Rigidity-adjustable foil aerodynamic bearing

Abstract

The invention provides a stiffness-adjustable foil aerodynamic bearing. The stiffness-adjustable foil aerodynamic bearing comprises a top foil, a first foil, an SMA foil group, a second foil, a bearing sleeve, a cooling fin and a radiating fin, wherein each of the first foil and the second foil is formed by connecting V-shaped beams which are distributed in the circumferential direction with two longitudinal beams at the end parts, the circumferential length of each first foil V-shaped beam is smaller than a gap between two adjacent second foil V-shaped beams, and each first foil V-shaped beam is arranged between the two corresponding second foil V-shaped beams; the SMA foil group is formed by sequentially overlapping a first SMA foil, an electric control heating film and a second SMA foil and is positioned between the first foil and the second foil, and the axial width of the SMA foil group is smaller than that of the V-shaped beams of the first foil and the second foil; the cold end of the electrically-controlled cooling fin is tightly attached to the second foil V-shaped beam, and the hot end is connected with the cooling fin; the top foil provides a bearing surface for the dynamic pressure gas film, and the bearing sleeve supports and fixes all the components. The elastic modulus of the SMA foil is rapidly adjusted through the electric control heating film and the cooling piece, active adjustment of the bearing rigidity is achieved, and the technical problems that an existing foil gas dynamic pressure bearing cannot cross the critical rotating speed and is unstable at the ultra-high speed are solved; the V-shaped beams distributed at intervals in the circumferential direction enable the top foil and the SMA foil sheet group to participate in structural deformation in a simply supported beam form, so that the impact resistance and the durability are improved; and after being loaded, the top foil forms a V-shaped recess to generate a gas gathering effect similar to a notch groove bearing, so that the bearing capacity of the bearing is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrodynamic bearings, and in particular to an adjustable stiffness foil gas hydrodynamic bearing, which is particularly suitable for high-speed rotating mechanical equipment such as fuel cell air compressors, blowers, micro gas turbines, etc. Background Art

[0002] Foil dynamic pressure bearings are divided into radial bearings and thrust bearings, which are composed of top foil, elastic foil and bearing sleeve, and use high-pressure gas as a carrier to support the rotor. However, the stiffness of the existing bearings and the rotor stiffness do not change with the rotor speed, resulting in the vibration amplitude seriously exceeding the bearing clearance when the rotor speed is close to or equal to the high-order natural frequency of the system, and the critical speed cannot be crossed. In addition, the smooth top foil and the circumferentially consistent elastic structure make the main stiffness of the bearing in the horizontal and vertical directions is isotropic and the cross stiffness is antisymmetric, resulting in subsynchronous instability of the rotor at high speed. The thrust bearing is used to bear the axial force of the rotor system to suppress the axial vibration and movement of the rotor system. However, in the prior art, the thrust bearing has insufficient bearing capacity for axial loads. Summary of the invention

[0003] In response to the above-mentioned technical deficiencies, the present application provides an adjustable stiffness foil gas dynamic pressure bearing, which uses SMA (shape memory alloy) foil as the elastic structure of the bearing, and quickly adjusts the elastic modulus of the SMA foil through the electrically controlled heating film and cooling sheet, thereby realizing active adjustment of the bearing stiffness. In addition, the combined design of the cooling sheet and the heat sink effectively improves the heat dissipation effect of the bearing, ensuring the stability of the bearing during high-speed rotation; the top foil, the first foil, the SMA foil group, and the second foil distributed in sequence participate in the deformation of the structure in the form of a simply supported beam, thereby improving the bearing capacity and durability of the bearing to impact loads; at the same time, the top foil, supported by the first foil, produces a gas gathering effect similar to that of a grooved bearing, thereby improving the bearing capacity of the bearing. The many technical effects that can be produced by the preferred technical scheme among the many technical schemes provided by the present invention are described below.

[0004] To achieve the above technical objectives, the present invention provides the following technical solutions: an adjustable stiffness foil gas dynamic pressure bearing, comprising: a top foil, a first foil, an SMA foil group, a second foil, a bearing sleeve, a cooling fin, and a heat sink.

[0005] The first foil and the second foil are both composed of two longitudinal beams at the ends of the foils connected by a plurality of circumferentially distributed V-shaped beams, the circumferential length of the first foil V-shaped beam is independent of the circumferential length of the second foil V-shaped beam, the circumferential gap between two adjacent first foil V-shaped beams is independent of the circumferential gap between two adjacent second foil V-shaped beams, the circumferential length of the first foil V-shaped beam is smaller than the gap between two adjacent second foil V-shaped beams, the first foil V-shaped beam is placed between the two second foil V-shaped beams, the circumferential length of the second foil V-shaped beam is smaller than the gap between two adjacent first foil V-shaped beams, and the second foil V-shaped beam is placed between the two first foil V-shaped beams; the axial widths of the first foil and the second foil are equal to the axial width of the top foil and larger than the axial width of the SMA foil group, and the end of the first foil is in a cantilever state relative to the SMA foil group.

