An axially variable clearance gas dynamic pressure bearing

Abstract

The present invention relates to the technical field of gas dynamic pressure bearings, and provides an axially variable clearance gas dynamic pressure bearing, including: a top foil, a bearing support structure, and a bearing sleeve; wherein, the bearing support structure is composed of a plurality of X-shaped beams distributed circumferentially and lapped in sequence, the X-shaped beam is formed by the intersection of two straight beams, the straight beam has a certain angle with the bearing axis direction, and this angle makes the distance between the straight beam and the rotor shaft first decrease and then increase along the straight beam direction. The middle part of the bearing support structure contacts the top foil first, and the end part does not contact the top foil. The top foil has an initially axially varying air film clearance. One end of the X-shaped beam is fixed in the groove of the bearing sleeve, and the other end is free. The latter X-shaped beam supports the former X-shaped beam; one end of the top foil is fixed on the bearing sleeve, and the other end is freely lapped on the bearing support structure. The direction from the free end to the fixed end of the top foil is the same as the direction from the free end to the fixed end of the X-shaped beam. The deformation of the top foil between the straight beams of the adjacent X-shaped beams is less than the deformation of the top foil between the two straight beams, forming a concave deformation with a certain angle with the rotor axis, having the effect of "gas accumulation" similar to that of a herringbone-grooved bearing, and solving the technical problems of bearing end wear and weak load-carrying capacity caused by the uneven air film clearance with a large middle and small ends in the existing foil gas dynamic pressure bearing.

Description

Technical Field

[0001] The invention relates to the technical field of hydrodynamic bearings, and in particular to an axial variable-clearance gas hydrodynamic bearing. Background Art

[0002] The traditional foil gas hydrodynamic bearing consists of a top foil, an elastic foil and a bearing sleeve. The top foil and the dynamic pressure gas film surrounding the rotor are used to keep the rotor in a suspended state. The elastic foil supports the top foil to provide damping and vibration deformation space for the rotor system, giving the rotor system the advantages of oil-free lubrication, high speed, and allowable micro-vibration. It is widely used in high-speed rotating mechanical equipment such as fuel cell air compressors, air cycle machines, blowers, micro gas turbines and turbojet engines.

[0003] The top foil and elastic foil of the traditional foil gas dynamic pressure bearing are made of a flat thin plate pressed by a mold, and its structure has axial consistency. As the speed of the rotor increases, the rotor will drive the surrounding gas into the convergence domain surrounded by the rotor surface and the top foil surface, the gas speed decreases and forms a high-pressure gas film, and the high-pressure gas suspends the rotor load, radially moves the top foil and the elastic foil, and gradually increases the gas film gap. However, the gas film at the end of the bearing is connected to the ambient gas, and the gas film boundary effect occurs, resulting in a "parabolic" distribution of the gas film pressure along the axial direction of the bearing, which is large in the middle and small at both ends. This causes the top foil and elastic foil with axial consistency to have large deformation in the middle and small deformation at the axial ends, making the distance between the axial ends of the top foil and the elastic foil and the rotor very small. When the rotor vibrates or the load is large, the top foil end is prone to wear, shortening the service life of the bearing. In addition, the axially unevenly distributed high-pressure gas film will reduce the bearing capacity. Summary of the invention

[0004] In view of the above technical deficiencies, the present application provides an axial variable clearance gas dynamic pressure bearing to solve the technical problems of the existing foil gas dynamic pressure bearings, which have large uneven air film gaps in the middle and small gaps at both ends, leading to wear on the bearing ends and weak bearing capacity. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0005] To achieve the above technical objectives, the present invention provides the following technical solutions: an axial variable clearance gas dynamic pressure bearing, consisting of a top foil, a bearing support structure, and a bearing sleeve; wherein the bearing support structure is composed of a plurality of X-shaped beams distributed along the circumferential direction, the X-shaped beam is formed by the intersection of two straight beams, the X-shaped beams distributed along the circumferential direction are overlapped in sequence, one end is fixed in the groove of the bearing sleeve, and the other end is free, and the rear X-shaped beam supports the front X-shaped beam; the top foil is an arc-shaped thin plate, one end of which is fixed on the bearing sleeve, and the other end is freely overlapped on the bearing support structure.

[0006] The bearing support structure is formed by a plurality of the X-shaped beams distributed circumferentially and overlapping in sequence. The X-shaped beam is cut out of a whole thin plate by wire cutting and laser cutting to form two intersecting straight beams. The straight beam has an angle with the bearing axis direction, and this angle makes the distance between the straight beam and the rotor shaft decrease first and then increase along the straight beam direction. One end of the X-shaped beam is fixed on the bearing sleeve, and the other end is freely lapped on the adjacent X-shaped beam.

