A gas dynamic pressure bearing with finned support foils

Abstract

The present invention discloses a gas dynamic pressure bearing with fin-shaped supporting foil, which includes a cylindrical bearing sleeve, a plurality of fin-shaped supporting foils and a hollow cylindrical top foil; a plurality of narrow grooves are formed on the bearing sleeve, the embedding ends of the supporting foils and the top foil are fixedly embedded in these narrow grooves, and the extending ends of the supporting foils are in contact with the outer wall after forming a ring with the top foil. The bearing adopts a straight sheet structure or an "L"-shaped bent supporting foil directly inserted into the narrow groove of the bearing sleeve, which can play an elastic supporting effect on the top foil; at the same time, different supporting foils are flexibly matched to achieve non-linear stiffness, and multiple contact areas between different supporting foils and between the supporting foils and the top foil provide good damping.

Description

Technical Field

[0001] The invention relates to the field of preparation of dynamic pressure gas bearings, and in particular to a dynamic pressure gas bearing with fin-type supporting foils. Background Art

[0002] As a novel bearing, hydrodynamic gas bearings are often used in ultra-high-speed small and medium-sized power machinery, such as high-speed blowers, compressors and turbines, etc. Among them, foil bearings are the most representative and widespread. Foil bearings have the advantages of simple structure, small size, and good adaptability to various working conditions. There is a certain gap between the foil group and the rotating shaft to form a gas hydrodynamic effect. The foil structure provides elastic support, and the mutual friction of the foil group during deformation after being loaded provides damping. This elastic support and damping improve the dynamic stability of the hydrodynamic bearing.

[0003] The earliest developed foil bearing is the cantilever type bearing, which has a simple structure and manufacturing and assembly process. The main structure is composed of multiple arc foils of the same shape. One end of the arc foil is embedded or hinged to the inner wall of the bearing sleeve, and the other end is freely suspended and overlapped with the adjacent arc foil. The envelope shape formed by these overlapping foils cooperates with the rotating shaft to form multiple wedge-shaped gaps. However, both practice and theory have shown that the stiffness and load-bearing capacity of the cantilever foil bearing are relatively small, and it is not competent in occasions with certain load requirements.

[0004] Another type of foil bearing that was developed earlier is the wave foil bearing, which is currently widely used. The wave foil bearing has a split design for the working surface and supporting structure used to form the air film, that is, the foil group consists of a top foil and a wave foil. The main body of the top foil is a smooth arc surface, and the wave foil consists of a plurality of arched corrugated shapes and a flat section connecting these waves. The corrugated shape greatly increases the supporting stiffness of the foil, so the bearing capacity is also improved, and there are more contact points between the corrugation and the top foil or the bearing sleeve, which also improves the damping performance. Generally, the paddle group of the wave foil bearing consists of a top foil and a wave foil, which is easy to install, but the bearing has high requirements for the manufacturing precision of the wave foil. Generally, a precision mold is used to stamp the foil into shape, and foils with different parameters require different molds to be designed, which increases the manufacturing difficulty and cost.

[0005] The fin-supported foil bearing proposed in the present application provides a support structure with a simple manufacturing process, and can provide sufficient rigidity and load-bearing capacity. It has more contact points with the top foil, can provide good damping, and is easy to design and manufacture bearings with different parameters. Summary of the invention

[0006] Based on the above problems, the problem to be solved by the present invention is to provide a gas dynamic pressure bearing with simple manufacturing process, low cost, strong load-bearing capacity and fin-type supporting foil.

[0007] The technical solution of the present invention is as follows:

[0008] A gas dynamic pressure bearing with fin-type supporting foils, comprising a cylindrical bearing sleeve, a plurality of fin-type supporting foils and a hollow cylindrical top foil; wherein:

[0009] The inner wall of the bearing sleeve is provided with a plurality of narrow grooves;

[0010] Each of the supporting foils comprises an embedded end and an extended end, wherein the embedded end is correspondingly embedded in one of the narrow grooves, and the extended end of the supporting foil extends toward the through hole of the bearing sleeve and contacts the outer wall of the top foil disposed in the through hole of the bearing sleeve;

[0011] The top foil is an open ring column, and the top foil includes a fixed end and a free end. The fixed end is bent outward and tilted and then embedded in a narrow groove of the bearing sleeve. The free end is close to the fixed end.

