DESC:BUMPLESS LAYERED AIR FOIL BEARING CONFIGURATION BACKGROUND
Technical Field
[0001] The embodiments herein generally relate to a bearing, more particularly to a bumpless layered air foil bearing configuration for high-speed rotating applications with 5 contactless operation.
Description of the Related Art
[0002] High-speed applications such as automotive, power generation, power generation and rotating machinery typically speeds above 50000 Rotations Per Minute (RPM), demand specialized bearings to support rotating components and manage associated loads 10 effectively. Rolling element bearings are commonly used for those applications. However, the performance of the rolling element bearings at elevated speeds and temperatures necessitates superior materials, enhanced cooling mechanisms, and regular maintenance routines, which results in increased cost and complexity.
[0003] The rolling element bearings are highly sensitive to tolerances requiring a high 15 precision finish on both the shaft and bearing seating area, increasing the costs. Even at low temperatures or low speeds of operation, friction-induced heat may lead to bearing degradation, demanding periodic maintenance interventions. To address these challenges, researchers developed gas foil bearings including an encircling foil around a rotating shaft, supported by a compliant foil with bumps assembled in a rigid housing. The compliant foil is made of a 20 plurality of bumps of certain size with a desired stiffness.
[0004] FIG. 1 illustrates an air foil bearing 100 with a bump foil 106 according to a prior art. The air foil bearing 100 includes a bearing sleeve 102, a top foil 104, the bump foil 106, and a journal 108. The bump foil 106 is designed to fit within the bearing sleeve 102 and
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the top foil 104 with a desired stiffness of the bump foil 106 with a plurality of bumps. At high operational speeds of the air foil bearing 100, working medium acts as a lubricant, leading to low friction levels within the air foil bearing 100. Design and fabrication of the bump foil 106 within the air foil bearing 100 may be specific to particular applications considering factors such as load, speed and diameter, which requires different bump foils for different applications. 5 However, the bump foil 106 in the air foil bearing 100 do not inherently provide significant damping, which can lead to vibration issues at high speeds. Fabrication and manufacturing processes involved in creating the bump foil 106 are complex, requiring attention in detail to ensure optimal performance.
[0005] Accordingly, there remains a need for an air foil bearing configuration for high-10 speed rotating applications which are simpler in construction and helps in reducing vibration amplitudes.
SUMMARY
[0006] In view of the foregoing, an embodiment herein provides an air foil bearing configuration for high-speed rotating applications. The air foil bearing configuration includes 15 an air foil bearing housing including an encircling foil, one or more stacked inscribing foils, and one or more stacked bumpless foils. The encircling foil is configured to accommodate a rotating element. The one or more stacked inscribing foils is positioned within the air foil bearing housing. The one or more stacked bumpless foils is configured to integrate between the encircling foil and the one or more stacked inscribing foils. When the rotating element 20 initiates spinning at high speeds, the rotating element induces surrounding air pressure to exert a repulsive force on the encircling foil, enabling the rotating element to levitate, preventing contact with the encircling foil, and the repulsive force presses the encircling foil against one or more stacked bumpless foils, which enables the rotating element and the encircling foil to separate with a high pressure air generated due to the high speed rotation of the rotating element 25
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and viscosity effects, thereby resulting in non-contact of the rotating element from the encircling foil with minimal friction and reduced vibration amplitudes.
[0007] In some embodiments, the one or more stacked bumpless foils and the one or more stacked inscribing foils include one or more perforations.
[0008] In some embodiments, the one or more perforations of the one or more stacked 5 bumpless foils and the one or more stacked inscribing foils are filled with viscous medium to provide damping that reduces the vibration amplitudes of the rotating element in the high-speed rotating applications. The air foil bearing configuration provides damping due to cumulative effect of interlayer friction between layers of the one or more stacked bumpless foils and the one or more stacked inscribing foils, along with a presence of the viscous medium in the one 10 or more perforations.
[0009] In some embodiments, the air foil bearing housing includes a foil arrester that is configured to lock the encircling foil and the one or more stacked bumpless foils in a pre-determined position, and one or more foil locking fasteners are configured to lock the foil arrester in the pre-determined position. 15
[0010] In some embodiments, the one or more stacked bumpless foils includes a straight spread foil. The straight spread foil is adapted into one or more shapes based on requirements of the air foil bearing configuration.
[0011] In some embodiments, the air foil bearing configuration for the high-speed rotating applications can be modified with a combination of number of the one or more stacked 20 inscribed foils and the one or more stacked bumpless foils with a specified stiffness and diameters.
