figure 6, the gap 27 is located in the center of the bump foil 6 in the axial direction D1. One end 16 of the bump foil 6 is defined as the 0% position relative to the length of the bump foil 6 in the axial direction D1. Furthermore, the gap increases from the one end 16 of the bump foil 6 toward the other end 18, with the other end 18 being defined as the 100% position relative to the length of the bump foil 6 in the axial direction D1. The gap 27 is located within the range of 40% to 60% relative to the length of the bump foil 6 in the axial direction D1.

[0043] In the embodiment illustrated in Figure 6, each of the one side portion 24 and the other side portion 26 overlaps with each other in at least a portion in the circumferential direction D2. Each of the one side portion 24 and the other side portion 26 is symmetrical with respect to a center line O2 that passes through the center of the axial direction D1 of the bump foil 6. In other words, the second bump portion 14B has a V-shape. Although not shown, in some embodiments, the bump foil 6 may have a slit that passes through the center line O2 of the bump foil 6. Such a configuration makes it possible to manufacture the bump foil 6 including the second bump portion 14B easier.

[0044] (Effects / Actions) The operation and effects of the foil bearing device 1B according to the second embodiment will now be explained. As illustrated in Figure 3, if the second bump portion 14B extends at an inclination with respect to the axial direction D1, a force may be generated on the second bump portion 14B acting along one side of the axial direction D1 when the bump foil 6 is deformed by being pressed by the top foil 4. Then, the second bump portion 14B may protrude along the axial direction D1 (extend from the bump foil 6) due to this generated force.

[0045] According to the second embodiment, since the second bump portion 14B has a V-shape, forces are generated along the axial direction D1 on each of the one side portion 24 and the other side portion 26, and these forces cancel each other out, so that the protrusion of the second bump portion 14B along the axial direction D1 is suppressed. In addition, since the fluid is guided toward the area where the gap 27 (the triangular space of the V-shape) is formed in the axial direction D1, the fluid pressure can be increased. And by increasing the fluid pressure, the damping performance can be improved. In particular, in the second embodiment, since the gap 27 is located in the center of the bump foil 6 in the axial direction D1, the fluid is guided toward the center, and the fluid pressure-boosting effect can be improved.

[0046] According to the second embodiment, the manufacturing of the bump foil 6 can be facilitated compared to the case where the gap 27 is not formed.

[0047] Furthermore, the second embodiment is not limited to the first bump portion 14A, the second bump portion 14B, and the third bump portion 14C having the same or similar rigidity as each other. In a modified example of the second embodiment, the first bump portion 14A and the second bump portion 14B have different rigidities. Although not shown, in a modified example of the second embodiment, the cross-sectional shapes of the first bump portion 14A and the second bump portion 14B are different when cut in a direction perpendicular to their respective extending directions D5A and D5B.

[0048] <Third Embodiment> A foil bearing device 1C(1) according to a third embodiment of this disclosure will now be described. The foil bearing device 1C according to the third embodiment differs from the first embodiment in that the first bump portion 14A and the second bump portion 14B each have their respective extending directions D5A and D5B not intersecting each other and have different rigidities. In the third embodiment, components that are the same as those of the first embodiment are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0049] (composition) Figure 7 is an unfolded view of a portion of the inner circumferential surface 9 of the bump foil 6 according to the third embodiment. Figure 8 is a schematic diagram showing the configuration 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 bump portions 14. As shown in Figure 7, the extension directions D5A and D5B of the first bump portion 14A and the second bump portion 14B do not intersect each other. In the embodiment illustrated in Figure 7, the first bump portion 14A and the second bump portion 14B each extend linearly parallel to the axial direction D1.

[0050] In the third embodiment, the first bump portion 14A and the second bump portion 14B have different rigidities. Specifically, when the first bump portion 14A and the second bump portion 14B are cut in a direction perpendicular to their respective extending directions D5A and D5B, their cross-sectional shapes are different. In the embodiment illustrated in Figure 8, the first bump portion 14A has a semi-circular arc shape. The second bump portion 14B has a second contact point 19B that widens along the circumferential direction D2, and is roughly U-shaped.