[0007] The top foil is formed by bending a whole thin plate. One end is fixed on the bearing sleeve, and the other end is freely lapped on the bearing support structure. The direction from the free end to the fixed end of the top foil is the same as the direction from the free end to the fixed end of the X-shaped beam. The top foil supported by a plurality of the X-shaped beams deforms under load. The deformation of the top foil between the straight beams of the adjacent X-shaped beams is less than the deformation of the top foil between the two straight beams, forming a concave deformation with an angle with the rotor axis, having the effect of "gas accumulation" similar to that of a herringbone-grooved bearing.

[0008] Preferably, the bearing support structure is composed of a plurality of double X-shaped beams formed by connecting a first X-shaped beam and a second X-shaped beam. The double X-shaped beams are distributed circumferentially and overlap in sequence. The previous double X-shaped beam is supported by the next double X-shaped beam. Among them, the first straight beam and the fourth straight beam of the first X-shaped beam of the previous double X-shaped beam are respectively inserted between the third straight beam and the fourth straight beam, and between the first straight beam and the second straight beam of the next double X-shaped beam, or the third straight beam and the fourth straight beam, and the first straight beam and the second straight beam of the previous double X-shaped beam respectively surround the second straight beam and the third straight beam of the second X-shaped beam of the next double X-shaped beam.

[0009] Preferably, the bearing support structure is formed by overlapping a plurality of reticulated beam structures composed of the X-shaped beams in sequence. The local X-shaped beams of the previous reticulated beam structure are inserted into the diamond-shaped holes of the next reticulated beam structure to form multi-node contacts. The axial ends of the reticulated beam structure are supported by the central part of the reticulated beam structure, so that the axial ends of the reticulated beam structure are in a cantilever state, and its structural stiffness is lower than that of the central part of the reticulated beam structure. After the bearing support structure is loaded, the top foil obtains the effect of the same axial clearance.

[0010] Due to the adoption of the above technologies, the present invention has the following positive effects compared with the prior art: An axially variable clearance gas dynamic pressure bearing of the present invention structurally includes a top foil, a bearing support structure, and a bearing sleeve; among them, the bearing sleeve is used to fix and support the top foil and the bearing support structure. The top foil is arc-shaped and forms upper and lower interfaces surrounding the high-pressure gas film with the rotor surface. The bearing support structure is composed of several straight X-shaped beams, which play a supporting role for the top foil. The two straight beams of the X-shaped beam form an angle with the axis of the circular rotor. This angle causes the distance between the straight beam and the rotor shaft to first decrease and then increase along the direction of the straight beam. The bearing support structure supports the top foil, and its middle part contacts the top foil first, while the ends do not contact the top foil, resulting in a bearing structure with large stiffness in the middle and small stiffness at both ends. The top foil has an initially axially variable gas film clearance, ensuring that the axial clearance between the top foil and the bearing support structure is the same after deformation, and solving the technical problems of bearing end wear and weak load-bearing capacity caused by the uneven gas film clearance with large middle and small ends in the existing foil gas dynamic pressure bearings. Description of the Drawings

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 An exploded view of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0013] Figure 2 A front view of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0014] Figure 3 A partially enlarged view of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0015] Figure 4 A schematic diagram of the X-shaped beam structure of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0016] Figure 5 A schematic diagram of the bearing sleeve of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0017] Figure 6 A schematic diagram of the axial dimension change of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0018] Figure 7 An exploded view of a modified bearing 1 of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0019] Figure 8 Front view of the modified bearing 1 of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0020] Figure 9 Schematic diagram of a double X-beam structure of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0021] Figure 10 Partial view of the modified bearing 1 of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0022] Figure 11 Exploded view of the modified bearing 2 of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0023] Figure 12 Schematic diagram of a mesh beam structure of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0024] Figure 13 Schematic diagram of a mesh beam structure of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0025] Figure 14 Partial schematic view of the modified bearing 2 of an axially variable clearance gas dynamic pressure bearing provided by an embodiment of the present invention.

[0026] Among them, the reference signs of each drawing in the figure: 1 - top foil, 2 - bearing support structure, 3 - bearing sleeve, 21 - X-beam, 201, 202 - straight beams of the X-beam, 31 - groove, 41 - double X-beam, 51 - mesh beam structure, 401 - first X-beam, 402 - second X-beam, 4101 - first straight beam of the double X-beam, 4102 - second straight beam of the double X-beam, 4103 - third straight beam of the double X-beam, 4104 - fourth straight beam of the double X-beam. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other implementation manners obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope protected by the present invention.

