Gas Bearing Device

Abstract

This gas bearing device comprises: a bump foil that is disposed on a stationary holding member facing a rotary member, and has a corrugated shape with a plurality of continuous peaks; and a top foil disposed on the bump foil. The bump foil includes a first bump foil on the rotary member side, and a second bump foil on the stationary holding member side that are disposed to face each other. The first bump foil and the second bump foil engage with each other so that sloping surfaces of the peaks thereof overlap each other, and gaps are formed respectively between the tops of the peaks and between the bottoms of the first bump foil and second bump foil overlapping each other.

Description

[Technical field]

[0001] The present disclosure relates to a gas bearing device for supporting a high-speed rotating body. [Background technology]

[0002] A conventional gas bearing device for supporting a high-speed rotating body has been known in which a gas bearing portion is provided between a rotating member and a stationary support member facing the rotating member, and this gas bearing portion is composed of a corrugated bump foil arranged on the stationary support member and a top foil arranged on the bump foil.

[0003] For example, Patent Document 1 discloses a hydrodynamic gas bearing that has sufficient rigidity to return an eccentric rotating shaft to its original position when a fluctuating load or an impact load is applied due to the rotating shaft becoming eccentric during rotation, as well as damping that contributes to high-speed stability.

[0004] Patent document 1 also shows a configuration in which the bump foils are arranged opposite each other, with a lower bump foil on the stationary member side and an upper bump foil on the rotating member side, and the lower bump foil and upper bump foil are pre-engaged so that the inclined surfaces of each bump foil overlap. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-148461 A Summary of the Invention [Problem to be solved by the invention]

[0006] Gas bearing devices are prone to vibrational instability because they support a high-speed rotating body, and in order to increase vibration stability, it is necessary to improve the vibration energy absorption capacity at high speed rotation, and there is a demand for improved vibration damping capacity.

[0007] A gas film exists between the top foil and the rotating member (rotating shaft side), and vibration damping by this gas film is conceivable, but it cannot be expected to have a large effect. In addition, friction damping due to contact friction between the bump foil and the top foil, and contact friction between the bump foil and the stationary holding member (housing side) is considered as another vibration damping factor. Therefore, since this friction damping is thought to contribute to the stabilization of vibration, it is expected that the stabilization of vibration will be achieved by increasing the friction damping.

[0008] Because the bump foil is corrugated, it expands and contracts in the left-right direction (circumferential direction in the case of a journal bearing) by compressing in the up-down direction when a load is applied in the up-down direction from the rotating member (radial direction in the case of a journal bearing, axial direction in the case of a thrust bearing), which causes friction due to slippage between the bump foil and the stationary holding member, resulting in frictional damping. However, because the sliding direction in which frictional damping occurs in response to the up-down load from the rotating member is the left-right direction (circumferential direction), its contribution to vibration damping due to the up-down load is small.

[0009] The aforementioned Patent Document 1 shows a double-structure bump foil in which the lower and upper bump foils are engaged so that the inclined surfaces of the corrugated peaks of the lower and upper bump foils overlap, as shown in Figure 3 of Patent Document 1, and the bottom of the corrugations of the upper bump foil overlaps in a state of contact with the bottom of the corrugations of the lower pump foil.

[0010] For this reason, in Patent Document 1, even if the inclined surfaces of the peaks of the upper bump foil and the lower bump foil overlap, the inclined surfaces cannot slide against each other due to the load applied in the vertical direction, and no friction damping effect can be expected at the overlapping contact surfaces.

[0011] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a gas bearing device that can increase the friction damping of a bump foil arranged on a stationary retaining member, thereby improving the vibration damping capacity and suppressing unstable vibrations of a rotating member. [Means for solving the problem]

[0012] In order to achieve the above-mentioned objective, the gas bearing device of the present disclosure comprises a corrugated bump foil arranged on a stationary holding member facing a rotating member and having a plurality of continuous ridges, and a top foil arranged on the bump foil, the bump foils including a first bump foil on the rotating member side and a second bump foil on the stationary holding member side which are arranged opposite each other, the first bump foil and the second bump foil engage with each other so that the inclined surfaces of the ridges overlap, and gaps are formed between the tops and bottoms of the overlapping first bump foil and second bump foil. Effect of the Invention

[0013] According to the gas bearing device of the present disclosure, gaps are formed between the tops and bottoms of the overlapping first bump foil and second bump foil, so that the first bump foil can slide in the direction of the load acting from the rotating member side to the stationary holding member side.

