Air foil dynamic pressure bearing

Abstract

The present invention discloses an air foil hydrodynamic bearing, which relates to the technical field of bearings. The air foil hydrodynamic bearing includes a bearing, a shaft neck matched with the bearing, and the bearing includes a body, and also includes: at least three pressure plates, the pressure plates are evenly spaced and arranged on the inner cylindrical surface of the body; an elastic film, the elastic film is arranged on the inner cylindrical surface of the body through the pressure plate; a cylindrical cavity, the cylindrical cavity is arranged between two adjacent pressure plates on the inner cylindrical surface of the body; the number of the cylindrical cavities corresponds to the number of pressure plates; a driving member, the driving member is arranged in the cylindrical cavity. The present invention acts on the thrust hemisphere through the elongation and contraction of the piezoelectric ceramic driver, promotes the radial movement of the film plane, and further drives the radial movement of the pad block, thereby realizing active control of the size of the pad gap, thereby controlling the size of the air film pressure, which can be used to improve the rotation accuracy of the journal, suppress the journal vibration and actively control the axis trajectory.

Description

Technical Field

[0001] The invention relates to the technical field of bearings, and in particular to an air foil dynamic pressure bearing. Background Art

[0002] Air dynamic pressure bearing is a kind of sliding bearing. Its structure and working principle are similar to those of liquid sliding bearing, but it uses gas as lubricating medium. Air dynamic pressure bearing has the characteristics of low friction, wide applicable speed range and wide applicable temperature range, and has begun to be applied to various fields, such as various high-speed motors, high-speed spindles and engines. The use of air dynamic pressure shaft improves the speed and work efficiency of the system in these fields, and the prospects are very broad.

[0003] The foil type dynamic pressure air bearing is a type of air dynamic pressure bearing. It is made of thin foil material and does not require external pressure supply during operation. Relying on the viscosity of the gas, the rotating shaft brings the gas into a convergent wedge formed between the shaft and the foil. It converts the dynamic pressure head of the gas into pressure, forming an air film with a pressure-supporting pressure to support the rotation of the shaft. The characteristics of the foil type air dynamic pressure bearing are long life and reliable operation. Even if a failure occurs, it will not have a destructive effect on the rotor. It does not require lubrication, and its load capacity increases with the increase of the speed.

[0004] At present, some existing air foil dynamic pressure bearings have low rotation accuracy, and the journal is prone to vibration, resulting in the deviation of the axis trajectory. How to solve the above technical problems is a technical problem that needs to be solved in the current bearing technology field. Summary of the invention

[0005] In view of the above technical problems, an embodiment of the present invention provides an air foil dynamic pressure bearing to solve the problems raised in the above background technology.

[0006] The present invention provides the following technical solution: an air foil dynamic pressure bearing, comprising a bearing, a journal matched with the bearing, the bearing comprising a body, and further comprising:

[0007] At least three pressing plates, the pressing plates being evenly spaced and arranged on the inner cylindrical surface of the body;

[0008] An elastic film, the elastic film is surrounded by a pressing plate and arranged on the inner cylindrical surface of the main body;

[0009] A cylindrical cavity, wherein the cylindrical cavity is arranged between two adjacent pressing plates on the cylindrical surface of the body; the number of the cylindrical cavities corresponds to the number of pressing plates;

[0010] A driving member, wherein the driving member is disposed in the cylindrical cavity;

[0011] A push block, wherein the push block is disposed on the driving member, and the driving member and the elastic film are connected via the push block;

[0012] The cushion block is arranged on the elastic film, and a foil group is arranged on the cushion block, and an air cushion gap is formed between the foil group and the shaft journal.

[0013] Preferably, the foil group includes an arched corrugated foil, a flat foil A and a flat foil B, and a slot A and a slot B are formed on the gasket; the ends on the same side of the arched corrugated foil and the flat foil B are fixed in the slot A, and one end of the flat foil A is fixed in the slot B, the arched corrugated foil is used to support the flat foil A and the flat foil B, and an air cushion gap is formed between the flat foil B and the shaft neck.

[0014] Preferably, the foil set comprises an arched corrugated foil, a slot A is formed on the cushion block, one end of the arched corrugated foil is fixed in the slot A; and an air cushion gap is formed between the arched corrugated foil and the shaft neck.