[0028] In the description of the present invention, it should be noted that unless otherwise specified, "several" and "multiple" mean two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", "first", "second", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0029] In the description of the present invention, it should be noted that unless otherwise specified, the term "preload" should be understood in a broad sense, that is, the air film thickness is uneven in the radial direction of the bearing. For example, when the bearing structure is installed, a preload is applied in advance, and the effect formed during the operation of the bearing is the same as the preload applied in advance. For those of ordinary skill in the art, the specific meaning of the above terms in the present invention can be understood according to specific circumstances.

[0030] The axial variable clearance gas dynamic pressure bearing provided by the embodiments of the present application will now be described.

[0031] As Figures 1 to 5 shown, the axial variable clearance gas dynamic pressure bearing includes a top foil (1), a bearing support structure (2), and a bearing sleeve (3).

[0032] As a specific implementation, as Figures 1 - 6 shown, the bearing support structure (2) is formed by several X-shaped beams (21) distributed circumferentially and overlapping in sequence. The X-shaped beam (21) is composed of two straight beams (201, 202) with intersecting cuts made by wire cutting and laser cutting from a whole thin plate. Both straight beams (201, 202) have an angle with the bearing axis direction, and this angle causes the distance between the straight beams (201, 202) and the rotor shaft to first decrease and then increase along the direction of the straight beams (201, 202). The distance at the intersection of the two straight beams (201, 202) from the rotor is the smallest, and the external dimension L2 is greater than L1. One end of the X-shaped beam (21) is fixed in the groove (31) of the bearing sleeve (3) or welded to the inner surface of the bearing sleeve (3), and the other end is freely lapped on the adjacent X-shaped beam (21). The free ends of the two straight beams (201, 202) are in a cantilever state after being supported by the adjacent X-shaped beam. When the loaded top foil (1) presses the straight beams (201, 202), it will sequentially press on the straight beams of multiple circumferentially adjacent X-shaped beams, obtaining a variable support stiffness.

[0033] As Figures 1 - 3As shown, the top foil (1) is formed by bending a whole thin plate. One end is fixed to the bearing sleeve (3), and the other end freely overlaps on the bearing support structure (2). The direction from the free end to the fixed end of the top foil (1) is the same as the direction from the free end to the fixed end of the X-shaped beam (21). The top foil (1) supported by several X-shaped beams (21) deforms under load. The deformation amount of the top foil (1) on the straight beams (201, 202) of adjacent X-shaped beams (21) is less than the deformation of the top foil (1) between the two straight beams (201, 202). Due to the angle between the straight beams (201, 202) and the rotor axis, the top foil has a concave deformation with an angle to the rotor axis, having an effect similar to the "gas accumulation" of a herringbone-grooved bearing.

[0034] As Figures 7 - 10 shown, as an alternative embodiment, the bearing support structure (2) is composed of a double X-shaped beam (41) formed by connecting several first X-shaped beams (401) to a second X-shaped beam (402). The double X-shaped beams (41) are circumferentially distributed and overlap in sequence. The previous double X-shaped beam (41) is supported by the next double X-shaped beam. Among them, the first straight beam (4101) and the fourth straight beam (4104) of the first X-shaped beam (401) of the previous double X-shaped beam (41) are respectively inserted between the third straight beam (4103) and the fourth straight beam (4104), and between the first straight beam (4101) and the second straight beam (4102) of the next double X-shaped beam (41), or the third straight beam (4103) and the fourth straight beam (4104), the first straight beam (4101) and the second straight beam (4102) of the previous double X-shaped beam (41) respectively surround the second straight beam (4102) and the third straight beam (4103) of the second X-shaped beam (402) of the next double X-shaped beam (41).

[0035] As Figures 11 - 14 shown, as an alternative embodiment, the bearing support structure (2) is formed by overlapping a reticular beam structure (51) composed of several X-shaped beams in sequence. A single reticular beam structure is obtained by laser cutting a whole thin plate and is regarded as composed of multiple X-shaped beams distributed circumferentially and axially. The local X-shaped beam of the previous reticular beam structure (51) is inserted into the diamond-shaped hole of the next reticular beam structure (51). The cross straight beams of the previous local X-shaped beam are supported by the cross straight beams of the next local X-shaped beam to form multi-node contact; the middle part of the reticular beam structure (51) is supported by the fixed end of the reticular beam structure (51) and the next local X-shaped beam together. The axial end of the reticular beam structure (51) is supported by the central part of the reticular beam structure (51), so that the axial end of the reticular beam structure (51) is in a cantilever state, and its structural stiffness is lower than that of the central part of the reticular beam structure (51), avoiding the technical problem that the gaps at both ends of the top foil (1) and the bearing support structure (2) are small after being loaded, and obtaining the effect of the same axial gap.