[0014] Therefore, a friction surface is formed on the contact surface between the inclined surfaces of the peaks, and friction damping is easily achieved. And, since the friction damping direction is aligned with the load acting direction, damping of vibration in the load direction is effectively achieved. This ensures excellent damping of vibration caused by fluctuating loads or impact loads applied from the rotating member side to the stationary member side, and suppresses unstable vibration of the rotating member. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating an overall configuration of a gas bearing device according to an embodiment of the present disclosure applied to a turbo compressor; [Diagram 2] 2 is a schematic cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 3 is an enlarged view of a portion of the bump foil of FIG. 2. [Figure 4] FIG. 4 is an enlarged view corresponding to FIG. 3 and showing another embodiment in which the bump foil is different from the first embodiment. [Diagram 5] FIG. 4 is a conceptual diagram of a surface treatment layer formed in the contact portion in FIG. 3 according to still another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a gas bearing device according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, and is not limited to this disclosure. Any modification can be made within the scope of the technical concept of the present disclosure.

[0017] <One embodiment> An embodiment of the present disclosure will be described with reference to Figures 1 to 3. Figure 1 is an overall schematic diagram of a gas bearing device 1 according to one embodiment applied to a turbo compressor 3. The turbo compressor 3 is configured such that impellers 9 are attached to the respective tips of an output shaft 7 protruding from the front and rear of a drive motor 5, and compresses sucked-in fluid. The front and rear output shafts 7 of the drive motor 5 are each supported by journal bearings 11.

[0018] The gas bearing device 1 of the present disclosure is applied to this journal bearing 11. As shown in Fig. 2, the gas bearing device 1 includes a rotating shaft (rotating member) 13 which is the output shaft 7 of a drive motor 5, and a cylindrical sleeve (stationary holding member) 15 which faces the rotating shaft 13 in the radial direction. A gas bearing portion 17 is provided between the rotating shaft 13 and the sleeve 15, and this gas bearing portion 17 is composed of a top foil 19 and a bump foil 21.

[0019] The top foil 19 is a cylindrical member that is a single plate-like member that faces the rotating shaft 13 and is elastically supported on the bump foil 21 by the bump foil 21, and further forms a gas film K between the top foil 19 and the rotating shaft 13 when the rotating shaft 13 rotates. One edge of the top foil 19 is bent outward and engaged with the sleeve 15 for circumferential positioning.

[0020] The bump foil 21 is disposed on the inner peripheral surface of the sleeve 15, and is formed in a corrugated shape having continuous peaks 23, and has a predetermined elasticity. As shown in Figures 2 and 3, the tops 25 and bottoms 29 of the continuous peaks 23 constituting the corrugated shape of the bump foil 21 are arranged side by side in the circumferential direction of the rotating shaft 13, and when the top foil 19 receives pressure from the gas film K in the radial direction of the rotating shaft 13, the peaks 23 elastically deform to reduce the height of the peaks 23 to support the top foil 19. Similarly to the top foil 19, one end edge of the bump foil 21 is bent outward and engaged with the sleeve 15, for circumferential positioning.

[0021] 3 is an enlarged schematic diagram of a portion of the bump foil 21 in FIG. 2, and the sleeve 15 and the rotating shaft 13 are circumferentially shaped but are illustrated as being flat for the sake of convenience.

[0022] In addition, the bump foil 21 has a double structure and is arranged opposite each other, with a first bump foil 21a on the rotating shaft 13 side (upper side in Figure 3) and a second bump foil 21b on the sleeve 15 side (lower side in Figure 3).

