Gas bearing

Abstract

To provide a gas bearing that is easy to design and does not require a special mechanism for adjusting the shape and dimensions of a bearing surface.SOLUTION: A gas bearing comprises a sleeve having a rigid bearing surface, and a support structure that elastically supports the sleeve from its radially outer side and is provided over the entire circumferential area of the sleeve. A preferred support structure is an assembly of a plurality of beams. A preferred beam is a cantilever beam or a beam supported at both ends.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to gas bearings that use a gas, such as air, as a lubricating medium. [Background technology]

[0002] A foil bearing is one example of a gas bearing. A foil bearing has a bearing surface made of a flexible thin film such as a metal foil, tape or film that has low bending stiffness. The load of the supported shaft is received by the deflection of the foil, so the precision of the shaft center position is poor, but the foil bearing has high speed stability.

[0003] Patent Document 1 discloses a gas bearing in which the shape and dimensions of the bearing surface can be adjusted even after the bearing is assembled. The gas bearing in Patent Document 1 comprises a housing with a tapered inner surface, a sleeve with a tapered outer surface that fits into the tapered inner surface, and an axial position adjustment means for adjusting the relative axial positional relationship between the housing and the sleeve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-119746 Summary of the Invention [Problem to be solved by the invention]

[0005] The design of foil bearings requires coupling of a fluid lubrication analysis that targets the air film with a structural analysis that targets the deformation of the foil, making the design complicated. The gas bearing of Patent Document 1 requires a mechanism for adjusting the bearing surface in addition to the bearing elements. In view of the above, an object of the present disclosure is to provide a gas bearing that is easy to design and does not require any special mechanism for adjusting the shape and dimensions of the bearing surface. [Means for solving the problem]

[0006] The gas bearing according to the present disclosure comprises a sleeve (11) having a rigid bearing surface (12); and a support structure (15) that elastically supports the sleeve (11) from the radial outside thereof and is provided over the entire circumferential area of ​​the sleeve (11). Effect of the Invention

[0007] According to the present disclosure, a gas bearing is provided that is easy to design and does not require any special mechanism for adjusting the shape and dimensions of the bearing surface. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a basic configuration of an embodiment of a gas bearing according to the present disclosure. FIG. [Diagram 2] FIG. 1 is a diagram illustrating a gas bearing according to a basic configuration. [Diagram 3] FIG. 1 is a diagram showing a gas bearing according to a first embodiment. [Figure 4] FIG. 2 is a diagram illustrating the rigidity of the gas bearing according to the first embodiment. [Diagram 5] FIG. 6 is a diagram showing a gas bearing according to a second embodiment. [Figure 6] FIG. 11 is a diagram showing another gas bearing according to the second embodiment. [Figure 7] FIG. 11 is a diagram showing a gas bearing according to a third embodiment. [Figure 8] FIG. 13 is a diagram showing a gas bearing according to a fourth embodiment. [Figure 9] FIG. 2 is a diagram showing a gas bearing that supports a rotating shaft. [Figure 10] 1A to 1C are diagrams showing examples of bearing surface configurations that may be employed in the air bearing of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the accompanying drawings. Although the present disclosure includes a plurality of embodiments, a basic configuration common to the plurality of embodiments will be described first, and then the plurality of more specific embodiments will be described in order.

[0010] [Basic configuration of the embodiment: see Figs. 1, 9 and 10] 1 comprises a sleeve 11 that houses a rotating shaft 100 therein, and a support structure 15 that elastically supports sleeve 11 from the outside in the radial direction. In gas bearing 1, support structure 15 is elastically deformable, whereas sleeve 11 has a rigid bearing surface 12. Support structure 15 is disposed over the entire circumferential area of ​​sleeve 11.

[0011] [Function of rigid bearing surface 12] In gas bearings, a thin film of gas, typically air, is created between the bearing surface and the shaft, which is drawn in by the rotation of the shaft. In the case of foil bearings, the top foil that provides the bearing surface is formed to be very thin, and is therefore deformed by the pressure of this air film. When the top foil deforms, the circumferential distribution (shape) of the air film changes, and the pressure distribution in the air film also changes. In this way, the pressure distribution in the air film and the deformation of the top foil have a mutually influencing relationship. Therefore, when designing a foil bearing, it is necessary to couple a fluid lubrication analysis that targets the air film with a structural analysis that targets the deformation of the foil.

