CN117090857A

CN117090857A - Thrust bearing for gas foil

Info

Publication number: CN117090857A
Application number: CN202310902611.4A
Authority: CN
Inventors: 陈振乾; 熊成; 许波
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2023-07-20
Filing date: 2023-07-20
Publication date: 2023-11-21

Abstract

The application discloses a gas foil thrust bearing, which comprises a bearing seat and a gas foil thrust bearing assembly arranged on the bearing seat; the method is characterized in that: the gas foil thrust bearing assembly comprises a top foil, a middle foil and a bottom foil; the middle foil is in surface contact with the bottom foil; the bottom foil is arranged on the bearing seat, the initial contact state of the bottom foil and the bearing seat is line contact, and the loading state is surface contact; the top foil comprises a wedge-shaped foil element, and a start end welding position hole and a terminal end which are respectively arranged at two sides of the wedge-shaped foil element; the starting end welding position hole is fixed on the upper plane of the middle foil, and the terminal end is suspended relative to the upper plane of the middle foil; a plurality of wedge-shaped foil elements are annularly and uniformly distributed on the upper plane of the middle foil; the bottom foil comprises a bottom foil matching ring and an elastic element which is arranged on the lower plane of the bottom foil matching ring and forms a certain inclination angle with the bottom foil matching ring. In the application, the middle foil and the bottom foil are in complete surface contact, which is beneficial to the uniform distribution of the temperature field of the foil structure and prevents the foil from generating uneven thermal deformation when the pneumatic heat is transferred.

Description

Thrust bearing for gas foil

Technical Field

The application relates to the field of rotary machinery, in particular to a gas foil thrust bearing.

Background

At present, due to the excellent characteristics of high running speed, high temperature, low friction resistance, low running cost, small quality and the like of the dynamic pressure gas foil bearing, the dynamic pressure gas foil bearing is widely applied to equipment such as high-speed rotating machinery, high-speed motors, turbine compressors, turbine pumps, gas turbines, turbine generators and the like of aerospace and the like through development and iteration for many years.

Existing gas foil thrust bearing designs typically employ a series of individual plates, sometimes in a non-planar configuration, to provide the spring effect.

Such prior designs not only result in excessively complex manufacturing, but also poor performance due to excessive friction, particularly at low rpm.

In particular, dynamic pressure gas foil thrust bearings typically employ an elastomeric base foil axially supported by a bearing housing; and a top foil, and a force transmitting middle foil. After the rotating thrust disc rotates, a thin fluid layer is formed between the top foil and the rotating thrust disc, and the fluid axially supports the thrust disc, so that a low-friction dynamic pressure air bearing is formed; in addition, the transfer of fluid facilitates heat transfer.

The thrust disc is generally flat and the foil elements are generally wedge-shaped converging in the circumferential direction, such a circumferential surface inclination leading to the creation of a fluid film and an axial lifting effect on the thrust disc.

In this way, the axial load applied by the rotating thrust disc may be transferred through the fluid film, top foil, middle foil and bottom foil to the bearing housing, which provides an equal and opposite axial reaction force to match the axial load applied to the bearing.

The presence of a fluid film in such a force transmission chain provides the possibility of significantly reducing friction losses that may occur due to relative rotation between the surfaces.

Thus, dynamic pressure gas foil thrust bearings may be used in micro gas turbines to overcome the associated impractical use of other conventional types of bearings at high rotational speeds and high operating temperatures.

However, the top foil, the middle foil and the bottom foil are usually in line contact or partial surface contact, so that the temperature distribution of the foil is easily uneven, the top foil is easily subjected to uneven thermal deformation, and a lubricating air film is destroyed.

Disclosure of Invention

The application aims to solve the defects in the prior art and provides a gas foil thrust bearing which can solve the problems.

