CN113048145B - Dynamic pressure gas bearing - Google Patents

Abstract

The application provides a dynamic pressure gas bearing, which comprises a bearing sleeve and a plurality of groups of foil groups distributed on the inner side of the bearing sleeve; a plurality of fixing positions are circumferentially distributed on the inner wall of the bearing sleeve, each foil set comprises a first foil and a second foil, the first fixing end of each first foil is fixed on one of the fixing positions and circumferentially extends from the fixing position to the position between the next two fixing positions, and the first free end of each first foil is lapped on the next first foil; each second foil is arranged between the bearing sleeve and the last first foil, the second fixed end of the second foil and the corresponding first fixed end are fixed on the same fixed position, the second foil circumferentially extends from the fixed position to a position between the fixed position and the last fixed position along the direction opposite to the direction of the first foil, and the second free end of the second foil is supported below the last first foil. According to the dynamic pressure gas bearing, through the arrangement of the second foil, the supporting point of the first foil is increased, and the damping characteristic, the running stability and the shock resistance of the dynamic pressure gas bearing are improved.

Description

Hydrodynamic Gas Bearings

Technical Field

The present invention belongs to the technical field of gas bearings, and more specifically, relates to a dynamic pressure gas bearing.

Background Art

Gas bearings can be divided into two categories: static pressure gas bearings and dynamic pressure gas bearings. Compared with static pressure gas bearings, dynamic pressure gas bearings do not require an additional high-pressure gas source and have the advantages of simple structure and small size. Therefore, dynamic pressure gas bearings are widely used in micro gas turbines, micro turbojet engines and other fields.

There is a wedge-shaped gap or other special gaps between the hydrodynamic gas bearing and the rotor. When the rotor rotates, gas dynamic pressure is generated in the gap. The hydrodynamic gas bearing includes a bearing sleeve, which generally has an elastic support structure such as a foil structure to improve the stability of the rotor system. When subjected to unstable loads, the foil structure produces relative sliding due to deformation, thereby generating Coulomb friction. The foil structure can withstand loads in different directions perpendicular to the axis, but because the foil structure has a low bending stiffness, its load-bearing stiffness is low, which affects the stability and service life of the entire hydrodynamic gas bearing.

Summary of the invention

The object of the present invention is to provide a hydrodynamic gas bearing to solve the technical problem of insufficient bearing rigidity of a foil structure in a hydrodynamic gas bearing in the prior art.

To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a dynamic pressure gas bearing is provided, the dynamic pressure gas bearing comprising a bearing sleeve and a plurality of foil groups distributed on the inner side of the bearing sleeve; a plurality of fixed positions are distributed circumferentially on the inner wall of the bearing sleeve, and the number of the fixed positions is equal to the number of the foil groups; each group of the foil groups comprises a first foil and a second foil, the first foil having a first fixed end and a first free end, and the second foil having a second fixed end and a second free end; the first fixed end of each of the first foils is fixed to one of the fixed positions, and extends circumferentially from the fixed position to between the next two fixed positions, and its first free end overlaps the next first foil; each of the second foils is arranged between the bearing sleeve and the previous first foil, the second fixed end of the second foil is fixed to the same fixed position as the corresponding first fixed end, and extends circumferentially from the fixed position in the direction opposite to the first foil to between the fixed position and the previous fixed position, and its second free end is supported under the previous first foil.

Optionally, the first foil abuts against a previous first foil at a first supporting point, the first foil abuts against a next second foil at a second supporting point, and the first foil abuts against a next first foil at a third supporting point;

Wherein, the second supporting point is located between the first supporting point and the third supporting point;

Alternatively, the first supporting point is located between the second supporting point and the third supporting point.

Optionally, there is a first circumferential distance between two adjacent fixing positions, and the first foil covers 1.35 to 1.75 times of the first circumferential distance; the second foil covers 0.35 to 0.75 times of the first circumferential distance.

Optionally, the first foil covers 1.5 times the first circumferential distance; and the second foil covers 0.5 times the first circumferential distance.

Optionally, the first foil is an arc-shaped structure, and the inner diameter and outer diameter of the first foil are both larger than the inner diameter of the bearing sleeve.

Optionally, the first foil is bent in the middle to form an inner step and an outer step, the height of the inner step and the height of the outer step are both adapted to the thickness of the first foil, the first free end of the previous first foil stops at the outer step, and the second free end of the next second foil stops at the inner step.

Optionally, a slot is provided at the fixing position, a first bending portion extends from the first fixing end, a second bending portion extends from the second fixing end, the first bending portion and the second bending portion are respectively disposed in the slot and clamped by a plug.