[0023] Furthermore, the first bump foil 21a and the second bump foil 21b are pre-engaged so that the inclined surfaces 27a of the continuous first bump ridge portions 23a that form the wave shape of the first bump foil 21a and the inclined surfaces 27b of the continuous second bump ridge portions 23b that form the wave shape of the second bump foil 21b overlap each other.

[0024] In the following description, the reference numerals for components related to the first bump foil 21a are marked with "a," and the reference numerals for components related to the second bump foil 21b are marked with "b."

[0025] A gap S1 is formed between the top 25a of the first bump mountain portion 23a and the top 25b of the second bump mountain portion 23b, which overlap each other, and a gap S2 is formed between the bottom 29a of the first bump mountain portion 23a and the bottom 29b of the second bump mountain portion 23b.

[0026] When the first bump foil 21a and the second bump foil 21b are formed from the same material, the plate thickness of the second bump foil 21b is formed to be thicker than that of the first bump foil 21a, and when the plate thicknesses are the same, the second bump foil 21b is formed from a material having higher rigidity than the first bump foil 21a.

[0027] The following two points can be mentioned as the action and effect of making the second bump foil 21b higher in rigidity than the first bump foil 21a. That is, by making the first bump foil 21a lower in rigidity (softer), the first bump foil 21a is more easily pressed in the circumferential direction, and therefore slippage at the contact surface between the first bump foil 21a and the second bump foil 21b is more easily controlled. Conversely, if the second bump foil 21b has lower rigidity (softer), slippage may occur at the contact surface between the second bump foil 21b and the sleeve 15, causing wear problems, but such problems can be suppressed.

[0028] The details of the overlapping state between the first bump foil 21a and the second bump foil 21b are shown in FIG. 3. The first bump foil 21a has a first bump one-side inclined surface 271a formed on one side of a first peak portion 231a which is one of a plurality of continuous first bump peak portions 23a forming a waveform, and a first bump other-side inclined surface 272a formed on the other side of the first peak portion 231a. Further, the second bump foil 21b has a second bump one-side inclined surface 271b formed on one side of a second peak portion 231b which is one of a plurality of continuous second bump peak portions 23b forming a waveform, and a second bump other-side inclined surface 272b formed on the other side of the second peak portion 231b.

[0029] And the back surface of the first bump one-side inclined surface 271a is in contact with the front surface of the second bump one-side inclined surface 271b, and the back surface of the first bump other-side inclined surface 272a is in contact with the front surface of the second bump other-side inclined surface 272b.

[0030] Also, the top 25a of the first bump peak portion 23a has an arc shape (radius R1), the top 25b of the second bump peak portion 23b also has an arc shape (radius R2), and the radius R1 of the top 25a of the first bump peak portion 23a and the radius R2 of the top 25b of the second bump peak portion 23b have a relationship where the top 25a of the first bump peak portion 23a is smaller than the top 25b of the second bump peak portion 23b (R1 < R2).

[0031] The bottom 29a of the first bump peak portion 23a also has an arc shape (radius R3), and the bottom 29a of the first bump peak portion 23a has a relationship where it is smaller than the top 25a of the first bump peak portion 23a (R3 < R1). Also, the bottom 29b of the second bump peak portion 23b is formed in a flat shape.

[0032] Note that the shapes of these tops 25a, 25b and bottoms 29a, 29b are examples, and as long as the inclined surfaces 27a of the first bump peak portion 23a and the inclined surfaces 27b of the second bump peak portion 23b overlap and friction attenuation occurs with respect to vibrations due to the vertical load F (refer to the arrow in FIG. 3) on the inclined surfaces 27a, 27b, any shape is acceptable.

[0033] In addition, the direction of action of friction force G against the vertical load F at the contact portion of overlapping inclined surfaces 27a, 27b (see arrow in FIG. 3) is preferably a direction intersecting the direction perpendicular to the vertical direction in which the load acts, and the closer the direction is to the vertical direction in which the load acts, the greater the friction damping effect against vertical vibrations.

