Description:AN AIR FOIL THRUST BEARING FOR HIGH-SPEED ROTATING MACHINES AND OPERATION METHOD THEREOF

FIELD OF INVENTION
The present invention generally relates to the field of mechanics. Specifically, the present invention relates to thrust bearings. Particularly, the present invention relates to air foil thrust bearing assembly. More particularly, the present invention relates to an axial air foil thrust bearing assembly for supporting high-speed rotating system.
BACKGROUND OF THE INVENTION
In general, thrust bearings are used to permit rotation between parts, particularly when under axial loading. In the oil and gas industry, for example, there are many situations which involve rotation between parts at high axial loads, and as such thrust bearings are commonly required, with the reliability of the bearings having a significant impact on successfully and efficiently performing operations.
In specific, mechanical thrust bearings are known, which typically include opposing bearing surfaces in rotary sliding contact, which may thus be subject to high wear rates, require lubrication and the like. The surface area of sliding contact may dictate the load capacity of the bearing, with larger loads typically accommodated with larger active bearing surface areas.
In particular, thrust bearings may be used in a wide variety of rotating machinery such as, but not limited to, pumps, turbines and motors. Thrust bearings limit axial movement of the rotating body that is subject to a force acting in a direction parallel to the axis of rotation. Thrust bearings, however, permit the rotation of the rotating body. Sources of axial thrust include the weight of a rotor or pressure differentials within a rotating machine. Additionally, a bearing is a mechanical part that secures the rotary shaft of a rotating machine while supporting a load applied to the shaft and shaft.
There are few of the patents available in the literature about the existence of thrust bearings.
EP0074847A1 discloses thrust bearing, the invention also includes two coaxial races (1,2) positioned on opposite sides of bearing means (3). An annular, one-piece element (4) of resilient material surrounds the races (1,2) and has integral, axially opposed, radially inwardly facing flanges (5) which retain the races (1,2) against axial outward movement. The one-piece annular element (4) also has a pair of axially outwardly facing sealing surfaces (8).
KR20190068970A discloses air foil bearing assembly, this invention also includes (i) a bearing housing having a hollow in which a rotating shaft is fitted, and having a hollow inner peripheral surface formed with a slot having both ends open to a front and rear side along an axial direction; (ii) a bump foil which forms a coupling part to be coupled to the slot, and which is installed in the hollow inner peripheral surface side; (iii) a top foil which forms a coupling part to be coupled to the slot, and which is installed in an inner side of the bump foil; and (iv) a stopper which is provided on the coupling part of one between the bump foil and the top foil, and preventing the coupling part of the bump foil and the top foil from being separated from the slot to the front and rear sides. Therefore, an objective of the present invention is to provide the air foil bearing assembly which can easily assemble a foil component to a bearing housing.
US10036279B2 discloses a thrust bearing, this invention including a bearing pad and a housing is provided. The bearing pad has a thrust face for supporting a vibration along an axial direction of the bearing. Additionally, the housing is formed integrally using an additive manufacturing process and is attached to or formed integrally with the bearing pad. The housing defines a working gas delivery system for providing a flow of pressurized working gas to the thrust face of the bearing pad and a fluid damper cavity. The fluid damper cavity provides a dampening of the axial vibration supported by the thrust face of the bearing pad along the axial direction.
WO2017086732A1 discloses an air foil bearing, the invention is configured such that the rigidity of bumps can be controlled by varying the width of single bumps, and has an advantage in managing the height of the bearing, since a wedge effect is realized only under the weight of an oil film as initial bumps all have the same height. Also, the present invention is capable of stably damping an impact exerted in the direction of the rotation axis of a rotor, improving bearing power, and minimizing an impact resulting from damping and has the effect of improving the durability of the air foil bearing.
