CN115711260A - Foil-tilting pad porous gas radial bearing - Google Patents
Foil-tilting pad porous gas radial bearing Download PDFInfo
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- CN115711260A CN115711260A CN202211577358.1A CN202211577358A CN115711260A CN 115711260 A CN115711260 A CN 115711260A CN 202211577358 A CN202211577358 A CN 202211577358A CN 115711260 A CN115711260 A CN 115711260A
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Abstract
The invention discloses a foil-tilting pad porous gas radial bearing which comprises a bearing sleeve, a plurality of porous bearing pads and a foil structure, wherein the bearing sleeve comprises a bearing inner wall and a plurality of tilting pads, the middle parts of pad backs of the tilting pads are respectively connected with the bearing inner wall into a whole through flexible hinges, and the tilting pads are arranged at equal intervals along the circumferential direction; a porous bearing bush is arranged on the inner wall of each tilting pad; an air inlet is arranged on the bearing sleeve corresponding to each flexible hinge, the air inlet penetrates through the flexible hinge to be communicated with the inner wall surface of the corresponding tiltable tile, and a foil structure is arranged in a cavity formed by the two adjacent tiltable tiles, the flexible hinge and the inner wall of the bearing. The invention combines the advantages of a porous aerostatic bearing, a tilting pad aerodynamic bearing and a foil aerodynamic bearing, and has the advantages of large bearing capacity, high rigidity, good damping characteristic and capability of actively regulating and controlling the performance of the bearing.
Description
Technical Field
The invention belongs to the technical field of air bearings, and particularly relates to a foil-tilting pad porous gas radial bearing.
Background
In recent years, as the demand for high-speed rotating equipment that can operate under extreme operating conditions has increased in related fields such as power equipment, turbomachinery, and distributed energy, higher demands have been made on high-energy-density, high-efficiency bearing technology. Because the gas bearing uses low-viscosity gas as a lubricant, the rotating speed, the energy density and the efficiency of the rotating machinery can be greatly improved, and the gas bearing has wide application in high-rotating-speed turbines, air compressors, refrigeration compressors and micro-combustion engine systems.
The aerostatic bearing supplies high-pressure gas to the bearing by an external gas supply system, and the high-pressure gas forms a high-pressure gas film in a gap between the bearing and the rotor through a pressure equalizing groove by the external supply system, so that the rotating rotor is supported and lubricated. In order to ensure high load capacity, high stiffness and high energy density, it is desirable to minimize the clearance between the rotor and the bearing to ensure high pressure and uniformity of the lubricating film. Among them, the porous aerostatic bearing can obtain a lubricating gas film with good consistency by utilizing the pore characteristics of the porous material itself. Compared with other throttling type aerostatic bearings, the gas supply bearing has higher bearing capacity, higher rigidity characteristic and better damping characteristic due to large gas supply area and uniform gas pressure distribution.
However, bearing clearance is difficult to ensure under extreme operating conditions such as high load and high rotating speed, and the phenomenon of vortex instability is easy to occur under the condition of an extremely high DN value (product of rotating speed and shaft diameter) due to compressibility and nonlinearity of gas, so that the dynamic stability of the rotor is reduced, and the risk of high-speed rotor-bearing friction exists. The above-described conditions and potential risks restrict the use of aerostatic bearings at high rotational speeds.
The tilting pad aerodynamic bearing comprises a plurality of bearing bushes and bearing sleeves, wherein the bearing bushes and the bearing sleeves can rotate around pivots of the tilting pad aerodynamic bearing, the bearing bushes are connected through flexible supports, the bearing bushes can change deflection states in a self-adaptive air film force action mode, and further adapt to the running state of a rotor.
The foil structure is additionally arranged in the bearing sleeve of the foil aerodynamic bearing to serve as a supporting energy dissipation element, and the vibration energy of the rotor can be effectively absorbed and dissipated due to elastic deformation of the foils and coulomb friction generated by displacement among the foils. Has higher bearing capacity and stability, and is widely applied to small-sized high-rotating-speed rotating equipment in recent years.