[0034] According to the above embodiment, the back surface of the inclined surface 27a of the multiple consecutive first bump ridge portions 23a that form the wave shape of the first bump foil 21a and the front surface of the inclined surface 27b of the multiple consecutive second bump ridge portions 23b that form the wave shape of the second bump foil 21b overlap and engage with each other, causing the respective inclined surfaces 27a, 27b to come into contact with each other and form a friction surface.

[0035] Furthermore, gaps S1, S2 are formed between the top 25a of the first bump crest 23a and the top 25b of the second bump crest 23b, and between the bottom 29a of the first bump crest 23a and the bottom 29b of the second bump crest 23b, respectively, so that the first bump foil 21a can slide along the load direction in response to vibrations caused by a load acting in the direction from the rotating shaft 13 to the sleeve 15.

[0036] Therefore, friction damping due to Coulomb friction is easily obtained on the friction surface formed by contacting the overlapping inclined surfaces 27a, 27b. Furthermore, since the friction damping direction acts along the load direction, damping against vibration caused by the load acting in the direction from the rotating shaft 13 to the sleeve 15 can be effectively obtained. This ensures excellent damping against vibration caused by the fluctuating load or impact load applied from the rotating shaft 13 to the sleeve 15, and makes it possible to suppress unstable vibration of the rotating shaft 13.

[0037] Furthermore, according to one embodiment, the back surface of the first bump one-side inclined surface 271a formed on one side of the first mountain portion 231a, which is one of the multiple continuous first bump mountain portions 23a, comes into contact with the surface of the second bump one-side inclined surface 271b formed on one side of the second mountain portion 231b, which is one of the multiple continuous second bump mountain portions 23b, and further, the back surface of the first bump other-side inclined surface 272a formed on the other side of the first mountain portion 231a, which is one of the multiple continuous first bump mountain portions 23a, comes into contact with the surface of the second bump other-side inclined surface 272b formed on the other side of the second mountain portion 231b, which is one of the multiple continuous second bump mountain portions 23b.

[0038] In other words, one peak of each of the multiple consecutive second bump peaks 23b that form the wave shape of the second bump foil 21b overlaps one peak of each of the multiple consecutive first bump peaks 23a that form the wave shape of the first bump foil 21a, thereby improving the vibration damping effect due to the load acting in the direction from the rotating shaft 13 to the sleeve 15 and increasing the rigidity of the bump foil 21 as a whole.

[0039] <Other embodiments> Another embodiment will be described with reference to Fig. 4. The gas bearing device 1 according to the other embodiment differs from the first embodiment in that a first bump foil 51a and a second bump foil 51b that constitute a bump foil 51. In the other embodiment, the same components as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0040] As shown in FIG. 4, the first bump foil 51a has a first bump one-side inclined surface 571a formed on one side of a third peak 531 which is one of a plurality of consecutive first bump peaks 53a forming the wave shape, and a first bump other-side inclined surface 572a formed on the other side of the third peak 531. Further, the second bump foil 51b has a second bump one-side inclined surface 571b formed on one side of a fourth peak 532 which is the second bump peak 53b located on the most one side of a consecutive peak 530 (two consecutive second bump peaks 53b in FIG. 4) which is part of a plurality of consecutive second bump peaks 53b forming the wave shape, and a second bump other-side inclined surface 572b formed on the other side of a fifth peak 533 which is the second bump peak 53b located on the most other side of the consecutive peak 530.

[0041] The back surface of the first bump one-side inclined surface 571a and the front surface of the second bump one-side inclined surface 571b are in contact, and the back surface of the first bump other-side inclined surface 572a and the front surface of the second bump other-side inclined surface 572b are in contact, so that the first bump foil 51a and the second bump foil 51b overlap and are pre-engaged.

[0042] Also, as in one embodiment, a gap S1 is formed between the top 55a of the first bump mountain portion 53a and the top 55b of the second bump mountain portion 53b, and a gap S2 is formed between the bottom 59a of the first bump mountain portion 53a and the bottom 59b of the second bump mountain portion 53b.

[0043] In Figure 4, an example is shown in which the number of consecutive second bump ridge portions 53b of the consecutive ridge portion 530 is two ridge portions, but this is not limited to this and the number can be set arbitrarily based on the overall damping characteristics, rigidity, etc. of the bump foil 51.

