CN218598602U

CN218598602U - Thrust foil bearing

Info

Publication number: CN218598602U
Application number: CN202222182739.1U
Authority: CN
Inventors: 陈双涛; 万晓; 赖天伟; 陈良; 张泽; 侯予
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2022-08-18
Filing date: 2022-08-18
Publication date: 2023-03-10
Anticipated expiration: 2032-08-18

Abstract

The application belongs to the technical field of bearings, and particularly relates to a thrust foil bearing. Conventional thrust foil bearings do not accommodate rotor pitch and yaw well. The application provides a thrust foil bearing, which comprises a flexible structure, a back plate and a movable structure which are sequentially connected, wherein the flexible structure comprises a flat foil, a gasket and a wave foil assembly which are sequentially connected, the wave foil assembly is arranged on the back plate and comprises a first wave foil and a second wave foil, the first wave foil comprises a first flat section and a first wave arch, the second wave foil comprises a second flat section and a second wave arch, the first flat section is connected with the back plate, the second flat section is connected with the back plate, the first flat section is provided with the first gasket, the flat foil and the second gasket are sequentially connected with the second flat section, the first wave arch is free, and the flat foil is in contact with the first wave arch; the back plate and the movable structure form a kinematic pair, and the back plate can freely incline or swing. Simple structure, low cost and strong applicability.

Description

Thrust foil bearing

Technical Field

The application belongs to the technical field of bearings, and particularly relates to a thrust foil bearing.

Background

With the development of the fields of high-speed turbines, aerospace, precision instruments and the like, the rotating speed and the stability of the bearing in the rotating machinery have higher requirements. The dynamic pressure thrust bearing is widely applied to the rotor support of high-speed rotating machinery, wherein the foil bearing occupies a main position in the dynamic pressure bearing due to the characteristics of simple structure, high rotating speed, long service life, low power consumption, cleanness, wide working temperature range and the like.

The high precision dimensions of foil bearings require relatively stable operating conditions of the bearings, and misalignment of the rotor is an inevitable failure of the rotating machine due to installation errors, asymmetric loads and thermal deformations. Misalignment of the bearing-rotor system changes the operating conditions of the bearing, which produces a series of dynamic effects that are detrimental to the stable operation of the rotating machine. Such as: the thickness of a lubricating gas film is reduced, and the bearing capacity, rigidity, damping and the like of the bearing during working are reduced; deflection deformation of the rotor; excessive vibration of the rotor system; resulting in dry friction of the rotor system with the bearing surface, damage to the coating, and generation of a large amount of frictional heat; the rotor may be unstable or even locked. The phenomenon of rotor misalignment under the high-speed and high-load working condition of the bearing-rotor system is one of the main reasons influencing the stability and reliability of the high-speed rotating machine.

The thrust foil bearing with elastic support has a certain deformation space and compensation effect on the misalignment of the rotor due to the characteristic combination of low friction and high damping. However, for excessive eccentricity and misalignment of the thrust plate, increasing the local deflection by increasing the damping of the resilient bearing under the lubricated surface is often ineffective. The reason for this is that conventional thrust foil bearings are integrally fixed and do not have circumferential and radial degrees of freedom, resulting in poor adaptability to rotor pitch and yaw.

SUMMERY OF THE UTILITY MODEL

1. Technical problem to be solved

Based on the problem that the traditional thrust foil bearing is integrally fixed and does not have circumferential and radial freedom degrees, so that the thrust foil bearing cannot be well adapted to the inclination and the swing of a rotor, the application provides the thrust foil bearing.