[0012] In one embodiment, in the gas dynamic pressure bearing, adjacent narrow grooves are evenly distributed at equal arc angle intervals along the clockwise direction on the inner wall of the bearing sleeve, and each narrow groove forms an acute angle with the radial surface of the bearing sleeve.

[0013] In one embodiment, in the gas hydrodynamic bearing, the supporting foils take the fixed end and the free end of the top foil as the starting point and the end point respectively, and the extended end of each supporting foil is fixedly arranged on the outer wall of the top foil in the order of decreasing and then increasing arrangement spacing, and the supporting foils arranged in the middle area of ​​the outer wall of the top foil are relatively denser than the supporting foils arranged in other areas of the outer wall of the top foil.

[0014] In one embodiment, in the gas dynamic pressure bearing, the supporting foil is a straight sheet structure, and the narrow groove is a straight groove; a lug is respectively provided at the two axial ends of the supporting foil, and after the supporting foil is installed in the narrow groove, a limiting ring for limiting the position is installed on the axial end face of the bearing sleeve, the lug is exposed on the axial end face of the bearing sleeve, and the limiting ring is adapted to be inserted between the lug and the top foil.

[0015] In one embodiment, in the gas dynamic pressure bearing, the supporting foil is a straight sheet-like structure, and a plurality of notches are formed along the longitudinal direction on the straight side of the extending end.

[0016] In one embodiment, in the gas hydrodynamic bearing, each of the supporting foils includes a main fin and a plurality of auxiliary fins; the embedded end of the auxiliary fin is flush with the embedded end of the main fin, the extended end of the auxiliary fin is closely adjacent to the extended end of the main fin, and the lug of the auxiliary fin is flush with the lug of the main fin.

[0017] In one embodiment, in the gas dynamic pressure bearing, the end face where the extending end of the auxiliary fin is located is straight, broken line or arc-shaped.

[0018] In one embodiment, in the gas dynamic pressure bearing, when the number of the auxiliary fins is greater than two and the number of the main fins is also greater than two, the auxiliary fins in the middle layer are lower than the auxiliary fins on both sides.

[0019] In one embodiment, in the gas dynamic pressure bearing, the number of the auxiliary fins is more than two, the auxiliary fins are arranged on one side of the main fin, or the auxiliary fins are respectively arranged on both sides of the main fin.

[0020] In one embodiment, in the gas dynamic pressure bearing, the supporting foil is "L"-shaped, and the narrow groove is an "L"-shaped narrow groove; after the supporting foil is installed on the bearing sleeve, the supporting foil and the bearing sleeve are directly fixed through the "L"-shaped narrow groove.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. By directly inserting a flat sheet-like structure or an "L"-shaped bent supporting foil into the narrow groove of the bearing sleeve, the elastic supporting effect on the top foil can be achieved, and at the same time, there is a tendency of circumferential displacement;

[0023] 2. The bearing structure and manufacturing process are simple, with high stiffness and load-bearing capacity, and at the same time have good damping performance; for example, multiple contact areas between different supporting foils and the top foil provide good damping, and at the same time, the bearing is easy to change various parameters to obtain different bearing performances;

[0024] 3. The bearing is easy to change various parameters to obtain different bearing performances. For example, the circumferential stiffness distribution can be adjusted by adjusting the circumferential support spacing and the circumferential variation of the height of the auxiliary fins, and the axial stiffness distribution can be adjusted by axially dividing the main fins or changing the shape of the overhanging end of the auxiliary fins. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a gas dynamic pressure bearing with a flat sheet-like structure of the supporting foil in one embodiment;

[0026] Figure 2 For Figure 1 the exploded view of the gas dynamic pressure bearing in;

[0027] Figure 3 For Figure 1 the schematic structural diagram of the bearing sleeve of the gas dynamic pressure bearing in;

[0028] Figure 4 For Figure 1 the external shape structure diagram of the top foil of the gas dynamic pressure bearing in;

[0029] Figure 5a 、 5b are respectively Figure 1 schematic diagrams of two different structures of the supporting foil structure in

[0030] Figure 6 is a schematic diagram of a gas dynamic pressure bearing structure with a limit ring installed;