[0036] As an alternative embodiment, straight beams at local positions of the reticulated beam structure (51) are added or removed during the processing to increase or decrease the local stiffness.

[0037] As an alternative embodiment, the X-shaped beam (21) is a beam structure of a shape that constitutes the bearing support structure (2), and is replaced by a triangular structure, a rectangular structure, a V-shaped structure, or an arc-shaped structure.

[0038] As an alternative embodiment, the bearing support structure (2) is sequentially formed by overlapping a plurality of X-shaped beams (21), double X-shaped beams (41), or reticulated beam structures (51) distributed axially or circumferentially. The plurality of X-shaped beams (21), double X-shaped beams (41), or reticulated beam structures (51) are evenly distributed or unevenly distributed. The bearing support structure (2) is formed by overlapping a plurality of X-shaped beams (21), double X-shaped beams (41), or reticulated beam structures (51) radially and then distributing them axially or circumferentially with radial overlap or radial misalignment overlap.

[0039] The above description is only a preferred embodiment of the present invention and is not a limitation of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, and modifications made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An axial variable clearance gas dynamic pressure bearing, characterized in that: include: A top foil (1), a bearing support structure (2), and a bearing sleeve (3); wherein the bearing support structure (2) is composed of a plurality of X-shaped beams (21) distributed along the circumferential direction and overlapped in sequence, the X-shaped beam (21) is cut from a whole thin plate by warp cutting and laser cutting to form two intersecting straight beams (201, 202), the two straight beams (201, 202) have an angle with the bearing axis direction, the X-shaped beams (21) distributed along the circumferential direction are overlapped in sequence, the angle makes the distance between the two straight beams (201, 202) and the rotor shaft decrease first and then increase along the direction of the two straight beams (201, 202), one end of the X-shaped beam (21) is fixed in the groove (31) of the bearing sleeve (3), and the other end is freely overlapped On adjacent X-shaped beams (21); the top foil (1) is formed by bending a whole thin plate, one end of which is fixed on the bearing sleeve (3) and the other end of which is freely overlapped on the bearing support structure (2); the direction from the free end of the top foil (1) to the fixed end is the same as the direction from the free end of the X-shaped beam (21) to the fixed end; the top foil (1) supported by a plurality of X-shaped beams (21) deforms after being loaded; the deformation of the top foil (1) between two straight beams (201, 202) of adjacent X-shaped beams (21) is smaller than the deformation of the top foil (1) between the two straight beams (201, 202), forming a concave deformation with an angle with the rotor axis, and having the effect of gathering air in a herringbone grooved bearing.

2. The axial variable clearance gas dynamic pressure bearing according to claim 1, characterized in that: The bearing support structure (2) is composed of a double X-shaped beam (41) composed of a plurality of first X-shaped beams (401) connected to a second X-shaped beam (402), wherein the double X-shaped beams (41) are distributed along the circumferential direction and overlapped in sequence, wherein a preceding double X-shaped beam (41) is supported by a succeeding double X-shaped beam, wherein a first straight beam (4101) and a fourth straight beam (4104) of the first X-shaped beam (401) of the preceding double X-shaped beam (41) are respectively inserted into the succeeding double X-shaped beam (41). ), between the third straight beam (4103) and the fourth straight beam (4104) of the double X-shaped beam (4102), between the first straight beam (4101) and the second straight beam (4102), or the third straight beam (4103) and the fourth straight beam (4104) of the first double X-shaped beam (41), the first straight beam (4101) and the second straight beam (4102) of the first double X-shaped beam (41) respectively surround the second straight beam (4102) and the third straight beam (4103) of the second X-shaped beam (402) of the second double X-shaped beam (41).

3. The axial variable clearance gas dynamic pressure bearing according to claim 1, characterized in that: The bearing support structure (2) is formed by overlapping a plurality of mesh beam structures (51) composed of X-shaped beams in sequence, wherein a partial X-shaped beam of a previous mesh beam structure (51) is inserted into a diamond-shaped hole of a subsequent mesh beam structure (51) to form a multi-node contact; the axial end of the mesh beam structure (51) is supported by the central part of the mesh beam structure (51), so that the axial end of the mesh beam structure (51) is in a cantilever state, and its structural rigidity is lower than the rigidity of the central part of the mesh beam structure (51); after the bearing support structure (2) is subjected to a load, the top foil (1) obtains the same effect as the axial clearance.

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