2. Technical scheme

In order to achieve the above object, the present application provides a thrust foil bearing, including a flexible structure, a back plate, and a movable structure, which are connected in sequence, where the flexible structure includes a flat foil, a spacer, and a wave foil assembly, the wave foil assembly is disposed on the back plate, the wave foil assembly includes a first wave foil and a second wave foil, which are arranged in sequence, the first wave foil includes a first flat section and a first wave arch, which are connected to each other, the second wave foil includes a second flat section and a second wave arch, which are connected to each other, the first flat section is connected to the back plate, the second flat section is connected to the back plate, the first flat section is provided with the first spacer, one end of the flat foil, the second spacer, and the second flat section are connected in sequence, the first wave arch is free, and the other end of the flat foil is in contact with the first wave arch; the back plate and the movable structure form a kinematic pair, and the back plate can freely tilt or swing.

Another embodiment provided by the present application is: the movable structure is connected with the back plate through a movable joint, the movable structure comprises a pressing plate and a first bearing seat which are connected with each other, one end of the movable joint is connected with the back plate, the other end of the movable joint penetrates through the pressing plate, the other end of the movable joint is arranged in the first bearing seat, and the back plate 4 can freely incline or swing around the movable joint.

Another embodiment provided by the present application is: an elastic gasket is arranged between the pressing plate and the first bearing seat, and the pressing plate, the elastic gasket and the first bearing seat are connected through fastening screws.

Another embodiment provided by the present application is: the movable joint is of a spherical structure, the spherical structure comprises a boss, and the plane of the boss is fixedly connected with the back plate.

Another embodiment provided by the present application is: the pressing plate is of a disc-shaped structure.

Another embodiment provided by the present application is: the movable structure comprises a second bearing seat, one side of the disc-shaped structure is a plane, the bump foil assembly is arranged on the plane, the other side of the disc-shaped structure is a curved surface, the curved surface is matched with the second bearing seat, the back plate is connected with the second bearing seat through a contact point, and the back plate 4 can freely tilt or swing around the contact point.

Another embodiment provided by the present application is: the back plate is of a disc-shaped structure, and the second bearing seat is of a split type semicircular structure.

Another embodiment provided by the present application is: the bearing comprises a bearing body, a bearing seat, a movable structure, a back plate, a third bearing seat, a rolling friction pair and a ring structure, wherein the movable structure comprises a fixing ring and the third bearing seat which are connected with each other, the fixing ring is connected with the back plate, the back plate is in a ring structure which is coaxially arranged with the third bearing seat, the back plate and the fixing ring form the rolling friction pair, and the back plate can wind the axis of the third bearing seat to perform inclined motion.

Another embodiment provided by the present application is: the back plate is provided with a plurality of slits which are distributed along the radial direction.

Another embodiment provided by the present application is: the flexible structure comprises a plane area, a wedge area and a fixed area which are connected in sequence.

3. Advantageous effects

Compared with the prior art, the thrust foil bearing provided by the application has the beneficial effects that:

the thrust foil bearing provided by the application has certain radial and circumferential degrees of freedom, allows the back plate 4 to freely tilt or swing within a certain angle, and can improve the adaptability of the thrust foil bearing to the eccentricity of a thrust disc and the misalignment of a rotor. The working performance of the gas thrust foil bearing under the high-speed and high-load condition is ensured, and the stability of a rotor system is improved.

The thrust foil bearing is simple in structure, low in cost and high in applicability; can be widely applied to the application field of gas foil bearings.

The application provides a thrust foil bearing, which is a thrust foil bearing with an inclination degree of freedom.

Drawings

FIG. 1 is an exploded schematic view of a thrust foil bearing structure of the present application;

FIG. 2 is a schematic cross-sectional view of a thrust foil bearing structure of the present application;

FIG. 3 is a partial schematic view of a thrust foil bearing of the present application;

FIG. 4 is a second exploded schematic view of the thrust foil bearing structure of the present application;

FIG. 5 is a second cross-sectional schematic view of the thrust foil bearing structure of the present application;

FIG. 6 is a schematic view of a second partial structure of the thrust foil bearing of the present application;

FIG. 7 is a third exploded schematic view of the thrust foil bearing structure of the present application;

FIG. 8 is a third cross-sectional schematic view of the thrust foil bearing structure of the present application;

FIG. 9 is a schematic view of a third partial structure of the thrust foil bearing of the present application;

FIG. 10 is a fourth partial schematic view of a thrust foil bearing of the present application.