[0031] Figure 7 is Figure 6 the exploded view of the gas dynamic pressure bearing in

[0032] Figure 8 is Figure 6 the schematic diagram of the rotor structure corresponding to the gas dynamic pressure bearing;

[0033] Figure 9a is Figure 6 the partial schematic diagram of the supporting foil height when the gas dynamic pressure bearing is static;

[0034] Figure 9b is Figure 6 the partial schematic diagram of the supporting foil height when the gas dynamic pressure bearing is dynamic;

[0035] Figure 10 is a schematic diagram of a gas dynamic pressure bearing structure in another embodiment where the supporting foil includes a main fin and an auxiliary fin structure;

[0036] Figure 11 is Figure 10 the exploded view of the gas dynamic pressure bearing in

[0037] Figure 12a 、 12b are respectively Figure 8 schematic diagrams of two different structures of the supporting foil structure in

[0038] Figure 13a is a partial schematic diagram when the gas dynamic pressure bearing is static and the supporting foil includes a main fin and an auxiliary fin structure;

[0039] Figure 13b is a partial schematic diagram when the gas dynamic pressure bearing is dynamic and the supporting foil includes a main fin and an auxiliary fin structure;

[0040] Figure 14 is a schematic diagram of a gas dynamic pressure bearing structure in yet another embodiment where the supporting foil is of an "L" - shaped structure;

[0041] Figure 15 is Figure 14 the exploded view of the gas dynamic pressure bearing in

[0042] Figure 16Schematic diagram of the supporting foil structure with an “L” shape. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0044] Example 1

[0045] like Figures 1 to 4 As shown in Figures 5a and 5b, the gas dynamic pressure bearing 10 with fin-type supporting foil in this embodiment includes a bearing sleeve 300, a supporting foil group 200 composed of a plurality of fin-type supporting foils 210, and a hollow cylindrical top foil 100. The bearing sleeve 300 is a cylindrical structure, and the height of the bearing sleeve 300 is consistent with the height of the top foil 100. A plurality of narrow grooves 320 are opened on the inner wall of the bearing sleeve 300. These narrow grooves 320 are arranged in a clockwise direction along the inner wall of the bearing sleeve 300 in a circumferential direction and at an acute angle β relative to the radial axis OX, and the arc angles of two adjacent narrow grooves 320 are equal, and the depth of each narrow groove 320 in the bearing sleeve 300 is equal, that is, the bottom of the narrow groove 320 opened in the bearing sleeve 300 is located on a concentric circle.

[0046] The fin-type supporting foil group 200 is composed of a plurality of fin-type supporting foils 210 , and each fin-type supporting foil 210 includes an embedded end 212 and an extended end 211 .

[0047] The supporting foil 210 is a flat sheet structure, and accordingly, the narrow groove 320 is a straight groove; a lug 202 is respectively provided at the two axial ends of the supporting foil 210. The number of the supporting foils 210 is one less than the number of the narrow grooves 320; that is, after the embedded ends 212 of all the supporting foils 210 are inserted into the narrow grooves 320, there is still one narrow groove 320 left for fixing the top foil 100. At this time, the extended end 211 of each supporting foil 210 extends toward the middle through hole 310 of the bearing sleeve 300 and contacts the outer wall of the top foil 100 placed in the middle through hole 310 of the bearing sleeve 300.

[0048] The top foil 100 is an open ring column formed by a thin sheet, and the top foil 100 includes a fixed end 120 and a free end 110. The fixed end 120 is bent outward and tilted to be embedded in a narrow groove 320 in the bearing sleeve 300, and the top foil 100 is fixedly connected to the bearing sleeve 300. The free end 110 of the top foil 100 is close to the fixed end 120, and a certain gap is reserved. In this way, the outer wall of the top foil 100 with an open arc surface overlaps with the extended end 211 of the supporting foil 210, and the inner wall side of the top foil 100 forms an air film gap with the rotating shaft to be inserted.

[0049] Besides being inserted into a narrow groove 320 of the bearing sleeve 300 by embedding, the fixed end 120 of the top foil 100 may also be connected to the bearing sleeve by other means.