KR100964883B1 discloses a thrust foil air bearing, this invention comprises: a thrust plate (60); and a bump foil (80) which is arranged in the upper side of the trust plate and wherein a saw foil (900) is arranged along the upper side of the bump foil. A lamp (990) is formed between the edge part (940) of the saw foil and the first bump (81) of the bump foil. The lamp accomplishes a curvature so that the centre be formed in the lower part and is horizontally contacted with the first bump of the bump foil.
Air foil thrust bearings (AFBs) are self-acting hydrodynamic complaint bearings, which typically use ambient air or gas as lubricants. When compared with traditional oil bearings and rolling bearings, AFBs have obvious advantages such as high reliability, extremely low friction during steady operation and excellent ability to operate at both high speeds and high temperatures.
Moreover, commonly used thrust bearing have bump foil and top foil to assemble a bearing. It focuses only on axially supporting rotating shaft at high speeds in a rotary machine, but more focus is read to improvising on design for manufacturing and enhancing the quality of cooling the thrust bearing while performing. Hence there is an urgent need in the state of art to develop a novel axial air foil bearing assembly for supporting high-speed rotating system to devoid from the above said drawbacks.
OBJECTIVE OF THE INVENTION:
The main objective of the present invention is to develop a novel air foil thrust bearing.
Another objective of the present invention is to develop a novel thrust bearing with high thrust load capacity, durable ease of assembly for serial production.
Another objective of the present invention is to develop an air foil thrust bearing assembly for enhancing load capacity at high-speed rotating system.
Another objective of the present invention is to develop an air foil thrust bearing assembly for manufacturability, assembly, and functionality.
Another objective of the present invention is to develop an air foil bearing assembly comprising five major components such as two or more carrier plates, two sub-assembly foils and spacer plate.
Yet another objective of the present invention is to develop a novel air foil bearing assembly with thermal management while thrust bearing works in continuous mobile phase.
Further objective of the present invention is to utilize the developed air foil bearing assembly for enhancing high-speed rotating system with high thrust loads thereof.
SUMMARY OF THE INVENTION:
According to the major aspect, the present invention discloses a novel air foil thrust bearing assembly (100), comprising:
a) two or more carrier plates (1) and (2);
b) two or more sub-assembly foils comprising top sub assembly (3) comprising a top foil (9) and bump foil (10), a bottom sub assembly (4) comprising a top foil (11) and bottom bump foil (12);
c) a spacer plate (5) ;
d) a rotating runner or thrust runner (6) ;
e) connecting units (7) comprising of dowel pins (7) and screws (8);
f) dowel insertion port (14);
g) outer integrated ring (15), and
h) cooling flow passages (16), in which two or more carrier plates (1,2) configured to remain stationary, host the two foil sub-assemblies (3, 4), aligned in opposite sides of the rotating runner (6), separated by spacer (5), and connected to external mounting housings by screws (8), in which the foil sub-assembly comprises;
a single piece 360-degree top foil sheet (9) & (11) and 360-degree bump foil sheet (10) & (12). (10,12), could be crimped at the projection in the bump foil sheet (17) engaged to the cut in the top foil sheet (18) to form the top and bottom sub-assembles (3, 4), the bump foil secured with predetermined spacial arrangement comprises a trapezoidal regions (19, 20) with a specific start as inner foil strip and end circumferential point and secured with an outer integrated ring (11) on bump foil sheet (13), the bump foil segments (10) & (12) includes a plurality of single bumps arranged in multiple rows strips (13) which are spaced radially apart , with the stiffness of each single strip is varied radially from inner diameter (D1) to the outer diameter (D2), and circumferentially in each trapezoidal arrangement, in which the carrier plate (1,2) along with either side sub-assemblies are interconnected through connecting units, thereby the air foil thrust bearing assembly configured for high-speed rotating system.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the spacer plate is placed annularly around the rotating thrust runner and configured to provide axial clearance flexibility control in the rotor system.