[0006] The SMA foil group consists of a first SMA foil, a second SMA foil and an electrically controlled heating film of the same length. The electrically controlled heating film is placed between the first SMA foil and the second SMA foil, and the axial width of the SMA foil group is smaller than the axial width of the V-shaped beam of the first foil and the second foil; the circumferential length of the electrically controlled heating film is equal to or smaller than the circumferential length of the first SMA foil; the electrically controlled heating film is powered on to heat the first SMA foil and the second SMA foil, causing them to undergo phase change, changing the elastic modulus and increasing their diameter values, thereby adjusting the stiffness of the bearing.

[0007] The cooling fins and heat sinks are respectively placed on the cooling fin grooves and the heat sink grooves on the bearing sleeve, and the cooling fins are distributed circumferentially. The cold end of the power-controlled cooling fin is located below the second foil, close to the V-shaped beam of the second foil and fixed in the cooling fin groove on the bearing, and the hot end of the cooling fin is close to the heat sink. The heat sink has multiple vertical thin plates, and the heat dissipation area is increased by the multiple vertical thin plates to ensure temperature control of the bearing when rotating at high speed.

[0008] One end of the top foil is fixed on the bearing sleeve and the other end is free. The axial length of the top foil is less than or equal to the axial length of the first foil, the second foil and the bearing sleeve. The top foil provides a bearing surface for the dynamic pressure air film.

[0009] The inner surface of the bearing sleeve is provided with a cooling fin groove and a heat sink groove. The cooling fin groove is above the heat sink groove. The bearing sleeve supports and fixes the top foil, the first foil and the second foil.

[0010] Preferably, the first foil and the second foil may consist of a longitudinal beam and circumferentially distributed V-shaped beams.

[0011] Preferably, the angle of the V-shaped beam can be changed according to actual needs, and the side lines on both sides of the V-shape may not be parallel.

[0012] Preferably, the first foil V-shaped beam can be replaced by an arc-shaped beam, an X-shaped beam, a straight beam, or a multi-segment linear beam, and the second foil is provided with holes corresponding to the enlarged proportions of the beam structures at the circumferential positions of the first foil V-shaped beam and other beam structures, so that the first foil V-shaped beam and other beam structures can be deformed.

[0013] Preferably, the circumferential length of the axial middle position of the V-shaped beam, arc-shaped beam, X-shaped beam, straight beam or other beam structure of the first foil can be greater than the circumferential length of its end, so that the middle stiffness of the foil support beam is greater than the end support stiffness.

[0014] Preferably, the ends of both sides of the first SMA foil and the second SMA foil may be provided with circumferentially distributed end grooves, so that the first SMA foil and the second SMA foil have greater stiffness in the middle and smaller stiffness at both ends, and the end grooves are placed under the V-shaped beam of the first foil.

[0015] Preferably, the electrically controlled heating film may be a single or multiple circumferentially distributed, globally or locally electrically heating the first SMA foil and the second SMA foil, so as to cause the SMA material to phase change, change its elastic modulus and expand its diameter, thereby producing a local preload effect.

[0016] Preferably, the top foil, the first foil and the second foil can all be made of SMA material.

[0017] Preferably, the top foil is arc-shaped, and may be one or a plurality of top foils distributed along the circumferential direction.

[0018] Preferably, the edge line of the free end of the top foil may be arc-shaped, V-shaped, or straight-shaped, and the direction of the arc or V-shape is consistent with the rotation direction of the rotor.

[0019] Preferably, the bearing is removable except for the cooling fins and heat sink.

[0020] The structural features of the adjustable stiffness foil gas dynamic pressure bearing can be used for radial bearings and thrust bearings; when used as a support structure for a thrust bearing, it is composed of a thrust top foil, a thrust first foil, a thrust SMA foil group, a thrust second foil, and a thrust bearing sleeve, and all components are fixed on the thrust bearing sleeve through thrust foil limiting holes.