[0050] Preferably, the supporting foil 210 with the flat sheet structure has a plurality of notches 201 longitudinally formed along the straight edge of the extending end 211 of each supporting foil 210. These notches 210 divide the cutting edge where the extending end 211 of the supporting foil 210 is located into multiple small segments, and the axial length of each segment can be designed according to requirements to form different axial stiffness distributions.

[0051] Generally, the supporting foil 210 and the corresponding narrow grooves on the bearing sleeve 300 are evenly distributed in the circumferential direction to obtain a uniform stiffness distribution.

[0052] Preferably, the above-mentioned supporting foils 210 start from the fixed end 120 and end at the free end 110 of the top foil 100 respectively. According to the arrangement pitch that first decreases and then increases, the extending end 211 of each supporting foil 210 is fixedly arranged on the outer wall of the top foil 100, and the density of the supporting foils 210 arranged in the middle region of the outer wall of the top foil 100 is relatively denser than that of the supporting foils arranged in other regions of the outer wall of the top foil 100, so as to achieve the effect that the fins in the main bearing area in the middle are more densely distributed. Therefore, the stiffness of this area is larger to adapt to the bearing load distribution law.

[0053] Such as Figure 6 and 7 As shown, for the fin-shaped supporting foil 210 with the flat sheet structure, a lug 202 is provided at each of the two axial ends of the embedding end 212. When the supporting foil is installed in the narrow groove, a limiting ring 400 for limiting is installed on the axial end face of the bearing sleeve 300, that is, the plane where XOY is located. The lug 202 is exposed on the axial end face of the bearing sleeve 300, and the limiting ring 400 is fitted and clamped between the lug 202 and the top foil 100, and the limiting ring 400 fixes the supporting foil group 200 and the bearing sleeve 300 together.

[0054] Specifically, the limiting ring 400 is a circular ring sheet structure, and a plurality of convex columns 410 are provided on the outer periphery. The arc angles between adjacent convex columns 410 are equal, and a limiting hole 411 is formed on each convex column 410. During installation, the limiting ring 400 is fitted and clamped between the lug 202 and the top foil 100, the limiting hole 411 on each convex column 410 is fitted and clamped into the lug 20 of the corresponding supporting foil 210, and the two side edges of each convex column 410 are adaptively clamped into the gap between two adjacent supporting foils 210; in this way, the limiting ring 400 can fix the supporting foil group 200 and the bearing sleeve 300 together.

[0055] The extending ends 211 of the supporting foils 210 in contact with the top foil 100 are of the same height in the radial direction. After the top foil 100 is assembled, it maintains a cylindrical shape, and its effect is similar to that of the top foil of a traditional wave foil bearing; or

[0056] Such asFigure 8 , 9a As shown in FIGS. 9a, 9b, the extending ends 211 of the respective supporting foil pieces 210 in contact with the top foil 100 vary circumferentially in height. After the top foil 100 is assembled and comes into contact with the extending ends 211 of the respective supporting foil pieces 210, a plurality of wedge-shaped gaps are formed between it and the rotor; and when the period of this height change is short, the top foil 100 cannot come into contact with the extending ends 211 of all the respective supporting foil pieces 210 in the initial state, and some regions are initially suspended. When a certain load is applied, the extending ends 211 of the respective supporting foil pieces 210 in these regions come into contact with the top foil 100. Therefore, it has a non-linear stiffness.

[0057] Therefore, when this bearing bears a load, the extending ends 211 of the supporting foil pieces 210 will undergo bending deformation, and at the same time, the extending ends 211 will also undergo circumferential slip relative to the top foil 100; compared with a wave foil bearing, the deformation and slip of the fin-shaped supporting foil pieces 210 are not affected by adjacent fins.

[0058] Embodiment 2

[0059] As Figure 10 , 11 As shown in FIGS. 12a and 12b, the difference between this embodiment and Embodiment 1 lies in: the supporting foil pieces 210 are different. Specifically as follows:

[0060] Each supporting foil piece 210 includes a main fin 230 and a plurality of auxiliary fins 220; during installation, one main fin 230 and a plurality of auxiliary fins 220 are installed as a group in a narrow groove 320 of the bearing housing 300.