[0051] (Effects / Actions) The operation and effects of the foil bearing device 1C according to the third embodiment will now 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 that the first bump portion 14A contacts and the portion of the top foil 4 that the second bump portion 14B contacts. In other words, by simply making the first bump portion 14A and the second bump portion 14B have different rigidities, the top foil 4 can be made to form multiple arc shapes (the top foil 4 can be made into a multi-arc shape) during the rotation of the rotating shaft 102, thereby increasing the damping effect of vibrations generated when the rotating shaft 102 rotates. Therefore, it is possible to improve the damping effect of vibrations generated by the rotation of the rotating shaft 102 while suppressing a decrease in assembly and manufacturability.

[0052] According to the third embodiment, the bump foil 6 can be manufactured more easily compared to the case where the first bump portion 14A and the second bump portion 14B are each formed of different materials. Note that the first bump portion 14A and the second bump portion 14B are not limited to the forms illustrated in Figure 8, but can have any cross-sectional shape. Although not shown, the second bump portion 14B has a semi-circular cross-sectional shape similar to the first bump portion 14A, but is thicker than the first bump portion 14A.

[0053] The contents described in each of the above embodiments can be understood, for example, as follows:

[0054] [1] The foil bearing devices (1A, 1B) relating to this disclosure are A foil bearing device that rotatably supports a rotating shaft (102), An annular member (2) having an insertion hole (3) through which the rotating shaft is inserted, Between the inner circumferential surface (8) of the annular member and the outer circumferential surface (110) of the rotating shaft, a top foil (4) with a circular arc cross-section is arranged to surround the entire outer circumference of the rotating shaft, A bump foil is arranged to surround the entire outer circumference of the top foil, and comprises a bump foil (6) supported on the inner circumferential surface of the annular member, The bump foil includes a plurality of bump portions (14) that protrude toward the top foil and at least a portion of which abut the top foil, The plurality of bump portions have first bump portions (14A, 14B) and second bump portions that are adjacent to each other in the circumferential direction (D2) of the top foil. When the inner circumferential surface (9) of the bump foil is unfolded and viewed, the first bump portion and the second bump portion each extend along the axial direction (D1) of the rotation axis such that their respective extending directions intersect each other.

[0055] According to the configuration described in [1] above, the distance between the first bump portion and the second bump portion changes depending on the axial position of the rotating shaft. Therefore, when the air film between the rotating shaft and the top foil presses against the top foil 4, a new arc shape can be formed between the portion of the top foil that contacts the first bump portion and the portion that contacts the second bump portion. In other words, by simply extending the first bump portion and the second bump portion along the axial direction of the rotating shaft so that their respective extension directions intersect with each other, the top foil can be made to form multiple arc shapes during the rotation of the rotating shaft (making the top foil multi-arc), thereby increasing the vibration damping effect when the rotating shaft rotates. Thus, it is possible to improve the vibration damping effect generated by the rotation of the rotating shaft while suppressing a decrease in assembly and manufacturability.

[0056] [2] In some embodiments, in the configuration described in [1] above, When the inner peripheral surface of the bump foil is developed and viewed, each of the first bump portion and the second bump portion extends continuously from one end (16) to the other end (18) of the bump foil in the axial direction.

[0057] According to the configuration described in [2] above, it is possible to suppress a decrease in the assemblability and manufacturability as compared with the case where at least one of the first bump portion and the second bump portion extends discontinuously from one end to the other end of the bump foil in the axial direction.

[0058] [3] In some embodiments, in the configuration described in [2] above, When the inner peripheral surface of the bump foil is developed and viewed, the circumferential distance between a first point (P1) located on one most side in the circumferential direction of the first bump portion and a second point (P2) located on the other most side in the circumferential direction of the first bump portion is taken as X1, and the circumferential distance between a third point (P3) located on one most side in the circumferential direction of the second bump portion and a fourth point (P4) located on the other most side in the circumferential direction of the second bump portion is taken as X2, then 1.05X1 < X2 < 1.5X1 is satisfied.