[0021] The first thrust foil and the second thrust foil are both composed of a plurality of circumferentially non-uniformly distributed thrust foil V-shaped beams connecting the thrust foil inner circle and the thrust foil outer circle. The circumferential length of the V-shaped beam of the first thrust foil is smaller than the gap between the two adjacent V-shaped beams of the second thrust foils. The V-shaped beam of the first thrust foil is placed between the two V-shaped beams of the second thrust foils. The circumferential length of the V-shaped beam of the second thrust foil is smaller than the gap between the two adjacent V-shaped beams of the first thrust foils. The V-shaped beam of the second thrust foil is placed between the two V-shaped beams of the first thrust foils. The plurality of circumferentially non-uniformly distributed V-shapes divide the bearing circumferentially into a plurality of parts. The V-shaped beam of the first part and the V-shaped beam of the second part are separated by thrust foil reserved holes. The circumferential distance of the thrust foil reserved holes is relatively large. The thrust foil reserved holes of the first thrust foil and the second thrust foil are approximately at the same circumferential position.

[0022] The thrust SMA foil group consists of a thrust first SMA foil, a thrust second SMA foil and a thrust electrically controlled heating film with the same structure. The shapes of the thrust first SMA foil and the thrust second SMA foil are similar to the thrust top foil. The inner diameters of the thrust first SMA foil and the thrust second SMA foil are larger than the inner diameter of the thrust foil V-shaped beam. The outer diameters of the thrust first SMA foil and the thrust second SMA foil are smaller than the outer diameter of the thrust foil V-shaped beam. The thrust electrically controlled heating film is placed between the thrust first SMA foil and the thrust second SMA foil. The circumferential length of the thrust electrically controlled heating film is equal to or smaller than the circumferential length of the thrust first SMA foil.

[0023] The thrust top foil is composed of a thrust top foil outer ring, a thrust top foil connecting beam, and a thrust top foil bearing surface. The outer diameter of the circumferentially distributed top foil bearing surface is greater than or equal to the outer diameter of the V-shaped beam of the thrust foil, and the inner diameter of the top foil bearing surface is less than or equal to the inner diameter of the V-shaped beam of the thrust foil. One top foil end of the thrust top foil is located in a reserved hole of the thrust foil. When subjected to an air film load, the top foil end is deformed in the reserved hole of the thrust foil to form a wedge shape.

[0024] Preferably, the thrust foil V-beam angle can be changed according to actual needs.

[0025] Preferably, the two side lengths and the circumferential widths of the thrust foil V-beam may be different.

[0026] Preferably, the V-shaped beam of the thrust foil can be replaced by an arc beam, an X-shaped beam, a straight beam or a multi-segment linear beam. The specific shapes of the V-shaped beam and other beam structures are set according to the pressure distribution of the thrust bearing. The thrust second foil is provided with holes corresponding to the V-shaped beam and other beam structures of the thrust first foil at the circumferential position of the V-shaped beam and other beam structures of the thrust first foil, so that the V-shaped beam and other beam structures of the thrust first foil can be deformed.

[0027] Preferably, the thrust first foil straight beam can be placed along the radial direction of the thrust bearing, or in the horizontal and vertical directions.

[0028] Preferably, the thrust electrically controlled heating film may be a single or multiple circumferentially distributed thrust first SMA foil and thrust second SMA foil, which may be electrically heated globally or locally to cause a phase change of the SMA material and change its elastic modulus.

[0029] Preferably, the thrust top foil, the thrust first foil and the thrust second foil can all be made of SMA material.

[0030] Preferably, the shape of the top foil end can be regular or irregular shapes such as arc or multi-segment lines, which is set according to the distribution of gas film pressure. The arc or V-shape of the top foil bearing surface is oriented in the same direction as the rotor rotation direction to gather gas.

[0031] Due to the adoption of the above technology, the present invention has the following positive effects compared with the prior art: the present invention provides an adjustable stiffness foil gas dynamic pressure bearing, wherein the top foil, the first foil, the SMA foil group and the second foil are all processed from flat foils, and no mold pressing and shaping is required, thereby improving the processing technology of the bearing structure; the SMA (shape memory alloy) foil is used as the elastic structure of the bearing, and the temperature rise and temperature drop of the SMA foil are quickly changed through an electrically controlled heating film and an electrically controlled cooling sheet, thereby changing the elastic modulus of the SMA foil, and then changing the circumferential global or local support stiffness of the bearing, so as to adjust the bearing stiffness. The main stiffness of the bearing is anisotropic and the cross stiffness is weakened, which enables the rotor system to operate stably across critical speeds and at ultra-high speeds; at the same time, the cooling fins and heat sinks increase the heat dissipation effect of the bearing and the temperature control speed of the SMA material; the V-shaped beams distributed circumferentially between the first foil and the second foil enable the top foil and the SMA foil group to participate in the deformation of the structure in the form of simply supported beams, thereby improving the bearing capacity and durability of the bearing to impact loads; at the same time, the top foil under load has a V-shaped depression supported by the first foil, producing a gas gathering effect similar to that of a grooved bearing, thereby improving the bearing capacity of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 work.