[0015] Preferably, the elastic film forms a film connection position at the pressure plate connection position, and forms a film plane between two adjacent pressure plates, and the cushion block is arranged on the film plane.

[0016] Preferably, the driving element is a piezoelectric ceramic driver.

[0017] Preferably, the push block is a thrust hemisphere.

[0018] Preferably, a threaded hole A is formed on the outer cylindrical surface of the main body at a position corresponding to the cylindrical cavity, and a bolt is arranged in the threaded hole A.

[0019] Preferably, the elastic film is connected to the cushion block via a flexible hinge A and a flexible hinge B.

[0020] Preferably, the pressure plate includes a pressure plate arm and two fixed ends, threaded holes B are formed on the fixed ends, and the pressure plate is connected to the annular groove A on the body by bolts.

[0021] Preferably, an annular groove B is formed on the outer cylindrical surface of the main body, and the annular groove B is used for assembling the bearing and the bearing seat.

[0022] An air foil dynamic pressure bearing provided by an embodiment of the present invention has the following beneficial effects:

[0023] (1) The present invention acts on the thrust hemisphere through the extension and contraction of the piezoelectric ceramic driver, pushing the film plane to move radially, further driving the pad to move radially, and realizing active control of the pad gap size, thereby controlling the size of the air film pressure, which can be used to improve the rotation accuracy of the journal, suppress the journal vibration and actively control the axis trajectory;

[0024] (2) A flexible hinge is provided on the elastic film to further improve the sensitivity of the active control pad;

[0025] (3) The foil set and the gasket are detachably fixedly connected, so when the foil is worn, the foil set can be easily replaced, which is simple, convenient and cost-saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of an air foil dynamic pressure bearing of the present invention;

[0027] Figure 2 A transverse cross-sectional view of an air foil dynamic pressure bearing of the present invention;

[0028] Figure 3 An axial view of an air foil hydrodynamic bearing of the present invention;

[0029] Figure 4 It is a structural schematic diagram of the pressing plate of the present invention;

[0030] Figure 5 It is a schematic diagram of the structure of a foil group of the present invention;

[0031] Figure 6 is another schematic diagram of the structure of a foil assembly of the present invention;

[0032] In the figure, 1 is a bearing; 11 is a body; 111 is a threaded hole A; 112 is a cylindrical cavity; 113 is an annular groove A; 114 is annular groove B; 12 is an elastic film; 121 is a flexible hinge A; 122 is a flexible hinge B; 123 is a film plane; 124 is a film connection position; 13 is a pressure plate; 131 is a pressure plate arm; 132 is a fixed end; 133 is a threaded hole B; 14 is a thrust hemisphere; 15 is a piezoelectric ceramic driver; 16 is a bolt; 17 is a spacer; 171 is a fixed plane; 172 is an arc surface; 173 is a slot A; 174 is a slot B; 18 is a foil group; 181 is an arched corrugated foil; 182 is an end A; 183 is a flat foil A; 184 is an end B; 185 is a flat foil B; 186 is an end C; 2-18 is an air cushion gap; 2 is a journal. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] Example 1, see Figure 1-Figure 4 , Figure 1 It is a structural schematic diagram of an air foil dynamic pressure bearing of the present invention; Figure 2 A transverse cross-sectional view of an air foil dynamic pressure bearing of the present invention; Figure 3 An axial view of an air foil hydrodynamic bearing of the present invention; Figure 4 It is a schematic structural diagram of the pressing plate of the present invention.

[0035] An air foil dynamic pressure bearing comprises a bearing 1 and a journal 2 matched with the bearing 1. The bearing 1 comprises a body 11 and further comprises:

[0036] At least three pressing plates 13, the pressing plates 13 are evenly spaced and arranged on the inner cylindrical surface of the body 11;

[0037] An elastic film 12, wherein the elastic film 12 is surrounded by a pressing plate 13 and disposed on the inner cylindrical surface of the body 11, wherein the elastic film 12 forms a film connection position 124 at a connection position of the pressing plate 13, and forms a film plane 123 between two adjacent pressing plates 13;

[0038] A cylindrical cavity 112, wherein the cylindrical cavity 112 is disposed between two adjacent pressing plates 13 on the inner cylindrical surface of the body 11; the number of the cylindrical cavities 112 corresponds to the number of the pressing plates 13;

[0039] A driving member 15, wherein the driving member 15 is disposed in the cylindrical cavity 112;

[0040] A push block 14, wherein the push block 14 is disposed on the driving member 15, and the driving member 15 and the elastic film 12 are connected via the push block 14;

[0041] The cushion block 17 is arranged on the elastic film 12 , and a foil group 18 is arranged on the cushion block 17 , and an air cushion gap 2 - 18 is formed between the foil group 18 and the journal 2 .