However, in the start-stop stage of the foil gas dynamic pressure bearing, when the rotor speed is low and the gas dynamic pressure effect is weak, the rotor contacts with the top foil, so that friction and abrasion are generated; meanwhile, under the condition of extremely high rotating speed, the bearing capacity and the damping characteristic of the bearing depend on the elastic foil structure, the weight of a supported rotor is limited, and the power level of the equipment is limited.
Disclosure of Invention
In order to solve the above-mentioned technical problems, the present invention provides a foil-tilting pad porous gas radial bearing having a simple structure, a high capability of coping with a vortex instability phenomenon, and a good dynamic stability of the bearing.
The technical scheme adopted by the invention is as follows: a foil-tilting pad porous gas radial bearing comprises a bearing sleeve, a plurality of porous bearing pads and a foil structure, wherein the bearing sleeve comprises a bearing inner wall and a plurality of tilting pads, the middle parts of pad backs of the tilting pads are respectively connected with the bearing inner wall into a whole through flexible hinges, and the tilting pads are arranged at equal intervals along the circumferential direction; a porous bearing bush is arranged on the inner wall of each tilting pad; an air inlet is arranged on the bearing sleeve corresponding to each flexible hinge, the air inlet penetrates through the flexible hinge to be communicated with the inner wall of the corresponding tiltable tile, and a foil structure is arranged in a cavity defined by the adjacent tiltable tiles, the flexible hinge and the inner wall of the bearing.
Further, the bearing sleeve comprises 3, 4 or 5 tilting pads; a plurality of pressure equalizing grooves and communicating grooves are formed in the inner wall of the tilting pad and are communicated through the communicating grooves; the inner opening of the air inlet hole is arranged in the communicating groove.
Furthermore, two sides of each flexible hinge on the inner wall of the bearing are respectively provided with an inserting groove, and two ends of the foil structure are inserted into the inserting grooves.
Furthermore, the porous bearing bush is made of porous graphite; the radian of the porous bearing bush is the same as that of the tilting pad, and the porous bearing bush is adhered to the inner wall of the tilting pad through glue.
Further, the cross-sectional shape of the pressure equalizing groove is circular, rectangular, rhombic or semicircular.
Furthermore, two ends of the foil structure are provided with folded edges which are inserted into the slots; the foil structure sequentially comprises a viscoelastic top foil I, a viscoelastic top foil II, a multi-cantilever type foil and a viscoelastic top foil III from inside to outside; the viscoelastic top foil I, the viscoelastic top foil II, the viscoelastic top foil III and the multi-cantilever type foil are arc-shaped; the viscoelastic top foil I and the viscoelastic top foil II are fixed in opposite directions; the viscoelastic top foil III and the multi-cantilever type foil are arranged in the same direction along the slot; the multi-cantilever type foil is provided with a plurality of supporting parts, the supporting parts are in a dovetail shape, and the supporting parts are gradually reduced from the inserting grooves to the outer edge of the tilting pad.
Further, the materials of the viscoelastic top foil i, the viscoelastic top foil ii, and the viscoelastic top foil iii were heat-treated to obtain SUS301, and the surfaces thereof were coated with viscoelastic materials.
Compared with the prior art, the invention has the beneficial effects that: 1) The tilting pad is provided with the pressure equalizing groove, the bearing bush is a porous bearing bush, the external gas supply system provides high-pressure gas for the bearing, and the high-pressure gas is supplied from the outside and forms a high-pressure gas film in a gap between the bearing and the rotor through the pressure equalizing groove and the porous bearing bush, so that the rotating rotor is supported and lubricated, the supported rotor weight is improved, and the power level of the equipment is improved. The invention utilizes the pore characteristics of the porous material to obtain a lubricating gas film with good consistency, and the bearing capacity of the bearing is enhanced because the gas supply area is large and the gas pressure is uniformly distributed.
2) The invention adopts the tilting pad as the fixing structure of the porous bearing pad, so that the bearing pad can change the deflection state by self-adapting to the action of air film force, further adapt to the running state of the rotor, reduce the risk of collision and friction of the high-speed rotor and the bearing, and meanwhile, under the working condition such as extremely high DN (product of rotating speed and shaft diameter), the bearing clearance can be actively changed, adapt to the action of wedge effect, improve the capability of coping with the phenomenon of vortex instability and improve the dynamic stability of the bearing.