[0033] Figure 1 An exploded diagram of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0034] Figure 2 A front view of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0035] Figure 3 A bearing support structure diagram of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0036] Figure 4 A schematic diagram of a first foil of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0037] Figure 5 A schematic diagram of a second foil of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0038] Figure 6 A schematic diagram of an SMA foil assembly of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0039] Figure 7 A partial enlarged view of a bearing sleeve of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0040] Figure 8 A schematic diagram of a first foil pattern 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0041] Fig. 9 A schematic diagram of a second foil pattern 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0042] Fig.10 A schematic diagram of a first foil pattern 2 of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0043] Fig.11 A schematic diagram of a first foil pattern 3 of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0044] Fig.12 This is an enlarged partial cross-sectional view of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0045] Fig.13 A schematic diagram of a bearing support structure style 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0046] Fig.14 A schematic diagram of an SMA foil pattern 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0047] Fig.15 An exploded diagram of an adjustable stiffness thrust bearing of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0048] Fig.16 A schematic diagram of a thrust foil of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0049] Fig.17 A schematic diagram of a thrust foil of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0050] Fig.18 A schematic diagram of a thrust SMA foil pattern 1 of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0051] Fig.19 A schematic diagram of a thrust bearing style 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0052] Fig. 20 A schematic diagram of a thrust top foil pattern 1 of an adjustable stiffness foil gas dynamic pressure bearing provided by the present invention.

[0053] Fig.21 A schematic diagram of a thrust foil pattern 1 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0054] Fig. 22 A schematic diagram of a thrust foil pattern 2 of an adjustable stiffness foil gas hydrodynamic bearing provided by the present invention.

[0055] Among them, the marks of the figures in the figure are: 1-top foil, 2-first foil, 3-SMA foil group, 4-second foil, 5-bearing sleeve, 6-cooling fin, 7-heat sink, 11-thrust bearing sleeve, 12-thrust first foil, 13-thrust SMA foil group, 14-thrust second foil, 15-thrust top foil, 16-thrust first foil pattern 1, 17-thrust SMA foil group pattern 1, 18-thrust second foil pattern 1, 19-thrust top foil pattern 1, 20-thrust first foil pattern 2, 21-first foil longitudinal beam, 22-first foil V-shaped beam, 23-X-shaped beam, 24-I-shaped beam, 31-first SMA foil, 32-electrically controlled heating film, 33-second SMA foil, 41-second foil longitudinal beam, 42-second foil V-shaped beam, 43-enlarged X-shaped hole, 51-cooling fin groove, 52-heat sink groove, 121-thrust foil outer ring, 122-thrust foil V-shaped beam, 123-thrust foil inner ring, 124-thrust foil limit hole, 125-thrust foil Reserved hole, 131-thrust first SMA foil, 132-thrust electric control heating film, 133-thrust second SMA foil, 141-thrust second foil outer ring, 142-thrust second foil cross beam, 143-thrust second foil inner ring, 144-thrust second foil limit hole, 145-thrust second foil reserved hole, 151-thrust top foil outer ring, 152-thrust top foil connecting beam, 153-thrust top foil bearing surface, 154-thrust top foil end, 171-thrust first SMA foil sample Formula 1, 172-thrust electric controlled heating film, 173-thrust second SMA foil style 1, 181-thrust first foil style 1 outer ring, 182-thrust first foil style 1 cross beam, 183-thrust first foil style 1 inner ring, 184-thrust first foil style 1 limiting hole, 185-thrust first foil style 1 reserved hole, 191-thrust top foil style 1 outer ring, 192-thrust top foil style 1 connecting beam, 193-thrust top foil style 1 bearing surface, 311-SMA foil end groove. DETAILED DESCRIPTION

[0056] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0057] In the description of the present invention, it should be noted that, unless otherwise specified, “several” and “plurality” mean two or more than two; the orientations or positional relationships indicated by the terms “upper”, “lower”, “top”, “bottom”, “inner”, “outer”, “first”, “second”, etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0058] 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 thickness of the air film is uneven in the radial direction of the bearing. For example, the bearing structure is preloaded during installation, or the preload formed during the working process of the bearing has the same effect as the preload applied in advance. For ordinary technicians in this field, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0059] The adjustable stiffness foil gas dynamic pressure bearing provided in the embodiment of the present application is now described.

[0060] like Figure 1 and Figure 2 As shown, an adjustable stiffness foil gas dynamic pressure bearing comprises: a top foil (1), a first foil (2), an SMA foil group (3), a second foil (4), a bearing sleeve (5), a cooling fin (6), and a heat sink (7).