[0012] In some embodiments, the one or more stacked bumpless foils are configured to divide into one or more equal sides and one protruding side to form into any shape based on requirements of the air foil bearing configuration. 25
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[0013] In some embodiments, the one protruding side in the one or more stacked bumpless foils is configured to arrest the rotation of the one or more stacked bumpless foils.
[0014] The bumpless foil can be manufactured easily as a spread without any bumps. With a desired number of inscribed foils, the one or more bumpless foils can be nested or stacked within each other. The air foil bearing configuration may be used for various high-5 speed rotating applications including turbomachinery, electric motors, spindles, flywheels, turbines, engines, and the like. The viscous medium filled in the perforations provides external damping suppressing vibrations of the high-speed rotating applications.
[0015] The description that follows more particularly exemplifies illustrative embodiments. In several places throughout this description, guidance is provided through lists 10 of examples, that may be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. Thus, the scope of the present description should not be limited to the specific illustrative embodiments described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those embodiments. Any of the elements that are positively 15 recited in this description as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Although various theories and possibilities have been discussed herein, in no event should such discussions serve to limit the claimable subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS 20
[0016] The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
[0017] FIG. 1 illustrates an air foil bearing with a bump foil according to a prior art;
[0018] FIG. 2 illustrates a block diagram of an air foil bearing configuration for high-speed rotating applications according to some embodiments herein; 25
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[0019] FIG. 3 illustrates an exemplary view of the air foil bearing configuration of FIG. 2 with a bumpless foil and an inscribing foil according to some embodiments herein;
[0020] FIG. 4A-4B illustrate exemplary views of the bumpless foil of the air foil bearing configuration of FIG. 3 according to some embodiments herein;
[0021] FIG. 5A illustrates an exemplary view of one or more stacked bumpless foils 5 and one or more stacked inscribing foils in the air foil bearing configuration of FIG. 2 according to some embodiments herein;
[0022] FIG. 5B illustrates an exemplary view of one or more stacked bumpless foils with perforations and one or more stacked inscribing foils with perforations in the air foil bearing configuration of FIG. 2 according to some embodiments herein; and 10
[0023] FIG. 6 illustrates a graphical representation of frequency and vibration amplitude of a high-speed rotating application i.e. a rotor system with one or more stacked inscribing foils and one or more stacked bumpless foils, and one or more stacked bumpless foils with perforations and one or more stacked inscribing foils with perforations according to some embodiments herein. 15
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not 20 unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
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[0025] As mentioned, there is a need for an air foil bearing configuration for high-speed rotating applications with reduced vibrations. Referring now to the drawings, and more particularly to FIGS. 2 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0026] FIG. 2 illustrates a block diagram of an air foil bearing configuration 200 for 5 high-speed rotating applications according to some embodiments herein. The air foil bearing configuration 200 includes an air foil bearing housing 212 including an encircling foil 202, one or more stacked bumpless foils 204A-N, one or more stacked inscribing foils 206A-N, a foil arrester 208, and one or more foil locking fasteners 210A-N. The encircling foil 202 may be a circular foil. The encircling foil 202 is configured to accommodate a rotating element. In some 10 embodiments, the rotating element is inserted into the encircling foil 202. The rotating element may be a shaft of the high-speed rotating applications. The encircling foil 202 may include a wear resistant coating. The one or more stacked bumpless foils 204A-N is a compliant member that is configured to support the encircling foil 202. The one or more stacked bumpless foils 204A-N may be a straight spread foil that can be modified into any shapes based on 15 requirements of the air foil bearing configuration 200. In some embodiments, the one or more stacked bumpless foils 204A-N can be in a shape of polygon or hexagon. The one or more stacked inscribing foils 206A-N that is positioned within the air foil bearing housing 212, is configured to support the one or more stacked bumpless foils 204A-N. The one or more stacked bumpless foils 204A-N may be integrated within the encircling foil 202 and the one or more 20 stacked inscribing foils 206A-N.
[0027] When the rotating element initiates spinning at high speeds, the rotating element induces surrounding air pressure to exert a repulsive force on the encircling foil 202, enabling the rotating element to levitate, preventing contact with the encircling foil 202, and the repulsive force presses the encircling foil 202 against the one or more stacked bumpless foils 25
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204A-N, which enables the rotating element and the encircling foil 202 to separate with a high pressure air generated due to the high speed rotation of the rotating element and viscosity effects, thereby resulting in non-contact of the rotating element from the encircling foil 202 with minimal friction and reduced vibration amplitudes.