[0044] According to another embodiment, a third peak 531, which is one of the multiple consecutive first bump peaks 53a that make up the wave shape of the first bump foil 51a, overlaps over a continuous peak 530, which is one of the multiple consecutive second bump peaks 53b that make up the wave shape of the second bump foil 51b.Therefore, the rigidity and frictional damping force of the entire bump foil can be adjusted by the number of peaks of the second bump peaks 53b that the third peak 531 straddles, thereby improving the freedom in designing these rigidity and frictional damping force.

[0045] <Further Other Embodiments> A further embodiment will be described with reference to Fig. 5. This embodiment is different from the embodiment shown in Fig. 3 and the other embodiment shown in Fig. 4 in that the contact portion is further surface-treated. In this embodiment, the same components as those in the embodiment and the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0046] Although FIG. 5 shows the surface treatment layer formed on the contact portion in the embodiment of FIG. 3, the surface treatment layer is similar in the contact portion of the other embodiment of FIG.

[0047] 5, in the overlapping inclined surfaces 27a, 27b of the first bump mountain portion 23a and the second bump mountain portion 23b, a hard coating film 61 is formed on either the back surface of the inclined surface 27a of the first bump mountain portion 23a or the front surface of the inclined surface 27b of the second bump mountain portion 23b, or on both. As the hard coating film 61, for example, a DLC coating film (abbreviation of diamond-like carbon, amorphous carbon coating film) or a CNx coating film (carbon nitride coating film) is suitable.

[0048] In place of the hard coating film 61, a molybdenum disulfide shot treatment layer 63 may be formed.

[0049] In this way, at each of the inclined surfaces 27a, 27b where the first bump crest 23a and the second bump crest 23b overlap, the wear resistance of the contact area is improved by the hard coating film formed on the contact surface side of one or both of the inclined surfaces, or by the molybdenum disulfide shot treatment layer, and this prevents the first bump crest 23a and the second bump crest 23b from sticking to each other at the contact area, preventing slippage and preventing the friction damping effect from being obtained.

[0050] Furthermore, in addition to the formation of the hard coating film 61 or the molybdenum disulfide shot treatment layer 63 on each of the aforementioned inclined surfaces 27a, 27b, a hard coating film is also formed on the contact surface between the sleeve 15 and the bottom 29b of the second bump crest 23b, either on the back surface of the bottom 29b of the second bump crest 23b or on the front surface of the sleeve 15, or on both. As the hard coating film 61, for example, a DLC coating film (abbreviation for diamond-like carbon, amorphous carbon coating film) or a CNx coating film (carbon nitride coating film) is suitable.

[0051] Also, instead of the hard coating film, a molybdenum disulfide shot treatment layer may be formed.

[0052] In this way, the hard coating film 61 formed on one or both contact surfaces between the sleeve 15 and the bottom 29b of the second bump crest 23b, or the molybdenum disulfide shot treatment layer 63, improves the wear resistance at the contact area and prevents the sleeve 15 and the bottom 29b of the second bump crest 23b from sticking to each other at the contact area and becoming unable to slide left and right, making it easier for the bottom 29b of the second bump crest 23b to slide left and right.

[0053] Because the bottom 29b of the second bump crest 23b becomes more slidable in the left-right direction, slippage is more likely to occur at the contact areas between the inclined surfaces 27a, 27b of the first bump crest 23a and the second bump crest 23b, making it easier to obtain the friction damping effect at the inclined surfaces 27a, 27b.

[0054] In the above embodiment, a radial bearing that supports the rotating shaft 13 in the radial direction has been described, but the same effects can be obtained with a thrust bearing that supports the rotating shaft 13 in the axial direction.

[0055] The contents described in each of the above embodiments can be understood, for example, as follows.