[0061] like Figures 3 to 5 As shown, the first foil (2) and the second foil (4) are both composed of a plurality of circumferentially distributed V-shaped beams connecting two longitudinal beams at the ends of the foils, the circumferential length of the first foil V-shaped beam (22) is not related to the circumferential length of the second foil V-shaped beam (42), the circumferential gap between two adjacent first foil V-shaped beams (22) is not related to the circumferential gap between two adjacent second foil V-shaped beams (42), the circumferential length of the first foil V-shaped beam (22) is smaller than the gap between two adjacent second foil V-shaped beams (42), and the circumferential length of the first foil V-shaped beam (22) is smaller than the gap between two adjacent second foil V-shaped beams (42). The SMA foil group (3) is a SMA foil group (4), the SMA foil group (4) is a SMA foil group (5), the SMA foil group (5) is a SMA foil group (6), the SMA foil group (7) is a SMA foil group (8), the SMA foil group (9) is a SMA foil group (10), the SMA foil group (11) is a SMA foil group (12), the SMA foil group (13) is a SMA foil group (14), the SMA foil group (24) is a SMA foil group (3), the SMA foil group (25) is a SMA foil group (3), the SMA foil group (25) is a SMA foil group (10), the SMA foil group (25) is a SMA foil group (3), the SMA foil group (26) is a SMA foil group (10), the SMA foil group (26) is a SMA foil group (3 ...

[0062] like Figure 6As shown, the SMA foil group (3) is composed of a first SMA foil (31), a second SMA foil (33) and an electrically controlled heating film (32) of the same length; the electrically controlled heating film (32) is placed between the first SMA foil (31) and the second SMA foil (33); the axial width of the SMA foil group (3) is smaller than the axial width of the V-shaped beam of the first foil and the second foil; the circumferential length of the electrically controlled heating film (32) is equal to or smaller than the circumferential length of the first SMA foil (31); when the electrically controlled heating film (32) is energized, it heats the first SMA foil (31) and the second SMA foil (33) simultaneously, causing the SMA material to undergo a phase change, changing its elastic modulus and increasing its diameter value, thereby producing a local preload effect.

[0063] like Figure 1 As shown, one end of the top foil (1) is fixed on the bearing sleeve (5) and the other end is free. The axial length of the top foil (1) is less than or equal to the axial length of the first foil (2), the second foil (4) and the bearing sleeve (5). The top foil (1) provides a bearing surface for the dynamic pressure air film.

[0064] like Figure 1 , Figure 2 , Figure 7 , Fig.12 As shown, the cooling fins (6) are distributed along the circumferential direction, the cold end of the cooling fin (6) controlled by power supply is located in the second foil V-shaped beam (42) and fixed in the cooling fin groove (51) on the bearing, the hot end of the cooling fin (6) is closely attached to the heat sink (7), the heat sink (7) has a plurality of vertical thin plates to increase the ventilation and heat dissipation area, and the heat sink (7) is placed in the heat sink groove (52) of the bearing sleeve (5).

[0065] like Figure 4 and Figure 5 As shown, preferably, the axial width of the longitudinal beams (21, 41) of the first foil (2) and the second foil (4) is independent of the circumferential length of the V-shaped beams (22, 42), and the two sizes can be made the same or different; Preferably, only one of the longitudinal beams (21, 41) of the first foil (2) and the second foil (4) may be retained.

[0066] Preferably, the angle of the V-shaped beam can be changed according to actual needs, and the side lines on both sides of the V-shape may not be parallel.

[0067] Preferably, if Figures 8 to 11As shown, the V-shaped beam of the first foil (2) can be replaced by an X-shaped beam (23), a straight beam (24), an arc beam, a multi-segment line beam, etc., and the first foil (2) and the second foil (3) after the replacement become the first foil style 1 and the second foil style 1, the first foil style 2, the first foil style 3, etc.; the second foil (4) is provided with an enlarged X-shaped hole corresponding to the various beam structures such as the X-shaped beam (23) of the first foil (2) at the circumferential position, so that the various beam structures such as the X-shaped beam (23) can be deformed.

[0068] Preferably, if Fig.11 As shown, the circumferential length of the axial middle position of the beam structure such as the V-shaped beam, arc-shaped beam, X-shaped beam (23), straight beam (24) of the first foil can be greater than the circumferential length of its end portion, so that the middle stiffness of the foil support beam is greater than the end support stiffness.

[0069] Preferably, if Figure 13-14 As shown, the ends of both sides of the first SMA foil (31) and the second SMA foil (33) can be processed to form circumferentially distributed SMA foil end grooves (311), so that the first SMA foil (31) and the second SMA foil (33) have greater rigidity in the middle and less rigidity at both ends, and the SMA foil end grooves (311) are placed below the first foil V-shaped beam (22).