In order to solve the technical problems, the application adopts the technical method that: the application discloses a gas foil thrust bearing, which comprises a bearing seat and a gas foil thrust bearing assembly arranged on the bearing seat; the method is characterized in that: the gas foil thrust bearing assembly comprises a top foil, a middle foil and a bottom foil; the middle foil is in surface contact with the bottom foil; the bottom foil is arranged on the bearing seat, the initial contact state of the bottom foil and the bearing seat is line contact, and the loading state is surface contact;

the top foil comprises a wedge-shaped foil element, and a start end welding position hole and a terminal end which are respectively arranged at two sides of the wedge-shaped foil element;

the initial end welding position hole is fixed on the middle foil upper plane, and the terminal is suspended relative to the middle foil upper plane; the wedge-shaped foil elements are distributed on the upper plane of the middle foil in an annular manner;

the bottom foil comprises a bottom foil matching ring and an elastic element which is arranged on the lower plane of the bottom foil matching ring and forms a certain inclination angle with the bottom foil matching ring.

Further, the bottom foil matching ring is provided with a plurality of through hole matrixes with circumferences distributed at equal intervals; the elastic element is arranged on one side of the through hole; the length direction of the elastic element is arranged along the circumferential direction of the bottom foil matching ring.

Further, the matrix of through holes includes through holes radially distributed along the bottom foil mating ring and through holes circumferentially distributed along the bottom foil mating ring.

Further, along the circumferential direction of the bottom foil mating ring, two adjacent elastic elements are axially symmetrically arranged.

Further, along the radial direction of the bottom foil matching ring, two adjacent elastic elements are arranged in a central symmetry manner.

Further, the surface of the annular matching surface of the bearing seat is flat but rough.

Further, the middle foil, the bottom foil and the bearing seat are sequentially provided with a middle foil positioning through hole, a bottom foil positioning through hole and a bearing seat positioning through hole which are coaxial and have the same aperture.

Advantageous effects

1. Compared with the prior art, the middle foil and the bottom foil are in complete surface contact, so that even distribution of a foil structure temperature field is facilitated when pneumatic heat is transferred, and uneven thermal deformation of the foil is prevented; the elastic elements of the bottom foil are uniformly distributed, so that the problem of uneven deformation of the foil caused by air film pressure can be solved.

2. The elastic element has an included angle relative to the bottom foil matching ring, so that the foil set has large deformation capacity, and the occurrence of bearing abrasion caused by insufficient foil deformation capacity in the operation process is reduced. Meanwhile, the pre-tightening assembly can be carried out during the rotor assembly, so that the elastic element has certain pre-deformation, the bearing rigidity is improved, and the bearing capacity is improved.

Drawings

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

FIG. 2 is an exploded view of a gas foil thrust bearing of the present application;

FIG. 3 is a schematic view of the structure of the top foil according to the present application;

FIG. 4 is a schematic view showing a specific structure of the middle foil in the present application;

FIG. 5 is a schematic illustration of a specific construction of a midsole foil according to the present application;

FIG. 6 is a schematic top surface view of a midsole foil of the present application;

FIG. 7 is a schematic view of the lower surface of the midsole foil of the present application;

fig. 8 is a schematic view of a specific structure of a bearing housing according to the present application.

Description of the embodiments

The application is described in further detail below with reference to the drawings and the detailed description.

FIGS. 1-7 depict a specific construction of a gas foil thrust bearing comprising a gas foil thrust bearing assembly 100 and a bearing housing 200;

the gas foil thrust bearing assembly 100 includes a top foil 110, a middle foil 120, and a bottom foil 130.

As shown in fig. 1, the wedge foil member 114, the middle foil annular mating ring 122, the bottom foil annular mating ring 132, and the bearing housing annular mating surface 242 are stacked in sequence. Before the bearing works, load is transmitted to the bottom foil annular matching ring 132 through the wedge-shaped foil elements 114 in sequence by the middle foil matching ring 122, the bottom foil matching ring transmits the load to the elastic elements 134, and the included angle between the elastic elements and the bottom foil annular matching ring 132 is reduced after the elastic elements are stressed.