[0012] If the bearing surface 12 is rigid, as in the gas bearing 1 of the present disclosure, the bearing surface 12 will not deform regardless of the presence or absence of an air film and its shape, and therefore the shape of the bearing surface 12 will be maintained. Therefore, the bearing surface 12 and the air film do not affect each other and can be said to be independent. Although the bearing surface 12 has been described as being rigid here, in the following it will be assumed that the entire sleeve 11 including the bearing surface 12 is rigid.

[0013] [Role of flexible support structure 15] While the sleeve 11 is rigid, the support structure 15 is configured to be elastically deformable and elastically supports the sleeve 11. Although the sleeve 11 is rigid and does not elastically deform, it may be displaced in the radial direction RD while supporting the rotating shaft 100. The support structure 15 absorbs this displacement of the sleeve 11 by elastically deforming. Here, sleeve 11 being rigid does not mean that sleeve 11 is made of a completely rigid body, but that it has a degree of rigidity that does not cause it to elastically deform due to the rotating shaft 100 it supports. Even if sleeve 11 is made of the same material, it may or may not be considered rigid depending on the rotating shaft 100 it supports. The elastic deformation of support structure 15 is similar to the rigidity of sleeve 11, and is not determined solely by the material, but is premised on its use as a gas bearing 1.

[0014] [Manufacturing process used] Considering that it is the mechanical precision of the components that affects the bearing performance of a foil bearing, it is desirable to employ a process for manufacturing gas bearing 1. For example, in order to satisfy the dimensional precision of sleeve 11 and support structure 15 of gas bearing 1, methods such as cutting, electric discharge machining, additive manufacturing (AM), and injection molding can be employed. Therefore, according to gas bearing 1, it is possible to manufacture gas bearing 1 with high mechanical precision in terms of dimensions, shape, etc., and variation in bearing characteristics can be suppressed. The material constituting the air bearing 1 is arbitrary, and metal materials are mainly used, but resin materials may also be used. In cases where the inner and outer rings and the rolling elements are in constant sliding contact with each other, such as in rolling bearings, bearing steel (JIS SUJ) is used to prevent sliding wear, but in the case of gas bearing 1, even if sliding occurs between the components, it is less than in rolling bearings. Therefore, there are many material options for gas bearing 1.

[0015] [Example of support structure 15: see Figure 2] Several configurations of the support structure 15 will be described. In the example shown in Fig. 2, a housing 17 is provided around the support structure 15. In this example, the support structure 15 is provided between the housing 17 and the sleeve 11. However, depending on the type of machinery in which a gas bearing is used, a member corresponding to the housing 17 may be provided in the machinery. Therefore, the housing 17 is an optional feature in the present disclosure.

[0016] Here, three types, Cmp.1, Emb.1, and Emb.2, are shown as examples. Cmp.1, Emb.1, and Emb.2 differ in the configuration of the support structure 15 in the circumferential direction CD. The horizontal direction H and vertical direction V when the gas bearing is used are defined as shown in FIG.

[0017] Cmp.1 is a part of the circumferential direction CD, and the support structure 15 is provided only in the weight direction of the rotating shaft. These support structures 15 are provided with consideration only for supporting the load of the shaft (not shown). However, in reality, the gas bearing 1 is subjected to loads in directions other than the weight direction due to whirling of the shaft or external vibration. Therefore, as shown in Emb.1 and Emb.2, if they are arranged over the entire circumferential direction CD, the shaft can be supported against loads in directions other than the weight direction. The support structure 15 of Emb.1 has a periodic structure in addition to covering the entire circumferential direction CD. The support structure 15 of Emb.2 also covers the entire direction CD, but does not have a periodic structure but has a non-periodic structure.