In an aspect of the present invention, in the air foil thrust bearing assembly (100) the spacer comprises cooling flow passages (16) to thermally manage the thrust runner and bearing temperatures.

In an aspect of the present invention, in the air foil thrust bearing assembly (100) radially outward direction from inner (D1) to outer diameter (D2), the stiffness of each radially located bump strip (13) is increased up to 80% of the bearing diameter and then reduced in the remaining radial portion.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the stiffness of the nominal diameter (Mean diameter Dm) region is considered the highest. With respect to Dm the stiffness is decreased by 30 – 40% in the diameter lesser than Dm inner strips and on the other hand the stiffness is reduced by 10 – 15% on the diameter greater than the Dm outer strips.

In an aspect of the present invention, in the air foil thrust bearing assembly (100) the continuous air film wedge by the bump offset placements and fixations of top and bump foils enhances functionality in clamping, load capacity and thermal management.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the leading edge (9f, 11f) of the top foil is fixed and the trailing edge (9t, 11t) is free in the direction of rotation in each segment.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the leading edge of the bump foil is free (12L, 10L) and the trailing edge (12f, 10f) is fixed with respect to the direction of rotation.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the spacer plate (5) secured with cooling channels arranged in specific gap proportional, the ratio by volume of the cooling channels on the spacer plate is in the range of 30-40%.

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the 360° plurality of top and bump foil segments (3,4) are held together by an outer integrated ring (15) that comprises dowel insert (14) and clamps the bearing between the carrier plates (1, 2) and the spacer plate (5).

In an aspect of the present invention, in the air foil thrust bearing assembly (100), the two carrier plates (1) & (2), two sub –assembly foils (3) & (4), and spacer plate (5) are connected by dowel pins (07) configured to constrain them from rotation and align axially on either sides of thrust runner (06).

In an aspect of the present invention, in the air foil thrust bearing assembly (100), multiple rows strips (13) which are spaced radially apart comprises 13a, 13b and 13c with bumps in each row varying in number and are offset to the orientation in comparison to the next row.

Additionally, in another aspect the present invention also discloses a method of operation of air foil thrust bearing assembly, comprises
a) rotating a thrust runner disc in an anti-clockwise or clock-wise direction, creating an air film by developing an air film pressure in air film, wherein the air film pressure carries the axial load in rotating system;
b) varying the number of trapezoidal pads in a thrust bearing according to the load capacity requirement,
c) establishing a frictional contact between a top foil and the surfaces of the thrust runner below the lift-off speed during startup,
d) applying a hard coating to the rotation surface of the thrust runner and applying a soft coating to the top foil.
e) employing the thrust runner disc housed by spacer plate enhances to operate at both high speeds and high temperatures.

In another aspect, a method of operation of air foil thrust bearing assembly of the present invention, the hard coating on thrust runner is diamond-like carbon (DLC) or equivalent hard coats.

In another aspect, a method of operation of air foil thrust bearing assembly of the present invention, the soft coating applied on the top foil is selected from MoS2 or Teflon coating like polytetrafluoroethylene (PTFE) or equivalent coats.

BRIEF DESCRIPTION OF DRAWINGS

Figure: 1 illustrates the exploded view of Air foil thrust bearing assembly of the present invention.

Figure: 2 illustrates the Dm region of the bump foil of the present invention.

Figure 3: illustrates the top foil of the bottom sub assembly (11) depicting free or trail end (11t) and fixed end (11f) and the trapezoidal region (22)

Figure 4 illustrates the bottom sub assembly, according to embodiments of the present invention.

Figure 5 illustrates the bump foil of the top sub assembly according to embodiments of the present invention and illustrates the (13) multiple tubular rows (13a, 13b, 13c) in bump foil strips according to embodiments of the present invention.

Figure 6 illustrates the sub assembly of bump foil incorporated with top foil of the axial air foil thrust bearing of the present invention.

Figure 7: illustrates the flow of thrust runner of axial air foil thrust bearing of the present invention.

REFERENCE NUMERALS:
Reference numerals for different part numbers of axial air foil thrust bearing assembly of the present invention:

S. No PART NAME PART NUMBER
1. Top carrier plates (1)
2. Bottom carrier plate (2)
3. Top sub assembly of foils (3)
4. Bottom sub assembly of foils (4)
5. Spacer plate with cooling channels (5)
6. Thrust runner (6)
7. Dowel pins (7)
8. Screws (8)
9. Top foil of top sub assembly (9)
10. Fixed end of top foil of top sub assembly (9f)
11. Bump foil sheet of top assembly (10)
12. Fixed end of bump foil sheet of top assembly (10f)
13. Top foil of bottom sub assembly (11)
14. Fixed end of top foil of bottom sub assembly (11f)
15. Free end of the trail end of the bottom sub assembly (11t)
16. Bump foil sheet of bottom assembly (12)
17. Fixed end of bump foil sheet of bottom assembly (12f)
18. Free end of the bump foil sheet of the bottom assembly. (12L)
19. Multiple tubular rows in bump foil strips of the top and bottom sub assembly with 13a the circumferentially towards center, followed by 13b the second row of tubular row on the bump foil and 13c, towards the outer circumference. (13)
20. Dowel inserts (14)
21. Outer integrated ring segment of the bump and top foils of top and bottom assemblies (15)
22. Cooling flow passages in the spacer (16)
23. Projection in the bump foil sheet (17)
24. Cut in the top foil sheet (18)
25. Trapezoidal region of the bump foil of top sub assembly (19)
26. Trapezoidal region of the bump foil of bottom sub assembly (20)
27. Trapezoidal region of the top foil of top sub assembly (21)
28. Trapezoidal region of the top foil of top sub assembly (22)

DETAILED DESCRIPTION OF THE INVENTION:
The present invention as embodied by an “AN AIR FOIL THRUST BEARING FOR HIGH-SPEED ROTATING MACHINES AND OPERATION METHOD THEREOF” succinctly fulfills the above-mentioned need[s] in the art. The present invention has objective[s] arising as a result of the above-mentioned need[s], said objective[s] being enumerated below. In as much as the objective[s] of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective[s] are not exhaustive of the present invention in its entirety and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative[s] and/or any functional equivalent[s] even though, such structural alternative[s] and/or any functional equivalent[s] are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation[s]/modification[s] applied to the structural alternative[s]/functional alternative[s] within its scope and purview. The present invention may be embodied in other specific form[s] without departing from the essential attributes thereof.

Throughout this specification, the use of the word "comprises" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.

The present invention discloses an air foil thrust bearing assembly.
The cluster of the bearing is designed for ease of manufacturability, assembly and functionality. The bearing is configured such that the circumferential & radial stiffness’s are managed to have larger effective & active bearing area. The design encourages a continuous air film wedge by the bump placements and fixations of top and bump foils. Also, the present invention provides features capable of having flexibility incorporated in the foils to accommodate rotating runner deformation and/or assembly related inclinations.

Air foil thrust bearings (AFBs) are self-acting hydrodynamic complaint bearings, which typically use ambient air or gas as lubricants. When compared with traditional oil bearings and rolling bearings, AFBs have obvious advantages such as high reliability, extremely low friction during steady operation and excellent ability to operate at both high speeds and high temperatures. Therefore, AFBs have broad application prospects in oil-free turbomachinery. Until recently, they were widely used in high speed and light-load turbomachinery, such as aircraft air cycle machines, compressors, and gas turbines.

As illustrated in the figure 7, its clearly depicts the operation of the axial air foil thrust bearing. In which thrust runner disc rotates in anti-clockwise direction thereby air film is developed. The developed air film pressure carries the axial load in the rotating system. The number of trapezoidal pads in the thrust bearing can be varied according to the load capacity requirement.

A frictional contact occurs between the top foil and the thrust runner surfaces at startup, below the lift-off speed. In general, hard coatings such as DLC (diamond-like carbon) are applied to the rotation surface of the thrust runner, while soft coatings such as MoS2 or Teflon coatings such as PTFE are applied to the top foil.

Description:
Axial Air Foil Bearing Assembly:
The axial air foil bearing assembly employed to support high-speed rotating system thrust loads. It consists of major five components such as two or more carrier plates (1) & (2), two or more sub-assembly foils (3) & (4), and a spacer plate (5). These components are connected, constrained from rotating, and axially aligned on either side of the thrust runner (6) using dowel pins (7). The entire assembly is then connected to the external mounting housings using screws (8). The two stationary carrier plates (1,2) host the compliant foil sub-assembly (3) & (4), positioned on opposite sides of the rotating runner (6). The sub-assemblies of top foil (9) & (11) & bump foil (10) & (12) are mounted on each carrier plate (1,2) and separated by a spacer plate (05).