Wherein the surface of the middle foil 120 is flat and the bottom foil mating ring 132 of the bottom foil 130 is flat. The top foil 110 comprises a non-planar configuration, while the middle foil 120 and the bottom foil 130 are planar.

The center positions of the top foil 110, the middle foil 120, the bottom foil 130 and the bearing seat 200 are provided with the same through holes.

The wedge-shaped foil elements 114 may be evenly distributed over the circumference of the intermediate foil annular mating ring 122. The wedge-shaped foil elements 114 are circumferentially arranged along the circumferential direction of the intermediate foil annular mating ring 122, as shown in fig. 3. This periodic distribution, particularly in combination with the foil mating ring 122 and the bottom foil mating ring 132 in the correspondingly distributed force transfer element, facilitates a uniform circumferential load distribution, which helps to prevent any local stress concentrations that may increase wear and tear.

As shown in fig. 3, the top foil 110 adapted to receive a rotating thrust disc comprises a wedge-shaped foil arrangement 114 and a start end solder apertures 113 and a finish end 115, which are provided separately on both sides of the wedge-shaped foil arrangement 114.

The start weld hole 113 is fixed to the middle foil annular mating ring 122, but the end 115 needs to remain free to relieve deformation caused by film pressure or thermal stress.

The top foil 110 comprises a plurality of radially inwardly arranged wedge-shaped foil elements 114. Wedge foil member 114 is configured to provide an axially converging wedge in a circumferential direction. Such circumferential fluctuations may create a fluid film upon rotation of the adjacent thrust disks that serves to axially support the rotating thrust disks.

During start-up and normal operation, the axial force exerted by the rotating thrust disc against the top of the top foil 110 is not constant. This load variation is accommodated in the thrust bearing by providing compliance (i.e., elasticity) in the form of an underlying spring mechanism comprised of elastic elements 134 coupled to the top foil underlying bottom foil 130.

The middle foil 120 includes a middle foil annular mating ring 122 and 4 locating holes 126 as shown in fig. 4.

The intermediate foil annular mating ring 122 may be planar in shape and contact the bottom of the top foil 114. As shown, the middle foil 120 may include a through hole 126 for positioning the middle foil provided on a radially outer edge thereof.

The base foil 130 as shown in fig. 5-7 includes a base foil annular mating ring 132 and a resilient element 134 disposed circumferentially and counterclockwise along the base foil annular mating ring 132. The resilient element 134 may extend circumferentially from the base foil annular mating ring 132.

The middle foil 120 and the bottom foil 130 of the thrust bearing assembly 100 facilitate axial transfer of the axial load generated by the wedge foil elements 114 of the top foil 110. In particular, each circumferentially spaced wedge foil element 114 may be supported by a respective pair of axially overlapping intermediate foil annular mating rings 122 and bottom foil annular mating rings 132.

The overlapping pairs of force elements and elastic elements may comprise circumferential and/or radial offset portions, i.e. the circumferential and/or radial offset portions of the force transfer elements are offset or non-overlapping with the circumferential and/or radial offset portions of the elastic elements.

As shown in fig. 6-7, the bottom foil 130 has a configuration of a bottom foil annular mating ring 132 and a resilient element 134. The elastic element 134 is inclined to the bottom foil annular mating ring 132 at an inclined angle that is controlled to form a fixed angle during processing.

Each spring element 134 may include a circumferentially extending, counter-clockwise support, the spring element 134 being at an angle to the base foil annular mating ring 132θSo as to fully exert the elastic performance of the elastic element.

The bottom foil 130 includes bottom foil locating through holes 246 provided on a radially outer edge thereof for receiving the upper or lower layer plates.

The bottom foil locating through holes 246 correspond to locating holes of the upper layer middle foil 120 and the top foil 110, securely fixing the plates of the thrust bearing assembly 100 together.