Detailed Description

Hereinafter, specific embodiments of the present application will be described in detail with reference to the accompanying drawings, and it will be apparent to those skilled in the art from this detailed description that the present application can be practiced. Features from different embodiments may be combined to yield new embodiments, or certain features may be substituted for certain embodiments to yield yet further preferred embodiments, without departing from the principles of the present application.

Referring to fig. 1 to 10, the application provides a thrust foil bearing, which includes a flexible structure, a back plate 4 and a movable structure, which are connected in sequence, where the flexible structure includes a flat foil 1, a spacer 2 and a wave foil 3 assembly, the wave foil 3 assembly is disposed on the back plate 4, the wave foil 3 assembly includes a first wave foil 3 and a second wave foil 3, which are arranged in sequence, the first wave foil 3 includes a first flat section and a first wave arch, which are connected to each other, the second wave foil 3 includes a second flat section and a second wave arch, which are connected to each other, the first flat section is connected to the back plate 4, the second flat section is connected to the back plate 4, the first spacer 2 is disposed on the first flat section, one end of the flat foil 1 and the second spacer 2 are connected to the second flat section in sequence, the first wave arch is free, and the other end of the flat foil 1 is in contact with the first wave arch; the back plate 4 and the movable structure form a kinematic pair, and the back plate 4 can freely tilt or swing.

The flat foils 1, the gaskets 2 and the wave foils 3 are sequentially arranged on the bearing seat from top to bottom, and the number of the flat foils, the gaskets 2 and the wave foils is the same and is generally 4-8; the wave foil 3 is in a regular fan shape, and the flat foil 1 and the wave foil 3 are different in shape and size. The bump foil 3 is fixed on the back plate 4, and the fixed end of the bump foil is flush with the positioning groove on the back plate 4; the shim 2 is fixed to the plane section of the bump foil 3 and has one end flush with the front edge thereof; the flat foil 1 is fixed on the gasket 2, and the fixed end of the flat foil is flush with the other end of the gasket 2; the flat foils 1 and the wave foils 3 are arranged in staggered arrangement in the circumferential direction, and the directions of the fixed ends to the free ends of the flat foils are opposite.

The converged wedge-shaped gap is naturally formed by the lap joint of the flat foil 1, the gasket 2 and the bump foil 3, and the flat foil 1 does not need to be subjected to pre-deformation treatment. In general, in a thrust foil bearing, a flat foil needs to be subjected to a punching process in order to form a desired wedge gap. After the gasket is adopted, because the gasket and the wave foil have a certain height difference, the flat foil can naturally form a convergence gap, and the gap can be adjusted by adjusting the height of the gasket.

The structure ensures that the thrust foil bearing has certain inclination freedom degree, allows the back plate 4 to freely incline or swing, can improve the adaptability of the thrust foil bearing to the eccentricity of a thrust disc and the misalignment of a rotor, ensures the working performance of the gas thrust foil bearing under the high-speed and high-load condition, and improves the stability of a rotor system.

The foils in foil bearings are generally fan-shaped. One end of the flat foil 1 is completely overlapped with the shape of the straight gasket, and the shape of the flat foil 1 is adjusted in the application so as to realize the positive and negative installation of the wave foil 3 of the flat foil 1 under the condition of not changing the fan shape of the wave foil. (the processing difficulty of the sector wave foil is lower, and the processing difficulty of the wave foil is far higher than that of the flat foil)

Furthermore, the movable structure is connected with the backboard 4 through a movable joint 8, the movable structure comprises a pressing plate 6 and a first bearing seat which are connected with each other, one end of the movable joint 8 is connected with the backboard 4, the other end of the movable joint 8 penetrates through the pressing plate 6, the other end of the movable joint 8 is arranged in the first bearing seat, and the backboard 4 can freely incline or swing around the movable joint 8.