[0070] Preferably, one or more electrically controlled heating films (32) may be distributed circumferentially to globally or locally heat the first SMA foil (31) and the second SMA foil (33), thereby causing the SMA material to undergo a phase change, changing its elastic modulus and expanding its diameter, thereby producing a local preload effect.

[0071] Preferably, the top foil (1), the first foil (2) and the second foil (4) can all be made of SMA material.

[0072] Preferably, the structure composed of the top foil (1), the first foil (2), the SMA foil group (3), and the second foil (4) can be one or a plurality of structures distributed along the circumferential direction.

[0073] Preferably, the edge line of the free end of the top foil (1) may be arc-shaped, V-shaped, or straight-shaped, and the direction of the arc or V-shape is consistent with the rotation direction of the rotor.

[0074] Preferably, the bearing has removable cooling fins (6) and heat sinks (7).

[0075] like Figure 1 and Figure 15-16As shown, the structural features of the adjustable stiffness foil gas dynamic pressure bearing can be used for radial bearings and thrust bearings; when used as a support structure for a thrust bearing, it is composed of a thrust top foil (15), a thrust first foil (12), a thrust SMA foil group (13), a thrust second foil (14), and a thrust bearing sleeve (11), and all components are fixed to the thrust bearing sleeve (11) via thrust foil limiting holes (124).

[0076] like Figure 15-16 As shown, the thrust first foil (12) and the thrust second foil (14) are composed of a plurality of thrust foil V-shaped beams (122) that are non-uniformly distributed in the circumferential direction and connect the thrust foil inner circle (123) and the thrust foil outer circle (121); the circumferential length of the thrust foil V-shaped beam (122) of the thrust first foil (12) is smaller than the gap between the thrust foil V-shaped beams (122) of two adjacent thrust second foils (14); the thrust foil V-shaped beam (122) of the thrust first foil (12) is placed between the thrust foil V-shaped beams (122) of the two thrust second foils (14); the circumferential length of the thrust foil V-shaped beam (122) of the thrust second foil (14) is smaller than the gap between the thrust foil V-shaped beams (122) of the two adjacent thrust first foils (1 2), the thrust foil V-shaped beam (122) of the second thrust foil (14) is placed between the thrust foil V-shaped beams (122) of the two first thrust foils (12); a plurality of thrust foil V-shaped beams (122) of the first thrust foil (12) and the second thrust foil (14) that are unevenly distributed in the circumferential direction divide the bearing into multiple parts in the circumferential direction; the thrust foil V-shaped beam of the first part and the thrust foil V-shaped beam of the second part are separated by thrust foil reserved holes (125); the circumferential distance of the thrust foil reserved holes (125) is relatively large; the thrust foil reserved holes (125) of the first thrust foil (12) and the thrust foil reserved holes (125) of the second thrust foil (14) are approximately in the same circumferential position.

[0077] like Fig.17 As shown, the thrust top foil (15) is composed of a thrust top foil outer ring (151), a thrust top foil connecting beam (152), and a thrust top foil bearing surface (153); the thrust top foil bearing surface (153) is connected to the thrust top foil outer ring (151) via the thrust top foil connecting beam (152); the outer diameter of the circumferentially distributed thrust top foil bearing surface (153) is less than or equal to the outer diameter of the thrust foil V-shaped beam (122); the inner diameter of the thrust top foil bearing surface (153) is greater than or equal to the inner diameter of the thrust foil V-shaped beam (122); a thrust top foil end portion (154) of the thrust top foil bearing surface (153) is located in a thrust foil reserved hole (125); and when subjected to an air film load, the thrust top foil end portion (154) is deformed in the thrust foil reserved hole (125) to form a wedge shape.

[0078] like Fig.18As shown, the thrust SMA foil group (17) is composed of a thrust first SMA foil (171), a thrust second SMA foil (173) and a thrust electrically controlled heating film (172) having the same structure; the shapes of the thrust first SMA foil (171) and the thrust second SMA foil (173) are similar to the thrust top foil (15); the inner diameters of the thrust first SMA foil (171) and the thrust second SMA foil (173) are larger than the inner diameters of the V-shaped beams of the thrust first foil and the thrust second foil, and the outer diameters are smaller than the outer diameters of the V-shaped beams of the thrust first foil (12) and the thrust second foil (14); the thrust electrically controlled heating film (132) is disposed between the thrust first SMA foil (11) and the thrust second SMA foil (173); and the circumferential length of the thrust electrically controlled heating film (172) is equal to or smaller than the circumferential length of the thrust first SMA foil (171).

[0079] Preferably, the included angle of the thrust foil V-shaped beam (122) can be changed according to actual needs.

[0080] Preferably, the two side lengths and the circumferential widths of the thrust foil V-beam (122) may be different.