[0061] Both the main fin 230 and the multiple auxiliary fins 220 have an embedded end 212 and an extended end 211 (since the embedded ends of the main fin 230 and the auxiliary fins 220 have the same structure and function, in this embodiment, the same identification number is used, e.g., the embedded end 212; of course, on the premise of no ambiguity, the identification of the embedded end of the auxiliary fin 220 can also use other identification numbers, e.g., 212', 212a, etc.). The embedded end 212 of the auxiliary fin 220 is flush and fitted with the embedded end 212 of the main fin 230, and the extended end 211' of the auxiliary fin 220 is closely arranged adjacent to and in contact with the extended end 211 of the main fin 230. The extended end 211' of the auxiliary fin 220 and the extended end 211 of the main fin 230 can both be in contact with the outer wall of the top foil 100, or the extended end 211 of the main fin 230 can be in contact with the outer wall of the top foil 100 while the extended end 211' of the auxiliary fin 220 is not in contact with the outer wall of the top foil 100. Additionally, the lug 202 of the auxiliary fin 220 and the lug 202 of the main fin 230 (since the lugs of the main fin 230 and the auxiliary fins 220 have the same structure, size, and function, in this embodiment, the same identification number is used, e.g., the lug 202; of course, on the premise of no ambiguity, the identification of the lug of the auxiliary fin 220 can also use other identification numbers, e.g., 202', 202a, etc.) are adaptively and flushly fitted.

[0062] The above-mentioned main fin 230 has the same structure as the flat sheet-shaped supporting foil 210 in Embodiment 1, and the embedded end of the auxiliary fin 220 is the same as that of the main fin 230, both being straight-line type. The end face where the extended end 211' of the auxiliary fin 220 is located can be straight-line type, broken-line type, arc type, etc. In the normal state, the distance between the auxiliary fins is smaller than that of the main fin, but the extended end 211' of the auxiliary fin 220 also needs to be exposed outside the inner wall of the bearing sleeve 300, that is, placed in the middle through hole 310 of the bearing sleeve 300.

[0063] The extended end 211' of the auxiliary fin 220 is a straight edge and is supported on the waist of the extended end 211 of the main fin 230 to improve the supporting stiffness of the main fin 230. Moreover, the height of the auxiliary fin 230 will also affect the supporting stiffness. Therefore, along the circumferential direction, the auxiliary fin 230 can be set to change its height according to a certain rule to achieve the purpose of variable stiffness distribution.

[0064] The extended end 211' of the auxiliary fin 220 is a broken-line edge or a curved edge. Different forms of edges can form different axial stiffness distributions, and the main purpose is to enhance the supporting stiffness in the middle region.

[0065] Since the number of the auxiliary fins 230 is more than one, i.e., two or more, at this time, all the auxiliary fins 220 can be arranged on the same side of the main fin 230, or multiple auxiliary fins 220 can be respectively arranged on both sides of the main fin 230.

[0066] Specifically, as Figure 13a and 13a shown, when the number of main fins 230 and auxiliary fins 220 is greater than two, the auxiliary fins 220 do not necessarily arrange in order of height. The auxiliary fins 220 in the middle layer can be lower than the auxiliary fins 220 on both sides. After the main fin 230 undergoes a certain bending deformation, it contacts the extension ends 211' of some auxiliary fins 220, and the effect of non-linear stiffness can be achieved. In this way, during the bending deformation process of the fin group composed of the main fin 230 and the auxiliary fins 220, slippage will occur between layers, having a damping effect.

[0067] Embodiment 3

[0068] As Figure 14 、 15 and 16 shown, the difference from Embodiment 1 is that:

[0069] The supporting foil 211 changes from a flat square sheet structure to an "L"-shaped structure. Correspondingly, the narrow groove 320 opened on the bearing sleeve 300 is also of an "L"-shaped structure. During assembly, the "L"-shaped supporting foil 211 is fitted and embedded into the "L"-shaped narrow groove of the bearing sleeve 300, and this "L"-shaped supporting foil 211 can directly play a limiting role, and there is no need to set a limiting ring 400 to prevent the supporting foil 211 from loosening out of the bearing sleeve 300.

[0070] It should be understood that the above description of the preferred embodiments of the present invention is relatively detailed, and it should not be considered as a limitation to the patent protection scope of the present invention. The patent protection scope of the present invention shall be subject to the appended claims.