The thrust foil bearing is divided into a flexible structure and a movable structure, wherein the flexible structure comprises a flat foil 1, a gasket 2 and a wave foil 3. The movable structure comprises a back plate 4, a fastening screw 5, a pressure plate 6, an elastic washer 7, a movable joint 8 and a bearing seat 9, or the back plate 4 and the bearing seat, or a fixed ring 10 and the bearing seat. The flat foil 1, the gasket 2 and the wave foil 3 are sequentially fixed on the movable structure from top to bottom, and the directions of the flat foil 1 and the wave foil 3 from the fixed end to the free end are opposite. The movable structure and the back plate 4 form a kinematic pair, so that the back plate 4 can freely tilt or swing around a pivot thereof.

The movable joint 8 is of a spherical structure with a boss, the back plate 4 is of a disc structure, and the boss plane of the movable joint 8 is fixedly connected with the back plate 4. The bearing seat 9 is of a disc-shaped structure, an annular boss matched with the pressing plate 6 is arranged at the outer edge of the bearing seat, a screw hole for fixing is formed in the circumferential direction of the bearing seat, and a spherical hole matched with the movable joint 8 is formed in the upper surface of the bearing seat. The pressing plate 6 is of a disc-shaped structure, is provided with a circular boss matched with the bearing seat 9, and is concentrically provided with a spherical hole and a circular hole matched with the movable joint 8. The elastic washer 7 is arranged between the pressure plate 6 and the bearing seat, coaxially arranged and fixedly connected through the fastening screw 5. The movable joint 8 is arranged in a spherical hole in the pressing plate 6 and the bearing seat 9 to form a kinematic pair, the back plate 4 is hinged through the movable joint 8, a certain gap is formed between the lower surface of the back plate 4 and the upper surface of the pressing plate 6, and the back plate 4 can freely incline or swing around the spherical center of the movable joint 8.

The thrust foil bearing has axial rigidity and radial and circumferential degrees of freedom, so that the integral structure of the thrust foil bearing can freely incline and swing, has good adaptability and self-balancing capability to the phenomena of eccentricity of a thrust disc and misalignment of a rotor, and can improve the stability and reliability of a bearing-rotor system.

The application provides a backplate 4, clamp plate 6, elastic washer 7, swing joint 8, bearing frame 9 or solid fixed ring 10 are split type structure, have reduced the processing cost and the processing degree of difficulty, easy dismounting, and the required precision is low.

Furthermore, an elastic gasket 7 is arranged between the pressure plate 6 and the first bearing seat, and the pressure plate 6, the elastic gasket 7 and the first bearing seat are connected through a fastening screw 5.

Further, the movable joint 8 is a spherical structure, the spherical structure includes a boss, and the boss plane is fixedly connected with the back plate 4.

Further, the pressing plate 6 has a disc-shaped structure.

Further, the movable structure comprises a second bearing seat 11, one side of the dish-shaped structure is a plane, the wave foil 3 assembly is arranged on the plane, the other side of the dish-shaped structure is a curved surface, the curved surface is matched with the second bearing seat 11, the back plate 4 is connected with the second bearing seat 11 through a contact point, and the back plate 4 can freely tilt or swing around the contact point.

The back plate 4 is of a disc-shaped structure, and the lower surface of the back plate is a curved surface. The second bearing seat 11 is of a split type semicircular structure, a groove matched with the curved surface of the back plate 4 is formed in the surface of the second bearing seat, the curvature of the groove is larger than that of the back plate 4, and the diameter of the groove opening is slightly smaller than the maximum diameter of the curved surface of the back plate 4. The back plate 4 can be swung around the contact points.

Further, the back plate 4 is a disc-shaped structure, and the second bearing seat 11 is a split-type semicircular structure.