Optionally, the first fixed end is fixed to the inner wall of the bearing sleeve by hinge, screw connection, riveting, welding or bonding;

The second fixed end is fixed to the inner wall of the bearing sleeve by means of hinge, screw connection, rivet connection, welding or bonding.

Optionally, the width of the bearing sleeve along the axial direction, the width of the first foil along the axial direction, and the width of the second foil along the axial direction are all equal.

Optionally, a surface of the first foil facing away from the bearing sleeve is paved with a wear-resistant material layer.

The beneficial effect of the hydrodynamic gas bearing provided by the present invention is that: compared with the prior art, the hydrodynamic gas bearing of the present invention includes a bearing sleeve and multiple foil groups, each foil group includes a first foil and a second foil, the first foil and the second foil extend circumferentially in opposite directions, and the free end of each first foil is overlapped on the next first foil, and the free end of each second foil is supported under the previous first foil, so that each first foil can be supported not only by the next first foil, but also by the next second foil, thereby increasing the supporting points of the first foil, increasing the bending stiffness of the first foil, and thereby improving the supporting stiffness of the entire hydrodynamic gas bearing, and improving the damping property of the hydrodynamic gas bearing, and improving the motion stability and service life of the hydrodynamic gas bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a perspective schematic diagram of a hydrodynamic gas bearing provided by an embodiment of the present invention;

FIG2 is an exploded schematic diagram of a hydrodynamic gas bearing provided in an embodiment of the present invention;

FIG3 is an axial schematic diagram of a hydrodynamic gas bearing provided in an embodiment of the present invention;

FIG4 is an axial schematic diagram of the hydrodynamic gas bearing in FIG3 without each second foil;

FIG5 is a schematic structural diagram of the first foil in FIG3 ;

FIG6 is a schematic diagram of the structure of the second foil in FIG3 ;

FIG7 is a schematic structural diagram of the bearing sleeve in FIG3 ;

FIG8 is an axial schematic diagram of a hydrodynamic gas bearing provided by another embodiment of the present invention;

FIG9 is a schematic diagram of the installation of the first foil and the second foil in FIG8 ;

FIG. 10 is a schematic structural diagram of the first foil in FIG. 8 .

Among them, the reference numerals in the figure are:

200-rotor; 10-bearing sleeve; 20-foil group; 30-block; 11-fixed position; 12-slot; 21-first foil; 22-second foil; 211-first fixed end; 212-first free end; 213-inner step; 214-outer step; 215-first bending portion; 221-second fixed end; 222-second fixed end; 223-second bending portion; P-first gap; O1-first supporting point; O2-second supporting point; O3-third supporting point; L1-first circumferential distance.

DETAILED DESCRIPTION

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

The hydrodynamic gas bearing provided by the present invention is now described.

Please refer to FIG1 , the hydrodynamic gas bearing includes a bearing sleeve 10 and eight foil groups 20. The bearing sleeve 10 is cylindrical, and the eight foil groups 20 are evenly distributed on the inner side of the bearing sleeve 10 along the circumferential direction, and when working, they are held between the rotor 200 and the bearing sleeve 10 to improve the stability of the operation between the rotor 200 and the bearing sleeve 10. It can be understood that in the embodiment of the present invention, according to the specific radial size of the bearing sleeve 10 and the actual supporting strength of the foil group 20, four, six, nine or more foil groups 20 can also be set on the inner side of the above-mentioned bearing sleeve 10, and this is not the only limitation here.

Eight fixing positions 11 are distributed on the inner wall of the bearing sleeve 10 along the circumferential direction. The number of the fixing positions 11 is equal to the number of the foil groups 20 , that is, the number of the fixing positions 11 changes with the change of the number of the foil groups 20 .

Please refer to FIG. 2 and FIG. 3 , each foil set 20 includes a first foil 21 and a second foil 22 . The first foil 21 and the second foil 22 are both cantilevered sheet structures. The first foil 21 has a first fixed end 211 and a first free end 212 , and the second foil 22 has a second fixed end 221 and a second free end 222 .

Please refer to FIG4, which is a schematic diagram of the installation of the bearing sleeve 10 and each first foil 21. The first fixed end 211 of each first foil 21 is fixed to one of the fixed positions 11, and extends counterclockwise from the fixed position 11 to between the next two fixed positions 11, and its first free end 212 overlaps the next first foil 21. As can be seen from FIG4, a first gap P is formed between each first foil 21 and the bearing sleeve 10, and the first gap P is below the area of the converging wedge-shaped gap between the first foil 21 and the rotor 200, so the supporting strength of the first foil 21 in this area is relatively weak.