Both the top foil and bump foil comprises trapezoidal region with a specific start and end circumferential point that constitute a bearing segment. The bump foil constitutes the bottom layer closer to the carrier plate at and the top foil stays above the bump foil. A plurality of such segments make-up for the thrust bearing, and these plural segments are all integral to the sub-assembly. A single piece 360-degree top foil sheet (9) & (11) and 360-degree bump foil sheet (10) & (12) are crimped using the projection in the bump foil sheet (17) which is assembled to the cut in the top foil sheet (18) to form the sub-assembly. As illustrated in figure 01, (19) Trapezoidal region of the bump foil of top sub assembly, (20) Trapezoidal region of the bump foil of bottom sub assembly, (21) Trapezoidal region of the top foil of top sub assembly, (22) From the figure 3, it is clearly inferred that the trapezoidal region of the top foil of top sub assembly. Further the bump foil segment (10) & (12) includes a plurality of single bumps on the trapezoidal region (19, 20) of the arranged in multiple rows called strips (13) which are spaced radially apart from each other. The stiffness of each single strip is varied radially from inner diameter (D1) to the outer diameter (D2). The spacing of the bumps in each radially located foil strip (13) relative to the next radially outward strip is varied non-uniformly to be not in a single radial line to avoid top foil sagging and film degradation, thereby enhancing load capacity. The bumps in the Mean diameter Dm strip area is offset by 40 - 50% of the bump pitch relative to the inner and the outer strips. For eg: In reference to figure 7, the bumps in Dm area i.e. 13 b are offset by 40-50% compared to 13a region inner to Dm and to 13b region outer to Dm in radially outward direction. It is the Dm region on which maximum load acts during operation of the system.

Bump Foil Segment:
The bump foil segment (03) & (04) are an integral part of the sub-assembly and consists of multiple rows of single bumps arranged in strips (13). These bumps are spaced radially apart and have varying stiffness from the inner diameter (D1) to the outer diameter (D2).

Non-Uniform Bump Spacing:
It is another major component of the present invention. To prevent top foil sagging and film degradation, the spacing of bumps in each radially located foil strip (13) is varied non-uniformly, avoiding a single radial line. The bumps (13b) in the mean diameter (Dm) strip area are offset by 40-50% of the bump pitch relative to the inner (13a) and outer strips (13b).

Slip-Friction Damping:
The fixed end of the bump foil (10) & (12) and top foil (9) & (11) are placed at opposite ends of the segment to enhance slip-friction damping, thereby increasing the load capacity in the rotating direction. 11t is the trail end and 11f is the free end of the top foil and comprises the trapezoidal region (22)

Foil Edge Configuration:
From the figures 1,3,4,5 it is clearly inferred that the
The leading edge of the top foil is fixed, while the trailing edge is free in the direction of rotation in each segment. In reference to Figure 1, the leading edge (9f, 11f) of the top foil is fixed and the trailing edge (9t, 11t) is free in the direction of rotation in each segment and the leading edge of the bump foil is free (12L, 10L) and the trailing edge (12f, 10f) is fixed with respect to the direction of rotation. Here, in reference to figure 3 is the crimped sub assembly, the top foil and bump foil the free and the fixed end or the leading and trailing ends are oriented in opposite direction. In reference to figure 1, 10f is fixed and 10L is free end, is opposite in orientation to the 9f and 9t of top foil of the top sub assemble, 03.

Radial Stiffness Variation:
The stiffness of each radially located bump strip (13) increases from the inner (D1) to the outer diameter (D2), up to 80% of the bearing diameter, i.e the stiffness is high. Beyond that, the stiffness is reduced in the remaining radial portion. The stiffness of the nominal diameter (Mean Diameter Dm) region is the highest (Figure 2). The stiffness is decreased by 30-40% in the diameter lesser than Dm inner strips (13a region of figure 6), and by 10-15% in the diameter greater than the Dm outer strips (13c of figure 6).

Inner Most Strip Width:
The width of the radially innermost strip (13) is higher than the remaining strips.

Spacer:
Spacer (5) provides axial clearance flexibility control in the rotor system, also it includes the provisions for cooling slow passages (16) to thermally manage the thrust runner and bearing temperatures. The cooling passages can be customized according to the temperature requirement.