[0018] A gas bearing having the above basic configuration is easy to design because the deformation of the bearing surface 12 and the pressure distribution of the gas film are independent due to the rigidity of the bearing surface 12. In addition, a gas bearing having a basic configuration has a support structure in the direction other than the weight of the rotating shaft, and can therefore accommodate loads other than the weight of the rotating shaft, such as vibrations of the rotating shaft, thereby achieving stable high-speed rotation. Gas bearings having the basic structure can be manufactured by cutting, AM and injection molding, which enables high-precision bearing manufacturing and reduces variation in bearing characteristics.

[0019] The basic configuration and effects of the gas bearing 1 according to the present disclosure have been described above, and more specific examples of the gas bearing 1 will now be described in order.

[0020] [First embodiment: see FIG. 3] Gas bearings 1A to 1F according to a first embodiment will be described with reference to Fig. 3. Gas bearings 1A to 1F have a common configuration in that they include a sleeve 11, a support structure 15, and a housing 17, but the specific structure of support structure 15 is different. Support structure 15 is composed of a plurality of beams 16 between sleeve 11 and housing 17 that mainly generate bending stress due to a load received from the shaft about which sleeve 11 rotates and transmits the stress to housing 17. In other words, support structure 15 is an assembly of a plurality of beams 16 provided between sleeve 11 and housing 17. Gas bearings 1A to 1F differ in the shape and arrangement of the beams.

[0021] [Gas bearing 1A] In the gas bearing 1A, the support structure 15 is formed of a plurality of cantilevers 16A curved in an arc. The fixed end 16A1 of the cantilever 16A is connected to the housing 17, and the free end 16A2 is provided between the sleeve 11 and the housing 17. That is, the cantilever 16A of the gas bearing 1A is curved in the radial direction RD. The cantilever 16A is connected to the sleeve 11 at a contact point 16A3 between the fixed end 16A1 and the free end 16A2, which is the apex of the arc as seen from the housing 17 side. In the gas bearing 1A, eight cantilevers 16A are arranged at equal intervals in the circumferential direction CD. The contact points 16A3 are joined to the sleeve 11, so that the entire gas bearing 1A is integrally formed. The gas bearings 1B to 1F are also integrally formed in the same manner. The shape of cantilever beam 16A is the shape seen when gas bearing 1A is viewed from the front. Also, cantilever beam 16A is continuous in the direction of axis C of air bearing 1A. The other gas bearings are similar.

[0022] [Gas bearing 1B] In the gas bearing 1B, the support structure 15 is formed of a plurality of diagonal beams 16B1, 16B2 inclined with respect to the radial direction RD. The diagonal beam 16B1 is connected to both the sleeve 11 and the housing 17, and is inclined clockwise in the figure. The diagonal beam 16B2 is connected to both the sleeve 11 and the housing 17, and is inclined counterclockwise in the figure. The pair of diagonal beams 16B1 and 16B2 is rigidly connected to the sleeve 11 at one end, and rigidly connected to the housing 17 at the other end. In other words, the support structure 15 in the gas bearing 1B forms a rigid frame structure consisting of the combination of the triangular diagonal beams 16B1, 16B2, the sleeve 11, and the housing 17.

[0023] [Gas bearing 1C] Like gas bearing 1B, gas bearing 1C has support structure 15 made of a rigid frame structure. In the rigid frame structure of gas bearing 1B, one end (the side of sleeve 11) and the other end (the side of housing 17) of a pair of diagonal beams 16B1, 16B2 are rigidly connected together, whereas in gas bearing 1C, one end (the side of sleeve 11) of a pair of diagonal beams 16B1, 16B2 are rigidly connected together, but the other ends (the side of housing 17) are each independently rigidly connected to housing 17. That is, gas bearing 1C can increase the number of points that support housing 17 compared to gas bearing 1B.

[0024] In gas bearing 1B and gas bearing 1C, a diagonal beam unit consisting of a pair of diagonal beams 16B1, 16B2 is provided continuously in the circumferential direction CD, but for example, the diagonal beam units may be provided intermittently in the circumferential direction CD. More specifically, in gas bearing 1B, eight diagonal beam units may be provided with no gaps at 45° intervals, or four diagonal beam units may be provided at 90° intervals. In this case as well, support structure 15 is provided over the entire circumferential area.