3) The foil structure comprises four layers of a viscoelastic top foil I, a viscoelastic top foil II, a viscoelastic top foil III and a multi-cantilever type foil, wherein the multilayer structure supports the tilting pad in parallel, so that the rigidity of the bearing is effectively improved, and the bearing capacity of the bearing is increased; because the elastic deformation of the foil structure can cause the relative displacement between layers, the vibration energy of the dissipative rotor can be effectively absorbed by means of coulomb friction energy generated between adjacent layers, the damping characteristic of the bearing can be obviously improved, the tilting pad resonance can be effectively prevented, and the stability of the bearing-rotor system is further improved.
4) The supporting part of the multi-cantilever type foil is designed into a dovetail shape, the size of a circumferential dovetail of the supporting part is gradually reduced from the slot to the outer edge of the tilting pad, and accordingly correspondingly changed supporting rigidity is obtained, deflection of the tilting pad is better adapted, and stability of a bearing-rotor system is facilitated. Under the condition of continuing the advantages of the tilting pad gas bearing, the invention increases the damping of the bearing, simultaneously does not limit the swing of the tilting pad, and improves the stability of a bearing-rotor system.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Fig. 2 is a schematic view of the structure of the bearing sleeve of the present invention.
Fig. 3 is a sectional view of the overall structure of the present invention.
FIG. 4 is a schematic structural view of a porous bushing according to the present invention.
FIG. 5 is a schematic diagram of the foil structure composition and its main shape parameters.
FIG. 6 is a schematic diagram of a multi-cantilever foil structure and its main shape parameters.
Fig. 7 is a schematic structural view of a five-lobe foil-tilting pad porous gas radial bearing.
Fig. 8 is a schematic structural view of a three-lobe foil-tilting pad porous gas radial bearing.
Detailed Description
The present invention is described in further detail below with reference to the attached drawing figures.
As shown in fig. 1-6, the present invention comprises a bearing housing 1, four porous bearing pads 2 (not limited to four, at least three, as shown in fig. 7 and 8, three, or five) and a foil structure 3, wherein the bearing housing 1 comprises a bearing inner wall 9 and a plurality of tilting pads 5, the middle parts of the pad backs of the tilting pads 5 are respectively connected with the bearing inner wall 9 through a flexible hinge 4, and the tilting pads 5 are arranged along the circumferential direction with equal intervals. The tilting pad 5 uses the flexible hinge 4 as a swing fulcrum, so that the porous bearing pad 2 can change the deflection state under the action of self-adaptive air film force. And the bearing clearance can be actively changed under the working conditions such as extremely high DN (product of rotating speed and shaft diameter), the wedge effect is adapted, the capability of coping with the phenomenon of vortex instability is improved, and the dynamic stability of the bearing is improved.
Each tilting pad inner wall 8 is provided with a porous bearing pad 2. The porous bearing bush 2 is made of porous graphite; the radian of the porous bearing bush 2 is the same as that of the tilting pad 5, and the porous bearing bush 2 is adhered and tightly attached to the inner wall 8 of the tilting pad through glue. The porous bush 2 utilizes the pore characteristics of the porous material itself to obtain a lubricating gas film with good consistency. The air supply area and the air pressure distribution uniformity are improved, and the bearing capacity of the bearing is further enhanced. An air inlet 6 is arranged on the bearing sleeve 1 corresponding to each flexible hinge 4, the air inlet 6 penetrates through the flexible hinge 4 and is communicated with the corresponding inclinable tile inner wall 8, and a foil structure 3 is arranged in a cavity formed by the adjacent inclinable tiles 5, the flexible hinge 4 and the bearing inner wall 9.
A plurality of pressure equalizing grooves 7 and communicating grooves are formed in the inner wall 8 of the tilting pad, and the pressure equalizing grooves 7 are communicated through the communicating grooves; the inner opening of the air inlet hole 6 is arranged in the communicating groove. The equalizing groove 7 and the communicating groove are both rectangular, and the equalizing groove 7 can also be circular, rhombic or semicircular. The air inlet holes 6 are uniformly distributed on 5 rectangular pressure equalizing grooves 7 which are equidistantly distributed along the circumference of the tilting pad 5 along the communication groove, so that stable air supply is ensured. The high-pressure gas forms a high-pressure gas film in the gap between the bearing and the rotor through the porous bearing bush 2, so that the rotating rotor is supported and lubricated, the supported rotor weight is improved, and the power level of the equipment is improved.