Outer integrated ring (15)
As illustrated in Figure 1, the 360° plurality of top and bump foil segments are held together by an outer integrated ring (15) which is also used for clamping the bearing between the carrier plate (1,2) and the spacer plate (05). This outer ring also has the provision for the dowel insertion (14).

Connecting units:
The connecting units comprises of dowel pins (07) and screws (08). Dowel pins (7) are used to prevent the sub-assembly rotation & keep proper alignment of sub-assembly (3) & (4) with carrier plates (1) & (2) together.

WORKING EXAMPLE:
The operation method of the axial air foil thrust bearing of the present invention is applied in a turbine driven or electrically driven compressor where the thrust runner disc is rotated clockwise, creating an air film pressure between the thrust runner and trapezoidal pads within the thrust bearing assembly. The number of trapezoidal pads is adjusted based on the varying load requirements of the turbine, allowing for optimal load management. During startup, the top foil establishes frictional contact with the thrust runner surfaces below the lift-off speed, facilitated by the specific coatings applied - a hard coating on the thrust runner's rotation surface and a soft coating on the top foil. The thrust runner disc, housed by a spacer plate, allows the assembly to function efficiently at high speeds and temperatures commonly experienced in turbine operations.

In preferred embodiment, the present invention discloses an air foil thrust bearing assembly (100), comprising:
a) two or more carrier plates (1) and (2);
b) two or more sub-assembly foils comprising top sub assembly (3) comprising a top foil (9) and bump foil (10), a bottom sub assembly (4) comprising a top foil (11) and bottom bump foil (12);
c) a spacer plate (5) ;
d) a rotating runner or thrust runner (6) ;
e) connecting units (7) comprising of dowel pins (7) and screws (8);
f) dowel insertion port (14);
g) outer integrated ring (15);
h) cooling flow passages (16);
in which the two or more carrier plates (1,2) configured to remain stationary, host the two foil sub assemblies (3, 4), aligned in opposite sides of the rotating runner (6), separated by spacer (5), and connected to external mounting housings by screws (8), in which the foil sub-assembly comprises;
a single piece 360-degree top foil sheet (9) & (11) and 360-degree bump foil sheet (10) & (12) (10,12), crimped at the projection in the bump foil sheet (17) engaged to the cut in the top foil sheet (18) to form the top and bottom sub-assembles (3, 4)., the bump foil secured with predetermined spacial arrangement comprises a trapezoidal regions (19, 20) with a specific start as inner foil strip and end circumferential point and secured with an outer integrated ring (11) on bump foil sheet (13), the bump foil segments (10) & (12) includes a plurality of single bumps arranged in multiple rows strips (13) which are spaced radially apart , with the stiffness of each single strip is varied radially from inner diameter (D1) to the outer diameter (D2), and circumferentially in each trapezoidal arrangement, wherein the carrier plate (1,2) along with either side sub-assemblies are interconnected through connecting units, thereby the air foil thrust bearing assembly configured for high-speed rotating system

In accordance with the present invention, the spacer plate is placed annularly around the rotating thrust runner and configured to provide axial clearance flexibility control in the full rotor system.
In an exemplary embodiment of the present invention, the bump foil segments (10) & (12) includes a plurality of single bumps arranged in multiple rows strips (13) which are spaced radially apart as 13a towards the center, 13b is the median row of the tubular rows and 13c is the outermost row comprising the bumps of the bump foil.

In an another exemplary embodiment of the present invention, Further, the number of bumps on the 13a, 13b, and 13c. The arrangement is such that the orientation of bumps in 13a is offset to arrangement in 13b and 13c.

As per the invention, the spacer comprises cooling flow passages (16) to thermally manage the thrust runner and bearing temperatures.

In accordance with the present invention, the radially outward direction from inner (D1) to outer diameter (D2), the stiffness of each radially located bump strip (13) is increased up to 80% of the bearing diameter and then reduced in the remaining radial portion.

As per the invention, the stiffness of the nominal diameter (Mean diameter Dm) region is considered the highest. With respect to Dm the stiffness is decreased by 30 – 40% in the diameter lesser than Dm inner strips and on the other hand the stiffness is reduced by 10 – 15% on the diameter greater than the Dm outer strips.