[0025] [Gas bearing 1D] Gas bearing 1D has support structure 15 formed of a plurality of beams 16D supported at both ends and curved in an arc shape. One end of this double-supported beam 16D is fixed to the sleeve 11, and the other end is fixed to the housing 17. A plurality of double-supported beams 16D are arranged at equal intervals or periods in the circumferential direction CD. The double-supported beams 16D are curved in the same direction in the circumferential direction CD.

[0026] [Gas bearing 1E] In the gas bearing 1E, a support structure 15 is formed of a double-supported beam 16E made of multiple thin plates similar to an involute curve. One end of the double-supported beam 16E is fixed to the sleeve 11, and the other end is fixed to the housing 17. A plurality of double-supported beams 16E, three in this example, are arranged at equal intervals or periods over the entire circumferential direction CD.

[0027] [Gas bearing 1F] In the gas bearing 1F, the support structure 15 is made up of a plurality of straight cantilever beams 16F. One end 16F1 of the cantilever beams 16F is fixed to the housing 17, and the other end 16F2 constitutes a free end. The cantilever beam 16F is connected to the sleeve 11 at a contact point 16F3 midway between the one end and the other end. A plurality of double-supported beams 16E, three in this example, are arranged at equal intervals or periods in the circumferential direction CD.

[0028] [Adjusting the stiffness of gas bearing 1A: see Figure 4] In the gas bearing 1A, when the sleeve 11 and the support structure 15 are joined, the sleeve 11 is supported by all beams 16A, including (2) and (4), as well as (1) and (3) arranged above and below the load L, when the load L is applied. Therefore, as in the design of foil bearings, the stiffness R in the load direction (vertical direction V) is V If the beam 16A is designed only with the stiffness R V and stiffness R V Stiffness R perpendicular to H It is necessary to design the beam 16A taking into consideration both of the above. In this case, the stiffness R V is the stiffness R H If it is possible to make the stiffness R larger than H Since the increase in bearing stiffness due to the above can be relatively ignored, the design of the beam 16A becomes easier.

[0029] In gas bearings 1B to 1F, the rigidity in the load direction and the direction perpendicular thereto can be adjusted by devising the shape and dimensions of beams and the like that constitute support structure 15. For example, both-end supported beam 16E of gas bearing 1E and cantilever beam 16F of gas bearing 1F have vertical rigidity R V <Horizontal stiffness R H The beam 16D supported at both ends of the gas bearing 1D has a vertical stiffness R V >Horizontal stiffness R H The above relationship exists.

[0030] [Effects of the first embodiment] Gas bearings 1A to 1F have an integral structure and do not require assembling a plurality of members, so there is no assembly error, and therefore gas bearings 1A to 1F can reduce manufacturing errors. Next, according to the gas bearings 1A to 1F, by adjusting the rigidity of the support structure 15, any rigidity can be imparted in any direction, so that desired bearing performance can be obtained. Furthermore, if the radial stiffness is greater than or equal to the circumferential stiffness, then it is only necessary to consider the radial stiffness, which makes it easier to consider the support structure 15 using a theoretical formula.

[0031] [Second embodiment: Figs. 5 and 6] Next, gas bearings 2A to 2D according to a second embodiment will be described with reference to FIGS. The second embodiment discloses gas bearings 2A to 2D which, in addition to the elements included in the first embodiment, include a friction damping element in the space of support structure 15. Gas bearings 2A to 2D differ in the content of the friction damping element included in support structure 15.

[0032] [Gas bearing 2A: see Figure 5] The gas bearing 2A uses cantilever beams 16G made of a thin plate similar to that of the gas bearing 1E of the first embodiment. In the gas bearing 2A, the multiple cantilever beams 16G are divided into three groups G1, G2, and G3, and in each of the groups G1, G2, and G3, the cantilever beams 16G overlap with adjacent cantilever beams 16G. A specific cantilever beam 16G has a fixed end on the housing 17 side and also a fixed end on the sleeve 11 side. In each of the groups G1, G2, and G3, the specific cantilever beam 16GI arranged at the innermost side in the radial direction RD has the other end integrated with the sleeve 11. This allows the sleeve 11 to be elastically supported by the support structure 15. In each of the groups G1, G2, and G3, the adjacent cantilever beams 16G are in contact with each other so as to be able to slide.