[0059] If X2 is less than 1.05X1, the top foil may not have an advantageous multi-arc shape with respect to the undulations of the surface caused by manufacturing variations. On the other hand, if X2 exceeds 1.5X1, the bump portion may protrude too much, and there is a risk that the floating characteristics of the rotating shaft will deteriorate. According to the configuration described in [3] above, it is possible to make the top foil have an advantageous multi-arc shape with respect to the undulations of the surface caused by manufacturing variations while suppressing the deterioration of the floating characteristics of the rotating shaft.

[0060] [4] In some embodiments, in the configuration described in [1] above, When the inner peripheral surface of the bump foil is developed and viewed, at least one of the first bump portion and the second bump portion is One side portion (24) extending from one end of the bump foil in the axial direction to the space between the one end and the other end of the bump foil in the axial direction, The bump foil in the axial direction includes the other side portion (26) extending from the other end toward the one side portion, If we set a virtual line (L2) that extends parallel to the axial direction downstream of the second bump portion in the rotation direction (D4) of the rotation axis, As the one side approaches the other side in the axial direction, the distance (X3) from the imaginary line decreases. The other side portion has a decreasing distance (X4) from the imaginary line as it moves toward one side in the axial direction.

[0061] When the inner surface of the bump foil is unfolded and viewed, if the first bump portion or the second bump portion extends at an inclination with respect to the axial direction of the rotation axis, a force acting along the axial direction is generated on the first bump portion or the second bump portion when the bump foil is deformed by being pressed by the top foil. As a result, the first bump portion or the second bump portion may protrude along the axial direction (extend from the bump foil) due to this generated force. According to the configuration described in [4] above, forces along the axial direction are generated on each of the one side and the other side, and these forces cancel each other out, so the protrusion of the first bump portion or the second bump portion is suppressed. In addition, the fluid (air) flowing between the rotation axis and the top foil is guided toward the center in the axial direction, and the pressure of the fluid can be increased.

[0062] [5] In some embodiments, in the configuration described in [4] above, The other side portion extends from the other end of the bump foil toward the one side portion such that a gap (27) is formed between it and the one side portion in the axial direction.

[0063] According to the configuration described in [5] above, the manufacturing of the bump foil can be facilitated compared to the case where no gap is formed.

[0064] [6] In some embodiments, in the configuration described in [4] or [5] above, The gap is located in the center of the bump foil in the axial direction.

[0065] According to the configuration described in [6] above, the fluid (air) flowing between the rotating shaft and the top foil is guided toward the center of the bump foil in the axial direction. Therefore, The fluid pressure-boosting effect of the second bump section can be improved.

[0066] [7] In some embodiments, in the configuration described in any one of [1] to [6] above, The first bump portion and the second bump portion have different rigidities.

[0067] According to the configuration described in [7] above, a new arc shape can be easily formed between the portion of the top foil that contacts the first bump and the portion that contacts the second bump.

[0068] [8] In some embodiments, in the configuration described in [7] above, The first bump portion and the second bump portion have different cross-sectional shapes.

[0069] According to the configuration described in [8] above, the bump foil can be manufactured more easily compared to the case where the first bump portion and the second bump portion are each formed of different materials.

[0070] [9] The foil bearing device (1C) relating to this disclosure is A foil bearing device that rotatably supports a rotating shaft, An annular member having an insertion hole through which the rotating shaft is inserted, Between the inner circumferential surface of the annular member and the outer circumferential surface of the rotating shaft, a top foil with a circular arc cross-section is arranged to surround the entire outer circumference of the rotating shaft, A bump foil is arranged to surround the entire outer circumference of the top foil, and the bump foil is supported on the inner circumferential surface of the annular member, The bump foil includes a plurality of bump portions that protrude toward the top foil and at least a portion of which abuts against the top foil. The plurality of bump portions have first bump portions and second bump portions that are adjacent to each other in the circumferential direction of the top foil. The first bump portion and the second bump portion have different rigidities.