[0028] The one or more stacked bumpless foils 204A-N and the one or more stacked 5 inscribing foils 206A-N includes one or more perforations. The one or more perforations of the one or more stacked bumpless foils and the one or more stacked inscribing foils may be filled with viscous medium to provide damping that reduces the vibration amplitudes of the rotating element in the high-speed rotating applications.
[0029] The foil arrester 208 is configured to lock the encircling foil 202 and the one or 10 more stacked bumpless foils 204A-N in a pre-determined position. In some embodiments, the foil arrester 208 locks the encircling foil 202 and the one or more stacked bumpless foils 204A-N in an upright position. The one or more foil locking fasteners 210A-N is configured to lock the foil arrester 208 in the pre-determined position. The pre-determined position may be anywhere and will typically not impact the functionality of the air foil bearing configuration 15 200. The air foil bearing housing 212 is configured to house all components of the air foil bearing configuration 200. In some embodiments, the foil arrester 208 and the one or more foil locking fasteners 210A-N are locked in the pre-determined position inside the air foil bearing housing 212.
[0030] In some embodiments, the one or more stacked bumpless foils 204A-N can be 20 modified to any shapes based on desired level of symmetry in radial stiffness. Stiffness in the one or more stacked bumpless foils 204A-N may be achieved by varying sides or shape of the one or more stacked bumpless foils 204A-N, or varying thickness of the one or more stacked bumpless foils 204A-N, or number of layers in the one or more stacked bumpless foils 204A-N. 25
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[0031] FIG. 3 illustrates an exemplary view of the air foil bearing configuration 200 of FIG. 2 with a bumpless foil 302 and an inscribing foil 304 according to some embodiments herein. The air foil bearing configuration 200 includes the encircling foil 202, the bumpless foil 302, the inscribing foil 304, the foil arrester 208, the one or more foil locking fasteners 210A-N, and the air foil bearing housing 212. The functions and explanations of the air foil 5 bearing configuration 200 are explained above.
[0032] FIG. 4A-4B illustrate exemplary views of the bumpless foil 302 of the air foil bearing configuration 200 of FIG. 3 according to some embodiments herein. FIG. 4A illustrates the bumpless foil 302 as a spread with one or more sides 402A-N. In some embodiments, the bumpless foil 302 can be folded or wrapped into any shapes based on the requirements. For 10 example, the air foil bearing configuration 200 requires the bumpless foil 302 to be integrated within the encircling foil 202 and the inscribing foil 304, which requires the bumpless foil 302 in a shape of hexagon. The bumpless foil 302 may be divided with the one or more sides 402A-N to form the hexagon shape. In some embodiments, the bumpless foil 302 can be divided into six equal sides and one protruding side to arrest the rotation of the bumpless foil 302. FIG. 4B 15 illustrates the bumpless foil 302 of FIG. 4A in the hexagon shape to integrate within the air foil bearing configuration 200 of FIG. 3.
[0033] FIG. 5A illustrates an exemplary view of the one or more stacked bumpless foils 204A-N and the one or more stacked inscribing foils 206A-N in the air foil bearing configuration 200 of FIG. 2 according to some embodiments herein. The one or more stacked 20 bumpless foils 204A-N are configured to integrate within the encircling foil 202 and the one or more stacked inscribing foils 206A-N.
[0034] FIG. 5B illustrates an exemplary view of one or more stacked bumpless foils with perforations 502A-N and one or more stacked inscribing foils with perforations 504A-N in the air foil bearing configuration 200 of FIG. 2 according to some embodiments herein. The 25
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one or more stacked bumpless foils with perforations 502A-N are configured to integrate within the encircling foil 202 and the one or more stacked inscribing foils with perforations 504A-N. In some embodiments, the perforations can be filled with viscous medium. The viscous medium may be any of grease, lubricants, or sealants. The one or more stacked bumpless foils with perforations 502A-N and one or more stacked inscribing foils with perforations 504A-N 5 with the viscous medium provide additional damping that reduces vibration amplitudes during operations of the air foil bearing configuration 200.