[0033] When the gas bearing 2A supports a rotating shaft and a load W is applied in the vertical direction V, the sleeve 11 supported by the cantilever 16GI is displaced in the vertical direction V. When the displaced sleeve 11 presses down on the other cantilever 16G, the other cantilever 16G is supported in a cantilevered manner, so that overlapping surfaces slide against each other, generating friction. As a result of vibration damping caused by this friction, particularly stable high-speed rotation can be achieved. The gas bearing 2A is equipped with the first friction damping element of the present disclosure.

[0034] [Gas bearing 2B: see Figure 5] In the gas bearing 2B, the support structure 15 is formed of a plurality of cantilever beams 16H curved in an arc. Cantilever beam 16H is similar to cantilever beam 16A of the first embodiment, but its free end extends toward the housing 17 side beyond cantilever beam 16A. The portion that contacts housing 17 is folded back toward sleeve 11. This folded back curved surface 16H1 is in slidable contact with inner circumferential surface 17I of housing 17. Note that the same parts as cantilever beam 16A are given the same reference numerals as cantilever beam 16A and will not be described.

[0035] In gas bearing 2B, when a rotating shaft is supported and load L is applied in vertical direction V, friction is generated between multiple curved surfaces 16H and inner circumferential surface 17I of housing 17, and vibration is damped by this friction, thereby achieving particularly stable high-speed rotation. Note that gas bearing 2B is provided with the third friction damping element of the present disclosure.

[0036] [Gas bearing 2C: see Figure 6] Gas bearing 2C has support structure 15 made up of multiple cantilever beams 16I curved in an arc. Cantilever beam 16I is provided with a sliding plate 16I1 on the free end side, and a sliding surface 16I2 of sliding plate 16I1 facing outward in radial direction RD is in slidable contact with inner circumferential surface 17I of housing 17.

[0037] In gas bearing 2C, when a rotating shaft is supported and a load W is applied in vertical direction V, friction is generated between multiple sliding surfaces 16I2 and inner circumferential surface 17I of housing 17, thereby providing a vibration damping effect. Note that gas bearing 2C is provided with the third friction damping element of the present disclosure.

[0038] [Gas bearing 2D: see Figure 6] The support structure 15 in the gas bearing 2D includes diagonal beams 16J1, 16J2 and diagonal beams 16J3, 16J4 that are inclined with respect to the radial direction RD. The diagonal beams 16J1 and 16J2 are arranged on the far side of the paper surface (FIG. 6) relative to the diagonal beam 16J2, and they intersect with each other. The diagonal beams 16J3 and 16J4 are arranged on the far side of the paper surface (FIG. 6) relative to the diagonal beam 16J2, and they intersect with each other. The diagonal beams 16J1 and 16J2 form a cantilever beam with a fixed end on the sleeve 11 side and a free end 16J5 on the housing 17 side. Although an example is shown in which the free end 16J5 is a small distance away from the inner peripheral surface 17I of the housing 17, it may be in contact with the inner peripheral surface 17I. The diagonal beams 16J3 and 16J4 have fixed ends on the sleeve 11 side and also on the housing 17 side, and constitute a double-supported beam.

[0039] In gas bearing 2D, when a rotating shaft is supported and a load W is applied in a vertical direction V, friction is generated between free ends 16J5 and inner circumferential surface 17I of housing 17, and vibration damping due to this friction enables particularly stable high-speed rotation to be achieved. Gas bearing 2D also includes the third friction damping element of the present disclosure.

[0040] [Effects of the second embodiment] Gas bearings 2A to 2D are provided with a friction damping element, which provides a vibration damping effect, thereby reducing the contact of the rotating shaft during rotation and improving the stability of the shaft diameter, thereby achieving particularly stable high-speed rotation.