Two sides of each flexible hinge 4 on the inner wall 9 of the bearing are respectively provided with a slot 10, and two ends of the foil structure 3 are inserted into the slots 10; the foil structure 3 sequentially comprises a viscoelastic top foil I11, a viscoelastic top foil II 12, a multi-cantilever type foil 13 and a viscoelastic top foil III 14 from inside to outside; the viscoelastic top foil I11, the viscoelastic top foil II 12 and the viscoelastic top foil III 14 are made of SUS301 subjected to heat treatment, the surfaces of the SUS301 are coated with viscoelastic materials (acrylic polymers), and the viscoelastic foils can dissipate energy in the deformation process, so that the damping of the bearing can be further increased. The invention can adjust the clearance and pre-tighten the viscoelastic top foil I11, the viscoelastic top foil II 12 and the viscoelastic top foil III 14 in the radial direction by changing the thickness.
The viscoelastic top foil I11 is arranged between the viscoelastic top foil II 12 and the tilting pad 5 and is fixed with the viscoelastic top foil II 12 in the opposite direction; during the operation of the bearing, the viscoelastic top foil I11 and the viscoelastic top foil II 12 move in opposite directions, so that larger friction is generated, and the damping of the bearing is further increased. The viscoelastic top foil iii 14 is disposed between the multi-cantilever type foil 13 and the bearing inner wall 9, and is arranged in the same direction as the multi-cantilever type foil 13 along the slot 10. The multi-cantilever foil 13 has a plurality of supporting portions, each supporting portion has a dovetail shape, and the supporting portions become smaller from the insertion groove 10 to the outer edge of the tilting pad 3.
As shown in fig. 6, the multi-cantilever type foil 13 is first processed into a foil dovetail groove hollow structure by wire cutting, and then bent to form a multi-cantilever type structure. When the bearing runs, the dovetail groove of the multi-cantilever type foil 13 is in contact with the viscoelastic top foil III 14 and coulomb friction is generated, so that the damping can be further increased. Furthermore, the support of the multi-cantilever type foil 13 is designed in a dovetail shape, the size of the circumferential dovetail thereof becomes gradually smaller from the slot 10 to the outer edge of the tilt pad 5, thereby obtaining a correspondingly varying support stiffness to better accommodate the deflection of the tilt pad 5.
The foil structure 5 comprises four layers of a viscoelastic top foil I, a viscoelastic top foil II, a viscoelastic top foil III and a multi-cantilever type foil, and the tilting pads are supported in parallel in a multi-layer mode, so that the rigidity of the bearing is effectively improved, and the bearing capacity of the bearing is increased. Because the elastic deformation of the foil structure 5 can cause the relative displacement between the layers, the vibration energy of the dissipative rotor can be effectively absorbed by means of coulomb friction energy generated between the adjacent layers, the damping characteristic of the bearing can be obviously improved, the tilting pad resonance can be effectively prevented, and the stability of the bearing-rotor system can be further improved. The supporting part of the multi-cantilever type foil is designed into a dovetail shape, the size of the circumferential dovetail of the supporting part is gradually reduced from the slot to the outer edge of the tilting pad, and accordingly, the supporting rigidity is correspondingly changed, so that the deflection of the tilting pad is better adapted, and the stability of a bearing-rotor system is facilitated. Under the condition of continuing the advantages of the tilting pad gas bearing, the invention increases the damping of the bearing, simultaneously does not limit the swinging of the tilting pad, and improves the stability of the bearing-rotor system. The composite structure can improve the rotation precision, ensure the bearing capacity and rigidity and greatly improve the stability of the bearing-rotor system. In addition, the bearing can monitor the position of the rotor in real time by adding a sensor, and reduce the vibration of the rotor passing through the critical rotating speed by actively regulating and controlling the air supply quantity. The assembly mode of the invention can be that the gravity direction of the rotating shaft is over against the center of one tilting pad 5, and can also be that the gravity direction of the rotating shaft is over against the gap between two tilting pads.