[0042] Preferably, the driving member 15 is a piezoelectric ceramic driver.

[0043] Preferably, the push block 14 is a thrust hemisphere.

[0044] It should be noted that the contact between the thrust hemisphere and the film plane 123 is point contact. In actual operation, the contact point can be adaptively adjusted according to the applied load and processing and assembly errors. At the same time, the lateral friction between the thrust hemisphere and the film plane is greatly reduced.

[0045] The pad 17 comprises a fixing plane 171 and an arc surface 172 . The pad 17 is connected to the film plane 123 via the fixing plane 171 . The fixing plane 171 and the film plane 123 are connected by gluing or welding. The foil assembly 18 is fixed on the arc surface 172 of the pad 17 .

[0046] The method of using an air foil hydrodynamic bearing of the present invention is as follows: when working, the piezoelectric ceramic driver 12 is extended and shortened to act on the thrust hemisphere 14, pushing the film plane 123 to move radially, further driving the pad 17 to move radially, realizing active control of the size of the air cushion gap 2-18, and then actively controlling the convergence gap 2-18, which can be used to improve the rotation accuracy of the journal, suppress the journal vibration and actively control the axis trajectory.

[0047] It should be noted that in the foil hydrodynamic bearing, an air film gap is formed between the foil and the journal. After the startup process, the air film gap often becomes a converging wedge-shaped gap. In the wedge-shaped gap, driven by the surface speed of the journal, a certain air dynamic pressure is formed to achieve the load-bearing effect. When the journal is subjected to an external static load, the size of the wedge-shaped gap changes, and then the air dynamic pressure changes, reaching a new equilibrium position under the new external load to achieve stable operation. When the journal is subjected to an external dynamic load, the air dynamic pressure in the wedge-shaped gap generates dynamic stiffness and damping to resist the external dynamic load.

[0048] It can be seen that at a certain journal speed, the size of the air dynamic pressure is determined by the size of the air film gap between the foil and the journal. The air film gap is a key factor in determining the static and dynamic characteristics and motion accuracy of the foil hydrodynamic bearing.

[0049] The air foil dynamic pressure shaft of the present invention controls the size of the air film pressure by actively changing the thrust of each pad 17 on the journal, thereby pushing the journal to move radially in the direction of reducing the motion error, thereby achieving the effect of improving the journal rotation accuracy; based on this principle, it can also achieve the effects of suppressing journal vibration and actively controlling the axis trajectory.

[0050] Preferably, in the embodiment of the present invention, five evenly spaced pressure plates 13 are provided on the inner cylindrical surface of the main body 11, and after the elastic film 12 is fixed by the pressure plates 13, five film connection positions 124 and five film planes 123 are formed; five cylindrical cavities 112 are opened on the inner cylindrical surface of the main body 11, which are alternately and evenly arranged with the pressure plates 13, and a piezoelectric ceramic driver 15 is arranged in the cylindrical cavity 112; the piezoelectric ceramic driver 15 is connected to the film plane 123 by setting a thrust hemisphere 14.

[0051] An air cushion gap 2-18 is formed between the foil group 18 and the journal 2. By controlling the extension or contraction of the piezoelectric ceramic driver 15 to drive the cushion block 17 to move radially, the size of the air cushion gap 177 can be actively controlled.

[0052] Example 2, see Figure 5 ,in, Figure 5 It is a schematic diagram of the structure of a foil group of the present invention.

[0053] The foil set 18 includes an arched corrugated foil 181, a flat foil A183 and a flat foil B185, and the pad 17 is provided with a slot A173 and a slot B174;

[0054] The end A182 of one side of the arched corrugated foil 181 and the end C186 of one side of the flat foil B185 are both fixed in the slot A173, and the other end of the arched corrugated foil 181 and the other end of the flat foil B185 are both free ends;

[0055] One end B184 of the flat foil A183 is fixed in the slot B174, and the other end is a free end;

[0056] The arched corrugated foil 181 provides support for the flat foil A183 and the flat foil B185; an air cushion gap 2-18 is formed between the flat foil B185 and the journal 2, and the air cushion gap 2-18 is a converging wedge-shaped gap.