Further, the active structure includes interconnect's solid fixed ring 10 and third bearing frame 12, gu fixed ring 10 with backplate 4 is connected, backplate 4 gu fixed ring 10 with third bearing frame 12 is the ring structure of coaxial setting, backplate 4 with gu fixed ring 10 forms rolling friction pair, backplate 4 can wind the axis of third bearing frame 12 carries out tilt motion.

The back plate 4, the fixing ring 10 and the third bearing seat 12 are coaxially arranged in a circular ring structure. The inner ring is fixed on the third bearing seat 12, the outer ring of the back plate 4 and the inner ring of the fixing ring 10 are a pair of spherical surfaces which are matched with each other to form a rolling friction pair, and the back plate 4 can do tilting motion in a certain angle range around the axis of the third bearing seat 12.

Further, the back plate 4 is provided with a plurality of slits, which are distributed in a radial direction. The slits are used for positioning when the foils are assembled on the back plate, so that the foils can be uniformly arranged on the back plate.

Further, the flexible structure comprises a plane area, a wedge area and a fixed area which are connected in sequence.

One end of the flat foil 1 is fixedly arranged on the gasket 2, and the other end of the flat foil is freely lapped on the corresponding next wave foil 3. The bump foil 3 and the spacer 2 have a small height difference, generally 50-100 μm, and the flat foil 1 naturally forms a flat area and a wedge area after being mounted.

Example 1

The present embodiment provides a multi-layer thrust foil bearing structure. As shown in fig. 1, 2 and 3, the structure comprises, from top to bottom: the device comprises a flat foil 1, a gasket 2, a bump foil 3, a back plate 4, a fastening screw 5, a pressure plate 6, an elastic washer 7, a movable joint 8 and a bearing seat 9. The flat foil 1, the gasket 2 and the bump foil 3 are of a split structure and have the same number, and the number of the thrust foil bearings is generally 4-8 in a single thrust foil bearing. The flat foil 1, the gasket 2 and the bump foil 3 are fixedly arranged on the back plate 4 from top to bottom in sequence. The back plate 4 is a round thin plate with a smooth surface, the inner ring of the back plate is provided with a round groove along the axial direction, and the diameter of the round groove is the same as the inner diameter of the flat foil 1, the gasket 2 and the wave foil 3. While a number of slits corresponding to the number of flat foils 1 are arranged in the radial direction. The movable joint 8 is a spherical structure with a plane boss, and the lower surface of the back plate 4 is fixedly connected with the boss plane of the movable joint 8 to be used as a carrier of the flat foil 1, the gasket 2 and the wave foil 3. The movable joint 8 is mounted in a spherical hole in the bearing block 9, with the same curvature, around the center of which the movable joint 8 can freely slide. The pressure plate 6, the elastic washer 7 and the bearing seat 9 are coaxially arranged and are fixedly connected through the fastening screw 5. The pressure plate 6 and the bearing block 9 have cooperating locating bosses. Circular hole and swing joint 8 cooperation on the clamp plate 6, the plane boss of swing joint 8 exceeds the upper surface of clamp plate 8, makes to form certain clearance between backplate 4 and the clamp plate 8, and accessible adjustment fastening screw 4 adjusts this clearance. When the bearing works, the movable joint 8 provides axial rigidity for the thrust foil bearing, and meanwhile, the back plate 4 has circumferential and radial degrees of freedom, so that the back plate 4 can freely tilt or swing around the spherical center of the movable joint 8, the adaptability of the thrust foil bearing to the eccentricity of a thrust disc and the misalignment of a rotor can be improved, and the working performance of the gas thrust foil bearing under the conditions of high speed and high load is ensured.