Claims (7)
1. A foil-tilting pad porous gas radial bearing comprises a bearing sleeve (1), a plurality of porous bearing pads (2) and a foil structure (3), and is characterized in that: the bearing sleeve (1) comprises a bearing inner wall (9) and a plurality of tilting pads (5), the middle parts of pad backs of the tilting pads (5) are respectively connected with the bearing inner wall (9) into a whole through a flexible hinge (4), and the tilting pads (5) are arranged at equal intervals along the circumferential direction; the inner wall of each tilting pad (5) is provided with a porous bearing bush (2), the bearing sleeve (1) is provided with an air inlet hole (6) corresponding to each flexible hinge (4), the air inlet hole (6) penetrates through the flexible hinge (4) to be communicated with the corresponding tilting pad inner wall (8), and a foil structure (3) is arranged in a cavity gap defined by the two adjacent tilting pads (5), the flexible hinge (4) and the bearing inner wall (9).
2. The foil-tiltable pad porous gas radial bearing of claim 1, wherein: the bearing sleeve (1) comprises 3, 4 or 5 tilting pads (5); a plurality of pressure equalizing grooves (7) and communicating grooves are formed in the inner wall (8) of the tilting pad, and the pressure equalizing grooves (7) are communicated through the communicating grooves; the inner opening of the air inlet hole (6) is arranged in the communicating groove.
3. The foil-tileable pad porous gas radial bearing of claim 1, wherein: two sides of each flexible hinge (4) on the inner wall (9) of the bearing are respectively provided with a slot (10), and two ends of the foil structure (3) are inserted into the slots (10).
4. The foil-tileable pad porous gas radial bearing of claim 1, wherein: the porous bearing bush (2) is made of porous graphite; the radian of the porous bearing bush (2) is the same as that of the tilting pad (5), and the porous bearing bush (2) is adhered to the inner wall (8) of the tilting pad by glue.
5. The foil-tiltable pad porous gas radial bearing of claim 2, wherein: the cross section of the pressure equalizing groove (7) is circular, rectangular, rhombic or semicircular.
6. The foil-tiltable pad porous gas radial bearing of claim 1, wherein: two ends of the foil structure (3) are provided with folded edges which are inserted into the slots (10); the foil structure (3) sequentially comprises a viscoelastic top foil I (11), a viscoelastic top foil II (12), a multi-cantilever type foil (13) and a viscoelastic top foil III (14) from inside to outside; the viscoelastic top foil I (11) and the viscoelastic top foil II (12) are fixed in opposite directions; the viscoelastic top foil III (14) and the multi-cantilever type foil (13) are arranged along the same direction of the slot (10); the multi-cantilever type foil (13) is provided with a plurality of supporting parts, the supporting parts are in a dovetail shape, and the supporting parts are gradually reduced from the inserting grooves (10) to the outer edge of the tilting pad (5).
7. The foil-tileable pad porous gas radial bearing of claim 6, wherein: the viscoelastic top foil I (11), the viscoelastic top foil II (12) and the viscoelastic top foil III (14) are made of SUS301 after heat treatment, and the surfaces of the viscoelastic top foil I (11), the viscoelastic top foil II (12) and the viscoelastic top foil III (14) are coated with viscoelastic materials.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211577358.1A CN115711260A (en) | 2022-12-09 | 2022-12-09 | Foil-tilting pad porous gas radial bearing |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211577358.1A CN115711260A (en) | 2022-12-09 | 2022-12-09 | Foil-tilting pad porous gas radial bearing |
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| CN115711260A true CN115711260A (en) | 2023-02-24 |
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| CN202211577358.1A Pending CN115711260A (en) | 2022-12-09 | 2022-12-09 | Foil-tilting pad porous gas radial bearing |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118257787A (en) * | 2024-05-31 | 2024-06-28 | 武汉理工大学 | Water lubrication thrust bearing and performance test method |
-
2022
- 2022-12-09 CN CN202211577358.1A patent/CN115711260A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118257787A (en) * | 2024-05-31 | 2024-06-28 | 武汉理工大学 | Water lubrication thrust bearing and performance test method |
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