[0057] The foil group 18 of the present invention is composed of an arched corrugated foil 181, a flat foil A183 and a flat foil B185, which provide elastic support to each other. When the journal speed changes and causes the dynamic pressure to change, the arched corrugated foil 181, the flat foil A183 and the flat foil B185 can coordinate their actions and reach a balanced state at a new position, thereby improving the radial stiffness and radial damping effect of the air dynamic pressure bearing, and at the same time improving the vibration resistance and high-speed stability of the air dynamic pressure bearing.

[0058] We know that in the prior art, foil-type dynamic pressure air bearings are mostly fixed at one end and free at the other end, and the bearing sleeve is concentric inside and outside, resulting in a large amount of movement of the foil and a high take-off speed of the bearing. Due to the working characteristics of the dynamic pressure air bearing, the shaft will rub against the inner surface of the bearing foil during the start and stop stages. Therefore, after a certain period of operation, the bearing needs to be maintained or the foil needs to be replaced.

[0059] At present, the foil of the dynamic pressure air bearing is mostly fixed by welding. Once the foil is worn, the whole air bearing needs to be replaced, which causes waste and increases the cost of use.

[0060] The present invention discloses an air foil dynamic pressure bearing, in which a slot A173 and a slot B174 are formed on a cushion block 17, and the ends on the same side of an arched corrugated foil 181 and a flat foil B185 are fixedly inserted into the slot A173, and the end on one side of the flat foil A183 is fixedly inserted into the slot B174, thereby realizing a detachable fixed connection between the foil group 18 and the cushion block 17. When the foil is worn, the foil group can be easily replaced, which is simple, convenient and cost-saving.

[0061] Example 3, see Figure 6 ,in, Figure 6 It is another schematic diagram of the foil group structure of the present invention.

[0062] The foil set 18 includes an arched wave foil 181, and the spacer block 17 is provided with a slot A173.

[0063] One end portion A182 of the arched corrugated foil 181 is fixed in the slot A173, and the other end portion of the arched corrugated foil 181 is a free end;

[0064] An air cushion gap 2 - 18 is formed between the arched corrugated foil 181 and the journal 2 , and the air cushion gap 2 - 18 is a combination of a plurality of converging and diverging wedge-shaped gaps.

[0065] The foil group 18 of the present invention includes an arched corrugated foil 181. The design of the arched corrugated foil 181 can form a plurality of converging and diverging wedge-shaped gaps, forming dynamic pressure in each converging wedge-shaped gap and disappearing the dynamic pressure in each diverging wedge-shaped gap. Finally, an effect of alternating dynamic pressure along the circumferential direction is formed on each pad, thereby achieving the effect of improving the vibration resistance and high-speed stability of the air dynamic pressure bearing.

[0066] An air foil dynamic pressure bearing of the present invention has a slot A173 on a cushion block 17, and a side end A182 of an arched wave foil 181 is fixedly inserted into the slot A173, thereby realizing a detachable fixed connection between the foil group 18 and the cushion block 17. When the foil is worn, the foil group can be easily replaced, which is simple, convenient and cost-saving.

[0067] Furthermore, a threaded hole A111 is formed on the outer cylindrical surface of the body 11 at a position corresponding to the cylindrical cavity 112 , and a bolt 16 is arranged in the threaded hole A111 . The piezoelectric ceramic driver 15 can be replaced by removing the bolt 16 .

[0068] Furthermore, the elastic film 12 is connected to the cushion block 17 via the flexible hinge A121 and the flexible hinge B122. The deformation stiffness of the flexible hinge is extremely low, and the film is easily bent and deformed at the flexible hinge.

[0069] Furthermore, the pressure plate 13 includes a pressure plate arm 131 and two fixed ends 132, and a threaded hole B133 is formed on the fixed end 132. An annular groove A113 is formed at both ends of the main body 11, and a threaded hole C matching the threaded hole B133 is provided on the annular groove A113. The pressure plate 13 is connected to the annular groove A113 on the main body 11 by bolts.