Example 2

The present embodiments provide a thrust foil bearing structure having a dished back plate. As shown in fig. 4, 5 and 6, the structure includes: flat foil 1, spacer 2, bump foil 3, back plate 4 and second bearing seat 11. As in embodiment 1, the flat foil 1, the spacer 2, and the bump foil 3 are of a split structure and have the same number, and the flat foil 1, the spacer 2, and the bump foil 3 are sequentially and fixedly mounted on the back plate 4 from top to bottom. The back plate 4 is a disc-shaped structure, and the lower surface is a curved surface. Like embodiment 1, the inner ring thereof has a circular groove in the axial direction, and a plurality of slits are arranged in the radial direction. The second bearing seats 11 are of a split type semicircular structure, a pair of second bearing seats 11 are concentrically fixed and connected with the back plate 4, grooves matched with the curved surface of the back plate 4 are formed in the second bearing seats 11, the curvature of each groove is larger than that of the back plate, and the diameter of each notch is slightly smaller than the maximum diameter of the curved surface of the back plate. When the bearing works, a certain arc-shaped gap is formed between the back plate 4 and the second bearing seat 11, the arc-shaped gap can freely tilt or swing around a contact point, the axial displacement of the back plate is limited, the adaptability of the thrust foil bearing to the eccentricity of a thrust disk and the misalignment of a rotor can be improved, and the working performance of the gas thrust foil bearing under the conditions of high speed and high load is ensured.

Example 3

The embodiment provides a collar type thrust foil bearing structure. As shown in fig. 7, 8 and 9, the structure includes: flat foil 1, spacer 2, bump foil 3, back plate 4, third bearing seat 12 and fixing ring 10. As in embodiment 1, the flat foil 1, the spacer 2, and the bump foil 3 are of a split structure and have the same number, and the flat foil 1, the spacer 2, and the bump foil 3 are fixedly mounted on the back plate 4 in this order from top to bottom. The back plate 4 has the same inner diameter as the flat foil 1 and has a plurality of slits arranged in the radial direction. The third bearing seat 12, the fixing ring 10 and the back plate 4 are of a ring structure which is coaxially arranged, the back plate fixing ring 10 and the bearing seat 9 are in interference fit, and the outer edge of the third bearing seat 12 is provided with a screw hole for fixing, so that the fixing ring 10 and the third bearing seat 12 are fixed with the shell. The outer ring of the back plate 4 and the inner ring of the fixing ring 10 are a pair of spherical surfaces which are matched with each other to form a rolling friction pair, and the back plate 4 can tilt around the axis of the third bearing seat 12 within a certain angle range.

As shown in fig. 10, the flat foil 1, the spacer 2 and the bump foil 3 provided by the present application are assembled in the following manner: the flat foil 1, the gasket 2 and the bump foil 3 are fixed on the back plate 4 in sequence from bottom to top. The flat section of the bump foil 3 is welded to the back plate 4 and is flush with one end of the slit, the other end of the bump foil 3 being free. One end of the shim 2 is welded to the flat section of the bump foil 3 and is flush with the fixed end. The front edge of the flat foil 1 is welded to the other end of the corresponding gasket 2 and is flush with the other end of the gasket 2, and the other end of the flat foil 1 is freely lapped on the wave arch of the next wave foil 3, namely the directions of the flat foil 1 and the wave foil 3 from the fixed end to the free end are opposite. The structure ensures that the deformation directions of the flat foil 1 and the wave foil 3 along the circumferential direction are opposite when the thrust foil bearing works, and is beneficial to improving the damping of the thrust foil bearing and improving the stability of a bearing-rotor system. Due to the height difference between the spacer 2 and the bump foil 3 in the axial direction, the flat foil 1 naturally forms three parts after the mounting is completed: a fixed zone, a wedge zone, and a planar zone. Wherein the wedge-shaped area is used for generating dynamic pressure effect, and the plane area is a working area of high-pressure lubricating fluid and is used for providing bearing capacity for the rotor. The method has the advantages that the flat foil 1 is not required to be subjected to pre-deformation treatment by an additional stamping die, the operation is simple and convenient, the processing cost is low, and the efficiency is high.