[0041] [Third embodiment: see FIG. 7] Next, gas bearings 3A and 3B according to a third embodiment will be described with reference to FIG. In the third embodiment, friction is generated by including a sliding portion between the sleeve 11 and the support structure 15 in part or in whole, thereby obtaining a damping effect. The gas bearings 3A and 3B are provided with the second friction damping element of the present disclosure.

[0042] Gas bearings 3A and 3B have the same basic configuration as gas bearing 1A. However, in gas bearing 3A, of cantilever beams 16K1 and K2 curved into a plurality of arcs, cantilever beam 16K1 is in slidable contact with outer peripheral surface 11O of sleeve 11 at contact surface 16K3, while cantilever beam 16K2 is joined to outer peripheral surface 11O of sleeve 11. Thus, in gas bearing 3A, sleeve 11 is supported by cantilever beams 16K1 and K2. In gas bearing 3B, all of the multiple arc-shaped curved cantilever beams 16K1 are in slidable contact with outer peripheral surface 11O of sleeve 11 at contact surfaces 16K3, thereby supporting sleeve 11 by support structure 15. Gas bearing 3B is constructed by assembling two members: sleeve 11 and housing 17 with which cantilever beams 16K1 are integrally formed.

[0043] Although an example in which sliding is provided partially or entirely between sleeve 11 and support structure 15 has been illustrated here, in other embodiments, a slidably separated portion can be provided partially or entirely between housing 17 and support structure 15. In addition, in cases where gas bearings 3A, 3B do not include housing 17, a slidably separated portion can be provided partially or entirely between a housing substituting for housing 17 and support structure 15.

[0044] [Effects of the third embodiment] In the third embodiment, as in the second embodiment, a vibration damping effect is obtained by providing a friction damping element, which reduces the contact of the rotating shaft during rotation and improves the stability of the shaft diameter during rotation. As in the gas bearing 3B, when all of the cantilever beams 16K1 are in contact with the sleeve 11 at the contact surface 16K3 and the support structure 15 and the sleeve 11 are separated, only the rigidity in the radial direction RD acts, making it easy to consider the support structure 15 using theoretical formulas.

[0045] [Fourth embodiment: see FIG. 8] Next, gas bearings 4A, 4B, and 4C according to a fourth embodiment will be described with reference to FIG. In the fourth embodiment, a viscoelastic body is interposed at a sliding location, thereby obtaining vibration damping due to material damping of the viscoelastic body.

[0046] Gas bearing 4A has the same basic configuration as gas bearing 3B, but in addition to providing damping cylinder 18 made of a viscoelastic material between sleeve 11 and cantilever beam 16K1, a damping sheet 19 made of a viscoelastic material is provided between inner circumferential surface 17I of housing 17 and the tip of cantilever beam 16K1. It can be said that gas bearing 4A replaces the damping due to friction in gas bearing 3B with material damping using a viscoelastic material.

[0047] Gas bearing 4B has the same basic configuration as gas bearing 4A, but has damping body 21 made of a rod-shaped viscoelastic body provided between housing 17 and free end 16A2 of cantilever beam 16A.

[0048] Gas bearing 4C has the same basic configuration as gas bearing 1C, but has damping body 23 made of a rod-shaped viscoelastic body provided between sleeve 11 and housing 17.

[0049] [Effects of the fourth embodiment] According to the gas bearings 4A, 4B, and 4C of the fourth embodiment, a viscoelastic material is interposed between the sleeve 11 and the beam 16, and / or between the housing 17 and the beam 16, thereby achieving a higher vibration damping effect.

[0050] [Note] The gas bearing according to the present disclosure is understood as follows. [Appendix 1] a sleeve (11) having a rigid bearing surface (12); a support structure (15) that elastically supports the sleeve (11) from the outside in the radial direction (RD) and is provided over the entire circumferential area of ​​the sleeve (11); A gas bearing comprising:

[0051] [Appendix 2] In Appendix 1, the preferred support structure (15) is It consists of a collection of multiple beams (16).

[0052] [Appendix 3] In Appendix 2, the preferred beam (16) comprises a cantilever beam (16A) or a double-supported beam (16D).

[0053] [Appendix 4] In Appendix 1, the preferred support structure (15) is It consists of a rigid frame structure.