The bearing housing 200 includes a housing annular mating surface 242 and a housing locating through hole 246 as shown in fig. 8. The bearing housing annular mating surface 242 is a flat planar surface, but it is necessary to roughen the surface to match the sliding of the elastic element 134 on the surface of the bearing housing annular mating surface 242 when the elastic element 134 is deformed, the roughness being expressed as a coefficient of friction to control the degree of sliding of the elastic element 134.

This axial spring-promoting action of the spring element 134 imparts compliance to the base foil. In this way, the elastic element 134 can be regarded as a cantilever extending circumferentially symmetrically.

Each wedge foil member 114 may be supported by an underlying force transfer member. The force transfer elements include, among other things, wedge foil elements 114, a middle foil annular mating ring 122, a bottom foil annular mating ring 132 and a resilient element 134.

Thus, the load exerted by the rotating thrust disc through the fluid film may be transferred through the wedge foil member 114, past the respective force transfer element, to the respective elastic element 134; this allows the resilient element 134 to slide radially over the bearing housing annular mating surface 242 and deform axially to accommodate the gas film pressure.

The bearing housing annular mating surface 242 may be used to limit the resiliency of the resilient member 134 by contacting the resilient member 134 after a sufficient resiliency of the resilient member 134 has occurred.

The downward axial load on the force transfer element can be transferred through the mating ring 122 to the resilient element 134, which resilient element 134 in turn is in line contact with the bearing housing annular mating surface 242 and is converted from line contact to surface contact upon pretensioning and load application to increase friction.

The layers of foil plates of the gas foil thrust bearing assembly 100 may be stacked such that each wedge foil member 114 is axially supported by a pair of corresponding, axially overlapping force transfer and elastic members 134.

As shown in fig. 1, the top foil 110 is overlaid on the middle foil 120, and the middle foil 120 is overlaid on the bottom foil 130. If the assembly 100 and the housing 200 are combined, the bottom foil 130 is covered on the housing 200.

The specific stacking sequence is as follows: the bottom foil 130 is positioned on the bearing housing 200, the middle foil 120 is positioned on the bottom foil 130, and finally the top foil 110 is positioned on the middle foil 120.

During or after stacking, the plates may be oriented such that the wedge foil elements 114 are axially supported by respective pairs of overlapping force transfer elements and elastic elements 134.

The foil plates are orientable such that each wedge-shaped foil unit 114 overlies a respective force transfer element and such that the force transfer element overlies a respective elastic element 134. In this way, the force transmitted from each wedge foil element 114 can be transmitted via the corresponding force transfer element to the corresponding elastic element 134. The force applied to the resilient element 134 may cause the resilient element 134 to be axially displaced relative to the bottom foil-engaging ring 132. The direction of displacement is axially away from the top foil 110.

The existence of the included angle of the elastic element 134 relative to the bottom foil matching ring 132 enables the foil set 100 to have large deformation capability, and pre-tightening assembly can be performed during rotor assembly, so that the elastic element 134 has certain pre-deformation, bearing rigidity is improved, and bearing capacity is improved.

In some prior art implementations, however, corrugated foil is provided to facilitate compliance, which has a tendency to cause plastic deformation in use; according to an example of the present application, the presently disclosed bulk foil thrust bearing assembly 100 increases the likelihood of preventing such plastic deformation.

In the disclosed example, a gas foil thrust bearing assembly 100 is provided for positioning directly onto the bearing housing 200, which has a minimum number of plates, thus reducing manufacturing complexity and performance variations compared to the case where a greater number of plates are used.

For the prior art, the middle foil 120 and the bottom foil 130 are in complete surface contact, so that the uniform distribution of the temperature field of the foil structure is facilitated and the uneven thermal deformation of the foil is prevented when the pneumatic heat is transferred; the elastic elements 134 of the bottom foil 130 are uniformly distributed, which can solve the problem of uneven deformation of the foil caused by air film pressure. The inclusion of the resilient element 134 in relation to the base foil mating ring 132 provides the foil assembly 100 with a large deformation capability, reducing the occurrence of bearing wear due to insufficient foil deformation capability during operation. Meanwhile, the pre-tightening assembly can be performed during the rotor assembly, so that the elastic element 134 has certain pre-deformation, the bearing rigidity is improved, and the bearing capacity is improved.