Please refer to FIG3, which is a schematic diagram of the installation of the bearing sleeve 10, each first foil 21 and each second foil 22. The present application supports the first foil 21 by arranging a second foil 22 in each first gap P. Specifically, each second foil 22 is arranged between the bearing sleeve 10 and the previous first foil 21, and the second fixed end 221 of the second foil 22 and the first fixed end 211 of the corresponding first foil 21 are fixed to the same fixed position 11, and extend circumferentially from the fixed position 11 in the opposite direction (i.e., clockwise) to between the fixed position 11 and the previous fixed position 11, and the second free end 222 is supported under the previous first foil 21. As can be seen from the above, for each first foil 21, its first free end 212 can be overlapped on the next first foil 21, and the suspended part of the first foil 21 can also be supported by the second foil 22. It can be understood that in other embodiments of the present application, in the same foil group 20, the first foil 21 may extend in the clockwise circumferential direction, and the second foil 22 may extend in the counterclockwise circumferential direction, which is not the only limitation here.

During the actual operation of the hydrodynamic gas bearing, air film pressure is formed between the multiple wedge-shaped gaps formed between the rotor 200 and the first foil 21, and the air film gaps of each wedge-shaped gap will vary with the size and direction of the load. Due to the symmetry of the structure, the hydrodynamic gas bearing with multiple first foils 21 can withstand loads in various directions perpendicular to the axis. When the bearing is under load, the first foil 21 is deformed by the air film pressure. Since the traditional hydrodynamic gas bearing has only one layer of the first foil 21, the first gap P between the first foil 21 and the bearing sleeve 10 has no support, so the support stiffness of the first foil 21 is small, resulting in a small load-bearing capacity. In the hydrodynamic gas bearing of the present invention, the second foil 22 is located below the area of the converging wedge-shaped gap between the first foil 21 and the rotor 200, which can reduce the deformation of the pressure area of the first foil 21, thereby increasing the support stiffness.

The hydrodynamic gas bearing provided by the present invention includes a bearing sleeve 10 and multiple foil groups 20, each foil group 20 includes a first foil 21 and a second foil 22, the first foil 21 and the second foil 22 extend circumferentially in opposite directions, and the free end 211 of each first foil 21 is overlapped on the next first foil 21, and the free end 221 of each second foil 22 is supported under the previous first foil 21, so that each first foil 21 can be supported not only by the next first foil 21, but also by the next second foil 22, so that the supporting points of the first foil 21 are increased, so that the mutual contact points between the foils are increased, thereby improving the damping characteristics of the hydrodynamic gas bearing, and improving the stability and impact resistance of the hydrodynamic gas bearing during operation.

In the present embodiment, please refer to FIG. 3 , a first supporting point O1 is abutted between the first foil 21 and the previous first foil 21 , a second supporting point O2 is abutted between the first foil 21 and the next second foil 22 , and a third supporting point O3 is abutted between the first foil 21 and the next first foil 21 ; wherein the second supporting point O2 is located between the first supporting point O1 and the third supporting point O3, that is, the position where the first foil 21 supports the previous first foil 21 is close to the first fixed end 211 , thereby enhancing the supporting strength and supporting stability of the first foil 21 to the previous first foil 21 , and the supporting position of the second foil 22 to the first foil 21 is close to the approximate middle position of the first foil 21 , that is, the position where the supporting strength of the first foil 21 is the weakest. In other words, the second foil 22 is fully utilized, so that the supporting effect of the second foil 22 is optimized. It can be understood that in other embodiments of the present invention, according to the specific circumferential length of the first foil 21, the first supporting point O1 may also be located between the second supporting point O2 and the third supporting point O3, which is not the only limitation herein.

The longer the circumferential length of the first foil 21 is, the weaker its supporting strength is, and the shorter the circumferential length of the first foil 21 is, the less the overlapping part between it and the adjacent first foil 21 is, and the weaker its supporting strength to the adjacent first foil 21 is, so the circumferential length of the first foil 21 is particularly important. In this embodiment, please refer to FIG. 3, there is a first circumferential distance L1 between two adjacent fixed positions 11, and the first foil 21 covers 1.5 times the first circumferential distance L1, that is, the first foil 21 extends from one fixed position 11 to the next fixed position 11, and exceeds 0.5 times the first circumferential distance L1 of the next fixed position. In this way, not only can it be ensured that the two adjacent first foils 21 can overlap 0.5 times the first circumferential distance L1, but also the circumferential length of the first foil 21 is moderate, which can ensure its own supporting strength. It can be understood that in other embodiments of the present application, the first foil 21 can also cover 1.35 times, 1.4 times, 1.6 times and 1.75 times the first circumferential distance L1. As long as the first foil 21 covers the first circumferential distance L1 within the range of 1.35 to 1.75, the supporting strength of the first foil 21 can be guaranteed, and no sole limitation is made here.