[0054] [Appendix 5] In addition, the present invention preferably includes a housing (17) surrounding the support structure (15), The support structure (15) is A first friction damping element comprising a plurality of cantilever beams (16G) slidable relative to one another; A second friction damping element formed by sliding between the plurality of cantilevers (16G) and the sleeve (11); and The third friction damping element is provided by sliding between the multiple cantilever beams (16G) and the housing (17).

[0055] [Appendix 6] In Appendix 5: A housing (17) is provided surrounding the support structure, A viscoelastic body is interposed between the sleeve (11) and the beam (16) and / or between the housing (17) and the beam (16).

[0056] [Appendix 7] In addition, the present invention preferably includes a housing (17) surrounding the support structure, The sleeve (11), the support structure (15) and the housing (17) are integrally formed. [Appendix 8] In any one of Supplementary Note 1 to Supplementary Note 7, preferably, the bearing surface is either a perfect circle or a plurality of offset circular arcs.

[0057] In addition to the above, it is possible to select and discard the configurations given in the above embodiment, or to change them to other configurations as appropriate. For example, the support structure 15 is not limited to a group of beams. For example, instead of the beams 16, a member that is easily elastically deformed, such as rubber, can be disposed between the sleeve 11 and the housing 17. In addition, as shown in FIG. 10, the bearing surface 12 in the present disclosure is not limited to a perfect circle shape as shown in (a), but may have a shape in which multiple arcs are offset, such as two arcs AR, three arcs AR, and four arcs AR, as shown in (b), (c), and (d) in order. When a bearing surface in which multiple arcs are offset is adopted, the destabilizing force is relatively small compared to a perfect circular bearing surface, so that vibration stability can be improved. For example, a vibration analysis has shown that when a bearing surface in which two arcs are offset is adopted, vibration stability is improved by about 25% compared to a perfect circular shape. Note that the amount of offset is exaggerated in FIGS. 10(b), (c), and (d) to clearly show that it is offset. [Explanation of symbols]

[0058] 1,1A,1B,1C,1D,1E,1F Gas bearings 2A, 2B, 2C, 2D Gas bearings 3A, 3B Gas bearings 4A, 4B, 4C Gas bearings 11 Sleeve 11O Outer surface 12 Bearing surface 15 Support structure 16 Beam 16A Cantilever beam 16A1 Fixed end 16A2 Free end 16A3 Support point 16A3 Contact 16B1,16B2 Diagonal beam 16D, 16E Double-supported beam 16F,16G,16GI,16H,16I cantilever 16F1 One end 16F2 other end 16F3 Contact 16H curved surface 16I1 Sliding plate 16I2 Sliding surface 16J1,16J2 Diagonal beam 16J3 Sliding end face 16K1,K2 Cantilever beam 16K3 contact surface 16K5 Tip 17 Housing 17I Inner surface 18 Attenuation tube 19 Damping Sheet 21,23 Attenuator

Claims

1. a sleeve having a rigid bearing surface; a support structure that elastically supports the sleeve from a radially outer side thereof and is provided over the entire circumferential area of ​​the sleeve; A gas bearing comprising:

2. The support structure includes: It is made up of a collection of multiple beams.

2. The gas bearing according to claim 1.

3. The beam is Consists of a cantilever or a beam supported at both ends; 3. A gas bearing according to claim 2.

4. The support structure includes: It consists of a rigid frame structure.

2. The gas bearing according to claim 1.

5. a housing surrounding the support structure; The support structure includes: a first friction damping element formed of a plurality of said cantilever beams slidable relative to one another; a second friction damping element formed by sliding between the plurality of cantilevers and the sleeve; and a third friction damping element formed by sliding between the cantilever beams and the housing; 4. A gas bearing according to claim 3.

6. a housing surrounding the support structure; a viscoelastic body is interposed between the sleeve and the beam and / or between the housing and the beam; 6. A gas bearing according to claim 5.

7. a housing surrounding the support structure; the sleeve, the support structure and the housing are integrally formed; 2. The gas bearing according to claim 1.

8. The bearing surface is either a perfect circle or a number of offset arcs.

2. The gas bearing according to claim 1.

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