[0056] [1] A gas bearing device (1) according to the present disclosure comprises a corrugated bump foil (21) having a plurality of continuous ridges (23) disposed on a stationary holding member (15) facing a rotating member (13), and a top foil (19) disposed on the bump foil, the bump foil including a first bump foil (21a) on the rotating member side and a second bump foil (21b) on the stationary holding member side which are arranged opposite each other, the first bump foil and the second bump foil engage with each other such that the inclined surfaces (27a, 27b) of the ridges (23a, 23b) overlap, and gaps (S1, S2) are formed between the tops (25a, 25b) and bottoms (29a, 29b) of the ridges of the overlapping first bump foil and second bump foil, respectively.

[0057] According to the configuration described in [1] above, the first bump foil (21a) and the second bump foil (21b) engage with each other so that the inclined surfaces (27a, 27b) of the respective peaks (23a, 23b) overlap, and gaps (S1, S2) are formed between the peaks (25a, 25b) and between the bottoms (29a, 29b) of the peaks of the overlapping first bump foil and second bump foil, respectively. Therefore, in response to vibrations due to a load acting in the direction from the rotating member (13) to the stationary holding member (15), the first bump foil (21a) can slide along the load direction.

[0058] Therefore, friction damping due to Coulomb friction is easily obtained on the friction surface formed by contact between the overlapping inclined surfaces. And, since the friction damping direction acts along the load direction, damping of vibration caused by the load acting in the direction from the rotating member to the stationary holding member is effectively obtained. This ensures excellent damping of vibration caused by the fluctuating load or impact load applied from the rotating member to the stationary holding member, and suppresses unstable vibration of the rotating member.

[0059] [2] In some embodiments, in the configuration described in [1] above, the first bump foil (21a) includes a first bump one-side inclined surface (271a) formed on one side of a first peak portion (231a) that is one of a plurality of continuous first bump peak portions (23a) that form the wave shape, and a first bump other-side inclined surface (272a) formed on the other side of the first peak portion, and the second bump foil (21b) includes a first bump one-side inclined surface (272a) formed on one side of a first peak portion (231a) that is one of a plurality of continuous first bump peak portions (23a) that form the wave shape. The bump includes a second bump one-side inclined surface (271b) formed on one side of a second peak portion (231b), which is one of the peak portions (23b), and a second bump other-side inclined surface (272b) formed on the other side of the second peak portion, and is configured so that the back surface of the first bump one-side inclined surface (271a) is in contact with the front surface of the second bump one-side inclined surface (271b) and the back surface of the first bump other-side inclined surface (272a) is in contact with the front surface of the second bump other-side inclined surface (272b).

[0060] According to the configuration described in [2] above, each of the plurality of consecutive second bump ridges (23b) that form the wave shape of the second bump foil (21b) is overlapped by one of the plurality of consecutive first bump ridges (23a) that form the wave shape of the first bump foil (21a), thereby increasing the rigidity of the bump foil (21) as a whole.

[0061] [3] In some embodiments, in the configuration described in [1] above, the first bump foil (51a) includes a first bump one-side inclined surface (571a) formed on one side of a third peak portion (531) that is one of a plurality of continuous first bump peak portions (53a) that constitute the wave shape, and a first bump other-side inclined surface (572a) formed on the other side of the third peak portion (531), and the second bump foil (51b) includes a first bump one-side inclined surface (572a) formed on the other side of the third peak portion (531), which is one of a plurality of continuous second bump peak portions (53b) that constitute the wave shape. The bump includes a second bump one-side inclined surface (571b) formed on one side of the fourth peak (532), which is the bump peak (53b), and a second bump other-side inclined surface (572b) formed on the other side of the fifth peak (533), which is the second bump peak (53b) located on the other side furthest of the continuous peak (530), and is configured such that the back surface of the first bump one-side inclined surface (571a) is in contact with the front surface of the second bump one-side inclined surface (571b) and the back surface of the first bump other-side inclined surface (572a) is in contact with the front surface of the second bump other-side inclined surface (572b).

[0062] According to the configuration described in [3] above, one of the continuous first bump ridges (53a) constituting the wave shape of the first bump foil (51a) overlaps with a continuous ridge (530), which is part of the continuous second bump ridges (53b) constituting the wave shape of the second bump foil (51b), so that the rigidity and frictional damping force of the entire bump foil (51) can be adjusted by the number of ridges that are spanned, thereby improving the freedom in designing the rigidity and frictional damping force.