The longer the circumferential length of the second foil 22 is, the weaker its own supporting strength is, and the weaker its supporting strength to the first foil 21 is, and the shorter the circumferential length of the second foil 22 is, the supporting position of the first foil 21 is not the position where the supporting strength of the first foil 21 is the weakest, that is, the second foil 22 does not play the supporting effect as it should, so the circumferential length of the second foil 22 is particularly important. In this embodiment, the second foil 22 covers 0.5 times the first circumferential distance L1, that is, the second foil 22 extends 0.5 times the first circumferential distance L1 in the reverse direction from the fixed position 11, so that the second foil 22 just supports the weakest position of the first foil 21, and the supporting strength of the second foil 22 is higher, and the supporting effect on the first foil 21 is better. It can be understood that in other embodiments of the present invention, the second foil 22 can also cover 0.35 times, 0.4 times, 0.6 times and 0.75 times the first circumferential distance L1. As long as the second foil 22 covers the first circumferential distance L1 in the range of 0.35 to 0.75, the supporting strength of the first foil 21 can be guaranteed, and no sole limitation is made here.

Please refer to FIG. 6 . The second foil 22 is an arc-shaped structure, and its inner diameter can be greater than, less than or equal to the inner diameter of the bearing sleeve 10 .

In this embodiment, please refer to Figures 4 and 5. The first foil 21 is an arc sheet structure. The first foil 21 has a first cylindrical surface and a second cylindrical surface. The first cylindrical surface faces the inner wall of the bearing sleeve 10, and the second cylindrical surface faces away from the inner wall of the bearing sleeve 10. The diameters of the first cylindrical surface and the second cylindrical surface are both larger than the inner diameter of the bearing sleeve 10. In this way, when the first fixed end 211 is fixed to the fixed position 11, the first free end 212 can be tilted to support the rotor 200.

In another embodiment of the present invention, please refer to Figures 8 to 10, the first foil 21 is bent in the middle to form an inner step 213 and an outer step 214, the height of the inner step 213 and the height of the outer step 214 are both adapted to the thickness of the first foil 21, the first free end 212 of the previous first foil 21 stops at the outer step 214, and the second free end 222 of the next second foil 22 stops at the inner step 213, that is, the first supporting point O1 and the second supporting point O2 are respectively located on both sides of the step. Specifically, the first foil 21 includes two sections of circular arc sheet structures, which are connected along the busbar and bent into a step-like shape at the connection. The first free end 212 of the previous first foil 21 overlaps with the first foil 21 at a position close to the outer step 214 but cannot cross the outer step 214. Therefore, the contact surface between the first foil 21 and the rotor 200 has a smoother transition at the overlap of the first foil 21. The first foil 21 is bent in the middle part, so that the transition of the overlap of the first foil 21 is smoother, and the air film gap between the rotor 200 and the first foil 21 is more evenly distributed, which also improves the bearing capacity of the first foil 21 to a certain extent.

In this embodiment, please refer to FIG. 3 and FIG. 7 , eight slots 12 are distributed on the inner side wall of the bearing sleeve 10, and the number of the slots 12 is equal to the number of the fixing positions 11. The slots 12 are opened at the fixing positions 11, and the slots 12 are U-shaped and open toward the center of the bearing sleeve 10. The slots 12 pass through the bearing sleeve 10 along the bearing. A first bending portion 215 extends from the first fixing end 211, and the first bending portion 215 extends toward the slot 12, and the bending angle of the first bending portion 215 is slightly greater than 90°. A second bending portion 223 extends from the second fixing end 221, and the second bending portion 223 extends toward the slot 12, and the bending angle of the second bending portion 223 is slightly greater than 90°. The first bending portion 215 and the second bending portion 223 are respectively clamped in the slot 12 and clamped by the plug 30. In this embodiment, the first bending portion 215 and the second bending portion 223 are tightly plugged into the slot 12 by the plugging block 30 , thereby achieving the installation of the first foil 21 and the second foil 22 . The structure is simple and the installation is convenient.