[0071] According to the configuration described in [9] above, when the air film presses against the top foil, a new arc shape can be formed between the portion of the top foil that contacts the first bump portion and the portion that contacts the second bump portion. In other words, by simply making the first bump portion and the second bump portion have different rigidities, the top foil can be made to form multiple arc shapes (multi-arc top foil) during the rotation of the rotating shaft, thereby increasing the damping effect of vibrations generated when the rotating shaft rotates. Thus, it is possible to improve the damping effect of vibrations generated by the rotation of the rotating shaft while suppressing a decrease in assembly and manufacturability.

[0072]

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

[0073] According to the configuration described in

[10] above, the bump foil can be manufactured more easily compared to the case where the first bump portion and the second bump portion are each formed of different materials. [Explanation of Symbols]

[0074] 1A Foil bearing device (first embodiment) 1B Foil bearing device (second embodiment) 1C Foil Bearing Device (Third Embodiment) 2. Annular member 3. Through hole 4 Top foil 6 Bump Foil 8. Inner circumferential surface of the annular member 9. Inner surface of the bump foil 14. Bump section 14A First bump section 14B Second bump section 14C Third Bump Section 16 One end of the bump foil 17A 1st contact point 17B 2nd contact point 17C 3rd contact point 18 The other end of the bump foil 19A 1st contact point 19B 2nd contact point 19C 3rd contact point 20. First bump foil section 22. Second bump foil section 24 One side 26 Other side 27 gaps 100 Turbo Compressor 102 Rotation axis 104 Electric Motor 106 Impeller 106A First Impeller 106B No. 2 Impeller 108 Housing 110 Outer surface of the rotating shaft D1 Axial direction D2 Circumferential direction D3 radial direction D4 Rotation direction L1 First Virtual Line L2 Second Virtual Line O1 Top foil centerline O2 bump foil centerline P1 First Point P2 2nd point P3 3rd point P4 4th point d distance

Claims

1. A foil bearing device that rotatably supports a rotating shaft, An annular member having an insertion hole through which the rotating shaft is inserted, Between the inner circumferential surface of the annular member and the outer circumferential surface of the rotating shaft, a top foil with a circular arc cross-section is arranged to surround the entire outer circumference of the rotating shaft, A bump foil is arranged to surround the entire outer circumference of the top foil, and the bump foil is supported on the inner circumferential surface of the annular member, The bump foil includes a plurality of bump portions that protrude toward the top foil and at least a portion of which abuts against the top foil. The plurality of bump portions have first bump portions and second bump portions that are adjacent to each other in the circumferential direction of the top foil. When the inner circumferential surface of the bump foil is unfolded and viewed, the first bump portion and the second bump portion each extend along the axial direction of the rotation axis such that their respective extending directions intersect each other. Foil bearing device.

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

3. When the inner circumferential surface of the bump foil is unfolded and viewed, let X1 be the circumferential distance between the first point located on the one side of the first bump portion in the circumferential direction and the second point located on the other side of the first bump portion in the circumferential direction, and let X2 be the circumferential distance between the third point located on the one side of the second bump portion in the circumferential direction and the fourth point located on the other side of the second bump portion in the circumferential direction. Satisfying 1.05X1 < X2 < 1.5X1, The foil bearing device according to claim 2.

4. When the inner circumferential surface of the bump foil is unfolded and viewed, at least one of the first bump portion and the second bump portion is One side portion extending from one end of the bump foil in the axial direction to the space between the one end and the other end of the bump foil in the axial direction, The bump foil in the axial direction includes the other side portion extending from the other end toward the one side portion, When a virtual line is set parallel to the axial direction on the downstream side of the rotational direction of the rotational shaft from the second bump portion, The distance between the imaginary line and the one side decreases as it moves toward the other side in the axial direction. The other side portion is such that the distance from the imaginary line decreases as it moves toward one side in the axial direction. The foil bearing device according to claim 1.

5. The other side portion extends from the other end of the bump foil toward the one side portion such that a gap is formed between it and the one side portion in the axial direction. The foil bearing device according to claim 4.

6. The gap is located in the center of the bump foil in the axial direction. The foil bearing device according to claim 5.

7. The first bump portion and the second bump portion have different rigidities. A foil bearing device according to any one of claims 1 to 6.

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

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