[0070] Furthermore, an annular groove B114 is formed on the outer cylindrical surface of the body 11, and the annular groove B114 is used for assembling the bearing 1 and the bearing seat.

[0071] An air foil hydrodynamic bearing provided by an embodiment of the present invention has the following beneficial effects: the present invention acts on the thrust hemisphere through the elongation and contraction of the piezoelectric ceramic driver, thereby promoting the radial movement of the film plane, and further driving the radial movement of the pad, thereby realizing active control of the size of the pad gap, thereby controlling the size of the air film pressure, and can be used to improve the shaft neck rotation accuracy, suppress shaft neck vibration and actively control the axis trajectory; a flexible hinge is provided on the elastic film, which can further improve the sensitivity of the active control pad; the foil group and the pad are detachably fixedly connected, and when the foil is worn, the foil group can be conveniently replaced, which is simple, convenient and cost-saving.

[0072] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0073] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0074] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. An air foil dynamic pressure bearing, comprising a bearing (1), a journal (2) matched with the bearing (1), wherein the bearing (1) comprises a body (11), characterized in that: Also includes: At least three pressing plates (13), wherein the pressing plates (13) are evenly spaced and arranged on the inner cylindrical surface of the body (11); An elastic film (12), wherein the elastic film (12) is surrounded by a pressure plate (13) and arranged on the inner cylindrical surface of the body (11); A cylindrical cavity (112), wherein the cylindrical cavity (112) is disposed between two adjacent pressing plates (13) on the inner cylindrical surface of the body (11); the number of the cylindrical cavities (112) corresponds to the number of the pressing plates (13); A driving member (15), wherein the driving member (15) is disposed in the cylindrical cavity (112); the driving member (15) is a piezoelectric ceramic driver; A push block (14), wherein the push block (14) is arranged on a driving member (15), and the driving member (15) and the elastic film (12) are connected via the push block (14); the push block (14) is a thrust hemisphere; and the contact between the thrust hemisphere (14) and the film plane (123) is point contact; A cushion block (17), the cushion block (17) being arranged on the elastic film (12), a foil group (18) being arranged on the cushion block (17), and an air cushion gap (2-18) being formed between the foil group (18) and the shaft journal (2); The elastic film (12) forms a film connection position (124) at the connection position of the pressure plate (13), and forms a film plane (123) between two adjacent pressure plates (13), and the cushion block (17) is arranged on the film plane (123); The elastic film (12) is connected to the cushion block (17) via a flexible hinge A (121) and a flexible hinge B (122).

2. An air foil dynamic pressure bearing according to claim 1, characterized in that the foil group (18) includes an arched corrugated foil (181), a flat foil A (183) and a flat foil B (185), and the pad (17) is provided with a slot A (173) and a slot B (174); the ends of the arched corrugated foil (181) and the flat foil B (185) on the same side are fixed in the slot A (173), and one end of the flat foil A (183) is fixed in the slot B (174); the arched corrugated foil (181) is used to support the flat foil A (183) and the flat foil B (185), and an air cushion gap (2-18) is formed between the flat foil B (185) and the shaft neck (2).

3. An air foil dynamic pressure bearing according to claim 1, characterized in that the foil group (18) includes an arched corrugated foil (181), a slot A (173) is opened on the cushion block (17), one side end of the arched corrugated foil (181) is fixed in the slot A (173); and an air cushion gap (2-18) is formed between the arched corrugated foil (181) and the shaft neck (2).

4. An air foil dynamic pressure bearing according to claim 1, characterized in that a threaded hole A (111) is opened on the outer cylindrical surface of the body (11) at a position corresponding to the cylindrical cavity (112), and a bolt (16) is arranged in the threaded hole A (111).

5. An air foil dynamic pressure bearing according to claim 1, characterized in that the pressure plate (13) includes a pressure plate arm (131) and two fixed ends (132), a threaded hole B (133) is opened on the fixed end (132), and the pressure plate (13) is connected to the annular groove A (113) on the body (11) by bolts.

6. An air foil dynamic pressure bearing according to claim 1, characterized in that an annular groove B (114) is opened on the outer cylindrical surface of the body (11), and the annular groove B (114) is used for assembling the bearing (1) and the bearing seat.

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