[0081] Preferably, if Figure 17-20 As shown, the thrust foil V-shaped beam (122) can be replaced by an arc beam, an X-shaped beam (23), a straight beam (24) or a multi-segment linear beam, and the specific shapes of the V-shaped beam and other beam structures are set according to the pressure distribution of the thrust bearing. The thrust second foil is provided with holes corresponding to the V-shaped beam and other beam structures of the first thrust foil at the circumferential position of the V-shaped beam and other beam structures of the first thrust foil, so that the V-shaped beam and other beam structures of the first thrust foil can be deformed.

[0082] Preferably, if Fig.18 As shown, the thrust electrically controlled heating film (172) can be a single or multiple circumferentially distributed thrust first SMA foil (171) and thrust second SMA foil (173) that are electrically heated globally or locally, causing the SMA material to undergo a phase change and change its elastic modulus.

[0083] Preferably, if Fig. 22 As shown, the I-shaped beam of the thrust foil can be placed along the radial direction of the thrust bearing, as well as in the horizontal and vertical directions.

[0084] Preferably, the thrust top foil (15), the thrust first foil (12), and the thrust second foil (14) can all be made of SMA material.

[0085] Preferably, the shape of the thrust top foil end (154) can be an arc or a multi-segment line, etc., which is set according to the air film pressure distribution. The arc or V-shape of the thrust top foil bearing surface (155) is oriented in the same direction as the rotor rotation direction to gather gas.

[0086] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, modification, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An adjustable stiffness foil gas dynamic pressure bearing, characterized in that: include: Top foil, first foil, SMA (shape memory alloy) foil group, second foil, bearing sleeve, cooling fin, heat sink; wherein, The first foil and the second foil are both composed of two longitudinal beams at the ends of the foils connected by a plurality of circumferentially distributed V-shaped beams, the circumferential length of the first foil V-shaped beam is smaller than the gap between two adjacent second foil V-shaped beams, and the first foil V-shaped beam is placed between the two second foil V-shaped beams; The SMA foil group is composed of a first SMA foil, an electrically controlled heating film, and a second SMA foil stacked in sequence, and is located in the middle of the first foil and the second foil in the radial and axial directions, and its axial width is smaller than the axial width of the V-shaped beam of the first foil and the second foil; The cold end of the electrically controlled cooling fin is located below the second foil and is in close contact with the V-shaped beam of the second foil, and the hot end of the cooling fin is in close contact with the heat sink, and the heat sink is provided with a plurality of vertical thin plates to increase the heat dissipation area; The axial length of the top foil is less than or equal to the axial lengths of the first foil, the second foil and the bearing sleeve. The top foil provides a bearing surface for the dynamic pressure air film, and the bearing sleeve supports and fixes all components.

2. The adjustable stiffness foil gas dynamic pressure bearing according to claim 1, characterized in that: The first foil and the second foil are both composed of two longitudinal beams connected by circumferentially distributed V-beams at the ends of the foils. The circumferential length of the V-beam of the first foil is less than the gap between two adjacent V-beams of the second foil, and the V-beam of the first foil is placed between the two V-beams of the second foil. The angle of the V-beam is adjustable, and the V-beam can be replaced by an arc beam, an X-beam, a straight beam, etc. The circumferential length of the axial middle position of the beam structure such as the V-beam, the arc beam, the X-beam, the straight beam, etc. can be greater than the circumferential length of the end thereof, so that the middle stiffness is greater than the supporting stiffness at both ends. The second foil is provided with holes corresponding to the beam structure of an enlarged proportion at the circumferential position of the various beam structures such as the first foil V-beam, so that the various beam structures such as the first foil V-beam can be deformed. The axial lengths of the first foil and the second foil are greater than or equal to the axial length of the top foil, and greater than the axial length of the SMA foil group, and the end of the first foil is in a cantilever state relative to the SMA foil group.

3. The adjustable stiffness foil gas dynamic pressure bearing according to claim 1, characterized in that: The SMA foil group consists of a first SMA foil, a second SMA foil and an electrically controlled heating film of the same length. The electrically controlled heating film is placed between the first SMA foil and the second SMA foil. The circumferential length of the electrically controlled heating film is equal to or less than the circumferential length of the first SMA foil. The electrically controlled heating films are distributed circumferentially singly or in plurality. Global or local heating causes the SMA material to undergo a phase change, changes its elastic modulus, and increases its diameter value to produce a local preload effect. The top foil, the first foil, and the second foil can all be made of SMA material.

4. The adjustable stiffness foil gas dynamic pressure bearing according to claim 1, characterized in that: The ends of both sides of the first SMA foil and the second SMA foil may be provided with circumferentially distributed end grooves so that the middle stiffness is greater than the two end stiffnesses, and the end grooves are placed under the V-shaped beam of the first foil.