[0063] [4] In some embodiments, in the configuration described in [2] or [3] above, on each of the overlapping inclined surfaces (271a, 272a, 271b, 272b, 571a, 572a, 571b, 572b) of the first bump crest (23a, 53a) and the second bump crest (23b, 53b), a hard coating film (61) is formed on either the back surface of the inclined surface of the first bump crest or the front surface of the inclined surface of the second bump crest, or on both.

[0064] According to the configuration described in [4] above, the hard coating film (61) formed on the contact surface side of one or both of the overlapping inclined surfaces of the first bump crest (23a, 53a) and the second bump crest (23b, 53b) improves the wear resistance at the contact area and prevents the first bump crest and the second bump crest from sticking to each other at the contact area, preventing slippage and preventing the friction damping effect from being obtained.

[0065] [5] In some embodiments, in the configuration described in [2] or [3] above, on each of the overlapping inclined surfaces (271a, 272a, 271b, 272b, 571a, 572a, 571b, 572b) of the first bump crest (23a, 53a) and the second bump crest (23b, 53b), a molybdenum disulfide shot treatment layer (63) is formed on either the back surface of the inclined surface of the first bump crest or the front surface of the inclined surface of the second bump crest, or on both.

[0066] According to the configuration described in [5] above, the molybdenum disulfide shot treatment layer (63) formed on the contact surface side of one or both of the overlapping inclined surfaces of the first bump crest (23a, 53a) and the second bump crest (23b, 53b) improves the wear resistance at the contact area and prevents the first bump crest and the second bump crest from sticking to each other at the contact area, preventing slippage and preventing the friction damping effect from being obtained.

[0067] [6] In some embodiments, in the configuration described in [4] or [5] above, a hard coating film (61) is further formed on either the back surface of the bottom of the second bump crest (23b, 53b) or the front surface of the stationary retaining member at the contact surface between the stationary retaining member (15) and the bottom (29b, 59b) of the second bump crest (23b, 53b), or on both.

[0068] According to the configuration described in [6] above, the hard coating film (61) formed on one or both of the contact surfaces between the stationary retaining member (15) and the bottom (29b, 59b) of the second bump crest (23b, 53b) makes it easier for the second bump crest to slide in the left-right direction without sticking to the stationary member, making it easier for slippage to occur at the contact area between the inclined surfaces of the first and second bump crests, and further improving the friction damping effect on the inclined surfaces.

[0069] [7] In some embodiments, in the configuration described in [4] or [5] above, a molybdenum disulfide shot treatment layer (63) is further formed on either the back surface of the bottom of the second bump crest (23b, 53b) or the front surface of the stationary retaining member at the contact surface between the stationary retaining member (15) and the bottom (29b, 59b) of the second bump crest (23b, 53b), or on both.

[0070] According to the configuration described in [7] above, the lubricating action of the molybdenum disulfide shot treatment layer (63) formed on one or both contact surfaces between the stationary retaining member (15) and the bottom (29b, 59b) of the second bump crest (23b, 53b) makes it easier for the second bump foil to slide in the left-right direction without adhering to the stationary member, making it easier for slippage to occur at the contact area between the inclined surfaces of the first bump crest and the second bump crest, and making it easier to obtain the friction damping effect on the inclined surfaces.

[0071] [8] In some embodiments, in the configurations described in [1] to [7] above, the stationary retaining member (15) is a stationary retaining member of a journal bearing (11) arranged radially opposite the rotating member (13).