While the embodiments provided herein give specific force transfer element and elastic element 134 geometries, the general principles of the present application are applicable to a wide variety of geometries.

The thickness of the middle foil 120 may be greater than the thickness of the bottom foil 130, or alternatively, the thickness of the top foil 110 may be greater, such as by providing a middle foil that is thicker than the bottom foil, preventing performance degradation associated with deformation of the middle foil. The increased thickness of the middle foil helps to evenly distribute the forces to be transferred over a larger working area of the top foil.

The thickness of the top foil 110 may be between 0.075 and 0.175 mm.

The thickness of the middle foil 120 may be between 0.1 and 0.2mm or between 0.15 and 0.25 mm.

The thickness of the bottom foil 130 may be between 0.075 and 0.15 mm.

Each example of the present disclosure may be provided in a high-speed rotary machine including a gas foil thrust bearing according to any example. The use of such a gas foil thrust bearing in a high speed rotating machine results in improved friction loss and heat management and simplified manufacturing, and therefore, performance characteristics of the high speed rotating machine. It should be understood that the examples disclosed herein are not limiting and that numerous modifications and substitutions are possible.

Claims

1. A gas foil thrust bearing comprising a bearing housing (200) and a gas foil thrust bearing assembly (100) disposed on the bearing housing (200); the method is characterized in that: the gas foil thrust bearing assembly (100) includes a top foil (110), a middle foil (120), and a bottom foil (130); the middle foil (120) is in surface contact with the bottom foil (130); the bottom foil (130) is arranged on the bearing seat (200), the initial contact state of the bottom foil (130) and the bearing seat (200) is line contact, and the loading state is surface contact;

the top foil (110) comprises a wedge-shaped foil element (114) and a start end welding position hole (113) and a terminal end (115) which are respectively arranged at two sides of the wedge-shaped foil element (114);

the initial end welding position hole (113) is fixedly arranged on the upper plane of the middle foil (120), and the terminal end (115) is suspended relative to the upper plane of the middle foil (120); the wedge-shaped foil elements (114) are distributed on the upper plane of the middle foil (120) in a ring shape;

the bottom foil (130) comprises a bottom foil matching ring (132) and an elastic element (134) which is arranged on the lower plane of the bottom foil matching ring (132) and forms a certain inclination angle with the bottom foil matching ring (132).

2. A gas foil thrust bearing as claimed in claim 1, wherein: the bottom foil matching ring (132) is provided with a plurality of through hole matrixes distributed at equal intervals on the circumference; one side of the through hole is provided with the elastic element (134); the elastic element (134) is arranged in the length direction along the circumferential direction of the bottom foil mating ring (132).

3. A gas foil thrust bearing as claimed in claim 2, wherein: the matrix of through holes includes through holes radially distributed along the bottom foil mating ring (132) and circumferentially distributed along the bottom foil mating ring (132).

4. A gas foil thrust bearing according to claim 3, wherein: along the circumferential direction of the bottom foil mating ring (132), two adjacent elastic elements (134) are arranged in an axisymmetric manner.

5. The gas foil thrust bearing of claim 4, wherein: along the radial direction of the bottom foil matching ring (132), two adjacent elastic elements (134) are arranged in a central symmetry mode.

6. A gas foil thrust bearing as claimed in claim 1, wherein: the bearing seat annular mating surface (242) of the bearing seat (200) is flat but rough in surface.

7. A gas foil thrust bearing as claimed in claim 1, wherein: the middle foil (120), the bottom foil (130) and the bearing seat (200) are sequentially provided with a middle foil positioning through hole (126), a bottom foil positioning through hole (136) and a bearing seat positioning through hole (246) which are coaxial and have the same aperture.