5. The adjustable stiffness foil gas dynamic pressure bearing according to claim 1, characterized in that: The detachable cooling fins and heat sinks are distributed along the circumferential direction and are respectively located in the cooling fin grooves and heat sink grooves on the bearing sleeve. The cooling fins and heat sinks and the electrically controlled heating film jointly adjust the temperature of the SMA material.

6. The adjustable stiffness foil gas dynamic pressure bearing according to claim 1, characterized in that: The top foil is an arc-shaped or segmented structure, one end of the top foil is fixed on the bearing sleeve, and the other end is free. The edge line of the free end of the top foil can be an arc, a V shape, or a straight line. The direction of the arc or V shape is consistent with the rotation direction of the rotor.

7. The adjustable stiffness foil gas dynamic pressure bearing according to claims 1-6, characterized in that: The structural features of the adjustable stiffness foil gas dynamic pressure bearing can be used for radial bearings and thrust bearings; when used as a thrust bearing, it is composed of a thrust top foil, a thrust first foil, a thrust SMA foil group, a thrust second foil, and a thrust bearing sleeve, and each component is fixed on the thrust bearing sleeve through the thrust foil limiting hole.

8. The adjustable stiffness foil gas dynamic pressure bearing according to claim 7, characterized in that: The first thrust foil and the second thrust foil are both composed of a plurality of thrust foil V-shaped beams that are non-uniformly distributed in the circumferential direction and connect the thrust foil inner circle and the thrust foil outer circle. The circumferential length of the first thrust foil V-shaped beam is smaller than the gap between two adjacent second thrust foil V-shaped beams and is placed between the two second thrust foil V-shaped beams. The circumferential length of the second thrust foil V-shaped beam is smaller than the gap between two adjacent first thrust foil V-shaped beams and is placed between the two first thrust foil V-shaped beams. The thrust foil V-shaped beam included angle can be changed, the two side lengths on the same side of the thrust foil V-shaped beam and the circumferential widths on both sides can be different, the thrust foil V-shaped beam can be replaced by an arc beam, an X-shaped beam, a straight beam or a multi-segment line beam, wherein the straight beam can be placed along the radial direction of the thrust bearing, or in the horizontal and vertical directions, and the specific shapes of the V-shaped beam and other beam structures are set according to the pressure distribution of the thrust bearing, and the thrust second foil is provided with holes corresponding to the V-shaped beam and other beam structures of the enlarged proportion at the circumferential position of the thrust first foil V-shaped beam and other beam structures, so that the thrust foil V-shaped beam and other beam structures can be deformed; Several V-shaped thrust foils distributed unevenly in the circumferential direction divide the bearing into multiple parts in the circumferential direction. The V-shaped beam of the first part and the V-shaped beam of the second part are separated by thrust foil reserved holes, and the circumferential distance of the thrust foil reserved holes is relatively large.

9. The adjustable stiffness foil gas dynamic pressure bearing according to claim 7, characterized in that: The thrust SMA foil group consists of a thrust first SMA foil, a thrust second SMA foil and a thrust electrically controlled heating film with the same structure. The shapes of the thrust first SMA foil and the thrust second SMA foil are similar to the thrust top foil. The inner diameters of the thrust first SMA foil and the thrust second SMA foil are larger than the inner diameters of the thrust foil V-shaped beams, and the outer diameters thereof are smaller than the outer diameters of the thrust foil V-shaped beams. The thrust electrically controlled heating film is placed in the middle of the thrust first SMA foil and the thrust second SMA foil. The circumferential length of the thrust electrically controlled heating film is equal to or smaller than the circumferential length of the thrust first SMA foil. The thrust electrically controlled heating film can be single or multiple circumferentially distributed. Global or local heating causes the SMA material to phase change, change its elastic modulus and increase its diameter value. The thrust top foil, the thrust first foil and the thrust second foil can all be made of SMA material.

10. The adjustable stiffness foil gas dynamic pressure bearing according to claim 7, characterized in that: The thrust top foil is composed of a thrust top foil outer ring, a thrust top foil connecting beam, and a thrust top foil bearing surface. The outer diameter of the circumferentially distributed thrust top foil bearing surface is greater than or equal to the outer diameter of the thrust foil V-shaped beam, and the inner diameter of the thrust top foil bearing surface is less than or equal to the inner diameter of the thrust foil V-shaped beam. The shape of the top foil end can be an arc or a multi-segment line, etc., which is set according to the air film pressure distribution; one thrust top foil end of the thrust top foil is supported by the thrust foil V-shaped beam, and the other thrust top foil end is deformed in the thrust foil reserved hole; the arc or V-shaped direction of the top foil bearing surface is consistent with the rotation direction of the rotor.

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