[0072] According to the configuration described in [8] above, the operational effects of each of the configurations [1] to [7] above can be obtained in the journal bearing (11). [Explanation of symbols]

[0073] 1 Gas bearing device 3. Turbo Compressor 11 Journal bearings 13 Rotating shaft (rotating member) 15 Sleeve (static holding member) 19 Top Foil 21, 51 Bump Foil 21a, 51a 1st Bump Foil 21b, 51b 2nd bump foil 23, 53 Yamabe 23a, 53a First bump 23b, 53b 2nd bump mountain 231a First mountain section 231b 2nd mountain section 25, 25a, 25b, 55a, 55b Top of mountain 29, 29a, 29b, 59a, 59b Bottom of mountain 27a, 27b Sloping surface of mountain 271a, 571a First bump one side inclined surface 272a, 572a First bump other side inclined surface 271b, 571b Second bump one side inclined surface 272b, 572b Second bump other side inclined surface 29a, 29b Bottom of the mountain 530 Continuous mountain area 531 3rd Mountain 532 4th Mountain 533 5th Mountain 61 Hard Coating Film 63 Molybdenum disulfide shot treatment layer F load K Gas film G friction force S1, S2 gap

Claims

1. a bump foil having a corrugated shape and a plurality of continuous peaks disposed on a stationary holding member facing the rotating member; a top foil disposed on the bump foil; The bump foils include a first bump foil on the rotating member side and a second bump foil on the stationary holding member side, the first bump foil and the second bump foil being disposed opposite each other, the first bump foil and the second bump foil are engaged with each other such that the inclined surfaces of the peaks of the first bump foil and the inclined surfaces of the second bump foil overlap each other; Gaps are formed between the tops and bottoms of the peaks of the first and second bump foils that overlap each other. Gas bearing device.

2. the first bump foil includes a first bump one-side inclined surface formed on one side of a first peak portion which is one of a plurality of continuous first bump peak portions constituting the wave shape, and a first bump other-side inclined surface formed on the other side of the first peak portion, the second bump foil includes a second bump one-side inclined surface formed on one side of a second peak portion that is one of a plurality of continuous second bump peak portions that form the wave shape, and a second bump other-side inclined surface formed on the other side of the second peak portion, a back surface of the first bump one side inclined surface and a front surface of the second bump one side inclined surface are in contact with each other; a back surface of the first bump other side inclined surface and a front surface of the second bump other side inclined surface are configured to be in contact with each other; 2. The gas bearing device according to claim 1.

3. the first bump foil includes a first bump one-side inclined surface formed on one side of a third peak portion, which is one of a plurality of continuous first bump peak portions constituting the wave shape, and a first bump other-side inclined surface formed on the other side of the third peak portion, the second bump foil includes a second bump one-side inclined surface formed on one side of a fourth peak portion which is the second bump peak portion located on the one side of a continuous peak portion which is a part of a plurality of continuous second bump peak portions which form the wave shape, and a second bump other-side inclined surface formed on the other side of a fifth peak portion which is the second bump peak portion located on the other side of the continuous peak portion, a back surface of the first bump one side inclined surface and a front surface of the second bump one side inclined surface are in contact with each other; a back surface of the first bump other side inclined surface and a front surface of the second bump other side inclined surface are configured to be in contact with each other; 2. The gas bearing device according to claim 1.

4. a hard coating film is formed on either a back surface of the inclined surface of the first bump crest or a front surface of the inclined surface of the second bump crest, or on both of the back surface and the front surface of the inclined surface of the second bump crest, at each of the inclined surfaces where the first bump crest and the second bump crest overlap each other; 4. A gas bearing device according to claim 2 or 3.

5. a molybdenum disulfide shot layer is formed on either or both of a back surface of the inclined surface of the first bump crest and a front surface of the inclined surface of the second bump crest at each overlapping inclined surface of the first bump crest; 4. A gas bearing device according to claim 2 or 3.

6. a hard coating film is further formed on either or both of a back surface of the bottom of the second bump crest and a surface of the stationary holding member at a contact surface between the stationary holding member and the bottom of the second bump crest; 6. A gas bearing device according to claim 4 or 5.

7. At the contact surface between the stationary holding member and the bottom of the second bump crest, a molybdenum disulfide shot treatment layer is further formed on either the back surface of the bottom of the second bump crest or the surface of the stationary holding member, or on both.

6. A gas bearing device according to claim 4 or 5.

8. The stationary retaining member is a stationary retaining member of a journal bearing arranged to face the rotating member in the radial direction.

8. A gas bearing device according to claim 1.

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