[0035] FIG. 6 illustrates a graphical representation 600 of frequency and vibration amplitude of a high-speed rotating application i.e. a rotor system with the one or more stacked inscribing foils 206A-N and the one or more stacked bumpless foils 204A-N, and the one or 10 more stacked bumpless foils with perforations 502A-N and the one or more stacked inscribing foils with perforations 504A-N according to some embodiments herein. The graphical representation 600 includes an X-axis including a frequency of the rotor system, and a Y-axis including a vibration amplitude of the rotor system. The frequency of the rotor system may be in Hertz (Hz), and the vibration amplitude of the rotor system may be in millimeters (mm). The 15 one or more stacked bumpless foils with perforations 502A-N and the one or more stacked inscribing foils with perforations 504A-N can be filled with the viscous medium. The viscous medium may be grease. The graphical representation 600 depicts that the vibration amplitude reaches 0.79548 mm with the one or more stacked inscribing foils 206A-N and the one or more stacked bumpless foils 204A-N at a frequency in a range of 222.5Hz to 232.5Hz, and the 20 vibration amplitude reaches around 0.35 mm with the one or more stacked bumpless foils with perforations 502A-N and the one or more stacked inscribing foils with perforations 504A-N filled with the viscous medium including grease at a frequency in a range of 222.5Hz to 232.5Hz, resulting in significant reduction in the vibration amplitude for the rotor system.
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[0036] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the 5 disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope. ,CLAIMS:I/We Claim:
1. An air foil bearing configuration (200) for high-speed rotating applications, wherein the air foil bearing configuration (200) comprises,
an air foil bearing housing (212) comprising: 5
an encircling foil (202) that is configured to accommodate a rotating element;
a plurality of stacked inscribing foils (206A-N) that is positioned within the air foil bearing housing (212); and
characterized in that,
a plurality of stacked bumpless foils (204A-N) that is configured to integrate 10 between the encircling foil (202) and the plurality of stacked inscribing foils (206A-N),
wherein, when the rotating element initiates spinning at high speeds, the rotating element induces surrounding air pressure to exert a repulsive force on the encircling foil (202), enabling the rotating element to levitate, preventing contact of the encircling foil (202), and the repulsive force presses the encircling foil (202) against the plurality of stacked bumpless foils (204A-N), 15 which enables the rotating element and the encircling foil (202) to separate with a high pressure air generated due to the high speed rotation of the rotating element and viscosity effects, thereby resulting in non-contact of the rotating element from the encircling foil (202) with minimal friction and reduced vibration amplitudes
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2. The air foil bearing configuration (200) as claimed in claim 1, wherein the plurality of stacked bumpless foils (204A-N) and the plurality of stacked inscribing foils (206A-N) comprise a plurality of perforations.
3. The air foil bearing configuration (200) as claimed in claim 2, wherein the plurality of 25 perforations of the plurality of stacked bumpless foils and the plurality of stacked inscribing foils are filled with viscous medium to provide additional damping that reduces the vibration amplitudes of the rotating element in the high-speed rotating applications.
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4. The air foil bearing configuration (200) as claimed in claim 1, wherein the rotating element exerts the repulsive force on the encircling foil (202) when a pre-determined air pressure is formed which is dependent on the size and configuration of the air foil bearing.
5. The air foil bearing configuration (200) as claimed in claim 1, wherein the air foil 5 bearing housing (212) comprises,
a foil arrester (208) that is configured to lock the encircling foil (202) and the plurality of stacked bumpless foils (204A-N) in a pre-determined position; and
a plurality of foil locking fasteners (210A-N) are configured to lock the foil arrester (208) in the pre-determined position. 10
6. The air foil bearing configuration (200) as claimed in claim 1, wherein the plurality of stacked bumpless foils (204A-N) comprise a straight spread foil, wherein the straight spread foil is adapted into a plurality of shapes based on requirements of the air foil bearing configuration (200). 15
7. The air foil bearing configuration (200) as claimed in claim 1, wherein the air foil bearing configuration (200) for the high-speed rotating applications can be modified with a combination of number of the plurality of stacked inscribing foils (206A-N) and the plurality of stacked bumpless foils (204A-N) with a specified stiffness and diameters. 20
8. The air foil bearing configuration (200) as claimed in claim 1, wherein the plurality of stacked bumpless foils (204A-N) is configured to divide into one or more equal sides and one protruding side to form into any shape based on requirements of the air foil bearing configuration (200). 25
9. The air foil bearing configuration (200) as claimed in claim 8, wherein the one protruding side in the plurality of stacked bumpless foils (204A-N) is configured to arrest the rotation of the plurality of stacked bumpless foils (204A-N).