Specifically, the slot 12 is processed by wire cutting and other processes, the width and depth of the slot 12 are both 2 to 3 mm, and the plug 30 is in the shape of a rectangular parallelepiped. During installation, the first bent portion 215 and the second bent portion 223 are respectively pressed against the two opposite inner walls of the slot 12 along the circumferential direction, and then the plug 30 is inserted between the first bent portion 215 and the second bent portion 223 to fix the first bent portion 215 and the second bent portion 223.

It can be understood that in other embodiments of the present invention, the first fixed end 211 can also be fixed to the inner wall of the bearing sleeve 10 by means of hinge, screw connection, rivet riveting, welding or bonding. Similarly, the second fixed end 221 can also be fixed to the inner wall of the bearing sleeve 10 by means of hinge, screw connection, rivet riveting, welding or bonding, which is not limited here.

In this embodiment, please refer to Figure 1, the axial width of the bearing sleeve 10, the axial width of the first foil 21 and the circumferential width of the second foil 22 are all equal. In this way, the supporting strength of the first foil 21 and the second foil 22 can be evenly distributed along the axial direction, ensuring the stable operation of the hydrodynamic gas bearing.

In this embodiment, a wear-resistant material layer is provided on the surface of the first foil 21 facing away from the bearing sleeve 10. The wear-resistant material layer makes the first foil 21 more wear-resistant to the rotor 200 and has a longer service life during the rotation of the rotor 200.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A hydrodynamic gas bearing, characterized in that it comprises a bearing sleeve and a plurality of foil groups distributed on the inner side of the bearing sleeve; a plurality of fixing positions are distributed circumferentially on the inner wall of the bearing sleeve, and the number of the fixing positions is equal to the number of the foil groups; each group of the foil groups comprises a first foil and a second foil, the first foil having a first fixed end and a first free end, and the second foil having a second fixed end and a second free end; the first fixed end of each of the first foils is fixed to one of the fixing positions, and extends circumferentially from the fixing position to between the next two fixing positions, and its first free end overlaps the next first foil; each of the second foils is arranged between the bearing sleeve and the previous first foil, the second fixed end of the second foil is fixed to the same fixing position as the corresponding first fixed end, and extends circumferentially from the fixing position in the opposite direction to the first foil to between the fixing position and the previous fixing position, and its second free end is supported under the previous first foil; The first foil abuts against the previous first foil at a first supporting point, the first foil abuts against the next second foil at a second supporting point, and the first foil abuts against the next first foil at a third supporting point; Wherein, the second supporting point is located between the first supporting point and the third supporting point; Alternatively, the first supporting point is located between the second supporting point and the third supporting point; There is a first circumferential distance between two adjacent fixing positions, and the first foil covers 1.35 to 1.75 times of the first circumferential distance; the second foil covers 0.35 to 0.75 times of the first circumferential distance. 2 . The hydrodynamic gas bearing according to claim 1 , wherein the first foil covers 1.5 times the first circumferential distance; and the second foil covers 0.5 times the first circumferential distance. 3. The hydrodynamic gas bearing according to claim 1 or 2, characterized in that the first foil is an arc-shaped sheet structure, and the inner diameter and outer diameter of the first foil are both larger than the inner diameter of the bearing sleeve. 4. The hydrodynamic gas bearing according to claim 1 or 2 is characterized in that the first foil is bent in the middle to form an inner step and an outer step, the height of the inner step and the height of the outer step are both adapted to the thickness of the first foil, the first free end of the previous first foil stops at the outer step, and the second free end of the next second foil stops at the inner step. 5. The hydrodynamic gas bearing according to claim 1 or 2 is characterized in that a slot is provided at the fixing position, a first bending portion extends from the first fixing end, a second bending portion extends from the second fixing end, the first bending portion and the second bending portion are respectively clamped in the slot and clamped by a plug block. 6. The dynamic pressure gas bearing according to claim 1 or 2, characterized in that the first fixed end is fixed to the inner wall of the bearing sleeve by hinge, screw connection, riveting, welding or bonding; The second fixed end is fixed to the inner wall of the bearing sleeve by means of hinge, screw connection, rivet connection, welding or bonding. 7. The hydrodynamic gas bearing according to claim 1 or 2, characterized in that the width of the bearing sleeve along the axial direction, the width of the first foil along the axial direction, and the width of the second foil along the axial direction are all equal. 8. The hydrodynamic gas bearing according to claim 1 or 2, characterized in that a wear-resistant material layer is laid on a surface of the first foil facing away from the bearing sleeve.