Claims

1. A gas dynamic pressure bearing having a fin-type supporting foil, characterized in that, It includes a cylindrical bearing sleeve, a plurality of fin-shaped supporting foils and a hollow cylindrical top foil; wherein: The inner wall of the bearing sleeve is provided with a plurality of narrow grooves, and the adjacent narrow grooves are evenly distributed at equal arc angle intervals along the clockwise direction on the inner wall of the bearing sleeve, and each of the narrow grooves forms an acute angle with the radial surface of the bearing sleeve; Each of the supporting foils comprises an embedded end and an extended end, wherein the embedded end is correspondingly embedded in the narrow groove, and the extended end of the supporting foil extends toward the through hole of the bearing sleeve and contacts the outer wall of the top foil disposed in the through hole of the bearing sleeve; The top foil is an open ring column, and the top foil includes a fixed end and a free end, the fixed end is bent outward and tilted and then embedded in a narrow groove of the bearing sleeve, and the free end is close to the fixed end; The supporting foils take the fixed end and the free end of the top foil as the starting point and the end point respectively, and the extended end of each supporting foil is fixedly arranged on the outer wall of the top foil in the order of decreasing and then increasing arrangement spacing, and the supporting foils arranged in the middle area of ​​the outer wall of the top foil are relatively denser than the supporting foils arranged in other areas of the outer wall of the top foil, and the supporting foils are of a straight sheet structure or an "L" shape.

2. The hydrodynamic bearing according to claim 1, characterized in that, When the supporting foil is "L"-shaped, the narrow groove is an "L"-shaped narrow groove; after the supporting foil is installed on the bearing sleeve, the supporting foil and the bearing sleeve are directly fixed through the "L"-shaped narrow groove.

3. A gas dynamic pressure bearing with a finned support foil, characterized in that, It includes a cylindrical bearing sleeve, a plurality of fin-shaped supporting foils and a hollow cylindrical top foil; wherein: The inner wall of the bearing sleeve is provided with a plurality of narrow grooves, and the adjacent narrow grooves are evenly distributed at equal arc angle intervals along the clockwise direction on the inner wall of the bearing sleeve, and each of the narrow grooves forms an acute angle with the radial surface of the bearing sleeve; Each of the supporting foils comprises an embedded end and an extended end, wherein the embedded end is correspondingly embedded in the narrow groove, and the extended end of the supporting foil extends toward the through hole of the bearing sleeve and contacts the outer wall of the top foil disposed in the through hole of the bearing sleeve; The top foil is an open ring column, and the top foil includes a fixed end and a free end, the fixed end is bent outward and tilted and then embedded in a narrow groove of the bearing sleeve, and the free end is close to the fixed end; The supporting foil is a flat sheet structure, and the narrow groove is a straight groove; a lug is respectively provided at the two axial ends of the supporting foil. After the supporting foil is installed in the narrow groove, a limiting ring is installed on the axial end face of the bearing sleeve to play a limiting role. The lug is exposed on the axial end face of the bearing sleeve, and the limiting ring is adapted to be inserted between the lug and the top foil.

4. The gas dynamic pressure bearing according to claim 3, wherein, The supporting foil is in a straight sheet-like structure, and a plurality of notches are formed on the straight side of the extending end along the longitudinal direction.

5. The hydrodynamic gas bearing according to claim 3 or 4, characterized in that, Each of the supporting foils comprises a main fin and a plurality of auxiliary fins; the embedded end of the auxiliary fin is flush with the embedded end of the main fin, the extended end of the auxiliary fin is closely adjacent to the extended end of the main fin, and the lug of the auxiliary fin is flush with the lug of the main fin.

6. The hydrodynamic gas bearing according to claim 5, characterized in that, The end surface where the extension end of the auxiliary fin is located is straight line type, broken line type or arc type.

7. The hydrodynamic gas bearing according to claim 5, wherein When the number of the auxiliary fins and the number of the main fins are more than two, the auxiliary fins in the middle layer are lower than the auxiliary fins on both sides.

8. The hydrodynamic gas bearing according to claim 5, characterized in that, The number of the auxiliary fins is more than two, and the auxiliary fins are arranged on one side of the main fin, or the auxiliary fins are respectively arranged on both sides of the main fin.

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