In accordance with the present invention, the continuous air film wedge by the bump offset placements and fixations of top and bump foils enhances functionality in thermal management.

As per the invention, the leading edge (9f, 11f) of the top foil is fixed and the trailing edge (9t, 11t) is free in the direction of rotation in each segment.

In accordance with the present invention, the leading edge of the bump foil is free (12L, 10L) and the trailing edge (12f, 10f) is fixed with respect to the direction of rotation.

As per the invention, the spacer plate (5) secured with cooling channels arranged in specific gap proportional, the ratio by volume of the cooling channels on the spacer plate is in the range of 30-40%.

In accordance with the present invention, the 360° plurality of top and bump foil segments (3,4) are held together by an outer integrated ring (15) that comprises dowel insert (14) and clamps the bearing between the carrier plates (1, 2) and the spacer plate (5).

As per the invention, the two carrier plates (1) & (2), two sub –assembly foils (3) & (4), and spacer plate (5) are connected by dowel pins (07) configured to constrain them from rotation and align axially on either sides of thrust runner (06).

In another preferred embodiment, the present invention discloses a method of operation of air foil thrust bearing assembly, comprises
a) rotating a thrust runner disc in an anti-clockwise or clockwise direction, creating an air film by developing an air film pressure in air film, wherein the air film pressure carries the axial load in rotating system;
b) varying the number of trapezoidal pads in a thrust bearing according to the load capacity requirement,
c) establishing a frictional contact between a top foil and the surfaces of the thrust runner below the lift-off speed during startup,
d) applying a hard coating to the rotation surface of the thrust runner and applying a soft coating to the top foil.
e) employing the thrust runner disc housed by spacer plate enhances to operate at both high speeds and high temperatures.

In accordance with the present invention, the hard coating on thrust runner is diamond-like carbon (DLC) or equivalent.

In accordance with the present invention, the thrust runner disc housed by spacer plate works at high speeds in a range beyond 120krpm and temperatures lower than 150 deg C

As per the invention, the soft coating applied on the top foil is selected from Mos2 or Teflon coating like polytetrafluoroethylene (PTFE) or equivalent.

Advantages of the present invention:
The axial air foil thrust bearing of the present invention enhances the ease of manufacturability, assembly, and enhanced functionality.
The present invention axial air foil bearing is configured such that the circumferential & radial stiffness’s are managed to have larger effective & active bearing area. The design encourages a continuous air film wedge by the bump placements and fixations of top and bump foils. Also, the present invention provides features capable of having flexibility incorporated in the foils to accommodate rotating runner deformation and/or assembly related inclinations.
The foregoing description and drawings merely explain and illustrate the invention and the invention is not limited thereto except insofar as the amended claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.

, Claims:WE CLAIM:

1. An air foil thrust bearing assembly (100), comprising:
a) two or more carrier plates (1) and (2);
b) two or more sub-assembly foils comprising top sub assembly (3) comprising a top foil (9) and bump foil (10), a bottom sub assembly (4) comprising a top foil (11) and bottom bump foil (12);
c) a spacer plate (5) ;
d) a rotating runner or thrust runner (6) ;
e) connecting units (7) comprising of dowel pins (7) and screws (8);
f) dowel insertion port (14);
g) outer integrated ring (15);
h) cooling flow passages (16);
wherein the two or more carrier plates (1,2) configured to remain stationary, host the two foil sub assemblies (3, 4), aligned in opposite sides of the rotating runner (6), separated by spacer (5), and connected to external mounting housings by screws (8), wherein the foil sub-assembly comprises;
a single piece 360-degree top foil sheet (9) & (11) and 360-degree bump foil sheet (10) & (12) (10,12), crimped at the projection in the bump foil sheet (17) engaged to the cut in the top foil sheet (18) to form the top and bottom sub-assembles (3, 4)., the bump foil secured with predetermined spacial arrangement comprises a trapezoidal regions (19, 20) with a specific start as inner foil strip and end circumferential point and secured with an outer integrated ring (11) on bump foil sheet (13), the bump foil segments (10) & (12) includes a plurality of single bumps arranged in multiple rows strips (13) which are spaced radially apart , with the stiffness of each single strip is varied radially from inner diameter (D1) to the outer diameter (D2), and circumferentially in each trapezoidal arrangement, wherein the carrier plate (1,2) along with either side sub-assemblies are interconnected through connecting units, thereby the air foil thrust bearing assembly configured for high-speed rotating system

2. The air foil thrust bearing assembly (100) as claimed in claim 1, wherein spacer plate is placed annularly around the rotating thrust runner and configured to provide axial clearance flexibility control in the rotor system.