When the bearing-rotor system works normally, the axis of the thrust foil bearing is superposed with the axis of the rotor, and the movable joint 8, the bearing seat 9 or the fixed ring 10 provides enough axial rigidity for the thrust foil bearing, so that the bearing does not generate axial displacement. Once the thrust disk is eccentric or the rotor is not centered, the bearing changes the shape of the lubricating air film, so that the stress on the back plate 4 is unbalanced, and then the back plate 4 freely inclines or swings around the circle center of the bearing seat, so that the lubricating surface of the thrust foil bearing is parallel to the surface of the thrust disk again. Especially, under the condition that the track of the axis of the rotor is complex and the fluctuation is large, the back plate 4 can be automatically and timely adjusted, so that the axis of the bearing is consistent with the axis of the rotor, the lubricating surface of the thrust foil bearing is not in contact with the rotor in advance, and the stability and the reliability of a bearing-rotor system can be improved.

Although the present application has been described above with reference to specific embodiments, those skilled in the art will recognize that many changes may be made in the configuration and details of the present application within the principles and scope of the present application. The scope of protection of the application is determined by the appended claims, and all changes that come within the meaning and range of equivalency of the technical features are intended to be embraced therein.

Claims

1. A thrust foil bearing, characterized by: the flexible structure comprises a flat foil, a gasket and a wave foil assembly which are sequentially connected, the wave foil assembly is arranged on the back plate and comprises a first wave foil and a second wave foil which are sequentially arranged, the first wave foil comprises a first flat section and a first wave arch which are mutually connected, the second wave foil comprises a second flat section and a second wave arch which are mutually connected, the first flat section is connected with the back plate, the second flat section is connected with the back plate, the first flat section is provided with the first gasket, one end of the flat foil, the second gasket and the second flat section are sequentially connected, the first wave arch is free, and the other end of the flat foil is in contact with the first wave arch; the back plate and the movable structure form a kinematic pair, and the back plate can freely incline or swing.

2. The thrust foil bearing of claim 1, wherein: the movable structure is connected with the back plate through a movable joint, the movable structure comprises a pressing plate and a first bearing seat which are connected with each other, one end of the movable joint is connected with the back plate, the other end of the movable joint penetrates through the pressing plate, the other end of the movable joint is arranged in the first bearing seat, and the back plate can freely incline or swing around the movable joint.

3. The thrust foil bearing of claim 2, wherein: an elastic gasket is arranged between the pressing plate and the first bearing seat, and the pressing plate, the elastic gasket and the first bearing seat are connected through fastening screws.

4. The thrust foil bearing of claim 2, wherein: the movable joint is of a spherical structure, the spherical structure comprises a boss, and the plane of the boss is fixedly connected with the back plate.

5. The thrust foil bearing of claim 2, wherein: the pressing plate is of a disc-shaped structure.

6. The thrust foil bearing of claim 1, wherein: the movable structure comprises a second bearing seat, the back plate is of a disc-shaped structure, one side of the disc-shaped structure is a plane, the wave foil assembly is arranged on the plane, the other side of the disc-shaped structure is a curved surface, the curved surface is matched with the second bearing seat, the disc-shaped structure is connected with the second bearing seat through a contact point, and the disc-shaped structure can freely tilt or swing around the contact point.

7. The thrust foil bearing of claim 6, wherein: the back plate is of a disc-shaped structure, and the second bearing seat is of a split type semicircular structure.

8. The thrust foil bearing of claim 1, wherein: the bearing structure comprises a third bearing seat and a movable structure, wherein the third bearing seat is connected with the movable structure, the movable structure comprises a fixing ring and a third bearing seat which are connected with each other, the fixing ring is connected with the back plate, the back plate is of a ring structure which is coaxially arranged with the third bearing seat, the back plate is in rolling friction pair with the fixing ring, and the back plate can wind the axis of the third bearing seat to perform inclined motion.

9. The thrust foil bearing of claim 8, wherein: the back plate is provided with a plurality of slits which are distributed along the radial direction.

10. A thrust foil bearing according to any one of claims 1 to 9, wherein: the flexible structure comprises a plane area, a wedge area and a fixed area which are connected in sequence.