3. The air foil thrust bearing assembly (100) as claimed in claim 2, wherein the spacer comprises cooling flow passages (16) to thermally manage the thrust runner and bearing temperatures.

4. The air foil thrust bearing assembly (100) as claimed in claim 1, wherein in radially outward direction from inner (D1) to outer diameter (D2), the stiffness of each radially located bump strip (13) is increased up to 80% of the bearing diameter and then reduced in the remaining radial portion.

5. The air foil thrust bearing assembly (100) as claimed in claim 1, wherein the stiffness of the nominal diameter (Mean diameter Dm) region is considered the highest. With respect to Dm the stiffness is decreased by 30 – 40% in the diameter lesser than Dm inner strips and on the other hand the stiffness is reduced by 10 – 15% on the diameter greater than the Dm outer strips.

6. The air foil thrust bearing assembly as claimed in claim 1, wherein the continuous air film wedge by the bump offset placements and fixations of top and bump foils enhances functionality in clamping, load capacity and thermal management.

7. The air foil thrust bearing assembly (100) as claimed in claim 1, wherein the leading edge (9f, 11f) of the top foil is fixed and the trailing edge (9t, 11t) is free in the direction of rotation in each segment.

8. The air foil thrust bearing assembly (100) as claimed in claim 1, wherein the leading edge of the bump foil is free (12L, 10L) and the trailing edge (12f, 10f) is fixed with respect to the direction of rotation.

9. The air foil thrust bearing assembly as claimed in claim 1, wherein the spacer plate (5) secured with cooling channels arranged in specific gap proportional, the ratio by volume of the cooling channels on the spacer plate is in the range of 30-40%.

10. The air foil thrust bearing assembly as claimed in claim 1, wherein the 360° plurality of top and bump foil segments (3,4) are held together by an outer integrated ring (15) that comprises dowel insert (14) and clamps the bearing between the carrier plates (1, 2) and the spacer plate (5).

11. The air foil thrust bearing assembly as claimed in claim 1, wherein the two carrier plates (1) & (2), two sub –assembly foils (3) & (4), and spacer plate (5) are connected by dowel pins (07) configured to constrain them from rotation and align axially on either sides of thrust runner (06).

12. The air foil thrust bearing assembly as claimed in claim 1, wherein multiple rows strips (13) which are spaced radially apart comprises 13a, 13b and 13c with bumps in each row varying in number and are offset to the orientation in comparison to the next row.

13. A method of operation of air foil thrust bearing assembly, comprises
f) rotating a thrust runner disc in an anti-clockwise or clock-wise direction, creating an air film by developing an air film pressure in air film, wherein the air film pressure carries the axial load in rotating system;
g) varying the number of trapezoidal pads in a thrust bearing according to the load capacity requirement,
h) establishing a frictional contact between a top foil and the surfaces of the thrust runner below the lift-off speed during startup,
i) applying a hard coating to the rotation surface of the thrust runner and applying a soft coating to the top foil.
j) employing the thrust runner disc housed by spacer plate enhances to operate at both high speeds and high temperatures.

14. The method of operation of air foil thrust bearing assembly as claimed in claim 13, wherein the hard coating on thrust runner is diamond-like carbon (DLC) or equivalent hard coats.

15. The method of operation of air foil thrust bearing assembly as claimed in claim 13, the soft coating applied on the top foil is selected from MoS2 or Teflon coating like polytetrafluoroethylene (PTFE) or equivalent coats.

Dated this 22nd day of January 2024 -SD-
Kalyanchand Jhabakh (IN/PA-830)
Agent for Applicant